Science.gov

Sample records for air conduction thresholds

  1. Air and Bone Conduction Thresholds of Deaf and Normal Hearing Subjects before and during the Elimination of Cutaneous-Tactile Interference with Anesthesia. Final Report.

    ERIC Educational Resources Information Center

    Nober, E. Harris

    The study investigated whether low frequency air and bone thresholds elicited at high intensity levels from deaf children with a sensory-neural diagnosis reflect valid auditory sensitivity or are mediated through cutaneous-tactile receptors. Subjects were five totally deaf (mean age 17.0) yielding vibrotactile thresholds but with no air and bone…

  2. Ocular vestibular-evoked myogenic potentials using air-conducted sound: test parameters and normative data in healthy children; effect of body position on threshold.

    PubMed

    Kastanioudakis, Ioannis; Saravakos, Panagiotis; Leontis, Theodoros; Balatsouras, Dimitrios G; Ziavra, Nausica

    2016-09-01

    In the present prospective study, we both investigated positioning techniques for the enhancement of oVEMP procedures and the viability of oVEMP testing in a healthy children population. A total of 41 healthy children were enrolled in this study. 21 were boys and 20 were girls, with their ages ranging from 4 to 16 years. All children underwent audiometry and tympanometry prior to oVEMP test in upright and supine position. All subjects had normal hearing. The procedure was well tolerated by all children. Typical biphasic oVEMPs presented in 97.56 % in upright position and 90.25 % in the supine position. No statistically significant difference could be found concerning which position elicits the best or worst responses. However, a trend towards the supine position was noticed. It may be concluded that oVEMP test proved to be a well-tolerated examination of the vestibular system in children aged above 4 years old. Our results did not show a statistical difference on the oVEMP thresholds between the two body positions. However, further larger studies are needed to confirm these findings. PMID:26499188

  3. Comparison of umbo velocity in air- and bone-conduction.

    PubMed

    Röösli, Christof; Chhan, David; Halpin, Christopher; Rosowski, John J

    2012-08-01

    This study investigates the ossicular motion produced by bone-conducted (BC) sound in live human ears. Laser Doppler vibrometry was used to measure air conduction (AC)- and BC-induced umbo velocity (V(U)) in both ears of 10 subjects, 20 ears total. Sound pressure in the ear canal (P(EC)) was measured simultaneously. For air conduction, V(U) at standard hearing threshold level was calculated. For BC, ΔV was defined as the difference between V(U) and the tympanic ring velocity (an estimate of the skull velocity measured in the ear canal). ΔV and P(EC) at BC standard hearing threshold were calculated. ΔV at standard BC threshold was significantly smaller than V(U) at standard AC threshold between 500 Hz and 2000 Hz. Ear canal pressure at BC threshold tended to be smaller than for AC below 3000 Hz (with significant differences at 1000 Hz and 2000 Hz). Our results are most consistent with inertia of the ossicles and cochlear fluid driving BC hearing below 500 Hz, but with other mechanisms playing a significant role at higher frequencies. Sound radiated into the external ear canal might contribute to BC hearing at 3000 Hz and above. PMID:22609771

  4. Reference guide to odor thresholds for hazardous air pollutants listed in the Clean Air Act amendments of 1990

    SciTech Connect

    Cain, W.S.; Shoaf, C.R.; Velasquez, S.F.; Selevan, S.; Victery, W.

    1992-03-01

    In response to numerous requests for information related to odor thresholds, this document was prepared by the Air Risk Information Support Center in its role in providing technical assistance to State and Local government agencies on risk assessment of air pollutants. A discussion of basic concepts related to olfactory function and the measurement of odor thresholds is presented. A detailed discussion of criteria which are used to evaluate the quality of published odor threshold values is provided. The use of odor threshold information in risk assessment is discussed. The results of a literature search and review of odor threshold information for the chemicals listed as hazardous air pollutants in the Clean Air Act amendments of 1990 is presented. The published odor threshold values are critically evaluated based on the criteria discussed and the values of acceptable quality are used to determine a geometric mean or best estimate.

  5. Percolation threshold and electrical conductivity of graphene-based nanocomposites with filler agglomeration and interfacial tunneling

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Shan, Jerry W.; Weng, George J.

    2015-08-01

    The dispersion state or degree of agglomeration of graphene is known to have a significant influence on the percolation threshold and electrical conductivity of graphene-based polymer nanocomposites. In addition, an imperfectly conducting interface and tunneling-assisted interfacial conductivity can also affect the overall conductivity. In this paper, a continuum theory is developed that considers all these factors. We first present a two-scale composite model consisting of graphene-rich regions serving as the agglomerates and a graphene-poor region as the matrix. We then introduce the effective-medium theory to determine the percolation threshold and electrical conductivity of the agglomerate and the composite. To account for the effect of imperfect interfaces, a thin layer of interphase with low conductivity is introduced to build a thinly coated graphene, while to account for the contribution of electron hopping from one graphene to another, Cauchy's statistical function which can reflect the increased tunneling activity near the percolation threshold is introduced. It is shown that the percolation threshold of the nanocomposite is controlled by two dispersion parameters, a and b, and the aspect ratio of agglomerates, αR . It is also shown that the overall conductivity of the nanocomposite mainly depends on the intrinsic conductivity of graphene and polymer matrix, the intrinsic interfacial resistivity, and the tunneling-assisted hopping process. We highlight the conceived theory by demonstrating that a set of recently measured data on the percolation threshold and electrical conductivity of graphene/polystyrene nanocomposites can be well captured by it.

  6. REFERENCE GUIDE TO ODOR THRESHOLDS FOR HAZARDOUS AIR POLLUTANTS LISTED IN THE CLEAN AIR ACT AMENDMENTS OF 1990.

    EPA Science Inventory

    In response to numerous requests for information related to odor thresholds, this document was prepared by the Air Risk Information Support Center in its role in providing technical assistance to State and Local government agencies on risk assessment of air pollutants. iscussion ...

  7. Milagro: A low energy threshold extensive air shower array

    NASA Astrophysics Data System (ADS)

    Sinnis, Gus

    1995-07-01

    Observations of gamma-ray bursts, active galactic nuclei, and radio pulsars by CGRO have revolutionized our view of the cosmos. Sources may pop into existence for a few milliseconds never to appear again and galaxies can change their luminosity by an order of magnitude within a few days. In addition to these space-based measurements, there have been at least 2 sources detected at even higher energies, ~1 TeV, using earth-bound detectors. To date, ground-based detectors of high-energy gamma rays with energy thresholds low enough to make credible detections have all had narrow fields of view and low duty factors. While these detectors are well suited to perform detailed studies of selected sources, they can not perform surveys of the entire sky with adequate sensitivity in a reasonable amount of time. We have designed a new type of ground-based gamma-ray detector with a low energy threshold, ~250 GeV, large aperture (~1 sr), and a duty factor greater than 90%-Milagro.

  8. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors

    PubMed Central

    Lee, Sungsik; Nathan, Arokia

    2016-01-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage. PMID:26932790

  9. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors.

    PubMed

    Lee, Sungsik; Nathan, Arokia

    2016-01-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage. PMID:26932790

  10. Conduction Threshold in Accumulation-Mode InGaZnO Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Lee, Sungsik; Nathan, Arokia

    2016-03-01

    The onset of inversion in the metal-oxide-semiconductor field-effect transistor (MOSFET) takes place when the surface potential is approximately twice the bulk potential. In contrast, the conduction threshold in accumulation mode transistors, such as the oxide thin film transistor (TFT), has remained ambiguous in view of the complex density of states distribution in the mobility gap. This paper quantitatively describes the conduction threshold of accumulation-mode InGaZnO TFTs as the transition of the Fermi level from deep to tail states, which can be defined as the juxtaposition of linear and exponential dependencies of the accumulated carrier density on energy. Indeed, this permits direct extraction and visualization of the threshold voltage in terms of the second derivative of the drain current with respect to gate voltage.

  11. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films

    NASA Astrophysics Data System (ADS)

    Rung, S.; Christiansen, A.; Hellmann, R.

    2014-06-01

    We report on a comprehensive study of the laser ablation threshold of transparent conductive oxide thin films. The ablation threshold is determined for both indium tin oxide and gallium zinc oxide as a function of film thickness and for different laser wavelengths. By using a pulsed diode pumped solid state laser at 1064 nm, 532 nm, 355 nm and 266 nm, respectively, the relationship between optical absorption length and film thickness is studied. We find that the ablation threshold decreases with increasing film thickness in a regime where the absorption length is larger than the film thickness. In turn, the ablation threshold increases in case the absorption length is smaller than the film thickness. In particular, we observe a minimum of the ablation threshold in a region where the film thickness is comparable to the absorption length. To the best of our knowledge, this behaviour previously predicted for thin metal films, has been unreported for all three regimes in case of transparent conductive oxides, yet. For industrial laser scribing processes, these results imply that the efficiency can be optimized by using a laser where the optical absorption length is close to the film thickness.

  12. Creating Opal Templated Continuous Conducting Polymer Films with Ultralow Percolation Thresholds Using Thermally Stable Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, D. J.; Kwon, T.; Kim, M. P.; Kim, B. J.; Jung, H.; Bang, J.

    2012-02-01

    We propose a novel and robust strategy for creating continuous conducting polymer films with ultralow percolation thresholds using polymer-coated gold nanoparticles (Au NPs) as surfactant. Continuous poly(triphenylamine) (PTPA) films of high internal phase polymeric emulsions were fabricated using an assembly of crosslinked polystyrene (PS) colloidal particles as template. Polymer-coated Au NPs localize at the PS/PTPA interface and function as surfactant to efficiently produce a continuous conducting PTPA polymer film with very low percolation thresholds. The volume fraction threshold for percolation of the PTPA phase with insulating PS colloids was found to be 0.20. In contrast, with the addition of an extremely low volume fraction of surfactant Au NPs, the volume fraction threshold for percolation of the PTPA phase was dramatically reduced to 0.05. The SEM and TEM measurements clearly demonstrated the formation of a continuous PTPA phase within the polyhedral phase of PS colloids. To elucidate the influence of the nanoparticle surfactant on the blend films, the morphology and conductivity of the blends at different PS colloid/PTPA volume ratios were carefully characterized as a function of the Au NP concentration.

  13. Percolation thresholds and percolation conductivities of octagonal and dodecagonal quasicrystalline lattices

    NASA Astrophysics Data System (ADS)

    Babalievski, F.

    1995-02-01

    The octagonal and dodecagonal quaislattices were generated by means of the grid method. Monte Carlo simulation and cluster counting procedure were used for numerical determination of the site and bond percolation thresholds. Two types of connectivity called ferromagnetic and chemical were studied. The estimated site percolation thresholds are 0.5435… and 0.585… for octagonal lattice and 0.617… and 0.628… for dodecagonal lattice respectively. The obtained spanning fraction curves (for site percolation) seem to approach the 50% value at the percolation threshold. The site percolation conductivity for these lattices was studied by means of a transfer-matrix approach. The critical behavior was found to be the same as for the periodic lattices.

  14. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    SciTech Connect

    Thiyagarajan, Magesh; Thompson, Shane

    2012-04-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then

  15. Percolation threshold determination of sputtered silver films using Stokes parameters and in situ conductance measurements.

    PubMed

    Hafezian, Soroush; Baloukas, Bill; Martinu, Ludvik

    2014-08-20

    This work presents a straightforward approach to determine the percolation threshold of silver thin films deposited by magnetron sputtering on various oxide layers at room temperature. The proposed method is based on the observation of the coupling of p-polarized light with local surface plasmons. By measuring the first Stokes parameter in real time, one can determine the moment at which the nano-islands of silver begin to coalesce into a continuous film. We confirm the results by in situ and ex situ conductance measurements. The method is then used to assess the percolation threshold on different oxide seed layers such as ZnSnO, ZnO, TiO2, and SiO2. PMID:25321107

  16. Cat hindlimb motoneurons during locomotion. I. Destination, axonal conduction velocity, and recruitment threshold.

    PubMed

    Hoffer, J A; Loeb, G E; Marks, W B; O'Donovan, M J; Pratt, C A; Sugano, N

    1987-02-01

    Fine flexible wire microelectrodes chronically implanted in the fifth lumbar ventral root (L5 VR) of 17 cats rendered stable records of the natural discharge patterns of 164 individual axons during locomotion on a treadmill. Fifty-one out of 164 axons were identified as motoneurons projecting to the anterior thigh muscle group. For these axons, the centrifugal propagation of action potentials was demonstrated by the technique of spike-triggered averaging using signals recorded from cuff electrodes implanted around the femoral nerve. The axonal conduction velocity was measured from the femoral nerve cuff records. For 43/51 motoneurons, the corresponding target muscle was identified by spike-triggered averaging of signals recorded from bipolar EMG electrodes implanted in each of the anterior thigh muscles: vastus intermedius, medialis and lateralis, sartorius anterior and medialis, and rectus femoris. For 32/51 motoneurons, the recruitment threshold during locomotion was determined from the mean value of the rectified digitally smoothed EMG of the target muscle measured at the time when the motoneuron fired its first spike for each step. The recruitment threshold of every motoneuron was relatively constant for a given speed of walking, but for some units there were small systematic variations as a function of treadmill speed (range: 0.1-1.3 m/s). Recruitment thresholds were standardized with respect to the mean value of peak EMG activity of the target muscle during 16 s of walking at 0.5 m/s. For 28/51 motoneurons recorded in nine cats, recruitment thresholds (range: 3-93% of peak target muscle EMG) were linearly correlated (r = 0.51, P less than 0.02) to axonal conduction velocities (range: 57-117 m/s). In addition, for seven recorded pairs of motoneurons that projected to the same muscle in the same cat, the recruitment thresholds were ordered by relative conduction velocities. Taken together, these results are consistent with the notion that, in normal cat

  17. Threshold responses of Blackside Dace (Chrosomus cumberlandensis) and Kentucky Arrow Darter (Etheostoma spilotum) to stream conductivity

    USGS Publications Warehouse

    Hitt, Nathaniel P.; Floyd, Michael; Compton, Michael; McDonald, Kenneth

    2016-01-01

    Chrosomus cumberlandensis (Blackside Dace [BSD]) and Etheostoma spilotum (Kentucky Arrow Darter [KAD]) are fish species of conservation concern due to their fragmented distributions, their low population sizes, and threats from anthropogenic stressors in the southeastern United States. We evaluated the relationship between fish abundance and stream conductivity, an index of environmental quality and potential physiological stressor. We modeled occurrence and abundance of KAD in the upper Kentucky River basin (208 samples) and BSD in the upper Cumberland River basin (294 samples) for sites sampled between 2003 and 2013. Segmented regression indicated a conductivity change-point for BSD abundance at 343 μS/cm (95% CI: 123–563 μS/cm) and for KAD abundance at 261 μS/cm (95% CI: 151–370 μS/cm). In both cases, abundances were negligible above estimated conductivity change-points. Post-hoc randomizations accounted for variance in estimated change points due to unequal sample sizes across the conductivity gradients. Boosted regression-tree analysis indicated stronger effects of conductivity than other natural and anthropogenic factors known to influence stream fishes. Boosted regression trees further indicated threshold responses of BSD and KAD occurrence to conductivity gradients in support of segmented regression results. We suggest that the observed conductivity relationship may indicate energetic limitations for insectivorous fishes due to changes in benthic macroinvertebrate community composition.

  18. Fluid stimulation elicits hearing in the absence of air and bone conduction-An animal study.

    PubMed

    Perez, Ronen; Adelman, Cahtia; Sohmer, Haim

    2016-04-01

    Conclusion Cochlea can be directly excited by fluid (soft-tissue) stimulation. Objective To determine whether there is no difference in auditory-nerve-brainstem evoked response (ABR) thresholds to fluid stimulation between normal and animal models of post radical-mastoidectomy, as seen in a previous human study. Background It has been shown in humans that hearing can be elicited with stimulation to fluid in the external auditory meatus (EAM), and radical-mastoidectomy cavity. These groups differed in age, initial hearing, and drilling exposure. To overcome this difference, experiments were conducted in sand-rats, first intact, and after inducing a radical-mastoidectomy. Methods The EAM of five sand-rats was filled with 0.3 ml saline. ABR thresholds were determined in response to vibratory stimulation by a clinical bone-vibrator with a plastic rod, applied to the saline in the EAM. Then the tympanic membrane was removed, and malleus dislocated (radical-mastoidectomy model). The cavity was filled with 0.45 ml saline and the ABR threshold was determined in response to vibratory stimulation to the cavity fluid. Results There was no difference in ABR fluid thresholds to EAM and mastoidectomy cavity stimulation. Air-conduction stimulation from the bone-vibrator was not involved (conductive loss due to fluid). Bone-conduction stimulation was not involved (large difference in acoustic impedance between fluid and bone). PMID:26824146

  19. Nocturnal stomatal conductance and ambient air quality standards for ozone

    NASA Astrophysics Data System (ADS)

    Musselman, Robert C.; Minnick, Tamera J.

    Vegetation response to ozone depends on ozone conductance into leaves and the defensive action inside the leaf. Ozone parameters currently used for air quality standards do not incorporate conductance or defensive components. Nighttime flux has often been ignored in ozone metrics relating to plant response, since ozone concentration and conductance are considered to be minimal at night. However, ozone concentration can remain relatively high at night, particularly in mountainous areas. Although conductance is lower at night than during the day for most plants, nocturnal conductance can result in considerable ozone flux into plants. Further, plants can be more susceptible to ozone exposure at night than during the daytime, a result of lower plant defenses at night. Any ozone metric used to relate air quality to plant response should use a 24 h ozone exposure period to include the nighttime exposures. It should also incorporate plant defensive mechanisms or their surrogate.

  20. Graded boosting of synaptic signals by low-threshold voltage-activated calcium conductance.

    PubMed

    Carbó Tano, Martín; Vilarchao, María Eugenia; Szczupak, Lidia

    2015-07-01

    Low-threshold voltage-activated calcium conductances (LT-VACCs) play a substantial role in shaping the electrophysiological attributes of neurites. We have investigated how these conductances affect synaptic integration in a premotor nonspiking (NS) neuron of the leech nervous system. These cells exhibit an extensive neuritic tree, do not fire Na(+)-dependent spikes, but express an LT-VACC that was sensitive to 250 μM Ni(2+) and 100 μM NNC 55-0396 (NNC). NS neurons responded to excitation of mechanosensory pressure neurons with depolarizing responses for which amplitude was a linear function of the presynaptic firing frequency. NNC decreased these synaptic responses and abolished the concomitant widespread Ca(2+) signals. Coherent with the interpretation that the LT-VACC amplified signals at the postsynaptic level, this conductance also amplified the responses of NS neurons to direct injection of sinusoidal current. Synaptic amplification thus is achieved via a positive feedback in which depolarizing signals activate an LT-VACC that, in turn, boosts these signals. The wide distribution of LT-VACC could support the active propagation of depolarizing signals, turning the complex NS neuritic tree into a relatively compact electrical compartment. PMID:25972583

  1. Threshold response of mesophyll CO2 conductance to leaf hydraulics in highly transpiring hybrid poplar clones exposed to soil drying

    PubMed Central

    Pepin, Steeve

    2014-01-01

    Mesophyll conductance (g m) has been shown to impose significant limitations to net CO2 assimilation (A) in various species during water stress. Net CO2 assimilation is also limited by stomatal conductance to water (g sw), both having been shown to co-vary with leaf hydraulic conductance (K leaf). Lately, several studies have suggested a close functional link between K leaf, g sw, and g m. However, such relationships could only be circumstantial since a recent study has shown that the response of g m to drought could merely be an artefactual consequence of a reduced intercellular CO2 mole fraction (C i). Experiments were conducted on 8-week-old hybrid poplar cuttings to determine the relationship between K leaf, g sw, and g m in clones of contrasting drought tolerance. It was hypothesized that changes in g sw and K leaf in response to drought would not impact on g m over most of its range. The results show that K leaf decreased in concert with g sw as drought proceeded, whereas g m measured at a normalized C i remained relatively constant up to a g sw threshold of ~0.15mol m–2 s–1. This delayed g m response prevented a substantial decline in A at the early stage of the drought, thereby enhancing water use efficiency. Reducing the stomatal limitation of droughted plants by diminishing the ambient CO2 concentration of the air did not modify g m or K leaf. The relationship between gas exchange and leaf hydraulics was similar in both drought-tolerant and drought-sensitive clones despite their contrasting vulnerability to stem cavitation and stomatal response to soil drying. The results support the hypothesis of a partial hydraulic isolation of the mesophyll from the main transpiration pathway. PMID:24368507

  2. LASER PLASMA: Experimental confirmation of the erosion origin of pulsed low-threshold surface optical breakdown of air

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ya; Chumakou, A. N.; Chivel', Yu A.

    1988-08-01

    Nanosecond kinetic spectroscopy techniques were used to identify the erosion origin of pulsed low-threshold surface optical breakdown of air as a result of interaction of microsecond neodymium and CO2 laser pulses with some metals (indium, lead).

  3. A Conductivity and Dielectric Constant of Systems Near the Percolation Threshold.

    NASA Astrophysics Data System (ADS)

    Song, Yi.

    The ac conductivity and dielectric constant of macroscopically inhomogeneous systems near the percolation threshold vary as a power of the frequency, with (sigma) (PROPORTIONAL) (omega)('x), and (epsilon) (PROPORTIONAL) (omega)('-y). The two critical exponents x and y should satisfy a general scaling relation x + y = 1, if (sigma) and (epsilon) both obey scaling forms that have a single characteristic time scale. Two different percolation systems were studied experi- mentally in order to find the critical exponents x and y. The ac con- ductance and capacitance of these two systems were measured in the frequency range from 10 Hz to 13 MHz. The ac conductivity exponent x and ac dielectric constant exponent y from a three dimensional randomly mixed carbon-teflon system were found to be 0.86 (+OR-) 0.06 and 0.12 (+OR-) 0.04, respectively. The same critical exponents x and y were obtained on a planar chromium film system. Their values were x = 0.98 (+OR-) 0.09 and y = 0.08 (+OR-) 0.04. In order to complete the study, the dc conductivity exponent t and dc dielectric constant exponent s of these systems were also measured. They were in good agreement with well-established values. Two important mechanisms are responsible for the power law dependence of the ac conductivity and dielectric constant of systems near the percolation threshold. They are the interaction between percolation clusters and the fractal nature of these clus- ters. Two independent models based on these two mechanisms separately, namely the intercluster polarization (IP) model and the anomalous diffusion (AD) model, both predict power law behavior for (sigma) and (epsilon). The IP model predicts x (DBLTURN) 0.72 and y (DBLTURN) 0.28 for three dimensional (3D) systems and x = y = 0.5 for two dimensional (2D) systems; while the AD model predicts x (DBLTURN) 0.58 and y (DBLTURN) 0.42 for 3D systems and x (DBLTURN) 0.33 and y (DBLTURN) 0.67 for 2D systems. The experimental results of the ac conductivity

  4. Air cushion vehicle conductive/semiconductive flexible skirt, and method

    NASA Astrophysics Data System (ADS)

    Cavenagh, Richard A.; Dyke, Raymond W.

    1990-03-01

    Discussed here is a method for dissipating static electrical energy from air cushion vehicles when operating more particularly in cold, low humidity environments, which method involves fabricating the skirt assembly from a flexible sheet material of at least semiconductive character, which will provide a suitable dissipating grounding pathway to discharge potential static electrical energy generated during the aforesaid operation. The method includes using a coated flexible fabric material having at least one of its opposite surfaces coated with an elastomeric abrasion-resistant material, and embedding a plurality of electrically conductive flexible strands at least partially within said flexible fabric material, or alternatively embedding electrically conductive particles or fibers in a generally uniformly manner throughout a forming of its elastomeric composition. The invention also is directed specifically to/on an air cushion vehicle skirt component comprised of electrically conductive composite flexible sheet material having sufficient conductive characteristics to provide a near constant dissipation grounding pathway from said vehicle for any substantial build up of generated static electrical energy, more particularly when the air cushion vehicle is operating in cold, low humidity environments.

  5. Vibrotactile threshold for hairy skin and its transformation into equivalent bone-conduction loss for the mastoid.

    PubMed

    Lamoré, P J

    1984-01-01

    Vibrotactile thresholds for the glabrous skin of the hand and for the hairy skin of the arm are investigated as a function of frequency in the range from 40 to 2 000 Hz, using a heavy vibrator. These thresholds are expressed as equivalent bone-conduction loss and compared with vibrotactile thresholds determined with bone vibrators on the arm and mastoid for normally hearing and severely hearing-impaired subjects. The results are used to predict the vibrotactile threshold of the hairy skin of the mastoid under conditions of severe hearing impairment and deafness. The frequency characteristics of a number of vibrators are discussed with respect to their suitability for skin stimulation. PMID:6517747

  6. Instability of an interface between air and a low conducting liquid subjected to charge injection

    NASA Astrophysics Data System (ADS)

    Chicón, Rafael; Pérez, Alberto T.

    2006-10-01

    We study the linear stability of an interface between air and a low conducting liquid in the presence of unipolar injection of charge. As a consequence of charge injection, a volume charge density builds up in the air gap and a surface charge density on the interface. Above a certain voltage threshold the electrical stresses may destabilize the interface, giving rise to a characteristic cell pattern known as rose-window instability. Contrary to what occurs in the classical volume electrohydrodynamic instability in insulating liquids, the typical cell size is several times larger than the liquid depth. We analyze the linear stability through the usual procedure of decomposing an arbitrary perturbation into normal modes. The resulting homogeneous linear system of ordinary differential equations is solved using a commercial software package. Finally, an analytical method is developed that provides a solution valid in the limit of small wavenumbers.

  7. The optical breakdown threshold of air on a polished metal surface for radiation at lambda=10.6 microns

    NASA Astrophysics Data System (ADS)

    Arkhipov, Iu. V.; Belashkov, I. N.; Datskevich, N. P.; Egorov, V. N.; Iziumov, A. F.

    1986-01-01

    Threshold conditions for the formation of a plasma due to optical breakdown of air on the polished surfaces of Al, Co, Mi, and W samples have been investigated experimentally. The optical breakdown was initiated by pulsed radiation from two CO2 lasers having pulse powers 0.5 and 1.0 kJ, respectively. The thresholds for the formation of the plasma were determined for two exposure spots of o/14 sq mm and 46 sq cm, respectively. A metallographic study was carried out in order to identify the specific types of defects corresponding to the lowest optical breakdown thresholds. Before-and-after photographs of the metal surfaces are provided.

  8. A continuum model with a percolation threshold and tunneling-assisted interfacial conductivity for carbon nanotube-based nanocomposites

    SciTech Connect

    Wang, Yang; Weng, George J.; Meguid, Shaker A.; Hamouda, Abdel Magid

    2014-05-21

    A continuum model that possesses several desirable features of the electrical conduction process in carbon-nanotube (CNT) based nanocomposites is developed. Three basic elements are included: (i) percolation threshold, (ii) interface effects, and (iii) tunneling-assisted interfacial conductivity. We approach the first one through the selection of an effective medium theory. We approach the second one by the introduction of a diminishing layer of interface with an interfacial conductivity to build a 'thinly coated' CNT. The third one is introduced through the observation that interface conductivity can be enhanced by electron tunneling which in turn can be facilitated with the formation of CNT networks. We treat this last issue in a continuum fashion by taking the network formation as a statistical process that can be represented by Cauchy's probability density function. The outcome is a simple and yet widely useful model that can simultaneously capture all these fundamental characteristics. It is demonstrated that, without considering the interface effect, the predicted conductivity would be too high, and that, without accounting for the additional contribution from the tunneling-assisted interfacial conductivity, the predicted conductivity beyond the percolation threshold would be too low. It is with the consideration of all three elements that the theory can fully account for the experimentally measured data. We further use the developed model to demonstrate that, despite the anisotropy of the intrinsic CNT conductivity, it is its axial component along the CNT direction that dominates the overall conductivity. This theory is also proved that, even with a totally insulating matrix, it is still capable of delivering non-zero conductivity beyond the percolation threshold.

  9. 49 CFR 232.217 - Train brake tests conducted using yard air.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Train brake tests conducted using yard air. 232... Train brake tests conducted using yard air. (a) When a train air brake system is tested from a yard air... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The...

  10. 49 CFR 232.217 - Train brake tests conducted using yard air.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Train brake tests conducted using yard air. 232... Train brake tests conducted using yard air. (a) When a train air brake system is tested from a yard air... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The...

  11. 49 CFR 232.217 - Train brake tests conducted using yard air.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Train brake tests conducted using yard air. 232... Train brake tests conducted using yard air. (a) When a train air brake system is tested from a yard air... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The...

  12. 49 CFR 232.217 - Train brake tests conducted using yard air.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Train brake tests conducted using yard air. 232... Train brake tests conducted using yard air. (a) When a train air brake system is tested from a yard air... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The...

  13. 49 CFR 232.217 - Train brake tests conducted using yard air.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Train brake tests conducted using yard air. 232... Train brake tests conducted using yard air. (a) When a train air brake system is tested from a yard air... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The...

  14. Styrene-Butadiene Co-Polymer Based Highly Conducting and Flexible Polymer Composite Film with Low Percolation Threshold

    NASA Astrophysics Data System (ADS)

    Mathew, Anisha Mary; Neena, P.

    2011-10-01

    Conducting polymer composites are finding novel applications in various fields especially in device technology. In this work an effort has been made to synthesize polyaniline-synthetic rubber (Styrene-butadiene rubber) composite via ex-situ technique and its electrochemical properties are investigated. Highly conducting emeraldine form of polyaniline (20 S/cm) is prepared by the oxidative polymerization of aniline in aqueous acidic (CSA) media using ammonium peroxydisulfate as oxidizing agent. These composite films are characterized by UV-Visible spectroscopy to investigate their optical properties. The dc conductivity studies indicate that these composite films show extremely low percolation threshold.

  15. Experimental establishment of the erosion nature of the pulsed low-threshold optical breakdown of air near the surface

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ia.; Chumakov, A. N.; Chivel', Iu. A.

    1988-08-01

    Nanosecond kinetic spectroscopy methods are used to establish the erosion nature of the pulsed low-threshold optical breakdown of air near the surface upon exposure of certain metals (indium, lead) to microsecond neodymium and CO2 laser radiation. It is shown that this optical breakdown of air by CO2 laser radiation is accompanied by the formation of a plasma spectrum which is optically thin in the visible range.

  16. In-air hearing of a diving duck: A comparison of psychoacoustic and auditory brainstem response thresholds.

    PubMed

    Crowell, Sara E; Wells-Berlin, Alicia M; Therrien, Ronald E; Yannuzzi, Sally E; Carr, Catherine E

    2016-05-01

    Auditory sensitivity was measured in a species of diving duck that is not often kept in captivity, the lesser scaup. Behavioral (psychoacoustics) and electrophysiological [the auditory brainstem response (ABR)] methods were used to measure in-air auditory sensitivity, and the resulting audiograms were compared. Both approaches yielded audiograms with similar U-shapes and regions of greatest sensitivity (2000-3000 Hz). However, ABR thresholds were higher than psychoacoustic thresholds at all frequencies. This difference was least at the highest frequency tested using both methods (5700 Hz) and greatest at 1000 Hz, where the ABR threshold was 26.8 dB higher than the behavioral measure of threshold. This difference is commonly reported in studies involving many different species. These results highlight the usefulness of each method, depending on the testing conditions and availability of the animals. PMID:27250191

  17. Comparison of the after-effects of impulse conduction on threshold at nodes of Ranvier along single frog sciatic axons.

    PubMed Central

    Carley, L R; Raymond, S A

    1987-01-01

    1. Single axons were teased from the distal end of whole frog sciatic nerve and impulses were recorded with a suction electrode. The whole nerve trunk was stimulated using a gross electrode that was slowly moved for several centimetres along the length of the nerve. The threshold for initiation of an action potential showed periodic minima which were interpreted as the location of nodes of Ranvier. 2. Internodal distances were uniform along individual fibres but differed among fibres having matching conduction velocities, suggesting that other individuating characteristics are also important in determining the spacing of nodes. 3. A standard protocol was used to measure the activity dependence of threshold. Nodes along any given fibre were found to be alike in the dependence of threshold on impulse activity. Both the superexcitable phase and the depressed phase of the after-effects of impulse activity were similar for successive nodes. This suggests that the activity dependence of an unbranched length of axon can be well characterized by looking at any one of its nodes. 4. Comparison of nodes from different axons showed large variations in activity dependence. Depressibility, denoting the relative tendency of an axon to show depression, was quantified either as the initial rate of rise in threshold (percentage increase/min) following the onset of repetitive stimulation or as the total rise in threshold (percentage increase) after 5 min of exposure to a standardized rate of repetitive stimulation. By either measure depressibility differed among axons more than it differed among nodes from a single axon. 5. Superexcitability following single impulses was measured in the absence of depression. Axons exhibiting a larger decrease in threshold during the superexcitable phase also tended to show larger depressions relative to other axons when stimulated at a given rate. 6. There was little correlation between conduction velocity and the magnitude of either the depressed

  18. Prevalence of permanent threshold shifts in the United States Air Force hearing conservation program by career field, 2005-2011.

    PubMed

    Lloyd Soderlund, Laurel; McKenna, Elizabeth A; Tastad, Katie; Paul, Marika

    2016-01-01

    The purpose of this study was to describe changes in hearing, using the permanent threshold shift metric, among United States Air Force servicemembers, including active duty, Reserve and Air National Guard components, for demographics, job categories, and career fields. In the United States Air Force, only servicemembers who are occupationally exposed routinely to hazardous noise are monitored. Audiogram records and demographic variables were analyzed for servicemembers from 2005-2011 using data from the Department of Defense system that captures occupational hearing tests worldwide. Results suggest that occupational hearing loss was larger in males than females, in officers than enlisted populations, and in Reserve and Air National Guard than in active duty. Compared to similar civilian career fields, active duty has lower prevalence rates for occupational hearing loss overall, although Reserve and Air National Guard prevalence rates were more similar to the civilian reported rates. The proportion of personnel with permanent threshold shifts varied between 4.6-16.7% within active duty career fields, which includes 76% of the population for study timeframe. Permanent threshold shift was larger in small job categories, and in jobs that are not considered exposed to hazardous noise routinely which is comparative with results from civilian data analysis of occupational hearing loss. Further investigation into testing practices for Air Force specific groups, use of the system for nonoccupational hearing testing, and challenges to follow-up compliance is warranted. Increased surveillance procedures for occupational hearing loss are needed to address concerns on the prevalence of servicemember hearing loss, the role of recreational and lifestyle factors to contribute the high reported hearing loss prevalence of veterans compared to nonveterans. PMID:26720128

  19. Short derivation of the influence of particle size ratio on the conductivity threshold in binary aggregates

    NASA Astrophysics Data System (ADS)

    Janzen, Jay

    1980-04-01

    A model developed by R.P. Kusy for predicting the composition at which the sudden onset of conductivity occurs in polymer/metal powder compacts is shown to yield quantitative results practically equivalent to those given by a previously published solution to the same problem. Significant differences nevertheless exist in the two theoretical developments leading to the concurring results; both approaches are appraised with reference to these differences.

  20. Alignment of carbon iron into polydimethylsiloxane to create conductive composite with low percolation threshold and high piezoresistivity

    NASA Astrophysics Data System (ADS)

    Dong, Shuai; Wang, R.; Wang, Xiaojie

    2016-04-01

    With the development of soft materials for applications in flexible tactile sensors, metal particles/insulated polymer composites have been studied for many years. This article proposes a method to prepare carbon iron particles (CIPs)/polydimethylsiloxane (PDMS) conductive composite with low percolation threshold and highly piezoresistive stain sensitivity. CIPs-PDMS composites with various filler volume fraction were cured under a magnetic field over 1.0 T to create chain-like structure resulting in anisotropy of conductive materials. The electrical resistivity for the longitudinal direction were measured as a function of filler volume fraction to understand the electrical percolation behavior. In this study, the percolation threshold of CIPs-PDMS composite cured under a magnetic field can be as low as 0.1 vol.%, which is much less than most of those studies in particulate composites. Meanwhile, the effects of compressive strain on the electrical properties of CIPs-PDMS composites were also investigated. The strain sensitivity depends on filler volume fraction and decreases with the increasing of compressive strain. It has been found that the composites containing a small amount of CI particles curing under a magnetic field exhibit a high strain sensitivity of over 150. The microstructures were measured by using a scanning electron microscope (SEM), and the results were also reported in this paper.

  1. Particle Arrangement Design for Predicting the Percolation Threshold of Silver/Epoxy Composite for Electrically Conductive Adhesive Application

    NASA Astrophysics Data System (ADS)

    Zulkarnain, M.; Husaini, Muhammad; Mariatti, M.; Azid, I. A.

    2015-11-01

    The early use of electrically conductive adhesives (ECAs) provided an alternative to solder because of their several advantages, such as good electrical conductivity, low cost, extendability to fine pitch of interconnecting material and environmental friendliness. According to previous works, an optimal particle volume fraction became a major objective of many researchers in order to obtain highly conductive ECAs, realizing that the need for transitions from an insulator to a conductor is controlled by the geometric arrangement of particles. In the current study, particle arrangement models of ECAs are developed by establishing the effects of van der Waals' attraction energy and particle motion, which act as a kind of particle interaction to generate a conducting structure. The methodology is divided into three major parts: the formulation of a particle arrangement technique, and numerical and experimental studies. The formulation of particle arrangement is developed in an epoxy colloidal system. During verification, the particle arrangement model is validated by the theoretical fractal dimension and guided by a morphological study of the experimental assessments. The model was simulated through representative volume elements with the volume fraction factor, which was set in the range of 2-8 vol.%, while electrical conductivity was an observed parameter. The numerical results showed good agreement with the experiments in which the percolation threshold occurred between 4 and 6% of the volume of filler loading.

  2. Influence of the angular scattering of electrons on the runaway threshold in air

    NASA Astrophysics Data System (ADS)

    Chanrion, O.; Bonaventura, Z.; Bourdon, A.; Neubert, T.

    2016-04-01

    The runaway electron mechanism is of great importance for the understanding of the generation of x- and gamma rays in atmospheric discharges. In 1991, terrestrial gamma-ray flashes (TGFs) were discovered by the Compton Gamma-Ray Observatory. Those emissions are bremsstrahlung from high energy electrons that run away in electric fields associated with thunderstorms. In this paper, we discuss the runaway threshold definition with a particular interest in the influence of the angular scattering for electron energy close to the threshold. In order to understand the mechanism of runaway, we compare the outcome of different Fokker-Planck and Monte Carlo models with increasing complexity in the description of the scattering. The results show that the inclusion of the stochastic nature of collisions smooths the probability to run away around the threshold. Furthermore, we observe that a significant number of electrons diffuse out of the runaway regime when we take into account the diffusion in angle due to the scattering. Those results suggest using a runaway threshold energy based on the Fokker-Planck model assuming the angular equilibrium that is 1.6 to 1.8 times higher than the one proposed by [1, 2], depending on the magnitude of the ambient electric field. The threshold also is found to be 5 to 26 times higher than the one assuming forward scattering. We give a fitted formula for the threshold field valid over a large range of electric fields. Furthermore, we have shown that the assumption of forward scattering is not valid below 1 MeV where the runaway threshold usually is defined. These results are important for the thermal runaway and the runaway electron avalanche discharge mechanisms suggested to participate in the TGF generation.

  3. A Conductivity Device for Measuring Sulfur Dioxide in the Air

    ERIC Educational Resources Information Center

    Craig, James C.

    1972-01-01

    Described is a general electroconductivity device enabling students to determine sulfur dioxide concentration in a particular location, hopefully leading to a deeper understanding of the problem of air pollution. (DF)

  4. Threshold velocities for input of soil particles into the air by desert soils

    SciTech Connect

    Gillette, D.A.; Adams, J.; Endo, A.; Smith, D.; Kihl, R.

    1980-10-20

    Desert soils mostly from the Mojave Desert were tested for threshold friction velocity (the friction velocity above which soil erosion takes place) with an open-bottomed portable wind tunnel. Several geomorphological settings were chosen to be representative of much of the surface of the Mojave Desert, for example, playas, alluvial fans, and aeolian features. Variables which increase threshold velocity are decreasing proportion of sand, increasing size of dry aggregates of the soil, and increasing fraction of the soil mass larger than 1 mm. Threshold velocity increases with different types of soil surfaces in the following order: disturbed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavement (alluvial deposits). 21 references, 5 figures, 6 tables.

  5. Between-airport heterogeneity in air toxics emissions associated with individual cancer risk thresholds and population risks

    PubMed Central

    2009-01-01

    Background Airports represent a complex source type of increasing importance contributing to air toxics risks. Comprehensive atmospheric dispersion models are beyond the scope of many applications, so it would be valuable to rapidly but accurately characterize the risk-relevant exposure implications of emissions at an airport. Methods In this study, we apply a high resolution atmospheric dispersion model (AERMOD) to 32 airports across the United States, focusing on benzene, 1,3-butadiene, and benzo [a]pyrene. We estimate the emission rates required at these airports to exceed a 10-6 lifetime cancer risk for the maximally exposed individual (emission thresholds) and estimate the total population risk at these emission rates. Results The emission thresholds vary by two orders of magnitude across airports, with variability predicted by proximity of populations to the airport and mixing height (R2 = 0.74–0.75 across pollutants). At these emission thresholds, the population risk within 50 km of the airport varies by two orders of magnitude across airports, driven by substantial heterogeneity in total population exposure per unit emissions that is related to population density and uncorrelated with emission thresholds. Conclusion Our findings indicate that site characteristics can be used to accurately predict maximum individual risk and total population risk at a given level of emissions, but that optimizing on one endpoint will be non-optimal for the other. PMID:19426510

  6. A comparison of nerve conduction velocities and current perception thresholds as correlates of clinical severity of diabetic sensory neuropathy.

    PubMed Central

    Rendell, M S; Katims, J J; Richter, R; Rowland, F

    1989-01-01

    Nerve conduction velocities (NCVs) are the standard measurements used to confirm the presence or absence of diabetic neuropathy. NCVs were contrasted with the newer technique of measurement of alternating current perception thresholds (CPTs) in assessing the quantitative level of correlation with severity of diabetic sensory neuropathy. A very detailed, scored neurological history (symptoms) and physical examination, emphasising sensory assessment, was conducted on 71 individuals with diabetic neuropathy of varying degrees of severity. Sensory and motor NCVs and CPTs at 5, 250, and 2000 Hz of the upper and lower extremities were determined for these individuals. In addition, vibration thresholds (VTs) were measured as a third modality. Twenty eight individuals underwent repeated evaluations at 2, 6, 10 and 12 months after the initial procedures. Using the results of 169 complete evaluations, correlations were determined between physical scores (PS) and symptoms scores (SS) and NCVs. NCV correlations with the SS were weaker than with the PS. The strongest of the correlations were found between the PS and motor NCVs of the median nerve (rho = 0.29) and the tibial nerve (rho = 0.38). Normal NCVs were present in the face of very significant historical and physical abnormality. Correlations of the SS and PS with both VTs and CPTs were higher than with the NCVs. CPTs proved the more effective as predictors of both symptomatic and physical impairment. NCVs appear to lack the resolving power necessary to evaluate subtle differences in clinical state of diabetic sensory neuropathy. The supplementary use of current perception testing may improve the quantitative assessment of this condition. PMID:2738593

  7. Ground level measurements of air conductivities under Florida thunderstorms

    NASA Technical Reports Server (NTRS)

    Blakeslee, Richard J.; Krider, E. P.

    1992-01-01

    Values of the positive and negative polar conductivities under summer thunderstorms in Florida are highly variable and exhibit a significant electrode effect, but the total conductivity usually remains close to values found in fair weather, 0.4 to 1.8 x 10 exp -14 S/m. With these values a method proposed by Krider and Musser (1982) for estimating the total conductivity from changes in the slope of the electric field recovery following a lightning discharge will be extremely sensitive to small time variations in the local Maxwell current density and must be modified to include these effects.

  8. Effect of Bipolar Cuff Electrode Design on Block Thresholds in High-Frequency Electrical Neural Conduction Block

    PubMed Central

    Ackermann, D. Michael; Foldes, Emily L.; Bhadra, Niloy; Kilgore, Kevin L.

    2012-01-01

    Many medical conditions are characterized by undesired or pathological peripheral neurological activity. The local delivery of high-frequency alternating currents (HFAC) has been shown to be a fast acting and quickly reversible method of blocking neural conduction and may provide a treatment alternative for eliminating pathological neural activity in these conditions. This work represents the first formal study of electrode design for high-frequency nerve block, and demonstrates that the interpolar separation distance for a bipolar electrode influences the current amplitudes required to achieve conduction block in both computer simulations and mammalian whole nerve experiments. The minimal current required to achieve block is also dependent on the diameter of the fibers being blocked and the electrode–fiber distance. Single fiber simulations suggest that minimizing the block threshold can be achieved by maximizing both the bipolar activating function (by adjusting the bipolar electrode contact separation distance) and a synergistic addition of membrane sodium currents generated by each of the two bipolar electrode contacts. For a rat sciatic nerve, 1.0–2.0 mm represented the optimal interpolar distance for minimizing current delivery. PMID:19840914

  9. 78 FR 37164 - Revisions to the Air Emissions Reporting Requirements: Revisions to Lead (Pb) Reporting Threshold...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ... INFORMATION CONTACT section. \\1\\ As prescribed by the Tribal Authority Rule (63 FR 7253, February 12, 1998... substitute language for your requested changes. Describe any assumptions and provide any technical... Lead (73 FR 66964, November 12, 2008) and the associated Revisions to Lead Ambient Air...

  10. Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

    SciTech Connect

    Ma, H. J. Harsan E-mail: ariando@nus.edu.sg; Zeng, S. W.; Annadi, A.; Ariando E-mail: ariando@nus.edu.sg; Huang, Z.; Venkatesan, T.

    2015-08-15

    The two-dimensional electron gas (2DEG) formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO{sub 3} (LAO) and non-polar SrTiO{sub 3} (STO). Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La{sub 0.5}Sr{sub 0.5}TiO{sub 3} (LSTO) layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

  11. Percolation threshold of graphene nanosheets as conductive additives in Li4Ti5O12 anodes of Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Yu, Yang; Liu, Yusi; Huang, Zhen-Dong; He, Yan-Bing; Kim, Jang-Kyo

    2013-02-01

    Graphene nanosheets (GNSs) have been considered as potential conductive additives for electrodes in Li-ion batteries to replace the existing carbon black (CB). Graphene has exceptionally high aspect ratio and excellent electrical conductivity, enabling the formation of extensive conductive networks at a much lower content than CB. This paper reports the beneficial effects of GNSs with a low percolation threshold on electrochemical performance of Li4Ti5O12 (LTO) anodes. The experimental results show that the GNSs with a diameter of 46 μm and a thickness of 4.5 nm have a percolation threshold of 1.8 wt%. The prediction based on the interparticle distance concept gives a percolation threshold of 0.54 wt% for GNSs, which is almost an order of magnitude lower than that for CB particles. The substantially low percolation along with a high electrical conductivity of GNSs explains why the LTO anodes containing only 5 wt% GNSs deliver a much better rate capability than those with 15 wt% CB. However, a higher GNS content of 10 wt% results in re-stacking GNSs, deteriorating the diffusion of Li ions through the thickness of GNSs. The parametric study indicates that the percolation threshold of GNSs is inversely proportional to the aspect ratio of GNSs.Graphene nanosheets (GNSs) have been considered as potential conductive additives for electrodes in Li-ion batteries to replace the existing carbon black (CB). Graphene has exceptionally high aspect ratio and excellent electrical conductivity, enabling the formation of extensive conductive networks at a much lower content than CB. This paper reports the beneficial effects of GNSs with a low percolation threshold on electrochemical performance of Li4Ti5O12 (LTO) anodes. The experimental results show that the GNSs with a diameter of 46 μm and a thickness of 4.5 nm have a percolation threshold of 1.8 wt%. The prediction based on the interparticle distance concept gives a percolation threshold of 0.54 wt% for GNSs, which is almost

  12. Percolation threshold of graphene nanosheets as conductive additives in Li4Ti5O12 anodes of Li-ion batteries.

    PubMed

    Zhang, Biao; Yu, Yang; Liu, Yusi; Huang, Zhen-Dong; He, Yan-bing; Kim, Jang-Kyo

    2013-03-01

    Graphene nanosheets (GNSs) have been considered as potential conductive additives for electrodes in Li-ion batteries to replace the existing carbon black (CB). Graphene has exceptionally high aspect ratio and excellent electrical conductivity, enabling the formation of extensive conductive networks at a much lower content than CB. This paper reports the beneficial effects of GNSs with a low percolation threshold on electrochemical performance of Li(4)Ti(5)O(12) (LTO) anodes. The experimental results show that the GNSs with a diameter of 46 μm and a thickness of 4.5 nm have a percolation threshold of 1.8 wt%. The prediction based on the interparticle distance concept gives a percolation threshold of 0.54 wt% for GNSs, which is almost an order of magnitude lower than that for CB particles. The substantially low percolation along with a high electrical conductivity of GNSs explains why the LTO anodes containing only 5 wt% GNSs deliver a much better rate capability than those with 15 wt% CB. However, a higher GNS content of 10 wt% results in re-stacking GNSs, deteriorating the diffusion of Li ions through the thickness of GNSs. The parametric study indicates that the percolation threshold of GNSs is inversely proportional to the aspect ratio of GNSs. PMID:23381093

  13. Low power ovonic threshold switching characteristics of thin GeTe{sub 6} films using conductive atomic force microscopy

    SciTech Connect

    Manivannan, Anbarasu E-mail: ranjith@iith.ac.in; Sahu, Smriti; Myana, Santosh Kumar; Miriyala, Kumaraswamy; Ramadurai, Ranjith E-mail: ranjith@iith.ac.in

    2014-12-15

    Minimizing the dimensions of the electrode could directly impact the energy-efficient threshold switching and programming characteristics of phase change memory devices. A ∼12–15 nm AFM probe-tip was employed as one of the electrodes for a systematic study of threshold switching of as-deposited amorphous GeTe{sub 6} thin films. This configuration enables low power threshold switching with an extremely low steady state current in the on state of 6–8 nA. Analysis of over 48 different probe locations on the sample reveals a stable Ovonic threshold switching behavior at threshold voltage, V{sub TH} of 2.4 ± 0.5 V and the off state was retained below a holding voltage, V{sub H} of 0.6 ± 0.1 V. All these probe locations exhibit repeatable on-off transitions for more than 175 pulses at each location. Furthermore, by utilizing longer biasing voltages while scanning, a plausible nano-scale control over the phase change behavior from as-deposited amorphous to crystalline phase was studied.

  14. A stably enhanced transparent conductive graphene film obtained using an air-annealing method

    NASA Astrophysics Data System (ADS)

    Song, Xuefen; Wei, Dapeng; Sun, Tai; Yu, Leyong; Yang, Jun; Zhang, Yongna; Fang, Liang; Wei, Dacheng; Shi, Haofei; Du, Chunlei

    2016-08-01

    A simple and effective air-annealing technique was developed to stably improve both the electrical conductivity and light transmission of pristine graphene. After the graphene film was annealed in air at 250 °C for 80 min, the mobility and carrier concentration were both significantly enhanced, and the sheet resistance was greatly reduced with a decrease rate of ∼33%. Meanwhile, the transparency was also improved by more than 3%. The mechanism is carefully discussed. The reason might be that air-annealing conditions provide a suitable atmosphere to etch and remove amorphous carbons. More importantly, the enhanced transparent conductive properties of the air-annealed graphene films were extraordinarily stable, and remained almost unchanged for 100 days.

  15. Quantitative measurement of odor detection thresholds using an air dilution olfactometer, and association with genetic variants in a sample of diverse ancestry

    PubMed Central

    Cook, Gillian R.; Krithika, S; Edwards, Melissa; Kavanagh, Paula

    2014-01-01

    Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n-butanol Sensitivity Kit (IDES Canada Inc.), n-butanol odor thresholds were determined for 182 individuals of diverse ancestry (mean age: 20.4 ± 2.5 years; n = 128 female; n = 54 male). Threshold scores from repeat participants were used to calculate a test–retest reliability coefficient, which was statistically significant (r = 0.754, p < 0.001, n = 29), indicating that the Scentroid provides reliable estimates of odor thresholds. In addition, we performed a preliminary genetic analysis evaluating the potential association of n-butanol odor thresholds to six single-nucleotide polymorphisms (SNPs) putatively involved in general olfactory sensitivity (GOS). The results of multiple linear regression analysis revealed no significant association between the SNPs tested and threshold scores. However, our sample size was relatively small, and our study was only powered to identify genetic markers with strong effects on olfactory sensitivity. Overall, we find that the Scentroid provides reliable quantitative measures of odor detection threshold and is well suited for genetic studies of olfactory sensitivity. PMID:25392755

  16. 40 CFR 60.2141 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection? 60.2141 Section 60.2141 Protection of Environment... Compliance Requirements § 60.2141 By what date must I conduct the initial air pollution control device inspection? (a) The initial air pollution control device inspection must be conducted within 60 days...

  17. 40 CFR 60.2706 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection? 60.2706 Section 60.2706 Protection of Environment... Requirements § 60.2706 By what date must I conduct the initial air pollution control device inspection? (a) The initial air pollution control device inspection must be conducted within 60 days after installation of...

  18. 40 CFR 60.4895 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Compliance Requirements § 60.4895 By what date must I conduct annual air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution... following the previous annual air pollution control device inspection. (b) Within 10 operating...

  19. 40 CFR 60.4895 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Compliance Requirements § 60.4895 By what date must I conduct annual air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution... following the previous annual air pollution control device inspection. (b) Within 10 operating...

  20. 40 CFR 60.2141 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection? 60.2141 Section 60.2141 Protection of Environment... Compliance Requirements § 60.2141 By what date must I conduct the initial air pollution control device inspection? (a) The initial air pollution control device inspection must be conducted within 60 days...

  1. 40 CFR 60.4895 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Compliance Requirements § 60.4895 By what date must I conduct annual air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution... following the previous annual air pollution control device inspection. (b) Within 10 operating...

  2. 40 CFR 60.4895 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Compliance Requirements § 60.4895 By what date must I conduct annual air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution... following the previous annual air pollution control device inspection. (b) Within 10 operating...

  3. 21 CFR 874.3950 - Transcutaneous air conduction hearing aid system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3950... occluding the ear canal. The device consists of an air conduction hearing aid attached to a surgically... ear canal. (b) Classification. Class II (special controls). The special control for this device is...

  4. 21 CFR 874.3950 - Transcutaneous air conduction hearing aid system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3950... occluding the ear canal. The device consists of an air conduction hearing aid attached to a surgically... ear canal. (b) Classification. Class II (special controls). The special control for this device is...

  5. 21 CFR 874.3950 - Transcutaneous air conduction hearing aid system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3950... occluding the ear canal. The device consists of an air conduction hearing aid attached to a surgically... ear canal. (b) Classification. Class II (special controls). The special control for this device is...

  6. 21 CFR 874.3305 - Wireless air-conduction hearing aid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Wireless air-conduction hearing aid. 874.3305 Section 874.3305 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3305 Wireless...

  7. 21 CFR 874.3950 - Transcutaneous air conduction hearing aid system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3950... occluding the ear canal. The device consists of an air conduction hearing aid attached to a surgically... ear canal. (b) Classification. Class II (special controls). The special control for this device is...

  8. 21 CFR 874.3305 - Wireless air-conduction hearing aid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Wireless air-conduction hearing aid. 874.3305 Section 874.3305 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3305 Wireless...

  9. 21 CFR 874.3305 - Wireless air-conduction hearing aid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Wireless air-conduction hearing aid. 874.3305 Section 874.3305 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3305 Wireless...

  10. 21 CFR 874.3950 - Transcutaneous air conduction hearing aid system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3950... occluding the ear canal. The device consists of an air conduction hearing aid attached to a surgically... ear canal. (b) Classification. Class II (special controls). The special control for this device is...

  11. Air temperature thresholds to evaluate snow melting at the surface of Alpine glaciers by T-index models: the case study of Forni Glacier (Italy)

    NASA Astrophysics Data System (ADS)

    Senese, A.; Maugeri, M.; Vuillermoz, E.; Smiraglia, C.; Diolaiuti, G.

    2014-03-01

    The glacier melt conditions (i.e.: null surface temperature and positive energy budget) can be assessed by analyzing meteorological and energy data acquired by a supraglacial Automatic Weather Station (AWS). In the case this latter is not present the assessment of actual melting conditions and the evaluation of the melt amount is difficult and simple methods based on T-index (or degree days) models are generally applied. These models require the choice of a correct temperature threshold. In fact, melt does not necessarily occur at daily air temperatures higher than 273.15 K. In this paper, to detect the most indicative threshold witnessing melt conditions in the April-June period, we have analyzed air temperature data recorded from 2006 to 2012 by a supraglacial AWS set up at 2631 m a.s.l. on the ablation tongue of the Forni Glacier (Italian Alps), and by a weather station located outside the studied glacier (at Bormio, a village at 1225 m a.s.l.). Moreover we have evaluated the glacier energy budget and the Snow Water Equivalent (SWE) values during this time-frame. Then the snow ablation amount was estimated both from the surface energy balance (from supraglacial AWS data) and from T-index method (from Bormio data, applying the mean tropospheric lapse rate and varying the air temperature threshold) and the results were compared. We found that the mean tropospheric lapse rate permits a good and reliable reconstruction of glacier air temperatures and the major uncertainty in the computation of snow melt is driven by the choice of an appropriate temperature threshold. From our study using a 5.0 K lower threshold value (with respect to the largely applied 273.15 K) permits the most reliable reconstruction of glacier melt.

  12. Energy distribution and quantum yield for photoemission from air-contaminated gold surfaces under ultraviolet illumination close to the threshold

    NASA Astrophysics Data System (ADS)

    Hechenblaikner, Gerald; Ziegler, Tobias; Biswas, Indro; Seibel, Christoph; Schulze, Mathias; Brandt, Nico; Schöll, Achim; Bergner, Patrick; Reinert, Friedrich T.

    2012-06-01

    The kinetic energy distributions of photo-electrons emitted from gold surfaces under illumination by UV-light close to the threshold (photon energy in the order of the material work function) are measured and analyzed. Samples are prepared as chemically clean through Ar-ion sputtering and then exposed to atmosphere for variable durations before quantum yield measurements are performed after evacuation. During measurements, the bias voltage applied to the sample is varied and the resulting emission current measured. Taking the derivative of the current-voltage curve yields the energy distribution which is found to closely resemble the distribution of total energies derived by DuBridge for emission from a free electron gas. We investigate the dependence of distribution shape and width on electrode geometry and contaminant substances adsorbed from the atmosphere, in particular, to water and hydro-carbons. Emission efficiency increases initially during air exposure before diminishing to zero on a timescale of several hours, whilst subsequent annealing of the sample restores emissivity. A model fit function, in good quantitative agreement with the measured data, is introduced which accounts for the experiment-specific electrode geometry and an energy dependent transmission coefficient. The impact of large patch potential fields from contact potential drops between sample and sample holder is investigated. The total quantum yield is split into bulk and surface contributions which are tested for their sensitivity to light incidence angle and polarization. Our results are directly applicable to model parameters for the contact-free discharge system onboard the Laser Interferometer Space Antenna (LISA) Pathfinder spacecraft.

  13. Guidelines for Auditory Threshold Measurement for Significant Threshold Shift.

    PubMed

    Campbell, Kathleen; Hammill, Tanisha; Hoffer, Michael; Kil, Jonathan; Le Prell, Colleen

    2016-09-01

    The purpose of this article is to provide guidelines for determining a Significant Noise-Induced Threshold Shift in clinical trials involving human populations. The article reviews recommendations for the standards to be referenced for human subjects, equipment, test environment, and personnel. Additional guidelines for military populations are provided. Guidelines for the calibration of audiometers, sound booth noise levels, and immitance equipment are provided. In addition the guidance provides specific suggestions for the subjects history before study onset, and otoscopy.Test frequencies for threshold determination and methods of threshold determination are reviewed for both air conduction and bone conduction for both baseline testing and later determination of either a temporary (TTS) or permanent threshold shift (PTS). Once a Significant Noise-Induced Threshold Shift has been determined, subjects should be retested, conductive component should be ruled out or addressed, and the subject should be counseled or referred for additional medical evaluation. Guidance for reporting procedures and the computerized study database are described. Finally, experimental designs suggested for noise-induced otoprotection clinical trials are described. PMID:27518134

  14. Performance and cycle life of carbon- and conductive-based air electrodes for rechargeable Zn-air battery applications

    NASA Astrophysics Data System (ADS)

    Chellapandi Velraj, Samgopiraj

    The development of high-performance, cyclically stable bifunctional air electrodes are critical to the commercial deployment of rechargeable Zn-air batteries. The carbon material predominantly used as support material in the air electrodes due to its higher surface area and good electrical conductivity suffers from corrosion at high oxygen evolution overpotentials. This study addresses the carbon corrosion issues and suggests alternate materials to replace the carbon as support in the air electrode. In this study, Sm0.5Sr0.5CoO3-delta with good electrochemical performance and cyclic lifetime was identified as an alternative catalyst material to the commonly used La0.4Ca 0.6CoO3 catalyst for the carbon-based bifunctional electrodes. Also, a comprehensive study on the effects of catalyst morphology, testing conditions on the cycle life as well as the relevant degradation mechanism for the carbon-based electrode was conducted in this dissertation. The cyclic life of the carbon-based electrodes was strongly dependent on the carbon support material, while the degradation mechanisms were entirely controlled by the catalyst particle size/morphology. Some testing conditions like resting time and electrolyte concentration did not change the cyclic life or degradation mechanism of the carbon-based electrode. The current density used for cyclic testing was found to dictate the degradation mechanism leading to the electrode failure. An alternate way to circumvent the carbon corrosion is to replace the carbon support with a suitable electrically-conductive ceramic material. In this dissertation, LaNi0.9Mn0.1O3, LaNi 0.8Co0.2O3, and NiCo2O4 were synthesized and evaluated as prospective support materials due to their good electrical conductivity and their ability to act as the catalyst needed for the bifunctional electrode. The carbon-free electrodes had remarkably higher catalytic activity for oxygen evolution reaction (OER) when compared to the carbon-based electrode. However

  15. Structural changes and conductance thresholds in metal-free intrinsic SiO{sub x} resistive random access memory

    SciTech Connect

    Mehonic, Adnan E-mail: t.kenyon@ucl.ac.uk; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Kenyon, Anthony J. E-mail: t.kenyon@ucl.ac.uk; Fearn, Sarah; Chater, Richard; McPhail, David

    2015-03-28

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G{sub 0}, is a natural boundary between the high and low resistance states of our devices.

  16. Microstructure and DC electrical conductivity of spinel nickel ferrite sintered in air and nitrogen atmospheres

    SciTech Connect

    Liu, Baogang; Zhou, Kechao; Li, Zhiyou; Zhang, Dou; Zhang, Lei

    2010-11-15

    In recent years, the development of inert anode materials has gained considerable attention because such materials are capable of producing only environment-friendly O{sub 2} and saving energy during aluminum electrolysis. Nickel ferrite was prepared by a solid-state reaction as the inert anode in this study and its microstructures and direct current conductivities were analyzed in detail regarding the effects of different sintering atmospheres. A single-phase spinel structure was confirmed for all samples by X-ray powder diffraction. The grain sizes and the relative densities of the samples sintered in nitrogen increased by over 7 {mu}m and 10.8%, respectively, compared to those sintered in air. The direct current conductivities of the samples sintered in nitrogen showed a drastic increase compared to those sintered in air, believed to be due to the effects of increased Fe{sup 2+} ion concentration at octahedral sites and the increase of the relative density.

  17. 40 CFR 60.5215 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution control device used to comply with the emission limits, according to § 60.5220(c), no later than 12 months following the previous annual air pollution control...

  18. 40 CFR 60.5215 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution control device used to comply with the emission limits, according to § 60.5220(c), no later than 12 months following the previous annual air pollution control...

  19. 40 CFR 60.2151 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection? 60.2151 Section 60.2151 Protection of Environment... Compliance Requirements § 60.2151 By what date must I conduct the annual air pollution control device inspection? On an annual basis (no more than 12 months following the previous annual air pollution...

  20. 40 CFR 60.2151 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection? 60.2151 Section 60.2151 Protection of Environment... Compliance Requirements § 60.2151 By what date must I conduct the annual air pollution control device inspection? On an annual basis (no more than 12 months following the previous annual air pollution...

  1. 40 CFR 60.2716 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection? 60.2716 Section 60.2716 Protection of Environment... Requirements § 60.2716 By what date must I conduct the annual air pollution control device inspection? On an annual basis (no more than 12 months following the previous annual air pollution control...

  2. 40 CFR 60.5215 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution control device used to comply with the emission limits, according to § 60.5220(c), no later than 12 months following the previous annual air pollution control...

  3. 40 CFR 60.5215 - By what date must I conduct annual air pollution control device inspections and make any...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspections and make any necessary repairs? (a) You must conduct an annual inspection of each air pollution control device used to comply with the emission limits, according to § 60.5220(c), no later than 12 months following the previous annual air pollution control...

  4. Unconventional but tunable phase transition above the percolation threshold by two-layer conduction in electroless-deposited Au nanofeatures on silicon substrate

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Shin, Muncheol; Hwang, Seongpil; Jang, Jae-Won

    2015-12-01

    Previous research has shown that disorder, dislocation, and carrier concentration are the main factors impacting transitions in the traditional metal-insulator transition (MIT) and metal-semiconductor transition (MST). In this study, it is demonstrated that a non-traditional metal-semiconductor transition governed by two-layer conduction is possible by tuning the conducting channel of one layer of the two-layer conduction system. By means of the electroless deposition method we produced Au nanofeatures (AuNFs) on p-type silicon (p-Si) as the two-layer conduction system, controlling AuNF coverage (Au%) below and above the percolation threshold (p c). Even when the AuNF coverage percentage is larger than p c, the resistivities of the AuNFs on p-Si show MST as the temperature increases. To demonstrate this finding, we present a conduction model based upon two predominant parallel conductions by AuNFs and p-Si in the present paper. In the results, we show how the temperature of the MST (T MST) is tuned from 145 to 232 K as Au% is changed from 82.7 to 54.3%.

  5. Unconventional but tunable phase transition above the percolation threshold by two-layer conduction in electroless-deposited Au nanofeatures on silicon substrate

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Hwang, Seongpil; Jang, Jaw-Won

    Previous research has shown that disorder, dislocation, and carrier concentration are the main factors impacting transitions in the traditional metal-insulator transition (MIT) and metal-semiconductor transition (MST). In this study, it is demonstrated that a non-traditional MST governed by two-layer conduction is possible by tuning the conducting channel of one layer of the two-layer conduction system. By means of the electroless deposition method we produced Au nanofeatures (AuNFs) on p-type silicon (p-Si) as the two-layer conduction system, controlling AuNF coverage (Au%) below and above the percolation threshold (pc). Even when the AuNF coverage percentage is larger than pc, the resistivities of the AuNFs on p-Si show MST as the temperature increases. We present a conduction model based upon two predominant parallel conductions by AuNFs and p-Si in the present paper. In the results, we show how the temperature of the MST is tuned from 145 to 232 K as Au% is changed from 82.7 to 54.3%. Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (no. 2013K1A3A1A32035429 and 2015R1A1A1A05027681).

  6. 76 FR 34845 - Medical Devices; Ear, Nose, and Throat Devices; Classification of the Wireless Air-Conduction...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-15

    ... first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0;Federal Register / Vol. 76, No. 115... the Wireless Air-Conduction Hearing Aid AGENCY: Food and Drug Administration, HHS. ACTION: Final rule. SUMMARY: The Food and Drug Administration (FDA) is classifying the wireless air-conduction hearing...

  7. Aqueous and air-compatible fabrication of high-performance conductive textiles.

    PubMed

    Wang, Xiaolong; Yan, Casey; Hu, Hong; Zhou, Xuechang; Guo, Ruisheng; Liu, Xuqing; Xie, Zhuang; Huang, Zhifeng; Zheng, Zijian

    2014-08-01

    This paper describes a fully aqueous- and air-compatible chemical approach to preparing high-performance conductive textiles. In this method, the surfaces of textile materials are first modified with an aqueous solution of double-bond-containing silane molecules to form a surface-anchoring layer for subsequent in situ free-radical polymerization of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) in the air. Thin layers of poly-METAC (PMETAC) are therefore covalently grafted on top of the silane-modified textile surface. Cu- or Ni-coated textiles are finally fabricated by electroless deposition (ELD) onto the PMETAC-modified textiles. Parameters including polymerization time, temperature, and ELD conditions are studied to optimize the whole fabrication process. The as-made conductive textiles exhibit sheet resistance as low as 0.2 Ω sq(-1) , which makes them highly suitable for use as conductive wires and interconnects in flexible and wearable electronic devices. More importantly, the chemical method is fully compatible with the conventional "pad-dry-cure" fabrication process in the textile manufacturing industry, thus indicating that it is very promising for high-throughput and roll-to-roll fabrication of high-performance metal-coated conductive textiles in the future. PMID:24867263

  8. Patterning process and actuation in open air of micro-beam actuator based on conducting IPNs

    NASA Astrophysics Data System (ADS)

    Khaldi, Alexandre; Plesse, Cédric; Soyer, Caroline; Chevrot, Claude; Teyssié, Dominique; Vidal, Frédéric; Cattan, Eric

    2012-04-01

    We report on new method to obtain micrometric electroactive polymer actuators operating in air. High speed conducting Interpenetrating Polymer Network (IPN) microactuators are synthesized and fully characterized. The IPN architecture used in this work allows solving the interface and adhesion problems, which have been reported in the design of classical conducting polymer-based actuators. We demonstrated that it is possible to reduce the thickness of these actuators by a specific synthetic pathway. IPN host matrixes based on polyethylene oxide / polytetrahydrofurane have been shaped by hot pressing. Then, the resulting thin host matrixes (below 10 μm) are compatible with the microfabrication technologies. After interpenetration of poly(3,4-ethylenedioxythiophene) (PEDOT), these electroactive materials are micro-sized using dry etching process. Frequency responses and displacement have been characterized by scanning electronic microscopy. These conducting IPN microactuators can be considered as potential candidates in numerous low frequency applications, including micro-valves, micro-optical instrumentation and micro-robotics.

  9. NanoCapillary Network Proton Conducting Membranes for High Temperature Hydrogen/Air Fuel Cells

    SciTech Connect

    Pintauro, Peter

    2012-07-09

    The objective of this proposal is to fabricate and characterize a new class of NanoCapillary Network (NCN) proton conducting membranes for hydrogen/air fuel cells that operate under high temperature, low humidity conditions. The membranes will be intelligently designed, where a high density interconnecting 3-D network of nm-diameter electrospun proton conducting polymer fibers is embedded in an inert (uncharged) water/gas impermeable polymer matrix. The high density of fibers in the resulting mat and the high ion-exchange capacity of the fiber polymer will ensure high proton conductivity. To further enhance water retention, molecular silica will be added to the sulfonated polymer fibers. The uncharged matrix material will control water swelling of the high ion-exchange capacity proton conducting polymer fibers and will impart toughness to the final nanocapillary composite membrane. Thus, unlike other fuel cell membranes, the role of the polymer support matrix will be decoupled from that of the proton-conducting channels. The expected final outcome of this 5-year project is the fabrication of fuel cell membranes with properties that exceed the DOE’s technical targets, in particular a proton conductivity of 0.1 S/cm at a temperature less than or equal to120°C and 25-50% relative humidity.

  10. Mathematical equations for heat conduction in the fins of air-cooled engines

    NASA Technical Reports Server (NTRS)

    Harper, R R; Brown, W B

    1923-01-01

    The problem considered in this report is that of reducing actual geometrical area of fin-cooling surface, which is, of course, not uniform in temperature, to equivalent cooling area at one definite temperature, namely, that prevailing on the cylinder wall at the point of attachment of the fin. This makes it possible to treat all the cooling surface as if it were part of the cylinder wall and 100 per cent effective. The quantities involved in the equations are the geometrical dimensions of the fin, thermal conductivity of the material composing it, and the coefficient of surface heat dissipation between the fin and the air streams.

  11. Distribution Characteristics of Normal Pure-Tone Thresholds

    PubMed Central

    Margolis, Robert H.; Wilson, Richard H.; Popelka, Gerald R.; Eikelboom, Robert H.; Swanepoel, De Wet; Saly, George L.

    2016-01-01

    Objective This study examined the statistical properties of normal air-conduction thresholds obtained with automated and manual audiometry to test the hypothesis that thresholds are normally distributed and to examine the distributions for evidence of bias in manual testing. Design Four databases were mined for normal thresholds. One contained audiograms obtained with an automated method. The other three were obtained with manual audiometry. Frequency distributions were examined for four test frequencies (250, 500, 1000, and 2000 Hz). Study Sample The analysis is based on 317,569 threshold determinations of 80,547 subjects from four clinical databases. Results Frequency distributions of thresholds obtained with automated audiometry are normal in form. Corrected for age, the mean thresholds are within 1.5 dB of Reference Equivalent Threshold Sound Pressure Levels. Frequency distributions of thresholds obtained by manual audiometry are shifted toward higher thresholds. Two of the three datasets obtained by manual audiometry are positively skewed. Conclusions The positive shift and skew of the manual audiometry data may result from tester bias. The striking scarcity of thresholds below 0 dB HL suggests that audiologists place less importance on identifying low thresholds than they do for higher-level thresholds. We refer to this as the Good Enough Bias and suggest that it may be responsible for differences in distributions of thresholds obtained by automated and manual audiometry. PMID:25938502

  12. A comparison of the nonlinear response of the ear to air and to bone-conducted sound.

    PubMed

    Clavier, O H; Norris, J A; Dietz, A J

    2010-05-01

    The nonlinear response of the ear to air-conducted sound has been studied to some depth. However, the nonlinear response of the ear to bone-conducted sound has received less attention. A comparison of the nonlinear response of humans to air and bone-conducted sound is presented. Two different human subject test techniques were combined in this investigation. The first was a psychoacoustic investigation measuring the perceived cancellation of a bone-conducted sound stimulus with another air-conducted sound stimulus. The measurement was accomplished through a loudness-matching technique. The second investigation used distortion product otoacoustic emissions (DPOAEs) to make objective measurements of the response of the ear to both air-conducted sound and bone-conducted sound. The results were compared to determine whether the measured compression effects were similar for the different types of stimuli. Results show that both the measured psychoacoustic response and the measured objective response of the ear to air-conducted sound and to bone-conducted sound were similar at 2 and 4kHz. PMID:20227477

  13. Deep rooting plants influence on soil hydraulic properties and air conductivity over time

    NASA Astrophysics Data System (ADS)

    Uteau, Daniel; Peth, Stephan; Diercks, Charlotte; Pagenkemper, Sebastian; Horn, Rainer

    2014-05-01

    Crop sequences are commonly suggested as an alternative to improve subsoil structure. A well structured soil can be characterized by enhanced transport properties. Our main hypothesis was, that different root systems can modify the soil's macro/mesopore network if enough cultivation time is given. We analyzed the influence of three crops with either shallower roots (Festuca arundinacea, fescue) or taproots (Cichorium intybus, chicory and Medicago sativa, alfalfa). The crops where cultivated on a Haplic Luvisol near Bonn (Germany) for one, two or three years. Undisturbed soil cores were taken for measurement of unsaturated hydraulic conductivity and air permeability. The unsaturated conductivity was measured using the evaporation method, monitoring the water content and tension at two depths of each undisturbed soil core. The van Genuchten-Mualem model (1991) was fitted to the measured data. Air permeability was measured in a permeameter with constant flow at low pressure gradient. The measurements were repeated at -1, -3, -6, -15, -30 and -50 kPa matric tension and the model of Ball et al. (1988) was used to describe permeability as function of matric tension. Furthermore, the cores equilibrated at -15 kPa matric tension were scanned with X-Ray computer tomography. By means of 3D image analysis, geometrical features as pore size distribution, tortuosity and connectivity of the pore network was analyzed. The measurements showed an increased unsaturated hydraulic conductivity associated to coarser pores at the taprooted cultivations. A enhanced pore system (related to shrink-swell processes) under alfalfa was observed in both transport measurements and was confirmed by the 3D image analysis. This highly functional pore system (consisting mainly of root paths, earthworm channels and shrinking cracks) was clearly visible below the 75 cm of depth and differentiated significantly from the other two treatments only after three years of cultivation, which shows the time

  14. Effect of floating conducting objects on critical switching impulse breakdown of air insulation

    SciTech Connect

    Rizk, F.A.M.

    1995-07-01

    The paper analyses the mechanism of breakdown of phase-to-ground and phase-to-phase air insulation in the presence of large conducting floating objects, under critical switching impulse stress. A new physical modeling approach is introduced which involves determination of the potential of the floating object by charge simulation technique, assessment of streamer breakdown and/or leader inception and propagation in the partial gaps and finally predicts the critical breakdown voltage of various configurations. As to phase-to-ground insulation, the investigation covers rod-plane, conductor-plane and conductor-tower leg configurations with different gap spacings as well as different shapes, dimensions and positions of the floating object. The phase-to-phase study additionally includes the effect of negative switching impulse content of the applied stress. The model is in excellent agreement with experiment and provides a novel tool for assessment of the effect of floating objects on switching impulse breakdown of some basic air gap configurations relevant to live line work.

  15. Fluid volume displacement at the oval and round windows with air and bone conduction stimulation

    NASA Astrophysics Data System (ADS)

    Stenfelt, Stefan; Hato, Naohito; Goode, Richard L.

    2004-02-01

    The fluids in the cochlea are normally considered incompressible, and the fluid volume displacement of the oval window (OW) and the round window (RW) should be equal and of opposite phase. However, other channels, such as the cochlear and vestibular aqueducts, may affect the fluid flow. To test if the OW and RW fluid flows are equal and of opposite phase, the volume displacement was assessed by multiple point measurement at the windows with a laser Doppler vibrometer. This was done during air conduction (AC) stimulation in seven fresh human temporal bones, and with bone conduction (BC) stimulation in eight temporal bones and one human cadaver head. With AC stimulation, the average volume displacement of the two windows is within 3 dB, and the phase difference is close to 180° for the frequency range 0.1 to 10 kHz. With BC stimulation, the average volume displacement difference between the two windows is greater: below 2 kHz, the volume displacement at the RW is 5 to 15 dB greater than at the OW and above 2 kHz more fluid is displaced at the OW. With BC stimulation, lesions at the OW caused only minor changes of the fluid flow at the RW.

  16. Air cooling of a vented enclosure by combined conduction, natural convection and radiation

    SciTech Connect

    Yu, E.; Joshi, Y.K.

    1996-12-31

    A three-dimensional investigation of combined conduction, natural convection and radiation in vented enclosures is carried out. A discrete flush type heat source mounted on a vertical substrate is used to simulate an electronic component. A uniform volumetric generation rate is assumed within the heat source. Combined natural convection in the air, conduction in the heat source, the substrate and the enclosure walls, and surface radiation are solved for Rayleigh numbers at 2.6 {times} 10{sup 6} and 2.0 {times} 10{sup 7}. Radiation is incorporated based on the radiosity/irradiation approach. The resulting flow and temperature patterns are discussed, focusing on radiation and three-dimensional effects. The relative contributions of natural convection and radiation are investigated for different emissivities of internal surface of the substrate. Heat transfer rates from the substrate and other internal walls are presented to illustrate conjugate heat transfer due to combined modes. The numerical solutions are found in reasonably good agreement with the data.

  17. Effect of High-Pass Filtering on the Neonatal Auditory Brainstem Response to Air- and Bone-Conducted Clicks.

    ERIC Educational Resources Information Center

    Stuart, Andrew; Yang, Edward Y.

    1994-01-01

    Simultaneous 3- channel recorded auditory brainstem responses (ABR) were obtained from 20 neonates with various high-pass filter settings and low intensity levels. Results support the advocacy of less restrictive high-pass filtering for neonatal and infant ABR screening to air-conducted and bone-conducted clicks. (Author/JDD)

  18. Adaptive Thresholds

    SciTech Connect

    Bremer, P. -T.

    2014-08-26

    ADAPT is a topological analysis code that allow to compute local threshold, in particular relevance based thresholds for features defined in scalar fields. The initial target application is vortex detection but the software is more generally applicable to all threshold based feature definitions.

  19. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  20. Prediction of the percolation threshold and electrical conductivity of self-assembled antimony-doped tin oxide nanoparticles into ordered structures in PMMA/ATO nanocomposites.

    PubMed

    Jin, Youngho; Gerhardt, Rosario A

    2014-12-24

    Electrical percolation in nanocomposites consisting of poly(methyl methacrylate) (PMMA) and antimony tin oxide (ATO) nanoparticles was investigated experimentally using monosize and polydisperse polymer particles. The nanocomposites were fabricated by compression molding at 170 °C. The matrix PMMA was transformed into space filling polyhedra while the ATO nanoparticles distributed along the sharp edges of the matrix, forming a 3D interconnected network. The measured electrical resistivity showed that percolation was achieved in these materials at a very low ATO content of 0.99 wt % ATO when monosize PMMA was used, whereas 1.48 wt % ATO was needed to achieve percolation when the PMMA was polydispersed. A parametric finite element approach was chosen to model this unique microstructure-driven self-assembling percolation behavior. COMSOL Multiphysics was used to solve the effects of phase segregation between the matrix and the filler using a 2D simplified model in the frequency domain of the AC/DC module. It was found that the percolation threshold (pc) is affected by the size ratio between the matrix and the filler in a systematic way. Furthermore, simulations indicate that small deviations from perfect interconnection result mostly in changes in the electrical resistivity while the minimum DC resistivity achievable in any given composite is governed by the electrical conductivity of the filler, which must be accurately known in order to obtain an accurate prediction. The model is quite general and is able to predict percolation behavior in a number of other similarly processed segregated network nanocomposites. PMID:25427537

  1. Occurrence of electrical percolation threshold and observation of phase transition in chitosan(1- x):AgI x (0.05 ≤ x ≤ 0.2)-based ion-conducting solid polymer composites

    NASA Astrophysics Data System (ADS)

    Aziz, Shujahadeen B.

    2016-07-01

    This paper reports on the investigation of electrical percolation threshold and ion transport mechanism for ion-conducting solid polymer composites based on chitosan. The composite samples were prepared by solution cast technique. The result of DC conductivity versus percolation threshold (Φ^{ - 1/3} ) confirmed that at low AgI concentration, the tunneling effect governs ionic conduction mechanism. Nevertheless, at high filler concentration, the DC conductivity showed a plateau behavior. The DC conductivity as a function of reciprocal temperature revealed that the ion conduction mechanism is slightly temperature dependent and the ion-ion correlational effect is dominant. A steep increase in DC conductivity above 323 K is observed, which indicated the existence of some phase transition near the beta (β)-phase. The drop of DC conductivity at high temperatures is anticipated from the impedance plots. The AC conductivity spectrum exhibited three distinct regions at low temperatures. The high-frequency regions of AC conductivity spectra were almost temperature independent at low temperatures (303-323 K) and obeyed the Jonscher's power law. The variation in frequency exponent versus temperature reveals that ion conduction mechanism follows QMT and CBH models at low and high temperatures, respectively. The valuable achievement of this work is that the temperature dependence of DC conductivity and the frequency exponent ( s) is correlated to interpret the Ag+ ion dynamic and ion-ion correlational effect. The Argand plots were used to explain the relaxation processes.

  2. Temperature and strain rate effects in high strength high conductivity copper alloys tested in air

    SciTech Connect

    Edwards, D.J.

    1998-03-01

    The tensile properties of the three candidate alloys GlidCop{trademark} Al25, CuCrZr, and CuNiBe are known to be sensitive to the testing conditions such as strain rate and test temperature. This study was conducted on GlidCop Al25 (2 conditions) and Hycon 3HP (3 conditions) to ascertain the effect of test temperature and strain rate when tested in open air. The results show that the yield strength and elongation of the GlidCop Al25 alloys exhibit a strain rate dependence that increases with temperature. Both the GlidCop and the Hycon 3 HP exhibited an increase in strength as the strain rate increased, but the GlidCop alloys proved to be the most strain rate sensitive. The GlidCop failed in a ductile manner irrespective of the test conditions, however, their strength and uniform elongation decreased with increasing test temperature and the uniform elongation also decreased dramatically at the lower strain rates. The Hycon 3 HP alloys proved to be extremely sensitive to test temperature, rapidly losing their strength and ductility when the temperature increased above 250 C. As the test temperature increased and the strain rate decreased the fracture mode shifted from a ductile transgranular failure to a ductile intergranular failure with very localized ductility. This latter observation is based on the presence of dimples on the grain facets, indicating that some ductile deformation occurred near the grain boundaries. The material failed without any reduction in area at 450 C and 3.9 {times} 10{sup {minus}4} s{sup {minus}1}, and in several cases failed prematurely.

  3. 40 CFR 60.4875 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.4875 Section 60.4875... Initial Compliance Requirements § 60.4875 By what date must I conduct the initial air pollution control device inspection and make any necessary repairs? (a) You must conduct an air pollution control...

  4. 40 CFR 60.4875 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.4875 Section 60.4875... Initial Compliance Requirements § 60.4875 By what date must I conduct the initial air pollution control device inspection and make any necessary repairs? (a) You must conduct an air pollution control...

  5. 40 CFR 60.4875 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.4875 Section 60.4875... Initial Compliance Requirements § 60.4875 By what date must I conduct the initial air pollution control device inspection and make any necessary repairs? (a) You must conduct an air pollution control...

  6. 40 CFR 60.4875 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.4875 Section 60.4875... Initial Compliance Requirements § 60.4875 By what date must I conduct the initial air pollution control device inspection and make any necessary repairs? (a) You must conduct an air pollution control...

  7. 40 CFR 60.5195 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.5195 Section 60.5195... air pollution control device inspection and make any necessary repairs? (a) You must conduct an air... approved state plan, Federal plan, or delegation, as applicable. For air pollution control...

  8. 40 CFR 60.5195 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.5195 Section 60.5195... air pollution control device inspection and make any necessary repairs? (a) You must conduct an air... approved state plan, Federal plan, or delegation, as applicable. For air pollution control...

  9. 40 CFR 60.5195 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.5195 Section 60.5195... air pollution control device inspection and make any necessary repairs? (a) You must conduct an air... approved state plan, Federal plan, or delegation, as applicable. For air pollution control...

  10. 40 CFR 60.5195 - By what date must I conduct the initial air pollution control device inspection and make any...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection and make any necessary repairs? 60.5195 Section 60.5195... air pollution control device inspection and make any necessary repairs? (a) You must conduct an air... approved state plan, Federal plan, or delegation, as applicable. For air pollution control...

  11. The role of biological system other than auditory air-conduction in the emergence of the hypersonic effect.

    PubMed

    Oohashi, Tsutomu; Kawai, Norie; Nishina, Emi; Honda, Manabu; Yagi, Reiko; Nakamura, Satoshi; Morimoto, Masako; Maekawa, Tadao; Yonekura, Yoshiharu; Shibasaki, Hiroshi

    2006-02-16

    Although human beings cannot perceive elastic vibrations in the frequency range above 20 kHz, nonstationary sounds containing a wealth of inaudible high-frequency components (HFC) above the human audible range activate deep-lying brain structures, including the brainstem and thalamus and evoke various physiological, psychological, and behavioral responses. In the previous reports, we have called these phenomena collectively "the hypersonic effect." It remains unclear, however, if vibratory stimuli above the audible range are transduced and perceived solely via the conventional air-conducting auditory system or if other mechanisms also contribute to mediate transduction and perception. In the present study, we have examined the emergence of the hypersonic effect when inaudible HFC and audible low-frequency components (LFC) were presented selectively to the ears, the entrance of an air-conducting auditory system, or to the body surface including the head which might contain some unknown vibratory sensing mechanisms. We used two independent measurements based on differing principles; one physiological (alpha 2 frequency of spontaneous electroencephalogram [alpha-EEG]) and the other behavioral (the comfortable listening level [CLL]). Only when the listener's entire body surface was exposed to HFC, but not when HFC was presented exclusively to the air-conducting auditory system, did both the alpha-EEG and the CLL significantly increase compared to the presentation of LFC alone, that is to say, there was an evident emergence of the hypersonic effect. The present findings suggest that the conventional air-conducting auditory system alone does not bring about the hypersonic effect. We may need to consider the possible involvement of a biological system distinct from the conventional air-conducting auditory nervous system in sensing and transducing high-frequency elastic vibration above the human audible range. PMID:16458271

  12. Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

    PubMed

    Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

    2013-08-01

    An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. PMID:23564676

  13. Air-Stable, High-Conduction Solid Electrolytes of Arsenic-Substituted Li4SnS4

    SciTech Connect

    Sahu, Gayatri; Lin, Zhan; Li, Juchuan; Liu, Zengcai; Dudney, Nancy J; Liang, Chengdu

    2014-01-01

    Lithium-ion-conducting solid electrolytes show promise for enabling high-energy secondary battery chemistries and solving safety issues associated with conventional lithium batteries. Achieving the combination of high ionic conductivity and outstanding chemical stability in solid electrolytes is a grand challenge for the synthesis of solid electrolytes. Herein we report the design of aliovalent substitution of Li4SnS4 to achieve high conduction and excellent air stability based on the hard and soft acids and bases theory. The composition of Li3.833Sn0.833As 0.166S4 has a high ionic conductivity of 1.39 mS/cm 1 at 25 C. Considering the high Li+ transference number, this phase conducts Li+ as well as carbonate-based liquid electrolytes. This research also addresses the compatibility of the sulfide-based solid electrolytes through chemical passivation.

  14. Wind Direction Bias in Generating Wind Roses and Conducting Sector-Based Air-Dispersion Modeling

    SciTech Connect

    Droppo, James G.; Napier, Bruce A.

    2008-07-01

    Certain widely used wind rose programs and air dispersion models use an overly-simple data-transfer algorithm that induces a directional bias in their output products. The purpose of this paper is to provide a revised algorithm that corrects the aliasing bias that occurs when the internals in reported wind direction data are on the same order of magnitude, but not equal to the intervals used in the wind direction summaries. The directional bias issue arises when output products in 22.5-degree sectors are produced from 10-degree wind direction data, which affects the results of simulations of air and surface concentrations using widely applied air-dispersion models. Datasets or models with the bias discussed here give consistent positive biases (approximately 30%) for cardinal direction sectors (north, south, east, and west) and consistent negative biases for all the other sectors (approximately -10%). Data summary and air dispersion programs providing outputs in directions sectors that do not match the observational sectors need to be checked for this bias. A revised data-transfer algorithm is provided that corrects the aliasing bias that can occur in transferring wind direction data between different sectors widths.

  15. An overview of the Noncyanide Metal Stripper program conducted at Kelly Air Force Base

    SciTech Connect

    Argyle, M.D.; Cowan, R.L.

    1995-01-01

    The Noncyanide Metal Stripper Program was a waste minimization effort aimed at identifying and testing suitable noncyanide stripping solutions that could replace the cyanide stripping solutions found in the United States Air Force (USAF) Air Logistics Centers (ALC). The program started with laboratory testing of commercial stripping solutions. The performance of these solutions was compared with the cyanide process solutions C-101 and C-106 targeted for replacement. Plate metal stripping rate, basis metal corrosion, and compatibility with masking materials and biodegradability were all used to determine the performance of each product. Those products that passed the acceptance criteria were field tested using 25 to 50-gallon solutions to determine optimum operating conditions, stripper maintenance requirements, and maximum solution loading and longevity. The program included investigating any adverse effects these new products might have on existing chemical and biological waste treatment processes. All cyanide stripping solutions at the San Antonio Air Logistics Command Center have been successfully replaced with commercial noncyanide products. Generally, these replacements were less toxic and generated less waste and had longer lifetimes than their cyanide counterparts.

  16. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    NASA Astrophysics Data System (ADS)

    Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.

    2010-01-01

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows.

  17. Quantum chemical clarification of the alkyl chain length threshold of nonionic surfactants for monolayer formation at the air/water interface.

    PubMed

    Vysotsky, Yu B; Kartashynska, E S; Belyaeva, E A; Vollhardt, D; Fainerman, V B; Miller, R

    2016-03-21

    A theoretical basis is provided for the experimental fact that for various surfactant classes the alkyl chain length threshold varies for the formation of condensed monolayers. The existence of the alkyl chain length threshold for a surfactant enabling the formation of monolayers is determined by the entropy increment to the Gibbs' energy, assessed by using the quantum chemical semiempiric method PM3. The value of the clusterization threshold is not stipulated by the surfactant solubility in water, rather by the electron-donor and electron-seeking properties of the head groups. These properties in turn impact the value of the solubility threshold for surfactants. The value of the clusterization threshold depends quadratically on the substituent constants, i.e. it is independent of whether the functional group is a donor or an acceptor of electrons. Rather it depends only on the donor or the acceptor 'force' of the substituent. The square-law dependence of the surface clusterization threshold of the amphiphile on the solubility threshold is evidenced. PMID:26957020

  18. Thermal Conductivity and Erosion Durability of Composite Two-Phase Air Plasma Sprayed Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Schmitt, Michael P.; Rai, Amarendra K.; Zhu, Dongming; Dorfman, Mitchell R.; Wolfe, Douglas E.

    2015-01-01

    To enhance efficiency of gas turbines, new thermal barrier coatings (TBCs) must be designed which improve upon the thermal stability limit of 7 wt% yttria stabilized zirconia (7YSZ), approximately 1200 C. This tenant has led to the development of new TBC materials and microstructures capable of improved high temperature performance. This study focused on increasing the erosion durability of cubic zirconia based TBCs, traditionally less durable than the metastable t' zirconia based TBCs. Composite TBC microstructures composed of a low thermal conductivity/high temperature stable cubic Low-k matrix phase and a durable t' Low-k secondary phase were deposited via APS. Monolithic coatings composed of cubic Low-k and t' Low-k were also deposited, in addition to a 7YSZ benchmark. The thermal conductivity and erosion durability were then measured and it was found that both of the Low-k materials have significantly reduced thermal conductivities, with monolithic t' Low-k and cubic Low-k improving upon 7YSZ by approximately 13 and approximately 25%, respectively. The 40 wt% t' Low-k composite (40 wt% t' Low-k - 60 wt% cubic Low-k) showed a approximately 22% reduction in thermal conductivity over 7YSZ, indicating even at high levels, the t' Low-k secondary phase had a minimal impact on thermal in the composite coating. It was observed that a mere 20 wt% t' Low-k phase addition can reduce the erosion of a cubic Low-k matrix phase composite coating by over 37%. Various mixing rules were then investigated to assess this non-linear composite behavior and suggestions were made to further improve erosion durability.

  19. Centimeter-scale secondary information on hydraulic conductivity using a hand-held air permeameter on borehole cores.

    NASA Astrophysics Data System (ADS)

    Rogiers, B.; Winters, P.; Huysmans, M.; Beerten, K.; Mallants, D.; Gedeon, M.; Batelaan, O.; Dassargues, A.

    2012-04-01

    Saturated hydraulic conductivity (Ks) is one of the most important parameters determining groundwater flow and contaminant transport in both unsaturated and saturated porous media. Determining the small-scale variability of this parameter is key to evaluate implications on effective parameters at the larger scale. Moreover, for stochastic simulations of groundwater flow and contaminant transport, accurate models on the spatial variability of Ks are very much needed. While several well-established laboratory methods exist for determining Ks, investigating the small-scale variability remains a challenge. If several tens to hundreds of metres of borehole core has to be hydraulically characterised at the centimetre to decimetre scale, several hundreds to thousands of Ks measurements are required, which makes it very costly and time-consuming should traditional methods be used. With reliable air permeameters becoming increasingly available from the late 80's, a fast and effective indirect method exists to determine Ks. Therefore, the use of hand-held air permeameter measurements for determining very accurate small-scale heterogeneity about Ks is very appealing. Very little is known, however, on its applicability for borehole cores that typically carry a small sediment volume. Therefore, the method was tested on several borehole cores of different size, originating from the Campine basin, Northern Belgium. The studied sediments are of Miocene to Pleistocene age, with a marine to continental origin, and consist of sand to clayey sand with distinct clay lenses, resulting in a Ks range of 7 orders of magnitude. During previous studies, two samples were taken from borehole cores each two meters for performing constant head lab permeameter tests. This data is now used as a reference for the air permeameter measurements that are performed with a resolution of 5 centimetres. Preliminary results indicate a very good correlation between the previously gathered constant head Ks

  20. Medical devices; ear, nose, and throat devices; classification of the transcutaneous air conduction hearing aid system. Final rule.

    PubMed

    2002-11-01

    The Food and Drug Administration (FDA) is classifying the transcutaneous air conduction hearing aid system (TACHAS) into class II (special controls). Elsewhere in this issue of the Federal Register, FDA is announcing the availability of a guidance document that will serve as the special control for the device. The agency is taking this action in response to a petition submitted under the Federal Food, Drug, and Cosmetic Act (the act) as amended by the Medical Device Amendments of 1976 (the amendments), the Safe Medical Devices Act of 1990, and the Food and Drug Administration Modernization Act of 1997 (FDAMA). The agency is classifying this device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. PMID:12422884

  1. A tough, thermally conductive silicon carbide composite with high strength up to 1600 degreesC in Air

    PubMed

    Ishikawa; Kajii; Matsunaga; Hogami; Kohtoku; Nagasawa

    1998-11-13

    A sintered silicon carbide fiber-bonded ceramic, which consists of a highly ordered, close-packed structure of very fine hexagonal columnar fibers with a thin interfacial carbon layer between fibers, was synthesized by hot-pressing plied sheets of an amorphous silicon-aluminum-carbon-oxygen fiber prepared from an organosilicon polymer. The interior of the fiber element was composed of sintered beta-silicon carbide crystal without an obvious second phase at the grain boundary and triple points. This material showed high strength (over 600 megapascals in longitudinal direction), fibrous fracture behavior, excellent high-temperature properties (up to 1600 degreesC in air), and high thermal conductivity (even at temperatures over 1000 degreesC). PMID:9812889

  2. Carrier-envelope phase-dependent electronic conductivity in an air filament driven by few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Wang, Lifeng; Lu, Xin; Teng, Hao; Xi, Tingting; Chen, Shiyou; He, Peng; He, Xinkui; Wei, Zhiyi

    2016-07-01

    The modulation of the electron conductivity in an air filament, which is produced by carrier-envelope phase (CEP) stabilized 7-fs laser pulses, is realized experimentally. Numerical results based on a coupled 3D+1 generalized nonlinear Schrödinger equation including the real electric-field dependent ionization model are in good agreement with those from the experiment. It is demonstrated that the CEP effect on the electron density originates from the CEP-induced modification of the electric field of the laser pulse, and this modification is amplified during nonlinear propagation. The results provide important information to help understand the physical mechanism of the filaments driven by few-cycle femtosecond laser pulses.

  3. Possible secular change and land-to-ocean extension of air pollution from measurements of atmospheric electrical conductivity over the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Kamra, A. K.; Deshpande, C. G.

    1995-04-01

    Diurnal variations of the atmospheric electrical conductivity and electric field at a fixed point in the Bay of Bengal, where an oceanographic ship, ORV Sagarkanya, remained stationary for a total of 28 days, are reported. From observations, one can speculate a secular decrease in total conductivity in the Bay of Bengal by at least 40% since the Cobb and Wells (1970) measurements during 1967 global expedition. Problem of the land-to-ocean extension of air pollution has been studied from the conductivity measurements made in the monsoon season when surface winds are persistently southwesterly. Values of conductivity near the eastern coastline of India where windflow is from land to sea are about half of those near to the western coastline where windflow is from sea to land. It is concluded that to know the air conductivity at a point over sea, the age of air mass over sea is a better determining factor than the distance from the coastline.

  4. Determinants of Change in Air-Bone Gap and Bone Conduction in Patients Operated on for Chronic Otitis Media

    PubMed Central

    Wiatr, Maciej; Wiatr, Agnieszka; Składzień, Jacek; Stręk, Paweł

    2015-01-01

    Background Middle ear surgery aims to eliminate pathology from the middle ear, improve drainage and ventilation of the postoperative cavity, and reconstruct the tympanic membrane and ossicles. The aim of this work is to define the factors that affect ABG (air-bone gap) and bone conduction in the patients operated on due to chronic otitis media. Material/Methods A prospective analysis of patients operated on due to diseases of the middle ear during 2009–2012 was carried out. The cases of patients operated on for the first time due to chronic otitis media were analyzed. The analysis encompassed patients who had undergone middle ear surgery. The patients were divided into several groups taking into account the abnormalities of the middle ear mucous and damage of the ossicular chain observed during otosurgery. Results A significant hearing improvement was observed in patients with type 2 tympanoplasty in the course of chronic cholesteatoma otitis media and in patients with simple chronic inflammatory process in whom a PORP was used in the reconstruction. Granulation tissue was an unfavorable factor of hearing improvement following tympanoplasty. A significant improvement of bone conduction was observed in the patients with dry perforation without other lesions in the middle ear. The elimination of granulation lesions was a positive factor for the future improvement of the function of the inner ear. Conclusions The presence of granuloma-related lesions in the middle ear spaces is likely to impede hearing improvement. Damage to the ossicular chain rules out the possibility of bone conduction improvement after surgery. The prognosis on tube-related simple chronic otitis media after myringoplasty, with the preserved continuity of the ossicular chain, consists of closing the ABG and leads to significant improvement of bone conduction. PMID:26259623

  5. 40 CFR 60.2716 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection? 60.2716 Section 60.2716 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY... annual air pollution control device inspection), you must complete the air pollution control...

  6. 40 CFR 60.2141 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection? 60.2141 Section 60.2141 Protection of Environment... initial air pollution control device inspection? (a) The initial air pollution control device inspection... startup. (b) Within 10 operating days following an air pollution control device inspection, all...

  7. 40 CFR 60.2716 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection? 60.2716 Section 60.2716 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY... annual air pollution control device inspection), you must complete the air pollution control...

  8. 40 CFR 60.2151 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection? 60.2151 Section 60.2151 Protection of Environment... annual air pollution control device inspection? On an annual basis (no more than 12 months following the previous annual air pollution control device inspection), you must complete the air pollution...

  9. 40 CFR 60.2716 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection? 60.2716 Section 60.2716 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY... annual air pollution control device inspection), you must complete the air pollution control...

  10. 40 CFR 60.2141 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection? 60.2141 Section 60.2141 Protection of Environment... initial air pollution control device inspection? (a) The initial air pollution control device inspection... startup. (b) Within 10 operating days following an air pollution control device inspection, all...

  11. 40 CFR 60.2151 - By what date must I conduct the annual air pollution control device inspection?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air pollution control device inspection? 60.2151 Section 60.2151 Protection of Environment... annual air pollution control device inspection? On an annual basis (no more than 12 months following the previous annual air pollution control device inspection), you must complete the air pollution...

  12. Conducting polymer actuator based on chemically deposited polypyrrole and polyurethane-based solid polymer electrolyte working in air

    NASA Astrophysics Data System (ADS)

    Choi, Hwa-Jeong; Song, Young-Min; Chung, Ildoo; Ryu, Kwang-Sun; Jo, Nam-Ju

    2009-02-01

    Conducting polymers (CPs), such as polypyrrole, polythiophene, and polyaniline, are unique in that they have switchable properties due to their two or more mechanically stable oxidation states. Thus, their films or coatings can be easily switched by the application of a small voltage and current to change their volume during electrochemical redox processes. In particular, polypyrrole (PPy) has been studied most extensively because of its high electrical conductivity and good environmental stability under ambient conditions. In this work, we have studied a new CP actuator, fully polymeric, assembled with two PPy film electrodes and a solid polymer electrolyte (SPE), polyurethane/Mg(ClO4)2. Polyurethanes (PUs) were synthesized from 4,4'-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD) and three types of polyol: poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and PPG-block-PEG-block-PPG (PPG-co-PEG). The chemical polymerization of PPy by immersion in Py monomer aqueous solution and oxidant aqueous solution is an adequate method to prepare PU/PPy composite film as an actuator. To find the proper thickness of the PPy coating layer for actuation, we measured the displacements of the actuators according to the thickness of the PPy coating layer. The displacement of all actuators is discussed in connection with the properties of the SPE and PPy. All the results obtained in this work show the feasibility of electrochemomechanical devices based on PPy and SPE film being able to work in air.

  13. Cervical and ocular vestibular-evoked myogenic potentials in vestibular neuritis: comparison between air- and bone-conducted stimulation.

    PubMed

    Oh, Sun-Young; Kim, Ji-Soo; Yang, Tae-Ho; Shin, Byoung-Soo; Jeong, Seul-Ki

    2013-08-01

    To clarify the changes of cervical (cVEMP) and ocular (oVEMP) vestibular evoked myogenic potentials induced by air-conducted sound (ACS) and bone-conducted vibration (BCV) in patients with vestibular neuritis (VN), patients with VN (n = 30) and normal controls (n = 45) underwent recording of cVEMP and oVEMP in response to ACS (1,000 Hz, 5 ms, tone bursts) and BCV (500 Hz, short tone burst). Patients with VN showed a high proportion of oVEMP abnormalities in response to both ACS (80.0 %) and BCV at the forehead (Fz, 73.3 %) or the mastoid (76.7 %). In contrast, cVEMPs were mostly normal with both ACS and BCV in the patients. The dissociations in the abnormalities of cVEMP and oVEMP induced by ACS and BCV at the mastoids and at the forehead in patients with VN suggest that oVEMP reflects functions of the superior vestibular nerve and most likely the utricular function. The results of our study suggest that oVEMP induced by either ACS or BCV appears to depend on integrity of the superior vestibular nerve, possibly due to the utricular afferents travelling in it. In contrast, cVEMP elicited by either ACS or BCV may reflect function of the saccular afferents running in the inferior vestibular nerve. PMID:23670310

  14. 40 CFR 60.2706 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air pollution control device inspection? 60.2706 Section 60.2706 Protection of Environment... pollution control device inspection? (a) The initial air pollution control device inspection must be... meeting the amended emission limitations. (b) Within 10 operating days following an air pollution...

  15. 40 CFR 60.2706 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air pollution control device inspection? 60.2706 Section 60.2706 Protection of Environment... pollution control device inspection? (a) The initial air pollution control device inspection must be... meeting the amended emission limitations. (b) Within 10 operating days following an air pollution...

  16. 40 CFR 60.2706 - By what date must I conduct the initial air pollution control device inspection?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air pollution control device inspection? 60.2706 Section 60.2706 Protection of Environment... pollution control device inspection? (a) The initial air pollution control device inspection must be... meeting the amended emission limitations. (b) Within 10 operating days following an air pollution...

  17. Frequency and phase effects on cervical vestibular evoked myogenic potentials (cVEMPs) to air-conducted sound.

    PubMed

    Govender, Sendhil; Dennis, Danielle L; Colebatch, James G

    2016-09-01

    Few previous studies of tuning using air-conducted (AC) stimuli and the cervical vestibular evoked myogenic potential (cVEMP) have compensated for the effects of middle ear (ME) attenuation. Zhang et al. (Exp Brain Res 213:111-116, 2011a) who did allow for ME effects were able to show a secondary peak around 100 Hz for the ocular VEMP (oVEMP). Recently, it has become clear that the otolith afferents responsible for the cVEMP and oVEMP differ and thus the nature of tuning may be more related to the reflex studied determining which otolith receptors are activated rather than the properties of the stimulus. We wished to reinvestigate the tuning for the cVEMP using AC stimuli, to establish whether the low-frequency peak is specific for the oVEMP or a consequence of the stimulus modality itself. In response to recent evidence using a 500 Hz AC stimulus that there was no effect of stimulus phase, we also investigated whether phase (condensation or rarefaction) had an effect at any frequency. We measured corrected cVEMP amplitudes and latencies in response to stimuli between 50 and 1200 Hz in 10 normal volunteers using an AC stimulus adjusted for ME attenuation. We confirmed earlier reports of the similarity of the tuning for both the cVEMP and oVEMP reflexes but found no separate 100 Hz peak for the cVEMP. AC stimulus phase did not affect either amplitude or latency. Both the tuning pattern and the phase effects contrast with those previously reported for bone-conducted (BC) stimuli. Unlike BC stimulation, which shows tuning consistent with an action on the otolith membrane, AC stimuli are likely to act through a different mechanism, most likely directly at the hair cell level. PMID:27150315

  18. Ionic Conductivity and Air Stability of Al-Doped Li₇La₃Zr₂O₁₂ Sintered in Alumina and Pt Crucibles.

    PubMed

    Xia, Wenhao; Xu, Biyi; Duan, Huanan; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-03-01

    Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state battery due to its high ionic conductivity and good stability with metallic lithium. In this article, we studied the effect of crucibles on the ionic conductivity and air stability by synthesizing 0.25Al doped LLZO pellets in Pt crucibles and alumina crucibles, respectively. The results show that the composition and microstructure of the pellets play important roles influencing the ionic conductivity, relative density, and air stability. Specifically, the 0.25Al-LLZO pellets sintered in Pt crucibles exhibit a high relative density (∼96%) and high ionic conductivity (4.48 × 10(-4) S cm(-1)). The ionic conductivity maintains 3.6 × 10(-4) S cm(-1) after 3-month air exposure. In contrast, the ionic conductivity of the pellets from alumina crucibles is about 1.81 × 10(-4) S cm(-1) and drops to 2.39 × 10(-5) S cm(-1) 3 months later. The large grains and the reduced grain boundaries in the pellets sintered in Pt crucibles are favorable to obtain high ionic conductivity and good air stability. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy results suggest that the formation of Li2CO3 on the pellet surface is probably another main reason, which is also closely related to the relative density and the amount of grain boundary within the pellets. This work stresses the importance of synthesis parameters, crucibles included, to obtain the LLZO electrolyte with high ionic conductivity and good air stability. PMID:26859158

  19. 40 CFR 98.81 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Reporting threshold. 98.81 Section 98.81 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Cement Production § 98.81 Reporting threshold. You must report...

  20. 40 CFR 98.51 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.51 Section 98.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Adipic Acid Production § 98.51 Reporting threshold. You must report...

  1. 40 CFR 98.81 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.81 Section 98.81 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Cement Production § 98.81 Reporting threshold. You must report...

  2. 40 CFR 98.51 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Reporting threshold. 98.51 Section 98.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Adipic Acid Production § 98.51 Reporting threshold. You must report...

  3. 40 CFR 98.111 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Reporting threshold. 98.111 Section 98.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Ferroalloy Production § 98.111 Reporting threshold. You must report...

  4. 40 CFR 98.81 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.81 Section 98.81 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Cement Production § 98.81 Reporting threshold. You must report...

  5. 40 CFR 98.361 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Reporting threshold. 98.361 Section 98.361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.361 Reporting threshold. Livestock facilities must report GHG emissions under this...

  6. 40 CFR 98.361 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.361 Section 98.361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management § 98.361 Reporting threshold. Livestock facilities...

  7. 40 CFR 98.461 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.461 Section 98.461 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Waste Landfills § 98.461 Reporting threshold. You must report GHG emissions under this subpart if...

  8. 40 CFR 98.111 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.111 Section 98.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Ferroalloy Production § 98.111 Reporting threshold. You must report...

  9. 40 CFR 98.51 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Reporting threshold. 98.51 Section 98.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Adipic Acid Production § 98.51 Reporting threshold. You must report...

  10. 40 CFR 98.181 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Reporting threshold. 98.181 Section 98.181 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Lead Production § 98.181 Reporting threshold. You must report...

  11. 40 CFR 98.461 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Reporting threshold. 98.461 Section 98.461 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Waste Landfills § 98.461 Reporting threshold. You must report GHG emissions under this subpart if...

  12. 40 CFR 98.341 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.341 Section 98.341 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Municipal Solid Waste Landfills § 98.341 Reporting threshold. You...

  13. 40 CFR 98.51 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Reporting threshold. 98.51 Section 98.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Adipic Acid Production § 98.51 Reporting threshold. You must report...

  14. 40 CFR 98.51 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.51 Section 98.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Adipic Acid Production § 98.51 Reporting threshold. You must report...

  15. 40 CFR 98.471 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Reporting threshold. 98.471 Section 98.471 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Injection of Carbon Dioxide § 98.471 Reporting threshold. (a) You...

  16. 40 CFR 98.471 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.471 Section 98.471 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Injection of Carbon Dioxide § 98.471 Reporting threshold. (a) You...

  17. 40 CFR 98.471 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Reporting threshold. 98.471 Section 98.471 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Injection of Carbon Dioxide § 98.471 Reporting threshold. (a) You...

  18. 40 CFR 98.111 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Reporting threshold. 98.111 Section 98.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Ferroalloy Production § 98.111 Reporting threshold. You must report...

  19. 40 CFR 98.111 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.111 Section 98.111 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Ferroalloy Production § 98.111 Reporting threshold. You must report...

  20. 40 CFR 98.421 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Reporting threshold. 98.421 Section 98.421 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Carbon Dioxide § 98.421 Reporting threshold. Any supplier...

  1. 40 CFR 98.421 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Reporting threshold. 98.421 Section 98.421 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Carbon Dioxide § 98.421 Reporting threshold. Any supplier...

  2. 40 CFR 98.461 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.461 Section 98.461 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Waste Landfills § 98.461 Reporting threshold. You must report GHG emissions under this subpart if...

  3. 40 CFR 98.231 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.231 Section 98.231 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems § 98.231 Reporting threshold. (a)...

  4. 40 CFR 98.461 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Reporting threshold. 98.461 Section 98.461 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Waste Landfills § 98.461 Reporting threshold. You must report GHG emissions under this subpart if...

  5. Mars Dust Threshold Under Heated Surface Conditions

    NASA Astrophysics Data System (ADS)

    Coquilla, R. V.; White, B. R.

    2002-12-01

    A wind tunnel was used to study the effects of a heated surface, thereby creating an unstable near-surface atmosphere, on the threshold of aeolian-blown (windblown) dust-size particles (1-2 mm) under Mars-simulated pressure. Unstable conditions on Mars typically arise during the mid to late afternoon hours due to the accumulation of daytime solar-radiation. When the surface is warmer than the atmosphere just above it, vertical turbulence is increased. Thus, loose dust particles can be more easily lofted and mixed at a threshold wind speed lower than that known under neutral atmospheric conditions. For this wind-tunnel study, unstable (heated) surface conditions were simulated based on the negative temperature gradients and surface bulk Richardson numbers estimated from the Mars Pathfinder Lander (MPL) mission data during the mid-afternoon to early evening Mars period. According to other missions, evidence of highly active dust suspension during this part of the Mars daytime hours was recorded, including the presence of "dust devils". Experiments were performed in the Martian Surface Wind Tunnel (MARSWIT) located at NASA Ames Research Center, Moffett Field, California. Based on data acquired from the MPL site, the mean surface pressure was found to be 6.75 mb. Thus, simulations in MARSWIT were conducted at 10-mb atmospheric pressure using air, which agrees with a dynamically similar environment of 6.5 mb on Mars. In order to attain the necessary vertical temperature gradients that would develop an unstable layer, a test bed was heated by sub-surface heaters. Three surface roughness conditions were simulated, over which not only dust threshold was measured but also velocity and temperature profiles were acquired under various heating levels. Boundary layer measurements and analysis conducted under neutral conditions were used to estimate roughness height, zo, and the friction speed, u*, for all stability conditions. Dust threshold tests were conducted using a

  6. Synthesis of an air-working trilayer artificial muscle using a conductive cassava starch biofilm (manihot esculenta, cranz) and polypyrrole (PPy)

    NASA Astrophysics Data System (ADS)

    Núñez D, Y. E.; Arrieta A, Á. A.; Segura B, J. A.; Bertel H, S. D.

    2016-02-01

    In this study, a methodology for obtaining a conductive cassava starch biofilm doped with lithium perchlorate (LiClO4) is shown, as well as the electrochemical technique for the synthesis of polypyrrole films, which are used for developing the trilayer artificial muscle PPy/Biopolymer/PPy designed to operate in air. Furthermore, results from the trilayer movement using chronoamperometric techniques are shown.

  7. CARA Risk Assessment Thresholds

    NASA Technical Reports Server (NTRS)

    Hejduk, M. D.

    2016-01-01

    Warning remediation threshold (Red threshold): Pc level at which warnings are issued, and active remediation considered and usually executed. Analysis threshold (Green to Yellow threshold): Pc level at which analysis of event is indicated, including seeking additional information if warranted. Post-remediation threshold: Pc level to which remediation maneuvers are sized in order to achieve event remediation and obviate any need for immediate follow-up maneuvers. Maneuver screening threshold: Pc compliance level for routine maneuver screenings (more demanding than regular Red threshold due to additional maneuver uncertainty).

  8. Analyses and estimates of hydraulic conductivity from slug tests in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

    USGS Publications Warehouse

    Houston, Natalie A.; Braun, Christopher L.

    2004-01-01

    This report describes the collection, analyses, and distribution of hydraulic-conductivity data obtained from slug tests completed in the alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas, during October 2002 and August 2003 and summarizes previously available hydraulic-conductivity data. The U.S. Geological Survey, in cooperation with the U.S. Air Force, completed 30 slug tests in October 2002 and August 2003 to obtain estimates of horizontal hydraulic conductivity to use as initial values in a ground-water-flow model for the site. The tests were done by placing a polyvinyl-chloride slug of known volume beneath the water level in selected wells, removing the slug, and measuring the resulting water-level recovery over time. The water levels were measured with a pressure transducer and recorded with a data logger. Hydraulic-conductivity values were estimated from an analytical relation between the instantaneous displacement of water in a well bore and the resulting rate of head change. Although nearly two-thirds of the tested wells recovered 90 percent of their slug-induced head change in less than 2 minutes, 90-percent recovery times ranged from 3 seconds to 35 minutes. The estimates of hydraulic conductivity range from 0.2 to 200 feet per day. Eighty-three percent of the estimates are between 1 and 100 feet per day.

  9. Threshold quantum cryptography

    SciTech Connect

    Tokunaga, Yuuki; Okamoto, Tatsuaki; Imoto, Nobuyuki

    2005-01-01

    We present the concept of threshold collaborative unitary transformation or threshold quantum cryptography, which is a kind of quantum version of threshold cryptography. Threshold quantum cryptography states that classical shared secrets are distributed to several parties and a subset of them, whose number is greater than a threshold, collaborates to compute a quantum cryptographic function, while keeping each share secretly inside each party. The shared secrets are reusable if no cheating is detected. As a concrete example of this concept, we show a distributed protocol (with threshold) of conjugate coding.

  10. AIR POLLUTION MEASUREMENTS IN THE VICINITY OF THE WORLD TRADE CENTER - SUMMARY OF MEASUREMENTS CONDUCTED BY EPA-ORD

    EPA Science Inventory

    The U.S. Environmental Protection Agency's Office of Research and Development (EPA-ORD) was requested by EPA's Region 2 office in New York on 9/12/01 to assist with air quality monitoring in response to the collapse of the World Trade Center. Scientists at the U.S. EPA-ORD's Nati...

  11. Static and Transient Cavitation Threshold Measurements for Mercury

    SciTech Connect

    Moraga, F.; Taleyarkhan, R.P.

    1999-11-14

    Transient and static cavitation thresholds for mercury as a function of the cover gas (helium or air), and pressure are reported. Both static and transient cavitation onset pressure thresholds increase linearly with cover gas pressure. Additionally, the cavitation thresholds as a function of dissolved gases were also measured and are reported.

  12. Threshold Concepts in Biochemistry

    ERIC Educational Resources Information Center

    Loertscher, Jennifer

    2011-01-01

    Threshold concepts can be identified for any discipline and provide a framework for linking student learning to curricular design. Threshold concepts represent a transformed understanding of a discipline, without which the learner cannot progress and are therefore pivotal in learning in a discipline. Although threshold concepts have been…

  13. Applying Threshold Concepts to Finance Education

    ERIC Educational Resources Information Center

    Hoadley, Susan; Wood, Leigh N.; Tickle, Leonie; Kyng, Tim

    2016-01-01

    Purpose: The purpose of this paper is to investigate and identify threshold concepts that are the essential conceptual content of finance programmes. Design/Methodology/Approach: Conducted in three stages with finance academics and students, the study uses threshold concepts as both a theoretical framework and a research methodology. Findings: The…

  14. Damage thresholds for terahertz radiation

    NASA Astrophysics Data System (ADS)

    Dalzell, Danielle R.; McQuade, Jill; Vincelette, Rebecca; Ibey, Bennet; Payne, Jason; Thomas, Robert; Roach, W. P.; Roth, Caleb L.; Wilmink, Gerald J.

    2010-02-01

    Several international organizations establish minimum safety standards to ensure that workers and the general population are protected against adverse health effects associated with electromagnetic radiation. Suitable standards are typically defined using published experimental data. To date, few experimental studies have been conducted at Terahertz (THz) frequencies, and as a result, current THz standards have been defined using extrapolated estimates from neighboring spectral regions. In this study, we used computational modeling and experimental approaches to determine tissue-damage thresholds at THz frequencies. For the computational modeling efforts, we used the Arrhenius damage integral to predict damage-thresholds. We determined thresholds experimentally for both long (minutes) and short (seconds) THz exposures. For the long exposure studies, we used an in-house molecular gas THz laser (υ= 1.89 THz, 189.92 mW/cm2, 10 minutes) and excised porcine skin. For the short exposure studies, we used the Free Electron Laser (FEL) at Jefferson Laboratory (υ= 0.1-1.0 THz, 2.0-14.0 mW/cm2, 2 seconds) and wet chamois cloths. Thresholds were determined using conventional damage score determination and probit analysis techniques, and tissue temperatures were measured using infrared thermographic techniques. We found that the FEL was ideal for tissue damage studies, while our in-house THz source was not suitable to determine tissue damage thresholds. Using experimental data, the tissue damage threshold (ED50) was determined to be 7.16 W/cm2. This value was in well agreement with that predicted using our computational models. We hope that knowledge of tissue-damage thresholds at THz frequencies helps to ensure the safe use of THz radiation.

  15. Electric field variations measured continuously in free air over a conductive thin zone in the tilted Lias-epsilon black shales near Osnabrück, Northwest Germany

    NASA Astrophysics Data System (ADS)

    Gurk, M.; Bosch, F. P.; Tougiannidis, N.

    2013-04-01

    Common studies on the static electric field distribution over a conductivity anomaly use the self-potential method. However, this method is time consuming and requires nonpolarizable electrodes to be placed in the ground. Moreover, the information gained by this method is restricted to the horizontal variations of the electric field. To overcome the limitation in the self-potential technique, we conducted a field experiment using a non conventional technique to assess the static electric field over a conductivity anomaly. We use two metallic potential probes arranged on an insulated boom with a separation of 126 cm. When placed into the electric field of the free air, a surface charge will be induced on each probe trying to equalize with the potential of the surrounding atmosphere. The use of a plasma source at both probes facilitated continuous and quicker measurement of the electric field in the air. The present study shows first experimental measurements with a modified potential probe technique (MPP) along a 600-meter-long transect to demonstrate the general feasibility of this method for studying the static electric field distribution over shallow conductivity anomalies. Field measurements were carried out on a test site on top of the Bramsche Massif near Osnabrück (Northwest Germany) to benefit from a variety of available near surface data over an almost vertical conductivity anomaly. High resolution self-potential data served in a numerical analysis to estimate the expected individual components of the electric field vector. During the experiment we found more anomalies in the vertical and horizontal components of the electric field than self-potential anomalies. These contrasting findings are successfully cross-validated with conventional near surface geophysical methods. Among these methods, we used self-potential, radiomagnetotelluric, electric resistivity tomography and induced polarization data to derive 2D conductivity models of the subsurface in

  16. Leaf conductance decreased under free-air CO2 enrichment (FACE) for three perennials in the Nevada desert

    USGS Publications Warehouse

    Nowak, R.S.; DeFalco, L.A.; Wilcox, C.S.; Jordan, D.N.; Coleman, J.S.; Seemann, J.R.; Smith, S.D.

    2001-01-01

    A common response of plants to elevated atmospheric CO2 concentration (CO2) is decreased leaf conductance. Consequently, leaf temperature is predicted to increase under elevated CO2. Diurnal patterns of leaf conductance and temperature were measured for three desert perennials, the C3 shrub Larrea tridentata, C3 tussock grass Achnatherum hymenoides and C4 tussock grass Pleuraphis rigida, at the Nevada Desert FACE facility. Measurements were made on ambient and c. 550 ??mol mol-1 CO2 plots through both a wet and dry year. Reductions in conductance were 35%, 20% and 13% for Pleuraphis, Achnatherum and Larrea, respectively. Decreased conductance occurred throughout the day only for Pleuraphis. Both C3 species had smaller CO2 effects during dry periods than wet. Leaf temperature did not differ significantly between elevated and ambient CO2 for any species. Comparisons of blower-control and nonring plots indicated that the FACE apparatus did not confound our results. All three species exhibited decreased leaf conductance under elevated CO2, although reductions were not uniform during the day or among years. Nonetheless, leaf energy balance was only minimally changed for these microphyllous desert perennials.

  17. A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells.

    PubMed

    Lan, Rong; Cowin, Peter I; Sengodan, Sivaprakash; Tao, Shanwen

    2016-01-01

    Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3-δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3-δ (SFCN) exhibits a conductivity of 63 Scm(-1)and 60 Scm(-1) at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3-δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3-δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3-δ as the cathode achieved a power density of 423 mWcm(-2) at 700 °C indicating that SFCN is a promising anode for SOFCs. PMID:27545200

  18. A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells

    PubMed Central

    Lan, Rong; Cowin, Peter I.; Sengodan, Sivaprakash; Tao, Shanwen

    2016-01-01

    Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3−δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3−δ (SFCN) exhibits a conductivity of 63 Scm−1and 60 Scm−1 at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3−δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3−δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3−δ as the cathode achieved a power density of 423 mWcm−2 at 700 °C indicating that SFCN is a promising anode for SOFCs. PMID:27545200

  19. A morphology, porosity and surface conductive layer optimized MnCo2O4 microsphere for compatible superior Li(+) ion/air rechargeable battery electrode materials.

    PubMed

    Yun, Young Jun; Kim, Jin Kyu; Ju, Ji Young; Unithrattil, Sanjith; Lee, Sun Sook; Kang, Yongku; Jung, Ha-Kyun; Park, Jin-Seong; Im, Won Bin; Choi, Sungho

    2016-03-15

    Uniform surface conductive layers with porous morphology-conserved MnCo2O4 microspheres are successfully synthesized, and their electrochemical performances are thoroughly investigated. It is found that the microwave-assisted hydrothermally grown MnCo2O4 using citric acid as the carbon source shows a maximum Li(+) ion lithiation/delithiation capacity of 501 mA h g(-1) at 500 mA g(-1) with stable capacity retention. Besides, the given microsphere compounds are effectively activated as air cathode catalysts in Li-O2 batteries with reduced charge overpotentials and improved cycling performance. We believe that such an affordable enhanced performance results from the appropriate quasi-hollow nature of MnCo2O4 microspheres, which can effectively mitigate the large volume change of electrodes during Li(+) migration and/or enhance the surface transport of the LiOx species in Li-air batteries. Thus, the rationally designed porous media for the improved Li(+) electrochemical reaction highlight the importance of the 3D macropores, the high specific area and uniformly overcoated conductive layer for the promising Li(+) redox reaction platforms. PMID:26877264

  20. Pausing at the Threshold

    ERIC Educational Resources Information Center

    Morgan, Patrick K.

    2015-01-01

    Since about 2003, the notion of threshold concepts--the central ideas in any field that change how learners think about other ideas--have become difficult to escape at library conferences and in general information literacy discourse. Their visibility will likely only increase because threshold concepts figure prominently in the Framework for…

  1. Threshold Concepts in Economics

    ERIC Educational Resources Information Center

    Shanahan, Martin

    2016-01-01

    Purpose: The purpose of this paper is to examine threshold concepts in the context of teaching and learning first-year university economics. It outlines some of the arguments for using threshold concepts and provides examples using opportunity cost as an exemplar in economics. Design/ Methodology/Approach: The paper provides an overview of the…

  2. Bayesian Threshold Estimation

    ERIC Educational Resources Information Center

    Gustafson, S. C.; Costello, C. S.; Like, E. C.; Pierce, S. J.; Shenoy, K. N.

    2009-01-01

    Bayesian estimation of a threshold time (hereafter simply threshold) for the receipt of impulse signals is accomplished given the following: 1) data, consisting of the number of impulses received in a time interval from zero to one and the time of the largest time impulse; 2) a model, consisting of a uniform probability density of impulse time…

  3. 40 CFR 98.151 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ....151 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING HCFC-22 Production and HFC-23 Destruction § 98.151 Reporting threshold... HFC-23 destruction process and the facility meets the requirements of either § 98.2(a)(1) or (a)(2)....

  4. 40 CFR 98.431 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.431 Section 98.431 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Importers and Exporters of Fluorinated Greenhouse Gases Contained in...

  5. 40 CFR 98.301 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Reporting threshold. 98.301 Section 98.301 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Electrical Transmission and Distribution Equipment Use § 98.301...

  6. Roots at the Percolation Threshold

    NASA Astrophysics Data System (ADS)

    Kroener, E.; Ahmed, M. A.; Kaestner, A.; Vontobel, P.; Zarebanadkouki, M.; Carminati, A.

    2014-12-01

    Much of the carbon assimilated by plants during photosynthesis is lost to the soil via rhizodepositions. One component of rhizopdeposition is mucilage, a hydrogel that dramatically alters the soil physical properties. Mucilage was assumed to explain unexpectedly low rhizosphere rewetting rates during irrigation (Carminati et al. 2010) and temporarily water repellency in the rhizosphere after severe drying (Moradi et al. 2012).Here, we present an experimental and theoretical study for the rewetting behaviour of a soil mixed with mucilage, which was used as an analogue of the rhizosphere. Our samples were made of two layers of untreated soils separated by a thin layer (ca. 1 mm) of soil treated with mucilage. We prepared soil columns of varying particle size, mucilage concentration and height of the middle layer above the water table. The dry soil columns were re-wetted by capillary rise from the bottom.The rewetting of the middle layer showed a distinct dual behavior. For mucilage concentrations lower than a certain threshold, water could cross the thin layer almost immediately after rewetting of bulk soil. At slightly higher mucilage concentrations, the thin layer was almost impermeable. The mucilage concentration at the threshold strongly depended on particle size: the smaller the particle size the larger the soil specific surface and the more mucilage was needed to cover the entire particle surface and to induce water repellency.We applied a classic pore network model to simulate the experimental observations. In the model a certain fraction of nodes were randomly disconnected to reproduce the effect of mucilage in temporarily blocking the flow. The percolation model could qualitatively reproduce well the threshold characteristics of the experiments. Our experiments, together with former observations of water dynamics in the rhizosphere, suggest that the rhizosphere is near the percolation threshold, where small variations in mucilage concentration sensitively

  7. How well do stomatal conductance models perform on closing plant carbon budgets? A test using seedlings grown under current and elevated air temperatures

    NASA Astrophysics Data System (ADS)

    Way, Danielle A.; Oren, Ram; Kim, Hyun-Seok; Katul, Gabriel G.

    2011-12-01

    Future carbon and water fluxes within terrestrial ecosystems will be determined by how stomatal conductance (gs) responds to rising atmospheric CO2and air temperatures. While both short- and long-term CO2 effects on gs have been repeatedly studied, there are few studies on how gs acclimates to higher air temperatures. Six gs models were parameterized using leaf gas exchange data from black spruce (Picea mariana) seedlings grown from seed at ambient (22/16°C day/night) or elevated (30/24°C) air temperatures. Model performance was independently assessed by how well carbon gain from each model reproduced estimated carbon costs to close the seedlings' seasonal carbon budgets, a `long-term' indicator of success. A model holding a constant intercellular to ambient CO2ratio and the Ball-Berry model (based on stomatal responses to relative humidity) could not close the carbon balance for either treatment, while the Jarvis-Oren model (based on stomatal responses to vapor pressure deficit,D) and a model assuming a constant gs each closed the carbon balance for one treatment. Two models, both based on gs responses to D, performed best overall, estimating carbon uptake within 10% of carbon costs for both treatments: the Leuning model and a linear optimization model that maximizes carbon gain per unit water loss. Since gsresponses in the optimization model are not a priori assumed, this approach can be used in modeling land-atmosphere exchange of CO2 and water in future climates.

  8. Conductivity Probe

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air.

    The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air.

    The needles on the probe are 15 millimeters (0.6 inch) long.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  9. Investigation of ULF magnetic pulsations, air conductivity changes, and infra red signatures associated with the 30 October Alum Rock M5.4 earthquake

    NASA Astrophysics Data System (ADS)

    Bleier, T.; Dunson, C.; Maniscalco, M.; Bryant, N.; Bambery, R.; Freund, F.

    2009-04-01

    Several electromagnetic signal types were observed prior to and immediately after 30 October 2007 (Local Time) M5.4 earthquake at Alum Rock, Ca with an epicenter ~15 km NE of San Jose Ca. The area where this event occurred had been monitored since November 2005 by a QuakeFinder magnetometer site, unit 609, 2 km from the epicenter. This instrument is one of 53 stations of the QuakeFinder (QF) California Magnetometer Network-CalMagNet. This station included an ultra low frequency (ULF) 3-axis induction magnetometer, a simple air conductivity sensor to measure relative airborne ion concentrations, and a geophone to identify the arrival of the P-wave from an earthquake. Similar in frequency content to the increased ULF activity reported two weeks prior to the Loma Prieta M7.0 quake in 1989 (Fraser-Smith, 1990, 1991), the QF station detected activity in the 0.01-12 Hz bands, but it consisted of an increasing number of short duration (1 to 30 s duration) pulsations. The pulsations peaked around 13 days prior to the event. The amplitudes of the pulses were strong, (3-20 nT), compared to the average ambient noise at the site, (10-250 pT), which included a component arising from the Bay Area Rapid Transit (BART) operations. The QF station also detected different pulse shapes, e.g. negative or positive only polarity, with some pulses including a combination of positive and negative. Typical pulse counts over the previous year ranged from 0-15 per day, while the count rose to 176 (east-west channel) on 17 October, 13 days prior to the quake. The air conductivity sensor saturated for over 14 h during the night and morning prior to the quake, which occurred at 20:29 LT. Anomalous IR signatures were also observed in the general area, within 50 km of the epicenter, during the 2 weeks prior to the quake. These three simultaneous EM phenomena were compared with data collected over a 1-2-year period at the site. The data was also compared against accounts of air ionization reported

  10. Evaluation of different methods for determining growing degree-day thresholds in apricot cultivars

    NASA Astrophysics Data System (ADS)

    Ruml, Mirjana; Vuković, Ana; Milatović, Dragan

    2010-07-01

    The aim of this study was to examine different methods for determining growing degree-day (GDD) threshold temperatures for two phenological stages (full bloom and harvest) and select the optimal thresholds for a greater number of apricot ( Prunus armeniaca L.) cultivars grown in the Belgrade region. A 10-year data series were used to conduct the study. Several commonly used methods to determine the threshold temperatures from field observation were evaluated: (1) the least standard deviation in GDD; (2) the least standard deviation in days; (3) the least coefficient of variation in GDD; (4) regression coefficient; (5) the least standard deviation in days with a mean temperature above the threshold; (6) the least coefficient of variation in days with a mean temperature above the threshold; and (7) the smallest root mean square error between the observed and predicted number of days. In addition, two methods for calculating daily GDD, and two methods for calculating daily mean air temperatures were tested to emphasize the differences that can arise by different interpretations of basic GDD equation. The best agreement with observations was attained by method (7). The lower threshold temperature obtained by this method differed among cultivars from -5.6 to -1.7°C for full bloom, and from -0.5 to 6.6°C for harvest. However, the “Null” method (lower threshold set to 0°C) and “Fixed Value” method (lower threshold set to -2°C for full bloom and to 3°C for harvest) gave very good results. The limitations of the widely used method (1) and methods (5) and (6), which generally performed worst, are discussed in the paper.

  11. Hydrodynamics of sediment threshold

    NASA Astrophysics Data System (ADS)

    Ali, Sk Zeeshan; Dey, Subhasish

    2016-07-01

    A novel hydrodynamic model for the threshold of cohesionless sediment particle motion under a steady unidirectional streamflow is presented. The hydrodynamic forces (drag and lift) acting on a solitary sediment particle resting over a closely packed bed formed by the identical sediment particles are the primary motivating forces. The drag force comprises of the form drag and form induced drag. The lift force includes the Saffman lift, Magnus lift, centrifugal lift, and turbulent lift. The points of action of the force system are appropriately obtained, for the first time, from the basics of micro-mechanics. The sediment threshold is envisioned as the rolling mode, which is the plausible mode to initiate a particle motion on the bed. The moment balance of the force system on the solitary particle about the pivoting point of rolling yields the governing equation. The conditions of sediment threshold under the hydraulically smooth, transitional, and rough flow regimes are examined. The effects of velocity fluctuations are addressed by applying the statistical theory of turbulence. This study shows that for a hindrance coefficient of 0.3, the threshold curve (threshold Shields parameter versus shear Reynolds number) has an excellent agreement with the experimental data of uniform sediments. However, most of the experimental data are bounded by the upper and lower limiting threshold curves, corresponding to the hindrance coefficients of 0.2 and 0.4, respectively. The threshold curve of this study is compared with those of previous researchers. The present model also agrees satisfactorily with the experimental data of nonuniform sediments.

  12. Mitochondrial threshold effects.

    PubMed Central

    Rossignol, Rodrigue; Faustin, Benjamin; Rocher, Christophe; Malgat, Monique; Mazat, Jean-Pierre; Letellier, Thierry

    2003-01-01

    The study of mitochondrial diseases has revealed dramatic variability in the phenotypic presentation of mitochondrial genetic defects. To attempt to understand this variability, different authors have studied energy metabolism in transmitochondrial cell lines carrying different proportions of various pathogenic mutations in their mitochondrial DNA. The same kinds of experiments have been performed on isolated mitochondria and on tissue biopsies taken from patients with mitochondrial diseases. The results have shown that, in most cases, phenotypic manifestation of the genetic defect occurs only when a threshold level is exceeded, and this phenomenon has been named the 'phenotypic threshold effect'. Subsequently, several authors showed that it was possible to inhibit considerably the activity of a respiratory chain complex, up to a critical value, without affecting the rate of mitochondrial respiration or ATP synthesis. This phenomenon was called the 'biochemical threshold effect'. More recently, quantitative analysis of the effects of various mutations in mitochondrial DNA on the rate of mitochondrial protein synthesis has revealed the existence of a 'translational threshold effect'. In this review these different mitochondrial threshold effects are discussed, along with their molecular bases and the roles that they play in the presentation of mitochondrial diseases. PMID:12467494

  13. Decreases in stomatal conductance of soybean (Glycine max) under open-air elevation of CO2 is closely coupled with decreases in ecosystem evapotranspiration

    NASA Astrophysics Data System (ADS)

    Bernacchi, C.; Kimball, B. A.; Quarles, D. R.; Long, S. P.; Ort, D. R.

    2006-12-01

    Stomatal responses to atmospheric change have been documented through a range of enclosure-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) has been shown to decrease stomatal conductance (gs) for a many species under numerous conditions. Less well understood, however, is the extent to which leaf level responses translate to changes in ecosystem evapotranspiration, ET. Since many changes at the soil, plant and canopy microclimate level may feed back on ET, it is not certain that decrease in gs will decrease ET in rainfed crops. To examine the scaling of the effect of elevated [CO2] on gs at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (ca 375 μmol CO2 mol-1 air) and elevated [CO2] (ca. 550 μmol mol^{- 1}) using Free Air CO2 Enrichment (FACE). ET was measured from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9 and 16% depending on year and despite large increases in photosynthesis and seed yield. Although elevated [CO2] increased leaf area and canopy temperature (Tc), ET was closely coupled (0.78) to gs of the upper canopy leaves; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses which suggest that, despite system feedbacks, decreased gs at elevated [CO2] results in decreased transfer of water vapor to the atmosphere.

  14. Decreases in stomatal conductance of soybean under open-air elevation of [CO2] are closely coupled with decreases in ecosystem evapotranspiration.

    PubMed

    Bernacchi, Carl J; Kimball, Bruce A; Quarles, Devin R; Long, Stephen P; Ort, Donald R

    2007-01-01

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO(2) ([CO(2)]) have been shown to decrease stomatal conductance (g(s)) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in g(s) will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO(2)] on g(s) at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 micromol CO(2) mol(-1) air) and elevated [CO(2)] (approximately 550 micromol mol(-1)) using free air CO(2) enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO(2)] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with g(s) of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in g(s) results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO(2)]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased g(s) of upper canopy leaves at elevated [CO(2)] results in decreased transfer of water vapor to the atmosphere. PMID:17114275

  15. Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration12[W][OA

    PubMed Central

    Bernacchi, Carl J.; Kimball, Bruce A.; Quarles, Devin R.; Long, Stephen P.; Ort, Donald R.

    2007-01-01

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) have been shown to decrease stomatal conductance (gs) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in gs will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO2] on gs at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 μmol CO2 mol−1 air) and elevated [CO2] (approximately 550 μmol mol−1) using free air CO2 enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with gs of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in gs results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased gs of upper canopy leaves at elevated [CO2] results in decreased transfer of water vapor to the atmosphere. PMID:17114275

  16. Yield threshold decision framework

    SciTech Connect

    Judd, B.R.; Younker, L.W.; Hannon, W.J.

    1989-08-17

    The USA is developing a decision analysis framework for evaluating the relative value of lower yield thresholds and related verification policies. The framework facilitates systematic analysis of the major issues in the yield threshold decision. The framework can be used to evaluate options proposed either in the inter-agency process or in the negotiations. In addition, the framework can measure the importance of uncertainties and alternative judgments, and thereby determine the advantages of additional research. Since the model is explicit and quantitative, it provides a rational, defensible approach for reaching important treaty and verification decisions. 9 figs.

  17. Results of borehole geophysical logging and hydraulic tests conducted in Area D supply wells, former US Naval Air Warfare Center, Warminster, Pennsylvania

    USGS Publications Warehouse

    Sloto, Ronald A.; Grazul, Kevin E.

    1998-01-01

    Borehole geophysical logging, aquifer tests, and aquifer-isolation (packer) tests were conducted in four supply wells at the former U.S. Naval Air Warfare Center (NAWC) in Warminster, PA to identify the depth and yield of water-bearing zones, occurrence of borehole flow, and effect of pumping on nearby wells. The study was conducted as part of an ongoing evaluation of ground-water contamination at the NAWC. Caliper, natural-gamma, single-point resistance, fluid resistivity, and fluid temperature logs and borehole television surveys were run in the supply wells, which range in depth from 242 to 560 ft (feet). Acoustic borehole televiewer and borehole deviation logs were run in two of the wells. The direction and rate of borehole-fluid movement under non-pumping conditions were measured with a high-resolution heatpulse flowmeter. The logs were used to locate water-bearing fractures, determine probable zones of vertical borehole-fluid movement, and determine the depth to set packers. An aquifer test was conducted in each well to determine open-hole specific capacity and the effect of pumping the open borehole on water levels in nearby wells. Specific capacities ranged from 0.21 to 1.7 (gal/min)/ft (gallons per minute per foot) of drawdown. Aquifer-isolation tests were conducted in each well to determine depth-discrete specific capacities and to determine the effect of pumping an individual fracture or fracture zone on water levels in nearby wells. Specific capacities of individual fractures and fracture zones ranged from 0 to 2.3 (gal/min)/ft. Most fractures identified as water-producing or water-receiving zones by borehole geophysical methods produced water when isolated and pumped. All hydrologically active fractures below 250 ft below land surface were identified as water-receiving zones and produced little water when isolated and pumped. In the two wells greater then 540 ft deep, downward borehole flow to the deep water-receiving fractures is caused by a large

  18. Long-Term Growth of Soybean at Elevated [CO2] Does not Cause Acclimation of Stomatal Conductance Under Fully Open-air Conditions.

    NASA Astrophysics Data System (ADS)

    Leakey, A. D.; Bernacchi, C. J.; Ort, D. R.; Long, S. P.

    2008-12-01

    Accurately predicting plant function and global biogeochemical cycles later this century will be complicated if stomatal conductance (gs) acclimates to growth at elevated [CO2], in the sense of a long-term alteration of the response of gs to [CO2], humidity (h) and/or photosynthetic rate (A). If so, photosynthetic and stomatal models will require parameterization at each growth [CO2] of interest. Photosynthetic acclimation to long-term growth at elevated [CO2] occurs frequently. Acclimation of gs has rarely been examined, even though stomatal density commonly changes with growth [CO2]. Soybean was grown under field conditions at ambient [CO2] (378 μmol mol-1) and elevated [CO2] (552 μmol mol-1) using Free-Air [CO2] Enrichment (FACE). This study tested for stomatal acclimation by parameterizing and validating the widely used Ball et al. model (1987, Progress in Photosynthesis Research, Vol IV, 221-224) with measurements of leaf gas exchange. The dependence of gs on A, h and [CO2] at the leaf surface was unaltered by long-term growth at elevated [CO2]. This suggests that the commonly observed decrease in gs under elevated [CO2] is due entirely to the direct instantaneous effect of [CO2] on gs and that there is no longer-term acclimation of stomatal conductance independent of photosynthetic acclimation. The Ball et al. (1987) model accurately predicted gs for soybean growing under ambient and elevated [CO2] in the field. Model parameters under ambient and elevated [CO2] were indistinguishable, demonstrating that stomatal function under ambient and elevated [CO2] could be modeled without the need for parameterization at each growth [CO2].

  19. Elaborating on Threshold Concepts

    ERIC Educational Resources Information Center

    Rountree, Janet; Robins, Anthony; Rountree, Nathan

    2013-01-01

    We propose an expanded definition of Threshold Concepts (TCs) that requires the successful acquisition and internalisation not only of knowledge, but also its practical elaboration in the domains of applied strategies and mental models. This richer definition allows us to clarify the relationship between TCs and Fundamental Ideas, and to account…

  20. Bone sarcoma in humans induced by radium: A threshold response?

    SciTech Connect

    Rowland, R.E.

    1996-08-01

    The radium 226 and radium 228 have induced malignancies in the skeleton (primarily bone sarcomas) of humans. They have also induced carcinomas in the paranasal sinuses and mastoid air cells. There is no evidence that any leukemias or any other solid cancers have been induced by internally deposited radium. This paper discuses a study conducted on the dial painter population. This study made a concerted effort to verify, for each of the measured radium cases, the published values of the skeletal dose and the initial intake of radium. These were derived from body content measurements made some 40 years after the radium intake. Corrections to the assumed radium retention function resulted in a considerable number of dose changes. These changes have changed the shape of the dose response function. It now appears that the induction of bone sarcomas is a threshold process.

  1. Ultrashort laser pulse ablation of copper, silicon and gelatin: effect of the pulse duration on the ablation thresholds and the incubation coefficients

    NASA Astrophysics Data System (ADS)

    Nathala, Chandra S. R.; Ajami, Ali; Husinsky, Wolfgang; Farooq, Bilal; Kudryashov, Sergey I.; Daskalova, Albena; Bliznakova, Irina; Assion, Andreas

    2016-02-01

    In this paper, the influence of the pulse duration on the ablation threshold and the incubation coefficient was investigated for three different types of materials: metal (copper), semiconductor (silicon) and biopolymer (gelatin). Ablation threshold values and the incubation coefficients have been measured for multiple Ti:sapphire laser pulses (3 to 1000 pulses) and for four different pulse durations (10, 30, 250 and 550 fs). The ablation threshold fluence was determined by extrapolation of curves from squared crater diameter versus fluence plots. For copper and silicon, the experiments were conducted in vacuum and for gelatin in air. For all materials, the ablation threshold fluence increases with the pulse duration. For copper, the threshold increases as τ 0.05, for silicon as τ 0.12 and for gelatin as τ 0.22. By extrapolating the curves of the threshold fluence versus number of pulses, the single-shot threshold fluence was determined for each sample. For 30 fs pulses, the single-shot threshold fluences were found to be 0.79, 0.35, and 0.99 J/cm2 and the incubation coefficients were found to be 0.75, 0.83 and 0.68 for copper, silicon and gelatin, respectively.

  2. Use of implantable temperature transponders for the determination of air cell temperature, eggshell water vapor conductance, and their functional relationships in embryonated broiler hatching eggs.

    PubMed

    Pulikanti, R; Peebles, E D; Gerard, P D

    2011-06-01

    Broiler hatching eggs obtained from a 29-wk-old Ross 308 breeder flock were weighed and set on 8 tray levels (60 eggs/level) of a single incubator. On d 10.5 of incubation, the eggs were weighed, and temperature transponders were implanted in the air cells of 4 randomly selected embryonated eggs per tray level for determination of internal egg temperature (IT). Two water-filled vials per tray level containing transponders were also placed within 5 cm of the implanted eggs for determination of external egg temperature (ET). Between 10.5 and 18.5 d of incubation, ET and IT were recorded every 12 h. Egg weights and embryo survival were determined on 10.5 and 18.5 d of incubation and were used for the calculation of average daily incubational weight loss of embryonated eggs (EWL) and average daily percentage of EWL. Approximately 75% (24 out of 32) of the embryos in the implanted eggs survived through d 18.5 of incubation. Mean ET and IT were used to calculate the water vapor pressure gradient across the eggshell, which was subsequently used with EWL to calculate eggshell water vapor conductance (G(H2O)) and specific G(H2O) (g(H2O); G(H2O) adjusted to a 100-g set egg weight basis). Mean percentage of EWL, ET, IT, G(H2O), and g(H2O) for the 10.5- to 18.5-d incubation period were 0.546 ± 0.02%, 37.1 ± 0.03°C, 37.8 ± 0.09°C, 13.9 ± 0.47 mg of H(2)O/d per Torr, and 24.5 ± 0.75 mg of H(2)O/d per Torr per 100 g, respectively. It was concluded that temperature transponders may be successfully implanted in the air cells of broiler hatching eggs to determine ET, IT, G(H2O), and g(H2O) in Ross × Ross 308 broiler hatching eggs. Nevertheless, increased embryo survivability by further improving the implantation procedure may increase the practicality of temperature transponder use in commercial settings. PMID:21597058

  3. Network problem threshold

    NASA Technical Reports Server (NTRS)

    Gejji, Raghvendra, R.

    1992-01-01

    Network transmission errors such as collisions, CRC errors, misalignment, etc. are statistical in nature. Although errors can vary randomly, a high level of errors does indicate specific network problems, e.g. equipment failure. In this project, we have studied the random nature of collisions theoretically as well as by gathering statistics, and established a numerical threshold above which a network problem is indicated with high probability.

  4. Elaborating on threshold concepts

    NASA Astrophysics Data System (ADS)

    Rountree, Janet; Robins, Anthony; Rountree, Nathan

    2013-09-01

    We propose an expanded definition of Threshold Concepts (TCs) that requires the successful acquisition and internalisation not only of knowledge, but also its practical elaboration in the domains of applied strategies and mental models. This richer definition allows us to clarify the relationship between TCs and Fundamental Ideas, and to account for both the important and the problematic characteristics of TCs in terms of the Knowledge/Strategies/Mental Models Framework defined in previous work.

  5. Long-term growth of soybean at elevated [CO2] does not cause acclimation of stomatal conductance under fully open-air conditions.

    PubMed

    Leakey, Andrew D B; Bernacchi, Carl J; Ort, Donald R; Long, Stephen P

    2006-09-01

    Accurately predicting plant function and global biogeochemical cycles later in this century will be complicated if stomatal conductance (g(s)) acclimates to growth at elevated [CO(2)], in the sense of a long-term alteration of the response of g(s) to [CO(2)], humidity (h) and/or photosynthetic rate (A). If so, photosynthetic and stomatal models will require parameterization at each growth [CO(2)] of interest. Photosynthetic acclimation to long-term growth at elevated [CO(2)] occurs frequently. Acclimation of g(s) has rarely been examined, even though stomatal density commonly changes with growth [CO(2)]. Soybean was grown under field conditions at ambient [CO(2)] (378 micromol mol(-1)) and elevated [CO(2)] (552 micromol mol(-1)) using free-air [CO(2)] enrichment (FACE). This study tested for stomatal acclimation by parameterizing and validating the widely used Ball et al. model (1987, Progress in Photosynthesis Research, vol IV, 221-224) with measurements of leaf gas exchange. The dependence of g(s) on A, h and [CO(2)] at the leaf surface was unaltered by long-term growth at elevated [CO(2)]. This suggests that the commonly observed decrease in g(s) under elevated [CO(2)] is due entirely to the direct instantaneous effect of [CO(2)] on g(s) and that there is no longer-term acclimation of g(s) independent of photosynthetic acclimation. The model accurately predicted g(s) for soybean growing under ambient and elevated [CO(2)] in the field. Model parameters under ambient and elevated [CO(2)] were indistinguishable, demonstrating that stomatal function under ambient and elevated [CO(2)] could be modelled without the need for parameterization at each growth [CO(2)]. PMID:16913868

  6. A Review and Analysis of Remote Sensing Capability for Air Quality Measurements as a Potential Decision Support Tool Conducted by the NASA DEVELOP Program

    NASA Technical Reports Server (NTRS)

    Ross, A.; Richards, A.; Keith, K.; Frew, C.; Boseck, J.; Sutton, S.; Watts, C.; Rickman, D.

    2007-01-01

    This project focused on a comprehensive utilization of air quality model products as decision support tools (DST) needed for public health applications. A review of past and future air quality measurement methods and their uncertainty, along with the relationship of air quality to national and global public health, is vital. This project described current and future NASA satellite remote sensing and ground sensing capabilities and the potential for using these sensors to enhance the prediction, prevention, and control of public health effects that result from poor air quality. The qualitative uncertainty of current satellite remotely sensed air quality, the ground-based remotely sensed air quality, the air quality/public health model, and the decision making process is evaluated in this study. Current peer-reviewed literature suggests that remotely sensed air quality parameters correlate well with ground-based sensor data. A satellite remote-sensed and ground-sensed data complement is needed to enhance the models/tools used by policy makers for the protection of national and global public health communities

  7. Manage postharvest deficit irrigation of peach trees using canopy to air temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A field study was conducted to use mid-day canopy to air temperature difference (delta T) to manage postharvest deficit irrigation of peach trees in San Joaquin Valley of California and its performance was evaluated. Delta T thresholds were selected, based on previous years’ stem water potential and...

  8. Crossing Thresholds: Identifying Conceptual Transitions in Postsecondary Teaching

    ERIC Educational Resources Information Center

    Wilcox, Susan; Leger, Andy B.

    2013-01-01

    In this paper we report on research we conducted to begin the process of identifying threshold concepts in the field of postsecondary teaching. Meyer & Land (2006) propose that within all disciplinary fields there seem to be particular "threshold concepts" that serve as gateways, opening up new and previously inaccessible ways of…

  9. Coloring geographical threshold graphs

    SciTech Connect

    Bradonjic, Milan; Percus, Allon; Muller, Tobias

    2008-01-01

    We propose a coloring algorithm for sparse random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). Here, we analyze the GTG coloring algorithm together with the graph's clique number, showing formally that in spite of the differences in structure between GTG and RGG, the asymptotic behavior of the chromatic number is identical: {chi}1n 1n n / 1n n (1 + {omicron}(1)). Finally, we consider the leading corrections to this expression, again using the coloring algorithm and clique number to provide bounds on the chromatic number. We show that the gap between the lower and upper bound is within C 1n n / (1n 1n n){sup 2}, and specify the constant C.

  10. Laser threshold magnetometry

    NASA Astrophysics Data System (ADS)

    Jeske, Jan; Cole, Jared H.; Greentree, Andrew D.

    2016-01-01

    We propose a new type of sensor, which uses diamond containing the optically active nitrogen-vacancy (NV-) centres as a laser medium. The magnetometer can be operated at room-temperature and generates light that can be readily fibre coupled, thereby permitting use in industrial applications and remote sensing. By combining laser pumping with a radio-frequency Rabi-drive field, an external magnetic field changes the fluorescence of the NV- centres. We use this change in fluorescence level to push the laser above threshold, turning it on with an intensity controlled by the external magnetic field, which provides a coherent amplification of the readout signal with very high contrast. This mechanism is qualitatively different from conventional NV--based magnetometers which use fluorescence measurements, based on incoherent photon emission. We term our approach laser threshold magnetometer (LTM). We predict that an NV--based LTM with a volume of 1 mm3 can achieve shot-noise limited dc sensitivity of 1.86 fT /\\sqrt{{{Hz}}} and ac sensitivity of 3.97 fT /\\sqrt{{{Hz}}}.

  11. Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz tone pips

    PubMed Central

    Todd, N.P.M.; Paillard, A.C.; Kluk, K.; Whittle, E.; Colebatch, J.G.

    2014-01-01

    Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulation and by conducting a source analysis of the resulting evoked potentials of short and long latency. Ten healthy, right-handed subjects were recruited and evoked potentials were recorded to both left- and right-ear sound stimulation, above and below vestibular threshold. Below VEMP threshold, typical AEPs were recorded, consisting of mid-latency (MLR) waves Na and Pa followed by long latency AEPs (LAEPs) N1 and P2. In the supra-threshold condition, the expected changes in morphology were observed, consisting of: (1) short-latency vestibular evoked potentials (VsEPs) which have no auditory correlate, i.e. the ocular VEMP (OVEMP) and inion response related potentials; (2) a later deflection, labelled N42/P52, followed by the LAEPs N1 and P2. Statistical analysis of the vestibular dependent responses indicated a contralateral effect for inion related short-latency responses and a left-ear/right-hemisphere advantage for the long-latency responses. Source analysis indicated that the short-latency effects may be mediated by a contralateral projection to left cerebellum, while the long-latency effects were mediated by a contralateral projection to right cingulate cortex. In addition we found evidence of a possible vestibular contribution to the auditory T-complex in radial temporal lobe sources. These last results raise the possibility that acoustic activation of the otolith organs could potentially contribute to auditory processing. PMID:24699384

  12. Roots at the percolation threshold

    NASA Astrophysics Data System (ADS)

    Kroener, Eva; Ahmed, Mutez Ali; Carminati, Andrea

    2015-04-01

    The rhizosphere is the layer of soil around the roots where complex and dynamic interactions between plants and soil affect the capacity of plants to take up water. The physical properties of the rhizosphere are affected by mucilage, a gel exuded by roots. Mucilage can absorb large volumes of water, but it becomes hydrophobic after drying. We use a percolation model to describe the rewetting of dry rhizosphere. We find that at a critical mucilage concentration the rhizosphere becomes impermeable. The critical mucilage concentration depends on the radius of the soil particle size. Capillary rise experiments with neutron radiography prove that for concentrations below the critical mucilage concentration water could easily cross the rhizosphere, while above the critical concentration water could no longer percolate through it. Our studies, together with former observations of water dynamics in the rhizosphere, suggest that the rhizosphere is near the percolation threshold, where small variations in mucilage concentration sensitively alter the soil hydraulic conductivity. Is mucilage exudation a plant mechanism to efficiently control the rhizosphere conductivity and the access to water?

  13. Roots at the percolation threshold.

    PubMed

    Kroener, Eva; Ahmed, Mutez Ali; Carminati, Andrea

    2015-04-01

    The rhizosphere is the layer of soil around the roots where complex and dynamic interactions between plants and soil affect the capacity of plants to take up water. The physical properties of the rhizosphere are affected by mucilage, a gel exuded by roots. Mucilage can absorb large volumes of water, but it becomes hydrophobic after drying. We use a percolation model to describe the rewetting of dry rhizosphere. We find that at a critical mucilage concentration the rhizosphere becomes impermeable. The critical mucilage concentration depends on the radius of the soil particle size. Capillary rise experiments with neutron radiography prove that for concentrations below the critical mucilage concentration water could easily cross the rhizosphere, while above the critical concentration water could no longer percolate through it. Our studies, together with former observations of water dynamics in the rhizosphere, suggest that the rhizosphere is near the percolation threshold, where small variations in mucilage concentration sensitively alter the soil hydraulic conductivity. Is mucilage exudation a plant mechanism to efficiently control the rhizosphere conductivity and the access to water? PMID:25974526

  14. Oscillatory Threshold Logic

    PubMed Central

    Borresen, Jon; Lynch, Stephen

    2012-01-01

    In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory. PMID:23173034

  15. Wind tunnel investigation of an all flush orifice air data system for a large subsonic aircraft. [conducted in a Langley 8 foot transonic pressure tunnel

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Flechner, S. G.; Siemers, P. M., III

    1980-01-01

    The results of a wind tunnel investigation on an all flush orifice air data system for use on a KC-135A aircraft are presented. The investigation was performed to determine the applicability of fixed all flush orifice air data systems that use only aircraft surfaces for orifices on the nose of the model (in a configuration similar to that of the shuttle entry air data system) provided the measurements required for the determination of stagnation pressure, angle of attack, and angle of sideslip. For the measurement of static pressure, additional flush orifices in positions on the sides of the fuselage corresponding to those in a standard pitot-static system were required. An acceptable but less accurate system, consisting of orifices only on the nose of the model, is defined and discussed.

  16. Crack Growth Behavior in the Threshold Region for High Cycle Fatigue Loading

    NASA Technical Reports Server (NTRS)

    Forman, R. G.; Zanganeh, M.

    2014-01-01

    This paper describes the results of a research program conducted to improve the understanding of fatigue crack growth rate behavior in the threshold growth rate region and to answer a question on the validity of threshold region test data. The validity question relates to the view held by some experimentalists that using the ASTM load shedding test method does not produce valid threshold test results and material properties. The question involves the fanning behavior observed in threshold region of da/dN plots for some materials in which the low R-ratio data fans out from the high R-ratio data. This fanning behavior or elevation of threshold values in the low R-ratio tests is generally assumed to be caused by an increase in crack closure in the low R-ratio tests. Also, the increase in crack closure is assumed by some experimentalists to result from using the ASTM load shedding test procedure. The belief is that this procedure induces load history effects which cause remote closure from plasticity and/or roughness changes in the surface morphology. However, experimental studies performed by the authors have shown that the increase in crack closure is a result of extensive crack tip bifurcations that can occur in some materials, particularly in aluminum alloys, when the crack tip cyclic yield zone size becomes less than the grain size of the alloy. This behavior is related to the high stacking fault energy (SFE) property of aluminum alloys which results in easier slip characteristics. Therefore, the fanning behavior which occurs in aluminum alloys is a function of intrinsic dislocation property of the alloy, and therefore, the fanned data does represent the true threshold properties of the material. However, for the corrosion sensitive steel alloys tested in laboratory air, the occurrence of fanning results from fretting corrosion at the crack tips, and these results should not be considered to be representative of valid threshold properties because the fanning is

  17. Effect of oxidation kinetics on the near threshold fatigue crack growth behavior of a nickel base superalloy

    SciTech Connect

    Yuen, J.L.; Roy, P.; Nix, W.D.

    1984-09-01

    The influence of oxidation kinetics on the near threshold fatigue crack growth behavior of a nickel base precipitation hardened superalloy was studied in air from 427 to 649 C. The tests were conducted at 100 Hz and at load ratios of 0.1 and 0.5. The threshold values of the alternating stress intensity factor were found to increase with temperature. This behavior is attributed to oxide deposits that form on the freshly created fracture surfaces which enhance crack closure. As determined from secondary ion mass spectrometry, the oxide thickness was uniform over the crack length and was of the order of the maximum crack tip opening displacement at threshold. Oxidation kinetics were important in thickening the oxide on the fracture surfaces at elevated temperatures, whereas at room temperature, the oxide deposits at near threshold fatigue crack growth rates and at low load ratios were thickened by an oxide fretting mechanism. The effect of fracture surface roughness-induced crack closure on the near threshold fatigue crack growth behavior is also discussed. 27 references.

  18. Effect of oxidation kinetics on the near threshold fatigue crack growth behavior of a nickel base superalloy

    NASA Astrophysics Data System (ADS)

    Yuen, J. L.; Roy, P.; Nix, W. D.

    1984-09-01

    The influence of oxidation kinetics on the near threshold fatigue crack growth behavior of a nickel base precipitation hardened superalloy was studied in air from 427° to 649 °C. The tests were conducted at 100 Hz and at load ratios of 0.1 and 0.5. The threshold ΔK values were found to increase with temperature. This behavior is attributed to oxide deposits that form on the freshly created fracture surfaces which enhance crack closure. As determined from secondary ion mass spectrometry, the oxide thickness was uniform over the crack length and was of the order of the maximum crack tip opening displacement at threshold. Oxidation kinetics were important in thickening the oxide on the fracture surfaces at elevated temperatures, whereas at room temperature, the oxide deposits at near threshold fatigue crack growth rates and at low load ratios were thickened by an oxide fretting mechanism. The effect of fracture surface roughness-induced crack closure on the near threshold fatigue crack growth behavior is also discussed.

  19. New Titan Saltation Threshold Experiments: Investigating Current and Past Climates

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Burr, D. M.; Marshall, J.; Smith, J. K.; Emery, J. P.; Horst, S. M.; Nield, E.; Yu, X.

    2015-12-01

    Titan exhibits aeolian sand dunes that cover ~20% of its surface, attesting to significant sediment transport by the wind. Recent experiments in the Titan Wind Tunnel (TWT) at NASA Ames Research Center [1,2] found that the threshold friction speed needed to detach Titanian "sand" is about 50% higher than previous estimates based on theory alone [3], a result that might be explained by the low ratio of particle to fluid density on the body [1]. Following the successful completion of the initial Titan threshold tests, we are conducting new experiments that expand the pressure range above and below current Titan values. The basic experimental techniques are described in [1], with minor updates to the instrumentation as described in [2]. To reproduce the kinematic viscosity and particle friction Reynolds number equivalent to that expected for Titan's nitrogen atmosphere at 1.4 bars and 94 K requires that TWT be pressurized to 12.5 bars for air at 293K. In addition to running experiments at this pressure to reproduce previous results [1] and investigate low density (high density ratio) materials, TWT pressures of 3 and 8 bars are in the experimental matrix to understand threshold under past Titan conditions when the atmospheric pressure may have been lower [4]. Higher pressures, at 15 and 20 bars in TWT, are also being run to understand the putative effects of low density ratio conditions. Our experimental matrix for this follow-on work uses some of the same materials as previously used, including walnut shells, basalt, quartz, glass spheres, and various low density materials to better simulate the gravity-equivalent weight of Titan sand. For these experiments, the TWT is now equipped with a new high pressure Tavis transducer with sufficient sensitivity to measure freestream speeds of less than 0.5 m s-1 at 12.5 bars. New techniques include video documentation of the experiments. We are also investigating methods of measuring humidity of the wind tunnel environment and

  20. Learning foraging thresholds for lizards

    SciTech Connect

    Goldberg, L.A.; Hart, W.E.; Wilson, D.B.

    1996-01-12

    This work gives a proof of convergence for a randomized learning algorithm that describes how anoles (lizards found in the Carribean) learn a foraging threshold distance. This model assumes that an anole will pursue a prey if and only if it is within this threshold of the anole`s perch. This learning algorithm was proposed by the biologist Roughgarden and his colleagues. They experimentally confirmed that this algorithm quickly converges to the foraging threshold that is predicted by optimal foraging theory our analysis provides an analytic confirmation that the learning algorithm converses to this optimal foraging threshold with high probability.

  1. Hairpin Vortex Regeneration Threshold

    NASA Astrophysics Data System (ADS)

    Sabatino, Daniel; Maharjan, Rijan

    2015-11-01

    A free surface water channel is used to study hairpin vortex formation created by fluid injection through a narrow slot into a laminar boundary layer. Particle image velocimetry is used to calculate the circulation of the primary hairpin vortex head which is found to monotonically decrease in strength with downstream distance. When a secondary hairpin vortex is formed upstream of the primary vortex, the circulation strength of the head is comparable to the strength of the primary head at the time of regeneration. However, the legs of the primary vortex strengthen up to the moment the secondary hairpin is generated. Although the peak circulation in the legs is not directly correlated to the strength of the original elongated ring vortex, when the circulation is scaled with the injection momentum ratio it is linearly related to scaled injection time. It is proposed that the injection momentum ratio and nondimensionalized injection time based on the wall normal penetration time can be used to identify threshold conditions which produce a secondary vortex. Supported by the National Science Foundation under Grant CBET- 1040236.

  2. Probabilistic Threshold Criterion

    SciTech Connect

    Gresshoff, M; Hrousis, C A

    2010-03-09

    The Probabilistic Shock Threshold Criterion (PSTC) Project at LLNL develops phenomenological criteria for estimating safety or performance margin on high explosive (HE) initiation in the shock initiation regime, creating tools for safety assessment and design of initiation systems and HE trains in general. Until recently, there has been little foundation for probabilistic assessment of HE initiation scenarios. This work attempts to use probabilistic information that is available from both historic and ongoing tests to develop a basis for such assessment. Current PSTC approaches start with the functional form of the James Initiation Criterion as a backbone, and generalize to include varying areas of initiation and provide a probabilistic response based on test data for 1.8 g/cc (Ultrafine) 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and LX-17 (92.5% TATB, 7.5% Kel-F 800 binder). Application of the PSTC methodology is presented investigating the safety and performance of a flying plate detonator and the margin of an Ultrafine TATB booster initiating LX-17.

  3. Martian dust threshold measurements: Simulations under heated surface conditions

    NASA Technical Reports Server (NTRS)

    White, Bruce R.; Greeley, Ronald; Leach, Rodman N.

    1991-01-01

    Diurnal changes in solar radiation on Mars set up a cycle of cooling and heating of the planetary boundary layer, this effect strongly influences the wind field. The stratification of the air layer is stable in early morning since the ground is cooler than the air above it. When the ground is heated and becomes warmer than the air its heat is transferred to the air above it. The heated parcels of air near the surface will, in effect, increase the near surface wind speed or increase the aeolian surface stress the wind has upon the surface when compared to an unheated or cooled surface. This means that for the same wind speed at a fixed height above the surface, ground-level shear stress will be greater for the heated surface than an unheated surface. Thus, it is possible to obtain saltation threshold conditions at lower mean wind speeds when the surface is heated. Even though the mean wind speed is less when the surface is heated, the surface shear stress required to initiate particle movement remains the same in both cases. To investigate this phenomenon, low-density surface dust aeolian threshold measurements have been made in the MARSWIT wind tunnel located at NASA Ames Research Center, Moffett Field, California. The first series of tests examined threshold values of the 100 micron sand material. At 13 mb surface pressure the unheated surface had a threshold friction speed of 2.93 m/s (and approximately corresponded to a velocity of 41.4 m/s at a height of 1 meter) while the heated surface equivalent bulk Richardson number of -0.02, yielded a threshold friction speed of 2.67 m/s (and approximately corresponded to a velocity of 38.0 m/s at a height of 1 meter). This change represents an 8.8 percent decrease in threshold conditions for the heated case. The values of velocities are well within the threshold range as observed by Arvidson et al., 1983. As the surface was heated the threshold decreased. At a value of bulk Richardson number equal to -0.02 the threshold

  4. A simple method to estimate threshold friction velocity of wind erosion in the field

    NASA Astrophysics Data System (ADS)

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Munson, Seth M.; Miller, Mark E.

    2010-05-01

    This study provides a fast and easy-to-apply method to estimate threshold friction velocity (TFV) of wind erosion in the field. Wind tunnel experiments and a variety of ground measurements including air gun, pocket penetrometer, torvane, and roughness chain were conducted in Moab, Utah and cross-validated in the Mojave Desert, California. Patterns between TFV and ground measurements were examined to identify the optimum method for estimating TFV. The results show that TFVs were best predicted using the air gun and penetrometer measurements in the Moab sites. This empirical method, however, systematically underestimated TFVs in the Mojave Desert sites. Further analysis showed that TFVs in the Mojave sites can be satisfactorily estimated with a correction for rock cover, which is presumably the main cause of the underestimation of TFVs. The proposed method may be also applied to estimate TFVs in environments where other non-erodible elements such as postharvest residuals are found.

  5. Percolation Threshold in Polycarbonate Nanocomposites

    NASA Astrophysics Data System (ADS)

    Ahuja, Suresh

    2014-03-01

    Nanocomposites have unique mechanical, electrical, magnetic, optical and thermal properties. Many methods could be applied to prepare polymer-inorganic nanocomposites, such as sol-gel processing, in-situ polymerization, particle in-situ formation, blending, and radiation synthesis. The analytical composite models that have been put forth include Voigt and Reuss bounds, Polymer nanocomposites offer the possibility of substantial improvements in material properties such as shear and bulk modulus, yield strength, toughness, film scratch resistance, optical properties, electrical conductivity, gas and solvent transport, with only very small amounts of nanoparticles Experimental results are compared against composite models of Hashin and Shtrikman bounds, Halpin-Tsai model, Cox model, and various Mori and Tanaka models. Examples of numerical modeling are molecular dynamics modeling and finite element modeling of reduced modulus and hardness that takes into account the modulus of the components and the effect of the interface between the hard filler and relatively soft polymer, polycarbonate. Higher nanoparticle concentration results in poor dispersion and adhesion to polymer matrix which results in lower modulus and hardness and departure from the existing composite models. As the level of silica increases beyond a threshold level, aggregates form which results in weakening of the structure. Polymer silica interface is found to be weak as silica is non-interacting promoting interfacial slip at silica-matrix junctions. Our experimental results compare favorably with those of nanocomposites of polyesters where the effect of nanoclay on composite hardness and modulus depended on dispersion of nanoclay in polyester.

  6. Life below the threshold.

    PubMed

    Castro, C

    1991-01-01

    This article explains that malnutrition, poor health, and limited educational opportunities plague Philippine children -- especially female children -- from families living below the poverty threshold. Nearly 70% of households in the Philippines do not meet the required daily level of nutritional intake. Because it is often -- and incorrectly -- assumed that women's nutritional requirements are lower than men's, women suffer higher rates of malnutrition and poor health. A 1987 study revealed that 11.7% of all elementary students were underweight and 13.9% had stunted growths. Among elementary-school girls, 17% were malnourished and 40% suffered from anemia (among lactating mothers, more than 1/2 are anemic). A 1988 Program for Decentralized Educational Development study showed that grade VI students learn only about 1/2 of what they are supposed to learn. 30% of the children enrolled in grade school drop out before they reach their senior year. The Department of Education, Culture and Sports estimates that some 2.56 million students dropped out of school in l989. That same year, some 3.7 million children were counted as part of the labor force. In Manila alone, some 60,000 children work the streets, whether doing odd jobs or begging, or turning to crime or prostitution. the article tells the story of a 12 year-old girl named Ging, a 4th grader at a public school and the oldest child in a poor family of 6 children. The undernourished Ging dreams of a good future for her family and sees education as a way out of poverty; unfortunately, her time after school is spend working in the streets or looking after her family. She considers herself luckier than many of the other children working in the streets, since she at least has a family. PMID:12285009

  7. Threshold Hypothesis: Fact or Artifact?

    ERIC Educational Resources Information Center

    Karwowski, Maciej; Gralewski, Jacek

    2013-01-01

    The threshold hypothesis (TH) assumes the existence of complex relations between creative abilities and intelligence: linear associations below 120 points of IQ and weaker or lack of associations above the threshold. However, diverse results have been obtained over the last six decades--some confirmed the hypothesis and some rejected it. In this…

  8. The Nature of Psychological Thresholds

    ERIC Educational Resources Information Center

    Rouder, Jeffrey N.; Morey, Richard D.

    2009-01-01

    Following G. T. Fechner (1966), thresholds have been conceptualized as the amount of intensity needed to transition between mental states, such as between a states of unconsciousness and consciousness. With the advent of the theory of signal detection, however, discrete-state theory and the corresponding notion of threshold have been discounted.…

  9. Threshold Concepts and Information Literacy

    ERIC Educational Resources Information Center

    Townsend, Lori; Brunetti, Korey; Hofer, Amy R.

    2011-01-01

    What do we teach when we teach information literacy in higher education? This paper describes a pedagogical approach to information literacy that helps instructors focus content around transformative learning thresholds. The threshold concept framework holds promise for librarians because it grounds the instructor in the big ideas and underlying…

  10. Components of Metabolic Syndrome as Risk Factors for Hearing Threshold Shifts

    PubMed Central

    Sun, Yu-Shan; Fang, Wen-Hui; Kao, Tung-Wei; Yang, Hui-Fang; Peng, Tao-Chun; Wu, Li-Wei; Chang, Yaw-Wen; Chou, Chang-Yi; Chen, Wei-Liang

    2015-01-01

    Background Hearing loss was a common, chronically disabling condition in the general population and had been associated with several inflammatory diseases. Metabolic syndrome, which was associated with insulin resistance and visceral obesity, was considered a chronic inflammatory disease. To date, few attempts had been made to establish a direct relationship between hearing loss and metabolic syndrome. The aim of the present study was to investigate the relationship between metabolic syndrome and hearing loss by analyzing the data in the reports of the National Health and Nutrition Examination Survey 1999–2004. Methods This study included 2100 participants aged ≤ 65 years who enrolled in the National Health and Nutrition Examination Survey (1999–2004). We examined the relationship between the presence of different features of metabolic syndrome in the participants and their pure-tone air-conduction hearing thresholds, including low-frequency and high-frequency thresholds. Results After adjusting for potential confounders, such as age, medical conditions, and smoking status, the participants with more components of metabolic syndrome were found to have higher hearing thresholds than those with fewer components of metabolic syndrome (p < 0.05 for a trend). The low-frequency hearing threshold was associated with individual components of metabolic syndrome, such as abdominal obesity, high blood pressure, elevated triglycerides, and a low level of high-density lipoprotein cholesterol (HDL-C) (p < 0.05 for all parameters). Conclusions The results indicated that the presence of a greater number of components of metabolic syndrome was significantly associated with the hearing threshold in the US adult population. Among the components of metabolic syndrome, the most apparent association was observed between low HDL and hearing loss. PMID:26247614

  11. Threshold selection for regional peaks-over-threshold data

    NASA Astrophysics Data System (ADS)

    Roth, Martin; Jongbloed, Geurt; Adri Buishand, T.

    2016-04-01

    A hurdle in the peaks-over-threshold approach for analyzing extreme values is the selection of the threshold. A method is developed to reduce this obstacle in the presence of multiple, similar data samples. This is for instance the case in many environmental applications. The idea is to combine threshold selection methods into a regional method. Regionalized versions of the threshold stability and the mean excess plot are presented as graphical tools for threshold selection. Moreover, quantitative approaches based on the bootstrap distribution of the spatially averaged Kolmogorov-Smirnov and Anderson-Darling test statistics are introduced. It is demonstrated that the proposed regional method leads to an increased sensitivity for too low thresholds, compared to methods that do not take into account the regional information. The approach can be used for a wide range of univariate threshold selection methods. We test the methods using simulated data and present an application to rainfall data from the Dutch water board Vallei en Veluwe.

  12. Use of air-pressurized slug tests to estimate hydraulic conductivity at selected piezometers completed in the Santa Fe Group aquifer system, Albuquerque area, New Mexico

    USGS Publications Warehouse

    Thomas, Carole L.; Thorn, Conde R.

    2000-01-01

    The City of Albuquerque Public Works Department, Water Resources Management (City), is interested in quantifying aquifer hydraulic properties in the Albuquerque, New Mexico, area to better understand and manage water resources in the Middle Rio Grande Basin. In 1998, the City and the U.S. Geological Survey entered into a cooperative program to determine hydraulic properties of aquifer material adjacent to screened intervals of piezometers in the Albuquerque area. Investigators conducted slug tests from March 8 through April 8, 1999, to estimate hydraulic conductivity of aquifer material adjacent to the screened intervals of 25 piezometers from 11 nested- piezometer sites in the Albuquerque area. At 20 of the piezometers, slug-test responses were typical; at 2 piezometers, tests were prematurely terminated because the tests were taking too long to complete; and at 3 piezometers, test responses were oscillatory. Methods used to estimate hydraulic conductivity were the Bouwer and Rice method or the Cooper, Bredehoeft, and Papadopulos method for most tests; the Shapiro and Greene method for prematurely terminated tests; and the van der Kamp method for oscillatory tests. Hydraulic-conductivity estimates ranged from about 0.15 to 92 feet per day. In general, the smaller estimated values are associated with fine-grained aquifer materials and the larger estimated hydraulic-conductivity values are associated with coarse- grained aquifer materials adjacent to the screened intervals of the piezometers. Hydraulic-conductivity estimates ranged from 0.15 to 8.2 feet per day for aquifer materials adjacent to the screened intervals at 12 piezometers and from 12 to 41 feet per day for aquifer materials adjacent to the screened intervals at 10 piezometers. Hydraulic-conductivity estimates at four piezometers were greater than 41 feet per day.

  13. Bayesian estimation of dose thresholds

    NASA Technical Reports Server (NTRS)

    Groer, P. G.; Carnes, B. A.

    2003-01-01

    An example is described of Bayesian estimation of radiation absorbed dose thresholds (subsequently simply referred to as dose thresholds) using a specific parametric model applied to a data set on mice exposed to 60Co gamma rays and fission neutrons. A Weibull based relative risk model with a dose threshold parameter was used to analyse, as an example, lung cancer mortality and determine the posterior density for the threshold dose after single exposures to 60Co gamma rays or fission neutrons from the JANUS reactor at Argonne National Laboratory. The data consisted of survival, censoring times and cause of death information for male B6CF1 unexposed and exposed mice. The 60Co gamma whole-body doses for the two exposed groups were 0.86 and 1.37 Gy. The neutron whole-body doses were 0.19 and 0.38 Gy. Marginal posterior densities for the dose thresholds for neutron and gamma radiation were calculated with numerical integration and found to have quite different shapes. The density of the threshold for 60Co is unimodal with a mode at about 0.50 Gy. The threshold density for fission neutrons declines monotonically from a maximum value at zero with increasing doses. The posterior densities for all other parameters were similar for the two radiation types.

  14. Pure tone hearing thresholds and leisure noise: Is there a relationship?

    PubMed Central

    Williams, Warwick; Carter, Lyndal; Seeto, Mark

    2015-01-01

    This paper reports on the examination of the relationship between self-reported historical noise exposure during leisure activities and audiological indicators: Measured hearing threshold levels (HTLs) and otoacoustic emissions (OAEs). The research was conducted by a cross-sectional survey of 1,432 individuals whose ages ranged from 11 years to 35 years. Methodology included a comprehensive audiometric assessment including otoscopy, pure tone audiometry (PTA) (air- and bone-conduction), OAEs, and tympanometry. A comprehensive questionnaire gathered information on demographics, hearing health status, and participation in work, nonwork, and leisure activities. Using the history of work, nonwork, and leisure noise exposure, a cumulative lifetime noise exposure was estimated. No correlation was found between cumulative lifetime noise exposure and audiometric PTA or OAE parameters. PMID:26356379

  15. Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentrations of both CO2 ([CO2]) have been shown to decrease stomatal conductance for a wide range of species under numerous conditions. Less well...

  16. Long-term growth of soybean at elevated [CO2] does not cause acclimation of stomatal conductance under fully open-air conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately predicting plant function and global biogeochemical cycles later this century will be complicated if stomatal conductance (gs) acclimates to growth at elevated [CO2], in the sense of a long-term alteration of the response of gs to [CO2], humidity (h) and/or photosynthetic rate (A). If so,...

  17. [Masking in bone-conduction testing--proposal of ABC method].

    PubMed

    Takeuchi, Y

    1992-11-01

    A new strategic masking technique, namely the ABC method, has been developed. In performing this method of measuring thresholds of bone-conduction, the vibrator is placed at the forehead with both ears occluded by air-conduction earphones. One of the earphones is for masking noise and the other is a dummy which balances out the occlusive effect of the test ear against the nontest ear. The ABC method is based on the ABC rule that, in bone-conduction testing, the effective masking noise level necessary to block out the nontest ear can be calculated by a simple equation: right AC (A) + left AC (B)--unmasked BCu (C) under the assumption that the BCu belongs to the nontest ear. In some cases of hearing loss, the above noise level might produce overmasking, then an additive safety noise level, BCu + Interaural Attenuation, is employed. This method offers testers step by step directions which consist of indications of the noise level and a criterion for determining whether the measured bone-conduction is free from cross hearing and overmasking for the given configuration of air-conduction of both ears, BCu, and the masking noise level. Compared to the well known Plato method, in which measurements of thresholds are repeated at several masking noise levels in order to find a single bone-conduction threshold, the ABC method can essentially find the threshold at only one masking noise level. Therefore the ABC method makes it possible to save a great deal of time in performing bone conduction testing. PMID:1464791

  18. Threshold models in radiation carcinogenesis

    SciTech Connect

    Hoel, D.G.; Li, P.

    1998-09-01

    Cancer incidence and mortality data from the atomic bomb survivors cohort has been analyzed to allow for the possibility of a threshold dose response. The same dose-response models as used in the original papers were fit to the data. The estimated cancer incidence from the fitted models over-predicted the observed cancer incidence in the lowest exposure group. This is consistent with a threshold or nonlinear dose-response at low-doses. Thresholds were added to the dose-response models and the range of possible thresholds is shown for both solid tumor cancers as well as the different leukemia types. This analysis suggests that the A-bomb cancer incidence data agree more with a threshold or nonlinear dose-response model than a purely linear model although the linear model is statistically equivalent. This observation is not found with the mortality data. For both the incidence data and the mortality data the addition of a threshold term significantly improves the fit to the linear or linear-quadratic dose response for both total leukemias and also for the leukemia subtypes of ALL, AML, and CML.

  19. Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities.

    PubMed

    Hoskins, Daniel L; Zhang, Xiaoyuan; Hickner, Michael A; Logan, Bruce E

    2014-11-01

    Separators are used to protect cathodes from biofouling and to avoid electrode short-circuiting, but they can adversely affect microbial fuel cell (MFC) performance. A spray method was used to apply a polyvinyl alcohol (PVA) separator to the cathode. Power densities were unaffected by the PVA separator (339±29mW/m(2)), compared to a control lacking a separator in a low conductivity solution (1mS/cm) similar to wastewater. Power was reduced with separators in solutions typical of laboratory tests (7-13mS/cm), compared to separatorless controls. The PVA separator produced more power in a separator assembly (SEA) configuration (444±8mW/m(2)) in the 1mS/cm solution, but power was reduced if a PVA or wipe separator was used in higher conductivity solutions with either Pt or activated carbon catalysts. Spray and cast PVA separators performed similarly, but the spray method is preferred as it was easier to apply and use. PMID:25260178

  20. High-resolution photodetachment spectroscopy from the lowest threshold of O{sup -}

    SciTech Connect

    Joiner, Anne; Mohr, Robert H.; Yukich, J. N.

    2011-03-15

    We conducted photodetachment spectroscopy near the lowest detachment threshold from O{sup -} in a 1-T field with sufficient resolution to observe a magnetic field structure similar to that observed in experiments conducted at the threshold of the electron affinity. These observations included not only cyclotron structure but also, to a smaller degree, individual Zeeman thresholds. The experiment was conducted in a Penning ion trap and with a single-mode, tunable, amplified diode laser. Finally, analysis of our results yielded a measurement of the lowest threshold energy.

  1. Cloud-screening for Africa using a geographically and seasonally variable infrared threshold

    NASA Technical Reports Server (NTRS)

    Eck, T. F.; Kalb, V. L.

    1991-01-01

    A spatially variable monthly, infrared cloud-threshold data base has been used to screen cloud-contaminated observations from radiances measured by the NOAA-9 AVHRR over Africa. Cloud-screening through a monthly average infrared threshold based on measured surface air temperature, which is geographically dependent, shows an improvement over using a seasonally and geographically independent thermal cloud threshold of 287 K. It is found that differences in cloud-screening for these two thresholds occur for cases of lower altitude clouds or subpixel clouds where the radiative temperature is higher than the 287 K infrared threshold, yet colder than the variable threshold developed by Stowe et al. (1988) for the Nimbus-7 global cloud climatology. The variable IR threshold is shown to be effective over persistently cloud-covered regions, such as the coastal region of the Gulf of Guinea, but may introduce some erroneous cloud identifications over mountains.

  2. Cooling of Gas Turbines I - Effects of Addition of Fins to Blade Tips and Rotor, Admission of Cooling Air Through Part of Nozzles, and Change in Thermal Conductivity of Turbine Components

    NASA Technical Reports Server (NTRS)

    Brown, Byron

    1947-01-01

    An analysis was developed for calculating the radial temperature distribution in a gas turbine with only the temperatures of the gas and the cooling air and the surface heat-transfer coefficient known. This analysis was applied to determine the temperatures of a complete wheel of a conventional single-stage impulse exhaust-gas turbine. The temperatures were first calculated for the case of the turbine operating at design conditions of speed, gas flow, etc. and with only the customary cooling arising from exposure of the outer blade flange and one face of the rotor to the air. Calculations were next made for the case of fins applied to the outer blade flange and the rotor. Finally the effects of using part of the nozzles (from 0 to 40 percent) for supplying cooling air and the effects of varying the metal thermal conductivity from 12 to 260 Btu per hour per foot per degree Farenheit on the wheel temperatures were determined. The gas temperatures at the nozzle box used in the calculations ranged from 1600F to 2000F. The results showed that if more than a few hundred degrees of cooling of turbine blades are required other means than indirect cooling with fins on the rotor and outer blade flange would be necessary. The amount of cooling indicated for the type of finning used could produce some improvement in efficiency and a large increase in durability of the wheel. The results also showed that if a large difference is to exist between the effective temperature of the exhaust gas and that of the blade material, as must be the case with present turbine materials and the high exhaust-gas temperatures desired (2000F and above), two alternatives are suggested: (a) If metal with a thermal conductivity comparable with copper is used, then the blade temperature can be reduced by strong cooling at both the blade tip and root. The center of the blade will be less than 2000F hotter than the ends; (b) With low conductivity materials some method of direct cooling other than

  3. Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

    SciTech Connect

    Cowan, Benjamin M.; /Tech-X, Boulder /SLAC

    2007-11-28

    We present measurements of the optical damage threshold of crystalline silicon in air for ultrafast pulses in the near infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm, extending to 2260 nm. We discuss the motivation for the measurements and give theoretical context. We then describe the experimental setup, diagnostics, and procedure. The results show a breakdown threshold of 0.2J/cm{sup 2} at 1550 nm and 1.06 ps FWHM pulse duration, and a weak dependence on wavelength.

  4. The Influence of Humidity on Assessing Irritation Threshold of Ammonia.

    PubMed

    Monsé, Christian; Sucker, Kirsten; Hoffmeyer, Frank; Jettkant, Birger; Berresheim, Hans; Bünger, Jürgen; Brüning, Thomas

    2016-01-01

    A large number of occupational exposure limit values (OELs) are based on avoiding of sensory irritation of the eyes and the upper respiratory tract. In order to investigate the chemosensory effect range of a chemical, odor and sensory irritation thresholds (lateralization thresholds, LTs) can be assessed. Humidity affects olfactory function and thus influences odor thresholds; however, a similar effect has not been shown for sensory irritation thresholds. The purpose of the present study was to explore whether LTs for ammonia vapor vary depending on the water vapor content of the inspired stimulus. Eight healthy nonsmoking volunteers were simultaneously exposed to ammonia vapor through one nostril and clean air through the other and were asked to determine which nostril received the chemical. Within experimental runs, ascending ammonia concentrations (60-350 ppm) that were either dry or humidified were administered at fixed time intervals. Geometric mean LTs obtained at wet (181 ppm) or dry (172 ppm) conditions did not differ significantly (P = 0.19) and were within the range of those reported by previous studies. These results suggest that humidity is not a critical factor in determining sensory irritation thresholds for ammonia, and future studies will examine if these findings are transferable to sensory irritation thresholds for other chemicals. PMID:27379250

  5. The Influence of Humidity on Assessing Irritation Threshold of Ammonia

    PubMed Central

    Sucker, Kirsten; Jettkant, Birger; Berresheim, Hans; Brüning, Thomas

    2016-01-01

    A large number of occupational exposure limit values (OELs) are based on avoiding of sensory irritation of the eyes and the upper respiratory tract. In order to investigate the chemosensory effect range of a chemical, odor and sensory irritation thresholds (lateralization thresholds, LTs) can be assessed. Humidity affects olfactory function and thus influences odor thresholds; however, a similar effect has not been shown for sensory irritation thresholds. The purpose of the present study was to explore whether LTs for ammonia vapor vary depending on the water vapor content of the inspired stimulus. Eight healthy nonsmoking volunteers were simultaneously exposed to ammonia vapor through one nostril and clean air through the other and were asked to determine which nostril received the chemical. Within experimental runs, ascending ammonia concentrations (60–350 ppm) that were either dry or humidified were administered at fixed time intervals. Geometric mean LTs obtained at wet (181 ppm) or dry (172 ppm) conditions did not differ significantly (P = 0.19) and were within the range of those reported by previous studies. These results suggest that humidity is not a critical factor in determining sensory irritation thresholds for ammonia, and future studies will examine if these findings are transferable to sensory irritation thresholds for other chemicals. PMID:27379250

  6. Ear surgery techniques results on hearing threshold improvement

    PubMed Central

    Mokhtarinejad, Farhad; Pour, Saeed Soheili; Nilforoush, Mohammad Hussein; Sepehrnejad, Mahsa; Mirelahi, Susan

    2013-01-01

    Background: Bone conduction (BC) threshold depression is not always by means of sensory neural hearing loss and sometimes it is an artifact caused by middle ear pathologies and ossicular chain problems. In this research, the influences of ear surgeries on bone conduction were evaluated. Materials and Methods: This study was conducted as a clinical trial study. The ear surgery performed on 83 patients classified in four categories: Stapedectomy, tympanomastoid surgery and ossicular reconstruction partially or totally; Partial Ossicular Replacement Prosthesis (PORP) and Total Ossicular Replacement Prosthesis (TORP). Bone conduction thresholds assessed in frequencies of 250, 500, 1000, 2000 and 4000 Hz pre and post the surgery. Results: In stapedectomy group, the average of BC threshold in all frequencies improved approximately 6 dB in frequency of 2000 Hz. In tympanomastoid group, BC threshold in the frequency of 500, 1000 and 2000 Hz changed 4 dB (P-value < 0.05). Moreover, In the PORP group, 5 dB enhancement was seen in 1000 and 2000 Hz. In TORP group, the results confirmed that BC threshold improved in all frequencies especially at 4000 Hz about 6.5 dB. Conclusion: In according to results of this study, BC threshold shift was seen after several ear surgeries such as stapedectomy, tympanoplasty, PORP and TORP. The average of BC improvement was approximately 5 dB. It must be considered that BC depression might happen because of ossicular chain problems. Therefore; by resolving middle ear pathologies, the better BC threshold was obtained, the less hearing problems would be faced. PMID:24381615

  7. Optimum threshold selection method of centroid computation for Gaussian spot

    NASA Astrophysics Data System (ADS)

    Li, Xuxu; Li, Xinyang; Wang, Caixia

    2015-10-01

    Centroid computation of Gaussian spot is often conducted to get the exact position of a target or to measure wave-front slopes in the fields of target tracking and wave-front sensing. Center of Gravity (CoG) is the most traditional method of centroid computation, known as its low algorithmic complexity. However both electronic noise from the detector and photonic noise from the environment reduces its accuracy. In order to improve the accuracy, thresholding is unavoidable before centroid computation, and optimum threshold need to be selected. In this paper, the model of Gaussian spot is established to analyze the performance of optimum threshold under different Signal-to-Noise Ratio (SNR) conditions. Besides, two optimum threshold selection methods are introduced: TmCoG (using m % of the maximum intensity of spot as threshold), and TkCoG ( usingμn +κσ n as the threshold), μn and σn are the mean value and deviation of back noise. Firstly, their impact on the detection error under various SNR conditions is simulated respectively to find the way to decide the value of k or m. Then, a comparison between them is made. According to the simulation result, TmCoG is superior over TkCoG for the accuracy of selected threshold, and detection error is also lower.

  8. Neutrino floor at ultralow threshold

    NASA Astrophysics Data System (ADS)

    Strigari, Louis E.

    2016-05-01

    By lowering their energy threshold, direct dark matter searches can reach the neutrino floor with experimental technology that is now in development. The 7Be flux can be detected with ˜10 eV nuclear recoil energy threshold and 50 kg/yr exposure. The p e p flux can be detected with ˜3 ton/yr exposure, and the first detection of the CNO flux is possible with similar exposure. The p p flux can be detected with threshold of ˜eV and only ˜ kg /yr exposure. These can be the first pure neutral current measurements of the low-energy solar neutrino flux. Measuring this flux is important for low mass dark matter searches and for understanding the solar interior.

  9. Efficient, low threshold, cryogenic Ho:YAG laser.

    PubMed

    Ganija, Miftar; Simakov, Nikita; Hemming, Alexander; Haub, John; Veitch, Peter; Munch, Jesper

    2016-05-30

    We report the development of an efficient, liquid-nitrogen conduction cooled Ho:YAG slab laser with good beam quality. Detailed measurements resolving the structure of the 1900-1911 nm absorption band in Ho:YAG at 77 K are presented. Stress-free conduction cooled mounting of the Ho:YAG slab was demonstrated and the resulting laser operated with a large mode volume of 42 mm3, a slope efficiency of 75% and a threshold of 0.84 W. To our knowledge this corresponds to the lowest reported threshold intensity for a Ho:YAG laser. PMID:27410084

  10. Explosive percolation in thresholded networks

    NASA Astrophysics Data System (ADS)

    Hayasaka, Satoru

    2016-06-01

    Explosive percolation in a network is a phase transition where a large portion of nodes becomes connected with an addition of a small number of edges. Although extensively studied in random network models and reconstructed real networks, explosive percolation has not been observed in a more realistic scenario where a network is generated by thresholding a similarity matrix describing between-node associations. In this report, I examine construction schemes of such thresholded networks, and demonstrate that explosive percolation can be observed by introducing edges in a particular order.

  11. Surface characterizations of color threshold

    NASA Technical Reports Server (NTRS)

    Poirson, Allen B.; Wandell, Brian A.; Varner, Denise C.; Brainard, David H.

    1990-01-01

    The paper evaluates how well three different parametric shapes, ellipsoids, rectangles, and parallelograms, serve as models of three-dimentional detection contours. The constraints of the procedures for deriving the best-fitting shapes on inferences about the theoretical visual detection mechanisms are described. Results of two statistical tests show that only the parallelogram fits the data with more precision than the variance in repeated threshold measurements, and thus provides a slightly better fit than the other two shapes. Nevertheless it does not serve as a better guide than the ellipsoidal model for interpolating from the measurements to thresholds in novel color directions.

  12. Thresholds in chemical respiratory sensitisation.

    PubMed

    Cochrane, Stella A; Arts, Josje H E; Ehnes, Colin; Hindle, Stuart; Hollnagel, Heli M; Poole, Alan; Suto, Hidenori; Kimber, Ian

    2015-07-01

    There is a continuing interest in determining whether it is possible to identify thresholds for chemical allergy. Here allergic sensitisation of the respiratory tract by chemicals is considered in this context. This is an important occupational health problem, being associated with rhinitis and asthma, and in addition provides toxicologists and risk assessors with a number of challenges. In common with all forms of allergic disease chemical respiratory allergy develops in two phases. In the first (induction) phase exposure to a chemical allergen (by an appropriate route of exposure) causes immunological priming and sensitisation of the respiratory tract. The second (elicitation) phase is triggered if a sensitised subject is exposed subsequently to the same chemical allergen via inhalation. A secondary immune response will be provoked in the respiratory tract resulting in inflammation and the signs and symptoms of a respiratory hypersensitivity reaction. In this article attention has focused on the identification of threshold values during the acquisition of sensitisation. Current mechanistic understanding of allergy is such that it can be assumed that the development of sensitisation (and also the elicitation of an allergic reaction) is a threshold phenomenon; there will be levels of exposure below which sensitisation will not be acquired. That is, all immune responses, including allergic sensitisation, have threshold requirement for the availability of antigen/allergen, below which a response will fail to develop. The issue addressed here is whether there are methods available or clinical/epidemiological data that permit the identification of such thresholds. This document reviews briefly relevant human studies of occupational asthma, and experimental models that have been developed (or are being developed) for the identification and characterisation of chemical respiratory allergens. The main conclusion drawn is that although there is evidence that the

  13. Interactive effects of soil water deficit and air vapour pressure deficit on mesophyll conductance to CO2 in Vitis vinifera and Olea europaea.

    PubMed

    Perez-Martin, A; Flexas, J; Ribas-Carbó, M; Bota, J; Tomás, M; Infante, J M; Diaz-Espejo, A

    2009-01-01

    The present work aims to study the interactive effect of drought stress and high vapour pressure deficit (VPD) on leaf gas exchange, and especially on mesophyll conductance to CO(2) (g(m)), in two woody species of great agronomical importance in the Mediterranean basin: Vitis vinifera L. cv. Tempranillo and Olea europaea L. cv. Manzanilla. Plants were grown in specially designed outdoor chambers with ambient and below ambient VPD, under both well-irrigated and drought conditions. g(m) was estimated by the variable J method from simultaneous measurements of gas exchange and fluorescence. In both species, the response to soil water deficit was larger in g(s) than in g(m), and more important than the response to VPD. Olea europaea was apparently more sensitive to VPD, so that plants growing in more humid chambers showed higher g(s) and g(m). In V. vinifera, in contrast, soil water deficit dominated the response of g(s) and g(m). Consequently, changes in g(m)/g(s) were more related to VPD in O. europaea and to soil water deficit in V. vinifera. Most of the limitations of photosynthesis were diffusional and especially due to stomatal closure. No biochemical limitation was detected. The results showed that structural parameters played an important role in determining g(m) during the acclimation process. Although the relationship between leaf mass per unit area (M(A)) with g(m) was scattered, it imposed a limitation to the maximum g(m) achievable, with higher values of M(A) in O. europaea at lower g(m) values. M(A) decreased under water stress in O. europaea but it increased in V. vinifera. This resulted in a negative relationship between M(A) and the CO(2) draw-down between substomatal cavities and chloroplasts in O. europaea, while being positive in V. vinifera. PMID:19457982

  14. Stiffness threshold of randomly distributed carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Chen, Yuli; Pan, Fei; Guo, Zaoyang; Liu, Bin; Zhang, Jianyu

    2015-11-01

    For carbon nanotube (CNT) networks, with increasing network density, there may be sudden changes in the properties, such as the sudden change in electrical conductivity at the electrical percolation threshold. In this paper, the change in stiffness of the CNT networks is studied and especially the existence of stiffness threshold is revealed. Two critical network densities are found to divide the stiffness behavior into three stages: zero stiffness, bending dominated and stretching dominated stages. The first critical network density is a criterion to judge whether or not the network is capable of carrying load, defined as the stiffness threshold. The second critical network density is a criterion to measure whether or not most of the CNTs in network are utilized effectively to carry load, defined as bending-stretching transitional threshold. Based on the geometric probability analysis, a theoretical methodology is set up to predict the two thresholds and explain their underlying mechanisms. The stiffness threshold is revealed to be determined by the statical determinacy of CNTs in the network, and can be estimated quantitatively by the stabilization fraction of network, a newly proposed parameter in this paper. The other threshold, bending-stretching transitional threshold, which signs the conversion of dominant deformation mode, is verified to be well evaluated by the proposed defect fraction of network. According to the theoretical analysis as well as the numerical simulation, the average intersection number on each CNT is revealed as the only dominant factor for the electrical percolation and the stiffness thresholds, it is approximately 3.7 for electrical percolation threshold, and 5.2 for the stiffness threshold of 2D networks. For 3D networks, they are 1.4 and 4.4. And it also affects the bending-stretching transitional threshold, together with the CNT aspect ratio. The average intersection number divided by the fourth root of CNT aspect ratio is found to be

  15. The Importance of Ecosystem Thresholds in Assessing Safe Concentrations of Greenhouse Gases

    NASA Astrophysics Data System (ADS)

    Janetos, A. C.

    2007-12-01

    There is a major strategic challenge in the public debate about global environmental change related to concentrations of greenhouse gases in the atmosphere that might lead to environmentally, socially, and economically unacceptable impacts. This project takes one approach to this problem: avoiding "dangerous anthropogenic interference" and "allowing ecosystems to adapt." But these phrases implicitly assume that the influences of climate change are likely to be gradual and that there will be substantial time for natural resources to adapt or for managers to cope with change. The current state of the science suggests that something quite different may be in the offing. The Intergovernmental Panel on Climate Change (IPCC) and other assessments of possible impacts now agree on two important points. One is that there is already well-documented evidence of the biological and ecological consequences of climate change - in the behavior of migratory birds, in corals bleached from the influence of warming ocean temperatures, in the loss of glaciers to warming air temperatures, and in the loss of sea grass beds to sea level rise. The second is that ecological systems may not in fact change gradually. Modeling studies and the historical record both suggest that changes in ecosystems can be rapid, large, and sometimes irreversible, i.e., there are thresholds that, once crossed, will present serious coping challenges to humans. Moreover, as suggested in a recent National Academy of Sciences (NAS) workshop on "Understanding and Responding to Multiple Environmental Stresses," dealing with threshold responses that may lead to sudden and dramatic change in societal or environmental structure and function will also require that we develop ways to proceed with decision-making despite the many uncertainties associated with thresholds. These observations present serious challenges to the modeling frameworks used in integrated assessment. Not only do the models have to characterize the

  16. New states above charm threshold

    SciTech Connect

    Eichten, Estia J.; Lane, Kenneth; Quigg, Chris; /Fermilab

    2005-11-01

    We revise and extend expectations for the properties of charmonium states that lie above charm threshold, in light of new experimental information. We refine the Cornell coupled-channel model for the coupling of c{bar c} levels to two-meson states, defining resonance masses and widths by pole positions in the complex energy plane, and suggest new targets for experiment.

  17. Estimating Conservation Thresholds on Rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Conservation Effects Assessment Project (CEAP) is a multi-agency effort designed to quantify the environmental and economic impacts of land conservation practices. One of USDA’s goals is to identify Conservation Thresholds, the point at which accelerated erosion occurs, and to examine the usefu...

  18. Threshold Concepts and Pedagogic Representation

    ERIC Educational Resources Information Center

    Meyer, Jan H. F.

    2016-01-01

    Purpose: The purpose of this paper is to present a brief exposure to the development of the threshold concepts framework (TCF), the intention being to illuminate for interested readers a broader landscape of research activity than that perhaps conveyed by the individual contributions to this special edition. Design/Methodology/Approach: There is…

  19. Crossing Thresholds in Academic Reading

    ERIC Educational Resources Information Center

    Abbott, Rob

    2013-01-01

    This paper looks at the conceptual thresholds in relation to academic reading which might be crossed by undergraduate English Literature students. It is part of a wider study following 16 students through three years of undergraduate study. It uses theoretical ideas from Bakhtin and Foucault to analyse interviews with English lecturers. It…

  20. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, C.

    1994-12-31

    Observations of high-energy gamma rays from astronomical sources have revolutionized our view of the cosmos. Gamma rays with energies up to {approximately}10 GeV can be observed directly with space-based instruments. Above 100 GeV the low flux of gamma rays requires one to utilize ground-based instruments. Milagro is a new type of gamma-ray detector based on water Cerenkov technology. This new design will enable to continuously observe the entire overhead sky, and be sensitive to cosmic rays with energies above {approximately}250 GeV. These attributes make Milagro an ideal detector for the study of high-energy transient phenomenon.

  1. Effective thermal conductivity of a thin composite material

    SciTech Connect

    Phelan, P.E.; Niemann, R.C.

    1996-12-31

    The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thickness. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relatively low thermal conductivity. Results indicate that, below some threshold thickness, the composite thermal conductivity increases with decreasing thickness, while above the threshold the thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between filler and matrix thermal conductivities.

  2. Stress intensity factor threshold in dental porcelains.

    PubMed

    Yoshimura, Humberto Naoyuki; Cesar, Paulo Francisco; Soki, Fabiana Naomi; Gonzaga, Carla Castiglia

    2008-05-01

    The stress intensity factor threshold (KI0) is related to the stress level at which cracks start to grow stably, causing the weakening of porcelain prostheses during their use. The values of KI0 of seven dental porcelains (with and without reinforcing leucite crystal, KAlSi2O6) stored in air (22 degrees C, 60% relative humidity) and artificial saliva (37 degrees C) were determined by measuring the crack growth velocity of radial cracks generated at the corner of Vickers indentations. The results of KI0 were correlated with the leucite content, fracture toughness (KIc), and chemical composition of the porcelains. It was observed that KI0 increased with the increase of leucite content (only for the leucite-based porcelains) and with the increase of KIc. The increase in Al2O3 content or the decrease in the alkali oxide (K2O and Na2O) content of the material's glassy matrix tended to increase the KI0 values. Storage media (air and saliva) did not significantly affect the KI0 of porcelains tested, indicating that the control parameter of KI0 value was not the water content of the storage media. PMID:17943412

  3. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  4. RNRA and neutron threshold analyses of thick lithium coatings deposited by sputter evaporation

    NASA Astrophysics Data System (ADS)

    Rigaux, C.; Vigneron, R.; Bodart, F.; Jongen, Y.; Cambriani, A.; Lucas, S.

    2008-05-01

    Li coatings on various substrates have numerous applications: Boron neutron capture therapy, super conducting tokamak, etc. Unfortunately the main difficulty using Li is its reactivity in air and diffusion into metals. It is the only metal that reacts with nitrogen at room temperature and it tarnishes and oxidizes rapidly in air. In this work, we investigate how to profile thick Li layers (50 μm) deposited on SiO2 substrates by a method based on plasma sputtering, involving both DC sputtering and evaporation simultaneously. A thick Li layer (≈10 μm) was covered with a thin stainless steel layer to prevent oxidation during transfer of the sample from the sputtering chamber and the accelerator. Li coatings were investigated by RNRA and neutron threshold reaction to obtain interdiffusion profiles of the different components and their concentration. The depth profile using the 7Li(p,γ)8Be∗ resonance nuclear reaction occurring at 440 keV allows us to obtain Li concentration versus depth up to 50 μm. Preliminary results indicate that homogeneous Li layers can be obtained and protected against air, even though it diffuses into the encapsulated layers.

  5. Hourly and seasonal variation in photosynthesis and stomatal conductance of soybean grown at future CO(2) and ozone concentrations for 3 years under fully open-air field conditions.

    PubMed

    Bernacchi, Carl J; Leakey, Andrew D B; Heady, Lindsey E; Morgan, Patrick B; Dohleman, Frank G; McGrath, Justin M; Gillespie, Kelly M; Wittig, Victoria E; Rogers, Alistair; Long, Stephen P; Ort, Donald R

    2006-11-01

    It is anticipated that enrichment of the atmosphere with CO(2) will increase photosynthetic carbon assimilation in C3 plants. Analysis of controlled environment studies conducted to date indicates that plant growth at concentrations of carbon dioxide ([CO(2)]) anticipated for 2050 ( approximately 550 micromol mol(-1)) will stimulate leaf photosynthetic carbon assimilation (A) by 20 to 40%. Simultaneously, concentrations of tropospheric ozone ([O(3)]) are expected to increase by 2050, and growth in controlled environments at elevated [O(3)] significantly reduces A. However, the simultaneous effects of both increases on a major crop under open-air conditions have never been tested. Over three consecutive growing seasons > 4700 individual measurements of A, photosynthetic electron transport (J(PSII)) and stomatal conductance (g(s)) were measured on Glycine max (L.) Merr. (soybean). Experimental treatments used free-air gas concentration enrichment (FACE) technology in a fully replicated, factorial complete block design. The mean A in the control plots was 14.5 micromol m(-2) s(-1). At elevated [CO(2)], mean A was 24% higher and the treatment effect was statistically significant on 80% of days. There was a strong positive correlation between daytime maximum temperatures and mean daily integrated A at elevated [CO(2)], which accounted for much of the variation in CO(2) effect among days. The effect of elevated [CO(2)] on photosynthesis also tended to be greater under water stress conditions. The elevated [O(3)] treatment had no statistically significant effect on mean A, g(s) or J(PSII) on newly expanded leaves. Combined elevation of [CO(2)] and [O(3)] resulted in a slightly smaller increase in average A than when [CO(2)] alone was elevated, and was significantly greater than the control on 67% of days. Thus, the change in atmospheric composition predicted for the middle of this century will, based on the results of a 3 year open-air field experiment, have smaller

  6. A threshold for dissipative fission

    SciTech Connect

    Thoennessen, M.; Bertsch, G.F.

    1993-09-21

    The empirical domain of validity of statistical theory is examined as applied to fission data on pre-fission data on pre-fission neutron, charged particle, and {gamma}-ray multiplicities. Systematics are found of the threshold excitation energy for the appearance of nonstatistical fission. From the data on systems with not too high fissility, the relevant phenomenological parameter is the ratio of the threshold temperature T{sub thresh} to the (temperature-dependent) fission barrier height E{sub Bar}(T). The statistical model reproduces the data for T{sub thresh}/E{sub Bar}(T) < 0.26 {plus_minus} 0.05, but underpredicts the multiplicities at higher T{sub thresh}/E{sub Bar}(T) independent of mass and fissility of the systems.

  7. Hadronic resonances enhanced by thresholds

    NASA Astrophysics Data System (ADS)

    Caramés, T. F.; Valcarce, A.

    2016-07-01

    We present a neat example of a meson-baryon system where the vicinity of two different thresholds enhances the binding of a hadronic resonance, a pentaquark. As a consequence the pattern of states may change when moving among different flavor sectors, what poses a warning on naive extrapolations to heavy flavor sectors based on systematic expansions. For this purpose we simultaneously analyze the N D bar and NB two-hadron systems looking for possible bound states or resonances. When a resonance is controlled by a coupled-channel effect, going to a different flavor sector may enhance or diminish the binding. This effect may, for example, generate significant differences between the charmonium and bottomonium spectra above open-flavor thresholds or pentaquark states in the open-charm and open-bottom sectors.

  8. Low Threshold Quantum Dot Lasers.

    PubMed

    Iyer, Veena Hariharan; Mahadevu, Rekha; Pandey, Anshu

    2016-04-01

    Semiconductor quantum dots have replaced conventional inorganic phosphors in numerous applications. Despite their overall successes as emitters, their impact as laser materials has been severely limited. Eliciting stimulated emission from quantum dots requires excitation by intense short pulses of light typically generated using other lasers. In this Letter, we develop a new class of quantum dots that exhibit gain under conditions of extremely low levels of continuous wave illumination. We observe thresholds as low as 74 mW/cm(2) in lasers made from these materials. Due to their strong optical absorption as well as low lasing threshold, these materials could possibly convert light from diffuse, polychromatic sources into a laser beam. PMID:26978011

  9. On Generating Fatigue Crack Growth Thresholds

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Newman, James, Jr.; Forman, Royce G.

    2003-01-01

    The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. These experimental procedures can induce load history effects that result in crack closure. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake or blunt at the crack tip, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor range, Delta K, will increase, as will the crack growth rate. da/dN. A fatigue crack growth threshold test procedure is experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R. The authors have chosen to study a ductile aluminum alloy where the plastic deformations generated during testing may be of the magnitude to impact the crack opening.

  10. Nanostructured conductive polymeric materials

    NASA Astrophysics Data System (ADS)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  11. Caries-selective ablation: the second threshold

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter; Jeitner, Peter; Kaufmann, Raimund

    1993-07-01

    The aim of the study was to describe the appropriate fluence necessary for the effective removal of dental decay by ablation processes without or with at least minimal removal of healthy dentin. The experiments were conducted at two wavelengths [355 nm (frequency tripled, Q-switched Nd:YAG-laser) and 377 nm (frequency doubled, gain-switched Alexandrite-laser)] found to be close to the maximum of preferential absorption of carious dentin over healthy dentin. Optoacoustic techniques were applied to determine the ablation thresholds of healthy and carious dentin. The ablation efficiencies at characteristic fluences were determined using non-tactile microtopography. During all experiments a fiber optic delivery system was engaged.

  12. VLSI implementations of threshold logic-a comprehensive survey.

    PubMed

    Beiu, V; Quintana, J M; Avedillo, M J

    2003-01-01

    This paper is an in-depth review on silicon implementations of threshold logic gates that covers several decades. In this paper, we will mention early MOS threshold logic solutions and detail numerous very-large-scale integration (VLSI) implementations including capacitive (switched capacitor and floating gate with their variations), conductance/current (pseudo-nMOS and output-wired-inverters, including a plethora of solutions evolved from them), as well as many differential solutions. At the end, we will briefly mention other implementations, e.g., based on negative resistance devices and on single electron technologies. PMID:18244573

  13. An evaluation of corn earworm damage and thresholds in soybean

    NASA Astrophysics Data System (ADS)

    Adams, Brian Patrick

    Interactions between corn earworm, Helicoverpa zea (Boddie), and soybean, Glycine max L. (Merrill), were investigated in the Mid-South to evaluate thresholds and damage levels. Field studies were conducted in both indeterminate and determinate modern cultivars to evaluate damage, critical injury levels, and soybean response to simulated corn earworm injury. Field studies were also conducted to evaluate the response of indeterminate cultivars to infestations of corn earworm. Field studies were also conducted to investigate the relationship between pyrethroid insecticide application and corn earworm oviposition in soybean. Results of field studies involving simulated corn earworm damage indicated the need for a dynamic threshold that becomes more conservative as soybean phenology progressed through the reproductive growth stages. This suggested that soybean was more tolerant to fruit loss during the earlier reproductive stages and was able to compensate for fruit loss better during this time than at later growth stages. Results of field studies involving infestations of corn earworm indicated that current thresholds are likely too liberal. This resulted in economic injury level tables being constructed based upon a range of crop values and control costs, however, a general action threshold was also recommended for indeterminate soybean in the Mid-South. Field study results investigating the relationship of pyrethroid application and corn earworm oviposition indicated that even in the presence of an insecticide, corn earworm prefers to oviposit in the upper portion of the canopy, as well as on the leaves as opposed to all other plant parts, consistent with all previous literature.

  14. Program For Thresholding In Digital Images

    NASA Technical Reports Server (NTRS)

    Nolf, Scott R.; Avis, Elizabeth L.; Matthews, Christine G.; Stacy, Kathryn

    1994-01-01

    THRTOOL program applies thresholding techniques to Sun rasterfiles. Provides for choice among four methods of thresholding. Written in C language and implemented on Sun series and Silicon Graphics IRIS machines.

  15. USE OF THRESHOLDS IN LANDSCAPE ASSESSMENTS

    EPA Science Inventory

    Identification and use of thresholds are potentially important additions to interpretations of ecological monitoring data. However, there are a number of issues related to defining and using thresholds in interpreting ecological data. Most of these issues center around the pauc...

  16. Damage Thresholds and Morphology of the Front- and Back-Irradiated SiO2 Thin Films Containing Gold Nanoparticles as Artificial Absorbing Defects

    SciTech Connect

    Papernov, S.; Schmid, A.W.; Oliver, J.B.; Rigatti, A.L.

    2008-01-30

    Previous ultraviolet-pulsed, laser-damage studies using model thin films with gold nanoparticles as artificial absorbing defects revealed damage morphology in a form of submicrometer-scaled craters. It was also demonstrated that for defects smaller than 20 nm, crater formation is preceded by plasma-ball formation around absorbing defects. In this work an attempt is made to verify symmetry of the plasma ball by conducting film irradiation from the side of the air/film or substrate/film interfaces. In each case, crater-formation thresholds are derived and crater morphology is analyzed by means of atomic force microscopy.

  17. Thresholds for impaired species recovery.

    PubMed

    Hutchings, Jeffrey A

    2015-06-22

    Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate or uncertainty of population increase. By contrast, Allee effects (positive associations between population size and realized per capita population growth rate, r(realized), a metric of average individual fitness) offer a theoretical and empirical basis for identifying numerical and temporal thresholds at which recovery is unlikely or uncertain. Following a critique of studies on Allee effects, I quantify population-size minima and subsequent trajectories of marine fishes that have and have not recovered following threat mitigation. The data suggest that threat amelioration, albeit necessary, can be insufficient to effect recovery for populations depleted to less than 10% of maximum abundance (N(max)), especially when they remain depleted for lengthy periods of time. Comparing terrestrial and aquatic vertebrates, life-history analyses suggest that population-size thresholds for impaired recovery are likely to be comparatively low for marine fishes but high for marine mammals.Articulation of a 'recovering population paradigm' would seem warranted. It might stimulate concerted efforts to identify generic impaired recovery thresholds across species. It might also serve to reduce the confusion of terminology, and the conflation of causes and consequences with patterns currently evident in the literature on Allee effects, thus strengthening communication among researchers and enhancing the practical utility of recovery-oriented research to conservation practitioners and resource managers. PMID:26213739

  18. Thresholds for impaired species recovery

    PubMed Central

    Hutchings, Jeffrey A.

    2015-01-01

    Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate or uncertainty of population increase. By contrast, Allee effects (positive associations between population size and realized per capita population growth rate, rrealized, a metric of average individual fitness) offer a theoretical and empirical basis for identifying numerical and temporal thresholds at which recovery is unlikely or uncertain. Following a critique of studies on Allee effects, I quantify population-size minima and subsequent trajectories of marine fishes that have and have not recovered following threat mitigation. The data suggest that threat amelioration, albeit necessary, can be insufficient to effect recovery for populations depleted to less than 10% of maximum abundance (Nmax), especially when they remain depleted for lengthy periods of time. Comparing terrestrial and aquatic vertebrates, life-history analyses suggest that population-size thresholds for impaired recovery are likely to be comparatively low for marine fishes but high for marine mammals. Articulation of a ‘recovering population paradigm’ would seem warranted. It might stimulate concerted efforts to identify generic impaired recovery thresholds across species. It might also serve to reduce the confusion of terminology, and the conflation of causes and consequences with patterns currently evident in the literature on Allee effects, thus strengthening communication among researchers and enhancing the practical utility of recovery-oriented research to conservation practitioners and resource managers. PMID:26213739

  19. Threshold Concepts in Finance: Student Perspectives

    ERIC Educational Resources Information Center

    Hoadley, Susan; Kyng, Tim; Tickle, Leonie; Wood, Leigh N.

    2015-01-01

    Finance threshold concepts are the essential conceptual knowledge that underpin well-developed financial capabilities and are central to the mastery of finance. In this paper we investigate threshold concepts in finance from the point of view of students, by establishing the extent to which students are aware of threshold concepts identified by…

  20. Compositional threshold for Nuclear Waste Glass Durability

    SciTech Connect

    Kruger, Albert A.; Farooqi, Rahmatullah; Hrma, Pavel R.

    2013-04-24

    Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.

  1. Percolation-dominated superhydrophobicity and conductivity for nanocomposite coatings from the mixtures of a commercial aqueous silica sol and functionalized carbon nanotubes.

    PubMed

    Peng, Mao; Guo, Honglei; Liao, Zhangjie; Qi, Ji; Zhou, Zhi; Fang, Zhengping; Shen, Lie

    2012-02-01

    Superhydrophobic conductive nanocomposite coatings are prepared for the first time from the simple mixture of a commercial aqueous silica sol and functionalized multiwalled carbon nanotubes (MWNTs) by air-spraying at ambient conditions followed by fluorosilane treatment. The relationship between MWNT content and the structure and properties of the nanocomposite coatings is investigated systematically. An ultra-low threshold (<5 vol.%) for superhydrophobicity is observed, which suggests that MWNTs are superior to any other spherical fillers for the construction of superhydrophobic nanocomposite coatings. When the content of nanotubes is below the threshold, the surface roughness mainly caused by the silica nanoparticles is not enough for creating superhydrophobic surfaces. Only above the threshold, the multiscale hierarchical structure is enough for both high water contact angles (>165°) and extremely low sliding angles (<2°). The conductivity is also percolation dominated, while the threshold for conductivity is much higher than that for superhydrophobicity, which can be ascribed to the encapsulated structure and the agglomeration of nanotubes in the composite coatings during air-spraying. Moreover, the aqueous silica sols hold merits of great film-forming capability at relatively low calcination temperatures, and being free of organic solvents. PMID:22056263

  2. Toward a new methodology for measuring the threshold Shields number

    NASA Astrophysics Data System (ADS)

    Rousseau, Gauthier; Dhont, Blaise; Ancey, Christophe

    2016-04-01

    A number of bedload transport equations involve the threshold Shields number (corresponding to the threshold of incipient motion for particles resting on the streambed). Different methods have been developed for determining this threshold Shields number; they usually assume that the initial streambed is plane prior to sediment transport. Yet, there are many instances in real-world scenarios, in which the initial streambed is not free of bed forms. We are interested in developing a new methodology for determining the threshold of incipient motion in gravel-bed streams in which smooth bed forms (e.g., anti-dunes) develop. Experiments were conducted in a 10-cm wide, 2.5-m long flume, whose initial inclination was 3%. Flows were supercritical and fully turbulent. The flume was supplied with water and sediment at fixed rates. As bed forms developed and migrated, and sediment transport rates exhibited wide fluctuations, measurements had to be taken over long times (typically 10 hr). Using a high-speed camera, we recorded the instantaneous bed load transport rate at the outlet of the flume by taking top-view images. In parallel, we measured the evolution of the bed slope, water depth, and shear stress by filming through a lateral window of the flume. These measurements allowed for the estimation of the space and time-averaged slope, from which we deduced the space and time-averaged Shields number under incipient bed load transport conditions. In our experiments, the threshold Shields number was strongly dependent on streambed morphology. Experiments are under way to determine whether taking the space and time average of incipient motion experiments leads to a more robust definition of the threshold Shields number. If so, this new methodology will perform better than existing approaches at measuring the threshold Shields number.

  3. Epidemic threshold in directed networks.

    PubMed

    Li, Cong; Wang, Huijuan; Van Mieghem, Piet

    2013-12-01

    Epidemics have so far been mostly studied in undirected networks. However, many real-world networks, such as the online social network Twitter and the world wide web, on which information, emotion, or malware spreads, are directed networks, composed of both unidirectional links and bidirectional links. We define the directionality ξ as the percentage of unidirectional links. The epidemic threshold τ(c) for the susceptible-infected-susceptible (SIS) epidemic is lower bounded by 1/λ(1) in directed networks, where λ(1), also called the spectral radius, is the largest eigenvalue of the adjacency matrix. In this work, we propose two algorithms to generate directed networks with a given directionality ξ. The effect of ξ on the spectral radius λ(1), principal eigenvector x(1), spectral gap (λ(1)-|λ(2)|), and algebraic connectivity μ(N-1) is studied. Important findings are that the spectral radius λ(1) decreases with the directionality ξ, whereas the spectral gap and the algebraic connectivity increase with the directionality ξ. The extent of the decrease of the spectral radius depends on both the degree distribution and the degree-degree correlation ρ(D). Hence, in directed networks, the epidemic threshold is larger and a random walk converges to its steady state faster than that in undirected networks with the same degree distribution. PMID:24483506

  4. Epidemic threshold in directed networks

    NASA Astrophysics Data System (ADS)

    Li, Cong; Wang, Huijuan; Van Mieghem, Piet

    2013-12-01

    Epidemics have so far been mostly studied in undirected networks. However, many real-world networks, such as the online social network Twitter and the world wide web, on which information, emotion, or malware spreads, are directed networks, composed of both unidirectional links and bidirectional links. We define the directionality ξ as the percentage of unidirectional links. The epidemic threshold τc for the susceptible-infected-susceptible (SIS) epidemic is lower bounded by 1/λ1 in directed networks, where λ1, also called the spectral radius, is the largest eigenvalue of the adjacency matrix. In this work, we propose two algorithms to generate directed networks with a given directionality ξ. The effect of ξ on the spectral radius λ1, principal eigenvector x1, spectral gap (λ1-λ2), and algebraic connectivity μN-1 is studied. Important findings are that the spectral radius λ1 decreases with the directionality ξ, whereas the spectral gap and the algebraic connectivity increase with the directionality ξ. The extent of the decrease of the spectral radius depends on both the degree distribution and the degree-degree correlation ρD. Hence, in directed networks, the epidemic threshold is larger and a random walk converges to its steady state faster than that in undirected networks with the same degree distribution.

  5. Computational gestalts and perception thresholds.

    PubMed

    Desolneux, Agnès; Moisan, Lionel; Morel, Jean-Michel

    2003-01-01

    In 1923, Max Wertheimer proposed a research programme and method in visual perception. He conjectured the existence of a small set of geometric grouping laws governing the perceptual synthesis of phenomenal objects, or "gestalt" from the atomic retina input. In this paper, we review this set of geometric grouping laws, using the works of Metzger, Kanizsa and their schools. In continuation, we explain why the Gestalt theory research programme can be translated into a Computer Vision programme. This translation is not straightforward, since Gestalt theory never addressed two fundamental matters: image sampling and image information measurements. Using these advances, we shall show that gestalt grouping laws can be translated into quantitative laws allowing the automatic computation of gestalts in digital images. From the psychophysical viewpoint, a main issue is raised: the computer vision gestalt detection methods deliver predictable perception thresholds. Thus, we are set in a position where we can build artificial images and check whether some kind of agreement can be found between the computationally predicted thresholds and the psychophysical ones. We describe and discuss two preliminary sets of experiments, where we compared the gestalt detection performance of several subjects with the predictable detection curve. In our opinion, the results of this experimental comparison support the idea of a much more systematic interaction between computational predictions in Computer Vision and psychophysical experiments. PMID:14766147

  6. Conduct disorder

    MedlinePlus

    Disruptive behavior - child; Impulse control problem - child ... Conduct disorder has been linked to: Child abuse Drug or alcohol abuse in the parents Family conflicts Genetic defects Poverty The diagnosis is more common among boys. It is ...

  7. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Effects of moisture content on wind erosion thresholds of biochar

    NASA Astrophysics Data System (ADS)

    Silva, F. C.; Borrego, C.; Keizer, J. J.; Amorim, J. H.; Verheijen, F. G. A.

    2015-12-01

    Biochar, i.e. pyrolysed biomass, as a soil conditioner is gaining increasing attention in research and industry, with guidelines and certifications being developed for biochar production, storage and handling, as well as for application to soils. Adding water to biochar aims to reduce its susceptibility to become air-borne during and after the application to soils, thereby preventing, amongst others, human health issues from inhalation. The Bagnold model has previously been modified to explain the threshold friction velocity of coal particles at different moisture contents, by adding an adhesive effect. However, it is unknown if this model also works for biochar particles. We measured the threshold friction velocities of a range of biochar particles (woody feedstock) under a range of moisture contents by using a wind tunnel, and tested the performance of the modified Bagnold model. Results showed that the threshold friction velocity can be significantly increased by keeping the gravimetric moisture content at or above 15% to promote adhesive effects between the small particles. For the specific biochar of this study, the modified Bagnold model accurately estimated threshold friction velocities of biochar particles up to moisture contents of 10%.

  9. Odour and flavour thresholds for key aroma components in an orange juice matrix: esters and miscellaneous compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thresholds for flavor volatiles have been traditionally calculated in water or air, but they may vary widely in more complex matrices such as milk, gels, or fruit slurries. The data presented is part of a continuing study to provide the industry with threshold guidelines more adequate for the use of...

  10. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  11. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  12. Epidemic thresholds for bipartite networks

    NASA Astrophysics Data System (ADS)

    Hernández, D. G.; Risau-Gusman, S.

    2013-11-01

    It is well known that sexually transmitted diseases (STD) spread across a network of human sexual contacts. This network is most often bipartite, as most STD are transmitted between men and women. Even though network models in epidemiology have quite a long history now, there are few general results about bipartite networks. One of them is the simple dependence, predicted using the mean field approximation, between the epidemic threshold and the average and variance of the degree distribution of the network. Here we show that going beyond this approximation can lead to qualitatively different results that are supported by numerical simulations. One of the new features, that can be relevant for applications, is the existence of a critical value for the infectivity of each population, below which no epidemics can arise, regardless of the value of the infectivity of the other population.

  13. Efficiency and threshold pump intensity of CW solar-pumped solid-state lasers

    SciTech Connect

    Hwang, I.H. . Dept. of Physics); Lee, J.H. . Langley Research Center)

    1991-09-01

    This paper reports on the efficiencies and threshold pump intensities of various solid-state laser materials that have been estimated to compare their performance characteristics as direct solar-pumped CW lasers. Among the laser materials evaluated in this research, alexandrite has the highest slope efficiency of about 12.6%; however, it does not seem to be practical for solar-pumped laser application because of its high threshold pump intensity. Cr:Nd:GSGG is the most promising for solar-pumped lasing. Its threshold pump intensity is about 100 air-mass-zero (AMO) solar constants and its slope efficiency is about 12% when thermal deformation is completely prevented.

  14. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: A Novel Fully Depleted Air AlN Silicon-on-Insulator Metal-Oxide-Semiconductor Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Yang, Yuan; Gao, Yong; Gong, Peng-Liang

    2008-08-01

    A novel fully depleted air AlN silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistor (MOS-FET) is presented, which can eliminate the self-heating effect and solve the problem that the off-state current of SOI MOSFETs increases and the threshold voltage characteristics become worse when employing a high thermal conductivity material as a buried layer. The simulation results reveal that the lattice temperature in normal SOI devices is 75 K higher than the atmosphere temperature, while the lattice temperature is just 4K higher than the atmosphere temperature resulting in less severe self-heating effect in air AlN SOI MOSFETs and AlN SOI MOSFETs. The on-state current of air AlN SOI MOSFETs is similar to the AlN SOI structure, and improves 12.3% more than that of normal SOI MOSFETs. The off-state current of AlN SOI is 6.7 times of normal SOI MOSFETs, while the counterpart of air AlN SOI MOSFETs is lower than that of SOI MOSFETs by two orders of magnitude. The threshold voltage change of air AlN SOI MOSFETs with different drain voltage is much less than that of AlN SOI devices, when the drain voltage is biased at 0.8 V, this difference is 28mV, so the threshold voltage change induced by employing high thermal conductivity material is cured.

  15. Embracing thresholds for better environmental management

    PubMed Central

    Kelly, Ryan P.; Erickson, Ashley L.; Mease, Lindley A.; Battista, Willow; Kittinger, John N.; Fujita, Rod

    2015-01-01

    Three decades of study have revealed dozens of examples in which natural systems have crossed biophysical thresholds (‘tipping points’)—nonlinear changes in ecosystem structure and function—as a result of human-induced stressors, dramatically altering ecosystem function and services. Environmental management that avoids such thresholds could prevent severe social, economic and environmental impacts. Here, we review management measures implemented in ecological systems that have thresholds. Using Ostrom's social–ecological systems framework, we analysed key biophysical and institutional factors associated with 51 social–ecological systems and associated management regimes, and related these to management success defined by ecological outcomes. We categorized cases as instances of prospective or retrospective management, based upon whether management aimed to avoid a threshold or to restore systems that have crossed a threshold. We find that smaller systems are more amenable to threshold-based management, that routine monitoring is associated with successful avoidance of thresholds and recovery after thresholds have been crossed, and that success is associated with the explicit threshold-based management. These findings are powerful evidence for the policy relevance of information on ecological thresholds across a wide range of ecosystems.

  16. Whole-body vibration perception thresholds

    NASA Astrophysics Data System (ADS)

    Parsons, K. C.; Griffin, M. J.

    1988-03-01

    This paper presents the results of a series of laboratory experiments concerned with perception thresholds for whole-body vibration. The nature of absolute perception thresholds is discussed and a method of determining vibration thresholds, based upon signal detection theory, is proposed. Thresholds of subjects exposed to x-, y- and z-axis sinusoidal vibration were determined for sitting and standing subjects (from 2 to 100 Hz). Perception thresholds have also been determined for supine subjects exposed to vertical ( x-axis) sinusoidal vibration (10-63 Hz). In additional experiments the effects of complex (e.g., random) vibration and the effects of duration on the perception thresholds were investigated. The relation between perception thresholds and vibration levels, said by subjects to be unacceptable if they occurred in their own homes, was investigated as well as the effects of subjects' personality and the visual and acoustic conditions in the laboratory. For the vertical vibration of seated subjects no significant differences were found between the responses of male and female subjects. Significant differences were found between perception thresholds for sitting and standing postures. The median threshold was approximately 0·01 m/s 2 r.m.s. between 2 and 100 Hz. Perception thresholds for x-axis and y-axis vibration were not significantly different in either sitting or standing subjects but significant differences in thresholds were found between sitting and standing positions for both x-axis and y-axis vibration. Subjects tended to be more sensitive to vibration when lying than when sitting or standing. The results suggested that the perception of random vibrations can be predicted from a knowledge of the perception of its component vibrations. The number of cycles of vibration did not affect perception thresholds for vibration durations of more than about 0·25 s. Some assessments suggested that vibration at more than twice the perception threshold may not

  17. Appropriate Conduct

    ERIC Educational Resources Information Center

    Di Lullo, Louis

    2004-01-01

    Many years ago when the author assumed the role of assistant principal for school climate, discipline, and attendance, he inherited many school policies and guidelines that were outdated, unfair, and without merit in the current school climate. Because the school conduct code had not been revised since the school opened in 1960, many of the…

  18. Conducting Meetings.

    ERIC Educational Resources Information Center

    United Tribes Educational Technical Center, Bismarck, ND.

    Written for anyone interested in what makes a meeting run smoothly (and what doesn't), the guide for conducting meetings is divided into the following sections: the chairperson (his/her responsibilities, preparing an agenda, organizing discussions); the meeting (quorums, discussions, points of order, and clarification); the motion (making the…

  19. Difference in Noise-Induced Threshold Shift between Planar and Homeotropic Electroconvections in Nematic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Huh, Jong-Hoon; Kuribayashi, Akiyuki; Kai, Shoichi

    2009-08-01

    We report the threshold shift induced by externally applied noises for electrohydrodynamic convections (EHCs) in both planarly and homeotropically aligned nematic liquid crystals as well as in both the conduction and dielectric regimes. Owing to the difference in timescales among the intrinsic properties of EHCs, externally applied noises, and deterministic fields, the stabilization or destabilization effects induced by noises are observed. In particular, the difference in the threshold shift between both alignments is found, and discussed in terms of the EHC mechanisms for both alignments. Moreover, a noticeable noise-induced threshold shift is observed in the dielectric regime, which is markedly different from that in the conventional conduction regime.

  20. Refinement of a thermal threshold probe to prevent burns.

    PubMed

    Dixon, M J; Taylor, P M; Slingsby, L C; Murrell, J C

    2016-02-01

    Thermal threshold testing is commonly used for pain research. The stimulus may cause burning and merits prevention. Thermal probe modifications hypothesized to reduce burning were evaluated for practicality and effect. Studies were conducted on two humans and eight cats. Unmodified probe 0 was tested on two humans and promising modifications were also evaluated on cats. Probe 1 incorporated rapid cooling after threshold was reached: probe 1a used a Peltier system and probe 1b used water cooling. Probe 2 released skin contact immediately after threshold. Probe 3 (developed in the light of evidence of 'hot spots' in probe 0) incorporated reduced thermal mass and even heating across the skin contact area. Human skin was heated to 48℃ (6℃ above threshold) and the resulting burn was evaluated using area of injury and a simple descriptive scale (SDS). Probe 1a cooled the skin but required further heat dissipation, excessive power, was not 'fail-safe' and was inappropriate for animal mounting. Probe 1b caused less damage than no cooling (27 ± 13 and 38 ± 11 mm(2) respectively, P = 0.0266; median SDS 1.5 and 4 respectively, P = 0.0317) but was cumbersome. Probe 2 was unwieldy and was not evaluated further. Probe 3 produced even heating without blistering in humans. With probe 3 in cats, after opioid treatment, thermal threshold reached cut-out (55℃) on 24 occasions, exceeded 50℃ in a further 32 tests and exceeded 48℃ in the remainder. No skin damage was evident immediately after testing and mild hyperaemia in three cats at 2-3 days resolved rapidly. Probe 3 appeared to be suitable for thermal threshold testing. PMID:25766976

  1. Thresholds for Cenozoic bipolar glaciation.

    PubMed

    Deconto, Robert M; Pollard, David; Wilson, Paul A; Pälike, Heiko; Lear, Caroline H; Pagani, Mark

    2008-10-01

    The long-standing view of Earth's Cenozoic glacial history calls for the first continental-scale glaciation of Antarctica in the earliest Oligocene epoch ( approximately 33.6 million years ago), followed by the onset of northern-hemispheric glacial cycles in the late Pliocene epoch, about 31 million years later. The pivotal early Oligocene event is characterized by a rapid shift of 1.5 parts per thousand in deep-sea benthic oxygen-isotope values (Oi-1) within a few hundred thousand years, reflecting a combination of terrestrial ice growth and deep-sea cooling. The apparent absence of contemporaneous cooling in deep-sea Mg/Ca records, however, has been argued to reflect the growth of more ice than can be accommodated on Antarctica; this, combined with new evidence of continental cooling and ice-rafted debris in the Northern Hemisphere during this period, raises the possibility that Oi-1 represents a precursory bipolar glaciation. Here we test this hypothesis using an isotope-capable global climate/ice-sheet model that accommodates both the long-term decline of Cenozoic atmospheric CO(2) levels and the effects of orbital forcing. We show that the CO(2) threshold below which glaciation occurs in the Northern Hemisphere ( approximately 280 p.p.m.v.) is much lower than that for Antarctica ( approximately 750 p.p.m.v.). Therefore, the growth of ice sheets in the Northern Hemisphere immediately following Antarctic glaciation would have required rapid CO(2) drawdown within the Oi-1 timeframe, to levels lower than those estimated by geochemical proxies and carbon-cycle models. Instead of bipolar glaciation, we find that Oi-1 is best explained by Antarctic glaciation alone, combined with deep-sea cooling of up to 4 degrees C and Antarctic ice that is less isotopically depleted (-30 to -35 per thousand) than previously suggested. Proxy CO(2) estimates remain above our model's northern-hemispheric glaciation threshold of approximately 280 p.p.m.v. until approximately 25 Myr

  2. Electrodeless conductivity.

    PubMed

    Light, T S; McHale, E J; Fletcher, K S

    1989-01-01

    Electrodeless conductivity is a technique for measuring the concentration of electrolytes in solution and utilizes a probe consisting of two toroids in close proximity, both of which are immersed in the solution. In special cases, the toroids may be mounted externally on insulated pipes carrying the solution. One toroid radiates an alternating electric field in the audiofrequency range and the other acts as a receiver to pick up the small current induced by the ions moving in a conducting loop of solution. Coatings which would foul contacting electrodes, such as suspensions, precipitates or oil, have little or no effect. Applications are chiefly to continuous measurement in the chemical processing industries, including pulp and paper, mining and heavy chemical production. The principles and practical details of the method are reviewed and cell-diameter, wall, and temperature effects are discussed. PMID:18964695

  3. Heat conduction

    SciTech Connect

    Lilley, D.G.

    1987-01-01

    Analytical and numerical methods, including both finite difference and finite element techniques, are presented with applications to heat conduction problems. Numerical and analytical methods are integrated throughout the text and a variety of complexities are thoroughly treated with many problems, solutions and computer programs. This book is presented as a fundamental course suitable for senior undergraduate and first year graduate students, with end-of-chapter problems and answers included. Sample case studies and suggested projects are included.

  4. Conduction apraxia.

    PubMed

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-10-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is suggested. PMID:7931387

  5. Health Effects of Air Pollution.

    ERIC Educational Resources Information Center

    Environmental Education Report and Newsletter, 1985

    1985-01-01

    Summarizes health hazards associated with air pollution, highlighting the difficulty in establishing acceptable thresholds of exposure. Respiratory disease, asthma, cancer, cardiovascular disease, and other problems are addressed. Indicates that a wide range of effects from any one chemical exists and that there are differences in sensitivity to…

  6. The three thresholds for fatigue crack propagation

    SciTech Connect

    Miller, K.J.

    1997-12-01

    The three governing threshold conditions in metal fatigue are considered, one relating to crack growth in single crystals, one concerned with crack growth in polycrystalline materials, and one based on linear elastic fracture mechanics (LEFM). All three conditions are examined in relation to the two physical processes of cracking, i.e., Stage I (shear) and Stage II (tensile) crack growth. The LEFM threshold is seen as a lower bound condition for fatigue crack growth rate, and the single crystal threshold is viewed in relation to the fundamental threshold pertaining to the fatigue resistance of polycrystalline metals.

  7. A study of FM threshold extension techniques

    NASA Technical Reports Server (NTRS)

    Arndt, G. D.; Loch, F. J.

    1972-01-01

    The characteristics of three postdetection threshold extension techniques are evaluated with respect to the ability of such techniques to improve the performance of a phase lock loop demodulator. These techniques include impulse-noise elimination, signal correlation for the detection of impulse noise, and delta modulation signal processing. Experimental results from signal to noise ratio data and bit error rate data indicate that a 2- to 3-decibel threshold extension is readily achievable by using the various techniques. This threshold improvement is in addition to the threshold extension that is usually achieved through the use of a phase lock loop demodulator.

  8. Efficient threshold for volumetric segmentation

    NASA Astrophysics Data System (ADS)

    Burdescu, Dumitru D.; Brezovan, Marius; Stanescu, Liana; Stoica Spahiu, Cosmin; Ebanca, Daniel

    2015-07-01

    Image segmentation plays a crucial role in effective understanding of digital images. However, the research on the existence of general purpose segmentation algorithm that suits for variety of applications is still very much active. Among the many approaches in performing image segmentation, graph based approach is gaining popularity primarily due to its ability in reflecting global image properties. Volumetric image segmentation can simply result an image partition composed by relevant regions, but the most fundamental challenge in segmentation algorithm is to precisely define the volumetric extent of some object, which may be represented by the union of multiple regions. The aim in this paper is to present a new method to detect visual objects from color volumetric images and efficient threshold. We present a unified framework for volumetric image segmentation and contour extraction that uses a virtual tree-hexagonal structure defined on the set of the image voxels. The advantage of using a virtual tree-hexagonal network superposed over the initial image voxels is that it reduces the execution time and the memory space used, without losing the initial resolution of the image.

  9. Cartilage conduction is characterized by vibrations of the cartilaginous portion of the ear canal.

    PubMed

    Nishimura, Tadashi; Hosoi, Hiroshi; Saito, Osamu; Miyamae, Ryosuke; Shimokura, Ryota; Yamanaka, Toshiaki; Kitahara, Tadashi; Levitt, Harry

    2015-01-01

    Cartilage conduction (CC) is a new form of sound transmission which is induced by a transducer being placed on the aural cartilage. Although the conventional forms of sound transmission to the cochlea are classified into air or bone conduction (AC or BC), previous study demonstrates that CC is not classified into AC or BC (Laryngoscope 124: 1214-1219). Next interesting issue is whether CC is a hybrid of AC and BC. Seven volunteers with normal hearing participated in this experiment. The threshold-shifts by water injection in the ear canal were measured. AC, BC, and CC thresholds at 0.5-4 kHz were measured in the 0%-, 40%-, and 80%-water injection conditions. In addition, CC thresholds were also measured for the 20%-, 60%-, 100%-, and overflowing-water injection conditions. The contributions of the vibrations of the cartilaginous portion were evaluated by the threshold-shifts. For AC and BC, the threshold-shifts by the water injection were 22.6-53.3 dB and within 14.9 dB at the frequency of 0.5-4 kHz, respectively. For CC, when the water was filled within the bony portion, the thresholds were elevated to the same degree as AC. When the water was additionally injected to reach the cartilaginous portion, the thresholds at 0.5 and 1 kHz dramatically decreased by 27.4 and 27.5 dB, respectively. In addition, despite blocking AC by the injected water, the CC thresholds in force level were remarkably lower than those for BC. The vibration of the cartilaginous portion contributes to the sound transmission, particularly in the low frequency range. Although the airborne sound is radiated into the ear canal in both BC and CC, the mechanism underlying its generation is different between them. CC generates airborne sound in the canal more efficiently than BC. The current findings suggest that CC is not a hybrid of AC and BC. PMID:25768088

  10. Facial warming increases the threshold for shivering.

    PubMed

    Iaizzo, P A; Jeon, Y M; Sigg, D C

    1999-10-01

    A decrease of 1-2 degrees C core temperature provides protection against cerebral ischemia. However, shivering usually prevents reduction in core temperature in unanesthetized patients. Therefore, it was tested whether facial and airway heating increases the shivering threshold and enables core cooling in unanesthetized patients. Nine trials were performed on seven healthy male volunteers. Each subject was positioned supine on a circulating-water mattress (8-15 degrees C) with a convective-air coverlet (15-18 degrees C) extending from the neck to the feet. A dynamic study protocol governed by individualized physiological responses was used. Focal facial (and airway) warming was employed to suppress involuntary motor activity (muscle tensing, shivering) and, thereby, enabling noninvasive cooling to lower the core temperature. The following parameters were monitored: 1) heart rate, 2) blood pressure, 3) core temperature (tympanic, axilla, and rectal), 4) cutaneous temperatures, and 5) a subjective shiver index (scale 1-10). In three, electromyograms and infrared thermographs were also obtained. Upon cooling without facial and airway warming, involuntary motor activity increased until it was widespread. This vigorous motor activity prevented any significant lowering of core temperature or caused it to slightly increase. Subsequently, in all subjects, within seconds after the application of facial focal warming, motor activity was suppressed almost completely, and within minutes core temperatures significantly decreased. Preliminary studies described here indicate that focal facial warming applied during active whole body cooling to initiate mild hypothermia might minimize the need to pharmacologically suppress involuntary motor activity. Such a procedure might be useful for initiating as soon as possible (such as during emergency transport), cerebral mild hypothermia in order to maximize protection and thus improve outcome in neurologically injured patients (head

  11. [Economic evaluation seeks threshold to support decision-making].

    PubMed

    García-Lorenzo, Borja; Vallejo-Torres, Laura; Trujillo-Martín, María Mar; Perestelo-Pérez, Lilisbeth; Valcárcel-Nazco, Cristina; Serrano Aguilar, Pedro

    2015-12-01

    To incorporate economic evaluation into decision-making, we need to know how much a health system is willing and able to invest in a quality-adjusted life year (QALY). In Spain, the figure of €30,000 per QALY as cost-effectiveness (CE) threshold has been widely cited. However, as in most health systems, no value has been formally adopted; mainly because of the arbitrariness, the lack of theoretical and scientific basis, and the controversy around its estimation and what the threshold should represent. Based on a systematic review of empirical studies on the estimation of the CE threshold undertaken by this research team, we conducted a critical appraisal of the state of the art, using a Delphi with the participation of 13 national experts. This paper contributes to assess the research progress on the CE threshold in Spain, to consider its utility in the decision making process supported by economic evaluation, and to propose further research to improve what has been achieved so far. PMID:26786302

  12. Echo thresholds for reflections from acoustically diffusive architectural surfaces.

    PubMed

    Robinson, Philip W; Walther, Andreas; Faller, Christof; Braasch, Jonas

    2013-10-01

    When sound reflects from an irregular architectural surface, it spreads spatially and temporally. Extensive research has been devoted to prediction and measurement of diffusion, but less has focused on its perceptual effects. This paper examines the effect of temporal diffusion on echo threshold. There are several notable differences between the waveform of a reflection identical to the direct sound and one from an architectural surface. The onset and offset are damped and the energy is spread in time; hence, the reflection response has a lower peak amplitude, and is decorrelated from the direct sound. The perceptual consequences of these differences are previously undocumented. Echo threshold tests are conducted with speech and music signals, using direct sound and a simulated reflection that is either identical to the direct sound or has various degrees of diffusion. Results indicate that for a speech signal, diffuse reflections are less easily detectable as a separate auditory event than specular reflections of the same total energy. For a music signal, no differences are observed between the echo thresholds for reflections with and without temporal diffusion. Additionally, echo thresholds are found to be shorter for speech than for music, and shorter for spatialized than for diotic presentation of signals. PMID:24116414

  13. Measured Rattle Threshold of Residential House Windows

    NASA Technical Reports Server (NTRS)

    Sizov, Natalia; Schultz, Troy; Hobbs, Christopher; Klos, Jacob

    2008-01-01

    Window rattle is a common indoor noise effect in houses exposed to low frequency noise from such sources as railroads, blast noise and sonic boom. Human perception of rattle can be negative that is a motivating factor of the current research effort to study sonic boom induced window rattle. A rattle study has been conducted on residential houses containing windows of different construction at a variety of geographic locations within the United States. Windows in these houses were excited by a portable, high-powered loudspeaker and enclosure specifically designed to be mounted on the house exterior to cover an entire window. Window vibration was measured with accelerometers placed on different window components. Reference microphones were also placed inside the house and inside of the loudspeaker box. Swept sine excitation was used to identify the vibration threshold at which the response of the structure becomes non-linear and begins to rattle. Initial results from this study are presented and discussed. Future efforts will continue to explore the rattle occurrence in windows of residential houses exposed to sonic booms.

  14. Thresholds of carcinogenicity of flavors.

    PubMed

    Waddell, William J

    2002-08-01

    Fifteen compounds approved by the FEMA (Flavor and Extract Manufacturers Association) expert panel as GRAS (Generally Recognized As Safe) and structurally related compounds have been reported to be carcinogenic in rodent studies. The dose response of the 15 compounds in these studies was scrutinized by attempting to plot the percentage of animals with tumors against the dose of the compound on a logarithmic scale in molecules of compound per kg per day (the Rozman scale). Four compounds had either no or an inverse dose response: benzaldehyde, furfural, 3,4-dihydroxycoumarin, and gamma-buterolactone. Three had a response at one dose only: anethole, estragole (2 studies), and isophorone. Obviously, a dose-response curve could not be generated for these 7 compounds. Four compounds had an increasing response at two doses (benzyl acetate, cinnamyl anthranilate, ethyl acrylate, and estragole); three compounds had increasing responses at three doses (citral, 2,4-hexadienal, and pyridine); one compound had increasing responses at four doses (methyl eugenol). The three compounds with three doses fit a linear plot with a correlation coefficient of at least 0.9; the four doses in male rats of methyl eugenol fit a linear plot with a correlation coefficient of 0.999983. The intercept at zero percentage tumors of these linear fits was at least several orders of magnitude greater than the estimated daily dose of these flavoring agents to individuals in the United States. This is interpreted to indicate that these flavoring agents have a clear threshold for carcinogenicity in animals that is well above the levels currently approved for use in foods; consequently, these animal studies should not be a cause for concern for carcinogenicity of these compounds in humans. Rather, the animal studies should be viewed as providing evidence for the safety of these compounds at current levels of human exposure. PMID:12151622

  15. Properties of air and combustion products of fuel with air

    NASA Technical Reports Server (NTRS)

    Poferl, D. J.; Svehla, R. A.

    1975-01-01

    Thermodynamic and transport properties have been calculated for air, the combustion products of natural gas and air, and combustion products of ASTM-A-1 jet fuel and air. Properties calculated include: ratio of specific heats, molecular weight, viscosity, specific heat, thermal conductivity, Prandtl number, and enthalpy.

  16. Optimal thresholds for the estimation of area rain-rate moments by the threshold method

    NASA Technical Reports Server (NTRS)

    Short, David A.; Shimizu, Kunio; Kedem, Benjamin

    1993-01-01

    Optimization of the threshold method, achieved by determination of the threshold that maximizes the correlation between an area-average rain-rate moment and the area coverage of rain rates exceeding the threshold, is demonstrated empirically and theoretically. Empirical results for a sequence of GATE radar snapshots show optimal thresholds of 5 and 27 mm/h for the first and second moments, respectively. Theoretical optimization of the threshold method by the maximum-likelihood approach of Kedem and Pavlopoulos (1991) predicts optimal thresholds near 5 and 26 mm/h for lognormally distributed rain rates with GATE-like parameters. The agreement between theory and observations suggests that the optimal threshold can be understood as arising due to sampling variations, from snapshot to snapshot, of a parent rain-rate distribution. Optimal thresholds for gamma and inverse Gaussian distributions are also derived and compared.

  17. Threshold effect in lead-induced peripheral neuropathy

    SciTech Connect

    Schwartz, J.; Landrigan, P.J.; Feldman, R.G.; Silbergeld, E.K.; Baker, E.L. Jr.; von Lindern, I.H.

    1988-01-01

    We previously demonstrated a negative correlation between blood lead level and motor nerve conduction velocity in 202 asymptomatic 5 to 9-year-old children living near a lead smelter in Idaho. Blood lead levels ranged from 13 to 97 micrograms/dL. To determine whether a threshold exists between blood lead level and maximal motor nerve conduction velocity, we conducted three regression analyses on these data: a ''hockey stick'' regression, a logistic regression, and a quadratic regression. We found evidence for a threshold in all three analyses: at a blood level of 30 micrograms/dL in the ''hockey stick'' regression, at 20 micrograms/dL in the logistic, and at 25 to 30 micrograms/dL in the quadratic. Neither age, sex, socioeconomic status, nor duration of residence near the smelter significantly modified the relationship. These analyses confirm that asymptomatic increased lead absorption causes slowing of nerve conduction, but they also indicate that measurement of maximal motor nerve conduction velocity is an insensitive screen for low-level lead toxicity.

  18. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  19. The Threshold Level--For Schools?

    ERIC Educational Resources Information Center

    Lauerbach, Gerda

    1979-01-01

    Comments on the document "Threshold Level for Modern Language Learning Schools" (J. A. Van Ek, Strasbourg, 1976) and its appropriateness as a description of learning goals for the first years of foreign language teaching. Criticizes particularly the "reduced learning" concept, on which the threshold projects are based. (IFS/WGA)

  20. 24 CFR 954.104 - Performance thresholds.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Performance thresholds. 954.104... DEVELOPMENT INDIAN HOME PROGRAM Applying for Assistance § 954.104 Performance thresholds. Applicants must have the administrative capacity to undertake the project proposed, including systems of internal...

  1. STIMULUS AND TRANSDUCER EFFECTS ON THRESHOLD

    PubMed Central

    Flamme, Gregory A.; Geda, Kyle; McGregor, Kara; Wyllys, Krista; Deiters, Kristy K.; Murphy, William J.; Stephenson, Mark R.

    2015-01-01

    Objective This study examined differences in thresholds obtained under Sennheiser HDA200 circumaural earphones using pure tone, equivalent rectangular noise bands, and 1/3 octave noise bands relative to thresholds obtained using Telephonics TDH-39P supra-aural earphones. Design Thresholds were obtained via each transducer and stimulus condition six times within a 10-day period. Study Sample Forty-nine adults were selected from a prior study to represent low, moderate, and high threshold reliability. Results The results suggested that (1) only small adjustments were needed to reach equivalent TDH-39P thresholds, (2) pure-tone thresholds obtained with HDA200 circumaural earphones had reliability equal to or better than those obtained using TDH-39P earphones, (3) the reliability of noise-band thresholds improved with broader stimulus bandwidth and was either equal to or better than pure-tone thresholds, and (4) frequency-specificity declined with stimulus bandwidths greater than one Equivalent Rectangular Band, which could complicate early detection of hearing changes that occur within a narrow frequency range. Conclusions These data suggest that circumaural earphones such as the HDA200 headphones provide better reliability for audiometric testing as compared to the TDH-39P earphones. These data support the use of noise bands, preferably ERB noises, as stimuli for audiometric monitoring. PMID:25549164

  2. Intelligence and Creativity: Over the Threshold Together?

    ERIC Educational Resources Information Center

    Welter, Marisete Maria; Jaarsveld, Saskia; van Leeuwen, Cees; Lachmann, Thomas

    2016-01-01

    Threshold theory predicts a positive correlation between IQ and creativity scores up to an IQ level of 120 and no correlation above this threshold. Primary school children were tested at beginning (N = 98) and ending (N = 70) of the school year. Participants performed the standard progressive matrices (SPM) and the Test of Creative…

  3. Network Motif Basis of Threshold Responses

    EPA Science Inventory

    There has been a long-running debate over the existence of thresholds for adverse effects. The difficulty stems from two fundamental challenges: (i) statistical analysis by itself cannot prove the existence of a threshold, i.e., a dose below which there is no effect; and (ii) the...

  4. Threshold Concepts, Systems and Learning for Sustainability

    ERIC Educational Resources Information Center

    Sandri, Orana Jade

    2013-01-01

    This paper presents a framework for understanding the role that systems theory might play in education for sustainability (EfS). It offers a sketch and critique of Land and Meyer's notion of a "threshold concept", to argue that seeing systems as a threshold concept for sustainability is useful for understanding the processes of…

  5. Methods for automatic trigger threshold adjustment

    DOEpatents

    Welch, Benjamin J; Partridge, Michael E

    2014-03-18

    Methods are presented for adjusting trigger threshold values to compensate for drift in the quiescent level of a signal monitored for initiating a data recording event, thereby avoiding false triggering conditions. Initial threshold values are periodically adjusted by re-measuring the quiescent signal level, and adjusting the threshold values by an offset computation based upon the measured quiescent signal level drift. Re-computation of the trigger threshold values can be implemented on time based or counter based criteria. Additionally, a qualification width counter can be utilized to implement a requirement that a trigger threshold criterion be met a given number of times prior to initiating a data recording event, further reducing the possibility of a false triggering situation.

  6. Implications in medical imaging of the new ICRP thresholds for tissue reactions.

    PubMed

    Vañó, E; Miller, D L; Dauer, L

    2015-06-01

    The International Commission on Radiological Protection (ICRP) statement on tissue reactions, issued by the Commission in April 2011, reviewed epidemiological evidence and suggested that there are some tissue reactions where threshold doses are or may be lower than those previously considered. For the lens of the eye, the threshold is now considered to be 0.5 Gy. The absorbed dose threshold for circulatory disease in the heart and brain may be as low as 0.5 Gy. These values can be reached in some patients during interventional cardiology or neuroradiology procedures. They may also be of concern for repeated computed tomography examinations of the head. The new thresholds should be considered in optimisation strategies for clinical procedures, especially in patients likely to require repeated interventions. The new dose thresholds also affect occupational protection for operators and staff. Some operators do not protect their eyes or their brain adequately. After several years of work without proper protection, the absorbed doses to the lens of the eye and the brain of staff can exceed 0.5 Gy. More research is needed to understand the biological effects of cumulative incident air kerma and the instantaneous air kerma rates currently used in medical imaging. The new thresholds, and the need for specific occupational dosimetry related to lens doses, should be considered in radiation protection programmes, and should be included in the education and training of professionals involved in fluoroscopy guided procedures and computed tomography. PMID:25816265

  7. AIR STRUCTURES FOR SCHOOL SPORTS.

    ERIC Educational Resources Information Center

    ROBERTSON, NAN

    AIR STRUCTURES ARE FABRIC BUILDINGS BLOWN UP AND HELD UP BY AIR PRESSURE. EXPERIMENTS WITH SUCH STRUCTURES WERE CONDUCTED AS EARLY AS 1917. IN 1948 THE UNITED STATES AIR FORCE SOUGHT A NEW WAY OF HOUSING LARGE RADAR ANTENNAE PLANNED FOR THE ARCTIC. AS AN OUTCOME OF THEIR SEARCH, BIRDAIR STRUCTURES, INC., WHICH IS NOW ONE OF SEVERAL COMPANIES…

  8. Air Structures for School Sports.

    ERIC Educational Resources Information Center

    Robertson, Nan

    Air structures are fabric buildings blown up and held up by air pressure. Experiments with such structures were conducted as early as 1917. In 1948 the United States Air Force sought a new way of housing large radar antennae planned for the arctic. As an outcome of their search, Birdair Structures, Inc., which is now one of several companies…

  9. A Threshold Continuum for Aeolian Sand Transport

    NASA Astrophysics Data System (ADS)

    Swann, C.; Ewing, R. C.; Sherman, D. J.

    2015-12-01

    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  10. Cartilage conduction hearing.

    PubMed

    Shimokura, Ryota; Hosoi, Hiroshi; Nishimura, Tadashi; Yamanaka, Toshiaki; Levitt, Harry

    2014-04-01

    Sound information is known to travel to the cochlea via either air or bone conduction. However, a vibration signal, delivered to the aural cartilage via a transducer, can also produce a clearly audible sound. This type of conduction has been termed "cartilage conduction." The aural cartilage forms the outer ear and is distributed around the exterior half of the external auditory canal. In cartilage conduction, the cartilage and transducer play the roles of a diaphragm and voice coil of a loudspeaker, respectively. There is a large gap between the impedances of cartilage and skull bone, such that cartilage vibrations are not easily transmitted through bone. Thus, these methods of conduction are distinct. In this study, force was used to apply a transducer to aural cartilage, and it was found that the sound in the auditory canal was amplified, especially for frequencies below 2 kHz. This effect was most pronounced at an application force of 1 N, which is low enough to ensure comfort in the design of hearing aids. The possibility of using force adjustments to vary amplification may also have applications for cell phone design. PMID:25234994

  11. Interlaminar shear fracture toughness and fatigue thresholds for composite materials

    NASA Technical Reports Server (NTRS)

    O'Brien, T. Kevin; Murri, Gretchen B.; Salpekar, Satish A.

    1989-01-01

    Static and cyclic end notched flexure tests were conducted on a graphite epoxy, a glass epoxy, and graphite thermoplastic to determine their interlaminar shear fracture toughness and fatigue thresholds for delamination in terms of limiting values of the mode II strain energy release rate, G-II, for delamination growth. The influence of precracking and data reduction schemes are discussed. Finite element analysis indicated that the beam theory calculation for G-II with the transverse shear contribution included was reasonably accurate over the entire range of crack lengths. Cyclic loading significantly reduced the critical G-II for delamination. A threshold value of the maximum cyclic G-II below which no delamination occurred after one million cycles was identified for each material. Also, residual static toughness tests were conducted on glass epoxy specimens that had undergone one million cycles without delamination. A linear mixed-mode delamination criteria was used to characterize the static toughness of several composite materials; however, a total G threshold criterion appears to characterize the fatigue delamination durability of composite materials with a wide range of static toughness.

  12. Interlaminar shear fracture toughness and fatigue thresholds for composite materials

    NASA Technical Reports Server (NTRS)

    Obrien, T. Kevin; Murri, Gretchen B.; Salpekar, Satish A.

    1987-01-01

    Static and cyclic end notched flexure tests were conducted on a graphite epoxy, a glass epoxy, and graphite thermoplastic to determine their interlaminar shear fracture toughness and fatigue thresholds for delamination in terms of limiting values of the mode II strain energy release rate, G-II, for delamination growth. The influence of precracking and data reduction schemes are discussed. Finite element analysis indicated that the beam theory calculation for G-II with the transverse shear contribution included was reasonably accurate over the entire range of crack lengths. Cyclic loading significantly reduced the critical G-II for delamination. A threshold value of the maximum cyclic G-II below which no delamination occurred after one million cycles was identified for each material. Also, residual static toughness tests were conducted on glass epoxy specimens that had undergone one million cycles without delamination. A linear mixed-mode delamination criteria was used to characterize the static toughness of several composite materials; however, a total G threshold criterion appears to characterize the fatigue delamination durability of composite materials with a wide range of static toughness.

  13. Data Assimilation Experiments using Quality Controlled AIRS Version 5 Temperature Soundings

    NASA Technical Reports Server (NTRS)

    Susskind, Joel

    2008-01-01

    The AIRS Science Team Version 5 retrieval algorithm has been finalized and is now operational at the Goddard DAAC in the processing (and reprocessing) of all AlRS data. Version 5 contains accurate case-by-case error estimates for most derived products, which are also used for quality control. We have conducted forecast impact experiments assimilating AlRS quality controlled temperature profiles using the NASA GEOS-5 data assimilation system, consisting of the NCEP GSI analysis coupled with the NASA FVGCM. Assimilation of quality controlled temperature profiles resulted in significantly improved forecast skill in both the Northern Hemisphere and Southern Hemisphere Extra-Tropics, compared to that obtained from analyses obtained when all data used operationally by NCEP except for AlRS data is assimilated. Experiments using different Quality Control thresholds for assimilation of AlRS temperature retrievals showed that a medium quality control threshold performed better than a tighter threshold, which provided better overall sounding accuracy; or a looser threshold, which provided better spatial coverage of accepted soundings. We are conducting more experiments to further optimize this balance of spatial coverage and sounding accuracy from the data assimilation perspective. In all cases, temperature soundings were assimilated well below cloud level in partially cloudy cases. The positive impact of assimilating AlRS derived atmospheric temperatures all but vanished when only AIRS stratospheric temperatures were assimilated. Forecast skill resulting from assimilation of AlRS radiances uncontaminated by clouds, instead of AlRS temperature soundings, was only slightly better than that resulting from assimilation of only stratospheric AlRS temperatures. This reduction in forecast skill is most likely the result of significant loss of tropospheric information when only AIRS radiances unaffected by clouds are used in the data assimilation process.

  14. Conductivity of continuum percolating systems

    NASA Astrophysics Data System (ADS)

    Stenull, Olaf; Janssen, Hans-Karl

    2001-11-01

    We study the conductivity of a class of disordered continuum systems represented by the Swiss-cheese model, where the conducting medium is the space between randomly placed spherical holes, near the percolation threshold. This model can be mapped onto a bond percolation model where the conductance σ of randomly occupied bonds is drawn from a probability distribution of the form σ-a. Employing the methods of renormalized field theory we show to arbitrary order in ɛ expansion that the critical conductivity exponent of the Swiss-cheese model is given by tSC(a)=(d-2)ν+max[φ,(1-a)-1], where d is the spatial dimension and ν and φ denote the critical exponents for the percolation correlation length and resistance, respectively. Our result confirms a conjecture that is based on the ``nodes, links, and blobs'' picture of percolation clusters.

  15. A model based rule for selecting spiking thresholds in neuron models.

    PubMed

    Mikkelsen, Frederik Riis

    2016-06-01

    Determining excitability thresholds in neuronal models is of high interest due to its applicability in separating spiking from non-spiking phases of neuronal membrane potential processes. However, excitability thresholds are known to depend on various auxiliary variables, including any conductance or gating variables. Such dependences pose as a double-edged sword; they are natural consequences of the complexity of the model, but proves difficult to apply in practice, since gating variables are rarely measured. In this paper a technique for finding excitability thresholds, based on the local behaviour of the flow in dynamical systems, is presented. The technique incorporates the dynamics of the auxiliary variables, yet only produces thresholds for the membrane potential. The method is applied to several classical neuron models and the threshold's dependence upon external parameters is studied, along with a general evaluation of the technique. PMID:27106187

  16. Femtosecond pulse damage thresholds of dielectric coatings in vacuum

    SciTech Connect

    Michelle D. Shinn, Duy N. Nguyen, Luke A. Emmert ,Paul Schwoebel, Dinesh Patel, Carmen S. Menoni, Wolfgang Rudolph

    2011-03-01

    At 10-7 Torr, the multiple femtosecond pulse damage threshold, F(?), is about 10% of the single pulse damage fluence F(1) for hafnia and silica films compared to about 65% and 50%, respectively, at 630 Torr. In contrast, the single-pulse damage threshold is pressure independent. The decrease of F(?) with decreasing air pressure correlates with the water vapor and oxygen content of the ambient gas with the former having the greater effect. The decrease in F(?) is likely associated with an accumulation of defects derived from oxygen deficiency, for example vacancies. From atmospheric air pressure to pressures of {approx}3 x 10{sup -6} Torr, the damage 'crater' starts deterministically at the center of the beam and grows in diameter as the fluence increases. At pressure below 3x10-6 Torr, damage is initiated at random 'sites' within the exposed area in hafnia films, while the damage morphology remains deterministic in silica films. A possible explanation is that absorbing centers are created at predisposed sample sites in hafnia, for example at boundaries between crystallites, or crystalline and amorphous phases.

  17. Effective thermal conductivity of a thin, randomly oriented composite material

    SciTech Connect

    Phelan, P.E.; Niemann, R.C.

    1997-10-01

    The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thicknesses. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relative low thermal conductivity. The results indicate that, below some threshold thickness, the composite thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between the filler and matrix thermal conductivities.

  18. Conducting a thermal conductivity survey

    NASA Technical Reports Server (NTRS)

    Allen, P. B.

    1985-01-01

    A physically transparent approximate theory of phonon decay rates is presented starting from a pair potential model of the interatomic forces in an insulator or semiconductor. The theory applies in the classical regime and relates the 3-phonon decay rate to the third derivative of the pair potential. Phonon dispersion relations do not need to be calculated, as sum rules relate all the needed quantities directly to the pair potential. The Brillouin zone averaged phonon lifetime turns out to involve a dimensionless measure of the anharmonicity multiplied by an effective density of states for 3-phonon decay. Results are given for rare gas and alkali halide crystals. For rare gases, the results are in good agreement with more elaborate perturbation calculations. Comparison to experimental data on phonon linewidths and thermal conductivity are made.

  19. Efficiency and threshold pump intensity of CW solar-pumped solid-state lasers

    NASA Technical Reports Server (NTRS)

    Hwang, In H.; Lee, Ja H.

    1991-01-01

    The authors consider the relation between the threshold pumping intensity, the material properties, the resonator parameters, and the ultimate slope efficiencies of various solid-state laser materials for solar pumping. They clarify the relation between the threshold pump intensity and the material parameters and the relation between the ultimate slope efficiency and the laser resonator parameters such that a design criterion for the solar-pumped solid-state laser can be established. Among the laser materials evaluated, alexandrite has the highest slope efficiency of about 12.6 percent; however, it does not seem to be practical for a solar-pumped laser application because of its high threshold pump intensity. Cr:Nd:GSGG is the most promising for solar-pumped lasing. Its threshold pump intensity is about 100 air-mass-zero (AM0) solar constants and its slope efficiency is about 12 percent when thermal deformation is completely prevented.

  20. Threshold friction velocity influenced by wetness of soils within the Columbia Plateau

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Windblown dust impacts air quality in the Columbia Plateau of the U.S. Pacific Northwest. Wind erosion of agricultural lands, which is the predominate source of windblown dust in the region, occurs when the friction velocity exceeds the threshold friction velocity (TFV) of the surface. Soil moisture...

  1. Organic thin film devices with stabilized threshold voltage and mobility, and method for preparing the devices

    DOEpatents

    Nastasi, Michael Anthony; Wang, Yongqiang; Fraboni, Beatrice; Cosseddu, Piero; Bonfiglio, Annalisa

    2013-06-11

    Organic thin film devices that included an organic thin film subjected to a selected dose of a selected energy of ions exhibited a stabilized mobility (.mu.) and threshold voltage (VT), a decrease in contact resistance R.sub.C, and an extended operational lifetime that did not degrade after 2000 hours of operation in the air.

  2. Photoproduction of the ω meson on the proton near threshold

    NASA Astrophysics Data System (ADS)

    Strakovsky, I. I.; Prakhov, S.; Azimov, Ya. I.; Aguar-Bartolomé, P.; Annand, J. R. M.; Arends, H. J.; Bantawa, K.; Beck, R.; Bekrenev, V.; Berghäuser, H.; Braghieri, A.; Briscoe, W. J.; Brudvik, J.; Cherepnya, S.; Codling, R. F. B.; Collicott, C.; Costanza, S.; Demissie, B. T.; Downie, E. J.; Drexler, P.; Fil'kov, L. V.; Glazier, D. I.; Gregor, R.; Hamilton, D. J.; Heid, E.; Hornidge, D.; Jaegle, I.; Jahn, O.; Jude, T. C.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Kotulla, M.; Koulbardis, A.; Kruglov, S.; Krusche, B.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Maghrbi, Y.; Manley, D. M.; Marinides, Z.; McGeorge, J. C.; McNicoll, E. F.; Mekterovic, D.; Metag, V.; Middleton, D. G.; Mushkarenkov, A.; Nefkens, B. M. K.; Nikolaev, A.; Novotny, R.; Ortega, H.; Ostrick, M.; Otte, P. B.; Oussena, B.; Pedroni, P.; Pheron, F.; Polonski, A.; Robinson, J.; Rosner, G.; Rostomyan, T.; Schumann, S.; Sikora, M. H.; Starostin, A.; Supek, I.; Taragin, M. F.; Tarbert, C. M.; Thiel, M.; Thomas, A.; Unverzagt, M.; Watts, D. P.; Werthmüller, D.; Zehr, F.; A2 Collaboration at MAMI

    2015-04-01

    An experimental study of ω photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The γ p →ω p differential cross sections are measured from threshold to the incident-photon energy Eγ=1.40 GeV (W =1.87 GeV for the center-of-mass energy) with 15-MeV binning in Eγ and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the ω N scattering length αω p is provided.

  3. Generating Fatigue Crack Growth Thresholds with Constant Amplitude Loads

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Newman, James C., J.; Forman, Royce G.

    2002-01-01

    The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. Some experimental procedures tend to induce load history effects that result in remote crack closure from plasticity. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor, K, will increase, as will the crack growth rate, da/dN. A fatigue crack growth threshold test procedure is developed and experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R.

  4. Sputtering Threshold Energies of Heavy Ions

    NASA Technical Reports Server (NTRS)

    Mantenieks, Maris A.

    1999-01-01

    Sputter erosion in ion thrusters has been measured in lifetests at discharge voltages as low as 25 V. Thruster operation at this discharge voltage results in component erosion rates sufficiently low to satisfy most mission requirements. It has been recognized that most of the internal sputtering in ion thrusters is done by doubly charged ions. Knowledge of the sputtering threshold voltage of a xenon molybdenum system would be beneficial in understanding the sputtering process as well as making more accurate calculations of the sputtering rates of ion thruster components. Sputtering threshold energies calculated from various formulations found in the literature results in values ranging from 28 to 200 eV. It is evident that some of these formulations cannot be relied upon to provide sputtering thresholds with any degree of accuracy. This paper re-examines the threshold energies measurements made in the early sixties by Askerov and Sena, and Stuart and Wehner. The threshold voltages as derived by Askerov and au have been reevaluated by using a different extrapolation method of sputter yields at low ion energies. The resulting threshold energies are in general similar to those measured by Stuart and Wehner. An empirical relationship is derived,for mercury and xenon ions for the ratio of the sputtering threshold energy to the sublimation energy as a function of the ratio of target to ion atomic mass.

  5. Experimental realization of chaos control by thresholding.

    PubMed

    Murali, K; Sinha, Sudeshna

    2003-07-01

    We report the experimental verification of thresholding as a versatile tool for efficient and flexible chaos control. The strategy here simply involves monitoring a single state variable and resetting it when it exceeds a threshold. We demonstrate the success of the technique in rapidly controlling different chaotic electrical circuits, including a hyperchaotic circuit, onto stable fixed points and limit cycles of different periods, by thresholding just one variable. The simplicity of this controller entailing no run-time computation, and the ease and rapidity of switching between different targets it offers, suggests a potent tool for chaos based applications. PMID:12935228

  6. Air monitoring device

    NASA Technical Reports Server (NTRS)

    Tissandier, Michael D. (Inventor)

    2012-01-01

    An air monitoring device (100) includes an outer casing (101) configured to receive an airflow (102) comprising particulate; a bore (103) located inside the outer casing (101); and a collection probe (104) located inside the outer casing (101), the collection probe (104) being configured such that there is a gap (105) between an exit of the bore (103) and an entrance of the collection probe (104), such that particulate in the airflow (102) having a diameter larger than a threshold flows through an interior of the collection probe (104).

  7. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Newman, John A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  8. Characterizing multi-pollutant air pollution in China: Comparison of three air quality indices.

    PubMed

    Hu, Jianlin; Ying, Qi; Wang, Yungang; Zhang, Hongliang

    2015-11-01

    high air pollution events. Sensitivity studies were conducted to examine the assumptions used in the AAQI and HAQI approaches. Results show that AAQI is sensitive to the choice of pollutant irrelevant constant. HAQI is sensitive to the choice of both threshold values and pollutants included in total risk calculation. PMID:26197060

  9. Audiological results with Baha in conductive and mixed hearing loss.

    PubMed

    Pfiffner, Flurin; Caversaccio, Marco-Domenico; Kompis, Martin

    2011-01-01

    The level of improvement in the audiological results of Baha(®) users mainly depends on the patient's preoperative hearing thresholds and the type of Baha sound processor used. This investigation shows correlations between the preoperative hearing threshold and postoperative aided thresholds and audiological results in speech understanding in quiet of 84 Baha users with unilateral conductive hearing loss, bilateral conductive hearing loss and bilateral mixed hearing loss. Secondly, speech understanding in noise of 26 Baha users with different Baha sound processors (Compact, Divino, and BP100) is investigated. Linear regression between aided sound field thresholds and bone conduction (BC) thresholds of the better ear shows highest correlation coefficients and the steepest slope. Differences between better BC thresholds and aided sound field thresholds are smallest for mid-frequencies (1 and 2 kHz) and become larger at 0.5 and 4 kHz. For Baha users, the gain in speech recognition in quiet can be expected to lie in the order of magnitude of the gain in their hearing threshold. Compared to its predecessor sound processors Baha(®) Compact and Baha(®) Divino, Baha(®) BP100 improves speech understanding in noise significantly by +0.9 to +4.6 dB signal-to-noise ratio, depending on the setting and the use of directional microphone. For Baha users with unilateral and bilateral conductive hearing loss and bilateral mixed hearing loss, audiological results in aided sound field thresholds can be estimated with the better BC hearing threshold. The benefit in speech understanding in quiet can be expected to be similar to the gain in their sound field hearing threshold. The most recent technology of Baha sound processor improves speech understanding in noise by an order of magnitude that is well perceived by users and which can be very useful in everyday life. PMID:21389707

  10. 40 CFR 98.281 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Silicon Carbide Production § 98.281 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a silicon carbide production process...

  11. 40 CFR 98.281 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Silicon Carbide Production § 98.281 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a silicon carbide production process...

  12. 40 CFR 98.281 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Silicon Carbide Production § 98.281 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a silicon carbide production process...

  13. 40 CFR 98.281 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Silicon Carbide Production § 98.281 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a silicon carbide production process...

  14. 40 CFR 98.281 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Silicon Carbide Production § 98.281 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a silicon carbide production process...

  15. 40 CFR 98.141 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.141 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a glass production process and the facility meets...

  16. 40 CFR 98.141 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.141 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a glass production process and the facility meets...

  17. 40 CFR 98.141 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.141 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a glass production process and the facility meets...

  18. 40 CFR 98.141 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.141 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a glass production process and the facility meets...

  19. 40 CFR 98.141 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.141 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a glass production process and the facility meets...

  20. Error Threshold of Fully Random Eigen Model

    NASA Astrophysics Data System (ADS)

    Li, Duo-Fang; Cao, Tian-Guang; Geng, Jin-Peng; Qiao, Li-Hua; Gu, Jian-Zhong; Zhan, Yong

    2015-01-01

    Species evolution is essentially a random process of interaction between biological populations and their environments. As a result, some physical parameters in evolution models are subject to statistical fluctuations. In this work, two important parameters in the Eigen model, the fitness and mutation rate, are treated as Gaussian distributed random variables simultaneously to examine the property of the error threshold. Numerical simulation results show that the error threshold in the fully random model appears as a crossover region instead of a phase transition point, and as the fluctuation strength increases the crossover region becomes smoother and smoother. Furthermore, it is shown that the randomization of the mutation rate plays a dominant role in changing the error threshold in the fully random model, which is consistent with the existing experimental data. The implication of the threshold change due to the randomization for antiviral strategies is discussed.

  1. Threshold altitude resulting in decompression sickness

    NASA Technical Reports Server (NTRS)

    Kumar, K. V.; Waligora, James M.; Calkins, Dick S.

    1990-01-01

    A review of case reports, hypobaric chamber training data, and experimental evidence indicated that the threshold for incidence of altitude decompression sickness (DCS) was influenced by various factors such as prior denitrogenation, exercise or rest, and period of exposure, in addition to individual susceptibility. Fitting these data with appropriate statistical models makes it possible to examine the influence of various factors on the threshold for DCS. This approach was illustrated by logistic regression analysis on the incidence of DCS below 9144 m. Estimations using these regressions showed that, under a noprebreathe, 6-h exposure, simulated EVA profile, the threshold for symptoms occurred at approximately 3353 m; while under a noprebreathe, 2-h exposure profile with knee-bends exercise, the threshold occurred at 7925 m.

  2. 40 CFR 98.411 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Industrial Greenhouse Gases § 98.411 Reporting threshold. Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4) must report...

  3. 40 CFR 98.411 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Industrial Greenhouse Gases § 98.411 Reporting threshold. Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4) must report...

  4. 40 CFR 98.411 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Industrial Greenhouse Gases § 98.411 Reporting threshold. Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4) must report...

  5. 40 CFR 98.411 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Industrial Greenhouse Gases § 98.411 Reporting threshold. Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4) must report...

  6. 40 CFR 98.411 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Industrial Greenhouse Gases § 98.411 Reporting threshold. Any supplier of industrial greenhouse gases who meets the requirements of § 98.2(a)(4) must report...

  7. 40 CFR 98.41 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Electricity Generation § 98.41 Reporting threshold. You must report GHG emissions under this subpart if your facility contains one or more electricity generating units and...

  8. 40 CFR 98.41 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Electricity Generation § 98.41 Reporting threshold. You must report GHG emissions under this subpart if your facility contains one or more electricity generating units and...

  9. 40 CFR 98.331 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Zinc Production § 98.331 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a zinc production process and the facility meets...

  10. 40 CFR 98.331 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Zinc Production § 98.331 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a zinc production process and the facility meets...

  11. 40 CFR 98.331 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Zinc Production § 98.331 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a zinc production process and the facility meets...

  12. 40 CFR 98.331 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Zinc Production § 98.331 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a zinc production process and the facility meets...

  13. 40 CFR 98.331 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Zinc Production § 98.331 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a zinc production process and the facility meets...

  14. 40 CFR 98.341 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Municipal Solid Waste Landfills § 98.341 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a MSW landfill and the facility...

  15. Nonlinear theory of kinetic instabilities near threshold

    SciTech Connect

    Berk, H.L.; Pekker, M.S.; Breizman, B.N. |

    1997-05-01

    A new nonlinear equation has been derived and solved for the evolution of an unstable collective mode in a kinetic system close to the threshold of linear instability. The resonant particle response produces the dominant nonlinearity, which can be calculated iteratively in the near-threshold regime as long as the mode doe snot trap resonant particles. With sources and classical relaxation processes included, the theory describes both soft nonlinear regimes, where the mode saturation level is proportional to an increment above threshold, and explosive nonlinear regimes, where the mode grows to a level that is independent of the closeness to threshold. The explosive solutions exhibit mode frequency shifting. For modes that exist in the absence of energetic particles, the frequency shift is both upward and downward. For modes that require energetic particles for their existence, there is a preferred direction of the frequency shift. The frequency shift continues even after the mode traps resonant particles.

  16. Laser damage threshold of diamond films

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia; Cropper, Andre D.; Watkins, Linwood C.; Byvik, Charles E.; Buoncristiani, A. Martin

    1989-01-01

    The possibility that diamond films may inhibit laser-induced damage to optical components in laser systems films was investigated by measuring laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced CVD process. It was found that free-standing diamond films had the highest laser damage threshold at 1064 nm. For a diamond film of 630 nm, the damage threshold was found to be 7 J/sq cm, as compared to a damage threshold of 4.5 J/sq cm for bare silicon, and a low value of 1.5 J/sq cm for the film/substrate combination. The damage mechanism is considered to involve melting or dielectric breakdown induced by laser radiation. The low value of the film/substrate combination is attributed to film stress and conditions of film deposition.

  17. 40 CFR 98.291 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Soda Ash Manufacturing § 98.291 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a soda ash manufacturing process and the...

  18. 40 CFR 98.261 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Phosphoric Acid Production § 98.261 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a phosphoric acid production process...

  19. 40 CFR 98.261 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Phosphoric Acid Production § 98.261 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a phosphoric acid production process...

  20. 40 CFR 98.261 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Phosphoric Acid Production § 98.261 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a phosphoric acid production process...

  1. 40 CFR 98.261 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Phosphoric Acid Production § 98.261 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a phosphoric acid production process...

  2. 40 CFR 98.261 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Phosphoric Acid Production § 98.261 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a phosphoric acid production process...

  3. 40 CFR 98.81 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Cement Production § 98.81 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a cement production process and the facility...

  4. 40 CFR 98.81 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Cement Production § 98.81 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a cement production process and the facility...

  5. 40 CFR 98.61 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Aluminum Production § 98.61 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an aluminum production process and the facility...

  6. 40 CFR 98.61 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Aluminum Production § 98.61 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an aluminum production process and the facility...

  7. 40 CFR 98.61 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Aluminum Production § 98.61 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an aluminum production process and the facility...

  8. 40 CFR 98.61 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Aluminum Production § 98.61 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an aluminum production process and the facility...

  9. 40 CFR 98.61 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Aluminum Production § 98.61 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an aluminum production process and the facility...

  10. Laser damage threshold of diamond films

    NASA Astrophysics Data System (ADS)

    Albin, Sacharia; Cropper, Andre D.; Watkins, Linwood C.; Byvik, Charles E.; Buoncristiani, A. Martin

    1989-03-01

    The possibility that diamond films may inhibit laser-induced damage to optical components in laser systems films was investigated by measuring laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced CVD process. It was found that free-standing diamond films had the highest laser damage threshold at 1064 nm. For a diamond film of 630 nm, the damage threshold was found to be 7 J/sq cm, as compared to a damage threshold of 4.5 J/sq cm for bare silicon, and a low value of 1.5 J/sq cm for the film/substrate combination. The damage mechanism is considered to involve melting or dielectric breakdown induced by laser radiation. The low value of the film/substrate combination is attributed to film stress and conditions of film deposition.

  11. 40 CFR 98.41 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Electricity Generation § 98.41 Reporting threshold. You must report GHG emissions under this subpart if your facility contains one or more electricity generating units and...

  12. 40 CFR 98.41 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Electricity Generation § 98.41 Reporting threshold. You must report GHG emissions under this subpart if your facility contains one or more electricity generating units and...

  13. 40 CFR 98.41 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Electricity Generation § 98.41 Reporting threshold. You must report GHG emissions under this subpart if your facility contains one or more electricity generating units and...

  14. 40 CFR 98.31 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING General Stationary Fuel Combustion Sources § 98.31 Reporting threshold... combustion sources and the facility meets the applicability requirements of either § 98.2(a)(1), §...

  15. 40 CFR 98.401 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Natural Gas and Natural Gas Liquids § 98.401 Reporting threshold. Any supplier of natural gas and natural gas liquids that meets the requirements of §...

  16. 40 CFR 98.161 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.161 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a hydrogen production process and the facility...

  17. 40 CFR 98.161 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.161 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a hydrogen production process and the facility...

  18. 40 CFR 98.161 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.161 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a hydrogen production process and the facility...

  19. 40 CFR 98.161 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.161 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a hydrogen production process and the facility...

  20. [Nonlinear magnetohydrodynamics]. [Threshold unstable MHD activity

    SciTech Connect

    Not Available

    1992-01-01

    Theoretical predictions were compared with available data from JET on the threshold unstable MHD activity in toroidal confinement devices. In particular, questions arising as to Hartmans number and the selection of a kinematic viscosity are discussed.

  1. 40 CFR 98.71 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Ammonia Manufacturing § 98.71 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an ammonia manufacturing process and the...

  2. 40 CFR 98.71 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Ammonia Manufacturing § 98.71 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an ammonia manufacturing process and the...

  3. 40 CFR 98.71 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Ammonia Manufacturing § 98.71 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an ammonia manufacturing process and the...

  4. 40 CFR 98.71 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Ammonia Manufacturing § 98.71 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an ammonia manufacturing process and the...

  5. 40 CFR 98.71 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Ammonia Manufacturing § 98.71 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an ammonia manufacturing process and the...

  6. 40 CFR 98.401 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Natural Gas and Natural Gas Liquids § 98.401 Reporting threshold. Any supplier of natural gas and natural gas liquids that meets the requirements of §...

  7. 40 CFR 98.401 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Natural Gas and Natural Gas Liquids § 98.401 Reporting threshold. Any supplier of natural gas and natural gas liquids that meets the requirements of §...

  8. 40 CFR 98.401 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Natural Gas and Natural Gas Liquids § 98.401 Reporting threshold. Any supplier of natural gas and natural gas liquids that meets the requirements of §...

  9. 40 CFR 98.401 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Natural Gas and Natural Gas Liquids § 98.401 Reporting threshold. Any supplier of natural gas and natural gas liquids that meets the requirements of §...

  10. 40 CFR 98.321 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Underground Coal Mines § 98.321 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an active underground coal mine and the...

  11. 40 CFR 98.381 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Coal-based Liquid Fuels § 98.381 Reporting threshold. Any supplier of coal-to-liquid products who meets the requirements of § 98.2(a)(4) must report GHG emissions....

  12. 40 CFR 98.321 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Underground Coal Mines § 98.321 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an active underground coal mine and the...

  13. 40 CFR 98.381 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Coal-based Liquid Fuels § 98.381 Reporting threshold. Any supplier of coal-to-liquid products who meets the requirements of § 98.2(a)(4) must report GHG emissions....

  14. 40 CFR 98.381 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Coal-based Liquid Fuels § 98.381 Reporting threshold. Any supplier of coal-to-liquid products who meets the requirements of § 98.2(a)(4) must report GHG emissions....

  15. 40 CFR 98.381 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Coal-based Liquid Fuels § 98.381 Reporting threshold. Any supplier of coal-to-liquid products who meets the requirements of § 98.2(a)(4) must report GHG emissions....

  16. 40 CFR 98.381 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Suppliers of Coal-based Liquid Fuels § 98.381 Reporting threshold. Any supplier of coal-to-liquid products who meets the requirements of § 98.2(a)(4) must report GHG emissions....

  17. 40 CFR 98.321 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Underground Coal Mines § 98.321 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an active underground coal mine and the...

  18. 40 CFR 98.321 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Underground Coal Mines § 98.321 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an active underground coal mine and the...

  19. 40 CFR 98.161 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.161 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a hydrogen production process and the facility...

  20. 40 CFR 98.171 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Iron and Steel Production § 98.171 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an iron and steel production process...

  1. 40 CFR 98.171 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Iron and Steel Production § 98.171 Reporting threshold. You must report GHG emissions under this subpart if your facility contains an iron and steel production process...

  2. 40 CFR 98.201 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Magnesium Production § 98.201 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a magnesium production process and the facility...

  3. 40 CFR 98.201 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Magnesium Production § 98.201 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a magnesium production process and the facility...

  4. 40 CFR 98.201 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Magnesium Production § 98.201 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a magnesium production process and the facility...

  5. 40 CFR 98.201 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Magnesium Production § 98.201 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a magnesium production process and the facility...

  6. 40 CFR 98.311 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.311 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a titanium dioxide production process...

  7. 40 CFR 98.311 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.311 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a titanium dioxide production process...

  8. 40 CFR 98.311 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.311 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a titanium dioxide production process...

  9. 40 CFR 98.311 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.311 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a titanium dioxide production process...

  10. 40 CFR 98.311 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.311 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a titanium dioxide production process...

  11. 40 CFR 98.221 - Reporting threshold.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Nitric Acid Production § 98.221 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a nitric acid train and the facility meets...

  12. Vanishing of {1}/{m} corrections at threshold

    NASA Astrophysics Data System (ADS)

    Boyd, C. Glenn; Brahm, David E.

    1991-03-01

    Heavy-quark predictions for hadronic weak-decay transition amplitudes have O( {1}/{m}) corrections, but we show these always vanish at threshold. This follows from the nonrenormalization of the threshold effective currents at O( {1}/{m}) , and an application of the Ademollo-Gatto theorem. The result, which we call Luke's theorem, holds for initial and final particles consisting of a heavy quark or scalar and light degrees of freedom in an arbitrary spin state.

  13. Optimizing Retransmission Threshold in Wireless Sensor Networks.

    PubMed

    Bi, Ran; Li, Yingshu; Tan, Guozhen; Sun, Liang

    2016-01-01

    The retransmission threshold in wireless sensor networks is critical to the latency of data delivery in the networks. However, existing works on data transmission in sensor networks did not consider the optimization of the retransmission threshold, and they simply set the same retransmission threshold for all sensor nodes in advance. The method did not take link quality and delay requirement into account, which decreases the probability of a packet passing its delivery path within a given deadline. This paper investigates the problem of finding optimal retransmission thresholds for relay nodes along a delivery path in a sensor network. The object of optimizing retransmission thresholds is to maximize the summation of the probability of the packet being successfully delivered to the next relay node or destination node in time. A dynamic programming-based distributed algorithm for finding optimal retransmission thresholds for relay nodes along a delivery path in the sensor network is proposed. The time complexity is O n Δ · max 1 ≤ i ≤ n { u i } , where u i is the given upper bound of the retransmission threshold of sensor node i in a given delivery path, n is the length of the delivery path and Δ is the given upper bound of the transmission delay of the delivery path. If Δ is greater than the polynomial, to reduce the time complexity, a linear programming-based ( 1 + p m i n ) -approximation algorithm is proposed. Furthermore, when the ranges of the upper and lower bounds of retransmission thresholds are big enough, a Lagrange multiplier-based distributed O ( 1 ) -approximation algorithm with time complexity O ( 1 ) is proposed. Experimental results show that the proposed algorithms have better performance. PMID:27171092

  14. Flicker fusion thresholds in Best macular dystrophy.

    PubMed

    Massof, R W; Fleischman, J A; Fine, S L; Yoder, F

    1977-06-01

    Flicker fusion threshold intensities were measured as a function of flicker frequency for patients with Best macular dystrophy having normal or near-normal Snellen visual acuity. These data were found to differ from normal in ways that may be interpreted to be an abnormal elevation of the foveal cone threshold, a loss of cone temporal resolution, or both. The results led to the conclusion that Best macular dystrophy affects the neurosensory retina even when Snellen visual acuity is normal. PMID:869758

  15. Optimizing Retransmission Threshold in Wireless Sensor Networks

    PubMed Central

    Bi, Ran; Li, Yingshu; Tan, Guozhen; Sun, Liang

    2016-01-01

    The retransmission threshold in wireless sensor networks is critical to the latency of data delivery in the networks. However, existing works on data transmission in sensor networks did not consider the optimization of the retransmission threshold, and they simply set the same retransmission threshold for all sensor nodes in advance. The method did not take link quality and delay requirement into account, which decreases the probability of a packet passing its delivery path within a given deadline. This paper investigates the problem of finding optimal retransmission thresholds for relay nodes along a delivery path in a sensor network. The object of optimizing retransmission thresholds is to maximize the summation of the probability of the packet being successfully delivered to the next relay node or destination node in time. A dynamic programming-based distributed algorithm for finding optimal retransmission thresholds for relay nodes along a delivery path in the sensor network is proposed. The time complexity is OnΔ·max1≤i≤n{ui}, where ui is the given upper bound of the retransmission threshold of sensor node i in a given delivery path, n is the length of the delivery path and Δ is the given upper bound of the transmission delay of the delivery path. If Δ is greater than the polynomial, to reduce the time complexity, a linear programming-based (1+pmin)-approximation algorithm is proposed. Furthermore, when the ranges of the upper and lower bounds of retransmission thresholds are big enough, a Lagrange multiplier-based distributed O(1)-approximation algorithm with time complexity O(1) is proposed. Experimental results show that the proposed algorithms have better performance. PMID:27171092

  16. Optical spectral singularities as threshold resonances

    SciTech Connect

    Mostafazadeh, Ali

    2011-04-15

    Spectral singularities are among generic mathematical features of complex scattering potentials. Physically they correspond to scattering states that behave like zero-width resonances. For a simple optical system, we show that a spectral singularity appears whenever the gain coefficient coincides with its threshold value and other parameters of the system are selected properly. We explore a concrete realization of spectral singularities for a typical semiconductor gain medium and propose a method of constructing a tunable laser that operates at threshold gain.

  17. Initiation Pressure Thresholds from Three Sources

    SciTech Connect

    Souers, P C; Vitello, P

    2007-02-28

    Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run-to-detonation times are the poorest source but the fitting of a function gives rough results. Flyer-induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data is in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half-width time pulses in the spacers may be used to create a pressure-time curve similar to that of the flyers. The very-large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much-expanded set of near-asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX-17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm{sup 3}, respectively.

  18. Quantitative mammography contrast threshold test tool.

    PubMed

    Wagner, A J; Frey, G D

    1995-02-01

    Mammographic contrast is commonly evaluated by visualizing small objects of varying size or mass divided by projected area. These qualitative contrast determinations are commonly performed by imaging a phantom like the American College of Radiology accreditation phantom at clinical mammographic settings. However, this contrast assessment does not take into account the kVp of the machine. This work describes a quantitative mammography contrast threshold test tool which examines light object contrast on a uniform background for a contrast range of 0.32% to 1.38% at 25 kVp. For this mammography contrast threshold test tool, contrast is defined by delta I/I = loge (psi O/ psi b), where psi O is the target energy flux, and psi b is the background energy flux. Contrast threshold is defined as the lowest contrast value for which the objects are visible. Unlike traditional assessments of mammographic contrast, this measurement of contrast threshold is kVp corrected. The mammography contrast threshold test tool is constructed out of common plastics and provides a quantitative means of assessing contrast threshold for individual mammographic units and total mammographic systems. PMID:7565343

  19. Cluster-span threshold: An unbiased threshold for binarising weighted complete networks in functional connectivity analysis.

    PubMed

    Smith, Keith; Azami, Hamed; Parra, Mario A; Starr, John M; Escudero, Javier

    2015-08-01

    We propose a new unbiased threshold for network analysis named the Cluster-Span Threshold (CST). This is based on the clustering coefficient, C, following logic that a balance of `clustering' to `spanning' triples results in a useful topology for network analysis and that the product of complementing properties has a unique value only when perfectly balanced. We threshold networks by fixing C at this balanced value, rather than fixing connection density at an arbitrary value, as has been the trend. We compare results from an electroencephalogram data set of volunteers performing visual short term memory tasks of the CST alongside other thresholds, including maximum spanning trees. We find that the CST holds as a sensitive threshold for distinguishing differences in the functional connectivity between tasks. This provides a sensitive and objective method for setting a threshold on weighted complete networks which may prove influential on the future of functional connectivity research. PMID:26736883

  20. Air heating system

    DOEpatents

    Primeau, John J.

    1983-03-01

    A self-starting, fuel-fired, air heating system including a vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with the provision of heat exchanger and circuitry for cooling the condensed fluid output from the pump prior to its return to the vapor generator.

  1. Fluence thresholds for grazing incidence hard x-ray mirrors

    SciTech Connect

    Aquila, A.; Ozkan, C.; Sinn, H.; Tschentscher, T.; Mancuso, A. P.; Gaudin, J.; Sobierajski, R.; Klepka, M. T.; Dłużewski, P.; Morawiec, K.; Störmer, M.; Bajt, S.; Ohashi, H.; Koyama, T.; Tono, K.; Inubushi, Y. [RIKEN and others

    2015-06-15

    X-ray Free Electron Lasers (XFELs) have the potential to contribute to many fields of science and to enable many new avenues of research, in large part due to their orders of magnitude higher peak brilliance than existing and future synchrotrons. To best exploit this peak brilliance, these XFEL beams need to be focused to appropriate spot sizes. However, the survivability of X-ray optical components in these intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at XFEL facilities, a physical understanding of the interaction between intense X-ray pulses and grazing incidence X-ray optics is desirable. We conducted single shot damage threshold fluence measurements on grazing incidence X-ray optics, with coatings of ruthenium and boron carbide, at the SPring-8 Angstrom compact free electron laser facility using 7 and 12 keV photon energies. The damage threshold dose limits were found to be orders of magnitude higher than would naively be expected. The incorporation of energy transport and dissipation via keV level energetic photoelectrons accounts for the observed damage threshold.

  2. Uncertainty Estimates of Psychoacoustic Thresholds Obtained from Group Tests

    NASA Technical Reports Server (NTRS)

    Rathsam, Jonathan; Christian, Andrew

    2016-01-01

    Adaptive psychoacoustic test methods, in which the next signal level depends on the response to the previous signal, are the most efficient for determining psychoacoustic thresholds of individual subjects. In many tests conducted in the NASA psychoacoustic labs, the goal is to determine thresholds representative of the general population. To do this economically, non-adaptive testing methods are used in which three or four subjects are tested at the same time with predetermined signal levels. This approach requires us to identify techniques for assessing the uncertainty in resulting group-average psychoacoustic thresholds. In this presentation we examine the Delta Method of frequentist statistics, the Generalized Linear Model (GLM), the Nonparametric Bootstrap, a frequentist method, and Markov Chain Monte Carlo Posterior Estimation and a Bayesian approach. Each technique is exercised on a manufactured, theoretical dataset and then on datasets from two psychoacoustics facilities at NASA. The Delta Method is the simplest to implement and accurate for the cases studied. The GLM is found to be the least robust, and the Bootstrap takes the longest to calculate. The Bayesian Posterior Estimate is the most versatile technique examined because it allows the inclusion of prior information.

  3. Thresholds for the onset of fluid and magnetofluid turbulence

    NASA Technical Reports Server (NTRS)

    Montgomery, D.

    1982-01-01

    Linear stability calculations conducted in plasma physics are based on the theory of hydrodynamic stability of neutral fluids. The present investigation is concerned with the validity of procedures based on linear stability analysis in six much-studied situations. All have the property that the fluid goes from laminar to turbulent at critical values of some dimensionless number, such as the Reynolds number or the Rayleigh number. The question is, at what threshold values of the dimensionless number do the unstable motions set in, and can these thresholds be predicted by a linear analysis of the stability of the laminar state as the threshold is approached from the stable side. In three cases linear stability analysis clearly seems to fail. These cases include Plane Poiseuille Flow, Plane Couette Flow, and Cylindrical Pipe Flow (Hagen-Poiseuille Flow). Situations in which predictions provided by linear stability analysis are correct are related to Rotating Couette Flow, Thermally-Driven Convection, and Instability of Laminar Boundary Layers.

  4. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming; Gottesfeld, Shimshon

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source. Water loss from the cell is minimized by making the conductive cathode assembly hydrophobic and the conductive anode assembly hydrophilic.

  5. Ultrasonic determination of thermodynamic threshold parameters for irreversible cutaneous burns

    NASA Technical Reports Server (NTRS)

    Cantrell, J. H., Jr.

    1982-01-01

    In vivo ultrasonic measurements of the depth of conductive cutaneous burns experimentally induced in anesthetized Yorkshire pigs are reported as a function of burn time for the case in which the skin surface temperature is maintained at 100 C. The data are used in the solution of the one-dimensional heat diffusion equation with time-dependent boundary conditions to obtain the threshold temperature and the energy of transformation per unit mass associated with the transition of the tissue from the state of viability to the state of necrosis. The simplicity of the mathematical model and the expediency of the ultrasonic measurements in studies of thermal injury are emphasized.

  6. Siamang gibbons exceed the saccular threshold: Intensity of the song of Hylobates syndactylus

    NASA Astrophysics Data System (ADS)

    McAngus Todd, Neil P.; Merker, Bjorn

    2004-06-01

    Measurements are reported of the intensity of the siamang gibbon loud call obtained from the vocal bouts of three family groups at Twycross Zoo, UK. Across 25 samples the maximum intensity ranged from 95 to 113 dB SPL (linear frequency-weighting and fast time-weighting) and exhibited three frequency modes of 250-315 Hz, 630-800 Hz and 1.2-1.6 kHz. The lowest frequency mode, which may correspond to the ``boom'' sound produced by resonance of the siamang inflated vocal sac, had a mean maximum intensity of 99 dB SPL. These values, which are in excess of the saccular acoustic threshold of about 90 dB at 300 Hz for air conducted sound, suggest that primate loud calls recruit a primitive mode of acoustic sensitivity furnished by the sacculus. Thus reproductive vocal behavior of primates may be influenced by a primitive acoustical reward pathway inherited from a common ancestor with anamniotes. In humans such a pathway could explain the compulsion for exposure to loud music.

  7. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source.

  8. Aeolian Sand Transport in the Planetary Context: Respective Roles of Aerodynamic and Bed-Dilatancy Thresholds

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.; Borucki, J.; Bratton, C.

    1999-01-01

    The traditional view of aeolian sand transport generally estimates flux from the perspective of aerodynamic forces creating the airborne grain population, although it has been recognized that "reptation" causes a significant part of the total airborne flux; reptation involves both ballistic injection of grains into the air stream by the impact of saltating grains as well as the "nudging" of surface grains into a creeping motion. Whilst aerodynamic forces may initiate sand motion, it is proposed here that within a fully-matured grain cloud, flux is actually governed by two thresholds: an aerodynamic threshold, and a bed-dilatancy threshold. It is the latter which controls the reptation population, and its significance increases proportionally with transport energy. Because we only have experience with terrestrial sand transport, extrapolations of aeolian theory to Mars and Venus have adjusted only the aerodynamic factor, taking gravitational forces and atmospheric density as the prime variables in the aerodynamic equations, but neglecting reptation. The basis for our perspective on the importance of reptation and bed dilatancy is a set of experiments that were designed to simulate sand transport across the surface of a martian dune. Using a modified sporting crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism, individual grains of sand were fired at loose sand targets with glancing angles typical of saltation impact; grains were projected at about 80 m/s to simulate velocities commensurate with those predicted for extreme martian aeolian conditions. The sabot impelling method permitted study of individual impacts without the masking effect of bed mobilization encountered in wind-tunnel studies. At these martian impact velocities, grains produced small craters formed by the ejection of several hundred grains from the bed. Unexpectedly, the craters were not elongated, despite glancing impact; the craters were very close to circular in planform

  9. Aeolian Sand Transport in the Planetary Context: Respective Roles of Aerodynamic and Bed-Dilatancy Thresholds

    NASA Astrophysics Data System (ADS)

    Marshall, J. R.; Borucki, J.; Bratton, C.

    1999-09-01

    The traditional view of aeolian sand transport generally estimates flux from the perspective of aerodynamic forces creating the airborne grain population, although it has been recognized that "reptation" causes a significant part of the total airborne flux; reptation involves both ballistic injection of grains into the air stream by the impact of saltating grains as well as the "nudging" of surface grains into a creeping motion. Whilst aerodynamic forces may initiate sand motion, it is proposed here that within a fully-matured grain cloud, flux is actually governed by two thresholds: an aerodynamic threshold, and a bed-dilatancy threshold. It is the latter which controls the reptation population, and its significance increases proportionally with transport energy. Because we only have experience with terrestrial sand transport, extrapolations of aeolian theory to Mars and Venus have adjusted only the aerodynamic factor, taking gravitational forces and atmospheric density as the prime variables in the aerodynamic equations, but neglecting reptation. The basis for our perspective on the importance of reptation and bed dilatancy is a set of experiments that were designed to simulate sand transport across the surface of a martian dune. Using a modified sporting crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism, individual grains of sand were fired at loose sand targets with glancing angles typical of saltation impact; grains were projected at about 80 m/s to simulate velocities commensurate with those predicted for extreme martian aeolian conditions. The sabot impelling method permitted study of individual impacts without the masking effect of bed mobilization encountered in wind-tunnel studies. At these martian impact velocities, grains produced small craters formed by the ejection of several hundred grains from the bed. Unexpectedly, the craters were not elongated, despite glancing impact; the craters were very close to circular in planform

  10. Entrainment of Air into Vertical Jets in a Crosswind

    NASA Astrophysics Data System (ADS)

    Roberts, K. K.; Solovitz, S.; Freedland, G.; Camp, E.; Cal, R. B.; Mastin, L. G.

    2015-12-01

    During volcanic eruptions, ash concentration must be determined for aviation safety, but the limiting threshold is difficult to distinguish visually. Computational models are typically used to predict ash concentrations, using inputs such as plume height, eruptive duration, and wind speeds. The models also depend on empirical parameters, such as the entrainment of atmospheric air as a ratio of the air inflow speed and the jet speed. Entrainment of atmospheric air plays a critical role in the behavior of volcanic plumes in the atmosphere, impacting the mass flow rate, buoyancy, and particle concentration of the plume. This process is more complex in a crosswind, leading to greater uncertainty in the model results. To address these issues, a laboratory-scale study has been conducted to improve the entrainment models. Observations of a vertical, unconfined jet are performed using Particle Image Velocimetry, while varying jet density using different compressed gases and Reynolds number. To test the effects of a crosswind on plume entrainment rates, these are then compared with similar jet experiments in a wind tunnel. A series of jet geometries, jet speeds and tunnel speeds are considered. The measured velocities are used to determine the entrainment response, which can be used to determine ash concentration over time as atmospheric air is entrained into the plume. We also quantify the mean and the fluctuations in flow velocity.

  11. Air resources

    SciTech Connect

    1995-10-01

    This section describes the ambient (surrounding) air quality of the TVA region, discusses TVA emission contributions to ambient air quality, and identifies air quality impacts to human health and welfare. Volume 2 Technical Document 2, Environmental Consequences, describes how changes in TVA emissions could affect regional air quality, human health, environmental resources, and materials. The primary region of the affected environment is broadly defined as the state of Tennessee, as well as southern Kentucky, western Virginia, southern West Virginia, western North Carolina, and northern Georgia, Alabama, and Mississippi. This area represents the watershed of the Tennessee River and the 201 counties of the greater TVA service area. Emissions from outside the Tennessee Valley region contribute to air quality in the Valley. Also, TVA emissions are transported outside the Valley and have some impact on air quality beyond the primary study area. Although the study area experiences a number of air quality problems, overall air quality is good.

  12. Electronic Conduction in Ti/Poly-TiO2/Ti Structures.

    PubMed

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-01-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2-x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets. PMID:27404085

  13. Electronic Conduction in Ti/Poly-TiO2/Ti Structures

    PubMed Central

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-01-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2−x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 106 V.m−1; higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets. PMID:27404085

  14. Electronic Conduction in Ti/Poly-TiO2/Ti Structures

    NASA Astrophysics Data System (ADS)

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-07-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2‑x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 106 V.m‑1 higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets.

  15. Experimental investigation of plastic finned-tube heat exchangers, with emphasis on material thermal conductivity

    SciTech Connect

    Chen, Lin; Li, Zhen; Guo, Zeng-Yuan

    2009-07-15

    In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)

  16. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  17. Threshold concepts in finance: conceptualizing the curriculum

    NASA Astrophysics Data System (ADS)

    Hoadley, Susan; Tickle, Leonie; Wood, Leigh N.; Kyng, Tim

    2015-08-01

    Graduates with well-developed capabilities in finance are invaluable to our society and in increasing demand. Universities face the challenge of designing finance programmes to develop these capabilities and the essential knowledge that underpins them. Our research responds to this challenge by identifying threshold concepts that are central to the mastery of finance and by exploring their potential for informing curriculum design and pedagogical practices to improve student outcomes. In this paper, we report the results of an online survey of finance academics at multiple institutions in Australia, Canada, New Zealand, South Africa and the United Kingdom. The outcomes of our research are recommendations for threshold concepts in finance endorsed by quantitative evidence, as well as a model of the finance curriculum incorporating finance, modelling and statistics threshold concepts. In addition, we draw conclusions about the application of threshold concept theory supported by both quantitative and qualitative evidence. Our methodology and findings have general relevance to the application of threshold concept theory as a means to investigate and inform curriculum design and delivery in higher education.

  18. Ignition threshold for impact-generated fires

    NASA Astrophysics Data System (ADS)

    Durda, Daniel D.; Kring, David A.

    2004-08-01

    Widespread fires can be generated after large impact events by atmospheric heating caused by the reaccretion of high-energy, vapor-rich plume material. We examine the threshold irradiance levels necessary for spontaneous and pilot ignition of various types of vegetation and define three specific cases for investigation: (1) 51 kW/m2 for a period of at least 2 min to spontaneously ignite wood; (2) 20 kW/m2 for a period of at least 20 min to ignite wood in the presence of an ignition source; and (3) 28 kW/m2 for a period of at least 1 min to ignite foliage, rotten wood, and forest litter. The threshold ejected plume mass for continent-wide spontaneous ignition of wood is ~2 to 6 × 1015 kg, independent of impact location but dependent on the details of the ejecta speed distribution. The threshold ejected plume mass for global spontaneous ignition of wood is in the range ~1 to 2 × 1016 kg. The threshold plume masses for continent-wide and global fires are very nearly the same for piloted ignition of wood, while the threshold plume masses for continent-wide and global ignition of leaves and forest litter are significantly lower, by a factor of ~2 to 3. Impact craters of at least 85 km diameter are needed to produce continental-scale fires, and craters of ~135 km diameter are needed for global-scale fires.

  19. Thresholds for Epidemic Spreading in Networks

    NASA Astrophysics Data System (ADS)

    Castellano, Claudio; Pastor-Satorras, Romualdo

    2010-11-01

    We study the threshold of epidemic models in quenched networks with degree distribution given by a power-law. For the susceptible-infected-susceptible model the activity threshold λc vanishes in the large size limit on any network whose maximum degree kmax⁡ diverges with the system size, at odds with heterogeneous mean-field (HMF) theory. The vanishing of the threshold has nothing to do with the scale-free nature of the network but stems instead from the largest hub in the system being active for any spreading rate λ>1/kmax⁡ and playing the role of a self-sustained source that spreads the infection to the rest of the system. The susceptible-infected-removed model displays instead agreement with HMF theory and a finite threshold for scale-rich networks. We conjecture that on quenched scale-rich networks the threshold of generic epidemic models is vanishing or finite depending on the presence or absence of a steady state.

  20. Motion parallax thresholds for unambiguous depth perception.

    PubMed

    Holmin, Jessica; Nawrot, Mark

    2015-10-01

    The perception of unambiguous depth from motion parallax arises from the neural integration of retinal image motion and extra-retinal eye movement signals. It is only recently that these parameters have been articulated in the form of the motion/pursuit ratio. In the current study, we explored the lower limits of the parameter space in which observers could accurately perform near/far relative depth-sign discriminations for a translating random-dot stimulus. Stationary observers pursued a translating random dot stimulus containing relative image motion. Their task was to indicate the location of the peak in an approximate square-wave stimulus. We measured thresholds for depth from motion parallax, quantified as motion/pursuit ratios, as well as lower motion thresholds and pursuit accuracy. Depth thresholds were relatively stable at pursuit velocities 5-20 deg/s, and increased at lower and higher velocities. The pattern of results indicates that minimum motion/pursuit ratios are limited by motion and pursuit signals, both independently and in combination with each other. At low and high pursuit velocities, depth thresholds were limited by inaccurate pursuit signals. At moderate pursuit velocities, depth thresholds were limited by motion signals. PMID:26232612

  1. Threshold of the precedence effect in noise

    PubMed Central

    Freyman, Richard L.; Griffin, Amanda M.; Zurek, Patrick M.

    2014-01-01

    Three effects that show a temporal asymmetry in the influence of interaural cues were studied through the addition of masking noise: (1) The transient precedence effect—the perceptual dominance of a leading transient over a similar lagging transient; (2) the ongoing precedence effect—lead dominance with lead and lag components that extend in time; and (3) the onset capture effect—determination by an onset transient of the lateral position of an otherwise ambiguous extended trailing sound. These three effects were evoked with noise-burst stimuli and were compared in the presence of masking noise. Using a diotic noise masker, detection thresholds for stimuli with lead/lag interaural delays of 0/500 μs were compared to those with 500/0 μs delays. None of the three effects showed a masking difference between those conditions, suggesting that none of the effects is operative at masked threshold. A task requiring the discrimination between stimuli with 500/0 and 0/500 μs interaural delays was used to determine the threshold for each effect in noise. The results showed similar thresholds in noise (10–13 dB SL) for the transient and ongoing precedence effects, but a much higher threshold (33 dB SL) for onset capture of an ambiguous trailing sound. PMID:24815272

  2. Studies in Above- and Below-Threshold Harmonics in Argon with an Infrared Femtosecond Laser

    NASA Astrophysics Data System (ADS)

    Chew, Andrew; Yin, Yanchun; Li, Jie; Ren, Xiaoming; Cunningham, Eric; Wu, Yi; Chang, Zenghu

    2016-05-01

    We investigate and compare the above- and below-threshold harmonics in Argon gas using our recently-developed 1 kHz, two-cycle (11.4 fs), 3mJ, and carrier-envelope-phase(CEP)-stable laser at 1.6 μm. Such ultraviolet pulses can serve as pump or probe for studying dynamics in atoms and molecules. Unlike high harmonics with photon energy well above the ionization potential, the mechanism for generating harmonics near the ionization threshold is still under intense investigation. Previous work by Chini et al. on below-threshold harmonics was done using a 0.8 μm few-cycle Ti:Sapphire spectrally-broadened source with energy up to 300 μJ. It has been predicted by theory that free-free transitions dominate the below threshold harmonic generation as the laser wavelength increase from near infrared to mid-infrared. We are therefore interested in investigating how using a longer wavelength laser might lead to changes to the behavior of below-threshold harmonics when we vary various parameters. We report the π-periodity CEP dependence and ellipticity dependence of the above- and below-threshold harmonics. This material was based on work supported by National Science Foundation (1068604), Army Research Office (W911NF-14-1-0383), Air Force Office of Scientific Research (FA9550-15-1-0037) and the DARPA PULSE program by a Grant from AMRDEC (W31P4Q1310017).

  3. Improving Forecast Skill by Assimilation of AIRS Temperature Soundings

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Reale, Oreste

    2010-01-01

    AIRS was launched on EOS Aqua on May 4, 2002, together with AMSU-A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU-A are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The AIRS Version 5 retrieval algorithm, is now being used operationally at the Goddard DISC in the routine generation of geophysical parameters derived from AIRS/AMSU data. A major innovation in Version 5 is the ability to generate case-by-case level-by-level error estimates delta T(p) for retrieved quantities and the use of these error estimates for Quality Control. We conducted a number of data assimilation experiments using the NASA GEOS-5 Data Assimilation System as a step toward finding an optimum balance of spatial coverage and sounding accuracy with regard to improving forecast skill. The model was run at a horizontal resolution of 0.5 deg. latitude X 0.67 deg longitude with 72 vertical levels. These experiments were run during four different seasons, each using a different year. The AIRS temperature profiles were presented to the GEOS-5 analysis as rawinsonde profiles, and the profile error estimates delta (p) were used as the uncertainty for each measurement in the data assimilation process. We compared forecasts analyses generated from the analyses done by assimilation of AIRS temperature profiles with three different sets of thresholds; Standard, Medium, and Tight. Assimilation of Quality Controlled AIRS temperature profiles significantly improve 5-7 day forecast skill compared to that obtained without the benefit of AIRS data in all of the cases studied. In addition, assimilation of Quality Controlled AIRS temperature soundings performs better than assimilation of AIRS observed radiances. Based on the experiments shown, Tight Quality Control of AIRS temperature profile performs best

  4. Electrically conductive and thermally conductive materials for electronic packaging

    NASA Astrophysics Data System (ADS)

    Liu, Zongrong

    The aim of this dissertation is to develop electrically or thermally conductive materials that are needed for electronic packaging and microelectronic cooling. These materials are in the form of coatings and are made from pastes. The research work encompasses paste formulation, studying the process of converting a paste to a conductive material, relating the processing conditions to the structure and performance, and evaluating performance attributes that are relevant to the application of these conductive materials. The research has resulted in new information that is valuable to the microelectronic industry. Work on electrically conductive materials emphasizes the development of electrical interconnection materials in the form of air-firable glass-free silver-based electrically conductive thick films, which use the Ti-Al alloy as the binder and are in contrast to conventional films that use glass as the binder. The air-firability, as enabled by minor additions of tin and zinc to the paste, is in contrast to previous glass-free films that are not firable. The recommended firing condition is 930°C in air. The organic vehicle in the paste comprises ethyl cellulose, which undergoes thermal decomposition during burnout of the paste. The ethyl cellulose is dissolved in ether, which facilitates the burnout. Excessive ethyl cellulose hinders the burnout. A higher heating rate results in more residue after burnout. The presence of silver particles facilitates drying and burnout. Firing in air gives lower resistivity than firing in oxygen. Firing in argon gives poor films. Compared to conventional films that use glass as the binder, these films, when appropriately fired, exhibit lower electrical resistivity (2.5 x 10-6 O.cm) and higher scratch resistance. Work on thermally conductive materials addresses thermal interface materials, which are materials placed at the interface between a heat sink and a heat source for the purpose of improving the thermal contact. Heat

  5. L-H Threshold Studies in NSTX

    SciTech Connect

    Kaye, S. M.; Maingi, Rajesh; Battaglia, D. J.; Bell, R. E.; Chang, C. S.; Hosea, J.; Kugel, H. W.; LaBlanc, B. P.; Meyer, H.; Wilson, J. R.

    2011-01-01

    Recent experiments in the low aspect ratio National Spherical Torus Experiment (NSTX) have been run in support of the high priority ITER and ITPA issue of access to the H-mode. Specifically, a series of experiments showed reduced power threshold values for deuterium versus helium plasmas, and for plasmas with lower current, lower triangularity and with lithium conditioning. Application of n = 3 fields at the plasma edge resulted in higher power thresholds. To within the constraints of temporal and spatial resolutions, no systematic difference in T(e), n(e), p(e), T(i), v or their derivatives was found in discharges that transitioned into the H-mode versus those at slightly lower power that did not. Finally, H(98y,2) similar to 1 confinement quality could be achieved for powers just above the threshold power in ELM-free conditions.

  6. L-H Threshold Studies in NSTX

    SciTech Connect

    Kaye, S M; Battaglia, D; Bell, R E; Chang, C S; Hosea, J; Kugel, H; LeBlanc, B P; Meyer, H; Park, G Y

    2011-09-06

    Recent experiments in the low aspect ratio National Spherical Torus Experiment (NSTX) have been run in support of the high priority ITER and ITPA issue of access to the H-mode. Specifically, a series of experiments showed reduced power threshold values for deuterium vs helium plasmas, and for plasmas with lower current, lower triangularity and with lithium conditioning. Application of n=3 fields at the plasma edge resulted in higher power thresholds. To within the constraints of temporal and spatial resolutions, no systematic difference in T{sub e}, n{sub e}, p{sub e}, T{sub i}, v or their derivatives was found in discharges that transitioned into the H-mode versus those at slightly lower power that did not. Finally, H{sub 98y,2} {approx} 1 confinement quality could be achieved for powers just above the threshold power in ELM-free conditions.

  7. Effects of pulse duration on magnetostimulation thresholds

    SciTech Connect

    Saritas, Emine U.; Goodwill, Patrick W.; Conolly, Steven M.

    2015-06-15

    Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

  8. Effects of nerve impulses on threshold of frog sciatic nerve fibres.

    PubMed Central

    Raymond, S A

    1979-01-01

    persists for at least as long as an absolute superexcitability (with threshold below the resting level) can be measured in the same fibre at rest. 7. The duration of the superexcitable phase interpreted as a relative change in excitability was roughly the same regardless of the level of depression. 8. The magnitude of the oscillation in threshold was give to ten times larger than the grey region (the range of stimuli for which response is probabilistic). It is concluded that at regions of low conduction safety such as axonal branches, where weak forces can influence whether an impulse will pass, such pronounced and long-lasting after-effects of firing can be expected to modulate conduction of nerve impulses. PMID:313985

  9. Predictability of threshold exceedances in dynamical systems

    NASA Astrophysics Data System (ADS)

    Bódai, Tamás

    2015-12-01

    In a low-order model of the general circulation of the atmosphere we examine the predictability of threshold exceedance events of certain observables. The likelihood of such binary events-the cornerstone also for the categoric (as opposed to probabilistic) prediction of threshold exceedances-is established from long time series of one or more observables of the same system. The prediction skill is measured by a summary index of the ROC curve that relates the hit- and false alarm rates. Our results for the examined systems suggest that exceedances of higher thresholds are more predictable; or in other words: rare large magnitude, i.e., extreme, events are more predictable than frequent typical events. We find this to hold provided that the bin size for binning time series data is optimized, but not necessarily otherwise. This can be viewed as a confirmation of a counterintuitive (and seemingly contrafactual) statement that was previously formulated for more simple autoregressive stochastic processes. However, we argue that for dynamical systems in general it may be typical only, but not universally true. We argue that when there is a sufficient amount of data depending on the precision of observation, the skill of a class of data-driven categoric predictions of threshold exceedances approximates the skill of the analogous model-driven prediction, assuming strictly no model errors. Therefore, stronger extremes in terms of higher threshold levels are more predictable both in case of data- and model-driven prediction. Furthermore, we show that a quantity commonly regarded as a measure of predictability, the finite-time maximal Lyapunov exponent, does not correspond directly to the ROC-based measure of prediction skill when they are viewed as functions of the prediction lead time and the threshold level. This points to the fact that even if the Lyapunov exponent as an intrinsic property of the system, measuring the instability of trajectories, determines predictability

  10. Energy Switching Threshold for Climatic Benefits

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Cao, L.; Caldeira, K.

    2013-12-01

    Climate change is one of the great challenges facing humanity currently and in the future. Its most severe impacts may still be avoided if efforts are made to transform current energy systems (1). A transition from the global system of high Greenhouse Gas (GHG) emission electricity generation to low GHG emission energy technologies is required to mitigate climate change (2). Natural gas is increasingly seen as a choice for transitions to renewable sources. However, recent researches in energy and climate puzzled about the climate implications of relying more energy on natural gas. On one hand, a shift to natural gas is promoted as climate mitigation because it has lower carbon per unit energy than coal (3). On the other hand, the effect of switching to natural gas on nuclear-power and other renewable energies development may offset benefits from fuel-switching (4). Cheap natural gas is causing both coal plants and nuclear plants to close in the US. The objective of this study is to measure and evaluate the threshold of energy switching for climatic benefits. We hypothesized that the threshold ratio of energy switching for climatic benefits is related to GHGs emission factors of energy technologies, but the relation is not linear. A model was developed to study the fuel switching threshold for greenhouse gas emission reduction, and transition from coal and nuclear electricity generation to natural gas electricity generation was analyzed as a case study. The results showed that: (i) the threshold ratio of multi-energy switching for climatic benefits changes with GHGs emission factors of energy technologies. (ii)The mathematical relation between the threshold ratio of energy switching and GHGs emission factors of energies is a curved surface function. (iii) The analysis of energy switching threshold for climatic benefits can be used for energy and climate policy decision support.

  11. CHATTANOOGA AIR TOXICS (CATS) MONITORING RISK ASSESSMENT

    EPA Science Inventory

    The Chattanooga-Hamilton County Air Pollution Control Bureau (CHCAPCB), the United States Environmental Protection Agency Region 4 (Region 4), and other stakeholders, in a cooperative effort, conducted an air toxics study in the Chattanooga area (city population approximately 285...

  12. Methods for threshold determination in multiplexed assays

    DOEpatents

    Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

    2014-06-24

    Methods for determination of threshold values of signatures comprised in an assay are described. Each signature enables detection of a target. The methods determine a probability density function of negative samples and a corresponding false positive rate curve. A false positive criterion is established and a threshold for that signature is determined as a point at which the false positive rate curve intersects the false positive criterion. A method for quantitative analysis and interpretation of assay results together with a method for determination of a desired limit of detection of a signature in an assay are also described.

  13. Linear pattern dynamics in nonlinear threshold systems

    SciTech Connect

    Rundle, John B.; Klein, W.; Tiampo, Kristy; Gross, Susanna

    2000-03-01

    Complex nonlinear threshold systems frequently show space-time behavior that is difficult to interpret. We describe a technique based upon a Karhunen-Loeve expansion that allows dynamical patterns to be understood as eigenstates of suitably constructed correlation operators. The evolution of space-time patterns can then be viewed in terms of a ''pattern dynamics'' that can be obtained directly from observable data. As an example, we apply our methods to a particular threshold system to forecast the evolution of patterns of observed activity. Finally, we perform statistical tests to measure the quality of the forecasts. (c) 2000 The American Physical Society.

  14. Near sputter-threshold GaSb nanopatterning

    SciTech Connect

    El-Atwani, Osman; Paul Allain, Jean; School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907; Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 ; Gonderman, Sean

    2013-09-14

    Nanopatterning at sputter-threshold energies with Ar irradiation of GaSb (100) surfaces is presented. Comparison with high-energy irradiations up to 1000 eV is conducted measuring in-situ the composition evolution over irradiation time at early stages (e.g., <10{sup 17} cm{sup −2}) and up to nanostructure saturation (e.g., ∼10{sup 18} cm{sup −2}). Low-energy irradiation is conducted for energies between 15–100 eV and a low-aspect ratio nanostructured dot formation is found. Furthermore, the role of oxide on GaSb is found to delay nanostructure formation and this is predominant at energies below 100 eV. In-situ quartz crystal microbalance measurements collect sputtered particles yielding the sputter rate at threshold energies indicating a correlation between erosion and surface composition consistent with recent theoretical models. Ion-induced segregation is also found and indicated by both compositional measurements of both the surface and the sputtered plume.

  15. Ultralow percolation threshold in aerogel and cryogel templated composites.

    PubMed

    Irin, Fahmida; Das, Sriya; Atore, Francis O; Green, Micah J

    2013-09-10

    We demonstrate a novel concept for preparing percolating composites with ultralow filler content by utilizing nanofiller-loaded aerogel and cryogels as a conductive template. This concept is investigated for several porous systems, including resorcinol-formaldehyde (RF), silica, and polyacrylamide (PAM) gels, and both graphene and carbon nanotubes are utilized as nanofiller. In each case, a stable, aqueous nanofiller dispersion is mixed with a sol-gel precursor and polymerized to form a hydrogel, which can then be converted to an aerogel by critical point drying or cryogel by freeze-drying. Epoxy resin is infused into the pores of the gels by capillary action without disrupting the monolithic structure. We show that conductive graphene/epoxy composites are formed with a very low graphene loading; a percolation threshold as low as 0.012 vol % is obtained for graphene-RF cryogel/epoxy composite. This is the lowest reported threshold of any graphene-based nanocomposites. Similar values are achieved in other aerogel and nanofiller systems, which demonstrates the versatility of this method. PMID:23927050

  16. Results of bone conduction following surgery for chronic ear disease.

    PubMed

    Vartiainen, E; Seppä, J

    1997-01-01

    Preoperative and postoperative bone conduction thresholds were compared in 181 chronic ears operated on over a 5-year period between 1990 to 1994. In the majority (92%) of cases the bone conduction thresholds remained unchanged (+/-10 dB). Nine ears (5%) showed better thresholds after surgery, with improvements ranging from 11 dB to 25 dB. This improvement was especially noted in ears with severe tympanic pathology. One ear with a large labyrinthine fistula became totally deaf after surgery. In 5 ears (3%) bone-conduction thresholds deteriorated, but remained measurable at all frequencies tested. In these latter cases this impairment ranged from 11 dB to 27 dB. Cholesteatomatous ears having intact ossicular chains were found to be at the highest risk of inner ear damage when "canal wall-down" mastoidectomies were performed. Methods for prevention of sensorineural hearing loss following chronic ear surgery are discussed. PMID:9332894

  17. Electrically Conductive Metal Nanowire Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Luo, Xiaoxiong

    This thesis investigates electrically conductive polymer nanocomposites formulated with metal nanowires for electrostatic discharge and electromagnetic interference shielding. Copper nanowires (CuNWs) of an average length of 1.98 mum and diameter of 25 +/- 4 nm were synthesized. The oxidation reaction of the CuNWs in air can be divided into two stages at weight of 111.2% on TGA curves. The isoconversional activation energies determined by Starink method were used to fit the different master plots. Johnson-Mehl-Avrami (JMA) equation gave the best fit. The surface atoms of the CuNWs are the sites for the random nucleation and the crystallite strain in the CuNWs is the driving force for the growth of nuclei mechanism during the oxidation process. To improve the anti-oxidation properties of the CuNWs, silver was coated onto the surface of the CuNWs in Ag-amine solution. The prepared silver coated CuNWs (AgCuNWs) with silver content of 66.52 wt. %, diameter of 28--33 nm exhibited improved anti-oxidation behavior. The electrical resistivity of the AgCuNW/low density polyethylene (LDPE) nanocomposites is lower than that of the CuNW/LDPE nanocomposites with the same volume percentage of fillers. The nanocomposites formulated with CuNWs and polyethylenes (PEs) were compared to study the different interaction between the CuNWs and the different types of PE matrices. The electrical conductivity of the different PE matrices filled with the same concentrations of CuNWs correlated well with the level of the CuNW dispersion. The intermolecular force and entanglement resulting from the different macromolecular structures such as molecular weight and branching played an important role in the dispersion, electrical properties and rheological behaviour of the CuNW/PE nanocomposites. Ferromagnetic polycrystalline nickel nanowires (NiNWs) were synthesized with uniform diameter of ca. 38 nm and an average length of 2.68 mum. The NiNW linear low density polyethylene (LLDPE

  18. An algorithm for automatic measurement of stimulation thresholds: clinical performance and preliminary results.

    PubMed

    Danilovic, D; Ohm, O J; Stroebel, J; Breivik, K; Hoff, P I; Markowitz, T

    1998-05-01

    We have developed an algorithmic method for automatic determination of stimulation thresholds in both cardiac chambers in patients with intact atrioventricular (AV) conduction. The algorithm utilizes ventricular sensing, may be used with any type of pacing leads, and may be downloaded via telemetry links into already implanted dual-chamber Thera pacemakers. Thresholds are determined with 0.5 V amplitude and 0.06 ms pulse-width resolution in unipolar, bipolar, or both lead configurations, with a programmable sampling interval from 2 minutes to 48 hours. Measured values are stored in the pacemaker memory for later retrieval and do not influence permanent output settings. The algorithm was intended to gather information on continuous behavior of stimulation thresholds, which is important in the formation of strategies for programming pacemaker outputs. Clinical performance of the algorithm was evaluated in eight patients who received bipolar tined steroid-eluting leads and were observed for a mean of 5.1 months. Patient safety was not compromised by the algorithm, except for the possibility of pacing during the physiologic refractory period. Methods for discrimination of incorrect data points were developed and incorrect values were discarded. Fine resolution threshold measurements collected during this study indicated that: (1) there were great differences in magnitude of threshold peaking in different patients; (2) the initial intensive threshold peaking was usually followed by another less intensive but longer-lasting wave of threshold peaking; (3) the pattern of tissue reaction in the atrium appeared different from that in the ventricle; and (4) threshold peaking in the bipolar lead configuration was greater than in the unipolar configuration. The algorithm proved to be useful in studying ambulatory thresholds. PMID:9604237

  19. Impact of Fast Sodium Channel Inactivation on Spike Threshold Dynamics and Synaptic Integration

    PubMed Central

    Platkiewicz, Jonathan; Brette, Romain

    2011-01-01

    Neurons spike when their membrane potential exceeds a threshold value. In central neurons, the spike threshold is not constant but depends on the stimulation. Thus, input-output properties of neurons depend both on the effect of presynaptic spikes on the membrane potential and on the dynamics of the spike threshold. Among the possible mechanisms that may modulate the threshold, one strong candidate is Na channel inactivation, because it specifically impacts spike initiation without affecting the membrane potential. We collected voltage-clamp data from the literature and we found, based on a theoretical criterion, that the properties of Na inactivation could indeed cause substantial threshold variability by itself. By analyzing simple neuron models with fast Na inactivation (one channel subtype), we found that the spike threshold is correlated with the mean membrane potential and negatively correlated with the preceding depolarization slope, consistent with experiments. We then analyzed the impact of threshold dynamics on synaptic integration. The difference between the postsynaptic potential (PSP) and the dynamic threshold in response to a presynaptic spike defines an effective PSP. When the neuron is sufficiently depolarized, this effective PSP is briefer than the PSP. This mechanism regulates the temporal window of synaptic integration in an adaptive way. Finally, we discuss the role of other potential mechanisms. Distal spike initiation, channel noise and Na activation dynamics cannot account for the observed negative slope-threshold relationship, while adaptive conductances (e.g. K+) and Na inactivation can. We conclude that Na inactivation is a metabolically efficient mechanism to control the temporal resolution of synaptic integration. PMID:21573200

  20. Air encapsulation during infiltration

    USGS Publications Warehouse

    Constantz, J.; Herkelrath, W.N.; Murphy, F.

    1988-01-01

    A series of field and laboratory experiments were performed to measure the effects of air encapsulation within the soil's transmission zone upon several infiltration properties. In the field, infiltration rates were measured using a double-cap infiltrometer and soil-water contents were measured using time-domain reflectometry (TDR). In the laboratory, infiltration experiments were peformed using repacked soil columns using TDR and CO 2 flooding. Results suggest that a significant portion of the total encapsulated air resided in interconnected pores within the soil's transmission zone. For the time scale considered, this residual air caused the effective hydraulic conductivity of the transmission zone to remain at a level no greater than 20% of the saturated hydraulic conductivity of the soil. -from Authors

  1. [Urban particulate air pollution: from epidemiology to health impact in public health].

    PubMed

    Filleul, L; Medina, S; Cassadou, S

    2003-10-01

    Major air pollution accidents which occurred in the 1950s led to public awareness of the health hazards involved. Since that period, levels of air pollution have decreased, but several studies conducted in North America and Europe indicate that particulate air pollution is linked to increased cardiorespiratory morbidity and mortality. Despite this evidence, several questions were raised concerning the interpretation of the results (threshold effect, harvesting effect and biological plausibility). The aim of this review is to present the link between epidemiological findings and their use in health impact assessment. We review the main causal criteria applied to epidemiology in light of scientific evidence currently available. Some causality criteria are more important than others, but they all support the causal nature of the relationship between air pollution and health, and thus justify the feasibility of health impact assessment calculations. Recent studies on relative risk assessment show that even if the risk linked to worsening air quality is low, public health consequences are high. Such information must be made accessible to policy makers and the population in general so that, together with the public health workers, they can all contribute to improving air quality and health in their communities. PMID:14657799

  2. Heat conduction in conducting polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Nath, Chandrani; Kumar, A.; Syu, K.-Z.; Kuo, Y.-K.

    2013-09-01

    Thermal conductivity and specific heat of conducting polyaniline nanofibers are measured to identify the nature of heat carrying modes combined with their inhomogeneous structure. The low temperature thermal conductivity results reveal crystalline nature while the high temperature data confirm the amorphous nature of the material suggesting heterogeneous model for conducting polyaniline. Extended acoustic phonons dominate the low temperature (<100 K) heat conduction, while localized optical phonons hopping, assisted by the extended acoustic modes, account for the high temperature (>100 K) heat conduction.

  3. Process air quality data

    NASA Technical Reports Server (NTRS)

    Butler, C. M.; Hogge, J. E.

    1978-01-01

    Air quality sampling was conducted. Data for air quality parameters, recorded on written forms, punched cards or magnetic tape, are available for 1972 through 1975. Computer software was developed to (1) calculate several daily statistical measures of location, (2) plot time histories of data or the calculated daily statistics, (3) calculate simple correlation coefficients, and (4) plot scatter diagrams. Computer software was developed for processing air quality data to include time series analysis and goodness of fit tests. Computer software was developed to (1) calculate a larger number of daily statistical measures of location, and a number of daily monthly and yearly measures of location, dispersion, skewness and kurtosis, (2) decompose the extended time series model and (3) perform some goodness of fit tests. The computer program is described, documented and illustrated by examples. Recommendations are made for continuation of the development of research on processing air quality data.

  4. On the two steps threshold selection for over-threshold modelling of extreme events

    NASA Astrophysics Data System (ADS)

    Bernardara, Pietro; Mazas, Franck; Weiss, Jerome; Andreewsky, Marc; Kergadallan, Xavier; Benoit, Michel; Hamm, Luc

    2013-04-01

    The estimation of the probability of occurrence of extreme events is traditionally achieved by fitting a probability distribution on a sample of extreme observations. In particular, the extreme value theory (EVT) states that values exceeding a given threshold converge through a Generalized Pareto Distribution (GPD) if the original sample is composed of independent and identically distributed values. However, the temporal series of sea and ocean variables usually show strong temporal autocorrelation. Traditionally, in order to select independent events for the following statistical analysis, the concept of a physical threshold is introduced: events that excess that threshold are defined as "extreme events". This is the so-called "Peak Over a Threshold (POT)" sampling, widely spread in the literature and currently used for engineering applications among many others. In the past, the threshold for the statistical sampling of extreme values asymptotically convergent toward GPD and the threshold for the physical selection of independent extreme events were confused, as the same threshold was used for both sampling data and to meet the hypothesis of extreme value convergence, leading to some incoherencies. In particular, if the two steps are performed simultaneously, the number of peaks over the threshold can increase but also decrease when the threshold decreases. This is logic in a physical point of view, since the definition of the sample of "extreme events" changes, but is not coherent with the statistical theory. We introduce a two-steps threshold selection for over-threshold modelling, aiming to discriminate (i) a physical threshold for the selection of extreme and independent events, and (ii) a statistical threshold for the optimization of the coherence with the hypothesis of the EVT. The former is a physical events identification procedure (also called "declustering") aiming at selecting independent extreme events. The latter is a purely statistical optimization

  5. Bone conduction reception: head sensitivity mapping.

    PubMed

    McBride, Maranda; Letowski, Tomasz; Tran, Phuong

    2008-05-01

    This study sought to identify skull locations that are highly sensitive to bone conduction (BC) auditory signal reception and could be used in the design of military radio communication headsets. In Experiment 1, pure tone signals were transmitted via BC to 11 skull locations of 14 volunteers seated in a quiet environment. In Experiment 2, the same signals were transmitted via BC to nine skull locations of 12 volunteers seated in an environment with 60 decibels of white background noise. Hearing threshold levels for each signal per location were measured. In the quiet condition, the condyle had the lowest mean threshold for all signals followed by the jaw angle, mastoid and vertex. In the white noise condition, the condyle also had the lowest mean threshold followed by the mastoid, vertex and temple. Overall results of both experiments were very similar and implicated the condyle as the most effective location. PMID:18432447

  6. MY 20 YEARS EXPERIENCE IN CONDUCTING ENVIRONMENTAL HEALTH STUDIES IN CHINA: (1) STUDIES ON LUNG CANCER AND INDOOR AIR POLLUTION IN YUNNAN AND (2) HEALTH EFFECTS OF ARSENIC EXPOSURE VIA DRINKING WATER IN INNER MONGOLIA

    EPA Science Inventory

    As a research health scientist at U.S. Environmental Protection Agency, I have been very fortunate to have opportunities to work as a principal investigator for two major environmental health research projects. The first study was conducted in 1983-1996 under a formal U.S.-China ...

  7. Temperature thresholds to freeze damage in cranberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sprinkler irrigation is required for frost protection of cranberry and is arguably the most important cultural practice used in production of the crop. A study was initiated in a commercial bed of ‘Stevens’ cranberry located in Langlois, OR. The objectives are to identify temperature thresholds to...

  8. Mandated Reporting Thresholds for Community Professionals

    ERIC Educational Resources Information Center

    Crowell, Kathryn; Levi, Benjamin H.

    2012-01-01

    This study examines how community-based mandated reporters understand and interpret "reasonable suspicion", the standard threshold for mandated reporting of suspected child abuse. Respondents were asked to identify the probability necessary for "suspicion of child abuse" to constitute "reasonable suspicion". Data were analyzed for internal…

  9. Speech reception thresholds in various interference conditions

    NASA Astrophysics Data System (ADS)

    Carr, Suzanne P.; Colburn, H. Steven

    2001-05-01

    Speech intelligibility is integral to human verbal communication; however, our understanding of the effects of competing noise, room reverberation, and frequency range restriction is incomplete. Using virtual stimuli, the dependence of intelligibility threshold levels on the extent of room reverberation, the relative locations of speech target and masking noise, and the available frequency content of the speech and the masking noise is explored. Speech-shaped masking noise and target sentences have three spectral conditions: wideband, high pass above 2-kHz, and low pass below 2-kHz. The 2-kHz cutoff was chosen to approximately bisect the range of frequencies most important in speech, and the high pass noise condition simulates high-frequency hearing loss. Reverberation conditions include a pseudo-anechoic case, a moderately reverberant ``classroom'' case, and a very reverberant ``bathroom'' case. Both binaural and monaural intelligibility are measured. Preliminary results show that source separation decreases thresholds, reverberation increases thresholds, and low frequency noise reverberates more in the rooms, contributing to increasing thresholds along with the effects of the upward spread of masking. The energetic effects of reverberation are explored. [Work supported by NIH DC00100.

  10. Auricular electrical stimulation and dental pain threshold.

    PubMed Central

    Simmons, M. S.; Oleson, T. D.

    1993-01-01

    A modified double-blind evaluation of naloxone reversibility of dental analgesia produced by auricular electrical stimulation (AES) was examined in 40 subjects assigned randomly to one of four groups: AES followed by saline (AS), AES followed by naloxone (AN), placebo AES followed by saline (PS), and placebo AES followed by naloxone (PN). Dental pain threshold was tested using a hand-held dental pulp tester. A second investigator administered the true or placebo AES using an electrical stimulator. A third investigator injected intravenously saline or naloxone. The subjects and investigators 1 and 3 were blind to all treatment conditions. A repeated measures analysis of variance revealed a significant difference among the four groups. The AES groups exhibited a statistically significant 18% elevation of pain threshold, whereas the two placebo stimulation groups (PS and PN) remained essentially unchanged. The mean pain threshold increased to more than 23% for group AS, but fell to less than 12% for the subjects in group AN, who were given naloxone. These findings indicate a small but significant elevation of pain threshold by AES, an effect partially blocked by naloxone, suggesting an endogenous opioid system as one mechanism for AES analgesia. Images Figure 1 Figure 2 PMID:8185085

  11. Gastric Residual Volume: Rethinking the Threshold.

    PubMed

    Emami Zeydi, Amir; Sharafkhani, Mohammad; Armat, Mohammad Reza

    2016-01-01

    There are many challenges related to enteral feedings of the mechanically ventilated patient. Among the most often debated issues is the threshold for gastric residual volume before further feeding. This brief article considers the factors to be considered and reviews current thinking on the topic. PMID:27575801

  12. 40 CFR 98.121 - Reporting threshold.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Fluorinated Gas Production § 98.121 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a fluorinated gas production process that... in § 98.2(a)(2), calculate process emissions from fluorinated gas production using uncontrolled...

  13. 40 CFR 98.121 - Reporting threshold.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Fluorinated Gas Production § 98.121 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a fluorinated gas production process that... in § 98.2(a)(2), calculate process emissions from fluorinated gas production using uncontrolled...

  14. 40 CFR 98.121 - Reporting threshold.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Fluorinated Gas Production § 98.121 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a fluorinated gas production process that... in § 98.2(a)(2), calculate process emissions from fluorinated gas production using uncontrolled...

  15. 40 CFR 98.121 - Reporting threshold.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) MANDATORY GREENHOUSE GAS REPORTING Fluorinated Gas Production § 98.121 Reporting threshold. You must report GHG emissions under this subpart if your facility contains a fluorinated gas production process that... in § 98.2(a)(2), calculate process emissions from fluorinated gas production using uncontrolled...

  16. The gradual nature of threshold switching

    NASA Astrophysics Data System (ADS)

    Wimmer, M.; Salinga, M.

    2014-11-01

    The recent commercialization of electronic memories based on phase change materials proved the usability of this peculiar family of materials for application purposes. More advanced data storage and computing concepts, however, demand a deeper understanding especially of the electrical properties of the amorphous phase and the switching behaviour. In this work, we investigate the temporal evolution of the current through the amorphous state of the prototypical phase change material, Ge2Sb2Te5, under constant voltage. A custom-made electrical tester allows the measurement of delay times over five orders of magnitude, as well as the transient states of electrical excitation prior to the actual threshold switching. We recognize a continuous current increase over time prior to the actual threshold-switching event to be a good measure for the electrical excitation. A clear correlation between a significant rise in pre-switching-current and the later occurrence of threshold switching can be observed. This way, we found experimental evidence for the existence of an absolute minimum for the threshold voltage (or electric field respectively) holding also for time scales far beyond the measurement range.

  17. Environment as a Threshold Variable: An Examination

    ERIC Educational Resources Information Center

    Marjoribanks, Kevin

    1974-01-01

    It is often assumed that, for intellectual performance, the environment acts as a threshold variable. This assumption was investigated by examining the nature of the relationship between the learning environment of the home and verbal, number, spatial, and reasoning ability test scores. (Author/JA)

  18. Threshold Concepts in Finance: Conceptualizing the Curriculum

    ERIC Educational Resources Information Center

    Hoadley, Susan; Tickle, Leonie; Wood, Leigh N.; Kyng, Tim

    2015-01-01

    Graduates with well-developed capabilities in finance are invaluable to our society and in increasing demand. Universities face the challenge of designing finance programmes to develop these capabilities and the essential knowledge that underpins them. Our research responds to this challenge by identifying threshold concepts that are central to…

  19. Human eye color difference threshold measurement system

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Zhou, Taogeng

    2013-12-01

    The human eye has the ability to distinguish millions of colors, with this feature we can identify very subtle color differences, and the measurement of human eye color difference threshold can provide a visual function diagnosis for testee. In recent years, people begin to focus on studies on visual threshold diagnostic equipment. This paper proposes a human eye color difference threshold measurement system which is based on dual integrating sphere. The system includes two pairs of dual integrating sphere and color control module. Dual integrating sphere uses to mix and produce color, and palette unit which produces primary colors (red (R), green (G), blue (B)) is embedded in dual integrating sphere. At the same time, the embedded palette unit which produces cyan (C), magenta (M), and yellow (Y) expands color area that the system can generate. One optical path based on dual integrating sphere generates standard color, the other path produces the matching color which is similar to a standard color. In the high-precision closed-loop color control module, photoelectric switch records stepper motor's origin position and limits move displacement. Precision stepper motor pushes the light-blocking panel of the palette unit to a predetermined position, while real-time monitoring the position of the light-blocking panel and mixing the ideal controllable color. Two colors that the system generates are projected onto the same target area. Subjects make a judgment on color difference threshold by observing the target eventually.

  20. Identification of Threshold Concepts for Biochemistry

    ERIC Educational Resources Information Center

    Loertscher, Jennifer; Green, David; Lewis, Jennifer E.; Lin, Sara; Minderhout, Vicky

    2014-01-01

    Threshold concepts (TCs) are concepts that, when mastered, represent a transformed understanding of a discipline without which the learner cannot progress. We have undertaken a process involving more than 75 faculty members and 50 undergraduate students to identify a working list of TCs for biochemistry. The process of identifying TCs for…