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Sample records for ahp time constant

  1. Afterhyperpolarization (AHP) regulates the frequency and timing of action potentials in the mitral cells of the olfactory bulb: role of olfactory experience

    PubMed Central

    Duménieu, Maël; Fourcaud-Trocmé, Nicolas; Garcia, Samuel; Kuczewski, Nicola

    2015-01-01

    Afterhyperpolarization (AHP) is a principal feedback mechanism in the control of the frequency and patterning of neuronal firing. In principal projection neurons of the olfactory bulb, the mitral cells (MCs), the AHP is produced by three separate components: classical potassium-mediated hyperpolarization, and the excitatory and inhibitory components, which are generated by the recurrent dendrodendritic synaptic transmission. Precise spike timing is involved in olfactory coding and learning, as well as in the appearance of population oscillatory activity. However, the contribution of the AHP and its components to these processes remains unknown. In this study, we demonstrate that the AHP is developed with the MC firing frequency and is dominated by the potassium component. We also show that recurrent synaptic transmission significantly modifies MC AHP and that the strength of the hyperpolarization produced by the AHP in the few milliseconds preceding the action potential (AP) emission determines MC firing frequency and AP timing. Moreover, we show that the AHP area is larger in younger animals, possibly owing to increased Ca2+ influx during MC firing. Finally, we show that olfactory experience selectively reduces the early component of the MC AHP (under 25 msec), thus producing a modification of the AP timing limited to the higher firing frequency. On the basis of these results, we propose that the AHP, and its susceptibility to be selectively modulated by the recurrent synaptic transmission and olfactory experience, participate in odor coding and learning by modifying the frequency and pattern of MC firing. PMID:26019289

  2. Redox chemistry of Mycobacterium tuberculosis alkylhydroperoxide reductase E (AhpE): Structural and mechanistic insight into a mycoredoxin-1 independent reductive pathway of AhpE via mycothiol.

    PubMed

    Kumar, Arvind; Balakrishna, Asha Manikkoth; Nartey, Wilson; Manimekalai, Malathy Sony Subramanian; Grüber, Gerhard

    2016-08-01

    Mycobacterium tuberculosis (Mtb) has the ability to persist within the human host for a long time in a dormant stage and re-merges when the immune system is compromised. The pathogenic bacterium employs an elaborate antioxidant defence machinery composed of the mycothiol- and thioredoxin system in addition to a superoxide dismutase, a catalase, and peroxiredoxins (Prxs). Among the family of Peroxiredoxins, Mtb expresses a 1-cysteine peroxiredoxin, known as alkylhydroperoxide reductase E (MtAhpE), and defined as a potential tuberculosis drug target. The reduced MtAhpE (MtAhpE-SH) scavenges peroxides to become converted to MtAhpE-SOH. To provide continuous availability of MtAhpE-SH, MtAhpE-SOH has to become reduced. Here, we used NMR spectroscopy to delineate the reduced (MtAhpE-SH), sulphenic (MtAhpE-SOH) and sulphinic (MtAhpE-SO2H) states of MtAhpE through cysteinyl-labelling, and provide for the first time evidence of a mycothiol-dependent mechanism of MtAhpE reduction. This is confirmed by crystallographic studies, wherein MtAhpE was crystallized in the presence of mycothiol and the structure was solved at 2.43Å resolution. Combined with NMR-studies, the crystallographic structures reveal conformational changes of important residues during the catalytic cycle of MtAhpE. In addition, alterations of the overall protein in solution due to redox modulation are observed by small angle X-ray scattering (SAXS) studies. Finally, by employing SAXS and dynamic light scattering, insight is provided into the most probable physiological oligomeric state of MtAhpE necessary for activity, being also discussed in the context of concerted substrate binding inside the dimeric MtAhpE. PMID:27417938

  3. Unified Technical Concepts. Module 12: Time Constants.

    ERIC Educational Resources Information Center

    Technical Education Research Center, Waco, TX.

    This concept module on time constants is one of thirteen modules that provide a flexible, laboratory-based physics instructional package designed to meet the specialized needs of students in two-year, postsecondary technical schools. Each of the thirteen concept modules discusses a single physics concept and how it is applied to each energy…

  4. 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.).

  5. Newman-Penrose constants of stationary electrovacuum space-times

    SciTech Connect

    Zhang Xiangdong; Gao Sijie; Wu Xiaoning

    2009-05-15

    A theorem related to the Newman-Penrose constants is proven. The theorem states that all the Newman-Penrose constants of asymptotically flat, stationary, asymptotically algebraically special electrovacuum space-times are zero. Straightforward application of this theorem shows that all the Newman-Penrose constants of the Kerr-Newman space-time must vanish.

  6. 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…

  7. Kaluza-Klein Bulk Viscous Cosmological Model with Time Dependent Gravitational Constant and Cosmological Constant

    NASA Astrophysics Data System (ADS)

    Jain, Namrata I.; Bhoga, Shyamsunder S.

    2015-08-01

    Cosmological models with time varying gravitational constant G and cosmological constant Λ in the presence of viscous fluid in Kaluza-Klein metric were investigated. The solutions to Einstein Field Equation were obtained for different types of G, with bulk coefficient ξ = ξ 0 ρ d (where ρ is density of the Universe, d is some constant) and lambda Λ = α H 2 + β R -2 where H and R are Hubble parameter and scale factor respectively. Two possible models are suggested, one where G is proportional to H and, the other where G is inversely proportional to H. While the former leads to a non-singular model, the latter results in an inflationary model. Both Cosmological models show that the Universe is accelerating; but at the early stage of the Universe the behaviour of both models is quite different,which has been studied through the variation of decelerating parameter q with time.

  8. 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.

  9. 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.

  10. Single time point isothermal drug stability experiments at constant humidity.

    PubMed

    Tao, Jian-Lin; Zhan, Xian-Cheng; Li, Lin-Li; Lin, Bing; Jiang, Lu

    2009-03-01

    A single time point isothermal drug stability experiments at constant humidity is introduced. In the new method, kinetic parameters related to both moisture and temperature were obtained by a single pair of experiments: these related to moisture by one with a group of testing humidities and a fixed temperature, those related to temperature by the other with a group of testing temperatures and a constant humidity. By a simulation, the estimates for the kinetic parameters (E(a), m, A) obtained by the proposed method and the reported programmed humidifying and heating method were statistically evaluated and were compared with those obtained by the isothermal measurements at constant humidity. Results indicated that under the same experimental conditions, the estimates obtained by the proposed method were significantly more precise than those obtained by the reported programmed humidifying and heating method. The estimates obtained by the isothermal method at constant humidity were somewhat more precise than those obtained by the proposed method. However, the experimental period needed by the isothermal method at constant humidity was greatly longer than that needed by the proposed method. The stability of dicloxacillin sodium, as a solid state model, was investigated by the single time point isothermal drug stability experiments at constant humidity. The results indicated that the kinetic parameters obtained by the proposed method were comparable to those from the reported. PMID:19252391

  11. 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.

  12. 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.

  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. Use of Constant Time Delay and Attentional Responses with Adolescents.

    ERIC Educational Resources Information Center

    Wolery, Mark; And Others

    1991-01-01

    This study examined effectiveness of a constant time delay (CTD) procedure in teaching social studies and health facts to five adolescents with learning or behavioral disorders. Students were given praise with and without additional information. Results indicated CTD procedures were reliable and effective, and students acquired nontargeted as well…

  15. 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.

  16. Cerebrovascular Time Constant in Patients with Head Injury.

    PubMed

    Trofimov, Alex; Kalentiev, George; Gribkov, Alexander; Voennov, Oleg; Grigoryeva, Vera

    2016-01-01

    The cerebrovascular time constant (τ) theoretically estimates how fast the cerebral arterial bed is filled by blood volume after a sudden change in arterial blood pressure during one cardiac cycle. The aim of this study was to assess the time constant of the cerebral arterial bed in patients with traumatic brain injury (TBI) with and without intracranial hematomas (IH). We examined 116 patients with severe TBI (mean 35 ± 15 years, 61 men, 55 women). The first group included 58 patients without IH and the second group included 58 patients with epidural (7), subdural (48), and multiple (3) hematomas. Perfusion computed tomography (PCT) was performed 1-12 days after TBI in the first group and 2-8 days after surgical evacuation of the hematoma in the second group. Arteriovenous amplitude of regional cerebral blood volume oscillation was calculated as the difference between arterial and venous blood volume in the "region of interest" of 1 cm(2). Mean arterial pressure was measured and the flow rate of the middle cerebral artery was recorded with transcranial Doppler ultrasound after PCT. The time constant was calculated by the formula modified by Kasprowicz. The τ was shorter (p = 0.05) in both groups 1 and 2 in comparison with normal data. The time constant in group 2 was shorter than in group 1, both on the side of the former hematoma (р = 0.012) and on the contralateral side (р = 0.044). The results indicate failure of autoregulation of cerebral capillary blood flow in severe TBI, which increases in patients with polytrauma and traumatic IH. PMID:26463964

  17. Fluorescence decay-time constants in organic liquid scintillators

    SciTech Connect

    Marrodan Undagoitia, T.; Feilitzsch, F. von; Oberauer, L.; Potzel, W.; Ulrich, A.; Winter, J.; Wurm, M.

    2009-04-15

    The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector Low Energy Neutrino Astronomy (LENA). In particular, the impact of the measured values to the search for proton decay via p{yields}K{sup +}{nu} is evaluated in this work.

  18. THE HUBBLE CONSTANT INFERRED FROM 18 TIME-DELAY LENSES

    SciTech Connect

    Paraficz, Danuta; Hjorth, Jens

    2010-04-01

    We present a simultaneous analysis of 18 galaxy lenses with time-delay measurements. For each lens, we derive mass maps using pixelated simultaneous modeling with shared Hubble constant. We estimate the Hubble constant to be 66{sup +6}{sub -4} km s{sup -1} Mpc{sup -1} (for a flat universe with OMEGA{sub m} = 0.3, OMEGA{sub L}AMBDA = 0.7). We have also selected a subsample of five relatively isolated early-type galaxies, and by simultaneous modeling with an additional constraint on isothermality of their mass profiles, we get H{sub 0} = 76{sup +3}{sub -3} km s{sup -1} Mpc{sup -1}.

  19. Roles of Alkyl Hydroperoxide Reductase Subunit C (AhpC) in Viable but Nonculturable Vibrio parahaemolyticus

    PubMed Central

    Wang, Hen-Wei; Chung, Chun-Hui; Ma, Tsung-Yong

    2013-01-01

    Alkyl hydroperoxide reductase subunit C (AhpC) is the catalytic subunit responsible for the detoxification of reactive oxygen species that form in bacterial cells or are derived from the host; thus, AhpC facilitates the survival of pathogenic bacteria under environmental stresses or during infection. This study investigates the role of AhpC in the induction and maintenance of a viable but nonculturable (VBNC) state in Vibrio parahaemolyticus. In this investigation, ahpC1 (VPA1683) and ahpC2 (VP0580) were identified in chromosomes II and I of this pathogen, respectively. Mutants with deletions of these two ahpC genes and their complementary strains were constructed from the parent strain KX-V231. The growth of these strains was monitored on tryptic soy agar–3% NaCl in the presence of the extrinsic peroxides H2O2 and tert-butyl hydroperoxide (t-BOOH) at different incubation temperatures. The results revealed that both ahpC genes were protective against t-BOOH, while ahpC1 was protective against H2O2. The protective function of ahpC2 at 4°C was higher than that of ahpC1. The times required to induce the VBNC state (4.7 weeks) at 4°C in a modified Morita mineral salt solution with 0.5% NaCl and then to maintain the VBNC state (4.7 weeks) in an ahpC2 mutant and an ahpC1 ahpC2 double mutant were significantly shorter than those for the parent strain (for induction, 6.2 weeks; for maintenance, 7.8 weeks) and the ahpC1 mutant (for induction, 6.0 weeks; for maintenance, 8.0 weeks) (P < 0.03). Complementation with an ahpC2 gene reversed the effects of the ahpC2 mutation in shortening the times for induction and maintenance of the VBNC state. This investigation identified the different functions of the two ahpC genes and confirmed the particular role of ahpC2 in the VBNC state of V. parahaemolyticus. PMID:23563952

  20. Advanced Hydrologic Prediction Services (AHPS) Science Infusion Strategy

    NASA Astrophysics Data System (ADS)

    Schaake, J.; Smith, G.; Carter, G.

    2002-05-01

    NWS is implementing an Advanced Hydrologic Prediction Services (AHPS) Science initiative to meet NWS Vision 2005 goals and related hydrologic services requirements, including the goal of being a world leader using state of the art forecast science and technology. AHPS includes a science infusion strategy to meet the following objectives: extend forecast lead time, improve forecast accuracy, and provide better information for user decisions. AHPS will meet these goals by implementing hydrologic forecast models tuned to local conditions and operated to account for uncertainty in hydrologic forecasts. AHPS will use ensemble weather and climate forecasts of precipitation and other conditions, such as air temperature, that affect the forecasts. This ensemble approach to weather, climate and water forecasting will provide a probabilistic basis for AHPS forecast products. Meeting AHPS goals and objectives requires an infusion of new science into the existing forecast system. Three AHPS requirements for science infusion are: 1. Quantify the uncertainty of river forecasts and provide users with a clear view of future hydrologic conditions together with hard evidence that AHPS products are based on valid forecast probability information; 2. Reduce the space and time scale, improve the accuracy, and extend the lead time of hydrologic forecasts. Demonstrate that new improvements to hydrologic forecast procedures add value to the forecasts and meet user requirements; 3. Improve the ability of forecasters to use the tools provided by integrating these into an efficient operational forecast system that includes automatic techniques for data quality control, access to data, model calibration, data assimilation, processing of ensemble forecasts, verification of forecasts and monitoring of all stages of the forecast process.

  1. 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.

  2. 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.

  3. 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.

  4. Role of the Pseudomonas aeruginosa oxyR-recG Operon in Oxidative Stress Defense and DNA Repair: OxyR-Dependent Regulation of katB-ankB, ahpB, and ahpC-ahpF

    PubMed Central

    Ochsner, Urs A.; Vasil, Michael L.; Alsabbagh, Eyad; Parvatiyar, Kislay; Hassett, Daniel J.

    2000-01-01

    Pseudomonas aeruginosa possesses an extensive armament of genes involved in oxidative stress defense, including katB-ankB, ahpB, and ahpC-ahpF. Transcription of these genes was regulated in response to H2O2, paraquat, or organic peroxides. Expression of katB-lacZ and the observed KatB catalase levels in P. aeruginosa PAO1 were induced up to 250-fold after exposure to oxidative stress-generating compounds. Also, ahpB-lacZ and ahpC-lacZ expression was 90- and 3-fold higher, respectively, upon exposure to paraquat. The dose- and time-response curves revealed that 1 μM paraquat was sufficient for half-maximal activation of each reporter fusion within 5 min of exposure. Expression of these genes was not observed in a ΔoxyR mutant, indicating that OxyR was essential for this response. The transcriptional start sites of katB-ankB, ahpB, and ahpC-ahpF were mapped, putative OxyR-binding sites were identified upstream of the −35 promoter elements, and direct binding of purified OxyR protein to these target promoters was demonstrated. The oxyR mutant was hypersusceptible to oxidative stress-generating agents, including H2O2 and paraquat, in spite of total KatA catalase activity being comparable to that of the wild type. The oxyR phenotype was fully complemented by a plasmid containing the oxyR gene, while any of the katB, ahpB, or ahpCF genes alone resulted in only marginal complementation. Increased katB-lacZ expression and higher KatB catalase levels were detected in a ΔahpCF background compared to wild-type bacteria, suggesting a compensatory function for KatB in the absence of AhpCF. In P. aeruginosa, oxyR is located upstream of recG, encoding a putative DNA repair enzyme. oxyR-lacZ and recG-lacZ reporter activities and oxyR-recG mRNA analysis showed that oxyR and recG are organized in an operon and expressed constitutively with regard to oxidative stress from a single promoter upstream of oxyR. Mutants affected in recG but not oxyR were dramatically impaired in DNA

  5. 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.

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

    PubMed

    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. PMID:25416875

  7. 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.

  8. Panasonic Small Cell Testing for AHPS

    NASA Technical Reports Server (NTRS)

    Pearson, C.; Blackmore, P.; Lain, M.; Walpole, A.; Darcy, Eric

    2006-01-01

    AEA selection and successful Interim Design Review for AHPS proves maturity of small cell approach for very large batteries. Cells show excellent opportunity for battery mass reduction for AHPS and other low cycle applications. Lack of cycle and extended calendar life make EOL battery performance difficult (AHPS 8 year mission). Preliminary design, AEA retained SONY 18650HC cell as baseline: a) Well characterized performance; b) Wealth of safety test data.

  9. Influence of gas microsensor mounting technique on its temperature time constant

    NASA Astrophysics Data System (ADS)

    Maziarz, Wojciech; Pisarkiewicz, Tadeusz

    2006-10-01

    Metal oxide semiconductor gas sensors with modulated working temperature should reveal small thermal time constant in comparison to the time constants of chemical reactions between gas atmosphere and sensitive layer. In such case analyzed sensor response is dominated with specific phenomena originated from these reactions. A way the sensors are mounted has big influence on the sensor thermal time constants. In experiments authors used gas sensors with ceramic and micromachined silicon substrates glued to the case or suspended on thin wires. Although mechanical stability and durability of glued sensors are better, the lower power consumption and lower time constants are possible with sensors mounted using thin wires.

  10. 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

  11. Vector Constants of Motion for Time-Dependent Kepler and Isotropic Harmonic Oscillator Potentials

    NASA Astrophysics Data System (ADS)

    Ritter, O. M.; Santos, F. C.; Tort, A. C.

    2001-06-01

    A method of obtaining vector constants of motion for time-independent as well as time-dependent central fields is discussed. Some well-established results are rederived in this alternative way and new ones obtained.

  12. Study of a Thermophysical System with Two Time Constants Using an Open Photoacoustic Cell

    NASA Astrophysics Data System (ADS)

    Bonno, B.; Zeninari, V.; Joly, L.; Parvitte, B.

    2011-03-01

    In this paper a study of a thermophysical system with two time constants, an electronic time constant and a thermal relaxation time constant, is presented. The system under study is a thin metallic sample coupled to an open photoacoustic (PA) cell, the resulting signal being measured by a lock-in amplifier or by a data acquisition device. All operations are performed by a computer-based automatic measurement system. A time- and frequency-domain theoretical analysis of the photothermal signal is given combining the usual PA scheme to the energy balance equation of the system. The experimental results are in very good agreement with the developed theory.

  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. The Pyramid House: A ten-day thermal time constant passive solar home

    SciTech Connect

    Ellison, T.

    1999-07-01

    The Pyramid House is a passive solar home being designed and built to operate without back-up heating. Having told people this, the fear that someday the author might have to swallow his pride and seek the warmth of a neighbor's cozy wood-heated cabin has encouraged him to analyze the Pyramid House's projected winter performance. This performance is easy to visualize when described in terms of the home's thermal time constant, {tau}--an easily calculated measure of the time it takes the house to reach equilibrium with the ambient temperature. The Pyramid House obtains its long time constant using conventional insulation, and a very high degree of thermal mass via a radiant heat flooring system and water storage. After presenting the time constant concept, it is employed to analyze building materials and then the Pyramid House. The analyses show the ineffectuality of adding solar gain to homes with low time constants, such as typical US homes.

  15. Performance of fast monolithic ECL voltage comparators in constant-fraction discriminators and other timing circuits

    SciTech Connect

    Binkley, D.M.; Casey, M.E. )

    1988-02-01

    Timing errors caused by voltage comparator operation are investigated in detail for constant-fraction discriminators and other timing circuits. These errors result from changing comparator response time for input signals with different slopes (voltage/time) and different levels. Comparator response time is analyzed for a modern high-speed ECL voltage comparator using the SPICE circuit analysis program which models the complex nonlinearities present in comparator operation. The simulated response time for a -90 mV to 10 mV step input is slightly larger than the specified comparator performance indicating a conservative analysis. Response time is presented for a variety of input signals and supports a comparator response-time model that consists of a charge-sensitivity (variable-time) delay component and a fixed delay component. Finally, SPICE circuit simulation is extended to simulate comparator operation in a constant-fraction discriminator circuit.

  16. 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.

  17. 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.

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  2. Teaching Employment Skills to Adolescents with Mild and Moderate Disabilities Using a Constant Time Delay Procedure.

    ERIC Educational Resources Information Center

    Chandler, Wanda; And Others

    1993-01-01

    A five-second constant time delay procedure was used to teach three chained vocational tasks (filling a soda machine, using a duplicating machine, and using a photocopier) to four high school students with mild or moderate disabilities. All students acquired the skills with a low percentage of errors. Maintenance and generalization data were…

  3. Use of Constant Time Delay in Small Group Instruction: A Study of Observational and Incidental Learning.

    ERIC Educational Resources Information Center

    Doyle, Patricia Munson; And Others

    1990-01-01

    Constant time delay was found to be an effective strategy in teaching targeted facts to four secondary-age students with mild and moderate mental retardation. Students also learned other students' target facts through observation and learned incidental information embedded in the consequent event following correct responding. (Author/JDD)

  4. 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.

  5. 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.…

  6. Using a Constant Time Delay Procedure to Teach Aquatic Play Skills to Children with Autism

    ERIC Educational Resources Information Center

    Yilmaz, Ilker; Birkan, Bunyamin; Konukman, Ferman; Erkan, Mert

    2005-01-01

    Effects of a constant time delay procedure on aquatic play skills of children with autism was investigated. A single subject multiple probe model across behaviors with probe conditions was used. Participants were four boys, 7-9 years old. Data were collected over a 10-week period using the single opportunity method as an intervention. Results…

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Transiting planets as a precision clock to constrain the time variation of the gravitational constant

    NASA Astrophysics Data System (ADS)

    Masuda, Kento; Suto, Yasushi

    2016-06-01

    Analysis of transit times in exoplanetary systems accurately provides an instantaneous orbital period, P(t), of their member planets. A long-term monitoring of those transiting planetary systems puts limits on the variability of P(t), which are translated into the constraints on the time variation of the gravitational constant G. We apply this analysis to 10 transiting systems observed by the Kepler spacecraft, and find that ΔG/G ≲ 5 × 10- 6 for 2009-2013, or dot{G}/G ≲ 10^{-6}yr-1 if dot{G} is constant. While the derived limit is weaker than those from other analyses, it is complementary to them and can be improved by analyzing numerous transiting systems that are continuously monitored.

  16. Dividing line between quantum and classical trajectories in a measurement problem: Bohmian time constant.

    PubMed

    Nassar, Antonio B; Miret-Artés, Salvador

    2013-10-11

    This Letter proposes an answer to a challenge posed by Bell on the lack of clarity in regards to the dividing line between the quantum and classical regimes in a measurement problem. To this end, a generalized logarithmic nonlinear Schrödinger equation is proposed to describe the time evolution of a quantum dissipative system under continuous measurement. Within the Bohmian mechanics framework, a solution to this equation reveals a novel result: it displays a time constant that should represent the dividing line between the quantum and classical trajectories. It is shown that continuous measurements and damping not only disturb the particle but compel the system to converge in time to a Newtonian regime. While the width of the wave packet may reach a stationary regime, its quantum trajectories converge exponentially in time to classical trajectories. In particular, it is shown that damping tends to suppress further quantum effects on a time scale shorter than the relaxation time of the system. If the initial wave packet width is taken to be equal to 2.8×10(-15) m (the approximate size of an electron), the Bohmian time constant is found to have an upper limit, i.e., τ(Bmax)=10(-26) s. PMID:24160580

  17. 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.

  18. Limits on the Time Evolution of Space Dimensions from Newton's Constant

    NASA Astrophysics Data System (ADS)

    Nasseri, Forough

    Limits are imposed upon the possible rate of change of extra spatial dimensions in a decrumpling model Universe with time variable spatial dimensions (TVSD) by considering the time variation of (1+3)-dimensional Newton's constant. Previous studies on the time variation of (1+3)-dimensional Newton's constant in TVSD theory had not include the effects of the volume of the extra dimensions and the effects of the surface area of the unit sphere in D-space dimensions. Our main result is that the absolute value of the present rate of change of spatial dimensions to be less than about 10-14 yr-1. Our results would appear to provide a prima facie case for ruling the TVSD model out. We show that based on observational bounds on the present variation of Newton's constant, one would have to conclude that the spatial dimension of the Universe when the Universe was "at the Planck scale" to be less than or equal to 3.09. If the dimension of space when the Universe was "at the Planck scale" is constrained to be fractional and very close to 3, then the whole edifice of TVSD model loses credibility.

  19. Dissecting peroxiredoxin catalysis: separating binding, peroxidation, and resolution for a bacterial AhpC.

    PubMed

    Parsonage, Derek; Nelson, Kimberly J; Ferrer-Sueta, Gerardo; Alley, Samantha; Karplus, P Andrew; Furdui, Cristina M; Poole, Leslie B

    2015-02-24

    Peroxiredoxins make up a ubiquitous family of cysteine-dependent peroxidases that reduce hydroperoxide or peroxynitrite substrates through formation of a cysteine sulfenic acid (R-SOH) at the active site. In the 2-Cys peroxiredoxins, a second (resolving) cysteine reacts with the sulfenic acid to form a disulfide bond. For all peroxiredoxins, structural rearrangements in the vicinity of the active site cysteine(s) are necessary to allow disulfide bond formation and subsequent reductive recycling. In this study, we evaluated the rate constants for individual steps in the catalytic cycle of Salmonella typhimurium AhpC. Conserved Trp residues situated close to both peroxidatic and resolving cysteines in AhpC give rise to large changes in fluorescence during the catalytic cycle. For recycling, AhpF very efficiently reduces the AhpC disulfide, with a single discernible step and a rate constant of 2.3 × 10(7) M(-1) s(-1). Peroxide reduction was more complex and could be modeled as three steps, beginning with a reversible binding of H2O2 to the enzyme (k1 = 1.36 × 10(8) M(-1) s(-1), and k-1 = 53 s(-1)), followed by rapid sulfenic acid generation (620 s(-1)) and then rate-limiting disulfide bond formation (75 s(-1)). Using bulkier hydroperoxide substrates with higher Km values, we found that different efficiencies (kcat/Km) for turnover of AhpC with these substrates are primarily caused by their slower rates of binding. Our findings indicate that this bacterial peroxiredoxin exhibits rates for both reducing and oxidizing parts of the catalytic cycle that are among the fastest observed so far for this diverse family of enzymes. PMID:25633283

  20. 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.

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

    PubMed

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

    2001-06-01

    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. PMID:11356655

  2. 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.

  3. Constants of the motion, universal time and the Hamilton-Jacobi function in general relativity

    NASA Astrophysics Data System (ADS)

    O'Hara, Paul

    2013-04-01

    In most text books of mechanics, Newton's laws or Hamilton's equations of motion are first written down and then solved based on initial conditions to determine the constants of the motions and to describe the trajectories of the particles. In this essay, we take a different starting point. We begin with the metrics of general relativity and show how they can be used to construct by inspection constants of motion, which can then be used to write down the equations of the trajectories. This will be achieved by deriving a Hamiltonian-Jacobi function from the metric and showing that its existence requires all of the above mentioned properties. The article concludes by showing that a consistent theory of such functions also requires the need for a universal measure of time which can be identified with the "worldtime" parameter, first introduced by Steuckelberg and later developed by Horwitz and Piron.

  4. 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.

  5. 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.

  6. 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.

  7. Deuteron quadrupole coupling constants and reorientational correlation times in protic ionic liquids.

    PubMed

    Strauch, Matthias; Bonsa, Anne-Marie; Golub, Benjamin; Overbeck, Viviane; Michalik, Dirk; Paschek, Dietmar; Ludwig, Ralf

    2016-07-21

    We describe a method for the accurate determination of deuteron quadrupole coupling constants χD for N-D bonds in triethylammonium-based protic ionic liquids (PILs). This approach was first introduced by Wendt and Farrar for O-D bonds in molecular liquids, and is based on the linear relationship between the deuteron quadrupole coupling constants χD, and the proton chemical shifts δ(1)H, as obtained from DFT calculated properties in differently sized clusters of the compounds. Thus the measurement of δ(1)H provides an accurate estimate for χD, which can then be used for deriving reorientational correlation-times τND, by means of NMR deuteron quadrupole relaxation time measurements. The method is applied to pure PILs including differently strong interacting anions. The obtained χD values vary between 152 and 204 kHz, depending on the cation-anion interaction strength, intensified by H-bonding. We find that considering dispersion corrections in the DFT-calculations leads to only slightly decreasing χD values. The determined reorientational correlation times indicate that the extreme narrowing condition is fulfilled for these PILs. The τc values along with the measured viscosities provide an estimate for the volume/size of the clusters present in solution. In addition, the correlation times τc, and the H-bonded aggregates were also characterized by molecular dynamics (MD) simulations. PMID:27067640

  8. 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.

  9. 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

  10. A Time-Dependent Numerical Model for Spherically Symmetric Hailstone Growth Thermodynamics under Constant Ambient Conditions.

    NASA Astrophysics Data System (ADS)

    Lozowski, E. P.; D'Amours, R.

    1980-08-01

    A model of spherical hailstone growth thermodynamics is presented, and used to examine the validity of the continuous growth and heat balance assumptions frequently employed in the `classical' hail growth models. The model is similar to the spherically symmetric model formulated by Macklin and Payne (1969), but solutions to the model equations are obtained by means of finite-difference numerical methods. In the model, we do not try to simulate the discrete accretion process of individual drops. Instead, we attempt to identify the implications of the discrete, time-dependent nature of the icing process, by examining the accretion of a thin uniform layer of supercooled water over the entire surface of the sphere. The heat transfer equations both with the air and within the hailstone axe then solved assuming radial symmetry. By the addition of several such layers, the finite growth of a spherical hailstone can be simulated. In the present paper, only growth in constant ambient conditions is considered. It is shown that there are large internal heat fluxes during the interval between the accretion of successive layers (typically 1 s), which cause the temperatures near the surface to oscillate several degrees above and below their time-mean value. Nevertheless, the time-averaged temperature over an accretion cycle is almost uniform throughout the hailstone and, when the environmental conditions are constant, is approximately equal to the equilibrium surface temperature predicted by the `classical' models. As the hailstone grows under constant environmental conditions, it continually adapts to the classical equilibrium temperature, warming up almost uniformly throughout. The time scale for this adjustment to a quasi-equilibrium state is found to be of the order of the internal diffusive time scale R2/k. It is speculated therefore that if the environmental conditions change slowly (over time scales large compared with R2/k) the hailstone thermodynamics will be adequately

  11. 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.

  12. 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.

  13. Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography

    NASA Astrophysics Data System (ADS)

    Doebrich, Marcus; Markstaller, Klaus; Karmrodt, Jens; Kauczor, Hans-Ulrich; Eberle, Balthasar; Weiler, Norbert; Thelen, Manfred; Schreiber, Wolfgang G.

    2005-04-01

    In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs.

  14. Origin and control of the dominant time constant of salamander cone photoreceptors

    PubMed Central

    Zang, Jingjing

    2012-01-01

    Recovery of the light response in vertebrate photoreceptors requires the shutoff of both active intermediates in the phototransduction cascade: the visual pigment and the transducin–phosphodiesterase complex. Whichever intermediate quenches more slowly will dominate photoresponse recovery. In suction pipette recordings from isolated salamander ultraviolet- and blue-sensitive cones, response recovery was delayed, and the dominant time constant slowed when internal [Ca2+] was prevented from changing after a bright flash by exposure to 0Ca2+/0Na+ solution. Taken together with a similar prior observation in salamander red-sensitive cones, these observations indicate that the dominance of response recovery by a Ca2+-sensitive process is a general feature of amphibian cone phototransduction. Moreover, changes in the external pH also influenced the dominant time constant of red-sensitive cones even when changes in internal [Ca2+] were prevented. Because the cone photopigment is, uniquely, exposed to the external solution, this may represent a direct effect of protons on the equilibrium between its inactive Meta I and active Meta II forms, consistent with the notion that the process dominating recovery of the bright flash response represents quenching of the active Meta II form of the cone photopigment. PMID:22802362

  15. 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.

  16. 12 CFR 1291.2 - Required annual AHP contributions; allocation of contributions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... that portion of its annual required AHP contribution that is not set aside to fund homeownership set... application program, pursuant to the requirements of this part. (2) Homeownership set-aside programs—(i) Allocation amount; first-time homebuyers. A Bank, in its discretion, may set aside annually, in the...

  17. Constant Time Delay and Interspersal of Known Items To Teach Sight Words to Students with Mental Retardation and Learning Disabilities.

    ERIC Educational Resources Information Center

    Knight, Melissa G.; Ross, Denise E.; Taylor, Ronald L.; Ramasamy, Rangasamy

    2003-01-01

    This study compared efficacy and efficiency of constant time delay and interspersal of known items to teach sight words to four students with mild mental retardation and learning disabilities. Results support effectiveness of constant time delay and suggest that interspersal of known items was more effective with students with learning…

  18. 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

  19. 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

  20. 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.

  1. Time and Space Resolved Wall Temperature Measurements during Nucleate Boiling with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work is to acquire time and space resolved temperature distributions under nucleate bubbles on a constant heat flux surface. This was performed using a microheater array with 100 micron resolution that allowed effectively simultaneous measurements of surface temperature while supplying a constant dissipative heat flux. This data is then correlated with high speed (> 1000Hz) visual recordings of the bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that a significant source of energy during bubble nucleation and initial growth is the superheated layer around the bubble. Bubble coalescence was not observed to decrease surface temperature as significantly as bubble departure from the surface. Since bubble departure is typically followed by a sharp increase in the heater surface temperature, it is surmised that the departing bubble effectively removes the superheated layer, allowing a high local heat transfer rate with the bulk fluid through transient conduction/micro-convection during rewetting.

  2. 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.

  3. 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.

  4. Time and Space Resolved Heat Flux Measurements During Nucleate Boiling with Constant Heat Flux Boundary Conditions

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work was to acquire time and space resolved temperature distributions under nucleating bubbles on a constant heat flux surface using a microheater array with 100x 100 square microns resolution, then numerically determine the wall to liquid heat flux. This data was then correlated with high speed (greater than l000Hz) visual recordings of The bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that microlayer evaporation and contact line heat transfer are not major heat transfer mechanisms for bubble growth. The dominant heat transfer mechanism appears to be transient conduction into the liquid as the liquid rewets the wall during the bubble departure process.

  5. 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.

  6. 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}.

  7. 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.

  8. Low resolution solution structure of an enzymatic active AhpC10:AhpF2 ensemble of the Escherichia coli Alkyl hydroperoxide Reductase.

    PubMed

    Kamariah, Neelagandan; Nartey, Wilson; Eisenhaber, Birgit; Eisenhaber, Frank; Grüber, Gerhard

    2016-01-01

    The ability of bacteria to combat oxidative stress is imperative for their survival. The Alkyl hydroperoxide Reductase (AhpR) system, composed of the AhpC and AhpF proteins, is one of the dominant antioxidant defense systems required for scavenging hydrogen peroxide and organic peroxide. Therefore, it is necessary to understand the mechanism of the AhpR ensemble formation. In previous studies, we were able to elucidate conformational flexibility of Escherichia coli AhpF during the catalytic cycle and its binding site, the N-terminal domain (NTD), to AhpC. We proposed the novel binding and release mechanism of EcAhpC-AhpF, which is mediated by the well defined redox-state linked conformational changes associated with the C-terminal tail and active site regions of EcAhpC. Here, we have proceeded further to elucidate the solution structure of E. coli AhpC and the stable ensemble formation with EcAhpF using size-exclusion chromatography (SEC), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) techniques. The EcAhpC-AhpF complex structure with a stoichiometry of AhpC10:AhpF2 reveals that dimeric EcAhpF in its extended conformation enables the NTD disulphide centers to come in close proximity to the redox-active disulphide centers of EcAhpC, and provides an efficient electron transfer. Furthermore, the significance of the C-terminal tail of EcAhpC in ensemble formation is elucidated. SAXS data-based modeling revealed the flexible C-terminal tail of EcAhpC in solution, and its exposed nature, making it possible to contact the NTD of EcAhpF for stable complex formation. PMID:26584540

  9. 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. PMID:24942645

  10. 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.

  11. Constant-thrust glideslope guidance algorithm for time-fixed rendezvous in real halo orbit

    NASA Astrophysics Data System (ADS)

    Lian, Yijun; Meng, Yunhe; Tang, Guojian; Liu, Luhua

    2012-10-01

    This paper presents a fixed-time glideslope guidance algorithm that is capable of guiding the spacecraft approaching a target vehicle on a quasi-periodic halo orbit in real Earth-Moon system. To guarantee the flight time is fixed, a novel strategy for designing the parameters of the algorithm is given. Based on the numerical solution of the linearized relative dynamics of the Restricted Three-Body Problem (expressed in inertial coordinates with a time-variant nature), the proposed algorithm breaks down the whole rendezvous trajectory into several arcs. For each arc, a two-impulse transfer is employed to obtain the velocity increment (delta-v) at the joint between arcs. Here we respect the fact that instantaneous delta-v cannot be implemented by any real engine, since the thrust magnitude is always finite. To diminish its effect on the control, a thrust duration as well as a thrust direction are translated from the delta-v in the context of a constant thrust engine (the most robust type in real applications). Furthermore, the ignition and cutoff delays of the thruster are considered as well. With this high-fidelity thrust model, the relative state is then propagated to the next arc by numerical integration using a complete Solar System model. In the end, final corrective control is applied to insure the rendezvous velocity accuracy. To fully validate the proposed guidance algorithm, Monte Carlo simulation is done by incorporating the navigational error and the thrust direction error. Results show that our algorithm can effectively maintain control over the time-fixed rendezvous transfer, with satisfactory final position and velocity accuracies for the near-range guided phase.

  12. Effects of lung time constant, gas analyser delay and rise time on measurements of respiratory dead-space.

    PubMed

    Tang, Yongquan; Turner, Martin J; Baker, A Barry

    2005-12-01

    This study evaluated effects of mechanical time constants (tau(m)) of the respiratory system, delays between flow and CO(2) partial pressure (P(CO)(2)) signals and rise time of the CO(2) analyser on dead-space measurements. A computer model simulated low alveolar dead-space, high alveolar dead-space, 0.2 time delays and anatomic and physiological dead-spaces were calculated. The CO(2) analyser was simulated as a critically damped second-order system with 10-90% rise times of 25-400 ms. The error in measured dead-space increases approximately 2.5% per 10 ms signal delay for normal lungs (tau(m) = 1 s), but has low sensitivity (0.58% per 10 ms) to the rise time of the CO(2) analyser. Sensitivity of physiological dead-space, but not anatomic dead-space to delay is decreased in high alveolar dead-space and abnormal V/Q distribution. Shorter tau(m) increase the error sensitivity of both physiological and anatomic dead-spaces to both delay and rise time. P(CO)(2) and flow should be well synchronized, particularly when tau(m) are short, to avoid dead-space errors. PMID:16311457

  13. On time variations of gravitational and Yang-Mills constants in a cosmological model of superstring origin

    NASA Astrophysics Data System (ADS)

    Ivashchuk, V. D.; Melnikov, V. N.

    2014-01-01

    In the framework of 10-dimensional "Friedmann-Calabi-Yau" cosmology of superstring origin we show that the time variation of either Newton's gravitational constant or Yang-Mills one is unavoidable in the present epoch.

  14. 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.

  15. A 45-year time series of dune mobility indicating constant windiness over the central Sahara

    NASA Astrophysics Data System (ADS)

    Vermeesch, P.; Leprince, S.

    2012-07-01

    Although evidence is mounting that links global warming to changes in atmospheric dynamics over the Atlantic realm, similar studies over the African continent are lacking. And even if such models would exist, it would be difficult to verify their validity due to the paucity of meteorological observations and anemometers in the central Sahara. A pragmatic way around this problem is to monitor barchan dune velocity as a proxy for the windiness of desert areas. Dune migration rates are a measure of the amount of work done by the wind which does not require field measurements but can be observed from space instead. This paper presents a novel application of the remote sensing tool COSI-Corr for the construction of time series of dune mobility from sequences of optical satellite imagery. The technique has been applied to the Bodélé Depression in northern Chad, to demonstrate that dune migration rates in the central Sahara have been remarkably constant for nearly half a century, leading us to conclude that wind velocities have not changed more than 0.2% per year over that period. It is therefore unlikely that the frequency and intensity of dust storms originating from this ‘hot spot’ has significantly changed over the past decades either.

  16. 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.

  17. The Oklo bound on the time variation of the fine-structure constant revisited

    NASA Astrophysics Data System (ADS)

    Damour, Thibault; Dyson, Freeman

    1996-02-01

    It has been pointed out by Shlyakhter that data from the natural fission reactors which operated about two billion years ago at Oklo (Gabon) had the potential of providing an extremely tight bound on the variability of the fine-structure constant α. We revisit the derivation of such a bound by (i) reanalyzing a large selection of published rare-earth data from Oklo, (ii) critically taking into account the very large uncertainty of the temperature at which the reactors operated, and (iii) connecting in a new way (using isotope shift measurements) the Oklo-derived constraint on a possible shift of thermal neutron-capture resonances with a bound on the time variation of α. Our final (95% C.L.) results are: -0.9 × 10 -7 < ( αOklo - αnow)/ α < 1.2 × 10 -7 and -6.7 × 10 -17yr-1 < αdotaveraged/α < 5.0 × 10 -17yr-1.

  18. 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.

  19. Smoothed Particle Hydrodynamics with Time Varying, Piecewise Constant Smoothing Length Profiles

    NASA Astrophysics Data System (ADS)

    Børve, S.; Omang, M.; Trulsen, J.

    2000-12-01

    Smoothed Particle Hydrodynamics (SPH) has proven to be a very useful numerical tool in studying a number of widely different astrophysical problems. Still, used on many other types of problems the method faces problems concerning efficiency and accuracy compared to that of modern grid-based methods. Essential to efficiency is maintaining a near-optimal particle distribution and smoothing length profile that reflects the physics of the problem. This means, directing computer resources towards those regions and time intervals where the action is taking place and not being wasted where nothing is happening. In the literature researchers have tried to achieve these goals by combining the Lagrangian nature of the SPH method with a smoothing length profile varying smoothly in space and time. To make the SPH method better suited for accurately describing a wider range of problems, a scheme containing two novel features is proposed. First, the scheme assumes a piecewise constant smoothing length profile. To avoid substantial errors near steps in the smoothing length profile, alternative forms of the SPH equations of motion is used. Secondly, a predictive attitude towards optimizing the particle distribution is introduced by activating a mass, momentum and internal energy conservation regularization process at intervals. The main challenge faced by the scheme has been to put the newly optimized smoothing length profile into use without severely altering the underlying physics. To achieve this, the entire set of particles is redefined in the process. The basic ideas behind this scheme is briefly described. Finally, the results from several hydrodynamical and magnetohydrodynamical tests in one and two dimensions are presented. This work is funded by the Research Council of Norway.

  20. 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

  1. Nightside magnetospheric current circuit: Time constants of the solar wind-magnetosphere coupling

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Uozumi, T.

    2014-05-01

    This study addresses the characteristics of the nightside magnetospheric current system using the analogy of an electric circuit. The modeled circuit consists of the generator (V: solar wind), inductor (L: tail lobes), capacitor (C: plasma sheet convection), and resistor (R: particle energization). The electric circuit has three time constants: τCR(=CR), τLC(=√LC), and τL/R(=L/R). Here τCR is of the order of the ion gyroperiod in the plasma sheet, τLC is a global timescale (2πτLC is several tens of minutes), and τL/R is even longer (several hours). Despite uncertainty in the estimate of each circuit element, τCR ≪ τLC ≪ τL/R holds generally for the magnetosphere, which characterizes the electric circuit as overdamped. The following implications are obtained: (1) During the substorm growth phase the cross-tail current increases continuously even if interplanetary magnetic field (IMF) BZ does not change after southward turning; (2) the magnetotail current weakens following northward turnings if the change of IMF BZ is comparable to the preceding southward IMF BZ; otherwise it may strengthen continuously if more gradually; (3) during the early main phase of magnetospheric storms the enhancement of the lobe magnetic energy is far more prominent than the enhancements of the kinematic and kinetic energies of the plasma sheet plasma; (4) The efficiency of the solar wind-magnetosphere coupling changes on a timescale of several hours (τL/R) through the change of the tail flaring, and so does the cross polar-cap potential; and (5) the magnetospheric current system does not resonate to an oscillatory external driver, and therefore, the periodicity of some magnetotail phenomena reflects that of their triggers.

  2. 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.

  3. Holographic dark energy with time depend gravitational constant in the non-flat Hořava-Lifshitz cosmology

    NASA Astrophysics Data System (ADS)

    Aghamohammadi, A.; Saaidi, K.; Setare, M. R.

    2011-04-01

    We study the holographic dark energy on the subject of Hořava-Lifshitz gravity with a time dependent gravitational constant G( t), in the non-flat space-time. We obtain the differential equation that specify the evolution of the dark energy density parameter based on varying gravitational constant. We find out a relation for the state parameter of the dark energy equation of state to low red-shifts which containing varying G corrections in the non-flat space-time.

  4. 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…

  5. Effectiveness of Constant Time Delay on Teaching Snack and Drink Preparation Skills to Children with Mental Retardation

    ERIC Educational Resources Information Center

    Bozkurt, Funda; Gursel, Oguz

    2005-01-01

    A multiple probe design with probe conditions across behaviors was used to evaluate effectiveness of constant time delay on teaching snack and drink preparation skills to children with mental retardation. In addition, generalization effects across settings, time, and materials, and maintenance effects were examined. Three students between the ages…

  6. The Evaluation of ERP Sandtable Simulation Based on AHP

    NASA Astrophysics Data System (ADS)

    Xu, Lan

    Due to the trend of world globalization, many enterprises have extended their business to operate globally. Enterprise resource planning is a powerful management system providing the best business resources information. This paper proposed the theory of AHP, and presented ERP sandtable simulation evaluation to discuss how to make a decision using AHP. Using this method can make enterprises consider factors influence operation of enterprise adequately, including feedback and dependence among the factors.

  7. Research on AHP speed adjusting based on fuzzy-PID double-mode complex control

    NASA Astrophysics Data System (ADS)

    Sang, Yong; Liu, Yang; Lin, Hongbin; Wang, Zhanlin

    2008-10-01

    In the ground test station of AC motor driven airborne hydraulic pump (referred to as AHP, hereinafter), speed adjusting is usually worsened by the high order, nonlinearity and time-varying features of AC motor, as well as the nonlinearity of the hydraulic system. In order to solve these problems a new complex control method based on Fuzzy-PID control theory is brought forward. The control method adopts fuzzy controller to enhance the system's tracing features under big error conditions and adopts parameter self-modifying Fuzzy-PID control to eliminate static errors under small error conditions. Simulation results show that the complex controller has faster response, higher accuracy, stronger robust, compared with the general PID controller. The AHP speed and robust requirements can be satisfied.

  8. 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…

  9. 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.…

  10. Coupling loss time constants in full-size Nb{sub 3}Sn CIC model conductors for fusion magnets

    SciTech Connect

    Nijhuis, A.; Kate, H.H.J. ten; Duchateau, J.L.

    1997-06-01

    The cable-in-conduit conductor for the ITER coils have to perform at magnetic fields up to 13 T under the conditions of normal high ramp rates as well as extreme magnetic pulses during a plasma disruption. Modelling, ac loss computations and design optimisations require to understand and identify the coupling loss time constants in multistage cables. For this AC loss measurements are performed on jacketed full size Nb{sub 3}Sn cable-in-conduit conductors. A transverse sinusoidal magnetic field is applied on the conductor to determine the coupling loss time constants with a calorimetric method. Moreover the decay of the coupling currents after a linear ramp is monitored with compensated pick-up coils. A comparison is made between the results obtained with both measuring methods. It appears that the n.{tau} value taken from the slope of the loss versus frequency curve in the low frequency limit has only a meaning at these low frequencies. At higher rates of magnetic field change which are relevant to describe a plasma disruption, internal shielding effects are not negligible and a different approach has to be used. The experimental results and a straightforward model are presented to find the coupling current time constants of this type of conductors. It is shown that several dominant time constants can exist that are associated with relatively small volume fractions of a cable.

  11. 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…

  12. 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…

  13. 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…

  14. 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…

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

    SciTech Connect

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

    2004-11-15

    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 {alpha} 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.

  17. The active site architecture in peroxiredoxins: a case study on Mycobacterium tuberculosis AhpE.

    PubMed

    Pedre, Brandán; van Bergen, Laura A H; Palló, Anna; Rosado, Leonardo A; Dufe, Veronica Tamu; Molle, Inge Van; Wahni, Khadija; Erdogan, Huriye; Alonso, Mercedes; Proft, Frank De; Messens, Joris

    2016-08-11

    Peroxiredoxins catalyze the reduction of peroxides, a process of vital importance to survive oxidative stress. A nucleophilic cysteine, also known as the peroxidatic cysteine, is responsible for this catalytic process. We used the Mycobacterium tuberculosis alkyl hydroperoxide reductase E (MtAhpE) as a model to investigate the effect of the chemical environment on the specificity of the reaction. Using an integrative structural (R116A - PDB ; F37H - PDB ), kinetic and computational approach, we explain the mutational effects of key residues in its environment. This study shows that the active site residues are specifically oriented to create an environment which selectively favours a reaction with peroxides. PMID:27471753

  18. The graviton one-loop effective action in cosmological space-times with constant deceleration

    NASA Astrophysics Data System (ADS)

    Janssen, T. M.; Prokopec, T.

    2010-05-01

    We consider the quantum Friedmann equations which include one-loop vacuum fluctuations due to gravitons and scalar field matter in a FLRW background with constant γ=-H˙/H2. After several field redefinitions, to remove the mixing between the gravitational and matter degrees of freedom, we can construct the one-loop correction to the Friedmann equations. Due to cosmological particle creation, the propagators needed in such a calculation are typically infrared divergent. In this paper we construct the graviton and matter propagators, making use of the recent construction of the infrared finite scalar propagators calculated on a compact spatial manifold in Janssen et al. (2008) [1]. The resulting correction to the Friedman equations is suppressed with respect to the tree level contribution by a factor of H2/mp2 and shows no secular growth.

  19. 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.

  20. Time constant of hydraulic-head response in aquifers subjected to sudden recharge change: application to large basins

    NASA Astrophysics Data System (ADS)

    Vasseur, Guy; Rousseau-Gueutin, Pauline; de Marsily, Ghislain

    2015-08-01

    Analytical formulae are proposed to describe the first-order temporal evolution of the head in large groundwater systems (such as those found in North Africa or eastern Australia) that are subjected to drastic modifications of their recharge conditions (such as those in Pleistocene and Holocene times). The mathematical model is based on the hydrodynamics of a mixed-aquifer system composed of a confined aquifer connected to an unconfined one with a large storage capacity. The transient behaviour of the head following a sudden change of recharge conditions is computed with Laplace transforms for linear one-dimensional and cylindrical geometries. This transient evolution closely follows an exponential trend exp(- t/ τ). The time constant τ is expressed analytically as a function of the various parameters characterizing the system. In many commonly occurring situations, τ depends on only four parameters: the width a c of the main confined aquifer, its transmissivity T c, the integrated storage situated upstream in the unconfined aquifer M = S u a u, and a curvature parameter accounting for convergence/divergence effects. This model is applied to the natural decay of large aquifer basins of the Sahara and Australia following the end of the mid-Holocene humid period. The observed persistence of the resource is discussed on the basis of the time constant estimated with the system parameters. This comparison confirms the role of the upstream water reserve, which is modelled as an unconfined aquifer, and highlights the significant increase of the time constant in case of converging flow.

  1. 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

  2. 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.

  3. Deletion of the L-type Calcium Channel CaV1.3 but not CaV1.2 Results in a Diminished sAHP in Mouse CA1 Pyramidal Neurons

    PubMed Central

    Gamelli, Amy E.; McKinney, Brandon C.; White, Jessica A.; Murphy, Geoffrey G.

    2009-01-01

    Trains of action potentials in CA1 pyramidal neurons are followed by a prolonged calcium-dependent post-burst afterhyperpolarization (AHP) that serves to limit further firing to a sustained depolarizing input. A reduction in the AHP accompanies acquisition of several types of learning and increases in the AHP are correlated with age-related cognitive impairment. The AHP develops primarily as the result of activation of outward calcium-activated potassium currents; however the precise source of calcium for activation of the AHP remains unclear. There is substantial experimental evidence suggesting that calcium influx via voltage-gated L-type calcium channels (L-VGCCs) contributes to the generation of the AHP. Two L-VGCC subtypes are predominately expressed in the hippocampus, CaV1.2 and CaV1.3, however it is not known which L-VGCC subtype is involved in generation of the AHP. This ambiguity is due in large part to the fact that at present there are no subunit-specific agonists or antagonists. Therefore, using mice in which the gene encoding CaV1.2 or CaV1.3 was deleted, we sought to determine the impact of alterations in levels of these two L-VCGG subtypes on neuronal excitability. No differences in any AHP measure were seen between neurons from CaV1.2 knockout mice and controls. However, the total area of the AHP was significantly smaller in neurons from CaV1.3 knockout mice as compared to neurons from wildtype controls. A significant reduction in the amplitude of the AHP was also seen at the 1 sec time point in neurons from CaV1.3 knockout mice as compared to those from controls. Reductions in both the area and 1 sec amplitude suggest the involvement of calcium influx via CaV1.3 in the slow AHP (sAHP). Thus, the results of our study demonstrate that deletion of CaV1.3, but not CaV1.2, significantly impacts the generation of the sAHP. PMID:20014384

  4. Using Constant Time Delay To Teach Preventative Safety Skills to Preschoolers with Disabilities. Final Report.

    ERIC Educational Resources Information Center

    Rule, Sarah; Tso, Marion

    This final report describes a study to investigate the effects of an intervention procedure that included time delay, praise, and other cues on the acquisition of safety skills in preschool children with disabilities. Twelve preschool-aged children with disabilities from six different classrooms participated. Preventive safety skills consisted of…

  5. A compensatory algorithm for the slow-down effect on constant-time-separation approaches

    NASA Technical Reports Server (NTRS)

    Abbott, Terence S.

    1991-01-01

    In seeking methods to improve airport capacity, the question arose as to whether an electronic display could provide information which would enable the pilot to be responsible for self-separation under instrument conditions to allow for the practical implementation of reduced separation, multiple glide path approaches. A time based, closed loop algorithm was developed and simulator validated for in-trail (one aircraft behind the other) approach and landing. The algorithm was designed to reduce the effects of approach speed reduction prior to landing for the trailing aircraft as well as the dispersion of the interarrival times. The operational task for the validation was an instrument approach to landing while following a single lead aircraft on the same approach path. The desired landing separation was 60 seconds for these approaches. An open loop algorithm, previously developed, was used as a basis for comparison. The results showed that relative to the open loop algorithm, the closed loop one could theoretically provide for a 6 pct. increase in runway throughput. Also, the use of the closed loop algorithm did not affect the path tracking performance and pilot comments indicated that the guidance from the closed loop algorithm would be acceptable from an operational standpoint. From these results, it is concluded that by using a time based, closed loop spacing algorithm, precise interarrival time intervals may be achievable with operationally acceptable pilot workload.

  6. 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.

  7. A two-dimensional model of the plasmasphere - Refilling time constants

    NASA Technical Reports Server (NTRS)

    Rasmussen, Craig E.; Guiter, Steven M.; Thomas, Steven G.

    1993-01-01

    A 2D model of the plasmasphere has been developed to study the temporal evolution of plasma density in the equatorial plane of the magnetosphere. This model includes the supply and loss of hydrogen ions due to ionosphere-magnetosphere coupling as well as the effects of E x B convection. A parametric model describing the required coupling fluxes has been developed which utilizes empirical models of the neutral atmosphere, the ionosphere and the saturated plasmasphere. The plasmaspheric model has been used to examine the time it takes for the plasmasphere to refill after it has been depleted by a magnetic storm. The time it takes for the plasmasphere to reach 90 percent of its equilibrium level ranges from 3 days at L = 3 during solar minimum to as high as 100 days at L = 5 during solar maximum. Refilling is also dependent on the month of the year, with refilling requiring a longer period of time at solar maximum during June than during December for L greater than 3.2.

  8. Avoiding unrealistic priors: The case of dark energy constraints from the time variation of the fine-structure constant

    NASA Astrophysics Data System (ADS)

    Avelino, P. P.

    2016-04-01

    We critically assess recent claims suggesting that upper limits on the time variation of the fine-structure constant tightly constrain the coupling of a dark energy scalar field to the electromagnetic sector, and, indirectly, the violation of the weak equivalence principle. We show that such constraints depend crucially on the assumed priors, even if the dark energy was described by a dynamical scalar field with a constant equation-of-state parameter w linearly coupled to the electromagnetic sector through a dimensionless coupling ζ . We find that, although local atomic clock tests, as well as other terrestrial, astrophysical and cosmological data, put stringent bounds on |ζ |√{|w +1 | } , the time variation of the fine-structure constant cannot be used to set or to improve upper limits on |ζ | or |w +1 | without specifying priors, consistent with but not favored by current data, which disfavor low values of |w +1 | or |ζ |, respectively. We briefly discuss how this might change with a new generation of high-resolution ultrastable spectrographs, such as ESPRESSO and ELT-HIRES, in combination with forthcoming missions to map the geometry of the Universe, such as Euclid, or to test the equivalence principle, such as MICROSCOPE or STEP.

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

    DOE PAGESBeta

    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

  10. 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.

  11. 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.

  12. 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.

  13. Analytic hierarchy process (AHP) as a tool in asset allocation

    NASA Astrophysics Data System (ADS)

    Zainol Abidin, Siti Nazifah; Mohd Jaffar, Maheran

    2013-04-01

    Allocation capital investment into different assets is the best way to balance the risk and reward. This can prevent from losing big amount of money. Thus, the aim of this paper is to help investors in making wise investment decision in asset allocation. This paper proposes modifying and adapting Analytic Hierarchy Process (AHP) model. The AHP model is widely used in various fields of study that are related in decision making. The results of the case studies show that the proposed model can categorize stocks and determine the portion of capital investment. Hence, it can assist investors in decision making process and reduce the risk of loss in stock market investment.

  14. Stability prediction of amorphous benzodiazepines by calculation of the mean relaxation time constant using the Williams-Watts decay function.

    PubMed

    Van den Mooter, G; Augustijns, P; Kinget, R

    1999-07-01

    The enthalpic relaxation of three amorphous benzodiazepines, diazepam, temazepam and triazolam was studied using differential scanning calorimetry for ageing temperatures which were below the glass transition temperature, and ageing times up to 16 h. Experimental determination of the relaxation enthalpy and the heat capacity change, both accompanying the glass transition, enabled us to calculate the extent of relaxation of the amorphous drugs at specific ageing conditions. Fitting of the relaxation function to the Williams-Watts two parameter decay function led to calculation of the mean relaxation time constant tau and the molecular relaxation time distribution parameter beta. The mean relaxation time constants for the three drugs increased from approximately ten h at the glass transition temperature with more than eight orders of magnitude at 66 K below the glass transition temperature. It was found that the benzodiazepines exhibited significant molecular mobility until approximately 50 K below the glass transition temperature; below this temperature molecular mobility becomes unimportant with respect to the shelf life stability. Hence the presented procedure provides the formulation scientist with a tool to set storage conditions for amorphous drugs and glassy pharmaceutical products. PMID:10477327

  15. 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.

  16. 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.

  17. 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

  18. Polestitters: Using Solar Sails for Constant Real-time Sensing of Earth's Polar Regions

    NASA Astrophysics Data System (ADS)

    Mulligan, P.; Diedrich, B. L.; Barnes, N.; Derbes, B.

    2012-12-01

    NASA has funded the Sunjammer mission - a near term demonstration of solar sail technology (2014/15). Sunjammer has the potential to demonstrate stationkeeping out of Earth's orbital plane. This is a first step in achieving "polesitter" orbits with year-round, real-time visibility of Earth's polar regions. Potential applications for such missions are illustrated. Solar sails have long been a concept for spacecraft propulsion that works by exchanging momentum with sunlight reflected by large, lightweight, mirrored sails. In addition to enabling propellantless propulsion throughout the solar system and beyond, their continuous thrust enables artificial Lagrange orbits (ALOs), some of which can be called "polesitter" orbits, with 24-hour, year-round visibility of Earth's polar regions. Several potential Earth remote sensing applications have been identified that address the limited temporal and spatial coverage from traditional polar and geostationary satellites. The Galileo spacecraft during its 1990 Earth flyby acquired imagery and radiometer data similar to the view from a polesitter. The Galileo imagery was used to derive aerosols and cloud variations used in atmospheric motion vector (AMV) derivations. Composites of satellite imagery over the South Pole is routinely used to derive atmospheric motion vectors like those performed regularly from geostationary satellites. The JAXA IKAROS mission flew a 14x14m solar sail past Venus in 2010. Sunjammer will demonstrate a state of the art 38x38m solar sail from Earth to an artificial Lagrange orbit located sunward and north of the sun-Earth L1 point. Traditional spacecraft can orbit naturally occurring Lagrange equilibrium points between the sun and Earth. The low, continuous thrust of solar sails can change where these points occur, creating new orbits with a variety of potential applications including polar remote sensing, space weather monitoring, and polar communications. This figure illustrates a selection of

  19. 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

  20. 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.

  1. Effect of UV curing time on physical and electrical properties and reliability of low dielectric constant materials

    SciTech Connect

    Kao, Kai-Chieh; Cheng, Yi-Lung; Chang, Wei-Yuan; Chang, Yu-Min; Leu, Jihperng

    2014-11-01

    This study comprehensively investigates the effect of ultraviolet (UV) curing time on the physical, electrical, and reliability characteristics of porous low-k materials. Following UV irradiation for various periods, the depth profiles of the chemical composition in the low-k dielectrics were homogeneous. Initially, the UV curing process preferentially removed porogen-related CH{sub x} groups and then modified Si-CH{sub 3} and cage Si-O bonds to form network Si-O bonds. The lowest dielectric constant (k value) was thus obtained at a UV curing time of 300 s. Additionally, UV irradiation made porogen-based low-k materials hydrophobic and to an extent that increased with UV curing time. With a short curing time (<300 s), porogen was not completely removed and the residues degraded reliability performance. A long curing time (>300 s) was associated with improved mechanical strength, electrical performance, and reliability of the low-k materials, but none of these increased linearly with UV curing time. Therefore, UV curing is necessary, but the process time must be optimized for porous low-k materials on back-end of line integration in 45 nm or below technology nodes.

  2. 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.

  3. Does slow energy transfer limit the observed time constant for radical pair formation in photosystem II reaction centers?

    PubMed

    Rech, T; Durrant, J R; Joseph, D M; Barber, J; Porter, G; Klug, D R

    1994-12-13

    We have used spectrally photoselective femtosecond transient absorption spectroscopy on photosystem II reaction centers to show that there are at least two pools of chlorin molecules/states which can transfer excitation energy to P680, the primary electron donor in photosystem II. It has previously been shown that one chlorin pool equilibrates with P680 in 100 fs [Durrant et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11632-11636], and we report here the observation of energy transfer from a second more weakly coupled chlorin pool. The effect of the weakly coupled pool is to increase the apparent time constant for radical pair formation from 21 ps when P680 is selectively excited to 27 ps when the accessory chlorins are excited. We conclude that it is possible to observe both radical pair formation somewhat slowed by an energy transfer step and radical pair formation not limited by this slow energy transfer, depending upon which chromophores are initially excited. These observations provide evidence that when using photoselective excitation of P680, the observed 21 ps time constant for radical pair formation is not limited by a slow energy transfer step. PMID:7993905

  4. Logistic time constant of isometric relaxation force curve of ferret ventricular papillary muscle: reliable index of lusitropism.

    PubMed

    Mizuno, J; Araki, J; Mikane, T; Mohri, S; Imaoka, T; Matsubara, H; Okuyama, H; Kurihara, S; Ohe, T; Hirakawa, M; Suga, H

    2000-10-01

    We have found that a logistic function fits the left ventricular isovolumic relaxation pressure curve in the canine excised, cross-circulated heart more precisely than a monoexponential function. On this basis, we have proposed a logistic time constant (tau(L)) as a better index of ventricular isovolumic lusitropism than the conventional monoexponential time constant (tau(E)). We hypothesize in the present study that this tau(L) would also be a better index of myocardial isometric lusitropism than the conventional tau(E). We tested this hypothesis by analyzing the isometric relaxation force curve of 114 twitches of eight ferret isolated right ventricular papillary muscles. The muscle length was changed between 82 and 100% L(max) and extracellular Ca(2+) concentrations ([Ca(2+)](o)) between 0.2 and 8 mmol/l. We found that the logistic function always fitted the isometric relaxation force curve much more precisely than the monoexponential function at any muscle length and [Ca(2+)](o) level. We also found that tau(L) was independent of the choice of the end of isometric relaxation but tau(E) was considerably dependent on it as in ventricular relaxation. These results validated our present hypothesis. We conclude that tau(L) is a more reliable, though still empirical, index of lusitropism than conventional tau(E) in the myocardium as in the ventricle. PMID:11120914

  5. 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.

  6. Use of Outcome Measurement by Paediatric AHPs in Northern Ireland

    ERIC Educational Resources Information Center

    Harron, Anita; Titterington, Jill

    2016-01-01

    Background: Professional standards advocate routine use of outcome measurement (OM) in the practice of allied health professionals (AHPs). Historically, OM has focused on impairment and its immediate constraints on activity, while current policy encourages the development and addition of impact-based OM. There appears to be an assumption at this…

  7. 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…

  8. In Situ Time Constant and Optical Efficiency Measurements of TRUCE Pixels in the Atacama B-Mode Search

    NASA Astrophysics Data System (ADS)

    Simon, S. M.; Appel, J. W.; Cho, H. M.; Essinger-Hileman, T.; Irwin, K. D.; Kusaka, A.; Niemack, M. D.; Nolta, M. R.; Page, L. A.; Parker, L. P.; Raghunathan, S.; Sievers, J. L.; Staggs, S. T.; Visnjic, K.

    2014-09-01

    The Atacama B-mode Search (ABS) instrument, which began observation in February of 2012, is a crossed-Dragone telescope located at an elevation of 5,100 m in the Atacama Desert in Chile. The primary scientific goal of ABS is to measure the B-mode polarization spectrum of the Cosmic Microwave Background from multipole moments of about 50 to 500 (angular scales from to ), a range that includes the primordial B-mode peak from inflationary gravitational waves. The ABS focal plane array consists of 240 pixels designed for observation at 145 GHz by the TRUCE collaboration. Each pixel has its own individual, single-moded feedhorn and contains two transition-edge sensor bolometers coupled to orthogonal polarizations that are read out using time domain multiplexing. We will report on the current status of ABS and discuss the time constants and optical efficiencies of the TRUCE detectors in the field.

  9. Relating low-flow characteristics to the base flow recession time constant at partial record stream gauges

    USGS Publications Warehouse

    Eng, K.; Milly, P.C.D.

    2007-01-01

    Base flow recession information is helpful for regional estimation of low-flow characteristics. However, analyses that exploit such information generally require a continuous record of streamflow at the estimation site to characterize base flow recession. Here we propose a simple method for characterizing base flow recession at low-flow partial record stream gauges (i.e., sites with very few streamflow measurements under low-streamflow conditions), and we use that characterization as the basis for a practical new approach to low-flow regression. In a case study the introduction of a base flow recession time constant, estimated from a single pair of strategically timed streamflow measurements, approximately halves the root-mean-square estimation error relative to that of a conventional drainage area regression. Additional streamflow measurements can be used to reduce the error further.

  10. Enhanced time response of 1-in. LaBr3(Ce) crystals by leading edge and constant fraction techniques

    NASA Astrophysics Data System (ADS)

    Vedia, V.; Mach, H.; Fraile, L. M.; Udías, J. M.; Lalkovski, S.

    2015-09-01

    We have characterized in depth the time response of three detectors equipped with cylindrical LaBr3(Ce) crystals with dimensions of 1-in. in height and 1-in. in diameter, and having nominal Ce doping concentration of 5%, 8% and 10%. Measurements were performed at 60Co and 22Na γ-ray energies against a fast BaF2 reference detector. The time resolution was optimized by the choice of the photomultiplier bias voltage and the fine tuning of the parameters of the constant fraction discriminator, namely the zero-crossing and the external delay. We report here on the optimal time resolution of the three crystals. It is observed that timing properties are influenced by the amount of Ce doping and the crystal homogeneity. For the crystal with 8% of Ce doping the use of the ORTEC 935 CFD at very shorts delays in addition to the Hamamatsu R9779 PMT has made it possible to improve the LaBr3(Ce) time resolution from the best literature value at 60Co photon energies to below 100 ps.

  11. 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.

  12. 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.

  13. 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.

  14. Hydraulic time constants for transpiration of loblolly pine at a free-air carbon dioxide enrichment site.

    PubMed

    Ward, Eric J; Bell, David M; Clark, James S; Oren, Ram

    2013-02-01

    The impact of stored water on estimates of transpiration from scaled sap flux measurements was assessed in mature Pinus taeda (L.) at the Duke Free-Air CO(2) Enrichment (FACE) site. We used a simple hydraulic model with measurements of sap flux (J) at breast height and the base of the live crown for 26 trees over 6 months to examine the effects of elevated CO(2) (eCO(2)) and fertilization (N(F)) treatments, as well as temporal variation in soil moisture (M(()(t)())), on estimates of the hydraulic time constant (κ). At low M(()(t)()), there was little (<12%) difference in κ of different treatments. At high M(()(t)()), differences were much greater, with κ reductions of 27, 52 and 34% in eCO(2), N(F) and eCO(2) × N(F) respective to the control. Incorporating κ with these effects into the analysis of a larger data set of previous J measurements at this site (1998-2008) improved agreement between modeled and measured values in 92% of cases. However, a simplified calibration of κ that neglected treatment and soil moisture effects performed more dependably, improving agreement in 98% of cases. Incorporating κ had the effect of increasing estimates of reference stomatal conductance at 1 kPa vapor pressure deficit (VPD) and saturating photosynthetic active radiation (PAR) an average of 12-14%, while increasing estimated sensitivities to VPD and PAR. A computationally efficient hydraulic model, such as the one presented here, incorporated into a hierarchical model of stomatal conductance presents a novel approach to including hydraulic time constants in estimates of stomatal responses from long-term sap flux data sets. PMID:23192973

  15. Zoom-TOFMS: addition of a constant-momentum-acceleration "zoom" mode to time-of-flight mass spectrometry.

    PubMed

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

    2014-11-01

    In this study, we demonstrate the performance of a new mass spectrometry concept called zoom time-of-flight mass spectrometry (zoom-TOFMS). In our zoom-TOFMS instrument, we combine two complementary types of TOFMS: conventional, constant-energy acceleration (CEA) TOFMS and constant-momentum acceleration (CMA) TOFMS to provide complete mass-spectral coverage as well as enhanced resolution and duty factor for a narrow, targeted mass region, respectively. Alternation between CEA- and CMA-TOFMS requires only that electrostatic instrument settings (i.e., reflectron and ion optics) and ion acceleration conditions be changed. The prototype zoom-TOFMS instrument has orthogonal-acceleration geometry, a total field-free distance of 43 cm, and a direct-current glow-discharge ionization source. Experimental results demonstrate that the CMA-TOFMS "zoom" mode offers resolution enhancement of 1.6 times over single-stage acceleration CEA-TOFMS. For the atomic mass range studied here, the maximum resolving power at full-width half-maximum observed for CEA-TOFMS was 1,610 and for CMA-TOFMS the maximum was 2,550. No difference in signal-to-noise (S/N) ratio was observed between the operating modes of zoom-TOFMS when both were operated at equivalent repetition rates. For a 10-kHz repetition rate, S/N values for CEA-TOFMS varied from 45 to 990 and from 67 to 10,000 for CMA-TOFMS. This resolution improvement is the result of a linear TOF-to-mass scale and the energy-focusing capability of CMA-TOFMS. Use of CMA also allows ions outside a given m/z range to be rejected by simple ion-energy barriers to provide a substantial improvement in duty factor. PMID:24866712

  16. Role of alkyl hydroperoxide reductase (AhpC) in the biofilm formation of Campylobacter jejuni.

    PubMed

    Oh, Euna; Jeon, Byeonghwa

    2014-01-01

    Biofilm formation of Campylobacter jejuni, a major cause of human gastroenteritis, contributes to the survival of this pathogenic bacterium in different environmental niches; however, molecular mechanisms for its biofilm formation have not been fully understood yet. In this study, the role of oxidative stress resistance in biofilm formation was investigated using mutants defective in catalase (KatA), superoxide dismutase (SodB), and alkyl hydroperoxide reductase (AhpC). Biofilm formation was substantially increased in an ahpC mutant compared to the wild type, and katA and sodB mutants. In contrast to the augmented biofilm formation of the ahpC mutant, a strain overexpressing ahpC exhibited reduced biofilm formation. A perR mutant and a CosR-overexpression strain, both of which upregulate ahpC, also displayed decreased biofilms. However, the introduction of the ahpC mutation to the perR mutant and the CosR-overexpression strain substantially enhanced biofilm formation. The ahpC mutant accumulated more total reactive oxygen species and lipid hydroperoxides than the wild type, and the treatment of the ahpC mutant with antioxidants reduced biofilm formation to the wild-type level. Confocal microscopy analysis showed more microcolonies were developed in the ahpC mutant than the wild type. These results successfully demonstrate that AhpC plays an important role in the biofilm formation of C. jejuni. PMID:24498070

  17. Inhibition of Mycobacterium tuberculosis AhpD, an Element of the Peroxiredoxin Defense against Oxidative Stress

    PubMed Central

    Koshkin, Aleksey; Zhou, Xiao-ti; Kraus, Carl N.; Brenner, Jason M.; Bandyopadhyay, Pradipta; Kuntz, Irwin D.; Barry, Clifton E.; Ortiz de Montellano, Paul R.

    2004-01-01

    The resistance of Mycobacterium tuberculosis to isoniazid (INH) is largely linked to suppression of a catalase-peroxidase enzyme (KatG) that activates INH. In the absence of KatG, antioxidant protection is provided by enhanced expression of the peroxiredoxin AhpC, which is itself reduced by AhpD, a protein with low alkylhydroperoxidase activity of its own. Inhibition of AhpD might therefore impair the antioxidant protection afforded by AhpC and make KatG-negative strains more sensitive to oxidative stress. We report here that the 3(E),17-dioxime of testosterone is a potent competitive AhpD inhibitor, with a Ki of 50 ± 2 nM. The inhibitor is stereospecific, in that the 3(E) but not 3(Z) isomer is active. Computational studies provide support for a proposed AhpD substrate binding site. However, the inhibitor does not completely suppress the in vitro activity of AhpC/AhpD, because a low titer of AhpD suffices to maintain AhpC activity. This finding, and the low solubility of the inhibitor, explains its inability to suppress the growth of INH-resistant M. tuberculosis in infected mouse lungs. PMID:15215090

  18. Blade synchronous vibration measurement based on tip-timing at constant rotating speed without once-per-revolution sensor

    NASA Astrophysics Data System (ADS)

    Guo, Haotian; Duan, Fajie; Wang, Meng

    2016-01-01

    In this article, a blade synchronous vibration measurement method based on tip-timing at constant rotating speed is presented. This method requires no once-per revolution sensor, which makes it more generally applicable, especially for high pressure compressors of the dual rotor engines. The vibration amplitude and engine order are identified with this method. The theoretical analysis is presented, and the least square method is utilized for vibration parameter identification. The method requires at least four tip-timing sensors if the Campbell diagram is previously known and five sensors if the Campbell diagram is unknown. The method has no strict requirement on the angles among sensors which facilitate the installation of the sensors in the measurement. In some special conditions the method will fail and these conditions are analyzed. Experiments are conducted on a high speed rotor with a fiber based tip-timing system, and the experimental results indicate that the theoretical analysis is correct and the method is feasible.

  19. Arabidopsis histidine-containing phosphotransfer factor 4 (AHP4) negatively regulates secondary wall thickening of the anther endothecium during flowering.

    PubMed

    Jung, Kwang Wook; Oh, Seung-Ick; Kim, Yun Young; Yoo, Kyoung Shin; Cui, Mei Hua; Shin, Jeong Sheop

    2008-04-30

    Cytokinins are essential hormones in plant development. Arabidopsis histidine-containing phosphotransfer proteins (AHPs) are mediators in a multistep phosphorelay pathway for cytokinin signaling. The exact role of AHP4 has not been elucidated. In this study, we demonstrated young flower-specific expression of AHP4, and compared AHP4-overexpressing (Ox) trangenic Arabidopsis lines and an ahp4 knock-out line. AHP4-Ox plants had reduced fertility due to a lack of secondary cell wall thickening in the anther endothecium and inhibition of IRREGURAR XYLEMs (IRXs) expression in young flowers. Conversely, ahp4 anthers had more lignified anther walls than the wild type, and increased IRXs expression. Our study indicates that AHP4 negatively regulates thickening of the secondary cell wall of the anther endothecium, and provides new insight into the role of cytokinins in formation of secondary cell walls via the action of AHP4. PMID:18413999

  20. 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

  1. AhpC (alkyl hydroperoxide reductase) from Anabaena sp. PCC 7120 protects Escherichia coli from multiple abiotic stresses

    SciTech Connect

    Mishra, Yogesh; Chaurasia, Neha; Rai, Lal Chand

    2009-04-17

    Alkyl hydroperoxide reductase (AhpC) is known to detoxify peroxides and reactive sulfur species (RSS). However, the relationship between its expression and combating of abiotic stresses is still not clear. To investigate this relationship, the genes encoding the alkyl hydroperoxide reductase (ahpC) from Anabaena sp. PCC 7120 were introduced into E. coli using pGEX-5X-2 vector and their possible functions against heat, salt, carbofuron, cadmium, copper and UV-B were analyzed. The transformed E. coli cells registered significantly increase in growth than the control cells under temperature (47 {sup o}C), NaCl (6% w/v), carbofuron (0.025 mg ml{sup -1}), CdCl{sub 2} (4 mM), CuCl{sub 2} (1 mM), and UV-B (10 min) exposure. Enhanced expression of ahpC gene as measured by semi-quantitative RT-PCR under aforementioned stresses at different time points demonstrated its role in offering tolerance against multiple abiotic stresses.

  2. 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)).

  3. Effect of tidal volume and positive end-expiratory pressure on expiratory time constants in experimental lung injury.

    PubMed

    Henderson, William R; Dominelli, Paolo B; Molgat-Seon, Yannick; Lipson, Rachel; Griesdale, Donald E G; Sekhon, Mypinder; Ayas, Najib; Sheel, A William

    2016-03-01

    We utilized a multicompartment model to describe the effects of changes in tidal volume (VT) and positive end-expiratory pressure (PEEP) on lung emptying during passive deflation before and after experimental lung injury. Expiratory time constants (τE) were determined by partitioning the expiratory flow-volume (V˙EV) curve into multiple discrete segments and individually calculating τE for each segment. Under all conditions of PEEP and VT, τE increased throughout expiration both before and after injury. Segmented τE values increased throughout expiration with a slope that was different than zero (P < 0. 01). On average, τE increased by 45.08 msec per segment. When an interaction between injury status and τE segment was included in the model, it was significant (P < 0.05), indicating that later segments had higher τE values post injury than early τE segments. Higher PEEP and VT values were associated with higher τE values. No evidence was found for an interaction between injury status and VT, or PEEP. The current experiment confirms previous observations that τE values are smaller in subjects with injured lungs when compared to controls. We are the first to demonstrate changes in the pattern of τE before and after injury when examined with a multiple compartment model. Finally, increases in PEEP or VT increased τE throughout expiration, but did not appear to have effects that differed between the uninjured and injured state. PMID:26997633

  4. [Study on building index system of risk assessment of post-marketing Chinese patent medicine based on AHP-fuzzy neural network].

    PubMed

    Li, Yuanyuan; Xie, Yanming; Fu, Yingkun

    2011-10-01

    Currently massive researches have been launched about the safety, efficiency and economy of post-marketing Chinese patent medicine (CPM) proprietary Chinese medicine, but it was lack of a comprehensive interpretation. Establishing the risk evaluation index system and risk assessment model of CPM is the key to solve drug safety problems and protect people's health. The clinical risk factors of CPM exist similarities with the Western medicine, can draw lessons from foreign experience, but also have itself multi-factor multivariate multi-level complex features. Drug safety risk assessment for the uncertainty and complexity, using analytic hierarchy process (AHP) to empower the index weights, AHP-based fuzzy neural network to build post-marketing CPM risk evaluation index system and risk assessment model and constantly improving the application of traditional Chinese medicine characteristic is accord with the road and feasible beneficial exploration. PMID:22292377

  5. H Scan/AHP advanced technology proposal evaluation process

    SciTech Connect

    Mack, S.; Valladares, M.R.S. de

    1996-10-01

    It is anticipated that a family of high value/impact projects will be funded by the Hydrogen Program to field test hydrogen technologies that are at advanced stages of development. These projects will add substantial value to the Program in several ways, by: demonstrating successful integration of multiple advanced technologies, providing critical insight on issues of larger scale equipment design, construction and operations management, yielding cost and performance data for competitive analysis, refining and deploying enhanced safety measures. These projects will be selected through a competitive proposal evaluation process. Because of the significant scope and funding levels of projects at these development phases, Program management has indicated the need for an augmented proposal evaluation strategy to ensure that supported projects are implemented by capable investigative teams and that their successful completion will optimally advance programmatic objectives. These objectives comprise a complex set of both quantitative and qualitative factors, many of which can only be estimated using expert judgment and opinion. To meet the above need, the National Renewable Energy Laboratory (NREL) and Energetics Inc. have jointly developed a proposal evaluation methodology called H Scan/AHP. The H Scan component of the process was developed by NREL. It is a two-part survey instrument that substantially augments the type and scope of information collected in a traditional proposal package. The AHP (Analytic Hierarchy Process) component was developed by Energetics. The AHP is an established decision support methodology that allows the Program decision makers to evaluate proposals relatively based on a unique set of weighted criteria that they have determined.

  6. A online credit evaluation method based on AHP and SPA

    NASA Astrophysics Data System (ADS)

    Xu, Yingtao; Zhang, Ying

    2009-07-01

    Online credit evaluation is the foundation for the establishment of trust and for the management of risk between buyers and sellers in e-commerce. In this paper, a new credit evaluation method based on the analytic hierarchy process (AHP) and the set pair analysis (SPA) is presented to determine the credibility of the electronic commerce participants. It solves some of the drawbacks found in classical credit evaluation methods and broadens the scope of current approaches. Both qualitative and quantitative indicators are considered in the proposed method, then a overall credit score is achieved from the optimal perspective. In the end, a case analysis of China Garment Network is provided for illustrative purposes.

  7. The Doubling Theory: Dark Matter and Dark Energy Finally Explained, Speed of Light and Fine Structure Constant Calculated for the First Time

    NASA Astrophysics Data System (ADS)

    Malet, Jean-Pierre Garnier

    2010-09-01

    Developed in previous papers [1, 2, 3, 4, 5], the ``doubling'' (of space and time) theory uses finite horizons of several virtual space-times which are embedded within the observable space-time. A specific fundamental movement creates imperceptible time instants (called ``temporal openings'') in the time flow. Considering different scale levels, it modifies the perception of the time flow and gives to each horizon instantaneous potential futures. This theory explains the cyclical planetary movement in the solar system, the entanglement between particles, the dissymmetry of matter/antimatter and the existence of the dark matter and dark energy. It can also calculate ``for the first time'' universal constants: the speed of light and the fine structure constant.

  8. Two Rice Authentic Histidine Phosphotransfer Proteins, OsAHP1 and OsAHP2, Mediate Cytokinin Signaling and Stress Responses in Rice1[C][W

    PubMed Central

    Sun, Lijing; Zhang, Qian; Wu, Jinxia; Zhang, Liqing; Jiao, Xuewen; Zhang, Shengwei; Zhang, Zhiguo; Sun, Daye; Lu, Tiegang; Sun, Ying

    2014-01-01

    Cytokinin plays an important role in plant development and stress tolerance. Studies of Arabidopsis (Arabidopsis thaliana) have demonstrated that cytokinin acts through a two-component system that includes a histidine (His) kinase, a His phosphotransfer protein (HP), and a response regulator. Phylogenetic analyses have revealed the conservation of His kinases but lineage-specific expansion of HPs and response regulators in rice (Oryza sativa). However, whether the functions of rice HPs have diverged remains unknown. In this study, two rice authentic HPs (OsAHP1 and OsAHP2) were knocked down simultaneously via RNA interference (RNAi), and the transgenic OsAHP-RNAi plants exhibited phenotypes expected for a deficiency in cytokinin signaling, including dwarfism with reduced internode lengths, enhanced lateral root growth, early leaf senescence, and reduced tiller numbers and fertility under natural conditions. The OsAHP-RNAi seedlings were also hyposensitive to exogenous cytokinin. Furthermore, OsAHP-RNAi seedlings were hypersensitive to salt treatment but resistant to osmotic stress relative to wild-type plants. These results indicate that OsAHPs function as positive regulators of the cytokinin signaling pathway and play different roles in salt and drought tolerance in rice. PMID:24578505

  9. 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

  10. Derivation and Inter-relationship of Planck time, the Hubble constant, and Cosmic Microwave Background Radiation from the Neutron and the Quantum Properties of Hydrogen

    NASA Astrophysics Data System (ADS)

    Chakeres, D. W.; Vento, R.; Moses, S. S.; Sauza, J. B.; Andrianarijaona, V. M.

    Planck time, tP, is presently the only fundamental constant that unites the physical domains of c, h, and G, and is therefore a globally defined normalized time constant. This study shows a method to derive tP, H0, G, and the Cosmic Microwave Background Radiation (CMBR) peak spectral radiance from the frequency equivalents of the neutron and the quantum properties of hydrogen such as Rydberg's constant, Bohr radius, electron mass and electron charge. All of the derivations are within the experimental ranges, including errors. Moreover, these results exceed what is experimentally possible because the natural unit data are of high precision. The constants are evaluated within a combined classic integer and harmonic fraction, power law relationship. The logarithmic base of the annihilation frequency of the neutron, approximately 2.27 ×1023 Hz, scales the independent axis to an integer and partial harmonic fraction system. The dependent axis is scaled by the properties of hydrogen. On the line that defines Planck time squared, tP2,there exist unique points directly related to H0, and the CMBR. Therefore these three fundamental cosmic constants are mathematically and conceptually closely inter-related, and each derivable from the others.

  11. 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. PMID:27116620

  12. Evaluation on Electronic Securities Settlements Systems by AHP Methods

    NASA Astrophysics Data System (ADS)

    Fukaya, Kiyoyuki; Komoda, Norihisa

    Accompanying the spread of Internet and the change of business models, electronic commerce expands buisness areas. Electronic finance commerce becomes popular and especially online security tradings becoome very popular in this area. This online securitiy tradings have some good points such as less mistakes than telephone calls. In order to expand this online security tradings, the transfer of the security paper is one the largest problems to be solved. Because it takes a few days to transfer the security paper from a seller to a buyer. So the dematerialization of security papers is one of the solutions. The demterilization needs the information systems for setteling security. Some countries such as France, German, United Kingdom and U.S.A. have been strating the dematerialization projects. The legacy assesments on these projects focus from the viewpoint of the legal schemes only and there is no assessment from system architectures. This paper focuses on the information system scheme and valuates these dematerlization projects by AHP methods from the viewpoints of “dematerializaion of security papers", “speed of transfer", “usefulness on the system" and “accumulation of risks". This is the first case of valuations on security settlements systems by AHP methods, especially four counties’ systems.

  13. 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)…

  14. The Effectiveness of a Constant Time Delay Procedure on Teaching Lifetime Sport Skills to Adolescents with Severe to Profound Intellectual Disabilities.

    ERIC Educational Resources Information Center

    Zhang, Jiabei; And Others

    1995-01-01

    A constant time delay (CTD) procedure was used to teach four adolescents with severe/profound intellectual disabilities to perform bowling, throwing, and putting. Results indicated that the adolescents could be effectively taught gross motor lifetime sport skills with the CTD procedure and that verbal description plus physical assistance could be…

  15. 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,…

  16. Using a Three-Step Decoding Strategy with Constant Time Delay to Teach Word Reading to Students with Mild and Moderate Mental Retardation

    ERIC Educational Resources Information Center

    Tucker Cohen, Elisabeth; Heller, Kathryn Wolff; Alberto, Paul; Fredrick, Laura D.

    2008-01-01

    The use of a three-step decoding strategy with constant time delay for teaching decoding and word reading to students with mild and moderate mental retardation was investigated in this study. A multiple probe design was used to examine the percentage of words correctly decoded and read as well as the percentage of sounds correctly decoded. The…

  17. 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

  18. Heteronuclear correlations by multiple-quantum evolution. II. Proton-proton "decoupling" and multiplicity labeling in a constant-time experiment using carbon detection

    NASA Astrophysics Data System (ADS)

    Batta, Gyula; Kövér, Katalin E.

    Modified Müller-Bolton type heteronuclear multiple-quantum correlation experiments are analyzed theoretically and experimentally. It is shown that the constant-time version offers homonuclear decoupling, multiplicity labeling, and a very efficient suppression of strong coupling artifacts. Such sequences may have advantages for studying macromolecules.

  19. The Effects of Constant Time Delay Embedded into Teaching Activities for Teaching the Names of Clothes for Preschool Children with Developmental Disabilities

    ERIC Educational Resources Information Center

    Odluyurt, Serhat

    2011-01-01

    The general purpose of this study was to examine the effectiveness of constant time delay embedded in activities for teaching clothes name for preschool children with developmental disabilities. This study included four participants having Down syndrome with an age range of 43-46 months. All experimental sessions were conducted in one to one…

  20. 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.

    Theories unifying gravity with other interactions suggest the possibility of spatial and temporal variation of fundamental ``constants'' in the Universe. Using quasar absorption systems we can probe the value of the fine-structure constant, alpha = e2/hbar c, over the history of the universe. Previous studies of three independent samples of data, containing 143 absorption systems spread from 2 to 10 billion years after big bang, hint that alpha was smaller 7 - 11 billion years ago. However competing studies show no such alpha -variation. The studies can be improved by utilising more atomic transitions that are seen in quasar spectra, however in many cases this is hampered by a lack of accurate laboratory frequency measurements. The aim of this paper is to provide a compilation of transitions of importance to the search for alpha variation. They are E1 transitions from the ground state in several different atoms and ions, with wavelengths ranging from around 900 - 6000 Å, and require an accuracy of better than 10-4 Å. We also discuss isotope shift measurements that are needed in order to resolve systematic effects in the study. Researchers who are interested in performing these measurements should contact the authors directly.

  1. A comparison between constant volume induction times and results from spatially resolved simulation of ignition behind reflected shocks: implications for shock tube experiments

    NASA Astrophysics Data System (ADS)

    Melguizo-Gavilanes, J.; Bauwens, L.

    2013-05-01

    The induction time measured in shock tube experiments is typically converted into kinetic data assuming that the reaction takes place in a constant volume process, thus neglecting spatial gradients. The actual process of shock ignition is, however, both time- and space-dependent; ignition takes place at a well-defined location, and subsequently a front travels, which may couple with the pressure wave that it created and forms a detonation wave behind the shock that reflects off the wall. To assess how different the actual processes are compared with the constant volume assumption, a numerical study was performed using a simplified three step chain-branching kinetic scheme. To overcome the difficulties that arise when simulating shock-induced ignition due to the initial absence of a domain filled with shocked reactive mixture, the problem is solved in a transformed frame of reference. Furthermore, initial conditions are derived from short-time asymptotics, which resolves the initial singularity. The induction times obtained using the full unsteady formulation with those of the homogeneous explosion are compared for various values of the heat release. Results for the spatially dependent formulation show that the evolution of the post-shock flow is complex, and that it leads to a gradient in induction times, after the passage of the reflected shock. For all cases simulated, thermal explosion initially occurs very close to the wall, and the corresponding induction time is found to be larger than that predicted under the constant volume assumption. As the measurement is made further away however, the actual time interval between passage of the reflected shock, and the specified pressure increase denoting ignition, decreases to a value close to zero, corresponding to that obtained along a Rayleigh line matching that of a steady ZND process (assuming a long enough tube). In situations where the constant volume assumption is expected to be weak, more accurate kinetic data

  2. Optimal generation scheduling based on AHP/ANP.

    PubMed

    Momoh, J A; Zhu, Jizhong

    2003-01-01

    This paper proposes an application of the analytic hierarchy process (AHP) and analytic network process (ANP) for enhancing the selection of generating power units for appropriate price allocation in a competitive power environment. The scheme addresses adequate ranking, prioritizing, and scheduling of units before optimizing the pricing of generation units to meet a given demand. In the deregulated environment, the classical optimization techniques will be insufficient for the above-mentioned purpose. Hence, by incorporating the interaction of factors such as load demand, generating cost curve, bid/sale price, unit up/down cost, and the relative importance of different generation units, the scheme can be implemented to address the technical and nontechnical constraints in unit commitment problems. This information is easily augmented with the optimization scheme for an effective optimal decision. The scheme proposed is tested using the IEEE 39-bus test system. PMID:18238201

  3. Regulation of the ahpC Gene Encoding Alkyl Hydroperoxide Reductase in Mycobacterium smegmatis

    PubMed Central

    Lee, Ha-Na; Lee, Na-On; Han, Seung J.; Ko, In-Jeong; Oh, Jeong-Il

    2014-01-01

    The ahpC (MSMEG_4891) gene encodes alkyl hydroperoxide reductase C in Mycobacterium smegmatis mc2155 and its expression is induced under oxidative stress conditions. Two well-defined inverted repeat sequences (IR1 and IR2) were identified in the upstream region of ahpC. Using a crp (cAMP receptor protein: MSMEG_6189) mutant and in vitro DNA-binding assay, it was demonstrated that the IR1 sequence serves as a Crp-binding site and that Crp functions as an activator in the regulation of ahpC expression. The expression level of ahpC was shown to be proportional to intracellular cAMP levels. Intracellular levels of cAMP were increased in M. smegmatis, when it was treated with oxidative stress inducers. The IR2 sequence is very similar to the known consensus sequence of FurA-binding sites and involved in the negative regulation of ahpC expression. Taken together, these results suggest that the induction of ahpC expression under oxidative stress conditions probably results from a combinatory effect of both inactivation of FurA by oxidative stress and activation of Crp in response to increased levels of cAMP. PMID:25365321

  4. Constant Energy of Time Involute Particles of Biharmonic Particles in Bianchi Type-I Cosmological Model Spacetime

    NASA Astrophysics Data System (ADS)

    Körpinar, Talat; Turhan, Essin

    2015-05-01

    In this paper, we study energy of time involute particles of biharmonic particles in Bianchi type-I (B-I) cosmological model spacetime. We give a geometrical description of energy for a Frenet vector fields of timelike biharmonic particle. Finally, using the Frenet frame of the given particle, we obtain different cases for this particles and give important characterizations about them in Bianchi type-I (B-I) cosmological model spacetime.

  5. 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.

  6. Constraint on the time variation of the fine-structure constant with the SDSS-III/BOSS DR12 quasar sample

    NASA Astrophysics Data System (ADS)

    Albareti, Franco D.; Comparat, Johan; Gutiérrez, Carlos M.; Prada, Francisco; Pâris, Isabelle; Schlegel, David; López-Corredoira, Martín; Schneider, Donald P.; Manchado, Arturo; García-Hernández, D. A.; Petitjean, Patrick; Ge, Jian

    2015-10-01

    From the Sloan Digital Sky Survey (SDSS) Data Release 12, which covers the full Baryonic Oscillation Spectroscopic Survey (BOSS) footprint, we investigate the possible variation of the fine-structure constant over cosmological time-scales. We analyse the largest quasar sample considered so far in the literature, which contains 13 175 spectra (10 363 from SDSS-III/BOSS DR12 + 2812 from SDSS-II DR7) with redshift z < 1. We apply the emission-line method on the [O III] doublet (λλ 4960, 5008 Å) and obtain Δα/α = (0.9 ± 1.8) × 10-5 for the relative variation of the fine-structure constant. We also investigate the possible sources of systematics: misidentification of the lines, sky OH lines, H β and broad line contamination, Gaussian and Voigt fitting profiles, optimal wavelength range for the Gaussian fits, chosen polynomial order for the continuum spectrum, signal-to-noise ratio and good quality of the fits. The uncertainty of the measurement is dominated by the sky subtraction. The results presented in this work, being systematics limited, have sufficient statistics to constrain robustly the variation of the fine-structure constant in redshift bins (Δz ≈ 0.06) over the last 7.9 Gyr. In addition, we study the [Ne III] doublet (λλ 3869, 3968 Å) present in 462 quasar spectra and discuss the systematic effects on using these emission lines to constrain the fine-structure constant variation. Better constraints on Δα/α (< 10-6) using the emission-line method would be possible with high-resolution spectroscopy and large galaxy/qso surveys.

  7. Application of Fuzzy AHP and ELECTRE to Network Selection

    NASA Astrophysics Data System (ADS)

    Charilas, Dimitris E.; Markaki, Ourania I.; Psarras, John; Constantinou, Philip

    In a heterogeneous wireless network environment services are ubiquitously delivered over multiple wireless access technologies. Ranking of the alternatives and selection of the most efficient and suitable access network to meet the QoS requirements of a specific service, as these are defined by the user, constitutes thus an important issue. Decisions on which network to connect to are however difficult to be reached, since multiple factors of different relative importance have to be taken into consideration. This paper addresses this difficulty by adopting Multi Attribute Decision Making (MADM) methods. Fuzzy AHP, a MADM method, is initially applied to determine the weights of certain Quality of Service indicators that act as the criteria impacting the decision process. The fuzzy extension of the method, and consequently the use of fuzzy numbers, is adopted in order to incorporate the existence of fuzziness as a result of subjective evaluations. Afterwards, ELECTRE, a ranking MADM method, is applied to rank the alternatives, in this case wireless networks, based on their overall performance.

  8. Experimental investigation of the excess charge and time constant of minority carriers in the thin diffused layer of 0.1 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Brandhorst, H. W., Jr.; Lindholm, F. A.; Sah, C. T.

    1976-01-01

    An experimental method is presented that can be used to interpret the relative roles of bandgap narrowing and recombination processes in the diffused layer. This method involves measuring the device time constant by open-circuit voltage decay and the base region diffusion length by X-ray excitation. A unique illuminated diode method is used to obtain the diode saturation current. These data are interpreted using a simple model to determine individually the minority carrier lifetime and the excess charge. These parameters are then used to infer the relative importance of bandgap narrowing and recombination processes in the diffused layer.

  9. 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.

  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 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

  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. Frequency Ratio of Two Optical Clock Transitions in Yb+ 171 and Constraints on the Time Variation of Fundamental Constants

    NASA Astrophysics Data System (ADS)

    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.

    2014-11-01

    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 Yb+ 171 . The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of 6 ×1 0-16. 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 )×1 0-16 yr-1 , along with an improved constraint on time variation of the fine structure constant, α ˙ /α =-0.7 (2.1 )×1 0-17 yr-1 .

  14. An Integrated Approach of Fuzzy Linguistic Preference Based AHP and Fuzzy COPRAS for Machine Tool Evaluation

    PubMed Central

    Nguyen, Huu-Tho; Md Dawal, Siti Zawiah; Nukman, Yusoff; Aoyama, Hideki; Case, Keith

    2015-01-01

    Globalization of business and competitiveness in manufacturing has forced companies to improve their manufacturing facilities to respond to market requirements. Machine tool evaluation involves an essential decision using imprecise and vague information, and plays a major role to improve the productivity and flexibility in manufacturing. The aim of this study is to present an integrated approach for decision-making in machine tool selection. This paper is focused on the integration of a consistent fuzzy AHP (Analytic Hierarchy Process) and a fuzzy COmplex PRoportional ASsessment (COPRAS) for multi-attribute decision-making in selecting the most suitable machine tool. In this method, the fuzzy linguistic reference relation is integrated into AHP to handle the imprecise and vague information, and to simplify the data collection for the pair-wise comparison matrix of the AHP which determines the weights of attributes. The output of the fuzzy AHP is imported into the fuzzy COPRAS method for ranking alternatives through the closeness coefficient. Presentation of the proposed model application is provided by a numerical example based on the collection of data by questionnaire and from the literature. The results highlight the integration of the improved fuzzy AHP and the fuzzy COPRAS as a precise tool and provide effective multi-attribute decision-making for evaluating the machine tool in the uncertain environment. PMID:26368541

  15. Using Python to generate AHPS-based precipitation simulations over CONUS using Amazon distributed computing

    NASA Astrophysics Data System (ADS)

    Machalek, P.; Kim, S. M.; Berry, R. D.; Liang, A.; Small, T.; Brevdo, E.; Kuznetsova, A.

    2012-12-01

    We describe how the Climate Corporation uses Python and Clojure, a language impleneted on top of Java, to generate climatological forecasts for precipitation based on the Advanced Hydrologic Prediction Service (AHPS) radar based daily precipitation measurements. A 2-year-long forecasts is generated on each of the ~650,000 CONUS land based 4-km AHPS grids by constructing 10,000 ensembles sampled from a 30-year reconstructed AHPS history for each grid. The spatial and temporal correlations between neighboring AHPS grids and the sampling of the analogues are handled by Python. The parallelization for all the 650,000 CONUS stations is further achieved by utilizing the MAP-REDUCE framework (http://code.google.com/edu/parallel/mapreduce-tutorial.html). Each full scale computational run requires hundreds of nodes with up to 8 processors each on the Amazon Elastic MapReduce (http://aws.amazon.com/elasticmapreduce/) distributed computing service resulting in 3 terabyte datasets. We further describe how we have productionalized a monthly run of the simulations process at full scale of the 4km AHPS grids and how the resultant terabyte sized datasets are handled.

  16. An Integrated Approach of Fuzzy Linguistic Preference Based AHP and Fuzzy COPRAS for Machine Tool Evaluation.

    PubMed

    Nguyen, Huu-Tho; Md Dawal, Siti Zawiah; Nukman, Yusoff; Aoyama, Hideki; Case, Keith

    2015-01-01

    Globalization of business and competitiveness in manufacturing has forced companies to improve their manufacturing facilities to respond to market requirements. Machine tool evaluation involves an essential decision using imprecise and vague information, and plays a major role to improve the productivity and flexibility in manufacturing. The aim of this study is to present an integrated approach for decision-making in machine tool selection. This paper is focused on the integration of a consistent fuzzy AHP (Analytic Hierarchy Process) and a fuzzy COmplex PRoportional ASsessment (COPRAS) for multi-attribute decision-making in selecting the most suitable machine tool. In this method, the fuzzy linguistic reference relation is integrated into AHP to handle the imprecise and vague information, and to simplify the data collection for the pair-wise comparison matrix of the AHP which determines the weights of attributes. The output of the fuzzy AHP is imported into the fuzzy COPRAS method for ranking alternatives through the closeness coefficient. Presentation of the proposed model application is provided by a numerical example based on the collection of data by questionnaire and from the literature. The results highlight the integration of the improved fuzzy AHP and the fuzzy COPRAS as a precise tool and provide effective multi-attribute decision-making for evaluating the machine tool in the uncertain environment. PMID:26368541

  17. Field and polarity dependence of time-to-resistance increase in Fe-O films studied by constant voltage stress method

    NASA Astrophysics Data System (ADS)

    Eriguchi, Koji; Wei, Zhiqiang; Takagi, Takeshi; Ohta, Hiroaki; Ono, Kouichi

    2009-01-01

    Constant voltage stress (CVS) was applied to Fe-O films prepared by a sputtering process to investigate a stress-induced resistance increase leading to a fundamental mechanism for switching behaviors. Under the CVS, an abrupt resistance increase was found for both stress polarities. A conduction mechanism after the resistance increase exhibited non-Ohmic transport. The time-to-resistance increase (tr) under the CVS was revealed to strongly depend on stress voltage as well as the polarity. From a polarity-dependent resistance increase determined by a time-zero measurement, the voltage and polarity-dependent tr were discussed on the basis of field- and structure-enhanced thermochemical reaction mechanisms.

  18. Field and polarity dependence of time-to-resistance increase in Fe-O films studied by constant voltage stress method

    SciTech Connect

    Eriguchi, Koji; Ohta, Hiroaki; Ono, Kouichi; Wei Zhiqiang; Takagi, Takeshi

    2009-01-05

    Constant voltage stress (CVS) was applied to Fe-O films prepared by a sputtering process to investigate a stress-induced resistance increase leading to a fundamental mechanism for switching behaviors. Under the CVS, an abrupt resistance increase was found for both stress polarities. A conduction mechanism after the resistance increase exhibited non-Ohmic transport. The time-to-resistance increase (t{sub r}) under the CVS was revealed to strongly depend on stress voltage as well as the polarity. From a polarity-dependent resistance increase determined by a time-zero measurement, the voltage and polarity-dependent t{sub r} were discussed on the basis of field- and structure-enhanced thermochemical reaction mechanisms.

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

    SciTech Connect

    Shavorskiy, Andrey; Slaughter, Daniel S.; Zegkinoglou, Ioannis; Rude, Bruce S.; Bluhm, Hendrik; Neppl, Stefan; Cryan, James P.; Siefermann, Katrin R.; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P.; Fraund, Matthew W.; Khurmi, Champak; Wright, Travis W.; Schoenlein, Robert W.; Gessner, Oliver; Hertlein, Marcus P.; Tyliszczak, Tolek; Huse, Nils; and others

    2014-09-15

    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{sub 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

  20. 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.

  1. Full solution, for crystal class 3m, of the Holland-EerNisse complex material-constant theory of lossy piezoelectrics for harmonic time dependence.

    PubMed

    Piquette, Jean C; McLaughlin, Elizabeth A

    2007-06-01

    A complex material-constant theory of lossy piezoelectrics is fully solved for crystal class 3m for harmonic time dependence of the fields and stresses. A new demonstration that the theory's eigen coupling factor equation applies to the lossy alternating current (AC) case also is given. The solution presented for crystal class 3m provides a complete orthonormal set of eigenvectors and eigenvalues for the eigen coupling factor problem, and it also provides a complete orthonormal set of eigenvectors and eigenvalues for the eigen loss tangent problem, for this crystal class. It is shown that two positive coupling factors are sufficient to express an arbitrary 3m crystal state. Despite the complex nature of the material constants, the Holland-EerNisse theory produces fully real expressions for the coupling factors. The loss tangent eigenvalues also are fully real and positive. The loss eigenstates are important because driving a crystal in a loss eigenstate tends to minimize the impact of material losses. Given also is a set of loss inequalities for crystal class 3m. The loss inequalities of crystal class 6mm are recovered from these when d22 and s(E)14 both vanish. PMID:17571823

  2. 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

  3. Broad specificity AhpC-like peroxiredoxin and its thioredoxin reductant in the sparse antioxidant defense system of Treponema pallidum

    PubMed Central

    Parsonage, Derek; Desrosiers, Daniel C.; Hazlett, Karsten R. O.; Sun, Yongcheng; Nelson, Kimberly J.; Cox, David L.; Radolf, Justin D.; Poole, Leslie B.

    2010-01-01

    Little is known about the mechanisms by which Treponema pallidum (Tp), the causative agent of syphilis, copes with oxidative stress as it establishes persistent infection within its obligate human host. The Tp genomic sequence indicates that the bacterium’s antioxidant defenses do not include glutathione and are limited to just a few proteins, with only one, TP0509, offering direct defense against peroxides. Although this Tp peroxiredoxin (Prx) closely resembles AhpC-like Prxs, Tp lacks AhpF, the typical reductant for such enzymes. Functionally, TpAhpC resembles largely eukaryotic, nonAhpC typical 2-Cys Prx proteins in using thioredoxin (Trx, TP0919) as an efficient electron donor and exhibiting broad specificity toward hydroperoxide substrates. Unlike many of the eukaryotic Prxs, however, TpAhpC is relatively resistant to inactivation during turnover with hydroperoxide substrates. As is often observed in typical 2-Cys Prxs, TpAhpC undergoes redox-sensitive oligomer formation. Quantitative immunoblotting revealed that TpTrx and TpAhpC are present at very high levels (over 100 and 300 μM, respectively) in treponemes infecting rabbit testes; their redox potentials, at -242 ± 1 and -192 ± 2 mV, respectively, are consistent with the role of TpTrx as the cellular reductant of TpAhpC. Transcriptional analysis of select antioxidant genes confirmed the presence of high mRNA levels for ahpC and trx which diminish greatly when spirochetes replicate under in vitro growth conditions. Thus, T. pallidum has evolved an extraordinarily robust, broad-spectrum AhpC as its sole mechanism for peroxide defense to combat this significant threat to treponemal growth and survival during infection. PMID:20304799

  4. Molecular Analysis of Promoter and Intergenic Region Attenuator of the Vibrio vulnificus prx1ahpF Operon.

    PubMed

    Lee, Hyun Sung; Lim, Jong Gyu; Han, Kook; Lee, Younghoon; Choi, Sang Ho

    2015-08-01

    Prx1, an AhpF-dependent 2-Cys peroxiredoxin (Prx), was previously identified in Vibrio vulnificus, a facultative aerobic pathogen. In the present study, transcription of the V. vulnificus prx1ahpF genes, which are adjacently located on the chromosome, was evaluated by analyzing the promoter and intergenic region of the two genes. Northern blot analyses revealed that transcription of prx1ahpF results in two transcripts, the prx1 and prx1ahpF transcripts. Primer extension analysis and a point mutational analysis of the promoter region showed that the two transcripts are generated from a single promoter. In addition, the 3' end of the prx1 transcript at the prx1ahpF intergenic region was determined by a 3'RACE assay. These results suggested that the prx1ahpF genes are transcribed as an operon, and the prx1 transcript was produced by transcriptional termination in the intergenic region. RNA secondary structure prediction of the prx1ahpF intergenic region singled out a stem-loop structure without poly(U) tract, and a deletion analysis of the intergenic region showed that the atypical stem-loop structure acts as the transcriptional attenuator to result in the prx1 and prx1ahpF transcripts. The combined results demonstrate that the differential expression of prx1 and ahpF is accomplished by the cis-acting transcriptional attenuator located between the two genes and thereby leads to the production of a high level of Prx1 and a low level of AhpF. PMID:25824432

  5. 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.

  6. Environmental quality indexing of large industrial development alternatives using AHP

    SciTech Connect

    Solnes, Julius

    2003-05-01

    Two industrial development alternatives have been proposed for the East Coast of Iceland in order to strengthen its socio-economic basis. The favoured option is to build a large aluminium smelter, which requires massive hydropower development in the nearby highlands. Another viable option is the construction of a 6-million-ton oil refinery, following the planned exploitation of the Timan Pechora oil reserves in the Russian Arctic. A third 'fictitious' alternative could be general development of existing regional industry and new knowledge-based industries, development of ecotourism, establishment of national parks, accompanied by infrastructure improvement (roads, tunnels, communications, schools, etc.). The three alternatives will have different environmental consequences. The controversial hydropower plant for the smelter requires a large water reservoir as well as considerable land disturbance in this unique mountain territory, considered to be the largest uninhabited wilderness in Western Europe. The aluminium smelter and the oil refinery will give rise to substantial increase of the greenhouse gas (GHG) emissions of the country (about 20%). Then there is potential environmental risk associated with the refinery regarding oil spills at sea, which could have disastrous impact on the fisheries industry. However, the oil refinery does not require any hydropower development, which is a positive factor. Finally, the third alternative could be defined as a ''green'' solution whereby the detrimental environmental consequences of the two industrial solutions are mostly avoided. In order to compare the three alternatives in an orderly manner, the analytic hierarchy process methodology of Saaty was applied to calculate the environmental quality index of each alternative, which is defined as a weighted sum of selected environmental and socio-economic factors. These factors are evaluated on a comparison basis, applying the AHP methodology, and the weights in the quality

  7. 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

  8. Structure of nitrogen-converting communities induced by hydraulic retention time and COD/N ratio in constantly aerated granular sludge reactors treating digester supernatant.

    PubMed

    Cydzik-Kwiatkowska, Agnieszka; Rusanowska, Paulina; Zielińska, Magdalena; Bernat, Katarzyna; Wojnowska-Baryła, Irena

    2014-02-01

    This study investigated how hydraulic retention time (HRT) and COD/N ratio affect nitrogen-converting consortia in constantly aerated granules treating high-ammonium digester supernatant. Three HRTs (10, 13, 19 h) were tested at COD/N ratios of 4.5 and 2.3. Denaturing gradient gel electrophoresis and relative real-time PCR were used to characterize the microbial communities. When changes in HRT and COD/N increased nitrogen loading, the ratio of the relative abundance of aerobic to anaerobic ammonium-oxidizers decreased. The COD/N ratio determined the species composition of the denitrifiers; however, Thiobacillus denitrificans, Pseudomonas denitrificans and Azoarcus sp. showed a high tolerance to the environmental conditions and occurred in the granules from all reactors. Denitrifier genera that support granule formation were identified, such as Pseudomonas, Shinella, and Flavobacterium. In aerated granules, nirK-possessing bacteria were more diverse than nirS-possessing bacteria. At a low COD/N ratio, N2O-reducer diversity increased because of the presence of bacteria known as aerobic denitrifiers. PMID:24384323

  9. 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.

  10. 12 CFR 1291.2 - Required annual AHP contributions; allocation of contributions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 9 2012-01-01 2012-01-01 false Required annual AHP contributions; allocation... its Program the greater of: (1) 10 percent of the Bank's net earnings for the previous year; or (2..., such proration being made on the basis of the net earnings of the Banks for the previous year,...

  11. An AHP-Based Weighted Analysis of Network Knowledge Management Platforms for Elementary School Students

    ERIC Educational Resources Information Center

    Lee, Chung-Ping; Lou, Shi-Jer; Shih, Ru-Chu; Tseng, Kuo-Hung

    2011-01-01

    This study uses the analytical hierarchy process (AHP) to quantify important knowledge management behaviors and to analyze the weight scores of elementary school students' behaviors in knowledge transfer, sharing, and creation. Based on the analysis of Expert Choice and tests for validity and reliability, this study identified the weight scores of…

  12. Study on the Higher Vocational Mode Combining Production with Learning and Research Based on AHP

    ERIC Educational Resources Information Center

    Li, Yanming; Li, Jin; Zhang, Xiumei

    2009-01-01

    In this article, we applied the AHP method with quantitative analysis and qualitative analysis to analyze three sorts of basic educational mode combining production with learning and research, i.e. the automated instruction, the mode combining production and learning, and the integration combining production with learning and research, and…

  13. 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

  14. 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. PMID:23526167

  15. Serum Helicobacter pylori KatA and AhpC antibodies as novel biomarkers for gastric cancer

    PubMed Central

    Zhang, Bing; Li, Hai-Lin; Fan, Qing; Guo, Fang; Ren, Xi-Yun; Zhou, Hai-Bo; Zhu, Ji-Wei; Zhao, Ya-Shuang; Tian, Wen-Jing

    2016-01-01

    AIM: To investigate catalase (KatA) and alkyl hydroperoxide reductase (AhpC) antibodies of Helicobacter pylori as biomarkers for gastric cancer (GC). METHODS: This study included 232 cases and 264 controls. Recombinant KatA and AhpC proteins were constructed and the levels of antibodies were tested by indirect enzyme-linked immunosorbent assay (ELISA). Logistic regression was applied to analyze the relationships between KatA, AhpC and GC. The χ2 trend test was used to evaluate the dose-response relationships between serum KatA and AhpC antibody levels and GC. Receiver operating characteristic (ROC) curve was used to evaluate the screening accuracy of KatA and AhpC as biomarkers. Combined analysis was used to observe screening accuracy of predictors for GC. RESULTS: In all subjects, the association between KatA and AhpC and GC risk was significant (P < 0.001) with odds ratio (OR) = 12.84 (95%CI: 7.79-21.15) and OR = 2.4 (95%CI: 1.55-3.73), respectively. KatA and AhpC antibody levels were strongly related to GC risk with a dose-dependent effect (P for trend < 0.001). The area under the ROC (AUC) for KatA was 0.806, providing a sensitivity of 66.81% and specificity of 86.36%; and the AUC for AhpC was 0.615, with a sensitivity of 75.65% and specificity of 45.49%. The AUC was 0.906 for KatA and flagella protein A (FlaA) combined analysis. CONCLUSION: Serum KatA and AhpC antibodies are associated with GC risk and KatA may serve as a biomarker for GC. KatA/FlaA combined analysis improved screening accuracy. PMID:27275098

  16. Connecting Fundamental Constants

    SciTech Connect

    Di Mario, D.

    2008-05-29

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

  17. Integrated multi-criteria decision making techniques AHP with Geographic Information System for Modelling of suitable Landfill location: a case study in Keraniganj of Dhaka city, Bangladesh.

    NASA Astrophysics Data System (ADS)

    Iqbal, M.

    2015-12-01

    This study is approaches a GIS based multi-criteria decision making technique to select potential land fill in Keraniganj of Dhaka city in Bangladesh. Site selection of landfill for Municipal solid waste is an important concern for the urban government in whole world. Dhaka city is highly dense populated city in Bangladesh and municipal solid waste generation rate is increase rapidly day by day. These large amount of generated municipal waste needs appropriate landfill considering environmental, geological, social and technical aspect of the region. The traditional process of site selection process is much difficult, time consuming and costly and needs to replace by a new approaches. An integration of Geographical Information System (GIS) and Multi-criteria Evaluation (MCE) method is best combination to solve complex decision and used to select suitable site. Analytical Hierarchy process (AHP) is world widely most popular decision making MCE technique. In this study AHP used as a multi-criteria decision making to compare five suitability attributes with each other and evaluate weight according to attributes potentiality. Various type raster map layer created using GIS tool for this study. Five suitability raster was assigned with the AHP calculated weight value. A combined weighted spatial layer obtained name as suitability map which is overlapped with a restriction raster map, as result a final suitable map was obtained. The result shows that 12.2% of the area is suitable for constructing landfill site where 4.9% is very high suitable, 2.6% is moderate suitable and 4.7% is low suitable. The final site is constructed after detail field investigation, other technical investigation, land ownership status and public acceptancy. Suitable site selection for non-hazardous landfill is not easy and its needs to consider many environmental factor at time. GIS tool combining with many decision making tool such as multi-criteria evaluation can solve this problem. A combining

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

    PubMed

    Tagusari, Junta; Matsui, Toshihito

    2016-04-01

    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

  19. 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

  20. 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

  1. Seven Novel Mutations in Bulgarian Patients with Acute Hepatic Porphyrias (AHP).

    PubMed

    Dragneva, Sonya; Szyszka-Niagolov, Monika; Ivanova, Aneta; Mateva, Lyudmila; Izumi, Rumiko; Aoki, Yoko; Matsubara, Yoichi

    2014-01-01

    Acute intermittent porphyria (AIP), variegate porphyria (VP), and hereditary coproporphyria (HCP) are caused by mutations in the hydroxymethylbilane synthase (HMBS), protoporphyrinogen oxidase (PPOX), and coproporphyrinogen oxidase (CPOX) genes, respectively. This study aimed to identify mutations in seven Bulgarian families with AIP, six with VP, and one with HCP. A total of 33 subjects, both symptomatic (n = 21) and asymptomatic (n = 12), were included in this study. The identification of mutations was performed by direct sequencing of all the coding exons of the corresponding enzymes in the probands. The available relatives were screened for the possible mutations. A total of six different mutations in HMBS were detected in all seven families with AIP, three of which were previously described: c.76C>T [p.R26C] in exon 3, c.287C>T [p.S96F] in exon 7, and c.445C>T [p.R149X] in exon 9. The following three novel HMBS mutations were found: c.345-2A>C in intron 7-8, c.279-280insAT in exon 7, and c.887delC in exon 15. A total of three different novel mutations were identified in the PPOX gene in the VP families: c.441-442delCA in exon 5, c.917T>C [p.L306P] in exon 9, and c.1252T>C [p.C418R] in exon 12. A novel nonsense mutation, c.364G>T [p.E122X], in exon 1 of the CPOX gene was identified in the HCP family. This study, which identified mutations in Bulgarian families with AHP for the first time, established seven novel mutation sites. Seven latent carriers were also diagnosed and, therefore, were able to receive crucial counseling to prevent attacks. PMID:24997713

  2. New Quasar Studies Keep Fundamental Physical Constant Constant

    NASA Astrophysics Data System (ADS)

    2004-03-01

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

  3. Characterization of the Mycobacterium tuberculosis H37Rv alkyl hydroperoxidase AhpC points to the importance of ionic interactions in oligomerization and activity.

    PubMed Central

    Chauhan, R; Mande, S C

    2001-01-01

    An alkyl hydroperoxidase (AhpC) has been found frequently to be overexpressed in isoniazid-resistant strains of Mycobacterium tuberculosis. These strains have an inactivated katG gene encoding a catalase peroxidase, which might render mycobacteria susceptible to the toxic peroxide radicals, thus leading to the concomitant overexpression of the AhpC. Although the overexpressed AhpC in isoniazid-resistant strains of M. tuberculosis may not directly participate in isoniazid action, AhpC might still assist M. tuberculosis in combating oxidative damage in the absence of the catalase. Here we have attempted to characterize the AhpC protein biochemically and report its functional and oligomerization properties. The alkyl hydroperoxidase of M. tuberculosis is unique in many ways compared with its well-characterized homologues from enteric bacteria. We show that AhpC is a decameric protein, composed of five identical dimers held together by ionic interactions. Dimerization of individual subunits takes place through an intersubunit disulphide linkage. The ionic interactions play a significant role in enzymic activity of the AhpC protein. The UV absorption spectrum and three-dimensional model of AhpC suggest that interesting conformational changes may take place during oxidation and reduction of the intersubunit disulphide linkage. In the absence of the partner AhpF subunit in M. tuberculosis, the mycobacterial AhpC might use small-molecule reagents, such as mycothiol, for completing its enzymic cycle. PMID:11171096

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

    PubMed

    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 (2)JHH 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. PMID:24365099

  5. A combination of extended fuzzy AHP and fuzzy GRA for government E-tendering in hybrid fuzzy environment.

    PubMed

    Wang, Yan; Xi, Chengyu; Zhang, Shuai; Yu, Dejian; Zhang, Wenyu; Li, Yong

    2014-01-01

    The recent government tendering process being conducted in an electronic way is becoming an inevitable affair for numerous governmental agencies to further exploit the superiorities of conventional tendering. Thus, developing an effective web-based bid evaluation methodology so as to realize an efficient and effective government E-tendering (GeT) system is imperative. This paper firstly investigates the potentiality of employing fuzzy analytic hierarchy process (AHP) along with fuzzy gray relational analysis (GRA) for optimal selection of candidate tenderers in GeT process with consideration of a hybrid fuzzy environment with incomplete weight information. We proposed a novel hybrid fuzzy AHP-GRA (HFAHP-GRA) method that combines an extended fuzzy AHP with a modified fuzzy GRA. The extended fuzzy AHP which combines typical AHP with interval AHP is proposed to obtain the exact weight information, and the modified fuzzy GRA is applied to aggregate different types of evaluation information so as to identify the optimal candidate tenderers. Finally, a prototype system is built and validated with an illustrative example for GeT to confirm the feasibility of our approach. PMID:25057506

  6. A Combination of Extended Fuzzy AHP and Fuzzy GRA for Government E-Tendering in Hybrid Fuzzy Environment

    PubMed Central

    Wang, Yan; Xi, Chengyu; Zhang, Shuai; Yu, Dejian; Zhang, Wenyu; Li, Yong

    2014-01-01

    The recent government tendering process being conducted in an electronic way is becoming an inevitable affair for numerous governmental agencies to further exploit the superiorities of conventional tendering. Thus, developing an effective web-based bid evaluation methodology so as to realize an efficient and effective government E-tendering (GeT) system is imperative. This paper firstly investigates the potentiality of employing fuzzy analytic hierarchy process (AHP) along with fuzzy gray relational analysis (GRA) for optimal selection of candidate tenderers in GeT process with consideration of a hybrid fuzzy environment with incomplete weight information. We proposed a novel hybrid fuzzy AHP-GRA (HFAHP-GRA) method that combines an extended fuzzy AHP with a modified fuzzy GRA. The extended fuzzy AHP which combines typical AHP with interval AHP is proposed to obtain the exact weight information, and the modified fuzzy GRA is applied to aggregate different types of evaluation information so as to identify the optimal candidate tenderers. Finally, a prototype system is built and validated with an illustrative example for GeT to confirm the feasibility of our approach. PMID:25057506

  7. Seismic vulnerability assessment of school buildings in Tehran city based on AHP and GIS

    NASA Astrophysics Data System (ADS)

    Panahi, M.; Rezaie, F.; Meshkani, S. A.

    2013-09-01

    The objective of the study was to evaluate the seismic vulnerability of school buildings in Tehran city based on analytical hierarchical process (AHP) and geographical information systems (GIS). Therefore, to this end, the peak ground acceleration, slope and soil liquefaction layers were used for preparation geotechnical map. Also, the construction materials of structures, year of construction, their quality and seismic resonance coefficient layers were defined as major affecting factors in structural vulnerability of schools. Then, the AHP method was applied to assess the priority rank and weight of criteria (layers) and alternatives (classes) of each criterion through pair wise comparison in all levels. Finally, geotechnical and structural spatial layers were overlaid to prepare the seismic vulnerability map of school buildings in Tehran city. The results indicated that only in 72 schools (about 3%) out of 2125 schools in the study area, the destruction rate is very high and therefore their reconstruction should be considered.

  8. Seismic vulnerability assessment of school buildings in Tehran city based on AHP and GIS

    NASA Astrophysics Data System (ADS)

    Panahi, M.; Rezaie, F.; Meshkani, S. A.

    2014-04-01

    The objective of the current study is to evaluate the seismic vulnerability of school buildings in Tehran city based on the analytic hierarchy process (AHP) and geographical information system (GIS). To this end, the peak ground acceleration, slope, and soil liquefaction layers were utilized for developing a geotechnical map. Also, the construction materials of structures, age of construction, the quality, and the seismic resonance coefficient layers were defined as major factors affecting the structural vulnerability of school buildings. Then, the AHP method was applied to assess the priority rank and weight of criteria (layers) and alternatives (classes) of each criterion via pairwise comparison in all levels. Finally, the geotechnical and structural spatial layers were overlaid to develop the seismic vulnerability map of school buildings in Tehran. The results indicated that only in 72 (about 3%) out of 2125 school buildings of the study area will the destruction rate be very high and therefore their reconstruction should seriously be considered.

  9. Comparison of fuzzy AHP and fuzzy TODIM methods for landfill location selection.

    PubMed

    Hanine, Mohamed; Boutkhoum, Omar; Tikniouine, Abdessadek; Agouti, Tarik

    2016-01-01

    Landfill location selection is a multi-criteria decision problem and has a strategic importance for many regions. The conventional methods for landfill location selection are insufficient in dealing with the vague or imprecise nature of linguistic assessment. To resolve this problem, fuzzy multi-criteria decision-making methods are proposed. The aim of this paper is to use fuzzy TODIM (the acronym for Interactive and Multi-criteria Decision Making in Portuguese) and the fuzzy analytic hierarchy process (AHP) methods for the selection of landfill location. The proposed methods have been applied to a landfill location selection problem in the region of Casablanca, Morocco. After determining the criteria affecting the landfill location decisions, fuzzy TODIM and fuzzy AHP methods are applied to the problem and results are presented. The comparisons of these two methods are also discussed. PMID:27186465

  10. Integration of QFD, AHP, and LPP methods in supplier development problems under uncertainty

    NASA Astrophysics Data System (ADS)

    Shad, Zahra; Roghanian, Emad; Mojibian, Fatemeh

    2014-04-01

    Quality function deployment (QFD) is a customer-driven approach, widely used to develop or process new product to maximize customer satisfaction. Last researches used linear physical programming (LPP) procedure to optimize QFD; however, QFD issue involved uncertainties, or fuzziness, which requires taking them into account for more realistic study. In this paper, a set of fuzzy data is used to address linguistic values parameterized by triangular fuzzy numbers. Proposed integrated approach including analytic hierarchy process (AHP), QFD, and LPP to maximize overall customer satisfaction under uncertain conditions and apply them in the supplier development problem. The fuzzy AHP approach is adopted as a powerful method to obtain the relationship between the customer requirements and engineering characteristics (ECs) to construct house of quality in QFD method. LPP is used to obtain the optimal achievement level of the ECs and subsequently the customer satisfaction level under different degrees of uncertainty. The effectiveness of proposed method will be illustrated by an example.

  11. Surveying general prospects and challenges of GIS implementation in developing countries: a SWOT-AHP approach

    NASA Astrophysics Data System (ADS)

    Taleai, Mohammad; Mansourian, Ali; Sharifi, Ali

    2009-09-01

    We propose a combined method based on the strengths, weaknesses, opportunities and threats (SWOT) and analytic hierarchy process (AHP) to investigate the challenges and prospects of adopting geographic information systems (GIS) in developing countries. In this context, we identify, group, and analyse SWOT indicators in relation to the main GIS components: data, people, and technology. The relative significance of each SWOT indicator and its related SWOT groups in each GIS component is quantified. The method is then applied in a situation assessment of GIS adoption in the governmental organisations and strategic planning. The SWOT-AHP approach proves to be very useful in identifying and quantifying the relative significance of the major factors affecting GIS implementation, and effectively facilitates GIS strategic planning.

  12. A Mixed Prioritization Operators Strategy Using A Single Measurement Criterion For AHP Application Development

    NASA Astrophysics Data System (ADS)

    Yuen, Kevin Kam Fung

    2009-10-01

    The most appropriate prioritization method is still one of the unsettled issues of the Analytic Hierarchy Process, although many studies have been made and applied. Interestingly, many AHP applications apply only Saaty's Eigenvector method as many studies have found that this method may produce rank reversals and have proposed various prioritization methods as alternatives. Some methods have been proved to be better than the Eigenvector method. However, these methods seem not to attract the attention of researchers. In this paper, eight important prioritization methods are reviewed. A Mixed Prioritization Operators Strategy (MPOS) is developed to select a vector which is prioritized by the most appropriate prioritization operator. To verify this new method, a case study of high school selection is revised using the proposed method. The contribution is that MPOS is useful for solving prioritization problems in the AHP.

  13. 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

  14. 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

  15. Developmental times and life table statistics of Aulacorthum solani (Hemiptera: Aphididae) at six constant temperatures, with recommendations on the application of temperature-dependent development models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Developmental rates and age-specific life tables were determined for Aulacorthum solani (Kaltenbach) (known as foxglove aphid or glasshouse potato aphid) at 6 constant temperatures feeding on pansy (Viola × wittrockiana) (Gams.). Previously, there were no complete life table studies of this species...

  16. a New Multimodal Multi-Criteria Route Planning Model by Integrating a Fuzzy-Ahp Weighting Method and a Simulated Annealing Algorithm

    NASA Astrophysics Data System (ADS)

    Ghaderi, F.; Pahlavani, P.

    2015-12-01

    A multimodal multi-criteria route planning (MMRP) system provides an optimal multimodal route from an origin point to a destination point considering two or more criteria in a way this route can be a combination of public and private transportation modes. In this paper, the simulate annealing (SA) and the fuzzy analytical hierarchy process (fuzzy AHP) were combined in order to find this route. In this regard, firstly, the effective criteria that are significant for users in their trip were determined. Then the weight of each criterion was calculated using the fuzzy AHP weighting method. The most important characteristic of this weighting method is the use of fuzzy numbers that aids the users to consider their uncertainty in pairwise comparison of criteria. After determining the criteria weights, the proposed SA algorithm were used for determining an optimal route from an origin to a destination. One of the most important problems in a meta-heuristic algorithm is trapping in local minima. In this study, five transportation modes, including subway, bus rapid transit (BRT), taxi, walking, and bus were considered for moving between nodes. Also, the fare, the time, the user's bother, and the length of the path were considered as effective criteria for solving the problem. The proposed model was implemented in an area in centre of Tehran in a GUI MATLAB programming language. The results showed a high efficiency and speed of the proposed algorithm that support our analyses.

  17. Crystallographic and solution studies of NAD(+)- and NADH-bound alkylhydroperoxide reductase subunit F (AhpF) from Escherichia coli provide insight into sequential enzymatic steps.

    PubMed

    Kamariah, Neelagandan; Manimekalai, Malathy Sony Subramanian; Nartey, Wilson; Eisenhaber, Frank; Eisenhaber, Birgit; Grüber, Gerhard

    2015-10-01

    Redox homeostasis is significant for the survival of pro- and eukaryotic cells and is crucial for defense against reactive oxygen species like superoxide and hydrogen peroxide. In Escherichia coli, the reduction of peroxides occurs via the redox active disulfide center of the alkyl hydroperoxide reductase C subunit (AhpC), whose reduced state becomes restored by AhpF. The 57kDa EcAhpF contains an N-terminal domain (NTD), which catalyzes the electron transfer from NADH via an FAD of the C-terminal domain into EcAhpC. The NTD is connected to the C-terminal domain via a linker. Here, the first crystal structure of E. coli AhpF bound with NADH and NAD(+) has been determined at 2.5Å and 2.4Å resolution, respectively. The NADH-bound form of EcAhpF reveals that the NADH-binding domain is required to alter its conformation to bring a bound NADH to the re-face of the isoalloxazine ring of the flavin, and thereby render the NADH-domain dithiol center accessible to the NTD disulfide center for electron transfer. The NAD(+)-bound form of EcAhpF shows conformational differences for the nicotinamide end moieties and its interacting residue M467, which is proposed to represent an intermediate product-release conformation. In addition, the structural alterations in EcAhpF due to NADH- and NAD(+)-binding in solution are shown by small angle X-ray scattering studies. The EcAhpF is revealed to adopt many intermediate conformations in solution to facilitate the electron transfer from the substrate NADH to the C-terminal domain, and subsequently to the NTD of EcAhpF for the final step of AhpC reduction. PMID:26092085

  18. A novel alkyl hydroperoxidase (AhpD) of Anabaena PCC7120 confers abiotic stress tolerance in Escherichia coli.

    PubMed

    Shrivastava, Alok Kumar; Singh, Shilpi; Singh, Prashant Kumar; Pandey, Sarita; Rai, L C

    2015-01-01

    In silico analysis together with cloning, molecular characterization and heterologous expression reports that the hypothetical protein All5371 of Anabaena sp. PCC7120 is a novel hydroperoxide scavenging protein similar to AhpD of bacteria. The presence of E(X)11CX HC(X)3H motif in All5371 confers peroxidase activity and closeness to bacterial AhpD which is also reflected by its highest 3D structure homology with Rhodospirillum rubrum AhpD. Heterologous expression of all5371 complimented for ahpC and conferred resistance in MJF178 strain (ahpCF::Km) of Escherichia coli. All5371 reduced the organic peroxide more efficiently than inorganic peroxide and the recombinant E. coli strain following exposure to H2O2, CdCl2, CuCl2, heat, UV-B and carbofuron registered increased growth over wild-type and mutant E. coli transformed with empty vector. Appreciable expression of all5371 in Anabaena sp. PCC7120 as measured by qRT-PCR under selected stresses and their tolerance against H2O2, tBOOH, CuOOH and menadione attested its role in stress tolerance. In view of the above, All5371 of Anabaena PCC7120 emerged as a new hydroperoxide detoxifying protein. PMID:25391500

  19. 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.

  20. Comparison of Customer Preference for Bulk Material Handling Equipment through Fuzzy-AHP Approach

    NASA Astrophysics Data System (ADS)

    Sen, Kingshuk; Ghosh, Surojit; Sarkar, Bijan

    2016-06-01

    In the present study, customer's perception has played one of the important roles for selection of the exact equipment out of available alternatives. The present study is dealt with the method of optimization of selection criteria of a material handling equipment, based on the technical specifications considered to be available at the user end. In this work, the needs of customers have been identified and prioritized, that lead to the selection of number of criteria, which have direct effect upon the performance of the equipment. To check the consistency of selection criteria, first of all an AHP based methodology is adopted with the identified criteria and available product categories, based upon which, the judgments of the users are defined to derive the priority scales. Such judgments expressed the relative strength or intensity of the impact of the elements of the hierarchy. Subsequently, all the alternatives have ranked for each identified criteria with subsequent constitution of weighted matrices. The same has been compared with the normalized values of approximate selling prices of the equipments to determine individual cost-benefit ratio. Based on the cost-benefit ratio, the equipment is ranked. With same conditions, the study is obtained again with a Fuzzy AHP concept, where a fuzzy linguistic approach has reduced the amount of uncertainty in decision making, caused by conventional AHP due to lack of deterministic approach. The priority vectors of category and criteria are determined separately and multiplied to obtain composite score. Subsequently, the average of fuzzy weights was determined and the preferences of equipment are ranked.

  1. 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.

  2. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of AHP2, a signal transmitter protein from Arabidopsis thaliana

    PubMed Central

    Degtjarik, Oksana; Dopitova, Radka; Puehringer, Sandra; Nejedla, Eliska; Kuty, Michal; Weiss, Manfred S.; Hejatko, Jan; Janda, Lubomir; Kuta Smatanova, Ivana

    2013-01-01

    Histidine-containing phosphotransfer proteins from Arabidopsis thaliana (AHP1–5) act as intermediates between sensor histidine kinases and response regulators in a signalling system called multi-step phosphorelay (MSP). AHP proteins mediate and potentially integrate various MSP-based signalling pathways (e.g. cytokinin or osmosensing). However, structural information about AHP proteins and their importance in MSP signalling is still lacking. To obtain a deeper insight into the structural basis of AHP-mediated signal transduction, the three-dimensional structure of AHP2 was determined. The AHP2 coding sequence was cloned into pRSET B expression vector, enabling production of AHP2 fused to an N-terminal His tag. AHP2 was expressed in soluble form in Escherichia coli strain BL21 (DE3) pLysS and then purified to homogeneity using metal chelate affinity chromatography and anion-exchange chromatography under reducing conditions. Successful crystallization in a buffer which was optimized for thermal stability yielded crystals that diffracted to 2.5 Å resolution. PMID:23385758

  3. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of AHP2, a signal transmitter protein from Arabidopsis thaliana.

    PubMed

    Degtjarik, Oksana; Dopitova, Radka; Puehringer, Sandra; Nejedla, Eliska; Kuty, Michal; Weiss, Manfred S; Hejatko, Jan; Janda, Lubomir; Kuta Smatanova, Ivana

    2013-02-01

    Histidine-containing phosphotransfer proteins from Arabidopsis thaliana (AHP1-5) act as intermediates between sensor histidine kinases and response regulators in a signalling system called multi-step phosphorelay (MSP). AHP proteins mediate and potentially integrate various MSP-based signalling pathways (e.g. cytokinin or osmosensing). However, structural information about AHP proteins and their importance in MSP signalling is still lacking. To obtain a deeper insight into the structural basis of AHP-mediated signal transduction, the three-dimensional structure of AHP2 was determined. The AHP2 coding sequence was cloned into pRSET B expression vector, enabling production of AHP2 fused to an N-terminal His tag. AHP2 was expressed in soluble form in Escherichia coli strain BL21 (DE3) pLysS and then purified to homogeneity using metal chelate affinity chromatography and anion-exchange chromatography under reducing conditions. Successful crystallization in a buffer which was optimized for thermal stability yielded crystals that diffracted to 2.5 Å resolution. PMID:23385758

  4. Solving a layout design problem by analytic hierarchy process (AHP) and data envelopment analysis (DEA) approach

    NASA Astrophysics Data System (ADS)

    Tuzkaya, Umut R.; Eser, Arzum; Argon, Goner

    2004-02-01

    Today, growing amounts of waste due to fast consumption rate of products started an irreversible environmental pollution and damage. A considerable part of this waste is caused by packaging material. With the realization of this fact, various waste policies have taken important steps. Here we considered a firm, where waste Aluminum constitutes majority of raw materials for this fir0m. In order to achieve a profitable recycling process, plant layout should be well designed. In this study, we propose a two-step approach involving Analytic Hierarchy Process (AHP) and Data Envelopment Analysis (DEA) to solve facility layout design problems. A case example is considered to demonstrate the results achieved.

  5. Prioritization of factors impacting on performance of power looms using AHP

    NASA Astrophysics Data System (ADS)

    Dulange, S. R.; Pundir, A. K.; Ganapathy, L.

    2014-08-01

    The purpose of this paper is to identify the critical success factors influencing the performance of power loom textiles, to evaluate their impact on the organizational performance and to find out the effect of these factors on the organizational performance of small and medium-sized enterprises (SMEs) in the Solapur (Maharashtra) industrial sector using AHP. In the methodology adopted, factors are identified through the literature survey and finalization of these factors is done by taking the opinion of experts in the Indian context. By cognitive map, the relation between these factors (direct and indirect effect) is determined and cause and effect diagram is prepared. Then these factors are arranged hierarchically and tree diagram is prepared. A questionnaire was designed and distributed among the experts; data is collected. Using expert choice software data is filled to quantify by pair-wise comparison of these factors and are prioritized. The weights demonstrate several key findings: local and global priority reveals that there is a substantial effect of the human resource, product style, and volume on the organizational performance. The skills and technology upgradation impact on organizational performance. Maintenance plays an important role in improving the organizational performances of the SMEs. Overall, the results showed the central role of the operational factors are important. The research is subject to the normal limitations of AHP. The study is using perceptual data provided by Experts which may not provide clear measures of impact factors. However, this can be overcome using more experts to collect data in future studies. Interestingly, the findings here may be generalisable outside Solapur like Ichalkarnji, Malegaon, and Bhiwadi (Maharashtra). Solapur power loom SMEs should consider AHP as an innovative tool for quantification of factors impacting on performance and improving operational and organizational performance in today's dynamic

  6. Decision making using AHP (Analytic Hierarchy Process) and fuzzy set theory in waste management

    SciTech Connect

    Chung, J.Y.; Lee, K.J.; Kim, C.D.

    1995-12-31

    The major problem is how to consider the differences in opinions, when many experts are involved in decision making process. This paper provides a simple general methodology to treat the differences in various opinions. The authors determined the grade of membership through the process of magnitude estimation derived from pairwise comparisons and AHP developed by Saaty. They used fuzzy set theory to consider the differences in opinions and obtain the priorities for each alternative. An example, which can be applied to radioactive waste management, also was presented. The result shows a good agreement with the results of averaging methods.

  7. Hospital site selection using fuzzy AHP and its derivatives.

    PubMed

    Vahidnia, Mohammad H; Alesheikh, Ali A; Alimohammadi, Abbas

    2009-07-01

    Environmental managers are commonly faced with sophisticated decisions, such as choosing the location of a new facility subject to multiple conflicting criteria. This paper considers the specific problem of creating a well-distributed network of hospitals that delivers its services to the target population with minimal time, pollution and cost. We develop a Multi-Criteria Decision Analysis process that combines Geographical Information System (GIS) analysis with the Fuzzy Analytical Hierarchy Process (FAHP), and use this process to determine the optimum site for a new hospital in the Tehran urban area. The GIS was used to calculate and classify governing criteria, while FAHP was used to evaluate the decision factors and their impacts on alternative sites. Three methods were used to estimate the total weights and priorities of the candidate sites: fuzzy extent analysis, center-of-area defuzzification, and the alpha-cut method. The three methods yield identical priorities for the five alternatives considered. Fuzzy extent analysis provides less discriminating power, but is simpler to implement and compute than the other two methods. The alpha-cut method is more complicated, but integrates the uncertainty and overall attitude of the decision-maker. The usefulness of the new hospital site is evaluated by computing an accessibility index for each pixel in the GIS, defined as the ratio of population density to travel time. With the addition of a new hospital at the optimum site, this index improved over about 6.5 percent of the geographical area. PMID:19477577

  8. Knockout of the BK β4-subunit promotes a functional coupling of BK channels and ryanodine receptors that mediate a fAHP-induced increase in excitability.

    PubMed

    Wang, Bin; Bugay, Vladislav; Ling, Ling; Chuang, Hui-Hsui; Jaffe, David B; Brenner, Robert

    2016-08-01

    BK channels are large-conductance calcium- and voltage-activated potassium channels with diverse properties. Knockout of the accessory BK β4-subunit in hippocampus dentate gyrus granule neurons causes BK channels to change properties from slow-gated type II channels to fast-gated type I channels that sharpen the action potential, increase the fast afterhyperpolarization (fAHP) amplitude, and increase spike frequency. Here we studied the calcium channels that contribute to fast-gated BK channel activation and increased excitability of β4 knockout neurons. By using pharmacological blockers during current-clamp recording, we find that BK channel activation during the fAHP is dependent on ryanodine receptor activation. In contrast, L-type calcium channel blocker (nifedipine) affects the BK channel-dependent repolarization phase of the action potential but has no effect on the fAHP. Reducing BK channel activation during the repolarization phase with nifedipine, or during the fAHP with ryanodine, indicated that it is the BK-mediated increase of the fAHP that confers proexcitatory effects. The proexcitatory role of the fAHP was corroborated using dynamic current clamp. Increase or decrease of the fAHP amplitude during spiking revealed an inverse relationship between fAHP amplitude and interspike interval. Finally, we show that the seizure-prone ryanodine receptor gain-of-function (R2474S) knockin mice have an unaltered repolarization phase but larger fAHP and increased AP frequency compared with their control littermates. In summary, these results indicate that an important role of the β4-subunit is to reduce ryanodine receptor-BK channel functional coupling during the fAHP component of the action potential, thereby decreasing excitability of dentate gyrus neurons. PMID:27146987

  9. 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.

  10. Solar constant secular changes

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Orosz, Jerome A.

    1990-01-01

    A recent model for solar constant secular changes is used to calculate a 'proxy' solar constant for: (1) the past four centuries, based upon the sunspot record, (2) the past nine centuries, based upon C-14 observations and their relation to solar activity, and (3) the next decade, based upon a dynamo theory model for the solar cycle. The proxy solar constant data is tabulated as it may be useful for climate modelers studying global climate changes.

  11. Diesel engine noise source identification based on EEMD, coherent power spectrum analysis and improved AHP

    NASA Astrophysics Data System (ADS)

    Zhang, Junhong; Wang, Jian; Lin, Jiewei; Bi, Fengrong; Guo, Qian; Chen, Kongwu; Ma, Liang

    2015-09-01

    As the essential foundation of noise reduction, many noise source identification methods have been developed and applied to engineering practice. To identify the noise source in the board-band frequency of different engine parts at various typical speeds, this paper presents an integrated noise source identification method based on the ensemble empirical mode decomposition (EEMD), the coherent power spectrum analysis, and the improved analytic hierarchy process (AHP). The measured noise is decomposed into several IMFs with physical meaning, which ensures the coherence analysis of the IMFs and the vibration signals are meaningful. An improved AHP is developed by introducing an objective weighting function to replace the traditional subjective evaluation, which makes the results no longer dependent on the subject performances and provides a better consistency in the meantime. The proposed noise identification model is applied to identifying a diesel engine surface radiated noise. As a result, the frequency-dependent contributions of different engine parts to different test points at different speeds are obtained, and an overall weight order is obtained as oil pan  >  left body  >  valve chamber cover  >  gear chamber casing  >  right body  >  flywheel housing, which provides an effectual guidance for the noise reduction.

  12. Transshipment site selection using the AHP and TOPSIS approaches under fuzzy environment.

    PubMed

    Onüt, Semih; Soner, Selin

    2008-01-01

    Site selection is an important issue in waste management. Selection of the appropriate solid waste site requires consideration of multiple alternative solutions and evaluation criteria because of system complexity. Evaluation procedures involve several objectives, and it is often necessary to compromise among possibly conflicting tangible and intangible factors. For these reasons, multiple criteria decision-making (MCDM) has been found to be a useful approach to solve this kind of problem. Different MCDM models have been applied to solve this problem. But most of them are basically mathematical and ignore qualitative and often subjective considerations. It is easier for a decision-maker to describe a value for an alternative by using linguistic terms. In the fuzzy-based method, the rating of each alternative is described using linguistic terms, which can also be expressed as triangular fuzzy numbers. Furthermore, there have not been any studies focused on the site selection in waste management using both fuzzy TOPSIS (technique for order preference by similarity to ideal solution) and AHP (analytical hierarchy process) techniques. In this paper, a fuzzy TOPSIS based methodology is applied to solve the solid waste transshipment site selection problem in Istanbul, Turkey. The criteria weights are calculated by using the AHP. PMID:17768038

  13. Dependence Assessment in Human Reliability Analysis Using Evidence Theory and AHP.

    PubMed

    Su, Xiaoyan; Mahadevan, Sankaran; Xu, Peida; Deng, Yong

    2015-07-01

    Dependence assessment among human errors in human reliability analysis (HRA) is an important issue. Many of the dependence assessment methods in HRA rely heavily on the expert's opinion, thus are subjective and may sometimes cause inconsistency. In this article, we propose a computational model based on the Dempster-Shafer evidence theory (DSET) and the analytic hierarchy process (AHP) method to handle dependence in HRA. First, dependence influencing factors among human tasks are identified and the weights of the factors are determined by experts using the AHP method. Second, judgment on each factor is given by the analyst referring to anchors and linguistic labels. Third, the judgments are represented as basic belief assignments (BBAs) and are integrated into a fused BBA by weighted average combination in DSET. Finally, the CHEP is calculated based on the fused BBA. The proposed model can deal with ambiguity and the degree of confidence in the judgments, and is able to reduce the subjectivity and improve the consistency in the evaluation process. PMID:25847228

  14. Transshipment site selection using the AHP and TOPSIS approaches under fuzzy environment

    SciTech Connect

    Onuet, Semih Soner, Selin

    2008-07-01

    Site selection is an important issue in waste management. Selection of the appropriate solid waste site requires consideration of multiple alternative solutions and evaluation criteria because of system complexity. Evaluation procedures involve several objectives, and it is often necessary to compromise among possibly conflicting tangible and intangible factors. For these reasons, multiple criteria decision-making (MCDM) has been found to be a useful approach to solve this kind of problem. Different MCDM models have been applied to solve this problem. But most of them are basically mathematical and ignore qualitative and often subjective considerations. It is easier for a decision-maker to describe a value for an alternative by using linguistic terms. In the fuzzy-based method, the rating of each alternative is described using linguistic terms, which can also be expressed as triangular fuzzy numbers. Furthermore, there have not been any studies focused on the site selection in waste management using both fuzzy TOPSIS (technique for order preference by similarity to ideal solution) and AHP (analytical hierarchy process) techniques. In this paper, a fuzzy TOPSIS based methodology is applied to solve the solid waste transshipment site selection problem in Istanbul, Turkey. The criteria weights are calculated by using the AHP.

  15. How fundamental are fundamental constants?

    NASA Astrophysics Data System (ADS)

    Duff, M. J.

    2015-01-01

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

  16. 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.

  17. 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…

  18. Calcium-activated afterhyperpolarizations regulate synchronization and timing of epileptiform bursts in hippocampal CA3 pyramidal neurons.

    PubMed

    Fernández de Sevilla, David; Garduño, Julieta; Galván, Emilio; Buño, Washington

    2006-12-01

    Calcium-activated potassium conductances regulate neuronal excitability, but their role in epileptogenesis remains elusive. We investigated in rat CA3 pyramidal neurons the contribution of the Ca(2+)-activated K(+)-mediated afterhyperpolarizations (AHPs) in the genesis and regulation of epileptiform activity induced in vitro by 4-aminopyridine (4-AP) in Mg(2+)-free Ringer. Recurring spike bursts terminated by prolonged AHPs were generated. Burst synchronization between CA3 pyramidal neurons in paired recordings typified this interictal-like activity. A downregulation of the medium afterhyperpolarization (mAHP) paralleled the emergence of the interictal-like activity. When the mAHP was reduced or enhanced by apamin and EBIO bursts induced by 4-AP were increased or blocked, respectively. Inhibition of the slow afterhyperpolarization (sAHP) with carbachol, t-ACPD, or isoproterenol increased bursting frequency and disrupted burst regularity and synchronization between pyramidal neuron pairs. In contrast, enhancing the sAHP by intracellular dialysis with KMeSO(4) reduced burst frequency. Block of GABA(A-B) inhibitions did not modify the abnormal activity. We describe novel cellular mechanisms where 1) the inhibition of the mAHP plays an essential role in the genesis and regulation of the bursting activity by reducing negative feedback, 2) the sAHP sets the interburst interval by decreasing excitability, and 3) bursting was synchronized by excitatory synaptic interactions that increased in advance and during bursts and decreased throughout the subsequent sAHP. These cellular mechanisms are active in the CA3 region, where epileptiform activity is initiated, and cooperatively regulate the timing of the synchronized rhythmic interictal-like network activity. PMID:16971683

  19. Mapping of the exchangeable and dispensable domains of the RNA 2-encoded 2A(HP) protein of arabis mosaic nepovirus.

    PubMed

    Nourinejhad Zarghani, Shaheen; Dupuis-Maguiraga, Laurence; Bassler, Alexandra; Wetzel, Thierry

    2014-06-01

    The N-terminal domains of the RNA 2-encoded 2A(HP) proteins of the arabis mosaic (ArMV) and grapevine fanleaf (GFLV) nepoviruses were shown to be highly variable and a hotspot for intra- and inter-species recombination events. Chimeric ArMV-NW clones in which the N-terminal domain of 2A(HP) or the entire 2A(HP) of GFLV isolates replaced the corresponding domains of ArMV retained their infectivity, showing that the 2A(HP) proteins of ArMV-NW and GFLV are exchangeable. ArMN-NW clones with deletions of the N-terminal, core, or C-terminal domains of the ArMV-NW 2A(HP) were infectious in Chenopodium quinoa although viral RNA (especially RNA 2) accumulated at reduced levels. In contrast, deletion of the entire 2A(HP) protein or of the C-terminal two thirds of the protein abolished infectivity of the ArMV-NW clones. These results suggest that multiple functional domains are distributed throughout the 2A(HP) protein and are essential for the accumulation of viral RNA 2. PMID:24928043

  20. Genomic Characterization of the Novel Aeromonas hydrophila Phage Ahp1 Suggests the Derivation of a New Subgroup from phiKMV-Like Family.

    PubMed

    Wang, Jian-Bin; Lin, Nien-Tsung; Tseng, Yi-Hsiung; Weng, Shu-Fen

    2016-01-01

    Aeromonas hydrophila is an opportunistic pathogenic bacterium causing diseases in human and fish. The emergence of multidrug-resistant A. hydrophila isolates has been increasing in recent years. In this study, we have isolated a novel virulent podophage of A. hydrophila, designated as Ahp1, from waste water. Ahp1 has a rapid adsorption (96% adsorbed in 2 min), a latent period of 15 min, and a burst size of 112 PFU per infected cell. At least eighteen Ahp1 virion proteins were visualized in SDS-polyacrylamide gel electrophoresis, with a 36-kDa protein being the predicted major capsid protein. Genome analysis of Ahp1 revealed a linear doubled-stranded DNA genome of 42,167 bp with a G + C content of 58.8%. The genome encodes 46 putative open reading frames, 5 putative phage promoters, and 3 transcriptional terminators. Based on high degrees of similarity in overall genome organization and among most of the corresponding ORFs, as well as phylogenetic relatedness among their DNAP, RNAP and major capsid proteins, we propose a new subgroup, designated Ahp1-like subgroup. This subgroup contains Ahp1 and members previously belonging to phiKMV-like subgroup, phiAS7, phi80-18, GAP227, phiR8-01, and ISAO8. Since Ahp1 has a narrow host range, for effective phage therapy, different phages are needed for preparation of cocktails that are capable of killing the heterogeneous A. hydrophila strains. PMID:27603936

  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. 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.

  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. Groundwater Potential Assessment Using Geographic Information Systems and Ahp Method (case Study: Baft City, Kerman, Iran)

    NASA Astrophysics Data System (ADS)

    Zeinolabedini, M.; Esmaeily, A.

    2015-12-01

    The purpose of the present study is to use Geographical Information Systems (GISs) for determining the best areas having ground water potential in Baft city. To achieve this objective, parameters such as precipitation, slope, fault, vegetation, land cover and lithology were used. Regarding different weight of these parameters effect, Analytic Hierarchy Process (AHP) was used. After developing informational layers in GIS and weighing each of them, a model was developed. The final map of ground waters potential was calculated through the above-mentioned model. Through applying our developed model four areas having high, average, low potential and without required potential distinguished. Results of this research indicated that 0.74, 41.23 and 45.63 percent of the area had high, average and low potential, respectively. Moreover, 12.38% of this area had no potential. Obtained results can be useful in management plans of ground water resources and preventing excessive exploitation.

  6. Application of the AHP method in modeling the trust and reputation of software agents

    NASA Astrophysics Data System (ADS)

    Zytniewski, Mariusz; Klementa, Marek; Skorupka, Dariusz; Stanek, Stanislaw; Duchaczek, Artur

    2016-06-01

    Given the unique characteristics of cyberspace and, in particular, the number of inherent security threats, communication between software agents becomes a highly complex issue and a major challenge that, on the one hand, needs to be continuously monitored and, on the other, awaits new solutions addressing its vulnerabilities. An approach that has recently come into view mimics mechanisms typical of social systems and is based on trust and reputation that assist agents in deciding which other agents to interact with. The paper offers an enhancement to existing trust and reputation models, involving the application of the AHP method that is widely used for decision support in social systems, notably for risks analysis. To this end, it is proposed to expand the underlying conceptual basis by including such notions as self-trust and social trust, and to apply these to software agents. The discussion is concluded with an account of an experiment aimed at testing the effectiveness of the proposed solution.

  7. Prioritizing sewer rehabilitation projects using AHP-PROMETHEE II ranking method.

    PubMed

    Kessili, Abdelhak; Benmamar, Saadia

    2016-01-01

    The aim of this paper is to develop a methodology for the prioritization of sewer rehabilitation projects for Algiers (Algeria) sewer networks to support the National Sanitation Office in its challenge to make decisions on prioritization of sewer rehabilitation projects. The methodology applies multiple-criteria decision making. The study includes 47 projects (collectors) and 12 criteria to evaluate them. These criteria represent the different issues considered in the prioritization of the projects, which are structural, hydraulic, environmental, financial, social and technical. The analytic hierarchy process (AHP) is used to determine weights of the criteria and the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE II) method is used to obtain the final ranking of the projects. The model was verified using the sewer data of Algiers. The results have shown that the method can be used for prioritizing sewer rehabilitation projects. PMID:26819383

  8. Green design assessment of electromechanical products based on group weighted-AHP

    NASA Astrophysics Data System (ADS)

    Guo, Jinwei; Zhou, MengChu; Li, Zhiwu; Xie, Huiguang

    2015-11-01

    Manufacturing industry is the backbone of a country's economy while environmental pollution is a serious problem that human beings must face today. The green design of electromechanical products based on enterprise information systems is an important method to solve the environmental problem. The question on how to design green products must be answered by excellent designers via both advanced design methods and effective assessment methods of electromechanical products. Making an objective and precise assessment of green design is one of the problems that must be solved when green design is conducted. An assessment method of green design on electromechanical products based on Group Weighted-AHP (Analytic Hierarchy Process) is proposed in this paper, together with the characteristics of green products. The assessment steps of green design are also established. The results are illustrated via the assessment of a refrigerator design.

  9. Evaluation and selection of open-source EMR software packages based on integrated AHP and TOPSIS.

    PubMed

    Zaidan, A A; Zaidan, B B; Al-Haiqi, Ahmed; Kiah, M L M; Hussain, Muzammil; Abdulnabi, Mohamed

    2015-02-01

    Evaluating and selecting software packages that meet the requirements of an organization are difficult aspects of software engineering process. Selecting the wrong open-source EMR software package can be costly and may adversely affect business processes and functioning of the organization. This study aims to evaluate and select open-source EMR software packages based on multi-criteria decision-making. A hands-on study was performed and a set of open-source EMR software packages were implemented locally on separate virtual machines to examine the systems more closely. Several measures as evaluation basis were specified, and the systems were selected based a set of metric outcomes using Integrated Analytic Hierarchy Process (AHP) and TOPSIS. The experimental results showed that GNUmed and OpenEMR software can provide better basis on ranking score records than other open-source EMR software packages. PMID:25483886

  10. Dielectric Constant of Suspensions

    NASA Astrophysics Data System (ADS)

    Mendelson, Kenneth S.; Ackmann, James J.

    1997-03-01

    We have used a finite element method to calculate the dielectric constant of a cubic array of spheres. Extensive calculations support preliminary conclusions reported previously (K. Mendelson and J. Ackmann, Bull. Am. Phys. Soc. 41), 657 (1996).. At frequencies below 100 kHz the real part of the dielectric constant (ɛ') shows oscillations as a function of the volume fraction of suspension. These oscillations disappear at low conductivities of the suspending fluid. Measurements of the dielectric constant (J. Ackmann, et al., Ann. Biomed. Eng. 24), 58 (1996). (H. Fricke and H. Curtis, J. Phys. Chem. 41), 729 (1937). are not sufficiently sensitive to show oscillations but appear to be consistent with the theoretical results.

  11. 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.

  12. Constant time INEPT CT-HSQC (CTi-CT-HSQC) - A new NMR method to measure accurate one-bond J and RDCs with strong 1H-1H couplings in natural abundance

    NASA Astrophysics Data System (ADS)

    Yu, Bingwu; van Ingen, Hugo; Freedberg, Darón I.

    2013-03-01

    Strong 1H-1H coupling can significantly reduce the accuracy of 1JCH measured from frequency differences in coupled HSQC spectra. Although accurate 1JCH values can be extracted from spectral simulation, it would be more convenient if the same accurate 1JCH values can be obtained experimentally. Furthermore, simulations reach their limit for residual dipolar coupling (RDC) measurement, as many significant, but immeasurable RDCs are introduced into the spin system when a molecule is weakly aligned, thus it is impossible to have a model spin system that truly represents the real spin system. Here we report a new J modulated method, constant-time INEPT CT-HSQC (CTi-CT-HSQC), to accurately measure one-bond scalar coupling constant and RDCs without strong coupling interference. In this method, changing the spacing between the two 180° pulses during a constant time INEPT period selectively modulates heteronuclear coupling in quantitative J fashion. Since the INEPT delays for measuring one-bond carbon-proton spectra are short compared to 3JHH, evolution due to (strong) 1H-1H coupling is marginal. The resulting curve shape is practically independent of 1H-1H coupling and only correlated to the heteronuclear coupling evolution. Consequently, an accurate 1JCH can be measured even in the presence of strong coupling. We tested this method on N-acetyl-glucosamine and mannose whose apparent isotropic 1JCH values are significantly affected by strong coupling with other methods. Agreement to within 0.5 Hz or better is found between 1JCH measured by this method and previously published simulation data. We further examined the strong coupling effects on RDC measurements and observed an error up to 100% for one bond RDCs using coupled HSQC in carbohydrates. We demonstrate that RDCs can be obtained with higher accuracy by CTi-CT-HSQC, which compensates the limitation of simulation method.

  13. 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).

  14. AhpC, AhpD, and a secreted 14-kilodalton antigen from Mycobacterium avium subsp. paratuberculosis distinguish between paratuberculosis and bovine tuberculosis in an enzyme-linked immunosorbent assay.

    PubMed

    Olsen, I; Tryland, M; Wiker, H G; Reitan, L J

    2001-07-01

    Sera from cattle naturally infected with Mycobacterium avium subsp. paratuberculosis (n = 56) and naturally (n = 4) and experimentally (n = 8) infected with Mycobacterium bovis were tested for the presence of antibodies against paratuberculosis antigens. An enzyme-linked immunosorbent assay (ELISA) was established based on absorption of M. avium subsp. paratuberculosis antigens on a hyperimmune antiserum against M. avium subsp. avium proteins in order to remove cross-reacting antigens. This absorbed-antigen ELISA recognized 66% of animals with paratuberculosis (37 of 56), while none of the animals with naturally occurring bovine tuberculosis (TB) had detectable antibodies. However, the animals with experimental bovine TB also responded in this ELISA. Similar results were found in a commercial ELISA, showing that neither of these tests was able to distinguish between paratuberculosis and bovine TB. The sera were further tested for antibody activities against purified AhpC and AhpD, which are proteins constitutively expressed by M. avium subsp. paratuberculosis, and against a secreted 14-kDa protein present in culture filtrates from the M. avium complex. Elevated antibody levels to AhpC, AhpD, and the 14-kDa antigen were found in 27% (13 of 48), 15% (7 of 48), and 27% (13 of 48), respectively, of the cattle with paratuberculosis. Together these ELISAs were positive with 35% (17 of 48) of the animals. None of the animals with bovine TB had detectable antibodies against any of the purified proteins despite their high levels of cross-reacting antibodies. These results show that purified specific antigens are needed to differentiate between paratuberculosis and bovine TB in ELISA. PMID:11427429

  15. New Quasar Studies Keep Fundamental Physical Constant Constant

    NASA Astrophysics Data System (ADS)

    2004-03-01

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

  16. Using AHP to analyze and ascertain the priority protective order of endangered plants in East Alashan-West Erdos

    NASA Astrophysics Data System (ADS)

    Tao, Zhang; Wei, Wang; Wang, Gary Z.; Luo, Hongyan; Liang, Cunzhu; Liu, Jiahui; An, Huijun; Pei, Hao; Zhong, Huidong; Chen, Xiaojun

    2006-08-01

    AHP is a kind of very effective systematic analytical method, widely applied to energy utilizing and resource analyzing, talent predicting, economic management project, urban industries planning, communications and transportation, water resource using and so on, using this method to solve the problem of ecology also have very strong practicability and validity. Using 15 kinds of endured plants in East Alashan-West Erdos as the research objects, this paper adopts 3S technique and outfield investigates to confirm the geographical distributions, extent density in the distribution area, plant community construction, and plant community environment of the plants. Then invite the experts to give marks according to this datum and using the AHP method to deal with the results, thereby get the priority protective order of endangered plants in East Alashan-West Erdos.

  17. Regularizing cosmological singularities by varying physical constants

    SciTech Connect

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

    2013-02-01

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

  18. 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.

  19. Renormalization of Newton's constant

    NASA Astrophysics Data System (ADS)

    Falls, Kevin

    2015-12-01

    The problem of obtaining a gauge independent beta function for Newton's constant is addressed. By a specific parametrization of metric fluctuations a gauge independent functional integral is constructed for the semiclassical theory around an arbitrary Einstein space. The effective action then has the property that only physical polarizations of the graviton contribute, while all other modes cancel with the functional measure. We are then able to compute a gauge independent beta function for Newton's constant in d dimensions to one-loop order. No Landau pole is present provided Ng<18 , where Ng=d (d -3 )/2 is the number of polarizations of the graviton. While adding a large number of matter fields can change this picture, the absence of a pole persists for the particle content of the standard model in four spacetime dimensions.

  20. 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.

  1. The Hubble Constant

    NASA Astrophysics Data System (ADS)

    Jackson, Neal

    2015-09-01

    I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H_0 values of around 72-74 km s^-1 Mpc^-1, with typical errors of 2-3 km s^-1 Mpc^-1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68 km s^-1 Mpc^-1 and typical errors of 1-2 km s^-1 Mpc^-1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.

  2. An Integrated model for Product Quality Development—A case study on Quality functions deployment and AHP based approach

    NASA Astrophysics Data System (ADS)

    Maitra, Subrata; Banerjee, Debamalya

    2010-10-01

    Present article is based on application of the product quality and improvement of design related with the nature of failure of machineries and plant operational problems of an industrial blower fan Company. The project aims at developing the product on the basis of standardized production parameters for selling its products in the market. Special attention is also being paid to the blower fans which have been ordered directly by the customer on the basis of installed capacity of air to be provided by the fan. Application of quality function deployment is primarily a customer oriented approach. Proposed model of QFD integrated with AHP to select and rank the decision criterions on the commercial and technical factors and the measurement of the decision parameters for selection of best product in the compettitive environment. The present AHP-QFD model justifies the selection of a blower fan with the help of the group of experts' opinion by pairwise comparison of the customer's and ergonomy based technical design requirements. The steps invoved in implementation of the QFD—AHP and selection of weighted criterion may be helpful for all similar purpose industries maintaining cost and utility for competitive product.

  3. H Scan/AHP decision process planning for evaluating and ranking of proposals submitted to the DOE hydrogen program

    SciTech Connect

    Szoka de Valladares, M.R.; Mack, S.

    1995-09-01

    The DOE Hydrogen Program needs to develop criteria as part of a systematic evaluation process for proposal identification, evaluation and selection. The H Scan component of this process provides a framework in which a project proposer can fully describe their candidate technology system and its components. The H Scan complements traditional methods of capturing cost and technical information. It consists of a special set of survey forms designed to elicit information so expert reviewers can assess the proposal relative to DOE specified selection criteria. The Analytic Hierarchy Process (AHP) component of the decision process assembles the management defined evaluation and selection criteria into a coherent multi-level decision construct by which projects can be evaluated in pair-wise comparisons. The AHP model will reflect management`s objectives and it will assist in the ranking of individual projects based on the extent to which each contributes to management`s objectives. This paper contains a detailed description of the products and activities associated with the planning and evaluation process: The objectives or criteria; the H Scan; and The Analytic Hierarchy Process (AHP).

  4. User needs elicitation via analytic hierarchy process (AHP). A case study on a Computed Tomography (CT) scanner

    PubMed Central

    2013-01-01

    Background The rigorous elicitation of user needs is a crucial step for both medical device design and purchasing. However, user needs elicitation is often based on qualitative methods whose findings can be difficult to integrate into medical decision-making. This paper describes the application of AHP to elicit user needs for a new CT scanner for use in a public hospital. Methods AHP was used to design a hierarchy of 12 needs for a new CT scanner, grouped into 4 homogenous categories, and to prepare a paper questionnaire to investigate the relative priorities of these. The questionnaire was completed by 5 senior clinicians working in a variety of clinical specialisations and departments in the same Italian public hospital. Results Although safety and performance were considered the most important issues, user needs changed according to clinical scenario. For elective surgery, the five most important needs were: spatial resolution, processing software, radiation dose, patient monitoring, and contrast medium. For emergency, the top five most important needs were: patient monitoring, radiation dose, contrast medium control, speed run, spatial resolution. Conclusions AHP effectively supported user need elicitation, helping to develop an analytic and intelligible framework of decision-making. User needs varied according to working scenario (elective versus emergency medicine) more than clinical specialization. This method should be considered by practitioners involved in decisions about new medical technology, whether that be during device design or before deciding whether to allocate budgets for new medical devices according to clinical functions or according to hospital department. PMID:23289426

  5. Prediction of Floor Water Inrush: The Application of GIS-Based AHP Vulnerable Index Method to Donghuantuo Coal Mine, China

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Liu, Yuanzhang; Liu, Donghai; Zhou, Wanfang

    2011-09-01

    Floor water inrush represents a geohazard that can pose significant threat to safe operations for instance in coal mines in China and elsewhere. Its occurrence is controlled by many factors, and the processes are often not amenable to mathematical expressions. To evaluate the water inrush risk, the paper proposes the vulnerability index approach by coupling the analytic hierarchy process (AHP) and geographic information system (GIS). The detailed procedures of using this innovative approach are shown in a case study in China (Donghuantuo Coal Mine). The powerful spatial data analysis functions of GIS was used to establish the thematic layer of each of the six factors that control the water inrush, and the contribution weights of each factor was determined with the AHP method. The established AHP evaluation model was used to determine the threshold value for each risk level with a histogram of the water inrush vulnerability index. As a result, the mine area was divided into five regions with different vulnerability levels which served as general guidelines for the mine operations. The prediction results were further corroborated with the actual mining data, and the evaluation result is satisfactory.

  6. An Ortholog of OxyR in Legionella pneumophila Is Expressed Postexponentially and Negatively Regulates the Alkyl Hydroperoxide Reductase (ahpC2D) Operon▿

    PubMed Central

    LeBlanc, Jason J.; Brassinga, Ann Karen C.; Ewann, Fanny; Davidson, Ross J.; Hoffman, Paul S.

    2008-01-01

    Legionella pneumophila expresses two peroxide-scavenging alkyl hydroperoxide reductase systems (AhpC1 and AhpC2D) that are expressed differentially during the bacterial growth cycle. Functional loss of the postexponentially expressed AhpC1 system is compensated for by increased expression of the exponentially expressed AhpC2D system. In this study, we used an acrylamide capture of DNA-bound complexes (ACDC) technique and mass spectrometry to identify proteins that bind to the promoter region of the ahpC2D operon. The major protein captured was an ortholog of OxyR (OxyRLp). Genetic studies indicated that oxyRLp was an essential gene expressed postexponentially and only partially complemented an Escherichia coli oxyR mutant (GS077). Gel shift assays confirmed specific binding of OxyRLp to ahpC2D promoter sequences, but not to promoters of ahpC1 or oxyRLp; however, OxyRLp weakly bound to E. coli OxyR-regulated promoters (katG, oxyR, and ahpCF). DNase I protection studies showed that the OxyRLp binding motif spanned the promoter and transcriptional start sequences of ahpC2 and that the protected region was unchanged by treatments with reducing agents or hydrogen peroxide (H2O2). Moreover, the OxyRLp (pBADLpoxyR)-mediated repression of an ahpC2-gfp reporter construct in E. coli GS077 (the oxyR mutant) was not reversed by H2O2 challenge. Alignments with other OxyR proteins revealed several amino acid substitutions predicted to ablate thiol oxidation or conformational changes required for activation. We suggest these mutations have locked OxyRLp in an active DNA-binding conformation, which has permitted a divergence of function from a regulator of oxidative stress to a cell cycle regulator, perhaps controlling gene expression during postexponential differentiation. PMID:18359810

  7. Multi-QoS Criteria Based Selection of Web Services by Using AHP Approach

    NASA Astrophysics Data System (ADS)

    Tran, Vuong Xuan; Tsuji, Hidekazu; Masuda, Ryosuke

    QoS-based Web service ranking problem is complex due to the diverse characteristic of QoS properties and the trade-off issue between them. A ranking mechanism needs to take into account different ways to effectively handle different types of QoS properties measured by different methods with different units and value types, as well as to unify those various QoS measurements in a fair comparison method. In this paper, we present a novel method for ranking and selecting Web services by introducing an extensible QoS model and a corresponding ranking algorithm. The QoS model takes into account the following considerations: different roles and preferences of users and system brokers in specifying QoS demand, different important levels between required QoS constraints and optional QoS preferences, and different QoS value comparison rules with respect to value types and comparative effects of QoS properties. AHP, a multiple criteria decision making method, is applied as an underlying mechanism for developing a flexible and effective ranking algorithm. The experimental results verify that our proposal produces significant achievement with our extensible QoS model and the new service ranking algorithm.

  8. RFM-based eco-efficiency analysis using Takagi-Sugeno fuzzy and AHP approach

    SciTech Connect

    Chen Ruiyang

    2009-04-15

    Eco-design is crucial to take environmental aspects into account in the phases of design. Few literature review that green product must meet market value. The development of models to predict market value is thus very useful because it can provide early eco-efficiency to the eco-design. For the eco-design engineer, when he tries to solve a customer feedback problem, he usually faces the eco-efficiency. There are, however, often other types of fuzziness uncertainty present, which are related to the quantity of eco-design conditions. In this paper, it is derived that analysis of eco-efficiency can be identified by using the RFM value for quantifying eco-design with Takagi-Sugeno fuzzy system on customer feedback problem. It clusters eco-efficiency into segments according to green product usages value expressed in terms of weighted RFM. This experiment examined the weighted RFM effect of overall average normalized, AHP and non-weighted for F1 metric. The experimental results show that the proposed methodology indeed can yield identification of higher quality.

  9. HbAHP-25, an In-Silico Designed Peptide, Inhibits HIV-1 Entry by Blocking gp120 Binding to CD4 Receptor

    PubMed Central

    Bashir, Tahir; Patgaonkar, Mandar; Kumar C, Selvaa; Pasi, Achhelal; Reddy, Kudumula Venkata Rami

    2015-01-01

    Human Immunodeficiency Virus (HIV-1) poses a serious threat to the developing world and sexual transmission continues to be the major source of new infections. Therefore, the development of molecules, which prevent new HIV-1 infections, is highly warranted. In the present study, a panel of human hemoglobin (Hb)-α subunit derived peptides and their analogues, with an ability to bind gp120, were designed in-silico and their anti-HIV-1 activity was evaluated. Of these peptides, HbAHP-25, an analogue of Hb-α derived peptide, demonstrated significant anti-HIV-1 activity. HbAHP-25 was found to be active against CCR5-tropic HIV-1 strains (ADA5 and BaL) and CXCR4-tropic HIV-1 strains (IIIB and NL4-3). Surface plasmon resonance (SPR) and ELISA revealed direct interaction between HbAHP-25 and HIV-1 envelope protein, gp120. The peptide prevented binding of CD4 to gp120 and blocked subsequent steps leading to entry and/or fusion or both. Anti-HIV activity of HbAHP-25 appeared to be specific as it failed to inhibit the entry of HIV-1 pseudotyped virus (HIV-1 VSV). Further, HbAHP-25 was found to be non-cytotoxic to TZM-bl cells, VK2/E6E7 cells, CEM-GFP cells and PBMCs, even at higher concentrations. Moreover, HbAHP-25 retained its anti-HIV activity in presence of seminal plasma and vaginal fluid. In brief, the study identified HbAHP-25, a novel anti-HIV peptide, which directly interacts with gp120 and thus has a potential to inhibit early stages of HIV-1 infection. PMID:25915507

  10. HbAHP-25, an In-Silico Designed Peptide, Inhibits HIV-1 Entry by Blocking gp120 Binding to CD4 Receptor.

    PubMed

    Bashir, Tahir; Patgaonkar, Mandar; Kumar, Selvaa C; Pasi, Achhelal; Reddy, Kudumula Venkata Rami

    2015-01-01

    Human Immunodeficiency Virus (HIV-1) poses a serious threat to the developing world and sexual transmission continues to be the major source of new infections. Therefore, the development of molecules, which prevent new HIV-1 infections, is highly warranted. In the present study, a panel of human hemoglobin (Hb)-α subunit derived peptides and their analogues, with an ability to bind gp120, were designed in-silico and their anti-HIV-1 activity was evaluated. Of these peptides, HbAHP-25, an analogue of Hb-α derived peptide, demonstrated significant anti-HIV-1 activity. HbAHP-25 was found to be active against CCR5-tropic HIV-1 strains (ADA5 and BaL) and CXCR4-tropic HIV-1 strains (IIIB and NL4-3). Surface plasmon resonance (SPR) and ELISA revealed direct interaction between HbAHP-25 and HIV-1 envelope protein, gp120. The peptide prevented binding of CD4 to gp120 and blocked subsequent steps leading to entry and/or fusion or both. Anti-HIV activity of HbAHP-25 appeared to be specific as it failed to inhibit the entry of HIV-1 pseudotyped virus (HIV-1 VSV). Further, HbAHP-25 was found to be non-cytotoxic to TZM-bl cells, VK2/E6E7 cells, CEM-GFP cells and PBMCs, even at higher concentrations. Moreover, HbAHP-25 retained its anti-HIV activity in presence of seminal plasma and vaginal fluid. In brief, the study identified HbAHP-25, a novel anti-HIV peptide, which directly interacts with gp120 and thus has a potential to inhibit early stages of HIV-1 infection. PMID:25915507

  11. 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

  12. 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.

  13. 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.

  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. 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.

  16. Integrating GIS with AHP and Fuzzy Logic to generate hand, foot and mouth disease hazard zonation (HFMD-HZ) model in Thailand

    NASA Astrophysics Data System (ADS)

    Samphutthanon, R.; Tripathi, N. K.; Ninsawat, S.; Duboz, R.

    2014-12-01

    The main objective of this research was the development of an HFMD hazard zonation (HFMD-HZ) model by applying AHP and Fuzzy Logic AHP methodologies for weighting each spatial factor such as disease incidence, socio-economic and physical factors. The outputs of AHP and FAHP were input into a Geographic Information Systems (GIS) process for spatial analysis. 14 criteria were selected for analysis as important factors: disease incidence over 10 years from 2003 to 2012, population density, road density, land use and physical features. The results showed a consistency ratio (CR) value for these main criteria of 0.075427 for AHP, the CR for FAHP results was 0.092436. As both remained below the threshold of 0.1, the CR value were acceptable. After linking to actual geospatial data (disease incidence 2013) through spatial analysis by GIS for validation, the results of the FAHP approach were found to match more accurately than those of the AHP approach. The zones with the highest hazard of HFMD outbreaks were located in two main areas in central Muang Chiang Mai district including suburbs and Muang Chiang Rai district including the vicinity. The produced hazardous maps may be useful for organizing HFMD protection plans.

  17. Cosmological constant from the emergent gravity perspective

    NASA Astrophysics Data System (ADS)

    Padmanabhan, T.; Padmanabhan, Hamsa

    2014-05-01

    Observations indicate that our universe is characterized by a late-time accelerating phase, possibly driven by a cosmological constant Λ, with the dimensionless parameter Λ {LP2} ˜= 10-122, where LP = (Għ/c3)1/2 is the Planck length. In this review, we describe how the emergent gravity paradigm provides a new insight and a possible solution to the cosmological constant problem. After reviewing the necessary background material, we identify the necessary and sufficient conditions for solving the cosmological constant problem. We show that these conditions are naturally satisfied in the emergent gravity paradigm in which (i) the field equations of gravity are invariant under the addition of a constant to the matter Lagrangian and (ii) the cosmological constant appears as an integration constant in the solution. The numerical value of this integration constant can be related to another dimensionless number (called CosMIn) that counts the number of modes inside a Hubble volume that cross the Hubble radius during the radiation and the matter-dominated epochs of the universe. The emergent gravity paradigm suggests that CosMIn has the numerical value 4π, which, in turn, leads to the correct, observed value of the cosmological constant. Further, the emergent gravity paradigm provides an alternative perspective on cosmology and interprets the expansion of the universe itself as a quest towards holographic equipartition. We discuss the implications of this novel and alternate description of cosmology.

  18. Assessing the service quality of Iran military hospitals: Joint Commission International standards and Analytic Hierarchy Process (AHP) technique

    PubMed Central

    Bahadori, Mohammadkarim; Ravangard, Ramin; Yaghoubi, Maryam; Alimohammadzadeh, Khalil

    2014-01-01

    Background: Military hospitals are responsible for preserving, restoring and improving the health of not only armed forces, but also other people. According to the military organizations strategy, which is being a leader and pioneer in all areas, providing quality health services is one of the main goals of the military health care organizations. This study was aimed to evaluate the service quality of selected military hospitals in Iran based on the Joint Commission International (JCI) standards and comparing these hospitals with each other and ranking them using the analytic hierarchy process (AHP) technique in 2013. Materials and Methods: This was a cross-sectional and descriptive study conducted on five military hospitals, selected using the purposive sampling method, in 2013. Required data collected using checklists of accreditation standards and nominal group technique. AHP technique was used for prioritizing. Furthermore, Expert Choice 11.0 was used to analyze the collected data. Results: Among JCI standards, the standards of access to care and continuity of care (weight = 0.122), quality improvement and patient safety (weight = 0.121) and leadership and management (weight = 0.117) had the greatest importance, respectively. Furthermore, in the overall ranking, BGT (weight = 0.369), IHM (0.238), SAU (0.202), IHK (weight = 0.125) and SAB (weight = 0.066) ranked first to fifth, respectively. Conclusion: AHP is an appropriate technique for measuring the overall performance of hospitals and their quality of services. It is a holistic approach that takes all hospital processes into consideration. The results of the present study can be used to improve hospitals performance through identifying areas, which are in need of focus for quality improvement and selecting strategies to improve service quality. PMID:25250364

  19. Optimal Medical Equipment Maintenance Service Proposal Decision Support System combining Activity Based Costing (ABC) and the Analytic Hierarchy Process (AHP).

    PubMed

    da Rocha, Leticia; Sloane, Elliot; M Bassani, Jose

    2005-01-01

    This study describes a framework to support the choice of the maintenance service (in-house or third party contract) for each category of medical equipment based on: a) the real medical equipment maintenance management system currently used by the biomedical engineering group of the public health system of the Universidade Estadual de Campinas located in Brazil to control the medical equipment maintenance service, b) the Activity Based Costing (ABC) method, and c) the Analytic Hierarchy Process (AHP) method. Results show the cost and performance related to each type of maintenance service. Decision-makers can use these results to evaluate possible strategies for the categories of equipment. PMID:17281912

  20. Evaluation of Wheel Loaders in Open Pit Marble Quarrying by Using the AHP and Topsis Approaches / Ocena pracy ładowarki na podwoziu kołowym w odkrywkowej kopalni marmuru w oparciu o metody AHP i topsis

    NASA Astrophysics Data System (ADS)

    Kun, Mete; Topaloǧlu, Şeyda; Malli, Tahir

    2013-03-01

    The marble mining in Turkey has been rising since the early 80's. In relation to that, the marble income has become noticeably bigger than those of other mining sectors. In recent years, marble and natural stone export composes half of the total mine export with a value of two billion dollars. This rapid development observed in marble operation has increased the importance of mining economics, income-expenditure balance and cost analysis. The most important cost elements observed in marble quarrying are machinery and equipment, labor costs and geological structures of the field. The aim of this study is to is to propose a multi-criteria decision making (MCDM) approach to evaluate the wheel loader alternatives and select the best loader under multiple criteria. A two-step methodology based on two MCDM methods, which are namely the Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), are used in the evaluation procedure. More precisely, AHP is applied to determine the relative weights of evaluation criteria and TOPSIS is applied to rank the wheel loader alternatives. The proposed approach also provides a relatively simple and very well suited decision making tool for this type of decision making problems.

  1. Four-dimensional dose distributions of step-and-shoot IMRT delivered with real-time tumor tracking for patients with irregular breathing: Constant dose rate vs dose rate regulation

    SciTech Connect

    Yang Xiaocheng; Han-Oh, Sarah; Gui Minzhi; Niu Ying; Yu, Cedric X.; Yi Byongyong

    2012-09-15

    Purpose: Dose-rate-regulated tracking (DRRT) is a tumor tracking strategy that programs the MLC to track the tumor under regular breathing and adapts to breathing irregularities during delivery using dose rate regulation. Constant-dose-rate tracking (CDRT) is a strategy that dynamically repositions the beam to account for intrafractional 3D target motion according to real-time information of target location obtained from an independent position monitoring system. The purpose of this study is to illustrate the differences in the effectiveness and delivery accuracy between these two tracking methods in the presence of breathing irregularities. Methods: Step-and-shoot IMRT plans optimized at a reference phase were extended to remaining phases to generate 10-phased 4D-IMRT plans using segment aperture morphing (SAM) algorithm, where both tumor displacement and deformation were considered. A SAM-based 4D plan has been demonstrated to provide better plan quality than plans not considering target deformation. However, delivering such a plan requires preprogramming of the MLC aperture sequence. Deliveries of the 4D plans using DRRT and CDRT tracking approaches were simulated assuming the breathing period is either shorter or longer than the planning day, for 4 IMRT cases: two lung and two pancreatic cases with maximum GTV centroid motion greater than 1 cm were selected. In DRRT, dose rate was regulated to speed up or slow down delivery as needed such that each planned segment is delivered at the planned breathing phase. In CDRT, MLC is separately controlled to follow the tumor motion, but dose rate was kept constant. In addition to breathing period change, effect of breathing amplitude variation on target and critical tissue dose distribution is also evaluated. Results: Delivery of preprogrammed 4D plans by the CDRT method resulted in an average of 5% increase in target dose and noticeable increase in organs at risk (OAR) dose when patient breathing is either 10% faster or

  2. Application of an integrated multi-criteria decision making AHP-TOPSIS methodology for ETL software selection.

    PubMed

    Hanine, Mohamed; Boutkhoum, Omar; Tikniouine, Abdessadek; Agouti, Tarik

    2016-01-01

    Actually, a set of ETL software (Extract, Transform and Load) is available to constitute a major investment market. Each ETL uses its own techniques for extracting, transforming and loading data into data warehouse, which makes the task of evaluating ETL software very difficult. However, choosing the right software of ETL is critical to the success or failure of any Business Intelligence project. As there are many impacting factors in the selection of ETL software, the same process is considered as a complex multi-criteria decision making (MCDM) problem. In this study, an application of decision-making methodology that employs the two well-known MCDM techniques, namely Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods is designed. In this respect, the aim of using AHP is to analyze the structure of the ETL software selection problem and obtain weights of the selected criteria. Then, TOPSIS technique is used to calculate the alternatives' ratings. An example is given to illustrate the proposed methodology. Finally, a software prototype for demonstrating both methods is implemented. PMID:27006872

  3. Local Health Department Planning for a Radiological Emergency: An Application of the AHP2 Tool to Emergency Preparedness Prioritization

    PubMed Central

    McKallagat, Chris; Klebesadal, Amy

    2014-01-01

    Objective We tested the Analytical Hierarchy Process tool for its use in public health to identify potential gaps in emergency preparedness by local health departments (LHDs) in California and Hawaii during a radiological emergency. Methods We developed a dedicated tool called All-Hazards Preparedness Squared (AHP2) that can be used by those who are responsible for all-hazards preparedness planning and response to guide them while making strategic decisions both in preparing for and responding to a slow-moving incident while it is unfolding. The tool is an Internet-based survey that can be distributed among teams responsible for emergency preparedness and response. Twenty-eight participants from 16 LHDs in California and Hawaii responsible for coordinating preparedness and response in a radiological emergency participated in using the tool in 2013. We used the data to compare the perceived importance of different elements of preparedness among participants and identify gaps in preparedness of their organizations for meeting the challenges presented by a radiological incident. Results Clarity of information and transfer of information (to and from agency to public, state, and federal partners) were public health officials' dominant concerns while responding to an emergency. Participants also found that there were gaps in the adequacy of training and awareness of the chain of command during a radiological emergency. Conclusion This preliminary study indicates that the AHP2 tool could be used for decision making in all-hazards preparedness planning and response. PMID:25355985

  4. Fuzzy fault tree assessment based on improved AHP for fire and explosion accidents for steel oil storage tanks.

    PubMed

    Shi, Lei; Shuai, Jian; Xu, Kui

    2014-08-15

    Fire and explosion accidents of steel oil storage tanks (FEASOST) occur occasionally during the petroleum and chemical industry production and storage processes and often have devastating impact on lives, the environment and property. To contribute towards the development of a quantitative approach for assessing the occurrence probability of FEASOST, a fault tree of FEASOST is constructed that identifies various potential causes. Traditional fault tree analysis (FTA) can achieve quantitative evaluation if the failure data of all of the basic events (BEs) are available, which is almost impossible due to the lack of detailed data, as well as other uncertainties. This paper makes an attempt to perform FTA of FEASOST by a hybrid application between an expert elicitation based improved analysis hierarchy process (AHP) and fuzzy set theory, and the occurrence possibility of FEASOST is estimated for an oil depot in China. A comparison between statistical data and calculated data using fuzzy fault tree analysis (FFTA) based on traditional and improved AHP is also made. Sensitivity and importance analysis has been performed to identify the most crucial BEs leading to FEASOST that will provide insights into how managers should focus effective mitigation. PMID:25010458

  5. Solid waste disposal site selection with GIS and AHP methodology: a case study in Senirkent-Uluborlu (Isparta) Basin, Turkey.

    PubMed

    Sener, Sehnaz; Sener, Erhan; Karagüzel, Remzi

    2011-02-01

    The appropriate site selection for waste disposal is one of the major problems in waste management. Also, many environmental, economical, and political considerations must be adhered to. In this study, landfill site selection is performed using the Geographic Information System (GIS), the Analytical Hierarchy Process (AHP), and the remote sensing methods for the Senirkent-Uluborlu Basin. The basin is located in the Eğirdir Lake catchment area, which is one of the most important fresh water in Turkey. So, waste management must be regulated in the basin. For this aim, ten different criteria (lithology, surface water, aquifer, groundwater depth, land use, lineaments, aspect, elevation, slope, and distance to roads) are examined in relation to landfill site selection. Each criterion was identified and weighted using AHP. Then, each criterion is mapped using the GIS technique, and a suitability map is prepared by overlay analyses. The results indicate that 96.3% of the area in the basin is unsuitable; 1.6%, moderately suitable; and 2.1%, most suitable. Finally, suitable regions in the basin are determined for solid waste landfill disposal and checked in the field. The selected and investigated regions are considered to be suitable for the landfill. PMID:20213053

  6. 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.

  7. 21 CFR 1250.42 - Water systems; constant temperature bottles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 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...

  8. 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...

  9. 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...

  10. 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...

  11. 21 CFR 1250.42 - Water systems; constant temperature bottles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  12. 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.

  13. Philicities, Fugalities, and Equilibrium Constants.

    PubMed

    Mayr, Herbert; Ofial, Armin R

    2016-05-17

    . Benzhydrylium ions (diarylcarbenium ions) with para- and meta-substituents are used as reference compounds for these investigations, because their Lewis acidities and electrophilicities can be varied by many orders of magnitude, while the steric surroundings of the reaction centers are kept constant. The rate constants for their reactions with nucleophiles correlate linearly over a wide range with the Lewis acidities of the benzhydrylium ions: from slow reactions with late transition states to very fast reactions with early, reactant-like transition states (including reactions which proceed without an enthalpic barrier, ΔH(⧧) = 0). Thus, unequivocal evidence is obtained that even within a series of closely related reactions, the Leffler-Hammond α cannot be a measure for the position of the transition state. Differences in intrinsic barriers lead to deviations from the linear rate-equilibrium correlations and give rise to counterintuitive phenomena. Thus, 1,4-diazabicyclo[2.2.2]octane (DABCO) reacts with lower intrinsic barriers than 4-(dimethylamino)pyridine (DMAP) and, therefore, is a stronger nucleophile as well as a better nucleofuge than DMAP. Common synthetically used SN2 reactions are presented, in which weak nucleophiles replace stronger ones. Whereas solvolysis rates of alkoxy- and alkyl-substituted benzhydryl derivatives correlate linearly with the Lewis acidities of the resulting carbenium ions, this is not the case for amino-substituted benzhydrylium ions, where differences in intrinsic barriers play a major role. The common rule that a structural variation, which increases the electrophilicity of a carbocation at the same time reduces its electrofugality, does not hold any longer. The need to systematically analyze the role of intrinsic barriers is emphasized. PMID:27108991

  14. Assessment of groundwater vulnerability based on a modified DRASTIC model, GIS and an analytic hierarchy process (AHP) method: the case of Egirdir Lake basin (Isparta, Turkey)

    NASA Astrophysics Data System (ADS)

    Sener, Erhan; Davraz, Aysen

    2013-05-01

    A DRASTIC-model method based on a geographic information system (GIS) was used to study groundwater vulnerability in Egirdir Lake basin (Isparta, Turkey), an alluvial area that has suffered agricultural pollution. `Lineament' and `land use' were added to the DRASTIC parameters, and an analytic hierarchy process (AHP) method determined the rating coefficients of each parameter. The effect of lineament and land-use parameters on the resulting vulnerability maps was determined with a single-parameter sensitivity analysis. Of the DRASTIC parameters, land use affects the aquifer vulnerability map most and lineament affects it least, after topography. A simple linear regression analysis assessed the statistical relation between groundwater nitrate concentration and the aquifer vulnerability areas; the highest R 2 value was obtained with the modified-DRASTIC-AHP method. The DRASTIC vulnerability map shows that only the shoreline of Egirdir Lake and the alluvium units have high contamination potential. In this respect, the modified DRASTIC vulnerability map is quite similar. According to the modified-DRASTIC-AHP method, the lakeshore areas of Senirkent-Uluborlu and Hoyran plains, and all of the Yalvaç-Gelendost plain, have high contamination potential. Analyses confirm that groundwater nitrate content is high in these areas. By comparison, the modified-DRASTIC-AHP method has provided more valid results.

  15. Formulas for determining rotational constants

    NASA Astrophysics Data System (ADS)

    Guelachvili, G.

    This document is part of Subvolume B `Linear Triatomic Molecules', Part 9, of Volume 20 `Molecular Constants mostly from Infrared Spectroscopy' of Landolt-Börnstein Group II `Molecules and Radicals'. Part of the introduction, it states formulas for determining rotational constants, band center, band origin, and quadrupole coupling. Specific comments relate to BHO (HBO) and COS (OCS).

  16. QCD coupling constants and VDM

    SciTech Connect

    Erkol, G.; Ozpineci, A.; Zamiralov, V. S.

    2012-10-23

    QCD sum rules for coupling constants of vector mesons with baryons are constructed. The corresponding QCD sum rules for electric charges and magnetic moments are also derived and with the use of vector-meson-dominance model related to the coupling constants. The VDM role as the criterium of reciprocal validity of the sum rules is considered.

  17. 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

  18. Molecular Analysis of Isoniazid-Resistant Mycobacterium tuberculosis Isolates from England and Wales Reveals the Phylogenetic Significance of the ahpC −46A Polymorphism

    PubMed Central

    Baker, L. V.; Brown, T. J.; Maxwell, O.; Gibson, A. L.; Fang, Z.; Yates, M. D.; Drobniewski, F. A.

    2005-01-01

    The present study investigated the prevalence and diagnostic potential of the most commonly reported mutations associated with isoniazid resistance, katG 315Thr, katG 315Asn, inhA −15T, inhA −8A, and the oxyR-ahpC intergenic region, in a population sample of 202 isoniazid-resistant Mycobacterium tuberculosis isolates and 176 randomly selected fully sensitive isolates from England and Wales identified by using a directed oligonucleotide array and limited DNA sequencing. The strains were recovered from patients originating from 29 countries; 41 isolates were multidrug resistant. Mutations affecting katG 315, the inhA promoter, and the oxyR-ahpC intergenic region were found in 62.7, 21.9, and 30% of 169 genotypically distinct isoniazid-resistant isolates, respectively, whereas they were found in 0, 0, and 8% of susceptible strains, respectively. The frequency of mutation at each locus was unrelated to the resistance profile or previous antituberculous drug therapy. The commonest mutation in the oxyR-ahpC intergenic region, ahpC −46A, was present in 23.7% of isoniazid-resistant isolates and 7.5% of susceptible isolates. This proved to be a phylogenetic marker for a subgroup of M. tuberculosis strains originating on the Indian subcontinent, which shared IS6110-based restriction fragment length polymorphism and spoligotype features with the Delhi strain and Central Asian strain CAS1; and this marker is strongly associated with isoniazid resistance and the katG 315Thr mutation. In total, 82.8% of unrelated isoniazid-resistant isolates could be identified by analysis of just two loci: katG 315 and the inhA promoter. Analysis of the oxyR-ahpC intergenic region, although phylogenetically interesting, does not contribute significantly to further identification of isoniazid-resistant isolates. PMID:15793126

  19. 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.

  20. Evaluation of B2C website based on the usability factors by using fuzzy AHP & hierarchical fuzzy TOPSIS

    NASA Astrophysics Data System (ADS)

    Masudin, I.; Saputro, T. E.

    2016-02-01

    In today's technology, electronic trading transaction via internet has been utilized properly with rapid growth. This paper intends to evaluate related to B2C e-commerce website in order to find out the one which meets the usability factors better than another. The influential factors to B2C e-commerce website are determined for two big retailer websites. The factors are investigated based on the consideration of several studies and conformed to the website characteristics. The evaluation is conducted by using different methods namely fuzzy AHP and hierarchical fuzzy TOPSIS so that the final evaluation can be compared. Fuzzy triangular number is adopted to deal with imprecise judgment under fuzzy environment.

  1. Integrated GIS/AHP-based flood disaster risk assessment and zonation: a case study of Henan Province, China

    NASA Astrophysics Data System (ADS)

    Li, Junling; Chen, Huailiang; Liu, Zhongyang; Zou, Chunhui

    2010-10-01

    In this paper, according to the flood risk-influencing hazard of disaster-formatire factors, the stability of hazard-pregnant environment and the vulnerability of hazard bearing body, the indexes of precipitation, runoff, river, terrain, population and economy are considered. Taking, Henan Province as the focus area, and county as the administrative unit, both the hazard assessment map and the vulnerability assessment map of the flood disaster are acquired based on GIS and AHP integrated method. Finally, the comprehensive hazard evaluating map of the flood disaster was drawn. The case study shows that the GIS-based category model is effective in flood risk zonation. Therefore the paper has a certain theoretical and practical significance.

  2. A Framework for Establishment of a Risk Assessment Model for Soil Erosion by Integrating the AHP Approach and Modeling Techniques

    NASA Astrophysics Data System (ADS)

    Wang, M.; Wu, Q.

    2006-12-01

    A new approach for establishment of an analytical risk assessment model to evaluate the risk index for soil erosion is proposed in which the analytical hierarchy process (AHP) approach and the model calibration and validation processes are integrated. A flowchart presenting a general procedure for implementation of the proposed approach is included. A case study is presented to demonstrate applications of this proposed framework through investigation of soil erosion by water in a joining area that partially covers the Shanxi province, Shaanxi province, and Inner Mongolia Autonomous Region of China. Based on field survey and information analyses, pertinent factors for soil erosion by water in this region are assessed and nine dominating factors are identified. The dominating factors considered include the soil type, rainstorm intensity, landform accounting for physiognomy type, ravine density, and land slope, vegetation coverage, mining area, level of water and soil conservation, and type of land uses. The GIS thematic layers of degrees of risk on soil erosion for those dominating factors are constructed. The weight of each thematic layer is determined through the AHP approach and modeling techniques. This model is then applied in predicting development of soil erosion at a typical scenario for this study area. A brief discussion on construction and application of this model is presented. It is demonstrated that the presented methodology is practicable for establishing a risk assessment mode for soil erosion by water for an area of interest where pertinent information such as remote sensing data is available. Furthermore, a predictive soil erosion model established by the proposed approach may be implemented for investigations of other pertinent environmental issues such as relative and quantitative risk assessments of migration of absorbed contaminants in soil, resulted from agricultural non-point source pollution, into a river or lake through soil erosion.

  3. Constant crunch coordinates for black hole simulations

    NASA Astrophysics Data System (ADS)

    Gentle, Adrian P.; Holz, Daniel E.; Kheyfets, Arkady; Laguna, Pablo; Miller, Warner A.; Shoemaker, Deirdre M.

    2001-03-01

    We reinvestigate the utility of time-independent constant mean curvature foliations for the numerical simulation of a single spherically symmetric black hole. Each spacelike hypersurface of such a foliation is endowed with the same constant value of the trace of the extrinsic curvature tensor K. Of the three families of K-constant surfaces possible (classified according to their asymptotic behaviors), we single out a subfamily of singularity-avoiding surfaces that may be particularly useful, and provide an analytic expression for the closest approach such surfaces make to the singularity. We then utilize a nonzero shift to yield families of K-constant surfaces which (1) avoid the black hole singularity, and thus the need to excise the singularity, (2) are asymptotically null, aiding in gravity wave extraction, (3) cover the physically relevant part of the spacetime, (4) are well behaved (regular) across the horizon, and (5) are static under evolution, and therefore have no ``grid stretching/ sucking'' pathologies. Preliminary numerical runs demonstrate that we can stably evolve a single spherically symmetric static black hole using this foliation. We wish to emphasize that this coordinatization produces K-constant surfaces for a single black hole spacetime that are regular, static, and stable throughout their evolution.

  4. Constant Communities in Complex Networks

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  5. Molecular dynamics at constant temperature and pressure

    NASA Astrophysics Data System (ADS)

    Toxvaerd, S.

    1993-01-01

    Algorithms for molecular dynamics (MD) at constant temperature and pressure are investigated. The ability to remain in a regular orbit in an intermittent chaotic regime is used as a criterion for long-time stability. A simple time-centered algorithm (leap frog) is found to be the most stable of the commonly used algorithms in MD. A model of N one-dimensional dimers with a double-well intermolecular potential, for which the distribution functions at constant temperature T and pressure P can be calculated, is used to investigate MD-NPT dynamics. A time-centered NPT algorithm is found to sample correctly and to be very robust with respect to volume scaling.

  6. The Arabidopsis thaliana response regulator ARR22 is a putative AHP phospho-histidine phosphatase expressed in the chalaza of developing seeds

    PubMed Central

    Horák, Jakub; Grefen, Christopher; Berendzen, Kenneth W; Hahn, Achim; Stierhof, York-Dieter; Stadelhofer, Bettina; Stahl, Mark; Koncz, Csaba; Harter, Klaus

    2008-01-01

    Background The Arabidopsis response regulator 22 (ARR22) is one of two members of a recently defined novel group of two-component system (TCS) elements. TCSs are stimulus perception and response modules of prokaryotic origin, which signal by a His-to-Asp phosphorelay mechanism. In plants, TCS regulators are involved in hormone response pathways, such as those for cytokinin and ethylene. While the functions of the other TCS elements in Arabidopsis, such as histidine kinases (AHKs), histidine-containing phosphotransfer proteins (AHPs) and A-type and B-type ARRs are becoming evident, the role of ARR22 is poorly understood. Results We present evidence that ARR22 is a preferentially cytoplasmic protein, exclusively expressed in the chalaza of developing seeds. ARR22 specifically interacts with AHP2, AHP3 and AHP5 in yeast and living plant cells. Two new loss-of-function alleles, arr22-2 and arr22-3, were isolated and characterized. With respect to their morphology and metabolite status, no significant difference in the developing seeds of the arr22 mutants was observed compared to wild type. The genetic complementation of the arr22 mutants with a genomic ARR22 fragment resulted in plants (arr22/gARR22) with a pleiotropic phenotype of different penetrance. This phenotype was not observed when the phosphorylatable Asp74 of ARR22 was changed to either a dominant-active Glu or a dominant-inactive Asn. The phenotype of the arr22/gARR22 plants was comparable to that of multiple ahk, ahp and B-type arr mutants. Conclusion Our results favor the model that ARR22 acts as a phospho-histidine phosphatase on specific AHPs in the cytoplasm of Arabidopsis chalaza cells. The lack of any aberrant morphological and metabolite phenotype in the seeds of the arr22 mutants indicates that ARR22 is probably primarily responsible for the fine tuning of specific branches of chalaza-based TCS signalling. Even when slightly mis-expressed, ARR22 interferes with hormone homeostasis in non

  7. Optical constants of solid methane

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Thompson, W. R.; Sagan, C.; Arakawa, E. T.; Bruel, C.; Judish, J. P.; Khanna, R. K.; Pollack, J. B.

    1989-01-01

    Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH4 for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. Preliminary results are presented of the optical constants of solid methane for the 0.4 to 2.6 micron region. K is reported for both the amorphous and the crystalline (annealed) states. Using the previously measured values of the real part of the refractive index, n, of liquid methane at 110 K n is computed for solid methane using the Lorentz-Lorentz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for condensed CH4.

  8. Optical constants of solid methane

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Thompson, W. R.; Sagan, C.; Arakawa, E. T.; Bruel, C.; Judish, J. P.; Khanna, R. K.; Pollack, J. B.

    1990-01-01

    Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH4 for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. Preliminary results are presented on the optical constants of solid methane for the 0.4 to 2.6 micrometer region. Deposition onto a substrate at 10 K produces glassy (semi-amorphous) material. Annealing this material at approximately 33 K for approximately 1 hour results in a crystalline material as seen by sharper, more structured bands and negligible background extinction due to scattering. The constant k is reported for both the amorphous and the crystalline (annealed) states. Typical values (at absorption maxima) are in the .001 to .0001 range. Below lambda = 1.1 micrometers the bands are too weak to be detected by transmission through the films less than or equal to 215 micrometers in thickness, employed in the studies to date. Using previously measured values of the real part of the refractive index, n, of liquid methane at 110 K, n is computed for solid methane using the Lorentz-Lorenz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for

  9. Cosmologies with variable gravitational constant

    NASA Astrophysics Data System (ADS)

    Narlikar, J. V.

    1983-03-01

    In 1937 Dirac presented an argument, based on the socalled large dimensionless numbers, which led him to the conclusion that the Newtonian gravitational constant G changes with epoch. Towards the end of the last century Ernst Mach had given plausible arguments to link the property of inertia of matter to the large scale structure of the universe. Mach's principle also leads to cosmological models with a variable gravitational constant. Three cosmologies which predict a variable G are discussed in this paper both from theoretical and observational points of view.

  10. An Integrated MCDM Model for Conveyor Equipment Evaluation and Selection in an FMC Based on a Fuzzy AHP and Fuzzy ARAS in the Presence of Vagueness.

    PubMed

    Nguyen, Huu-Tho; Dawal, Siti Zawiah Md; Nukman, Yusoff; Rifai, Achmad P; Aoyama, Hideki

    2016-01-01

    The conveyor system plays a vital role in improving the performance of flexible manufacturing cells (FMCs). The conveyor selection problem involves the evaluation of a set of potential alternatives based on qualitative and quantitative criteria. This paper presents an integrated multi-criteria decision making (MCDM) model of a fuzzy AHP (analytic hierarchy process) and fuzzy ARAS (additive ratio assessment) for conveyor evaluation and selection. In this model, linguistic terms represented as triangular fuzzy numbers are used to quantify experts' uncertain assessments of alternatives with respect to the criteria. The fuzzy set is then integrated into the AHP to determine the weights of the criteria. Finally, a fuzzy ARAS is used to calculate the weights of the alternatives. To demonstrate the effectiveness of the proposed model, a case study is performed of a practical example, and the results obtained demonstrate practical potential for the implementation of FMCs. PMID:27070543

  11. An Integrated MCDM Model for Conveyor Equipment Evaluation and Selection in an FMC Based on a Fuzzy AHP and Fuzzy ARAS in the Presence of Vagueness

    PubMed Central

    Nguyen, Huu-Tho; Md Dawal, Siti Zawiah; Nukman, Yusoff; P. Rifai, Achmad; Aoyama, Hideki

    2016-01-01

    The conveyor system plays a vital role in improving the performance of flexible manufacturing cells (FMCs). The conveyor selection problem involves the evaluation of a set of potential alternatives based on qualitative and quantitative criteria. This paper presents an integrated multi-criteria decision making (MCDM) model of a fuzzy AHP (analytic hierarchy process) and fuzzy ARAS (additive ratio assessment) for conveyor evaluation and selection. In this model, linguistic terms represented as triangular fuzzy numbers are used to quantify experts’ uncertain assessments of alternatives with respect to the criteria. The fuzzy set is then integrated into the AHP to determine the weights of the criteria. Finally, a fuzzy ARAS is used to calculate the weights of the alternatives. To demonstrate the effectiveness of the proposed model, a case study is performed of a practical example, and the results obtained demonstrate practical potential for the implementation of FMCs. PMID:27070543

  12. Dynamical Cosmological Constant in R 3 Gravity

    NASA Astrophysics Data System (ADS)

    Zare, Nasser; Fathi, Mohsen

    2015-03-01

    In this paper, we go through the famous f( R) theories of gravity, but keeping a peculiar one, namely R 3 modification. Moreover, instead of a coordinate free cosmological parameter, we take it to be a function of time. Having all these stuff, we investigate the notions of standard cosmology model, in the context of R 3 modification to general relativity, and in various regimes, we study the dynamical cosmological constant.

  13. Time?

    NASA Astrophysics Data System (ADS)

    Amoroso, Richard L.

    2013-09-01

    The concept of time in the `clockwork' Newtonian world was irrelevant; and has generally been ignored until recently by several generations of physicists since the implementation of quantum mechanics. We will set aside the utility of time as a property relating to physical calculations of events relating to a metrics line element or as an aspect of the transformation of a particles motion/interaction in a coordinate system or in relation to thermodynamics etc., i.e. we will discard all the usual uses of time as a concept used to circularly define physical parameters in terms of other physical parameters; concentrating instead on time as an aspect of the fundamental cosmic topology of our virtual reality especially as it inseparably relates to the nature and role of the observer in natural science.

  14. Damping constant estimation in magnetoresistive readers

    SciTech Connect

    Stankiewicz, Andrzej Hernandez, Stephanie

    2015-05-07

    The damping constant is a key design parameter in magnetic reader design. Its value can be derived from bulk or sheet film ferromagnetic resonance (FMR) line width. However, dynamics of nanodevices is usually defined by presence of non-uniform modes. It triggers new damping mechanisms and produces stronger damping than expected from traditional FMR. This work proposes a device-level technique for damping evaluation, based on time-domain analysis of thermally excited stochastic oscillations. The signal is collected using a high bandwidth oscilloscope, by direct probing of a biased reader. Recorded waveforms may contain different noise signals, but free layer FMR is usually a dominating one. The autocorrelation function is a reflection of the damped oscillation curve, averaging out stochastic contributions. The damped oscillator formula is fitted to autocorrelation data, producing resonance frequency and damping constant values. Restricting lag range allows for mitigation of the impact of other phenomena (e.g., reader instability) on the damping constant. For a micromagnetically modeled reader, the technique proves to be much more accurate than the stochastic FMR line width approach. Application to actual reader waveforms yields a damping constant of ∼0.03.

  15. Damping constant estimation in magnetoresistive readers

    NASA Astrophysics Data System (ADS)

    Stankiewicz, Andrzej; Hernandez, Stephanie

    2015-05-01

    The damping constant is a key design parameter in magnetic reader design. Its value can be derived from bulk or sheet film ferromagnetic resonance (FMR) line width. However, dynamics of nanodevices is usually defined by presence of non-uniform modes. It triggers new damping mechanisms and produces stronger damping than expected from traditional FMR. This work proposes a device-level technique for damping evaluation, based on time-domain analysis of thermally excited stochastic oscillations. The signal is collected using a high bandwidth oscilloscope, by direct probing of a biased reader. Recorded waveforms may contain different noise signals, but free layer FMR is usually a dominating one. The autocorrelation function is a reflection of the damped oscillation curve, averaging out stochastic contributions. The damped oscillator formula is fitted to autocorrelation data, producing resonance frequency and damping constant values. Restricting lag range allows for mitigation of the impact of other phenomena (e.g., reader instability) on the damping constant. For a micromagnetically modeled reader, the technique proves to be much more accurate than the stochastic FMR line width approach. Application to actual reader waveforms yields a damping constant of ˜0.03.

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

    NASA Technical Reports Server (NTRS)

    Adams, P. J.

    1983-01-01

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

  17. Constant-amplitude RC oscillator

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Westbrook, R. M.

    1970-01-01

    Sinusoidal oscillator has a frequency determined by resistance-capacitance /RC/ values of two charge control devices and a constant-amplitude voltage independent of frequency and RC values. RC elements provide either voltage-control, resistance-control, or capacitance-control of the frequency.

  18. Acute Limonene Toxicity in Escherichia coli Is Caused by Limonene Hydroperoxide and Alleviated by a Point Mutation in Alkyl Hydroperoxidase AhpC

    PubMed Central

    Chubukov, Victor; Mingardon, Florence; Schackwitz, Wendy; Baidoo, Edward E. K.; Alonso-Gutierrez, Jorge; Hu, Qijun; Lee, Taek Soon; Keasling, Jay D.

    2015-01-01

    Limonene, a major component of citrus peel oil, has a number of applications related to microbiology. The antimicrobial properties of limonene make it a popular disinfectant and food preservative, while its potential as a biofuel component has made it the target of renewable production efforts through microbial metabolic engineering. For both applications, an understanding of microbial sensitivity or tolerance to limonene is crucial, but the mechanism of limonene toxicity remains enigmatic. In this study, we characterized a limonene-tolerant strain of Escherichia coli and found a mutation in ahpC, encoding alkyl hydroperoxidase, which alleviated limonene toxicity. We show that the acute toxicity previously attributed to limonene is largely due to the common oxidation product limonene hydroperoxide, which forms spontaneously in aerobic environments. The mutant AhpC protein with an L-to-Q change at position 177 (AhpCL177Q) was able to alleviate this toxicity by reducing the hydroperoxide to a more benign compound. We show that the degree of limonene toxicity is a function of its oxidation level and that nonoxidized limonene has relatively little toxicity to wild-type E. coli cells. Our results have implications for both the renewable production of limonene and the applications of limonene as an antimicrobial. PMID:25934627

  19. Acute Limonene Toxicity in Escherichia coli Is Caused by Limonene Hydroperoxide and Alleviated by a Point Mutation in Alkyl Hydroperoxidase AhpC.

    PubMed

    Chubukov, Victor; Mingardon, Florence; Schackwitz, Wendy; Baidoo, Edward E K; Alonso-Gutierrez, Jorge; Hu, Qijun; Lee, Taek Soon; Keasling, Jay D; Mukhopadhyay, Aindrila

    2015-07-01

    Limonene, a major component of citrus peel oil, has a number of applications related to microbiology. The antimicrobial properties of limonene make it a popular disinfectant and food preservative, while its potential as a biofuel component has made it the target of renewable production efforts through microbial metabolic engineering. For both applications, an understanding of microbial sensitivity or tolerance to limonene is crucial, but the mechanism of limonene toxicity remains enigmatic. In this study, we characterized a limonene-tolerant strain of Escherichia coli and found a mutation in ahpC, encoding alkyl hydroperoxidase, which alleviated limonene toxicity. We show that the acute toxicity previously attributed to limonene is largely due to the common oxidation product limonene hydroperoxide, which forms spontaneously in aerobic environments. The mutant AhpC protein with an L-to-Q change at position 177 (AhpC(L177Q)) was able to alleviate this toxicity by reducing the hydroperoxide to a more benign compound. We show that the degree of limonene toxicity is a function of its oxidation level and that nonoxidized limonene has relatively little toxicity to wild-type E. coli cells. Our results have implications for both the renewable production of limonene and the applications of limonene as an antimicrobial. PMID:25934627

  20. Crystallization and preliminary crystallographic analysis of decameric and monomeric forms of C49S mutant thioredoxin-dependent AhpC from Helicobacter pylori

    SciTech Connect

    Supangat; Seo, Kyung Hye; Furqoni, Ahmad; Kwon, Young-Chul; Cho, Myung-Je; Rhee, Kwang-Ho; Lee, Sang Yeol; Lee, Kon Ho

    2008-05-01

    Decameric and monomeric forms of recombinant C49S mutant AhpC from H. pylori have been crystallized. Diffraction data were collected to 2.8 and 2.25 Å, respectively. Cys49Ser mutant Helicobacter pylori alkyl hydroperoxide reductase (C49S HpAhpC) was purified under reducing conditions in monomeric and decameric forms. The monomeric form was crystallized by the hanging-drop vapour-diffusion method. The crystals diffracted to 2.25 Å resolution and belonged to space group C2, with unit-cell parameters a = 245.8, b = 140.7, c = 189.5 Å, β = 127°, and contained 20 molecules in the asymmetric unit. A crystal of the decameric form was obtained by the microbatch crystallization method and diffracted to 2.8 Å resolution. It belonged to space group C222, with unit-cell parameters a = 257.5, b = 417.5, c = 95.6 Å. The structure of the monomeric form of C49S HpAhpC has been solved by the molecular-replacement method.

  1. Determining the most suitable areas for artificial groundwater recharge via an integrated PROMETHEE II-AHP method in GIS environment (case study: Garabaygan Basin, Iran).

    PubMed

    Nasiri, Hossein; Boloorani, Ali Darvishi; Sabokbar, Hassan Ali Faraji; Jafari, Hamid Reza; Hamzeh, Mohamad; Rafii, Yusef

    2013-01-01

    Flood spreading is a suitable strategy for controlling and benefiting from floods. Selecting suitable areas for flood spreading and directing the floodwater into permeable formations are amongst the most effective strategies in flood spreading projects. Having combined geographic information systems (GIS) and multi-criteria decision analysis approaches, the present study sought to locate the most suitable areas for flood spreading operation in the Garabaygan Basin of Iran. To this end, the data layers relating to the eight effective factors were prepared in GIS environment. This stage was followed by elimination of the exclusionary areas for flood spreading while determining the potentially suitable ones. Having closely examined the potentially suitable areas using the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) II and analytic hierarchy process (AHP) methods, the land suitability map for flood spreading was produced. The PROMETHEE II and AHP were used for ranking all the alternatives and weighting the criteria involved, respectively. The results of the study showed that most suitable areas for the artificial groundwater recharge are located in Quaternary Q(g) and Q(gsc) geologic units and in geomorphological units of pediment and Alluvial fans with slopes not exceeding 3%. Furthermore, significant correspondence between the produced map and the control areas, where the flood spreading projects were successfully performed, provided further evidence for the acceptable efficiency of the integrated PROMETHEE II-AHP method in locating suitable flood spreading areas. PMID:22402992

  2. The 1% concordance Hubble constant

    SciTech Connect

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

    2014-10-20

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

  3. Optical constants of solid methane

    SciTech Connect

    Khare, B.N.; Thompson, W.R.; Sagan, C. . Lab. for Planetary Studies); Arakawa, E.T.; Bruel, C.; Judish, J.P. ); Khanna, R.K. . Dept. of Chemistry and Biochemistry); Pollack, J.B. . Ames Research Center)

    1989-01-01

    Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH{sub 4} for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. We present preliminary results of the optical constants of solid methane for the 0.4 {mu}m to 2.6 {mu}m region. We report k for both the amorphous and the crystalline (annealed) states. Using our previously measured values of the real part of the refractive index, n, of liquid methane at 110{degree}K (Bull. Am. Phys. Soc.31, 700 (1986)) we compute n for solid methane using the Lorentz-Lorentz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for condensed CH{sub 4}. 33 refs., 6 figs., 2 tabs.

  4. Effects of constant-current/constant-voltage charge parameters on lead-acid traction cell performance

    SciTech Connect

    Deluca, W.H.; Biwer, R.L.; Yao, N.P.

    1981-01-01

    A factor described for the application of battery systems for electric vehicle propulsion is the methodology of charging. It was quantitatively determined that both the total charge cycle time and the maximum charging rate (constant-current level) are limited by battery charge acceptance. The test system and procedures are outlined, acquired battery parameter data presented, and conclusions discussed.

  5. What is Fine-structure Constant?

    NASA Astrophysics Data System (ADS)

    Goradia, Shantilal

    2008-10-01

    Equation in [1] α>= 1/ ln λ, linking fine-structure constant and cosmological constant derived by using S = k ln W, the total number of microstates used (W) is 10^60, justified based on a unique age tag attached to each Planck time. The OPEN and CLOSED states of the particle's mouth illustrated in [1] could be two different types of entropic repositioning pulses, say attractive and repulsive. They need not be confused as affecting the number of microstates. The characteristics of a microstate need not change the number of microstates. Mathematically then, W = N! / n!(N-n)!; where N = 10^60 and n =1; giving W = 10^60, used in [1]. There are reasons to consider each Planck time as unique microstate based on its unique age. While investigating the proposal in terms of other theories, one has to be to keep in mind that the knowledge that created one problem cannot solve another. Refer to [1] Goradia, Shantilal, ``What is Fine-structure Constant?'' http://www.arXiv.org/pdf/physics/0210040v3.

  6. Effect of a positive cosmological constant on cosmic strings

    SciTech Connect

    Bhattacharya, Sourav; Lahiri, Amitabha

    2008-09-15

    We study cosmic Nielsen-Olesen strings in space-times with a positive cosmological constant. For the free cosmic string in a cylindrically symmetric space-time, we calculate the contribution of the cosmological constant to the angle deficit, and to the bending of null geodesics. For a cosmic string in a Schwarzschild-de Sitter space-time, we use Kruskal patches around the inner and outer horizons to show that a thin string can pierce them.

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

    PubMed

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

    2002-01-21

    We investigate the cosmological consequences of a theory in which the electric charge e can vary. In this theory the fine structure "constant," alpha, remains almost constant in the radiation era, undergoes a small increase in the matter era, but approaches a constant value when the universe starts accelerating because of a positive cosmological constant. This model satisfies geonuclear, nucleosynthesis, and cosmic microwave background constraints on time variation in alpha, while fitting the observed accelerating Universe and evidence for small alpha variations in quasar spectra. It also places specific restrictions on the nature of the dark matter. Further tests, involving stellar spectra and Eötvös experiments, are proposed. PMID:11801051

  8. Pole placement with constant gain output feedback

    NASA Technical Reports Server (NTRS)

    Sridhar, B.; Lindorff, D. P.

    1972-01-01

    Given a linear time invariant multivariable system with m inputs and p outputs, it was shown that p closed loop poles of the system can be preassigned arbitrarily using constant gain output feedback provided (A circumflex, B circumflex) is controllable. These data show that if (A circumflex, B circumflex, C circumflex) is controllable and observable, and Rank B circumflex = m, Rank C circumflex = p, then max (m,p) poles of the system can be assigned arbitarily using constant gain output feedback. Further, it is shown that in some cases more than max (m,p) poles can be arbitrarily assigned. A least square design technique is outlined to approximate the desired pole locations when it is not possible to place all the poles.

  9. Quaternions as astrometric plate constants

    NASA Technical Reports Server (NTRS)

    Jefferys, William H.

    1987-01-01

    A new method for solving problems in relative astrometry is proposed. In it, the relationship between the measured quantities and the components of the position vector of a star is modeled using quaternions, in effect replacing the plate constants of a standard four-plate-constant solution with the four components of a quaternion. The method allows a direct solution for the position vectors of the stars, and hence for the equatorial coordinates. Distortions, magnitude, and color effects are readily incorporated into the formalism, and the method is directly applicable to overlapping-plate problems. The advantages of the method include the simplicity of the resulting equations, their freedom from singularities, and the fact that trigonometric functions and tangential point transformations are not needed to model the plate material. A global solution over the entire sky is possible.

  10. Confinement from constant field condensates

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Guendelman, Eduardo; Spallucci, Euro

    2007-01-01

    For (2 + 1)- and (3 + 1)-dimensional reformulated SU (2) Yang-Mills theory, we compute the interaction potential within the framework of the gauge-invariant but path-dependent variables formalism. This reformulation is due to the presence of a constant gauge field condensate. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges. This result is equivalent to that of the massive Schwinger model.

  11. An approach for environmental risk assessment of engineered nanomaterials using Analytical Hierarchy Process (AHP) and fuzzy inference rules.

    PubMed

    Topuz, Emel; van Gestel, Cornelis A M

    2016-01-01

    The usage of Engineered Nanoparticles (ENPs) in consumer products is relatively new and there is a need to conduct environmental risk assessment (ERA) to evaluate their impacts on the environment. However, alternative approaches are required for ERA of ENPs because of the huge gap in data and knowledge compared to conventional pollutants and their unique properties that make it difficult to apply existing approaches. This study aims to propose an ERA approach for ENPs by integrating Analytical Hierarchy Process (AHP) and fuzzy inference models which provide a systematic evaluation of risk factors and reducing uncertainty about the data and information, respectively. Risk is assumed to be the combination of occurrence likelihood, exposure potential and toxic effects in the environment. A hierarchy was established to evaluate the sub factors of these components. Evaluation was made with fuzzy numbers to reduce uncertainty and incorporate the expert judgements. Overall score of each component was combined with fuzzy inference rules by using expert judgements. Proposed approach reports the risk class and its membership degree such as Minor (0.7). Therefore, results are precise and helpful to determine the risk management strategies. Moreover, priority weights calculated by comparing the risk factors based on their importance for the risk enable users to understand which factor is effective on the risk. Proposed approach was applied for Ag (two nanoparticles with different coating) and TiO2 nanoparticles for different case studies. Results verified the proposed benefits of the approach. PMID:27131016

  12. Evaluation of key driver categories influencing sustainable waste management development with the analytic hierarchy process (AHP): Serbia example.

    PubMed

    Tot, Bojana; Srđević, Bojan; Vujić, Bogdana; Russo, Mário Augusto Tavares; Vujić, Goran

    2016-08-01

    The problems of waste management have become increasingly complex in recent decades. The increasing amount of generated waste, adopted legislation in the field of waste management, administrative issues, economic impacts and social awareness are important drivers in achieving a sustainable waste management system. However, in practice, there are many other drivers that are often mutually in conflict. The purpose of this research is to define the precise driver and their corresponding sub-drivers, which are relevant for developing a waste management system and, on the basis of their importance, to determine which has the predominant influence on the slow development of a waste management system at the national and regional level, within the Republic of Serbia and similar countries of southeast Europe. This research presents two levels of decision making: the first is a pair-wise comparison of the drivers in relation to the goal and the second is a pair-wise comparison of the sub-drivers in relation to the driver and in relation to the goal. Results of performed analyses on the waste management drivers were integrated via the decision-making process supported by an analytic hierarchy process (AHP). The final results of this research shows that the Institutional-Administrative driver is the most important for developing a sustainable waste management system. PMID:27288689

  13. Environmental hazard mapping using GIS and AHP - A case study of Dong Trieu District in Quang Ninh Province, Vietnam

    NASA Astrophysics Data System (ADS)

    Anh, N. K.; Phonekeo, V.; My, V. C.; Duong, N. D.; Dat, P. T.

    2014-02-01

    In recent years, Vietnamese economy has been growing up rapidly and caused serious environmental quality plunging, especially in industrial and mining areas. It brings an enormous threat to a socially sustainable development and the health of human beings. Environmental quality assessment and protection are complex and dynamic processes, since it involves spatial information from multi-sector, multi-region and multi-field sources and needs complicated data processing. Therefore, an effective environmental protection information system is needed, in which considerable factors hidden in the complex relationships will become clear and visible. In this paper, the authors present the methodology which was used to generate environmental hazard maps which are applied to the integration of Analytic Hierarchy Process (AHP) and Geographical Information system (GIS). We demonstrate the results that were obtained from the study area in Dong Trieu district. This research study has contributed an overall perspective of environmental quality and identified the devastated areas where the administration urgently needs to establish an appropriate policy to improve and protect the environment.

  14. Computing the dielectric constant of liquid water at constant dielectric displacement

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Sprik, Michiel

    2016-04-01

    The static dielectric constant of liquid water is computed using classical force field based molecular dynamics simulation at fixed electric displacement D . The method to constrain the electric displacement is the finite-temperature classical variant of the constant D method developed by Stengel, Spaldin, and Vanderbilt [Nat. Phys. 5, 304 (2009), 10.1038/nphys1185]. There is also a modification of this scheme imposing fixed values of the macroscopic field E . The method is applied to the popular SPC/E model of liquid water. We compare four different estimates of the dielectric constant, two obtained from fluctuations of the polarization at D =0 and E =0 and two from the variation of polarization with finite D and E . It is found that all four estimates agree when properly converged. The computational effort to achieve convergence varies, however, with constant D calculations being substantially more efficient. We attribute this difference to the much shorter relaxation time of longitudinal polarization compared to transverse polarization accelerating constant D calculations.

  15. A constant current source for extracellular microiontophoresis.

    PubMed

    Walker, T; Dillman, N; Weiss, M L

    1995-12-01

    A sophisticated constant-current source suitable for extracellular microiontophoresis of tract-tracing substances, such as Phaseolus vulgaris leucoagglutinin, Biocytin or Fluoro-Gold, is described. This design uses a flyback switched-mode power supply to generate controllable high-voltage and operational amplifier circuitry to regulate current and provide instrumentation. Design features include a fast rise time, +/- 2000 V supply (stable output in < 250 ms), simultaneous load current and voltage monitoring, and separate pumping and holding current settings. Three features of this constant-current source make it especially useful for extracellular microiontophoresis. First, the output voltage monitor permits one to follow changes in the microelectrode resistance during current injection. Second, the voltage-limit (or out-of-compliance) indicator circuitry will sound an alarm when the iontophoretic pump is unable to generate the desired current, such as when the micropipette is blocked. Third, the high-compliance voltage power supply insures up to +/- 20 microA of current through 100 M omega resistance. This device has proven itself to be a reliable constant-current source for extracellular microiontophoresis in the laboratory. PMID:8788057

  16. Constant of heat conduction and stabilization of bus bar conductor

    NASA Astrophysics Data System (ADS)

    López, G.

    Using the one-dimensional, time-independent conduction state, a constant of heat conduction is given bringing about the known stabilization theorem and a closed expression for the bus bar to be cryogenically stable in superconducting accelerators.

  17. 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.

  18. Markov constant and quantum instabilities

    NASA Astrophysics Data System (ADS)

    Pelantová, Edita; Starosta, Štěpán; Znojil, Miloslav

    2016-04-01

    For a qualitative analysis of spectra of certain two-dimensional rectangular-well quantum systems several rigorous methods of number theory are shown productive and useful. These methods (and, in particular, a generalization of the concept of Markov constant known in Diophantine approximation theory) are shown to provide a new mathematical insight in the phenomenologically relevant occurrence of anomalies in the spectra. Our results may inspire methodical innovations ranging from the description of the stability properties of metamaterials and of certain hiddenly unitary quantum evolution models up to the clarification of the mechanisms of occurrence of ghosts in quantum cosmology.

  19. The constant-V vortex

    NASA Astrophysics Data System (ADS)

    Faller, Alan J.

    2001-05-01

    It has been found that the generation of swirl by a continuous rotary oscillation of a right-circular cylinder partially filled with water can leave a vortex with a radially constant tangential velocity, V, i.e. [partial partial differential]V/[partial partial differential]r = 0, excepting a small central core and the sidewall boundary layer. This vortex maintains [partial partial differential]V/[partial partial differential]r = 0 during viscous decay by the turbulent bottom boundary layer, a fact that suggests that [partial partial differential]V/[partial partial differential]r = 0 is a stable condition for a decaying vortex.

  20. Assessing uncertainty in physical constants

    NASA Astrophysics Data System (ADS)

    Henrion, Max; Fischhoff, Baruch

    1986-09-01

    Assessing the uncertainty due to possible systematic errors in a physical measurement unavoidably involves an element of subjective judgment. Examination of historical measurements and recommended values for the fundamental physical constants shows that the reported uncertainties have a consistent bias towards underestimating the actual errors. These findings are comparable to findings of persistent overconfidence in psychological research on the assessment of subjective probability distributions. Awareness of these biases could help in interpreting the precision of measurements, as well as provide a basis for improving the assessment of uncertainty in measurements.

  1. Potentiometric determination of aminal stability constants.

    PubMed

    Taylor, P D

    1995-02-01

    Potentiometric titration was used to determine the logarithms of the stepwise equilibrium constants for the species formed between morpholine and formaldehyde in aqueous solution, ionic strength 0.5 and 2.5M (KCl) at 25 degrees C. The instrumental and computational techniques developed for metal-ligand stability constant determination were applied. Formaldehyde is equivalent to the metal-ion and is represented by M while neutral morpholine is equivalent to the ligand and is represented by L. The stability constants of the following equilibria were determined by non-linear regression (figures in parentheses are at ionic strength 2.5 M KCl): M + L left arrow over right arrow ML (hemi-aminal) logK(1) = 2.90 +/- 0.02 (2.980 +/- 0.004); ML + L left arrow over right arrow ML(2) (bis-aminal); log K(2) = 1.3 +/- 0.2 (1.41 +/- 0.07); MLH left arrow over right arrow ML + H(+) (protonated hemi-aminal) pK(a) = 5.87 +/- 0.01 (6.411 +/- 0.005); ML(2)H left arrow over right arrow ML(2) + H(+) (protonated bis-aminal) pK(a) = (7.6 +/- 0.2). the pK(a) of the protonated bis-aminal could only be determined at the higher ionic strength. The results are in good agreement with reported values determined using the classic formol titration. The automated titration system acquired the full time course of the pH change upon each titrant addition allowing a kinetic analysis to be performed as well as an equilibrium analysis. The forward and reverse rate constants for M + L left arrow over right arrow ML were 0.77M(-1) sec(-1) and 8.1 x 10(-4) sec(-1). respectively. PMID:18966223

  2. Constant mean curvature foliations in cosmological spacetimes.

    NASA Astrophysics Data System (ADS)

    Rendall, A. D.

    1996-11-01

    Foliations by constant mean curvature hypersurfaces provide a possibility of defining a preferred time coordinate in general relativity. In the following various conjectures are made about the existence of foliations of this kind in spacetimes satisfying the strong energy condition and possessing compact Cauchy hypersurfaces. Recent progress on proving these conjectures under supplementary assumptions is reviewed. The method of proof used is explained and the prospects for generalizing it discussed. The relations of these questions to cosmic censorship and the closed universe recollapse conjecture are pointed out.

  3. The Boltzmann constant from a snifter

    NASA Astrophysics Data System (ADS)

    Tyukodi, B.; Sárközi, Zs; Néda, Z.; Tunyagi, A.; Györke, E.

    2012-03-01

    Evaporation of a small glass of ethylic alcohol is studied both experimentally and through an elementary thermal physics approach. For a cylindrical beaker and no air flow in the room, a simple quadratic relation is found between the evaporation time and the mass of evaporated liquid. This problem and the obtained results offer excellent possibilities for simple student experiments and for testing basic principles of thermal physics. As an example, we use the obtained results for estimating the value of the Boltzmann constant from evaporation experiments.

  4. Radiation balances and the solar constant

    NASA Technical Reports Server (NTRS)

    Crommelynck, D.

    1981-01-01

    The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.

  5. Radiation balances and the solar constant

    NASA Astrophysics Data System (ADS)

    Crommelynck, D.

    1981-07-01

    The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.

  6. Scalar field collapse with negative cosmological constant

    NASA Astrophysics Data System (ADS)

    Baier, R.; Nishimura, H.; Stricker, S. A.

    2015-07-01

    The formation of black holes or naked singularities is studied in a model in which a homogeneous time-dependent scalar field with an exponential potential couples to four-dimensional gravity with negative cosmological constant. An analytic solution is derived and its consequences are discussed. The model depends only on one free parameter, which determines the equation of state and decides the fate of the spacetime. Without fine tuning the value of this parameter the collapse ends in a generic formation of a black hole or a naked singularity. The latter case violates the cosmic censorship conjecture.

  7. Stability constant estimator user`s guide

    SciTech Connect

    Hay, B.P.; Castleton, K.J.; Rustad, J.R.

    1996-12-01

    The purpose of the Stability Constant Estimator (SCE) program is to estimate aqueous stability constants for 1:1 complexes of metal ions with ligands by using trends in existing stability constant data. Such estimates are useful to fill gaps in existing thermodynamic databases and to corroborate the accuracy of reported stability constant values.

  8. Assessment of groundwater quality using DEA and AHP: a case study in the Sereflikochisar region in Turkey.

    PubMed

    Kavurmaci, Murat; Üstün, A Korkut

    2016-04-01

    This study investigated the spatial distribution of groundwater quality in Sereflikochisar Basin, in the Central Anatolian region of Turkey using different hydrochemical, statistical, and geostatistical methods. A total of 51 groundwater samples were collected from the observation wells in the study area to evaluate the characteristics of the groundwater quality. As a relatively simple and practical method, a groundwater quality index (GWQI) was developed to evaluate the overall groundwater quality. In this process, complex decision-making techniques such as analytic hierarchy process (AHP) and data envelopment analysis (DEA) were used. Based on these models, two new indices (A-GWQI and D-GWQI) were proposed. According to the D-GWQI score (from 0.6 to 1), water quality was classified in four categories as unsuitable (0.6-0.7), permissible (0.7-0.8), good (0.8-0.9), and excellent (0.9-1). The spatial distribution maps of the groundwater quality were created using the Kriging method. For each map, seven different semivariogram models were tested and the best-fitted model was chosen based on their root mean square standardized error. These maps showed that the areas with high groundwater quality were in the eastern and southern parts of the study area where the D-GWQI scores were greater than 0.8. Depending on the distance from the Salt Lake, the characteristics of groundwater changed from NaCl to NaHCO3 and CaHCO3 facies. This study shows how to determine the spatial distribution of the groundwater quality and identify the impact of salt lakes on the groundwater quality in inland aquifers. The findings of this study can be applied to ensure the quality of groundwater used for drinking and irrigation purposes in the study area. PMID:27034240

  9. Assessment of groundwater quality using DEA and AHP: a case study in the Sereflikochisar region in Turkey.

    PubMed

    Kavurmaci, Murat; Üstün, A Korkut

    2016-04-01

    This study investigated the spatial distribution of groundwater quality in Sereflikochisar Basin, in the Central Anatolian region of Turkey using different hydrochemical, statistical, and geostatistical methods. A total of 51 groundwater samples were collected from the observation wells in the study area to evaluate the characteristics of the groundwater quality. As a relatively simple and practical method, a groundwater quality index (GWQI) was developed to evaluate the overall groundwater quality. In this process, complex decision-making techniques such as analytic hierarchy process (AHP) and data envelopment analysis (DEA) were used. Based on these models, two new indices (A-GWQI and D-GWQI) were proposed. According to the D-GWQI score (from 0.6 to 1), water quality was classified in four categories as unsuitable (0.6–0.7), permissible (0.7–0.8), good (0.8–0.9), and excellent (0.9–1). The spatial distribution maps of the groundwater quality were created using the Kriging method. For each map, seven different semivariogram models were tested and the best-fitted model was chosen based on their root mean square standardized error. These maps showed that the areas with high groundwater quality were in the eastern and southern parts of the study area where the D-GWQI scores were greater than 0.8. Depending on the distance from the Salt Lake, the characteristics of groundwater changed from NaCl to NaHCO3 and CaHCO3 facies. This study shows how to determine the spatial distribution of the groundwater quality and identify the impact of salt lakes on the groundwater quality in inland aquifers. The findings of this study can be applied to ensure the quality of groundwater used for drinking and irrigation purposes in the study area. PMID:27359000

  10. Dynamics of the cosmological and Newton’s constant

    NASA Astrophysics Data System (ADS)

    Smolin, Lee

    2016-01-01

    A modification of general relativity is presented in which Newton’s constant, G, and the cosmological constant, Λ, become a conjugate pair of dynamical variables. These are functions of a global time, hence the theory is presented in the framework of shape dynamics, which trades many-fingered time for a local scale invariance and an overall reparametrization of the global time. As a result, due to the fact that these global dynamical variables are canonically conjugate, the field equations are consistent. The theory predicts a relationship with no free parameters between the rates of change of Newton’s constant and the cosmological constant, in terms of the spatial average of the matter Lagrangian density.

  11. 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.

  12. Constant magnification optical tracking system

    NASA Technical Reports Server (NTRS)

    Frazer, R. E. (Inventor)

    1982-01-01

    A constant magnification optical tracking system for continuously tracking of a moving object is described. In the tracking system, a traveling objective lens maintains a fixed relationship with an object to be optically tracked. The objective lens was chosen to provide a collimated light beam oriented in the direction of travel of the moving object. A reflective surface is attached to the traveling objective lens for reflecting an image of the moving object. The object to be tracked is a free-falling object which is located at the focal point of the objective lens for at least a portion of its free-fall path. A motor and control means is provided for mantaining the traveling objective lens in a fixed relationship relative to the free-falling object, thereby keeping the free-falling object at the focal point and centered on the axis of the traveling objective lens throughout its entire free-fall path.

  13. High Resolution Photon Timing with MCP-PMTs: A Comparison of a Commercial Constant Fraction Discriminator (CFD) with the ASIC-based Waveform Digitizers TARGET and WaveCatcher

    SciTech Connect

    Breton, D.; Delagnes, E.; Maalmi, J.; Nishimura, K.; Ruckman, L.L.; Varner, G.; Va'vra, J.; /SLAC

    2011-07-14

    There is a considerable interest to develop new time-of-flight detectors using, for example, micro-channel-plate photodetectors (MCP-PMTs). The question we pose in this paper is if new waveform digitizer ASICs, such as the WaveCatcher and TARGET, operating with a sampling rate of 2-3 GSa/s can compete with 1GHz BW CFD/TDC/ADC electronics. We have performed a series of measurements with these waveform digitizers coupled to MCP-PMTs operating at low gain and with a signal equivalent to {approx}40 photoelectrons. The tests were done with a laser diode on detectors operating under the same condition used previously in SLAC and Fermilab beam tests. Our test results indicate that one can achieve similar resolution with both methods. Although the commercial CFD-based electronics does exist and performs very well, it is difficult to implement on a very large scale, and therefore the custom electronics is needed. In addition, the analog delay line requirement makes it very difficult to incorporate CFD discriminators in ASIC designs.

  14. Using the Analytic Hierarchy Process (AHP) to understand the most important factors to design and evaluate a telehealth system for Parkinson's disease

    PubMed Central

    2015-01-01

    Background The assessment of a new health technology is a multidisciplinary and multidimensional process, which requires a complex analysis and the convergence of different stakeholders into a common decision. This task is even more delicate when the assessment is carried out in early stage of development processes, when the maturity of the technology prevents conducting a large scale trials to evaluate the cost effectiveness through classic health economics methods. This lack of information may limit the future development and deployment in the clinical practice. This work aims to 1) identify the most relevant user needs of a new medical technology for managing and monitoring Parkinson's Disease (PD) patients and to 2) use these user needs for a preliminary assessment of a specific system called PERFORM, as a case study. Methods Analytic Hierarchy Process (AHP) was used to design a hierarchy of 17 needs, grouped into 5 categories. A total of 16 experts, 6 of them with a clinical background and the remaining 10 with a technical background, were asked to rank these needs and categories. Results On/Off fluctuations detection, Increase wearability acceptance, and Increase self-management support have been identified as the most relevant user needs. No significant differences were found between the clinician and technical groups. These results have been used to evaluate the PERFORM system and to identify future areas of improvement. Conclusions First of all, the AHP contributed to the elaboration of a unified hierarchy, integrating the needs of a variety of stakeholders, promoting the discussion and the agreement into a common framework of evaluation. Moreover, the AHP effectively supported the user need elicitation as well as the assignment of different weights and priorities to each need and, consequently, it helped to define a framework for the assessment of telehealth systems for PD management and monitoring. This framework can be used to support the decision

  15. Assessment of land suitability for olive mill wastewater disposal site selection by integrating fuzzy logic, AHP, and WLC in a GIS.

    PubMed

    Aydi, Abdelwaheb; Abichou, Tarek; Nasr, Imen Hamdi; Louati, Mourad; Zairi, Moncef

    2016-01-01

    This paper presents a geographic information system-based multi-criteria site selection tool of an olive mill wastewater (OMW) disposal site in Sidi Bouzid Region, Tunisia. The multi-criteria decision framework integrates ten constraints and six factors that relate to environmental and economic concerns, and builds a hierarchy model for OMW disposal site suitability. The methodology is used for preliminary assessment of the most suitable OMW disposal sites by combining fuzzy set theory and analytic hierarchy process (AHP). The fuzzy set theory is used to standardize factors using different fuzzy membership functions while the AHP is used to establish the relative importance of the criteria. The AHP makes pairwise comparisons of relative importance between hierarchy elements grouped by both environmental and economic decision criteria. The OMW disposal site suitability is achieved by applying a weighted linear combination that uses a comparison matrix to aggregate different importance scenarios associated with environmental and economic objectives. Three different scenarios generated by different weights applied to the two objectives. The scenario (a) assigns a weight of 0.75 to the environmental and 0.25 to the economic objective, scenario (b) has equal weights, and scenario (c) features weights of 0.25 and 0.75 for environmental and economic objectives, respectively. The results from this study assign the least suitable OMW disposal site of 2.5 % when environmental and economic objectives are rated equally, while a more suitable OMW disposal site of 1.0 % is generated when the economic objective is rated higher. PMID:26711812

  16. Modified large number theory with constant G

    SciTech Connect

    Recami, E.

    1983-03-01

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

  17. Emergence of constant curvature spacetimes with an effective charge and cosmological constant in loop quantum cosmology

    NASA Astrophysics Data System (ADS)

    Joe, Anton; Dadhich, Naresh; Singh, Parampreet

    2015-04-01

    The loop quantum dynamics of Kantowski-Sachs and the interior of higher genus black hole spacetimes with cosmological constant has some peculiar features not shared by various other spacetimes in loop quantum cosmolgy. As in the other cases, though the quantum geometric effects resolve the singularity and result in a bounce, after the bounce a spacetime with small spacetime curvature does not emerge at late times. Instead, asymptotically the spacetime has constant spacetime curvature with a product manifold. Interestingly, though the spacetime curvature of these asymptotic spacetimes is very high, the effective metric of these spacetimes is a solution to the Einstein field equations. Analysis of the components of the Ricci tensor shows that after the singularity resolution, the Kantowski-Sachs spacetimes lead to an effective charged Nariai, and, the higher genus black hole interior lead to an anti Bertotti-Robinson spacetime with an effective tachyonic charge. The asymptotic spacetimes have an effective cosmological constant which is different in magnitude, and sometimes even its sign, from the cosmological constant in the Kantwoski-Sachs and higher genus black hole metrics.

  18. Determination of the lumped constant and the kinetic constants for deoxyglucose and fluorodeoxyglucose in man

    SciTech Connect

    Greenberg, J.H.; Reivich, M.; Alavi, A.; Wolf, A.; Fowler, J.; Russell, J.; Arnett, C.; MacGregor, R.R.; Shiue, C.Y.; Atkins, H.

    1985-01-01

    If both the time course of the arterial plasma radionuclide concentration and the brain tissue radionuclide concentrations are known, it is possible to calculate the kinetic constants (k/sub 1/*, k/sub 2/*, k/sub 3/*, k/sub 4/*) of the glucose analogue. In a series of male subjects, arterial blood samples were obtained at frequent intervals immediately following the bolus administration of /sup 18/F-FDG and then at less frequent intervals for up to 5 hours after the radionuclide administration. The tissue time course was obtained by making positron emission tomographic scans every three minutes for 30 minutes and then at less frequent intervals for 5 hours. These images were used to construct the time course of /sup 18/F activity in gray and white matter structures. Using these values for the lumped constants and the kinetic constants, the values obtained for the global metabolic rate for glucose in two series of young male subjects were 4.99 +- 0.23 and 5.55 +- 0.37 mg/100 g/min when /sup 11/C-DG and /sup 18/F-FDG were used as tracers respectively.

  19. Proteomics of the oxidative stress response induced by hydrogen peroxide and paraquat reveals a novel AhpC-like protein in Pseudomonas aeruginosa.

    PubMed

    Hare, Nathan J; Scott, Nichollas E; Shin, Eun Hye H; Connolly, Angela M; Larsen, Martin R; Palmisano, Giuseppe; Cordwell, Stuart J

    2011-08-01

    Pseudomonas aeruginosa is a ubiquitous pathogen most typically associated with wound infections, but also the main cause of mortality in patients suffering from cystic fibrosis (CF). The ability to adapt to oxidative stress associated with host immune defense may be one mechanism by which P. aeruginosa establishes infection in the cystic fibrosis lung and eventually out-competes other pathogenic bacteria to persist into chronic infection. We utilized a proteomics approach to identify the proteins associated with the oxidative stress response of P. aeruginosa PAO1 to hydrogen peroxide and superoxide-inducing paraquat. 2-DE and MS allowed for the identification of 59 and 58 protein spots that were statistically significantly altered following H(2) O(2) and paraquat treatment, respectively. We observed a unique mass and pI pattern for alkylhydroperoxide reductase C (AhpC) that was replicated by hypothetical protein PA3529 following treatment with 10 mM H(2) O(2) . AhpC belongs to the 2-Cys peroxiredoxin family and is a redox enzyme responsible for removing peroxides in bacterial cells. MS analysis showed that PA3529 was altered by the formation of a dimer via a disulfide bond in a manner analogous to that known for AhpC, and by cysteine overoxidation to Cys-sulfonic acid (SO(3) H) postoxidative stress. PA3529 is therefore a functional AhpC paralog expressed under H(2) O(2) stress. Following paraquat-induced oxidative stress, we also observed the overabundance and likely oxidative modification of a second hypothetical antioxidant protein (PA3450) that shares sequence similarity with 1-Cys peroxiredoxins. Other induced proteins included known oxidative stress proteins (superoxide dismutase and catalase), as well as those involved in iron acquisition (siderophore biosynthesis and receptor proteins FpvA and FptA) and hypothetical proteins, including others predicted to be antioxidants (PA0848). These data suggest that P. aeruginosa contains a plethora of novel

  20. Is There a Cosmological Constant?

    NASA Technical Reports Server (NTRS)

    Kochanek, Christopher; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The grant contributed to the publication of 18 refereed papers and 5 conference proceedings. The primary uses of the funding have been for page charges, travel for invited talks related to the grant research, and the support of a graduate student, Charles Keeton. The refereed papers address four of the primary goals of the proposal: (1) the statistics of radio lenses as a probe of the cosmological model (#1), (2) the role of spiral galaxies as lenses (#3), (3) the effects of dust on statistics of lenses (#7, #8), and (4) the role of groups and clusters as lenses (#2, #6, #10, #13, #15, #16). Four papers (#4, #5, #11, #12) address general issues of lens models, calibrations, and the relationship between lens galaxies and nearby galaxies. One considered cosmological effects in lensing X-ray sources (#9), and two addressed issues related to the overall power spectrum and theories of gravity (#17, #18). Our theoretical studies combined with the explosion in the number of lenses and the quality of the data obtained for them is greatly increasing our ability to characterize and understand the lens population. We can now firmly conclude both from our study of the statistics of radio lenses and our survey of extinctions in individual lenses that the statistics of optically selected quasars were significantly affected by extinction. However, the limits on the cosmological constant remain at lambda < 0.65 at a 2-sigma confidence level, which is in mild conflict with the results of the Type la supernova surveys. We continue to find that neither spiral galaxies nor groups and clusters contribute significantly to the production of gravitational lenses. The lack of group and cluster lenses is strong evidence for the role of baryonic cooling in increasing the efficiency of galaxies as lenses compared to groups and clusters of higher mass but lower central density. Unfortunately for the ultimate objective of the proposal, improved constraints on the cosmological constant, the next

  1. Gravitational Collapse with Cosmological Constant and Anisotropic Pressure

    NASA Astrophysics Data System (ADS)

    Ahmad, Zahid; Malik, Sania Abdul

    2016-01-01

    We investigate the gravitational collapse of anisotropic perfect fluid by applying junction conditions and spherically symmetric space-times in the presence of cosmological constant. We show that the cosmological constant slows down the collapsing process and also reduces the size of black hole.This work provides a generalization of the previous studies by Cissoko et al. (arXiv: gr-qc/9809057) for dust and by Sharif and Ahmad (Mod. Phys. Lett. A, 22:1493, 2007) for perfect fluid.

  2. Parallel (delta + 1) coloring of constant-degree graphs

    SciTech Connect

    Goldberg, A.V.; Plotkin, S.A.

    1986-12-01

    This paper presents parallel algorithms for coloring a constant-degree graph with a maximum degree of delta in (delta + 1) colors and for finding a maximal independent set in a constant-degree graph. Given a graph with n vertices, the algorithms run in O (lg*n) time on EREW PRAM with O(n) processors. The algorithms use only local communication and achieve the same complexity bounds when implemented in the distributed model of parallel computation.

  3. Renormalization of curvature elastic constants for elastic and fluid membranes

    NASA Astrophysics Data System (ADS)

    Ami, S.; Kleinert, H.

    1987-02-01

    We study the fluctuations of membranes with area and curvature elasticity and calculate the renormalization of the curvature elastic constants due to thermal fluctuations. For the mean curvature elastic constant the result is the same as obtained previously for “ideal membranes” which resist only to curvature deformations. The renormalization of the gaussian curvature, on the other hand, depends on the elastic contants. In an incompressible membrane, it is five times weaker than in an ideal membrane.

  4. High voltage compliance constant current ballast

    NASA Technical Reports Server (NTRS)

    Rosenthal, L. A.

    1976-01-01

    A ballast circuit employing a constant current diode and a vacuum tube that can provide a constant current over a voltage range of 1000 volts. The simple circuit can prove useful in studying voltage breakdown characteristics.

  5. ESR melting under constant voltage conditions

    SciTech Connect

    Schlienger, M.E.

    1997-02-01

    Typical industrial ESR melting practice includes operation at a constant current. This constant current operation is achieved through the use of a power supply whose output provides this constant current characteristic. Analysis of this melting mode indicates that the ESR process under conditions of constant current is inherently unstable. Analysis also indicates that ESR melting under the condition of a constant applied voltage yields a process which is inherently stable. This paper reviews the process stability arguments for both constant current and constant voltage operation. Explanations are given as to why there is a difference between the two modes of operation. Finally, constant voltage process considerations such as melt rate control, response to electrode anomalies and impact on solidification will be discussed.

  6. Capacitive Cells for Dielectric Constant Measurement

    ERIC Educational Resources Information Center

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

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

  7. Search for a Variation of Fundamental Constants

    NASA Astrophysics Data System (ADS)

    Ubachs, W.

    2013-06-01

    Since the days of Dirac scientists have speculated about the possibility that the laws of nature, and the fundamental constants appearing in those laws, are not rock-solid and eternal but may be subject to change in time or space. Such a scenario of evolving constants might provide an answer to the deepest puzzle of contemporary science, namely why the conditions in our local Universe allow for extreme complexity: the fine-tuning problem. In the past decade it has been established that spectral lines of atoms and molecules, which can currently be measured at ever-higher accuracies, form an ideal test ground for probing drifting constants. This has brought this subject from the realm of metaphysics to that of experimental science. In particular the spectra of molecules are sensitive for probing a variation of the proton-electron mass ratio μ, either on a cosmological time scale, or on a laboratory time scale. A comparison can be made between spectra of molecular hydrogen observed in the laboratory and at a high redshift (z=2-3), using the Very Large Telescope (Paranal, Chile) and the Keck telescope (Hawaii). This puts a constraint on a varying mass ratio Δμ/μ at the 10^{-5} level. The optical work can also be extended to include CO molecules. Further a novel direction will be discussed: it was discovered that molecules exhibiting hindered internal rotation have spectral lines in the radio-spectrum that are extremely sensitive to a varying proton-electron mass ratio. Such lines in the spectrum of methanol were recently observed with the radio-telescope in Effelsberg (Germany). F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs, Phys. Rev. Lett. 106, 180802 (2011). A. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs, Mon. Not. Roy. Astron. Soc. 403, 1541 (2010). E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs, Phys. Rev. A 86, 022510

  8. Characterization of supercapacitor models for analyzing supercapacitors connected to constant power elements

    NASA Astrophysics Data System (ADS)

    Yang, Hengzhao; Zhang, Ying

    2016-04-01

    Understanding the power and energy performance of supercapacitors connected to constant power elements is important for many applications. This paper proposes a characterization method for two supercapacitor models that are used to analyze the power and energy behavior of supercapacitors connected to constant power elements: linear capacitance model and constant capacitance model. The linear or constant capacitance is determined by conducting a constant power experiment. A set of constant power experiments is designed. The proposed method can reduce the error in estimating the constant power experiment time for a variety of supercapacitor samples with different rated capacitance and voltage. The accuracy of using the linear capacitance model and the constant capacitance model is approximately equal. Moreover, the performance evaluation results suggest that using the linear or constant capacitance fitted through a low power discharge experiment can minimize the error, which can serve as a guideline to design the constant power experiment.

  9. Particle creation with time dependent gravitational and cosmological constants

    NASA Astrophysics Data System (ADS)

    Ibotombi Singh, N.; Bembem Devi, Y.; Surendra Singh, S.

    2013-05-01

    The effect of particle creation on the evolution of FRW cosmological model has been studied. The universe has been considered as an open thermodynamic system when particle creation leads to supplementary negative creation pressure in addition to the thermodynamic pressure. Dynamical behaviors of the cosmological solutions have been studied.

  10. Constant time worker thread allocation via configuration caching

    DOEpatents

    Eichenberger, Alexandre E; O'Brien, John K. P.

    2014-11-04

    Mechanisms are provided for allocating threads for execution of a parallel region of code. A request for allocation of worker threads to execute the parallel region of code is received from a master thread. Cached thread allocation information identifying prior thread allocations that have been performed for the master thread are accessed. Worker threads are allocated to the master thread based on the cached thread allocation information. The parallel region of code is executed using the allocated worker threads.

  11. A fuzzy model for achieving lean attributes for competitive advantages development using AHP-QFD-PROMETHEE

    NASA Astrophysics Data System (ADS)

    Roghanian, E.; Alipour, Mohammad

    2014-06-01

    Lean production has become an integral part of the manufacturing landscape as its link with superior performance and its ability to provide competitive advantage is well accepted among academics and practitioners. Lean production helps producers in overcoming the challenges organizations face through using powerful tools and enablers. However, most companies are faced with restricted resources such as financial and human resources, time, etc., in using these enablers, and are not capable of implementing all these techniques. Therefore, identifying and selecting the most appropriate and efficient tool can be a significant challenge for many companies. Hence, this literature seeks to combine competitive advantages, lean attributes, and lean enablers to determine the most appropriate enablers for improvement of lean attributes. Quality function deployment in fuzzy environment and house of quality matrix are implemented. Throughout the methodology, fuzzy logic is the basis for translating linguistic judgments required for the relationships and correlation matrix to numerical values. Moreover, for final ranking of lean enablers, a multi-criteria decision-making method (PROMETHEE) is adopted. Finally, a case study in automotive industry is presented to illustrate the implementation of the proposed methodology.

  12. Monitoring desertification using the integrated CA GIS and RS with AHP-derived weights: a case study of Beijing and its neighboring areas in recent 20 years

    NASA Astrophysics Data System (ADS)

    Wang, Gongwen; Chen, Jianping; Li, Qing; Ding, Huoping

    2007-06-01

    This paper aims to monitor desertification evolution of different stages and assess its factors using remote sensing (RS) data and cellular automata (CA)-geographical information system (GIS) with an adaptive analytic hierarchy process (AHP) to derive weights of desertification factors. The study areas (114°E to 117°E and 39.5°to 42.2°N) are one of the important agro-pastoral transitional zone, located in Beijing and its neighboring areas, marginal desertified areas in North China. Desertification information including NDVI and desertification area were derived from the satellite images of 1987TM, 1996TM (with a resolution of 28.5), and 2006 CBERS-(with a resolution of 19.5 m) in study areas. The ancillary data in terms of meteorology, geology, 30m-DEM, hydrography can be statistical analyzed with GIS technology. A CA model based on the desertification factors with AHP-derived weights was built by AML program in ArcGIS workstation to assess the evolution of desertification in different stages (from 1987 to 1996, and from 1996 to 2006). The research results show that desertified areas was increased by 3.28% per year from 1987 to 1996, so was 0.51% per year from 1996 to 2006. Although the weights of desertification factors have some changes in different stages, the main factors including climate, NDVI, and terrain did not change except the values in study areas.

  13. Combining AHP with GIS for landfill site selection: a case study in the Lake Beyşehir catchment area (Konya, Turkey).

    PubMed

    Sener, Sehnaz; Sener, Erhan; Nas, Bilgehan; Karagüzel, Remzi

    2010-11-01

    Landfills are the most common method for the disposal of municipal solid waste (MSW) in Turkey. However, determining the location of landfill sites is a difficult and complex process because it must combine social, environmental and technical parameters. Additionally, it depends on several criteria and regulations. The main objective of this study was to select of a landfill site for the Lake Beyşehir catchment area. The Beyşehir Lake is the largest freshwater lake and drinking water reservoir in Turkey, but there is no controlled landfill site in the region. Therefore, the landfill site should be determined such that the lake is protected. To determine the most suitable landfill site, an analytical hierarchy process (AHP) was combined with a geographic information system (GIS) to examine several criteria, such as geology/hydrogeology, land use, slope, height, aspect and distance from settlements, surface waters, roads, and protected areas (ecologic, scientific or historic). Each criterion was evaluated with the aid of AHP and mapped by GIS. Data were assorted into four suitability classes within the study area, i.e., high, moderate, low and very low suitability areas, which represented 3.24%, 7.55%, 12.70% and 2.81%, of the study area, respectively. Additionally, 73.70% was determined to be completely unsuitable for a landfill site. As a result, two candidate landfill sites are suggested and discussed. The final decision for landfill site selection will require more detailed field studies. PMID:20594819

  14. Hawking temperature of constant curvature black holes

    SciTech Connect

    Cai Ronggen; Myung, Yun Soo

    2011-05-15

    The constant curvature (CC) black holes are higher dimensional generalizations of Banados-Teitelboim-Zanelli black holes. It is known that these black holes have the unusual topology of M{sub D-1}xS{sup 1}, where D is the spacetime dimension and M{sub D-1} stands for a conformal Minkowski spacetime in D-1 dimensions. The unusual topology and time-dependence for the exterior of these black holes cause some difficulties to derive their thermodynamic quantities. In this work, by using a globally embedding approach, we obtain the Hawking temperature of the CC black holes. We find that the Hawking temperature takes the same form when using both the static and global coordinates. Also, it is identical to the Gibbons-Hawking temperature of the boundary de Sitter spaces of these CC black holes.

  15. Fast Fourier Transforms of Piecewise Constant Functions

    NASA Astrophysics Data System (ADS)

    Sorets, Eugene

    1995-02-01

    We present an algorithm for the evaluation of the Fourier transform of piecewise constant functions of two variables. The algorithm overcomes the accuracy problems associated with computing the Fourier transform of discontinuous functions; in fact, its time complexity is O (N2 logN + NP log2 (1/ε) + V log3 (1/ε)), where ε is the accuracy, N is the size of the problem, P is the perimeter of the set of discontinuities, and V is its number of vertices. The algorithm is based on the Lagrange interpolation formula and the Green's theorem, which are used to preprocess the data before applying the fast Fourier transform. It readily generalizes to higher dimensions and to piecewise smooth functions.

  16. Fundamental Constants and Tests with Simple Atoms

    NASA Astrophysics Data System (ADS)

    Tan, Joseph

    2015-05-01

    Precise measurements with simple atoms provide stringent tests of physical laws, improving the accuracy of fundamental constants--a set of which will be selected to fully define the proposed New International System of Units. This talk focuses on the atomic constants (namely, the Rydberg constant, the fine-structure constant, and the proton charge radius), discussing the impact of the proton radius obtained from the Lamb-shift measurements in muonic hydrogen. Significant discrepancies persist despite years of careful examination: the slightly smaller proton radius obtained from muonic hydrogen requires the Rydberg constant and the fine-structure constant to have values that disagree significantly with the CODATA recommendations. After giving a general overview, I will discuss our effort to produce one-electron ions in Rydberg states, to enable a different test of theory and measurement of the Rydberg constant.

  17. PECVD of low-dielectric constant films for ULSI

    NASA Astrophysics Data System (ADS)

    Shimogaki, Yukihiro

    1998-10-01

    We studied the reduction mechanism of the dielectric constant of F-doped silicon oxide films prepared by PECVD from SiH_4/N_2O/CF4 mixture. From the estimation of the dielectric constant at various frequencies, ranging from 1MHz to 100THz, using CV measurement, Kramers-Kronig relation and the square of the refractive index, we suggest that the dielectric constant due to ionic and electronic polarization is not the dominant factor in decreasing the dielectric constant. It is important to remove -OH in films to obtain very low dielectric constant F-doped silicon oxide films, because Si-OH is the main factor of the orientational polarization in silicon oxide films made by PECVD. To investigate the reaction mechanism which controls the film structure, we changed the residence time of gas in chamber by varying the flow rate. When the residence time in chamber decreases, the film deposition rate increases. We tried to explain flow rate dependency of the deposition rate using a simple CSTR (continuous stirred tank reactor) model. It can be concluded that there are two paths to deposit the films. One route is a deposition by the precursors with poor step coverage profile, and the other route is deposition through intermediates formed by gas phase reactions that contribute to have better step coverage. The overall gas phase reaction rate constant was estimated from these kinetic studies. Same approach was also carried out on the PECVD of C:F film deposition.

  18. PREFACE: Fundamental Constants in Physics and Metrology

    NASA Astrophysics Data System (ADS)

    Klose, Volkmar; Kramer, Bernhard

    1986-01-01

    /or a physical unit have their origin in the shortcomings of our understanding of the underlying physics rather than being due to the technical problems in the experiment. In this context, it is worth mentioning that the quantum Hall effect, the discovery of which by Klaus von Klitzing was rewarded only recently by the Nobel Prize for physics, still needs further attention. We are able to reproduce experimentally resistances with an extremely high precision using this effect. Nevertheless, we have severe difficulties in our present physical understanding of the mechanism which provides the plateaux in the Hall resistance. Lectures on "Quantum Non-Demolition" and "Determination of the Boltzmann Constant" have been included in order to show routes to "new frontiers" in metrology. Even the "conventional" metrological concepts, when combined with modern technology, can provide surprises: Although the Josephson effect is known since 1962, it was only recently that a quantized voltage in the 1-volt range could be experimentally realized. The experiment was performed by making use of modern thin-film technology. In addition to providing a simple and precise voltage standard in a practically important regime it also sets a new frontier in precision electrical metrology by demonstrating that, ultimately, the reproducibility of the unit of voltage is limited by that of the unit of time. We are indebted to a number of people who helped to organize the Seminar as well as to prepare this volume. Especially, we would like to mention Mrs Inge Bode. Without her continuous work the 70th PTB Seminar would not have been possible in the way we all have experienced it. We appreciate also the help of R P Hudson and H Lotsch in achieving a fast publication of this volume. Financial support from the Helmholtz-Fond is gratefully acknowledged.

  19. Star polymers rupture induced by constant forces

    NASA Astrophysics Data System (ADS)

    García, N. A.; Febbo, M.; Vega, D. A.; Milchev, A.

    2014-10-01

    In this work, we study the breakage process of an unknotted three-arm star-shaped polymer when it is pulled from its free ends by a constant force. The star polymer configuration is described through an array of monomers coupled by anharmonic bonds, while the rupture process is tracked in three-dimensional space by means of Langevin Molecular Dynamics simulations. The interaction between monomers is described by a Morse potential, while a Weeks-Chandler-Anderson energetic contribution accounts for the excluded volume interaction. We explore the effect of the molecular architecture on the distributions of rupture times over a broad interval of pulling forces and star configurations. It was found that the rupture time distribution of the individual star arms is strongly affected by the star configuration imposed by the pulling forces and the length of the arms. We also observed that for large pulling forces the rupture time distributions resemble the dominant features observed for linear polymer chains. The model introduced here provides the basic ingredients to describe the effects of tensile forces on stress-induced degradation of branched macromolecules and polymer networks.

  20. The Not so Constant Gravitational "Constant" G as a Function of Quantum Vacuum

    NASA Astrophysics Data System (ADS)

    Maxmilian Caligiuri, Luigi

    Gravitation is still the less understood among the fundamental forces of Nature. The ultimate physical origin of its ruling constant G could give key insights in this understanding. According to the Einstein's Theory of General Relativity, a massive body determines a gravitational potential that alters the speed of light, the clock's rate and the particle size as a function of the distance from its own center. On the other hand, it has been shown that the presence of mass determines a modification of Zero-Point Field (ZPF) energy density within its volume and in the space surrounding it. All these considerations strongly suggest that also the constant G could be expressed as a function of quantum vacuum energy density somehow depending on the distance from the mass whose presence modifies the ZPF energy structure. In this paper, starting from a constitutive medium-based picture of space, it has been formulated a model of gravitational constant G as a function of Planck's time and Quantum Vacuum energy density in turn depending on the radial distance from center of the mass originating the gravitational field, supposed as spherically symmetric. According to this model, in which gravity arises from the unbalanced physical vacuum pressure, gravitational "constant" G is not truly unchanging but slightly varying as a function of the distance from the mass source of gravitational potential itself. An approximate analytical form of such dependence has been discussed. The proposed model, apart from potentially having deep theoretical consequences on the commonly accepted picture of physical reality (from cosmology to matter stability), could also give the theoretical basis for unthinkable applications related, for example, to the field of gravity control and space propulsion.

  1. Planck intermediate results. XXIV. Constraints on variations in fundamental constants

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Butler, R. C.; Calabrese, E.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Couchot, F.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Diego, J. M.; Dole, H.; Doré, O.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Fabre, O.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Menegoni, E.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Ristorcelli, I.; Rocha, G.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Uzan, J.-P.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Yvon, D.; Zacchei, A.; Zonca, A.

    2015-08-01

    Any variation in the fundamental physical constants, more particularly in the fine structure constant, α, or in the mass of the electron, me, affects the recombination history of the Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data allow one to improve the constraint on the time variation of the fine structure constant at redshift z ~ 103 by about a factor of 5 compared to WMAP data, as well as to break the degeneracy with the Hubble constant, H0. In addition to α, we can set a constraint on the variation in the mass of the electron, me, and in the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other cosmological probes. We conclude that independent time variations of the fine structure constant and of the mass of the electron are constrained by Planck to Δα/α = (3.6 ± 3.7) × 10-3 and Δme/me = (4 ± 11) × 10-3 at the 68% confidence level. We also investigate the possibility of a spatial variation of the fine structure constant. The relative amplitude of a dipolar spatial variation in α (corresponding to a gradient across our Hubble volume) is constrained to be δα/α = (-2.4 ± 3.7) × 10-2. Appendices are available in electronic form at http://www.aanda.org

  2. Graviton mass or cosmological constant?

    SciTech Connect

    Gabadadze, Gregory; Gruzinov, Andrei

    2005-12-15

    To describe a massive graviton in 4D Minkowski space-time one introduces a quadratic term in the Lagrangian. This term, however, can lead to a readjustment or instability of the background instead of describing a massive graviton on flat space. We show that for all local 4D Lorentz-invariant mass terms Minkowski space is unstable. The instability can develop in a time scale that is many orders of magnitude shorter than the inverse graviton mass. We start with the Pauli-Fierz (PF) term that is the only local mass term with no ghosts in the linearized approximation. We show that nonlinear completions of the PF Lagrangian give rise to instability of Minkowski space. We continue with the mass terms that are not of a PF type. Although these models are known to have ghosts in the linearized approximations, nonlinear interactions can lead to background change in which the ghosts are eliminated. In the latter case, however, the graviton perturbations on the new background are not massive. We argue that a consistent theory of a massive graviton on flat space can be formulated in theories with extra dimensions. They require an infinite number of fields or nonlocal description from a 4D point of view.

  3. Low power, constant-flow air pump systems

    SciTech Connect

    Polito, M.D.; Albert, B.

    1994-01-01

    A rugged, yet small and lightweight constant-flow air pump system has been designed. Flow control is achieved using a novel approach which is three times more power efficient than previous designs. The resultant savings in battery size and weight makes these pumps ideal for sampling air on balloon platforms. The pump package includes meteorological sensors and an onboard computer that stores time and sensor data and turns the constant-flow pump circuit on/off. Some applications of these systems are also presented in this report.

  4. The sixteen channel CAMAC constant fraction discriminator for APEX

    SciTech Connect

    Maier, M.R. ); Robertson, M. ); Wolfs, F.L.H.; Perera, P.A.A. . Nuclear Structure Research Lab.)

    1991-11-01

    We report on the construction and the performance of a sixteen channel constant fraction discriminator (CFD) for the Atlas Positron Experiment (APEX). We have used an integrated circuit (IC), recently introduced commercially, which contains all the electronic building blocks needed to construct a CFD. We have placed 16 channels of CFD into a CAMAC module. An important feature is the time to charge converter (TQC) that we have included for every CFD channel. Its calibration constant is controlled via CAMAC. The TQC allows the use charge sensitive analog to digital converters (QDC) for timing measurements. Results for CFD walk, resolution and crosstalk as well as for TQC linearity will be presented.

  5. Determination of the Hubble constant.

    PubMed

    Freedman, W L; Feng, L L

    1999-09-28

    Establishing accurate extragalactic distances has provided an immense challenge to astronomers since the 1920s. The situation has improved dramatically as better detectors have become available, and as several new, promising techniques have been developed. For the first time in the history of this difficult field, relative distances to galaxies are being compared on a case-by-case basis, and their quantitative agreement is being established. New instrumentation, the development of new techniques for measuring distances, and recent measurements with the Hubble Space telescope all have resulted in new distances to galaxies with precision at the +/-5-20% level. The current statistical uncertainty in some methods for measuring H(0) is now only a few percent; with systematic errors, the total uncertainty is approaching +/-10%. Hence, the historical factor-of-two uncertainty in the value of the H(0) is now behind us. PMID:10500124

  6. Determination of the Hubble constant

    PubMed Central

    Freedman, Wendy L.; Feng, Long Long

    1999-01-01

    Establishing accurate extragalactic distances has provided an immense challenge to astronomers since the 1920s. The situation has improved dramatically as better detectors have become available, and as several new, promising techniques have been developed. For the first time in the history of this difficult field, relative distances to galaxies are being compared on a case-by-case basis, and their quantitative agreement is being established. New instrumentation, the development of new techniques for measuring distances, and recent measurements with the Hubble Space telescope all have resulted in new distances to galaxies with precision at the ±5–20% level. The current statistical uncertainty in some methods for measuring H0 is now only a few percent; with systematic errors, the total uncertainty is approaching ±10%. Hence, the historical factor-of-two uncertainty in the value of the H0 is now behind us. PMID:10500124

  7. Emergent cosmological constant from colliding electromagnetic waves

    SciTech Connect

    Halilsoy, M.; Mazharimousavi, S. Habib; Gurtug, O. E-mail: habib.mazhari@emu.edu.tr

    2014-11-01

    In this study we advocate the view that the cosmological constant is of electromagnetic (em) origin, which can be generated from the collision of em shock waves coupled with gravitational shock waves. The wave profiles that participate in the collision have different amplitudes. It is shown that, circular polarization with equal amplitude waves does not generate cosmological constant. We also prove that the generation of the cosmological constant is related to the linear polarization. The addition of cross polarization generates no cosmological constant. Depending on the value of the wave amplitudes, the generated cosmological constant can be positive or negative. We show additionally that, the collision of nonlinear em waves in a particular class of Born-Infeld theory also yields a cosmological constant.

  8. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, Max E.

    1996-01-01

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

  9. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, M.E.

    1996-10-22

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

  10. Cosmological Constant and Axions in String Theory

    SciTech Connect

    Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC

    2006-08-18

    String theory axions appear to be promising candidates for explaining cosmological constant via quintessence. In this paper, we study conditions on the string compactifications under which axion quintessence can happen. For sufficiently large number of axions, cosmological constant can be accounted for as the potential energy of axions that have not yet relaxed to their minima. In compactifications that incorporate unified models of particle physics, the height of the axion potential can naturally fall close to the observed value of cosmological constant.

  11. Dielectric constant microscopy for biological materials

    NASA Astrophysics Data System (ADS)

    Valavade, A. V.; Kothari, D. C.; Löbbe, C.

    2013-02-01

    This paper describes the work on the development of Dielectric Constant Microscopy for biological materials using double pass amplitude modulation method. The dielectric constant information can be obtained at nanometer scales using this technique. Electrostatic force microscopy images of biological materials are presented. The images obtained from the EFM technique mode clearly show inversion contrast and gives the spatial variation of tip-sample capacitance. The EFM images are further processed to obtain dielectric constant information at nanometer scales.

  12. An Alcohol Test for Drifting Constants

    NASA Astrophysics Data System (ADS)

    Jansen, P.; Bagdonaite, J.; Ubachs, W.; Bethlem, H. L.; Kleiner, I.; Xu, L.-H.

    2013-06-01

    The Standard Model of physics is built on the fundamental constants of nature, however without providing an explanation for their values, nor requiring their constancy over space and time. Molecular spectroscopy can address this issue. Recently, we found that microwave transitions in methanol are extremely sensitive to a variation of the proton-to-electron mass ratio μ, due to a fortuitous interplay between classically forbidden internal rotation and rotation of the molecule as a whole. In this talk, we will explain the origin of this effect and how the sensitivity coefficients in methanol are calculated. In addition, we set a limit on a possible cosmological variation of μ by comparing transitions in methanol observed in the early Universe with those measured in the laboratory. Based on radio-astronomical observations of PKS1830-211, we deduce a constraint of Δμ/μ=(0.0± 1.0)× 10^{-7} at redshift z = 0.89, corresponding to a look-back time of 7 billion years. While this limit is more constraining and systematically more robust than previous ones, the methanol method opens a new search territory for probing μ-variation on cosmological timescales. P. Jansen, L.-H. Xu, I. Kleiner, W. Ubachs, and H.L. Bethlem Phys. Rev. Lett. {106}(100801) 2011. J. Bagdonaite, P. Jansen, C. Henkel, H.L. Bethlem, K.M. Menten, and W. Ubachs Science {339}(46) 2013.

  13. Cosmological Constant and the Final Anthropic Hypothesis

    NASA Astrophysics Data System (ADS)

    Ćirković, Milan M.; Bostrom, Nick

    The influence of recent detections of a finite vacuum energy (`cosmological constant') on our formulation of anthropic conjectures, particularly the so-called Final Anthropic Principle is investigated. It is shown that non-zero vacuum energy implies the onset of a quasi-exponential expansion of our causally connected domain (`the universe') at some point in the future, a stage similar to the inflationary expansion at the very beginning of time. The transition to this future inflationary phase of cosmological expansion will preclude indefinite survival of intelligent species in our domain, because of the rapid shrinking of particle horizons and subsequent depletion of energy necessary for information processes within the horizon of any observer. Therefore, to satisfy the Final Anthropic Hypothesis (reformulated to apply to the entire ensemble of universes), it is necessary to show that (i) chaotic inflation of Linde (or some similar model) provides a satisfactory description of reality, (ii) migration between causally connected domains within the multiverse is physically permitted, and (iii) the time interval left to the onset of the future inflationary phase is sufficient for development of the technology necessary for such inter-domain travel. These stringent requirements diminish the probability of the Final Anthropic Hypothesis being true.

  14. Modification of the characteristic gravitational constants

    NASA Astrophysics Data System (ADS)

    Vujičić, V. A.

    2006-08-01

    In the educational and scientific literature the numerical values of gravitational constants are seen as only approximately correct. The numerical values are different in work by various researchers, as also are the formulae and definitions of constants employed. In this paper, on the basis of Newton’s laws and Kepler’s laws we prove that it is necessary to modify the characteristic gravitational constants and their definitions. The formula for the geocentric gravitational constant of the satellites Kosmos N and the Moon are calculated.

  15. A natural cosmological constant from chameleons

    NASA Astrophysics Data System (ADS)

    Nastase, Horatiu; Weltman, Amanda

    2015-07-01

    We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru-Kallosh-Linde-Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now).

  16. Dynamical dark energy and variation of fundamental "constants"

    NASA Astrophysics Data System (ADS)

    Stern, Steffen

    2008-12-01

    In this thesis we study the influence of a possible variation of fundamental "constants" on the process of Big Bang Nucleosynthesis (BBN). Our findings are combined with further studies on variations of constants in other physical processes to constrain models of grand unification (GUT) and quintessence. We will find that the 7Li problem of BBN can be ameliorated if one allows for varying constants, where especially varying light quark masses show a strong influence. Furthermore, we show that recent studies of varying constants are in contradiction with each other and BBN in the framework of six exemplary GUT scenarios, if one assumes monotonic variation with time. We conclude that there is strong tension between recent claims of varying constants, hence either some claims have to be revised, or there are much more sophisticated GUT relations (and/or non-monotonic variations) realized in nature. The methods introduced in this thesis prove to be powerful tools to probe regimes well beyond the Standard Model of particle physics or the concordance model of cosmology, which are currently inaccessible by experiments. Once the first irrefutable proofs of varying constants are available, our method will allow for probing the consistency of models beyond the standard theories like GUT or quintessence and also the compatibility between these models.

  17. Spectral Sensitivity Measured with Electroretinogram Using a Constant Response Method

    PubMed Central

    Rocha, Fernando Allan de Farias; Gomes, Bruno Duarte; Silveira, Luiz Carlos de Lima; Martins, Sonia Limara; Aguiar, Renata Genaro; de Souza, John Manuel; Ventura, Dora Fix

    2016-01-01

    A new method is presented to determine the retinal spectral sensitivity function S(λ) using the electroretinogram (ERG). S(λ)s were assessed in three different species of myomorph rodents, Gerbils (Meriones unguiculatus), Wistar rats (Ratus norvegicus), and mice (Mus musculus). The method, called AC Constant Method, is based on a computerized automatic feedback system that adjusts light intensity to maintain a constant-response amplitude to a flickering stimulus throughout the spectrum, as it is scanned from 300 to 700 nm, and back. The results are presented as the reciprocal of the intensity at each wavelength required to maintain a constant peak to peak response amplitude. The resulting S(λ) had two peaks in all three rodent species, corresponding to ultraviolet and M cones, respectively: 359 nm and 511 nm for mice, 362 nm and 493 nm for gerbils, and 362 nm and 502 nm for rats. Results for mouse and gerbil were similar to literature reports of S(λ) functions obtained with other methods, confirming that the ERG associated to the AC Constant-Response Method was effective to obtain reliable S(λ) functions. In addition, due to its fast data collection time, the AC Constant Response Method has the advantage of keeping the eye in a constant light adapted state. PMID:26800521

  18. Spectral Sensitivity Measured with Electroretinogram Using a Constant Response Method.

    PubMed

    Rocha, Fernando Allan de Farias; Gomes, Bruno Duarte; Silveira, Luiz Carlos de Lima; Martins, Sonia Limara; Aguiar, Renata Genaro; de Souza, John Manuel; Ventura, Dora Fix

    2016-01-01

    A new method is presented to determine the retinal spectral sensitivity function S(λ) using the electroretinogram (ERG). S(λ)s were assessed in three different species of myomorph rodents, Gerbils (Meriones unguiculatus), Wistar rats (Ratus norvegicus), and mice (Mus musculus). The method, called AC Constant Method, is based on a computerized automatic feedback system that adjusts light intensity to maintain a constant-response amplitude to a flickering stimulus throughout the spectrum, as it is scanned from 300 to 700 nm, and back. The results are presented as the reciprocal of the intensity at each wavelength required to maintain a constant peak to peak response amplitude. The resulting S(λ) had two peaks in all three rodent species, corresponding to ultraviolet and M cones, respectively: 359 nm and 511 nm for mice, 362 nm and 493 nm for gerbils, and 362 nm and 502 nm for rats. Results for mouse and gerbil were similar to literature reports of S(λ) functions obtained with other methods, confirming that the ERG associated to the AC Constant-Response Method was effective to obtain reliable S(λ) functions. In addition, due to its fast data collection time, the AC Constant Response Method has the advantage of keeping the eye in a constant light adapted state. PMID:26800521

  19. Sinkhole susceptibility mapping using the analytical hierarchy process (AHP) and magnitude-frequency relationships: A case study in Hamadan province, Iran

    NASA Astrophysics Data System (ADS)

    Taheri, Kamal; Gutiérrez, Francisco; Mohseni, Hassan; Raeisi, Ezzat; Taheri, Milad

    2015-04-01

    Since 1989, an increasing number of sinkhole occurrences have been reported in the Kabudar Ahang and Razan-Qahavand subcatchments (KRQ) of Hamadan province, western Iran. The sinkhole-related subsidence phenomenon poses a significant threat for people and human structures, including sensitive facilities like the Hamadan Power Plant. Groundwater over-exploitation from the thick alluvial cover and the underlying cavernous limestone has been identified as the main factor involved in sinkhole development. A sinkhole susceptibility model was produced in a GIS environment applying the analytical hierarchy process (AHP) approach and considering a selection of eight factors, each categorized into five classes: distance to faults (DF), water level decline (WLD), groundwater exploitation (GE), penetration of deep wells into karst bedrock (PKA), distance to deep wells (DDW), groundwater alkalinity (GA), bedrock lithology (BL), and alluvium thickness (AT). Relative weights were preliminarily assigned to each factor and to their different classes through systematic pairwise comparisons based on expert judgment. The resulting sinkhole susceptibility index (SSI) values were then classified into four susceptibility classes: low, moderate, high and very high susceptibility. Subsequently, the model was refined through a trial and error process involving changes in the relative weights and iterative evaluation of the prediction capability. Independent evaluation of the final model indicates that 55% and 45% of the subsidence events fall within the very high and high, susceptibility zones, respectively. The results of this study show that AHP can be a useful approach for susceptibility assessment if data on the main controlling factors have sufficient accuracy and spatial coverage. The limitations of the model are partly related to the difficulty of gathering data on some important geological factors, due to their hidden nature. The magnitude and frequency relationship constructed

  20. Vacuum energy and the cosmological constant

    NASA Astrophysics Data System (ADS)

    Bass, Steven D.

    2015-06-01

    The accelerating expansion of the Universe points to a small positive value for the cosmological constant or vacuum energy density. We discuss recent ideas that the cosmological constant plus Large Hadron Collider (LHC) results might hint at critical phenomena near the Planck scale.

  1. Performance of a constant torque pedal device.

    PubMed Central

    Sherwin, K.

    1979-01-01

    A constant-torque oscillatory pedal-crank device using vertical movement of the feet is described and its performance compared to a conventional rotational cycle. Using a generator to measure the power output the constant-torque device produced 33% less power and thus has no practical value as an alternative to the conventional pedal-crank system. Images Figure 3 PMID:526783

  2. The method of constant stimuli is inefficient

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Fitzhugh, Andrew

    1990-01-01

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

  3. Air kerma rate constants for radionuclides.

    PubMed

    Wasserman, H; Groenewald, W

    1988-01-01

    Conversion to SI units requires that the exposure rate constant which was usually quoted in R.h-1.mCi-1.cm2 be replaced by the air kerma rate constant with units m2.Gy.Bq-1.s-1. The conversion factor is derived and air kerma rate constants for 30 radionuclides used in nuclear medicine and brachytherapy are listed. A table for calculation of air kerma rates for other radionuclides is also given. To calculate absorbed dose to tissue, the air kerma rate has to be multiplied by approximately 1.1. A dose equivalent rate constant is thus listed which allows direct calculation of dose equivalent rate to soft tissue without resorting to exposure rate constants tabulated in the special units R.m2.mCi-1.h-1 which should no longer be used. PMID:3208786

  4. Elastic constants of layers in isotropic laminates.

    PubMed

    Heyliger, Paul R; Ledbetter, Hassel; Kim, Sudook; Reimanis, Ivar

    2003-11-01

    The individual laminae elastic constants in multilayer laminates composed of dissimilar isotropic layers were determined using ultrasonic-resonance spectroscopy and the linear theory of elasticity. Ultrasonic resonance allows one to measure the free-vibration response spectrum of a traction-free solid under periodic vibration. These frequencies depend on pointwise density, laminate dimensions, layer thickness, and layer elastic constants. Given a material with known mass but unknown constitution, this method allows one to extract the elastic constants and density of the constituent layers. This is accomplished by measuring the frequencies and then minimizing the differences between these and those calculated using the theory of elasticity for layered media to select the constants that best replicate the frequency-response spectrum. This approach is applied to a three-layer, unsymmetric laminate of WpCu, and very good agreement is found with the elastic constants of the two constituent materials. PMID:14649998

  5. Using an air thermometer to estimate the gas constant

    NASA Astrophysics Data System (ADS)

    Kinchin, John

    2015-03-01

    The air thermometer, widely used in physics laboratories to show the relationship between volume and temperature, can also be used to obtain values for the gas constant and hence Avogadro’s number. Using a very low cost, home-made air thermometer can give surprisingly good results in a very short period of time.

  6. Universal constants and equations of turbulent motion

    NASA Astrophysics Data System (ADS)

    Baumert, Helmut

    2011-11-01

    For turbulence at high Reynolds number we present an analogy with the kinetic theory of gases, with dipoles made of vortex tubes as frictionless, incompressible but deformable quasi-particles. Their movements are governed by Helmholtz' elementary vortex rules applied locally. A contact interaction or ``collision'' leads either to random scatter of a trajectory or to the formation of two likewise rotating, fundamentally unstable whirls forming a dissipative patch slowly rotating around its center of mass, the latter almost at rest. This approach predicts von Karman's constant as 1/sqrt(2 pi) = 0.399 and the spatio-temporal dynamics of energy-containing time and length scales controlling turbulent mixing [Baumert 2005, 2009]. A link to turbulence spectra was missing so far. In the present contribution it is shown that the above image of dipole movements is compatible with Kolmogorov's spectra if dissipative patches, beginning as two likewise rotating eddies, evolve locally into a space-filling bearing in the sense of Herrmann [1990], i.e. into an ``Apollonian gear.'' Its parts and pieces are are frictionless, excepting the dissipative scale of size zero. Our approach predicts the dimensionless pre-factor in the 3D Eulerian wavenumber spectrum (in terms of pi) as 1.8, and in the Lagrangian frequency spectrum as the integer number 2. Our derivations are free of empirical relations and rest on geometry, methods from many-particle physics, and on elementary conservation laws only. Department of the Navy Grant, ONR Global

  7. Constant mean curvature slicings of Kantowski-Sachs spacetimes

    SciTech Connect

    Heinzle, J. Mark

    2011-04-15

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

  8. Microwave dielectric constants of silicon, gallium arsenide, and quartz

    SciTech Connect

    Seeger, K.

    1988-06-01

    For a determination of the dielectric constants epsilon of semiconductors, a microwave transmission interference method has been applied. For the first time, a calculation is presented which yields the full interference spectrum, not only the position of the extremal points. A comparison of the theoretical and experimental spectra results in a higher precision than previously obtained. A metal evaporation of the sample faces which are in contact with the waveguide walls turns out to be very important. Relative dielectric constants of 11.6 for silicon, 12.8 for gallium arsenide, and 4.6 for crystalline quartz, all +- 0.05, have been obtained.

  9. Topological Quantization in Units of the Fine Structure Constant

    SciTech Connect

    Maciejko, Joseph; Qi, Xiao-Liang; Drew, H.Dennis; Zhang, Shou-Cheng; /Stanford U., Phys. Dept. /Stanford U., Materials Sci. Dept. /SLAC

    2011-11-11

    Fundamental topological phenomena in condensed matter physics are associated with a quantized electromagnetic response in units of fundamental constants. Recently, it has been predicted theoretically that the time-reversal invariant topological insulator in three dimensions exhibits a topological magnetoelectric effect quantized in units of the fine structure constant {alpha} = e{sup 2}/{h_bar}c. In this Letter, we propose an optical experiment to directly measure this topological quantization phenomenon, independent of material details. Our proposal also provides a way to measure the half-quantized Hall conductances on the two surfaces of the topological insulator independently of each other.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Direct expressions for magnetic anisotropy constants

    NASA Astrophysics Data System (ADS)

    Miura, Daisuke; Sasaki, Ryo; Sakuma, Akimasa

    2015-11-01

    Direct expressions for the magnetic anisotropy constants are given at a finite temperature from a microscopic viewpoint. The present derivation assumes that the Hamiltonian is a linear function with respect to the magnetization direction. We discuss in detail the first-order anisotropy constant K1 and show that our present results reproduce previous results. We applied our method to Nd2Fe14B compounds and confirmed that the present method can reproduce the temperature dependence of the magnetocrystalline anisotoropy constants K1, K2, and K3 well.

  12. Latest rocket measurements of the solar constant

    NASA Technical Reports Server (NTRS)

    Duncan, C. H.; Willson, R. C.; Kendall, J. M.; Harrison, R. G.; Hickey, J. R.

    1982-01-01

    Three rocket flights which carried a payload of absolute radiometers to measure the solar constant with an accuracy of plus or minus 0.5 per cent have been accomplished. Several of the rocket radiometers were duplicates of those aboard the Solar Maximum Mission and Nimbus spacecrafts. The values for the solar constant obtained by the rocket sensors for the three flight dates indicate an increase between the first and latter two flights approximately equivalent to the uncertainty of the measurements. The values for the solar constant for the three flights are 1367, 1372 and 1374 W/sq m.

  13. Quantum hyperbolic geometry in loop quantum gravity with cosmological constant

    NASA Astrophysics Data System (ADS)

    Dupuis, Maïté; Girelli, Florian

    2013-06-01

    Loop quantum gravity (LQG) is an attempt to describe the quantum gravity regime. Introducing a nonzero cosmological constant Λ in this context has been a standing problem. Other approaches, such as Chern-Simons gravity, suggest that quantum groups can be used to introduce Λ into the game. Not much is known when defining LQG with a quantum group. Tensor operators can be used to construct observables in any type of discrete quantum gauge theory with a classical/quantum gauge group. We illustrate this by constructing explicitly geometric observables for LQG defined with a quantum group and show for the first time that they encode a quantized hyperbolic geometry. This is a novel argument pointing out the usefulness of quantum groups as encoding a nonzero cosmological constant. We conclude by discussing how tensor operators provide the right formalism to unlock the LQG formulation with a nonzero cosmological constant.

  14. Marshak waves: Constant flux vs constant T-a (slight) paradigm shift

    SciTech Connect

    Rosen, M.D.

    1994-12-22

    We review the basic scaling laws for Marshak waves and point out the differences in results for wall loss, albedo, and Marshak depth when a constant absorbed flux is considered as opposed to a constant absorbed temperature. Comparisons with LASNEX simulations and with data are presented that imply that a constant absorbed flux is a more appropriate boundary condition.

  15. Constants of motion in stationary axisymmetric gravitational fields

    NASA Astrophysics Data System (ADS)

    Markakis, C.

    2014-07-01

    The motion of test particles in stationary axisymmetric gravitational fields is generally non-integrable unless a non-trivial constant of motion, in addition to energy and angular momentum along the symmetry axis, exists. The Carter constant in Kerr-de Sitter space-time is the only example known to date. Proposed astrophysical tests of the black hole no-hair theorem have often involved integrable gravitational fields more general than the Kerr family, but the existence of such fields has been a matter of debate. To elucidate this problem, we treat its Newtonian analogue by systematically searching for non-trivial constants of motion polynomial in the momenta and obtain two theorems. First, solving a set of quadratic integrability conditions, we establish the existence and uniqueness of the family of stationary axisymmetric potentials admitting a quadratic constant. As in Kerr-de Sitter space-time, the mass moments of this class satisfy a `no-hair' recursion relation M2l +2 = a2M2l, and the constant is Noether related to a second-order Killing-Stäckel tensor. Second, solving a new set of quartic integrability conditions, we establish non-existence of quartic constants. Remarkably, a subset of these conditions is satisfied when the mass moments obey a generalized `no-hair' recursion relation M2l +4 = (a2 + b2)M2l +2 - a2b2M2l. The full set of quartic integrability conditions, however, cannot be satisfied non-trivially by any stationary axisymmetric vacuum potential.

  16. The Cosmological Constant in Quantum Cosmology

    SciTech Connect

    Wu Zhongchao

    2008-10-10

    Hawking proposed that the cosmological constant is probably zero in quantum cosmology in 1984. By using the right configuration for the wave function of the universe, a complete proof is found very recently.

  17. The Solar Constant: A Take Home Lab

    ERIC Educational Resources Information Center

    Eaton, B. G.; And Others

    1977-01-01

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

  18. How the cosmological constant affects gravastar formation

    SciTech Connect

    Chan, R.; Silva, M.F.A. da; Rocha, P. E-mail: mfasnic@gmail.com

    2009-12-01

    Here we generalized a previous model of gravastar consisted of an internal de Sitter spacetime, a dynamical infinitely thin shell with an equation of state, but now we consider an external de Sitter-Schwarzschild spacetime. We have shown explicitly that the final output can be a black hole, a ''bounded excursion'' stable gravastar, a stable gravastar, or a de Sitter spacetime, depending on the total mass of the system, the cosmological constants, the equation of state of the thin shell and the initial position of the dynamical shell. We have found that the exterior cosmological constant imposes a limit to the gravastar formation, i.e., the exterior cosmological constant must be smaller than the interior cosmological constant. Besides, we have also shown that, in the particular case where the Schwarzschild mass vanishes, no stable gravastar can be formed, but we still have formation of black hole.

  19. Constant-amplitude, frequency- independent phase shifter

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.

    1971-01-01

    Electronic circuit using operational amplifiers provides output with constant phase shift amplitude, with respect to sinusoidal input, over wide range of frequencies. New circuit includes field effect transistor, Q, operational amplifiers, A1 and A2, and phase detector.

  20. The Rate Constant for Fluorescence Quenching

    ERIC Educational Resources Information Center

    Legenza, Michael W.; Marzzacco, Charles J.

    1977-01-01

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

  1. Dielectric constant of water in the interface

    NASA Astrophysics Data System (ADS)

    Dinpajooh, Mohammadhasan; Matyushov, Dmitry V.

    2016-07-01

    We define the dielectric constant (susceptibility) that should enter the Maxwell boundary value problem when applied to microscopic dielectric interfaces polarized by external fields. The dielectric constant (susceptibility) of the interface is defined by exact linear-response equations involving correlations of statistically fluctuating interface polarization and the Coulomb interaction energy of external charges with the dielectric. The theory is applied to the interface between water and spherical solutes of altering size studied by molecular dynamics (MD) simulations. The effective dielectric constant of interfacial water is found to be significantly lower than its bulk value, and it also depends on the solute size. For TIP3P water used in MD simulations, the interface dielectric constant changes from 9 to 4 when the solute radius is increased from ˜5 to 18 Å.

  2. Dielectric constant of water in the interface.

    PubMed

    Dinpajooh, Mohammadhasan; Matyushov, Dmitry V

    2016-07-01

    We define the dielectric constant (susceptibility) that should enter the Maxwell boundary value problem when applied to microscopic dielectric interfaces polarized by external fields. The dielectric constant (susceptibility) of the interface is defined by exact linear-response equations involving correlations of statistically fluctuating interface polarization and the Coulomb interaction energy of external charges with the dielectric. The theory is applied to the interface between water and spherical solutes of altering size studied by molecular dynamics (MD) simulations. The effective dielectric constant of interfacial water is found to be significantly lower than its bulk value, and it also depends on the solute size. For TIP3P water used in MD simulations, the interface dielectric constant changes from 9 to 4 when the solute radius is increased from ∼5 to 18 Å. PMID:27394114

  3. Holographic dark energy with varying gravitational constant

    NASA Astrophysics Data System (ADS)

    Jamil, Mubasher; Saridakis, Emmanuel N.; Setare, M. R.

    2009-08-01

    We investigate the holographic dark energy scenario with a varying gravitational constant, in flat and non-flat background geometry. We extract the exact differential equations determining the evolution of the dark energy density-parameter, which include G-variation correction terms. Performing a low-redshift expansion of the dark energy equation of state, we provide the involved parameters as functions of the current density parameters, of the holographic dark energy constant and of the G-variation.

  4. Simple constant-current-regulated power supply

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  5. A model for solar constant secular changes

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1988-01-01

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

  6. Optical constants of concentrated aqueous ammonium sulfate.

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.

    1973-01-01

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

  7. Divergences and involution-dependent constants

    SciTech Connect

    Nagao, G.

    1989-01-01

    The authors show the cancellation of the dilation divergence in the 1-loop open bosonic string vacuum and N-tachyon scattering amplitude depends upon a set of involution-dependent constants. Such a set of constants exists at each loop level and thus provides a means with which to study the connection between the cancellation of divergences and anomalies for the gauge group SO(2/sup D/2/).

  8. Theoretical Analysis of One-Dimensional Pressure Diffusion from a Constant Upstream Pressure to a Constant Downstream Storage

    NASA Astrophysics Data System (ADS)

    Song, Insun

    2016-05-01

    The one-dimensional diffusion equation was solved to understand the pressure and flow behaviors along a cylindrical rock specimen for experimental boundary conditions of constant upstream pressure and constant downstream storage. The solution consists of a time-constant asymptotic part and a transient part that is a negative exponential function of time. This means that the transient flow exponentially decays with time and is eventually followed by a steady-state condition. For a given rock sample, the transient stage is shortest when the downstream storage is minimized. For this boundary condition, a simple equation was derived from the analytic solution to determine the hydraulic permeability from the initial flow rate during the transient stage. The specific storage of a rock sample can be obtained simply from the total flow into the sample during the entire transient stage if there is no downstream storage. In theory, both of these hydraulic properties could be obtained simultaneously from transient-flow stage measurements without a complicated curve fitting or inversion process. Sensitivity analysis showed that the derived permeability is more reliable for lower-permeability rock samples. In conclusion, the constant head method with no downstream storage might be more applicable to extremely low-permeability rocks if the upstream flow rate is measured precisely upstream.

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

    NASA Technical Reports Server (NTRS)

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

    1970-01-01

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

  10. Effective optical constants of anisotropic materials

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  11. RNA structure and scalar coupling constants

    SciTech Connect

    Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G.

    1994-12-01

    Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.

  12. Inflation with a constant rate of roll

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  13. Fundamental constants and cosmic vacuum: The micro and macro connection

    NASA Astrophysics Data System (ADS)

    Fritzsch, Harald; Solà, Joan

    2015-06-01

    The idea that the vacuum energy density ρΛ could be time-dependent is a most reasonable one in the expanding Universe; in fact, much more reasonable than just a rigid cosmological constant for the entire cosmic history. Being ρΛ = ρΛ(t) dynamical, it offers a possibility to tackle the cosmological constant problem in its various facets. Furthermore, for a long time (most prominently since Dirac’s first proposal on a time variable gravitational coupling) the possibility that the fundamental “constants” of Nature are slowly drifting with the cosmic expansion has been continuously investigated. In the last two decades, and specially in recent times, mounting experimental evidence attests that this could be the case. In this paper, we consider the possibility that these two groups of facts might be intimately connected, namely that the observed acceleration of the Universe and the possible time variation of the fundamental constants are two manifestations of the same underlying dynamics. We call it: the “micro and macro connection”, and on its basis we expect that the cosmological term in Einstein’s equations, Newton’s coupling and the masses of all the particles in the Universe, both the dark matter (DM) particles and the ordinary baryons and leptons, should all drift with the cosmic expansion. Here, we discuss specific cosmological models realizing such possibility in a way that preserves the principle of covariance of general relativity (GR).

  14. Scrutinizing the cosmological constant problem and a possible resolution

    NASA Astrophysics Data System (ADS)

    Bernard, Denis; LeClair, André

    2013-03-01

    We suggest a new perspective on the cosmological constant problem by scrutinizing its standard formulation. In classical and quantum mechanics without gravity, there is no definition of the zero point of energy. Furthermore, the Casimir effect only measures how the vacuum energy changes as one varies a geometric modulus. This leads us to propose that the physical vacuum energy in a Friedmann-Lemaître-Robertson-Walker expanding universe only depends on the time variation of the scale factor a(t). Equivalently, requiring that empty Minkowski space is gravitationally stable is a principle that fixes the ambiguity in the zero-point energy. On the other hand, if there is a meaningful bare cosmological constant, this prescription should be viewed as a fine-tuning. We describe two different choices of vacuum, one of which is consistent with the current universe consisting only of matter and vacuum energy. The resulting vacuum energy density ρvac is constant in time and approximately kc2H02, where kc is a momentum cutoff and H0 is the current Hubble constant; for a cutoff close to the Planck scale, values of ρvac in agreement with astrophysical measurements are obtained. Another choice of vacuum is more relevant to the early universe consisting of only radiation and vacuum energy, and we suggest it as a possible model of inflation.

  15. Measurements of the gravitational constant - why we need new ideas

    NASA Astrophysics Data System (ADS)

    Schlamminger, Stephan

    2016-03-01

    In this presentation, I will summarize measurements of the Newtonian constant of gravitation, big G, that have been carried out in the last 30 years. I will describe key techniques that were used by researchers around the world to determine G. Unfortunately, the data set is inconsistent with itself under the assumption that the gravitational constant does not vary in space or time, an assumption that has been tested by other experiments. Currently, several research groups have reported measurements with relative uncertainties below 2 ×10-5 , however, the relative difference between the smallest and largest reported number exceeds 5 ×10-4 . It is embarrassing that after over 200 years of measuring the gravitational constant, we do not have a better understanding of the numerical value of this constant. Clearly, we need new ideas to tackle this problem and now is the time to come forward with new ideas. The National Science Foundation is currently soliciting proposals for an Ideas Lab on measuring big G. In the second part of the presentation, I will introduce the Ideas Lab on big G and I am hoping to motivate the audience to think about new ideas to measure G and encourage them to apply to participate in the Ideas Lab.

  16. The afterhyperpolarization conductance exerts the same control over the gain and variability of motoneurone firing in anaesthetized cats

    PubMed Central

    Manuel, Marin; Meunier, Claude; Donnet, Maud; Zytnicki, Daniel

    2006-01-01

    Does the afterhyperpolarization current control the gain and discharge variability of motoneurones according to the same law? We investigated this issue in lumbar motoneurones of anaesthetized cats. Using dynamic clamp, we measured the conductance, time constant and driving force of the AHP current in a sample of motoneurones and studied how the gain was correlated to these quantities. To study the action of the AHP on the discharge variability and to compare it to its action on the gain, we injected an artificial AHP-like current in motoneurones. This increased the natural AHP. In three motoneurones, we abolished most of the natural AHP with the calcium chelator BAPTA to investigate the condition where the discharge was essentially controlled by the artificial AHP. Our results demonstrate that both the gain and the coefficient of variation of the firing rate are inversely proportional to the magnitude and to the time constant of the artificial AHP conductance. This indicates that the AHP exerts the same control over the gain and the variability. This mechanism ensures that the variability of the discharge is modulated with the gain. This guarantees a great regularity of the discharge when the motoneurone is in a low excitability state and hence good control of the force produced. PMID:16931549

  17. The Fine-Structure Constant and Wavelength Calibration

    NASA Astrophysics Data System (ADS)

    Whitmore, Jonathan

    The fine-structure constant is a fundamental constant of the universe--and widely thought to have an unchanging value. However, the past decade has witnessed a controversy unfold over the claimed detection that the fine-structure constant had a different value in the distant past. These astrophysical measurements were made with spectrographs at the world's largest optical telescopes. The spectrographs make precise measurements of the wavelength spacing of absorption lines in the metals in the gas between the quasar background source and our telescopes on Earth. The wavelength spacing gives a snapshot of the atomic physics at the time of the interaction. Whether the fine-structure constant has changed is determined by comparing the atomic physics in the distant past with the atomic physics of today. We present our contribution to the discussion by analyzing three nights data taken with the HIRES instrument (High Resolution Echelle Spectrograph) on the Keck telescope. We provide an independent measurement on the fine-structure constant from the Damped Lyman alpha system at a redshift of z =2.309 (10.8 billion years ago) quasar PHL957. We developed a new method for calibrating the wavelength scale of a quasar exposure to a much higher precision than previously achieved. In our subsequent analysis, we discovered unexpected wavelength calibration errors that has not been taken into account in the previously reported measurements. After characterizing the wavelength miscalibrations on the Keck-HIRES instrument, we obtained several nights of data from the main competing instrument, the VLT (Very Large Telescope) with UVES (Ultraviolet and Visual Echelle Spectrograph). We applied our new wavelength calibration method and uncovered similar in nature systematic errors as found on Keck-HIRES. Finally, we make a detailed Monte Carlo exploration of the effects that these miscalibrations have on making precision fine-structure constant measurements.

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

    PubMed Central

    Syganow, A; von Kitzing, E

    1999-01-01

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

  19. Does the Newtonian Gravity "Constant" G Vary?

    NASA Astrophysics Data System (ADS)

    Noerdlinger, Peter D.

    2015-08-01

    A series of measurements of Newton's gravity constant, G, dating back as far as 1893, yielded widely varying values, the variation greatly exceeding the stated error estimates (Gillies, 1997; Quinn, 2000, Mohr et al 2008). The value of G is usually said to be unrelated to other physics, but we point out that the 8B Solar Neutrino Rate ought to be very sensitive. Improved pulsar timing could also help settle the issue as to whether G really varies. We claim that the variation in measured values over time (1893-2014 C.E.) is a more serious problem than the failure of the error bars to overlap; it appears that challenging or adjusting the error bars hardly masks the underlying disagreement in central values. We have assessed whether variations in the gravitational potential due to (for example) local dark matter (DM) could explain the variations. We find that the required potential fluctuations could transiently accelerate the Solar System and nearby stars to speeds in excess of the Galactic escape speed. Previous theories for the variation in G generally deal with supposed secular variation on a cosmological timescale, or very rapid oscillations whose envelope changes on that scale (Steinhardt and Will 1995). Therefore, these analyses fail to support variations on the timescale of years or spatial scales of order parsecs, which would be required by the data for G. We note that true variations in G would be associated with variations in clock rates (Derevianko and Pospelov 2014; Loeb and Maoz 2015), which could mask changes in orbital dynamics. Geringer-Sameth et al (2014) studied γ-ray emission from the nearby Reticulum dwarf galaxy, which is expected to be free of "ordinary" (stellar, black hole) γ-ray sources and found evidence for DM decay. Bernabei et al (2003) also found evidence for DM penetrating deep underground at Gran Sasso. If, indeed, variations in G can be tied to variations in gravitational potential, we have a new tool to assess the DM density.

  20. Athermal nonlinear elastic constants of amorphous solids.

    PubMed

    Karmakar, Smarajit; Lerner, Edan; Procaccia, Itamar

    2010-08-01

    We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities such as plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elastoplasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of our calculations we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place. PMID:20866874

  1. Athermal nonlinear elastic constants of amorphous solids

    NASA Astrophysics Data System (ADS)

    Karmakar, Smarajit; Lerner, Edan; Procaccia, Itamar

    2010-08-01

    We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities such as plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elastoplasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of our calculations we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place.

  2. Modified Analytical Hierarchy Process (M-AHP) Based River-Line Flood Hazard Assessment Module Running on GIS: Netcad Architect Environment

    NASA Astrophysics Data System (ADS)

    Avdac, Dogus; Poyraz, Mert; Nefeslioglu, Hakan A.; Sezer, Ebru A.; Toptas, Tunc E.; Celik, Deniz; Orhun, Koray; Osna, Turgay; Ak, Serdar; Gokceoglu, Candan

    2014-05-01

    The main purpose of the present study is to introduce an expert based river-line flood hazard assessment approach, and develop a module running this approach on Netcad Architect environment. The spatial variability of river-line flood hazard was evaluated by considering two components of the phenomenon. The first component defines the heuristic infiltration rates of ground while the second one expresses the heuristic potential of water accumulation. In order to model these heuristic concepts geological, geomorphological, and environmental factors were implemented. Soil erosion observed on residual soils of volcanic rocks, slope gradient and slope aspect of natural topography, and normalized difference vegetation index acquired from natural vegetation were considered to be the primary conditioning factors controlling the infiltration rates during possible short-term or long-term rainfall events. Additionally, the slope gradient of topography, drainage channel density, and topographic wetness index of ground being one of the second derivatives of topography were evaluated to be the main conditioning factors controlling water accumulation on ground. The conditioning factors evaluated in the present study were handled in Netcad GIS 6.0 environment. Netcad GIS 6.0 has all of the abilities which expected from a traditional GIS. Additionally, it has a new module namely Netcad Architect which enables to describe processes visually. The majority of the Architect was developed within ".Net". The main concept of the Architect is "Operator" and it corresponds the complex routines which maps inputs coming from data sources to output. As can be seen from this definition, the M-AHP and other expert based approaches could be easily defined as new operators in the Architect. Some of operators are specifically named as "Geocalculator" which provides templates for different forms of linear formulae. Similarly, operators which present templates of matrix are called as "Geokernel". The

  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. Clusters of Galaxies and the Hubble Constant

    NASA Astrophysics Data System (ADS)

    Falcon, N.

    2008-09-01

    The expansion rate, at height scale, of the Universe, is given for the value of the Hubble constant (H0). Several methods have used by determinations of the Hubble constant: CMB anisotropy's, Supernovae observation and AGN at height red-shift. In this work, we used the Grainge et al (3) method by estimated of the Hubble constant thought of the Sunyaev-Zel'dovich effect and the result of the VSA interferometer (Teide Observatory) and the X-ray data by ROSAT. We obtain, h ? 0,78, in accord with other report by cluster of galaxies (Mason et al, 2001) as higher than of the standard value h =0,71 obtain by other method. We discussed the systematic fount of error and possible discrepant by assumptions of the spheroid and isothermal in cluster and the Sunyaev- Zel'dovich Kinetic effect.

  5. Binary Solid Propellants for Constant Momentum Missions

    SciTech Connect

    Pakhomov, Andrew V.; Mahaffy, Kevin E.

    2008-04-28

    A constant momentum mission is achieved when the speed of the vehicle in the inertial frame of reference is equal to the speed of exhaust relative to the vehicle. Due to 100% propulsive efficiency such missions are superior to traditional constant specific impulse missions. A new class of solid binary propellants for constant momentum missions is under development. A typical propellant column is prepared as a solid solution of two components, with composition gradually changing from 100% of a propellant of high coupling coefficient (C{sub m}) to one which has high specific impulse (I{sub sp}). The high coupling component is ablated first, gradually giving way to the high I{sub sp} component, as the vehicle accelerates. This study opens new opportunities for further design of complex propellants for laser propulsion, providing variable C{sub m} and I{sub sp} during missions.

  6. Ground State of the Universe and the Cosmological Constant. A Nonperturbative Analysis

    NASA Astrophysics Data System (ADS)

    Husain, Viqar; Qureshi, Babar

    2016-02-01

    The physical Hamiltonian of a gravity-matter system depends on the choice of time, with the vacuum naturally identified as its ground state. We study the expanding Universe with scalar field in the volume time gauge. We show that the vacuum energy density computed from the resulting Hamiltonian is a nonlinear function of the cosmological constant and time. This result provides a new perspective on the relation between time, the cosmological constant, and vacuum energy.

  7. Fundamental Constants as Monitors of Particle Physics and Dark Energy

    NASA Astrophysics Data System (ADS)

    Thompson, Rodger

    2016-03-01

    This contribution considers the constraints on particle physics and dark energy parameter space imposed by the astronomical observational constraints on the variation of the proton to electron mass ratio μ and the fine structure constant α. These constraints impose limits on the temporal variation of these parameters on a time scale greater than half the age of the universe, a time scale inaccessible by laboratory facilities such as the Large Hadron Collider. The limits on the variance of μ and α constrain combinations of the QCD Scale, the Higgs VEV and the Yukawa coupling on the particle physics side and a combination of the temporal variation of rolling scalar field and its coupling to the constants on the dark energy side.

  8. New process to avoid emissions: Constant pressure in coke ovens

    SciTech Connect

    Giertz, J.; Huhn, F.; Hofherr, K.

    1995-12-01

    A chamber pressure regulation (PROven), especially effective in regard to emission control problems of coke ovens is introduced for the first time. Because of the partial vacuum in the collecting main system, it is possible to keep the oven`s raw gas pressure constant on a low level over the full coking time. The individual pressure control for each chamber is assured directly as a function of the oven pressure by an immersion system controlling the flow resistance of the collecting main valve. The latter is a fixed-position design (system name ``FixCup``). By doing away with the interdependence of collecting main pressure and chamber pressure, a parameter seen as a coking constant could not be made variable. This opens a new way to reduce coke oven emissions and simultaneously to prevent the ovens from damage caused by air ingress into the oven.

  9. A computational 3D model for reconstruction of neural stem cells in bright-field time-lapse microscopy

    NASA Astrophysics Data System (ADS)

    Degerman, J.; Winterfors, E.; Faijerson, J.; Gustavsson, T.

    2007-02-01

    This paper describes a computational model for image formation of in-vitro adult hippocampal progenitor (AHP) cells, in bright-field time-lapse microscopy. Although this microscopymodality barely generates sufficient contrast for imaging translucent cells, we show that by using a stack of defocused image slices it is possible to extract position and shape of spherically shaped specimens, such as the AHP cells. This inverse problem was solved by modeling the physical objects and image formation system, and using an iterative nonlinear optimization algorithm to minimize the difference between the reconstructed and measured image stack. By assuming that the position and shape of the cells do not change significantly between two time instances, we can optimize these parameters using the previous time instance in a Bayesian estimation approach. The 3D reconstruction algorithm settings, such as focal sampling distance, and PSF, were calibrated using latex spheres of known size and refractive index. By using the residual between reconstructed and measured image intensities, we computed a peak signal-to-noise ratio (PSNR) to 28 dB for the sphere stack. A biological specimen analysis was done using an AHP cell, where reconstruction PSNR was 28 dB as well. The cell was immuno-histochemically stained and scanned in a confocal microscope, in order to compare our cell model to a ground truth. After convergence the modelled cell volume had an error of less than one percent.

  10. Optimizing constant wavelength neutron powder diffractometers

    NASA Astrophysics Data System (ADS)

    Cussen, Leo D.

    2016-06-01

    This article describes an analytic method to optimize constant wavelength neutron powder diffractometers. It recasts the accepted mathematical description of resolution and intensity in terms of new variables and includes terms for vertical divergence, wavelength and some sample scattering effects. An undetermined multiplier method is applied to the revised equations to minimize the RMS value of resolution width at constant intensity and fixed wavelength. A new understanding of primary spectrometer transmission (presented elsewhere) can then be applied to choose beam elements to deliver an optimum instrument. Numerical methods can then be applied to choose the best wavelength.

  11. Environmental dependence of masses and coupling constants

    SciTech Connect

    Olive, Keith A.; Pospelov, Maxim

    2008-02-15

    We construct a class of scalar field models coupled to matter that lead to the dependence of masses and coupling constants on the ambient matter density. Such models predict a deviation of couplings measured on the Earth from values determined in low-density astrophysical environments, but do not necessarily require the evolution of coupling constants with the redshift in the recent cosmological past. Additional laboratory and astrophysical tests of {delta}{alpha} and {delta}(m{sub p}/m{sub e}) as functions of the ambient matter density are warranted.

  12. Dielectric constants of soils at microwave frequencies

    NASA Technical Reports Server (NTRS)

    Geiger, F. E.; Williams, D.

    1972-01-01

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

  13. Coulomb field in a constant electromagnetic background

    NASA Astrophysics Data System (ADS)

    Adorno, T. C.; Gitman, D. M.; Shabad, A. E.

    2016-06-01

    Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with a Euler-Heisenberg (EH) effective Lagrangian. The linear electric response to an imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field and corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants. These are specialized for the EH Lagrangian.

  14. Image segmentation via piecewise constant regression

    NASA Astrophysics Data System (ADS)

    Acton, Scott T.; Bovik, Alan C.

    1994-09-01

    We introduce a novel unsupervised image segmentation technique that is based on piecewise constant (PICO) regression. Given an input image, a PICO output image for a specified feature size (scale) is computed via nonlinear regression. The regression effectively provides the constant region segmentation of the input image that has a minimum deviation from the input image. PICO regression-based segmentation avoids the problems of region merging, poor localization, region boundary ambiguity, and region fragmentation. Additionally, our segmentation method is particularly well-suited for corrupted (noisy) input data. An application to segmentation and classification of remotely sensed imagery is provided.

  15. Black hole constraints on varying fundamental constants.

    PubMed

    MacGibbon, Jane H

    2007-08-10

    We apply the generalized second law of thermodynamics and derive upper limits on the variation in the fundamental constants. The maximum variation in the electronic charge permitted for black holes accreting and emitting in the present cosmic microwave background corresponds to a variation in the fine-structure constant of Deltaalpha/alpha approximately 2 x 10(-23) per second. This value matches the variation measured by Webb et al. [Phys. Rev. Lett. 82, 884 (1999); Phys. Rev. Lett. 87, 091301 (2001)] using absorption lines in the spectra of distant quasars and suggests the variation mechanism may be a coupling between the electron and the cosmic photon background. PMID:17930813

  16. Atomic weights: no longer constants of nature

    USGS Publications Warehouse

    Coplen, Tyler B.; Holden, Norman E.

    2011-01-01

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

  17. Atomic Weights No Longer Constants of Nature

    SciTech Connect

    Coplen, T.B.; Holden, N.

    2011-03-01

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

  18. Microfabricated microengine with constant rotation rate

    DOEpatents

    Romero, Louis A.; Dickey, Fred M.

    1999-01-01

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

  19. Our Universe from the cosmological constant

    SciTech Connect

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

    2014-12-01

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

  20. Atom interferometry using wave packets with constant spatial displacements

    SciTech Connect

    Su, Edward J.; Prentiss, Mara G.; Wu Saijun

    2010-04-15

    A standing-wave light-pulse sequence is demonstrated that places atoms into a superposition of wave packets with precisely controlled displacements that remain constant for times as long as 1 s. The separated wave packets are subsequently recombined, resulting in atom interference patterns that probe energy differences of {approx_equal}10{sup -34} J and can provide acceleration measurements that are insensitive to platform vibrations.

  1. The cosmological constant and the energy of gravitational radiation

    NASA Astrophysics Data System (ADS)

    Chruściel, Piotr T.; Ifsits, Lukas

    2016-06-01

    We propose a definition of mass for characteristic hypersurfaces in asymptotically vacuum space-times with nonvanishing cosmological constant Λ ∈R* , generalizing the definition of Trautman and Bondi for Λ =0 . We show that our definition reduces to some standard definitions in several situations. We establish a balance formula linking the characteristic mass and a suitably defined renormalized volume of the null hypersurface, generalizing the positivity identity proved by Chruściel and Paetz when Λ =0 .

  2. Cosmological constant, violation of cosmological isotropy and CMB

    SciTech Connect

    Urban, Federico R.; Zhitnitsky, Ariel R. E-mail: arz@physics.ubc.ca

    2009-09-01

    We suggest that the solution to the cosmological vacuum energy puzzle does not require any new field beyond the standard model, but rather can be explained as a result of the interaction of the infrared sector of the effective theory of gravity with standard model fields. The cosmological constant in this framework can be presented in terms of QCD parameters and the Hubble constant H as follows, ε{sub vac} ≅ H⋅m{sub q}( q-bar q)/m{sub η'} ≅ (4.3⋅10{sup −3}eV){sup 4}, which is amazingly close to the observed value today. In this work we explain how this proposal can be tested by analyzing CMB data. In particular, knowing the value of the observed cosmological constant fixes univocally the smallest size of the spatially flat, constant time 3d hypersurface which, for instance in the case of an effective 1-torus, is predicted to be around 74 Gpc. We also comment on another important prediction of this framework which is a violation of cosmological isotropy. Such anisotropy is indeed apparently observed by WMAP, and will be confirmed (or ruled out) by future PLANCK data.

  3. Hydrogen, deuterium and tritium in palladium: An eleastic constants study

    SciTech Connect

    Bach, H. T.; Schwarz, R. B.; Tuggle, D. G.

    2004-01-01

    We have used resonant ultrasound spectroscopy to measure the three independent elastic constants of Pd-H, Pd-D, and Pd-T single crystal at 300K as a junction of hydrogen, deuterium, and tritium concentration, respectively. The addition of interstitial H (D, or T) atoms, located at (0, 1/2, 0) in the fcc Pd lattice, affects all three elastic constants C, C{sub 44}, and B. In the mixed (a+{beta}) phase, and with increasing H isotope, the shear modulus C' shows an abnormal softening whereas C{sub 44} and B do not. This is explained in terms of Zener-type anelastic relaxations affecting the shape of the hydride phases in the coherent ({alpha}+{beta}) two-phase mixture In the single {beta}-phase, C' shows a strong isotope dependence whereas C{sub 44} and B show none. This behavior is explained in terms of differences in the excitation of optical phonons. In Pd-T, {sup 3}He is produced by the radioactive decay of tritium. We have measured in situ the swelling and the change in the elastic constants in Pd-T as a function of aging time. Aging ({sup 3}He formation) affects all three elastic constants. These measurements are being used to understand the early stages of {sup 3}H-{sup 3}He clusterformation in aged Pd-T crystal.

  4. Constant curvature solutions of Grassmannian sigma models: (2) Non-holomorphic solutions

    NASA Astrophysics Data System (ADS)

    Delisle, L.; Hussin, V.; Zakrzewski, W. J.

    2013-09-01

    We generalize here our general procedure for constructing constant curvature maps of 2-spheres into Grassmannian manifolds G(m,n) this time concentrating our attention on maps which are non-holomorphic. We present some expressions describing these solutions in the general case and discuss how to use these results to construct solutions of constant curvature. We also discuss possible values of this constant curvature.

  5. Gradient chromatography under constant frictional heat: realization and application.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2013-05-10

    A new mode of gradient elution in liquid chromatography is proposed. It is derived from simple theoretical considerations and is particularly suitable for applications to fast, very-high pressure gradients. It is designed to improve the injection-to-injection repeatability of chromatographic runs at either constant flow (cF, cooling case scenario) or constant pressure (cP, heating case scenario). The purpose of this original gradient mode is to minimize the variations of the temperatures and the pressures across and along the column during the gradient time. These variations are caused by the heat generated in the column due to the friction of the eluent percolating the bed. Any temperature fluctuation affects to some extent the precision of the measurements of retention times and bandwidths of eluted compounds. The minimization of this effect was achieved by maintaining constant the frictional heat power (i.e., the product of the flow rate by the column pressure drop) generated during the gradient run, the washing step, and the re-equilibration time. The eluent temperature was recorded at the column outlet. One useful application of gradient chromatography at constant frictional heat (cFH) is illustrated for a 50-100% volume gradient of acetonitrile in water using a 4.6mm × 150 mm column packed with 3.5 μm BEH-C18 particles and operated with an Agilent 1290 Infinity liquid chromatograph. The reproducibility (eleven consecutive injections) of the retention times and peak variances of nine small molecules (RPLC check-out sample mixture) using cF, cP, and cFH gradients were compared for the same amount of heat produced (403 J) during each run time. The RSDs of the retention times and the peak variances for four consecutive injections were systematically below 0.035 and 0.50% in constant frictional heat gradient chromatography, after three initial injections. These RSDs were markedly higher for cF (0.050 and 0.90%) and cP (0.070 and 1.80%) gradients. PMID:23566917

  6. Can compactifications solve the cosmological constant problem?

    NASA Astrophysics Data System (ADS)

    Hertzberg, Mark P.; Masoumi, Ali

    2016-06-01

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

  7. Man's Size in Terms of Fundamental Constants.

    ERIC Educational Resources Information Center

    Press, William H.

    1980-01-01

    Reviews calculations that derive an order of magnitude expression for the size of man in terms of fundamental constants, assuming that man satifies these three properties: he is made of complicated molecules; he requires an atmosphere which is not hydrogen and helium; he is as large as possible. (CS)

  8. Teaching Nanochemistry: Madelung Constants of Nanocrystals

    ERIC Educational Resources Information Center

    Baker, Mark D.; Baker, A. David

    2010-01-01

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

  9. CONSTANT VOLUME SAMPLING SYSTEM WATER CONDENSATION

    EPA Science Inventory

    Combustion of organic motor vehicle fuels produces carbon dioxide and water (H2O) vapor (and also products of incomplete combustion, e.g. hydrocarbons and carbon monoxide, at lower concentrations). he Constant Volume Sampling (CVS) system, commonly used to condition auto exhaust ...

  10. Double well isomerization rate constants in solution

    NASA Astrophysics Data System (ADS)

    Zawadzki, Anthony G.; Hynes, James T.

    1985-02-01

    The rate constant k for a double well isomerization in solution is calculated over the entire friction range. The importance of frequency-dependent friction for both the vibrational energy transfer (VET) and barrier passage components of k is described. Rapid suppression of the VET transfer component with increasing degrees of freedom is discussed.

  11. Stokes constants for a singular wave equation

    SciTech Connect

    Linnaeus, Staffan

    2005-05-01

    The Stokes constants for arbitrary-order phase-integral approximations are calculated when the square of the wave number has either two simple zeros close to a second-order pole or one simple zero close to a first-order pole. The treatment is based on uniform approximations. All parameters may assume general complex values.

  12. Variations of the Solar Constant. [conference

    NASA Technical Reports Server (NTRS)

    Sofia, S. (Editor)

    1981-01-01

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

  13. The ideal Kolmogorov inertial range and constant

    NASA Technical Reports Server (NTRS)

    Zhou, YE

    1993-01-01

    The energy transfer statistics measured in numerically simulated flows are found to be nearly self-similar for wavenumbers in the inertial range. Using the measured self-similar form, an 'ideal' energy transfer function and the corresponding energy flux rate were deduced. From this flux rate, the Kolmogorov constant was calculated to be 1.5, in excellent agreement with experiments.

  14. Mars Pathfinder Project: Planetary Constants and Models

    NASA Technical Reports Server (NTRS)

    Lyons, D.; Vaughn, R.

    1999-01-01

    This document provides a common set of astrodynamic constants and planetary models for use by the Mars pathfinder Project. It attempts to collect in a single reference all the quantities and models in use across the project during development and for mission operations.

  15. Bouncing models with a cosmological constant

    NASA Astrophysics Data System (ADS)

    Maier, Rodrigo; Pereira, Stella; Pinto-Neto, Nelson; Siffert, Beatriz B.

    2012-01-01

    Bouncing models have been proposed by many authors as a completion of, or even as an alternative to, inflation for the description of the very early and dense Universe. However, most bouncing models contain a contracting phase from a very large and rarefied state, where dark energy might have had an important role as it has today in accelerating our large Universe. In that case, its presence can modify the initial conditions and evolution of cosmological perturbations, changing the known results already obtained in the literature concerning their amplitude and spectrum. In this paper, we assume the simplest and most appealing candidate for dark energy, the cosmological constant, and evaluate its influence on the evolution of cosmological perturbations during the contracting phase of a bouncing model, which also contains a scalar field with a potential allowing background solutions with pressure and energy density satisfying p=wɛ, w being a constant. An initial adiabatic vacuum state can be set at the end of domination by the cosmological constant, and an almost scale-invariant spectrum of perturbations is obtained for w≈0, which is the usual result for bouncing models. However, the presence of the cosmological constant induces oscillations and a running towards a tiny red-tilted spectrum for long-wavelength perturbations.

  16. Spray Gun With Constant Mixing Ratio

    NASA Technical Reports Server (NTRS)

    Simpson, William G.

    1987-01-01

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

  17. FATE, THE ENVIRONMENTAL FATE CONSTANTS INFORMATION DATABASE

    EPA Science Inventory

    An online database, FATE, has been developed for the interactive retrieval of kinetic and equilibrium constants that are needed for assessing the fate of chemicals in the environment. he database contains values for up to 12 parameters for each chemical. s of December 1991, FATE ...

  18. Construction of a technique plan repository and evaluation system based on AHP group decision-making for emergency treatment and disposal in chemical pollution accidents.

    PubMed

    Shi, Shenggang; Cao, Jingcan; Feng, Li; Liang, Wenyan; Zhang, Liqiu

    2014-07-15

    The environmental pollution resulting from chemical accidents has caused increasingly serious concerns. Therefore, it is very important to be able to determine in advance the appropriate emergency treatment and disposal technology for different types of chemical accidents. However, the formulation of an emergency plan for chemical pollution accidents is considerably difficult due to the substantial uncertainty and complexity of such accidents. This paper explains how the event tree method was used to create 54 different scenarios for chemical pollution accidents, based on the polluted medium, dangerous characteristics and properties of chemicals involved. For each type of chemical accident, feasible emergency treatment and disposal technology schemes were established, considering the areas of pollution source control, pollutant non-proliferation, contaminant elimination and waste disposal. Meanwhile, in order to obtain the optimum emergency disposal technology schemes as soon as the chemical pollution accident occurs from the plan repository, the technique evaluation index system was developed based on group decision-improved analytical hierarchy process (AHP), and has been tested by using a sudden aniline pollution accident that occurred in a river in December 2012. PMID:24887122

  19. Assessment of groundwater quality at a MSW landfill site using standard and AHP based water quality index: a case study from Ranchi, Jharkhand, India.

    PubMed

    Chakraborty, Shubhrasekhar; Kumar, R Naresh

    2016-06-01

    Landfill leachate generated from open MSW dumpsite can cause groundwater contamination. The impact of open dumping of MSW on the groundwater of adjacent area was studied. To assess the spatial and temporal variations in groundwater quality, samples were collected around an open MSW dumping site in Ranchi city, Jharkhand, India. Groundwater samples were analysed for various physicochemical and bacteriological parameters for 1 year. Results indicated that the groundwater is getting contaminated due to vertical and horizontal migration of landfill leachate. Extent of contamination was higher in areas closer to the landfill as indicated by high alkalinity, total dissolved solids and ammonia concentration. Metals such as lead, iron, and manganese were present at concentrations of 0.097, 0.97 and 0.36 mg/L, respectively exceeding the Bureau of Indian Standards (BIS) 10,500 for drinking water. Enterobacteriaceae were also detected in several groundwater samples and highest coliform count of 2.1×10(4) CFU/mL was recorded from a dug well. In order to determine the overall groundwater quality, water quality index (WQI) was calculated using weighted arithmetic index method and this index was further modified by coupling with the analytical hierarchy process (AHP) to get specific information. WQI values indicated that the overall groundwater quality of the region came under "poor" category while zone wise classification indicated the extent of impact of landfill leachate on groundwater. PMID:27155859

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

    ERIC Educational Resources Information Center

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

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