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Sample records for twa-tlv threshold limit

  1. Approach to DOE threshold guidance limits

    International Nuclear Information System (INIS)

    Shuman, R.D.; Wickham, L.E.

    1984-01-01

    The need for less restrictive criteria governing disposal of extremely low-level radioactive waste has long been recognized. The Low-Level Waste Management Program has been directed by the Department of Energy (DOE) to aid in the development of a threshold guidance limit for DOE low-level waste facilities. Project objectives are concernd with the definition of a threshold limit dose and pathway analysis of radionuclide transport within selected exposure scenarios at DOE sites. Results of the pathway analysis will be used to determine waste radionuclide concentration guidelines that meet the defined threshold limit dose. Methods of measurement and verification of concentration limits round out the project's goals. Work on defining a threshold limit dose is nearing completion. Pathway analysis of sanitary landfill operations at the Savannah River Plant and the Idaho National Engineering Laboratory is in progress using the DOSTOMAN computer code. Concentration limit calculations and determination of implementation procedures shall follow completion of the pathways work. 4 references

  2. Summary of DOE threshold limits efforts

    International Nuclear Information System (INIS)

    Wickham, L.E.; Smith, C.F.; Cohen, J.J.

    1987-01-01

    The Department of Energy (DOE) has been developing the concept of threshold quantities for use in determining which waste materials may be disposed of as nonradioactive waste in DOE sanitary landfills. Waste above a threshold level could be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. After extensive review of a draft threshold guidance document in 1985, a second draft threshold background document was produced in March 1986. The second draft included a preliminary cost-benefit analysis and quality assurance considerations. The review of the second draft has been completed. Final changes to be incorporated include an in-depth cost-benefit analysis of two example sites and recommendations of how to further pursue (i.e. employ) the concept of threshold quantities within the DOE. 3 references

  3. Thermal Limits and Thresholds of Red Sea Biota

    KAUST Repository

    Chaidez, Veronica

    2018-01-01

    tropical systems. This has major consequences for organisms that may already find themselves at their thermal limits. The aim of this project was to define the thermal limits and thresholds of certain Red Sea species. Firstly, to better understand

  4. A non-parametric framework for estimating threshold limit values

    Directory of Open Access Journals (Sweden)

    Ulm Kurt

    2005-11-01

    Full Text Available Abstract Background To estimate a threshold limit value for a compound known to have harmful health effects, an 'elbow' threshold model is usually applied. We are interested on non-parametric flexible alternatives. Methods We describe how a step function model fitted by isotonic regression can be used to estimate threshold limit values. This method returns a set of candidate locations, and we discuss two algorithms to select the threshold among them: the reduced isotonic regression and an algorithm considering the closed family of hypotheses. We assess the performance of these two alternative approaches under different scenarios in a simulation study. We illustrate the framework by analysing the data from a study conducted by the German Research Foundation aiming to set a threshold limit value in the exposure to total dust at workplace, as a causal agent for developing chronic bronchitis. Results In the paper we demonstrate the use and the properties of the proposed methodology along with the results from an application. The method appears to detect the threshold with satisfactory success. However, its performance can be compromised by the low power to reject the constant risk assumption when the true dose-response relationship is weak. Conclusion The estimation of thresholds based on isotonic framework is conceptually simple and sufficiently powerful. Given that in threshold value estimation context there is not a gold standard method, the proposed model provides a useful non-parametric alternative to the standard approaches and can corroborate or challenge their findings.

  5. Dynamic-Threshold-Limited Timed-Token (DTLTT) Protocol | Kalu ...

    African Journals Online (AJOL)

    An improved version of the Static-Threshold-Limited On-Demand Guaranteed Service Timed-Token (STOGSTT) Media Access Control (MAC) protocol for channel capacity allocation to the asynchronous trac in Multiservice Local Area Network (MLANs) was developed and analyzed. TLODGSTT protocol uses static value of ...

  6. Thresholds and noise limitations of colour vision in dim light.

    Science.gov (United States)

    Kelber, Almut; Yovanovich, Carola; Olsson, Peter

    2017-04-05

    Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod-cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones.This article is part of the themed issue 'Vision in dim light'. © 2017 The Author(s).

  7. Thermal Limits and Thresholds of Red Sea Biota

    KAUST Repository

    Chaidez, Veronica

    2018-05-01

    As ocean temperatures continue to rise, the effect of temperature on marine organisms becomes highly relevant. The Red Sea is the warmest sea and is rapidly warming with current surface temperatures (28 – 34 °C) already exceeding those of most tropical systems. This has major consequences for organisms that may already find themselves at their thermal limits. The aim of this project was to define the thermal limits and thresholds of certain Red Sea species. Firstly, to better understand the thermal regimes of the Red Sea, we looked at decadal trends in maximum sea surface temperature across the basin. Then, we tested the thermal capacities of Red Sea mangroves and zooplankton, two key ecological groups, by performing thermal stress experiments in the laboratory. We found that the Red Sea basin is warming faster than the global average (0.17 °C decade-1), the thermal limit of mangrove propagules is between 33 and 35 °C, and the limits among the most common zooplankton groups range from 30 to 36 °C. This project gives us a better understanding of how organisms respond to extreme temperatures and how they may be affected in a future, warmer, ocean.

  8. Perspectives on what we formerly called threshold limit values

    International Nuclear Information System (INIS)

    Goldsmith, J.R.

    1991-01-01

    From the point of view of an epidemiologist with experience in community air quality standards, occupational health standards, radiation standards, and water quality standards, reasons are given for discarding the assumption that occupational health protection should be based on threshold concepts. The weakness of worker health protection based on prescription of maximal exposure levels is noted, regardless of whose judgement is used for such levels. 37 references

  9. Threshold effect under nonlinear limitation of the intensity of high-power light

    International Nuclear Information System (INIS)

    Tereshchenko, S A; Podgaetskii, V M; Gerasimenko, A Yu; Savel'ev, M S

    2015-01-01

    A model is proposed to describe the properties of limiters of high-power laser radiation, which takes into account the threshold character of nonlinear interaction of radiation with the working medium of the limiter. The generally accepted non-threshold model is a particular case of the threshold model if the threshold radiation intensity is zero. Experimental z-scan data are used to determine the nonlinear optical characteristics of media with carbon nanotubes, polymethine and pyran dyes, zinc selenide, porphyrin-graphene and fullerene-graphene. A threshold effect of nonlinear interaction between laser radiation and some of investigated working media of limiters is revealed. It is shown that the threshold model more adequately describes experimental z-scan data. (nonlinear optical phenomena)

  10. Threshold limit values, permissible exposure limits, and feasibility: The bases for exposure limits in the United States

    International Nuclear Information System (INIS)

    Rappaport, S.M.

    1993-01-01

    The development of exposure limits in the United States has always relied heavily upon the threshold limit values (TLVs) developed by the American Conference of Governmental Industrial Hygienists (ACGIH). In fact, the TLVs were adopted as official exposure limits by the Occupational Safety and Health Administration (OSHA) in 1972 and 1989. Given the continuing importance of the ACGIH limits, this paper compares the basis of the TLVs with that employed by OSHA de novo in its 12 new permissible exposure limits (PELs). Using benzene as an example, it is shown that OSHA's new PELs have been established following a rigorous assessment of the inherent risks and the feasibility of instituting the limit. The TLVs, on the other hand, have been developed by ad hoc procedures and appear to have traditionally reflected levels thought to be achievable at the time. However, this might be changing. Analysis of the historical reductions of TLVs, for 27 substances on the 1991-1992 list of intended changes, indicates smaller reductions in the past (median reduction of 2.0-2.5-fold between 1946 and 1988) compared to those currently being observed (median reduction of 7.5-fold between 1989 and 1991). Further analysis suggests a more aggressive policy of the ACGIH regarding TLVs for carcinogens but not for substances that produce effects other than cancer. Regardless of whether the basis of the TLVs has changed recently, it would take a relatively long time for the impact of any change to be felt, since the median age of the 1991-1992 TLVs is 16.5 years, and 75% of these limits are more than 10 years old. The implications of OSHA's continued reliance on the TLVs as a means of updating its PELs are discussed, and four alternatives are presented to the ACGIH regarding the future of its activities related to exposure limits. It is concluded that new mechanisms are needed for OSHA to update its PELs in a timely fashion so that the TLVs will not be adopted by default in the future

  11. Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn

    International Nuclear Information System (INIS)

    Gineys, N.; Aouad, G.; Sorrentino, F.; Damidot, D.

    2011-01-01

    This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C 3 S, C 2 S, C 3 A and C 4 AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C 3 S, 18% C 2 S, 8% C 3 A and 8% C 4 AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO 2 ) and Sn reacted with lime to form a calcium stannate (Ca 2 SnO 4 ). Cu changed the crystallisation process and affected therefore the formation of C 3 S. Indeed a high content of Cu in clinker led to the decomposition of C 3 S into C 2 S and of free lime. Zn, in turn, affected the formation of C 3 A. Ca 6 Zn 3 Al 4 O 15 was formed whilst a tremendous reduction of C 3 A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

  12. Using self-organizing maps to determine observation threshold limit predictions in highly variant data

    Science.gov (United States)

    Paganoni, C.A.; Chang, K.C.; Robblee, M.B.

    2006-01-01

    A significant data quality challenge for highly variant systems surrounds the limited ability to quantify operationally reasonable limits on the data elements being collected and provide reasonable threshold predictions. In many instances, the number of influences that drive a resulting value or operational range is too large to enable physical sampling for each influencer, or is too complicated to accurately model in an explicit simulation. An alternative method to determine reasonable observation thresholds is to employ an automation algorithm that would emulate a human analyst visually inspecting data for limits. Using the visualization technique of self-organizing maps (SOM) on data having poorly understood relationships, a methodology for determining threshold limits was developed. To illustrate this approach, analysis of environmental influences that drive the abundance of a target indicator species (the pink shrimp, Farfantepenaeus duorarum) provided a real example of applicability. The relationship between salinity and temperature and abundance of F. duorarum is well documented, but the effect of changes in water quality upstream on pink shrimp abundance is not well understood. The highly variant nature surrounding catch of a specific number of organisms in the wild, and the data available from up-stream hydrology measures for salinity and temperature, made this an ideal candidate for the approach to provide a determination about the influence of changes in hydrology on populations of organisms.

  13. You Spin my Head Right Round: Threshold of Limited Immersion for Rotation Gains in Redirected Walking.

    Science.gov (United States)

    Schmitz, Patric; Hildebrandt, Julian; Valdez, Andre Calero; Kobbelt, Leif; Ziefle, Martina

    2018-04-01

    In virtual environments, the space that can be explored by real walking is limited by the size of the tracked area. To enable unimpeded walking through large virtual spaces in small real-world surroundings, redirection techniques are used. These unnoticeably manipulate the user's virtual walking trajectory. It is important to know how strongly such techniques can be applied without the user noticing the manipulation-or getting cybersick. Previously, this was estimated by measuring a detection threshold (DT) in highly-controlled psychophysical studies, which experimentally isolate the effect but do not aim for perceived immersion in the context of VR applications. While these studies suggest that only relatively low degrees of manipulation are tolerable, we claim that, besides establishing detection thresholds, it is important to know when the user's immersion breaks. We hypothesize that the degree of unnoticed manipulation is significantly different from the detection threshold when the user is immersed in a task. We conducted three studies: a) to devise an experimental paradigm to measure the threshold of limited immersion (TLI), b) to measure the TLI for slowly decreasing and increasing rotation gains, and c) to establish a baseline of cybersickness for our experimental setup. For rotation gains greater than 1.0, we found that immersion breaks quite late after the gain is detectable. However, for gains lesser than 1.0, some users reported a break of immersion even before established detection thresholds were reached. Apparently, the developed metric measures an additional quality of user experience. This article contributes to the development of effective spatial compression methods by utilizing the break of immersion as a benchmark for redirection techniques.

  14. The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA.

    Science.gov (United States)

    Sayapathi, Balachandar S; Su, Anselm Ting; Koh, David

    2014-10-01

    Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at 'deteriorated' level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz

  15. Setting limits: Using air pollution thresholds to protect and restore US ecosystems

    Science.gov (United States)

    Fenn, Mark E.; Lambert, Kathleen F.; Blett, Tamara F.; Burns, Douglas A.; Pardo, Linda H.; Lovett, Gary M.; Haeuber, Richard A.; Evers, David C.; Driscoll, Charles T.; Jeffries, Dean S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage.

  16. Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems

    Science.gov (United States)

    Fenn, M.E.; Lambert, K.F.; Blett, T.F.; Burns, Douglas A.; Pardo, L.H.; Lovett, Gary M.; Haeuber, R. A.; Evers, D.C.; Driscoll, C.T.; Jeffries, D.S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage. Based on the results of a comprehensive review of air pollution thresholds, we conclude: ??? Ecosystem services such as air and water purification, decomposition and detoxification of waste materials, climate regulation, regeneration of soil fertility, production and biodiversity maintenance, as well as crop, timber and fish supplies are impacted by deposition of nitrogen, sulfur, mercury and other pollutants. The consequences of these changes may be difficult or impossible to reverse as impacts cascade throughout affected ecosystems. ??? The effects of too much nitrogen are common across the U.S. and include altered plant and lichen communities, enhanced growth of invasive species, eutrophication and acidification of lands and waters, and habitat deterioration for native species, including endangered species. ??? Lake, stream and soil acidification is widespread across the eastern United States. Up to 65% of lakes within sensitive areas receive acid deposition that exceeds critical loads. ??? Mercury contamination adversely affects fish in many inland and coastal waters. Fish consumption advisories for mercury exist in all 50

  17. Bayesian-statistical decision threshold, detection limit, and confidence interval in nuclear radiation measurement

    International Nuclear Information System (INIS)

    Weise, K.

    1998-01-01

    When a contribution of a particular nuclear radiation is to be detected, for instance, a spectral line of interest for some purpose of radiation protection, and quantities and their uncertainties must be taken into account which, such as influence quantities, cannot be determined by repeated measurements or by counting nuclear radiation events, then conventional statistics of event frequencies is not sufficient for defining the decision threshold, the detection limit, and the limits of a confidence interval. These characteristic limits are therefore redefined on the basis of Bayesian statistics for a wider applicability and in such a way that the usual practice remains as far as possible unaffected. The principle of maximum entropy is applied to establish probability distributions from available information. Quantiles of these distributions are used for defining the characteristic limits. But such a distribution must not be interpreted as a distribution of event frequencies such as the Poisson distribution. It rather expresses the actual state of incomplete knowledge of a physical quantity. The different definitions and interpretations and their quantitative consequences are presented and discussed with two examples. The new approach provides a theoretical basis for the DIN 25482-10 standard presently in preparation for general applications of the characteristic limits. (orig.) [de

  18. Physiological limitation at alpine treeline: relationships of threshold responses of conifers to their establishment patterns

    Science.gov (United States)

    Germino, M. J.; Lazarus, B.; Castanha, C.; Moyes, A. B.; Kueppers, L. M.

    2014-12-01

    An understanding of physiological limitations to tree establishment at alpine treeline form the basis for predicting how this climate-driven boundary will respond to climate shifts. Most research on this topic has focused on limitations related to carbon balance and growth of trees. Carbon balance could limit survival and establishment primarily through slow-acting, chronic means. We asked whether tree survival and thus establishment patterns reflect control by chronic effects in comparison to acute, threshold responses, such as survival of frost events. Seedling survivorship patterns were compared to thresholds in freezing (temperature causing leaf freezing, or freezing point, FP; and physiological response to freezing) and water status (turgor loss point, TLP; and related physiological adjustments). Subject seedlings were from forest, treeline, and alpine sites in the Alpine Treeline Warming Experiment in Colorado, and included limber and lodgepole pine (a low-elevation species), and Engelmann Spruce. Preliminary results show survival increases with seedling age, but the only corresponding increase in stress acclimation was photosynthetic resistance to freezing and TLP, not FP. Differences in survivorship among the species were not consistent with variation in FP but they generally agreed with variation in photosynthetic resistance to deep freezing and to early-season drought avoidance. Mortality of limber pine increased 35% when minimum temperatures decreased below -9C, which compares with FPs of >-8.6C, and about 1/3 of its mortality occurred during cold/wet events, particularly in the alpine. The other major correlate of mortality is midsummer drying events, as previously reported. Also in limber pine, the TLP for year-old seedlings (-2.5 MPa) corresponded with seasonal-drought mortality. In summary, we show several examples of correspondence in physiological thresholds to mortality events within a species, although the relationships are not strong. Across

  19. ZnO-PVA nanocomposite films for low threshold optical limiting applications

    International Nuclear Information System (INIS)

    Viswanath, Varsha; Beenakumari, C.; Muneera, C. I.

    2014-01-01

    Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages ( −3 M to 7×10 −3 M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayed by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ (3) |, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices

  20. The Impact of Heterogeneity on Threshold-Limited Social Contagion, and on Crowd Decision-Making

    Science.gov (United States)

    Karampourniotis, Panagiotis Dimitrios

    Recent global events and their poor predictability are often attributed to the complexity of the world event dynamics. A key factor generating the turbulence is human diversity. Here, we study the impact of heterogeneity of individuals on opinion formation and emergence of global biases. In the case of opinion formation, we focus on the heterogeneity of individuals' susceptibility to new ideas. In the case of global biases, we focus on the aggregated heterogeneity of individuals in a country. First, to capture the complex nature of social influencing we use a simple but classic model of contagion spreading in complex social systems, namely the threshold model. We investigate numerically and analytically the transition in the behavior of threshold-limited cascades in the presence of multiple initiators as the distribution of thresholds is varied between the two extreme cases of identical thresholds and a uniform distribution. We show that individuals' heterogeneity of susceptibility governs the dynamics, resulting in different sizes of initiators needed for consensus. Furthermore, given the impact of heterogeneity on the cascade dynamics, we investigate selection strategies for accelerating consensus. To this end, we introduce two new selection strategies for Influence Maximization. One of them focuses on finding the balance between targeting nodes which have high resistance to adoptions versus nodes positioned in central spots in networks. The second strategy focuses on the combination of nodes for reaching consensus, by targeting nodes which increase the group's influence. Our strategies outperform other existing strategies regardless of the susceptibility diversity and network degree assortativity. Finally, we study the aggregated biases of humans in a global setting. The emergence of technology and globalization gives raise to the debate on whether the world moves towards becoming flat, a world where preferential attachment does not govern economic growth. By

  1. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    Science.gov (United States)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  2. 30 CFR 71.700 - Inhalation hazards; threshold limit values for gases, dust, fumes, mists, and vapors.

    Science.gov (United States)

    2010-07-01

    ... gases, dust, fumes, mists, and vapors. 71.700 Section 71.700 Mineral Resources MINE SAFETY AND HEALTH... limit values for gases, dust, fumes, mists, and vapors. (a) No operator of an underground coal mine and... limit values adopted by the American Conference of Governmental Industrial Hygienists in “Threshold...

  3. Extracting dynamics from threshold-crossing interspike intervals: Possibilities and limitations

    DEFF Research Database (Denmark)

    Pavlov, A. N.; Sosnovtseva, O. V.; Mosekilde, Erik

    2000-01-01

    In this paper we estimate dynamical characteristics of chaotic attractors from sequences of threshold-crossing interspike intervals, and study how the choice of the threshold level (which sets the equation of a secant plane) influences the results of the numerical computations. Under quite genera...

  4. Application of habitat thresholds in conservation: Considerations, limitations, and future directions

    Directory of Open Access Journals (Sweden)

    Yntze van der Hoek

    2015-01-01

    Full Text Available Habitat thresholds are often interpreted as the minimum required area of habitat, and subsequently promoted as conservation targets in natural resource policies and planning. Unfortunately, several recent reviews and messages of caution on the application of habitat thresholds in conservation have largely fallen on deaf ears, leading to a dangerous oversimplification and generalization of the concept. We highlight the prevalence of oversimplification/over-generalization of results from habitat threshold studies in policy documentation, the consequences of such over-generalization, and directions for habitat threshold studies that have conservation applications without risking overgeneralization. We argue that in order to steer away from misapplication of habitat thresholds in conservation, we should not focus on generalized nominal habitat values (i.e., amounts or percentages of habitat, but on the use of habitat threshold modeling for comparative exercises of area-sensitivity or the identification of environmental dangers. In addition, we should remain focused on understanding the processes and mechanisms underlying species responses to habitat change. Finally, studies could that focus on deriving nominal value threshold amounts should do so only if the thresholds are detailed, species-specific, and translated to conservation targets particular to the study area only.

  5. Extracting dynamics from threshold-crossing interspike intervals: possibilities and limitations

    DEFF Research Database (Denmark)

    Pavlov, A N; Sosnovtseva, Olga; Mosekilde, Erik

    2000-01-01

    In this paper we estimate dynamical characteristics of chaotic attractors from sequences of threshold-crossing interspike intervals, and study how the choice of the threshold level (which sets the equation of a secant plane) influences the results of the numerical computations. Under quite genera...

  6. Threshold-dependent climate effects and high mortality limit recruitment and recovery of the Kattegat cod

    DEFF Research Database (Denmark)

    Lindegren, Martin; Eero, Margit

    2013-01-01

    Cod in the Kattegat is one of the most dramatic examples of stock collapse, where despite large management efforts, almost no signs of recovery have been observed. We investigate how multiple physical and biological factors could potentially influence recruitment and recovery of Kattegat cod, using...... non-additive threshold models. In contrast to previous studies on recruitment dynamics of Kattegat cod Gadus morhua, we found that recruitment variability may be explained by a combination of the size of the spawning stock and external conditions (i.e. sea surface temperature and oxygen concentrations...

  7. The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA

    OpenAIRE

    Sayapathi, Balachandar S; Su, Anselm Ting; Koh, David

    2014-01-01

    Background: Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institut...

  8. 77 FR 9925 - Price Index Adjustments for Expenditure Limitations and Lobbyist Bundling Disclosure Threshold

    Science.gov (United States)

    2012-02-21

    ... FEDERAL ELECTION COMMISSION [Notice 2012-02] Price Index Adjustments for Expenditure Limitations...)(A)) are adjusted periodically to reflect changes in the consumer price index. See 2 U.S.C. 434(i)(3... difference between the price index, as certified to the Commission by the Secretary of Labor, for the 12...

  9. 75 FR 8353 - Price Index Adjustments for Expenditure Limitations and Lobbyist Bundling Disclosure Threshold

    Science.gov (United States)

    2010-02-24

    ... FEDERAL ELECTION COMMISSION [Notice 2010-02] Price Index Adjustments for Expenditure Limitations... price index. See 2 U.S.C. 434(i)(3) and 441a(c)(1), and 11 CFR 109.32 and 110.17(a), (f). The Commission... is increased by 4.35110, which reflects the difference between the price index, as certified to the...

  10. Sooting limit in counterflow diffusion flames of ethylene/propane fuels and implication to threshold soot index

    KAUST Repository

    Joo, Peter H.

    2013-01-01

    Sooting limits in counterflow diffusion flames of propane/ethylene fuels have been studied experimentally using a light scattering technique, including the effects of dilution, fuel mixing, and strain rate. The results are discussed in view of the threshold soot index (TSI). In soot-formation (SF) flames, where the flame is located on the oxidizer side of the stagnation plane, the sooting limit depends critically on fuel type and subsequently on flame temperature. The sooting limit has a non-linear dependence on the fuel-mixing ratio, which is similar to the non-linear mixing rule for TSI observed experimentally in rich premixed flames, where soot oxidation is absent for both SF and rich premixed flames. In soot-formation-oxidation (SFO) flames, where the flame is located on the fuel side, the sooting limit depends critically on flame temperature, while it is relatively independent on fuel type. This result suggests a linear mixing rule for sooting limits in SFO flames, which is similar to the TSI behavior for coflow diffusion flames. Soot oxidation takes place for both types of flames. The aerodynamic strain effect on the sooting limits has also been studied and an appreciable influence has been observed. Under sooting conditions, soot volume fraction was measured using a light extinction technique. The soot loadings in SF flames of the mixture fuels demonstrated a synergistic effect, i.e., soot production increased for certain mixture fuels as compared to the respective singlecomponent fuels. © 2012 The Combustion Institute.

  11. Decision Threshold and Detection Limit in Spectrometric Measurements. Part 1: Application to Gamma Spectrometry

    International Nuclear Information System (INIS)

    Perez, C.; Gasco, C.; Lopez, M. A.

    2010-01-01

    This report summarised the author's lecture of the advanced gamma spectrometry course organised by CIEMAT. The characteristic limits determination in gamma spectrometry generally is obtained through the programming that the trade marks offers to the client with the objective of the automatic calculation of the activity concentrations existing in a sample. In this report, the examples shown in the ISO 11929 standard are compared to the programming realised by Genie 2k for determining characteristic limits. The main difference of both is located in the uncertainty calculations due to the efficiency calibration that is considered by ISO and not by Genie 2K. Through implementation in the software developed by trade marks will be possible to introduce this uncertainty and to assimilate to the calculation done by ISO 11929. In the second part of this report will be analyzed the more complicated samples of this application as counting in a whole body counter (following ISO-28218 about Performance Criteria for radio bioassay), multiplet, overlapping, addition of several peaks for obtaining the activity concentration, etc. (Author) 19 refs.

  12. Determination of carcinogenic threshold limit values using the tumorigenic dose rate 50% (TD50)

    International Nuclear Information System (INIS)

    Bonvalot, Y.; Oudiz, A.; Hubert, P.; Abenhaim, L.

    1989-01-01

    The objective of the present study is to propose a simple procedure for the determination of Occupational Limit Values (OLVs) based on the TD 50 concept (Tumorigenic Dose Rate 50%). The TD 50 concept was introduced by Peto R. and al. to help classify chemical substances according to their carcinogenic potency. The TD 50 is that dose rate (in mg/KXg body weight/day) which, if administered chronically for the standard lifespan of the species will halve the probability of remaining tumorless throughout that period. Using TD 50 values available for 776 substances, the procedure presented here allows one to determine OLVs corresponding to a fixed excess risk. It is based on a mathematical high-to-low doses extrapolation of the TD 50 . OLVs obtained with this procedure are compared with currently available TLVs and other occupational guidelines. (author)

  13. Early Liver and Kidney Dysfunction Associated with Occupational Exposure to Sub-Threshold Limit Value Levels of Benzene, Toluene, and Xylenes in Unleaded Petrol

    Directory of Open Access Journals (Sweden)

    Masoud Neghab

    2015-12-01

    Conclusion: The average exposure of petrol station workers to BTX did not exceed the current threshold limit values (TLVs for these chemicals. However, evidence of subtle, subclinical and prepathologic early liver and kidney dysfunction was evident in exposed individuals.

  14. Tropical Andean ecosystems and the need to keep warming limits below a +1.5°C threshold

    Science.gov (United States)

    Ruiz-Carrascal, D.; Herzog, S. K.; Guitierrez Lagoueyte, M. E.; Gonzalez-Duque, D.; Cuevas-Moreno, J.; del Valle, J. I.; Andreu-Hayles, L.; Herrera, D. A.; Martínez, R.

    2017-12-01

    Long-term climate change and rapid land-use change are synergistically threatening the integrity and functioning of tropical Andean ecosystems. The main goal of our research was to integrate climate change projections, biodiversity data and anthropogenically driven ecosystem disruption assessments to quantify the vulnerability of Andean ecosystems and species to global change at a local scale. We merged discernible trends in local quality-controlled weather station data with reanalysis data, as well as with historical and prospective simulation outputs of five well-known GCMs to assess a long-term context for the analysis of climate change exposure (temperature severity intervals). Individual, medium-term, multi-member GCM simulations included: altitude-corrected 2046-2065 (IPCC-AR4) climate change scenarios for the A1B emission scenario; and spatially-downscaled 2040-2069 (IPCC-AR5) projections for the RCP4.5. Previous studies reported mean annual temperature anomaly intervals that resulted in exceedingly high thresholds: the lowest severity interval ( +2.71°C). The least severe interval extended up to the threshold widely recognized as `dangerous' climate change, thereby leading to an underestimation of the true vulnerability of Andean species. Our analyses suggest that temperature anomalies for the full extent of the tropical Andes will likely range from low ( +2.61°C), exceeding the threshold of 'natural' climate variability (+1.78°C). Our results suggest that most species that were used as proxies of ecosystem vulnerabilities will likely experience overall low-to-medium-to-high temperature increases. Since many of them have potentially high sensitivity to such long-term changes, Andean species will likely experience greatly increases in vulnerability. The already-disrupted Andean ecosystems will suffer a further climatic stress, which will worsen the well-known detrimental synergies between climate and land-use changes. There is an imperative need to

  15. Limit of detection and threshold for positivity of the Centers for Disease Control and Prevention assay for factor VIII inhibitors.

    Science.gov (United States)

    Miller, C H; Boylan, B; Shapiro, A D; Lentz, S R; Wicklund, B M

    2017-10-01

    Essentials Immunologic methods detect factor VIII (FVIII) antibodies in some inhibitor-negative specimens. Specimens were tested by modified Nijmegen-Bethesda assay (NBA) and fluorescence immunoassay. The NBA with preanalytical heat inactivation detects FVIII inhibitors down to 0.2 NBU. IgG 4 frequency validates the established threshold for positivity of ≥ 0.5 NBU for this NBA. Background The Bethesda assay for measurement of factor VIII inhibitors called for quantification of positive inhibitors by using dilutions producing 25-75% residual activity (RA), corresponding to 0.4-2.0 Bethesda units, with the use of 'more sensitive methods' for samples with RA closer to 100% being recommended. The Nijmegen modification (Nijmegen-Bethesda assay [NBA]) changed the reagents used but not these calculations. Some specimens negative by the NBA have been shown to have FVIII antibodies detectable with sensitive immunologic methods. Objective To examine the performance at very low inhibitor titers of the Centers for Disease Control and Prevention (CDC)-modified NBA (CDC-NBA), which includes preanalytic heat inactivation to liberate bound anti-FVIII antibodies. Methods Specimens with known inhibitors were tested with the CDC-NBA. IgG 4 anti-FVIII antibodies were measured by fluorescence immunoassay (FLI). Results Diluted inhibitors showed linearity below 0.4 Nijmegen-Bethesda units (NBU). With four statistical methods, the limit of detection of the CDC-NBA was determined to be 0.2 NBU. IgG 4 anti-FVIII antibodies, which correlate most strongly with functional inhibitors, were present at rates above the background rate of healthy controls in specimens with titers ≥ 0.2 NBU and showed an increase in frequency from 14.3% at 0.4 NBU to 67% at the established threshold for positivity of 0.5 NBU. Conclusions The CDC-NBA can detect inhibitors down to 0.2 NBU. The FLI, which is more sensitive, demonstrates anti-FVIII IgG 4 in some patients with negative (NBA, supporting the need for

  16. Perspectives on the relevance of the circadian time structure to workplace threshold limit values and employee biological monitoring.

    Science.gov (United States)

    Smolensky, Michael H; Reinberg, Alain E; Sackett-Lundeen, Linda

    2017-01-01

    The circadian time structure (CTS) and its disruption by rotating and nightshift schedules relative to work performance, accident risk, and health/wellbeing have long been areas of occupational medicine research. Yet, there has been little exploration of the relevance of the CTS to setting short-term, time-weighted, and ceiling threshold limit values (TLVs); conducting employee biological monitoring (BM); and establishing normative reference biological exposure indices (BEIs). Numerous publications during the past six decades document the CTS substantially affects the disposition - absorption, distribution, metabolism, and elimination - and effects of medications. Additionally, laboratory animal and human studies verify the tolerance to chemical, biological (contagious), and physical agents can differ extensively according to the circadian time of exposure. Because of slow and usually incomplete CTS adjustment by rotating and permanent nightshift workers, occupational chemical and other contaminant encounters occur during a different circadian stage than for dayshift workers. Thus, the intended protection of some TLVs when working the nightshift compared to dayshift might be insufficient, especially in high-risk settings. The CTS is germane to employee BM in that large-amplitude predictable-in-time 24h variation can occur in the concentration of urine, blood, and saliva of monitored chemical contaminants and their metabolites plus biomarkers indicative of adverse xenobiotic exposure. The concept of biological time-qualified (for rhythms) reference values, currently of interest to clinical laboratory pathology practice, is seemingly applicable to industrial medicine as circadian time and workshift-specific BEIs to improve surveillance of night workers, in particular. Furthermore, BM as serial assessments performed frequently both during and off work, exemplified by employee self-measurement of lung function using a small portable peak expiratory flow meter, can

  17. The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults.

    Science.gov (United States)

    Lamarche, Dallon T; Meade, Robert D; D'Souza, Andrew W; Flouris, Andreas D; Hardcastle, Stephen G; Sigal, Ronald J; Boulay, Pierre; Kenny, Glen P

    2017-09-01

    The American Conference of Governmental and Industrial Hygienists (ACGIH®) Threshold Limit Values (TLV® guidelines) for work in the heat consist of work-rest (WR) allocations designed to ensure a stable core temperature that does not exceed 38°C. However, the TLV® guidelines have not been validated in older workers. This is an important shortcoming given that adults as young as 40 years demonstrate impairments in their ability to dissipate heat. We therefore evaluated body temperature responses in older adults during work performed in accordance to the TLV® recommended guidelines. On three occasions, 9 healthy older (58 ± 5 years) males performed a 120-min work-simulated protocol in accordance with the TLV® guidelines for moderate-to-heavy intensity work (360 W fixed rate of heat production) in different wet-bulb globe temperatures (WBGT). The first was 120 min of continuous (CON) cycling at 28.0°C WBGT (CON[28°C]). The other two protocols were 15-min intermittent work bouts performed with different WR cycles and WBGT: (i) WR of 3:1 at 29.0°C (WR3:1[29°C]) and (ii) WR of 1:1 at 30.0°C (WR1:1[30°C]). Rectal temperature was measured continuously. The rate of change in mean body temperature was determined via thermometry (weighting coefficients: rectal, 0.9; mean skin temperature, 0.1) and direct calorimetry. Rectal temperature exceeded 38°C in all participants in CON[28°C] and WR3:1[29°C] whereas a statistically similar proportion of workers exceeded 38°C in WR1:1[30°C] (χ 2 ; P = 0.32). The average time for rectal temperature to reach 38°C was: CON[28°C], 53 ± 7; WR3:1[29°C], 79 ± 11; and WR1:1[30°C], 100 ± 29 min. Finally, while a stable mean body temperature was not achieved in any work condition as measured by thermometry (i.e., >0°C·min -1 ; all Pheat balance as determined by direct calorimetry was achieved in WR3:1[29°C] and WR1:1[30°C] (both P ≥ 0.08). Our findings indicate that the TLV® guidelines do not prevent body core

  18. The impact of threshold language assistance programming on the accessibility of mental health services for persons with limited English proficiency in the Medi-Cal setting.

    Science.gov (United States)

    McClellan, Sean R; Wu, Frances M; Snowden, Lonnie R

    2012-06-01

    Title VI of the 1964 Civil Rights Act prohibits federal funds recipients from providing care to limited English proficiency (LEP) persons more limited in scope or lower in quality than care provided to others. In 1999, the California Department of Mental Health implemented a "threshold language access policy" to meet its Title VI obligations. Under this policy, Medi-Cal agencies must provide language assistance programming in a non-English language where a county's Medical population contains either 3000 residents or 5% speakers of that language. We examine the impact of threshold language policy-required language assistance programming on LEP persons' access to mental health services by analyzing the county-level penetration rate of services for Russian, Spanish, and Vietnamese speakers across 34 California counties, over 10 years of quarterly data. Exploiting a time series with nonequivalent control group study design, we studied this phenomena using linear regression with random county effects to account for trends over time. Threshold language policy-required assistance programming led to an immediate and significant increase in the penetration rate of mental health services for Russian (8.2, P language speaking persons. Threshold language assistance programming was effective in increasing mental health access for Russian and Vietnamese, but not for Spanish-speaking LEP persons.

  19. Limitations of threshold voltage engineering of AlGaN/GaN heterostructures by dielectric interface charge density and manipulation by oxygen plasma surface treatments

    Science.gov (United States)

    Lükens, G.; Yacoub, H.; Kalisch, H.; Vescan, A.

    2016-05-01

    The interface charge density between the gate dielectric and an AlGaN/GaN heterostructure has a significant impact on the absolute value and stability of the threshold voltage Vth of metal-insulator-semiconductor (MIS) heterostructure field effect transistor. It is shown that a dry-etching step (as typically necessary for normally off devices engineered by gate-recessing) before the Al2O3 gate dielectric deposition introduces a high positive interface charge density. Its origin is most likely donor-type trap states shifting Vth to large negative values, which is detrimental for normally off devices. We investigate the influence of oxygen plasma annealing techniques of the dry-etched AlGaN/GaN surface by capacitance-voltage measurements and demonstrate that the positive interface charge density can be effectively compensated. Furthermore, only a low Vth hysteresis is observable making this approach suitable for threshold voltage engineering. Analysis of the electrostatics in the investigated MIS structures reveals that the maximum Vth shift to positive voltages achievable is fundamentally limited by the onset of accumulation of holes at the dielectric/barrier interface. In the case of the Al2O3/Al0.26Ga0.74N/GaN material system, this maximum threshold voltage shift is limited to 2.3 V.

  20. The spectral analysis and threshold limits of quasi-supercontinuum self-assembled quantum dot interband lasers

    KAUST Repository

    Tan, Cheeloon

    2009-09-01

    This paper presents a theoretical model to explain the quasi-supercontinuum interband emission from InGaAs/GaAs self-assembled semiconductor quantum dot lasers by accounting for both inhomogeneous and homogeneous optical gain broadening. The experimental and theoretical agreement of a room temperature (293 K) broadband laser emission confirms the presence of multiple-state lasing actions in highly inhomogeneous dot ensembles. The corresponding full-width half-maximum of the photoluminescence is 76 meV as opposed to those wideband lasing coverage at only low temperature (∼60 K) from typical quantum dot lasers. A newly proposed change of homogeneous broadening with injection that occurs only in highly inhomogeneous quantum dot system is critical to account for the continuous wideband lasing but not the conventional ideas of carrier dynamics in semiconductor lasers. In addition, the analysis of threshold conditions reveals that broadband lasing only occurs when the energy spacing between quantized energy states is comparable to the inhomogeneous broadening of quantum-dot nanostructures. The study is important in providing a picture of this novel device and realization of broad lasing coverage for diverse applications, especially in the research field of short-pulse generation and ultra-fast phenomena in semiconductor quantum-dot laser. © 2009 IEEE.

  1. Estimating annual rainfall threshold for establishment of tree species in water-limited ecosystems using tree-ring data

    NARCIS (Netherlands)

    Lopez, B.C.; Holmgren, M.; Sabate, S.; Gracia, C.A.

    2008-01-01

    In arid and semi-arid ecosystems, water availability is discontinuous, highly variable, and characterized by discrete pulse events separated by long periods of limited resource availability. Plant recruitment in these ecosystems is also episodic and dependent on the water available during and after

  2. Theory of threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel

    2002-01-01

    Theory of Threshold Phenomena in Quantum Scattering is developed in terms of Reduced Scattering Matrix. Relationships of different types of threshold anomalies both to nuclear reaction mechanisms and to nuclear reaction models are established. Magnitude of threshold effect is related to spectroscopic factor of zero-energy neutron state. The Theory of Threshold Phenomena, based on Reduced Scattering Matrix, does establish relationships between different types of threshold effects and nuclear reaction mechanisms: the cusp and non-resonant potential scattering, s-wave threshold anomaly and compound nucleus resonant scattering, p-wave anomaly and quasi-resonant scattering. A threshold anomaly related to resonant or quasi resonant scattering is enhanced provided the neutron threshold state has large spectroscopic amplitude. The Theory contains, as limit cases, Cusp Theories and also results of different nuclear reactions models as Charge Exchange, Weak Coupling, Bohr and Hauser-Feshbach models. (author)

  3. Development of slew-rate-limited time-over-threshold (ToT) ASIC for a multi-channel silicon-based ion detector

    Science.gov (United States)

    Uenomachi, M.; Orita, T.; Shimazoe, K.; Takahashi, H.; Ikeda, H.; Tsujita, K.; Sekiba, D.

    2018-01-01

    High-resolution Elastic Recoil Detection Analysis (HERDA), which consists of a 90o sector magnetic spectrometer and a position-sensitive detector (PSD), is a method of quantitative hydrogen analysis. In order to increase sensitivity, a HERDA system using a multi-channel silicon-based ion detector has been developed. Here, as a parallel and fast readout circuit from a multi-channel silicon-based ion detector, a slew-rate-limited time-over-threshold (ToT) application-specific integrated circuit (ASIC) was designed, and a new slew-rate-limited ToT method is proposed. The designed ASIC has 48 channels and each channel consists of a preamplifier, a slew-rate-limited shaping amplifier, which makes ToT response linear, and a comparator. The measured equivalent noise charges (ENCs) of the preamplifier, the shaper, and the ToT on no detector capacitance were 253±21, 343±46, and 560±56 electrons RMS, respectively. The spectra from a 241Am source measured using a slew-rate-limited ToT ASIC are also reported.

  4. Benefits and limitations of using the weather radar for the definition of rainfall thresholds for debris flows. Case study from Catalonia (Spain).

    Science.gov (United States)

    Abancó, C.; Hürlimann, M.; Sempere, D.; Berenguer, M.

    2012-04-01

    Torrential processes such as debris flows or hyperconcentrated flows are fast movements formed by a mix of water and different amounts of unsorted solid material. They occur in steep torrents and suppose a high risk for the human settlements. Rainfall is the most common triggering factor for debris flows. The rainfall threshold defines the rainfall conditions that, when reached or exceeded, are likely to provoke one or more events. Many different types of empirical rainfall thresholds for landslide triggering have been defined. Direct measurements of rainfall data are normally not available from a point next to or in the surroundings of the initiation area of the landslide. For this reason, most of the thresholds published for debris flows have been established by data measured at the nearest rain gauges (often located several km far from the landslide). Only in very few cases, the rainfall data to analyse the triggering conditions of the debris flows have been obtained by weather (Doppler) radar. Radar devices present certain limitations in mountainous regions due to undesired reboots, but their main advantage is that radar data can be obtained for any point of the territory. The objective of this work was to test the use of the weather radar data for the definition of rainfall thresholds for debris-flow triggering. Thus, rainfall data obtained from 3 to 5 rain gauges and from radar were compared for a dataset of events occurred in Catalonia (Spain). The goal was to determine in which cases the description of the rainfall episode (in particular the maximum intensity) had been more accurate. The analysed dataset consists of: 1) three events occurred in the Rebaixader debris-flow monitoring station (Axial Pyrenees) including two hyperconcentrated flows and one debris flow; 2) one debris-flow event occurred in the Port Ainé ski resort (Axial Pyrenees); 3) one debris-flow event in Montserrat (Mediterranean Coastal range). The comparison of the hyetographs from the

  5. Early Liver and Kidney Dysfunction Associated with Occupational Exposure to Sub-Threshold Limit Value Levels of Benzene, Toluene, and Xylenes in Unleaded Petrol.

    Science.gov (United States)

    Neghab, Masoud; Hosseinzadeh, Kiamars; Hassanzadeh, Jafar

    2015-12-01

    Unleaded petrol contains significant amounts of monocyclic aromatic hydrocarbons such as benzene, toluene, and xylenes (BTX). Toxic responses following occupational exposure to unleaded petrol have been evaluated only in limited studies. The main purpose of this study was to ascertain whether (or not) exposure to unleaded petrol, under normal working conditions, is associated with any hepatotoxic or nephrotoxic response. This was a cross-sectional study in which 200 employees of Shiraz petrol stations with current exposure to unleaded petrol, as well as 200 unexposed employees, were investigated. Atmospheric concentrations of BTX were measured using standard methods. Additionally, urine and fasting blood samples were taken from individuals for urinalysis and routine biochemical tests of kidney and liver function. The geometric means of airborne concentrations of BTX were found to be 0.8 mg m(-3), 1.4 mg m(-3), and 2.8 mg m(-3), respectively. Additionally, means of direct bilirubin, alanine aminotransferase, aspartate aminotransferase, blood urea and plasma creatinine were significantly higher in exposed individuals than in unexposed employees. Conversely, serum albumin, total protein, and serum concentrations of calcium and sodium were significantly lower in petrol station workers than in their unexposed counterparts. The average exposure of petrol station workers to BTX did not exceed the current threshold limit values (TLVs) for these chemicals. However, evidence of subtle, subclinical and prepathologic early liver and kidney dysfunction was evident in exposed individuals.

  6. The Strain Index (SI) and Threshold Limit Value (TLV) for Hand Activity Level (HAL): risk of carpal tunnel syndrome (CTS) in a prospective cohort.

    Science.gov (United States)

    Garg, A; Kapellusch, J; Hegmann, K; Wertsch, J; Merryweather, A; Deckow-Schaefer, G; Malloy, E J

    2012-01-01

    A cohort of 536 workers was enrolled from 10 diverse manufacturing facilities and was followed monthly for six years. Job physical exposures were individually measured. Worker demographics, medical history, psychosocial factors, current musculoskeletal disorders (MSDs) and nerve conduction studies (NCS) were obtained. Point and lifetime prevalence of carpal tunnel syndrome (CTS) at baseline (symptoms + abnormal NCS) were 10.3% and 19.8%. During follow-up, there were 35 new CTS cases (left, right or both hands). Factors predicting development of CTS included: job physical exposure (American conference of governmental industrial hygienists Threshold Limit Value (ACGIH TLV) for Hand Activity Level (HAL) and the Strain Index (SI)), age, BMI, other MSDs, inflammatory arthritis, gardening outside of work and feelings of depression. In the adjusted models, the TLV for HAL and the SI were both significant per unit increase in exposure with hazard ratios (HR) increasing up to a maximum of 5.4 (p = 0.05) and 5.3 (p = 0.03), respectively; however, similar to other reports, both suggested lower risk at higher exposures. Data suggest that the TLV for HAL and the SI are useful metrics for estimating exposure to biomechanical stressors. This study was conducted to determine how well the TLV for HAL and the SI predict risk of CTS using a prospective cohort design with survival analysis. Both the TLV for HAL and the SI were found to predict risk of CTS when adjusted for relevant covariates.

  7. Limits on light WIMPs with a 1 kg-scale germanium detector at 160 eVee physics threshold at the China Jinping Underground Laboratory

    Science.gov (United States)

    Yang, Li-Tao; Li, Hau-Bin; Yue, Qian; Kang, Ke-Jun; Cheng, Jian-Ping; Li, Yuan-Jing; Tsz-King Wong, Henry; Aǧartioǧlu, M.; An, Hai-Peng; Chang, Jian-Ping; Chen, Jing-Han; Chen, Yun-Hua; Deng, Zhi; Du, Qiang; Gong, Hui; He, Li; Hu, Jin-Wei; Hu, Qing-Dong; Huang, Han-Xiong; Jia, Li-Ping; Jiang, Hao; Li, Hong; Li, Jian-Min; Li, Jin; Li, Xia; Li, Xue-Qian; Li, Yu-Lan; Lin, Fong-Kay; Lin, Shin-Ted; Liu, Shu-Kui; Liu, Zhong-Zhi; Ma, Hao; Ma, Jing-Lu; Pan, Hui; Ren, Jie; Ruan, Xi-Chao; Sevda, B.; Sharma, Vivek; Shen, Man-Bin; Singh, Lakhwinder; Singh, Manoj Kumar; Tang, Chang-Jian; Tang, Wei-You; Tian, Yang; Wang, Ji-Min; Wang, Li; Wang, Qing; Wang, Yi; Wu, Shi-Yong; Wu, Yu-Cheng; Xing, Hao-Yang; Xu, Yin; Xue, Tao; Yang, Song-Wei; Yi, Nan; Yu, Chun-Xu; Yu, Hai-Jun; Yue, Jian-Feng; Zeng, Xiong-Hui; Zeng, Ming; Zeng, Zhi; Zhang, Yun-Hua; Zhao, Ming-Gang; Zhao, Wei; Zhou, Ji-Fang; Zhou, Zu-Ying; Zhu, Jing-Jun; Zhu, Zhong-Hua; CDEX Collaboration

    2018-01-01

    We report results of a search for light weakly interacting massive particle (WIMP) dark matter from the CDEX-1 experiment at the China Jinping Underground Laboratory (CJPL). Constraints on WIMP-nucleon spin-independent (SI) and spin-dependent (SD) couplings are derived with a physics threshold of 160 eVee, from an exposure of 737.1 kg-days. The SI and SD limits extend the lower reach of light WIMPs to 2 GeV and improve over our earlier bounds at WIMP mass less than 6 GeV. Supported by the National Key Research and Development Program of China (2017YFA0402200, 2017YFA0402201), the National Natural Science Foundation of China (11175099, 11275107, 11475117, 11475099, 11475092, 11675088), the National Basic Research Program of China (973 Program) (2010CB833006). We thank the support of grants from the Tsinghua University Initiative Scientific Research Program (20121088494, 20151080354) and the Academia Sinica Investigator Award 2011-15, contracts 103-2112-M-001-024 and 104-2112-M-001-038-MY3 from the Ministry of Science and Technology of Taiwan.

  8. Determination of the detection limit and decision threshold for ionizing radiation measurements. Part 2: Fundamentals and application to counting measurements with the influence of sample treatment

    International Nuclear Information System (INIS)

    2000-01-01

    This part of ISO 11929 addresses the field of ionizing radiation measurements in which events (in particular pulses) on samples are counted after treating them (e.g. aliquotation, solution, enrichment, separation). It considers, besides the random character of radioactive decay and of pulse counting, all other influences arising from sample treatment, (e.g. weighing, enrichment, calibration or the instability of the test setup). ISO 11929 consists of the following parts, under the general title Determination of the detection limit and decision threshold for ionizing radiation measurements: Part 1: Fundamentals and application to counting measurements without the influence of sample treatment; Part 2: Fundamentals and application to counting measurements with the influence of sample treatment; Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment; Part 4: Fundamentals and application to measurements by use of linear scale analogue ratemeters, without the influence of sample treatment. This part of ISO 11929 was prepared in parallel with other International Standards prepared by WG 2 (now WG 17): ISO 11932:1996, Activity measurements of solid materials considered for recycling, re-use or disposal as non radioactive waste, and ISO 11929-1, ISO 11929-3 and ISO 11929-4 and is, consequently, complementary to these documents

  9. Limited predictive value of achieving beneficial plasma (Z)-endoxifen threshold level by CYP2D6 genotyping in tamoxifen-treated Polish women with breast cancer

    International Nuclear Information System (INIS)

    Hennig, Ewa E.; Piatkowska, Magdalena; Karczmarski, Jakub; Goryca, Krzysztof; Brewczynska, Elzbieta; Jazwiec, Radoslaw; Kluska, Anna; Omiotek, Robert; Paziewska, Agnieszka; Dadlez, Michal; Ostrowski, Jerzy

    2015-01-01

    Tamoxifen, the most frequently used drug for treating estrogen receptor-positive breast cancer, must be converted into active metabolites to exert its therapeutic efficacy, mainly through CYP2D6 enzymes. The objective of this study was to investigate the impact of CYP2D6 polymorphisms on (Z)-endoxifen-directed tamoxifen metabolism and to assess the usefulness of CYP2D6 genotyping for identifying patients who are likely to have insufficient (Z)-endoxifen concentrations to benefit from standard therapy. Blood samples from 279 Polish women with breast cancer receiving tamoxifen 20 mg daily were analyzed for CYP2D6 genotype and drug metabolite concentration. Steady-state plasma levels of tamoxifen and its 14 metabolites were measured by using the ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. In nearly 60 % of patients, including over 30 % of patients with fully functional CYP2D6, (Z)-endoxifen concentration was below the predefined threshold of therapeutic efficacy. The most frequently observed CYP2D6 genotype was EM/PM (34.8 %), among which 83.5 % of patients had a combination of wild-type and *4 alleles. Plasma concentration of five metabolites was significantly correlated with CYP2D6 genotype. For the first time, we identified an association between decreased (E/Z)-4-OH-N-desmethyl-tamoxifen-β-D-glucuronide levels (r 2 = 0.23; p < 10 −16 ) and increased CYP2D6 functional impairment. The strongest correlation was observed for (Z)-endoxifen, whose concentration was significantly lower in groups of patients carrying at least one CYP2D6 null allele, compared with EM/EM patients. The CYP2D6 genotype accounted for plasma level variability of (Z)-endoxifen by 27 % (p < 10 −16 ) and for the variability of metabolic ratio indicating (Z)-endoxifen-directed metabolism of tamoxifen by 51 % (p < 10 −43 ). The majority of breast cancer patients in Poland may not achieve a therapeutic level of (Z)-endoxifen upon receiving a standard

  10. Optimizing Systems of Threshold Detection Sensors

    National Research Council Canada - National Science Library

    Banschbach, David C

    2008-01-01

    .... Below the threshold all signals are ignored. We develop a mathematical model for setting individual sensor thresholds to obtain optimal probability of detecting a significant event, given a limit on the total number of false positives allowed...

  11. An isotope dilution gas chromatography/mass spectrometry method for trace analysis of xylene and its metabolites in tissues following threshold limit value exposures

    Energy Technology Data Exchange (ETDEWEB)

    Pyon, K.H.; Kracko, D.A.; Strunk, M.R. [and others

    1995-12-01

    The existence of a nose-brain barrier that functions to protect the central nervous system (CNS) from inhaled toxicants has been postulated. Just as a blood-brain barrier protects the CNS from systemic toxicants, the nose-brain barrier may have similar characteristic functions. One component of interest is nasal xenobiotic metabolism and its effect on the transport of pollutants into the CNS at environmentally plausible levels of exposure. Previous results have shown that inhaled xylene are dimethyl phenol (DMP) and methyl benzyl alcohol (MBA), and the nonvolatile metabolites are toluic acid (TA) and methyl hippuric acid (MHA). The nonvolatile metabolites of xylene, along with a small quantity of volatiles, representing either parent xylene or volatile metabolites, are transported via the olfactory epithelium to the glomeruli within the olfactory bulbs of the brain. Further work will be done to establish the linearity for each analyte at the actual highest detection limit of the GC/MS.

  12. An isotope dilution gas chromatography/mass spectrometry method for trace analysis of xylene and its metabolites in tissues following threshold limit value exposures

    International Nuclear Information System (INIS)

    Pyon, K.H.; Kracko, D.A.; Strunk, M.R.

    1995-01-01

    The existence of a nose-brain barrier that functions to protect the central nervous system (CNS) from inhaled toxicants has been postulated. Just as a blood-brain barrier protects the CNS from systemic toxicants, the nose-brain barrier may have similar characteristic functions. One component of interest is nasal xenobiotic metabolism and its effect on the transport of pollutants into the CNS at environmentally plausible levels of exposure. Previous results have shown that inhaled xylene are dimethyl phenol (DMP) and methyl benzyl alcohol (MBA), and the nonvolatile metabolites are toluic acid (TA) and methyl hippuric acid (MHA). The nonvolatile metabolites of xylene, along with a small quantity of volatiles, representing either parent xylene or volatile metabolites, are transported via the olfactory epithelium to the glomeruli within the olfactory bulbs of the brain. Further work will be done to establish the linearity for each analyte at the actual highest detection limit of the GC/MS

  13. CARA Risk Assessment Thresholds

    Science.gov (United States)

    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).

  14. Decision Threshold and Detection Limit in Spectrometric Measurements. Part 1: Application to Gamma Spectrometry; Umbral de Decision y Limite de Deteccion en Medidas Espectrometricas. Parte 1: Aplicacion a la Espectrometria Gamma

    Energy Technology Data Exchange (ETDEWEB)

    Perez, C.; Gasco, C.; Lopez, M.A.

    2010-03-03

    This report summarised the author's lecture of the advanced gamma spectrometry course organised by CIEMAT. The characteristic limits determination in gamma spectrometry generally is obtained through the programming that the trade marks offers to the client with the objective of the automatic calculation of the activity concentrations existing in a sample. In this report, the examples shown in the ISO 11929 standard are compared to the programming realised by Genie 2k for determining characteristic limits. The main difference of both is located in the uncertainty calculations due to the efficiency calibration that is considered by ISO and not by Genie 2K. Through implementation in the software developed by trade marks will be possible to introduce this uncertainty and to assimilate to the calculation done by ISO 11929. In the second part of this report will be analyzed the more complicated samples of this application as counting in a whole body counter (following ISO-28218 about Performance Criteria for radio bioassay), multiplet, overlapping, addition of several peaks for obtaining the activity concentration, etc. (Author) 19 refs.

  15. Music effect on pain threshold evaluated with current perception threshold

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    AIM: Music relieves anxiety and psychotic tension. This effect of music is applied to surgical operation in the hospital and dental office. It is still unclear whether this music effect is only limited to the psychological aspect but not to the physical aspect or whether its music effect is influenced by the mood or emotion of audience. To elucidate these issues, we evaluated the music effect on pain threshold by current perception threshold (CPT) and profile of mood states (POMC) test. METHODS: Healthy 30 subjects (12 men, 18 women, 25-49 years old, mean age 34.9) were tested. (1)After POMC test, all subjects were evaluated pain threshold with CPT by Neurometer (Radionics, USA) under 6 conditions, silence, listening to the slow tempo classic music, nursery music, hard rock music, classic paino music and relaxation music with 30 seconds interval. (2)After Stroop color word test as the stresser, pain threshold was evaluated with CPT under 2 conditions, silence and listening to the slow tempo classic music. RESULTS: Under litening to the music, CPT sores increased, especially 2 000 Hz level related with compression, warm and pain sensation. Type of music, preference of music and stress also affected CPT score. CONCLUSION: The present study demonstrated that the concentration on the music raise the pain threshold and that stress and mood influence the music effect on pain threshold.

  16. Threshold quantum cryptography

    International Nuclear Information System (INIS)

    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

  17. Doubler system quench detection threshold

    International Nuclear Information System (INIS)

    Kuepke, K.; Kuchnir, M.; Martin, P.

    1983-01-01

    The experimental study leading to the determination of the sensitivity needed for protecting the Fermilab Doubler from damage during quenches is presented. The quench voltage thresholds involved were obtained from measurements made on Doubler cable of resistance x temperature and voltage x time during quenches under several currents and from data collected during operation of the Doubler Quench Protection System as implemented in the B-12 string of 20 magnets. At 4kA, a quench voltage threshold in excess of 5.OV will limit the peak Doubler cable temperature to 452K for quenches originating in the magnet coils whereas a threshold of 0.5V is required for quenches originating outside of coils

  18. Detection thresholds of macaque otolith afferents.

    Science.gov (United States)

    Yu, Xiong-Jie; Dickman, J David; Angelaki, Dora E

    2012-06-13

    The vestibular system is our sixth sense and is important for spatial perception functions, yet the sensory detection and discrimination properties of vestibular neurons remain relatively unexplored. Here we have used signal detection theory to measure detection thresholds of otolith afferents using 1 Hz linear accelerations delivered along three cardinal axes. Direction detection thresholds were measured by comparing mean firing rates centered on response peak and trough (full-cycle thresholds) or by comparing peak/trough firing rates with spontaneous activity (half-cycle thresholds). Thresholds were similar for utricular and saccular afferents, as well as for lateral, fore/aft, and vertical motion directions. When computed along the preferred direction, full-cycle direction detection thresholds were 7.54 and 3.01 cm/s(2) for regular and irregular firing otolith afferents, respectively. Half-cycle thresholds were approximately double, with excitatory thresholds being half as large as inhibitory thresholds. The variability in threshold among afferents was directly related to neuronal gain and did not depend on spike count variance. The exact threshold values depended on both the time window used for spike count analysis and the filtering method used to calculate mean firing rate, although differences between regular and irregular afferent thresholds were independent of analysis parameters. The fact that minimum thresholds measured in macaque otolith afferents are of the same order of magnitude as human behavioral thresholds suggests that the vestibular periphery might determine the limit on our ability to detect or discriminate small differences in head movement, with little noise added during downstream processing.

  19. Determination of the detection limit and decision threshold for ionizing radiation measurements. Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment

    International Nuclear Information System (INIS)

    2000-01-01

    This part of ISO 11929 addresses the field of ionizing radiation measurements in which events (in particular pulses) are counted by high resolution gamma spectrometry registrating a pulse-heights distribution (acquisition of a multichannel spectrum), for example on samples. It considers exclusively the random character of radioactive decay and of pulse counting and ignores all other influences (e.g. arising from sample treatment, weighing, enrichment or the instability of the test setup). It assumes that the distance of neighbouring peaks of gamma lines is not smaller than four times the full width half maximum (FWHM) of gamma line and that the background near to gamma line is nearly a straight line. Otherwise ISO 11929-1 or ISO 11929-2 should be used. ISO 11929 consists of the following parts, under the general title Determination of the detection limit and decision threshold for ionizing radiation measurements: Part 1: Fundamentals and application to counting measurements without the influence of sample treatment; Part 2: Fundamentals and application to counting measurements with the influence of sample treatment; Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment; Part 4: Fundamentals and application to measurements by use of linear scale analogue ratemeters, without the influence of sample treatment. This part of ISO 11929 was prepared in parallel with other International Standards prepared by WG2 (now WG 17): ISO 11932:1996, Activity measurements of solid materials considered for recycling, re-use or disposal as nonradioactive waste, and ISO 11929-1, ISO 11929-2 and ISO 11929-4, and is, consequently, complementary to these documents

  20. Threshold Signature Schemes Application

    Directory of Open Access Journals (Sweden)

    Anastasiya Victorovna Beresneva

    2015-10-01

    Full Text Available This work is devoted to an investigation of threshold signature schemes. The systematization of the threshold signature schemes was done, cryptographic constructions based on interpolation Lagrange polynomial, elliptic curves and bilinear pairings were examined. Different methods of generation and verification of threshold signatures were explored, the availability of practical usage of threshold schemes in mobile agents, Internet banking and e-currency was shown. The topics of further investigation were given and it could reduce a level of counterfeit electronic documents signed by a group of users.

  1. Particles near threshold

    International Nuclear Information System (INIS)

    Bhattacharya, T.; Willenbrock, S.

    1993-01-01

    We propose returning to the definition of the width of a particle in terms of the pole in the particle's propagator. Away from thresholds, this definition of width is equivalent to the standard perturbative definition, up to next-to-leading order; however, near a threshold, the two definitions differ significantly. The width as defined by the pole position provides more information in the threshold region than the standard perturbative definition and, in contrast with the perturbative definition, does not vanish when a two-particle s-wave threshold is approached from below

  2. Double Photoionization Near Threshold

    Science.gov (United States)

    Wehlitz, Ralf

    2007-01-01

    The threshold region of the double-photoionization cross section is of particular interest because both ejected electrons move slowly in the Coulomb field of the residual ion. Near threshold both electrons have time to interact with each other and with the residual ion. Also, different theoretical models compete to describe the double-photoionization cross section in the threshold region. We have investigated that cross section for lithium and beryllium and have analyzed our data with respect to the latest results in the Coulomb-dipole theory. We find that our data support the idea of a Coulomb-dipole interaction.

  3. Thresholds in radiobiology

    International Nuclear Information System (INIS)

    Katz, R.; Hofmann, W.

    1982-01-01

    Interpretations of biological radiation effects frequently use the word 'threshold'. The meaning of this word is explored together with its relationship to the fundamental character of radiation effects and to the question of perception. It is emphasised that although the existence of either a dose or an LET threshold can never be settled by experimental radiobiological investigations, it may be argued on fundamental statistical grounds that for all statistical processes, and especially where the number of observed events is small, the concept of a threshold is logically invalid. (U.K.)

  4. Quench limits

    International Nuclear Information System (INIS)

    Sapinski, M.

    2012-01-01

    With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

  5. Regional Seismic Threshold Monitoring

    National Research Council Canada - National Science Library

    Kvaerna, Tormod

    2006-01-01

    ... model to be used for predicting the travel times of regional phases. We have applied these attenuation relations to develop and assess a regional threshold monitoring scheme for selected subregions of the European Arctic...

  6. Risk assessments using the Strain Index and the TLV for HAL, Part II: Multi-task jobs and prevalence of CTS.

    Science.gov (United States)

    Kapellusch, Jay M; Silverstein, Barbara A; Bao, Stephen S; Thiese, Mathew S; Merryweather, Andrew S; Hegmann, Kurt T; Garg, Arun

    2018-02-01

    The Strain Index (SI) and the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL) have been shown to be associated with prevalence of distal upper-limb musculoskeletal disorders such as carpal tunnel syndrome (CTS). The SI and TLV for HAL disagree on more than half of task exposure classifications. Similarly, time-weighted average (TWA), peak, and typical exposure techniques used to quantity physical exposure from multi-task jobs have shown between-technique agreement ranging from 61% to 93%, depending upon whether the SI or TLV for HAL model was used. This study compared exposure-response relationships between each model-technique combination and prevalence of CTS. Physical exposure data from 1,834 workers (710 with multi-task jobs) were analyzed using the SI and TLV for HAL and the TWA, typical, and peak multi-task job exposure techniques. Additionally, exposure classifications from the SI and TLV for HAL were combined into a single measure and evaluated. Prevalent CTS cases were identified using symptoms and nerve-conduction studies. Mixed effects logistic regression was used to quantify exposure-response relationships between categorized (i.e., low, medium, and high) physical exposure and CTS prevalence for all model-technique combinations, and for multi-task workers, mono-task workers, and all workers combined. Except for TWA TLV for HAL, all model-technique combinations showed monotonic increases in risk of CTS with increased physical exposure. The combined-models approach showed stronger association than the SI or TLV for HAL for multi-task workers. Despite differences in exposure classifications, nearly all model-technique combinations showed exposure-response relationships with prevalence of CTS for the combined sample of mono-task and multi-task workers. Both the TLV for HAL and the SI, with the TWA or typical techniques, appear useful for epidemiological studies and surveillance

  7. Threshold guidance update

    International Nuclear Information System (INIS)

    Wickham, L.E.

    1986-01-01

    The Department of Energy (DOE) is developing the concept of threshold quantities for use in determining which waste materials must be handled as radioactive waste and which may be disposed of as nonradioactive waste at its sites. Waste above this concentration level would be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. Last years' activities (1984) included the development of a threshold guidance dose, the development of threshold concentrations corresponding to the guidance dose, the development of supporting documentation, review by a technical peer review committee, and review by the DOE community. As a result of the comments, areas have been identified for more extensive analysis, including an alternative basis for selection of the guidance dose and the development of quality assurance guidelines. Development of quality assurance guidelines will provide a reasonable basis for determining that a given waste stream qualifies as a threshold waste stream and can then be the basis for a more extensive cost-benefit analysis. The threshold guidance and supporting documentation will be revised, based on the comments received. The revised documents will be provided to DOE by early November. DOE-HQ has indicated that the revised documents will be available for review by DOE field offices and their contractors

  8. Near threshold fatigue testing

    Science.gov (United States)

    Freeman, D. C.; Strum, M. J.

    1993-01-01

    Measurement of the near-threshold fatigue crack growth rate (FCGR) behavior provides a basis for the design and evaluation of components subjected to high cycle fatigue. Typically, the near-threshold fatigue regime describes crack growth rates below approximately 10(exp -5) mm/cycle (4 x 10(exp -7) inch/cycle). One such evaluation was recently performed for the binary alloy U-6Nb. The procedures developed for this evaluation are described in detail to provide a general test method for near-threshold FCGR testing. In particular, techniques for high-resolution measurements of crack length performed in-situ through a direct current, potential drop (DCPD) apparatus, and a method which eliminates crack closure effects through the use of loading cycles with constant maximum stress intensity are described.

  9. Threshold factorization redux

    Science.gov (United States)

    Chay, Junegone; Kim, Chul

    2018-05-01

    We reanalyze the factorization theorems for the Drell-Yan process and for deep inelastic scattering near threshold, as constructed in the framework of the soft-collinear effective theory (SCET), from a new, consistent perspective. In order to formulate the factorization near threshold in SCET, we should include an additional degree of freedom with small energy, collinear to the beam direction. The corresponding collinear-soft mode is included to describe the parton distribution function (PDF) near threshold. The soft function is modified by subtracting the contribution of the collinear-soft modes in order to avoid double counting on the overlap region. As a result, the proper soft function becomes infrared finite, and all the factorized parts are free of rapidity divergence. Furthermore, the separation of the relevant scales in each factorized part becomes manifest. We apply the same idea to the dihadron production in e+e- annihilation near threshold, and show that the resultant soft function is also free of infrared and rapidity divergences.

  10. Elaborating on Threshold Concepts

    Science.gov (United States)

    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…

  11. Some considerations regarding the creep crack growth threshold

    International Nuclear Information System (INIS)

    Thouless, M.D.; Evans, A.G.

    1984-01-01

    The preceding analysis reveals that the existence of a threshold determined by the sintering stress does not influence the post threshold crack velocity. Considerations of the sintering stress can thus be conveniently excluded from analysis of the post threshold crack velocity. The presence of a crack growth threshold has been predicted, based on the existence of cavity nucleation controlled crack growth. A preliminary analysis of cavity nucleation rates within the damage zone reveals that this threshold is relatively abrupt, in accord with experimental observations. Consequently, at stress intensities below K /SUB th/ growth becomes nucleation limited and crack blunting occurs in preference to crack growth

  12. Hadron production near threshold

    Indian Academy of Sciences (India)

    Abstract. Final state interaction effects in pp → pΛK+ and pd → 3He η reactions are explored near threshold to study the sensitivity of the cross-sections to the pΛ potential and the ηN scattering matrix. The final state scattering wave functions between Λ and p and η and 3He are described rigorously. The Λ production is ...

  13. Casualties and threshold effects

    International Nuclear Information System (INIS)

    Mays, C.W.; National Cancer Inst., Bethesda

    1988-01-01

    Radiation effects like cancer are denoted as casualties. Other radiation effects occur almost in everyone when the radiation dose is sufficiently high. One then speaks of radiation effects with a threshold dose. In this article the author puts his doubt about this classification of radiation effects. He argues that some effects of exposure to radiation do not fit in this classification. (H.W.). 19 refs.; 2 figs.; 1 tab

  14. Resonance phenomena near thresholds

    International Nuclear Information System (INIS)

    Persson, E.; Mueller, M.; Rotter, I.; Technische Univ. Dresden

    1995-12-01

    The trapping effect is investigated close to the elastic threshold. The nucleus is described as an open quantum mechanical many-body system embedded in the continuum of decay channels. An ensemble of compound nucleus states with both discrete and resonance states is investigated in an energy-dependent formalism. It is shown that the discrete states can trap the resonance ones and also that the discrete states can directly influence the scattering cross section. (orig.)

  15. Thresholding methods for PET imaging: A review

    International Nuclear Information System (INIS)

    Dewalle-Vignion, A.S.; Betrouni, N.; Huglo, D.; Vermandel, M.; Dewalle-Vignion, A.S.; Hossein-Foucher, C.; Huglo, D.; Vermandel, M.; Dewalle-Vignion, A.S.; Hossein-Foucher, C.; Huglo, D.; Vermandel, M.; El Abiad, A.

    2010-01-01

    This work deals with positron emission tomography segmentation methods for tumor volume determination. We propose a state of art techniques based on fixed or adaptive threshold. Methods found in literature are analysed with an objective point of view on their methodology, advantages and limitations. Finally, a comparative study is presented. (authors)

  16. Threshold switching uniformity in In2Se3 nanowire-based phase change memory

    International Nuclear Information System (INIS)

    Chen Jian; Du Gang; Liu Xiao-Yan

    2015-01-01

    The uniformity of threshold voltage and threshold current in the In 2 Se 3 nanowire-based phase change memory (PCM) devices is investigated. Based on the trap-limited transport model, amorphous layer thickness, trap density, and trap depth are considered to clarify their influences upon the threshold voltage and threshold current through simulations. (paper)

  17. Risk thresholds for alcohol consumption

    DEFF Research Database (Denmark)

    Wood, Angela M; Kaptoge, Stephen; Butterworth, Adam S

    2018-01-01

    previous cardiovascular disease. METHODS: We did a combined analysis of individual-participant data from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). We characterised dose-response associations and calculated hazard......BACKGROUND: Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers without......·4 million person-years of follow-up. For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week. Alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100...

  18. Intermediate structure and threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel

    2004-01-01

    The Intermediate Structure, evidenced through microstructures of the neutron strength function, is reflected in open reaction channels as fluctuations in excitation function of nuclear threshold effects. The intermediate state supporting both neutron strength function and nuclear threshold effect is a micro-giant neutron threshold state. (author)

  19. Effects of pulse duration on magnetostimulation thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Saritas, Emine U., E-mail: saritas@ee.bilkent.edu.tr [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey); National Magnetic Resonance Research Center (UMRAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Goodwill, Patrick W. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Conolly, Steven M. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of EECS, University of California, Berkeley, California 94720-1762 (United States)

    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

  20. Effects of pulse duration on magnetostimulation thresholds

    International Nuclear Information System (INIS)

    Saritas, Emine U.; Goodwill, Patrick W.; Conolly, Steven M.

    2015-01-01

    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

  1. The threshold photoelectron spectrum of mercury

    International Nuclear Information System (INIS)

    Rojas, H; Dawber, G; Gulley, N; King, G C; Bowring, N; Ward, R

    2013-01-01

    The threshold photoelectron spectrum of mercury has been recorded over the energy range (10–40 eV) which covers the region from the lowest state of the singly charged ion, 5d 10 6s( 2 S 1/2 ), to the double charged ionic state, 5d 9 ( 2 D 3/2 )6s( 1 D 2 ). Synchrotron radiation has been used in conjunction with the penetrating-field threshold-electron technique to obtain the spectrum with high resolution. The spectrum shows many more features than observed in previous photoemission measurements with many of these assigned to satellite states converging to the double ionization limit. (paper)

  2. Regional rainfall thresholds for landslide occurrence using a centenary database

    Science.gov (United States)

    Vaz, Teresa; Luís Zêzere, José; Pereira, Susana; Cruz Oliveira, Sérgio; Garcia, Ricardo A. C.; Quaresma, Ivânia

    2018-04-01

    This work proposes a comprehensive method to assess rainfall thresholds for landslide initiation using a centenary landslide database associated with a single centenary daily rainfall data set. The method is applied to the Lisbon region and includes the rainfall return period analysis that was used to identify the critical rainfall combination (cumulated rainfall duration) related to each landslide event. The spatial representativeness of the reference rain gauge is evaluated and the rainfall thresholds are assessed and calibrated using the receiver operating characteristic (ROC) metrics. Results show that landslide events located up to 10 km from the rain gauge can be used to calculate the rainfall thresholds in the study area; however, these thresholds may be used with acceptable confidence up to 50 km from the rain gauge. The rainfall thresholds obtained using linear and potential regression perform well in ROC metrics. However, the intermediate thresholds based on the probability of landslide events established in the zone between the lower-limit threshold and the upper-limit threshold are much more informative as they indicate the probability of landslide event occurrence given rainfall exceeding the threshold. This information can be easily included in landslide early warning systems, especially when combined with the probability of rainfall above each threshold.

  3. Coloring geographical threshold graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Percus, Allon [Los Alamos National Laboratory; Muller, Tobias [EINDHOVEN UNIV. OF TECH

    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.

  4. Crossing the Petawatt threshold

    International Nuclear Information System (INIS)

    Perry, M.

    1996-01-01

    A revolutionary new laser called the Petawatt, developed by Lawrence Livermore researchers after an intensive three-year development effort, has produced more than 1,000 trillion (open-quotes petaclose quotes) watts of power, a world record. By crossing the petawatt threshold, the extraordinarily powerful laser heralds a new age in laser research. Lasers that provide a petawatt of power or more in a picosecond may make it possible to achieve fusion using significantly less energy than currently envisioned, through a novel Livermore concept called open-quotes fast ignition.close quotes The petawatt laser will also enable researchers to study the fundamental properties of matter, thereby aiding the Department of Energy's Stockpile Stewardship efforts and opening entirely new physical regimes to study. The technology developed for the Petawatt has also provided several spinoff technologies, including a new approach to laser material processing

  5. Eigen's Error Threshold and Mutational Meltdown in a Quasispecies Model

    OpenAIRE

    Bagnoli, F.; Bezzi, M.

    1998-01-01

    We introduce a toy model for interacting populations connected by mutations and limited by a shared resource. We study the presence of Eigen's error threshold and mutational meltdown. The phase diagram of the system shows that the extinction of the whole population due to mutational meltdown can occur well before an eventual error threshold transition.

  6. Effect of threshold quantization in opportunistic splitting algorithm

    KAUST Repository

    Nam, Haewoon

    2011-12-01

    This paper discusses algorithms to find the optimal threshold and also investigates the impact of threshold quantization on the scheduling outage performance of the opportunistic splitting scheduling algorithm. Since this algorithm aims at finding the user with the highest channel quality within the minimal number of mini-slots by adjusting the threshold every mini-slot, optimizing the threshold is of paramount importance. Hence, in this paper we first discuss how to compute the optimal threshold along with two tight approximations for the optimal threshold. Closed-form expressions are provided for those approximations for simple calculations. Then, we consider linear quantization of the threshold to take the limited number of bits for signaling messages in practical systems into consideration. Due to the limited granularity for the quantized threshold value, an irreducible scheduling outage floor is observed. The numerical results show that the two approximations offer lower scheduling outage probability floors compared to the conventional algorithm when the threshold is quantized. © 2006 IEEE.

  7. Crossing the threshold

    Science.gov (United States)

    Bush, John; Tambasco, Lucas

    2017-11-01

    First, we summarize the circumstances in which chaotic pilot-wave dynamics gives rise to quantum-like statistical behavior. For ``closed'' systems, in which the droplet is confined to a finite domain either by boundaries or applied forces, quantum-like features arise when the persistence time of the waves exceeds the time required for the droplet to cross its domain. Second, motivated by the similarities between this hydrodynamic system and stochastic electrodynamics, we examine the behavior of a bouncing droplet above the Faraday threshold, where a stochastic element is introduced into the drop dynamics by virtue of its interaction with a background Faraday wave field. With a view to extending the dynamical range of pilot-wave systems to capture more quantum-like features, we consider a generalized theoretical framework for stochastic pilot-wave dynamics in which the relative magnitudes of the drop-generated pilot-wave field and a stochastic background field may be varied continuously. We gratefully acknowledge the financial support of the NSF through their CMMI and DMS divisions.

  8. Albania - Thresholds I and II

    Data.gov (United States)

    Millennium Challenge Corporation — From 2006 to 2011, the government of Albania (GOA) received two Millennium Challenge Corporation (MCC) Threshold Programs totaling $29.6 million. Albania received...

  9. Thresholds in Xeric Hydrology and Biogeochemistry

    Science.gov (United States)

    Meixner, T.; Brooks, P. D.; Simpson, S. C.; Soto, C. D.; Yuan, F.; Turner, D.; Richter, H.

    2011-12-01

    Due to water limitation, thresholds in hydrologic and biogeochemical processes are common in arid and semi-arid systems. Some of these thresholds such as those focused on rainfall runoff relationships have been well studied. However to gain a full picture of the role that thresholds play in driving the hydrology and biogeochemistry of xeric systems a full view of the entire array of processes at work is needed. Here a walk through the landscape of xeric systems will be conducted illustrating the powerful role of hydrologic thresholds on xeric system biogeochemistry. To understand xeric hydro-biogeochemistry two key ideas need to be focused on. First, it is important to start from a framework of reaction and transport. Second an understanding of the temporal and spatial components of thresholds that have a large impact on hydrologic and biogeochemical fluxes needs to be offered. In the uplands themselves episodic rewetting and drying of soils permits accelerated biogeochemical processing but also more gradual drainage of water through the subsurface than expected in simple conceptions of biogeochemical processes. Hydrologic thresholds (water content above hygroscopic) results in a stop start nutrient spiral of material across the landscape since runoff connecting uplands to xeric perennial riparian is episodic and often only transports materials a short distance (100's of m). This episodic movement results in important and counter-intuitive nutrient inputs to riparian zones but also significant processing and uptake of nutrients. The floods that transport these biogeochemicals also result in significant input to riparian groundwater and may be key to sustaining these critical ecosystems. Importantly the flood driven recharge process itself is a threshold process dependent on flood characteristics (floods greater than 100 cubic meters per second) and antecedent conditions (losing to near neutral gradients). Floods also appear to influence where arid and semi

  10. Threshold Concepts and Information Literacy

    Science.gov (United States)

    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…

  11. A threshold limit theorem for the stochastic logistic epidemic

    OpenAIRE

    Andersson, Håkan; Djehiche, Boualem

    1998-01-01

    The time until extinction for the closed SIS stochastic logistic epidemic model is investigated. We derive the asymptotic distribution for the extinction time as the population grows to infinity, under different initial conditions and for different values of the infection rate.

  12. dynamic-threshold-limited timed-token (dtltt) protocol

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... Token (STOGSTT) Media Access Control (MAC) protocol for channel capacity allocation to the asynchronous traffic in ... Keywords: multi-access, multiservice, network, synchronous, asynchronous, traffic, timed-token. 1. Introduction .... Messages generated in the system at run time may be classified as ...

  13. Practical threshold limit values in a conversion plant

    International Nuclear Information System (INIS)

    Faron, R.

    1996-01-01

    Comurhex in a subsidiary of the Cogema group, and its business is the conversion to hexafluoride of the uranium contained in a variety of mining concentrates of differing origins. This report gives an example of the evaluation of the health aspects of a conversion plant. (author). 11 figs

  14. Ingmar Bergman in the museum? Thresholds, limits, conditions of possibility

    NARCIS (Netherlands)

    Elsaesser, T.

    2009-01-01

    ‘THE CINEMA IS DEAD*LONG LIVE THE CINEMA (IN THE MUSEUM)’ For several decades now, the cinema’s demise has been presented as a fact: at first, television took away the family audience, then the video recorder killed off the neighbourhood cinemas, and now digitisation has broken the indexicality of

  15. fm threshold and methods of limiting its effect on performance

    African Journals Online (AJOL)

    SAMSON BRIGHT ONYEDIKACHI

    Non-coherent detection schemes are characterized by this. Noise ni (t) BPF ... R C. G d. Y t. G K V t. n t. K A dt π. = +. (9) or. 4. () 2. (). (). f m i. Y t. G K V t n t π. = +. (10) ..... p.337. 10. M.A. Ahaneku. NIGERIAN JOURNAL OF TECHNOLOGY, VOL.

  16. Estimating threshold limits for mercury in biological material

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, M H

    1963-01-01

    A brief historical review of the study of occupational exposure to mercury is presented. Important factors in the determination of the tolerable body burden of mercury are discussed, notably the body distribution of mercury after exposure, and the risk of accumulation in different organs. In acute exposure the kidney and liver accumulate much mercury and are hence liable to injury, while recent findings indicate that in chronic exposure to moderate levels of mercury the brain and possibly testes are the critical organs because of a pronounced tendency to accumulate. The possibility of obtaining an index of mercury retention is explored; it is concluded that urinary mercury excretion does not reflect the level of body retention although it may indicate very recent exposure. It is suggested that mercury concentration in biopsies of skin, liver, kidney and colonic mucosa may serve as an index of body retention of mercury. 37 references, 7 figures.

  17. Rayleigh scattering from ions near threshold

    International Nuclear Information System (INIS)

    Roy, S.C.; Gupta, S.K.S.; Kissel, L.; Pratt, R.H.

    1988-01-01

    Theoretical studies of Rayleigh scattering of photons from neon atoms with different degrees of ionization, for energies both below and above the K-edges of the ions, are presented. Some unexpected structures both in Rayleigh scattering and in photoionization from neutral and weakly ionized atoms, very close to threshold, have been reported. It has recently been realized that some of the predicted structures may have a nonphysical origin and are due to the limitation of the independent-particle model and also to the use of a Coulombic Latter tail. Use of a K-shell vacancy potential - in which an electron is assumed to be removed from the K-shell - in calculating K-shell Rayleigh scattering amplitudes removes some of the structure effects near threshold. We present in this work a discussion of scattering angular distributions and total cross sections, obtained utilizing vacancy potentials, and compare these predictions with those previously obtained in other potential model. (author) [pt

  18. Parton distributions with threshold resummation

    CERN Document Server

    Bonvini, Marco; Rojo, Juan; Rottoli, Luca; Ubiali, Maria; Ball, Richard D.; Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P.

    2015-01-01

    We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculation. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.

  19. Conceptions of nuclear threshold status

    International Nuclear Information System (INIS)

    Quester, G.H.

    1991-01-01

    This paper reviews some alternative definitions of nuclear threshold status. Each of them is important, and major analytical confusions would result if one sense of the term is mistaken for another. The motives for nations entering into such threshold status are a blend of civilian and military gains, and of national interests versus parochial or bureaucratic interests. A portion of the rationale for threshold status emerges inevitably from the pursuit of economic goals, and another portion is made more attraction by the derives of the domestic political process. Yet the impact on international security cannot be dismissed, especially where conflicts among the states remain real. Among the military or national security motives are basic deterrence, psychological warfare, war-fighting and, more generally, national prestige. In the end, as the threshold phenomenon is assayed for lessons concerning the role of nuclear weapons more generally in international relations and security, one might conclude that threshold status and outright proliferation coverage to a degree in the motives for all of the states involved and in the advantages attained. As this paper has illustrated, nuclear threshold status is more subtle and more ambiguous than outright proliferation, and it takes considerable time to sort out the complexities. Yet the world has now had a substantial amount of time to deal with this ambiguous status, and this may tempt more states to exploit it

  20. Novel Threshold Changeable Secret Sharing Schemes Based on Polynomial Interpolation.

    Science.gov (United States)

    Yuan, Lifeng; Li, Mingchu; Guo, Cheng; Choo, Kim-Kwang Raymond; Ren, Yizhi

    2016-01-01

    After any distribution of secret sharing shadows in a threshold changeable secret sharing scheme, the threshold may need to be adjusted to deal with changes in the security policy and adversary structure. For example, when employees leave the organization, it is not realistic to expect departing employees to ensure the security of their secret shadows. Therefore, in 2012, Zhang et al. proposed (t → t', n) and ({t1, t2,⋯, tN}, n) threshold changeable secret sharing schemes. However, their schemes suffer from a number of limitations such as strict limit on the threshold values, large storage space requirement for secret shadows, and significant computation for constructing and recovering polynomials. To address these limitations, we propose two improved dealer-free threshold changeable secret sharing schemes. In our schemes, we construct polynomials to update secret shadows, and use two-variable one-way function to resist collusion attacks and secure the information stored by the combiner. We then demonstrate our schemes can adjust the threshold safely.

  1. Threshold Learning Dynamics in Social Networks

    Science.gov (United States)

    González-Avella, Juan Carlos; Eguíluz, Victor M.; Marsili, Matteo; Vega-Redondo, Fernado; San Miguel, Maxi

    2011-01-01

    Social learning is defined as the ability of a population to aggregate information, a process which must crucially depend on the mechanisms of social interaction. Consumers choosing which product to buy, or voters deciding which option to take with respect to an important issue, typically confront external signals to the information gathered from their contacts. Economic models typically predict that correct social learning occurs in large populations unless some individuals display unbounded influence. We challenge this conclusion by showing that an intuitive threshold process of individual adjustment does not always lead to such social learning. We find, specifically, that three generic regimes exist separated by sharp discontinuous transitions. And only in one of them, where the threshold is within a suitable intermediate range, the population learns the correct information. In the other two, where the threshold is either too high or too low, the system either freezes or enters into persistent flux, respectively. These regimes are generally observed in different social networks (both complex or regular), but limited interaction is found to promote correct learning by enlarging the parameter region where it occurs. PMID:21637714

  2. A inadequação dos valores dos limites de tolerância biológica para a prevenção da intoxicação profissional pelo chumbo no Brasil The inadequacy of threshold values for preventing lead poisoning in Brazil

    Directory of Open Access Journals (Sweden)

    Ricardo Cordeiro

    1995-06-01

    Full Text Available São revisados os trabalhos que, a partir de 1975,estudaram a ocorrência de manifestações neurológicas centrais e periféricas em trabalhadores ocupacionalmente expostos ao chumbo, que apresentavam níveis de exposição supostamente insuficientes para causarem Saturnismo. A partir da revisão realizada é sugerido que os limites de tolerância biológica utilizados em nosso meio para firmar o diagnóstico de intoxicação profissional pelo chumbo devam ser revistos. Tal sugestão baseia-se na existência de evidências bem estabelecidas que apontam disfunções da condução nervosa periférica e central, além de alterações de várias funções nervosas superiores, em trabalhadores profissionalmente expostos ao chumbo que apresentam indicadores de efeito biológico e indicadores de exposição inferiores aos limites estabelecidos pela legislação brasileira.This article reviews studies performed since 1975 on the occurrence of central and peripheral neurological manifestations in low-level lead exposure. The review shows that in many workers exposed to lead who present indications of both biological effects and exposure below the limits established by the Brazilian laws, abnormalities are found in peripheral nerve conduction velocity and also in several central nervous system functions. The study thus suggests that the threshold values used in Brazil to confirm lead poisoning should be revised.

  3. Computational analysis of thresholds for magnetophosphenes

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Hirata, Akimasa

    2012-01-01

    In international guidelines, basic restriction limits on the exposure of humans to low-frequency magnetic and electric fields are set with the objective of preventing the generation of phosphenes, visual sensations of flashing light not caused by light. Measured data on magnetophosphenes, i.e. phosphenes caused by a magnetically induced electric field on the retina, are available from volunteer studies. However, there is no simple way for determining the retinal threshold electric field or current density from the measured threshold magnetic flux density. In this study, the experimental field configuration of a previous study, in which phosphenes were generated in volunteers by exposing their heads to a magnetic field between the poles of an electromagnet, is computationally reproduced. The finite-element method is used for determining the induced electric field and current in five different MRI-based anatomical models of the head. The direction of the induced current density on the retina is dominantly radial to the eyeball, and the maximum induced current density is observed at the superior and inferior sides of the retina, which agrees with literature data on the location of magnetophosphenes at the periphery of the visual field. On the basis of computed data, the macroscopic retinal threshold current density for phosphenes at 20 Hz can be estimated as 10 mA m −2 (−20% to  + 30%, depending on the anatomical model); this current density corresponds to an induced eddy current of 14 μA (−20% to  + 10%), and about 20% of this eddy current flows through each eye. The ICNIRP basic restriction limit for the induced electric field in the case of occupational exposure is not exceeded until the magnetic flux density is about two to three times the measured threshold for magnetophosphenes, so the basic restriction limit does not seem to be conservative. However, the reasons for the non-conservativeness are purely technical: removal of the highest 1% of

  4. Thermotactile perception thresholds measurement conditions.

    Science.gov (United States)

    Maeda, Setsuo; Sakakibara, Hisataka

    2002-10-01

    The purpose of this paper is to investigate the effects of posture, push force and rate of temperature change on thermotactile thresholds and to clarify suitable measuring conditions for Japanese people. Thermotactile (warm and cold) thresholds on the right middle finger were measured with an HVLab thermal aesthesiometer. Subjects were eight healthy male Japanese students. The effects of posture in measurement were examined in the posture of a straight hand and forearm placed on a support, the same posture without a support, and the fingers and hand flexed at the wrist with the elbow placed on a desk. The finger push force applied to the applicator of the thermal aesthesiometer was controlled at a 0.5, 1.0, 2.0 and 3.0 N. The applicator temperature was changed to 0.5, 1.0, 1.5, 2.0 and 2.5 degrees C/s. After each measurement, subjects were asked about comfort under the measuring conditions. Three series of experiments were conducted on different days to evaluate repeatability. Repeated measures ANOVA showed that warm thresholds were affected by the push force and the rate of temperature change and that cold thresholds were influenced by posture and push force. The comfort assessment indicated that the measurement posture of a straight hand and forearm laid on a support was the most comfortable for the subjects. Relatively high repeatability was obtained under measurement conditions of a 1 degrees C/s temperature change rate and a 0.5 N push force. Measurement posture, push force and rate of temperature change can affect the thermal threshold. Judging from the repeatability, a push force of 0.5 N and a temperature change of 1.0 degrees C/s in the posture with the straight hand and forearm laid on a support are recommended for warm and cold threshold measurements.

  5. DOE approach to threshold quantities

    International Nuclear Information System (INIS)

    Wickham, L.E.; Kluk, A.F.; Department of Energy, Washington, DC)

    1985-01-01

    The Department of Energy (DOE) is developing the concept of threshold quantities for use in determining which waste materials must be handled as radioactive waste and which may be disposed of as nonradioactive waste at its sites. Waste above this concentration level would be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. Ideally, the threshold must be set high enough to significantly reduce the amount of waste requiring special handling. It must also be low enough so that waste at the threshold quantity poses a very small health risk and multiple exposures to such waste would still constitute a small health risk. It should also be practical to segregate waste above or below the threshold quantity using available instrumentation. Guidance is being prepared to aid DOE sites in establishing threshold quantity values based on pathways analysis using site-specific parameters (waste stream characteristics, maximum exposed individual, population considerations, and site specific parameters such as rainfall, etc.). A guidance dose of between 0.001 to 1.0 mSv/y (0.1 to 100 mrem/y) was recommended with 0.3 mSv/y (30 mrem/y) selected as the guidance dose upon which to base calculations. Several tasks were identified, beginning with the selection of a suitable pathway model for relating dose to the concentration of radioactivity in the waste. Threshold concentrations corresponding to the guidance dose were determined for waste disposal sites at a selected humid and arid site. Finally, cost-benefit considerations at the example sites were addressed. The results of the various tasks are summarized and the relationship of this effort with related developments at other agencies discussed

  6. A threshold for dissipative fission

    International Nuclear Information System (INIS)

    Thoennessen, M.; Bertsch, G.F.

    1993-01-01

    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 γ-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 thresh to the (temperature-dependent) fission barrier height E Bar (T). The statistical model reproduces the data for T thresh /E Bar (T) thresh /E Bar (T) independent of mass and fissility of the systems

  7. Thresholds in chemical respiratory sensitisation.

    Science.gov (United States)

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

    2015-07-03

    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

  8. Optimization Problems on Threshold Graphs

    Directory of Open Access Journals (Sweden)

    Elena Nechita

    2010-06-01

    Full Text Available During the last three decades, different types of decompositions have been processed in the field of graph theory. Among these we mention: decompositions based on the additivity of some characteristics of the graph, decompositions where the adjacency law between the subsets of the partition is known, decompositions where the subgraph induced by every subset of the partition must have predeterminate properties, as well as combinations of such decompositions. In this paper we characterize threshold graphs using the weakly decomposition, determine: density and stability number, Wiener index and Wiener polynomial for threshold graphs.

  9. Threshold current for fireball generation

    Science.gov (United States)

    Dijkhuis, Geert C.

    1982-05-01

    Fireball generation from a high-intensity circuit breaker arc is interpreted here as a quantum-mechanical phenomenon caused by severe cooling of electrode material evaporating from contact surfaces. According to the proposed mechanism, quantum effects appear in the arc plasma when the radius of one magnetic flux quantum inside solid electrode material has shrunk to one London penetration length. A formula derived for the threshold discharge current preceding fireball generation is found compatible with data reported by Silberg. This formula predicts linear scaling of the threshold current with the circuit breaker's electrode radius and concentration of conduction electrons.

  10. Nuclear threshold effects and neutron strength function

    International Nuclear Information System (INIS)

    Hategan, Cornel; Comisel, Horia

    2003-01-01

    One proves that a Nuclear Threshold Effect is dependent, via Neutron Strength Function, on Spectroscopy of Ancestral Neutron Threshold State. The magnitude of the Nuclear Threshold Effect is proportional to the Neutron Strength Function. Evidence for relation of Nuclear Threshold Effects to Neutron Strength Functions is obtained from Isotopic Threshold Effect and Deuteron Stripping Threshold Anomaly. The empirical and computational analysis of the Isotopic Threshold Effect and of the Deuteron Stripping Threshold Anomaly demonstrate their close relationship to Neutron Strength Functions. It was established that the Nuclear Threshold Effects depend, in addition to genuine Nuclear Reaction Mechanisms, on Spectroscopy of (Ancestral) Neutron Threshold State. The magnitude of the effect is proportional to the Neutron Strength Function, in their dependence on mass number. This result constitutes also a proof that the origins of these threshold effects are Neutron Single Particle States at zero energy. (author)

  11. Precipitation Thresholds for Triggering Floods in the Corgo Basin, Portugal

    Directory of Open Access Journals (Sweden)

    Mónica Santos

    2016-08-01

    Full Text Available Thresholds based on critical combinations of amount/duration of precipitation and flood events were estimated for the Corgo hydrographic basin, in northern Portugal. Thirty-one flood events in the Corgo basin were identified between 1865 and 2011 from a database of hydrometeorological disasters in Portugal. The minimum, maximum, and pre-warning thresholds that define the boundaries for flood occurrence were determined. The results show that the ratio between the total number of floods and precipitation events exceeding the minimum threshold denotes a relatively low probability of successful forecasting. This result may be due to the reduced number of flooding events in the floods database, which only include floods that caused damage as reported by the media. The estimated maximum threshold is not adequate for use in floods, since the majority of true positives are below this limit. However, and more interestingly, the retrospective verification of the estimated thresholds suggests that the minimum and pre-warning thresholds are well adjusted. Therefore, the application of these precipitation thresholds may contribute to minimize possible situations of pre-crisis or immediate crisis by reducing the flood consequences and the resources involved in emergency response to flood events.

  12. A practical threshold concept for simple and reasonable radiation protection

    International Nuclear Information System (INIS)

    Kaneko, Masahito

    2002-01-01

    A half century ago it was assumed for the purpose of protection that radiation risks are linearly proportional at all levels of dose. Linear No-Threshold (LNT) hypothesis has greatly contributed to the minimization of doses received by workers and members of the public, while it has brought about 'radiophobia' and unnecessary over-regulation. Now that the existence of bio-defensive mechanisms such as DNA repair, apoptosis and adaptive response are well recognized, the linearity assumption can be said 'unscientific'. Evidences increasingly imply that there are threshold effects in risk of radiation. A concept of 'practical' thresholds is proposed and the classification of 'stochastic' and 'deterministic' radiation effects should be abandoned. 'Practical' thresholds are dose levels below which induction of detectable radiogenic cancers or hereditary effects are not expected. There seems to be no evidence of deleterious health effects from radiation exposures at the current dose limits (50 mSv/y for workers and 5 mSv/y for members of the public), which have been adopted worldwide in the latter half of the 20th century. Those limits are assumed to have been set below certain 'practical' thresholds. As any workers and members of the public do not gain benefits from being exposed, excepting intentional irradiation for medical purposes, their radiation exposures should be kept below 'practical' thresholds. There is no use of 'justification' and 'optimization' (ALARA) principles, because there are no 'radiation detriments' as far as exposures are maintained below 'practical' thresholds. Accordingly the ethical issue of 'justification' to allow benefit to society to offset radiation detriments to individuals can be resolved. And also the ethical issue of 'optimization' to exchange health or safety for economical gain can be resolved. The ALARA principle should be applied to the probability (risk) of exceeding relevant dose limits instead of applying to normal exposures

  13. Percolation Threshold Parameters of Fluids

    Czech Academy of Sciences Publication Activity Database

    Škvor, J.; Nezbeda, Ivo

    2009-01-01

    Roč. 79, č. 4 (2009), 041141-041147 ISSN 1539-3755 Institutional research plan: CEZ:AV0Z40720504 Keywords : percolation threshold * universality * infinite cluster Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.400, year: 2009

  14. Threshold analyses and Lorentz violation

    International Nuclear Information System (INIS)

    Lehnert, Ralf

    2003-01-01

    In the context of threshold investigations of Lorentz violation, we discuss the fundamental principle of coordinate independence, the role of an effective dynamical framework, and the conditions of positivity and causality. Our analysis excludes a variety of previously considered Lorentz-breaking parameters and opens an avenue for viable dispersion-relation investigations of Lorentz violation

  15. Threshold enhancement of diphoton resonances

    Directory of Open Access Journals (Sweden)

    Aoife Bharucha

    2016-10-01

    Full Text Available We revisit a mechanism to enhance the decay width of (pseudo-scalar resonances to photon pairs when the process is mediated by loops of charged fermions produced near threshold. Motivated by the recent LHC data, indicating the presence of an excess in the diphoton spectrum at approximately 750 GeV, we illustrate this threshold enhancement mechanism in the case of a 750 GeV pseudoscalar boson A with a two-photon decay mediated by a charged and uncolored fermion having a mass at the 12MA threshold and a small decay width, <1 MeV. The implications of such a threshold enhancement are discussed in two explicit scenarios: i the Minimal Supersymmetric Standard Model in which the A state is produced via the top quark mediated gluon fusion process and decays into photons predominantly through loops of charginos with masses close to 12MA and ii a two Higgs doublet model in which A is again produced by gluon fusion but decays into photons through loops of vector-like charged heavy leptons. In both these scenarios, while the mass of the charged fermion has to be adjusted to be extremely close to half of the A resonance mass, the small total widths are naturally obtained if only suppressed three-body decay channels occur. Finally, the implications of some of these scenarios for dark matter are discussed.

  16. Threshold disorder as a source of diverse and complex behavior in random nets

    DEFF Research Database (Denmark)

    McGuire, P.C.; Bohr, Henrik; Clark, J.W.

    2002-01-01

    We study the diversity of complex spatio-temporal patterns in the behavior of random synchronous asymmetric neural networks (RSANNs). Special attention is given to the impact of disordered threshold values on limit-cycle diversity and limit-cycle complexity in RSANNs which have 'normal' thresholds...... systems. In order to reach beyond this seemingly disabling 'stable and small' aspect of the limit-cycle repertoire of RSANNs, we have found that if an RSANN has threshold disorder above a critical level, then there is a rapid increase of the size of the repertoire of patterns. The repertoire size...... initially follows a power-law function of the magnitude of the threshold disorder. As the disorder increases further, the limit-cycle patterns themselves become simpler until at a second critical level most of the limit cycles become simple fixed points. Nonetheless, for moderate changes in the threshold...

  17. The issue of threshold states

    International Nuclear Information System (INIS)

    Luck, L.

    1994-01-01

    The states which have not joined the Non-proliferation Treaty nor have undertaken any other internationally binding commitment not to develop or otherwise acquire nuclear weapons are considered a threshold states. Their nuclear status is rendered opaque as a conscious policy. Nuclear threshold status remains a key disarmament issue. For those few states, as India, Pakistan, Israel, who have put themselves in this position, the security returns have been transitory and largely illusory. The cost to them, and to the international community committed to the norm of non-proliferation, has been huge. The decisions which could lead to recovery from the situation in which they find themselves are essentially at their own hands. Whatever assistance the rest of international community is able to extend, it will need to be accompanied by a vital political signal

  18. Multiscalar production amplitudes beyond threshold

    CERN Document Server

    Argyres, E N; Kleiss, R H

    1993-01-01

    We present exact tree-order amplitudes for $H^* \\to n~H$, for final states containing one or two particles with non-zero three-momentum, for various interaction potentials. We show that there are potentials leading to tree amplitudes that satisfy unitarity, not only at threshold but also in the above kinematical configurations and probably beyond. As a by-product, we also calculate $2\\to n$ tree amplitudes at threshold and show that for the unbroken $\\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they vanish for $n\\ge 3~$ and for a model potential, respecting tree-order unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of the one-loop $1\\to n$ amplitude in both symmetric and spontaneously broken $\\phi^4$ theory.

  19. Realistic Realizations Of Threshold Circuits

    Science.gov (United States)

    Razavi, Hassan M.

    1987-08-01

    Threshold logic, in which each input is weighted, has many theoretical advantages over the standard gate realization, such as reducing the number of gates, interconnections, and power dissipation. However, because of the difficult synthesis procedure and complicated circuit implementation, their use in the design of digital systems is almost nonexistant. In this study, three methods of NMOS realizations are discussed, and their advantages and shortcomings are explored. Also, the possibility of using the methods to realize multi-valued logic is examined.

  20. Root finding with threshold circuits

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil

    2012-01-01

    Roč. 462, Nov 30 (2012), s. 59-69 ISSN 0304-3975 R&D Projects: GA AV ČR IAA100190902; GA MŠk(CZ) 1M0545 Institutional support: RVO:67985840 Keywords : root finding * threshold circuit * power series Subject RIV: BA - General Mathematics Impact factor: 0.489, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304397512008006#

  1. Design proposal for door thresholds

    Directory of Open Access Journals (Sweden)

    Smolka Radim

    2017-01-01

    Full Text Available Panels for openings in structures have always been an essential and integral part of buildings. Their importance in terms of a building´s functionality was not recognised. However, the general view on this issue has changed from focusing on big planar segments and critical details to sub-elements of these structures. This does not only focus on the forms of connecting joints but also on the supporting systems that keep the panels in the right position and ensure they function properly. One of the most strained segments is the threshold structure, especially the entrance door threshold structure. It is the part where substantial defects in construction occur in terms of waterproofing, as well as in the static, thermal and technical functions thereof. In conventional buildings, this problem is solved by pulling the floor structure under the entrance door structure and subsequently covering it with waterproofing material. This system cannot work effectively over the long term so local defects occur. A proposal is put forward to solve this problem by installing a sub-threshold door coupler made of composite materials. The coupler is designed so that its variability complies with the required parameters for most door structures on the European market.

  2. Color difference thresholds in dentistry.

    Science.gov (United States)

    Paravina, Rade D; Ghinea, Razvan; Herrera, Luis J; Bona, Alvaro D; Igiel, Christopher; Linninger, Mercedes; Sakai, Maiko; Takahashi, Hidekazu; Tashkandi, Esam; Perez, Maria del Mar

    2015-01-01

    The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. The CIELAB 50:50% PT was ΔEab  = 1.2, whereas 50:50% AT was ΔEab  = 2.7. Corresponding CIEDE2000 (ΔE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas ΔE00 /ΔEab . Observer groups and sites showed high level of statistical difference in all thresholds. Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and

  3. Bedding material affects mechanical thresholds, heat thresholds and texture preference

    Science.gov (United States)

    Moehring, Francie; O’Hara, Crystal L.; Stucky, Cheryl L.

    2015-01-01

    It has long been known that the bedding type animals are housed on can affect breeding behavior and cage environment. Yet little is known about its effects on evoked behavior responses or non-reflexive behaviors. C57BL/6 mice were housed for two weeks on one of five bedding types: Aspen Sani Chips® (standard bedding for our institute), ALPHA-Dri®, Cellu-Dri™, Pure-o’Cel™ or TEK-Fresh. Mice housed on Aspen exhibited the lowest (most sensitive) mechanical thresholds while those on TEK-Fresh exhibited 3-fold higher thresholds. While bedding type had no effect on responses to punctate or dynamic light touch stimuli, TEK-Fresh housed animals exhibited greater responsiveness in a noxious needle assay, than those housed on the other bedding types. Heat sensitivity was also affected by bedding as animals housed on Aspen exhibited the shortest (most sensitive) latencies to withdrawal whereas those housed on TEK-Fresh had the longest (least sensitive) latencies to response. Slight differences between bedding types were also seen in a moderate cold temperature preference assay. A modified tactile conditioned place preference chamber assay revealed that animals preferred TEK-Fresh to Aspen bedding. Bedding type had no effect in a non-reflexive wheel running assay. In both acute (two day) and chronic (5 week) inflammation induced by injection of Complete Freund’s Adjuvant in the hindpaw, mechanical thresholds were reduced in all groups regardless of bedding type, but TEK-Fresh and Pure-o’Cel™ groups exhibited a greater dynamic range between controls and inflamed cohorts than Aspen housed mice. PMID:26456764

  4. Regional rainfall thresholds for landslide occurrence using a centenary database

    Science.gov (United States)

    Vaz, Teresa; Luís Zêzere, José; Pereira, Susana; Cruz Oliveira, Sérgio; Quaresma, Ivânia

    2017-04-01

    Rainfall is one of the most important triggering factors for landslides occurrence worldwide. The relation between rainfall and landslide occurrence is complex and some approaches have been focus on the rainfall thresholds identification, i.e., rainfall critical values that when exceeded can initiate landslide activity. In line with these approaches, this work proposes and validates rainfall thresholds for the Lisbon region (Portugal), using a centenary landslide database associated with a centenary daily rainfall database. The main objectives of the work are the following: i) to compute antecedent rainfall thresholds using linear and potential regression; ii) to define lower limit and upper limit rainfall thresholds; iii) to estimate the probability of critical rainfall conditions associated with landslide events; and iv) to assess the thresholds performance using receiver operating characteristic (ROC) metrics. In this study we consider the DISASTER database, which lists landslides that caused fatalities, injuries, missing people, evacuated and homeless people occurred in Portugal from 1865 to 2010. The DISASTER database was carried out exploring several Portuguese daily and weekly newspapers. Using the same newspaper sources, the DISASTER database was recently updated to include also the landslides that did not caused any human damage, which were also considered for this study. The daily rainfall data were collected at the Lisboa-Geofísico meteorological station. This station was selected considering the quality and completeness of the rainfall data, with records that started in 1864. The methodology adopted included the computation, for each landslide event, of the cumulative antecedent rainfall for different durations (1 to 90 consecutive days). In a second step, for each combination of rainfall quantity-duration, the return period was estimated using the Gumbel probability distribution. The pair (quantity-duration) with the highest return period was

  5. Colour thresholding and objective quantification in bioimaging

    Science.gov (United States)

    Fermin, C. D.; Gerber, M. A.; Torre-Bueno, J. R.

    1992-01-01

    Computer imaging is rapidly becoming an indispensable tool for the quantification of variables in research and medicine. Whilst its use in medicine has largely been limited to qualitative observations, imaging in applied basic sciences, medical research and biotechnology demands objective quantification of the variables in question. In black and white densitometry (0-256 levels of intensity) the separation of subtle differences between closely related hues from stains is sometimes very difficult. True-colour and real-time video microscopy analysis offer choices not previously available with monochrome systems. In this paper we demonstrate the usefulness of colour thresholding, which has so far proven indispensable for proper objective quantification of the products of histochemical reactions and/or subtle differences in tissue and cells. In addition, we provide interested, but untrained readers with basic information that may assist decisions regarding the most suitable set-up for a project under consideration. Data from projects in progress at Tulane are shown to illustrate the advantage of colour thresholding over monochrome densitometry and for objective quantification of subtle colour differences between experimental and control samples.

  6. Ecosystem thresholds, tipping points, and critical transitions

    Science.gov (United States)

    Munson, Seth M.; Reed, Sasha C.; Peñuelas, Josep; McDowell, Nathan G.; Sala, Osvaldo E.

    2018-01-01

    Abrupt shifts in ecosystems are cause for concern and will likelyintensify under global change (Scheffer et al., 2001). The terms‘thresho lds’, ‘tipping points’, and ‘critical transitions’ have beenused interchangeably to refer to sudden changes in the integrityor state of an ecosystem caused by environmental drivers(Holling, 1973; May, 1977). Threshold-based concepts havesignific antly aided our capacity to predict the controls overecosystem structure and functioning (Schwinning et al., 2004;Peters et al., 2007) and have become a framework to guide themanagement of natural resources (Glick et al., 2010; Allen et al.,2011). However, our unders tanding of how biotic and abioticdrivers interact to regulate ecosystem responses and of ways toforecast th e impending responses remain limited. Terrestrialecosystems, in particular, are already responding to globalchange in ways that are both transformati onal and difficult topredict due to strong heterogeneity across temporal and spatialscales (Pe~nuelas & Filella, 2001; McDowell et al., 2011;Munson, 2013; Reed et al., 2016). Comparing approaches formeasuring ecosystem performance in response to changingenvironme ntal conditions and for detecting stress and thresholdresponses can improve tradition al tests of resilience and provideearly warning signs of ecosystem transitions. Similarly, com-paring responses across ecosystems can offer insight into themechanisms that underlie variation in threshold responses.

  7. Compressively sampled MR image reconstruction using generalized thresholding iterative algorithm

    Science.gov (United States)

    Elahi, Sana; kaleem, Muhammad; Omer, Hammad

    2018-01-01

    Compressed sensing (CS) is an emerging area of interest in Magnetic Resonance Imaging (MRI). CS is used for the reconstruction of the images from a very limited number of samples in k-space. This significantly reduces the MRI data acquisition time. One important requirement for signal recovery in CS is the use of an appropriate non-linear reconstruction algorithm. It is a challenging task to choose a reconstruction algorithm that would accurately reconstruct the MR images from the under-sampled k-space data. Various algorithms have been used to solve the system of non-linear equations for better image quality and reconstruction speed in CS. In the recent past, iterative soft thresholding algorithm (ISTA) has been introduced in CS-MRI. This algorithm directly cancels the incoherent artifacts produced because of the undersampling in k -space. This paper introduces an improved iterative algorithm based on p -thresholding technique for CS-MRI image reconstruction. The use of p -thresholding function promotes sparsity in the image which is a key factor for CS based image reconstruction. The p -thresholding based iterative algorithm is a modification of ISTA, and minimizes non-convex functions. It has been shown that the proposed p -thresholding iterative algorithm can be used effectively to recover fully sampled image from the under-sampled data in MRI. The performance of the proposed method is verified using simulated and actual MRI data taken at St. Mary's Hospital, London. The quality of the reconstructed images is measured in terms of peak signal-to-noise ratio (PSNR), artifact power (AP), and structural similarity index measure (SSIM). The proposed approach shows improved performance when compared to other iterative algorithms based on log thresholding, soft thresholding and hard thresholding techniques at different reduction factors.

  8. Alternative method for determining anaerobic threshold in rowers

    Directory of Open Access Journals (Sweden)

    Giovani Dos Santos Cunha

    2008-01-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2008v10n4p367 In rowing, the standard breathing that athletes are trained to use makes it difficult, or even impossible, to detect ventilatory limits, due to the coupling of the breath with the technical movement. For this reason, some authors have proposed determining the anaerobic threshold from the respiratory exchange ratio (RER, but there is not yet consensus on what value of RER should be used. The objective of this study was to test what value of RER corresponds to the anaerobic threshold and whether this value can be used as an independent parameter for determining the anaerobic threshold of rowers. The sample comprised 23 male rowers. They were submitted to a maximal cardiorespiratory test on a rowing ergometer with concurrent ergospirometry in order to determine VO2máx and the physiological variables corresponding to their anaerobic threshold. The anaerobic threshold was determined using the Dmax (maximal distance method. The physiological variables were classified into maximum values and anaerobic threshold values. The maximal state of these rowers reached VO2 (58.2±4.4 ml.kg-1.min-1, lactate (8.2±2.1 mmol.L-1, power (384±54.3 W and RER (1.26±0.1. At the anaerobic threshold they reached VO2 (46.9±7.5 ml.kg-1.min-1, lactate (4.6±1.3 mmol.L-1, power (300± 37.8 W and RER (0.99±0.1. Conclusions - the RER can be used as an independent method for determining the anaerobic threshold of rowers, adopting a value of 0.99, however, RER should exhibit a non-linear increase above this figure.

  9. Thresholds for Coral Bleaching: Are Synergistic Factors and Shifting Thresholds Changing the Landscape for Management? (Invited)

    Science.gov (United States)

    Eakin, C.; Donner, S. D.; Logan, C. A.; Gledhill, D. K.; Liu, G.; Heron, S. F.; Christensen, T.; Rauenzahn, J.; Morgan, J.; Parker, B. A.; Hoegh-Guldberg, O.; Skirving, W. J.; Strong, A. E.

    2010-12-01

    As carbon dioxide rises in the atmosphere, climate change and ocean acidification are modifying important physical and chemical parameters in the oceans with resulting impacts on coral reef ecosystems. Rising CO2 is warming the world’s oceans and causing corals to bleach, with both alarming frequency and severity. The frequent return of stressful temperatures has already resulted in major damage to many of the world’s coral reefs and is expected to continue in the foreseeable future. Warmer oceans also have contributed to a rise in coral infectious diseases. Both bleaching and infectious disease can result in coral mortality and threaten one of the most diverse ecosystems on Earth and the important ecosystem services they provide. Additionally, ocean acidification from rising CO2 is reducing the availability of carbonate ions needed by corals to build their skeletons and perhaps depressing the threshold for bleaching. While thresholds vary among species and locations, it is clear that corals around the world are already experiencing anomalous temperatures that are too high, too often, and that warming is exceeding the rate at which corals can adapt. This is despite a complex adaptive capacity that involves both the coral host and the zooxanthellae, including changes in the relative abundance of the latter in their coral hosts. The safe upper limit for atmospheric CO2 is probably somewhere below 350ppm, a level we passed decades ago, and for temperature is a sustained global temperature increase of less than 1.5°C above pre-industrial levels. How much can corals acclimate and/or adapt to the unprecedented fast changing environmental conditions? Any change in the threshold for coral bleaching as the result of acclimation and/or adaption may help corals to survive in the future but adaptation to one stress may be maladaptive to another. There also is evidence that ocean acidification and nutrient enrichment modify this threshold. What do shifting thresholds mean

  10. 11 CFR 9036.1 - Threshold submission.

    Science.gov (United States)

    2010-01-01

    ... credit or debit card, including one made over the Internet, the candidate shall provide sufficient... section shall not count toward the threshold amount. (c) Threshold certification by Commission. (1) After...

  11. THRESHOLD OF SIGNIFICANCE IN STRESS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Elena RUSE

    2015-12-01

    Full Text Available Stress management is the individual's ability to handle any situation, external conditions, to match the demands of the external environment. The researchers revealed several stages in the stress response. A first phase was called ‘‘alert reaction'' or ‘‘immediate reaction to stress‘‘, phase in which there are physiological modifications and manifestations that occur under psychological aspect. Adaptation phase is the phase in which the reactions from the first phase diminishes or disappears. Exhaustion phase is related to the diversity of stress factors and time and may exceed the resources of the human body to adapt. Influencing factors may be: limited, cognitive, perceptual, and a priori. But there is a threshold of significance in stress management. Once the reaction to external stimuli occurs, awareness is needed. The capability effect occurs, any side effect goes away and comes out the ''I AM'' effect.

  12. Nuclear thermodynamics below particle threshold

    International Nuclear Information System (INIS)

    Schiller, A.; Agvaanluvsan, U.; Algin, E.; Bagheri, A.; Chankova, R.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Voinov, A.

    2005-01-01

    From a starting point of experimentally measured nuclear level densities, we discuss thermodynamical properties of nuclei below the particle emission threshold. Since nuclei are essentially mesoscopic systems, a straightforward generalization of macroscopic ensemble theory often yields unphysical results. A careful critique of traditional thermodynamical concepts reveals problems commonly encountered in mesoscopic systems. One of which is the fact that microcanonical and canonical ensemble theory yield different results, another concerns the introduction of temperature for small, closed systems. Finally, the concept of phase transitions is investigated for mesoscopic systems

  13. Compositional threshold for Nuclear Waste Glass Durability

    International Nuclear Information System (INIS)

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

    2013-01-01

    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

  14. Threshold Concepts in Finance: Student Perspectives

    Science.gov (United States)

    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…

  15. Threshold condition for nonlinear tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Zabiego, M.F.; Callen, J.D.

    1996-03-01

    Low-mode-number tearing, mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. The models can be compared with the available data and/or serve as a basis for planning some experiments in order to either test theory (by means of beta-limit scaling laws, as proposed in this paper) or attempt to control undesirable tearing modes. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space

  16. Epidemic threshold in directed networks

    Science.gov (United States)

    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.

  17. Computational gestalts and perception thresholds.

    Science.gov (United States)

    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.

  18. Threshold enhancement of diphoton resonances

    CERN Document Server

    Bharucha, Aoife; Goudelis, Andreas

    2016-10-10

    The data collected by the LHC collaborations at an energy of 13 TeV indicates the presence of an excess in the diphoton spectrum that would correspond to a resonance of a 750 GeV mass. The apparently large production cross section is nevertheless very difficult to explain in minimal models. We consider the possibility that the resonance is a pseudoscalar boson $A$ with a two--photon decay mediated by a charged and uncolored fermion having a mass at the $\\frac12 M_A$ threshold and a very small decay width, $\\ll 1$ MeV; one can then generate a large enhancement of the $A\\gamma\\gamma$ amplitude which explains the excess without invoking a large multiplicity of particles propagating in the loop, large electric charges and/or very strong Yukawa couplings. The implications of such a threshold enhancement are discussed in two explicit scenarios: i) the Minimal Supersymmetric Standard Model in which the $A$ state is produced via the top quark mediated gluon fusion process and decays into photons predominantly through...

  19. Combined threshold and transverse momentum resummation for inclusive observables

    International Nuclear Information System (INIS)

    Muselli, Claudio; Forte, Stefano; Ridolfi, Giovanni

    2017-01-01

    We present a combined resummation for the transverse momentum distribution of a colorless final state in perturbative QCD, expressed as a function of transverse momentum p T and the scaling variable x. Its expression satisfies three requirements: it reduces to standard transverse momentum resummation to any desired logarithmic order in the limit p T →0 for fixed x, up to power suppressed corrections in p T ; it reduces to threshold resummation to any desired logarithmic order in the limit x→1 for fixed p T , up to power suppressed correction in 1−x; upon integration over transverse momentum it reproduces the resummation of the total cross cross at any given logarithmic order in the threshold x→1 limit, up to power suppressed correction in 1−x. Its main ingredient, and our main new result, is a modified form of transverse momentum resummation, which leads to threshold resummation upon integration over p T , and for which we provide a simple closed-form analytic expression in Fourier-Mellin (b,N) space. We give explicit coefficients up to NNLL order for the specific case of Higgs production in gluon fusion in the effective field theory limit. Our result allows for a systematic improvement of the transverse momentum distribution through threshold resummation which holds for all p T , and elucidates the relation between transverse momentum resummation and threshold resummation at the inclusive level, specifically by providing within perturbative QCD a simple derivation of the main consequence of the so-called collinear anomaly of SCET.

  20. Combined threshold and transverse momentum resummation for inclusive observables

    Energy Technology Data Exchange (ETDEWEB)

    Muselli, Claudio; Forte, Stefano [Tif Lab, Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano,Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova,Via Dodecaneso 33, I-16146 Genova (Italy)

    2017-03-21

    We present a combined resummation for the transverse momentum distribution of a colorless final state in perturbative QCD, expressed as a function of transverse momentum p{sub T} and the scaling variable x. Its expression satisfies three requirements: it reduces to standard transverse momentum resummation to any desired logarithmic order in the limit p{sub T}→0 for fixed x, up to power suppressed corrections in p{sub T}; it reduces to threshold resummation to any desired logarithmic order in the limit x→1 for fixed p{sub T}, up to power suppressed correction in 1−x; upon integration over transverse momentum it reproduces the resummation of the total cross cross at any given logarithmic order in the threshold x→1 limit, up to power suppressed correction in 1−x. Its main ingredient, and our main new result, is a modified form of transverse momentum resummation, which leads to threshold resummation upon integration over p{sub T}, and for which we provide a simple closed-form analytic expression in Fourier-Mellin (b,N) space. We give explicit coefficients up to NNLL order for the specific case of Higgs production in gluon fusion in the effective field theory limit. Our result allows for a systematic improvement of the transverse momentum distribution through threshold resummation which holds for all p{sub T}, and elucidates the relation between transverse momentum resummation and threshold resummation at the inclusive level, specifically by providing within perturbative QCD a simple derivation of the main consequence of the so-called collinear anomaly of SCET.

  1. Setting conservation management thresholds using a novel participatory modeling approach.

    Science.gov (United States)

    Addison, P F E; de Bie, K; Rumpff, L

    2015-10-01

    We devised a participatory modeling approach for setting management thresholds that show when management intervention is required to address undesirable ecosystem changes. This approach was designed to be used when management thresholds: must be set for environmental indicators in the face of multiple competing objectives; need to incorporate scientific understanding and value judgments; and will be set by participants with limited modeling experience. We applied our approach to a case study where management thresholds were set for a mat-forming brown alga, Hormosira banksii, in a protected area management context. Participants, including management staff and scientists, were involved in a workshop to test the approach, and set management thresholds to address the threat of trampling by visitors to an intertidal rocky reef. The approach involved trading off the environmental objective, to maintain the condition of intertidal reef communities, with social and economic objectives to ensure management intervention was cost-effective. Ecological scenarios, developed using scenario planning, were a key feature that provided the foundation for where to set management thresholds. The scenarios developed represented declines in percent cover of H. banksii that may occur under increased threatening processes. Participants defined 4 discrete management alternatives to address the threat of trampling and estimated the effect of these alternatives on the objectives under each ecological scenario. A weighted additive model was used to aggregate participants' consequence estimates. Model outputs (decision scores) clearly expressed uncertainty, which can be considered by decision makers and used to inform where to set management thresholds. This approach encourages a proactive form of conservation, where management thresholds and associated actions are defined a priori for ecological indicators, rather than reacting to unexpected ecosystem changes in the future. © 2015 The

  2. The H-mode power threshold in JET

    Energy Technology Data Exchange (ETDEWEB)

    Start, D F.H.; Bhatnagar, V P; Campbell, D J; Cordey, J G; Esch, H P.L. de; Gormezano, C; Hawkes, N; Horton, L; Jones, T T.C.; Lomas, P J; Lowry, C; Righi, E; Rimini, F G; Saibene, G; Sartori, R; Sips, G; Stork, D; Thomas, P; Thomsen, K; Tubbing, B J.D.; Von Hellermann, M; Ward, D J [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    New H-mode threshold data over a range of toroidal field and density values have been obtained from the present campaign. The scaling with n{sub e} B{sub t} is almost identical with that of the 91/92 period for the same discharge conditions. The scaling with toroidal field alone gives somewhat higher thresholds than the older data. The 1991/2 database shows a scaling of P{sub th} (power threshold) with n{sub e} B{sub t} which is approximately linear and agrees well with that observed on other tokamaks. For NBI and carbon target tiles the threshold power is a factor of two higher with the ion {Nu}B drift away from the target compared with the value found with the drift towards the target. The combination of ICRH and beryllium tiles appears to be beneficial for reducing P{sub th}. The power threshold is largely insensitive to plasma current, X-point height and distance between the last closed flux surface and the limiter, at least for values greater than 2 cm. (authors). 3 refs., 6 figs.

  3. Determining cardiac vagal threshold from short term heart rate complexity

    Directory of Open Access Journals (Sweden)

    Hamdan Rami Abou

    2016-09-01

    Full Text Available Evaluating individual aerobic exercise capacity is fundamental in sports and exercise medicine but associated with organizational and instrumental effort. Here, we extract an index related to common performance markers, the aerobic and anaerobic thresholds enabling the estimation of exercise capacity from a conventional sports watch supporting beatwise heart rate tracking. Therefore, cardiac vagal threshold (CVT was determined in 19 male subjects performing an incremental maximum exercise test. CVT varied around the anaerobic threshold AnT with mean deviation of 7.9 ± 17.7 W. A high correspondence of the two thresholds was indicated by Bland-Altman plots with limits of agreement −27.5 W and 43.4 W. Additionally, CVT was strongly correlated AnT (rp = 0.86, p < 0.001 and reproduced this marker well (rc = 0.81. We conclude, that cardiac vagal threshold derived from compression entropy time course can be useful to assess physical fitness in an uncomplicated way.

  4. Dimensional threshold for fracture linkage and hooking

    Science.gov (United States)

    Lamarche, Juliette; Chabani, Arezki; Gauthier, Bertrand D. M.

    2018-03-01

    Fracture connectivity in rocks depends on spatial properties of the pattern including length, abundance and orientation. When fractures form a single-strike set, they hardly cross-cut each other and the connectivity is limited. Linkage probability increases with increasing fracture abundance and length as small fractures connect to each other to form longer ones. A process for parallel fracture linkage is the "hooking", where two converging fracture tips mutually deviate and then converge to connect due to the interaction of their crack-tip stresses. Quantifying the processes and conditions for fracture linkage in single-strike fracture sets is crucial to better predicting fluid flow in Naturally Fractured Reservoirs. For 1734 fractures in Permian shales of the Lodève Basin, SE France, we measured geometrical parameters in 2D, characterizing three stages of the hooking process: underlapping, overlapping and linkage. We deciphered the threshold values, shape ratios and limiting conditions to switch from one stage to another one. The hook set up depends on the spacing (S) and fracture length (Lh) with the relation S ≈ 0.15 Lh. Once the hooking is initiated, with the fracture deviation length (L) L ≈ 0.4 Lh, the fractures reaches the linkage stage only when the spacing is reduced to S ≈ 0.02 Lh and the convergence (C) is < 0.1 L. These conditions apply to multi-scale fractures with a shape ratio L/S = 10 and for fracture curvature of 10°-20°.

  5. Some threshold spectral problems of Schroedinger operators

    International Nuclear Information System (INIS)

    Jia, X.

    2009-01-01

    This Ph.D. thesis deals with some spectral problems of the Schroedinger operators. We first consider the semi-classical limit of the number of bound states of unique two-cluster N-body Schroedinger operator. Then we use Dirichlet-Neumann bracket to get semi-classical limit of Riesz means of the discrete eigenvalues of N-body Schroedinger operator. The effective potential of N-body Schroedinger operator with Coulomb potential is also considered and we find that the effective potential has critical decay at infinity. Thus, the Schroedinger operator with critical potential is studied in this thesis. We study the coupling constant threshold of Schroedinger operator with critical potential and the asymptotic expansion of resolvent of Schroedinger operator with critical potential. We use that expansion to study low-energy asymptotics of derivative of spectral shift function for perturbation with critical decay. After that, we use this result and the known result for high-energy asymptotic expansion of spectral shift function to obtain the Levinson theorem. (author)

  6. A Framework for Optimizing Phytosanitary Thresholds in Seed Systems.

    Science.gov (United States)

    Choudhury, Robin Alan; Garrett, Karen A; Klosterman, Steven J; Subbarao, Krishna V; McRoberts, Neil

    2017-10-01

    Seedborne pathogens and pests limit production in many agricultural systems. Quarantine programs help prevent the introduction of exotic pathogens into a country, but few regulations directly apply to reducing the reintroduction and spread of endemic pathogens. Use of phytosanitary thresholds helps limit the movement of pathogen inoculum through seed, but the costs associated with rejected seed lots can be prohibitive for voluntary implementation of phytosanitary thresholds. In this paper, we outline a framework to optimize thresholds for seedborne pathogens, balancing the cost of rejected seed lots and benefit of reduced inoculum levels. The method requires relatively small amounts of data, and the accuracy and robustness of the analysis improves over time as data accumulate from seed testing. We demonstrate the method first and illustrate it with a case study of seedborne oospores of Peronospora effusa, the causal agent of spinach downy mildew. A seed lot threshold of 0.23 oospores per seed could reduce the overall number of oospores entering the production system by 90% while removing 8% of seed lots destined for distribution. Alternative mitigation strategies may result in lower economic losses to seed producers, but have uncertain efficacy. We discuss future challenges and prospects for implementing this approach.

  7. Threshold behavior in electron-atom scattering

    International Nuclear Information System (INIS)

    Sadeghpour, H.R.; Greene, C.H.

    1996-01-01

    Ever since the classic work of Wannier in 1953, the process of treating two threshold electrons in the continuum of a positively charged ion has been an active field of study. The authors have developed a treatment motivated by the physics below the double ionization threshold. By modeling the double ionization as a series of Landau-Zener transitions, they obtain an analytical formulation of the absolute threshold probability which has a leading power law behavior, akin to Wannier's law. Some of the noteworthy aspects of this derivation are that the derivation can be conveniently continued below threshold giving rise to a open-quotes cuspclose quotes at threshold, and that on both sides of the threshold, absolute values of the cross sections are obtained

  8. A numerical study of threshold states

    International Nuclear Information System (INIS)

    Ata, M.S.; Grama, C.; Grama, N.; Hategan, C.

    1979-01-01

    There are some experimental evidences of charged particle threshold states. On the statistical background of levels, some simple structures were observed in excitation spectrum. They occur near the coulombian threshold and have a large reduced width for the decay in the threshold channel. These states were identified as charged cluster threshold states. Such threshold states were observed in sup(15,16,17,18)O, sup(18,19)F, sup(19,20)Ne, sup(24)Mg, sup(32)S. The types of clusters involved were d, t, 3 He, α and even 12 C. They were observed in heavy-ions transfer reactions in the residual nucleus as strong excited levels. The charged particle threshold states occur as simple structures at high excitation energy. They could be interesting both from nuclear structure as well as nuclear reaction mechanism point of view. They could be excited as simple structures both in compound and residual nucleus. (author)

  9. Iran: the next nuclear threshold state?

    OpenAIRE

    Maurer, Christopher L.

    2014-01-01

    Approved for public release; distribution is unlimited A nuclear threshold state is one that could quickly operationalize its peaceful nuclear program into one capable of producing a nuclear weapon. This thesis compares two known threshold states, Japan and Brazil, with Iran to determine if the Islamic Republic could also be labeled a threshold state. Furthermore, it highlights the implications such a status could have on U.S. nonproliferation policy. Although Iran's nuclear program is mir...

  10. Dynamical thresholds for complete fusion

    International Nuclear Information System (INIS)

    Davies, K.T.R.; Sierk, A.J.; Nix, J.R.

    1983-01-01

    It is our purpose here to study the effect of nuclear dissipation and shape parametrization on dynamical thresholds for compound-nucleus formation in symmetric heavy-ion reactions. This is done by solving numerically classical equations of motion for head-on collisions to determine whether the dynamical trajectory in a multidimensional deformation space passes inside the fission saddle point and forms a compound nucleus, or whether it passes outside the fission saddle point and reseparates in a fast-fission or deep-inelastic reaction. Specifying the nuclear shape in terms of smoothly joined portions of three quadratic surfaces of revolution, we take into account three symmetric deformation coordinates. However, in some cases we reduce the number of coordinates to two by requiring the ends of the fusing system to be spherical in shape. The nuclear potential energy of deformation is determined in terms of a Coulomb energy and a double volume energy of a Yukawa-plus-exponential folding function. The collective kinetic energy is calculated for incompressible, nearly irrotational flow by means of the Werner-Wheeler approximation. Four possibilities are studied for the transfer of collective kinetic energy into internal single-particle excitation energy: zero dissipation, ordinary two body viscosity, one-body wall-formula dissipation, and one-body wall-and-window dissipation

  11. Damage Threshold of In Vivo Rabbit Cornea by 2 micron Laser Irradiation

    National Research Council Canada - National Science Library

    Chen, Bo; Oliver, Jeffery; Dutta, Soumak; Rylander, III, Grady H; Thomsen, Sharon L; Welch, Ashley J

    2007-01-01

    To support refinement of the Maximum Permissible Exposure (MPE) safety limits, a series of experiments were conducted in vivo on Dutch Belted rabbit corneas to determine corneal minimum visible lesion thresholds...

  12. Log canonical thresholds of smooth Fano threefolds

    International Nuclear Information System (INIS)

    Cheltsov, Ivan A; Shramov, Konstantin A

    2008-01-01

    The complex singularity exponent is a local invariant of a holomorphic function determined by the integrability of fractional powers of the function. The log canonical thresholds of effective Q-divisors on normal algebraic varieties are algebraic counterparts of complex singularity exponents. For a Fano variety, these invariants have global analogues. In the former case, it is the so-called α-invariant of Tian; in the latter case, it is the global log canonical threshold of the Fano variety, which is the infimum of log canonical thresholds of all effective Q-divisors numerically equivalent to the anticanonical divisor. An appendix to this paper contains a proof that the global log canonical threshold of a smooth Fano variety coincides with its α-invariant of Tian. The purpose of the paper is to compute the global log canonical thresholds of smooth Fano threefolds (altogether, there are 105 deformation families of such threefolds). The global log canonical thresholds are computed for every smooth threefold in 64 deformation families, and the global log canonical thresholds are computed for a general threefold in 20 deformation families. Some bounds for the global log canonical thresholds are computed for 14 deformation families. Appendix A is due to J.-P. Demailly.

  13. Thresholding magnetic resonance images of human brain

    Institute of Scientific and Technical Information of China (English)

    Qing-mao HU; Wieslaw L NOWINSKI

    2005-01-01

    In this paper, methods are proposed and validated to determine low and high thresholds to segment out gray matter and white matter for MR images of different pulse sequences of human brain. First, a two-dimensional reference image is determined to represent the intensity characteristics of the original three-dimensional data. Then a region of interest of the reference image is determined where brain tissues are present. The non-supervised fuzzy c-means clustering is employed to determine: the threshold for obtaining head mask, the low threshold for T2-weighted and PD-weighted images, and the high threshold for T1-weighted, SPGR and FLAIR images. Supervised range-constrained thresholding is employed to determine the low threshold for T1-weighted, SPGR and FLAIR images. Thresholding based on pairs of boundary pixels is proposed to determine the high threshold for T2- and PD-weighted images. Quantification against public data sets with various noise and inhomogeneity levels shows that the proposed methods can yield segmentation robust to noise and intensity inhomogeneity. Qualitatively the proposed methods work well with real clinical data.

  14. Time-efficient multidimensional threshold tracking method

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Kowalewski, Borys; Dau, Torsten

    2015-01-01

    Traditionally, adaptive methods have been used to reduce the time it takes to estimate psychoacoustic thresholds. However, even with adaptive methods, there are many cases where the testing time is too long to be clinically feasible, particularly when estimating thresholds as a function of anothe...

  15. 40 CFR 68.115 - Threshold determination.

    Science.gov (United States)

    2010-07-01

    ... (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Regulated Substances for Accidental Release Prevention... process exceeds the threshold. (b) For the purposes of determining whether more than a threshold quantity... portion of the process is less than 10 millimeters of mercury (mm Hg), the amount of the substance in the...

  16. Applying Threshold Concepts to Finance Education

    Science.gov (United States)

    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…

  17. The effects of loading history on fatigue crack growth threshold

    International Nuclear Information System (INIS)

    Ogawa, Takeshi; Tokaji, Keiro; Ochi, Satoshi; Kobayashi, Hideo.

    1987-01-01

    The effects of loading history on threshold stress intensity range (ΔK th ) were investigated in a low alloy steel SFVQ1A (A508 - 3) and a low carbon steel S10C. A single overload and multiple overloads were chosen as loading history. Crack growth and crack closure following the loading histories were measured at load ratios of 0.05 and 0.70. Threshold values were determined as a fatigue limit of preloaded specimens. The ΔK th values increased with increasing overload stress intensity factor (K h ). For a given K h value, multiple overloads produced much larger increase in ΔK th than a single overload and threshold values expressed by maximum stress intensity factor (K max,th ) were almost constant, independent of stress ratio. The results obtained were discussed in terms of crack closure behaviour, and a method was proposed to evaluate the threshold value based on plasticity-induced crack closure. (author)

  18. Rapid Estimation of Gustatory Sensitivity Thresholds with SIAM and QUEST

    Directory of Open Access Journals (Sweden)

    Richard Höchenberger

    2017-06-01

    Full Text Available Adaptive methods provide quick and reliable estimates of sensory sensitivity. Yet, these procedures are typically developed for and applied to the non-chemical senses only, i.e., to vision, audition, and somatosensation. The relatively long inter-stimulus-intervals in gustatory studies, which are required to minimize adaptation and habituation, call for time-efficient threshold estimations. We therefore tested the suitability of two adaptive yes-no methods based on SIAM and QUEST for rapid estimation of taste sensitivity by comparing test-retest reliability for sucrose, citric acid, sodium chloride, and quinine hydrochloride thresholds. We show that taste thresholds can be obtained in a time efficient manner with both methods (within only 6.5 min on average using QUEST and ~9.5 min using SIAM. QUEST yielded higher test-retest correlations than SIAM in three of the four tastants. Either method allows for taste threshold estimation with low strain on participants, rendering them particularly advantageous for use in subjects with limited attentional or mnemonic capacities, and for time-constrained applications during cohort studies or in the testing of patients and children.

  19. Doctoral conceptual thresholds in cellular and molecular biology

    Science.gov (United States)

    Feldon, David F.; Rates, Christopher; Sun, Chongning

    2017-12-01

    In the biological sciences, very little is known about the mechanisms by which doctoral students acquire the skills they need to become independent scientists. In the postsecondary biology education literature, identification of specific skills and effective methods for helping students to acquire them are limited to undergraduate education. To establish a foundation from which to investigate the developmental trajectory of biologists' research skills, it is necessary to identify those skills which are integral to doctoral study and distinct from skills acquired earlier in students' educational pathways. In this context, the current study engages the framework of threshold concepts to identify candidate skills that are both obstacles and significant opportunities for developing proficiency in conducting research. Such threshold concepts are typically characterised as transformative, integrative, irreversible, and challenging. The results from interviews and focus groups with current and former doctoral students in cellular and molecular biology suggest two such threshold concepts relevant to their subfield: the first is an ability to effectively engage primary research literature from the biological sciences in a way that is critical without dismissing the value of its contributions. The second is the ability to conceptualise appropriate control conditions necessary to design and interpret the results of experiments in an efficient and effective manner for research in the biological sciences as a discipline. Implications for prioritising and sequencing graduate training experiences are discussed on the basis of the identified thresholds.

  20. Using ecological thresholds to inform resource management: current options and future possibilities

    Directory of Open Access Journals (Sweden)

    Melissa M Foley

    2015-11-01

    Full Text Available In the face of growing human impacts on ecosystems, scientists and managers recognize the need to better understand thresholds and nonlinear dynamics in ecological systems to help set management targets. However, our understanding of the factors that drive threshold dynamics, and when and how rapidly thresholds will be crossed is currently limited in many systems. In spite of these limitations, there are approaches available to practitioners today—including ecosystem monitoring, statistical methods to identify thresholds and indicators, and threshold-based adaptive management—that can be used to help avoid ecological thresholds or restore systems that have crossed them. We briefly review the current state of knowledge and then use real-world examples to demonstrate how resource managers can use available approaches to avoid crossing ecological thresholds. We also highlight new tools and indicators being developed that have the potential to enhance our ability to detect change, predict when a system is approaching an ecological threshold, or restore systems that have already crossed a tipping point.

  1. A Threshold Continuum for Aeolian Sand Transport

    Science.gov (United States)

    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.

  2. Cinética do consumo de oxigênio e tempo limite na vvo2max: comparação entre homens e mulheres Oxygen uptake kinetics and threshold time at the vVO2max: tomparison between men and women

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Silva Marques de Azevedo

    2010-08-01

    Full Text Available Foi investigada a influência do gênero no tempo limite (Tlim e na cinética do VO2 durante corrida na velocidade associada ao VO2max (vVO2max em nove homens e nove mulheres, todos adultos, jovens e sedentários, com idades entre 20 e 30 anos. Homens e mulheres realizaram dois testes em esteira rolante, sendo um teste incremental para determinar VO2max (42,66 ± 4,50 vs. 32,92 ± 6,03mL.kg-1.min-1 e vVO2max (13.2 ± 1.5 vs. 10,3 ± 2,0km.h-1, respectivamente. Um segundo teste com carga constante na vVO2max até a exaustão. O Tlim e a cinética do VO2 foram determinados. Não houve diferença significante entre homens e mulheres para constante de tempo (τ (35,76 ± 21,03 vs. 36,5 ± 6,21s, respectivamente; P = 0,29; Tlim (308 ± 84,3 vs. 282,11 ± 57,19s, respectivamente; P = 0,68, tempo para atingir o VO2max (TAVO2max (164,48 ± 96,73 vs. 167,88 ± 28,59s, respectivamente; P = 0,29, tempo para atingir o VO2max em percentual do Tlim (%Tlim (50,24 ± 16,93 vs. 62,63 ± 16,60%, respectivamente; P = 0,19, tempo mantido no VO2max (TMVO2max (144,08 ± 42,55 vs. 114,23 ± 76,96s, respectivamente; P = 0,13. Estes resultados sugerem que a cinética do VO2 e o Tlim são similares entre homens e mulheres sedentários na vVO2max.The aim of this study was to investigate the influence of gender on Tthre and VO2 response during running exercise performed at vVO2max. Therefore, eighteen untrained individuals (9 male and 9 female with normal weight and aged between 20 - 30 years (VO2max = 42.66 ± 4.50 vs 32.92 ± 6.03 mL.kg-1.min-1 and vVO2max = 13.2 ± 1.5 vs 10.3 ± 2.0 km.h-1, for male and female, respectively were assessed. Subjects performed two exercise tests on treadmill. First one was an incremental test to determine VO2max, velocity at VO2max (vVO2max and second test was performed at steady velocity - vVO2max - until exhaustion. The threshold time (Tthre and VO2 kinetics response was determined. No significant differences were observed between men

  3. Hyper-arousal decreases human visual thresholds.

    Directory of Open Access Journals (Sweden)

    Adam J Woods

    Full Text Available Arousal has long been known to influence behavior and serves as an underlying component of cognition and consciousness. However, the consequences of hyper-arousal for visual perception remain unclear. The present study evaluates the impact of hyper-arousal on two aspects of visual sensitivity: visual stereoacuity and contrast thresholds. Sixty-eight participants participated in two experiments. Thirty-four participants were randomly divided into two groups in each experiment: Arousal Stimulation or Sham Control. The Arousal Stimulation group underwent a 50-second cold pressor stimulation (immersing the foot in 0-2° C water, a technique known to increase arousal. In contrast, the Sham Control group immersed their foot in room temperature water. Stereoacuity thresholds (Experiment 1 and contrast thresholds (Experiment 2 were measured before and after stimulation. The Arousal Stimulation groups demonstrated significantly lower stereoacuity and contrast thresholds following cold pressor stimulation, whereas the Sham Control groups showed no difference in thresholds. These results provide the first evidence that hyper-arousal from sensory stimulation can lower visual thresholds. Hyper-arousal's ability to decrease visual thresholds has important implications for survival, sports, and everyday life.

  4. Alternative method for determining anaerobic threshold in rowers

    Directory of Open Access Journals (Sweden)

    Giovani dos Santos Cunha

    2008-12-01

    Full Text Available In rowing, the standard breathing that athletes are trained to use makes it difficult, or even impossible, to detectventilatory limits, due to the coupling of the breath with the technical movement. For this reason, some authors have proposeddetermining the anaerobic threshold from the respiratory exchange ratio (RER, but there is not yet consensus on what valueof RER should be used. The objective of this study was to test what value of RER corresponds to the anaerobic thresholdand whether this value can be used as an independent parameter for determining the anaerobic threshold of rowers. Thesample comprised 23 male rowers. They were submitted to a maximal cardiorespiratory test on a rowing ergometer withconcurrent ergospirometry in order to determine VO2máx and the physiological variables corresponding to their anaerobicthreshold. The anaerobic threshold was determined using the Dmax (maximal distance method. The physiological variableswere classified into maximum values and anaerobic threshold values. The maximal state of these rowers reached VO2(58.2±4.4 ml.kg-1.min-1, lactate (8.2±2.1 mmol.L-1, power (384±54.3 W and RER (1.26±0.1. At the anaerobic thresholdthey reached VO2 (46.9±7.5 ml.kg-1.min-1, lactate (4.6±1.3 mmol.L-1, power (300± 37.8 W and RER (0.99±0.1. Conclusions- the RER can be used as an independent method for determining the anaerobic threshold of rowers, adopting a value of0.99, however, RER should exhibit a non-linear increase above this figure.

  5. Music students: conventional hearing thresholds and at high frequencies.

    Science.gov (United States)

    Lüders, Débora; Gonçalves, Cláudia Giglio de Oliveira; Lacerda, Adriana Bender de Moreira; Ribas, Ângela; Conto, Juliana de

    2014-01-01

    Research has shown that hearing loss in musicians may cause difficulty in timbre recognition and tuning of instruments. To analyze the hearing thresholds from 250 Hz to 16,000 Hz in a group of music students and compare them to a non-musician group in order to determine whether high-frequency audiometry is a useful tool in the early detection of hearing impairment. Study design was a retrospective observational cohort. Conventional and high-frequency audiometry was performed in 42 music students (Madsen Itera II audiometer and TDH39P headphones for conventional audiometry, and HDA 200 headphones for high-frequency audiometry). Of the 42 students, 38.1% were female students and 61.9% were male students, with a mean age of 26 years. At conventional audiometry, 92.85% had hearing thresholds within normal limits; but even within the normal limits, the worst results were observed in the left ear for all frequencies, except for 4000 Hz; compared to the non-musician group, the worst results occurred at 500 Hz in the left ear, and at 250 Hz, 6000 Hz, 9000 Hz, 10,000 Hz, and 11,200 Hz in both the ears. The periodic evaluation of high-frequency thresholds may be useful in the early detection of hearing loss in musicians. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  6. Music students: conventional hearing thresholds and at high frequencies

    Directory of Open Access Journals (Sweden)

    Débora Lüders

    2014-07-01

    Full Text Available INTRODUCTION: Research has shown that hearing loss in musicians may cause difficulty in timbre recognition and tuning of instruments. AIM: To analyze the hearing thresholds from 250 Hz to 16,000 Hz in a group of music students and compare them to a non-musician group in order to determine whether high-frequency audiometry is a useful tool in the early detection of hearing impairment. METHODS: Study design was a retrospective observational cohort. Conventional and high-frequency audiometry was performed in 42 music students (Madsen Itera II audiometer and TDH39P headphones for conventional audiometry, and HDA 200 headphones for high-frequency audiometry. RESULTS: Of the 42 students, 38.1% were female students and 61.9% were male students, with a mean age of 26 years. At conventional audiometry, 92.85% had hearing thresholds within normal limits; but even within the normal limits, the worst results were observed in the left ear for all frequencies, except for 4000 Hz; compared to the non-musician group, the worst results occurred at 500 Hz in the left ear, and at 250 Hz, 6000 Hz, 9000 Hz, 10,000 Hz, and 11,200 Hz in both the ears. CONCLUSION: The periodic evaluation of high-frequency thresholds may be useful in the early detection of hearing loss in musicians.

  7. NEUTRON SPECTRUM MEASUREMENTS USING MULTIPLE THRESHOLD DETECTORS

    Energy Technology Data Exchange (ETDEWEB)

    Gerken, William W.; Duffey, Dick

    1963-11-15

    From American Nuclear Society Meeting, New York, Nov. 1963. The use of threshold detectors, which simultaneously undergo reactions with thermal neutrons and two or more fast neutron threshold reactions, was applied to measurements of the neutron spectrum in a reactor. A number of different materials were irradiated to determine the most practical ones for use as multiple threshold detectors. These results, as well as counting techniques and corrections, are presented. Some materials used include aluminum, alloys of Al -Ni, aluminum-- nickel oxides, and magesium orthophosphates. (auth)

  8. Reaction thresholds in doubly special relativity

    International Nuclear Information System (INIS)

    Heyman, Daniel; Major, Seth; Hinteleitner, Franz

    2004-01-01

    Two theories of special relativity with an additional invariant scale, 'doubly special relativity', are tested with calculations of particle process kinematics. Using the Judes-Visser modified conservation laws, thresholds are studied in both theories. In contrast with some linear approximations, which allow for particle processes forbidden in special relativity, both the Amelino-Camelia and Magueijo-Smolin frameworks allow no additional processes. To first order, the Amelino-Camelia framework thresholds are lowered and the Magueijo-Smolin framework thresholds may be raised or lowered

  9. Evaluation of Maryland abutment scour equation through selected threshold velocity methods

    Science.gov (United States)

    Benedict, S.T.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the Maryland State Highway Administration, used field measurements of scour to evaluate the sensitivity of the Maryland abutment scour equation to the critical (or threshold) velocity variable. Four selected methods for estimating threshold velocity were applied to the Maryland abutment scour equation, and the predicted scour to the field measurements were compared. Results indicated that performance of the Maryland abutment scour equation was sensitive to the threshold velocity with some threshold velocity methods producing better estimates of predicted scour than did others. In addition, results indicated that regional stream characteristics can affect the performance of the Maryland abutment scour equation with moderate-gradient streams performing differently from low-gradient streams. On the basis of the findings of the investigation, guidance for selecting threshold velocity methods for application to the Maryland abutment scour equation are provided, and limitations are noted.

  10. Threshold concepts as barriers to understanding climate science

    Science.gov (United States)

    Walton, P.

    2013-12-01

    Whilst the scientific case for current climate change is compelling, the consequences of climate change have largely failed to permeate through to individuals. This lack of public awareness of the science and the potential impacts could be considered a key obstacle to action. The possible reasons for such limited success centre on the issue that climate change is a complex subject, and that a wide ranging academic, political and social research literature on the science and wider implications of climate change has failed to communicate the key issues in an accessible way. These failures to adequately communicate both the science and the social science of climate change at a number of levels results in ';communication gaps' that act as fundamental barriers to both understanding and engagement with the issue. Meyer and Land (2003) suggest that learners can find certain ideas and concepts within a discipline difficult to understand and these act as a barrier to deeper understanding of a subject. To move beyond these threshold concepts, they suggest that the expert needs to support the learner through a range of learning experiences that allows the development of learning strategies particular to the individual. Meyer and Land's research into these threshold concepts has been situated within Economics, but has been suggested to be more widely applicable though there has been no attempt to either define or evaluate threshold concepts to climate change science. By identifying whether common threshold concepts exist specifically in climate science for cohorts of either formal or informal learners, scientists will be better able to support the public in understanding these concepts by changing how the knowledge is communicated to help overcome these barriers to learning. This paper reports on the findings of a study that examined the role of threshold concepts as barriers to understanding climate science in a UK University and considers its implications for wider

  11. Photoproduction of the φ(1020) near threshold in CLAS

    International Nuclear Information System (INIS)

    Tedeschi, D.J.

    2002-01-01

    The differential cross section for the photoproduction of the φ (1020) near threshold (E γ = 1.57GeV) is predicted to be sensitive to production mechanisms other than diffraction. However, the existing low energy data is of limited statistics and kinematical coverage. Complete measurements of φ meson production on the proton have been performed at The Thomas Jefferson National Accelerator Facility using a liquid hydrogen target and the CEBAF Large Acceptance Spectrometer (CLAS). The φ was identified by missing mass using a proton and positive kaon detected by CLAS in coincidence with an electron in the photon tagger. The energy of the tagged, bremsstrahlung photons ranged from φ-threshold to 2.4 GeV. A description of the data set and the differential cross section for (E γ = 2.0 GeV) will be presented and compared with present theoretical calculations. (author)

  12. Temporary threshold shift after exposure to pop music.

    Science.gov (United States)

    Axelsson, A; Lindgren, F

    1978-01-01

    Temporary threshold shift (TTS) was studied in pop musicians as well as in listeners. It appears that TTS is less pronounced in pop musicians than in listeners. This can only in part be explained by slightly inferior hearing threshold levels than in the audience before exposure. Further, male listeners showed more TTS than female listeners. After 2 hours of exposure to live pop music a TTS2 appears in pop musicians after an exposure to 98 dB(A) as opposed to listeners where TTS2 appears at 92 dB(A). When the present results are related to the CHABA risk criteria it seems that exposure to live pop music at 100 dB(A) for 2 hours is a limit which should not be exceeded if the risk of permanent hearing loss is to be avoided.

  13. Threshold double photoionization of atoms with synchrotron radiation

    International Nuclear Information System (INIS)

    Armen, G.B.

    1985-01-01

    In this dissertation, probabilities of M-shell excitation accompanying K-shell photoionization in argon are examined from both an experimental and theoretical standpoint. In the limit of high excitation energy, the conventional sudden approximation is applied to the problem. Threshold behavior of these probabilities is examined in the central-field dipole approximation, which is seen to reduce to the sudden approximation at larger excitation energies. Auger satellites were measured to determine these double-excitation probabilities as a function of incident photon energy. The theoretically predicted difference between the dependence of shake-up and shake-off probabilities on the photon energy near threshold is demonstrated. The present theory is seen to provide adequate predictions for shake-up probabilities, but to underestimate shake-off

  14. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  15. Software thresholds alter the bias of actigraphy for monitoring sleep in team-sport athletes.

    Science.gov (United States)

    Fuller, Kate L; Juliff, Laura; Gore, Christopher J; Peiffer, Jeremiah J; Halson, Shona L

    2017-08-01

    Actical ® actigraphy is commonly used to monitor athlete sleep. The proprietary software, called Actiware ® , processes data with three different sleep-wake thresholds (Low, Medium or High), but there is no standardisation regarding their use. The purpose of this study was to examine validity and bias of the sleep-wake thresholds for processing Actical ® sleep data in team sport athletes. Validation study comparing actigraph against accepted gold standard polysomnography (PSG). Sixty seven nights of sleep were recorded simultaneously with polysomnography and Actical ® devices. Individual night data was compared across five sleep measures for each sleep-wake threshold using Actiware ® software. Accuracy of each sleep-wake threshold compared with PSG was evaluated from mean bias with 95% confidence limits, Pearson moment-product correlation and associated standard error of estimate. The Medium threshold generated the smallest mean bias compared with polysomnography for total sleep time (8.5min), sleep efficiency (1.8%) and wake after sleep onset (-4.1min); whereas the Low threshold had the smallest bias (7.5min) for wake bouts. Bias in sleep onset latency was the same across thresholds (-9.5min). The standard error of the estimate was similar across all thresholds; total sleep time ∼25min, sleep efficiency ∼4.5%, wake after sleep onset ∼21min, and wake bouts ∼8 counts. Sleep parameters measured by the Actical ® device are greatly influenced by the sleep-wake threshold applied. In the present study the Medium threshold produced the smallest bias for most parameters compared with PSG. Given the magnitude of measurement variability, confidence limits should be employed when interpreting changes in sleep parameters. Copyright © 2017 Sports Medicine Australia. All rights reserved.

  16. Invited perspectives: Hydrological perspectives on precipitation intensity-duration thresholds for landslide initiation: proposing hydro-meteorological thresholds

    Science.gov (United States)

    Bogaard, Thom; Greco, Roberto

    2018-01-01

    Many shallow landslides and debris flows are precipitation initiated. Therefore, regional landslide hazard assessment is often based on empirically derived precipitation intensity-duration (ID) thresholds and landslide inventories. Generally, two features of precipitation events are plotted and labeled with (shallow) landslide occurrence or non-occurrence. Hereafter, a separation line or zone is drawn, mostly in logarithmic space. The practical background of ID is that often only meteorological information is available when analyzing (non-)occurrence of shallow landslides and, at the same time, it could be that precipitation information is a good proxy for both meteorological trigger and hydrological cause. Although applied in many case studies, this approach suffers from many false positives as well as limited physical process understanding. Some first steps towards a more hydrologically based approach have been proposed in the past, but these efforts received limited follow-up.Therefore, the objective of our paper is to (a) critically analyze the concept of precipitation ID thresholds for shallow landslides and debris flows from a hydro-meteorological point of view and (b) propose a trigger-cause conceptual framework for lumped regional hydro-meteorological hazard assessment based on published examples and associated discussion. We discuss the ID thresholds in relation to return periods of precipitation, soil physics, and slope and catchment water balance. With this paper, we aim to contribute to the development of a stronger conceptual model for regional landslide hazard assessment based on physical process understanding and empirical data.

  17. Pion photoproduction on the nucleon at threshold

    International Nuclear Information System (INIS)

    Cheon, I.T.; Jeong, M.T.

    1989-08-01

    Electric dipole amplitudes of pion photoproduction on the nucleon at threshold have been calculated in the framework of the chiral bag model. Our results are in good agreement with the existing experimental data

  18. Effect of dissipation on dynamical fusion thresholds

    International Nuclear Information System (INIS)

    Sierk, A.J.

    1986-01-01

    The existence of dynamical thresholds to fusion in heavy nuclei (A greater than or equal to 200) due to the nature of the potential-energy surface is shown. These thresholds exist even in the absence of dissipative forces, due to the coupling between the various collective deformation degrees of freedom. Using a macroscopic model of nuclear shape dynamics, It is shown how three different suggested dissipation mechanisms increase by varying amounts the excitation energy over the one-dimensional barrier required to cause compound-nucleus formation. The recently introduced surface-plus-window dissipation may give a reasonable representation of experimental data on fusion thresholds, in addition to properly describing fission-fragment kinetic energies and isoscalar giant multipole widths. Scaling of threshold results to asymmetric systems is discussed. 48 refs., 10 figs

  19. 40 CFR 98.411 - Reporting threshold.

    Science.gov (United States)

    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 GHG...

  20. Melanin microcavitation threshold in the near infrared

    Science.gov (United States)

    Schmidt, Morgan S.; Kennedy, Paul K.; Vincelette, Rebecca L.; Schuster, Kurt J.; Noojin, Gary D.; Wharmby, Andrew W.; Thomas, Robert J.; Rockwell, Benjamin A.

    2014-02-01

    Thresholds for microcavitation of isolated bovine and porcine melanosomes were determined using single nanosecond (ns) laser pulses in the NIR (1000 - 1319 nm) wavelength regime. Average fluence thresholds for microcavitation increased non-linearly with increasing wavelength. Average fluence thresholds were also measured for 10-ns pulses at 532 nm, and found to be comparable to visible ns pulse values published in previous reports. Fluence thresholds were used to calculate melanosome absorption coefficients, which decreased with increasing wavelength. This trend was found to be comparable to the decrease in retinal pigmented epithelial (RPE) layer absorption coefficients reported over the same wavelength region. Estimated corneal total intraocular energy (TIE) values were determined and compared to the current and proposed maximum permissible exposure (MPE) safe exposure levels. Results from this study support the proposed changes to the MPE levels.

  1. Secure information management using linguistic threshold approach

    CERN Document Server

    Ogiela, Marek R

    2013-01-01

    This book details linguistic threshold schemes for information sharing. It examines the opportunities of using these techniques to create new models of managing strategic information shared within a commercial organisation or a state institution.

  2. Robust Adaptive Thresholder For Document Scanning Applications

    Science.gov (United States)

    Hsing, To R.

    1982-12-01

    In document scanning applications, thresholding is used to obtain binary data from a scanner. However, due to: (1) a wide range of different color backgrounds; (2) density variations of printed text information; and (3) the shading effect caused by the optical systems, the use of adaptive thresholding to enhance the useful information is highly desired. This paper describes a new robust adaptive thresholder for obtaining valid binary images. It is basically a memory type algorithm which can dynamically update the black and white reference level to optimize a local adaptive threshold function. The results of high image quality from different types of simulate test patterns can be obtained by this algorithm. The software algorithm is described and experiment results are present to describe the procedures. Results also show that the techniques described here can be used for real-time signal processing in the varied applications.

  3. Recent progress in understanding climate thresholds

    NARCIS (Netherlands)

    Good, Peter; Bamber, Jonathan; Halladay, Kate; Harper, Anna B.; Jackson, Laura C.; Kay, Gillian; Kruijt, Bart; Lowe, Jason A.; Phillips, Oliver L.; Ridley, Jeff; Srokosz, Meric; Turley, Carol; Williamson, Phillip

    2018-01-01

    This article reviews recent scientific progress, relating to four major systems that could exhibit threshold behaviour: ice sheets, the Atlantic meridional overturning circulation (AMOC), tropical forests and ecosystem responses to ocean acidification. The focus is on advances since the

  4. Verifiable Secret Redistribution for Threshold Sharing Schemes

    National Research Council Canada - National Science Library

    Wong, Theodore M; Wang, Chenxi; Wing, Jeannette M

    2002-01-01

    .... Our protocol guards against dynamic adversaries. We observe that existing protocols either cannot be readily extended to allow redistribution between different threshold schemes, or have vulnerabilities that allow faulty old shareholders...

  5. Thresholding projection estimators in functional linear models

    OpenAIRE

    Cardot, Hervé; Johannes, Jan

    2010-01-01

    We consider the problem of estimating the regression function in functional linear regression models by proposing a new type of projection estimators which combine dimension reduction and thresholding. The introduction of a threshold rule allows to get consistency under broad assumptions as well as minimax rates of convergence under additional regularity hypotheses. We also consider the particular case of Sobolev spaces generated by the trigonometric basis which permits to get easily mean squ...

  6. Noise thresholds for optical quantum computers.

    Science.gov (United States)

    Dawson, Christopher M; Haselgrove, Henry L; Nielsen, Michael A

    2006-01-20

    In this Letter we numerically investigate the fault-tolerant threshold for optical cluster-state quantum computing. We allow both photon loss noise and depolarizing noise (as a general proxy for all local noise), and obtain a threshold region of allowed pairs of values for the two types of noise. Roughly speaking, our results show that scalable optical quantum computing is possible for photon loss probabilities <3 x 10(-3), and for depolarization probabilities <10(-4).

  7. Design of Threshold Controller Based Chaotic Circuits

    DEFF Research Database (Denmark)

    Mohamed, I. Raja; Murali, K.; Sinha, Sudeshna

    2010-01-01

    We propose a very simple implementation of a second-order nonautonomous chaotic oscillator, using a threshold controller as the only source of nonlinearity. We demonstrate the efficacy and simplicity of our design through numerical and experimental results. Further, we show that this approach...... of using a threshold controller as a nonlinear element, can be extended to obtain autonomous and multiscroll chaotic attractor circuits as well....

  8. Interword and intraword pause threshold in writing.

    Science.gov (United States)

    Chenu, Florence; Pellegrino, François; Jisa, Harriet; Fayol, Michel

    2014-01-01

    Writing words in real life involves setting objectives, imagining a recipient, translating ideas into linguistic forms, managing grapho-motor gestures, etc. Understanding writing requires observation of the processes as they occur in real time. Analysis of pauses is one of the preferred methods for accessing the dynamics of writing and is based on the idea that pauses are behavioral correlates of cognitive processes. However, there is a need to clarify what we are observing when studying pause phenomena, as we will argue in the first section. This taken into account, the study of pause phenomena can be considered following two approaches. A first approach, driven by temporality, would define a threshold and observe where pauses, e.g., scriptural inactivity occurs. A second approach, linguistically driven, would define structural units and look for scriptural inactivity at the boundaries of these units or within these units. Taking a temporally driven approach, we present two methods which aim at the automatic identification of scriptural inactivity which is most likely not attributable to grapho-motor management in texts written by children and adolescents using digitizing tablets in association with Eye and Pen (©) (Chesnet and Alamargot, 2005). The first method is purely statistical and is based on the idea that the distribution of pauses exhibits different Gaussian components each of them corresponding to a different type of pause. After having reviewed the limits of this statistical method, we present a second method based on writing dynamics which attempts to identify breaking points in the writing dynamics rather than relying only on pause duration. This second method needs to be refined to overcome the fact that calculation is impossible when there is insufficient data which is often the case when working with young scriptors.

  9. A New Wavelet Threshold Function and Denoising Application

    Directory of Open Access Journals (Sweden)

    Lu Jing-yi

    2016-01-01

    Full Text Available In order to improve the effects of denoising, this paper introduces the basic principles of wavelet threshold denoising and traditional structures threshold functions. Meanwhile, it proposes wavelet threshold function and fixed threshold formula which are both improved here. First, this paper studies the problems existing in the traditional wavelet threshold functions and introduces the adjustment factors to construct the new threshold function basis on soft threshold function. Then, it studies the fixed threshold and introduces the logarithmic function of layer number of wavelet decomposition to design the new fixed threshold formula. Finally, this paper uses hard threshold, soft threshold, Garrote threshold, and improved threshold function to denoise different signals. And the paper also calculates signal-to-noise (SNR and mean square errors (MSE of the hard threshold functions, soft thresholding functions, Garrote threshold functions, and the improved threshold function after denoising. Theoretical analysis and experimental results showed that the proposed approach could improve soft threshold functions with constant deviation and hard threshold with discontinuous function problems. The proposed approach could improve the different decomposition scales that adopt the same threshold value to deal with the noise problems, also effectively filter the noise in the signals, and improve the SNR and reduce the MSE of output signals.

  10. Thresholds for boreal biome transitions.

    Science.gov (United States)

    Scheffer, Marten; Hirota, Marina; Holmgren, Milena; Van Nes, Egbert H; Chapin, F Stuart

    2012-12-26

    Although the boreal region is warming twice as fast as the global average, the way in which the vast boreal forests and tundras may respond is poorly understood. Using satellite data, we reveal marked alternative modes in the frequency distributions of boreal tree cover. At the northern end and at the dry continental southern extremes, treeless tundra and steppe, respectively, are the only possible states. However, over a broad intermediate temperature range, these treeless states coexist with boreal forest (∼75% tree cover) and with two more open woodland states (∼20% and ∼45% tree cover). Intermediate tree covers (e.g., ∼10%, ∼30%, and ∼60% tree cover) between these distinct states are relatively rare, suggesting that they may represent unstable states where the system dwells only transiently. Mechanisms for such instabilities remain to be unraveled, but our results have important implications for the anticipated response of these ecosystems to climatic change. The data reveal that boreal forest shows no gradual decline in tree cover toward its limits. Instead, our analysis suggests that it becomes less resilient in the sense that it may more easily shift into a sparse woodland or treeless state. Similarly, the relative scarcity of the intermediate ∼10% tree cover suggests that tundra may shift relatively abruptly to a more abundant tree cover. If our inferences are correct, climate change may invoke massive nonlinear shifts in boreal biomes.

  11. Characteristics of Omega-Optimized Portfolios at Different Levels of Threshold Returns

    Directory of Open Access Journals (Sweden)

    Renaldas Vilkancas

    2014-12-01

    Full Text Available There is little literature considering effects that the loss-gain threshold used for dividing good and bad outcomes by all downside (upside risk measures has on portfolio optimization and performance. The purpose of this study is to assess the performance of portfolios optimized with respect to the Omega function developed by Keating and Shadwick at different levels of the threshold returns. The most common choices of the threshold values used in various Omega studies cover the risk-free rate and the average market return or simply a zero return, even though the inventors of this measure for risk warn that “using the values of the Omega function at particular points can be critically misleading” and that “only the entire Omega function contains information on distribution”. The obtained results demonstrate the importance of the selected values of the threshold return on portfolio performance – higher levels of the threshold lead to an increase in portfolio returns, albeit at the expense of a higher risk. In fact, within a certain threshold interval, Omega-optimized portfolios achieved the highest net return, compared with all other strategies for portfolio optimization using three different test datasets. However, beyond a certain limit, high threshold values will actually start hurting portfolio performance while meta-heuristic optimizers typically are able to produce a solution at any level of the threshold, and the obtained results would most likely be financially meaningless.

  12. Using Johnson Distribution for Automatic Threshold Setting in Wind Turbine Condition Monitoring System

    DEFF Research Database (Denmark)

    Marhadi, Kun Saptohartyadi; Skrimpas, Georgios Alexandros

    2014-01-01

    not rep- resent the whole operating conditions of a turbine, which re- sults in uncertainty in the parameters of the fitted probabil- ity distribution and the thresholds calculated. In this study Johnson distribution is used to identify shape, location, and scale parameters of distribution that can best...... fit vibration data. This study shows that using Johnson distribution can elim- inate testing or fitting various distributions to the data, and have more direct approach to obtain optimal thresholds. To quantify uncertainty in the thresholds due to limited data, im- plementations with bootstrap method...

  13. Measurement of inclusive eta production in e+e- interactions near charm threshold

    International Nuclear Information System (INIS)

    Porter, F.C.

    1981-01-01

    We have measured the inclusive cross section for eta production in e + e - interactions near charm threshold using the Crystal Ball detector at SPEAR. By comparing the inclusive eta production above and below charm threshold we obtain the limits: R(e + e - →FFX) BR(F→etax)<0.3 (90% C.L., E/sub c.m./<4.5 GeV); BR(D→etax)<0.13

  14. Dose limits

    International Nuclear Information System (INIS)

    Fitoussi, L.

    1987-12-01

    The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed

  15. Effects of programming threshold and maplaw settings on acoustic thresholds and speech discrimination with the MED-EL COMBI 40+ cochlear implant.

    Science.gov (United States)

    Boyd, Paul J

    2006-12-01

    The principal task in the programming of a cochlear implant (CI) speech processor is the setting of the electrical dynamic range (output) for each electrode, to ensure that a comfortable loudness percept is obtained for a range of input levels. This typically involves separate psychophysical measurement of electrical threshold ([theta] e) and upper tolerance levels using short current bursts generated by the fitting software. Anecdotal clinical experience and some experimental studies suggest that the measurement of [theta]e is relatively unimportant and that the setting of upper tolerance limits is more critical for processor programming. The present study aims to test this hypothesis and examines in detail how acoustic thresholds and speech recognition are affected by setting of the lower limit of the output ("Programming threshold" or "PT") to understand better the influence of this parameter and how it interacts with certain other programming parameters. Test programs (maps) were generated with PT set to artificially high and low values and tested on users of the MED-EL COMBI 40+ CI system. Acoustic thresholds and speech recognition scores (sentence tests) were measured for each of the test maps. Acoustic thresholds were also measured using maps with a range of output compression functions ("maplaws"). In addition, subjective reports were recorded regarding the presence of "background threshold stimulation" which is occasionally reported by CI users if PT is set to relatively high values when using the CIS strategy. Manipulation of PT was found to have very little effect. Setting PT to minimum produced a mean 5 dB (S.D. = 6.25) increase in acoustic thresholds, relative to thresholds with PT set normally, and had no statistically significant effect on speech recognition scores on a sentence test. On the other hand, maplaw setting was found to have a significant effect on acoustic thresholds (raised as maplaw is made more linear), which provides some theoretical

  16. Ultrahigh Error Threshold for Surface Codes with Biased Noise

    Science.gov (United States)

    Tuckett, David K.; Bartlett, Stephen D.; Flammia, Steven T.

    2018-02-01

    We show that a simple modification of the surface code can exhibit an enormous gain in the error correction threshold for a noise model in which Pauli Z errors occur more frequently than X or Y errors. Such biased noise, where dephasing dominates, is ubiquitous in many quantum architectures. In the limit of pure dephasing noise we find a threshold of 43.7(1)% using a tensor network decoder proposed by Bravyi, Suchara, and Vargo. The threshold remains surprisingly large in the regime of realistic noise bias ratios, for example 28.2(2)% at a bias of 10. The performance is, in fact, at or near the hashing bound for all values of the bias. The modified surface code still uses only weight-4 stabilizers on a square lattice, but merely requires measuring products of Y instead of Z around the faces, as this doubles the number of useful syndrome bits associated with the dominant Z errors. Our results demonstrate that large efficiency gains can be found by appropriately tailoring codes and decoders to realistic noise models, even under the locality constraints of topological codes.

  17. Adiabatic theory of Wannier threshold laws and ionization cross sections

    International Nuclear Information System (INIS)

    Macek, J.H.; Ovchinnikov, S.Y.

    1994-01-01

    Adiabatic energy eigenvalues of H 2 + are computed for complex values of the internuclear distance R. The infinite number of bound-state eigenenergies are represented by a function ε(R) that is single valued on a multisheeted Riemann surface. A region is found where ε(R) and the corresponding eigenfunctions exhibit harmonic-oscillator structure characteristic of electron motion on a potential saddle. The Schroedinger equation is solved in the adiabatic approximation along a path in the complex R plane to compute ionization cross sections. The cross section thus obtained joins the Wannier threshold region with the keV energy region, but the exponent near the ionization threshold disagrees with well-accepted values. Accepted values are obtained when a lowest-order diabatic correction is employed, indicating that adiabatic approximations do not give the correct zero velocity limit for ionization cross sections. Semiclassical eigenvalues for general top-of-barrier motion are given and the theory is applied to the ionization of atomic hydrogen by electron impact. The theory with a first diabatic correction gives the Wannier threshold law even for this case

  18. Identifying Threshold Concepts for Information Literacy: A Delphi Study

    Directory of Open Access Journals (Sweden)

    Lori Townsend

    2016-06-01

    Full Text Available This study used the Delphi method to engage expert practitioners on the topic of threshold concepts for information literacy. A panel of experts considered two questions. First, is the threshold concept approach useful for information literacy instruction? The panel unanimously agreed that the threshold concept approach holds potential for information literacy instruction. Second, what are the threshold concepts for information literacy instruction? The panel proposed and discussed over fifty potential threshold concepts, finally settling on six information literacy threshold concepts.

  19. QRS Detection Based on Improved Adaptive Threshold

    Directory of Open Access Journals (Sweden)

    Xuanyu Lu

    2018-01-01

    Full Text Available Cardiovascular disease is the first cause of death around the world. In accomplishing quick and accurate diagnosis, automatic electrocardiogram (ECG analysis algorithm plays an important role, whose first step is QRS detection. The threshold algorithm of QRS complex detection is known for its high-speed computation and minimized memory storage. In this mobile era, threshold algorithm can be easily transported into portable, wearable, and wireless ECG systems. However, the detection rate of the threshold algorithm still calls for improvement. An improved adaptive threshold algorithm for QRS detection is reported in this paper. The main steps of this algorithm are preprocessing, peak finding, and adaptive threshold QRS detecting. The detection rate is 99.41%, the sensitivity (Se is 99.72%, and the specificity (Sp is 99.69% on the MIT-BIH Arrhythmia database. A comparison is also made with two other algorithms, to prove our superiority. The suspicious abnormal area is shown at the end of the algorithm and RR-Lorenz plot drawn for doctors and cardiologists to use as aid for diagnosis.

  20. Cost-effectiveness thresholds: pros and cons.

    Science.gov (United States)

    Bertram, Melanie Y; Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R

    2016-12-01

    Cost-effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost-effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost-effectiveness thresholds allow cost-effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization's Commission on Macroeconomics in Health suggested cost-effectiveness thresholds based on multiples of a country's per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this - in addition to uncertainty in the modelled cost-effectiveness ratios - can lead to the wrong decision on how to spend health-care resources. Cost-effectiveness information should be used alongside other considerations - e.g. budget impact and feasibility considerations - in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost-effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair.

  1. At-Risk-of-Poverty Threshold

    Directory of Open Access Journals (Sweden)

    Táňa Dvornáková

    2012-06-01

    Full Text Available European Statistics on Income and Living Conditions (EU-SILC is a survey on households’ living conditions. The main aim of the survey is to get long-term comparable data on social and economic situation of households. Data collected in the survey are used mainly in connection with the evaluation of income poverty and determinationof at-risk-of-poverty rate. This article deals with the calculation of the at risk-of-poverty threshold based on data from EU-SILC 2009. The main task is to compare two approaches to the computation of at riskof-poverty threshold. The first approach is based on the calculation of the threshold for each country separately,while the second one is based on the calculation of the threshold for all states together. The introduction summarizes common attributes in the calculation of the at-risk-of-poverty threshold, such as disposable household income, equivalised household income. Further, different approaches to both calculations are introduced andadvantages and disadvantages of these approaches are stated. Finally, the at-risk-of-poverty rate calculation is described and comparison of the at-risk-of-poverty rates based on these two different approaches is made.

  2. Threshold concepts in finance: student perspectives

    Science.gov (United States)

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

    2015-10-01

    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 finance academics. In addition, we investigate the potential of a framework of different types of knowledge to differentiate the delivery of the finance curriculum and the role of modelling in finance. Our purpose is to identify ways to improve curriculum design and delivery, leading to better student outcomes. Whilst we find that there is significant overlap between what students identify as important in finance and the threshold concepts identified by academics, much of this overlap is expressed by indirect reference to the concepts. Further, whilst different types of knowledge are apparent in the student data, there is evidence that students do not necessarily distinguish conceptual from other types of knowledge. As well as investigating the finance curriculum, the research demonstrates the use of threshold concepts to compare and contrast student and academic perceptions of a discipline and, as such, is of interest to researchers in education and other disciplines.

  3. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  4. Low-threshold support for families with dementia in Germany

    Directory of Open Access Journals (Sweden)

    Hochgraeber Iris

    2012-06-01

    Full Text Available Abstract Background Low-threshold support services are a part of the German health care system and help relieving family caregivers. There is limited information available on how to construct and implement low-threshold support services for people with dementia and their families in Germany. Some studies describe separately different perspectives of experiences and expectations, but there is no study combining all the different perspectives of those involved and taking the arrangements and organisation as well as their opinions on supporting and inhibiting factors into consideration. Findings This protocol describes the design of the study on low-threshold support services for families with a person with dementia in two German regions. The aim is to develop recommendations on how to build up these services and how to implement them in a region. A quantitative as well as a qualitative approach will be used. The quantitative part will be a survey on characteristics of service users and providers, as well as health care structures of the two project regions and an evaluation of important aspects derived from a literature search. Group discussions and semi-structured interviews will be carried out to get a deeper insight into the facilitators and barriers for both using and providing these services. All people involved will be included, such as the people with dementia, their relatives, volunteers, coordinators and institution representatives. Discussion Results of this study will provide important aspects for policymakers who are interested in an effective and low-threshold support for people with dementia. Furthermore the emerging recommendations can help staff and institutions to improve quality of care and can contribute to developing health and social care structures in Germany.

  5. Psychophysical thresholds of face visibility during infancy

    DEFF Research Database (Denmark)

    Gelskov, Sofie; Kouider, Sid

    2010-01-01

    The ability to detect and focus on faces is a fundamental prerequisite for developing social skills. But how well can infants detect faces? Here, we address this question by studying the minimum duration at which faces must appear to trigger a behavioral response in infants. We used a preferential...... looking method in conjunction with masking and brief presentations (300 ms and below) to establish the temporal thresholds of visibility at different stages of development. We found that 5 and 10 month-old infants have remarkably similar visibility thresholds about three times higher than those of adults....... By contrast, 15 month-olds not only revealed adult-like thresholds, but also improved their performance through memory-based strategies. Our results imply that the development of face visibility follows a non-linear course and is determined by a radical improvement occurring between 10 and 15 months....

  6. Stimulated Brillouin scattering threshold in fiber amplifiers

    International Nuclear Information System (INIS)

    Liang Liping; Chang Liping

    2011-01-01

    Based on the wave coupling theory and the evolution model of the critical pump power (or Brillouin threshold) for stimulated Brillouin scattering (SBS) in double-clad fiber amplifiers, the influence of signal bandwidth, fiber-core diameter and amplifier gain on SBS threshold is simulated theoretically. And experimental measurements of SBS are presented in ytterbium-doped double-clad fiber amplifiers with single-frequency hundred nanosecond pulse amplification. Under different input signal pulses, the forward amplified pulse distortion is observed when the pulse energy is up to 660 nJ and the peak power is up to 3.3 W in the pulse amplification with pulse duration of 200 ns and repetition rate of 1 Hz. And the backward SBS narrow pulse appears. The pulse peak power equals to SBS threshold. Good agreement is shown between the modeled and experimental data. (authors)

  7. Threshold Theory Tested in an Organizational Setting

    DEFF Research Database (Denmark)

    Christensen, Bo T.; Hartmann, Peter V. W.; Hedegaard Rasmussen, Thomas

    2017-01-01

    A large sample of leaders (N = 4257) was used to test the link between leader innovativeness and intelligence. The threshold theory of the link between creativity and intelligence assumes that below a certain IQ level (approximately IQ 120), there is some correlation between IQ and creative...... potential, but above this cutoff point, there is no correlation. Support for the threshold theory of creativity was found, in that the correlation between IQ and innovativeness was positive and significant below a cutoff point of IQ 120. Above the cutoff, no significant relation was identified, and the two...... correlations differed significantly. The finding was stable across distinct parts of the sample, providing support for the theory, although the correlations in all subsamples were small. The findings lend support to the existence of threshold effects using perceptual measures of behavior in real...

  8. Thresholds of ion turbulence in tokamaks

    International Nuclear Information System (INIS)

    Garbet, X.; Laurent, L.; Mourgues, F.; Roubin, J.P.; Samain, A.; Zou, X.L.

    1991-01-01

    The linear thresholds of ionic turbulence are numerically calculated for the Tokamaks JET and TORE SUPRA. It is proved that the stability domain at η i >0 is determined by trapped ion modes and is characterized by η i ≥1 and a threshold L Ti /R of order (0.2/0.3)/(1+T i /T e ). The latter value is significantly smaller than what has been previously predicted. Experimental temperature profiles in heated discharges are usually marginal with respect to this criterium. It is also shown that the eigenmodes are low frequency, low wavenumber ballooned modes, which may produce a very large transport once the threshold ion temperature gradient is reached

  9. THRESHOLD PARAMETER OF THE EXPECTED LOSSES

    Directory of Open Access Journals (Sweden)

    Josip Arnerić

    2012-12-01

    Full Text Available The objective of extreme value analysis is to quantify the probabilistic behavior of unusually large losses using only extreme values above some high threshold rather than using all of the data which gives better fit to tail distribution in comparison to traditional methods with assumption of normality. In our case we estimate market risk using daily returns of the CROBEX index at the Zagreb Stock Exchange. Therefore, it’s necessary to define the excess distribution above some threshold, i.e. Generalized Pareto Distribution (GPD is used as much more reliable than the normal distribution due to the fact that gives the accent on the extreme values. Parameters of GPD distribution will be estimated using maximum likelihood method (MLE. The contribution of this paper is to specify threshold which is large enough so that GPD approximation valid but low enough so that a sufficient number of observations are available for a precise fit.

  10. Determining lower threshold concentrations for synergistic effects

    DEFF Research Database (Denmark)

    Bjergager, Maj-Britt Andersen; Dalhoff, Kristoffer; Kretschmann, Andreas

    2017-01-01

    which proven synergists cease to act as synergists towards the aquatic crustacean Daphnia magna. To do this, we compared several approaches and test-setups to evaluate which approach gives the most conservative estimate for the lower threshold for synergy for three known azole synergists. We focus...... on synergistic interactions between the pyrethroid insecticide, alpha-cypermethrin, and one of the three azole fungicides prochloraz, propiconazole or epoxiconazole measured on Daphnia magna immobilization. Three different experimental setups were applied: A standard 48h acute toxicity test, an adapted 48h test...... of immobile organisms increased more than two-fold above what was predicted by independent action (vertical assessment). All three tests confirmed the hypothesis of the existence of a lower azole threshold concentration below which no synergistic interaction was observed. The lower threshold concentration...

  11. Shifts in the relationship between motor unit recruitment thresholds versus derecruitment thresholds during fatigue.

    Science.gov (United States)

    Stock, Matt S; Mota, Jacob A

    2017-12-01

    Muscle fatigue is associated with diminished twitch force amplitude. We examined changes in the motor unit recruitment versus derecruitment threshold relationship during fatigue. Nine men (mean age = 26 years) performed repeated isometric contractions at 50% maximal voluntary contraction (MVC) knee extensor force until exhaustion. Surface electromyographic signals were detected from the vastus lateralis, and were decomposed into their constituent motor unit action potential trains. Motor unit recruitment and derecruitment thresholds and firing rates at recruitment and derecruitment were evaluated at the beginning, middle, and end of the protocol. On average, 15 motor units were studied per contraction. For the initial contraction, three subjects showed greater recruitment thresholds than derecruitment thresholds for all motor units. Five subjects showed greater recruitment thresholds than derecruitment thresholds for only low-threshold motor units at the beginning, with a mean cross-over of 31.6% MVC. As the muscle fatigued, many motor units were derecruited at progressively higher forces. In turn, decreased slopes and increased y-intercepts were observed. These shifts were complemented by increased firing rates at derecruitment relative to recruitment. As the vastus lateralis fatigued, the central nervous system's compensatory adjustments resulted in a shift of the regression line of the recruitment versus derecruitment threshold relationship. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  12. Near threshold expansion of Feynman diagrams

    International Nuclear Information System (INIS)

    Mendels, E.

    2005-01-01

    The near threshold expansion of Feynman diagrams is derived from their configuration space representation, by performing all x integrations. The general scalar Feynman diagram is considered, with an arbitrary number of external momenta, an arbitrary number of internal lines and an arbitrary number of loops, in n dimensions and all masses may be different. The expansions are considered both below and above threshold. Rules, giving real and imaginary part, are derived. Unitarity of a sunset diagram with I internal lines is checked in a direct way by showing that its imaginary part is equal to the phase space integral of I particles

  13. Double photoionization of helium near threshold

    International Nuclear Information System (INIS)

    Levin, J.C.; Armen, G.B.; Sellin, I.A.

    1996-01-01

    There has been substantial recent experimental interest in the ratio of double-to-single photoionization of He near threshold following several theoretical observations that earlier measurements appear to overestimate the ratio, perhaps by as much as 25%, in the first several hundred eV above threshold. The authors recent measurements are 10%-15% below these earlier results and more recent results of Doerner et al. and Samson et al. are yet another 10% lower. The authors will compare these measurement with new data, not yet analyzed, and available theory

  14. Color image Segmentation using automatic thresholding techniques

    International Nuclear Information System (INIS)

    Harrabi, R.; Ben Braiek, E.

    2011-01-01

    In this paper, entropy and between-class variance based thresholding methods for color images segmentation are studied. The maximization of the between-class variance (MVI) and the entropy (ME) have been used as a criterion functions to determine an optimal threshold to segment images into nearly homogenous regions. Segmentation results from the two methods are validated and the segmentation sensitivity for the test data available is evaluated, and a comparative study between these methods in different color spaces is presented. The experimental results demonstrate the superiority of the MVI method for color image segmentation.

  15. Comparison between intensity- duration thresholds and cumulative rainfall thresholds for the forecasting of landslide

    Science.gov (United States)

    Lagomarsino, Daniela; Rosi, Ascanio; Rossi, Guglielmo; Segoni, Samuele; Catani, Filippo

    2014-05-01

    This work makes a quantitative comparison between the results of landslide forecasting obtained using two different rainfall threshold models, one using intensity-duration thresholds and the other based on cumulative rainfall thresholds in an area of northern Tuscany of 116 km2. The first methodology identifies rainfall intensity-duration thresholds by means a software called MaCumBA (Massive CUMulative Brisk Analyzer) that analyzes rain-gauge records, extracts the intensities (I) and durations (D) of the rainstorms associated with the initiation of landslides, plots these values on a diagram, and identifies thresholds that define the lower bounds of the I-D values. A back analysis using data from past events can be used to identify the threshold conditions associated with the least amount of false alarms. The second method (SIGMA) is based on the hypothesis that anomalous or extreme values of rainfall are responsible for landslide triggering: the statistical distribution of the rainfall series is analyzed, and multiples of the standard deviation (σ) are used as thresholds to discriminate between ordinary and extraordinary rainfall events. The name of the model, SIGMA, reflects the central role of the standard deviations in the proposed methodology. The definition of intensity-duration rainfall thresholds requires the combined use of rainfall measurements and an inventory of dated landslides, whereas SIGMA model can be implemented using only rainfall data. These two methodologies were applied in an area of 116 km2 where a database of 1200 landslides was available for the period 2000-2012. The results obtained are compared and discussed. Although several examples of visual comparisons between different intensity-duration rainfall thresholds are reported in the international literature, a quantitative comparison between thresholds obtained in the same area using different techniques and approaches is a relatively undebated research topic.

  16. Levels of alarm thresholds of meningitis outbreaks in Hamadan Province, west of Iran.

    Science.gov (United States)

    Faryadres, Mohammad; Karami, Manoochehr; Moghimbeigi, Abbas; Esmailnasab, Nader; Pazhouhi, Khabat

    2015-01-01

    Few studies have focused on syndromic data to determine levels of alarm thresholds to detection of meningitis outbreaks. The purpose of this study was to determine threshold levels of meningitis outbreak in Hamadan Province, west of Iran. Data on both confirmed and suspected cases of meningitis (fever and neurological symptom) form 21 March 2010 to 20 March 2012 were used in Hamadan Province, Iran. Alarm threshold levels of meningitis outbreak were determined using four different methods including absolute values or standard method, relative increase, statistical cutoff points and upper control limit of exponentially weighted moving average (EWMA) algorithm. Among 723 reported cases, 41 were diagnosed to have meningitis. Standard level of alarm thresholds for meningitis outbreak was determined as incidence of 5/100000 persons. Increasing 1.5 to two times in reported cases of suspected meningitis per week was known as the threshold levels according to relative increase method. An occurrence four cases of suspected meningitis per week that equals to 90th percentile was chosen as alarm thresholds by statistical cut off point method. The corresponding value according to EWMA algorithm was 2.57 i.e. three cases. Policy makers and staff of syndromic surveillance systems are highly recommended to apply the above different methods to determine the levels of alarm threshold.

  17. Threshold intensity factors as lower boundaries for crack propagation in ceramics

    Directory of Open Access Journals (Sweden)

    Walter Per-Ole

    2004-11-01

    Full Text Available Abstract Background Slow crack growth can be described in a v (crack velocity versus KI (stress intensity factor diagram. Slow crack growth in ceramics is attributed to corrosion assisted stress at the crack tip or at any pre-existing defect in the ceramic. The combined effect of high stresses at the crack tip and the presence of water or body fluid molecules (reducing surface energy at the crack tip induces crack propagation, which eventually may result in fatigue. The presence of a threshold in the stress intensity factor, below which no crack propagation occurs, has been the subject of important research in the last years. The higher this threshold, the higher the reliability of the ceramic, and consequently the longer its lifetime. Methods We utilize the Irwin K-field displacement relation to deduce crack tip stress intensity factors from the near crack tip profile. Cracks are initiated by indentation impressions. The threshold stress intensity factor is determined as the time limit of the tip stress intensity when the residual stresses have (nearly disappeared. Results We determined the threshold stress intensity factors for most of the all ceramic materials presently important for dental restorations in Europe. Of special significance is the finding that alumina ceramic has a threshold limit nearly identical with that of zirconia. Conclusion The intention of the present paper is to stress the point that the threshold stress intensity factor represents a more intrinsic property for a given ceramic material than the widely used toughness (bend strength or fracture toughness, which refers only to fast crack growth. Considering two ceramics with identical threshold limits, although with different critical stress intensity limits, means that both ceramics have identical starting points for slow crack growth. Fast catastrophic crack growth leading to spontaneous fatigue, however, is different. This growth starts later in those ceramic materials

  18. Heritability estimates derived from threshold analyses for ...

    African Journals Online (AJOL)

    Unknown

    reproductive traits in a composite multibreed beef cattle herd using a threshold model. A GFCAT set of ..... pressure for longevity include low heritabilities, the increased generation interval necessary to obtain survival information, and automatic selection because long-lived cows contribute more offspring to subsequent ...

  19. Regression Discontinuity Designs Based on Population Thresholds

    DEFF Research Database (Denmark)

    Eggers, Andrew C.; Freier, Ronny; Grembi, Veronica

    In many countries, important features of municipal government (such as the electoral system, mayors' salaries, and the number of councillors) depend on whether the municipality is above or below arbitrary population thresholds. Several papers have used a regression discontinuity design (RDD...

  20. Identification of Threshold Concepts for Biochemistry

    Science.gov (United States)

    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…

  1. The Resting Motor Threshold - Restless or Resting?

    DEFF Research Database (Denmark)

    Karabanov, Anke Ninija; Raffin, Estelle Emeline; Siebner, Hartwig Roman

    2015-01-01

    , the RMT of the right first dorsal interosseus muscle was repeatedly determined using a threshold-hunting procedure while participants performed motor imagery and visual attention tasks with the right or left hand. Data were analyzed using repeated-measure ANOVA. Results RMT differed depending on which...

  2. The gradual nature of threshold switching

    International Nuclear Information System (INIS)

    Wimmer, M; Salinga, M

    2014-01-01

    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, Ge 2 Sb 2 Te 5 , 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. (paper)

  3. Multiparty Computation from Threshold Homomorphic Encryption

    DEFF Research Database (Denmark)

    Cramer, Ronald; Damgård, Ivan Bjerre; Nielsen, Jesper Buus

    2001-01-01

    We introduce a new approach to multiparty computation (MPC) basing it on homomorphic threshold crypto-systems. We show that given keys for any sufficiently efficient system of this type, general MPC protocols for n parties can be devised which are secure against an active adversary that corrupts...

  4. Classification error of the thresholded independence rule

    DEFF Research Database (Denmark)

    Bak, Britta Anker; Fenger-Grøn, Morten; Jensen, Jens Ledet

    We consider classification in the situation of two groups with normally distributed data in the ‘large p small n’ framework. To counterbalance the high number of variables we consider the thresholded independence rule. An upper bound on the classification error is established which is taylored...

  5. Intraoperative transfusion threshold and tissue oxygenation

    DEFF Research Database (Denmark)

    Nielsen, K; Dahl, B; Johansson, P I

    2012-01-01

    Transfusion with allogeneic red blood cells (RBCs) may be needed to maintain oxygen delivery during major surgery, but the appropriate haemoglobin (Hb) concentration threshold has not been well established. We hypothesised that a higher level of Hb would be associated with improved subcutaneous...... oxygen tension during major spinal surgery....

  6. Handwriting Automaticity: The Search for Performance Thresholds

    Science.gov (United States)

    Medwell, Jane; Wray, David

    2014-01-01

    Evidence is accumulating that handwriting has an important role in written composition. In particular, handwriting automaticity appears to relate to success in composition. This relationship has been little explored in British contexts and we currently have little idea of what threshold performance levels might be. In this paper, we report on two…

  7. Grid - a fast threshold tracking procedure

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Dau, Torsten; MacDonald, Ewen

    2016-01-01

    A new procedure, called “grid”, is evaluated that allows rapid acquisition of threshold curves for psychophysics and, in particular, psychoacoustic, experiments. In this method, the parameterresponse space is sampled in two dimensions within a single run. This allows the procedure to focus more e...

  8. 49 CFR 80.13 - Threshold criteria.

    Science.gov (United States)

    2010-10-01

    ... exceed $30 million); (4) Project financing shall be repayable, in whole or in part, from tolls, user fees... Transportation Office of the Secretary of Transportation CREDIT ASSISTANCE FOR SURFACE TRANSPORTATION PROJECTS... project shall meet the following five threshold criteria: (1) The project shall be consistent with the...

  9. Low-threshold conical microcavity dye lasers

    DEFF Research Database (Denmark)

    Grossmann, Tobias; Schleede, Simone; Hauser, Mario

    2010-01-01

    element simulations confirm that lasing occurs in whispering gallery modes which corresponds well to the measured multimode laser-emission. The effect of dye concentration on lasing threshold and lasing wavelength is investigated and can be explained using a standard dye laser model....

  10. Microplastic effect thresholds for freshwater benthic macroinvertebrates

    NARCIS (Netherlands)

    Redondo Hasselerharm, P.E.; Dede Falahudin, Dede; Peeters, E.T.H.M.; Koelmans, A.A.

    2018-01-01

    Now that microplastics have been detected in lakes, rivers and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates

  11. Threshold Concepts in Finance: Conceptualizing the Curriculum

    Science.gov (United States)

    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…

  12. Distribution of sensory taste thresholds for phenylthiocarbamide ...

    African Journals Online (AJOL)

    The ability to taste Phenylthiocarbamide (PTC), a bitter organic compound has been described as a bimodal autosomal trait in both genetic and anthropological studies. This study is based on the ability of a person to taste PTC. The present study reports the threshold distribution of PTC taste sensitivity among some Muslim ...

  13. The acoustic reflex threshold in aging ears.

    Science.gov (United States)

    Silverman, C A; Silman, S; Miller, M H

    1983-01-01

    This study investigates the controversy regarding the influence of age on the acoustic reflex threshold for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators between Jerger et al. [Mono. Contemp. Audiol. 1 (1978)] and Jerger [J. Acoust. Soc. Am. 66 (1979)] on the one hand and Silman [J. Acoust. Soc. Am. 66 (1979)] and others on the other. The acoustic reflex thresholds for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators were evaluated under two measurement conditions. Seventy-two normal-hearing ears were drawn from 72 subjects ranging in age from 20-69 years. The results revealed that age was correlated with the acoustic reflex threshold for BBN activator but not for any of the tonal activators; the correlation was stronger under the 1-dB than under the 5-dB measurement condition. Also, the mean acoustic reflex thresholds for broadband noise activator were essentially similar to those reported by Jerger et al. (1978) but differed from those obtained in this study under the 1-dB measurement condition.

  14. Atherogenic Risk Factors and Hearing Thresholds

    DEFF Research Database (Denmark)

    Frederiksen, Thomas Winther; Ramlau-Hansen, Cecilia Høst; Stokholm, Zara Ann

    2014-01-01

    The objective of this study was to evaluate the influence of atherogenic risk factors on hearing thresholds. In a cross-sectional study we analyzed data from a Danish survey in 2009-2010 on physical and psychological working conditions. The study included 576 white- and blue-collar workers from c...

  15. Near threshold behavior of photoelectron satellite intensities

    International Nuclear Information System (INIS)

    Shirley, D.A.; Becker, U.; Heimann, P.A.; Langer, B.

    1987-09-01

    The historical background and understanding of photoelectron satellite peaks is reviewed, using He(n), Ne(1s), Ne(2p), Ar(1s), and Ar(3s) as case studies. Threshold studies are emphasized. The classification of electron correlation effects as either ''intrinsic'' or ''dynamic'' is recommended. 30 refs., 7 figs

  16. Development of a landlside EWS based on rainfall thresholds for Tuscany Region, Italy

    Science.gov (United States)

    Rosi, Ascanio; Segoni, Samuele; Battistini, Alessandro; Rossi, Guglielmo; Catani, Filippo; Casagli, Nicola

    2017-04-01

    We present the set-up of a landslide EWS based on rainfall thresholds for the Tuscany region (central Italy), that shows a heterogeneous distribution of reliefs and precipitation. The work started with the definition of a single set of thresholds for the whole region, but it resulted unsuitable for EWS purposes, because of the heterogeneity of the Tuscan territory and non-repeatability of the analyses, that were affected by a high degree of subjectivity. To overcome this problem, the work started from the implementation of a software capable of objectively defining the rainfall thresholds, since some of the main issues of these thresholds are the subjectivity of the analysis and therefore their non-repeatability. This software, named MaCumBA, is largely automated and can analyze, in a short time, a high number of rainfall events to define several parameters of the threshold, such as the intensity (I) and the duration (D) of the rainfall event, the no-rain time gap (NRG: how many hours without rain are needed to consider two events as separated) and the equation describing the threshold. The possibility of quickly perform several analyses lead to the decision to divide the territory in 25 homogeneous areas (named alert zones, AZ), so as a single threshold for each AZ could be defined. For the definition of the thresholds two independent datasets (of joint rainfall-landslide occurrences) have been used: a calibration dataset (data from 2000 to 2007) and a validation dataset (2008-2009). Once the thresholds were defined, a WebGIS-based EWS has been implemented. In this system it is possible to focus both on monitoring of real-time data and on forecasting at different lead times up to 48 h; forecasting data are collected from LAMI (Limited Area Model Italy) rainfall forecasts. The EWS works on the basis of the threshold parameters defined by MaCumBA (I, D, NRG). An important feature of the warning system is that the visualization of the thresholds in the Web

  17. Cost effectiveness of below-threshold waste disposal at DOE sites

    International Nuclear Information System (INIS)

    Wickham, L.E.; Smith, C.F.; Cohen, J.J.

    1986-01-01

    Previous study has indicated the feasibility of establishing a threshold of concentration below which certain low-level (radioactive wastes) (LLW) could be safely handled and disposed of by conventional means such as landfills. Such below-threshold wastes have been synonymously termed de minimis or below regulatory concern (BRC) and can be deemed appropriate for management according to their nonradiological characteristics. The objective of this study was to determine the cost effectiveness for management and disposal of below-threshold waste at certain US Department of Energy sites. The sites selected for this study were the Idaho National Engineering Laboratory and Savannah River Laboratory. Cost-benefit analysis was used to determine the impacts, benefits, and potential cost advantages of establishing and implementing a threshold limit

  18. Radar rainfall estimation for the identification of debris-flow precipitation thresholds

    Science.gov (United States)

    Marra, Francesco; Nikolopoulos, Efthymios I.; Creutin, Jean-Dominique; Borga, Marco

    2014-05-01

    Identification of rainfall thresholds for the prediction of debris-flow occurrence is a common approach for warning procedures. Traditionally the debris-flow triggering rainfall is derived from the closest available raingauge. However, the spatial and temporal variability of intense rainfall on mountainous areas, where debris flows take place, may lead to large uncertainty in point-based estimates. Nikolopoulos et al. (2014) have shown that this uncertainty translates into a systematic underestimation of the rainfall thresholds, leading to a step degradation of the performances of the rainfall threshold for identification of debris flows occurrence under operational conditions. A potential solution to this limitation lies on use of rainfall estimates from weather radar. Thanks to their high spatial and temporal resolutions, these estimates offer the advantage of providing rainfall information over the actual debris flow location. The aim of this study is to analyze the value of radar precipitation estimations for the identification of debris flow precipitation thresholds. Seven rainfall events that triggered debris flows in the Adige river basin (Eastern Italian Alps) are analyzed using data from a dense raingauge network and a C-Band weather radar. Radar data are elaborated by using a set of correction algorithms specifically developed for weather radar rainfall application in mountainous areas. Rainfall thresholds for the triggering of debris flows are identified in the form of average intensity-duration power law curves using a frequentist approach by using both radar rainfall estimates and raingauge data. Sampling uncertainty associated to the derivation of the thresholds is assessed by using a bootstrap technique (Peruccacci et al. 2012). Results show that radar-based rainfall thresholds are largely exceeding those obtained by using raingauge data. Moreover, the differences between the two thresholds may be related to the spatial characteristics (i.e., spatial

  19. LANSCE Beam Current Limiter (XL)

    International Nuclear Information System (INIS)

    Gallegos, F.R.; Hall, M.J.

    1997-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) is an engineered safety system that provides personnel protection from prompt radiation due to accelerated proton beams. The Beam Current Limiter (XL), as an active component of the RSS, limits the maximum average current in a beamline, thus the current available for a beam spill accident. Exceeding the pre-set limit initiates action by the RSS to mitigate the hazard (insertion of beam stoppers in the low energy beam transport). The beam limiter is an electrically isolated, toroidal transformer and associated electronics. The device was designed to continuously monitor beamline currents independent of any external timing. Fail-safe operation was a prime consideration in its development. Fail-safe operation is defined as functioning as intended (due to redundant circuitry), functioning with a more sensitive fault threshold, or generating a fault condition. This report describes the design philosophy, hardware, implementation, operation, and limitations of the device

  20. Cost–effectiveness thresholds: pros and cons

    Science.gov (United States)

    Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R

    2016-01-01

    Abstract Cost–effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost–effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost–effectiveness thresholds allow cost–effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization’s Commission on Macroeconomics in Health suggested cost–effectiveness thresholds based on multiples of a country’s per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this – in addition to uncertainty in the modelled cost–effectiveness ratios – can lead to the wrong decision on how to spend health-care resources. Cost–effectiveness information should be used alongside other considerations – e.g. budget impact and feasibility considerations – in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost–effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair. PMID:27994285

  1. Multimodal distribution of human cold pain thresholds.

    Science.gov (United States)

    Lötsch, Jörn; Dimova, Violeta; Lieb, Isabel; Zimmermann, Michael; Oertel, Bruno G; Ultsch, Alfred

    2015-01-01

    It is assumed that different pain phenotypes are based on varying molecular pathomechanisms. Distinct ion channels seem to be associated with the perception of cold pain, in particular TRPM8 and TRPA1 have been highlighted previously. The present study analyzed the distribution of cold pain thresholds with focus at describing the multimodality based on the hypothesis that it reflects a contribution of distinct ion channels. Cold pain thresholds (CPT) were available from 329 healthy volunteers (aged 18 - 37 years; 159 men) enrolled in previous studies. The distribution of the pooled and log-transformed threshold data was described using a kernel density estimation (Pareto Density Estimation (PDE)) and subsequently, the log data was modeled as a mixture of Gaussian distributions using the expectation maximization (EM) algorithm to optimize the fit. CPTs were clearly multi-modally distributed. Fitting a Gaussian Mixture Model (GMM) to the log-transformed threshold data revealed that the best fit is obtained when applying a three-model distribution pattern. The modes of the identified three Gaussian distributions, retransformed from the log domain to the mean stimulation temperatures at which the subjects had indicated pain thresholds, were obtained at 23.7 °C, 13.2 °C and 1.5 °C for Gaussian #1, #2 and #3, respectively. The localization of the first and second Gaussians was interpreted as reflecting the contribution of two different cold sensors. From the calculated localization of the modes of the first two Gaussians, the hypothesis of an involvement of TRPM8, sensing temperatures from 25 - 24 °C, and TRPA1, sensing cold from 17 °C can be derived. In that case, subjects belonging to either Gaussian would possess a dominance of the one or the other receptor at the skin area where the cold stimuli had been applied. The findings therefore support a suitability of complex analytical approaches to detect mechanistically determined patterns from pain phenotype data.

  2. Identifying thresholds for ecosystem-based management.

    Directory of Open Access Journals (Sweden)

    Jameal F Samhouri

    Full Text Available BACKGROUND: One of the greatest obstacles to moving ecosystem-based management (EBM from concept to practice is the lack of a systematic approach to defining ecosystem-level decision criteria, or reference points that trigger management action. METHODOLOGY/PRINCIPAL FINDINGS: To assist resource managers and policymakers in developing EBM decision criteria, we introduce a quantitative, transferable method for identifying utility thresholds. A utility threshold is the level of human-induced pressure (e.g., pollution at which small changes produce substantial improvements toward the EBM goal of protecting an ecosystem's structural (e.g., diversity and functional (e.g., resilience attributes. The analytical approach is based on the detection of nonlinearities in relationships between ecosystem attributes and pressures. We illustrate the method with a hypothetical case study of (1 fishing and (2 nearshore habitat pressure using an empirically-validated marine ecosystem model for British Columbia, Canada, and derive numerical threshold values in terms of the density of two empirically-tractable indicator groups, sablefish and jellyfish. We also describe how to incorporate uncertainty into the estimation of utility thresholds and highlight their value in the context of understanding EBM trade-offs. CONCLUSIONS/SIGNIFICANCE: For any policy scenario, an understanding of utility thresholds provides insight into the amount and type of management intervention required to make significant progress toward improved ecosystem structure and function. The approach outlined in this paper can be applied in the context of single or multiple human-induced pressures, to any marine, freshwater, or terrestrial ecosystem, and should facilitate more effective management.

  3. Do multiple body modifications alter pain threshold?

    Science.gov (United States)

    Yamamotová, A; Hrabák, P; Hříbek, P; Rokyta, R

    2017-12-30

    In recent years, epidemiological data has shown an increasing number of young people who deliberately self-injure. There have also been parallel increases in the number of people with tattoos and those who voluntarily undergo painful procedures associated with piercing, scarification, and tattooing. People with self-injury behaviors often say that they do not feel the pain. However, there is no information regarding pain perception in those that visit tattoo parlors and piercing studios compared to those who don't. The aim of this study was to compare nociceptive sensitivity in four groups of subjects (n=105, mean age 26 years, 48 women and 57 men) with different motivations to experience pain (i.e., with and without multiple body modifications) in two different situations; (1) in controlled, emotionally neutral conditions, and (2) at a "Hell Party" (HP), an event organized by a piercing and tattoo parlor, with a main event featuring a public demonstration of painful techniques (burn scars, hanging on hooks, etc.). Pain thresholds of the fingers of the hand were measured using a thermal stimulator and mechanical algometer. In HP participants, information about alcohol intake, self-harming behavior, and psychiatric history were used in the analysis as intervening variables. Individuals with body modifications as well as without body modifications had higher thermal pain thresholds at Hell Party, compared to thresholds measured at control neutral conditions. No such differences were found relative to mechanical pain thresholds. Increased pain threshold in all HP participants, irrespectively of body modification, cannot be simply explained by a decrease in the sensory component of pain; instead, we found that the environment significantly influenced the cognitive and affective component of pain.

  4. Measuring Input Thresholds on an Existing Board

    Science.gov (United States)

    Kuperman, Igor; Gutrich, Daniel G.; Berkun, Andrew C.

    2011-01-01

    A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and

  5. Critical current simulation in granular superconductors above the percolation threshold

    Science.gov (United States)

    Riedinger, Roland

    1992-02-01

    In the phase-coherent regime without applied external magnetic field, the critical superconducting current is limited by intragranular junctions which behave like Josephson junctions. We study the percolation aspects specific to lattices of such junctions and/or the mixing of superconductor with normal grains by averaging over configurations. We illustrate on 2 and 3 dimensional examples. The power laws valid near the percolation threshold are valid well above it, in two and three dimensions. We discuss the other models limiting the superconducting current, the vortex creep and superconducting order parameter fluctuations. Dans la limite de champ magnétique nul et de cohérence de phase du paramètre d'ordre supraconducteur, le courant supraconducteur maximal dans un réseau est limité par les jonctions intergranulaires qui se comportent comme des jonctions Josephson. Nous analysons les problèmes de percolation spécifiques aux réseaux de jonctions et du mélange de grains normaux et supraconducteurs. Nous donnons des exemples bidimensionnels et tridimensionnels ; après moyenne sur les configurations et analyse en taille finie, nous montrons que les lois de puissance valables au voisinage du seuil de percolation s'étendent sur un grand domaine au-delà du seuil de percolation, à deux et trois dimensions. Nous discutons les autres modèles limitant le courant supraconducteur, ancrage de vortex et fluctuations du paramètre d'ordre.

  6. Threshold behaviour in hydrological systems as (human geo-ecosystems: manifestations, controls, implications

    Directory of Open Access Journals (Sweden)

    M. Sivapalan

    2009-07-01

    Full Text Available In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a suggest indicators for detecting threshold behavior, b discuss their implications for predictability, c distinguish different forms of threshold behavior and their underlying controls, and d hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs or system states as expressed by dimensionless quantities (e.g. the Reynolds number exceed threshold values. Mixing, water movement or depletion of thermodynamic gradients becomes much more efficient as a result. Intermittency is a very good indicator for detecting event scale threshold behavior in hydrological systems. Predictability of intermittent processes/system responses is inherently low for combinations of systems states and/or boundary conditions that push the system close to a threshold. Post hoc identification of "cause-effect relations" to explain when the system became critical is inherently difficult because of our limited ability to perform observations under controlled identical experimental conditions. In this review, we distinguish three forms of threshold behavior. The first one is threshold behavior at the process level that is controlled by the interplay of local soil characteristics and states, vegetation and the rainfall forcing. Overland flow formation, particle detachment and preferential flow are examples of this. The second form of threshold behaviour is the response of systems of intermediate complexity – e.g., catchment runoff response and sediment yield – governed by the redistribution of water and sediments in space and time

  7. Differential equation models for sharp threshold dynamics.

    Science.gov (United States)

    Schramm, Harrison C; Dimitrov, Nedialko B

    2014-01-01

    We develop an extension to differential equation models of dynamical systems to allow us to analyze probabilistic threshold dynamics that fundamentally and globally change system behavior. We apply our novel modeling approach to two cases of interest: a model of infectious disease modified for malware where a detection event drastically changes dynamics by introducing a new class in competition with the original infection; and the Lanchester model of armed conflict, where the loss of a key capability drastically changes the effectiveness of one of the sides. We derive and demonstrate a step-by-step, repeatable method for applying our novel modeling approach to an arbitrary system, and we compare the resulting differential equations to simulations of the system's random progression. Our work leads to a simple and easily implemented method for analyzing probabilistic threshold dynamics using differential equations. Published by Elsevier Inc.

  8. Gamin partable radiation meter with alarm threshold

    International Nuclear Information System (INIS)

    Payat, Rene.

    1981-10-01

    The Gamin Radiation meter is a direct reading, portable, battery-powered gamma doserate meter featuring alarm thresholds. Doserate is read on a micro-ammeter with a millirad-per-hour logarithmic scale, covering a range of 0,1 to 1000 millirads/hour. The instrument issues an audible warning signal when dose-rate level exceeds a threshold value, which can be selected. The detector tube is of the Geiger-Muller counter, energy compensated type. Because of its low battery drain, the instrument can be operated continously for 1000 hours. It is powered by four 1.5 volt alcaline batteries of the R6 type. The electronic circuitry is housed in a small lightweight case made of impact resistant plastic. Applications of the Gamin portable radiation monitor are found in health physics, safety departments, medical facilities, teaching, civil defense [fr

  9. Edith Wharton's threshold phobia and two worlds.

    Science.gov (United States)

    Holtzman, Deanna; Kulish, Nancy

    2014-08-01

    The American novelist Edith Wharton suffered an unusual childhood neurotic symptom, a fear of crossing thresholds, a condition that might be called a "threshold phobia." This symptom is identified and examined in autobiographical material, letters, diaries, and selected literary fiction and nonfiction left by Wharton to arrive at a formulation not previously drawn together. A fascinating theme-living or being trapped between "two worlds"-runs through much of the writer's life and work. The phobia is related to this theme, and both can be linked more broadly to certain sexual conflicts in women. This understanding of Wharton's phobia, it is argued, throws new light on the developmental issues and conflicts related to the female "oedipal" or triadic phase, characterized by the need to negotiate the two worlds of mother and of father. © 2014 by the American Psychoanalytic Association.

  10. Ultracompact low-threshold organic laser.

    Science.gov (United States)

    Deotare, Parag B; Mahony, Thomas S; Bulović, Vladimir

    2014-11-25

    We report an ultracompact low-threshold laser with an Alq3:DCM host:guest molecular organic thin film gain layer. The device uses a photonic crystal nanobeam cavity which provides a high quality factor to mode volume (Q/V) ratio and increased spontaneous emission factor along with a small footprint. Lasing is observed with a threshold of 4.2 μJ/cm(2) when pumped by femtosecond pulses of λ = 400 nm wavelength light. We also model the dynamics of the laser and show good agreement with the experimental data. The inherent waveguide geometry of the structure enables easy on-chip integration with potential applications in biochemical sensing, inertial sensors, and data communication.

  11. Predicting visual acuity from detection thresholds.

    Science.gov (United States)

    Newacheck, J S; Haegerstrom-Portnoy, G; Adams, A J

    1990-03-01

    Visual performance based exclusively on high luminance and high contrast letter acuity measures often fails to predict individual performance at low contrast and low luminance. Here we measured visual acuity over a wide range of contrasts and luminances (low mesopic to photopic) for 17 young normal observers. Acuity vs. contrast functions appear to fit a single template which can be displaced laterally along the log contrast axis. The magnitude of this lateral displacement for different luminances was well predicted by the contrast threshold difference for a 4 min arc spot. The acuity vs. contrast template, taken from the mean of all 17 subjects, was used in conjunction with individual spot contrast threshold measures to predict an individual's visual acuity over a wide range of luminance and contrast levels. The accuracy of the visual acuity predictions from this simple procedure closely approximates test-retest accuracy for both positive (projected Landolt rings) and negative contrast (Bailey-Lovie charts).

  12. The monolithic double-threshold discriminator

    International Nuclear Information System (INIS)

    Baturitsky, M.A.; Dvornikov, O.V.

    1999-01-01

    A double-threshold discriminator capable of processing input signals of different duration is described. Simplicity of the discriminator circuitry makes it possible to embody the discriminator in multichannel ICs using microwave bipolar-JFET technology. Time walk is calculated to be less than 0.35 ns for the input ramp signals with rise times 25-100 ns and amplitudes 50 mV-1 V

  13. Factors affecting mechanical (nociceptive) thresholds in piglets.

    Science.gov (United States)

    Janczak, Andrew M; Ranheim, Birgit; Fosse, Torunn K; Hild, Sophie; Nordgreen, Janicke; Moe, Randi O; Zanella, Adroaldo J

    2012-11-01

    To evaluate the stability and repeatability of measures of mechanical (nociceptive) thresholds in piglets and to examine potentially confounding factors when using a hand held algometer. Descriptive, prospective cohort. Forty-four piglets from four litters, weighing 4.6 ± 1.0 kg (mean ± SD) at 2 weeks of age. Mechanical thresholds were measured twice on each of 2 days during the first and second week of life. Data were analyzed using a repeated measures design to test the effects of behavior prior to testing, sex, week, day within week, and repetition within day. The effect of body weight and the interaction between piglet weight and behaviour were also tested. Piglet was entered into the model as a random effect as an additional test of repeatability. The effect of repeated testing was used to test the stability of measures. Pearson correlations between repeated measures were used to test the repeatability of measures. Variance component analysis was used to describe the variability in the data. Variance component analysis indicated that piglet explained only 17% of the variance in the data. All variables in the model (behaviour prior to testing, sex, week, day within week, repetition within day, body weight, the interaction between body weight and behaviour, piglet identity) except sex had a significant effect (p testing and measures changed with repeated testing and increased with increasing piglet weight, indicating that time (age) and animal body weight should be taken into account when measuring mechanical (nociceptive) thresholds in piglets. Mechanical (nociceptive) thresholds can be used both for testing the efficacy of anaesthetics and analgesics, and for assessing hyperalgesia in chronic pain states in research and clinical settings. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

  14. Measurement of inclusive eta production in e+e- interactions near charm threshold

    International Nuclear Information System (INIS)

    Partridge, R.; Peck, C.; Porter, F.C.; Gu, Y.F.; Kollmann, W.; Richardson, M.; Strauch, K.; Wacker, K.; Aschman, D.; Bagger, J.; Burnett, T.; Cavalli-Sforza, M.; Coyne, D.; Joy, M.; Sadrozinski, H.F.W.; Hofstadter, R.; Horisberger, R.; Kirkbride, I.; Kolanoski, H.; Koenigsmann, K.; Liberman, A.; O'Reilly, J.; Osterheld, A.; Tompkins, J.; Bloom, E.; Bulos, F.; Chestnut, R.; Gaiser, J.; Godfrey, G.; Kiesling, C.; Lockman, W.; Oreglia, M.

    1981-01-01

    We have measured the inclusive cross section for eta production in e + e - interactions near charm threshold using the Crystal Ball detector. No pronounced structure in the energy dependence is observed. By comparing cross sections above and below charm threshold we obtain the limits (90% confidence limit): R(e + e - →FF-barX)Br(F→etax) <0.15--0.32 (for E/sub c.m./ from 4.0 to 4.5 GeV), Br(D→etax)<0.13 [averaged over charged and neutral D components of the psi''(3770) decays]. Our results are inconsistent with a previous report of a large energy dependence of the eta cross section ascribed to the crossing the FF* and F*F* production thresholds

  15. Explaining the length threshold of polyglutamine aggregation

    International Nuclear Information System (INIS)

    De Los Rios, Paolo; Hafner, Marc; Pastore, Annalisa

    2012-01-01

    The existence of a length threshold, of about 35 residues, above which polyglutamine repeats can give rise to aggregation and to pathologies, is one of the hallmarks of polyglutamine neurodegenerative diseases such as Huntington’s disease. The reason why such a minimal length exists at all has remained one of the main open issues in research on the molecular origins of such classes of diseases. Following the seminal proposals of Perutz, most research has focused on the hunt for a special structure, attainable only above the minimal length, able to trigger aggregation. Such a structure has remained elusive and there is growing evidence that it might not exist at all. Here we review some basic polymer and statistical physics facts and show that the existence of a threshold is compatible with the modulation that the repeat length imposes on the association and dissociation rates of polyglutamine polypeptides to and from oligomers. In particular, their dramatically different functional dependence on the length rationalizes the very presence of a threshold and hints at the cellular processes that might be at play, in vivo, to prevent aggregation and the consequent onset of the disease. (paper)

  16. Explaining the length threshold of polyglutamine aggregation

    Science.gov (United States)

    De Los Rios, Paolo; Hafner, Marc; Pastore, Annalisa

    2012-06-01

    The existence of a length threshold, of about 35 residues, above which polyglutamine repeats can give rise to aggregation and to pathologies, is one of the hallmarks of polyglutamine neurodegenerative diseases such as Huntington’s disease. The reason why such a minimal length exists at all has remained one of the main open issues in research on the molecular origins of such classes of diseases. Following the seminal proposals of Perutz, most research has focused on the hunt for a special structure, attainable only above the minimal length, able to trigger aggregation. Such a structure has remained elusive and there is growing evidence that it might not exist at all. Here we review some basic polymer and statistical physics facts and show that the existence of a threshold is compatible with the modulation that the repeat length imposes on the association and dissociation rates of polyglutamine polypeptides to and from oligomers. In particular, their dramatically different functional dependence on the length rationalizes the very presence of a threshold and hints at the cellular processes that might be at play, in vivo, to prevent aggregation and the consequent onset of the disease.

  17. Treatment of threshold retinopathy of prematurity

    Directory of Open Access Journals (Sweden)

    Deshpande Dhanashree

    1998-01-01

    Full Text Available This report deals with our experience in the management of threshold retinopathy of prematurity (ROP. A total of 45 eyes of 23 infants were subjected to treatment of threshold ROP. 26.1% of these infants had a birth weight of >l,500 gm. The preferred modality of treatment was laser indirect photocoagulation, which was facilitated by scleral depression. Cryopexy was done in cases with nondilating pupils or medial haze and was always under general anaesthesia. Retreatment with either modality was needed in 42.2% eyes; in this the skip areas were covered. Total regression of diseases was achieved in 91.1% eyes with no sequelae. All the 4 eyes that progressed to stage 5 despite treatment had zone 1 disease. Major treatment-induced complications did not occur in this series. This study underscores the importance of routine screening of infants upto 2,000 gm birth weight for ROP and the excellent response that is achieved with laser photocoagulation in inducing regression of threshold ROP. Laser is the preferred method of treatment in view of the absence of treatment-related morbidity to the premature infants.

  18. Acoustic emission sensor radiation damage threshold experiment

    International Nuclear Information System (INIS)

    Beeson, K.M.; Pepper, C.E.

    1994-01-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ''false negative or false positive'' indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments

  19. Threshold photoelectron spectroscopy of acetaldehyde and acrolein

    International Nuclear Information System (INIS)

    Yencha, Andrew J.; Siggel-King, Michele R.F.; King, George C.; Malins, Andrew E.R.; Eypper, Marie

    2013-01-01

    Highlights: •High-resolution threshold photoelectron spectrum of acetaldehyde. •High-resolution threshold photoelectron spectrum of acrolein. •High-resolution total photoion yield spectrum of acetaldehyde. •High-resolution total photoion yield spectrum of acrolein. •Determination of vertical ionization potentials in acetaldehyde and acrolein. -- Abstract: High-resolution (6 meV and 12 meV) threshold photoelectron (TPE) spectra of acetaldehyde and acrolein (2-propenal) have been recorded over the valence binding energy region 10–20 eV, employing synchrotron radiation and a penetrating-field electron spectrometer. These TPE spectra are presented here for the first time. All of the band structures observed in the TPE spectra replicate those found in their conventional HeI photoelectron (PE) spectra. However, the relative band intensities are found to be dramatically different in the two types of spectra that are attributed to the different dominant operative formation mechanisms. In addition, some band shapes and their vertical ionization potentials are found to differ in the two types of spectra that are associated with the autoionization of Rydberg states in the two molecules

  20. Validity of Lactate Thresholds in Inline Speed Skating.

    Science.gov (United States)

    Hecksteden, Anne; Heinze, Tobias; Faude, Oliver; Kindermann, Wilfried; Meyer, Tim

    2015-09-01

    Lactate thresholds are commonly used as estimates of the highest workload where lactate production and elimination are in equilibrium (maximum lactate steady state [MLSS]). However, because of the high static load on propulsive muscles, lactate kinetics in inline speed skating may differ significantly from other endurance exercise modes. Therefore, the discipline-specific validity of lactate thresholds has to be verified. Sixteen competitive inline-speed skaters (age: 30 ± 10 years; training per week: 10 ± 4 hours) completed an exhaustive stepwise incremental exercise test (start 24 km·h, step duration 3 minutes, increment 2 km·h) to determine individual anaerobic threshold (IAT) and the workload corresponding to a blood lactate concentration of 4 mmol·L (LT4) and 2-5 continuous load tests of (up to) 30 minutes to determine MLSS. The IAT and LT4 correlated significantly with MLSS, and the mean differences were almost negligible (MLSS 29.5 ± 2.5 km·h; IAT 29.2 ± 2.0 km·h; LT4 29.6 ± 2.3 km·h; p > 0.1 for all differences). However, the variability of differences was considerable resulting in 95% limits of agreement in the upper range of values known from other endurance disciplines (2.6 km·h [8.8%] for IAT and 3.1 km·h [10.3%] for LT4). Consequently, IAT and LT4 may be considered as valid estimates of the MLSS in inline speed skating, but verification by means of a constant load test should be considered in cases of doubt or when optimal accuracy is needed (e.g., in elite athletes or scientific studies).

  1. Near peripheral motion contrast threshold predicts older drivers' simulator performance.

    Science.gov (United States)

    Henderson, Steven; Gagnon, Sylvain; Collin, Charles; Tabone, Ricardo; Stinchcombe, Arne

    2013-01-01

    Our group has previously demonstrated that peripheral motion contrast threshold (PMCT) is significantly associated with self-reported accident risk of older drivers (questionnaire assessment), and with Useful Field of View(®) subtest 2 (UFOV2). It has not been shown, however, that PMCT is significantly associated with driving performance. Using the method of descending limits (spatial two-alternative forced choice) we assessed motion contrast thresholds of 28 young participants (25-45), and 21 older drivers (63-86) for 0.4 cycle/degree drifting Gabor stimuli at 15° eccentricity and examined whether it was related to performance on a simulated on-road test and to a measure of visual attention (UFOV(®) subtests 2 and 3). Peripheral motion contrast thresholds (PMCT) of younger participants were significantly lower than older participants. PMCT and UFOV2 significantly predicted driving examiners' scores of older drivers' simulator performance, as well as number of crashes. Within the older group, PMCT correlated significantly with UFOV2, UFOV3, and age. Within the younger group, PMCT was not significantly related to either UFOV(®) scores or age. Partial correlations showed that: substantial association between PMCT and UFOV2 was not age-related (within the older driver group); PMCT and UFOV2 tapped a common visual function; and PMCT assessed a component not captured by UFOV2. PMCT is potentially a useful assessment tool for predicting accident risk of older drivers, and for informing efforts to develop effective countermeasures to remediate this functional deficit as much as possible. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Extended high-frequency thresholds in college students: effects of music player use and other recreational noise.

    Science.gov (United States)

    Le Prell, Colleen G; Spankovich, Christopher; Lobariñas, Edward; Griffiths, Scott K

    2013-09-01

    Human hearing is sensitive to sounds from as low as 20 Hz to as high as 20,000 Hz in normal ears. However, clinical tests of human hearing rarely include extended high-frequency (EHF) threshold assessments, at frequencies extending beyond 8000 Hz. EHF thresholds have been suggested for use monitoring the earliest effects of noise on the inner ear, although the clinical usefulness of EHF threshold testing is not well established for this purpose. The primary objective of this study was to determine if EHF thresholds in healthy, young adult college students vary as a function of recreational noise exposure. A retrospective analysis of a laboratory database was conducted; all participants with both EHF threshold testing and noise history data were included. The potential for "preclinical" EHF deficits was assessed based on the measured thresholds, with the noise surveys used to estimate recreational noise exposure. EHF thresholds measured during participation in other ongoing studies were available from 87 participants (34 male and 53 female); all participants had hearing within normal clinical limits (≤25 HL) at conventional frequencies (0.25-8 kHz). EHF thresholds closely matched standard reference thresholds [ANSI S3.6 (1996) Annex C]. There were statistically reliable threshold differences in participants who used music players, with 3-6 dB worse thresholds at the highest test frequencies (10-16 kHz) in participants who reported long-term use of music player devices (>5 yr), or higher listening levels during music player use. It should be possible to detect small changes in high-frequency hearing for patients or participants who undergo repeated testing at periodic intervals. However, the increased population-level variability in thresholds at the highest frequencies will make it difficult to identify the presence of small but potentially important deficits in otherwise normal-hearing individuals who do not have previously established baseline data. American

  3. Thresholds of sea-level rise rate and sea-level acceleration rate in a vulnerable coastal wetland

    Science.gov (United States)

    Wu, W.; Biber, P.; Bethel, M.

    2017-12-01

    Feedback among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold help address the key challenge in ecology - nonlinear response of ecosystems to environmental change, and promote communication between ecologists and policy makers. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to the enhanced anthropogenic forces. We developed a mechanistic model to simulate wetland change and derived the SLR thresholds for Grand Bay, MS, a micro-tidal estuary with limited upland freshwater and sediment input in the northern Gulf of Mexico. The new SLR acceleration rate threshold complements the threshold of SLR rate and can help explain the temporal lag before the rapid decline of wetland area becomes evident after the SLR rate threshold is exceeded. Deriving these two thresholds depends on the temporal scale, the interaction of SLR with other environmental factors, and landscape metrics, which have not been fully accounted for before this study. The derived SLR rate thresholds range from 7.3 mm/yr to 11.9 mm/yr. The thresholds of SLR acceleration rate are 3.02×10-4 m/yr2 and 9.62×10-5 m/yr2 for 2050 and 2100 respectively. Based on the thresholds developed, predicted SLR that will adversely impact the coastal wetlands in Grand Bay by 2100 will fall within the likely range of SLR under a high warming scenario (RCP8.5), and beyond the very likely range under a low warming scenario (RCP2.6 or 3), highlighting the need to avoid the high warming scenario in the future if these marshes are to be preserved.

  4. Perspective: Uses and misuses of thresholds in diagnostic decision making.

    Science.gov (United States)

    Warner, Jeremy L; Najarian, Robert M; Tierney, Lawrence M

    2010-03-01

    The concept of thresholds plays a vital role in decisions involving the initiation, continuation, and completion of diagnostic testing. Much research has focused on the development of explicit thresholds, in the form of practice guidelines and decision analyses. However, these tools are used infrequently; most medical decisions are made at the bedside, using implicit thresholds. Study of these thresholds can lead to a deeper understanding of clinical decision making. The authors examine some factors constituting individual clinicians' implicit thresholds. They propose a model for static thresholds using the concept of situational gravity to explain why some thresholds are high, and some low. Next, they consider the hypothetical effects of incorrect placement of thresholds (miscalibration) and changes to thresholds during diagnosis (manipulation). They demonstrate these concepts using common clinical scenarios. Through analysis of miscalibration of thresholds, the authors demonstrate some common maladaptive clinical behaviors, which are nevertheless internally consistent. They then explain how manipulation of thresholds gives rise to common cognitive heuristics including premature closure and anchoring. They also discuss the case where no threshold has been exceeded despite exhaustive collection of data, which commonly leads to application of the availability or representativeness heuristics. Awareness of implicit thresholds allows for a more effective understanding of the processes of medical decision making and, possibly, to the avoidance of detrimental heuristics and their associated medical errors. Research toward accurately defining these thresholds for individual physicians and toward determining their dynamic properties during the diagnostic process may yield valuable insights.

  5. Threshold and channel interaction in cochlear implant users: evaluation of the tripolar electrode configuration.

    Science.gov (United States)

    Bierer, Julie Arenberg

    2007-03-01

    The efficacy of cochlear implants is limited by spatial and temporal interactions among channels. This study explores the spatially restricted tripolar electrode configuration and compares it to bipolar and monopolar stimulation. Measures of threshold and channel interaction were obtained from nine subjects implanted with the Clarion HiFocus-I electrode array. Stimuli were biphasic pulses delivered at 1020 pulses/s. Threshold increased from monopolar to bipolar to tripolar stimulation and was most variable across channels with the tripolar configuration. Channel interaction, quantified by the shift in threshold between single- and two-channel stimulation, occurred for all three configurations but was largest for the monopolar and simultaneous conditions. The threshold shifts with simultaneous tripolar stimulation were slightly smaller than with bipolar and were not as strongly affected by the timing of the two channel stimulation as was monopolar. The subjects' performances on clinical speech tests were correlated with channel-to-channel variability in tripolar threshold, such that greater variability was related to poorer performance. The data suggest that tripolar channels with high thresholds may reveal cochlear regions of low neuron survival or poor electrode placement.

  6. Framework for determining airport daily departure and arrival delay thresholds: statistical modelling approach.

    Science.gov (United States)

    Wesonga, Ronald; Nabugoomu, Fabian

    2016-01-01

    The study derives a framework for assessing airport efficiency through evaluating optimal arrival and departure delay thresholds. Assumptions of airport efficiency measurements, though based upon minimum numeric values such as 15 min of turnaround time, cannot be extrapolated to determine proportions of delay-days of an airport. This study explored the concept of delay threshold to determine the proportion of delay-days as an expansion of the theory of delay and our previous work. Data-driven approach using statistical modelling was employed to a limited set of determinants of daily delay at an airport. For the purpose of testing the efficacy of the threshold levels, operational data for Entebbe International Airport were used as a case study. Findings show differences in the proportions of delay at departure (μ = 0.499; 95 % CI = 0.023) and arrival (μ = 0.363; 95 % CI = 0.022). Multivariate logistic model confirmed an optimal daily departure and arrival delay threshold of 60 % for the airport given the four probable thresholds {50, 60, 70, 80}. The decision for the threshold value was based on the number of significant determinants, the goodness of fit statistics based on the Wald test and the area under the receiver operating curves. These findings propose a modelling framework to generate relevant information for the Air Traffic Management relevant in planning and measurement of airport operational efficiency.

  7. Physico-chemical thresholds in the distribution of fish species among French lakes

    Directory of Open Access Journals (Sweden)

    Roubeix Vincent

    2017-01-01

    Full Text Available The management of lakes requires the definition of physico-chemical thresholds to be used for ecosystem preservation or restoration. According to the European Water Framework Directive, the limits between physico-chemical quality classes must be set consistently with biological quality elements. One way to do this consists in analyzing the response of aquatic communities to environmental gradients across monitoring sites and in identifying ecological community thresholds, i.e. zones in the gradients where the species turnover is the highest. In this study, fish data from 196 lakes in France were considered to derive ecological thresholds using the multivariate method of gradient forest. The analysis was performed on 25 species and 36 environmental parameters. The results revealed the highest importance of maximal water temperature in the distribution of fish species. Other important parameters included geographical factors, dissolved organic carbon concentration and water transparency, while nutrients appeared to have low influence. In spite of the diversity of species responses to the gradients, community thresholds were detected in the gradients of the most important physico-chemical parameters and of total phosphorus and nitrate concentrations as well. The thresholds identified in such macroecological study may highlight new patterns of species natural distribution and improve niche characterization. Moreover, when factors that may be influenced by human activities are involved, the thresholds could be used to set environmental standards for lake preservation.

  8. A Robust Threshold for Iterative Channel Estimation in OFDM Systems

    Directory of Open Access Journals (Sweden)

    A. Kalaycioglu

    2010-04-01

    Full Text Available A novel threshold computation method for pilot symbol assisted iterative channel estimation in OFDM systems is considered. As the bits are transmitted in packets, the proposed technique is based on calculating a particular threshold for each data packet in order to select the reliable decoder output symbols to improve the channel estimation performance. Iteratively, additional pilot symbols are established according to the threshold and the channel is re-estimated with the new pilots inserted to the known channel estimation pilot set. The proposed threshold calculation method for selecting additional pilots performs better than non-iterative channel estimation, no threshold and fixed threshold techniques in poor HF channel simulations.

  9. Pressure Systems Stored-Energy Threshold Risk Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Paulsen, Samuel S.

    2009-08-25

    Federal Regulation 10 CFR 851, which became effective February 2007, brought to light potential weaknesses regarding the Pressure Safety Program at the Pacific Northwest National Laboratory (PNNL). The definition of a pressure system in 10 CFR 851 does not contain a limit based upon pressure or any other criteria. Therefore, the need for a method to determine an appropriate risk-based hazard level for pressure safety was identified. The Laboratory has historically used a stored energy of 1000 lbf-ft to define a pressure hazard; however, an analytical basis for this value had not been documented. This document establishes the technical basis by evaluating the use of stored energy as an appropriate criterion to establish a pressure hazard, exploring a suitable risk threshold for pressure hazards, and reviewing the methods used to determine stored energy. The literature review and technical analysis concludes the use of stored energy as a method for determining a potential risk, the 1000 lbf-ft threshold, and the methods used by PNNL to calculate stored energy are all appropriate. Recommendations for further program improvements are also discussed

  10. Plutonium Assay in Soil at the BRC Threshold

    International Nuclear Information System (INIS)

    Miller, T.

    2003-01-01

    The Atomic Weapons Establishment (AWE) at Aldermaston has investigated the performance of low and high-resolution gamma-ray detectors for plutonium (Pu) assay in soil at the UK Below Regulatory Concern (BRC) threshold (0.4 Bq/g above the natural background activity level). The goal was a rapid and economical technique for sorting large volumes of lightly contaminated soils into above and BRC fractions. The strategy involved utilizing the relatively high yield 60 keV emission from Am-241 ingrowth (Pu-241 daughter) and known isotopic ratios. This paper covers the determination of detector response factors for an Am-241 source positioned at various locations within a circular tray of soil. These factors were weighted, according to the relative volumes that they represent, in order to derive a uniform response factor and quantify the systematic error for non-uniform activity distributions. Detection limits and random errors were also derived from the counting data. The high-resolution detector was shown to have the best detection levels and lowest systematic and random errors. However, uncertainties for non-uniform distributions of contamination were relatively large. Hence, analyzing soils at the BRC threshold would only be feasible if contamination was well distributed throughout the soil sample being monitored. Fortunately, contaminated land at AWE is generally homogeneous and so the technique has wide applicability

  11. Impedance and instability threshold estimates in the main injector I

    International Nuclear Information System (INIS)

    Martens, M.A.; Ng, K.Y.

    1994-03-01

    One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and its potential limitations on beam intensity and beam emittance. Future work should consider this issue. The body of the work contains detailed analysis of the various impedance estimations and instability threshold calculations. The calculations are based on the Main Injector beam intensity of 6 x 10 10 protons per bunch, 95% normalized transverse emittances of 20π mm-mrad, and 95% normalized longitudinal emittance of 0.1 eV-s at 8.9 GeV injection energy and 0.25 eV-s at 150 GeV flattop energy. The conclusions section summarizes the results in the paper and is meant to be readable by itself without referring to the rest of the paper. Also in the conclusion section are recommendations for future investigations

  12. Rainfall thresholds and susceptibility mapping for shallow landslides and debris flows in Scotland

    Science.gov (United States)

    Postance, Benjamin; Hillier, John; Dijkstra, Tom; Dixon, Neil

    2017-04-01

    Shallow translational slides and debris flows (hereafter 'landslides') pose a significant threat to life and cause significant annual economic impacts (e.g. by damage and disruption of infrastructure). The focus of this research is on the definition of objective rainfall thresholds using a weather radar system and landslide susceptibility mapping. In the study area Scotland, an inventory of 75 known landslides was used for the period 2003 to 2016. First, the effect of using different rain records (i.e. time series length) on two threshold selection techniques in receiver operating characteristic (ROC) analysis was evaluated. The results show that thresholds selected by 'Threat Score' (minimising false alarms) are sensitive to rain record length and which is not routinely considered, whereas thresholds selected using 'Optimal Point' (minimising failed alarms) are not; therefore these may be suited to establishing lower limit thresholds and be of interest to those developing early warning systems. Robust thresholds are found for combinations of normalised rain duration and accumulation at 1 and 12 day's antecedence respectively; these are normalised using the rainy-day normal and an equivalent measure for rain intensity. This research indicates that, in Scotland, rain accumulation provides a better indicator than rain intensity and that landslides may be generated by threshold conditions lower than previously thought. Second, a landslide susceptibility map is constructed using a cross-validated logistic regression model. A novel element of the approach is that landslide susceptibility is calculated for individual hillslope sections. The developed thresholds and susceptibility map are combined to assess potential hazards and impacts posed to the national highway network in Scotland.

  13. Designing and Teaching Business & Society Courses from a Threshold Concept Approach

    Science.gov (United States)

    Vidal, Natalia; Smith, Renae; Spetic, Wellington

    2015-01-01

    This article examines the redesign of an undergraduate course in Business & Society using a threshold concept approach. Business & Society courses may be troublesome for students because they depart from the premise that business is limited to creating value for shareholders. We argue that Business & Society courses contain a web of…

  14. Hydrometeorological threshold conditions for debris flow initiation in Norway

    Directory of Open Access Journals (Sweden)

    N. K. Meyer

    2012-10-01

    Full Text Available Debris flows, triggered by extreme precipitation events and rapid snow melt, cause considerable damage to the Norwegian infrastructure every year. To define intensity-duration (ID thresholds for debris flow initiation critical water supply conditions arising from intensive rainfall or snow melt were assessed on the basis of daily hydro-meteorological information for 502 documented debris flow events. Two threshold types were computed: one based on absolute ID relationships and one using ID relationships normalized by the local precipitation day normal (PDN. For each threshold type, minimum, medium and maximum threshold values were defined by fitting power law curves along the 10th, 50th and 90th percentiles of the data population. Depending on the duration of the event, the absolute threshold intensities needed for debris flow initiation vary between 15 and 107 mm day−1. Since the PDN changes locally, the normalized thresholds show spatial variations. Depending on location, duration and threshold level, the normalized threshold intensities vary between 6 and 250 mm day−1. The thresholds obtained were used for a frequency analysis of over-threshold events giving an estimation of the exceedance probability and thus potential for debris flow events in different parts of Norway. The absolute thresholds are most often exceeded along the west coast, while the normalized thresholds are most frequently exceeded on the west-facing slopes of the Norwegian mountain ranges. The minimum thresholds derived in this study are in the range of other thresholds obtained for regions with a climate comparable to Norway. Statistics reveal that the normalized threshold is more reliable than the absolute threshold as the former shows no spatial clustering of debris flows related to water supply events captured by the threshold.

  15. Wafer plane inspection with soft resist thresholding

    Science.gov (United States)

    Hess, Carl; Shi, Rui-fang; Wihl, Mark; Xiong, Yalin; Pang, Song

    2008-10-01

    Wafer Plane Inspection (WPI) is an inspection mode on the KLA-Tencor TeraScaTM platform that uses the high signalto- noise ratio images from the high numerical aperture microscope, and then models the entire lithographic process to enable defect detection on the wafer plane[1]. This technology meets the needs of some advanced mask manufacturers to identify the lithographically-significant defects while ignoring the other non-lithographically-significant defects. WPI accomplishes this goal by performing defect detection based on a modeled image of how the mask features would actually print in the photoresist. There are several advantages to this approach: (1) the high fidelity of the images provide a sensitivity advantage over competing approaches; (2) the ability to perform defect detection on the wafer plane allows one to only see those defects that have a printing impact on the wafer; (3) the use of modeling on the lithographic portion of the flow enables unprecedented flexibility to support arbitrary illumination profiles, process-window inspection in unit time, and combination modes to find both printing and non-printing defects. WPI is proving to be a valuable addition to the KLA-Tencor detection algorithm suite. The modeling portion of WPI uses a single resist threshold as the final step in the processing. This has been shown to be adequate on several advanced customer layers, but is not ideal for all layers. Actual resist chemistry has complicated processes including acid and base-diffusion and quench that are not consistently well-modeled with a single resist threshold. We have considered the use of an advanced resist model for WPI, but rejected it because the burdensome requirements for the calibration of the model were not practical for reticle inspection. This paper describes an alternative approach that allows for a "soft" resist threshold to be applied that provides a more robust solution for the most challenging processes. This approach is just

  16. Category 3 threshold quantities for hazard categorization of nonreactor facilities

    International Nuclear Information System (INIS)

    Mandigo, R.L.

    1996-01-01

    This document provides the information necessary to determine Hazard Category 3 threshold quantities for those isotopes of interest not listed in WHC-CM-4-46, Section 4, Table 1.''Threshold Quantities.''

  17. Effect of threshold quantization in opportunistic splitting algorithm

    KAUST Repository

    Nam, Haewoon; Alouini, Mohamed-Slim

    2011-01-01

    This paper discusses algorithms to find the optimal threshold and also investigates the impact of threshold quantization on the scheduling outage performance of the opportunistic splitting scheduling algorithm. Since this algorithm aims at finding

  18. Multiuser switched diversity scheduling systems with per-user threshold

    KAUST Repository

    Nam, Haewoon

    2010-05-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed and analyzed in this paper. The conventional multiuser switched diversity scheduling scheme uses a single feedback threshold for every user, where the threshold is a function of the average signal-to-noise ratios (SNRs) of the users as well as the number of users involved in the scheduling process. The proposed scheme, however, constructs a sequence of feedback thresholds instead of a single feedback threshold such that each user compares its channel quality with the corresponding feedback threshold in the sequence. Numerical and simulation results show that thanks to the flexibility of threshold selection, where a potentially different threshold can be used for each user, the proposed scheme provides a higher system capacity than that for the conventional scheme. © 2006 IEEE.

  19. Marginal instability threshold of magnetosonic waves in kappa distributed plasma

    Science.gov (United States)

    Bashir, M. F.; Manzoor, M. Z.; Ilie, R.; Yoon, P. H.; Miasli, M. S.

    2017-12-01

    The dispersion relation of magnetosonic wave is studied taking the non-extensive anisotropic counter-streaming distribution which follows the Tsallis statistics. The effects of non-extensivity parameter (q), counter-streaming parameter (P) and the wave-particle interaction is analyzed on the growth rate and the marginal instability threshold condition of Magnetosonic (MS) mode to provide the possible explanation of different regions the Bale-diagram obtained from the solar wind data at 1 AU as represented by the temperature anisotropy ( ) vs plasma beta ( ) solar wind data plot. It is shown that the most of the regions of Bale-diagram is bounded by the MS instability under different condition and best fitted by the non-extesnive distribution. The results for the bi-kappa distribution and bi- Maxwellian distribution are also obtained in the limits and respectively.

  20. Superstring threshold corrections to Yukawa couplings

    International Nuclear Information System (INIS)

    Antoniadis, I.; Taylor, T.R.

    1992-12-01

    A general method of computing string corrections to the Kaehler metric and Yukawa couplings is developed at the one-loop level for a general compactification of the heterotic superstring theory. It also provides a direct determination of the so-called Green-Schwarz term. The matter metric has an infrared divergent part which reproduces the field-theoretical anomalous dimensions, and a moduli-dependent part which gives rise to threshold corrections in the physical Yukawa couplings. Explicit expressions are derived for symmetric orbifold compactifications. (author). 20 refs

  1. Double threshold discriminator for timing measurements

    International Nuclear Information System (INIS)

    Frolov, A.R.; Oslopova, T.V.; Pestov, Yu.N.

    1995-01-01

    The new type of a discriminator is based on the idea of simultaneous time measurements at two different thresholds for each pulse. Instead of using two independent electronic TDC channels this discriminator produces an output pulse with the timing taking into account the information from two time measurements ''on-line''. The operation principle, analytical calculations and experimental results are presented. The time walk of the discriminator at the level of 10 ps in the range of the input pulse height of 0.2-1.5 V has been obtained. ((orig.))

  2. Near threshold absolute TDCS: First results

    International Nuclear Information System (INIS)

    Roesel, T.; Schlemmer, P.; Roeder, J.; Frost, L.; Jung, K.; Ehrhardt, H.

    1992-01-01

    A new method, and first results for an impact energy 2 eV above the threshold of ionisation of helium, are presented for the measurement of absolute triple differential cross sections (TDCS) in a crossed beam experiment. The method is based upon measurement of beam/target overlap densities using known absolute total ionisation cross sections and of detection efficiencies using known absolute double differential cross sections (DDCS). For the present work the necessary absolute DDCS for 1 eV electrons had also to be measured. Results are presented for several different coplanar kinematics and are compared with recent DWBA calculations. (orig.)

  3. Threshold quantum cryptograph based on Grover's algorithm

    International Nuclear Information System (INIS)

    Du Jianzhong; Qin Sujuan; Wen Qiaoyan; Zhu Fuchen

    2007-01-01

    We propose a threshold quantum protocol based on Grover's operator and permutation operator on one two-qubit signal. The protocol is secure because the dishonest parties can only extract 2 bits from 3 bits information of operation on one two-qubit signal while they have to introduce error probability 3/8. The protocol includes a detection scheme to resist Trojan horse attack. With probability 1/2, the detection scheme can detect a multi-qubit signal that is used to replace a single-qubit signal, while it makes every legitimate qubit invariant

  4. Norm based Threshold Selection for Fault Detectors

    DEFF Research Database (Denmark)

    Rank, Mike Lind; Niemann, Henrik

    1998-01-01

    The design of fault detectors for fault detection and isolation (FDI) in dynamic systems is considered from a norm based point of view. An analysis of norm based threshold selection is given based on different formulations of FDI problems. Both the nominal FDI problem as well as the uncertain FDI...... problem are considered. Based on this analysis, a performance index based on norms of the involved transfer functions is given. The performance index allows us also to optimize the structure of the fault detection filter directly...

  5. Tunable femtosecond lasers with low pump thresholds

    Science.gov (United States)

    Oppo, Karen

    The work in this thesis is concerned with the development of tunable, femtosecond laser systems, exhibiting low pump threshold powers. The main motive for this work was the development of a low threshold, self-modelocked Ti:Al2O3 laser in order to replace the conventional large-frame argon-ion pump laser with a more compact and efficient all-solid-state alternative. Results are also presented for an all-solid-state, self-modelocked Cr:LiSAF laser, however most of this work is concerned with self-modelocked Ti:Al2O3 laser systems. In chapter 2, the operation of a regeneratively-initiated, and a hard-aperture self- modelocked Ti:Al2O3 laser, pumped by an argon-ion laser, is discussed. Continuous- wave oscillation thresholds as low as 160mW have been demonstrated, along with self-modelocked threshold powers as low as 500mW. The measurement and suppression of phase noise on modelocked lasers is discussed in chapter 3. This is followed by a comparison of the phase noise characteristics of the regeneratively-initiated, and hard-aperture self-modelocked Ti:Al2O3 lasers. The use of a synchronously-operating, high resolution electron-optical streak camera in the evaluation of timing jitter is also presented. In chapter 4, the construction and self-modelocked operation of an all-solid-state Ti:Al2O3 laser is described. The all-solid-state alternative to the conventional argon-ion pump laser was a continuous-wave, intracavity-frequency doubled, diode-laser pumped Nd:YLF ring laser. At a total diode-laser pump power of 10W, this minilaser was capable of producing a single frequency output of 1W, at 523.5nm in a TEM00 beam. The remainder of this thesis looks at the operation of a self-modelocked Ti:Al2O3 laser generating ultrashort pulses at wavelengths as long as 1053nm. The motive for this work was the development of an all-solid-state, self- modelocked Ti:Al2O3 laser operating at 1053nm, for use as a master oscillator in a Nd:glass power chain.

  6. Density limit study on the W7-AS stellarator

    International Nuclear Information System (INIS)

    Grigull, P.; Giannone, L.; Stroth, U.

    1998-01-01

    Data from currentless NBI discharges in W7-AS strongly indicate that the maximum density for quasi-stationary operation is limited by detachment from limiters. The threshold density at the edge scales with P s 0.5 B 0.8 (with P s being the net power flow across the LCMS) which is consistent with an edge based analytic estimation presuming constant threshold downstream temperatures. (author)

  7. Statistical Algorithm for the Adaptation of Detection Thresholds

    DEFF Research Database (Denmark)

    Stotsky, Alexander A.

    2008-01-01

    Many event detection mechanisms in spark ignition automotive engines are based on the comparison of the engine signals to the detection threshold values. Different signal qualities for new and aged engines necessitate the development of an adaptation algorithm for the detection thresholds...... remains constant regardless of engine age and changing detection threshold values. This, in turn, guarantees the same event detection performance for new and aged engines/sensors. Adaptation of the engine knock detection threshold is given as an example. Udgivelsesdato: 2008...

  8. When Do Price Thresholds Matter in Retail Categories?

    OpenAIRE

    Koen Pauwels; Shuba Srinivasan; Philip Hans Franses

    2007-01-01

    Marketing literature has long recognized that brand price elasticity need not be monotonic and symmetric, but has yet to provide generalizable market-level insights on threshold-based price elasticity, asymmetric thresholds, and the sign and magnitude of elasticity transitions. This paper introduces smooth transition regression models to study threshold-based price elasticity of the top 4 brands across 20 fast-moving consumer good categories. Threshold-based price elasticity is found for 76% ...

  9. When do price thresholds matter in retail categories?

    OpenAIRE

    Pauwels, Koen; Srinivasan, Shuba; Franses, Philip Hans

    2007-01-01

    textabstractMarketing literature has long recognized that brand price elasticity need not be monotonic and symmetric, but has yet to provide generalizable market-level insights on threshold-based price elasticity, asymmetric thresholds, and the sign and magnitude of elasticity transitions. This paper introduces smooth transition regression models to study threshold-based price elasticity of the top 4 brands across 20 fast-moving consumer good categories. Threshold-based price elasticity is fo...

  10. Identifying Threshold Concepts for Information Literacy: A Delphi Study

    OpenAIRE

    Lori Townsend; Amy R. Hofer; Silvia Lin Hanick; Korey Brunetti

    2016-01-01

    This study used the Delphi method to engage expert practitioners on the topic of threshold concepts for information literacy. A panel of experts considered two questions. First, is the threshold concept approach useful for information literacy instruction? The panel unanimously agreed that the threshold concept approach holds potential for information literacy instruction. Second, what are the threshold concepts for information literacy instruction? The panel proposed and discussed over fift...

  11. Estimating the Threshold Level of Inflation for Thailand

    OpenAIRE

    Jiranyakul, Komain

    2017-01-01

    Abstract. This paper analyzes the relationship between inflation and economic growth in Thailand using annual dataset during 1990 and 2015. The threshold model is estimated for different levels of threshold inflation rate. The results suggest that the threshold level of inflation above which inflation significantly slow growth is estimated at 3 percent. The negative relationship between inflation and growth is apparent above this threshold level of inflation. In other words, the inflation rat...

  12. Small-threshold behaviour of two-loop self-energy diagrams: two-particle thresholds

    International Nuclear Information System (INIS)

    Berends, F.A.; Davydychev, A.I.; Moskovskij Gosudarstvennyj Univ., Moscow; Smirnov, V.A.; Moskovskij Gosudarstvennyj Univ., Moscow

    1996-01-01

    The behaviour of two-loop two-point diagrams at non-zero thresholds corresponding to two-particle cuts is analyzed. The masses involved in a cut and the external momentum are assumed to be small as compared to some of the other masses of the diagram. By employing general formulae of asymptotic expansions of Feynman diagrams in momenta and masses, we construct an algorithm to derive analytic approximations to the diagrams. In such a way, we calculate several first coefficients of the expansion. Since no conditions on relative values of the small masses and the external momentum are imposed, the threshold irregularities are described analytically. Numerical examples, using diagrams occurring in the standard model, illustrate the convergence of the expansion below the first large threshold. (orig.)

  13. Impacts of DEM resolution and area threshold value uncertainty on ...

    African Journals Online (AJOL)

    ... that DEM resolution influences the selected flow accumulation threshold value; the suitable flow accumulation threshold value increases as the DEM resolution increases, and shows greater variability for basins with lower drainage densities. The link between drainage area threshold value and stream network extraction ...

  14. Circuit and method for controlling the threshold voltage of transistors.

    NARCIS (Netherlands)

    2008-01-01

    A control unit, for controlling a threshold voltage of a circuit unit having transistor devices, includes a reference circuit and a measuring unit. The measuring unit is configured to measure a threshold voltage of at least one sensing transistor of the circuit unit, and to measure a threshold

  15. Is action potential threshold lowest in the axon?

    NARCIS (Netherlands)

    Kole, Maarten H. P.; Stuart, Greg J.

    2008-01-01

    Action potential threshold is thought to be lowest in the axon, but when measured using conventional techniques, we found that action potential voltage threshold of rat cortical pyramidal neurons was higher in the axon than at other neuronal locations. In contrast, both current threshold and voltage

  16. Comparative Study of Retinal Vessel Segmentation Based on Global Thresholding Techniques

    Directory of Open Access Journals (Sweden)

    Temitope Mapayi

    2015-01-01

    Full Text Available Due to noise from uneven contrast and illumination during acquisition process of retinal fundus images, the use of efficient preprocessing techniques is highly desirable to produce good retinal vessel segmentation results. This paper develops and compares the performance of different vessel segmentation techniques based on global thresholding using phase congruency and contrast limited adaptive histogram equalization (CLAHE for the preprocessing of the retinal images. The results obtained show that the combination of preprocessing technique, global thresholding, and postprocessing techniques must be carefully chosen to achieve a good segmentation performance.

  17. Renormalizability of Reggeon field theory taking into account thresholds and ''mass'' terms at D = 2

    International Nuclear Information System (INIS)

    Eremyan, S.S.; Nazaryan, A.E.

    1982-01-01

    It is shown that the inclusion of the Reggeon production thresholds xi 0 = 1n(M 2 /s 0 )roughly-equal2 in Reggeon field theory causes the epsilon-c expansion to become analytic at epsilon-c = 2 and it becomes possible to simultaneously take epsilon-c → 2 and E → 0, which corresponds to the physical dimensionality of space in the limit of asymptotic energies. The introduction of thresholds makes it easier to carry out perturbative calculations at D = 2 by removing the ultraviolet divergences of the theory and is useful for a smooth joining of the perturbative and asymptotic solutions

  18. Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials

    International Nuclear Information System (INIS)

    Soong, Ken

    2011-01-01

    The accelerating gradient in a laser-driven dielectric accelerating structure is often limited by the laser damage threshold of the structure. For a given laser-driven dielectric accelerator design, we can maximize the accelerating gradient by choosing the best combination of the accelerator's constituent material and operating wavelength. We present here a model of the damage mechanism from ultrafast infrared pulses and compare that model with experimental measurements of the damage threshold of bulk silicon. Additionally, we present experimental measurements of a variety of candidate materials, thin films, and nanofabricated accelerating structures.

  19. Measurement of inclusive eta production in e+e- interactions near charm threshold

    International Nuclear Information System (INIS)

    Porter, F.C.

    1980-08-01

    The inclusive cross section for eta production in e + e - interactions near charm threshold was measured by use of the Crystal Ball detector at SPEAR. By comparison of the inclusive eta production above and below charm threshold the following limits were obtained: R(e + e - → F anti FX)BR(F → eta x) < 0.3 (90% C.L., E/sub cm/ < 4.5 GeV); BR(D → eta x) < 0.13 (90% C.L., averaged over charged and neutral D components of the psi''). 4 figures, 1 table

  20. Comparison of different approaches to determine the bursting threshold at ANKA

    Energy Technology Data Exchange (ETDEWEB)

    Schoenfeldt, Patrik; Hiller, Nicole; Judin, Vitali; Mueller, Anke-Susanne [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany)

    2013-07-01

    The synchrotron light source ANKA at the Karlsruhe Institute of Technology provides a dedicated low-α-optics. In this mode bursting of Coherent Synchrotron Radiation (CSR) is observed for bunch charges above a threshold that depends on beam parameters. This threshold can be determined by several approaches, e.g. bunch lengthening or changes in the THz radiation spectra. This talk compares different methods and their implementation at the ANKA storage ring outlining their advantages, disadvantages and limitations, including reliability and possibility of real time analysis.

  1. Gauge threshold corrections for local orientifolds

    International Nuclear Information System (INIS)

    Conlon, Joseph P.; Palti, Eran

    2009-01-01

    We study gauge threshold corrections for systems of fractional branes at local orientifold singularities and compare with the general Kaplunovsky-Louis expression for locally supersymmetric N = 1 gauge theories. We focus on branes at orientifolds of the C 3 /Z 4 , C 3 /Z 6 and C 3 /Z 6 ' singularities. We provide a CFT construction of these theories and compute the threshold corrections. Gauge coupling running undergoes two phases: one phase running from the bulk winding scale to the string scale, and a second phase running from the string scale to the infrared. The first phase is associated to the contribution of N = 2 sectors to the IR β functions and the second phase to the contribution of both N = 1 and N = 2 sectors. In contrast, naive application of the Kaplunovsky-Louis formula gives single running from the bulk winding mode scale. The discrepancy is resolved through 1-loop non-universality of the holomorphic gauge couplings at the singularity, induced by a 1-loop redefinition of the twisted blow-up moduli which couple differently to different gauge nodes. We also study the physics of anomalous and non-anomalous U(1)s and give a CFT description of how masses for non-anomalous U(1)s depend on the global properties of cycles.

  2. Transient threshold shift after gunshot noise exposure.

    Science.gov (United States)

    Saedi, B; Ghasemi, M; Motiee, M; Mojtahed, M; Safavi, A

    2013-01-01

    Many people, such as soldiers, are routinely exposed to gunshot noise during target practice. It is suspected that this high-intensity noise may affect audition through repeated Transient Threshold Shifts (TTS); it can also mechanically alter auditory components such as waves. This study investigates the scope of gunshot noise from the AK-47 rifle (Kalashnikov) and the impact on the shooters' audition. Forty soldiers (80 ears) were recruited in this study. They were all young and being exposed to gunshot noise for the first time. Gunshot characteristics were measured before exposure. The soldiers underwent auditory evaluation with Pure Tone Audiometry (PTA) and Oto-Acoustic Emission (OAE) once before exposure and immediately (less than one hour) after exposure. The AK-47 gunshot noise pressure level varied between L(AIm) = 73.7 dBA to L(AIm) = 111.4 dBA. Fourteen participants had subclinical hearing impairment in their pre-exposure evaluation; this number increased to 16 after the exposure. Six months post-exposure and later, the number of cases with impairment had fallen to eight (improvement in 50%). Both pre- and post-exposure OAE results were within normal values, while PTA results indicated a significant threshold alteration only at 6 kHz. The results of this study confirm that exposure to gunshot noise with no ear protection can represent a significant hazard for auditory function, especially at higher frequencies.

  3. A threshold model of investor psychology

    Science.gov (United States)

    Cross, Rod; Grinfeld, Michael; Lamba, Harbir; Seaman, Tim

    2005-08-01

    We introduce a class of agent-based market models founded upon simple descriptions of investor psychology. Agents are subject to various psychological tensions induced by market conditions and endowed with a minimal ‘personality’. This personality consists of a threshold level for each of the tensions being modeled, and the agent reacts whenever a tension threshold is reached. This paper considers an elementary model including just two such tensions. The first is ‘cowardice’, which is the stress caused by remaining in a minority position with respect to overall market sentiment and leads to herding-type behavior. The second is ‘inaction’, which is the increasing desire to act or re-evaluate one's investment position. There is no inductive learning by agents and they are only coupled via the global market price and overall market sentiment. Even incorporating just these two psychological tensions, important stylized facts of real market data, including fat-tails, excess kurtosis, uncorrelated price returns and clustered volatility over the timescale of a few days are reproduced. By then introducing an additional parameter that amplifies the effect of externally generated market noise during times of extreme market sentiment, long-time volatility correlations can also be recovered.

  4. Updated LPI Thresholds for the Nike Laser*

    Science.gov (United States)

    Weaver, J. L.; Oh, J.; Afeyan, B.; Phillips, L.; Seely, J.; Kehne, D.; Brown, C.; Obenschain, S. P.; Serlin, V.; Schmitt, A. J.; Feldman, U.; Holland, G.; Manka, C.; Lehmberg, R. H.; McLean, E.

    2009-11-01

    Advanced implosion designs for direct drive inertial confinement fusion use high laser intensities (10^15-10^16 W/cm^2) to achieve gain (g>100) with a reduction in total laser energy (ENike laser at NRL are an attractive choice due to their combination of short wavelength (248 nm), large bandwidth (1-2 THz), and beam smoothing by induced spatial incoherence but the potential threat from laser-plasma instabilities (LPI) needs to be assessed. The 2008 LPI campaign at Nike yielded threshold intensities above 10^15 W/cm^2 for the two-plasmon instability, a value higher than reported for 351 nm glass lasers. The experiments used a planar geometry, solid polystyrene targets, and a subset of beams (E<200 J) with a reduced focal spot (d<125 μm). The 2009 campaign extended the shot parameters to higher laser energies (E<1 kJ) and larger spot sizes (d<300 μm). Spectrally-resolved and time-resolved measurements of x-rays and emission near ^1/2φo and ^3/2φo harmonics of the laser wavelength show threshold intensities consistent with the 2008 results. *Work supported by DoE/NNSA

  5. Limiting currents of overcompensated electron beams

    International Nuclear Information System (INIS)

    Malafaev, V.A.

    1990-01-01

    A possibility of producing recompensated electron beam and increasing its limiting currents in the magnetic field is experimentally investigated. It is shown that such a possibility is realized when the beam is surrounded by a cylindrical net placed into the tube located under the positive potential relative to the net. In this case an increase of limiting current at the expense of increasing the ion life time, takes place. Current, exceeding the Pierce threshold 1.5 times, is obtained

  6. Window in the dark matter exclusion limits

    International Nuclear Information System (INIS)

    Zaharijas, Gabrijela; Farrar, Glennys R.

    2005-01-01

    We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range

  7. Limiting values for radioactive materials in food

    International Nuclear Information System (INIS)

    Steiner, Martin

    2014-01-01

    The contribution describes the fundamentals of radiation protection: LNT (linear, no threshold) hypotheses, ALARA (a slow as reasonably achievable), limiting values. Using the example the nuclear accident in Chernobyl the differences in contamination development in different foodstuffs in Germany is demonstrated including recommended limiting values and the radiation exposures after 30 years due to consumption of contaminated food. The natural radioactivity is about 0.3 mSv/year.

  8. 30 CFR 56.5001 - Exposure limits for airborne contaminants.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exposure limits for airborne contaminants. 56... Quality and Physical Agents Air Quality § 56.5001 Exposure limits for airborne contaminants. Except as... contaminants shall not exceed, on the basis of a time weighted average, the threshold limit values adopted by...

  9. Application of Improved Wavelet Thresholding Function in Image Denoising Processing

    Directory of Open Access Journals (Sweden)

    Hong Qi Zhang

    2014-07-01

    Full Text Available Wavelet analysis is a time – frequency analysis method, time-frequency localization problems are well solved, this paper analyzes the basic principles of the wavelet transform and the relationship between the signal singularity Lipschitz exponent and the local maxima of the wavelet transform coefficients mold, the principles of wavelet transform in image denoising are analyzed, the disadvantages of traditional wavelet thresholding function are studied, wavelet threshold function, the discontinuity of hard threshold and constant deviation of soft threshold are improved, image is denoised through using the improved threshold function.

  10. Phased arrays: A strategy to lower the energy threshold for neutrinos

    Directory of Open Access Journals (Sweden)

    Wissel Stephanie

    2017-01-01

    Full Text Available In-ice radio arrays are optimized for detecting the highest energy, cosmogenic neutrinos expected to be produced though cosmic ray interactions with background photons. However, there are two expected populations of high energy neutrinos: the astrophysical flux observed by IceCube (~1 PeV and the cosmogenic flux (~ 1017 eV or 100 PeV. Typical radio arrays employ a noise-riding trigger, which limits their minimum energy threshold based on the background noise temperature of the ice. Phased radio arrays could lower the energy threshold by combining the signals from several channels before triggering, thereby improving the signal-to-noise at the trigger level. Reducing the energy threshold would allow radio experiments to more efficiently overlap with optical Cherenkov neutrino telescopes as well as for more efficient searches for cosmogenic neutrinos. We discuss the proposed technique and prototypical phased arrays deployed in an anechoic chamber and at Greenland’s Summit Station.

  11. Dynamics of the helium atom close to the full fragmentation threshold: Ionization excitation

    International Nuclear Information System (INIS)

    Bouri, C.; Selles, P.; Malegat, L.; Teuler, J.M.; Njock, M. Kwato; Kazansky, A.K.

    2005-01-01

    The hyperspherical R-matrix method with semiclassical outgoing waves, designed to provide accurate double-ionization cross sections, is extended to allow for the computation of ionization-excitation data of comparable quality. Accordingly, it appears now as a complete method for treating the correlated dynamics of two-electron atoms, in particular above their full fragmentation threshold. Cross sections σ n and asymmetry parameters β n are obtained for single photoionization of helium with excitation of the residual ion up to as high a level as n=50 at 0.1 eV above the double-ionization threshold. These data are extrapolated to infinite values of n in order to check widespread assumptions regarding this limit. Our data are found consistent with the assumed n -3 dependence of the partial ionization cross sections. However, the β ∞ =-0.636 obtained still lies far from the -1 value expected at the double-ionization threshold

  12. Effects of noise and confidence thresholds in nominal and metric Axelrod dynamics of social influence

    Science.gov (United States)

    de Sanctis, Luca; Galla, Tobias

    2009-04-01

    We study the effects of bounded confidence thresholds and of interaction and external noise on Axelrod’s model of social influence. Our study is based on a combination of numerical simulations and an integration of the mean-field master equation describing the system in the thermodynamic limit. We find that interaction thresholds affect the system only quantitatively, but that they do not alter the basic phase structure. The known crossover between an ordered and a disordered state in finite systems subject to external noise persists in models with general confidence threshold. Interaction noise here facilitates the dynamics and reduces relaxation times. We also study Axelrod systems with metric features and point out similarities and differences compared to models with nominal features.

  13. Nonclassicality threshold for the three-qubit Greenberger-Horne-Zeilinger state

    International Nuclear Information System (INIS)

    Vertesi, Tamas; Pal, Karoly F.

    2011-01-01

    The nonclassical properties of the noisy three-qubit Greenberger-Horne-Zeilinger (GHZ) states, ρ v =v|GHZ> v is nonclassical for the parameter range 1/2< v≤1. It has been posed whether additional settings would allow to lower the threshold visibility. Here we report on Bell inequalities giving a threshold value smaller than v=1/2. This rules out the possibility of a local hidden variable model in the limit of v=1/2. In particular, the lowest threshold visibility we found is v=0.496 057, attainable with 5x5x5 settings, whereas the most economical one in number of settings corresponds to 3x3x4 settings. The method which enabled us to obtain these results, and in particular the about 10 000 tight Bell inequalities giving v<1/2, are also discussed in detail.

  14. Definition of Pluviometric Thresholds For A Real Time Flood Forecasting System In The Arno Watershed

    Science.gov (United States)

    Amadio, P.; Mancini, M.; Mazzetti, P.; Menduni, G.; Nativi, S.; Rabuffetti, D.; Ravazzani, G.; Rosso, R.

    The pluviometric flood forecasting thresholds are an easy method that helps river flood emergency management collecting data from limited area meteorologic model or telemetric raingauges. The thresholds represent the cumulated rainfall depth which generate critic discharge for a particular section. The thresholds were calculated for different sections of Arno river and for different antecedent moisture condition using the flood event distributed hydrologic model FEST. The model inputs were syntethic hietographs with different shape and duration. The system realibility has been verified by generating 500 year syntethic rainfall for 3 important subwatersheds of the studied area. A new technique to consider spatial variability of rainfall and soil properties effects on hydrograph has been investigated. The "Geomorphologic Weights" were so calculated. The alarm system has been implemented in a dedicated software (MIMI) that gets measured and forecast rainfall data from Autorità di Bacino and defines the state of the alert of the river sections.

  15. Thresholds of Toxicological Concern - Setting a threshold for testing below which there is little concern.

    Science.gov (United States)

    Hartung, Thomas

    2017-01-01

    Low dose, low risk; very low dose, no real risk. Setting a pragmatic threshold below which concerns become negligible is the purpose of thresholds of toxicological concern (TTC). The idea is that such threshold values do not need to be established for each and every chemical based on experimental data, but that by analyzing the distribution of lowest or no-effect doses of many chemicals, a TTC can be defined - typically using the 5th percentile of this distribution and lowering it by an uncertainty factor of, e.g., 100. In doing so, TTC aims to compare exposure information (dose) with a threshold below which any hazard manifestation is very unlikely to occur. The history and current developments of this concept are reviewed and the application of TTC for different regulated products and their hazards is discussed. TTC lends itself as a pragmatic filter to deprioritize testing needs whenever real-life exposures are much lower than levels where hazard manifestation would be expected, a situation that is called "negligible exposure" in the REACH legislation, though the TTC concept has not been fully incorporated in its implementation (yet). Other areas and regulations - especially in the food sector and for pharmaceutical impurities - are more proactive. Large, curated databases on toxic effects of chemicals provide us with the opportunity to set TTC for many hazards and substance classes and thus offer a precautionary second tier for risk assessments if hazard cannot be excluded. This allows focusing testing efforts better on relevant exposures to chemicals.

  16. The influence of thresholds on the risk assessment of carcinogens in food.

    Science.gov (United States)

    Pratt, Iona; Barlow, Susan; Kleiner, Juliane; Larsen, John Christian

    2009-08-01

    The risks from exposure to chemical contaminants in food must be scientifically assessed, in order to safeguard the health of consumers. Risk assessment of chemical contaminants that are both genotoxic and carcinogenic presents particular difficulties, since the effects of such substances are normally regarded as being without a threshold. No safe level can therefore be defined, and this has implications for both risk management and risk communication. Risk management of these substances in food has traditionally involved application of the ALARA (As Low as Reasonably Achievable) principle, however ALARA does not enable risk managers to assess the urgency and extent of the risk reduction measures needed. A more refined approach is needed, and several such approaches have been developed. Low-dose linear extrapolation from animal carcinogenicity studies or epidemiological studies to estimate risks for humans at low exposure levels has been applied by a number of regulatory bodies, while more recently the Margin of Exposure (MOE) approach has been applied by both the European Food Safety Authority and the Joint FAO/WHO Expert Committee on Food Additives. A further approach is the Threshold of Toxicological Concern (TTC), which establishes exposure thresholds for chemicals present in food, dependent on structure. Recent experimental evidence that genotoxic responses may be thresholded has significant implications for the risk assessment of chemicals that are both genotoxic and carcinogenic. In relation to existing approaches such as linear extrapolation, MOE and TTC, the existence of a threshold reduces the uncertainties inherent in such methodology and improves confidence in the risk assessment. However, for the foreseeable future, regulatory decisions based on the concept of thresholds for genotoxic carcinogens are likely to be taken case-by-case, based on convincing data on the Mode of Action indicating that the rate limiting variable for the development of cancer

  17. Single event upset threshold estimation based on local laser irradiation

    International Nuclear Information System (INIS)

    Chumakov, A.I.; Egorov, A.N.; Mavritsky, O.B.; Yanenko, A.V.

    1999-01-01

    An approach for estimation of ion-induced SEU threshold based on local laser irradiation is presented. Comparative experiment and software simulation research were performed at various pulse duration and spot size. Correlation of single event threshold LET to upset threshold laser energy under local irradiation was found. The computer analysis of local laser irradiation of IC structures was developed for SEU threshold LET estimation. The correlation of local laser threshold energy with SEU threshold LET was shown. Two estimation techniques were suggested. The first one is based on the determination of local laser threshold dose taking into account the relation of sensitive area to local irradiated area. The second technique uses the photocurrent peak value instead of this relation. The agreement between the predicted and experimental results demonstrates the applicability of this approach. (authors)

  18. Wave-Block Due to a Threshold Gradient Underlies Limited Coordination in Pancreatic Islets

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram; Sørensen, Mads Peter

    2008-01-01

    Two models for coupled pancreatic β cells are used to investigate excited wave propagation in spatially inhomogeneous islets of Langerhans. The application concerns spatial variation of glucose concentration across the islet. A comprehensive model of coupled cells shows that wave blocking occurs ...

  19. The problem of a threshold limit value of beryllium and its salts

    International Nuclear Information System (INIS)

    Zorn, H.; Stiefel, T.

    1977-01-01

    There are great individual differences in the dose of beryllium which produces biological measurable results even under long exposure times. To explain these different individual reactions some men, and mammals, had been clinically tested, who had been living under minimal beryllium concentrations in their breathing air, (in the environment), for a long time. The first step in these experiments was the development of analytical methods which guarantee an accurate determination of beryllium traces in organic materials. The examination of the methods produced satisfactory results only with three methods: the 7 Be-isotope, the chelate gas chromatography with ECD and the flameless a.a.s. The resorption, distribution and elimination of beryllium was measured in animal experiments. The biotransformation had been explored by biochemical methods, the biological behaviour of the lymphocytes by cellular-biological methods. The examination of the lymphocyte transformation index of men, exposed to 3 over a long time period, (> 1 year), shows, that there is no significant augmentation of the transformation index. It is considered that the lymphocyte transformation test is a satisfying method to test the individual Be-sensitivity. (author)

  20. The Limits of Moral Principle: An Ends, Means, and Role Spheres Model of the Ethical Threshold.

    Science.gov (United States)

    1986-09-01

    Stuart Mill (1806-1873) and Jeremy Bentham (1748-1832) are readily identified with utilitarianism , while Plato, Aris- totle, Immanual Kant (1724-1804), and...Pennsylvania: Chandler Publishing Company, 1970. 11. Mill , John Stewart. Utilitarianism . Edited by Oskar Piest. New York: Bobbs-Merrill, 1957. 12. Muller... John Locke (1632-1704) are identified with formalism (1:365). Utilitarian thought can be further broken down into such categories as act

  1. Forward elastic scattering above the physical threshold

    Energy Technology Data Exchange (ETDEWEB)

    Avila, R.F. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Matematica, Estatistica e Computacao Cientifica; Menon, M.J. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin

    2006-07-01

    Making use of the 'extended derivative dispersion relations', recently introduced by Avila and Menon, we analyze forward elastic proton-proton and antiproton-proton scattering at any energy above the physical threshold ({radical}s=2m{sub p} {approx} 1,88 GeV). The analysis is based on an analytical parametrization for the total cross section with leading triple pole pomeron (high energies) and full nondegenerated secondary reggeons (intermediate and low energies). Experimental data on total cross section and the ratio r between the real and imaginary parts of the forward amplitude are simultaneously fitted with the CERN-Minuit code and energy cutoff at 4 GeV. We show that, the results are exactly the same as those obtained through standard integral dispersion relations. Physical implications of the results in the pomeron-reggeon context are also discussed. (author)

  2. The thresholds for statistical and clinical significance

    DEFF Research Database (Denmark)

    Jakobsen, Janus Christian; Gluud, Christian; Winkel, Per

    2014-01-01

    BACKGROUND: Thresholds for statistical significance are insufficiently demonstrated by 95% confidence intervals or P-values when assessing results from randomised clinical trials. First, a P-value only shows the probability of getting a result assuming that the null hypothesis is true and does...... not reflect the probability of getting a result assuming an alternative hypothesis to the null hypothesis is true. Second, a confidence interval or a P-value showing significance may be caused by multiplicity. Third, statistical significance does not necessarily result in clinical significance. Therefore...... of the probability that a given trial result is compatible with a 'null' effect (corresponding to the P-value) divided by the probability that the trial result is compatible with the intervention effect hypothesised in the sample size calculation; (3) adjust the confidence intervals and the statistical significance...

  3. Analysis of threshold curves for superconducting interferometers

    International Nuclear Information System (INIS)

    Peterson, R.L.; Hamilton, C.A.

    1979-01-01

    Threshold curves for multijunction superconducting interferometers have been calculated previously, showing general agreement with observed features, especially in symmetric cases. We here add some more details to the analysis, paying particular attention to the effects of asymmetries in coupling, inductance, or critical currents. Feed-loop inductance and flux quantization in the feed loop can be important. A changing lobe pattern over many periods, asymmetries within a period, shifting patterns between runs spanning a warm-up, and sudden changes in pattern because of noise in the environment are all quantitatively explainable on the basis of this model. By use of a single ''calibration curve'', the inductance for symmetric two- or three-junction interferometers can be obtained immediately

  4. Deuteron threshold electrodisintegration at high momentum transfer

    International Nuclear Information System (INIS)

    Schmitt, W.M.; Turchinetz, W.; Williamson, C.F.; Yates, T.C.; Zumbro, J.D.; Lee, K.S.; Baghaei, H.; Churchwell, S.; Hicks, R.S.; Miskimen, R.; Peterson, G.A.; Wang, K.; Bosted, P.E.; Spengos, M.; Frois, B.; Martino, J.; Platchkov, S.; Hotta, A.

    1997-01-01

    Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160 degree for five values of Q 2 ranging from 8.66 to 42.4fm -2 . Comparisons of the data averaged over E np from 0 to 3 MeV and from 0 to 10 MeV are made with nonrelativistic meson exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the interaction. Some of these calculations can describe the data reasonably well over certain ranges of Q 2 ; however, none of these calculations can accurately describe the data over the entire measured Q 2 range. copyright 1997 The American Physical Society

  5. Deuteron threshold electrodisintegration at high momentum transfer

    International Nuclear Information System (INIS)

    Schmitt, W.M.; Turchinetz, W.; Williamson, C.F.

    1997-01-01

    Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160 degree for five values of Q 2 ranging from 8.66 to 42.4 fm -2 . Comparisons of the data averaged over E np from 0--3 MeV and 0--10 MeV are made with nonrelativistic meson-exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the interaction. Some of these calculations can describe the data reasonably well over certain ranges of Q 2 ; however, none of these calculations can accurately describe the data over the entire measured Q 2 range

  6. Deuteron Compton scattering below pion photoproduction threshold

    Science.gov (United States)

    Levchuk, M. I.; L'vov, A. I.

    2000-07-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  7. Deuteron Compton scattering below pion photoproduction threshold

    International Nuclear Information System (INIS)

    Levchuk, M.I.; L'vov, A.I.

    2000-01-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data

  8. Deuteron Compton scattering below pion photoproduction threshold

    Energy Technology Data Exchange (ETDEWEB)

    Levchuk, M.I. E-mail: levchuk@dragon.bas-net.by; L' vov, A.I. E-mail: lvov@x4u.lebedev.ru

    2000-07-17

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  9. Coping with ecological catastrophe: crossing major thresholds

    Directory of Open Access Journals (Sweden)

    John Cairns, Jr.

    2004-08-01

    Full Text Available The combination of human population growth and resource depletion makes catastrophes highly probable. No long-term solutions to the problems of humankind will be discovered unless sustainable use of the planet is achieved. The essential first step toward this goal is avoiding or coping with global catastrophes that result from crossing major ecological thresholds. Decreasing the number of global catastrophes will reduce the risks associated with destabilizing ecological systems, which could, in turn, destabilize societal systems. Many catastrophes will be local, regional, or national, but even these upheavals will have global consequences. Catastrophes will be the result of unsustainable practices and the misuse of technology. However, avoiding ecological catastrophes will depend on the development of eco-ethics, which is subject to progressive maturation, comments, and criticism. Some illustrative catastrophes have been selected to display some preliminary issues of eco-ethics.

  10. Threshold-based Adaptive Detection for WSN

    KAUST Repository

    Abuzaid, Abdulrahman I.

    2014-01-06

    Efficient receiver designs for wireless sensor networks (WSNs) are becoming increasingly important. Cooperative WSNs communicated with the use of L sensors. As the receiver is constrained, it can only process U out of L sensors. Channel shortening and reduced-rank techniques were employed to design the preprocessing matrix. In this work, a receiver structure is proposed which combines the joint iterative optimization (JIO) algorithm and our proposed threshold selection criteria. This receiver structure assists in determining the optimal Uopt. It also provides the freedom to choose U

  11. Heavy quark threshold dynamics in higher order

    Energy Technology Data Exchange (ETDEWEB)

    Piclum, J.H.

    2007-05-15

    In this work we discuss an important building block for the next-to-next-to-next-to leading order corrections to the pair production of top quarks at threshold. Specifically, we explain the calculation of the third order strong corrections to the matching coefficient of the vector current in non-relativistic Quantum Chromodynamics and provide the result for the fermionic part, containing at least one loop of massless quarks. As a byproduct, we obtain the matching coefficients of the axial-vector, pseudo-scalar and scalar current at the same order. Furthermore, we calculate the three-loop corrections to the quark renormalisation constants in the on-shell scheme in the framework of dimensional regularisation and dimensional reduction. Finally, we compute the third order strong corrections to the chromomagnetic interaction in Heavy Quark Effective Theory. The calculational methods are discussed in detail and results for the master integrals are given. (orig.)

  12. Mob control models of threshold collective behavior

    CERN Document Server

    Breer, Vladimir V; Rogatkin, Andrey D

    2017-01-01

    This book presents mathematical models of mob control with threshold (conformity) collective decision-making of the agents. Based on the results of analysis of the interconnection between the micro- and macromodels of active network structures, it considers the static (deterministic, stochastic and game-theoretic) and dynamic (discrete- and continuous-time) models of mob control, and highlights models of informational confrontation. Many of the results are applicable not only to mob control problems, but also to control problems arising in social groups, online social networks, etc. Aimed at researchers and practitioners, it is also a valuable resource for undergraduate and postgraduate students as well as doctoral candidates specializing in the field of collective behavior modeling.

  13. Magnetic monopoles near the black hole threshold

    International Nuclear Information System (INIS)

    Lue, A.; Weinberg, E.J.

    1999-01-01

    We present new analytic and numerical results for self-gravitating SU(2)-Higgs magnetic monopoles approaching the black hole threshold. Our investigation extends to large Higgs self-coupling, λ, a regime heretofore unexplored. When λ is small, the critical solution where a horizon first appears is extremal Reissner-Nordstroem outside the horizon but has a nonsingular interior. When λ is large, the critical solution is an extremal black hole with non-Abelian hair and a mass less than the extremal Reissner-Nordstroem value. The transition between these two regimes is reminiscent of a first-order phase transition. We analyze in detail the approach to these critical solutions as the Higgs expectation value is varied, and compare this analysis with the numerical results. copyright 1999 The American Physical Society

  14. Threshold-based Adaptive Detection for WSN

    KAUST Repository

    Abuzaid, Abdulrahman I.; Ahmed, Qasim Zeeshan; Alouini, Mohamed-Slim

    2014-01-01

    Efficient receiver designs for wireless sensor networks (WSNs) are becoming increasingly important. Cooperative WSNs communicated with the use of L sensors. As the receiver is constrained, it can only process U out of L sensors. Channel shortening and reduced-rank techniques were employed to design the preprocessing matrix. In this work, a receiver structure is proposed which combines the joint iterative optimization (JIO) algorithm and our proposed threshold selection criteria. This receiver structure assists in determining the optimal Uopt. It also provides the freedom to choose U

  15. Calibration of the neutron scintillation counter threshold

    International Nuclear Information System (INIS)

    Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.

    1978-01-01

    A method for calibrating the threshold of a neutron counter in the form of a 10x10x40 cm plastic scintillator is described. The method is based on the evaluation of the Compton boundary of γ-spectrum from the discrimination curve of counter loading. The results of calibration using 60 Co and 24 Na γ-sources are given. In order to eValuate the Compton edge rapidly, linear extrapolation of the linear part of the discrimination curve towards its intersection with the X axis is recommended. Special measurements have shown that the calibration results do not practically depend on the distance between the cathode of a photomultiplier and the place where collimated γ-radiation of the calibration source reaches the scintillator

  16. Gauge threshold corrections for local string models

    International Nuclear Information System (INIS)

    Conlon, Joseph P.

    2009-01-01

    We study gauge threshold corrections for local brane models embedded in a large compact space. A large bulk volume gives important contributions to the Konishi and super-Weyl anomalies and the effective field theory analysis implies the unification scale should be enhanced in a model-independent way from M s to RM s . For local D3/D3 models this result is supported by the explicit string computations. In this case the scale RM s comes from the necessity of global cancellation of RR tadpoles sourced by the local model. We also study D3/D7 models and discuss discrepancies with the effective field theory analysis. We comment on phenomenological implications for gauge coupling unification and for the GUT scale.

  17. Thresholds of allergenic proteins in foods

    International Nuclear Information System (INIS)

    Hourihane, Jonathan O'B.; Knulst, Andre C.

    2005-01-01

    Threshold doses or Estimated Eliciting Doses (EEDs) represent an important new field of research in food allergy. Clinicians and regulators have embraced some toxicological concepts such as LOAEL and NOAEL and applied them to an area of significant clinical uncertainty and interest. The impact of intrinsic human factors (e.g., asthma and exercise) and extrinsic event factors (e.g., season, location and especially dose of allergen) on a future allergic reaction in the community needs to be considered carefully when interpreting results of clinical and research low-dose food challenges. The ongoing cooperation of food allergy research groups in medicine, food science and government will surely deliver results of the highest importance to the wider communities of allergology, food science and technology and the increasing number of allergic consumers

  18. Two percolation thresholds due to geometrical effects: experimental and simulated results

    International Nuclear Information System (INIS)

    Nettelblad, B; Martensson, E; Oenneby, C; Gaefvert, U; Gustafsson, A

    2003-01-01

    The electrical properties of a mixture of ethylene-propylene-diene monomer rubber and silicon carbide (SiC) have been measured as a function of filler concentration. It was found that mixtures containing angular SiC grains have a conductivity that displays not one, but two percolation thresholds. Different types of contacts between the conducting particles, being represented by edge and face connections, respectively, can explain the phenomenon. The two percolation thresholds are obtained at volume fractions of about 0.25 and 0.40, respectively. These values are higher than those predicted by theory, which can be explained by dispersion effects with only one phase being granular and the other being continuous. The value of the conductivity at the central plateau was found to be close to the geometric mean of the limiting conductivities at low and high concentrations. This is in good agreement with theory. With rounded SiC grains only one threshold is obtained, which is consistent with only one type of contact. The concentration dependence of the conductivity was simulated using a three-dimensional impedance network model that incorporates both edge and face contacts. The double-threshold behaviour also appears in the calculations. By dispersing the conducting particles more evenly than random, the thresholds are shifted towards higher concentrations as observed in the experiments

  19. Relieving dyspnoea by non-invasive ventilation decreases pain thresholds in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Dangers, Laurence; Laviolette, Louis; Georges, Marjolaine; Gonzalez-Bermejo, Jésus; Rivals, Isabelle; Similowski, Thomas; Morelot-Panzini, Capucine

    2017-03-01

    Dyspnoea is a threatening sensation of respiratory discomfort that presents many similarities with pain. Experimental dyspnoea in healthy subjects induces analgesia. This 'dyspnoea-pain counter-irritation' could, in reverse, imply that relieving dyspnoea in patients with chronic respiratory diseases would lower their pain thresholds. We first determined pressure pain thresholds in 25 healthy volunteers (22-31 years; 13 men; handheld algometer), during unloaded breathing (BASELINE) and during inspiratory threshold loading (ITL). Two levels of loading were used, adjusted to induce dyspnoea self-rated at 60% or 80% of a 10 cm visual analogue scale (ITL6 and ITL8). 18 patients with chronic respiratory failure due to amyotrophic lateral sclerosis (ALS) were then studied during unassisted breathing and after 30 and 60 min of non-invasive ventilation-NIV30 and NIV60-(same dyspnoea evaluation). In healthy volunteers, pressure pain thresholds increased significantly in the deltoid during ITL6 (pNIV30 and NIV60 (pNIV in patients with ALS having respiratory failure is associated with decreased pressure pain thresholds. Clinical implications have yet to be determined, but this observation suggests that patients with ALS could become more susceptible to pain after the institution of NIV, hence the need for reinforced attention towards potentially painful diagnostic and therapeutic interventions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  20. Social Thresholds and their Translation into Social-ecological Management Practices

    Directory of Open Access Journals (Sweden)

    Lisa Christensen

    2012-03-01

    Full Text Available The objective of this paper is to provide a preliminary discussion of how to improve our conceptualization of social thresholds using (1 a more sociological analysis of social resilience, and (2 results from research carried out in collaboration with the Champagne and Aishihik First Nations of the Yukon Territory, Canada. Our sociological analysis of the concept of resilience begins with a review of the literature followed by placement of the concept in the domain of sociological theory to gain insight into its strengths and limitations. A new notion of social thresholds is proposed and case study research discussed to support the proposition. Our findings suggest that rather than view social thresholds as breakpoints between two regimes, as thresholds are typically conceived in the resilience literature, that they be viewed in terms of collectively recognized points that signify new experiences. Some examples of thresholds identified in our case study include power in decision making, level of healing from historical events, and a preference for small-scale development over large capital intensive projects.

  1. Impact of Thresholds and Load Patterns when Executing HPC Applications with Cloud Elasticity

    Directory of Open Access Journals (Sweden)

    Vinicius Facco Rodrigues

    2016-04-01

    Full Text Available Elasticity is one of the most known capabilities related to cloud computing, being largely deployed reactively using thresholds. In this way, maximum and minimum limits are used to drive resource allocation and deallocation actions, leading to the following problem statements: How can cloud users set the threshold values to enable elasticity in their cloud applications? And what is the impact of the application’s load pattern in the elasticity? This article tries to answer these questions for iterative high performance computing applications, showing the impact of both thresholds and load patterns on application performance and resource consumption. To accomplish this, we developed a reactive and PaaS-based elasticity model called AutoElastic and employed it over a private cloud to execute a numerical integration application. Here, we are presenting an analysis of best practices and possible optimizations regarding the elasticity and HPC pair. Considering the results, we observed that the maximum threshold influences the application time more than the minimum one. We concluded that threshold values close to 100% of CPU load are directly related to a weaker reactivity, postponing resource reconfiguration when its activation in advance could be pertinent for reducing the application runtime.

  2. Threshold Games and Cooperation on Multiplayer Graphs.

    Directory of Open Access Journals (Sweden)

    Kaare B Mikkelsen

    Full Text Available The study investigates the effect on cooperation in multiplayer games, when the population from which all individuals are drawn is structured-i.e. when a given individual is only competing with a small subset of the entire population.To optimize the focus on multiplayer effects, a class of games were chosen for which the payoff depends nonlinearly on the number of cooperators-this ensures that the game cannot be represented as a sum of pair-wise interactions, and increases the likelihood of observing behaviour different from that seen in two-player games. The chosen class of games are named "threshold games", and are defined by a threshold, M > 0, which describes the minimal number of cooperators in a given match required for all the participants to receive a benefit. The model was studied primarily through numerical simulations of large populations of individuals, each with interaction neighbourhoods described by various classes of networks.When comparing the level of cooperation in a structured population to the mean-field model, we find that most types of structure lead to a decrease in cooperation. This is both interesting and novel, simply due to the generality and breadth of relevance of the model-it is likely that any model with similar payoff structure exhibits related behaviour. More importantly, we find that the details of the behaviour depends to a large extent on the size of the immediate neighbourhoods of the individuals, as dictated by the network structure. In effect, the players behave as if they are part of a much smaller, fully mixed, population, which we suggest an expression for.

  3. Temperature threshold for burn injury: an oximeter safety study.

    Science.gov (United States)

    Greenhalgh, David G; Lawless, Mary Beth; Chew, Bradford B; Crone, Willem A; Fein, Michael E; Palmieri, Tina L

    2004-01-01

    Pulse oximeters have become essential devices for evaluating and monitoring patient oxygenation. The probe emits a small amount of heat into the skin in the process of signal detection. Regulations set by the Food and Drug Administration currently limit the maximum allowable temperature of an oximeter probe to 41 degrees C. As a result of the prolonged exposure of extremities to these devices, we sought to determine the actual temperature threshold for burn injury in patients. Eighteen patients undergoing surgery for removal of redundant skin (abdominoplasty, breast reduction) consented to the application of a temperature-controlled custom probe with four light-emitting diodes that had temperatures set randomly at the expected threshold for burn injury (42.5 degrees C, 43 degrees C, 43.5 degrees C, and 44 degrees C). The probe was left in place for 8 hours (or less if significant pain was noted). The sites covered by the probes were then checked for signs of injury. On the next day, the redundant skin was removed as a scheduled procedure, and histopathology was performed to detect the extent of burn injury. The study was approved by the local institutional research board. Two patients were excluded because of technical problems with the probe, one of whom had the probe turned off because of pain. The only observed sign of injury was either erythema or a superficial blister that was usually unobservable or slightly red at operation. These subtle signs of a burn were noted in one patient at 43 degrees C, four at 43.5 degrees C, and nine at 44 degrees C. No burns were noted in two patients. Minimal or no signs of injury frequently were noted by histopathology. Pulse oximeter probes are safe up to a temperature of 43 degrees C for at least 8 hours in well-perfused skin. Above that temperature, there is a risk of burn injury. Performing temperature threshold tests in redundant skin that is planned for excision is a potential method for testing the safety of devices or

  4. Catastrophic Disruption Threshold and Maximum Deflection from Kinetic Impact

    Science.gov (United States)

    Cheng, A. F.

    2017-12-01

    The use of a kinetic impactor to deflect an asteroid on a collision course with Earth was described in the NASA Near-Earth Object Survey and Deflection Analysis of Alternatives (2007) as the most mature approach for asteroid deflection and mitigation. The NASA DART mission will demonstrate asteroid deflection by kinetic impact at the Potentially Hazardous Asteroid 65803 Didymos in October, 2022. The kinetic impactor approach is considered to be applicable with warning times of 10 years or more and with hazardous asteroid diameters of 400 m or less. In principle, a larger kinetic impactor bringing greater kinetic energy could cause a larger deflection, but input of excessive kinetic energy will cause catastrophic disruption of the target, leaving possibly large fragments still on collision course with Earth. Thus the catastrophic disruption threshold limits the maximum deflection from a kinetic impactor. An often-cited rule of thumb states that the maximum deflection is 0.1 times the escape velocity before the target will be disrupted. It turns out this rule of thumb does not work well. A comparison to numerical simulation results shows that a similar rule applies in the gravity limit, for large targets more than 300 m, where the maximum deflection is roughly the escape velocity at momentum enhancement factor β=2. In the gravity limit, the rule of thumb corresponds to pure momentum coupling (μ=1/3), but simulations find a slightly different scaling μ=0.43. In the smaller target size range that kinetic impactors would apply to, the catastrophic disruption limit is strength-controlled. A DART-like impactor won't disrupt any target asteroid down to significantly smaller size than the 50 m below which a hazardous object would not penetrate the atmosphere in any case unless it is unusually strong.

  5. Threshold Considerations and Wetland Reclamation in Alberta's Mineable Oil Sands

    Directory of Open Access Journals (Sweden)

    Lee Foote

    2012-03-01

    Full Text Available Oil sand extraction in Alberta, Canada is a multibillion dollar industry operating over 143 km² of open pit mining and 4600 km² of other bitumen strata in northern boreal forests. Oil production contributes to Canada-wide GDP, creates socio-cultural problems, provides energy exports and employment, and carries environmental risks regarding long-term reclamation uncertainties. Of particular concern are the implications for wetlands and water supply management. Mining of oil sands is very attractive because proven reserves of known quality occur in an accessible, politically stable environment with existing infrastructure and an estimated 5.5 billion extractable barrels to be mined over the next five decades. Extraction occurs under a set of limiting factors or thresholds including: limited social tolerance at local to international levels for externalities of oil sand production; water demands > availability; limited natural gas supplies for oil processing leading to proposals for hydroelectric dams and nuclear reactors to be constructed; difficulties in reclaiming sufficient habitat area to replace those lost. Replacement of the 85 km² of peat-forming wetlands forecast to be destroyed appears unlikely. Over 840 billion liters of toxic fluid byproducts are currently held in 170 km² of open reservoirs without any known process to purify this water in meaningful time frames even as some of it leaches into adjacent lands and rivers. Costs for wetland reclamation are high with estimates of $4 to $13 billion, or about 6% of the net profits generated from mining those sites. This raises a social equity question of how much reclamation is appropriate. Time frames for economic, political, and ecological actions are not well aligned. Local people on or near mine sites have had to change their area use for decades and have been affected by industrial development. Examining mining effects to estimate thresholds of biophysical realities, time scales

  6. Representation of dynamical stimuli in populations of threshold neurons.

    Directory of Open Access Journals (Sweden)

    Tatjana Tchumatchenko

    2011-10-01

    Full Text Available Many sensory or cognitive events are associated with dynamic current modulations in cortical neurons. This raises an urgent demand for tractable model approaches addressing the merits and limits of potential encoding strategies. Yet, current theoretical approaches addressing the response to mean- and variance-encoded stimuli rarely provide complete response functions for both modes of encoding in the presence of correlated noise. Here, we investigate the neuronal population response to dynamical modifications of the mean or variance of the synaptic bombardment using an alternative threshold model framework. In the variance and mean channel, we provide explicit expressions for the linear and non-linear frequency response functions in the presence of correlated noise and use them to derive population rate response to step-like stimuli. For mean-encoded signals, we find that the complete response function depends only on the temporal width of the input correlation function, but not on other functional specifics. Furthermore, we show that both mean- and variance-encoded signals can relay high-frequency inputs, and in both schemes step-like changes can be detected instantaneously. Finally, we obtain the pairwise spike correlation function and the spike triggered average from the linear mean-evoked response function. These results provide a maximally tractable limiting case that complements and extends previous results obtained in the integrate and fire framework.

  7. Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

    Science.gov (United States)

    Peres, David J.; Cancelliere, Antonino; Greco, Roberto; Bogaard, Thom A.

    2018-03-01

    Uncertainty in rainfall datasets and landslide inventories is known to have negative impacts on the assessment of landslide-triggering thresholds. In this paper, we perform a quantitative analysis of the impacts of uncertain knowledge of landslide initiation instants on the assessment of rainfall intensity-duration landslide early warning thresholds. The analysis is based on a synthetic database of rainfall and landslide information, generated by coupling a stochastic rainfall generator and a physically based hydrological and slope stability model, and is therefore error-free in terms of knowledge of triggering instants. This dataset is then perturbed according to hypothetical reporting scenarios that allow simulation of possible errors in landslide-triggering instants as retrieved from historical archives. The impact of these errors is analysed jointly using different criteria to single out rainfall events from a continuous series and two typical temporal aggregations of rainfall (hourly and daily). The analysis shows that the impacts of the above uncertainty sources can be significant, especially when errors exceed 1 day or the actual instants follow the erroneous ones. Errors generally lead to underestimated thresholds, i.e. lower than those that would be obtained from an error-free dataset. Potentially, the amount of the underestimation can be enough to induce an excessive number of false positives, hence limiting possible landslide mitigation benefits. Moreover, the uncertain knowledge of triggering rainfall limits the possibility to set up links between thresholds and physio-geographical factors.

  8. Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

    Directory of Open Access Journals (Sweden)

    D. J. Peres

    2018-03-01

    Full Text Available Uncertainty in rainfall datasets and landslide inventories is known to have negative impacts on the assessment of landslide-triggering thresholds. In this paper, we perform a quantitative analysis of the impacts of uncertain knowledge of landslide initiation instants on the assessment of rainfall intensity–duration landslide early warning thresholds. The analysis is based on a synthetic database of rainfall and landslide information, generated by coupling a stochastic rainfall generator and a physically based hydrological and slope stability model, and is therefore error-free in terms of knowledge of triggering instants. This dataset is then perturbed according to hypothetical reporting scenarios that allow simulation of possible errors in landslide-triggering instants as retrieved from historical archives. The impact of these errors is analysed jointly using different criteria to single out rainfall events from a continuous series and two typical temporal aggregations of rainfall (hourly and daily. The analysis shows that the impacts of the above uncertainty sources can be significant, especially when errors exceed 1 day or the actual instants follow the erroneous ones. Errors generally lead to underestimated thresholds, i.e. lower than those that would be obtained from an error-free dataset. Potentially, the amount of the underestimation can be enough to induce an excessive number of false positives, hence limiting possible landslide mitigation benefits. Moreover, the uncertain knowledge of triggering rainfall limits the possibility to set up links between thresholds and physio-geographical factors.

  9. Speech-in-Noise Tests and Supra-threshold Auditory Evoked Potentials as Metrics for Noise Damage and Clinical Trial Outcome Measures.

    Science.gov (United States)

    Le Prell, Colleen G; Brungart, Douglas S

    2016-09-01

    In humans, the accepted clinical standards for detecting hearing loss are the behavioral audiogram, based on the absolute detection threshold of pure-tones, and the threshold auditory brainstem response (ABR). The audiogram and the threshold ABR are reliable and sensitive measures of hearing thresholds in human listeners. However, recent results from noise-exposed animals demonstrate that noise exposure can cause substantial neurodegeneration in the peripheral auditory system without degrading pure-tone audiometric thresholds. It has been suggested that clinical measures of auditory performance conducted with stimuli presented above the detection threshold may be more sensitive than the behavioral audiogram in detecting early-stage noise-induced hearing loss in listeners with audiometric thresholds within normal limits. Supra-threshold speech-in-noise testing and supra-threshold ABR responses are reviewed here, given that they may be useful supplements to the behavioral audiogram for assessment of possible neurodegeneration in noise-exposed listeners. Supra-threshold tests may be useful for assessing the effects of noise on the human inner ear, and the effectiveness of interventions designed to prevent noise trauma. The current state of the science does not necessarily allow us to define a single set of best practice protocols. Nonetheless, we encourage investigators to incorporate these metrics into test batteries when feasible, with an effort to standardize procedures to the greatest extent possible as new reports emerge.

  10. Threshold responses of songbirds to long-term timber management on an active industrial forest

    Science.gov (United States)

    Becker, Douglas A.; Wood, Petra Bohall; Keyser, Patrick D.; Wigley, T. Bently; Dellinger, Rachel; Weakland, Cathy A.

    2011-01-01

    confidence intervals for individual species overlapped their guild threshold intervals 91% of the time. Even though relative abundance of most species (80%) did not decline as the area affected by timber management increased, implementing management at or below our approximate forest-interior and interior-edge harvest thresholds would reduce the number of declining species by half, maintain higher relative abundances of four species with a net decline in abundance but that peaked in abundance mid-study, and maintain higher relative abundances of ten additional species. In contrast, this management strategy also would prevent the increase in relative abundance of seven species and limit the increase in abundance of three species that increased throughout the study.

  11. Inertial cavitation threshold of nested microbubbles.

    Science.gov (United States)

    Wallace, N; Dicker, S; Lewin, Peter; Wrenn, S P

    2015-04-01

    Cavitation of ultrasound contrast agents (UCAs) promotes both beneficial and detrimental bioeffects in vivo (Radhakrishnan et al., 2013) [1]. The ability to determine the inertial cavitation threshold of UCA microbubbles has potential application in contrast imaging, development of therapeutic agents, and evaluation of localized effects on the body (Ammi et al., 2006) [2]. This study evaluates a novel UCA and its inertial cavitation behavior as determined by a home built cavitation detection system. Two 2.25 MHz transducers are placed at a 90° angle to one another where one transducer is driven by a high voltage pulser and the other transducer receives the signal from the oscillating microbubble. The sample chamber is placed in the overlap of the focal region of the two transducers where the microbubbles are exposed to a pulser signal consisting of 600 pulse trains per experiment at a pulse repetition frequency of 5 Hz where each train has four pulses of four cycles. The formulation being analyzed is comprised of an SF6 microbubble coated by a DSPC PEG-3000 monolayer nested within a poly-lactic acid (PLA) spherical shell. The effect of varying shell diameters and microbubble concentration on cavitation threshold profile for peak negative pressures ranging from 50 kPa to 2 MPa are presented and discussed in this paper. The nesting shell decreases inertial cavitation events from 97.96% for an un-nested microbubble to 19.09% for the same microbubbles nested within a 2.53 μm shell. As shell diameter decreases, the percentage of inertially cavitating microbubbles also decreases. For nesting formulations with average outer capsule diameters of 20.52, 14.95, 9.95, 5.55, 2.53, and 1.95 μm, the percentage of sample destroyed at 1 MPa was 51.02, 38.94, 33.25, 25.27, 19.09, and 5.37% respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. The asymmetry of the impact of oil price shocks on economic activities: an application of the multivariate threshold model

    International Nuclear Information System (INIS)

    Bwo-Nung Huang; National Chia-Yi University; Hwang, M.J.; Hsiao-Ping Peng

    2005-01-01

    This paper applies the multivariate threshold model to investigate the impacts of an oil price change and its volatility on economic activities (changes in industrial production and real stock returns). The statistical test on the existence of a threshold effect indicates that a threshold value does exist. Using monthly data of the US, Canada, and Japan during the period from 1970 to 2002, we conclude: (i) the optimal threshold level seems to vary according to how an economy depends on imported oil and the attitude towards adopting energy-saving technology; (ii) an oil price change or its volatility has a limited impact on the economies if the change is below the threshold levels; (iii) if the change is above threshold levels, it appears that the change in oil price better explains macroeconomic variables than the volatility of the oil price; and (iv) if the change is above threshold levels, a change in oil price or its volatility explains the model better than the real interest rate. (author)

  13. Towards a unifying basis of auditory thresholds: binaural summation.

    Science.gov (United States)

    Heil, Peter

    2014-04-01

    Absolute auditory threshold decreases with increasing sound duration, a phenomenon explainable by the assumptions that the sound evokes neural events whose probabilities of occurrence are proportional to the sound's amplitude raised to an exponent of about 3 and that a constant number of events are required for threshold (Heil and Neubauer, Proc Natl Acad Sci USA 100:6151-6156, 2003). Based on this probabilistic model and on the assumption of perfect binaural summation, an equation is derived here that provides an explicit expression of the binaural threshold as a function of the two monaural thresholds, irrespective of whether they are equal or unequal, and of the exponent in the model. For exponents >0, the predicted binaural advantage is largest when the two monaural thresholds are equal and decreases towards zero as the monaural threshold difference increases. This equation is tested and the exponent derived by comparing binaural thresholds with those predicted on the basis of the two monaural thresholds for different values of the exponent. The thresholds, measured in a large sample of human subjects with equal and unequal monaural thresholds and for stimuli with different temporal envelopes, are compatible only with an exponent close to 3. An exponent of 3 predicts a binaural advantage of 2 dB when the two ears are equally sensitive. Thus, listening with two (equally sensitive) ears rather than one has the same effect on absolute threshold as doubling duration. The data suggest that perfect binaural summation occurs at threshold and that peripheral neural signals are governed by an exponent close to 3. They might also shed new light on mechanisms underlying binaural summation of loudness.

  14. Consolidation by Prefabricated Vertical Drains with a Threshold Gradient

    OpenAIRE

    Xiao Guo; Kang-He Xie; Yue-Bao Deng

    2014-01-01

    This paper shows the development of an approximate analytical solution of radial consolidation by prefabricated vertical drains with a threshold gradient. To understand the effect of the threshold gradient on consolidation, a parametric analysis was performed using the present solution. The applicability of the present solution was demonstrated in two cases, wherein the comparisons with Hansbo’s results and observed data were conducted. It was found that (1) the flow with the threshold gradie...

  15. Development of threshold action criteria for light water reactors

    International Nuclear Information System (INIS)

    Okrent, D.; Baldewicz, W.L.

    1982-06-01

    A survey of recently threshold criteria for regulatory action on LWRs is presented together with some commentary. This is followed by a new proposal for threshold action criteria which includes some different risk attributes than are found in previous criteria. Some preliminary risk values are suggested for the criteria and then evaluated in terms of a few hypothetical accident scenarios. Finally, several licensing issues are examined in terms of various threshold action criteria

  16. Simplified Threshold RSA with Adaptive and Proactive Security

    DEFF Research Database (Denmark)

    Almansa Guerra, Jesus Fernando; Damgård, Ivan Bjerre; Nielsen, Jesper Buus

    2006-01-01

    We present the currently simplest, most efficient, optimally resilient, adaptively secure, and proactive threshold RSA scheme. A main technical contribution is a new rewinding strategy for analysing threshold signature schemes. This new rewinding strategy allows to prove adaptive security...... of a proactive threshold signature scheme which was previously assumed to be only statically secure. As a separate contribution we prove that our protocol is secure in the UC framework....

  17. Pathways to extinction: beyond the error threshold.

    Science.gov (United States)

    Manrubia, Susanna C; Domingo, Esteban; Lázaro, Ester

    2010-06-27

    Since the introduction of the quasispecies and the error catastrophe concepts for molecular evolution by Eigen and their subsequent application to viral populations, increased mutagenesis has become a common strategy to cause the extinction of viral infectivity. Nevertheless, the high complexity of virus populations has shown that viral extinction can occur through several other pathways apart from crossing an error threshold. Increases in the mutation rate enhance the appearance of defective forms and promote the selection of mechanisms that are able to counteract the accelerated appearance of mutations. Current models of viral evolution take into account more realistic scenarios that consider compensatory and lethal mutations, a highly redundant genotype-to-phenotype map, rough fitness landscapes relating phenotype and fitness, and where phenotype is described as a set of interdependent traits. Further, viral populations cannot be understood without specifying the characteristics of the environment where they evolve and adapt. Altogether, it turns out that the pathways through which viral quasispecies go extinct are multiple and diverse.

  18. Synergistic effects in threshold models on networks

    Science.gov (United States)

    Juul, Jonas S.; Porter, Mason A.

    2018-01-01

    Network structure can have a significant impact on the propagation of diseases, memes, and information on social networks. Different types of spreading processes (and other dynamical processes) are affected by network architecture in different ways, and it is important to develop tractable models of spreading processes on networks to explore such issues. In this paper, we incorporate the idea of synergy into a two-state ("active" or "passive") threshold model of social influence on networks. Our model's update rule is deterministic, and the influence of each meme-carrying (i.e., active) neighbor can—depending on a parameter—either be enhanced or inhibited by an amount that depends on the number of active neighbors of a node. Such a synergistic system models social behavior in which the willingness to adopt either accelerates or saturates in a way that depends on the number of neighbors who have adopted that behavior. We illustrate that our model's synergy parameter has a crucial effect on system dynamics, as it determines whether degree-k nodes are possible or impossible to activate. We simulate synergistic meme spreading on both random-graph models and networks constructed from empirical data. Using a heterogeneous mean-field approximation, which we derive under the assumption that a network is locally tree-like, we are able to determine which synergy-parameter values allow degree-k nodes to be activated for many networks and for a broad family of synergistic models.

  19. Threshold nonlinear absorption in Zeeman transitions

    International Nuclear Information System (INIS)

    Narayanan, Andal; Hazra, Abheera; Sandhya, S N

    2010-01-01

    We experimentally study the absorption spectroscopy from a collection of gaseous 87 Rb atoms at room temperature irradiated with three fields. Two of these fields are in a pump-probe saturation absorption configuration. The third field co-propagates with the pump field. The three fields address Zeeman degenerate transitions between hyperfine levels 5S 1/2 , F = 1 and 5P 3/2 , F = 0, F = 1 around the D2 line. We find a sub-natural absorption resonance in the counter-propagating probe field for equal detunings of all three fields. This absorption arises in conjunction with the appearance of increased transmission due to electro-magnetically induced transparency in the co-propagating fields. The novel feature of this absorption is its onset only for the blue of 5P 3/2 , F = 0, as the laser frequency is scanned through the excited states 5P 3/2 , F = 0, F = 1 and F = 2. The absorption rapidly rises to near maximum values within a narrow band of frequency near 5P 3/2 , F = 0. Our experimental results are compared with a dressed atom model. We find the threshold absorption to be a result of coherent interaction between the dressed states of our system.

  20. Microplastic Effect Thresholds for Freshwater Benthic Macroinvertebrates

    Science.gov (United States)

    2018-01-01

    Now that microplastics have been detected in lakes, rivers, and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates with different species traits, using a wide range of microplastic concentrations. Standardized 28 days single species bioassays were performed under environmentally relevant exposure conditions using polystyrene microplastics (20–500 μm) mixed with sediment at concentrations ranging from 0 to 40% sediment dry weight (dw). Microplastics caused no effects on the survival of Gammarus pulex, Hyalella azteca, Asellus aquaticus, Sphaerium corneum, and Tubifex spp. and no effects were found on the reproduction of Lumbriculus variegatus. No significant differences in growth were found for H. azteca, A. aquaticus, S. corneum, L. variegatus, and Tubifex spp. However, G. pulex showed a significant reduction in growth (EC10 = 1.07% sediment dw) and microplastic uptake was proportional with microplastic concentrations in sediment. These results indicate that although the risks of environmentally realistic concentrations of microplastics may be low, they still may affect the biodiversity and the functioning of aquatic communities which after all also depend on the sensitive species. PMID:29337537

  1. Nuclear threshold countries in the Third World

    International Nuclear Information System (INIS)

    Stahl, K.

    1990-01-01

    The article analyses the nuclear-technological capacities and the danger of nuclear weapons proliferation in the six nuclear threshold countries: Argentina, Brazil, India, Pakistan, Israel and South Africa. All six states have developed sensitive nuclear facilities that are not covered by IAEA-safeguards. The risk of nuclear proliferation in Argentina and Brazil is considered at present as non-existent. The economic and especially the nuclear cooperation between the two states and the mutual visits of the unsafeguarded nuclear facilities has promoted a process of confidence building and political detente between them. The risk of nuclear weapons proliferation in the Middle East is considered high. It is estimated that Israel already has built up a nuclear weapons arsenal. The growing political influence of nationalistic groups in India and Pakistan, that favour a course of confrontation between the two states, have augmented the risk of nuclear proliferation in both states. South Africa is economically and militarily clearly dominating its black ruled neighbours. The Apartheid-regime is at present negociating with the nuclear weapons states about its adherence to the NPT, but demands political, economic and military concessions in exchange for its adherence to the treaty. (orig./HSCH) [de

  2. MOS Current Mode Logic Near Threshold Circuits

    Directory of Open Access Journals (Sweden)

    Alexander Shapiro

    2014-06-01

    Full Text Available Near threshold circuits (NTC are an attractive and promising technology that provides significant power savings with some delay penalty. The combination of NTC technology with MOS current mode logic (MCML is examined in this work. By combining MCML with NTC, the constant power consumption of MCML is reduced to leakage power levels that can be tolerated in certain modern applications. Additionally, the speed of NTC is improved due to the high speed nature of MCML technology. A 14 nm Fin field effect transistor (FinFET technology is used to evaluate these combined circuit techniques. A 32-bit Kogge Stone adder is chosen as a demonstration vehicle for feasibility analysis. MCML with NTC is shown to yield enhanced power efficiency when operated above 1 GHz with a 100% activity factor as compared to standard CMOS. MCML with NTC is more power efficient than standard CMOS beyond 9 GHz over a wide range of activity factors. MCML with NTC also exhibits significantly lower noise levels as compared to standard CMOS. The results of the analysis demonstrate that pairing NTC and MCML is efficient when operating at high frequencies and activity factors.

  3. Energy Threshold Hypothesis for Household Consumption

    International Nuclear Information System (INIS)

    Ortiz, Samira; Castro-Sitiriche, Marcel; Amador, Isamar

    2017-01-01

    A strong positive relationship among quality of life and electricity consumption at impoverished countries is found in many studies. However, previous work has presented that the positive relationship does not hold beyond certain electricity consumption threshold. Consequently, there is a need of exploring the possibility for communities to live with sustainable level of energy consumption without sacrificing their quality of life. The Gallup-Healthways Report measures global citizen’s wellbeing. This paper provides a new outlook using these elements to explore the relationships among actual percentage of population thriving in most countries and their energy consumption. A measurement of efficiency is computed to determine an adjusted relative social value of energy considering the variability in the happy life years as a function of electric power consumption. Adjustment is performed so single components don’t dominate in the measurement. It is interesting to note that the countries with the highest relative social value of energy are in the top 10 countries of the Gallup report.

  4. Threshold states in /sup 26/Al revisited

    Energy Technology Data Exchange (ETDEWEB)

    Champagne, A E; McDonald, A B; Wang, T F; Howard, A J; Magnus, P V; Parker, P D

    1986-03-31

    Threshold states in /sup 26/Al have been re-examined using the /sup 27/Al(/sup 3/He,..cap alpha..)/sup 26/Al and /sup 25/Mg(/sup 3/He,d..gamma..)/sup 26/Al reactions in order to resolve apparent ambiguities in some of the previously reported properties of these states. In particular, the s-wave resonance strength reported at E=37 keV is now found to be located at E/sub c.m./=57.54 keV, and the proton width for the 374 keV resonance has been revised to GAMMA/sub p/=0.82 eV. These results have been used to calculate a new resonance strength of ..omega gamma..= 1.6 x 10/sup -13/ eV for the 57.54 keV resonance. As a result, the stellar production rate for /sup 26/Al is increased by a factor approx.=3-38 for temperatures T/sub 9/=0.05-0.1.

  5. Image thresholding in the high resolution target movement monitor

    Science.gov (United States)

    Moss, Randy H.; Watkins, Steve E.; Jones, Tristan H.; Apel, Derek B.; Bairineni, Deepti

    2009-03-01

    Image thresholding in the High Resolution Target Movement Monitor (HRTMM) is examined. The HRTMM was developed at the Missouri University of Science and Technology to detect and measure wall movements in underground mines to help reduce fatality and injury rates. The system detects the movement of a target with sub-millimeter accuracy based on the images of one or more laser dots projected on the target and viewed by a high-resolution camera. The relative position of the centroid of the laser dot (determined by software using thresholding concepts) in the images is the key factor in detecting the target movement. Prior versions of the HRTMM set the image threshold based on a manual, visual examination of the images. This work systematically examines the effect of varying threshold on the calculated centroid position and describes an algorithm for determining a threshold setting. First, the thresholding effects on the centroid position are determined for a stationary target. Plots of the centroid positions as a function of varying thresholds are obtained to identify clusters of thresholds for which the centroid position does not change for stationary targets. Second, the target is moved away from the camera in sub-millimeter increments and several images are obtained at each position and analyzed as a function of centroid position, target movement and varying threshold values. With this approach, the HRTMM can accommodate images in batch mode without the need for manual intervention. The capability for the HRTMM to provide automated, continuous monitoring of wall movement is enhanced.

  6. Determinants of Change in the Cost-effectiveness Threshold.

    Science.gov (United States)

    Paulden, Mike; O'Mahony, James; McCabe, Christopher

    2017-02-01

    The cost-effectiveness threshold in health care systems with a constrained budget should be determined by the cost-effectiveness of displacing health care services to fund new interventions. Using comparative statics, we review some potential determinants of the threshold, including the budget for health care, the demand for existing health care interventions, the technical efficiency of existing interventions, and the development of new health technologies. We consider the anticipated direction of impact that would affect the threshold following a change in each of these determinants. Where the health care system is technically efficient, an increase in the health care budget unambiguously raises the threshold, whereas an increase in the demand for existing, non-marginal health interventions unambiguously lowers the threshold. Improvements in the technical efficiency of existing interventions may raise or lower the threshold, depending on the cause of the improvement in efficiency, whether the intervention is already funded, and, if so, whether it is marginal. New technologies may also raise or lower the threshold, depending on whether the new technology is a substitute for an existing technology and, again, whether the existing technology is marginal. Our analysis permits health economists and decision makers to assess if and in what direction the threshold may change over time. This matters, as threshold changes impact the cost-effectiveness of interventions that require decisions now but have costs and effects that fall in future periods.

  7. Low heat pain thresholds in migraineurs between attacks.

    Science.gov (United States)

    Schwedt, Todd J; Zuniga, Leslie; Chong, Catherine D

    2015-06-01

    Between attacks, migraine is associated with hypersensitivities to sensory stimuli. The objective of this study was to investigate hypersensitivity to pain in migraineurs between attacks. Cutaneous heat pain thresholds were measured in 112 migraineurs, migraine free for ≥ 48 hours, and 75 healthy controls. Pain thresholds at the head and at the arm were compared between migraineurs and controls using two-tailed t-tests. Among migraineurs, correlations between heat pain thresholds and headache frequency, allodynia symptom severity, and time interval until next headache were calculated. Migraineurs had lower pain thresholds than controls at the head (43.9 ℃ ± 3.2 ℃ vs. 45.1 ℃ ± 3.0 ℃, p = 0.015) and arm (43.2 ℃ ± 3.4 ℃ vs. 44.8 ℃ ± 3.3 ℃, p pain thresholds and headache frequency or allodynia symptom severity. For the 41 migraineurs for whom time to next headache was known, there were positive correlations between time to next headache and pain thresholds at the head (r = 0.352, p = 0.024) and arm (r = 0.312, p = 0.047). This study provides evidence that migraineurs have low heat pain thresholds between migraine attacks. Mechanisms underlying these lower pain thresholds could also predispose migraineurs to their next migraine attack, a hypothesis supported by finding positive correlations between pain thresholds and time to next migraine attack. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  8. Diagnostic thresholds for ambulatory blood pressure moving lower: a review based on a meta-analysis-clinical implications

    DEFF Research Database (Denmark)

    Hansen, T.W.; Kikuya, M.; Thijs, L.

    2008-01-01

    Upper limits of normal ambulatory blood pressure (ABP) have been a matter of debate in recent years. Current diagnostic thresholds for ABP rely mainly on statistical parameters derived from reference populations. Recent findings from the International Database of Ambulatory Blood Pressure...... in Relation to Cardiovascular Outcome (IDACO) provide outcome-driven thresholds for ABP. Rounded systolic/diastolic thresholds for optimal ABP were found to be 115/75 mm Hg for 24 hours, 120/80 mm Hg for daytime, and 100/65 mm Hg for nighttime. The corresponding rounded thresholds for normal ABP were 125...... database is therefore being updated with additional population cohorts to enable the construction of multifactorial risk score charts, which also include ABP Udgivelsesdato: 2008/5...

  9. Legislating thresholds for drug trafficking: a policy development case study from New South Wales, Australia.

    Science.gov (United States)

    Hughes, Caitlin Elizabeth; Ritter, Alison; Cowdery, Nicholas

    2014-09-01

    Legal thresholds are used in many parts of the world to define the quantity of illicit drugs over which possession is deemed "trafficking" as opposed to "possession for personal use". There is limited knowledge about why or how such laws were developed. In this study we analyse the policy processes underpinning the introduction and expansion of the drug trafficking legal threshold system in New South Wales (NSW), Australia. A critical legal and historical analysis was undertaken sourcing data from legislation, Parliamentary Hansard debates, government inquiries, police reports and research. A timeline of policy developments was constructed from 1970 until 2013 outlining key steps including threshold introduction (1970), expansion (1985), and wholesale revision (1988). We then critically analysed the drivers of each step and the roles played by formal policy actors, public opinion, research/data and the drug trafficking problem. We find evidence that while justified as a necessary tool for effective law enforcement of drug trafficking, their introduction largely preceded overt police calls for reform or actual increases in drug trafficking. Moreover, while the expansion from one to four thresholds had the intent of differentiating small from large scale traffickers, the quantities employed were based on government assumptions which led to "manifest problems" and the revision in 1988 of over 100 different quantities. Despite the revisions, there has remained no further formal review and new quantities for "legal highs" continue to be added based on assumption and an uncertain evidence-base. The development of legal thresholds for drug trafficking in NSW has been arbitrary and messy. That the arbitrariness persists from 1970 until the present day makes it hard to conclude the thresholds have been well designed. Our narrative provides a platform for future policy reform. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Thresholds of time dependent intergranular crack growth in a nickel disc alloy Alloy 720Li

    Directory of Open Access Journals (Sweden)

    Li Hangyue

    2014-01-01

    Full Text Available At high temperatures in air, introducing a dwell period at the peak stress of fatigue cycles promotes time dependent intergranular crack growth which can increase crack growth rates by upto a few orders of magnitude from the rates of transgranular fatigue crack growth in superalloys. It is expected that time dependent intergranular crack growth in nickel-based superalloys may not occur below a critical mechanical driving force, ΔKth−IG, analogous to a fatigue threshold (ΔKth and a critical temperature, Tth. In this study, dwell fatigue crack growth tests have been carefully designed and conducted on Alloy 720Li to examine such thresholds. Unlike a fatigue threshold, the threshold stress intensity factor range for intergranular crack growth is observed to be highly sensitive to microstructure, dwell time and test procedure. The near threshold crack growth behaviour is made complex by the interactions between grain boundary oxidation embrittlement and crack tip stress relaxation. In general, lower ΔKth−IG values are associated with finer grain size and/or shorter dwell times. Often a load increasing procedure promotes stress relaxation and tends to lead to higher ΔKth−IG. When there is limited stress relaxation at the crack tip, similar ΔKth−IG values are measured with load increasing and load shedding procedures. They are generally higher than the fatigue threshold (ΔKth despite faster crack growth rates (da/dN in the stable crack growth regime. Time dependent intergranular crack growth cannot be activated below a temperature of 500 ∘C.

  11. When is rational to order a diagnostic test, or prescribe treatment: the threshold model as an explanation of practice variation.

    Science.gov (United States)

    Djulbegovic, Benjamin; van den Ende, Jef; Hamm, Robert M; Mayrhofer, Thomas; Hozo, Iztok; Pauker, Stephen G

    2015-05-01

    The threshold model represents an important advance in the field of medical decision-making. It is a linchpin between evidence (which exists on the continuum of credibility) and decision-making (which is a categorical exercise - we decide to act or not act). The threshold concept is closely related to the question of rational decision-making. When should the physician act, that is order a diagnostic test, or prescribe treatment? The threshold model embodies the decision theoretic rationality that says the most rational decision is to prescribe treatment when the expected treatment benefit outweighs its expected harms. However, the well-documented large variation in the way physicians order diagnostic tests or decide to administer treatments is consistent with a notion that physicians' individual action thresholds vary. We present a narrative review summarizing the existing literature on physicians' use of a threshold strategy for decision-making. We found that the observed variation in decision action thresholds is partially due to the way people integrate benefits and harms. That is, explanation of variation in clinical practice can be reduced to a consideration of thresholds. Limited evidence suggests that non-expected utility threshold (non-EUT) models, such as regret-based and dual-processing models, may explain current medical practice better. However, inclusion of costs and recognition of risk attitudes towards uncertain treatment effects and comorbidities may improve the explanatory and predictive value of the EUT-based threshold models. The decision when to act is closely related to the question of rational choice. We conclude that the medical community has not yet fully defined criteria for rational clinical decision-making. The traditional notion of rationality rooted in EUT may need to be supplemented by reflective rationality, which strives to integrate all aspects of medical practice - medical, humanistic and socio-economic - within a coherent

  12. Some fundamental considerations on the dynamics of class B laser threshold crossing

    OpenAIRE

    Puccioni, G. P.; Wang, T.; Lippi, G. L.

    2016-01-01

    With the help of a simple rate equation model, we analyze the intrinsic dynamics of threshold crossing for Class B lasers. A thorough discussion of the characteristics and the limitations of this very commonly employed model, which provides excellent qualitative predictions on the laser behaviour, is offered. Approximate solutions for the population inversion and for the field intensity, up to the point where the latter reaches macroscopic levels, are found and discussed, together with the as...

  13. At-risk and intervention thresholds of occupational stress using a visual analogue scale

    Science.gov (United States)

    Pereira, Bruno; Moustafa, Farès; Naughton, Geraldine; Lesage, François-Xavier; Lambert, Céline

    2017-01-01

    Background The visual analogue scale (VAS) is widely used in clinical practice by occupational physicians to assess perceived stress in workers. However, a single cut-off (black-or-white decision) inadequately discriminates between workers with and without stress. We explored an innovative statistical approach to distinguish an at-risk population among stressed workers, and to establish a threshold over which an action is urgently required, via the use of two cut-offs. Methods Participants were recruited during annual work medical examinations by a random sample of workers from five occupational health centres. We previously proposed a single cut-off of VAS stress in comparison with the Perceived Stress Scale (PSS14). Similar methodology was used in the current study, along with a gray zone approach. The lower limit of the gray zone supports sensitivity (“at-risk” threshold; interpreted as requiring closer surveillance) and the upper limit supports specificity (i.e. “intervention” threshold–emergency action required). Results We included 500 workers (49.6% males), aged 40±11 years, with a PSS14 score of 3.8±1.4 and a VAS score of 4.0±2.4. Using a receiver operating characteristic curve and the PSS cut-off score of 7.2, the optimal VAS threshold was 6.8 (sensitivity = 0.89, specificity = 0.87). The lower and upper thresholds of the gray zone were 5 and 8.2, respectively. Conclusions We identified two clinically relevant cut-offs on the VAS of stress: a first cut-off of 5.0 for an at-risk population, and a second cut-off of 8.2 over which an action is urgently required. Future investigations into the relationships between this upper threshold and deleterious events are required. PMID:28586383

  14. Hexavalent chrome: threshold concept for carcinogenicity.

    Science.gov (United States)

    Jones, R E

    1990-03-01

    Certain hexavalent chromium (Cr6+) compounds when administered via inhalation at high doses have the potential to induce lung tumors in humans and experimental animals. Trivalent chromium (Cr3+) is an essential human and animal nutrient at levels of 50 to 200 micrograms/day. Recent data have shown that the human body is able to reduce Cr6+ to Cr3+. This reduction occurs in bodily fluids such as gastric juice, epithelial lining fluid of the respiratory tract, blood, and other fluids. Secondary reduction occurs at the cellular level by the cytosol, mitochondria, and microsomes. Thus, at low levels of exposure hexavalent chromium ions are reduced before the 6+ ions can interact with DNA unless the dose is sufficient to overwhelm the body's reduction capacity. This paper summarizes the available data concerning the reducing ability of the body and formulates the steps in the mechanism of cancer induction. These steps include: (1) only certain Cr6+ compounds have the capacity to interact with cellular components; (2) Cr6+ is reduced by body fluids and excess Cr6+ enters the cell (Cr3+ is poorly absorbed across membranes); (3) cellular organelles and the cytoplasm reduce Cr6+ to Cr3+; (4) excess Cr6+ can enter the nucleus; (5) Cr6+ reduction through 5+ and 4+ to 3+ has a potential to interact with the DNA molecule; and (6) if unrepaired, this DNA damage can lead to cancer induction. On the basis of current evidence Cr6+ has a threshold for carcinogenic potential in humans that is greater than the current TLV.

  15. Objective threshold for distinguishing complicated tasks

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Kyun; Jung, Won Dea [KAERI, Daejeon (Korea, Republic of)

    2014-08-15

    Estimating the likelihood of human error in a reliable manner is really important for enhancing the safety of a large process control system such as Nuclear Power Plants (NPPs). In this regard, from the point of view of Probabilistic Safety Assessment (PSA), various kinds of Human Reliability Analysis (HRA) methods have been used for several decades in order to systematically evaluate the effect of human error on the safety of NPPs. However, one of the recurrence issues is to determine the level of an important Performance Shaping Factor (PSF) by using a clear and objective manner with respect to the context of a given task. Unfortunately, there is no such criterion for a certain PSF such as the complexity of a task. For this reason, in this study, an objective criterion that is helpful for identifying a complicated task is suggested based on the Task Complexity (TACOM) measure. To this end, subjective difficulty scores rated by high speed train drivers are collected. After that, subjective difficulty scores are compared with the associated TACOM scores being quantified based on tasks to be conducted by high speed train drivers. As a result, it is expected that high speed train drivers feel a significant difficulty when they are faced with tasks of which the TACOM scores are greater than 4.2. Since TACOM measure is a kind of general tool to quantify the complexity of tasks to be done by human operators, it is promising to conclude that this value can be regarded as a common threshold representing what a complicated task is.

  16. Top-quark pair production near threshold

    International Nuclear Information System (INIS)

    Sumino, Y.; Fujii, K.; Hagiwara, K.; Murayama, H.; Ng, C.

    1993-01-01

    We present a novel formalism to calculate the total and the differential cross sections for heavy unstable top-quark pair production near threshold. Within the context of the nonrelativistic quark model, we introduce the running toponium width Γ FTHETA (E,p) in the Schroedinger equation for the three-point Green's function that governs the t bar t contribution to the e + e- annihilation process. The effect of the running of the width is found to be significant in two aspects: (i) it takes account of the phase-space volume for the decay process t bar t→bW + bar bW- and provides a consistent framework for calculating the differential cross sections; and (ii) it reduces the widths of the low-lying resonances to considerably less than 2Γ t (m t 2 ). Furthermore, the running of the width causes the total cross section to decrease significantly at c.m. energies below the first ''resonance'' enhancement, whereas it makes the ''peak'' cross section more distinct than is obtained in the fixed toponium width approximation. We use the two-loop-improved QCD potential in our calculation, and the α s (m Z ) Mbar S dependences of the total and differential cross sections are studied quantitatively, where M bar S denotes the modified minimal subtraction scheme. We find that the correlations in the α s and m t measurements are opposite in the total and differential cross sections, and the simultaneous measurements would lead to an accurate determination of both parameters

  17. Heritability estimates derived from threshold analyses for ...

    African Journals Online (AJOL)

    Product-moment correlations between breeding values for stayability traits were low. The highest correlation of 0.22 was obtained between the ages of 36 and 48 months. Heritability estimates and correlations between traits appear to be of such a low magnitude that selection for these characteristics would result in limited ...

  18. Reference hearing threshold levels for short duration signals

    DEFF Research Database (Denmark)

    Poulsen, Torben; Legarth, Søren Vase

    2008-01-01

    for the determination of reference hearing threshold levels. The results are given as peak-to-peak equivalent threshold sound pressure levels (peETSPL). The results are in good agreement with other sparse results from literature and are part of the basis for the ISO 389-6 standard from 2007....

  19. Model Threshold untuk Pembelajaran Memproduksi Pantun Kelas XI

    Directory of Open Access Journals (Sweden)

    Fitri Nura Murti

    2017-03-01

    Full Text Available Abstract: The learning pantun method in schools provided less opportunity to develop the students’ creativity in producing pantun. This situation was supported by the result of the observation conducted on eleventh graders at SMAN 2 Bondowoso. It showed that the students tend to plagiarize their pantun. The general objective of this research and development is to develop Threshold Pantun model for learning to produce pantun for elevent graders. The product was presented in guidance book for teachers entitled “Pembelajaran Memproduksi Pantun Menggunakan Model Threshold Pantun untuk Kelas XI”. This study adapted design method of Borg-Gall’s R&D procedure. The result of this study showed that Threshold Pantun model was appropriate to be implemented for learning to produce pantun. Key Words: Threshold Pantun model, produce pantun Abstrak: Pembelajaran pantun di sekolah selama ini kurang mengembangkan kreativitas siswa dalam memproduksi pantun. Hal tersebut dikuatkan oleh hasil observasi siswa kelas XI SMAN 2 Bondowoso yang menunjukkan adanya kecenderungan produk siswa bersifat plagiat. Tujuan penelitian dan pengembangan ini secara umum adalah mengembangkan model Threshold Pantun untuk pembelajaran memproduksi pantun kelas XI..Produk disajikan dalam bentuk buku panduan bagi guru dengan judul “Pembelajaran Memproduksi Pantun Menggunakan Model Threshold Pantun untuk Kelas XI”. Penelitian ini menggunakan rancangan penelitian yang diadaptasi dari prosedur penelitian dan pengembangan Borg dan Gall. Berdasarkan hasil validasi model Threshold Pantun untuk pembelajaran memproduksi pantun layak diimplementasikan. Kata kunci: model Threshold Pantun, memproduksi pantun

  20. Weight, Mass, and Gravity: Threshold Concepts in Learning Science

    Science.gov (United States)

    Bar, Varda; Brosh, Yaffa; Sneider, Cary

    2016-01-01

    Threshold concepts are essential ideas about the natural world that present either a barrier or a gateway to a deep understanding of science. Weight, mass, and gravity are threshold concepts that underpin students' abilities to understand important ideas in all fields of science, embodied in the performance expectations in the Next Generation…

  1. 20 CFR 418.1105 - What is the threshold?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false What is the threshold? 418.1105 Section 418.1105 Employees' Benefits SOCIAL SECURITY ADMINISTRATION MEDICARE SUBSIDIES Medicare Part B Income... in the Consumer Price Index rounded to the nearest $1,000. CMS will publish the threshold amounts...

  2. Europe's Other Poverty Measures: Absolute Thresholds Underlying Social Assistance

    Science.gov (United States)

    Bavier, Richard

    2009-01-01

    The first thing many learn about international poverty measurement is that European nations apply a "relative" poverty threshold and that they also do a better job of reducing poverty. Unlike the European model, the "absolute" U.S. poverty threshold does not increase in real value when the nation's standard of living rises,…

  3. On the threshold sensitivity of low background photoneutron systems

    International Nuclear Information System (INIS)

    Kazakevich, G.M.; Ponomarchuk, V.A.; Filippov, E.M.

    1973-01-01

    A mathematical substantiation is given of determining the sensitivity threshold for a number of photoneutron devices used in practice (Berill-2, Berill-4 etc.). It is shown that, considering various effects and a real time of measurements, the sensitivity threshold of the photoneutron devices waries within the range of 1.3x10 -3 % (Berill-3) to 2.2x10 -5 %

  4. A curve of thresholds governs plague epizootics in Central Asia

    DEFF Research Database (Denmark)

    Reijniers, Jonas; Davis, Stephen; Begon, Mike

    2012-01-01

    , it is common to assume a threshold defined by the ratio of vector and host abundances. Here, we show in contrast, both from field data and model simulations, that for plague (Yersinia pestis) in Kazakhstan, the invasion threshold quantity is based on the product of its host (Rhombomys opimus) and vector...

  5. 49 CFR 38.99 - Floors, steps and thresholds.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Floors, steps and thresholds. 38.99 Section 38.99 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Commuter Rail Cars and Systems § 38.99 Floors, steps and thresholds...

  6. thresholds of gully erosion in the coastal plains sands of ...

    African Journals Online (AJOL)

    Ada

    estimating thresholds for gully initiation and sustenance. The entire 413. Km2 Ikpa River basin was covered with grids 1km2 and random number table was used to select 15% of the target population in the basin. The pair-wise correlation technique was employed to establish the threshold values of vegetation cover, organic ...

  7. When do price thresholds matter in retail categories?

    NARCIS (Netherlands)

    K.H. Pauwels (Koen); S. Srinivasan (Shuba); Ph.H.B.F. Franses (Philip Hans)

    2007-01-01

    textabstractMarketing literature has long recognized that brand price elasticity need not be monotonic and symmetric, but has yet to provide generalizable market-level insights on threshold-based price elasticity, asymmetric thresholds, and the sign and magnitude of elasticity transitions. This

  8. Effects of data resolution and stream delineation threshold area on ...

    African Journals Online (AJOL)

    The results also indicate that peak flow and slope of the hydrograph rising limb obtained from the SRTM DEM at different threshold areas (ranging from 0.25% to 3%) are greater than that for the TOPO DEM. Investigating the effects of stream network delineation threshold area on the simulated peak flow shows that the ...

  9. Optimal threshold functions for fault detection and isolation

    DEFF Research Database (Denmark)

    Stoustrup, J.; Niemann, Hans Henrik; Cour-Harbo, A. la

    2003-01-01

    Fault diagnosis systems usually comprises two parts: a filtering part and a decision part, the latter typically based on threshold functions. In this paper, systematic ways to choose the threshold values are proposed. Two different test functions for the filtered signals are discussed and a method...

  10. Accelerated testing for chloride threshold of reinforcing steel in concrete

    NARCIS (Netherlands)

    Polder, R.B.; Put, M. van; Peelen, W.H.A.

    2017-01-01

    Testing for the chloride threshold (also called critical chloride content) for corrosion initiation of steel in concrete has been found difficult and, at best, time consuming. Nevertheless, the chloride threshold is an important parameter in service life design of new structures and for evaluation

  11. An examination of fire spread thresholds in discontinuous fuel beds

    Science.gov (United States)

    Mark A. Finney; Jack D. Cohen; Isaac C. Grenfell; Kara M. Yedinak

    2010-01-01

    Many fuel beds, especially live vegetation canopies (conifer forests, shrub fields, bunch-grasses) contain gaps between vegetation clumps. Fires burning in these fuel types often display thresholds for spread that are observed to depend on environmental factors like wind, slope, and fuel moisture content. To investigate threshold spread behaviours, we conducted a set...

  12. Estimating the optimal growth-maximising public debt threshold for ...

    African Journals Online (AJOL)

    This paper attempts to estimate an optimal growth-maximising public debt threshold for Zimbabwe. The public debt threshold is estimated by assessing the relationship between public debt and economic growth. The analysis is undertaken to determine the tipping point beyond which increases in public debt adversely affect ...

  13. Thermalization threshold in models of 1D fermions

    Science.gov (United States)

    Mukerjee, Subroto; Modak, Ranjan; Ramswamy, Sriram

    2013-03-01

    The question of how isolated quantum systems thermalize is an interesting and open one. In this study we equate thermalization with non-integrability to try to answer this question. In particular, we study the effect of system size on the integrability of 1D systems of interacting fermions on a lattice. We find that for a finite-sized system, a non-zero value of an integrability breaking parameter is required to make an integrable system appear non-integrable. Using exact diagonalization and diagnostics such as energy level statistics and the Drude weight, we find that the threshold value of the integrability breaking parameter scales to zero as a power law with system size. We find the exponent to be the same for different models with its value depending on the random matrix ensemble describing the non-integrable system. We also study a simple analytical model of a non-integrable system with an integrable limit to better understand how a power law emerges.

  14. A STELLAR MASS THRESHOLD FOR QUENCHING OF FIELD GALAXIES

    International Nuclear Information System (INIS)

    Geha, M.; Blanton, M. R.; Yan, R.; Tinker, J. L.

    2012-01-01

    We demonstrate that dwarf galaxies (10 7 stellar 9 M ☉ , –12 > M r > –18) with no active star formation are extremely rare ( Hα stellar 9 M ☉ below which quenched galaxies do not exist in the field. Below this threshold, we find that none of the 2951 field dwarf galaxies are quenched; all field dwarf galaxies show evidence for recent star formation. Correcting for volume effects, this corresponds to a 1σ upper limit on the quenched fraction of 0.06%. In more dense environments, quenched galaxies account for 23% of the dwarf population over the same stellar mass range. The majority of quenched dwarf galaxies (often classified as dwarf elliptical galaxies) are within 2 virial radii of a massive galaxy, and only a few percent of quenched dwarf galaxies exist beyond 4 virial radii. Thus, for galaxies with stellar mass less than 1.0 × 10 9 M ☉ , ending star formation requires the presence of a more massive neighbor, providing a stringent constraint on models of star formation feedback.

  15. Proton-threshold states in /sup 28/Si

    Energy Technology Data Exchange (ETDEWEB)

    Champagne, A E; Pitt, M L; Zhang, P H; Lee, Jr, L L; Levine, M J

    1986-10-27

    The /sup 27/Al(/sup 3/He, d)/sup 28/Si reaction has been used to locate candidates for resonances in the /sup 27/Al+p system residing near the proton-capture threshold in the energy region characteristic of quiescent stellar hydrogen burning. Two such states are observed at excitation energies E/sub x/=11.658 MeV (J/sup ..pi../=2/sup +/) and 11.671 MeV (J/sup ..pi../=1/sup -/). A comparison of the cross sections for the /sup 27/Al(/sup 3/He, d)/sup 28/Si and the /sup 27/Al(..cap alpha.., t)/sup 28/Si reactions implies angular-momentum transfers of l=2 and l=3, respectively, for the two states of interest. Using this result, an astrophysically significant upper limit on the thermonuclear reaction rate has been calculated for the /sup 27/Al(p, ..gamma..)/sup 28/Si reaction which is found to be too slow to affect the /sup 27/Al abundance in red giants.

  16. The absolute threshold of colour vision in the horse.

    Directory of Open Access Journals (Sweden)

    Lina S V Roth

    Full Text Available Arrhythmic mammals are active both during day and night if they are allowed. The arrhythmic horses are in possession of one of the largest terrestrial animal eyes and the purpose of this study is to reveal whether their eye is sensitive enough to see colours at night. During the day horses are known to have dichromatic colour vision. To disclose whether they can discriminate colours in dim light a behavioural dual choice experiment was performed. We started the training and testing at daylight intensities and the horses continued to choose correctly at a high frequency down to light intensities corresponding to moonlight. One Shetland pony mare, was able to discriminate colours at 0.08 cd/m(2, while a half blood gelding, still discriminated colours at 0.02 cd/m(2. For comparison, the colour vision limit for several human subjects tested in the very same experiment was also 0.02 cd/m(2. Hence, the threshold of colour vision for the horse that performed best was similar to that of the humans. The behavioural results are in line with calculations of the sensitivity of cone vision where the horse eye and human eye again are similar. The advantage of the large eye of the horse lies not in colour vision at night, but probably instead in achromatic tasks where presumably signal summation enhances sensitivity.

  17. The concept of nuclear threshold and its political and strategic implications

    International Nuclear Information System (INIS)

    Sitt, Bernard

    2013-07-01

    literature to date. Such an approach would consist of going over the different dimensions of the nuclear threshold concept one by one and responding to a certain number of questions raised by an initial review. These questions can be divided into four categories: Those relative to the concept itself: is the threshold notion a useful concept? What does threshold mean exactly? Do several thresholds exist? What does a military nuclear capability entail? Those relative to the concept's implications for international law and arms control: are thresholds to be found in existing international instruments? Is the lack of a definition of what constitutes a nuclear weapon in the NPT problematic? Could new obligations be established that would amount to a de facto threshold (for instance, limiting States' rights under Article IV of the NPT)? Those relative to the concept's political implications: can or should a threshold be associated with a red line? How is the threshold notion perceived by different States? Those relative to the potential regional or global consequences of crossing a threshold: what can or should the international community's reaction be? Does the nuclear non-proliferation regime possess the necessary resilience to react or adapt? In various respects, the last category of questions is the most crucial. As suggested above, the emergence of a new nuclear-weapon-capable country has foiled the international community on several occasions. Is this kind of occurrence inevitable or can other diplomatic strategies, which could be coercive where necessary, be found? (author)

  18. A critical experimental study of the classical tactile threshold theory

    Directory of Open Access Journals (Sweden)

    Medina Leonel E

    2010-06-01

    Full Text Available Abstract Background The tactile sense is being used in a variety of applications involving tactile human-machine interfaces. In a significant number of publications the classical threshold concept plays a central role in modelling and explaining psychophysical experimental results such as in stochastic resonance (SR phenomena. In SR, noise enhances detection of sub-threshold stimuli and the phenomenon is explained stating that the required amplitude to exceed the sensory threshold barrier can be reached by adding noise to a sub-threshold stimulus. We designed an experiment to test the validity of the classical vibrotactile threshold. Using a second choice experiment, we show that individuals can order sensorial events below the level known as the classical threshold. If the observer's sensorial system is not activated by stimuli below the threshold, then a second choice could not be above the chance level. Nevertheless, our experimental results are above that chance level contradicting the definition of the classical tactile threshold. Results We performed a three alternative forced choice detection experiment on 6 subjects asking them first and second choices. In each trial, only one of the intervals contained a stimulus and the others contained only noise. According to the classical threshold assumptions, a correct second choice response corresponds to a guess attempt with a statistical frequency of 50%. Results show an average of 67.35% (STD = 1.41% for the second choice response that is not explained by the classical threshold definition. Additionally, for low stimulus amplitudes, second choice correct detection is above chance level for any detectability level. Conclusions Using a second choice experiment, we show that individuals can order sensorial events below the level known as a classical threshold. If the observer's sensorial system is not activated by stimuli below the threshold, then a second choice could not be above the chance

  19. Basis for limiting exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Bush, W.R.

    1979-07-01

    In view of the uncertainty about the size of the risk from radiation, it is assumed that all doses are potentially harmful with the probability of harm proportional to the dose, without threshold. Canada participates in the work of UNSCEAR, and the Canadian Atomic Energy Control Board follows the recommendations of the International Commission on Radiological Protection in setting its dose limits, encouraging the application of the ALARA (as low as reasonably achievable) concept through its licensing and compliance activities

  20. Experimental investigation on the threshold chloride concentration for corrosion initiation in reinforced concrete structures

    International Nuclear Information System (INIS)

    Byung Hwan Oh; Seung Yup Jang

    2005-01-01

    The corrosion of steel reinforcements in concrete is of great importance in the view of safety and durability of reinforced concrete structures. This study is focused on the corrosion behavior of steel bars induced by internal chlorides in concrete. The main objective of this study is to determine the threshold chloride concentration causing depassivation and active corrosion of steel reinforcement in concrete. To examine the threshold concentration of chloride ion, the half-cell potential, the chemical composition of extracted pore solutions of concrete and the extent of corroded area of the specimens were measured. Major test variables include the added amount of chlorides in concrete, type of binder, and water-to-binder ratios. From the present comprehensive test results, the factors influencing threshold chloride concentration are investigated, and the rational ranges of threshold chloride concentration causing active corrosion of steels are proposed. The present study provides the realistic chloride limit for corrosion initiation of reinforced concrete structures, which can be used efficiently in the future technical specification. (authors)

  1. Stress lowers the detection threshold for foul-smelling 2-mercaptoethanol.

    Science.gov (United States)

    Pacharra, Marlene; Schäper, Michael; Kleinbeck, Stefan; Blaszkewicz, Meinolf; Wolf, Oliver T; van Thriel, Christoph

    2016-01-01

    Previous studies have reported enhanced vigilance for threat-related information in response to acute stress. While it is known that acute stress modulates sensory systems in humans, its impact on olfaction and the olfactory detection of potential threats is less clear. Two psychophysical experiments examined, if acute stress lowers the detection threshold for foul-smelling 2-mercaptoethanol. Participants in Experiment 1 (N = 30) and Experiment 2 (N = 32) were randomly allocated to a control group or a stress group. Participants in the stress group underwent a purely psychosocial stressor (public mental arithmetic) in Experiment 1 and a stressor that combined a physically demanding task with social-evaluative threat in Experiment 2 (socially evaluated cold-pressor test). In both experiments, olfactory detection thresholds were repeatedly assessed by means of dynamic dilution olfactometry. Each threshold measurement consisted of three trials conducted using an ascending method of limits. Participants in the stress groups showed the expected changes in heart rate, salivary cortisol, and mood measures in response to stress. About 20 min after the stressor, participants in the stress groups could detect 2-mercaptoethanol at a lower concentration than participants in the corresponding control groups. Our results show that acute stress lowers the detection threshold for a malodor.

  2. Low level radiation: how does the linear without threshold model provide the safety of Canadian

    International Nuclear Information System (INIS)

    Anon.

    2010-01-01

    The linear without threshold model is a model of risk used worldwide by the most of health organisms of nuclear regulation in order to establish dose limits for workers and public. It is in the heart of the approach adopted by the Canadian commission of nuclear safety (C.C.S.N.) in matter of radiation protection. The linear without threshold model presumes reasonably it exists a direct link between radiation exposure and cancer rate. It does not exist scientific evidence that chronicle exposure to radiation doses under 100 milli sievert (mSv) leads harmful effects on health. Several scientific reports highlighted scientific evidences that seem indicate a low level of radiation is less harmful than the linear without threshold predicts. As the linear without threshold model presumes that any radiation exposure brings risks, the ALARA principle obliges the licensees to get the radiation exposure at the lowest reasonably achievable level, social and economical factors taken into account. ALARA principle constitutes a basic principle in the C.C.S.N. approach in matter of radiation protection; On the radiation protection plan, C.C.S.N. gets a careful approach that allows to provide health and safety of Canadian people and the protection of their environment. (N.C.)

  3. Radioactive sealed sources: Reasonable accountability, exemption, and licensing activity thresholds -- A technical basis

    International Nuclear Information System (INIS)

    Lee, D.W.; Shingleton, K.L.

    1996-01-01

    Perhaps owing to their small size and portability, some radiation accidents/incidents have involved radioactive sealed sources (RSSs). As a result, programs for the control and accountability of RSSs have come to be recommended and emplaced that essentially require RSSs to be controlled in a manner different from bulk, unsealed radioactive material. Crucially determining the total number of RSSs for which manpower-intensive radiation protection surveillance is provided is the individual RSS activity above which such surveillance is required and below which such effort is not considered cost effective. Individual RSS activity thresholds are typically determined through scenarios which impart a chosen internal or external limiting dose to Reference Man under specified exposure conditions. The resultant RSS threshold activity levels have meaning commensurate with the assumed scenario exposure parameters, i.e., if they are realistic and technically based. A review of how the Department of Energy (DOE), the International Atomic Energy Agency (IAEA), and the Nuclear Regulatory Commission (NRC) have determined their respective accountability, exemption, and licensing threshold activity values is provided. Finally, a fully explained method using references readily available to practicing health physicists is developed using realistic, technically-based calculation parameters by which RSS threshold activities may be locally generated

  4. Effect of gap detection threshold on consistency of speech in children with speech sound disorder.

    Science.gov (United States)

    Sayyahi, Fateme; Soleymani, Zahra; Akbari, Mohammad; Bijankhan, Mahmood; Dolatshahi, Behrooz

    2017-02-01

    The present study examined the relationship between gap detection threshold and speech error consistency in children with speech sound disorder. The participants were children five to six years of age who were categorized into three groups of typical speech, consistent speech disorder (CSD) and inconsistent speech disorder (ISD).The phonetic gap detection threshold test was used for this study, which is a valid test comprised six syllables with inter-stimulus intervals between 20-300ms. The participants were asked to listen to the recorded stimuli three times and indicate whether they heard one or two sounds. There was no significant difference between the typical and CSD groups (p=0.55), but there were significant differences in performance between the ISD and CSD groups and the ISD and typical groups (p=0.00). The ISD group discriminated between speech sounds at a higher threshold. Children with inconsistent speech errors could not distinguish speech sounds during time-limited phonetic discrimination. It is suggested that inconsistency in speech is a representation of inconsistency in auditory perception, which causes by high gap detection threshold. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Perioperative transfusion threshold and ambulation after hip revision surgery

    DEFF Research Database (Denmark)

    Nielsen, Kamilla; Johansson, Pär I; Dahl, Benny

    2014-01-01

    BACKGROUND: Transfusion with red blood cells (RBC) may be needed during hip revision surgery but the appropriate haemoglobin concentration (Hb) threshold for transfusion has not been well established. We hypothesized that a higher transfusion threshold would improve ambulation after hip revision...... surgery. METHODS: The trial was registered at Clinicaltrials.gov ( NCT00906295). Sixty-six patients aged 18 years or older undergoing hip revision surgery were randomized to receive RBC at a Hb threshold of either 7.3 g/dL (restrictive group) or 8.9 g/dL (liberal group). Postoperative ambulation...... received RBC. CONCLUSIONS: A Hb transfusion threshold of 8.9 g/dL was associated with a statistically significantly faster TUG after hip revision surgery compared to a threshold of 7.3 g/dL but the clinical importance is questionable and the groups did not differ in Hb at the time of testing....

  6. Testing for a Debt-Threshold Effect on Output Growth.

    Science.gov (United States)

    Lee, Sokbae; Park, Hyunmin; Seo, Myung Hwan; Shin, Youngki

    2017-12-01

    Using the Reinhart-Rogoff dataset, we find a debt threshold not around 90 per cent but around 30 per cent, above which the median real gross domestic product (GDP) growth falls abruptly. Our work is the first to formally test for threshold effects in the relationship between public debt and median real GDP growth. The null hypothesis of no threshold effect is rejected at the 5 per cent significance level for most cases. While we find no evidence of a threshold around 90 per cent, our findings from the post-war sample suggest that the debt threshold for economic growth may exist around a relatively small debt-to-GDP ratio of 30 per cent. Furthermore, countries with debt-to-GDP ratios above 30 per cent have GDP growth that is 1 percentage point lower at the median.

  7. 64 x 64 thresholding photodetector array for optical pattern recognition

    Science.gov (United States)

    Langenbacher, Harry; Chao, Tien-Hsin; Shaw, Timothy; Yu, Jeffrey W.

    1993-10-01

    A high performance 32 X 32 peak detector array is introduced. This detector consists of a 32 X 32 array of thresholding photo-transistor cells, manufactured with a standard MOSIS digital 2-micron CMOS process. A built-in thresholding function that is able to perform 1024 thresholding operations in parallel strongly distinguishes this chip from available CCD detectors. This high speed detector offers responses from one to 10 milliseconds that is much higher than the commercially available CCD detectors operating at a TV frame rate. The parallel multiple peaks thresholding detection capability makes it particularly suitable for optical correlator and optoelectronically implemented neural networks. The principle of operation, circuit design and the performance characteristics are described. Experimental demonstration of correlation peak detection is also provided. Recently, we have also designed and built an advanced version of a 64 X 64 thresholding photodetector array chip. Experimental investigation of using this chip for pattern recognition is ongoing.

  8. Is the diagnostic threshold for bulimia nervosa clinically meaningful?

    Science.gov (United States)

    Chapa, Danielle A N; Bohrer, Brittany K; Forbush, Kelsie T

    2018-01-01

    The DSM-5 differentiates full- and sub-threshold bulimia nervosa (BN) according to average weekly frequencies of binge eating and inappropriate compensatory behaviors. This study was the first to evaluate the modified frequency criterion for BN published in the DSM-5. The purpose of this study was to test whether community-recruited adults (N=125; 83.2% women) with current full-threshold (n=77) or sub-threshold BN (n=48) differed in comorbid psychopathology and eating disorder (ED) illness duration, symptom severity, and clinical impairment. Participants completed the Clinical Impairment Assessment and participated in semi-structured clinical interviews of ED- and non-ED psychopathology. Differences between the sub- and full-threshold BN groups were assessed using MANOVA and Chi-square analyses. ED illness duration, age-of-onset, body mass index (BMI), alcohol and drug misuse, and the presence of current and lifetime mood or anxiety disorders did not differ between participants with sub- and full-threshold BN. Participants with full-threshold BN had higher levels of clinical impairment and weight concern than those with sub-threshold BN. However, minimal clinically important difference analyses suggested that statistically significant differences between participants with sub- and full-threshold BN on clinical impairment and weight concern were not clinically significant. In conclusion, sub-threshold BN did not differ from full-threshold BN in clinically meaningful ways. Future studies are needed to identify an improved frequency criterion for BN that better distinguishes individuals in ways that will more validly inform prognosis and effective treatment planning for BN. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Attempt to define a repair threshold (or the prospects for kidneys of reduced uptake rate)

    International Nuclear Information System (INIS)

    Le Duc, A.; Camey, M.; Bourguignon, M.; CEA, 91 - Orsay

    1976-01-01

    The definition of a repair threshold hardly seems realistic whatever the etiology considered. It is impossible to set a lower uptake limit below which a kidney does not recover, nor an upper limit above which recuperation is inevitable. To be able to use an uptake rate result with discernment it is useful to know two facts: '0 degradation' prospects exist for very diseased kidneys; the prospects of recovery are very appreciable for kidneys subjected to an infected stasis, amply justifying conservation in uptake regions around 20%. All this obviously needs confirmation which can only be obtained by adding a functional study to certain files which already date back significantly [fr

  10. Plant responses to precipitation in desert ecosystems: integrating functional types, pulses, thresholds, and delays.

    Science.gov (United States)

    Ogle, Kiona; Reynolds, James F

    2004-10-01

    The 'two-layer' and 'pulse-reserve' hypotheses were developed 30 years ago and continue to serve as the standard for many experiments and modeling studies that examine relationships between primary productivity and rainfall variability in aridlands. The two-layer hypothesis considers two important plant functional types (FTs) and predicts that woody and herbaceous plants are able to co-exist in savannas because they utilize water from different soil layers (or depths). The pulse-reserve model addresses the response of individual plants to precipitation and predicts that there are 'biologically important' rain events that stimulate plant growth and reproduction. These pulses of precipitation may play a key role in long-term plant function and survival (as compared to seasonal or annual rainfall totals as per the two-layer model). In this paper, we re-evaluate these paradigms in terms of their generality, strengths, and limitations. We suggest that while seasonality and resource partitioning (key to the two-layer model) and biologically important precipitation events (key to the pulse-reserve model) are critical to understanding plant responses to precipitation in aridlands, both paradigms have significant limitations. Neither account for plasticity in rooting habits of woody plants, potential delayed responses of plants to rainfall, explicit precipitation thresholds, or vagaries in plant phenology. To address these limitations, we integrate the ideas of precipitation thresholds and plant delays, resource partitioning, and plant FT strategies into a simple 'threshold-delay' model. The model contains six basic parameters that capture the nonlinear nature of plant responses to pulse precipitation. We review the literature within the context of our threshold-delay model to: (i) develop testable hypotheses about how different plant FTs respond to pulses; (ii) identify weaknesses in the current state-of-knowledge; and (iii) suggest future research directions that will

  11. Taste perception with age: pleasantness and its relationships with threshold sensitivity and supra-threshold intensity of five taste qualities

    NARCIS (Netherlands)

    Mojet, J.; Christ-Hazelhof, E.; Heidema, J.

    2005-01-01

    The relationships between threshold sensitivity, supra-threshold intensity of NaCl, KCl, sucrose, aspartame, acetic acid, citric acid, caffeine, quinine HCl, monosodium glutamate (MSG) and inosine 5¿-monophosphate (IMP), and the pleasantness of these stimuli in products, were studied in 21 young

  12. Photonic limiters with enhanced dynamic range

    Science.gov (United States)

    Kononchuk, Rodion; Limberopoulos, Nicholaos; Anisimov, Igor; Vitebskiy, Ilya; Chabanov, Andrey

    2018-02-01

    Optical limiters transmit low intensity input light while blocking input light with the intensity exceeding certain limiting threshold. Conventional passive limiters utilize nonlinear optical materials, which are transparent at low light intensity and turn absorptive at high intensity. Strong nonlinear absorption, though, can result in over- heating and destruction of the limiter. Another problem is that the limiting threshold provided by the available optical material with nonlinear absorption is too high for many applications. To address the above problems, the nonlinear material can be incorporated in a photonic structure with engineered dispersion. At low intensity, the photonic structure can display resonant transmission via localized mode(s), while at high intensity the resonant transmission can disappear, and the entire stack can become highly re ective (not absorptive) within a broad frequency range. In the proposed design, the transition from the resonant transmission at low intensity to nearly total re ectivity at high intensity does not rely on nonlinear absorption; instead, it requires only a modest change in the refractive index of the nonlinear material. The latter implies a dramatic increase in the dynamic range of the limiter. The main idea is to eliminate the high-intensity resonant transmission by decoupling the localized (resonant) modes from the input light, rather than suppressing those modes using nonlinear absorption. Similar approach can be used for light modulation and switching.

  13. Electrocardiogram signal denoising based on a new improved wavelet thresholding

    Science.gov (United States)

    Han, Guoqiang; Xu, Zhijun

    2016-08-01

    Good quality electrocardiogram (ECG) is utilized by physicians for the interpretation and identification of physiological and pathological phenomena. In general, ECG signals may mix various noises such as baseline wander, power line interference, and electromagnetic interference in gathering and recording process. As ECG signals are non-stationary physiological signals, wavelet transform is investigated to be an effective tool to discard noises from corrupted signals. A new compromising threshold function called sigmoid function-based thresholding scheme is adopted in processing ECG signals. Compared with other methods such as hard/soft thresholding or other existing thresholding functions, the new algorithm has many advantages in the noise reduction of ECG signals. It perfectly overcomes the discontinuity at ±T of hard thresholding and reduces the fixed deviation of soft thresholding. The improved wavelet thresholding denoising can be proved to be more efficient than existing algorithms in ECG signal denoising. The signal to noise ratio, mean square error, and percent root mean square difference are calculated to verify the denoising performance as quantitative tools. The experimental results reveal that the waves including P, Q, R, and S waves of ECG signals after denoising coincide with the original ECG signals by employing the new proposed method.

  14. Smartphone threshold audiometry in underserved primary health-care contexts.

    Science.gov (United States)

    Sandström, Josefin; Swanepoel, De Wet; Carel Myburgh, Hermanus; Laurent, Claude

    2016-01-01

    To validate a calibrated smartphone-based hearing test in a sound booth environment and in primary health-care clinics. A repeated-measure within-subject study design was employed whereby air-conduction hearing thresholds determined by smartphone-based audiometry was compared to conventional audiometry in a sound booth and a primary health-care clinic environment. A total of 94 subjects (mean age 41 years ± 17.6 SD and range 18-88; 64% female) were assessed of whom 64 were tested in the sound booth and 30 within primary health-care clinics without a booth. In the sound booth 63.4% of conventional and smartphone thresholds indicated normal hearing (≤15 dBHL). Conventional thresholds exceeding 15 dB HL corresponded to smartphone thresholds within ≤10 dB in 80.6% of cases with an average threshold difference of -1.6 dB ± 9.9 SD. In primary health-care clinics 13.7% of conventional and smartphone thresholds indicated normal hearing (≤15 dBHL). Conventional thresholds exceeding 15 dBHL corresponded to smartphone thresholds within ≤10 dB in 92.9% of cases with an average threshold difference of -1.0 dB ± 7.1 SD. Accurate air-conduction audiometry can be conducted in a sound booth and without a sound booth in an underserved community health-care clinic using a smartphone.

  15. Lower versus higher hemoglobin threshold for transfusion in septic shock.

    Science.gov (United States)

    Holst, Lars B; Haase, Nicolai; Wetterslev, Jørn; Wernerman, Jan; Guttormsen, Anne B; Karlsson, Sari; Johansson, Pär I; Aneman, Anders; Vang, Marianne L; Winding, Robert; Nebrich, Lars; Nibro, Helle L; Rasmussen, Bodil S; Lauridsen, Johnny R M; Nielsen, Jane S; Oldner, Anders; Pettilä, Ville; Cronhjort, Maria B; Andersen, Lasse H; Pedersen, Ulf G; Reiter, Nanna; Wiis, Jørgen; White, Jonathan O; Russell, Lene; Thornberg, Klaus J; Hjortrup, Peter B; Müller, Rasmus G; Møller, Morten H; Steensen, Morten; Tjäder, Inga; Kilsand, Kristina; Odeberg-Wernerman, Suzanne; Sjøbø, Brit; Bundgaard, Helle; Thyø, Maria A; Lodahl, David; Mærkedahl, Rikke; Albeck, Carsten; Illum, Dorte; Kruse, Mary; Winkel, Per; Perner, Anders

    2014-10-09

    Blood transfusions are frequently given to patients with septic shock. However, the benefits and harms of different hemoglobin thresholds for transfusion have not been established. In this multicenter, parallel-group trial, we randomly assigned patients in the intensive care unit (ICU) who had septic shock and a hemoglobin concentration of 9 g per deciliter or less to receive 1 unit of leukoreduced red cells when the hemoglobin level was 7 g per deciliter or less (lower threshold) or when the level was 9 g per deciliter or less (higher threshold) during the ICU stay. The primary outcome measure was death by 90 days after randomization. We analyzed data from 998 of 1005 patients (99.3%) who underwent randomization. The two intervention groups had similar baseline characteristics. In the ICU, the lower-threshold group received a median of 1 unit of blood (interquartile range, 0 to 3) and the higher-threshold group received a median of 4 units (interquartile range, 2 to 7). At 90 days after randomization, 216 of 502 patients (43.0%) assigned to the lower-threshold group, as compared with 223 of 496 (45.0%) assigned to the higher-threshold group, had died (relative risk, 0.94; 95% confidence interval, 0.78 to 1.09; P=0.44). The results were similar in analyses adjusted for risk factors at baseline and in analyses of the per-protocol populations. The numbers of patients who had ischemic events, who had severe adverse reactions, and who required life support were similar in the two intervention groups. Among patients with septic shock, mortality at 90 days and rates of ischemic events and use of life support were similar among those assigned to blood transfusion at a higher hemoglobin threshold and those assigned to blood transfusion at a lower threshold; the latter group received fewer transfusions. (Funded by the Danish Strategic Research Council and others; TRISS ClinicalTrials.gov number, NCT01485315.).

  16. Defining indoor heat thresholds for health in the UK.

    Science.gov (United States)

    Anderson, Mindy; Carmichael, Catriona; Murray, Virginia; Dengel, Andy; Swainson, Michael

    2013-05-01

    It has been recognised that as outdoor ambient temperatures increase past a particular threshold, so do mortality/morbidity rates. However, similar thresholds for indoor temperatures have not yet been identified. Due to a warming climate, the non-sustainability of air conditioning as a solution, and the desire for more energy-efficient airtight homes, thresholds for indoor temperature should be defined as a public health issue. The aim of this paper is to outline the need for indoor heat thresholds and to establish if they can be identified. Our objectives include: describing how indoor temperature is measured; highlighting threshold measurements and indices; describing adaptation to heat; summary of the risk of susceptible groups to heat; reviewing the current evidence on the link between sleep, heat and health; exploring current heat and health warning systems and thresholds; exploring the built environment and the risk of overheating; and identifying the gaps in current knowledge and research. A global literature search of key databases was conducted using a pre-defined set of keywords to retrieve peer-reviewed and grey literature. The paper will apply the findings to the context of the UK. A summary of 96 articles, reports, government documents and textbooks were analysed and a gap analysis was conducted. Evidence on the effects of indoor heat on health implies that buildings are modifiers of the effect of climate on health outcomes. Personal exposure and place-based heat studies showed the most significant correlations between indoor heat and health outcomes. However, the data are sparse and inconclusive in terms of identifying evidence-based definitions for thresholds. Further research needs to be conducted in order to provide an evidence base for threshold determination. Indoor and outdoor heat are related but are different in terms of language and measurement. Future collaboration between the health and building sectors is needed to develop a common

  17. Calculation of Pareto-optimal solutions to multiple-objective problems using threshold-of-acceptability constraints

    Science.gov (United States)

    Giesy, D. P.

    1978-01-01

    A technique is presented for the calculation of Pareto-optimal solutions to a multiple-objective constrained optimization problem by solving a series of single-objective problems. Threshold-of-acceptability constraints are placed on the objective functions at each stage to both limit the area of search and to mathematically guarantee convergence to a Pareto optimum.

  18. Performance of iPad-based threshold perimetry in glaucoma and controls.

    Science.gov (United States)

    Schulz, Angela M; Graham, Elizabeth C; You, YuYi; Klistorner, Alexander; Graham, Stuart L

    2017-10-04

    Independent validation of iPad visual field testing software Melbourne Rapid Fields (MRF). To examine the functionality of MRF and compare its performance with Humphrey SITA 24-2 (HVF). Prospective, cross-sectional validation study. Sixty glaucomas (MD:-5.08±5.22); 17 pre-perimetric, 43 HVF field defects and 25 controls. The MRF was compared with HVF for scotoma detection, global indices, regional mean threshold values and sensitivity/specificity. Long-term test-retest variability was assessed after 6 months. Linear regression and Bland Altman analyses of global indices sensitivity/specificity using ROC curves, intraclass correlations. Using a cluster definition of three points at <1% or two at 0.5% to define a scotoma on HVF, MRF detected 39/54 abnormal hemifields with a similar threshold-based criteria. Global indices were highly correlated between MRF and HVF: MD r 2 = 0.80, PSD r 2 = 0.77, VFI r 2 = 0.85 (all P < 0.0001). For manifest glaucoma patients, correlations of regional mean thresholds ranged from r 2 = 0.45-0.78, despite differing array of tested points between devices. ROC analysis of global indices showed reasonable sensitivity/specificity with AUC values of MD:0.89, PSD:0.85 and VFI:0.88. MRF retest variability was low with ICC values at 0.95 (MD and VFI), 0.94 (PSD). However, individual test point variability for mid-range thresholds was higher. MRF perimetry, despite using a completely different test paradigm, shows good performance characteristics compared to HVF for detection of defects, correlation of global indices and regional mean threshold values. Reproducibility for individual points may limit application for monitoring change over time, and fixation monitoring needs improvement. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  19. Adjusting patients streaming initiated by a wait time threshold in emergency department for minimizing opportunity cost.

    Science.gov (United States)

    Kim, Byungjoon B J; Delbridge, Theodore R; Kendrick, Dawn B

    2017-07-10

    Purpose Two different systems for streaming patients were considered to improve efficiency measures such as waiting times (WTs) and length of stay (LOS) for a current emergency department (ED). A typical fast track area (FTA) and a fast track with a wait time threshold (FTW) were designed and compared effectiveness measures from the perspective of total opportunity cost of all patients' WTs in the ED. The paper aims to discuss these issues. Design/methodology/approach This retrospective case study used computerized ED patient arrival to discharge time logs (between July 1, 2009 and June 30, 2010) to build computer simulation models for the FTA and fast track with wait time threshold systems. Various wait time thresholds were applied to stream different acuity-level patients. National average wait time for each acuity level was considered as a threshold to stream patients. Findings The fast track with a wait time threshold (FTW) showed a statistically significant shorter total wait time than the current system or a typical FTA system. The patient streaming management would improve the service quality of the ED as well as patients' opportunity costs by reducing the total LOS in the ED. Research limitations/implications The results of this study were based on computer simulation models with some assumptions such as no transfer times between processes, an arrival distribution of patients, and no deviation of flow pattern. Practical implications When the streaming of patient flow can be managed based on the wait time before being seen by a physician, it is possible for patients to see a physician within a tolerable wait time, which would result in less crowded in the ED. Originality/value A new streaming scheme of patients' flow may improve the performance of fast track system.

  20. An iterative two-threshold analysis for single-subject functional MRI of the human brain

    Energy Technology Data Exchange (ETDEWEB)

    Auer, Tibor; Schweizer, Renate; Frahm, Jens [Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fuer Biophysikalische Chemie, Goettingen (Germany)

    2011-11-15

    Current thresholding strategies for the analysis of functional MRI (fMRI) datasets may suffer from specific limitations (e.g. with respect to the required smoothness) or lead to reduced performance for a low signal-to-noise ratio (SNR). Although a previously proposed two-threshold (TT) method offers a promising solution to these problems, the use of preset settings limits its performance. This work presents an optimised TT approach that estimates the required parameters in an iterative manner. The iterative TT (iTT) method is compared with the original TT method, as well as other established voxel-based and cluster-based thresholding approaches and spatial mixture modelling (SMM) for both simulated data and fMRI of a hometown walking task at different experimental settings (spatial resolution, filtering and SNR). In general, the iTT method presents with remarkable sensitivity and good specificity that outperforms all conventional approaches tested except for SMM in a few cases. This also holds true for challenging conditions such as high spatial resolution, the absence of filtering, high noise level, or a low number of task repetitions. Thus, iTT emerges as a good candidate for both scientific fMRI studies at high spatial resolution and more routine applications for clinical purposes. (orig.)

  1. The dual rod system of amphibians supports colour discrimination at the absolute visual threshold.

    Science.gov (United States)

    Yovanovich, Carola A M; Koskela, Sanna M; Nevala, Noora; Kondrashev, Sergei L; Kelber, Almut; Donner, Kristian

    2017-04-05

    The presence of two spectrally different kinds of rod photoreceptors in amphibians has been hypothesized to enable purely rod-based colour vision at very low light levels. The hypothesis has never been properly tested, so we performed three behavioural experiments at different light intensities with toads ( Bufo ) and frogs ( Rana ) to determine the thresholds for colour discrimination. The thresholds of toads were different in mate choice and prey-catching tasks, suggesting that the differential sensitivities of different spectral cone types as well as task-specific factors set limits for the use of colour in these behavioural contexts. In neither task was there any indication of rod-based colour discrimination. By contrast, frogs performing phototactic jumping were able to distinguish blue from green light down to the absolute visual threshold, where vision relies only on rod signals. The remarkable sensitivity of this mechanism comparing signals from the two spectrally different rod types approaches theoretical limits set by photon fluctuations and intrinsic noise. Together, the results indicate that different pathways are involved in processing colour cues depending on the ecological relevance of this information for each task.This article is part of the themed issue 'Vision in dim light'. © 2017 The Authors.

  2. Analytical determination of the bifurcation thresholds in stochastic differential equations with delayed feedback.

    Science.gov (United States)

    Gaudreault, Mathieu; Drolet, François; Viñals, Jorge

    2010-11-01

    Analytical expressions for pitchfork and Hopf bifurcation thresholds are given for a nonlinear stochastic differential delay equation with feedback. Our results assume that the delay time τ is small compared to other characteristic time scales, not a significant limitation close to the bifurcation line. A pitchfork bifurcation line is found, the location of which depends on the conditional average , where x(t) is the dynamical variable. This conditional probability incorporates the combined effect of fluctuation correlations and delayed feedback. We also find a Hopf bifurcation line which is obtained by a multiple scale expansion around the oscillatory solution near threshold. We solve the Fokker-Planck equation associated with the slowly varying amplitudes and use it to determine the threshold location. In both cases, the predicted bifurcation lines are in excellent agreement with a direct numerical integration of the governing equations. Contrary to the known case involving no delayed feedback, we show that the stochastic bifurcation lines are shifted relative to the deterministic limit and hence that the interaction between fluctuation correlations and delay affect the stability of the solutions of the model equation studied.

  3. Threshold-voltage modulated phase change heterojunction for application of high density memory

    International Nuclear Information System (INIS)

    Yan, Baihan; Tong, Hao; Qian, Hang; Miao, Xiangshui

    2015-01-01

    Phase change random access memory is one of the most important candidates for the next generation non-volatile memory technology. However, the ability to reduce its memory size is compromised by the fundamental limitations inherent in the CMOS technology. While 0T1R configuration without any additional access transistor shows great advantages in improving the storage density, the leakage current and small operation window limit its application in large-scale arrays. In this work, phase change heterojunction based on GeTe and n-Si is fabricated to address those problems. The relationship between threshold voltage and doping concentration is investigated, and energy band diagrams and X-ray photoelectron spectroscopy measurements are provided to explain the results. The threshold voltage is modulated to provide a large operational window based on this relationship. The switching performance of the heterojunction is also tested, showing a good reverse characteristic, which could effectively decrease the leakage current. Furthermore, a reliable read-write-erase function is achieved during the tests. Phase change heterojunction is proposed for high-density memory, showing some notable advantages, such as modulated threshold voltage, large operational window, and low leakage current

  4. Threshold-voltage modulated phase change heterojunction for application of high density memory

    Science.gov (United States)

    Yan, Baihan; Tong, Hao; Qian, Hang; Miao, Xiangshui

    2015-09-01

    Phase change random access memory is one of the most important candidates for the next generation non-volatile memory technology. However, the ability to reduce its memory size is compromised by the fundamental limitations inherent in the CMOS technology. While 0T1R configuration without any additional access transistor shows great advantages in improving the storage density, the leakage current and small operation window limit its application in large-scale arrays. In this work, phase change heterojunction based on GeTe and n-Si is fabricated to address those problems. The relationship between threshold voltage and doping concentration is investigated, and energy band diagrams and X-ray photoelectron spectroscopy measurements are provided to explain the results. The threshold voltage is modulated to provide a large operational window based on this relationship. The switching performance of the heterojunction is also tested, showing a good reverse characteristic, which could effectively decrease the leakage current. Furthermore, a reliable read-write-erase function is achieved during the tests. Phase change heterojunction is proposed for high-density memory, showing some notable advantages, such as modulated threshold voltage, large operational window, and low leakage current.

  5. Cost effectiveness of below-threshold waste disposal at DOE sites

    International Nuclear Information System (INIS)

    Smith, C.F.; Cohen, J.J.

    1987-01-01

    A minimal health and environmental risk, limitations on disposal capacity, and the relatively high costs of low level waste (LLW) disposal are basic driving forces that lead to consideration of less restrictive disposal of wastes with very low levels of radiological contamination. The term threshold limit describes radioactive wastes that have sufficiently low-levels of radiological content to be managed according to their nonradiological properties. Given the efforts described elsewhere to provide guidance on the definition of below threshold (BT) doses and concentration levels, the purpose of this study was to quantify the resultant quantities, costs and cost effectiveness of BT disposal. For purposes of consistency with the previous demonstrations of the application of the threshold concept, available data for waste streams at the Idaho National Engineering Laboratory (INEL) and the Savannah River Plant (SRP) sites were collected and analyzed with regard to volumes, radionuclide concentrations, and disposal costs. From this information, quantities of BT waste, potential cost savings and cost effectiveness values were estimated. 1 reference, 5 tables

  6. Re-examination of the threshold energy surface in copper

    International Nuclear Information System (INIS)

    King, W.E.; Benedek, R.; Merkle, K.L.; Meshii, M.

    1981-01-01

    Radiation-induced defect production in copper has been studied using in-situ electrical resistivity damage-rate measurements in the HVEM and molecular dynamics simulations. Analysis of the results yields a threshold energy surface characterized by two isolated pockets of low threshold energy centered at and surrounded by regions of much higher threshold energy; the corresponding damage function exhibits a plateau at 0.65 Frenkel pairs. A Frenkel pair resistivity of (2.75/sub -0.2/ + 0 6 ) x 10 - 4 Ω-cm is proposed. A model damage function is constructed and compared to results from ion irradiation damage-rate measurements. 7 figures

  7. Threshold pump power of a solar-pumped dye laser

    Science.gov (United States)

    Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.

    1988-01-01

    Threshold solar power for dye laser pumping has been determined by measuring the gain of a rhodamine 6G dye laser amplifier at various solar-simulated irradiances on an amplifier cell. The measured threshold was 20,000 solar constants (2.7 kW/sq cm) for the dye volume of 2 x 5 x 40 cu mm and the optimum dye concentration of 0.001 M. The threshold is about one-third of that achievable with a high-intensity solar concentrator.

  8. Review and Analysis of Cryptographic Schemes Implementing Threshold Signature

    Directory of Open Access Journals (Sweden)

    Anastasiya Victorovna Beresneva

    2015-03-01

    Full Text Available This work is devoted to the study of threshold signature schemes. The systematization of the threshold signature schemes was done, cryptographic constructions based on interpolation Lagrange polynomial, ellipt ic curves and bilinear pairings were investigated. Different methods of generation and verification of threshold signatures were explored, e.g. used in a mobile agents, Internet banking and e-currency. The significance of the work is determined by the reduction of the level of counterfeit electronic documents, signed by certain group of users.

  9. Faster magnet sorting with a threshold acceptance algorithm

    International Nuclear Information System (INIS)

    Lidia, S.; Carr, R.

    1995-01-01

    We introduce here a new technique for sorting magnets to minimize the field errors in permanent magnet insertion devices. Simulated annealing has been used in this role, but we find the technique of threshold acceptance produces results of equal quality in less computer time. Threshold accepting would be of special value in designing very long insertion devices, such as long free electron lasers (FELs). Our application of threshold acceptance to magnet sorting showed that it converged to equivalently low values of the cost function, but that it converged significantly faster. We present typical cases showing time to convergence for various error tolerances, magnet numbers, and temperature schedules

  10. Near-Threshold Ionization of Argon by Positron Impact

    Science.gov (United States)

    Babij, T. J.; Machacek, J. R.; Murtagh, D. J.; Buckman, S. J.; Sullivan, J. P.

    2018-03-01

    The direct single-ionization cross section for Ar by positron impact has been measured in the region above the first ionization threshold. These measurements are compared to semiclassical calculations which give rise to a power law variation of the cross section in the threshold region. The experimental results appear to be in disagreement with extensions to the Wannier theory applied to positron impact ionization, with a smaller exponent than that calculated by most previous works. In fact, in this work, we see no difference in threshold behavior between the positron and electron cases. Possible reasons for this discrepancy are discussed.

  11. A light-powered sub-threshold microprocessor

    Energy Technology Data Exchange (ETDEWEB)

    Liu Ming; Chen Hong; Zhang Chun; Li Changmeng; Wang Zhihua, E-mail: lium02@mails.tsinghua.edu.cn [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2010-11-15

    This paper presents an 8-bit sub-threshold microprocessor which can be powered by an integrated photosensitive diode. With a custom designed sub-threshold standard cell library and 1 kbit sub-threshold SRAM design, the leakage power of 58 nW, dynamic power of 385 nW - 165 kHz, EDP 13 pJ/inst and the operating voltage of 350 mV are achieved. Under a light of about 150 kLux, the microprocessor can run at a rate of up to 500 kHz. The microprocessor can be used for wireless-sensor-network nodes.

  12. Measurements of NN → dπ near threshold

    International Nuclear Information System (INIS)

    Hutcheon, D.A.

    1990-09-01

    New, precise measurements of the differential cross sections for np → dπ 0 and π + d → pp and of analyzing powers for pp → dπ + have been made at energies within 10 MeV (c.m.) of threshold. They allow the pion s-wave and p-wave parts of the production strength to be distinguished unambiguously, yielding an s-wave strength at threshold which is significantly smaller than the previously accepted value. There is no evidence for charge independence breaking nor for πNN resonances near threshold. (Author) (17 refs., 17 figs., tab.)

  13. Threshold Characteristics of Slow-Light Photonic Crystal Lasers

    DEFF Research Database (Denmark)

    Xue, Weiqi; Yu, Yi; Ottaviano, Luisa

    2016-01-01

    The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental...... results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced...

  14. Faster magnet sorting with a threshold acceptance algorithm

    International Nuclear Information System (INIS)

    Lidia, S.

    1994-08-01

    The authors introduce here a new technique for sorting magnets to minimize the field errors in permanent magnet insertion devices. Simulated annealing has been used in this role, but they find the technique of threshold acceptance produces results of equal quality in less computer time. Threshold accepting would be of special value in designing very long insertion devices, such as long FEL's. Their application of threshold acceptance to magnet sorting showed that it converged to equivalently low values of the cost function, but that it converged significantly faster. They present typical cases showing time to convergence for various error tolerances, magnet numbers, and temperature schedules

  15. Weak production of strangeness at threshold with polarization observables

    International Nuclear Information System (INIS)

    Baker, O.K.

    2002-01-01

    The differential cross section for the charged current electroweak reaction e → +p → ν → e +Λ → at threshold with polarization observables is presented. The form of the cross section at threshold for the reaction is simplified compared to higher energy. An expression is given for the invariant matrix element appropriate for the reaction when the incident electron is polarized, and the final state hyperon polarization is determined. The energy dependence of the resulting cross section is shown near threshold. Under the right kinematic conditions, there can be a sizeable enhancement in the cross section, making an experimental measurement of the weak axial-vector form factor feasible

  16. Recirculating beam-breakup thresholds for polarized higher-order modes with optical coupling

    Directory of Open Access Journals (Sweden)

    Georg H. Hoffstaetter

    2007-04-01

    Full Text Available Here we will derive the general theory of the beam-breakup (BBU instability in recirculating linear accelerators with coupled beam optics and with polarized higher-order dipole modes. The bunches do not have to be at the same radio-frequency phase during each recirculation turn. This is important for the description of energy recovery linacs (ERLs where beam currents become very large and coupled optics are used on purpose to increase the threshold current. This theory can be used for the analysis of phase errors of recirculated bunches, and of errors in the optical coupling arrangement. It is shown how the threshold current for a given linac can be computed and a remarkable agreement with tracking data is demonstrated. General formulas are then analyzed for several analytically solvable problems: (a Why can different higher order modes (HOM in one cavity couple and why can they then not be considered individually, even when their frequencies are separated by much more than the resonance widths of the HOMs? For the Cornell ERL as an example, it is noted that optimum advantage is taken of coupled optics when the cavities are designed with an x-y HOM frequency splitting of above 50 MHz. The simulated threshold current is then far above the design current of this accelerator. To justify that the simulation can represent an actual accelerator, we simulate cavities with 1 to 8 modes and show that using a limited number of modes is reasonable. (b How does the x-y coupling in the particle optics determine when modes can be considered separately? (c How much of an increase in threshold current can be obtained by coupled optics and why does the threshold current for polarized modes diminish roughly with the square root of the HOMs’ quality factors. Because of this square root scaling, polarized modes with coupled optics increase the threshold current more effectively for cavities that have rather large HOM quality factors, e.g. those without very

  17. Development of high damage threshold optics for petawatt-class short-pulse lasers

    International Nuclear Information System (INIS)

    Stuart, B.C.; Perry, M.D.; Boyd, R.D.

    1995-01-01

    The authors report laser-induced damage threshold measurements on pure and multilayer dielectrics and gold-coated optics at 1053 and 526 nm for pulse durations, τ, ranging from 140 fs to 1 ns. Damage thresholds of gold coatings are limited to 500 mJ/cm 2 in the subpicosecond range for 1053-nm pulses. In dielectrics, qualitative differences in the morphology of damage and a departure from the diffusion-dominated τ1/2 scaling indicate that damage results from plasma formation and ablation for τ≤10 ps and from conventional melting and boiling for τ>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in quantitative agreement with both the pulsewidth and wavelength scaling of experimental results

  18. CVTresh: R Package for Level-Dependent Cross-Validation Thresholding

    Directory of Open Access Journals (Sweden)

    Donghoh Kim

    2006-04-01

    Full Text Available The core of the wavelet approach to nonparametric regression is thresholding of wavelet coefficients. This paper reviews a cross-validation method for the selection of the thresholding value in wavelet shrinkage of Oh, Kim, and Lee (2006, and introduces the R package CVThresh implementing details of the calculations for the procedures. This procedure is implemented by coupling a conventional cross-validation with a fast imputation method, so that it overcomes a limitation of data length, a power of 2. It can be easily applied to the classical leave-one-out cross-validation and K-fold cross-validation. Since the procedure is computationally fast, a level-dependent cross-validation can be developed for wavelet shrinkage of data with various sparseness according to levels.

  19. CVTresh: R Package for Level-Dependent Cross-Validation Thresholding

    Directory of Open Access Journals (Sweden)

    Donghoh Kim

    2006-04-01

    Full Text Available The core of the wavelet approach to nonparametric regression is thresholding of wavelet coefficients. This paper reviews a cross-validation method for the selection of the thresholding value in wavelet shrinkage of Oh, Kim, and Lee (2006, and introduces the R package CVThresh implementing details of the calculations for the procedures.This procedure is implemented by coupling a conventional cross-validation with a fast imputation method, so that it overcomes a limitation of data length, a power of 2. It can be easily applied to the classical leave-one-out cross-validation and K-fold cross-validation. Since the procedure is computationally fast, a level-dependent cross-validation can be developed for wavelet shrinkage of data with various sparseness according to levels.

  20. Dynamics of the helium atom close to the full fragmentation threshold: Double ionization

    International Nuclear Information System (INIS)

    Bouri, C.; Selles, P.; Malegat, L.; Kwato Njock, M. G.

    2006-01-01

    A complete set of cross sections is presented for photodouble ionization of He at 0.1 eV above the threshold. Special care is taken to clear the asymmetry parameter and the energy differential cross section of any ionization-excitation contribution. As a result, their limiting behaviors for the fully asymmetric partitionings of the excess energy are elucidated, thus shedding light on pending discussions in the field. A reliable scheme follows for computing the fully integrated cross section. Very good agreement is observed between the calculated and measured fully differential cross sections after a detailed reassessment of the experimental normalization procedure. The present findings are compared with the assumptions underlying the Wannier picture of near-threshold double escape

  1. Ultrafast two-photon absorption optical thresholding of spectrally coded pulses

    Science.gov (United States)

    Zheng, Z.; Shen, S.; Sardesai, H.; Chang, C.-C.; Marsh, J. H.; Karkhanehchi, M. M.; Weiner, A. M.

    1999-08-01

    We report studies on two-photon absorption (TPA) GaAs p-i-n waveguide photodetectors as optical thresholders for proposed ultrashort pulse optical code-division multiple-access (CDMA) systems. For either chirped optical pulses or spectrally phase coded pseudonoise bursts, the TPA photocurrent response reveals a strong pulseshape dependence and shows good agreement with theoretical predictions and results from conventional SHG measurements. The performance limits of the TPA optical thresholders set by the encoded bandwidth in the spectral encoding-decoding process are also discussed based on numerical simulations. Our results show the feasibility of applying such devices as nonlinear intensity discriminators in ultrahigh-speed optical network applications.

  2. The threshold of coexistence and critical behaviour of a predator-prey cellular automaton

    International Nuclear Information System (INIS)

    Arashiro, Everaldo; Tome, Tania

    2007-01-01

    We study a probabilistic cellular automaton to describe two population biology problems: the threshold of species coexistence in a predator-prey system and the spreading of an epidemic in a population. By carrying out mean-field approximations and numerical simulations we obtain the phase boundaries (thresholds) related to the transition between an active state, where prey and predators present a stable coexistence, and a prey absorbing state. The numerical estimates for the critical exponents show that the transition belongs to the directed percolation universality class. In the limit where the cellular automaton maps into a model for the spreading of an epidemic with immunization we observe a crossover from directed percolation class to the dynamic percolation class. Patterns of growing clusters related to species coexistence and spreading of epidemic are shown and discussed

  3. Life below a ‘Language Threshold'?

    DEFF Research Database (Denmark)

    Liversage, Anika

    2009-01-01

    in three social locations: households, workplaces and language schools. During their first years in Denmark a gendered division of work may relegate the women to the Turkish- or Kurdish-speaking home environment. When they subsequently enter work, their poor Danish skills only allow them access into jobs......In many immigrant groups, women gain less command of the host country language than the men. Using life story interviews with marriage migrants from Turkey, now living in Denmark, this article investigates this limited language learning, linking it to these women's lives as they primarily unfold...... with little host country interaction. The available language education becomes fragmented after childbirth and often remains inadequate to substantially raise the women's command of Danish. Furthermore, national legislation may unintentionally impede language learning. As a result, even women with expressed...

  4. Threshold resummation of the structure function FL

    International Nuclear Information System (INIS)

    Moch, S.; Vogt, A.

    2009-02-01

    The behaviour of the quark coefficient function for the longitudinal structure function F L in deepinelastic scattering is investigated for large values of the Bjorken variable x. We combine a highly plausible conjecture on the large-x limit of the physical evolution kernel for this quantity with our explicit three-loop results to derive the coefficients of the three leading large-x logarithms, α s n ln 2n-1-k (1-x), k=1,2,3, to all orders in the strong coupling constant α s . Corresponding results are derived for the non-C F part of the gluon coefficient function suppressed by a factor 1-x, and for the analogous subleading (1-x)ln k (1-x) contributions in the quark case. Our results appear to indicate an obstacle for an exponentiation with a higher logarithmic accuracy. (orig.)

  5. Schubert calculus and threshold polynomials of affine fusion

    International Nuclear Information System (INIS)

    Irvine, S.E.; Walton, M.A.

    2000-01-01

    We show how the threshold level of affine fusion, the fusion of Wess-Zumino-Witten (WZW) conformal field theories, fits into the Schubert calculus introduced by Gepner. The Pieri rule can be modified in a simple way to include the threshold level, so that calculations may be done for all (non-negative integer) levels at once. With the usual Giambelli formula, the modified Pieri formula deforms the tensor product coefficients (and the fusion coefficients) into what we call threshold polynomials. We compare them with the q-deformed tensor product coefficients and fusion coefficients that are related to q-deformed weight multiplicities. We also discuss the meaning of the threshold level in the context of paths on graphs

  6. Stress relaxation insensitive designs for metal compliant mechanism threshold accelerometers

    Directory of Open Access Journals (Sweden)

    Carlos Vilorio

    2015-12-01

    Full Text Available We present two designs for metal compliant mechanisms for use as threshold accelerometers which require zero external power. Both designs rely on long, thin flexures positioned orthogonally to a flat body. The first design involves cutting or stamping a thin spring-steel sheet and then bending elements to form the necessary thin flexors. The second design uses precut spring-steel flexure elements mounted into a mold which is then filled with molten tin to form a bimetallic device. Accelerations necessary to switch the devices between bistable states were measured using a centrifuge. Both designs showed very little variation in threshold acceleration due to stress relaxation over a period of several weeks. Relatively large variations in threshold acceleration were observed for devices of the same design, most likely due to variations in the angle of the flexor elements relative to the main body of the devices. Keywords: Structural health monitoring, Sensor, Accelerometer, Zero power, Shock, Threshold

  7. Rainfall thresholds and flood warning: an operative case study

    Directory of Open Access Journals (Sweden)

    V. Montesarchio

    2009-02-01

    Full Text Available An operative methodology for rainfall thresholds definition is illustrated, in order to provide at critical river section optimal flood warnings. Threshold overcoming could produce a critical situation in river sites exposed to alluvial risk and trigger the prevention and emergency system alert. The procedure for the definition of critical rainfall threshold values is based both on the quantitative precipitation observed and the hydrological response of the basin. Thresholds values specify the precipitation amount for a given duration that generates a critical discharge in a given cross section and are estimated by hydrological modelling for several scenarios (e.g.: modifying the soil moisture conditions. Some preliminary results, in terms of reliability analysis (presence of false alarms and missed alarms, evaluated using indicators like hit rate and false alarm rate for the case study of Mignone River are presented.

  8. Threshold policy for global games with noisy information sharing

    KAUST Repository

    Mahdavifar, Hessam

    2015-12-15

    It is known that global games with noisy sharing of information do not admit a certain type of threshold policies [1]. Motivated by this result, we investigate the existence of threshold-type policies on global games with noisy sharing of information and show that such equilibrium strategies exist and are unique if the sharing of information happens over a sufficiently noisy environment. To show this result, we establish that if a threshold function is an equilibrium strategy, then it will be a solution to a fixed point equation. Then, we show that for a sufficiently noisy environment, the functional fixed point equation leads to a contraction mapping, and hence, its iterations converge to a unique continuous threshold policy.

  9. The distribution choice for the threshold of solid state relay

    International Nuclear Information System (INIS)

    Sun Beiyun; Zhou Hui; Cheng Xiangyue; Mao Congguang

    2009-01-01

    Either normal distribution or Weibull distribution can be accepted as sample distribution of the threshold of solid state relay. By goodness-of-fit method, bootstrap method and Bayesian method, the Weibull distribution is chosen later. (authors)

  10. Weighted-noise threshold based channel estimation for OFDM ...

    Indian Academy of Sciences (India)

    Existing optimal time-domain thresholds exhibit suboptimal behavior for completely unavailable KCS ... Compared with no truncation case, truncation improved the MSE ... channel estimation errors has been studied. ...... Consumer Electron.

  11. Higgs-Stoponium Mixing Near the Stop-Antistop Threshold

    CERN Document Server

    Bodwin, Geoffrey T; Wagner, Carlos E M

    2016-01-01

    Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhancements in the cross section that might arise either from the perturbative contributions to the Higgs-to-digluon and Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium states. Near threshold, enhancements in the relevant amplitudes that go as inverse powers of the stop-antistop relative velocity require resummations of perturbation theory and/or nonperturbative treatments. We present a complete formulation of threshold effects at leading order in the stop-antistop relative velocity in terms of nonrelativistic effective field theory. We give detailed numerical calculations for the case in ...

  12. Dynamical fusion thresholds in macroscopic and microscopic theories

    International Nuclear Information System (INIS)

    Davies, K.T.R.; Sierk, A.J.; Nix, J.R.

    1983-01-01

    Macroscopic and microscopic results demonstrating the existence of dynamical fusion thresholds are presented. For macroscopic theories, it is shown that the extra-push dynamics is sensitive to some details of the models used, e.g. the shape parametrization and the type of viscosity. The dependence of the effect upon the charge and angular momentum of the system is also studied. Calculated macroscopic results for mass-symmetric systems are compared to experimental mass-asymmetric results by use of a tentative scaling procedure, which takes into account both the entrance-channel and the saddle-point regions of configuration space. Two types of dynamical fusion thresholds occur in TDHF studies: (1) the microscopic analogue of the macroscopic extra push threshold, and (2) the relatively high energy at which the TDHF angular momentum window opens. Both of these microscopic thresholds are found to be very sensitive to the choice of the effective two-body interaction

  13. Lower versus Higher Hemoglobin Threshold for Transfusion in Septic Shock

    DEFF Research Database (Denmark)

    Holst, Lars B; Haase, Nicolai; Wetterslev, Jørn

    2014-01-01

    BACKGROUND: Blood transfusions are frequently given to patients with septic shock. However, the benefits and harms of different hemoglobin thresholds for transfusion have not been established. METHODS: In this multicenter, parallel-group trial, we randomly assigned patients in the intensive care...... unit (ICU) who had septic shock and a hemoglobin concentration of 9 g per deciliter or less to receive 1 unit of leukoreduced red cells when the hemoglobin level was 7 g per deciliter or less (lower threshold) or when the level was 9 g per deciliter or less (higher threshold) during the ICU stay...... were similar in the two intervention groups. CONCLUSIONS: Among patients with septic shock, mortality at 90 days and rates of ischemic events and use of life support were similar among those assigned to blood transfusion at a higher hemoglobin threshold and those assigned to blood transfusion...

  14. Rainfall characteristics and thresholds for periglacial debris flows in ...

    Indian Academy of Sciences (India)

    Mingfeng Deng

    2018-02-14

    Feb 14, 2018 ... Rainfall characteristics; runoff generated; threshold; debris flows; southeast Tibetan. Plateau. 1. ... glacier ablation water (Lu and Li 1989; Liu et al. 2013). ...... F J and Lund L J, US Department of Agriculture (River- side, CA ...

  15. Dynamics of polaritons in semiconductor microcavities near instability thresholds

    International Nuclear Information System (INIS)

    He, Peng-Bin

    2012-01-01

    A theoretical study is presented on the dynamics of polaritons in semiconductor microcavities near parametric instability thresholds. With upward or downward ramp of optical pump, different instability modes emerge in parameter space defined by damping and detuning. According to these modes, stationary short-wave, stationary periodic, oscillatory periodic, and oscillatory uniform parametric instabilities are distinguished. By multiple scale expansion, the dynamics near threshold can be described by a critical mode with a slowly varying amplitude for the last three instabilities. Furthermore, it is found that the evolutions of their amplitudes are governed by real or complex Ginzburg–Landau equations. -- Highlights: ► Phase diagrams for different instability in extended parameter space. ► Different instability modes near thresholds. ► Different envelop equations near thresholds obtained by multi-scale expansion.

  16. Porcine skin damage thresholds for pulsed nanosecond-scale laser exposure at 1064-nm

    Science.gov (United States)

    DeLisi, Michael P.; Peterson, Amanda M.; Noojin, Gary D.; Shingledecker, Aurora D.; Tijerina, Amanda J.; Boretsky, Adam R.; Schmidt, Morgan S.; Kumru, Semih S.; Thomas, Robert J.

    2018-02-01

    Pulsed high-energy lasers operating in the near-infrared (NIR) band are increasingly being used in medical, industrial, and military applications, but there are little available experimental data to characterize their hazardous effects on skin tissue. The current American National Standard for the Safe Use of Lasers (ANSI Z136.1-2014) defines the maximum permissible exposure (MPE) on the skin as either a single-pulse or total exposure time limit. This study determined the minimum visible lesion (MVL) damage thresholds in Yucatan miniature pig skin for the single-pulse case and several multiple-pulse cases over a wide range of pulse repetition frequencies (PRFs) (10, 125, 2,000, and 10,000 Hz) utilizing nanosecond-scale pulses (10 or 60 ns). The thresholds are expressed in terms of the median effective dose (ED50) based on varying individual pulse energy with other laser parameters held constant. The results confirm a decrease in MVL threshold as PRF increases for exposures with a constant number of pulses, while also noting a PRF-dependent change in the threshold as a function of the number of pulses. Furthermore, this study highlights a change in damage mechanism to the skin from melanin-mediated photomechanical events at high irradiance levels and few numbers of pulses to bulk tissue photothermal additivity at lower irradiance levels and greater numbers of pulses. The observed trends exceeded the existing exposure limits by an average factor of 9.1 in the photothermally-damaged cases and 3.6 in the photomechanicallydamaged cases.

  17. Minimum indoor temperature threshold recommendations for English homes in winter - A systematic review.

    Science.gov (United States)

    Jevons, R; Carmichael, C; Crossley, A; Bone, A

    2016-07-01

    To identify and assess the available evidence on the impacts of cold indoor temperature thresholds on human health and make evidence-based recommendations for English homes. Systematic literature review. A systematic search of peer-reviewed published literature from the UK and countries with similar climates, and grading of the evidence using the National Institute of Health (NIH) framework was followed by a discussion with experts and formulation of recommendations. Twenty papers were included. Studies were included if they were conducted outside England but were from countries considered to have similar climates. Studies included two small randomised controlled trials, two cohort studies and one case control study; other studies were cross-sectional, largely laboratory-based studies. Health effects in the general population start to occur at around 18 °C. Effects in older people are more profound than in younger adults. Older people are less able to perceive low temperatures. Although evidence was limited, a strong argument for setting thresholds remains. The effects observed on the general population and the effects on those more vulnerable makes a case for a recommended minimum temperature for all. Health messages should be clear and simple, allowing informed choices to be made. A threshold of 18 °C was considered the evidence based and practical minimum temperature at which a home should be kept during winter in England. There is limited evidence available on minimum temperature thresholds for homes. However a recommendation of at least 18 °C for the whole population with nuancing of messages for those more vulnerable to the effects of cold can be made from the results of the retrieved studies. Heating homes to at least 18 °C (65 °F) in winter poses minimal risk to the health of a sedentary person, wearing suitable clothing. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  18. ‘Soglitude’- introducing a method of thinking thresholds

    Directory of Open Access Journals (Sweden)

    Tatjana Barazon

    2010-04-01

    Full Text Available ‘Soglitude’ is an invitation to acknowledge the existence of thresholds in thought. A threshold in thought designates the indetermination, the passage, the evolution of every state the world is in. The creation we add to it, and the objectivity we suppose, on the border of those two ideas lies our perceptive threshold. No state will ever be permanent, and in order to stress the temporary, fluent character of the world and our perception of it, we want to introduce a new suitable method to think change and transformation, when we acknowledge our own threshold nature. The contributions gathered in this special issue come from various disciplines: anthropology, philosophy, critical theory, film studies, political science, literature and history. The variety of these insights shows the resonance of the idea of threshold in every category of thought. We hope to enlarge the notion in further issues on physics and chemistry, as well as mathematics. The articles in this issue introduce the method of threshold thinking by showing the importance of the in-between, of the changing of perspective in their respective domain. The ‘Documents’ section named INTERSTICES, includes a selection of poems, two essays, a philosophical-artistic project called ‘infraphysique’, a performance on thresholds in the soul, and a dialogue with Israel Rosenfield. This issue presents a kaleidoscope of possible threshold thinking and hopes to initiate new ways of looking at things.For every change that occurs in reality there is a subjective counterpart in our perception and this needs to be acknowledged as such. What we name objective is reflected in our own personal perception in its own personal manner, in such a way that the objectivity of an event might altogether be questioned. The absolute point of view, the view from “nowhere”, could well be the projection that causes dogmatism. By introducing the method of thinking thresholds into a system, be it

  19. Rainfall thresholds for the triggering of landslides in Slovenia

    Science.gov (United States)

    Peternel, Tina; Jemec Auflič, Mateja; Rosi, Ascanio; Segoni, Samuele; Komac, Marko; Casagli, Nicola

    2017-04-01

    Both at the worldwide level and in Slovenia, precipitation and related phenomena represent one of the most important triggering factors for the occurrence of slope mass movements. In the past decade, extreme rainfall events with a very high amount of precipitation occurs in a relatively short rainfall period have become increasingly important and more frequent, that causing numerous undesirable consequences. Intense rainstorms cause flash floods and mostly trigger shallow landslides and soil slips. On the other hand, the damage of long lasting rainstorms depends on the region's adaptation and its capacity to store or infiltrate excessive water from the rain. The amount and, consequently, the intensity of daily precipitation that can cause floods in the eastern part of Slovenia is a rather common event for the north-western part of the country. Likewise, the effect of rainfall is very dependent on the prior soil moisture, periods of full soil saturation and the creation of drifts in groundwater levels due to the slow melting of snow, growing period, etc. Landslides could be identified and to some extent also prevent with better knowledge of the relation between landslides and rainfall. In this paper the definition of rainfall thresholds for rainfall-induced landslides in Slovenia is presented. The thresholds have been calculated by collecting approximately 900 landslide data and the relative rainfall amounts, which have been collected from 41 rain gauges all over the country. The thresholds have been defined by the (1) use of an existing procedure, characterized by a high degree of objectiveness and (2) software that was developed for a test site with very different geological and climatic characteristics (Tuscany, central Italy). Firstly, a single national threshold has been defined, later the country was divided into four zones, on the basis of major the river basins and a single threshold has been calculated for each of them. Validation of the calculated

  20. Relationship of extinction to perceptual thresholds for single stimuli.

    Science.gov (United States)

    Meador, K J; Ray, P G; Day, L J; Loring, D W

    2001-04-24

    To demonstrate the effects of target stimulus intensity on extinction to double simultaneous stimuli. Attentional deficits contribute to extinction in patients with brain lesions, but extinction (i.e., masking) can also be produced in healthy subjects. The relationship of extinction to perceptual thresholds for single stimuli remains uncertain. Brief electrical pulses were applied simultaneously to the left and right index fingers of 16 healthy volunteers (8 young and 8 elderly adults) and 4 patients with right brain stroke (RBS). The stimulus to be perceived (i.e., target stimulus) was given at the lowest perceptual threshold to perceive any single stimulus (i.e., Minimal) and at the threshold to perceive 100% of single stimuli. The mask stimulus (i.e., stimulus given to block the target) was applied to the contralateral hand at intensities just below discomfort. Extinction was less for target stimuli at 100% than Minimal threshold for healthy subjects. Extinction of left targets was greater in patients with RBS than elderly control subjects. Left targets were extinguished less than right in healthy subjects. In contrast, the majority of left targets were extinguished in patients with RBS even when right mask intensity was reduced below right 100% threshold for single stimuli. RBS patients had less extinction for right targets despite having greater left mask - threshold difference than control subjects. In patients with RBS, right "targets" at 100% threshold extinguished left "masks" (20%) almost as frequently as left masks extinguished right targets (32%). Subtle changes in target intensity affect extinction in healthy adults. Asymmetries in mask and target intensities (relative to single-stimulus perceptual thresholds) affect extinction in RBS patients less for left targets but more for right targets as compared with control subjects.

  1. Threshold reduction through photon recycling in semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Gigase, Y.B.; Harder, C.S.; Kesler, M.P.; Meier, H.P. (IBM Research Division, Zurich Research Laboratory, CH-8803 Rueschlikon (Switzerland)); Van Zeghbroeck, B. (University of Colorado, Boulder, CO (USA))

    1990-09-24

    The threshold pump power of an AlGaAs-GaAs ridge quantum well laser diode has been reduced by 42% by recycling the spontaneous emission. An integrated photodiode absorbs the spontaneous radiation emitted by the laser diode and converts it back into electrical power. The recycling of this power results in a reduction of the electrical power required to reach the lasing threshold.

  2. Threshold condition for nonlinear tearing modes in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Zabiego, M.F. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Callen, J.D. [Wisconsin Univ., Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

    1996-04-01

    Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author). 19 refs.

  3. Room Temperature Ultralow Threshold GaN Nanowire Polariton Laser

    KAUST Repository

    Das, Ayan

    2011-08-01

    We report ultralow threshold polariton lasing from a single GaN nanowire strongly coupled to a large-area dielectric microcavity. The threshold carrier density is 3 orders of magnitude lower than that of photon lasing observed in the same device, and 2 orders of magnitude lower than any existing room-temperature polariton devices. Spectral, polarization, and coherence properties of the emission were measured to confirm polariton lasing. © 2011 American Physical Society.

  4. Social psychological approach to the problem of threshold

    International Nuclear Information System (INIS)

    Nakayachi, Kazuya

    1999-01-01

    This paper discusses the threshold of carcinogen risk from the viewpoint of social psychology. First, the results of a survey suggesting that renunciation of the Linear No-Threshold (LNT) hypothesis would have no influence on the public acceptance (PA) of nuclear power plants are reported. Second, the relationship between the adoption of the LNT hypothesis and the standardization of management for various risks are discussed. (author)

  5. Fuzzy Behavior Modulation with Threshold Activation for Autonomous Vehicle Navigation

    Science.gov (United States)

    Tunstel, Edward

    2000-01-01

    This paper describes fuzzy logic techniques used in a hierarchical behavior-based architecture for robot navigation. An architectural feature for threshold activation of fuzzy-behaviors is emphasized, which is potentially useful for tuning navigation performance in real world applications. The target application is autonomous local navigation of a small planetary rover. Threshold activation of low-level navigation behaviors is the primary focus. A preliminary assessment of its impact on local navigation performance is provided based on computer simulations.

  6. Total water content thresholds for shallow landslides, Outer Western Carpathians

    Czech Academy of Sciences Publication Activity Database

    Bil, M.; Andrašík, R.; Zahradníček, Pavel; Kubeček, J.; Sedonik, J.; Štěpánek, Petr

    2016-01-01

    Roč. 13, č. 2 (2016), s. 337-347 ISSN 1612-510X R&D Projects: GA ČR GA13-19831S; GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : data quality -control * debris flows * rainfall thresholds * equivalent * depth * failures * example * europe * model * Landslides * Threshold * Snowmelt * Time series * Antecedent rainfall * Outer Western Carpathians Subject RIV: EH - Ecology, Behaviour Impact factor: 3.657, year: 2016

  7. Cochlear neuropathy and the coding of supra-threshold sound.

    Science.gov (United States)

    Bharadwaj, Hari M; Verhulst, Sarah; Shaheen, Luke; Liberman, M Charles; Shinn-Cunningham, Barbara G

    2014-01-01

    Many listeners with hearing thresholds within the clinically normal range nonetheless complain of difficulty hearing in everyday settings and understanding speech in noise. Converging evidence from human and animal studies points to one potential source of such difficulties: differences in the fidelity with which supra-threshold sound is encoded in the early portions of the auditory pathway. Measures of auditory subcortical steady-state responses (SSSRs) in humans and animals support the idea that the temporal precision of the early auditory representation can be poor even when hearing thresholds are normal. In humans with normal hearing thresholds (NHTs), paradigms that require listeners to make use of the detailed spectro-temporal structure of supra-threshold sound, such as selective attention and discrimination of frequency modulation (FM), reveal individual differences that correlate with subcortical temporal coding precision. Animal studies show that noise exposure and aging can cause a loss of a large percentage of auditory nerve fibers (ANFs) without any significant change in measured audiograms. Here, we argue that cochlear neuropathy may reduce encoding precision of supra-threshold sound, and that this manifests both behaviorally and in SSSRs in humans. Furthermore, recent studies suggest that noise-induced neuropathy may be selective for higher-threshold, lower-spontaneous-rate nerve fibers. Based on our hypothesis, we suggest some approaches that may yield particularly sensitive, objective measures of supra-threshold coding deficits that arise due to neuropathy. Finally, we comment on the potential clinical significance of these ideas and identify areas for future investigation.

  8. Cochlear Neuropathy and the Coding of Supra-threshold Sound

    Directory of Open Access Journals (Sweden)

    Hari M Bharadwaj

    2014-02-01

    Full Text Available Many listeners with hearing thresholds within the clinically normal range nonetheless complain of difficulty hearing in everyday settings and understanding speech in noise. Converging evidence from human and animal studies points to one potential source of such difficulties: differences in the fidelity with which supra-threshold sound is encoded in the early portions of the auditory pathway. Measures of auditory subcortical steady-state responses in humans and animals support the idea that the temporal precision of the early auditory representation can be poor even when hearing thresholds are normal. In humans with normal hearing thresholds, behavioral ability in paradigms that require listeners to make use of the detailed spectro-temporal structure of supra-threshold sound, such as selective attention and discrimination of frequency modulation, correlate with subcortical temporal coding precision. Animal studies show that noise exposure and aging can cause a loss of a large percentage of auditory nerve fibers without any significant change in measured audiograms. Here, we argue that cochlear neuropathy may reduce encoding precision of supra-threshold sound, and that this manifests both behaviorally and in subcortical steady-state responses in humans. Furthermore, recent studies suggest that noise-induced neuropathy may be selective for higher-threshold, lower-spontaneous-rate nerve fibers. Based on our hypothesis, we suggest some approaches that may yield particularly sensitive, objective measures of supra-threshold coding deficits that arise due to neuropathy. Finally, we comment on the potential clinical significance of these ideas and identify areas for future investigation.

  9. Nonlinear threshold Boolean automata networks and phase transitions

    OpenAIRE

    Demongeot, Jacques; Sené, Sylvain

    2010-01-01

    In this report, we present a formal approach that addresses the problem of emergence of phase transitions in stochastic and attractive nonlinear threshold Boolean automata networks. Nonlinear networks considered are informally defined on the basis of classical stochastic threshold Boolean automata networks in which specific interaction potentials of neighbourhood coalition are taken into account. More precisely, specific nonlinear terms compose local transition functions that define locally t...

  10. Determining rainfall thresholds that trigger landslides in Colombia

    International Nuclear Information System (INIS)

    Mayorga Marquez, Ruth

    2003-01-01

    Considering that rainfall is the natural event that more often triggers landslides, it is important to study the relationship between this phenomenon and the occurrence of earth mass movements, by determining rainfall thresholds that trigger landslides in different zones of Colombia. The research presents a methodology that allows proposing rainfall thresholds that trigger landslides in Colombia, by means of a relationship between the accumulated rain in the soil (antecedent rainfall) and the rain that falls the day of the landslide occurrence (event rainfall)

  11. Threshold condition for nonlinear tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Zabiego, M.F.; Callen, J.D.

    1996-04-01

    Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author)

  12. Viral Diversity Threshold for Adaptive Immunity in Prokaryotes

    Science.gov (United States)

    Weinberger, Ariel D.; Wolf, Yuri I.; Lobkovsky, Alexander E.; Gilmore, Michael S.; Koonin, Eugene V.

    2012-01-01

    ABSTRACT Bacteria and archaea face continual onslaughts of rapidly diversifying viruses and plasmids. Many prokaryotes maintain adaptive immune systems known as clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated genes (Cas). CRISPR-Cas systems are genomic sensors that serially acquire viral and plasmid DNA fragments (spacers) that are utilized to target and cleave matching viral and plasmid DNA in subsequent genomic invasions, offering critical immunological memory. Only 50% of sequenced bacteria possess CRISPR-Cas immunity, in contrast to over 90% of sequenced archaea. To probe why half of bacteria lack CRISPR-Cas immunity, we combined comparative genomics and mathematical modeling. Analysis of hundreds of diverse prokaryotic genomes shows that CRISPR-Cas systems are substantially more prevalent in thermophiles than in mesophiles. With sequenced bacteria disproportionately mesophilic and sequenced archaea mostly thermophilic, the presence of CRISPR-Cas appears to depend more on environmental temperature than on bacterial-archaeal taxonomy. Mutation rates are typically severalfold higher in mesophilic prokaryotes than in thermophilic prokaryotes. To quantitatively test whether accelerated viral mutation leads microbes to lose CRISPR-Cas systems, we developed a stochastic model of virus-CRISPR coevolution. The model competes CRISPR-Cas-positive (CRISPR-Cas+) prokaryotes against CRISPR-Cas-negative (CRISPR-Cas−) prokaryotes, continually weighing the antiviral benefits conferred by CRISPR-Cas immunity against its fitness costs. Tracking this cost-benefit analysis across parameter space reveals viral mutation rate thresholds beyond which CRISPR-Cas cannot provide sufficient immunity and is purged from host populations. These results offer a simple, testable viral diversity hypothesis to explain why mesophilic bacteria disproportionately lack CRISPR-Cas immunity. More generally, fundamental limits on the adaptability of biological

  13. Midline Shift Threshold Value for Hemiparesis in Chronic Subdural Hematoma.

    Science.gov (United States)

    Juković, Mirela F; Stojanović, Dejan B

    2015-01-01

    Chronic subdural hematoma (CSDH) has a variety of clinical presentations, with numerous neurological symptoms and signs. Hemiparesis is one of the leading signs that potentially indicates CSDH. Purpose of this study was to determine the threshold (cut-off) value of midsagittal line (MSL) shift after which hemiparesis is likely to appear. The study evaluated 83 patients with 53 unilateral and 30 bilateral CSDHs in period of three years. Evaluated computed tomography (CT) findings in patients with CSDH were diameter of the hematoma and midsagittal line shift, measured on non-contrast CT scan in relation with occurrence of hemiparesis. Threshold values of MSL shift for both types of CSDHs were obtained as maximal (equal) sensitivity and specificity (intersection of the curves). MSL is a good predictor for hemiparesis occurrence (total sample, AUROC 0.75, p=0.0001). Unilateral and bilateral CSDHs had different threshold values of the MSL for hemiparesis development. Results suggested that in unilateral CSDH the threshold values of MSL could be at 10 mm (AUROC=0.65; p=0.07). For bilateral CSDH the threshold level of MSL shift was 4.5 mm (AUROC=0.77; p=0.01). Our study pointed on the phenomenon that midsagittal line shift can predict hemiparesis occurrence. Hemiparesis in patients with bilateral CSDH was more related to midsagittal line shift compared with unilateral CSDH. When value of midsagittal line shift exceed the threshold level, hemiparesis occurs with certain probability.

  14. ENTRIA workshop. Determine threshold values in radiation protection

    International Nuclear Information System (INIS)

    Diener, Lisa

    2015-01-01

    Threshold values affect our daily lives. Whether it concerns traffic or noise regulations, we all experience thresholds on a regular basis. But how are such values generated? The conference ''Determine Thres-hold Values in Radiation Protection'', taking place on January 27th 2015 in Braunschweig, focused on this question. The conference was undertaken in the context of the BMBF-funded interdisciplinary research project ''ENTRIA - Disposal Options for Radioactive Residues''. It aimed to stimulate a cross-disciplinary discussion. Spea-kers from different disciplinary backgrounds talked about topics like procedures of setting threshold values, standards for evaluating dosages, and public participation in the standardization of threshold values. Two major theses emerged: First, setting threshold values always requires considering contexts and protection targets. Second, existing uncertainties must be communicated in and with the public. Altogether, the conference offered lots of input and issues for discussion. In addition, it raised interesting and important questions for further and ongoing work in the research project ENTRIA.

  15. High-order above-threshold dissociation of molecules

    Science.gov (United States)

    Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

    2018-03-01

    Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

  16. Threshold and maximum power evolution of stimulated Brillouin scattering and Rayleigh backscattering in a single mode fiber segment

    International Nuclear Information System (INIS)

    Sanchez-Lara, R; Alvarez-Chavez, J A; Mendez-Martinez, F; De la Cruz-May, L; Perez-Sanchez, G G

    2015-01-01

    The behavior of stimulated Brillouin scattering (SBS) and Rayleigh backscattering phenomena, which limit the forward transmission power in modern, ultra-long haul optical communication systems such as dense wavelength division multiplexing systems is analyzed via simulation and experimental investigation of threshold and maximum power. Evolution of SBS, Rayleigh scattering and forward powers are experimentally investigated with a 25 km segment of single mode fiber. Also, a simple algorithm to predict the generation of SBS is proposed where two criteria of power thresholds was used for comparison with experimental data. (paper)

  17. Program requirements to determine and relate fuel damage and failure thresholds to anticipated conditions in pressurized water reactors

    International Nuclear Information System (INIS)

    Loyd, R.F.; Croucher, D.W.

    1980-03-01

    Anticipated transients, licensing criteria, and damage mechanisms for PWR fuel rods are reviewed. Potential mechanistic fuel rod damage limits for PWRs are discussed. An expermental program to be conducted out-of-pile and in the Engineering Test Reactor (ETR) to generate a safety data base to define mechanistic fuel damage and failure thresholds and to relate these thresholds to the thermal-hydraulic and power conditions in a PWR is proposed. The requirements for performing the tests are outlined. Analytical support requirements are defined

  18. Partnerships – Limited partnerships and limited liability limited partnerships

    OpenAIRE

    Henning, Johan J.

    2000-01-01

    Consideration of the Limited Liability Partnership Act 2000 which introduced a new corporate entity, carrying the designations “partnership” and “limited” which allow members to limit their liability whilst organising themselves internally as a partnership. Article by Professor Johan Henning (Director of the Centre for Corporate Law and Practice, IALS and Dean of the Faculty of Law, University of the Free State, South Africa). Published in Amicus Curiae - Journal of the Institute of Advanced ...

  19. Rainfall thresholds for the possible occurrence of landslides in Italy

    Directory of Open Access Journals (Sweden)

    M. T. Brunetti

    2010-03-01

    Full Text Available In Italy, rainfall is the primary trigger of landslides that frequently cause fatalities and large economic damage. Using a variety of information sources, we have compiled a catalogue listing 753 rainfall events that have resulted in landslides in Italy. For each event in the catalogue, the exact or approximate location of the landslide and the time or period of initiation of the slope failure is known, together with information on the rainfall duration D, and the rainfall mean intensity I, that have resulted in the slope failure. The catalogue represents the single largest collection of information on rainfall-induced landslides in Italy, and was exploited to determine the minimum rainfall conditions necessary for landslide occurrence in Italy, and in the Abruzzo Region, central Italy. For the purpose, new national rainfall thresholds for Italy and new regional rainfall thresholds for the Abruzzo Region were established, using two independent statistical methods, including a Bayesian inference method and a new Frequentist approach. The two methods proved complementary, with the Bayesian method more suited to analyze small data sets, and the Frequentist method performing better when applied to large data sets. The new regional thresholds for the Abruzzo Region are lower than the new national thresholds for Italy, and lower than the regional thresholds proposed in the literature for the Piedmont and Lombardy Regions in northern Italy, and for the Campania Region in southern Italy. This is important, because it shows that landslides in Italy can be triggered by less severe rainfall conditions than previously recognized. The Frequentist method experimented in this work allows for the definition of multiple minimum rainfall thresholds, each based on a different exceedance probability level. This makes the thresholds suited for the design of probabilistic schemes for the prediction of rainfall-induced landslides. A scheme based on four

  20. Restorative treatment thresholds: factors influencing the treatment thresholds and modalities of general dentists in Kuwait.

    Science.gov (United States)

    Khalaf, Mai E; Alomari, Qasem D; Ngo, Hien; Doméjean, Sophie

    2014-01-01

    This study investigated the thresholds at which general dentists in Kuwait would restore approximal and occlusal carious lesions and examined the demographic characteristics of the dentists in relation to their decision making. The study population consisted of a random sample of 185 general dentists practicing in the Ministry of Health of Kuwait. A survey questionnaire was administered. The questionnaire presented different stages and locations of carious lesions; the participants were asked to identify the stage at which a restoration is required under different conditions, the preparation technique, and their choice of restorative material. For approximal carious lesions, 74 (40%) of the participants reported that they would restoratively intervene when the carious lesion reached the outer third of the dentin. A total of 91 (49.2%) reported the use of traditional class II restorations. For occlusal carious lesions, 128 (69.2%) said they would intervene when lesions reached the middle third of the dentin. 146 (78.9%) said they would remove the carious tissue only in their preparation. For both approximal and occlusal lesions, the participants preferred resin composite as the material for restoration. The respondents tended to delay restorative intervention until dentinal penetration of the caries. Resin restorative materials were used in conservatively prepared cavities. Participants chose a conservative approach for occlusal lesions but still believed in a traditional approach when it concerned approximal lesions. Experience, university dental education, and participation in continuous education courses were most significantly related to restorative treatment. © 2014 S. Karger AG, Basel.

  1. Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

    International Nuclear Information System (INIS)

    Bergamaschi, Anna; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura

    2011-01-01

    The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems

  2. Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bergamaschi, Anna, E-mail: anna.bergamaschi@psi.ch; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2011-11-01

    The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems.

  3. Calculation of abort thresholds for the Beam Loss Monitoring System of the Large Hadron Collider at CERN

    CERN Document Server

    Nemcic, Martin; Dehning, Bernd

    The Beam Loss Monitoring (BLM) System is one of the most critical machine protection systems for the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), Switzerland. Its main purpose is to protect the superconducting magnets from quenches and other equipment from damage by requesting a beam abort when the measured losses exceed any of the predefined threshold levels. The system consist of circa 4000 ionization chambers which are installed around the 27 kilometres ring (LHC). This study aims to choose a technical platform and produce a system that addresses all of the limitations with the current system that is used for the calculation of the LHC BLM abort threshold values. To achieve this, a comparison and benchmarking of the Java and .NET technical platforms is performed in order to establish the most suitable solution. To establish which technical platform is a successful replacement of the current abort threshold calculator, comparable prototype systems in Java and .NET we...

  4. Crossing Thresholds: Identifying conceptual transitions in postsecondary teaching

    Directory of Open Access Journals (Sweden)

    Susan Wilcox

    2013-12-01

    Full Text Available 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 thinking and practicing. We developed a series of questions focusing on the “troublesome” and “transformative” characteristics of threshold concepts and asked these questions of several constituent groups, including those who are new to practice and the body of knowledge in postsecondary teaching and those who are already knowledgeable and/or experienced in the field. Based on our interpretation of participants’ responses, we identified four recognized concepts in the field of postsecondary teaching as potential threshold concepts in this field: Assessment for/as learning; Learning-centred teaching; Accommodation for diversity; and, Context-driven practice. Our findings suggest that threshold concepts are relevant to the field of postsecondary teaching. Through this work, we hope to help educational developers and faculty members consider what is involved in learning to teach and developing teaching expertise, and to encourage critical discussion about the teaching development “curriculum” in postsecondary settings. Threshold concepts arise as a field develops and are defined as practitioners and scholars in the field define their field. At this stage, we believe the real value of threshold concepts for postsecondary teaching lies in the discussion that arises in the process of identifying and naming the concepts.

  5. Ear surgery techniques results on hearing threshold improvement

    Directory of Open Access Journals (Sweden)

    Farhad Mokhtarinejad

    2013-01-01

    Full Text Available 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.

  6. Hearing threshold evaluation of dentistsin Babol (North of Iran

    Directory of Open Access Journals (Sweden)

    Maryam Ehsani

    2014-03-01

    Full Text Available Introduction:Noise in dental offices is one of the risk factors in the workplace. One of the major effects of noise is hearing loss. This study aimed to determine the effects of noise on hearing thresholds of dentists of Babol city. Methods:This descriptive analytical cross-sectional study was performed on 40 dentists in Babol City (as case group and 40 office workers (as control group. Hearing thresholdswere measured from all the subjects. The mean hearing threshold was calculated at different frequencies in each group and compared with the number 15 db. The data were analyzed by statistical software SPSS17and p≤0.05was considered significant. Results:The mean and standard deviation of hearing thresholds for the right ear of dentists and the control group without considering the different frequencies were 13.6156±9.14210db and10.0156±5.4488db (P=0.036,respectively and for the left ear were12.5115± 8.7609db and 10.059 ± 5.9254db respectively. Hearing threshold of right and left ear of young and middle age dentists was not significant. The hearing thresholds of the dentists with work experience of 15 years or less were not significant for the right and left ear. Auditory thresholds were significant between male and female only for the left ear (P=0.02. Conclusion:There was a change in hearing thresholds at all frequencies. A clear difference was in the left ear of men and women and hearing loss was higher in men. Also, age and working experience were not among the contributing factors to the incidence of noise-induced hearing loss.

  7. [Relationship between Occlusal Discomfort Syndrome and Occlusal Threshold].

    Science.gov (United States)

    Munakata, Motohiro; Ono, Yumie; Hayama, Rika; Kataoka, Kanako; Ikuta, Ryuhei; Tamaki, Katsushi

    2016-03-01

    Occlusal dysesthesia has been defined as persistent uncomfortable feelings of intercuspal position continuing for more than 6 months without evidence of physical occlusal discrepancy. The problem often occurs after occlusal intervention by dental care. Although various dental treatments (e. g. occlusal adjustment, orthodontic treatment and prosthetic reconstruction) are attempted to solve occlusal dysesthesia, they rarely reach a satisfactory result, neither for patients nor dentists. In Japan, these symptoms are defined by the term "Occlusal discomfort syndrome" (ODS). The aim of this study was to investigate the characteristics of ODS with the simple occlusal sensory perceptive and discriminative test. Twenty-one female dental patients with ODS (mean age 55.8 ± 19.2 years) and 21 age- and gender-matched dental patients without ODS (mean age 53.1 ± 16.8 years) participated in the study. Upon grinding occlusal registration foils that were stacked to different thicknesses, participants reported the thicknesses at which they recognized the foils (recognition threshold) and felt discomfort (discomfort threshold). Although there was no significant difference in occlusal recognition thresholds between the two patient groups, the discomfort threshold was significantly smaller in the patients with ODS than in those without ODS. Moreover, the recognition threshold showed an age-dependent increase in patients without ODS, whereas it remained comparable between the younger (patient subgroups with ODS. These results suggest that occlusal discomfort threshold rather than recognition threshold is an issue in ODS. The foil grinding procedure is a simple and useful method to evaluate occlusal perceptive and discriminative abilities in patients with ODS.

  8. Quantifying the Arousal Threshold Using Polysomnography in Obstructive Sleep Apnea.

    Science.gov (United States)

    Sands, Scott A; Terrill, Philip I; Edwards, Bradley A; Taranto Montemurro, Luigi; Azarbarzin, Ali; Marques, Melania; de Melo, Camila M; Loring, Stephen H; Butler, James P; White, David P; Wellman, Andrew

    2018-01-01

    Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al.) to the pattern of ventilation during spontaneous respiratory events. Conceptually, the magnitude of the airflow signal immediately after arousal onset reveals information on the underlying ventilatory drive that triggered the arousal. Polysomnographic arousal threshold measures were compared with gold standard values taken from esophageal pressure and intraoesophageal diaphragm electromyography recorded simultaneously (N = 29). Comparisons were also made to arousal threshold measures using continuous positive airway pressure (CPAP) dial-downs (N = 28). The validity of using (linearized) nasal pressure rather than pneumotachograph ventilation was also assessed (N = 11). Polysomnographic arousal threshold values were correlated with those measured using esophageal pressure and diaphragm EMG (R = 0.79, p < .0001; R = 0.73, p = .0001), as well as CPAP manipulation (R = 0.73, p < .0001). Arousal threshold estimates were similar using nasal pressure and pneumotachograph ventilation (R = 0.96, p < .0001). The arousal threshold in patients with OSA can be estimated using polysomnographic signals and may enable more personalized therapeutic interventions for patients with a low arousal threshold. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  9. HOME Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — HOME Income Limits are calculated using the same methodology that HUD uses for calculating the income limits for the Section 8 program. These limits are based on HUD...

  10. OPTIMUM, CRITICAL AND THRESHOLD VALUES FOR WATER OXYGENATION FOR MULLETS (MUGILIDAE AND FLATFISHES (PLEURONECTIDAE IN ONTOGENESIS

    Directory of Open Access Journals (Sweden)

    P. Shekk

    2014-12-01

    Full Text Available Purpose. To determine the optimum, critical, and threshold values of water oxygenation for embryos, larvae and fingerlings of mullets and flatfishes under different temperature conditions. Methodology. Oxygen consumption was studied in chronic experiments with «interrupted flow» method with automatic fixation of dissolved oxygen in water with the aid of an oxygen sensor and automatic, continuous recording of the obtained results. «Critical» (Pcrit., and the «threshold» (Pthr. oxygen tension in the water have been determined. Findings. Under optimum conditions, the normal embryogenesis of mullets and flatfish to the gastrulation stage, provided 90–130% oxygen saturation. The critical content was 80–85%, the threshold – 65–70% of the saturation. At the stage of «movable embryo» depending on water temperature and fish species, the optimum range of water oxygenation was within 70‒127.1%. The most tolerant to oxygen deficiency was flounder Platichthys luscus (Pcrit – 25.4–27,5; Pthr. – 20.5–22.5%, the least resistant to hypoxia was striped mullet Mugil серhalus (Pcrit. – 50–60; Pthr. – 35–40%. The limits of the critical and threshold concentration of dissolved oxygen directly depended on the temperature and salinity, at which embryogenesis occurred. An increase in water temperature and salinity resulted in an increase in critical and threshold values for oxygen tension embryos. Mullet and flatfish fingerlings in all stages of development had a high tolerance to hypoxia, which increased as they grew. They were resistant to the oversaturation of water with oxygen. The most demanding for the oxygen regime are larvae and fingerlings of striped mullet and Liza aurata. Hypoxia tolerance of Psetta maeoticus (Psetta maeoticus and flounder at all stages of development is very high. The fingerlings of these species can endure reduction of the dissolved oxygen in water to 2.10 and 1.65 mgO2/dm3 respectively for a long time

  11. Threshold for the destabilisation of the ion-temperature-gradient mode in magnetically confined toroidal plasmas

    Science.gov (United States)

    Zocco, A.; Xanthopoulos, P.; Doerk, H.; Connor, J. W.; Helander, P.

    2018-02-01

    The threshold for the resonant destabilisation of ion-temperature-gradient (ITG) driven instabilities that render the modes ubiquitous in both tokamaks and stellarators is investigated. We discover remarkably similar results for both confinement concepts if care is taken in the analysis of the effect of the global shear . We revisit, analytically and by means of gyrokinetic simulations, accepted tokamak results and discover inadequacies of some aspects of their theoretical interpretation. In particular, for standard tokamak configurations, we find that global shear effects on the critical gradient cannot be attributed to the wave-particle resonance destabilising mechanism of Hahm & Tang (Phys. Plasmas, vol. 1, 1989, pp. 1185-1192), but are consistent with a stabilising contribution predicted by Biglari et al. (Phys. Plasmas, vol. 1, 1989, pp. 109-118). Extensive analytical and numerical investigations show that virtually no previous tokamak theoretical predictions capture the temperature dependence of the mode frequency at marginality, thus leading to incorrect instability thresholds. In the asymptotic limit , where is the rotational transform, and such a threshold should be solely determined by the resonant toroidal branch of the ITG mode, we discover a family of unstable solutions below the previously known threshold of instability. This is true for a tokamak case described by a local local equilibrium, and for the stellarator Wendelstein 7-X, where these unstable solutions are present even for configurations with a small trapped-particle population. We conjecture they are of the Floquet type and derive their properties from the Fourier analysis of toroidal drift modes of Connor & Taylor (Phys. Fluids, vol. 30, 1987, pp. 3180-3185), and to Hill's theory of the motion of the lunar perigee (Acta Math., vol. 8, 1886, pp. 1-36). The temperature dependence of the newly determined threshold is given for both confinement concepts. In the first case, the new temperature

  12. Perceptual thresholds for detecting modifications applied to the acoustical properties of a violin.

    Science.gov (United States)

    Fritz, Claudia; Cross, Ian; Moore, Brian C J; Woodhouse, Jim

    2007-12-01

    This study is the first step in the psychoacoustic exploration of perceptual differences between the sounds of different violins. A method was used which enabled the same performance to be replayed on different "virtual violins," so that the relationships between acoustical characteristics of violins and perceived qualities could be explored. Recordings of real performances were made using a bridge-mounted force transducer, giving an accurate representation of the signal from the violin string. These were then played through filters corresponding to the admittance curves of different violins. Initially, limits of listener performance in detecting changes in acoustical characteristics were characterized. These consisted of shifts in frequency or increases in amplitude of single modes or frequency bands that have been proposed previously to be significant in the perception of violin sound quality. Thresholds were significantly lower for musically trained than for nontrained subjects but were not significantly affected by the violin used as a baseline. Thresholds for the musicians typically ranged from 3 to 6 dB for amplitude changes and 1.5%-20% for frequency changes. Interpretation of the results using excitation patterns showed that thresholds for the best subjects were quite well predicted by a multichannel model based on optimal processing.

  13. The Impact of Dynamic RTS Threshold Adjustment for IEEE 802.11 MAC Protocol

    Directory of Open Access Journals (Sweden)

    Mostafa Mjidi

    2009-01-01

    Full Text Available In recent years, wireless technologies and application received great attention. The Medium Access Control (MAC protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel in wireless local area networks (WLANs. IEEE 802.11 introduced the optional RTS/CTS handshaking mechanism to address the hidden terminal problem as well as to reduces the chance of collision in case of higher node density and traffic. RTS Threshold (RT determines when RTS/CTS mechanism should be used and proved to be an important parameter for performance characteristics in data transmission. We first investigate to find a meaningful threshold value according to the network situation and determine the impact of using or disengaging the RTS/CTS optional mechanism and dynamically adjust the RTS Threshold to maximize data transmission. The results show a significant improvement over existing CSMA/CA and RTS/CTS schemes. Our adaptive scheme performed even better when data rate increases. We verify our proposed scheme both analytically and with extensive network simulation using ns-2.

  14. Photoionization dynamics of excited Ne, Ar, Kr and Xe atoms near threshold

    International Nuclear Information System (INIS)

    Sukhorukov, V L; Petrov, I D; Schäfer, M; Merkt, F; Ruf, M-W; Hotop, H

    2012-01-01

    A review of experimental and theoretical studies of the threshold photoionization of the heavier rare-gas atoms is presented, with particular emphasis on the autoionization resonances in the spectral region between the lowest two ionization thresholds 2 P 3/2 and 2 P 1/2 , accessed from the ground or excited states. Observed trends in the positions, widths and shapes of the autoionization resonances depending on the atomic number, the principal quantum number n, the orbital angular momentum quantum number ℓ and further quantum numbers specifying the fine- and hyperfine-structure levels are summarized and discussed in the light of ab initio and multichannel quantum defect theory calculations. The dependence of the photoionization spectra on the initially prepared neutral state are also discussed, including results on the photoionization cross sections and photoelectron angular distributions of polarized excited states. The effects of various approximations in the theoretical treatment of photoionization in these systems are analysed. The very large diversity of observed phenomena and the numerous anomalies in spectral structures associated with the threshold ionization of the rare-gas atoms can be described in terms of a limited set of interactions and dynamical processes. Examples are provided illustrating characteristic aspects of the photoionization, and sets of recommended parameters describing the energy-level structure and photoionization dynamics of the rare-gas atoms are presented which were extracted in a critical analysis of the very large body of experimental and theoretical data available on these systems in the literature. (topical review)

  15. Near-Threshold Computing and Minimum Supply Voltage of Single-Rail MCML Circuits

    Directory of Open Access Journals (Sweden)

    Ruiping Cao

    2014-01-01

    Full Text Available In high-speed applications, MOS current mode logic (MCML is a good alternative. Scaling down supply voltage of the MCML circuits can achieve low power-delay product (PDP. However, the current almost all MCML circuits are realized with dual-rail scheme, where the NMOS configuration in series limits the minimum supply voltage. In this paper, single-rail MCML (SRMCML circuits are described, which can avoid the devices configuration in series, since their logic evaluation block can be realized by only using MOS devices in parallel. The relationship between the minimum supply voltage of the SRMCML circuits and the model parameters of MOS transistors is derived, so that the minimum supply voltage can be estimated before circuit designs. An MCML dynamic flop-flop based on SRMCML is also proposed. The optimization algorithm for near-threshold sequential circuits is presented. A near-threshold SRMCML mode-10 counter based on the optimization algorithm is verified. Scaling down the supply voltage of the SRMCML circuits is also investigated. The power dissipation, delay, and power-delay products of these circuits are carried out. The results show that the near-threshold SRMCML circuits can obtain low delay and small power-delay product.

  16. Infrared skin damage thresholds from 1319-nm continuous-wave laser exposures

    Science.gov (United States)

    Oliver, Jeffrey W.; Vincelette, Rebecca; Noojin, Gary D.; Clark, Clifton D.; Harbert, Corey A.; Schuster, Kurt J.; Shingledecker, Aurora D.; Kumru, Semih S.; Maughan, Justin; Kitzis, Naomi; Buffington, Gavin D.; Stolarski, David J.; Thomas, Robert J.

    2013-12-01

    A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ˜0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of optical-thermal interaction. Resultant trends with respect to exposure duration and beam diameter are compared with current standardized exposure limits for laser safety. Mathematical modeling agreed well with experimental data, predicting that though laser safety standards are sufficient for exposures <10 s, they may become less safe for very long exposures.

  17. Nonclassicality threshold for the three-qubit Greenberger-Horne-Zeilinger state

    Energy Technology Data Exchange (ETDEWEB)

    Vertesi, Tamas; Pal, Karoly F. [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, H-4001 Debrecen (Hungary)

    2011-10-15

    The nonclassical properties of the noisy three-qubit Greenberger-Horne-Zeilinger (GHZ) states, {rho}{sub v}=v|GHZ>threshold visibility. Here we report on Bell inequalities giving a threshold value smaller than v=1/2. This rules out the possibility of a local hidden variable model in the limit of v=1/2. In particular, the lowest threshold visibility we found is v=0.496 057, attainable with 5x5x5 settings, whereas the most economical one in number of settings corresponds to 3x3x4 settings. The method which enabled us to obtain these results, and in particular the about 10 000 tight Bell inequalities giving v<1/2, are also discussed in detail.

  18. Quantity and quality limit detritivore growth: mechanisms revealed by ecological stoichiometry and co-limitation theory.

    Science.gov (United States)

    Halvorson, Halvor M; Sperfeld, Erik; Evans-White, Michelle A

    2017-12-01

    Resource quantity and quality are fundamental bottom-up constraints on consumers. Best understood in autotroph-based systems, co-occurrence of these constraints may be common but remains poorly studied in detrital-based systems. Here, we used a laboratory growth experiment to test limitation of the detritivorous caddisfly larvae Pycnopsyche lepida across a concurrent gradient of oak litter quantity (food supply) and quality (phosphorus : carbon [P:C ratios]). Growth increased simultaneously with quantity and quality, indicating co-limitation across the resource gradients. We merged approaches of ecological stoichiometry and co-limitation theory, showing how co-limitation reflected shifts in C and P acquisition throughout homeostatic regulation. Increased growth was best explained by elevated consumption rates and improved P assimilation, which both increased with elevated quantity and quality. Notably, C assimilation efficiencies remained unchanged and achieved maximum 18% at low quantity despite pronounced C limitation. Detrital C recalcitrance and substantive post-assimilatory C losses probably set a minimum quantity threshold to achieve positive C balance. Above this threshold, greater quality enhanced larval growth probably by improving P assimilation toward P-intensive growth. We suggest this interplay of C and P acquisition contributes to detritivore co-limitation, highlighting quantity and quality as potential simultaneous bottom-up controls in detrital-based ecosystems, including under anthropogenic change like nutrient enrichment. © 2017 by the Ecological Society of America.

  19. Decision threshold associated with multiple measurements. Application to the synthesis of the environment monitoring results; Seuil de decision associe a des mesures multiples. Application a la synthese des resultats de surveillance de l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    Vivier, A. [CEA, Institut national des sciences et techniques nucleaires, Centre de Saclay, 91191 Gif-sur-Yvette Cedex (France); Manificat, G. [IRSN, Direction de l' environnement et de l' intervention, Service d' etude et de surveillance de la radioactivite dans l' environnement, BP 40035, 78116 Le Vesinet Cedex (France); Picolo, J.L.; Fleury, S. [IRSN, Direction de l' environnement et de l' intervention, Service de traitement des echantillons et de metrologie pour l' environnement, BP 40035, 78116 Le Vesinet Cedex (France); Mokili, M. [Laboratoire SUBATECH - UMR 6457, ecole des Mines de Nantes, IN2P3/CNRS, Universite de Nantes, 4 rue Alfred Kastler, La Chantrerie, BP 20722, 44307 Nantes Cedex 03 (France); Guo, X. [ORTEC-AMETEK Inc, 801 S. Illinois Ave., Oak Ridge, TN 37830 (United States)

    2012-01-15

    When the sample activity is measured for various reasons several times, then with each measurement can be associated an individual decision threshold and limit of detection. Each measurement can be analyzed through its own decision threshold. The whole measurements can sometimes present contradictory results, some measurements being lower than the decision threshold and other higher. The problem then arises to build a decision threshold and a detection limit taking into account all the individual results, and to decide if the radioactivity is finally detected or not. It is interesting to note that it is possible sometimes that the decision threshold taking account all results makes it possible to decide that the radioactivity is present whereas the totality of the individual results are negative in terms of individual decision threshold. The purpose of this article is to show how these thresholds and these coherent limits cumulated can be determined in way according to the experimental conditions. In a general way a rigorous method of cumulating makes it possible to systematically decrease the decision threshold and limit of detection in terms of activity. This approach has interesting applications in gamma spectrometry with multi-emitters, discharge or periodical environmental measurements. On the basis of measurements realized by the IRSN within the framework of the national monitoring of the environment, we will see the potential impact of these methods on the final assessments. (authors)

  20. Precipitation thresholds for triggering floods in Corgo hydrographic basin (Northern Portugal)

    Science.gov (United States)

    Santos, Monica; Fragoso, Marcelo

    2016-04-01

    The precipitation is a major cause of natural hazards and is therefore related to the flood events (Borga et al., 2011; Gaál et al., 2014; Wilhelmi & Morss, 2013). The severity of a precipitation event and their potential damage is dependent on the total amount of rain but also on the intensity and duration event (Gaál et al., 2014). In this work, it was established thresholds based on critical combinations: amount / duration of flood events with daily rainfall data for Corgo hydrographic basin, in northern Portugal. In Corgo basin are recorded 31 floods events between 1865 and 2011 (Santos et al., 2015; Zêzere et al., 2014). We determined the minimum, maximum and pre-warning thresholds that define the boundaries so that an event may occur. Additionally, we applied these thresholds to different flood events occurred in the past in the study basin. The results show that the ratio between the flood events and precipitation events that occur above the minimum threshold has relatively low probability of a flood happen. These results may be related to the reduced number of floods events (only those that caused damage reported by the media and produced some type of damage). The maximum threshold is not useful for floods forecasting, since the majority of true positives are below this limit. The retrospective analysis of the thresholds defined suggests that the minimum and pre warning thresholds are well adjusted. The application of rainfall thresholds contribute to minimize possible situations of pre-crisis or immediate crisis, reducing the consequences and the resources involved in emergency response of flood events. References Borga, M., Anagnostou, E. N., Blöschl, G., & Creutin, J. D. (2011). Flash flood forecasting, warning and risk management: the HYDRATE project. Environmental Science & Policy, 14(7), 834-844. doi: 10.1016/j.envsci.2011.05.017 Gaál, L., Molnar, P., & Szolgay, J. (2014). Selection of intense rainfall events based on intensity thresholds and