persistent linear contrails: Topics by WorldWideScience.org

Sample records for persistent linear contrails

Properties of Linear Contrails Detected in 2012 Northern Hemisphere MODIS Imagery

Science.gov (United States)

Duda, David P.; Chee, Thad; Khlopenkov, Konstantin; Bedka, Sarah; Spangenberg, Doug; Minnis, Patrick

2015-01-01

Observation of linear contrail cirrus coverage and retrieval of their optical properties are valuable data for validating atmospheric climate models that represent contrail formation explicitly. These data can reduce our uncertainty of the regional effects of contrail-generated cirrus on global radiative forcing, and thus improve our estimation of the impact of commercial aviation on climate change. We use an automated contrail detection algorithm (CDA) to determine the coverage of linear persistent contrails over the Northern Hemisphere during 2012. The contrail detection algorithm is a modified form of the Mannstein et al. (1999) method, and uses several channels from thermal infrared MODIS data to reduce the occurrence of false positive detections. A set of contrail masks of varying sensitivity is produced to define the potential range of uncertainty in contrail coverage estimated by the CDA. Global aircraft emissions waypoint data provided by FAA allow comparison of detected contrails with commercial aircraft flight tracks. A pixel-level product based on the advected flight tracks defined by the waypoint data and U-V wind component profiles from the NASA GMAO GEOS-4 reanalysis has been developed to assign a confidence of contrail detection for the contrail mask. To account for possible contrail cirrus missed by the CDA, a post-processing method based on the assumption that pixels adjacent to detected linear contrails will have radiative signatures similar to those of the detected contrails is applied to the Northern Hemisphere data. Results from several months of MODIS observations during 2012 will be presented, representing a near-global climatology of contrail coverage. Linear contrail coverage will be compared with coverage estimates determined previously from 2006 MODIS data.
A diagnostic study of the global coverage by contrails. Pt. 1. Present day climate. Revised version

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Sausen, R.; Gierens, K.; Ponater, M.; Schumann, U.

1998-03-01

The global distribution of the contrail formation potential and the contrail cloud coverage are estimated using meteorological analysis data for temperature and humidity (ECMWF re-analyses) and a data base on aircraft fuel consumption. Regions with humidity between ice and liquid saturation and with temperature low enough to let aircraft trigger contrail formation are identified as regions in which persistent contrails may be formed. The frequency with which a region is conditioned for such persistent contrail formation measures the contrail formation potential. The mean contrail cloud coverage is computed by multiplying this frequency with a suitable function of fuel consumption (linear or non-linear). The product is normalized such that the contrail coverage equals the observed value of 0.5% in a domain between 30 W to 30 E, 35 N to 75 N. The results show a large potential for contrail formation in the upper troposphere, in particular in the tropics but also at mid-latitudes. At northern mid-latitudes about 20% of the upper tropospheric air is conditioned to form persistent contrails. Part of this region may be covered by otherwise forming cirrus clouds. When multiplied with fuel consumption of 1992 aviation, large cover by persistent contrail clouds is computed over Europe, the North Atlantic, the continental USA, and south-east Asia. The computed contrail coverage reaches 2% over the USA, and is larger in winter than in summer. The global mean contrail coverage is about 0.11% for linear fuel dependence and the given normalization. The result is only weakly sensitive to the propulsion efficiency of aircraft, but strongly sensitive to aircraft flight altitude. (orig.)
A Linear Programming Approach to the Development of Contrail Reduction Strategies Satisfying Operationally Feasible Constraints

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Wei, Peng; Sridhar, Banavar; Chen, Neil Yi-Nan; Sun, Dengfent

2012-01-01

A class of strategies has been proposed to reduce contrail formation in the United States airspace. A 3D grid based on weather data and the cruising altitude level of aircraft is adjusted to avoid the persistent contrail potential area with the consideration to fuel-efficiency. In this paper, the authors introduce a contrail avoidance strategy on 3D grid by considering additional operationally feasible constraints from an air traffic controller's aspect. First, shifting too many aircraft to the same cruising level will make the miles-in-trail at this level smaller than the safety separation threshold. Furthermore, the high density of aircraft at one cruising level may exceed the workload for the traffic controller. Therefore, in our new model we restrict the number of total aircraft at each level. Second, the aircraft count variation for successive intervals cannot be too drastic since the workload to manage climbing/descending aircraft is much larger than managing cruising aircraft. The contrail reduction is formulated as an integer-programming problem and the problem is shown to have the property of total unimodularity. Solving the corresponding relaxed linear programming with the simplex method provides an optimal and integral solution to the problem. Simulation results are provided to illustrate the methodology.
Basic Diagnosis and Prediction of Persistent Contrail Occurrence using High-resolution Numerical Weather Analyses/Forecasts and Logistic Regression. Part II: Evaluation of Sample Models

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Duda, David P.; Minnis, Patrick

2009-01-01

Previous studies have shown that probabilistic forecasting may be a useful method for predicting persistent contrail formation. A probabilistic forecast to accurately predict contrail formation over the contiguous United States (CONUS) is created by using meteorological data based on hourly meteorological analyses from the Advanced Regional Prediction System (ARPS) and from the Rapid Update Cycle (RUC) as well as GOES water vapor channel measurements, combined with surface and satellite observations of contrails. Two groups of logistic models were created. The first group of models (SURFACE models) is based on surface-based contrail observations supplemented with satellite observations of contrail occurrence. The second group of models (OUTBREAK models) is derived from a selected subgroup of satellite-based observations of widespread persistent contrails. The mean accuracies for both the SURFACE and OUTBREAK models typically exceeded 75 percent when based on the RUC or ARPS analysis data, but decreased when the logistic models were derived from ARPS forecast data.
Factors controlling contrail cirrus optical depth

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B. Kärcher

2009-08-01

Full Text Available Aircraft contrails develop into contrail cirrus by depositional growth and sedimentation of ice particles and horizontal spreading due to wind shear. Factors controlling this development include temperature, ice supersaturation, thickness of ice-supersaturated layers, and vertical gradients in the horizontal wind field. An analytical microphysical cloud model is presented and validated that captures these processes. Many individual contrail cirrus are simulated that develop differently owing to the variability in the controlling factors, resulting in large samples of cloud properties that are statistically analyzed. Contrail cirrus development is studied over the first four hours past formation, similar to the ages of line-shaped contrails that were tracked in satellite imagery on regional scales. On these time scales, contrail cirrus optical depth and microphysical variables exhibit a marked variability, expressed in terms of broad and skewed probability distribution functions. Simulated mean optical depths at a wavelength of 0.55 μm range from 0.05-0.5 and a substantial fraction 20-50% of contrail cirrus stay subvisible (optical depth <0.02, depending on meteorological conditions.

A detailed analysis based on an observational case study over the continental USA suggests that previous satellite measurements of line-shaped persistent contrails have missed about 89%, 50%, and 11% of contrails with optical depths 0-0.05, 0.05-0.1, and 0.1-0.2, respectively, amounting to 65% of contrail coverage of all optical depths. When comparing observations with simulations and when estimating the contrail cirrus climate impact, not only mean values but also the variability in optical depth and microphysical properties need to be considered.
Contrails and Climate Change: An Investigation of the Role of Aviation-Induced-Cloudiness on the Ireland Climate Using AATSR Imagery

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Whelan, Gillian M.; Cawkwell, Fiona; Mannstein, Hermann; Minnis, Patrick

2010-12-01

Contrails, or 'condensation trails', produced in the wake of jet aircraft have been found to have a small but significant global net climate-warming effect [1]. When atmospheric conditions are favorable (i.e. when ambient atmospheric humidity is high and temperature is below a threshold value of typically less than -40oC), contrails can persist for several hours, grow to become several kilometers long and can also trigger additional cirrus- cloud formation as they spread - which can further impact climate! Due to Ireland's proximity to the North Atlantic Flight Corridor, large volumes of high-altitude overflights cross Ireland daily. Contrails are essentially artificial-linear-ice-clouds at a lower temperature than the surrounding atmosphere and so are visible in 1 Km satellite imagery at the 11 and 12 μm wavelengths; but are better detected in the temperature difference image between these two thermal channels. An automated Contrail Detection Algorithm (CDA) is applied to AATSR thermal imagery over Ireland, and the percentage contrail-coverage of each scene determined. Preliminary results, based on 2008 morning and evening AATSR overpasses show a similar annual average contrail-coverage when present of 0.25% and 0.19% respectively, even though air-traffic density is typically several times higher during the morning overpasses. Cases of excessive contrail-coverage, of up to 2.06% have been observed in combination with extensive cirrus-coverage over Ireland. Results from meteorological data indicate more highly favorable atmospheric conditions for contrail formation and persistence in 00h00 and 06h00 radiosonde ascents; which corresponds to a night-time peak in high-altitude flights over Ireland. Furthermore, exceptionally thick contrail-susceptible-atmospheric layers are found in conjunction with cases of excessive satellite-derived- contrail-coverage.
Basic Diagnosis and Prediction of Persistent Contrail Occurrence using High-resolution Numerical Weather Analyses/Forecasts and Logistic Regression. Part I: Effects of Random Error

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Duda, David P.; Minnis, Patrick

2009-01-01

Straightforward application of the Schmidt-Appleman contrail formation criteria to diagnose persistent contrail occurrence from numerical weather prediction data is hindered by significant bias errors in the upper tropospheric humidity. Logistic models of contrail occurrence have been proposed to overcome this problem, but basic questions remain about how random measurement error may affect their accuracy. A set of 5000 synthetic contrail observations is created to study the effects of random error in these probabilistic models. The simulated observations are based on distributions of temperature, humidity, and vertical velocity derived from Advanced Regional Prediction System (ARPS) weather analyses. The logistic models created from the simulated observations were evaluated using two common statistical measures of model accuracy, the percent correct (PC) and the Hanssen-Kuipers discriminant (HKD). To convert the probabilistic results of the logistic models into a dichotomous yes/no choice suitable for the statistical measures, two critical probability thresholds are considered. The HKD scores are higher when the climatological frequency of contrail occurrence is used as the critical threshold, while the PC scores are higher when the critical probability threshold is 0.5. For both thresholds, typical random errors in temperature, relative humidity, and vertical velocity are found to be small enough to allow for accurate logistic models of contrail occurrence. The accuracy of the models developed from synthetic data is over 85 percent for both the prediction of contrail occurrence and non-occurrence, although in practice, larger errors would be anticipated.
Spatial and optical parameters of contrails in the vortex and dispersion regime determined by means of a ground-based scanning lidar

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Freudenthaler, V; Homburg, F; Jaeger, H [Fraunhofer-Inst. fuer Atmosphaerische Umweltforschung (IFU), Garmisch-Partenkirchen (Germany)

1998-12-31

The spatial growth of individual condensation trails (contrails) of commercial aircrafts in the time range from 15 s to 60 min behind the aircraft is investigated by means of a ground-based scanning backscatter lidar. The growth in width is mainly governed by wind shear and varies between 18 m/min and 140 m/min. The growth of the cross-section varies between 3500 m{sup 2}/min and 25000 m{sup 2}/min. These values are in agreement with results of model calculations and former field measurements. The vertical growth is often limited by boundaries of the humid layer at flight level, but values up to 18 m/min were observed. Optical parameters like depolarization, optical depth and lidar ratio, i.e. the extinction-to-backscatter ratio, have been retrieved from the measurements at a wavelength of 532 nm. The linear depolarization rises from values as low as 0.06 for a young contrail (10 s old) to values around 0.5, typical for aged contrails. The latter indicates the transition from non-crystalline to crystalline particles in persistent contrails within a few minutes. The scatter of depolarization values measured in individual contrails is narrow, independent of the contrails age, and suggests a rather uniform growth of the particles inside a contrail. (author) 18 refs.
Spatial and optical parameters of contrails in the vortex and dispersion regime determined by means of a ground-based scanning lidar

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Freudenthaler, V.; Homburg, F.; Jaeger, H. [Fraunhofer-Inst. fuer Atmosphaerische Umweltforschung (IFU), Garmisch-Partenkirchen (Germany)

1997-12-31

The spatial growth of individual condensation trails (contrails) of commercial aircrafts in the time range from 15 s to 60 min behind the aircraft is investigated by means of a ground-based scanning backscatter lidar. The growth in width is mainly governed by wind shear and varies between 18 m/min and 140 m/min. The growth of the cross-section varies between 3500 m{sup 2}/min and 25000 m{sup 2}/min. These values are in agreement with results of model calculations and former field measurements. The vertical growth is often limited by boundaries of the humid layer at flight level, but values up to 18 m/min were observed. Optical parameters like depolarization, optical depth and lidar ratio, i.e. the extinction-to-backscatter ratio, have been retrieved from the measurements at a wavelength of 532 nm. The linear depolarization rises from values as low as 0.06 for a young contrail (10 s old) to values around 0.5, typical for aged contrails. The latter indicates the transition from non-crystalline to crystalline particles in persistent contrails within a few minutes. The scatter of depolarization values measured in individual contrails is narrow, independent of the contrails age, and suggests a rather uniform growth of the particles inside a contrail. (author) 18 refs.
Do supersonic aircraft avoid contrails?

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A. Stenke

2008-02-01

Full Text Available The impact of a potential future fleet of supersonic aircraft on contrail coverage and contrail radiative forcing is investigated by means of simulations with the general circulation model ECHAM4.L39(DLR including a contrail parameterization. The model simulations consider air traffic inventories of a subsonic fleet and of a combined fleet of sub- and supersonic aircraft for the years 2025 and 2050, respectively. In case of the combined fleet, part of the subsonic fleet is replaced by supersonic aircraft. The combined air traffic scenario reveals a reduction in contrail cover at subsonic cruise levels (10 to 12 km in the northern extratropics, especially over the North Atlantic and North Pacific. At supersonic flight levels (18 to 20 km, contrail formation is mainly restricted to tropical regions. Only in winter is the northern extratropical stratosphere above the 100 hPa level cold enough for the formation of contrails. Total contrail coverage is only marginally affected by the shift in flight altitude. The model simulations indicate a global annual mean contrail cover of 0.372% for the subsonic and 0.366% for the combined fleet in 2050. The simulated contrail radiative forcing is most closely correlated to the total contrail cover, although contrails in the tropical lower stratosphere are found to be optically thinner than contrails in the extratropical upper troposphere. The global annual mean contrail radiative forcing in 2050 (2025 amounts to 24.7 mW m⁻² (9.4 mW m⁻² for the subsonic fleet and 24.2 mW m⁻² (9.3 mW m⁻² for the combined fleet. A reduction of the supersonic cruise speed from Mach 2.0 to Mach 1.6 leads to a downward shift in contrail cover, but does not affect global mean total contrail cover and contrail radiative forcing. Hence the partial substitution of subsonic air traffic leads to a shift of contrail occurrence from mid to low latitudes, but the resulting change in
Impact of biofuels on contrail warming

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Caiazzo, Fabio; Agarwal, Akshat; Speth, Raymond L.; Barrett, Steven R. H.

2017-11-01

Contrails and contrail-cirrus may be the largest source of radiative forcing (RF) attributable to aviation. Biomass-derived alternative jet fuels are a potentially major way to mitigate the climate impacts of aviation by reducing lifecycle CO2 emissions. Given the up to 90% reduction in soot emissions from paraffinic biofuels, the potential for a significant impact on contrail RF due to the reduction in contrail-forming ice nuclei (IN) remains an open question. We simulate contrail formation and evolution to quantify RF over the United States under different emissions scenarios. Replacing conventional jet fuels with paraffinic biofuels generates two competing effects. First, the higher water emissions index results in an increase in contrail occurrence (~ +8%). On the other hand, these contrails are composed of larger diameter crystals (~ +58%) at lower number concentrations (~ -75%), reducing both contrail optical depth (~ -29%) and albedo (~ -32%). The net changes in contrail RF induced by switching to biofuels range from -4% to +18% among a range of assumed ice crystal habits (shapes). In comparison, cleaner burning engines (with no increase in water emissions index) result in changes to net contrail RF ranging between -13% and +5% depending on habit. Thus, we find that even 67% to 75% reductions in aircraft soot emissions are insufficient to substantially reduce warming from contrails, and that the use of biofuels may either increase or decrease contrail warming—contrary to previous expectations of a significant decrease in warming.
Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing.

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Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

2010-11-09

Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model's diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m(2) to 11.6 mW/m(2) for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8-20 mW/m(2) for the air traffic in the year 2000.
A methodology for in-situ and remote sensing of microphysical and radiative properties of contrails as they evolve into cirrus

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Jones, H. M.; Haywood, J.; Marenco, F.; O'Sullivan, D.; Meyer, J.; Thorpe, R.; Gallagher, M. W.; Krämer, M.; Bower, K. N.; Rädel, G.; Rap, A.; Woolley, A.; Forster, P.; Coe, H.

2012-09-01

Contrails and especially their evolution into cirrus-like clouds are thought to have very important effects on local and global radiation budgets, though are generally not well represented in global climate models. Lack of contrail parameterisations is due to the limited availability of in situ contrail measurements which are difficult to obtain. Here we present a methodology for successful sampling and interpretation of contrail microphysical and radiative data using both in situ and remote sensing instrumentation on board the FAAM BAe146 UK research aircraft as part of the COntrails Spreading Into Cirrus (COSIC) study. Forecast models were utilised to determine flight regions suitable for contrail formation and sampling; regions that were both free of cloud but showed a high probability of occurrence of air mass being supersaturated with respect to ice. The FAAM research aircraft, fitted with cloud microphysics probes and remote sensing instruments, formed a distinctive spiral-shaped contrail in the predicted area by flying in an orbit over the same ground position as the wind advected the contrails to the east. Parts of these contrails were sampled during the completion of four orbits, with sampled contrail regions being between 7 and 30 min old. Lidar measurements were useful for in-flight determination of the location and spatial extent of the contrails, and also to report extinction values that agreed well with those calculated from the microphysical data. A shortwave spectrometer was also able to detect the contrails, though the signal was weak due to the dispersion and evaporation of the contrails. Post-flight the UK Met Office NAME III dispersion model was successfully used as a tool for modelling the dispersion of the persistent contrail; determining its location and age, and determining when there was interference from other measured aircraft contrails or when cirrus encroached on the area later in the flight. The persistent contrails were found to
A methodology for in-situ and remote sensing of microphysical and radiative properties of contrails as they evolve into cirrus

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H. M. Jones

2012-09-01

Full Text Available Contrails and especially their evolution into cirrus-like clouds are thought to have very important effects on local and global radiation budgets, though are generally not well represented in global climate models. Lack of contrail parameterisations is due to the limited availability of in situ contrail measurements which are difficult to obtain. Here we present a methodology for successful sampling and interpretation of contrail microphysical and radiative data using both in situ and remote sensing instrumentation on board the FAAM BAe146 UK research aircraft as part of the COntrails Spreading Into Cirrus (COSIC study.

Forecast models were utilised to determine flight regions suitable for contrail formation and sampling; regions that were both free of cloud but showed a high probability of occurrence of air mass being supersaturated with respect to ice. The FAAM research aircraft, fitted with cloud microphysics probes and remote sensing instruments, formed a distinctive spiral-shaped contrail in the predicted area by flying in an orbit over the same ground position as the wind advected the contrails to the east. Parts of these contrails were sampled during the completion of four orbits, with sampled contrail regions being between 7 and 30 min old. Lidar measurements were useful for in-flight determination of the location and spatial extent of the contrails, and also to report extinction values that agreed well with those calculated from the microphysical data. A shortwave spectrometer was also able to detect the contrails, though the signal was weak due to the dispersion and evaporation of the contrails. Post-flight the UK Met Office NAME III dispersion model was successfully used as a tool for modelling the dispersion of the persistent contrail; determining its location and age, and determining when there was interference from other measured aircraft contrails or when cirrus encroached on the area later in the flight.

The
Large-eddy simulation of contrails

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Chlond, A [Max-Planck-Inst. fuer Meteorologie, Hamburg (Germany)

1998-12-31

A large eddy simulation (LES) model has been used to investigate the role of various external parameters and physical processes in the life-cycle of contrails. The model is applied to conditions that are typical for those under which contrails could be observed, i.e. in an atmosphere which is supersaturated with respect to ice and at a temperature of approximately 230 K or colder. The sensitivity runs indicate that the contrail evolution is controlled primarily by humidity, temperature and static stability of the ambient air and secondarily by the baroclinicity of the atmosphere. Moreover, it turns out that the initial ice particle concentration and radiative processes are of minor importance in the evolution of contrails at least during the 30 minutes simulation period. (author) 9 refs.
Large-eddy simulation of contrails

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Chlond, A. [Max-Planck-Inst. fuer Meteorologie, Hamburg (Germany)

1997-12-31

A large eddy simulation (LES) model has been used to investigate the role of various external parameters and physical processes in the life-cycle of contrails. The model is applied to conditions that are typical for those under which contrails could be observed, i.e. in an atmosphere which is supersaturated with respect to ice and at a temperature of approximately 230 K or colder. The sensitivity runs indicate that the contrail evolution is controlled primarily by humidity, temperature and static stability of the ambient air and secondarily by the baroclinicity of the atmosphere. Moreover, it turns out that the initial ice particle concentration and radiative processes are of minor importance in the evolution of contrails at least during the 30 minutes simulation period. (author) 9 refs.
Parametrization of contrails in a comprehensive climate model

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Ponater, M; Brinkop, S; Sausen, R; Schumann, U [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1998-12-31

A contrail parametrization scheme for a general circulation model (GCM) is presented. Guidelines for its development were that it should be based on the thermodynamic theory of contrail formation and that it should be consistent with the cloud parametrization scheme of the GCM. Results of a six-year test integration indicate reasonable results concerning the spatial and temporal development of both contrail coverage and contrail optical properties. Hence, the scheme forms a promising basis for the quantitative estimation of the contrail climatic impact. (author) 9 refs.
Parametrization of contrails in a comprehensive climate model

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Ponater, M.; Brinkop, S.; Sausen, R.; Schumann, U. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

A contrail parametrization scheme for a general circulation model (GCM) is presented. Guidelines for its development were that it should be based on the thermodynamic theory of contrail formation and that it should be consistent with the cloud parametrization scheme of the GCM. Results of a six-year test integration indicate reasonable results concerning the spatial and temporal development of both contrail coverage and contrail optical properties. Hence, the scheme forms a promising basis for the quantitative estimation of the contrail climatic impact. (author) 9 refs.
Measurement of Contrails Using ADS-B Data

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Martin Voráček

2016-01-01

Full Text Available Air transport contributes to climate changes not only by greenhouse gas production but also because of production of contrails. The effect of contrails is less scientifically understood compared to greenhouse gases according to IPCC [3]. In order to be able to research the effect of contrails on the atmosphere, it is necessary to identify their realistic frequency of occurrence and to define the relationship between their occurrence and other factors. The effort to identify and monitor contrails and their dependence on the type of air traffic is the objective of SGS project.
Microphysical properties of contrails and natural cirrus clouds

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Strauss, B; Wendling, P [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany)

1998-12-31

The radiative properties of a condensation trail (contrail) are determined by its microphysical properties. Therefore an understanding of the concentration, size distribution, and shapes of the particles is necessary for an estimation of the climatic impact of contrails. In-situ particle measurements by use of an ice replicator are presented for several contrail and cirrus events. Contrail particles aged about 2 minutes show shapes which are nearly spherical. Typical sizes are 5 to 10 {mu}m. Concentration values reach up to the order of 1000 cm{sup -3}. Aged contrail size distributions are within the variability of those found in natural cirrus clouds. (author) 2 refs.

Microphysical properties of contrails and natural cirrus clouds

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Strauss, B.; Wendling, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany)

1997-12-31

The radiative properties of a condensation trail (contrail) are determined by its microphysical properties. Therefore an understanding of the concentration, size distribution, and shapes of the particles is necessary for an estimation of the climatic impact of contrails. In-situ particle measurements by use of an ice replicator are presented for several contrail and cirrus events. Contrail particles aged about 2 minutes show shapes which are nearly spherical. Typical sizes are 5 to 10 {mu}m. Concentration values reach up to the order of 1000 cm{sup -3}. Aged contrail size distributions are within the variability of those found in natural cirrus clouds. (author) 2 refs.
Contrail observations from space using NOAA-AVHRR data

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Mannstein, H. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

The infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) onboard of the weather satellites of the NOAA series allow the detection of contrails. An automated detection scheme is described and tested against computer aided visual classifications by two experts. The algorithm seems to identify contrails within the satellite data with a skill comparable to the human observers. Clusters of contrails within the satellite images are connected to outline regions where the atmospheric properties are favourable for the existence of observable contrails. Air traffic data shows that, over Middle Europe at least, in the main flight levels most of these regions should be marked by detectable contrails. The mean areal coverage of these regions is estimated to be in the range of 10% to 20%, the cloud coverage by detected contrails was 0.9% in 60 AVHRR scenes covering Central Europe. (author) 3 refs.
Remote sensing of contrails and aircraft altered cirrus clouds

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Palikonda, R.; Nguyen, L.; Garber, D.P.; Smith, W.L. Jr [Analytical Services and Materials, Inc., Hampton, VA (United States); Minnis, P.; Young, D.F. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

1997-12-31

Analyses of satellite imagery are used to show that contrails can develop into fully extended cirrus cloud systems. Contrails can be advective on great distances, but would appear to observers as natural cirrus clouds. The conversion of simple contrails into cirrus may help explain the apparent increase of cloudiness over populated areas since the beginning of commercial jet air travel. Statistics describing the typical growth, advection, and lifetime of contrail cirrus is needed to evaluate their effects on climate. (author) 4 refs.
Remote sensing of contrails and aircraft altered cirrus clouds

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Palikonda, R; Nguyen, L; Garber, D P; Smith, Jr, W L [Analytical Services and Materials, Inc., Hampton, VA (United States); Minnis, P; Young, D F [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

1998-12-31

Analyses of satellite imagery are used to show that contrails can develop into fully extended cirrus cloud systems. Contrails can be advective on great distances, but would appear to observers as natural cirrus clouds. The conversion of simple contrails into cirrus may help explain the apparent increase of cloudiness over populated areas since the beginning of commercial jet air travel. Statistics describing the typical growth, advection, and lifetime of contrail cirrus is needed to evaluate their effects on climate. (author) 4 refs.
A simple framework for assessing the trade-off between the climate impact of aviation carbon dioxide emissions and contrails for a single flight

International Nuclear Information System (INIS)

A Irvine, E; J Hoskins, B; P Shine, K

2014-01-01

Persistent contrails are an important climate impact of aviation which could potentially be reduced by re-routing aircraft to avoid contrailing; however this generally increases both the flight length and its corresponding CO 2 emissions. Here, we provide a simple framework to assess the trade-off between the climate impact of CO 2 emissions and contrails for a single flight, in terms of the absolute global warming potential and absolute global temperature potential metrics for time horizons of 20, 50 and 100 years. We use the framework to illustrate the maximum extra distance (with no altitude changes) that can be added to a flight and still reduce its overall climate impact. Small aircraft can fly up to four times further to avoid contrailing than large aircraft. The results have a strong dependence on the applied metric and time horizon. Applying a conservative estimate of the uncertainty in the contrail radiative forcing and climate efficacy leads to a factor of 20 difference in the maximum extra distance that could be flown to avoid a contrail. The impact of re-routing on other climatically-important aviation emissions could also be considered in this framework. (letters)
A numerical simulation of a contrail

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Levkov, L.; Boin, M.; Meinert, D. [GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht (Germany)

1997-12-31

The formation of a contrail from an aircraft flying near the tropopause is simulated using a three-dimensional mesoscale atmospheric model including a very complex scheme of parameterized cloud microphysical processes. The model predicted ice concentrations are in very good agreement with data measured during the International Cirrus Experiment (ICE), 1989. Sensitivity simulations were run to determine humidity forcing on the life time of contrails. (author) 4 refs.
A numerical simulation of a contrail

Energy Technology Data Exchange (ETDEWEB)

Levkov, L; Boin, M; Meinert, D [GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht (Germany)

1998-12-31

The formation of a contrail from an aircraft flying near the tropopause is simulated using a three-dimensional mesoscale atmospheric model including a very complex scheme of parameterized cloud microphysical processes. The model predicted ice concentrations are in very good agreement with data measured during the International Cirrus Experiment (ICE), 1989. Sensitivity simulations were run to determine humidity forcing on the life time of contrails. (author) 4 refs.
Towards a contrail climatology from NOAA-satellite images over Europe

Energy Technology Data Exchange (ETDEWEB)

Bakan, S [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Betancor, M [Hamburg Univ. (Germany). Meteorologisches Inst.; Gayler, V [Hamburg Univ. (Germany). Meteorologisches Inst.; Grassl, H [Hamburg Univ. (Germany). Meteorologisches Inst.; [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)

1993-11-01

Contrail cloudiness over Europe and the eastern part of the North Atlantic Ocean was analyzed for the two periods Sept. 1979-Dec. 1981 and Sept. 1989-Aug. 1992 by visual inspection of quicklook photographic prints of NOAA/AVHRR infrared images. The averaged contrail cover exhibits maximum values along the transatlantic flight corridor around 50 N (of almost 2%) and over western Europe resulting in 0.5% contrail cloudiness on the average. A strong yearly cycle appears with a maximum (<2%) in spring and summer over the Atlantic and a smaller maximum (<1%) in winter over southwestern Europe. Comparing the two time periods of one decade separation there is a significant decrease in contrail cloudiness over western Europe and a significant increase over the North Atlantic observable between March and July. Contrail cloud cover during daytime is about twice as high as during nighttime. Contrails are preferably found in larger fields of 1000 km diameter which last usually for more than one day. Causes, possible errors and consequences are discussed. (orig.)
Towards a contrail climatology from NOAA-satellite images over Europe

International Nuclear Information System (INIS)

Bakan, S.; Betancor, M.

1993-01-01

Contrail cloudiness over Europe and the eastern part of the North Atlantic Ocean was analyzed for the two periods Sept. 1979-Dec. 1981 and Sept. 1989-Aug. 1992 by visual inspection of quicklook photographic prints of NOAA/AVHRR infrared images. The averaged contrail cover exhibits maximum values along the transatlantic flight corridor around 50 N (of almost 2%) and over western Europe resulting in 0.5% contrail cloudiness on the average. A strong yearly cycle appears with a maximum (<2%) in spring and summer over the Atlantic and a smaller maximum (<1%) in winter over southwestern Europe. Comparing the two time periods of one decade separation there is a significant decrease in contrail cloudiness over western Europe and a significant increase over the North Atlantic observable between March and July. Contrail cloud cover during daytime is about twice as high as during nighttime. Contrails are preferably found in larger fields of 1000 km diameter which last usually for more than one day. Causes, possible errors and consequences are discussed. (orig.)
Towards a Model Climatology of Relative Humidity in the Upper Troposphere for Estimation of Contrail and Contrail-Induced Cirrus

Science.gov (United States)

Selkirk, Henry B.; Manyin, M.; Ott, L.; Oman, L.; Benson, C.; Pawson, S.; Douglass, A. R.; Stolarski, R. S.

2011-01-01

The formation of contrails and contrail cirrus is very sensitive to the relative humidity of the upper troposphere. To reduce uncertainty in an estimate of the radiative impact of aviation-induced cirrus, a model must therefore be able to reproduce the observed background moisture fields with reasonable and quantifiable fidelity. Here we present an upper tropospheric moisture climatology from a 26-year ensemble of simulations using the GEOS CCM. We compare this free-running model's moisture fields to those obtained from the MLS and AIRS satellite instruments, our most comprehensive observational databases for upper tropospheric water vapor. Published comparisons have shown a substantial wet bias in GEOS-5 assimilated fields with respect to MLS water vapor and ice water content. This tendency is clear as well in the GEOS CCM simulations. The GEOS-5 moist physics in the GEOS CCM uses a saturation adjustment that prevents supersaturation, which is unrealistic when compared to in situ moisture observations from MOZAIC aircraft and balloon sondes as we will show. Further, the large-scale satellite datasets also consistently underestimate super-saturation when compared to the in-situ observations. We place these results in the context of estimates of contrail and contrail cirrus frequency.
Contrails and their impact on shortwave radiation and photovoltaic power production – a regional model study

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S. Gruber

2018-05-01

Full Text Available A high-resolution regional-scale numerical model was extended by a parameterization that allows for both the generation and the life cycle of contrails and contrail cirrus to be calculated. The life cycle of contrails and contrail cirrus is described by a two-moment cloud microphysical scheme that was extended by a separate contrail ice class for a better representation of the high concentration of small ice crystals that occur in contrails. The basic input data set contains the spatially and temporally highly resolved flight trajectories over Central Europe derived from real-time data. The parameterization provides aircraft-dependent source terms for contrail ice mass and number. A case study was performed to investigate the influence of contrails and contrail cirrus on the shortwave radiative fluxes at the earth's surface. Accounting for contrails produced by aircraft enabled the model to simulate high clouds that were otherwise missing on this day. The effect of these extra clouds was to reduce the incoming shortwave radiation at the surface as well as the production of photovoltaic power by up to 10 %.
In-situ observations of young contrails – overview and selected results from the CONCERT campaign

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C. Voigt

2010-09-01

Full Text Available Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT – CONtrail and Cirrus ExpeRimenT – campaign in October/November 2008. The Falcon was equipped with a set of instruments to measure the particle size distribution, shape, extinction and chemical composition as well as trace gas mixing ratios of sulfur dioxide (SO₂, reactive nitrogen and halogen species (NO, NO_y, HNO₃, HONO, HCl, ozone (O₃ and carbon monoxide (CO. During 12 mission flights over Europe, numerous contrails, cirrus clouds and a volcanic aerosol layer were probed at altitudes between 8.5 and 11.6 km and at temperatures above 213 K. 22 contrails from 11 different aircraft were observed near and below ice saturation. The observed NO mixing ratios, ice crystal and soot number densities are compared to a process based contrail model. On 19 November 2008 the contrail from a CRJ-2 aircraft was penetrated in 10.1 km altitude at a temperature of 221 K. The contrail had mean ice crystal number densities of 125 cm⁻³ with effective radii r_eff of 2.6 μm. The presence of particles with r>50 μm in the less than 2 min old contrail suggests that natural cirrus crystals were entrained in the contrail. Mean HONO/NO (HONO/NO_y ratios of 0.037 (0.024 and the fuel sulfur conversion efficiency to H₂SO₄ (ε_S↓ of 2.9 % observed in the CRJ-2 contrail are in the range of previous measurements in the gaseous aircraft exhaust. On 31 October 2010 aviation NO emissions could have contributed by more than 40% to the regional scale NO levels in the mid-latitude lowest stratosphere. The CONCERT observations help to better quantify the climate impact from contrails and will be used to investigate the chemical processing of trace gases on contrails.
Variability of the contrail radiative forcing due to crystal shape

Science.gov (United States)

Markowicz, K. M.; Witek, M. L.

2011-12-01

The aim of this study is to examine the influence of particles' shape and particles' optical properties on the contrail radiative forcing. Contrail optical properties in the shortwave and longwave range are derived using a ray-tracing geometric method and the discrete dipole approximation method, respectively. Both methods present good correspondence of the single scattering albedo and the asymmetry parameter in a transition range (3-7μm). We compare optical properties defined following simple 10 crystals habits randomly oriented: hexagonal plates, hexagonal columns with different aspect ratio, and spherical. There are substantial differences in single scattering properties between ten crystal models investigated here (e.g. hexagonal columns and plates with different aspect ratios, spherical particles). The single scattering albedo and the asymmetry parameter both vary up to 0.1 between various crystal shapes. Radiative forcing calculations were performed using a model which includes an interface between the state-of-the-art radiative transfer model Fu-Liou and databases containing optical properties of the atmosphere and surface reflectance and emissivity. This interface allows to determine radiative fluxes in the atmosphere and to estimate the contrail radiative forcing for clear- and all-sky (including natural clouds) conditions for various crystal shapes. The Fu-Liou code is fast and therefore it is suitable for computing radiative forcing on a global scale. At the same time it has sufficiently good accuracy for such global applications. A noticeable weakness of the Fu-Liou code is that it does not take into account the 3D radiative effects, e.g. cloud shading and horizontal. Radiative transfer model calculations were performed at horizontal resolution of 5x5 degree and time resolution of 20 min during day and 3 h during night. In order to calculate a geographic distribution of the global and annual mean contrail radiative forcing, the contrail cover must be
Parametric studies of contrail ice particle formation in jet regime using microphysical parcel modeling

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H.-W. Wong

2010-04-01

Full Text Available Condensation trails (contrails formed from water vapor emissions behind aircraft engines are the most uncertain components of the aviation impacts on climate change. To gain improved knowledge of contrail and contrail-induced cirrus cloud formation, understanding of contrail ice particle formation immediately after aircraft engines is needed. Despite many efforts spent in modeling the microphysics of ice crystal formation in jet regime (with a plume age <5 s, systematic understanding of parametric effects of variables affecting contrail ice particle formation is still limited. In this work, we apply a microphysical parcel modeling approach to study contrail ice particle formation in near-field aircraft plumes up to 1000 m downstream of an aircraft engine in the soot-rich regime (soot number emission index >1×10¹⁵ (kg-fuel⁻¹ at cruise. The effects of dilution history, ion-mediated nucleation, ambient relative humidity, fuel sulfur contents, and initial soot emissions were investigated. Our simulation results suggest that ice particles are mainly formed by water condensation on emitted soot particles. The growth of ice coated soot particles is driven by water vapor emissions in the first 1000 m and by ambient relative humidity afterwards. The presence of chemi-ions does not significantly contribute to the formation of ice particles in the soot-rich regime, and the effect of fuel sulfur contents is small over the range typical of standard jet fuels. The initial properties of soot emissions play the most critical role, and our calculations suggest that higher number concentration and smaller size of contrail particle nuclei may be able to effectively suppress the formation of contrail ice particles. Further modeling and experimental studies are needed to verify if our findings can provide a possible approach for contrail mitigation.
Carbon balance of China constrained by CONTRAIL aircraft CO2 measurements

Science.gov (United States)

Jiang, F.; Wang, H. M.; Chen, J. M.; Machida, T.; Zhou, L. X.; Ju, W. M.; Matsueda, H.; Sawa, Y.

2014-09-01

Terrestrial carbon dioxide (CO2) flux estimates in China using atmospheric inversion method are beset with considerable uncertainties because very few atmospheric CO2 concentration measurements are available. In order to improve these estimates, nested atmospheric CO2 inversion during 2002-2008 is performed in this study using passenger aircraft-based CO2 measurements over Eurasia from the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project. The inversion system includes 43 regions with a focus on China, and is based on the Bayesian synthesis approach and the TM5 transport model. The terrestrial ecosystem carbon flux modeled by the Boreal Ecosystems Productivity Simulator (BEPS) model and the ocean exchange simulated by the OPA-PISCES-T model are considered as the prior fluxes. The impacts of CONTRAIL CO2 data on inverted China terrestrial carbon fluxes are quantified, the improvement of the inverted fluxes after adding CONTRAIL CO2 data are rationed against climate factors and evaluated by comparing the simulated atmospheric CO2 concentrations with three independent surface CO2 measurements in China. Results show that with the addition of CONTRAIL CO2 data, the inverted carbon sink in China increases while those in South and Southeast Asia decrease. Meanwhile, the posterior uncertainties over these regions are all reduced (2-12%). CONTRAIL CO2 data also have a large effect on the inter-annual variation of carbon sinks in China, leading to a better correlation between the carbon sink and the annual mean climate factors. Evaluations against the CO2 measurements at three sites in China also show that the CONTRAIL CO2 measurements may have improved the inversion results.
On the regional climatic impact of contrails: microphysical and radiative properties of contrails and natural cirrus clouds

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B. Strauss

Full Text Available The impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM. The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 µm, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 µm. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2K in July and from 0.8 to 0.9K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05K.
On the regional climatic impact of contrails: microphysical and radiative properties of contrails and natural cirrus clouds

Directory of Open Access Journals (Sweden)

B. Strauss

1997-11-01

Full Text Available The impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM. The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 µm, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 µm. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2K in July and from 0.8 to 0.9K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05K.
Ground-based mobile scanning LIDAR for remote sensing of contrails

Directory of Open Access Journals (Sweden)

F. Homburg

Full Text Available Air traffic is a source of trace gases in the upper troposphere and lower stratosphere. Contrails readily form from water vapor exhausts under favorable meteorological conditions. Since contrails are ice crystal clouds like natural cirrus clouds, they bear a greenhouse potential which has to be investigated. The IFU has built a scanning lidar system employing a pulsed Nd:YAG laser as the emitter and a 52-cm diameter telescope as the receiver. Signals are processed in several channels to investigate depolarization and wavelength dependencies of the light backscattered from ice crystals. These investigations are aimed at the formation and life cycles of contrails, their optical properties, and their climatological consequences in areas of dense air traffic. The experimental lidar setup is described and a sample measurement is shown.
Ground-based mobile scanning LIDAR for remote sensing of contrails

Directory of Open Access Journals (Sweden)

V. Freudenthaler

1994-08-01

Full Text Available Air traffic is a source of trace gases in the upper troposphere and lower stratosphere. Contrails readily form from water vapor exhausts under favorable meteorological conditions. Since contrails are ice crystal clouds like natural cirrus clouds, they bear a greenhouse potential which has to be investigated. The IFU has built a scanning lidar system employing a pulsed Nd:YAG laser as the emitter and a 52-cm diameter telescope as the receiver. Signals are processed in several channels to investigate depolarization and wavelength dependencies of the light backscattered from ice crystals. These investigations are aimed at the formation and life cycles of contrails, their optical properties, and their climatological consequences in areas of dense air traffic. The experimental lidar setup is described and a sample measurement is shown.
Contrails over the U.S. and their potential impact on the radiation budget

Energy Technology Data Exchange (ETDEWEB)

Minnis, P [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Ayers, J K; Doelling, D R [Analytical Services and Materials, Inc., Hampton, VA (United States)

1998-12-31

A methodology for assessing the contrail impact on the radiation budget is developed to use data characterizing the frequency, areal coverage, optical depth, particle size, and altitude of contrails with observations of cloud and surface properties. The method is tested using various scenarios over the United States to estimate contrail-induced albedo changes based on current aircraft fuel usage statistics. The technique can be used for estimating infrared effects and the impact of future fuel-use rates. (author) 11 refs.

Contrails over the U.S. and their potential impact on the radiation budget

Energy Technology Data Exchange (ETDEWEB)

Minnis, P. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Ayers, J.K.; Doelling, D.R. [Analytical Services and Materials, Inc., Hampton, VA (United States)

1997-12-31

A methodology for assessing the contrail impact on the radiation budget is developed to use data characterizing the frequency, areal coverage, optical depth, particle size, and altitude of contrails with observations of cloud and surface properties. The method is tested using various scenarios over the United States to estimate contrail-induced albedo changes based on current aircraft fuel usage statistics. The technique can be used for estimating infrared effects and the impact of future fuel-use rates. (author) 11 refs.
Detection of jet contrails from satellite images

Science.gov (United States)

Meinert, Dieter

1994-02-01

In order to investigate the influence of modern technology on the world climate it is important to have automatic detection methods for man-induced parameters. In this case the influence of jet contrails on the greenhouse effect shall be investigated by means of images from polar orbiting satellites. Current methods of line recognition and amplification cannot distinguish between contrails and rather sharp edges of natural cirrus or noise. They still rely on human control. Through the combination of different methods from cloud physics, image comparison, pattern recognition, and artificial intelligence we try to overcome this handicap. Here we will present the basic methods applied to each image frame, and list preliminary results derived this way.
Aircraft clouds: from chemtrail pseudoscience to the science of contrails

OpenAIRE

Mazón Bueso, Jordi; Costa, Marcel; Pino González, David

2018-01-01

The most frequent statements and arguments found in pseudoscience websites and forums supporting the existence of so-called aircraft chemtrails can be refuted with a scientific explanation of the processes resulting in the formation of condensation or deposition trails, known as contrails. Thus, the hypothesis that chemtrails exist is disproven by the scientific literature that shows that they are the exact same entity as contrails: They are hydrological phenomena which result from a physical...
The impact of diurnal variations of air traffic on contrail radiative forcing

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N. Stuber

2007-06-01

Full Text Available We combined high resolution aircraft flight data from the EU Fifth Framework Programme project AERO2k with analysis data from the ECMWF's integrated forecast system to calculate diurnally resolved 3-D contrail cover. We scaled the contrail cover in order to match observational data for the Bakan area (eastern-Atlantic/western-Europe.

We found that less than 40% of the global distance travelled by aircraft is due to flights during local night time. Yet, due to the cancellation of shortwave and longwave effects during daytime, night time flights contribute a disproportional 60% to the global annual mean forcing. Under clear sky conditions the night flights contribute even more disproportionally at 76%. There are pronounced regional variations in night flying and the associated radiative forcing. Over parts of the North Atlantic flight corridor 75% of air traffic and 84% of the forcing occurs during local night, whereas only 35% of flights are during local night in South-East Asia, yet these contribute 68% of the radiative forcing. In general, regions with a significant local contrail radiative forcing are also regions for which night time flights amount to less than half of the daily total of flights. Therefore, neglecting diurnal variations in air traffic/contrail cover by assuming a diurnal mean contrail cover can over-estimate the global mean radiative forcing by up to 30%.
Variability of contrail formation conditions and the implications for policies to reduce the climate impacts of aviation

International Nuclear Information System (INIS)

Williams, Victoria; Noland, Robert B.

2005-01-01

This paper describes an approach to balance the climate benefits of contrail reduction against the penalties incurred when cruise altitudes are restricted. Altitude restrictions are targeted by selecting, for each 6-h period, the altitude that provides the greatest reduction in contrail for the lowest increase in carbon dioxide emission. Calculations are for western Europe. This paper discusses the variability in contrail formation conditions in the region and presents contrail reductions and carbon dioxide emission increases obtained with this optimised approach, which compare favourably with fixed altitude restrictions. A new method is also developed to estimate contrail fractions within three-dimensional grids. Conclusions discuss potential operational issues associated with a varying altitude restriction policy. (Author)
Intercomparison of radiative forcing calculations of stratospheric water vapour and contrails

Energy Technology Data Exchange (ETDEWEB)

Myhre, Gunnar [Dept. of Geosciences, Univ. of Oslo (Norway); Center for International Climate and Environmental Research-Oslo (CICERO), Oslo (Norway); Kvalevaag, Maria [Dept. of Geosciences, Univ. of Oslo (Norway); Raedel, Gaby; Cook, Jolene; Shine, Keith P. [Dept. of Meteorology, Univ. of Reading (United Kingdom); Clark, Hannah [CNRM/GAME Meteo France, Toulouse (France); Lab. d' Aerologie, Univ. de Toulouse (France); Karcher, Fernand [CNRM/GAME Meteo France, Toulouse (France); Markowicz, Krzysztof; Kardas, Aleksandra; Wolkenberg, Paulina [Inst. of Geophysics, Univ. of Warsaw (Poland); Balkanski, Yves [LSCE/IPSL, Lab. CEA-CNRS-UVSQ (France); Ponater, Michael [Deutsches Zentrum fuer Luft und Raumfahrt (DLR), Inst. fuer Physik der Atmosphaere, Oberpfaffenhofen (Germany); Forster, Piers; Rap, Alexandru [School of Earth and Environment, Univ. of Leeds (United Kingdom); Leon, Ruben Rodriguez de [Manchester Metropolitan Univ. (United Kingdom)

2009-12-15

Seven groups have participated in an intercomparison study of calculations of radiative forcing (RF) due to stratospheric water vapour (SWV) and contrails. a combination of detailed radiative transfer schemes and codes for global-scale calculations have been used, as well as a combination of idealized simulations and more realistic global-scale changes in stratospheric water vapour and contrails. Detailed line-by-line codes agree within about 15% for longwave (LW) and shortwave (SW) RF, except in one case where the difference is 30%. Since the LW and SW RF due to contrails and SWV changes are of opposite sign, the differences between the models seen in the individual LW and SW components can be either compensated or strengthened in the net RF. and thus in relative terms uncertainties are much larger for the net RF. Some of the models used for global-scale simulations of changes in SWV and contrails differ substantially in RF from the more detailed radiative transfer schemes. For the global-scale calculations we use a method of weighting the results to calculate a best estimate based on their performance compared to the more detailed radiative transfer schemes in the idealized simulations. (orig.)
Sensitivity of surface temperature to radiative forcing by contrail cirrus in a radiative-mixing model

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U. Schumann

2017-11-01

Full Text Available Earth's surface temperature sensitivity to radiative forcing (RF by contrail cirrus and the related RF efficacy relative to CO2 are investigated in a one-dimensional idealized model of the atmosphere. The model includes energy transport by shortwave (SW and longwave (LW radiation and by mixing in an otherwise fixed reference atmosphere (no other feedbacks. Mixing includes convective adjustment and turbulent diffusion, where the latter is related to the vertical component of mixing by large-scale eddies. The conceptual study shows that the surface temperature sensitivity to given contrail RF depends strongly on the timescales of energy transport by mixing and radiation. The timescales are derived for steady layered heating (ghost forcing and for a transient contrail cirrus case. The radiative timescales are shortest at the surface and shorter in the troposphere than in the mid-stratosphere. Without mixing, a large part of the energy induced into the upper troposphere by radiation due to contrails or similar disturbances gets lost to space before it can contribute to surface warming. Because of the different radiative forcing at the surface and at top of atmosphere (TOA and different radiative heating rate profiles in the troposphere, the local surface temperature sensitivity to stratosphere-adjusted RF is larger for SW than for LW contrail forcing. Without mixing, the surface energy budget is more important for surface warming than the TOA budget. Hence, surface warming by contrails is smaller than suggested by the net RF at TOA. For zero mixing, cooling by contrails cannot be excluded. This may in part explain low efficacy values for contrails found in previous global circulation model studies. Possible implications of this study are discussed. Since the results of this study are model dependent, they should be tested with a comprehensive climate model in the future.
Contrail Cirrus Forecasts for the ML-CIRRUS Experiment and Some Comparison Results

Science.gov (United States)

Schumann, Ulrich; Graf, Kaspar; Bugliaro, Luca; Dörnbrack, Andreas; Giez, Andreas; Jurkat, Tina; Kaufmann, Stefan; Krämer, Martina; Minikin, Andreas; Schäfler, Andreas; Voigt, Christiane; Wirth, Martin; Zahn, Andreas; Ziereis, Helmut

2015-04-01

Model simulations with the contrail cirrus prediction model CoCiP driven by numerical weather prediction (NWP) data provided from the European Centre for Medium Range Forecasts (ECMWF) and global aircraft waypoint data show a mean computed cover (for optical depth larger than 0.1) of 0.23% globally, and 5.4% over mid Europe (Schumann and Graf, JGR, 2013). The computed mean longwave radiative forcing (RF) reaches 3 W m-2 over mid Europe (10°W-20°E and 40°N-55°N), and 0.13 W m-2 globally. The global net RF is about 40-60% smaller because of compensating shortwave cooling induced by contrails during daytime. The results depend on several model details such as the number of ice particles forming from aircraft soot emissions, the contrail plume dispersion, ice particle sedimentation etc., all influencing contrail life time and their optical properties. The quantitative results depend also strongly on ambient relative humidity, vertical motion and on ice water content of other cirrus predicted by the NWP model. In order to test and possibly improve this and other contrail models, high-quality observations are needed to which multi-parameter model output can be compared. The Mid-Latitude Cirrus Experiment ML-CIRRUS was performed (see C. Voigt et al., this conference) with a suite of in-situ and Lidar instruments for airborne measurements on the research aircraft HALO. Before and during the mission, CoCiP was run daily to provide 3-days forecasts of contrail cover using operational ECMWF forecasts and historical traffic data. CoCiP forecast output was made available in an internet tool twice a day for experiment planning. The one-day and two-day contrail forecasts often showed only small differences. Still, most recent forecasts and detailed satellite observations results were transmitted via satellite link to the crew for onboard campaign optimization. After the campaign, a data base of realistic air traffic data has been setup from various sources, and CoCiP was
Regional coverage of contrails from satellite data and their radiative forcing; Regionale Kondensstreifen-Bedeckung aus Satellitendaten und ihr Einfluss auf den Strahlungshaushalt

Energy Technology Data Exchange (ETDEWEB)

Meyer, R.

2000-07-01

An operational contrail detection algorithm is applied to day and night overpasses of the Advanced Very High Resolution Radiometer (AVHRR). From the classification results the daytime and nighttime coverage by linear shaped contrails over Western Europa is derived. The annual daytime average for the analyzed region of 0.75% shows a strong annual cycle with 1.0% coverage during winter and 0.4% during summer. The day/night ratio reaches the factor 3. Using the radiance contrasts in the 11 {mu}m channel for contrail and adjacent pixels an average visible optical depth for the observed contrails of 0.1 is derived. This leads to an annual mean top of atmosphere radiative forcing by contrails over Central Europe in the range of 0.03 W/m{sup 2} to 0.08 W/m{sup 2}, which is about one magnitude smaller than prior studies suggest. The highest annual mean contrail forcing exceeds 0.12 W/m{sup 2} over Northeastern France, Belgium, Great Britain and Hungary. (orig.) [German] Ein operationelles Kondensstreifen-Erkennungsverfahren wird auf Tag- und Nacht-Ueberfluege des Advanced Very High Resolution Radiometer (AVHRR) angewandt. Aus den Klassifizierungsergebnissen wird die mittaegliche und naechtliche Bedeckung durch linienhafte Kondensstreifen ueber Westeuropa abgeleitet. Das Jahresmittel der Bedeckung am Tag betraegt 0,75% und zeigt einen ausgepraegten Jahresgang mit 1% im Winter und 0,4% im Sommer, sowie einen starken Tag/Nacht-Unterschied mit einer Amplitude von 3. Mit Hilfe von Strahldichtekontrasten im 11 {mu}m Kanal zwischen Kondensstreifen und benachbarten Pixeln wird fuer die erkannten Kondensstreifen eine durchschnittliche optische Dicke im sichtbaren Spektralbereich von 0,1 abgeschaetzt. Daraus ergibt sich am Oberrand der Atmosphaere ein mittlerer auf Kondensstreifen zurueckzufuehrender Strahlungsantrieb zwischen 0,03 W/m{sup 2} und 0,08 W/m{sup 2}, was eine Groessenordnung unter den Ergebnissen bisheriger Studien liegt. Die hoechsten Jahresmittel mit mehr als 0,12 W
Experiments on contrail formation from fuels with different sulfur content

Energy Technology Data Exchange (ETDEWEB)

Busen, R; Kuhn, M; Petzold, A; Schroeder, F; Schumann, U [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany); Baumgardner, D [National Center for Atmospheric Research, Boulder, CO (United States); Borrmann, S [Mainz Univ. (Germany); Hagen, D; Whitefield, Ph [Missouri Univ., Rolla, MO (United States). Bureau of Mines; Stroem, J [Stockholm Univ. (Sweden)

1998-12-31

A series of both flight tests and ground experiments has been performed to evaluate the role of the sulfur contained in kerosene in condensation trail (contrail) formation processes. The results of the first experiments are compiled briefly. The last SULFUR 4 experiment dealing with the influence of the fuel sulfur content and different appertaining conditions is described in detail. Different sulfur mass fractions lead to different particle size spectra. The number of ice particles in the contrail increases by about a factor of 2 for 3000 ppm instead of 6 ppm sulfur fuel content. (author) 10 refs.
Experiments on contrail formation from fuels with different sulfur content

Energy Technology Data Exchange (ETDEWEB)

Busen, R.; Kuhn, M.; Petzold, A.; Schroeder, F.; Schumann, U. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany); Baumgardner, D. [National Center for Atmospheric Research, Boulder, CO (United States); Borrmann, S. [Mainz Univ. (Germany); Hagen, D.; Whitefield, Ph. [Missouri Univ., Rolla, MO (United States). Bureau of Mines; Stroem, J. [Stockholm Univ. (Sweden)

1997-12-31

A series of both flight tests and ground experiments has been performed to evaluate the role of the sulfur contained in kerosene in condensation trail (contrail) formation processes. The results of the first experiments are compiled briefly. The last SULFUR 4 experiment dealing with the influence of the fuel sulfur content and different appertaining conditions is described in detail. Different sulfur mass fractions lead to different particle size spectra. The number of ice particles in the contrail increases by about a factor of 2 for 3000 ppm instead of 6 ppm sulfur fuel content. (author) 10 refs.
Multi-scale path planning for reduced environmental impact of aviation

Science.gov (United States)

Campbell, Scot Edward

A future air traffic management system capable of rerouting aircraft trajectories in real-time in response to transient and evolving events would result in increased aircraft efficiency, better utilization of the airspace, and decreased environmental impact. Mixed-integer linear programming (MILP) is used within a receding horizon framework to form aircraft trajectories which mitigate persistent contrail formation, avoid areas of convective weather, and seek a minimum fuel solution. Areas conducive to persistent contrail formation and areas of convective weather occur at disparate temporal and spatial scales, and thereby require the receding horizon controller to be adaptable to multi-scale events. In response, a novel adaptable receding horizon controller was developed to account for multi-scale disturbances, as well as generate trajectories using both a penalty function approach for obstacle penetration and hard obstacle avoidance constraints. A realistic aircraft fuel burn model based on aircraft data and engine performance simulations is used to form the cost function in the MILP optimization. The performance of the receding horizon algorithm is tested through simulation. A scalability analysis of the algorithm is conducted to ensure the tractability of the path planner. The adaptable receding horizon algorithm is shown to successfully negotiate multi-scale environments with performance exceeding static receding horizon solutions. The path planner is applied to realistic scenarios involving real atmospheric data. A single flight example for persistent contrail mitigation shows that fuel burn increases 1.48% when approximately 50% of persistent contrails are avoided, but 6.19% when 100% of persistent contrails are avoided. Persistent contrail mitigating trajectories are generated for multiple days of data, and the research shows that 58% of persistent contrails are avoided with a 0.48% increase in fuel consumption when averaged over a year.
Numerical simulations of contrail-to-cirrus transition – Part 2: Impact of initial ice crystal number, radiation, stratification, secondary nucleation and layer depth

Directory of Open Access Journals (Sweden)

S. Unterstrasser

2010-02-01

Full Text Available Simulations of contrail-to-cirrus transition were performed with an LES model. In Part 1 the impact of relative humidity, temperature and vertical wind shear was explored in a detailed parametric study. Here, we study atmospheric parameters like stratification and depth of the supersaturated layer and processes which may affect the contrail evolution. We consider contrails in various radiation scenarios herein defined by the season, time of day and the presence of lower-level cloudiness which controls the radiance incident on the contrail layer. Under suitable conditions, controlled by the radiation scenario and stratification, radiative heating lifts the contrail-cirrus and prolongs its lifetime. The potential of contrail-driven secondary nucleation is investigated. We consider homogeneous nucleation and heterogeneous nucleation of preactivated soot cores released from sublimated contrail ice crystals. In our model the contrail dynamics triggered by radiative heating does not suffice to force homogeneous freezing of ambient liquid aerosol particles. Furthermore, our model results suggest that heterogeneous nucleation of preactivated soot cores is unimportant. Contrail evolution is not controlled by the depth of the supersaturated layer as long as it exceeds roughly 500 m. Deep fallstreaks however need thicker layers. A variation of the initial ice crystal number is effective during the whole evolution of a contrail. A cut of the soot particle emission by two orders of magnitude can reduce the contrail timescale by one hour and the optical thickness by a factor of 5. Hence future engines with lower soot particle emissions could potentially lead to a reduction of the climate impact of aviation.
Microphysical and optical properties of contrails and cirrus

Energy Technology Data Exchange (ETDEWEB)

Gayet, J F; Febvre, G [Universite Blaise Pascal, Clermont-Ferand (France). Lab. de Meteorologie Physique; Brogniez, G [Universite des Sciences et Techniques de Lille, (France). Lab. d` Optique Atmospherique; Wendling, P [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Larsen, H [National Inst. for Water and Atmospheric Research, Wellington (New Zealand)

1998-12-31

Aircraft contrails have significantly different properties to natural cirrus clouds. Their local and global climate impact cannot be assessed without consideration of these differences. Microphysical data were obtained from the Merlin aircraft equipped with a PMS FSSP-100 for particle spectrum measurements over the 3 {mu}m to 45 {mu}m diameter range; a PMS 2D-C for particle size spectrum and particle shape over the size range from 25 {mu}m to 800 {mu}m and a Johnson-Williams cloud liquid-water probe. Radiative measurements were obtained from a Do228 aircraft which carried the upward looking ALEX-F Lidar operating at a wavelength of 1.06 {mu}m and a Barnes PRT-5 radiometer aligned parallel to the lidar and with a 9 to 11 {mu}m spectral range. The limitation in accuracy of cloud microphysical sensor used in contrail studies are also discussed with subsequent errors on description of cloud radiative properties. (R.P.) 9 refs.
Microphysical and optical properties of contrails and cirrus

Energy Technology Data Exchange (ETDEWEB)

Gayet, J.F.; Febvre, G. [Universite Blaise Pascal, Clermont-Ferand (France). Lab. de Meteorologie Physique; Brogniez, G. [Universite des Sciences et Techniques de Lille, (France). Lab. d`Optique Atmospherique; Wendling, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Larsen, H. [National Inst. for Water and Atmospheric Research, Wellington (New Zealand)

1997-12-31

Aircraft contrails have significantly different properties to natural cirrus clouds. Their local and global climate impact cannot be assessed without consideration of these differences. Microphysical data were obtained from the Merlin aircraft equipped with a PMS FSSP-100 for particle spectrum measurements over the 3 {mu}m to 45 {mu}m diameter range; a PMS 2D-C for particle size spectrum and particle shape over the size range from 25 {mu}m to 800 {mu}m and a Johnson-Williams cloud liquid-water probe. Radiative measurements were obtained from a Do228 aircraft which carried the upward looking ALEX-F Lidar operating at a wavelength of 1.06 {mu}m and a Barnes PRT-5 radiometer aligned parallel to the lidar and with a 9 to 11 {mu}m spectral range. The limitation in accuracy of cloud microphysical sensor used in contrail studies are also discussed with subsequent errors on description of cloud radiative properties. (R.P.) 9 refs.
Extrapolation of contrail investigations by LIDAR to larger scale measurements. Analysis and calibration of CCD camera and satellite images

Energy Technology Data Exchange (ETDEWEB)

Sussmann, R.; Homburg, F.; Freudenthaler, V.; Jaeger, H. [Frauenhofer Inst. fuer Atmosphaerische Umweltforschung, Garmisch-Partenkirchen (Germany)

1997-12-31

The CCD image of a persistent contrail and the coincident LIDAR measurement are presented. To extrapolate the LIDAR derived optical thickness to the video field of view an anisotropy correction and calibration has to be performed. Observed bright halo components result from highly regular oriented hexagonal crystals with sizes of 200 {mu}m-2 mm. This explained by measured ambient humidities below the formation threshold of natural cirrus. Optical thickness from LIDAR shows significant discrepancies to the result from coincident NOAA-14 data. Errors result from anisotropy correction and parameterized relations between AVHRR channels and optical properties. (author) 28 refs.
In situ observations of contrail micro-physics and implications for their radiative impact

Energy Technology Data Exchange (ETDEWEB)

Poellot, M R [North Dakota Univ., Grand Forks, ND (United States); Arnott, W P; Hallett, J [Nevada Univ., Reno, NV (United States). Desert Research Inst.

1998-12-31

Increasing levels of air traffic have raised concerns about the potential effects of aircraft exhaust on the climate. Current knowledge is expanded by examining in situ data from 21 contrails sampled at altitudes of 9.3 - 12.5 km and temperatures of -47 deg C to -66 deg C. The airborne equipment allowed measurements of particles as small as 2 {mu}m in diameter, which have not previously been reported. The microphysical characteristics of the contrails, which occurred in both clear and cloudy air, are presented and compared with natural cirrus properties. Computations of the wavelength-dependent radiative properties of the sampled particle distributions are also presented and compared with laboratory measurements. Finally, implications of these findings for climatic assessment are discussed. (R.P.) 9 refs.
In situ observations of contrail micro-physics and implications for their radiative impact

Energy Technology Data Exchange (ETDEWEB)

Poellot, M.R. [North Dakota Univ., Grand Forks, ND (United States); Arnott, W.P.; Hallett, J. [Nevada Univ., Reno, NV (United States). Desert Research Inst.

1997-12-31

Increasing levels of air traffic have raised concerns about the potential effects of aircraft exhaust on the climate. Current knowledge is expanded by examining in situ data from 21 contrails sampled at altitudes of 9.3 - 12.5 km and temperatures of -47 deg C to -66 deg C. The airborne equipment allowed measurements of particles as small as 2 {mu}m in diameter, which have not previously been reported. The microphysical characteristics of the contrails, which occurred in both clear and cloudy air, are presented and compared with natural cirrus properties. Computations of the wavelength-dependent radiative properties of the sampled particle distributions are also presented and compared with laboratory measurements. Finally, implications of these findings for climatic assessment are discussed. (R.P.) 9 refs.
On the climatic impact of contrails

Energy Technology Data Exchange (ETDEWEB)

Strauss, B.; Meerkoetter, R.; Wissinger, B.; Wendling, P. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

The impact of contrail induced cirrus clouds on regional climate is estimated for atmospheric conditions of Southern Germany that are typical for the months of July and October. This is done by the use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results using averaged climatological values of cloudiness with those of a case with modified cloudiness. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase of 1.4 K and 1.2 K for the months of July and October, respectively. (author) 14 refs.
On the climatic impact of contrails

Energy Technology Data Exchange (ETDEWEB)

Strauss, B; Meerkoetter, R; Wissinger, B; Wendling, P [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1998-12-31

The impact of contrail induced cirrus clouds on regional climate is estimated for atmospheric conditions of Southern Germany that are typical for the months of July and October. This is done by the use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results using averaged climatological values of cloudiness with those of a case with modified cloudiness. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase of 1.4 K and 1.2 K for the months of July and October, respectively. (author) 14 refs.

A modelling study of the effects of different CCN on contrail formation

Energy Technology Data Exchange (ETDEWEB)

Gleitsmann, G; Zellner, R [Essen Univ. (Gesamthochschule) (Germany). Inst. fuer Physikalische und Theoretische Chemie

1998-12-31

The formation of cloud condensation nuclei (CCN) in the jet regime of a B747 airliner at cruise has been investigated by modelling calculations using the BOAT model. Both homogeneous condensation of H{sub 2}O/H{sub 2}SO{sub 4}-mixtures and heterogeneous deposition of H{sub 2}O on soot surfaces activated by H{sub 2}SO{sub 4} were taken into account. Whereas the heterogeneous condensation leads to particles with average diameters of about 1.3 {mu}m, the homogeneously condensed H{sub 2}O/H{sub 2}SO{sub 4} particles are much smaller ({<=} 7 nm) and do not contribute to visible contrail formation. Nevertheless, they contribute to the atmospheric background aerosol. Using different SO{sub 2} emission indices, it is concluded that the contrail onset is essentially independent of this quantity and depends mainly on ambient temperature and soot activation kinetics. (author) 15 refs.
A modelling study of the effects of different CCN on contrail formation

Energy Technology Data Exchange (ETDEWEB)

Gleitsmann, G.; Zellner, R. [Essen Univ. (Gesamthochschule) (Germany). Inst. fuer Physikalische und Theoretische Chemie

1997-12-31

The formation of cloud condensation nuclei (CCN) in the jet regime of a B747 airliner at cruise has been investigated by modelling calculations using the BOAT model. Both homogeneous condensation of H{sub 2}O/H{sub 2}SO{sub 4}-mixtures and heterogeneous deposition of H{sub 2}O on soot surfaces activated by H{sub 2}SO{sub 4} were taken into account. Whereas the heterogeneous condensation leads to particles with average diameters of about 1.3 {mu}m, the homogeneously condensed H{sub 2}O/H{sub 2}SO{sub 4} particles are much smaller ({<=} 7 nm) and do not contribute to visible contrail formation. Nevertheless, they contribute to the atmospheric background aerosol. Using different SO{sub 2} emission indices, it is concluded that the contrail onset is essentially independent of this quantity and depends mainly on ambient temperature and soot activation kinetics. (author) 15 refs.
Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

Directory of Open Access Journals (Sweden)

H.-W. Wong

2013-10-01

Full Text Available Contrails and contrail-induced cirrus clouds are identified as the most uncertain components in determining aviation impacts on global climate change. Parameters affecting contrail ice particle formation immediately after the engine exit plane (< 5 s in plume age may be critical to ice particle properties used in large-scale models predicting contrail radiative forcing. Despite this, detailed understanding of these parametric effects is still limited. In this paper, we present results from recent laboratory and modeling studies conducted to investigate the effects of water and soot emissions and ambient conditions on near-field formation of contrail ice particles and ice particle properties. The Particle Aerosol Laboratory (PAL at the NASA Glenn Research Center and the Aerodyne microphysical parcel model for contrail ice particle formation were employed. Our studies show that exhaust water concentration has a significant impact on contrail ice particle formation and properties. When soot particles were introduced, ice particle formation was observed only when exhaust water concentration was above a critical level. When no soot or sulfuric acid was introduced, no ice particle formation was observed, suggesting that ice particle formation from homogeneous nucleation followed by homogeneous freezing of liquid water was unfavorable. Soot particles were found to compete for water vapor condensation, and higher soot concentrations emitted into the chamber resulted in smaller ice particles being formed. Chamber conditions corresponding to higher cruising altitudes were found to favor ice particle formation. The microphysical model captures trends of particle extinction measurements well, but discrepancies between the model and the optical particle counter measurements exist as the model predicts narrower ice particle size distributions and ice particle sizes nearly a factor of two larger than measured. These discrepancies are likely due to particle
Alternative-Fuel Effects on Contrails & Cruise Emissions (ACCESS-2) Flight Experiment

Science.gov (United States)

Anderson, Bruce E.

2015-01-01

Although the emission performance of gas-turbine engines burning renewable aviation fuels have been thoroughly documented in recent ground-based studies, there is still great uncertainty regarding how the fuels effect aircraft exhaust composition and contrail formation at cruise altitudes. To fill this information gap, the NASA Aeronautics Research Mission Directorate sponsored the ACCESS flight series to make detailed measurements of trace gases, aerosols and ice particles in the near-field behind the NASA DC-8 aircraft as it burned either standard petroleum-based fuel of varying sulfur content or a 50:50 blend of standard fuel and a hydro-treated esters and fatty acid (HEFA) jet fuel produced from camelina plant oil. ACCESS 1, conducted in spring 2013 near Palmdale CA, focused on refining flight plans and sampling techniques and used the instrumented NASA Langley HU-25 aircraft to document DC-8 emissions and contrails on five separate flights of approx.2 hour duration. ACCESS 2, conducted from Palmdale in May 2014, engaged partners from the Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) and National Research Council-Canada to provide additional scientific expertise and sampling aircraft (Falcon 20 and CT-133, respectively) with more extensive trace gas, particle, or air motion measurement capability. Eight, muliti-aircraft research flights of 2 to 4 hour duration were conducted to document the emissions and contrail properties of the DC-8 as it 1) burned low sulfur Jet A, high sulfur Jet A or low sulfur Jet A/HEFA blend, 2) flew at altitudes between 6 and 11 km, and 3) operated its engines at three different fuel flow rates. This presentation further describes the ACCESS flight experiments, examines fuel type and thrust setting impacts on engine emissions, and compares cruise-altitude observations with similar data acquired in ground tests.
Kinetics of contrail particles formation and heterogeneous reactions on such particles

Energy Technology Data Exchange (ETDEWEB)

Kogan, M.N.; Butkovsky, A.V.; Erofeev, A.I.; Freedlender, O.G.; Makashev, N.K. [Central Aerohydrodynamic Inst., Zhukovsky (Russian Federation)

1997-12-31

The research of impact of aircraft emissions upon the atmosphere is very complex and difficult problem. More than two decades of intensive investigations of the problem of ozone decay do not permit to make definite conclusions. Many important problems still remain unsolved in the aircraft/atmosphere interaction: engine, nozzle, jet, jet/vortex system interaction, vortex breakdown, contrail formation, meso-scale and global processes, their effects on climate. The particles formation and heterogeneous reactions play an important role in some of these processes. These problems are discussed. (author) 11 refs.
Kinetics of contrail particles formation and heterogeneous reactions on such particles

Energy Technology Data Exchange (ETDEWEB)

Kogan, M N; Butkovsky, A V; Erofeev, A I; Freedlender, O G; Makashev, N K [Central Aerohydrodynamic Inst., Zhukovsky (Russian Federation)

1998-12-31

The research of impact of aircraft emissions upon the atmosphere is very complex and difficult problem. More than two decades of intensive investigations of the problem of ozone decay do not permit to make definite conclusions. Many important problems still remain unsolved in the aircraft/atmosphere interaction: engine, nozzle, jet, jet/vortex system interaction, vortex breakdown, contrail formation, meso-scale and global processes, their effects on climate. The particles formation and heterogeneous reactions play an important role in some of these processes. These problems are discussed. (author) 11 refs.
Probing Aircraft Flight Test Hazard Mitigation for the Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS) Research Team

Science.gov (United States)

Kelly, Michael J.

2013-01-01

The Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS) Project Integration Manager requested in July 2012 that the NASA Engineering and Safety Center (NESC) form a team to independently assess aircraft structural failure hazards associated with the ACCESS experiment and to identify potential flight test hazard mitigations to ensure flight safety. The ACCESS Project Integration Manager subsequently requested that the assessment scope be focused predominantly on structural failure risks to the aircraft empennage raft empennage.
Persistent current analysis of superconducting coils in a linear synchronous motor for maglev passenger transport system. Fujoshiki tetsudoyo linear doki motor ni okeru teijisoku mode chodendo coil denryu no kaiseki

Energy Technology Data Exchange (ETDEWEB)

Azusawa, T [Toshiba Corp., Tokyo (Japan)

1994-05-20

The simple analysis method of persistent current induced in on-board superconducting coils was proposed for the vehicle of a superconducting magnetically-suspended train which is running in the magnetic field generated by armature coil current of a linear synchronous motor installed along a guideway, and the performance of the method is discussed through calculation based on typical models. As fluctuation of persistent current due to running was calculated with various parameter values under a normal running condition, fluctuation of persistent current induced was less then 1% of an initial magnetomotive force, having no adverse effect on the stability and reliability of superconducting magnets. Electromagnetic forces under a normal running condition could be predicted accurately enough by relatively easy-to-calculate constant current mode analysis. Double-layered armature coils were preferred to single-layered ones to enhance the stability of superconducting magnets by reducing fluctuation of persistent current. 10 refs., 8 figs., 1 tab.
Probing Aircraft Flight Test Hazard Mitigation for the Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) Research Team . Volume 2; Appendices

Science.gov (United States)

Kelly, Michael J.

2013-01-01

The Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) Project Integration Manager requested in July 2012 that the NASA Engineering and Safety Center (NESC) form a team to independently assess aircraft structural failure hazards associated with the ACCESS experiment and to identify potential flight test hazard mitigations to ensure flight safety. The ACCESS Project Integration Manager subsequently requested that the assessment scope be focused predominantly on structural failure risks to the aircraft empennage (horizontal and vertical tail). This report contains the Appendices to Volume I.
In-situ observations of interstitial aerosol particles and cloud residues found in contrails

Energy Technology Data Exchange (ETDEWEB)

Stroem, J. [Stockholm Univ. (Sweden). Dept. of Meteorology

1997-12-31

In spring 1994 a series of flights were conducted in cirrus clouds and contrails over southern Germany. One of the aims of this campaign was to study the phase partitioning of aerosols and water in these clouds. To achieve this separation of particles two complementary sampling probes were mounted on the research aircraft Falcon. These are the Counterflow Virtual Impactor (CVI) or super-micrometer inlet, and the interstitial inlet or submicrometer inlet. The CVI is a device that inertially separates cloud elements larger than a certain aerodynamic size from the surrounding atmosphere into a warm, dry and particle free air. Assuming that each cloud element leaves behind only one residue particle, these measurements yield an equivalent number concentration for cloud particles having an aerodynamic diameter larger than the lower cut size of the CVI. The size distribution of the sampled aerosol and residual particles between 0.1 to 3.5 {mu}m diameter was measured by a PMS PCASP (Passive Cavity Aerosol Spectrometer) working alternatively on both inlets. The gas-phase water vapor content was measured by a cryogenic frost point mirror. (R.P.) 4 refs.
In-situ observations of interstitial aerosol particles and cloud residues found in contrails

Energy Technology Data Exchange (ETDEWEB)

Stroem, J [Stockholm Univ. (Sweden). Dept. of Meteorology

1998-12-31

In spring 1994 a series of flights were conducted in cirrus clouds and contrails over southern Germany. One of the aims of this campaign was to study the phase partitioning of aerosols and water in these clouds. To achieve this separation of particles two complementary sampling probes were mounted on the research aircraft Falcon. These are the Counterflow Virtual Impactor (CVI) or super-micrometer inlet, and the interstitial inlet or submicrometer inlet. The CVI is a device that inertially separates cloud elements larger than a certain aerodynamic size from the surrounding atmosphere into a warm, dry and particle free air. Assuming that each cloud element leaves behind only one residue particle, these measurements yield an equivalent number concentration for cloud particles having an aerodynamic diameter larger than the lower cut size of the CVI. The size distribution of the sampled aerosol and residual particles between 0.1 to 3.5 {mu}m diameter was measured by a PMS PCASP (Passive Cavity Aerosol Spectrometer) working alternatively on both inlets. The gas-phase water vapor content was measured by a cryogenic frost point mirror. (R.P.) 4 refs.
Variation of linear and circular polarization persistence for changing field of view and collection area in a forward scattering environment

Science.gov (United States)

van der Laan, John D.; Wright, Jeremy B.; Scrymgeour, David A.; Kemme, Shanalyn A.; Dereniak, Eustace L.

2016-05-01

We present experimental and simulation results for a laboratory-based forward-scattering environment, where 1 μm diameter polystyrene spheres are suspended in water to model the optical scattering properties of fog. Circular polarization maintains its degree of polarization better than linear polarization as the optical thickness of the scattering environment increases. Both simulation and experiment quantify circular polarization's superior persistence, compared to that of linear polarization, and show that it is much less affected by variations in the field of view and collection area of the optical system. Our experimental environment's lateral extent was physically finite, causing a significant difference between measured and simulated degree of polarization values for incident linearly polarized light, but not for circularly polarized light. Through simulation we demonstrate that circular polarization is less susceptible to the finite environmental extent as well as the collection optic's limiting configuration.
Modelling asymmetric persistence over the business cycle

NARCIS (Netherlands)

Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)

1998-01-01

textabstractWe address the issue of time varying persistence of shocks to macroeconomic time series variables by proposing a new and parsimonious time series model. Our model assumes that this time varying persistence depends on a linear combination of lagged explanatory variables, where this
Integration of Linear Dynamic Emission and Climate Models with Air Traffic Simulations

Science.gov (United States)

Sridhar, Banavar; Ng, Hok K.; Chen, Neil Y.

2012-01-01

Future air traffic management systems are required to balance the conflicting objectives of maximizing safety and efficiency of traffic flows while minimizing the climate impact of aviation emissions and contrails. Integrating emission and climate models together with air traffic simulations improve the understanding of the complex interaction between the physical climate system, carbon and other greenhouse gas emissions and aviation activity. This paper integrates a national-level air traffic simulation and optimization capability with simple climate models and carbon cycle models, and climate metrics to assess the impact of aviation on climate. The capability can be used to make trade-offs between extra fuel cost and reduction in global surface temperature change. The parameters in the simulation can be used to evaluate the effect of various uncertainties in emission models and contrails and the impact of different decision horizons. Alternatively, the optimization results from the simulation can be used as inputs to other tools that monetize global climate impacts like the FAA s Aviation Environmental Portfolio Management Tool for Impacts.
Motor properties from persistence: a linear molecular walker lacking spatial and temporal asymmetry

International Nuclear Information System (INIS)

Zuckermann, Martin J; Forde, Nancy R; Angstmann, Christopher N; Schmitt, Regina; Linke, Heiner; Blab, Gerhard A; Bromley, Elizabeth HC; Curmi, Paul MG

2015-01-01

The stepping direction of linear molecular motors is usually defined by a spatial asymmetry of the motor, its track, or both. Here we present a model for a molecular walker that undergoes biased directional motion along a symmetric track in the presence of a temporally symmetric chemical cycle. Instead of using asymmetry, directionality is achieved by persistence. At small load force the walker can take on average thousands of steps in a given direction until it stochastically reverses direction. We discuss a specific experimental implementation of a synthetic motor based on this design and find, using Langevin and Monte Carlo simulations, that a realistic walker can work against load forces on the order of picoNewtons with an efficiency of ∼18%, comparable to that of kinesin. In principle, the walker can be turned into a permanent motor by externally monitoring the walker’s momentary direction of motion, and using feedback to adjust the direction of a load force. We calculate the thermodynamic cost of using feedback to enhance motor performance in terms of the Shannon entropy, and find that it reduces the efficiency of a realistic motor only marginally. We discuss the implications for natural protein motor performance in the context of the strong performance of this design based only on a thermal ratchet. (paper)
Ratio-based estimators for a change point in persistence.

Science.gov (United States)

Halunga, Andreea G; Osborn, Denise R

2012-11-01

We study estimation of the date of change in persistence, from [Formula: see text] to [Formula: see text] or vice versa. Contrary to statements in the original papers, our analytical results establish that the ratio-based break point estimators of Kim [Kim, J.Y., 2000. Detection of change in persistence of a linear time series. Journal of Econometrics 95, 97-116], Kim et al. [Kim, J.Y., Belaire-Franch, J., Badillo Amador, R., 2002. Corringendum to "Detection of change in persistence of a linear time series". Journal of Econometrics 109, 389-392] and Busetti and Taylor [Busetti, F., Taylor, A.M.R., 2004. Tests of stationarity against a change in persistence. Journal of Econometrics 123, 33-66] are inconsistent when a mean (or other deterministic component) is estimated for the process. In such cases, the estimators converge to random variables with upper bound given by the true break date when persistence changes from [Formula: see text] to [Formula: see text]. A Monte Carlo study confirms the large sample downward bias and also finds substantial biases in moderate sized samples, partly due to properties at the end points of the search interval.
Testing hypotheses in an I(2) model with piecewise linear trends. An analysis of the persistent long swings in the Dmk/$ rate

DEFF Research Database (Denmark)

Johansen, Søren; Juselius, Katarina; Frydman, Roman

2010-01-01

This paper discusses the I(2) model with breaks in the deterministic component and illustrates with an analysis of German and US prices, exchange rates, and interest rates in 1975--1999. It provides new results on the likelihood ratio test of overidentifying restrictions on the cointegrating...... relations when they contain piecewise linear trends. One important aim of the paper is to demonstrate that a structured I(2) analysis is useful for a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates....
Model-Checking of Linear-Time Properties in Multi-Valued Systems

OpenAIRE

Li, Yongming; Droste, Manfred; Lei, Lihui

2012-01-01

In this paper, we study model-checking of linear-time properties in multi-valued systems. Safety property, invariant property, liveness property, persistence and dual-persistence properties in multi-valued logic systems are introduced. Some algorithms related to the above multi-valued linear-time properties are discussed. The verification of multi-valued regular safety properties and multi-valued $\\omega$-regular properties using lattice-valued automata are thoroughly studied. Since the law o...
Global estimation of long-term persistence in annual river runoff

Science.gov (United States)

Markonis, Y.; Moustakis, Y.; Nasika, C.; Sychova, P.; Dimitriadis, P.; Hanel, M.; Máca, P.; Papalexiou, S. M.

2018-03-01

Long-term persistence (LTP) of annual river runoff is a topic of ongoing hydrological research, due to its implications to water resources management. Here, we estimate its strength, measured by the Hurst coefficient H, in 696 annual, globally distributed, streamflow records with at least 80 years of data. We use three estimation methods (maximum likelihood estimator, Whittle estimator and least squares variance) resulting in similar mean values of H close to 0.65. Subsequently, we explore potential factors influencing H by two linear (Spearman's rank correlation, multiple linear regression) and two non-linear (self-organizing maps, random forests) techniques. Catchment area is found to be crucial for medium to larger watersheds, while climatic controls, such as aridity index, have higher impact to smaller ones. Our findings indicate that long-term persistence is weaker than found in other studies, suggesting that enhanced LTP is encountered in large-catchment rivers, were the effect of spatial aggregation is more intense. However, we also show that the estimated values of H can be reproduced by a short-term persistence stochastic model such as an auto-regressive AR(1) process. A direct consequence is that some of the most common methods for the estimation of H coefficient, might not be suitable for discriminating short- and long-term persistence even in long observational records.
Persistent spin helices in 2D electron systems

Science.gov (United States)

Kozulin, A. S.; Malyshev, A. I.; Konakov, A. A.

2017-03-01

We present a theoretical investigation of persistent spin helices in two-dimensional electron systems with spin-orbit coupling. For this purpose, we consider a single-particle effective mass Hamiltonian with a generalized linear-in- k spin-orbit coupling term corresponding to a quantum well grown in an arbitrary crystallographic direction, and derive the general condition for the formation of the persistent spin helix. This condition applied for the Hamiltonians describing quantum wells with different growth directions indicates the possibility of existence of the persistent spin helix in a wide class of 2D systems apart from the [001] model with equal Rashba and Dresselhaus spin-orbit coupling strengths and the [110] Dresselhaus model.

Persistence-Driven Durotaxis: Generic, Directed Motility in Rigidity Gradients

Science.gov (United States)

Novikova, Elizaveta A.; Raab, Matthew; Discher, Dennis E.; Storm, Cornelis

2017-02-01

Cells move differently on substrates with different rigidities: the persistence time of their motion is higher on stiffer substrates. We show that this behavior—in and of itself—results in a net flux of cells directed up a soft-to-stiff gradient. Using simple random walk models with varying persistence and stochastic simulations, we characterize the propensity to move in terms of the durotactic index also measured in experiments. A one-dimensional model captures the essential features and highlights the competition between diffusive spreading and linear, wavelike propagation. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects.
Persistent currents in three-dimensional shell-doped nanorings

International Nuclear Information System (INIS)

Ning, Xu; Jian-Wen, Ding; Hong-Bo, Chen; Ming-Ming, Ma

2009-01-01

The persistent current in three-dimensional (P × N 2 ) nanorings as a function of the unit cell number (P), the channel number (M = N 2 ), surface disorder (ξ), and temperature (T) is theoretically investigated in terms of rotational symmetry. On the whole, the typical current increases linearly with √M but decreases exponentially with P, while wide fluctuations exist therein. In the presence of surface disorder, the persistent current decreases with ξ in the regime of weak disorder but increases in the regime of strong disorder. In addition, it is found that the persistent current in perfect rings decreases exponentially with temperature even at T * , while in most disorder rings, the typical current decreases slightly with temperature at T *
Linear interictal pain in Epicrania Fugax.

Science.gov (United States)

Pareja, Juan A; Bandrés, Pablo

2015-01-01

Epicrania Fugax is a paroxysmal, short-lasting, head pain moving across one hemicranium, describing a linear or zag trajectory, starting and ending in territories of different nerves. Between attacks, patients are usually free of symptoms. We describe an Epicrania Fugax patient complaining of interictal pain. The interictal pain was line-shaped and extended across the usual starting and ending points of the typical Epicrania Fugax paroxysms. Although rarely encountered, persistent linear pain may be a feature of Epicrania Fugax.
Climates of suspicion: ‘chemtrail’ conspiracy narratives and the international politics of geoengineering

OpenAIRE

Cairns, Rose

2016-01-01

Concurrent with growing academic and policy interest in ‘geoengineering’ the global climate in response to climate change, a more marginal discourse postulating the existence of a climate control conspiracy is also proliferating on the Internet. Here, the term ‘chemtrails’ is used interchangeably with the term geoengineering to describe the belief that the persistent contrails left by aeroplanes provide evidence that a secret programme of large scale weather and climate modification is on-goi...
Persistent ectopic pregnancy after linear salpingotomy: a non-predictable complication to conservative surgery for tubal gestation

DEFF Research Database (Denmark)

Lund, Claus Otto; Nilas, Lisbeth; Bangsgaard, Nannie

2002-01-01

BACKGROUND: The drawback of conservative surgery for ectopic pregnancy (EP) is the risk of persistent trophoblast. The purpose was to characterize patients who develop persistent ectopic pregnancy (PEP) after salpingotomy for EP and to assess prognostic factors. METHODS: The medical records of 417...... patients treated by salpingotomy for EP were reviewed. Forty-eight (11.5%) patients were diagnosed with persistent EP. The data were analyzed using the Mann-Whitney U-test, Fischer's exact test or the chi2-test. RESULTS: Of 417 women, 48 (11,5%) were treated for PEP by either repeat surgery (n = 25......) or methotrexate (n = 23). Oral methotrexate failed in 4/19 cases while intramuscular (i.m.) methotrexate was successful in 4/4 cases. Women treated for PEP had a higher preoperative and a slower postoperative decline of serum human chorionic gonadotropin (hCG). Both the preoperative and the early postoperative h...
Inhibition linearizes firing rate responses in human motor units: implications for the role of persistent inward currents.

Science.gov (United States)

Revill, Ann L; Fuglevand, Andrew J

2017-01-01

Motor neurons are the output neurons of the central nervous system and are responsible for controlling muscle contraction. When initially activated during voluntary contraction, firing rates of motor neurons increase steeply but then level out at modest rates. Activation of an intrinsic source of excitatory current at recruitment onset may underlie the initial steep increase in firing rate in motor neurons. We attempted to disable this intrinsic excitatory current by artificially activating an inhibitory reflex. When motor neuron activity was recorded while the inhibitory reflex was engaged, firing rates no longer increased steeply, suggesting that the intrinsic excitatory current was probably responsible for the initial sharp rise in motor neuron firing rate. During graded isometric contractions, motor unit (MU) firing rates increase steeply upon recruitment but then level off at modest rates even though muscle force continues to increase. The mechanisms underlying such firing behaviour are not known although activation of persistent inward currents (PICs) might be involved. PICs are intrinsic, voltage-dependent currents that activate strongly when motor neurons (MNs) are first recruited. Such activation might cause a sharp escalation in depolarizing current and underlie the steep initial rise in MU firing rate. Because PICs can be disabled with synaptic inhibition, we hypothesized that artificial activation of an inhibitory pathway might curb this initial steep rise in firing rate. To test this, human subjects performed slow triangular ramp contractions of the ankle dorsiflexors in the absence and presence of tonic synaptic inhibition delivered to tibialis anterior (TA) MNs by sural nerve stimulation. Firing rate profiles (expressed as a function of contraction force) of TA MUs recorded during these tasks were compared for control and stimulation conditions. Under control conditions, during the ascending phase of the triangular contractions, 93% of the firing
Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review.

Science.gov (United States)

Rittman, Martyn; Gilroy, Emma; Koohya, Hashem; Rodger, Alison; Richards, Adair

2009-01-01

Persistence length is the foremost measure of DNA flexibility. Its origins lie in polymer theory which was adapted for DNA following the determination of BDNA structure in 1953. There is no single definition of persistence length used, and the links between published definitions are based on assumptions which may, or may not be, clearly stated. DNA flexibility is affected by local ionic strength, solvent environment, bound ligands and intrinsic sequence-dependent flexibility. This article is a review of persistence length providing a mathematical treatment of the relationships between four definitions of persistence length, including: correlation, Kuhn length, bending, and curvature. Persistence length has been measured using various microscopy, force extension and solution methods such as linear dichroism and transient electric birefringence. For each experimental method a model of DNA is required to interpret the data. The importance of understanding the underlying models, along with the assumptions required by each definition to determine a value of persistence length, is highlighted for linear dichroism data, where it transpires that no model is currently available for long DNA or medium to high shear rate experiments.
On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

Science.gov (United States)

Klimas, Alexander J.; Fitzenreiter, Richard J.

1988-01-01

This paper presents further evidence for the persistence of bump-on-tail unstable reduced velocity distributions in the earth's electron foreshock, which contradicts the understanding of quasi-linear saturation of the bump-on-tail instability. A modified theory for the saturation of the bump-on-tail instability in the earth's foreshock is proposed to explain the mechanism of this persistence, and the predictions are compared to the results of a numerical simulation of the electron plasma in the foreshock. The results support the thesis that quasi-linear saturation of the bump-on-tail instability is modified in the foreshock, due to the driven nature of the region, so that at saturation the stabilized velocity distribution still appears bump-on-tail unstable to linear plasma analysis.
Linearly Refined Session Types

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Pedro Baltazar

2012-11-01

Full Text Available Session types capture precise protocol structure in concurrent programming, but do not specify properties of the exchanged values beyond their basic type. Refinement types are a form of dependent types that can address this limitation, combining types with logical formulae that may refer to program values and can constrain types using arbitrary predicates. We present a pi calculus with assume and assert operations, typed using a session discipline that incorporates refinement formulae written in a fragment of Multiplicative Linear Logic. Our original combination of session and refinement types, together with the well established benefits of linearity, allows very fine-grained specifications of communication protocols in which refinement formulae are treated as logical resources rather than persistent truths.
A characterization of persistence at short times in the WFC3/IR detector

Science.gov (United States)

Gennaro, M.; Bajaj, V.; Long, K.

2018-05-01

Persistence in the WFC3/IR detector appears to decay as a power law as a function of time elapsed since the end of a stimulus. In this report we study departures from the power law at times shorter than a few hundreds seconds after the stimulus. In order to have better short-time cadence, we use the Multiaccum (.ima) files, which trace the accumulated charge in the pixels as function of time, rather than the final pipeline products (.flt files), which instead report the electron rate estimated via a linear fit to the accumulated charge vs. time relation. We note that at short times after the stimulus, the absolute change in persistence is the strongest, thus a linear fit to the accumulated signal (the .flt values) can be a poor representation of the strongly varying persistence signal. The already observed power-law decay of the persistence signal, still holds at shorter times, with typical values of the power law index, gamma in [-0.8,-1] for stimuli that saturate the WFC3 pixels. To a good degree of approximation, a single power law is a good fit to the persistence signal decay from 100 to 5000 seconds. We also detect a tapering-off in the power-law decay at increasingly shorter times. This change in behavior is of the order of Delta Gamma 0.02 - 0.05 when comparing power-law fits performed to the persistence signal from 0 up to 250 seconds and from 0 up to 4000 seconds after the stimulus, indicating that persistence decays slightly more rapidly as time progresses. Our results may suggest that for even shorter times, not probed by our study, the WFC3 persistence signal might deviate from a single power-law model.
Rotenone persistence model for montane streams

Science.gov (United States)

Brown, Peter J.; Zale, Alexander V.

2012-01-01

The efficient and effective use of rotenone is hindered by its unknown persistence in streams. Environmental conditions degrade rotenone, but current label instructions suggest fortifying the chemical along a stream based on linear distance or travel time rather than environmental conditions. Our objective was to develop models that use measurements of environmental conditions to predict rotenone persistence in streams. Detailed measurements of ultraviolet radiation, water temperature, dissolved oxygen, total dissolved solids (TDS), conductivity, pH, oxidation–reduction potential (ORP), substrate composition, amount of organic matter, channel slope, and travel time were made along stream segments located between rotenone treatment stations and cages containing bioassay fish in six streams. The amount of fine organic matter, biofilm, sand, gravel, cobble, rubble, small boulders, slope, pH, TDS, ORP, light reaching the stream, energy dissipated, discharge, and cumulative travel time were each significantly correlated with fish death. By using logistic regression, measurements of environmental conditions were paired with the responses of bioassay fish to develop a model that predicted the persistence of rotenone toxicity in streams. This model was validated with data from two additional stream treatment reaches. Rotenone persistence was predicted by a model that used travel time, rubble, and ORP. When this model predicts a probability of less than 0.95, those who apply rotenone can expect incomplete eradication and should plan on fortifying rotenone concentrations. The significance of travel time has been previously identified and is currently used to predict rotenone persistence. However, rubble substrate, which may be associated with the degradation of rotenone by adsorption and volatilization in turbulent environments, was not previously considered.
Geometry Helps to Compare Persistence Diagrams

Energy Technology Data Exchange (ETDEWEB)

Kerber, Michael; Morozov, Dmitriy; Nigmetov, Arnur

2015-11-16

Exploiting geometric structure to improve the asymptotic complexity of discrete assignment problems is a well-studied subject. In contrast, the practical advantages of using geometry for such problems have not been explored. We implement geometric variants of the Hopcroft--Karp algorithm for bottleneck matching (based on previous work by Efrat el al.), and of the auction algorithm by Bertsekas for Wasserstein distance computation. Both implementations use k-d trees to replace a linear scan with a geometric proximity query. Our interest in this problem stems from the desire to compute distances between persistence diagrams, a problem that comes up frequently in topological data analysis. We show that our geometric matching algorithms lead to a substantial performance gain, both in running time and in memory consumption, over their purely combinatorial counterparts. Moreover, our implementation significantly outperforms the only other implementation available for comparing persistence diagrams.
Irregular persistent activity induced by synaptic excitatory feedback

Directory of Open Access Journals (Sweden)

Francesca Barbieri

2007-11-01

Full Text Available Neurophysiological experiments on monkeys have reported highly irregular persistent activity during the performance of an oculomotor delayed-response task. These experiments show that during the delay period the coefficient of variation (CV of interspike intervals (ISI of prefrontal neurons is above 1, on average, and larger than during the fixation period. In the present paper, we show that this feature can be reproduced in a network in which persistent activity is induced by excitatory feedback, provided that (i the post-spike reset is close enough to threshold , (ii synaptic efficacies are a non-linear function of the pre-synaptic firing rate. Non-linearity between presynaptic rate and effective synaptic strength is implemented by a standard short-term depression mechanism (STD. First, we consider the simplest possible network with excitatory feedback: a fully connected homogeneous network of excitatory leaky integrate-and-fire neurons, using both numerical simulations and analytical techniques. The results are then confirmed in a network with selective excitatory neurons and inhibition. In both the cases there is a large range of values of the synaptic efficacies for which the statistics of firing of single cells is similar to experimental data.
Linear Darier's disease: A case with bilateral presentation

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Anal Jyoti Bordoloi

2015-01-01

Full Text Available Darier's disease is an autosomal dominant genodermatosis characterized by a persistent eruption of hyperkeratotic greasy papules mainly over the seborrheic sites of the body, usually associated with nail abnormalities and sometimes with mucous membrane lesions. The lesions typically occur in the younger age group and are associated with pruritus. We report here an atypical case of Linear Darier's disease with bilateral presentation in a middle-aged adult that could be confused with conditions such as lichen planus, inflammatory linear verrucous epidermal nevus, and wart.
Impact of stepwise ablation on the biatrial substrate in patients with persistent atrial fibrillation and heart failure.

Science.gov (United States)

Jones, David G; Haldar, Shouvik K; Jarman, Julian W E; Johar, Sofian; Hussain, Wajid; Markides, Vias; Wong, Tom

2013-08-01

Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary vein isolation (PVI) but also additional linear lesions and ablation of complex fractionated electrograms (CFE). We examined the impact of stepwise ablation on a human model of advanced atrial substrate of persistent atrial fibrillation in heart failure. In 30 patients with persistent atrial fibrillation and left ventricular ejection fraction ≤35%, high-density CFE maps were recorded biatrially at baseline, in the left atrium (LA) after PVI and linear lesions (roof and mitral isthmus), and biatrially after LA CFE ablation. Surface area of CFE (mean cycle length ≤120 ms) remote to PVI and linear lesions, defined as CFE area, was reduced after PVI (18.3±12.03 to 10.2±7.1 cm(2); Patrial CFE area was reduced by LA ablation, from 25.9±14.1 to 12.9±11.8 cm(2) (Patrial CFE area. Reduction of CFE area at sites remote from ablation would suggest either regression of the advanced atrial substrate or that these CFE were functional phenomena. Nevertheless, in an advanced atrial fibrillation substrate, linear lesions after PVI diminished the target area for CFE ablation, and complete lesions resulted in a favorable clinical outcome.
An Offline Formulation of MPC for LPV Systems Using Linear Matrix Inequalities

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P. Bumroongsri

2014-01-01

Full Text Available An offline model predictive control (MPC algorithm for linear parameter varying (LPV systems is presented. The main contribution is to develop an offline MPC algorithm for LPV systems that can deal with both time-varying scheduling parameter and persistent disturbance. The norm-bounding technique is used to derive an offline MPC algorithm based on the parameter-dependent state feedback control law and the parameter-dependent Lyapunov functions. The online computational time is reduced by solving offline the linear matrix inequality (LMI optimization problems to find the sequences of explicit state feedback control laws. At each sampling instant, a parameter-dependent state feedback control law is computed by linear interpolation between the precomputed state feedback control laws. The algorithm is illustrated with two examples. The results show that robust stability can be ensured in the presence of both time-varying scheduling parameter and persistent disturbance.
Quantifying the degree of persistence in random amoeboid motion based on the Hurst exponent of fractional Brownian motion.

Science.gov (United States)

Makarava, Natallia; Menz, Stephan; Theves, Matthias; Huisinga, Wilhelm; Beta, Carsten; Holschneider, Matthias

2014-10-01

Amoebae explore their environment in a random way, unless external cues like, e.g., nutrients, bias their motion. Even in the absence of cues, however, experimental cell tracks show some degree of persistence. In this paper, we analyzed individual cell tracks in the framework of a linear mixed effects model, where each track is modeled by a fractional Brownian motion, i.e., a Gaussian process exhibiting a long-term correlation structure superposed on a linear trend. The degree of persistence was quantified by the Hurst exponent of fractional Brownian motion. Our analysis of experimental cell tracks of the amoeba Dictyostelium discoideum showed a persistent movement for the majority of tracks. Employing a sliding window approach, we estimated the variations of the Hurst exponent over time, which allowed us to identify points in time, where the correlation structure was distorted ("outliers"). Coarse graining of track data via down-sampling allowed us to identify the dependence of persistence on the spatial scale. While one would expect the (mode of the) Hurst exponent to be constant on different temporal scales due to the self-similarity property of fractional Brownian motion, we observed a trend towards stronger persistence for the down-sampled cell tracks indicating stronger persistence on larger time scales.
Current strategies for non-pharmacological therapy of long-standing persistent atrial fibrillation

Directory of Open Access Journals (Sweden)

Teiichi Yamane, MD, PhD

2012-06-01

Full Text Available Non-pharmacological rhythm control of atrial fibrillation (AF is becoming increasingly important in our aging society. Advancement of catheter ablation techniques in the last decade has provided a cure for AF patients, with a nearly established efficiency for paroxysmal cases. However, since ablation of persistent/chronic AF cases is still challenging, early treatment of paroxysmal AF before transformation to the persistent/chronic form is mandatory. Although there is a consensus that pulmonary vein isolation is the first-line approach for ablation of long-standing persistent AF, similar to that for paroxysmal AF, there are still wide variations in the adjunctive approach to modify the atrial substrate of persistent AF (anatomical linear ablation, electrogram-based complex fractionated atrial electrogram ablation, ganglionated plexus ablation, etc.. Since data comparing the effectiveness of these adjunctive approaches are still lacking, large-scale controlled trials evaluating the effect of catheter ablation in diverse patient populations on a long-term basis are needed to establish the appropriate approach for long-standing persistent AF. Furthermore, the development of de novo ablation methods (new energies, new targets, etc. is expected to improve ablation outcome in patients with long-standing persistent AF.
Numerical modelling of the Concorde wake during ZEBRE

Energy Technology Data Exchange (ETDEWEB)

Gierens, K. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

Numerical simulations of the Concorde contrail during the ZEBRE experiment have been performed. The main goal of the simulations is to reproduce the fast vanishing of the contrail which disappeared 20-30 s after exhaust. It is difficult to evaporate ice crystals during the jet and vortex phase of the aircraft wake, when the exhaust products are trapped in the vortex cores. The trapping also excludes spatial dispersion of the ice crystals as an explanation of the short contrail lifetime. The disappearance of the contrail within 20-30 s requires that a substantial part of the exhaust gases escapes from the region that is later on trapped in the vortex cores. (author) 10 refs.
Numerical modelling of the Concorde wake during ZEBRE

Energy Technology Data Exchange (ETDEWEB)

Gierens, K [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1998-12-31

Numerical simulations of the Concorde contrail during the ZEBRE experiment have been performed. The main goal of the simulations is to reproduce the fast vanishing of the contrail which disappeared 20-30 s after exhaust. It is difficult to evaporate ice crystals during the jet and vortex phase of the aircraft wake, when the exhaust products are trapped in the vortex cores. The trapping also excludes spatial dispersion of the ice crystals as an explanation of the short contrail lifetime. The disappearance of the contrail within 20-30 s requires that a substantial part of the exhaust gases escapes from the region that is later on trapped in the vortex cores. (author) 10 refs.

Persistence versus extinction for a class of discrete-time structured population models.

Science.gov (United States)

Jin, Wen; Smith, Hal L; Thieme, Horst R

2016-03-01

We provide sharp conditions distinguishing persistence and extinction for a class of discrete-time dynamical systems on the positive cone of an ordered Banach space generated by a map which is the sum of a positive linear contraction A and a nonlinear perturbation G that is compact and differentiable at zero in the direction of the cone. Such maps arise as year-to-year projections of population age, stage, or size-structure distributions in population biology where typically A has to do with survival and individual development and G captures the effects of reproduction. The threshold distinguishing persistence and extinction is the principal eigenvalue of (II−A)(−1)G'(0) provided by the Krein-Rutman Theorem, and persistence is described in terms of associated eigenfunctionals. Our results significantly extend earlier persistence results of the last two authors which required more restrictive conditions on G. They are illustrated by application of the results to a plant model with a seed bank.
Inflation Persistence under Semi-Fixed Exchange Rate Regimes:The European Evidence 1974-1998

NARCIS (Netherlands)

Kool, C.J.M.; Lammertsma, A.

2004-01-01

In this paper, we empirically investigate the link between exchange rate accommodation and inflation persistence in Europe. We introduce the lagged level of the real exchange rate as an appropriate indicator of exchange rate accommodation. We correspondingly estimate a non-linear autoregressive
Investigating the persistence of earnings components and pricing test of abnormal changes in cash

Directory of Open Access Journals (Sweden)

Yaser Ahmadi

2013-03-01

Full Text Available This paper investigates the persistence of earnings components and pricing test of abnormal changes in cash for selected firms listed on Tehran Stock Exchange (TSE. The proposed study gathers the necessary data from 166 firms over the period 2004-2012 from firms whose shares were actively traded on TSE market. The study uses Panel data and with the implementation of linear regression technique examines four hypotheses. The results indicate that abnormal negative changes in cash are more persistence than positive abnormal changes. In addition, both positive and negative abnormal changes are more persistence than accruals. Market also has a good perception on abnormal positive and negative changes in cash.
Novel Approach to Linear Accelerator Superconducting Magnet System

International Nuclear Information System (INIS)

Kashikhin, Vladimir

2011-01-01

Superconducting Linear Accelerators include a superconducting magnet system for particle beam transportation that provides the beam focusing and steering. This system consists of a large number of quadrupole magnets and dipole correctors mounted inside or between cryomodules with SCRF cavities. Each magnet has current leads and powered from its own power supply. The paper proposes a novel approach to magnet powering based on using superconducting persistent current switches. A group of magnets is powered from the same power supply through the common, for the group of cryomodules, electrical bus and pair of current leads. Superconducting switches direct the current to the chosen magnet and close the circuit providing the magnet operation in a persistent current mode. Two persistent current switches were fabricated and tested. In the paper also presented the results of magnetic field simulations, decay time constants analysis, and a way of improving quadrupole magnetic center stability. Such approach substantially reduces the magnet system cost and increases the reliability.
Effect of Cisplatin on the Flexibility of Linear DNA

International Nuclear Information System (INIS)

Ji Chao; Zhang Ling-Yun; Hou Xi-Miao; Dou Shuo-Xing; Wang Peng-Ye

2011-01-01

With the aid of an atomic force microscope (AFM), we study the interaction between linear DNA fragment and cisplatin. For different cisplatin concentrations, the AFM used to observe the conformation of DNA has a gradual change. The contour length, the end-to-end distance and the local bend angles of the linear DNA fragment can be accurately measured. The persistence length of DNA interacting with cisplatin is decreased with the increasing cisplatin concentration. Furthermore, it is demonstrated that the local bend angles of DNA chains are increased by the binding interaction of cisplatin. (cross-disciplinary physics and related areas of science and technology)
[Persistent diarrhea

Science.gov (United States)

Andrade, J A; Moreira, C; Fagundes Neto, U

2000-07-01

INTRODUCTION: Persistent diarrhea has high impact on infantile morbidity and mortality rates in developing countries. Several studies have shown that 3 to 20% of acute diarrheal episodes in children under 5 years of age become persistent. DEFINITION: Persistent diarrhea is defined as an episode that lasts more than 14 days. ETIOLOGY: The most important agents isolated in persistent diarrhea are: Enteropathogenic E. coli (EPEC), Salmonella, Enteroaggregative E. coli (EAEC), Klebisiella and Cryptosporidium. CLINICAL ASPECTS: In general, the clinical characteristics of patients with persistent diarrhea do not change with the pathogenic agent. Persistent diarrhea seems to represent the final result of a several insults a infant suffers that predisposes to a more severe episode of diarrhea due to a combination of host factors and high rates of enviromental contamination. Therefore, efforts should be made to promptly treat all episodes of diarrhea with apropriate follow-up. THERAPY: The aim of the treatment is to restore hydroelectrolytic deficits and to replace losses until the diarrheal ceases. It is possible in the majority of the cases, using oral rehydration therapy and erly an appropriate type of diet. PREVENTION: It is imperative that management strategies also focus on preventive aspects. The most effective diarrheal prevention strategy in young infants worldwide is promotion of exclusive breast feeding.
Virtual In-Silico Modeling Guided Catheter Ablation Predicts Effective Linear Ablation Lesion Set for Longstanding Persistent Atrial Fibrillation: Multicenter Prospective Randomized Study.

Science.gov (United States)

Shim, Jaemin; Hwang, Minki; Song, Jun-Seop; Lim, Byounghyun; Kim, Tae-Hoon; Joung, Boyoung; Kim, Sung-Hwan; Oh, Yong-Seog; Nam, Gi-Byung; On, Young Keun; Oh, Seil; Kim, Young-Hoon; Pak, Hui-Nam

2017-01-01

Objective: Radiofrequency catheter ablation for persistent atrial fibrillation (PeAF) still has a substantial recurrence rate. This study aims to investigate whether an AF ablation lesion set chosen using in-silico ablation (V-ABL) is clinically feasible and more effective than an empirically chosen ablation lesion set (Em-ABL) in patients with PeAF. Methods: We prospectively included 108 patients with antiarrhythmic drug-resistant PeAF (77.8% men, age 60.8 ± 9.9 years), and randomly assigned them to the V-ABL ( n = 53) and Em-ABL ( n = 55) groups. Five different in-silico ablation lesion sets [1 pulmonary vein isolation (PVI), 3 linear ablations, and 1 electrogram-guided ablation] were compared using heart-CT integrated AF modeling. We evaluated the feasibility, safety, and efficacy of V-ABL compared with that of Em-ABL. Results: The pre-procedural computing time for five different ablation strategies was 166 ± 11 min. In the Em-ABL group, the earliest terminating blinded in-silico lesion set matched with the Em-ABL lesion set in 21.8%. V-ABL was not inferior to Em-ABL in terms of procedure time ( p = 0.403), ablation time ( p = 0.510), and major complication rate ( p = 0.900). During 12.6 ± 3.8 months of follow-up, the clinical recurrence rate was 14.0% in the V-ABL group and 18.9% in the Em-ABL group ( p = 0.538). In Em-ABL group, clinical recurrence rate was significantly lower after PVI+posterior box+anterior linear ablation, which showed the most frequent termination during in-silico ablation (log-rank p = 0.027). Conclusions: V-ABL was feasible in clinical practice, not inferior to Em-ABL, and predicts the most effective ablation lesion set in patients who underwent PeAF ablation.
The psychological costs and benefits of being highly persistent: personality profiles distinguish mood disorders from anxiety disorders.

Science.gov (United States)

Cloninger, C Robert; Zohar, Ada H; Hirschmann, Schmuel; Dahan, Dana

2012-02-01

The personality trait of Persistence is highly valued by conscientious overachievers, but it has both psychological costs and benefits. The interactions among multiple personality factors influencing the development of mood and anxiety disorders have been confounded in prior clinical samples, but can be disentangled in terms of their underlying brain circuitry and influence on perception of emotional stimuli. 285 individuals who represented the full range of personality variation in a large sample of adult volunteers from the general community of Israel were selected for follow-up by psychiatric interviews, cognitive testing, and medical examinations. The Temperament and Character Inventory (TCI) measured profiles of traits that distinguished individuals with diagnoses of mood and/or anxiety disorders using linear discriminant analysis and non-linear profile analysis. High Harm Avoidance and low Self-directedness strongly distinguished people with mood and/or anxiety disorders from those with neither. High Persistence distinguished people with only anxiety disorders from those with mood disorders. High Persistence was associated with greater health and happiness overall, but also led to more negative emotions than in people with low Persistence unless they were both unusually tolerant of frustration (i.e., low in Harm Avoidance) and self-accepting of personal limitations (i.e. high in Self-directedness). Subjects were volunteers over 40 years of age at assessment. People who are highly persistent (i.e., persevering, ambitious, perfectionistic) are more likely to have anxiety disorders than mood disorders, even when they have other traits increasing risk for both (i.e., high Harm Avoidance and low Self-directedness). High Persistence increases both positive and negative emotions in most people. However, high Persistence reduces negative emotions and increases positive emotions if a person is easy-going (i.e., "happy-go-lucky" when low in both Harm Avoidance and Self
Systematic study of doping dependence on linear magnetoresistance in p-PbTe

International Nuclear Information System (INIS)

Schneider, J. M.; Chitta, V. A.; Oliveira, N. F.; Peres, M. L.; Castro, S. de; Soares, D. A. W.; Wiedmann, S.; Zeitler, U.; Abramof, E.; Rappl, P. H. O.; Mengui, U. A.

2014-01-01

We report on a large linear magnetoresistance effect observed in doped p-PbTe films. While undoped p-PbTe reveals a sublinear magnetoresistance, p-PbTe films doped with BaF 2 exhibit a transition to a nearly perfect linear magnetoresistance behaviour that is persistent up to 30 T. The linear magnetoresistance slope ΔR/ΔB is to a good approximation, independent of temperature. This is in agreement with the theory of Quantum Linear Magnetoresistance. We also performed magnetoresistance simulations using a classical model of linear magnetoresistance. We found that this model fails to explain the experimental data. A systematic study of the doping dependence reveals that the linear magnetoresistance response has a maximum for small BaF 2 doping levels and diminishes rapidly for increasing doping levels. Exploiting the huge impact of doping on the linear magnetoresistance signal could lead to new classes of devices with giant magnetoresistance behavior.
Investigating the correlation between paediatric stride interval persistence and gross energy expenditure

Directory of Open Access Journals (Sweden)

Sejdić Ervin

2010-02-01

Full Text Available Abstract Background Stride interval persistence, a term used to describe the correlation structure of stride interval time series, is thought to provide insight into neuromotor control, though its exact clinical meaning has not yet been realized. Since human locomotion is shaped by energy efficient movements, it has been hypothesized that stride interval dynamics and energy expenditure may be inherently tied, both having demonstrated similar sensitivities to age, disease, and pace-constrained walking. Findings This study tested for correlations between stride interval persistence and measures of energy expenditure including mass-specific gross oxygen consumption per minute (, mass-specific gross oxygen cost per meter (VO2 and heart rate (HR. Metabolic and stride interval data were collected from 30 asymptomatic children who completed one 10-minute walking trial under each of the following conditions: (i overground walking, (ii hands-free treadmill walking, and (iii handrail-supported treadmill walking. Stride interval persistence was not significantly correlated with (p > 0.32, VO2 (p > 0.18 or HR (p > 0.56. Conclusions No simple linear dependence exists between stride interval persistence and measures of gross energy expenditure in asymptomatic children when walking overground and on a treadmill.
Long-term persistence of oral human papillomavirus type 16: the HPV Infection in Men (HIM) study.

Science.gov (United States)

Pierce Campbell, Christine M; Kreimer, Aimée R; Lin, Hui-Yi; Fulp, William; O'Keefe, Michael T; Ingles, Donna J; Abrahamsen, Martha; Villa, Luisa L; Lazcano-Ponce, Eduardo; Giuliano, Anna R

2015-03-01

Persistent infection with oral HPV16 is believed to drive the development of most oropharyngeal cancers. However, patterns of oral HPV16 persistence remain understudied, particularly among HIV-negative individuals. Oral HPV16 persistence was evaluated among 1,626 participants of the HPV Infection in Men (HIM) Study. Twenty-three oral HPV16-positive men who provided an oral gargle sample on ≥2 study visits were included in the analysis. Archived oral samples from all follow-up visits were tested for HPV16 using Linear Array and INNO-LiPA detection methods. Persistence was evaluated using consecutive HPV16-positive visits held approximately 6 months apart and using the Kaplan-Meier method. Oral HPV16-positive men were aged 18 to 64 years [median, 36 years; interquartile range (IQR), 25-42] and were followed for a median of 44.4 months (IQR, 29.9-49.5). Of 13 incident infections, 4 (30.8%) persisted ≥12 months, 1 (10.0%) persisted ≥24 months, and none persisted ≥36 months [median infection duration, 7.3 months; 95% confidence interval (CI), 6.4-NA)]. Of 10 prevalent infections, 9 (90.0%) persisted ≥12 months, 8 (80.0%) persisted ≥24 months, 4 (57.1%) persisted ≥36 months, and 2 (40.0%) persisted ≥48 months (median infection duration, NA). Twelve-month persistence of incident infections increased significantly with age (Ptrend = 0.028). Prevalent oral HPV16 infections in men persisted longer than newly acquired infections, and persistence appeared to increase with age. These findings may explain the high prevalence of oral HPV observed at older ages. Understanding oral HPV16 persistence will aid in the identification of men at high-risk of developing HPV-related oropharyngeal cancer. ©2015 American Association for Cancer Research.
Induction and Persistence of Large γH2AX Foci by High Linear Energy Transfer Radiation in DNA-Dependent protein kinase–Deficient Cells

Energy Technology Data Exchange (ETDEWEB)

Bracalente, Candelaria; Ibañez, Irene L. [Departamento de Micro y Nanotecnología, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Molinari, Beatriz [Departamento de Radiobiología, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Palmieri, Mónica [Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Kreiner, Andrés [Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Buenos Aires (Argentina); Valda, Alejandro [Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Buenos Aires (Argentina); and others

2013-11-15

Purpose: To evaluate the cell response to DNA double-strand breaks induced by low and high linear energy transfer (LET) radiations when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of the nonhomologous end-joining repair pathway, lacks kinase activity. Methods and Materials: CHO10B2, a Chinese hamster ovary cell line, and its derived radiosensitive mutant cell line, irs-20, lacking DNA-PKcs activity, were evaluated after 0 to 3 Gy of γ-rays, plateau and Bragg peak protons, and lithium beams by clonogenic assay, and as a measurement of double-strand breaks, phosphorylated H2AX (γH2AX) foci number and size were quantified by immunocytofluorescence. Results: Irs-20 exhibited greater radiosensitivity and a higher amount of γH2AX foci than CHO10B2 at 6 hours after irradiation for all types of radiations. Remarkably, CHO10B2 and irs-20 maintained their difference in radiosensitivity after high-LET radiation. Six hours after low-LET radiations, irs-20 did not reach basal levels of γH2AX at high doses, whereas CHO10B2 recovered basal levels for all doses. After high-LET radiation, only CHO10B2 exhibited a reduction in γH2AX foci, but it never reached basal levels. Persistent foci in irs-20 confirmed a repair deficiency. Interestingly, after 30 minutes of high-LET radiation both cell lines exhibited large foci (size >0.9 μm{sup 2}) related to the damage nature, whereas at 6 hours irs-20 showed a higher amount of large foci than CHO10B2, with a 7-fold increase at 3 Gy, that could also be associated to radiosensitivity. Conclusions: We demonstrated, for the first time, an association between deficient DNA-PKcs activity and not only high levels of H2AX phosphorylation but also persistence and size increase of γH2AX foci after high-LET irradiation.
Induction and Persistence of Large γH2AX Foci by High Linear Energy Transfer Radiation in DNA-Dependent protein kinase–Deficient Cells

International Nuclear Information System (INIS)

Bracalente, Candelaria; Ibañez, Irene L.; Molinari, Beatriz; Palmieri, Mónica; Kreiner, Andrés; Valda, Alejandro

2013-01-01

Purpose: To evaluate the cell response to DNA double-strand breaks induced by low and high linear energy transfer (LET) radiations when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of the nonhomologous end-joining repair pathway, lacks kinase activity. Methods and Materials: CHO10B2, a Chinese hamster ovary cell line, and its derived radiosensitive mutant cell line, irs-20, lacking DNA-PKcs activity, were evaluated after 0 to 3 Gy of γ-rays, plateau and Bragg peak protons, and lithium beams by clonogenic assay, and as a measurement of double-strand breaks, phosphorylated H2AX (γH2AX) foci number and size were quantified by immunocytofluorescence. Results: Irs-20 exhibited greater radiosensitivity and a higher amount of γH2AX foci than CHO10B2 at 6 hours after irradiation for all types of radiations. Remarkably, CHO10B2 and irs-20 maintained their difference in radiosensitivity after high-LET radiation. Six hours after low-LET radiations, irs-20 did not reach basal levels of γH2AX at high doses, whereas CHO10B2 recovered basal levels for all doses. After high-LET radiation, only CHO10B2 exhibited a reduction in γH2AX foci, but it never reached basal levels. Persistent foci in irs-20 confirmed a repair deficiency. Interestingly, after 30 minutes of high-LET radiation both cell lines exhibited large foci (size >0.9 μm 2 ) related to the damage nature, whereas at 6 hours irs-20 showed a higher amount of large foci than CHO10B2, with a 7-fold increase at 3 Gy, that could also be associated to radiosensitivity. Conclusions: We demonstrated, for the first time, an association between deficient DNA-PKcs activity and not only high levels of H2AX phosphorylation but also persistence and size increase of γH2AX foci after high-LET irradiation
On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

International Nuclear Information System (INIS)

Klimas, A.J.; Fitzenreiter, R.J.

1988-01-01

Further evidence for the persistence of bump-on-tail unstable reduced velocity distribution in the Earth's electron foreshock is presented. This persistence contradicts our understanding of quasi-linear saturation of the bump-on-tail instability; the distributions should be stabilized through velocity space diffusion too quickly to allow an observation of their unstable form. A modified theory for the saturation of the bump-on-tail instability in the Earth's foreshock is proposed and examined using numerical simulation and quasi-linear theoretical techniques. It is argued the mechanism due to Filbert and Kellogg and to Cairns which is responsible for the creation of the bump-on-tail velocity distribution in the foreshock is still operative during the evolution of the bump-on-tail instability. The saturated state of the plasma must represent a balance between this creation mechanism and velocity space diffusion; the saturated state is not determined by velocity space diffusion alone. Thus the velocity distribution of the saturated stat may still appear bump-on-tail unstable to standard linear analysis which does not take the creation mechanism into account. The bump-on-tail velocity distributions in the foreshock would then represent the state of the plasma after saturation of the bump-on-tail instability, not before
Persistent luminescence and thermoluminescence of UV/VIS -irradiated SrAl2O4: Eu2+, Dy3+ phosphor

International Nuclear Information System (INIS)

Pereyda-Pierre, C.; Meléndrez, R.; García, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2011-01-01

The persistent luminescence and thermoluminescence properties of SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors excited with UV–VIS light in the 200–500 nm region were investigated. The thermoluminescence glow curve was found to be composed of peaks around 70, 125 and 245 °C. The persistent luminescence and thermoluminescence excitation spectra exhibited a broad band around 300–500 nm centered at 400 and 420 nm respectively. A linear behavior of the integrated thermoluminescence intensity and persistent luminescence versus irradiation time was found for the first 60 s. The charge detrapping from the 70 °C trapping levels was the major contributor to the observed persistent luminescence at room temperature. The SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors have suitable properties to be applied as storage and persistent luminescence UV–VIS irradiation dose phosphor. -- Highlights: ► SrAl 2 O 4 :Eu 2+ , Dy 3+ persistent luminescence and thermoluminescence was measured. ► The phosphor was irradiated with UV–VIS photons in the 200–500 nm wavelength range. ► SrAl 2 O 4 :Eu 2+ , Dy 3+ behaves adequately as persistent and storage UV–VIS dosimeter. ► The persistent luminescence dosimetry does not require heat or light stimulation.
Numeric invariants from multidimensional persistence

Energy Technology Data Exchange (ETDEWEB)

Skryzalin, Jacek [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carlsson, Gunnar [Stanford Univ., Stanford, CA (United States)

2017-05-19

In this paper, we analyze the space of multidimensional persistence modules from the perspectives of algebraic geometry. We first build a moduli space of a certain subclass of easily analyzed multidimensional persistence modules, which we construct specifically to capture much of the information which can be gained by using multidimensional persistence over one-dimensional persistence. We argue that the global sections of this space provide interesting numeric invariants when evaluated against our subclass of multidimensional persistence modules. Lastly, we extend these global sections to the space of all multidimensional persistence modules and discuss how the resulting numeric invariants might be used to study data.
Persistent Aerial Tracking

KAUST Repository

Mueller, Matthias

2016-01-01

persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc
Persistent angina

DEFF Research Database (Denmark)

Jespersen, L.; Abildstrom, S. Z.; Hvelplund, Anders

2013-01-01

To evaluate persistent angina in stable angina pectoris with no obstructive coronary artery disease (CAD) compared to obstructive CAD and its relation to long-term anxiety, depression, quality of life (QOL), and physical functioning. We invited 357 patients (men = 191; women = 166; response rate 83......-obstructive CAD or normal coronary arteries than in patients with obstructive CAD. Persistent angina symptoms were associated with long-term anxiety, depression, impaired physical functioning, and QOL irrespective of the degree of CAD. Contrary to common perception, excluding obstructive CAD in stable angina does...... %) with no prior cardiovascular disease who had a first-time coronary angiography (CAG) in 2008-2009 due to suspected stable angina to participate in a questionnaire survey in 2011 with the Seattle Angina Questionnaire and the Hospital Anxiety and Depression Scale as key elements. Long-term persistent angina (i...
Variable Persister Gene Interactions with (pppGpp for Persister Formation in Escherichia coli

Directory of Open Access Journals (Sweden)

Shuang Liu

2017-09-01

Full Text Available Persisters comprise a group of phenotypically heterogeneous metabolically quiescent bacteria with multidrug tolerance and contribute to the recalcitrance of chronic infections. Although recent work has shown that toxin-antitoxin (TA system HipAB depends on stringent response effector (pppGppin persister formation, whether other persister pathways are also dependent on stringent response has not been explored. Here we examined the relationship of (pppGpp with 15 common persister genes (dnaK, clpB, rpoS, pspF, tnaA, sucB, ssrA, smpB, recA, umuD, uvrA, hipA, mqsR, relE, dinJ using Escherichia coli as a model. By comparing the persister levels of wild type with their single gene knockout and double knockout mutants with relA, we divided their interactions into five types, namely A “dependent” (dnaK, recA, B “positive reinforcement” (rpoS, pspF, ssrA, recA, C “antagonistic” (clpB, sucB, umuD, uvrA, hipA, mqsR, relE, dinJ, D “epistasis” (clpB, rpoS, tnaA, ssrA, smpB, hipA, and E “irrelevant” (dnaK, clpB, rpoS, tnaA, sucB, smpB, umuD, uvrA, hipA, mqsR, relE, dinJ. We found that the persister gene interactions are intimately dependent on bacterial culture age, cell concentrations (diluted versus undiluted culture, and drug classifications, where the same gene may belong to different groups with varying antibiotics, culture age or cell concentrations. Together, this study represents the first attempt to systematically characterize the intricate relationships among the different mechanisms of persistence and as such provide new insights into the complexity of the persistence phenomenon at the level of persister gene network interactions.
LINEAR2007, Linear-Linear Interpolation of ENDF Format Cross-Sections

International Nuclear Information System (INIS)

2007-01-01

1 - Description of program or function: LINEAR converts evaluated cross sections in the ENDF/B format into a tabular form that is subject to linear-linear interpolation in energy and cross section. The code also thins tables of cross sections already in that form. Codes used subsequently need thus to consider only linear-linear data. IAEA1311/15: This version include the updates up to January 30, 2007. Changes in ENDF/B-VII Format and procedures, as well as the evaluations themselves, make it impossible for versions of the ENDF/B pre-processing codes earlier than PREPRO 2007 (2007 Version) to accurately process current ENDF/B-VII evaluations. The present code can handle all existing ENDF/B-VI evaluations through release 8, which will be the last release of ENDF/B-VI. Modifications from previous versions: - Linear VERS. 2007-1 (JAN. 2007): checked against all ENDF/B-VII; increased page size from 60,000 to 600,000 points 2 - Method of solution: Each section of data is considered separately. Each section of File 3, 23, and 27 data consists of a table of cross section versus energy with any of five interpolation laws. LINEAR will replace each section with a new table of energy versus cross section data in which the interpolation law is always linear in energy and cross section. The histogram (constant cross section between two energies) interpolation law is converted to linear-linear by substituting two points for each initial point. The linear-linear is not altered. For the log-linear, linear-log and log- log laws, the cross section data are converted to linear by an interval halving algorithm. Each interval is divided in half until the value at the middle of the interval can be approximated by linear-linear interpolation to within a given accuracy. The LINEAR program uses a multipoint fractional error thinning algorithm to minimize the size of each cross section table

Inflation persistence and flexible prices

OpenAIRE

Robert Dittmar; William T. Gavin; Finn E. Kydland

2004-01-01

If the central bank follows an interest rate rule, then inflation is likely to be persistence, even when prices are fully flexible. Any shock, whether persistent or not, may lead to inflation persistence. In equilibrium, the dynamics of inflation are determined by the evolution of the spread between the real interest rate and the central bank’s target. Inflation persistence in U.S. data can be characterized by a vector autocorrelation function relating inflation and deviations of output from ...
Physical trust-based persistent authentication

DEFF Research Database (Denmark)

Fujita, Masahiro; Jensen, Christian D.; Arimura, Shiori

2015-01-01

propose a new type of persistent authentication, called Persistent Authentication Based On physical Trust (PABOT). PABOT uses a context of “physical trust relationship” that is built by visual contact between users, and thus can offer a persistent authentication mechanism with better usability and higher...
Classification of Listeria monocytogenes persistence in retail delicatessen environments using expert elicitation and machine learning.

Science.gov (United States)

Vangay, P; Steingrimsson, J; Wiedmann, M; Stasiewicz, M J

2014-10-01

Increasing evidence suggests that persistence of Listeria monocytogenes in food processing plants has been the underlying cause of a number of human listeriosis outbreaks. This study extracts criteria used by food safety experts in determining bacterial persistence in the environment, using retail delicatessen operations as a model. Using the Delphi method, we conducted an expert elicitation with 10 food safety experts from academia, industry, and government to classify L. monocytogenes persistence based on environmental sampling results collected over six months for 30 retail delicatessen stores. The results were modeled using variations of random forest, support vector machine, logistic regression, and linear regression; variable importance values of random forest and support vector machine models were consolidated to rank important variables in the experts' classifications. The duration of subtype isolation ranked most important across all expert categories. Sampling site category also ranked high in importance and validation errors doubled when this covariate was removed. Support vector machine and random forest models successfully classified the data with average validation errors of 3.1% and 2.2% (n = 144), respectively. Our findings indicate that (i) the frequency of isolations over time and sampling site information are critical factors for experts determining subtype persistence, (ii) food safety experts from different sectors may not use the same criteria in determining persistence, and (iii) machine learning models have potential for future use in environmental surveillance and risk management programs. Future work is necessary to validate the accuracy of expert and machine classification against biological measurement of L. monocytogenes persistence. © 2014 Society for Risk Analysis.
Persistence-Based Branch Misprediction Bounds for WCET Analysis

DEFF Research Database (Denmark)

Puffitsch, Wolfgang

2015-01-01

Branch prediction is an important feature of pipelined processors to achieve high performance. However, it can lead to overly pessimistic worst-case execution time (WCET) bounds when being modeled too conservatively. This paper presents bounds on the number of branch mispredictions for local...... dynamic branch predictors. To handle interferences between branch instructions we use the notion of persistence, a concept that is also found in cache analyses. The bounds apply to branches in general, not only to branches that close a loop. Furthermore, the bounds can be easily integrated into integer...... linear programming formulations of the WCET problem. An evaluation on a number of benchmarks shows that with these bounds, dynamic branch prediction does not necessarily lead to higher WCET bounds than static prediction schemes....
New-found fundamentals of bacterial persistence.

Science.gov (United States)

Kint, Cyrielle I; Verstraeten, Natalie; Fauvart, Maarten; Michiels, Jan

2012-12-01

Persister cells display tolerance to high doses of bactericidal antibiotics and typically comprise a small fraction of a bacterial population. Recently, evidence was provided for a causal link between therapy failure and the presence of persister cells in chronic infections, underscoring the need for research on bacterial persistence. A series of recent breakthroughs have shed light on the multiplicity of persister genes, the contribution of gene expression noise to persister formation, the importance of active responses to antibiotic tolerance and heterogeneity among persister cells. Moreover, the development of in vivo model systems has highlighted the clinical relevance of persistence. This review discusses these recent advances and how this knowledge fundamentally changes the way in which we will perceive the problem of antibiotic tolerance in years to come. Copyright © 2012 Elsevier Ltd. All rights reserved.
Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

Science.gov (United States)

Storm, Ingeborg M.; Stuart, Martien A. Cohen; de Vries, Renko; Leermakers, Frans A. M.

2018-03-01

A self-consistent field analysis for tunable contributions to the persistence length of isolated semiflexible polymer chains including electrostatically driven coassembled deoxyribonucleic acid (DNA) bottlebrushes is presented. When a chain is charged, i.e., for polyelectrolytes, there is, in addition to an intrinsic rigidity, an electrostatic stiffening effect, because the electric double layer resists bending. For molecular bottlebrushes, there is an induced contribution due to the grafts. We explore cases beyond the classical phantom main-chain approximation and elaborate molecularly more realistic models where the backbone has a finite volume, which is necessary for treating coassembled bottlebrushes. We find that the way in which the linear charge density or the grafting density is regulated is important. Typically, the stiffening effect is reduced when there is freedom for these quantities to adapt to the curvature stresses. Electrostatically driven coassembled bottlebrushes, however, are relatively stiff because the chains have a low tendency to escape from the compressed regions and the electrostatic binding force is largest in the convex part. For coassembled bottlebrushes, the induced persistence length is a nonmonotonic function of the polymer concentration: For low polymer concentrations, the stiffening grows quadratically with coverage; for semidilute polymer concentrations, the brush chains retract and regain their Gaussian size. When doing so, they lose their induced persistence length contribution. Our results correlate well with observed physical characteristics of electrostatically driven coassembled DNA-bioengineered protein-polymer bottlebrushes.
Linearization Method and Linear Complexity

Science.gov (United States)

Tanaka, Hidema

We focus on the relationship between the linearization method and linear complexity and show that the linearization method is another effective technique for calculating linear complexity. We analyze its effectiveness by comparing with the logic circuit method. We compare the relevant conditions and necessary computational cost with those of the Berlekamp-Massey algorithm and the Games-Chan algorithm. The significant property of a linearization method is that it needs no output sequence from a pseudo-random number generator (PRNG) because it calculates linear complexity using the algebraic expression of its algorithm. When a PRNG has n [bit] stages (registers or internal states), the necessary computational cost is smaller than O(2n). On the other hand, the Berlekamp-Massey algorithm needs O(N2) where N(≅2n) denotes period. Since existing methods calculate using the output sequence, an initial value of PRNG influences a resultant value of linear complexity. Therefore, a linear complexity is generally given as an estimate value. On the other hand, a linearization method calculates from an algorithm of PRNG, it can determine the lower bound of linear complexity.
Persistent homology of complex networks

International Nuclear Information System (INIS)

Horak, Danijela; Maletić, Slobodan; Rajković, Milan

2009-01-01

Long-lived topological features are distinguished from short-lived ones (considered as topological noise) in simplicial complexes constructed from complex networks. A new topological invariant, persistent homology, is determined and presented as a parameterized version of a Betti number. Complex networks with distinct degree distributions exhibit distinct persistent topological features. Persistent topological attributes, shown to be related to the robust quality of networks, also reflect the deficiency in certain connectivity properties of networks. Random networks, networks with exponential connectivity distribution and scale-free networks were considered for homological persistency analysis
Off-Line Robust Constrained MPC for Linear Time-Varying Systems with Persistent Disturbances

Directory of Open Access Journals (Sweden)

P. Bumroongsri

2014-01-01

Full Text Available An off-line robust constrained model predictive control (MPC algorithm for linear time-varying (LTV systems is developed. A novel feature is the fact that both model uncertainty and bounded additive disturbance are explicitly taken into account in the off-line formulation of MPC. In order to reduce the on-line computational burdens, a sequence of explicit control laws corresponding to a sequence of positively invariant sets is computed off-line. At each sampling time, the smallest positively invariant set containing the measured state is determined and the corresponding control law is implemented in the process. The proposed MPC algorithm can guarantee robust stability while ensuring the satisfaction of input and output constraints. The effectiveness of the proposed MPC algorithm is illustrated by two examples.
Persistent myalgia following whiplash.

Science.gov (United States)

Dommerholt, Jan

2005-10-01

Persistent myalgia following whiplash is commonly considered the result of poor psychosocial status, illness behavior, or failing coping skills. However, there is much evidence that persistent myalgia may be due to neurophysiologic mechanisms involving peripheral and central sensitization. Myofascial trigger points may play a crucial role in maintaining sensitization. Recent research suggests that the chemical environment of myofascial trigger points is an important factor. Several consequences are reviewed when central pain mechanisms and myofascial trigger points are included in the differential diagnosis and in the management of patients with persistent pain following whiplash.
Harm avoidance and persistence are associated with somatoform disorder psychopathology: A study in Taiwan.

Science.gov (United States)

Huang, Wei-Lieh; Chen, Tzu-Ting; Chen, I-Ming; Chang, Li-Ren; Lin, Yu-Hsuan; Liao, Shih-Cheng; Gau, Susan Shur-Fen

2016-05-15

Whether personality features affect the development of somatoform disorders and their psychopathologies is an important issue. Aim of this study was to resolve this issue by comparing indicators of psychopathology and personality features in subjects with somatoform disorders and healthy controls. This study recruited 148 subjects with somatoform disorders and 146 healthy controls. The severity of psychopathology was measured with the Patient Health Questionnaire-15 (PHQ-15), Health Anxiety Questionnaire (HAQ), Beck Depression Inventory-II (BDI-II), and Beck Anxiety Inventory (BAI). The Tridimensional Personality Questionnaire (TPQ) was used to assess personality features. Demographic data, psychopathology indicators, and TPQ scores were compared between groups. Correlation and multivariate linear regression analysis were used to identify the personality dimensions or demographic variables associated with psychopathology. The somatoform group had lower novelty seeking (NS) and reward dependence (RD) and higher harm avoidance (HA) and severity of psychopathologies. Multiple regression analysis revealed that fatigability, persistence, gender, and education level were predictive of PHQ-15; HA, educational level, persistence, and dependence were predictive of HAQ; HA, persistence, education level, and NS were predictive of BDII-II; and fatigability, education level, persistence, and anticipatory worry were predictive of BAI. The development of somatoform disorders was associated with fatigability, age, residence location, education level, and attachment. The limitations include heterogeneity of the diagnosis, the high proportion of undifferentiated somatoform disorder, and the cross-sectional study design. HA/fatigability, persistence, and education level are associated with each type of psychopathology. Fatigability is a powerful predictor of somatoform disorder development. Copyright © 2016. Published by Elsevier B.V.
Hippocampal subfield and medial temporal cortical persistent activity during working memory reflects ongoing encoding

Directory of Open Access Journals (Sweden)

Rachel K Nauer

2015-03-01

Full Text Available Previous neuroimaging studies support a role for the medial temporal lobes (MTL in maintaining novel stimuli over brief working memory (WM delays, and suggest delay period activity predicts subsequent memory. Additionally, slice recording studies have demonstrated neuronal persistent spiking in entorhinal cortex (EC, perirhinal cortex (PrC, and hippocampus (CA1, CA3, subiculum. These data have led to computational models that suggest persistent spiking in parahippocampal regions could sustain neuronal representations of sensory information over many seconds. This mechanism may support both WM maintenance and encoding of information into long term episodic memory. The goal of the current study was to use high-resolution fMRI to elucidate the contributions of the MTL cortices and hippocampal subfields to WM maintenance as it relates to later episodic recognition memory. We scanned participants while they performed a delayed match to sample task with novel scene stimuli, and assessed their memory for these scenes post-scan. We hypothesized stimulus-driven activation that persists into the delay period—a putative correlate of persistent spiking—would predict later recognition memory. Our results suggest sample and delay period activation in the parahippocampal cortex (PHC, PrC, and subiculum (extending into DG/CA3 and CA1 was linearly related to increases in subsequent memory strength. These data extend previous neuroimaging studies that have constrained their analysis to either the sample or delay period by modeling these together as one continuous ongoing encoding process, and support computational frameworks that predict persistent activity underlies both WM and episodic encoding.
Persistent luminescence nanothermometers

Science.gov (United States)

Martín Rodríguez, Emma; López-Peña, Gabriel; Montes, Eduardo; Lifante, Ginés; García Solé, José; Jaque, Daniel; Diaz-Torres, Luis Armando; Salas, Pedro

2017-08-01

Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20-60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.
Is bacterial persistence a social trait?

Directory of Open Access Journals (Sweden)

Andy Gardner

Full Text Available The ability of bacteria to evolve resistance to antibiotics has been much reported in recent years. It is less well-known that within populations of bacteria there are cells which are resistant due to a non-inherited phenotypic switch to a slow-growing state. Although such 'persister' cells are receiving increasing attention, the evolutionary forces involved have been relatively ignored. Persistence has a direct benefit to cells because it allows survival during catastrophes-a form of bet-hedging. However, persistence can also provide an indirect benefit to other individuals, because the reduced growth rate can reduce competition for limiting resources. This raises the possibility that persistence is a social trait, which can be influenced by kin selection. We develop a theoretical model to investigate the social consequences of persistence. We predict that selection for persistence is increased when: (a cells are related (e.g. a single, clonal lineage; and (b resources are scarce. Our model allows us to predict how the level of persistence should vary with time, across populations, in response to intervention strategies and the level of competition. More generally, our results clarify the links between persistence and other bet-hedging or social behaviours.
Linear accelerator stereotactic radiosurgery for vestibular schwannomas: a UK series.

Science.gov (United States)

Benghiat, H; Heyes, G; Nightingale, P; Hartley, A; Tiffany, M; Spooner, D; Geh, J I; Cruickshank, G; Irving, R M; Sanghera, P

2014-06-01

To evaluate non-auditory toxicity and local control after linear accelerator stereotactic radiosurgery (SRS) for the treatment of vestibular schwannomas. The institutional policy was to use SRS for radiologically progressing vestibular schwannomas. Case notes and plans were retrospectively reviewed for all patients undergoing SRS for vestibular schwannomas between September 2002 and June 2012. All patients were surgically immobilised using a BrainLab stereotactic head frame. The treatment plan was generated using BrainLab software (BrainScan 5.03). The aim was to deliver 12 Gy to the surface of the target with no margin. Patients with a minimum of 12 months of follow-up were included for toxicity and local control assessment. Radiological progression was defined as growth on imaging beyond 2 years of follow-up. Overall local control was defined in line with other series as absence of surgical salvage. Ninety-nine patients were identified. Two patients were lost to follow-up. After a median follow-up interval of 2.4 years, the actuarial radiological progression-free survival at 3 years was 100% and overall local control was also 100%. However, two patients progressed radiologically at 3.3 and 4.5 years, respectively. Twenty-one of 97 (22%) evaluable patients suffered trigeminal toxicity and this was persistent in 8/97 (8%). Two of 97 (2%) suffered long-term facial nerve toxicity (one with associated radiological progression causing hemi-facial spasm alone). One of 97 (1%) required intervention for obstructive hydrocephalus. No statistically significant dosimetric relationship could be shown to cause trigeminal or facial nerve toxicity. However, 7/8 patients with persistent trigeminal nerve toxicity had tumours in contact with the trigeminal nerve. SRS delivering 12 Gy using a linear accelerator leads to high local control rates, but only prospective evaluation will fully establish short-term toxicity. In this study, persistent trigeminal toxicity occurred almost
Dualities in persistent (co)homology

International Nuclear Information System (INIS)

De Silva, Vin; Morozov, Dmitriy; Vejdemo-Johansson, Mikael

2011-01-01

We consider sequences of absolute and relative homology and cohomology groups that arise naturally for a filtered cell complex. We establish algebraic relationships between their persistence modules, and show that they contain equivalent information. We explain how one can use the existing algorithm for persistent homology to process any of the four modules, and relate it to a recently introduced persistent cohomology algorithm. We present experimental evidence for the practical efficiency of the latter algorithm
The role of metabolism in bacterial persistence

Directory of Open Access Journals (Sweden)

Stephanie M. Amato

2014-03-01

Full Text Available Bacterial persisters are phenotypic variants with extraordinary tolerances toward antibiotics. Persister survival has been attributed to inhibition of essential cell functions during antibiotic stress, followed by reversal of the process and resumption of growth upon removal of the antibiotic. Metabolism plays a critical role in this process, since it participates in the entry, maintenance, and exit from the persister phenotype. Here, we review the experimental evidence that demonstrates the importance of metabolism to persistence, highlight the successes and potential for targeting metabolism in the search for anti-persister therapies, and discuss the current methods and challenges to understand persister physiology.
Introduction: Persistent Modelling

DEFF Research Database (Denmark)

Ayres, Phil

2012-01-01

This introduction to 'Persistent Modelling – an extended role for architectural representation' identifies how the book probes the relationship between representation and the represented, in an architectural context. It discusses how the book presents an examination and discussion of historical......, familiar contemporary and, perhaps, not so familiar emerging manifestations of this relation. What persists from this probing, fully intact, is that representation and the represented remain inextricably related in our contemporary and emerging practices. What comes into focus is that the nature...
White matter developmental trajectories associated with persistence and recovery of childhood stuttering.

Science.gov (United States)

Chow, Ho Ming; Chang, Soo-Eun

2017-04-08

Stuttering affects the fundamental human ability of fluent speech production, and can have a significant negative impact on an individual's psychosocial development. While the disorder affects about 5% of all preschool children, approximately 80% of them recover naturally within a few years of stuttering onset. The pathophysiology and neuroanatomical development trajectories associated with persistence and recovery of stuttering are still largely unknown. Here, the first mixed longitudinal diffusion tensor imaging (DTI) study of childhood stuttering has been reported. A total of 195 high quality DTI scans from 35 children who stutter (CWS) and 43 controls between 3 and 12 years of age were acquired, with an average of three scans per child, each collected approximately a year apart. Fractional anisotropy (FA), a measure reflecting white matter structural coherence, was analyzed voxel-wise to examine group and age-related differences using a linear mixed-effects (LME) model. Results showed that CWS exhibited decreased FA relative to controls in the left arcuate fasciculus, underlying the inferior parietal and posterior temporal areas, and the mid body of corpus callosum. Further, white matter developmental trajectories reflecting growth rate of these tract regions differentiated children with persistent stuttering from those who recovered from stuttering. Specifically, a reduction in FA growth rate (i.e., slower FA growth with age) in persistent children relative to fluent controls in the left arcuate fasciculus and corpus callosum was found, which was not evident in recovered children. These findings provide first glimpses into the possible neural mechanisms of onset, persistence, and recovery of childhood stuttering. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Association Between Persistent Pain and Memory Decline and Dementia in a Longitudinal Cohort of Elders.

Science.gov (United States)

Whitlock, Elizabeth L; Diaz-Ramirez, L Grisell; Glymour, M Maria; Boscardin, W John; Covinsky, Kenneth E; Smith, Alexander K

2017-08-01

Chronic pain is common among the elderly and is associated with cognitive deficits in cross-sectional studies; the population-level association between chronic pain and longitudinal cognition is unknown. To determine the population-level association between persistent pain, which may reflect chronic pain, and subsequent cognitive decline. Cohort study with biennial interviews of 10 065 community-dwelling older adults in the nationally representative Health and Retirement Study who were 62 years or older in 2000 and answered pain and cognition questions in both 1998 and 2000. Data analysis was conducted between June 24 and October 31, 2016. "Persistent pain," defined as a participant reporting that he or she was often troubled with moderate or severe pain in both the 1998 and 2000 interviews. Coprimary outcomes were composite memory score and dementia probability, estimated by combining neuropsychological test results and informant and proxy interviews, which were tracked from 2000 through 2012. Linear mixed-effects models, with random slope and intercept for each participant, were used to estimate the association of persistent pain with slope of the subsequent cognitive trajectory, adjusting for demographic characteristics and comorbidities measures in 2000 and applying sampling weights to represent the 2000 US population. We hypothesized that persistent pain would predict accelerated memory decline and increased probability of dementia. To quantify the impact of persistent pain on functional independence, we combined our primary results with information on the association between memory and ability to manage medications and finances independently. Of the 10 065 eligible HRS sample members, 60% were female, and median baseline age was 73 years (interquartile range, 67-78 years). At baseline, persistent pain affected 10.9% of participants and was associated with worse depressive symptoms and more limitations in activities of daily living. After covariate

Linear Algebra and Smarandache Linear Algebra

OpenAIRE

Vasantha, Kandasamy

2003-01-01

The present book, on Smarandache linear algebra, not only studies the Smarandache analogues of linear algebra and its applications, it also aims to bridge the need for new research topics pertaining to linear algebra, purely in the algebraic sense. We have introduced Smarandache semilinear algebra, Smarandache bilinear algebra and Smarandache anti-linear algebra and their fuzzy equivalents. Moreover, in this book, we have brought out the study of linear algebra and vector spaces over finite p...
Prognostic Factors for Persistent Leg-Pain in Patients Hospitalized With Acute Sciatica.

Science.gov (United States)

Fjeld, Olaf; Grotle, Margreth; Siewers, Vibeke; Pedersen, Linda M; Nilsen, Kristian Bernhard; Zwart, John-Anker

2017-03-01

Prospective cohort study. To identify potential prognostic factors for persistent leg-pain at 12 months among patients hospitalized with acute severe sciatica. The long-term outcome for patients admitted to hospital with sciatica is generally unfavorable. Results concerning prognostic factors for persistent sciatica are limited and conflicting. A total of 210 patients acutely admitted to hospital for either surgical or nonsurgical treatment of sciatica were consecutively recruited and received a thorough clinical and radiographic examination in addition to responding to a comprehensive questionnaire. Follow-up assessments were done at 6 weeks, 6 months, and 12 months. Potential prognostic factors were measured at baseline and at 6 weeks. The impact of these factors on leg-pain was analyzed by multiple linear regression modeling. A total of 151 patients completed the entire study, 93 receiving nonrandomized surgical treatment. The final multivariate models showed that the following factors were significantly associated with leg-pain at 12 months: high psychosocial risk according to the Örebro Musculosceletal Pain Questionnaire (unstandardized beta coefficient 1.55, 95% confidence interval [CI] 0.72-2.38, P sciatica. 2.
Persistent and recurrent hyperparathyroidism.

Science.gov (United States)

Guerin, Carole; Paladino, Nunzia Cinzia; Lowery, Aoife; Castinetti, Fréderic; Taieb, David; Sebag, Fréderic

2017-06-01

Despite remarkable progress in imaging modalities and surgical management, persistence or recurrence of primary hyperparathyroidism (PHPT) still occurs in 2.5-5% of cases of PHPT. The aim of this review is to expose the management of persistent and recurrent hyperparathyroidism. A literature search was performed on MEDLINE using the search terms "recurrent" or "persistent" and "hyperparathyroidism" within the past 10 years. We also searched the reference lists of articles identified by this search strategy and selected those we judged relevant. Before considering reoperation, the surgeon must confirm the diagnosis of PHPT. Then, the patient must be evaluated with new imaging modalities. A single adenoma is found in 68% of cases, multiglandular disease in 28%, and parathyroid carcinoma in 3%. Others causes (<1%) include parathyromatosis and graft recurrence. The surgeon must balance the benefits against the risks of a reoperation (permanent hypocalcemia and recurrent laryngeal nerve palsy). If surgery is necessary, a focused approach can be considered in cases of significant imaging foci, but in the case of multiglandular disease, a bilateral neck exploration could be necessary. Patients with multiple endocrine neoplasia syndromes are at high risk of recurrence and should be managed regarding their hereditary pathology. The cure rate of persistent-PHPT or recurrent-PHPT in expert centers is estimated from 93 to 97%. After confirming the diagnosis of PHPT, patients with persistent-PHPT and recurrent-PHPT should be managed in an expert center with all dedicated competencies.
Persistence of interest in science, technology, engineering and mathematics: An analysis of persisting and non-persisting students

Science.gov (United States)

White, Jeffry L.

While there has been an increase in enrollment, interest in science, technology, engineering, and mathematics (STEM) has been declining on college campuses since 1967. Higher enrollment does not transfer to an increase in the number of minorities in the STEM fields. The majority-minority enrollment ratio is nearly 2:1 but the gap widens to 4:1 when it comes to graduation. In fact, underrepresented minorities (URM) earned only 12% of the STEM degrees awarded in 1998. When the higher attrition and lower graduation rates of URM are scrutinized, upwards of 60% changed majors or dropped out of STEM. Further investigation reveals the most frequently cited reasons for departure were loss of initial interest, developed a greater interest in another field, or were turned off by the STEM disciplines. A primarily exploratory study was conducted into the conditions necessary for academic interest in the STEM fields to persist. A model based on student engagement (Astin, 1977) and interest operations (Prenzel, 1988a) theories was used with a random sample of URM at universities participating in the Ohio Science and Engineering Alliance. Survey research was employed to investigate interest development and the effect of student retention programs and activities on such interest. The latter part of the study could not be fully examined when 95% reported not utilizing retention services. For the section on interest, an online survey using a 5-point Likert scale was validated using principal components analysis. A binominal logistic regression was used to predict membership in one of two possible groups: persisters and students at-risk for not persisting. The major conclusions are: (1) While 3 variables (feelings, learning and difficulty) were statistically significant only one, feelings was substantively significant. (2) Persistence increased 80.9% for each 1-unit increase in feelings and 9.9% for learning. (3) Persistence decreased 19.8% for each one-unit increase in difficulty
Micro-physics of aircraft-generated aerosols and their potential impact on heterogeneous plume chemistry

Energy Technology Data Exchange (ETDEWEB)

Kaercher, B; Luo, B P [Muenchen Univ., Freising (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

1998-12-31

Answers are attempted to give to open questions concerning physico-chemical processes in near-field aircraft plumes, with emphasis on their potential impact on subsequent heterogeneous chemistry. Research issues concerning the nucleation of aerosols and their interactions among themselves and with exhaust gases are summarized. Microphysical properties of contrail ice particles, formation of liquid ternary mixtures, and nucleation of nitric acid trihydrate particles in contrails are examined and possible implications for heterogeneous plume chemistry are discussed. (author) 19 refs.
Micro-physics of aircraft-generated aerosols and their potential impact on heterogeneous plume chemistry

Energy Technology Data Exchange (ETDEWEB)

Kaercher, B.; Luo, B.P. [Muenchen Univ., Freising (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

1997-12-31

Answers are attempted to give to open questions concerning physico-chemical processes in near-field aircraft plumes, with emphasis on their potential impact on subsequent heterogeneous chemistry. Research issues concerning the nucleation of aerosols and their interactions among themselves and with exhaust gases are summarized. Microphysical properties of contrail ice particles, formation of liquid ternary mixtures, and nucleation of nitric acid trihydrate particles in contrails are examined and possible implications for heterogeneous plume chemistry are discussed. (author) 19 refs.
Persistence Characteristics of Australian Rainfall Anomalies

Science.gov (United States)

Simmonds, Ian; Hope, Pandora

1997-05-01

Using 79 years (1913-1991) of Australian monthly precipitation data we examined the nature of the persistence of rainfall anomalies. Analyses were performed for four climate regions covering the country, as well as for the entire Australian continent. We show that rainfall over these regions has high temporal variability and that annual rainfall amounts over all five sectors vary in phase and are, with the exception of the north-west region, significantly correlated with the Southern Oscillation Index (SOI). These relationships were particularly strong during the spring season.It is demonstrated that Australian rainfall exhibits statistically significant persistence on monthly, seasonal, and (to a limited extent) annual time-scales, up to lags of 3 months and one season and 1 year. The persistence showed strong seasonal dependence, with each of the five regions showing memory out to 4 or 5 months from winter and spring. Many aspects of climate in the Australasian region are known to have undergone considerable changes about 1950. We show this to be true for persistence also; its characteristics identified for the entire record were present during the 1951--1980 period, but virtually disappeared in the previous 30-year period.Much of the seasonal distribution of rainfall persistence on monthly time-scales, particularly in the east, is due to the influence of the SOI. However, most of the persistence identified in winter and spring in the north-west is independent of the ENSO phenomenon.Rainfall anomalies following extreme dry and wet months, seasons and years (lowest and highest two deciles) persisted more than would be expected by chance. For monthly extreme events this was more marked in the winter semester for the wet events, except in the south-east region. In general, less persistence was found for the extreme seasons. Although the persistence of dry years was less than would have been expected by chance, the wet years appear to display persistence.
Environmental controls on spatial patterns in the long-term persistence of giant kelp in central California

Science.gov (United States)

Young, Mary Alida; Cavanaugh, Kyle C.; Bell, Tom W.; Raimondi, Peter T.; Edwards, Christopher A.; Drake, Patrick T.; Erikson, Li H.; Storlazzi, Curt

2016-01-01

As marine management is moving towards the practice of protecting static areas, it is 44 important to make sure protected areas capture and protect persistent populations. Rocky reefs in 45 many temperate areas worldwide serve as habitat for canopy forming macroalgae and these 46 structure forming species of kelps (order Laminariales) often serve as important habitat for a great 47 diversity of species. Macrocystis pyrifera is the most common canopy forming kelp species found 48 along the coast of California but the distribution and abundance of M. pyrifera varies in space and 49 time. The purpose of this study is to determine what environmental parameters are correlated with 50 the spatial and temporal persistence of M. pyrifera along the central coast of California and how 51 well those environmental parameters can be used to predict areas where M. pyrifera is more likely 52 to persist. Nine environmental variables considered in this study included depth of the seafloor, 53 structure of the rocky reef, proportion of rocky reef, size of kelp patch, biomass of kelp within a 54 patch, distance from the edge of a kelp patch, sea surface temperature, wave orbital velocities, and 55 population connectivity of individual kelp patches. Using a generalized linear mixed effects model 56 (GLMM), the persistence of M. pyrifera was significantly associated with seven of the nine 57 variables considered: depth, complexity of the rocky reef, proportion of rock, patch biomass, 58 distance from the edge of a patch, population connectivity, and wave-orbital velocities. These 59 seven environmental variables were then used to predict the persistence of kelp across the central 60 coast and these predictions were compared to a reserved dataset of M. pyrifera persistence, which 61 was not used in the creation of the GLMM. The environmental variables were shown to accurately 62 predict the persistence of M. pyrifera within the central coast of California (r = 0.71, P<0.001). 63 Because
Contributions to Persistence Theory

Directory of Open Access Journals (Sweden)

Du Dong

2014-12-01

Full Text Available Persistence theory discussed in this paper is an application of algebraic topology (Morse Theory [29] to Data Analysis, precisely to qualitative understanding of point cloud data, or PCD for short. PCD can be geometrized as a filtration of simplicial complexes (Vietoris-Rips complex [25] [36] and the homology changes of these complexes provide qualitative information about the data. Bar codes describe the changes in homology with coefficients in a fixed field. When the coefficient field is ℤ2, the calculation of bar codes is done by ELZ algorithm (named after H. Edelsbrunner, D. Letscher, and A. Zomorodian [20]. When the coefficient field is ℝ, we propose an algorithm based on the Hodge decomposition [17]. With Dan Burghelea and Tamal K. Dey we developed a persistence theory which involves level sets discussed in Section 4. We introduce and discuss new computable invariants, the “relevant level persistence numbers” and the “positive and negative bar codes”, and explain how they are related to the bar codes for level persistence. We provide enhancements and modifications of ELZ algorithm to calculate such invariants and illustrate them by examples.
Nonlinear aeroacoustic characterization of Helmholtz resonators with a local-linear neuro-fuzzy network model

Science.gov (United States)

Förner, K.; Polifke, W.

2017-10-01

The nonlinear acoustic behavior of Helmholtz resonators is characterized by a data-based reduced-order model, which is obtained by a combination of high-resolution CFD simulation and system identification. It is shown that even in the nonlinear regime, a linear model is capable of describing the reflection behavior at a particular amplitude with quantitative accuracy. This observation motivates to choose a local-linear model structure for this study, which consists of a network of parallel linear submodels. A so-called fuzzy-neuron layer distributes the input signal over the linear submodels, depending on the root mean square of the particle velocity at the resonator surface. The resulting model structure is referred to as an local-linear neuro-fuzzy network. System identification techniques are used to estimate the free parameters of this model from training data. The training data are generated by CFD simulations of the resonator, with persistent acoustic excitation over a wide range of frequencies and sound pressure levels. The estimated nonlinear, reduced-order models show good agreement with CFD and experimental data over a wide range of amplitudes for several test cases.
Gate-controlled switching between persistent and inverse persistent spin helix states

International Nuclear Information System (INIS)

Yoshizumi, K.; Sasaki, A.; Kohda, M.; Nitta, J.

2016-01-01

We demonstrate gate-controlled switching between persistent spin helix (PSH) state and inverse PSH state, which are detected by quantum interference effect on magneto-conductance. These special symmetric spin states showing weak localization effect give rise to a long spin coherence when the strength of Rashba spin-orbit interaction (SOI) is close to that of Dresselhaus SOI. Furthermore, in the middle of two persistent spin helix states, where the Rashba SOI can be negligible, the bulk Dresselhaus SOI parameter in a modulation doped InGaAs/InAlAs quantum well is determined.
Gate-controlled switching between persistent and inverse persistent spin helix states

Energy Technology Data Exchange (ETDEWEB)

Yoshizumi, K.; Sasaki, A.; Kohda, M.; Nitta, J. [Department of Materials Science, Tohoku University, Sendai 980-8579 (Japan)

2016-03-28

We demonstrate gate-controlled switching between persistent spin helix (PSH) state and inverse PSH state, which are detected by quantum interference effect on magneto-conductance. These special symmetric spin states showing weak localization effect give rise to a long spin coherence when the strength of Rashba spin-orbit interaction (SOI) is close to that of Dresselhaus SOI. Furthermore, in the middle of two persistent spin helix states, where the Rashba SOI can be negligible, the bulk Dresselhaus SOI parameter in a modulation doped InGaAs/InAlAs quantum well is determined.
Demographics of antibiotic persistence

DEFF Research Database (Denmark)

Kollerova, Silvia; Jouvet, Lionel; Steiner, Ulrich

Persister cells, cells that can survive antibiotic exposure but lack heritable antibiotic resistance, are assumed to play a crucial role for the evolution of antibiotic resistance. Persistence is a stage associated with reduced metabolic activity. Most previous studies have been done on batch...... even play a more prominent role for the evolution of resistance and failures of medical treatment by antibiotics as currently assumed....
Reduction of Linear Programming to Linear Approximation

OpenAIRE

Vaserstein, Leonid N.

2006-01-01

It is well known that every Chebyshev linear approximation problem can be reduced to a linear program. In this paper we show that conversely every linear program can be reduced to a Chebyshev linear approximation problem.
Using Benchmarking To Strengthen the Assessment of Persistence.

Science.gov (United States)

McLachlan, Michael S; Zou, Hongyan; Gouin, Todd

2017-01-03

Chemical persistence is a key property for assessing chemical risk and chemical hazard. Current methods for evaluating persistence are based on laboratory tests. The relationship between the laboratory based estimates and persistence in the environment is often unclear, in which case the current methods for evaluating persistence can be questioned. Chemical benchmarking opens new possibilities to measure persistence in the field. In this paper we explore how the benchmarking approach can be applied in both the laboratory and the field to deepen our understanding of chemical persistence in the environment and create a firmer scientific basis for laboratory to field extrapolation of persistence test results.
Association between community pharmacy loyalty and persistence and implementation of antipsychotic treatment among individuals with schizophrenia.

Science.gov (United States)

Zongo, Frank E; Moisan, Jocelyne; Grégoire, Jean-Pierre; Lesage, Alain; Dossa, Anara Richi; Lauzier, Sophie

2018-01-01

Non-adherence is a major obstacle to optimal treatment of schizophrenia. Community pharmacists are in a key position to detect non-adherence and put in place interventions. Their role is likely to be more efficient when individuals are loyal to a single pharmacy. To assess the association between the level of community pharmacy loyalty and persistence with and implementation of antipsychotic drug treatment among individuals with schizophrenia. A cohort study using databases from the Quebec health insurance board (Canada) was conducted among new antipsychotic users insured by Quebec's public drug plan. Level of community pharmacy loyalty was assessed as the number of pharmacies visited in the year after antipsychotics initiation. Persistence was defined as having an antipsychotic supply in the user's possession on the 730 th day after its initiation and implementation as having antipsychotics in the user's possession for ≥80% of the days in the second year after antipsychotics initiation (among persistent only). Generalized linear models were used to estimate adjusted prevalence ratios (aPR) and 95% confidence intervals (95%CI). 6,251 individuals were included in the cohort and 54.1% had their drug prescriptions filled in >1 pharmacy. When compared to those who had their prescriptions filled in a single pharmacy, those who had their prescriptions filled in ≥4 different pharmacies were 22% more likely to be non-persistent (aPR = 1.22; 95%CI = 1.10-1.37) and 49% more likely to have an antipsychotic for loyalty in the context of severe mental illness indicates that this healthcare organisation factor might be associated with antipsychotics persistence and implementation. Identification of individuals with low community pharmacy loyalty and initiatives to optimize community pharmacy loyalty could contribute to enhanced persistence and implementation. Copyright © 2016 Elsevier Inc. All rights reserved.
Non-Linear Dynamics of Saturn's Rings

Science.gov (United States)

Esposito, L. W.

2016-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. Stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, that push the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like `straw' that can explain the halo morphology and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; this requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping explains both small and large particles at resonances. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating it as an asymmetric random walk with reflecting boundaries
Mastering NServiceBus and persistence

CERN Document Server

Helton, Rich

2014-01-01

This book is intended for developers, designers, and architects alike who wish to build C# NServiceBus enterprise architectures and learn how ESB persists data and messages to help them attain their goals. No prior knowledge of persistence in NServiceBus is required.
Persistent maternal depressive symptoms trajectories influence children's IQ: The EDEN mother-child cohort.

Science.gov (United States)

van der Waerden, Judith; Bernard, Jonathan Y; De Agostini, Maria; Saurel-Cubizolles, Marie-Josèphe; Peyre, Hugo; Heude, Barbara; Melchior, Maria

2017-02-01

This study assessed the association between timing and course of maternal depression from pregnancy onwards and children's cognitive development at ages 5 to 6. Potential interaction effects with child sex and family socioeconomic status were explored. One thousand thirty-nine mother-child pairs from the French EDEN mother-child birth cohort were followed from 24 to 28 weeks of pregnancy onwards. Based on Center for Epidemiological Studies Depression (CES-D) and Edinburgh Postnatal Depression Scale (EPDS) scores assessed at six timepoints, longitudinal maternal depressive symptom trajectories were calculated with a group-based semiparametric method. Children's cognitive function was assessed at ages 5 to 6 by trained interviewers with the Wechsler Preschool and Primary Scale of Intelligence Third Edition (WPPSI-III), resulting in three composite scores: Verbal IQ (VIQ), Performance IQ (PIQ), and Full-Scale IQ (FSIQ). Five trajectories of maternal symptoms of depression could be distinguished: no symptoms, persistent intermediate-level depressive symptoms, persistent high depressive symptoms, high symptoms in pregnancy only, and high symptoms in the child's preschool period only. Multiple linear regression analyses showed that, compared to children of mothers who were never depressed, children of mothers with persistent high levels of depressive symptoms had reduced VIQ, PIQ, and FSIQ scores. This association was moderated by the child's sex, boys appearing especially vulnerable in case of persistent maternal depression. Chronicity of maternal depression predicts children's cognitive development at school entry age, particularly in boys. As maternal mental health is an early modifiable influence on child development, addressing the treatment needs of depressed mothers may help reduce the associated burden on the next generation. © 2016 Wiley Periodicals, Inc.
Persistent disturbance rejection via state feedback for networked control systems

Energy Technology Data Exchange (ETDEWEB)

Yue Dong [Institute of Information and Control Engineering Technology, Nanjing Normal University, 78 Bancang Street, Nanjing, Jiangsu 210042 (China)], E-mail: medongy@njnu.edu.cn; Lam, James [Department of Mechanical Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); Wang Zidong [Department of Information Systems and Computing, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom)], E-mail: Zidong.Wang@brunel.ac.uk

2009-04-15

The problem of persistent disturbance rejection via state feedback for networked control systems is concerned based on the Lyapunov function method. The effect of the network conditions, such as network-induced delay and data dropout, is considered in the modeling of the system. It is assumed that the state and the control signals are individually quantized by quantizers on the sensor side and the controller side. The feedback gain and the quantizer parameters that guarantee the internal stability and the disturbance rejection performance of the closed-loop system are obtained by solving some linear matrix inequalities. To illustrate the effectiveness of the proposed method, a numerical example is provided for the design of the feedback gain and the quantizer parameters.

Persistent disturbance rejection via state feedback for networked control systems

International Nuclear Information System (INIS)

Yue Dong; Lam, James; Wang Zidong

2009-01-01

The problem of persistent disturbance rejection via state feedback for networked control systems is concerned based on the Lyapunov function method. The effect of the network conditions, such as network-induced delay and data dropout, is considered in the modeling of the system. It is assumed that the state and the control signals are individually quantized by quantizers on the sensor side and the controller side. The feedback gain and the quantizer parameters that guarantee the internal stability and the disturbance rejection performance of the closed-loop system are obtained by solving some linear matrix inequalities. To illustrate the effectiveness of the proposed method, a numerical example is provided for the design of the feedback gain and the quantizer parameters.
The persistence of depression score

NARCIS (Netherlands)

Spijker, J.; de Graaf, R.; Ormel, J.; Nolen, W. A.; Grobbee, D. E.; Burger, H.

2006-01-01

Objective: To construct a score that allows prediction of major depressive episode (MDE) persistence in individuals with MDE using determinants of persistence identified in previous research. Method: Data were derived from 250 subjects from the general population with new MDE according to DSM-III-R.
Drought Persistence Errors in Global Climate Models

Science.gov (United States)

Moon, H.; Gudmundsson, L.; Seneviratne, S. I.

2018-04-01

The persistence of drought events largely determines the severity of socioeconomic and ecological impacts, but the capability of current global climate models (GCMs) to simulate such events is subject to large uncertainties. In this study, the representation of drought persistence in GCMs is assessed by comparing state-of-the-art GCM model simulations to observation-based data sets. For doing so, we consider dry-to-dry transition probabilities at monthly and annual scales as estimates for drought persistence, where a dry status is defined as negative precipitation anomaly. Though there is a substantial spread in the drought persistence bias, most of the simulations show systematic underestimation of drought persistence at global scale. Subsequently, we analyzed to which degree (i) inaccurate observations, (ii) differences among models, (iii) internal climate variability, and (iv) uncertainty of the employed statistical methods contribute to the spread in drought persistence errors using an analysis of variance approach. The results show that at monthly scale, model uncertainty and observational uncertainty dominate, while the contribution from internal variability is small in most cases. At annual scale, the spread of the drought persistence error is dominated by the statistical estimation error of drought persistence, indicating that the partitioning of the error is impaired by the limited number of considered time steps. These findings reveal systematic errors in the representation of drought persistence in current GCMs and suggest directions for further model improvement.
Stochastic convergence of persistence landscapes and silhouettes

Directory of Open Access Journals (Sweden)

Frédéric Chazal

2015-03-01

Full Text Available Persistent homology is a widely used tool in Topological Data Analysis that encodes multi-scale topological information as a multiset of points in the plane called a persistence diagram. It is difficult to apply statistical theory directly to a random sample of diagrams. Instead, we summarize persistent homology with a persistence landscape, introduced by Bubenik, which converts a diagram into a well-behaved real-valued function. We investigate the statistical properties of landscapes, such as weak convergence of the average landscapes and convergence of the bootstrap. In addition, we introduce an alternate functional summary of persistent homology, which we call the silhouette, and derive an analogous statistical theory.
Missed diagnosis-persistent delirium

Directory of Open Access Journals (Sweden)

Aseem Mehra

2014-01-01

Full Text Available Delirium is in general considered as an acute short lasting reversible neuropsychiatric syndrome. However, there is some evidence to suggest that in a small proportion of cases delirium may be a chronic or persistent condition. However, making this diagnosis requires clinical suspicion and ruling other differential diagnosis. In this report, we present a case of a 55-year-old man who had cognitive symptoms, psychotic symptoms and depressive symptoms along with persistent hypokalemia and glucose intolerance. He was seen by 3 psychiatrists with these symptoms and was initially diagnosed as having depressive disorder and later diagnosis of bipolar affective disorder (current episode mania, and psychosis were considered by the third psychiatrist. However, despite the presence of persistent neurocognitive deficits, evening worsening of symptoms, hypokalemia and glucose intolerance diagnosis of delirium was not suspected.
Bacterial persistence

Indian Academy of Sciences (India)

PRAKASH KUMAR

Drug indifference versus persistence. Studies on the mode of ... is a special case of drug indifference, restricted to a small ... to his model (outlined in detail in Lewis 2008), treatment .... belong to the heat and cold shock response family; many.
Ranking of persister genes in the same Escherichia coli genetic background demonstrates varying importance of individual persister genes in tolerance to different antibiotics

Directory of Open Access Journals (Sweden)

Nan eWu

2015-09-01

Full Text Available Despite the identification of many genes and pathways involved in the persistence phenomenon of bacteria, the relative importance of these genes in a single organism remains unclear. Here, using Escherichia coli as a model, we generated mutants of 21 known candidate persister genes and compared the relative importance of these mutants in persistence to various antibiotics (ampicillin, gentamicin, norfloxacin, and trimethoprim at different times. We found that oxyR, dnaK, sucB, relA, rpoS, clpB, mqsR, and recA were prominent persister genes involved in persistence to multiple antibiotics. These genes map to the following pathways: antioxidative defense pathway (oxyR, global regulators (dnaK, clpB, and rpoS, energy production (sucB, stringent response (relA, toxin–antitoxin (TA module (mqsR, and SOS response (recA. Among the TA modules, the ranking order was mqsR, lon, relE, tisAB, hipA, and dinJ. Intriguingly, rpoS deletion caused a defect in persistence to gentamicin but increased persistence to ampicillin and norfloxacin. Mutants demonstrated dramatic differences in persistence to different antibiotics at different time points: some mutants (oxyR, dnaK, phoU, lon, recA, mqsR, and tisAB displayed defect in persistence from early time points, while other mutants (relE, smpB, glpD, umuD, and tnaA showed defect only at later time points. These results indicate that varying hierarchy and importance of persister genes exist and that persister genes can be divided into those involved in shallow persistence and those involved in deep persistence. Our findings suggest that the persistence phenomenon is a dynamic process with different persister genes playing roles of variable significance at different times. These findings have implications for improved understanding of persistence phenomenon and developing new drugs targeting persisters for more effective cure of persistent infections.
Linear waves and stability in ideal magnetohydrodynamics

International Nuclear Information System (INIS)

Eckhoff, K.S.

1987-05-01

Linear waves superimposed on an arbitrary basic state in ideal magnetohydrodynamics are studied by an asymptotic expansion valid for short wavelenghts. The theory allows for a gravitational potential, and it may therefore be applied both in astrophysics and in problems related to thermonuclear fusion. The linearized equations for the perturbations of the basic state are found in the form of a symmetric hyperbolic system. This symmetric hyperbolic system is shown to possess characteristics of nonuniform multiplicity, which implies that waves of different types may interact. In particular it is shown that the mass waves, the Alf-n waves, and the slow magnetoacoustic waves will persistently interact in the exceptional case where the local wave number vector is perpendicular to the magnetic field. The equations describing this interaction are found in the form of a weakly coupled hyperbolic system. This weakly coupled hyperbloc system is studied in a number of special cases, and detailed analytic results are obtained for some such cases. The results show that the interaction of the waves may be one of the major causes of instability of the basic state. It seems beyond doubt that the interacting waves contain the physically relevant parts of the waves, which often are referred to as ballooning modes, including Suydam modes and Mercier modes
How to decode Unemployment Persistence: An econometric framework for identifying and comparing the sources of persistence

DEFF Research Database (Denmark)

Møller, Niels Framroze

2016-01-01

Most econometric analyses of persistence focus on the existence of non-stationary unemployment but not the origin of this. The present research contains a multivariate econometric framework for identifying and comparing different sources of unemployment persistence (e.g. hysteresis versus a slowly...... moving equilibrium rate). A small example, considering historical data (1988-2006) for the UK, demonstrates how the method can be applied in practice. Although this primarily serves as an illustration, the evidence clearly suggests that persistence was due to a slowly moving equilibrium (driven...
Observational evidence for the impact of jet condensation trails upon the earths radiation budget

Energy Technology Data Exchange (ETDEWEB)

Meinert, D. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

1997-12-31

Jet condensation trails have been classified in AVHRR images from a couple of month. It was tried to estimate their impact upon the radiation budget from the observed radiances. This has been performed by direct comparison of contrail image points to neighboring image points, assuming a slowly varying background. The classification method, basing on an artificial neural network for pattern recognition is explained. The details of the estimation of the net impact of contrails upon the radiation budget are shown by one example. (author) 5 refs.
Observational evidence for the impact of jet condensation trails upon the earths radiation budget

Energy Technology Data Exchange (ETDEWEB)

Meinert, D [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

1998-12-31

Jet condensation trails have been classified in AVHRR images from a couple of month. It was tried to estimate their impact upon the radiation budget from the observed radiances. This has been performed by direct comparison of contrail image points to neighboring image points, assuming a slowly varying background. The classification method, basing on an artificial neural network for pattern recognition is explained. The details of the estimation of the net impact of contrails upon the radiation budget are shown by one example. (author) 5 refs.
Persistence of Women in Online Degree-Completion Programs

Directory of Open Access Journals (Sweden)

Terry Müller

2008-06-01

Full Text Available Although online courses at postsecondary institutions promise adults access, flexibility, and convenience, many barriers to online learning remain. This article presents findings from a qualitative case study, which explored the phenomenon of undergraduate and graduate women learners’ persistence in online degree-completion programs at a college in the Northeast of the United States. Research questions asked why women learners persisted or failed to persist, and how factors supporting or hindering persistence influenced learners. Interviews with a purposeful sample of 20 participants revealed the complexity of variables affecting learners’ persistence to graduation. Findings suggested that multiple responsibilities, insufficient interaction with faculty, technology, and coursework ranked highest as barriers to women’s persistence. Strong motivation to complete degrees, engagement in the learning community, and appreciation for the convenience of an online degree-completion option facilitated persistence.
Gasoline on hands: preliminary study on collection and persistence.

Science.gov (United States)

Darrer, Melinda; Jacquemet-Papilloud, Joëlle; Delémont, Olivier

2008-03-05

The identification of an arsonist remains one of the most difficult challenges a fire investigation has to face. Seeking and detection of traces of gasoline could provide a valuable information to link a suspect with an arson scene where gasoline was used to set-up the fire. In this perspective, a first study was undertaken to evaluate a simple, fast and efficient method for collecting gasoline from hands, and to assess its persistence over time. Four collection means were tested: PVC, PE and Latex gloves, as well as humidified filter paper. A statistical assessment of the results indicates that Latex and PVC gloves worn for about 20 min, as well as paper filter rubbed on hands, allow an efficient collection of gasoline applied to hands. Due to ease of manipulation and to a reduced amount of volatile compounds detected from the matrix, PVC gloves were selected for the second set of experiments. The evaluation of the persistence of gasoline on hands was then carried out using two initial quantities (500 and 1000 microl). Collection was made with PVC gloves after 0, 30 min, 1, 2 and 4h, on different volunteers. The results show a common tendency of massive evaporation of gasoline during the first 30 min: a continued but non-linear decrease was observed along different time intervals. The results of this preliminary study are in agreement with other previous researches conducted on the detection of flammable liquid residues on clothes, shoes and skin.
Laboratory diagnosis of persistent human chlamydial infection

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Mirja ePuolakkainen

2013-12-01

Full Text Available Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data.
Exploring Non-Traditional Adult Undergraduate Student Persistence and Non-Persistence in Higher Education: A Stress and Coping Model Approach

Science.gov (United States)

Maroney, Barbara R.

2010-01-01

This study explores persistence and non-persistence among adult undergraduate students with particular focus on these students' lives, their stressors, their coping resources including academic supports, and their styles of coping. The study approaches the issue of non-persistence not as a personal failure but rather as a consequence of multiple…
Persistent insomnia is associated with mortality risk.

Science.gov (United States)

Parthasarathy, Sairam; Vasquez, Monica M; Halonen, Marilyn; Bootzin, Richard; Quan, Stuart F; Martinez, Fernando D; Guerra, Stefano

2015-03-01

Insomnia has been associated with mortality risk, but whether this association is different in subjects with persistent vs intermittent insomnia is unclear. Additionally, the role of systemic inflammation in such an association is unknown. We used data from a community-based cohort to determine whether persistent or intermittent insomnia, defined based on persistence of symptoms over a 6-year period, was associated with death during the following 20 years of follow-up. We also determined whether changes in serum C-reactive protein (CRP) levels measured over 2 decades between study initiation and insomnia determination were different for the persistent, intermittent, and never insomnia groups. The results were adjusted for confounders such as age, sex, body mass index, smoking, physical activity, alcohol, and sedatives. Of the 1409 adult participants, 249 (18%) had intermittent and 128 (9%) had persistent insomnia. During a 20-year follow-up period, 318 participants died (118 due to cardiopulmonary disease). In adjusted Cox proportional-hazards models, participants with persistent insomnia (adjusted hazards ratio [HR] 1.58; 95% confidence interval [CI], 1.02-2.45) but not intermittent insomnia (HR 1.22; 95% CI, 0.86-1.74) were more likely to die than participants without insomnia. Serum CRP levels were higher and increased at a steeper rate in subjects with persistent insomnia as compared with intermittent (P = .04) or never (P = .004) insomnia. Although CRP levels were themselves associated with increased mortality (adjusted HR 1.36; 95% CI, 1.01-1.82; P = .04), adjustment for CRP levels did not notably change the association between persistent insomnia and mortality. In a population-based cohort, persistent, and not intermittent, insomnia was associated with increased risk for all-cause and cardiopulmonary mortality and was associated with a steeper increase in inflammation. Copyright © 2015 Elsevier Inc. All rights reserved.
MOOCs and Persistence: Definitions and Predictors

Science.gov (United States)

Evans, Brent J.; Baker, Rachel B.

2016-01-01

The chapter argues for redefining the term "persistence" as it relates to MOOCs and considers how different measures produce different results in the research; it closes with a review of research on persistence in MOOCs.
Students' Persistence and Academic Success in a First-Year Professional Bachelor Program: The Influence of Students' Learning Strategies and Academic Motivation

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Gert Vanthournout

2012-01-01

Full Text Available The present study explores whether students' learning strategies and academic motivation predict persistence and academic success in the first year of higher education. Freshmen students in a professional bachelor program in teacher education were questioned on their learning strategy use and motivation at the start and at the end of the academic year. Students' learning strategies were assessed using the inventory of learning styles-SV. Motivation was measured using scales from the self-regulation questionnaire and the academic motivation scale. Gender and students' prior education were incorporated as control variables. Logistic regression analyses and general linear modelling were applied to predict persistence and academic success, respectively. In each case a stepwise approach in data analysis was used. Results on persistence indicate that lack of regulation and amotivation at the start of the year are significant predictors. For academic success, results showed that relating and structuring, lack of regulation, and lack of motivation at the end of the year are meaningful predictors. Overall, our study demonstrates that learning strategies and motivation have a moderate explanatory value regarding academic success and persistence, and that these effects remain even after controlling for the influence of background variables.
Linear versus non-linear supersymmetry, in general

Energy Technology Data Exchange (ETDEWEB)

Ferrara, Sergio [Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); INFN - Laboratori Nazionali di Frascati,Via Enrico Fermi 40, I-00044 Frascati (Italy); Department of Physics and Astronomy, UniversityC.L.A.,Los Angeles, CA 90095-1547 (United States); Kallosh, Renata [SITP and Department of Physics, Stanford University,Stanford, California 94305 (United States); Proeyen, Antoine Van [Institute for Theoretical Physics, Katholieke Universiteit Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Wrase, Timm [Institute for Theoretical Physics, Technische Universität Wien,Wiedner Hauptstr. 8-10, A-1040 Vienna (Austria)

2016-04-12

We study superconformal and supergravity models with constrained superfields. The underlying version of such models with all unconstrained superfields and linearly realized supersymmetry is presented here, in addition to the physical multiplets there are Lagrange multiplier (LM) superfields. Once the equations of motion for the LM superfields are solved, some of the physical superfields become constrained. The linear supersymmetry of the original models becomes non-linearly realized, its exact form can be deduced from the original linear supersymmetry. Known examples of constrained superfields are shown to require the following LM’s: chiral superfields, linear superfields, general complex superfields, some of them are multiplets with a spin.
Linear versus non-linear supersymmetry, in general

International Nuclear Information System (INIS)

Ferrara, Sergio; Kallosh, Renata; Proeyen, Antoine Van; Wrase, Timm

2016-01-01

We study superconformal and supergravity models with constrained superfields. The underlying version of such models with all unconstrained superfields and linearly realized supersymmetry is presented here, in addition to the physical multiplets there are Lagrange multiplier (LM) superfields. Once the equations of motion for the LM superfields are solved, some of the physical superfields become constrained. The linear supersymmetry of the original models becomes non-linearly realized, its exact form can be deduced from the original linear supersymmetry. Known examples of constrained superfields are shown to require the following LM’s: chiral superfields, linear superfields, general complex superfields, some of them are multiplets with a spin.

Habit persistence

DEFF Research Database (Denmark)

Vinther Møller, Stig

2009-01-01

This paper uses an iterated GMM approach to estimate and test the consumption based habit persistence model of Campbell and Cochrane (1999) on the US stock market. The empirical evidence shows that the model is able to explain the size premium, but fails to explain the value premium. Further...
High blood levels of persistent organic pollutants are statistically correlated with smoking

DEFF Research Database (Denmark)

Deutch, Bente; Hansen, Jens C.

1999-01-01

, smoking and intake of traditional Inuit food. Multiple linear regression analyses showed highly significant positive associations between the mothers' smoking status (never, previous, present) and plasma concentrations of all the studied organic pollutants both in maternal blood and umbilical cord blood......Persistent Organic Pollutants (11 pesticides and 14 PCB-congeners), and heavy metals (Cd, Cu, Hg, Pb, Se, and Zn) were determined in 175 pregnant women and 160 newborn infants (umbilical cord blood) from Disko Bay, Greenland, 1994-96. Among these, 135 women filled out questionnaires about drinking....... Traditional food and not the tobacco is known to be the source of the contaminants. But smoking may influence the enzymatic turnover of toxic substances....
Non-Linear Dynamics of Saturn’s Rings

Science.gov (United States)

Esposito, Larry W.

2015-11-01

Non-linear processes can explain why Saturn’s rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states.Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit.Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like ‘straw’ that can explain the halo structure and spectroscopy: This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn’s rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects
Emission metrics for quantifying regional climate impacts of aviation

Directory of Open Access Journals (Sweden)

M. T. Lund

2017-07-01

Full Text Available This study examines the impacts of emissions from aviation in six source regions on global and regional temperatures. We consider the NOx-induced impacts on ozone and methane, aerosols and contrail-cirrus formation and calculate the global and regional emission metrics global warming potential (GWP, global temperature change potential (GTP and absolute regional temperature change potential (ARTP. The GWPs and GTPs vary by a factor of 2–4 between source regions. We find the highest aviation aerosol metric values for South Asian emissions, while contrail-cirrus metrics are higher for Europe and North America, where contrail formation is prevalent, and South America plus Africa, where the optical depth is large once contrails form. The ARTP illustrate important differences in the latitudinal patterns of radiative forcing (RF and temperature response: the temperature response in a given latitude band can be considerably stronger than suggested by the RF in that band, also emphasizing the importance of large-scale circulation impacts. To place our metrics in context, we quantify temperature change in four broad latitude bands following 1 year of emissions from present-day aviation, including CO2. Aviation over North America and Europe causes the largest net warming impact in all latitude bands, reflecting the higher air traffic activity in these regions. Contrail cirrus gives the largest warming contribution in the short term, but remain important at about 15 % of the CO2 impact in several regions even after 100 years. Our results also illustrate both the short- and long-term impacts of CO2: while CO2 becomes dominant on longer timescales, it also gives a notable warming contribution already 20 years after the emission. Our emission metrics can be further used to estimate regional temperature change under alternative aviation emission scenarios. A first evaluation of the ARTP in the context of aviation suggests that further work to account
Persistent gravity wave coupling from the stratosphere to the MLT versus secondary wave generation in Antarctica

Science.gov (United States)

Zhao, J.; Geraghty, I.; Chu, X.; Vadas, S.; Becker, E.; Harvey, V. L.; Jones, R. M.; Chen, C.; Lu, X.

2017-12-01

After Antarctic persistent gravity waves (GWs) in the Mesosphere and Lower Thermosphere (MLT) were discovered from lidar observations [Chen et al., 2013, 2016], secondary wave generation theory was proposed to explain the source. Here we perform a source investigation of such persistent GWs through analyzing both stratospheric and MLT GWs at McMurdo using temperature measurements (30 - 50 km, year 2011 - 2015) obtained by Fe Boltzmann lidar. In the stratosphere, GW vertical wavelengths (λ) and periods exhibit seasonal cycles with winter maxima and summer minima, which linearly correlated with mean zonal wind velocities. GWs dissipate more in winter than in summer due to larger wave amplitudes. The potential energy density (Ep) are anti-correlated with wind rotation angles but positively correlated with surface and stratospheric winds. Critical level filtering, in-situ generation of GWs, and wave saturation changes play roles in Ep seasonal variations (winter maxima and summer minima). The large increase of Ep from summer to winter possibly results from the decrease in critical level filtering. The gradual variations of Ep from Mar to Oct are likely related both to the increased λ towards winter, allowing larger wave amplitudes before saturation, and to in-situ GW generation via geostrophic adjustment, secondary GW generation. Large Ep occur when McMurdo is inside the jet stream core 5-24º poleward from vortex edge. In winter MLT, the persistent GWs cause larger temperature perturbations (± 30 K, compared to ± 10 K in the stratosphere) with longer λ (23.5 km) and larger vertical phase speeds (1.8 m/s). More waves (95.4%) show downward phase progression compared to the stratospheric GWs (70.4%). Since the inferred horizontal wavelength of stratospheric GWs (350 - 450 km) are much shorter than those of the persistent GWs in the MLT (1000 - 2000 km), the dominant stratospheric GWs are not the direct source of the MLT persistent GWs. Secondary wave generation
Bronchodilator Response in Patients with Persistent Allergic Asthma Could Not Predict Airway Hyperresponsiveness

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Petanjek Bojana B

2007-12-01

Full Text Available Anticholinergics, or specific antimuscarinic agents, by inhibition of muscarinic receptors cause bronchodilatation, which might correlate with activation of these receptors by the muscarinic agonist methacholine. The aim of this study was to determine whether a positive bronchodilator response to the anticholinergic ipratropium bromide could predict airway hyperresponsiveness in patients with persistent allergic asthma. The study comprised 40 patients with mild and moderate persistent allergic asthma. Diagnosis was established by clinical and functional follow-up (skin-prick test, spirometry, bronchodilator tests with salbutamol and ipratropium bromide, and methacholine challenge testing. The bronchodilator response was positive to both bronchodilator drugs in all patients. After salbutamol inhalation, forced expiratory volume in 1 second (FEV1 increased by 18.39 ± 6.18%, p 1 increased by 19.14 ± 6.74%, p 1 decreased by 25.75 ± 5.16%, p 20 FEV1 [provocative concentration of methacholine that results in a 20% fall in FEV1] from 0.026 to 1.914 mg/mL. Using linear regression, between methacholine challenge testing and bronchodilator response to salbutamol, a positive, weak, and stastistically significant correlation for FEV1 was found (p
Foundations of linear and generalized linear models

CERN Document Server

Agresti, Alan

2015-01-01

A valuable overview of the most important ideas and results in statistical analysis Written by a highly-experienced author, Foundations of Linear and Generalized Linear Models is a clear and comprehensive guide to the key concepts and results of linear statistical models. The book presents a broad, in-depth overview of the most commonly used statistical models by discussing the theory underlying the models, R software applications, and examples with crafted models to elucidate key ideas and promote practical model building. The book begins by illustrating the fundamentals of linear models,
DNA-crosslinker cisplatin eradicates bacterial persister cells.

Science.gov (United States)

Chowdhury, Nityananda; Wood, Thammajun L; Martínez-Vázquez, Mariano; García-Contreras, Rodolfo; Wood, Thomas K

2016-09-01

For all bacteria, nearly every antimicrobial fails since a subpopulation of the bacteria enter a dormant state known as persistence, in which the antimicrobials are rendered ineffective due to the lack of metabolism. This tolerance to antibiotics makes microbial infections the leading cause of death worldwide and makes treating chronic infections, including those of wounds problematic. Here, we show that the FDA-approved anti-cancer drug cisplatin [cis-diamminodichloroplatinum(II)], which mainly forms intra-strand DNA crosslinks, eradicates Escherichia coli K-12 persister cells through a growth-independent mechanism. Additionally, cisplatin is more effective at killing Pseudomonas aeruginosa persister cells than mitomycin C, which forms inter-strand DNA crosslinks, and cisplatin eradicates the persister cells of several pathogens including enterohemorrhagic E. coli, Staphylococcus aureus, and P. aeruginosa. Cisplatin was also highly effective against clinical isolates of S. aureus and P. aeruginosa. Therefore, cisplatin has broad spectrum activity against persister cells. Biotechnol. Bioeng. 2016;113: 1984-1992. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
On persistence interfaces for scientific data stores

International Nuclear Information System (INIS)

Malon, D.M.; May, E.N.

1996-01-01

A common dilemma among builders of large scientific data stores is whether to use a lightweight object persistence manager or a genuine object-oriented database. There are often good reasons to consider each of these strategies; a few are described in this paper. Too often, however, electing to use a lightweight approach has meant programming to an interface that is entirely different than that expected by commercial object-oriented databases. With the emergence of object database standards, it is possible to provide an interface to persistence managers that does not needlessly inhibit coexistence with (and, perhaps, eventual migration to) object-oriented databases. This paper describes an implementation of a substantial subset of the ODMG-93[1]C++ specification that allows clients to use many of today's lightweight object persistence managers through an interface that conforms to the ODMG standard. We also describe a minimal interface that persistence software should support in order to provide persistence services for ODMG implementations
Persistence of stapedial artery: a case report

International Nuclear Information System (INIS)

Carvalho, Bruna Vilaca de; Gaiotti, Juliana Oggioni; Diniz, Renata Lopes Furletti Caldeira; Ribeiro, Marcelo Almeida; Motta, Emilia Guerra Pinto Coelho; Moreira, Wanderval

2013-01-01

Persistent stapedial artery is a rare congenital anomaly that occurs by a failure in the involution of such artery. Most patients with persistent stapedial artery are asymptomatic. The imaging diagnosis is made principally by means of multidetector computed tomography. In the present case, persistent stapedial artery was an incidental computed tomography finding. The authors discuss the embryogenesis, computed tomography findings and the importance of an early diagnosis of such anomaly. (author)
Teriparatide Induced Delayed Persistent Hypercalcemia

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Nirosshan Thiruchelvam

2014-01-01

Full Text Available Teriparatide, a recombinant PTH, is an anabolic treatment for osteoporosis that increases bone density. Transient hypercalcemia is a reported side effect of teriparatide that is seen few hours following administration of teriparatide and resolves usually within 16 hours of drug administration. Persistent hypercalcemia, although not observed in clinical trials, is rarely reported. The current case describes a rare complication of teriparatide induced delayed persistent hypercalcemia.
On the linear programming bound for linear Lee codes.

Science.gov (United States)

Astola, Helena; Tabus, Ioan

2016-01-01

Based on an invariance-type property of the Lee-compositions of a linear Lee code, additional equality constraints can be introduced to the linear programming problem of linear Lee codes. In this paper, we formulate this property in terms of an action of the multiplicative group of the field [Formula: see text] on the set of Lee-compositions. We show some useful properties of certain sums of Lee-numbers, which are the eigenvalues of the Lee association scheme, appearing in the linear programming problem of linear Lee codes. Using the additional equality constraints, we formulate the linear programming problem of linear Lee codes in a very compact form, leading to a fast execution, which allows to efficiently compute the bounds for large parameter values of the linear codes.
Low-Grade Persistent Hyperparathyroidism After Pediatric Renal Transplant.

Science.gov (United States)

Gulleroglu, Kaan; Baskin, Esra; Moray, Gokhan; Haberal, Mehmet

2016-06-01

Hyperparathyroidism, a frequent complication of chronic kidney disease, persists after renal transplant. Our aims were to examine the status of parathyroid hormone levels and to determine the clinical and biochemical risk factors of persistent hyperparathyroidism after transplant. Our study included 44 pediatric renal transplant recipients with stable graft function. Median follow-up after transplant was 17.5 months (range, 12-126 mo). Patients did not receive routine vitamin D or calcium supplements after transplant, and none had undergone previous parathyroidectomy. Bone mineral densitometry of the lumbar spine was measured. Fifteen patients (34%) had parathyroid hormone levels greater than 70 pg/mL (normal range, 10-70 pg/mL). Duration of dialysis before transplant was longer in patients with persistent hyperparathyroidism. Mean serum bicarbonate levels were significantly lower in patients with persistent hyperparathyroidism than in patients without persistent hyperparathyroidism after transplant. A significant negative correlation was noted between parathyroid hormone level and serum bicarbonate level. Another significant negative correlation was shown between parathyroid hormone level and z score. We found that persistent hyperparathyroidism is related to longer dialysis duration, lower serum bicarbonate level, and lower z score. Pretransplant dialysis duration is an important predictor of persistent hyperparathyroidism. Early identification of factors that contribute to persistent hyperparathyroidism after transplant could lead to treatment strategies to minimize or prevent its detrimental effects on bone health and growth in pediatric transplant recipients.
Fundamental bound on the persistence and capacity of short-term memory stored as graded persistent activity.

Science.gov (United States)

Koyluoglu, Onur Ozan; Pertzov, Yoni; Manohar, Sanjay; Husain, Masud; Fiete, Ila R

2017-09-07

It is widely believed that persistent neural activity underlies short-term memory. Yet, as we show, the degradation of information stored directly in such networks behaves differently from human short-term memory performance. We build a more general framework where memory is viewed as a problem of passing information through noisy channels whose degradation characteristics resemble those of persistent activity networks. If the brain first encoded the information appropriately before passing the information into such networks, the information can be stored substantially more faithfully. Within this framework, we derive a fundamental lower-bound on recall precision, which declines with storage duration and number of stored items. We show that human performance, though inconsistent with models involving direct (uncoded) storage in persistent activity networks, can be well-fit by the theoretical bound. This finding is consistent with the view that if the brain stores information in patterns of persistent activity, it might use codes that minimize the effects of noise, motivating the search for such codes in the brain.
Novel protocol for persister cells isolation.

Directory of Open Access Journals (Sweden)

Silvia J Cañas-Duarte

Full Text Available Bacterial persistence, where a fraction of a population presents a transient resistance to bactericidal substances, has great medical importance due to its relation with the appearance of antibiotic resistances and untreatable bacterial chronic infections. The mechanisms behind this phenomenon remain largely unknown in spite of recent advances, in great part because of the difficulty in isolating the very small fraction of the population that is in this state at any given time. Current protocols for persister isolation have resulted in possible biases because of the induction of this state by the protocol itself. Here we present a novel protocol that allows rapid isolation of persister cells both from exponential and stationary phase. Moreover, it is capable of differentiating between type I and type II persister cells, which should allow the field to move beyond its current state of studying only one type. While this protocol prompts a revision of many of the current results, it should greatly facilitate further advances in the field.
Herbicide Persistence in Seawater Simulation Experiments.

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Philip Mercurio

Full Text Available Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR. The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities. Very little degradation was recorded over the standard 60 d period (Experiment 1 so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated
Herbicide Persistence in Seawater Simulation Experiments

Science.gov (United States)

Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P.

2015-01-01

Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes
Linear algebra

CERN Document Server

Shilov, Georgi E

1977-01-01

Covers determinants, linear spaces, systems of linear equations, linear functions of a vector argument, coordinate transformations, the canonical form of the matrix of a linear operator, bilinear and quadratic forms, Euclidean spaces, unitary spaces, quadratic forms in Euclidean and unitary spaces, finite-dimensional space. Problems with hints and answers.
Performance Persistence of Equity Funds in Hungary

Directory of Open Access Journals (Sweden)

Dariusz Filip

2011-03-01

Full Text Available This study examines the phenomenon of performance persistence of equity funds in Hungary in two time perspectives: 1-year and 6-month perspectives. The empirical results confirm the occurrence of performance dependence in consecutive periods. There is also a strong evidence of short-term persistence in the total horizon of the study (from the beginning of 2000 to the end of 2009, and in several sub-periods. The 1-year persistence was also found in the tested sample and, in general, depended on the measure applied. Furthermore, I observed performance reversal, which can be partly explained by trend changes in the financial markets. The persistence of equity funds performance in Hungary is shaped by market factors rather than the diversity of managerial characteristics.
Persistent agents in Axelrod's social dynamics model

Science.gov (United States)

Reia, Sandro M.; Neves, Ubiraci P. C.

2016-01-01

Axelrod's model of social dynamics has been studied under the effect of external media. Here we study the formation of cultural domains in the model by introducing persistent agents. These are agents whose cultural traits are not allowed to change but may be spread through local neighborhood. In the absence of persistent agents, the system is known to present a transition from a monocultural to a multicultural regime at some critical Q (number of traits). Our results reveal a dependence of critical Q on the occupation probability p of persistent agents and we obtain the phase diagram of the model in the (p,Q) -plane. The critical locus is explained by the competition of two opposite forces named here barrier and bonding effects. Such forces are verified to be caused by non-persistent agents which adhere (adherent agents) to the set of traits of persistent ones. The adherence (concentration of adherent agents) as a function of p is found to decay for constant Q. Furthermore, adherence as a function of Q is found to decay as a power law with constant p.

Application of Wilmink’s Exponential Function in Genetic Analysis of 305-d Milk Production and Lactation Persistency in Holstein Cows of Razavi Khorasan

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R Izadkhah

2012-02-01

Full Text Available To estimate heritability and genetic trend for 305-d milk production and lactation persistency, a total of 130,668 monthly test day milk yields belonging to 15,183 first lactation Holstein cows in 131 herds and calved from 2000 to 2009 were used. To calculate 305-d milk yield as well as lactation persistency, estimated parameters of Wilmink’s exponential function were applied. The parameters of the function were estimated by SAS software. Genetic and environmental variance components and heritability of the traits were estimated by single trait animal model using DMU software. Genetic trend was estimated based upon weighted simple linear regression of average breeding values on calving year. Heritability estimate of 305-d milk yield and lactation persistency were found to be 0.184 and 0.05, respectively. A positive significant phenotypic trend (166.11 kg per year was observed for 305-d milk yield while a non-significant genetic trend (-2.0107 was revealed for the trait. For the lactation persistency, there were no significant phenotypic (0.054 % per year and genetic (0.003 % per year trends over the period of time.
Persistence in the Cryptocurrency Market

OpenAIRE

Caporale, Guglielmo Maria; Gil-Alaña, Luis A.; Plastun, Alex

2017-01-01

This paper examines persistence in the cryptocurrency market. Two different long-memory methods (R/S analysis and fractional integration) are used to analyse it in the case of the four main cryptocurrencies (BitCoin, LiteCoin, Ripple, Dash) over the sample period 2013-2017. The findings indicate that this market exhibits persistence (there is a positive correlation between its past and future values), and that its degree changes over time. Such predictability represents evidence of market ine...
Treatment of acral persistent papular mucinosis with electrocoagulation.

Science.gov (United States)

André Jorge, Flávia; Mimura Cortez, Tatiana; Guadalini Mendes, Fabiana; Esther Alencar Marques, Mariângela; Amante Miot, Hélio

2011-01-01

Acral persistent papular mucinosis is a rare localized form of lichen myxedematosus with few case reports and no documented therapeutic options. To report full resolution of acral persistent papular mucinosis after electrocoagulation. Case report of a 51-year-old white female diagnosed with an acral persistent papular mucinosis. The clinical and histopathologic features, treatment provided, and response to treatment are detailed. Acral persistent papular mucinosis presented as multiple asymptomatic normochromic papules on the wrists. Treatment with topical and intralesional steroids was unsatisfactory. Gentle electrocoagulation led to complete resolution of the lesions and negligible scarring. The favorable results remained for 6 months of follow-up, and no new lesions have emerged. Our case of acral persistent papular mucinosis was successfully treated with electrocoagulation and long-lasting, excellent cosmetic results.
Long-term efficacy of linear-scanning 808 nm diode laser for hair removal compared to a scanned alexandrite laser.

Science.gov (United States)

Grunewald, Sonja; Bodendorf, Marc Oliver; Zygouris, Alexander; Simon, Jan Christoph; Paasch, Uwe

2014-01-01

Alexandrite and diode lasers are commonly used for hair removal. To date, the available spot sizes and repetition rates are defining factors in terms of penetration depth, treatment speed, and efficacy. Still, larger treatment areas and faster systems are desirable. To compare the efficacy, tolerability, and subject satisfaction of a continuously linear-scanning 808 nm diode laser with an alexandrite 755 nm laser for axillary hair removal. A total of 31 adults with skin types I-IV received 6 treatments at 4-week intervals with a 755 nm alexandrite laser (right axilla) and a continuously linear-scanning 808 nm diode laser (left axilla). Axillary hair density was assessed using a computerized hair detection system. There was a significant reduction in axillary hair after the 6th treatment (P lasers was not significant, but both were persistant at 18 months follow-up (left: hair clearance of 73.71%; right: hair clearance of 71.90%). Erythema and perifollicular edema were more common after alexandrite laser treatment, but all side effects were transient. While 62.50% of patients reported more pain in response to treatment with the new diode laser, all patients rated treatment with either laser tolerable. Treatment with either the alexandrite or the linear-scanning diode laser results in significant, comparable, persistent (at least 18 months) axillary hair reduction among individuals with skin types I-IV. © 2013 Wiley Periodicals, Inc.
Association Between Local Bipolar Voltage and Conduction Gap Along the Left Atrial Linear Ablation Lesion in Patients With Atrial Fibrillation.

Science.gov (United States)

Masuda, Masaharu; Fujita, Masashi; Iida, Osamu; Okamoto, Shin; Ishihara, Takayuki; Nanto, Kiyonori; Kanda, Takashi; Sunaga, Akihiro; Tsujimura, Takuya; Matsuda, Yasuhiro; Mano, Toshiaki

2017-08-01

A bipolar voltage reflects a thick musculature where formation of a transmural lesion may be hard to achieve. The purpose of this study was to explore the association between local bipolar voltage and conduction gap in patients with persistent atrial fibrillation (AF) who underwent atrial roof or septal linear ablation. This prospective observational study included 42 and 36 consecutive patients with persistent AF who underwent roof or septal linear ablations, respectively. After pulmonary vein isolation, left atrial linear ablations were performed, and conduction gap sites were identified and ablated after first-touch radiofrequency application. Conduction gap(s) after the first-touch roof and septal linear ablation were observed in 13 (32%) and 19 patients (53%), respectively. Roof and septal area voltages were higher in patients with conduction gap(s) than in those without (roof, 1.23 ± 0.77 vs 0.73 ± 0.42 mV, p = 0.010; septal, 0.96 ± 0.43 vs 0.54 ± 0.18 mV, p = 0.001). Trisected regional analyses revealed that the voltage was higher at the region with a conduction gap than at the region without. Complete conduction block across the roof and septal lines was not achieved in 3 (7%) and 6 patients (17%), respectively. Patients in whom a linear conduction block could not be achieved demonstrated higher ablation area voltage than those with a successful conduction block (roof, 1.91 ± 0.74 vs 0.81 ± 0.51 mV, p = 0.001; septal, 1.15 ± 0.56 vs 0.69 ± 0.31 mV, p = 0.006). In conclusion, a high regional bipolar voltage predicts failure to achieve conduction block after left atrial roof or septal linear ablation. In addition, the conduction gap was located at the preserved voltage area. Copyright © 2017 Elsevier Inc. All rights reserved.
Linear and non-linear optics of condensed matter

International Nuclear Information System (INIS)

McLean, T.P.

1977-01-01

Part I - Linear optics: 1. General introduction. 2. Frequency dependence of epsilon(ω, k vector). 3. Wave-vector dependence of epsilon(ω, k vector). 4. Tensor character of epsilon(ω, k vector). Part II - Non-linear optics: 5. Introduction. 6. A classical theory of non-linear response in one dimension. 7. The generalization to three dimensions. 8. General properties of the polarizability tensors. 9. The phase-matching condition. 10. Propagation in a non-linear dielectric. 11. Second harmonic generation. 12. Coupling of three waves. 13. Materials and their non-linearities. 14. Processes involving energy exchange with the medium. 15. Two-photon absorption. 16. Stimulated Raman effect. 17. Electro-optic effects. 18. Limitations of the approach presented here. (author)
Spatial patterns of drought persistence in East China

Science.gov (United States)

Meng, L.; Ford, T.

2017-12-01

East China has experienced a number of severe droughts in recent decades. Understanding the characteristics of droughts and their persistence will provide operational guidelines for water resource management and agricultural production. This study uses a logistic regression model to measure the probability of drought occurrence in the current season given the previous season's Standardized Precipitation Index (SPI) and Southern Oscillation Index (SOI) as well as drought persistence. Results reveal large spatial and seasonal variations in the relationship between the previous season's SPI and the drought occurrence probability in a given season. The drought persistence averaged over the entire study area for all the four seasons is approximately 34% with large variations from season to season and from region to region. The East and Northeast regions have the largest summer drought persistence ( 40%) and lowest fall drought persistence ( 28%). The spatial pattern in winter and spring drought persistence is dissimilar with stronger winter and weaker spring drought persistence in the Southwest and Northeast relative to other regions. Logistic regression analysis indicates a stronger negative relationship in summer-to-fall (or between fall drought occurrence and summer SPI) than other inter-season relationships. This study demonstrates that the impact of previous season SPI and SOI on current season drought varies substantially from region to region and from season to season. This study also shows stronger drought persistence in summer than in other seasons. In other words, the probability of fall drought occurrence is closely related to summer moisture conditions in the East China.
Persistence in the WFC3 IR Detector: Intrinsic Variability

Science.gov (United States)

Long, Knox S.; Baggett, Sylvia M.

2018-03-01

When the WFC3 IR detector is exposed to a bright source or sources, the sources can appear as afterimages in subsequent exposures, a phenomenon known as persistence. This can affect the science obtained with the IR channel. We have been involved in an effort to predict the brightness of the afterimages so that users can (at a minimum) flag the affected pixels and remove them from their analysis or (even better) subtract the afterimages from their science images to salvage the data. The ability of any model to remove afterimages depends on the degree to which persistence is the same for identical sets of exposures. We investigate possible time variability of persistence in the WFC3 detector using sets of (almost) identical visits comprised of single exposures of Omega Cen followed by a series of darks in which persistence is measured. We analyze 8 data sets, each consisting of two or three identical visits, with stimulus exposures between 49 and 1199 s, and find clear evidence of variability in several of the datasets in darks taken within 1000 s of the stimulus exposure. In most of the datasets, the difference in persistence for saturated pixels in the stimulus exposure is a power law decay; the visit with higher persistence has a higher power law amplitude. There was nothing unusual about the observing conditions preceding and during each of these visits that can explain the discrepancy in persistence levels. Variation in persistence implies that: (1) Unless and until the source of the variability is understood, any persistence model for the WFC3 array will be limited in its ability to predict persistence in a single observation, and, (2) as a consequence, users should always carefully inspect the results of any attempt to subtract persistence from WFC3 IR data based on a model prediction.
Linearity and Non-linearity of Photorefractive effect in Materials ...

African Journals Online (AJOL)

In this paper we have studied the Linearity and Non-linearity of Photorefractive effect in materials using the band transport model. For low light beam intensities the change in the refractive index is proportional to the electric field for linear optics while for non- linear optics the change in refractive index is directly proportional ...
Non-persistent pesticides removal in constructed wetlands

Science.gov (United States)

Tu, Yue; Jiang, Lei; Li, Haixiang

2018-03-01

The heavy use of non-persistent pesticides, resulting in the accumulation of environment and destroy the aquatic environment. This paper presents the research status of using CWs to treat non-persistent pesticides in water. The removal mechanisms are mainly physical deposition, chemical hydrolysis and plant absorption. Analysis of the factors that affect the removal effect are mainly the nature of pesticides, HRT, plants. Some scholars have proposed that secondary products of non-persistent pesticides may be more harmful to the environment, However, the relevant reports are scarce.
Near-Infrared Quantum Cutting Long Persistent Luminescence

OpenAIRE

Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

2016-01-01

By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called ?near-infrared quantum cutting long persistent luminescence (NQPL)?, which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr3+,Yb3+. It reveals that both the two-step energy transfer of model (I) and the one-step energy ...
Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated superconductors.

Science.gov (United States)

Hu, Tao; Liu, Yinshang; Xiao, Hong; Mu, Gang; Yang, Yi-Feng

2017-08-25

The strongly correlated electron fluids in high temperature cuprate superconductors demonstrate an anomalous linear temperature (T) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-T resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation [Formula: see text], which bridges the slope of the linear-T-dependent resistivity (dρ/dT) to the London penetration depth λ L at zero temperature among cuprate superconductor Bi 2 Sr 2 CaCu 2 O 8+δ and heavy fermion superconductors CeCoIn 5 , where μ 0 is vacuum permeability, k B is the Boltzmann constant and ħ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and heavy fermion superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient (D) approaching the quantum limit D ~ ħ/m*, where m* is the quasi-particle effective mass.
Prediction of antibody persistency from antibody titres to natalizumab

DEFF Research Database (Denmark)

Jensen, Poul Erik H; Koch-Henriksen, Nils; Sellebjerg, Finn

2012-01-01

In a subgroup of patients with multiple sclerosis natalizumab therapy causes generation of anti-natalizumab antibodies that may be transient or persistent. It is recommended to discontinue natalizumab therapy in persistently antibody-positive patients.......In a subgroup of patients with multiple sclerosis natalizumab therapy causes generation of anti-natalizumab antibodies that may be transient or persistent. It is recommended to discontinue natalizumab therapy in persistently antibody-positive patients....
Persistent Hiccups Following Stapedectomy

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Aidonis I

2010-10-01

Full Text Available Objective: We report a case of a 37 year-old man who developed persistent hiccups after elective stapedectomy. Method and Results: The diagnostic approach is discussed as well as the non-pharmacologic and pharmacologic treatments and overall management. The aim is to stress that there is a variety of potential factors that can induce hiccups perioperatively and in cases like this a step by step approach must be taken. Conclusion: Persistent hiccups are very rare following stapedectomy, control of them is crucial for the successful outcome. The trigger may be more than one factors and the good response to treatment may be due to dealing successfully with more than one thing.
Special set linear algebra and special set fuzzy linear algebra

OpenAIRE

Kandasamy, W. B. Vasantha; Smarandache, Florentin; Ilanthenral, K.

2009-01-01

The authors in this book introduce the notion of special set linear algebra and special set fuzzy Linear algebra, which is an extension of the notion set linear algebra and set fuzzy linear algebra. These concepts are best suited in the application of multi expert models and cryptology. This book has five chapters. In chapter one the basic concepts about set linear algebra is given in order to make this book a self contained one. The notion of special set linear algebra and their fuzzy analog...
Persistence and drug tolerance in pathogenic yeast

DEFF Research Database (Denmark)

Bojsen, Rasmus Kenneth; Regenberg, Birgitte; Folkesson, Sven Anders

2017-01-01

In this review, we briefly summarize the current understanding of how fungal pathogens can persist antifungal treatment without heritable resistance mutations by forming tolerant persister cells. Fungal infections tolerant to antifungal treatment have become a major medical problem. One mechanism...
Persistent and non-persistent strains of Listeria monocytogenes: A focus on growth kinetics under different temperature, salt, and pH conditions and their sensitivity to sanitizers.

Science.gov (United States)

Magalhães, R; Ferreira, V; Brandão, T R S; Palencia, R Casquete; Almeida, G; Teixeira, P

2016-08-01

This study aimed to investigate the effect of different conditions, including temperature (37 °C, 22 °C, and 4 °C), NaCl concentrations (2.5%, 4%, and 8%), and acidity (pH = 5), on the growth response of persistent and non-persistent isolates of Listeria monocytogenes. The resistance to two common sanitizers (benzalkonium chloride and hydrogen peroxide) was also investigated. A selected group of 41 persistent and non-persistent L. monocytogenes isolates recovered from three cheese processing plants during a previous longitudinal study was assembled. Average lag time was similar for persistent and non-persistent isolates grown at 37 °C, 22 °C and 4 °C but significantly shorter (p < 0.05) for persistent isolates grown at 2.5%, 4% and 8% NaCl, and at pH 5. Average growth rates were significantly higher (p < 0.05) for persistent than for non-persistent isolates when grown at 22 °C, 2.5%, 4% and 8% NaCl, and at pH 5. These results suggest that persistent strains may be better adapted to grow under stressful conditions frequently encountered in food processing environments than non-persistent strains. No relation between persistence and resistance to the tested sanitizers was found. Copyright © 2016 Elsevier Ltd. All rights reserved.
The Persistence of Mutual Fund Performance.

OpenAIRE

Grinblatt, Mark; Titman, Sheridan

1992-01-01

This paper analyzes how mutual fund performance relates to past performance. These tests are based on a multiple portfolio benchmark that was formed on the basis of securities characteristics. The authors find evidence that differences in performance between funds persist over time and that this persistence is consistent with the ability of fund managers to earn abnormal returns. Copyright 1992 by American Finance Association.
Statistical Inference for Porous Materials using Persistent Homology.

Energy Technology Data Exchange (ETDEWEB)

Moon, Chul [Univ. of Georgia, Athens, GA (United States); Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Scott A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

We propose a porous materials analysis pipeline using persistent homology. We rst compute persistent homology of binarized 3D images of sampled material subvolumes. For each image we compute sets of homology intervals, which are represented as summary graphics called persistence diagrams. We convert persistence diagrams into image vectors in order to analyze the similarity of the homology of the material images using the mature tools for image analysis. Each image is treated as a vector and we compute its principal components to extract features. We t a statistical model using the loadings of principal components to estimate material porosity, permeability, anisotropy, and tortuosity. We also propose an adaptive version of the structural similarity index (SSIM), a similarity metric for images, as a measure to determine the statistical representative elementary volumes (sREV) for persistence homology. Thus we provide a capability for making a statistical inference of the uid ow and transport properties of porous materials based on their geometry and connectivity.
Understanding mild persistent asthma in children

DEFF Research Database (Denmark)

Bisgaard, Hans; Szefler, Stanley J

2005-01-01

Limitations in asthma prevalence studies and difficulties in diagnosing pediatric asthma lead to uncertainty over the full extent of mild persistent asthma in children and adolescents. Although recent surveys have reported that the majority of pediatric patients with asthma in the United States...... and Europe have symptoms consistent with mild disease, these surveys have limitations in design. Thus, the true prevalence of mild asthma remains unknown. It is unclear whether children with mild persistent asthma progress to more severe asthma, but the risk of severe asthma exacerbations seems...... to be unrelated to the symptom severity. Clinical studies restricted to pediatric patients with mild asthma are limited, but available data do suggest substantial morbidity of mild persistent asthma in this population and support inhaled corticosteroid intervention. There is a need for further investigation...

International perspectives on retention and persistence

Directory of Open Access Journals (Sweden)

Gary Burkholder

2014-06-01

Full Text Available Access to higher education globally is increasing dramatically; attainment of tertiary degrees is a high priority, as educational attainment is associated with increased personal incomes as well as growth of the middle class in developing countries. The purpose of this essay is to briefly examine retention and persistence issues from a global perspective, review some retention strategies that have been employed at schools outside the United States, and to identify several key factors that related to retention and persistence globally, including access, infrastructure, financial consideration, and readiness for tertiary education. There exists an opportunity to utilize knowledge gained in the evolution of the higher education system in the United States to help address the problems associated with retention and persistence. DOI: 10.18870/hlrc.v4i2.208
Persistent facial pain conditions

DEFF Research Database (Denmark)

Forssell, Heli; Alstergren, Per; Bakke, Merete

2016-01-01

Persistent facial pains, especially temporomandibular disorders (TMD), are common conditions. As dentists are responsible for the treatment of most of these disorders, up-to date knowledge on the latest advances in the field is essential for successful diagnosis and management. The review covers...... TMD, and different neuropathic or putative neuropathic facial pains such as persistent idiopathic facial pain and atypical odontalgia, trigeminal neuralgia and painful posttraumatic trigeminal neuropathy. The article presents an overview of TMD pain as a biopsychosocial condition, its prevalence......, clinical features, consequences, central and peripheral mechanisms, diagnostic criteria (DC/TMD), and principles of management. For each of the neuropathic facial pain entities, the definitions, prevalence, clinical features, and diagnostics are described. The current understanding of the pathophysiology...
Persistent Structural Priming from Language Comprehension to Language Production

Science.gov (United States)

Bock, Kathryn; Dell, Gary S.; Chang, Franklin; Onishi, Kristine H.

2007-01-01

To examine the relationship between syntactic processes in language comprehension and language production, we compared structural persistence from sentence primes that speakers heard to persistence from primes that speakers produced. [Bock, J. K., & Griffin, Z. M. (2000). The persistence of structural priming: transient activation or implicit…
THE ROLE OF PERSISTENCE IN STUDENTS’ SELF-REALIZATION

Directory of Open Access Journals (Sweden)

Sergey I. Kudinov

2017-12-01

Full Text Available The paper analyzes the results of an empirical research obtained with the help of a sample of students. The research of persistence was carried out within the framework of the dispositional concept of personality traits and individuality by A. I. Krupnov. The techniques developed by A. I. Krupnov as well as the author’s test of persistence were used in the study. After allocating the levels of persistence, the features of self-realization were analyzed in each group of the respondents. The specificity of self-realization was revealed in the context of the author’s polysystemic concept, the author’s multidimensional questionnaire on personality’s self-realization (MQPSR was used as a diagnostic tool. The empirical study revealed statistically significant differences in the specifics of self-realization of the students with different levels of persistence manifestation. The respondents with a high level of persistence realize themselves more successfully in different spheres of life due to the obvious active behaviour, optimistic attitude, high motivation, creative methods and techniques of self-expression, internal self-regulation and constructive behavior. The students with low persistence lack successful self-realization because of passivity, pessimism, external locus of self-control, a high level of barriers and standard simple schemes of self-expression.
Lesion-to-ventricle distance and other risk factors for the persistence of newly formed black holes in relapsing-remitting multiple sclerosis.

Science.gov (United States)

Papadopoulou, Athina; Menegola, Milena; Kuhle, Jens; Ramagopalan, Sreeram V; D'Souza, Marcus; Sprenger, Till; Radue, Ernst-Wilhelm; Kappos, Ludwig; Yaldizli, Özgür

2014-03-01

Progenitor cells from the subventricular zone (SVZ) of the lateral ventricles are assumed to contribute to remyelination and resolution of black holes (BHs) in multiple sclerosis (MS). This process may depend on the distance between the lesion and the SVZ. The objective of this paper is to investigate the relationship between lesion-to-ventricle (LV) distance and persistence of new BHs. We analysed the magnetic resonance images (MRIs) of 289 relapsing-remitting (RR) MS patients, obtained during a multi-centre, placebo-controlled phase II trial over one year. Overall, 112/289 patients showed 367 new BHs at the beginning of the trial. Of these, 225 were located in 94/112 patients at the level of the lateral ventricles on axial MRIs and included in this analysis. In total, 86/225 (38%) BHs persisted at month 12. LV distance in persistent BHs (PBHs) was not longer than in transient BHs. In fact PBHs tended to be closer to the SVZ than transient BHs. A generalised linear mixed multivariate model adjusted for BHs clustered within a patient and including patient- as well as lesion-specific factors revealed size, ring contrast enhancement, and shorter LV distance as independent predictors for BH persistence. Location of BHs close to the lateral ventricles does not appear to favourably influence the resolution of new BHs in RRMS.
Linear Algebraic Method for Non-Linear Map Analysis

International Nuclear Information System (INIS)

Yu, L.; Nash, B.

2009-01-01

We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Inefficiency persistence and heterogeneity in Colombian electricity utilities

International Nuclear Information System (INIS)

Galán, Jorge E.; Pollitt, Michael G.

2014-01-01

The electricity reform in Colombia has exhibited gains in terms of reliability but its effects on firm efficiency and service quality have not been clear. Previous studies evaluating the performance of distribution companies after the reform have not found evidence of improvements, although large differences in efficiency have been found among firms. This suggests high inefficiency persistence and heterogeneity in the Colombian distribution sector. In this paper, we propose an extension of dynamic stochastic frontier models that accounts for unobserved heterogeneity in the inefficiency persistence and in the technology. The model incorporates total expenses, service quality and energy losses in an efficiency analysis of Colombian distributors over fifteen years after the reform. We identify the presence of high inefficiency persistence in the sector, and important differences between firms. In particular, rural companies and firms with small customers present low persistence and evidence the largest gains in efficiency during the period. However, increases in efficiency are only manifested during thelast five years when the main improvements in service quality and energy losses are presented. Overall, inefficiency persistence, customer density and consumption density are found to be important criteria to be considered for regulatory purposes. - Highlights: • We evaluate efficiency of Colombian electricity distributors after the reform. • We use a stochastic frontier model with dynamic effects and heterogeneity. • We find high inefficiency persistence but important differences among firms. • High persistent and low efficient firms should draw the attention of the regulator. • Recent regulation in quality has increased not only efficiency but also tariffs
Persistence among Minority STEM Majors: A Phenomenological Study

Science.gov (United States)

Williams-Watson, Stacey

The United States needs to increase the number of science, technology, engineering, and math (STEM) graduates to remain competitive in the global market and maintain national security. Minority students, specifically African-American and Hispanic, are underrepresented in STEM fields. As the minority population continues to grow it is essential that higher education institutions improve minority students' persistence in STEM education. This study examined the problem of minority students' lack of persistence in STEM programs. The purpose of this qualitative transcendental phenomenological study was to describe the lived experiences that minority students perceived as contributing to their persistence in STEM. The central research question was: What are the lived experiences of minority STEM students that have contributed to their persistence in a STEM program? The sub-questions were: a) What led participants to majors in STEM?; b) What contributed to students' success and persistence in STEM?; and c) What advice do students have to offer? The researcher interviewed 12 minority STEM students and uncovered 10 themes that described the lived experiences of minority students' persistence in STEM programs. The themes were 1) Childhood experiences and interests; 2) Positive educational experiences in secondary school; 3) Self- motivation; 4) Positive experiences with professors; 5) Family encouragement and values; 6) Lack of minorities; 7) Lack of educational preparation; 8) The need for financial assistance; 9) Clubs and organizations; and 10) Friends within the major. The significance of these findings is the potential to produce changes in curricula, programs, and retention methods that may improve the persistence of minority students in STEM programs.
Persistence of Mycoplasma genitalium following azithromycin therapy.

Directory of Open Access Journals (Sweden)

Catriona S Bradshaw

Full Text Available BACKGROUND: To determine clinical outcomes and cure rates for M.genitalium genital infection in men and women following azithromycin 1 g. METHODOLOGY: Patients attending Melbourne Sexual Health Centre between March 2005 and November 2007 with urethritis/epididymitis, cervicitis/pelvic inflammatory disease and sexual contacts of M.genitalium were tested for M.genitalium by polymerase chain reaction (PCR. M.genitalium-infection was treated with 1 g of azithromycin and a test-of-cure (toc was performed one month post-azithromycin. Response to azithromycin, and response to moxifloxacin (400 mg daily for 10 days in individuals with persistent infection post-azithromycin, was determined. PRINCIPAL FINDINGS: Of 1538 males and 313 females tested, 161 males (11% and 30 females (10% were infected with M.genitalium. A toc was available on 131 (69% infected individuals (median = 36 days [range 12-373]. Of 120 individuals prescribed azithromycin only pre-toc, M.genitalium was eradicated in 101 (84%, 95% confidence intervals [CI]: 77-90% and persisted in 19 (16%, 95% CI: 10-23%. Eleven individuals with persistent infection (9%, 95% CI: 5-15% had no risk of reinfection from untreated-partners, while eight (7%, 95% CI: 3-12% may have been at risk of reinfection from doxycycline-treated or untreated-partners. Moxifloxacin was effective in eradicating persistent infection in all cases not responding to azithromycin. Patients with persistent-M.genitalium were more likely to experience persistent symptoms (91%, compared to patients in whom M.genitalium was eradicated (17%, p<0.0001. CONCLUSION: Use of azithromycin 1 g in M.genitalium-infected patients was associated with unacceptable rates of persistent infection, which was eradicated with moxifloxacin. These findings highlight the importance of follow-up in M.genitalium-infected patients prescribed azithromycin, and the need to monitor for the development of resistance. Research to determine optimal first and
Persistence of undergraduate women in STEM fields

Science.gov (United States)

Pedone, Maggie Helene

The underrepresentation of women in science, technology, engineering, and mathematics (STEM) is a complex problem that continues to persist at the postsecondary level, particularly in computer science and engineering fields. This dissertation explored the pre-college and college level factors that influenced undergraduate women's persistence in STEM. This study also examined and compared the characteristics of undergraduate women who entered STEM fields and non-STEM fields in 2003-2004. The nationally representative Beginning Postsecondary Students Longitudinal Study (BPS:04/09) data set was used for analysis. BPS:04/09 study respondents were surveyed three times (NPSAS:04, BPS:04/06, BPS:04/09) over a six-year period, which enabled me to explore factors related to long-term persistence. Astin's Input-Environment-Output (I-E-O) model was used as the framework to examine student inputs and college environmental factors that predict female student persistence (output) in STEM. Chi-square tests revealed significant differences between undergraduate women who entered STEM and non-STEM fields in 2003-2004. Differences in student demographics, prior academic achievement, high school course-taking patterns, and student involvement in college such as participation in study groups and school clubs were found. Notably, inferential statistics showed that a significantly higher proportion of female minority students entered STEM fields than non-STEM fields. These findings challenge the myth that underrepresented female minorities are less inclined to enter STEM fields. Logistic regression analyses revealed thirteen significant predictors of persistence for undergraduate women in STEM. Findings showed that undergraduate women who were younger, more academically prepared, and academically and socially involved in college (e.g., lived on campus, interacted with faculty, participated in study groups, fine arts activities, and school sports) were more likely to persist in STEM
Examining database persistence of ISO/EN 13606 standardized electronic health record extracts: relational vs. NoSQL approaches.

Science.gov (United States)

Sánchez-de-Madariaga, Ricardo; Muñoz, Adolfo; Lozano-Rubí, Raimundo; Serrano-Balazote, Pablo; Castro, Antonio L; Moreno, Oscar; Pascual, Mario

2017-08-18

The objective of this research is to compare the relational and non-relational (NoSQL) database systems approaches in order to store, recover, query and persist standardized medical information in the form of ISO/EN 13606 normalized Electronic Health Record XML extracts, both in isolation and concurrently. NoSQL database systems have recently attracted much attention, but few studies in the literature address their direct comparison with relational databases when applied to build the persistence layer of a standardized medical information system. One relational and two NoSQL databases (one document-based and one native XML database) of three different sizes have been created in order to evaluate and compare the response times (algorithmic complexity) of six different complexity growing queries, which have been performed on them. Similar appropriate results available in the literature have also been considered. Relational and non-relational NoSQL database systems show almost linear algorithmic complexity query execution. However, they show very different linear slopes, the former being much steeper than the two latter. Document-based NoSQL databases perform better in concurrency than in isolation, and also better than relational databases in concurrency. Non-relational NoSQL databases seem to be more appropriate than standard relational SQL databases when database size is extremely high (secondary use, research applications). Document-based NoSQL databases perform in general better than native XML NoSQL databases. EHR extracts visualization and edition are also document-based tasks more appropriate to NoSQL database systems. However, the appropriate database solution much depends on each particular situation and specific problem.
Persistence of aquatic insects across managed landscapes: effects of landscape permeability on re-colonization and population recovery.

Directory of Open Access Journals (Sweden)

Nika Galic

Full Text Available Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic insects. Dispersal is often the limiting factor for successful re-colonization and recovery of stressed habitats. Therefore, in this study, we evaluated the effects of landscape permeability, assuming a combination of riparian vegetation (edge permeability and other vegetation (landscape matrix permeability, and distance between waterbodies on the colonization and recovery potential of weakly flying insects. For this purpose, we developed two models, a movement and a population model of the non-biting midge, Chironomus riparius, an aquatic insect with weak flying abilities. With the movement model we predicted the outcome of dispersal in a landscape with several linear water bodies (ditches under different assumptions regarding landscape-dependent movement. Output from the movement model constituted the probabilities of encountering another ditch and of staying in the natal ditch or perishing in the landscape matrix, and was used in the second model. With this individual-based model of midge populations, we assessed the implications for population persistence and for recovery potential after an extreme stress event. We showed that a combination of landscape attributes from the movement model determines the fate of dispersing individuals and, once extrapolated to the population level, has a big impact on the persistence and recovery of populations. Population persistence benefited from low edge permeability as it reduced the dispersal mortality which was the main factor determining population persistence and viability. However, population recovery benefited from higher edge permeability, but this was conditional on the low effective distance that ensured fewer losses in the landscape matrix. We discuss these findings with respect to possible landscape management scenarios.
Demonstration of persistent contamination of a cooked egg product production facility with Salmonella enterica serovar Tennessee and characterization of the persistent strain

DEFF Research Database (Denmark)

Jakociune, D.; Bisgaard, M.; Pedersen, Karl

2014-01-01

Aims: The aim of this study was to investigate whether continuous contamination of light pasteurized egg products with Salmonella enterica serovar Tennessee (S. Tennessee) at a large European producer of industrial egg products was caused by persistent contamination of the production facility......, members of the persistent clone were weak producers of H2S in laboratory medium. S. Tennessee isolated from the case was able to grow better in pasteurized egg product compared with other serovars investigated. Conclusions: It was concluded that the contamination was caused by a persistent strain...... in the production facility and that this strain apparently had adapted to grow in the relevant egg product. Significance and Impact of the Study: S. Tennessee has previously been associated with persistence in hatching facilities. This is the first report of persistent contamination of an egg production facility...
Childhood intermittent and persistent rhinitis prevalence and climate and vegetation: a global ecologic analysis.

Science.gov (United States)

Fuertes, Elaine; Butland, Barbara K; Ross Anderson, H; Carlsten, Chris; Strachan, David P; Brauer, Michael

2014-10-01

The effect of climate change and its effects on vegetation growth, and consequently on rhinitis, are uncertain. To examine between- and within-country associations of climate measures and the normalized difference vegetation index with intermittent and persistent rhinitis symptoms in a global context. Questionnaire data from 6- to 7-year-olds and 13- to 14-year-olds were collected in phase 3 of the International Study of Asthma and Allergies in Childhood. Associations of intermittent (>1 symptom report but not for 2 consecutive months) and persistent (symptoms for ≥2 consecutive months) rhinitis symptom prevalences with temperature, precipitation, vapor pressure, and the normalized difference vegetation index were assessed in linear mixed-effects regression models adjusted for gross national income and population density. The mean difference in prevalence per 100 children (with 95% confidence intervals [CIs]) per interquartile range increase of exposure is reported. The country-level intermittent symptom prevalence was associated with several country-level climatic measures, including the country-level mean monthly temperature (6.09 °C; 95% CI, 2.06-10.11°C per 10.4 °C), precipitation (3.10 mm; 95% CI, 0.46-5.73 mm; per 67.0 mm), and vapor pressure (6.21 hPa; 95% CI, 2.17-10.24 hPa; per 10.4 hPa) among 13- to 14-year-olds (222 center in 94 countries). The center-level persistent symptom prevalence was positively associated with several center-level climatic measures. Associations with climate were also found for the 6- to 7-year-olds (132 center in 57 countries). Several between- and within-country spatial associations between climatic factors and intermittent and persistent rhinitis symptom prevalences were observed. These results provide suggestive evidence that climate (and future changes in climate) may influence rhinitis symptom prevalence. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.
A model for persistency of egg production

NARCIS (Netherlands)

Grossman, M.; Gossman, T.N.; Koops, W.J.

2000-01-01

The objectives of our study were to propose a new definition for persistency of egg production and to develop a mathematical model to describe the egg production curve, one that includes a new measure for persistency, based on the proposed definition, for use as a selection criterion to improve
Persistent Memory in Single Node Delay-Coupled Reservoir Computing.

Science.gov (United States)

Kovac, André David; Koall, Maximilian; Pipa, Gordon; Toutounji, Hazem

2016-01-01

Delays are ubiquitous in biological systems, ranging from genetic regulatory networks and synaptic conductances, to predator/pray population interactions. The evidence is mounting, not only to the presence of delays as physical constraints in signal propagation speed, but also to their functional role in providing dynamical diversity to the systems that comprise them. The latter observation in biological systems inspired the recent development of a computational architecture that harnesses this dynamical diversity, by delay-coupling a single nonlinear element to itself. This architecture is a particular realization of Reservoir Computing, where stimuli are injected into the system in time rather than in space as is the case with classical recurrent neural network realizations. This architecture also exhibits an internal memory which fades in time, an important prerequisite to the functioning of any reservoir computing device. However, fading memory is also a limitation to any computation that requires persistent storage. In order to overcome this limitation, the current work introduces an extended version to the single node Delay-Coupled Reservoir, that is based on trained linear feedback. We show by numerical simulations that adding task-specific linear feedback to the single node Delay-Coupled Reservoir extends the class of solvable tasks to those that require nonfading memory. We demonstrate, through several case studies, the ability of the extended system to carry out complex nonlinear computations that depend on past information, whereas the computational power of the system with fading memory alone quickly deteriorates. Our findings provide the theoretical basis for future physical realizations of a biologically-inspired ultrafast computing device with extended functionality.
The origins of lactase persistence in Europe.

Directory of Open Access Journals (Sweden)

Yuval Itan

2009-08-01

Full Text Available Lactase persistence (LP is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (-13,910 C/T indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the--13,910*T (derived allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on--13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the--13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe.
The origins of lactase persistence in Europe.

Science.gov (United States)

Itan, Yuval; Powell, Adam; Beaumont, Mark A; Burger, Joachim; Thomas, Mark G

2009-08-01

Lactase persistence (LP) is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (-13,910 C/T) indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the--13,910*T (derived) allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on--13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the--13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe.
Persistent organic pollutants

NARCIS (Netherlands)

Dungen, van den M.W.

2016-01-01

Wild caught fish, especially marine fish, can contain high levels of persistent organic pollutants (POPs). In the Netherlands, especially eel from the main rivers have high POP levels. This led to a ban in 2011 on eel fishing due to health concerns. Many of the marine POPs have been related to
Bacterial persistence: some new insights into an old phenomenon

Indian Academy of Sciences (India)

PRAKASH KUMAR

the involvement of the alarmone (p) ppGpp in the generation of persisters. However, the precise mechanisms are ... Bigger noticed that treatment of cultures of Staphylococcus aureus with high concentrations of ...... Li Y and Zhang Y 2007 pho U is a persister switch involved in persister formation and tolerance to multiple ...

Persistent infection caused by Hobi-like pestivirus.

Science.gov (United States)

Decaro, Nicola; Losurdo, Michele; Lucente, Maria Stella; Sciarretta, Rossana; Mari, Viviana; Larocca, Vittorio; Elia, Gabriella; Cavaliere, Nicola; Martella, Vito; Fasanella, Antonio; Buonavoglia, Canio

2013-04-01

A calf persistently infected by Hobi-like pestivirus was monitored for about 6 months, displaying clinical signs typical of bovine viral diarrhea virus persistent infection and shedding the virus through all body secretions, with maximal titers detected in urine. This report provides new insights into the pathogenesis of the emerging pestivirus.
Presynaptic learning and memory with a persistent firing neuron and a habituating synapse: a model of short term persistent habituation.

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Ramanathan, Kiruthika; Ning, Ning; Dhanasekar, Dhiviya; Li, Guoqi; Shi, Luping; Vadakkepat, Prahlad

2012-08-01

Our paper explores the interaction of persistent firing axonal and presynaptic processes in the generation of short term memory for habituation. We first propose a model of a sensory neuron whose axon is able to switch between passive conduction and persistent firing states, thereby triggering short term retention to the stimulus. Then we propose a model of a habituating synapse and explore all nine of the behavioral characteristics of short term habituation in a two neuron circuit. We couple the persistent firing neuron to the habituation synapse and investigate the behavior of short term retention of habituating response. Simulations show that, depending on the amount of synaptic resources, persistent firing either results in continued habituation or maintains the response, both leading to longer recovery times. The effectiveness of the model as an element in a bio-inspired memory system is discussed.
Impact of persistence and non-persistence in leisure time physical activity on coronary heart disease and all-cause mortality

DEFF Research Database (Denmark)

Schnohr, Peter; O'Keefe, James H.; Lange, Peter

2017-01-01

Aims: The aim of this study was to investigate the impact of persistence and non-persistence in leisure time physical activity on coronary heart disease and all-cause mortality. Methods and results: In the Copenhagen City Heart Study, we prospectively followed 12,314 healthy subjects for 33 years...
Generating Dynamic Persistence in the Time Domain

Science.gov (United States)

Guerrero, A.; Smith, L. A.; Smith, L. A.; Kaplan, D. T.

2001-12-01

Many dynamical systems present long-range correlations. Physically, these systems vary from biological to economical, including geological or urban systems. Important geophysical candidates for this type of behaviour include weather (or climate) and earthquake sequences. Persistence is characterised by slowly decaying correlation function; that, in theory, never dies out. The Persistence exponent reflects the degree of memory in the system and much effort has been expended creating and analysing methods that successfully estimate this parameter and model data that exhibits persistence. The most widely used methods for generating long correlated time series are not dynamical systems in the time domain, but instead are derived from a given spectral density. Little attention has been drawn to modelling persistence in the time domain. The time domain approach has the advantage that an observation at certain time can be calculated using previous observations which is particularly suitable when investigating the predictability of a long memory process. We will describe two of these methods in the time domain. One is a traditional approach using fractional ARIMA (autoregressive and moving average) models; the second uses a novel approach to extending a given series using random Fourier basis functions. The statistical quality of the two methods is compared, and they are contrasted with weather data which shows, reportedly, persistence. The suitability of this approach both for estimating predictability and for making predictions is discussed.
BEAM-BASED MEASUREMENTS OF PERSISTENT CURRENT DECAY IN RHIC

International Nuclear Information System (INIS)

FISCHER, W.; JAIN, A.; TEPIKIAN, S.

2001-01-01

The two RHIC rings are equipped with superconducting dipole magnets. At injection, induced persistent currents in these magnets lead to a sextupole component. As the persistent currents decay with time, the horizontal and vertical chromaticities change. From magnet measurements of persistent current decays, chromaticity changes in the machine are estimated and compared with chromaticity measurements
Using latent selection difference to model persistence in a declining population.

Directory of Open Access Journals (Sweden)

Mara E Erickson

Full Text Available Population persistence is a direct measure of the viability of a population. Monitoring the distribution of declining populations or subpopulations over time can yield estimates of persistence, which we show can be modeled as a latent selection difference (LSD contrasting attributes of sites where populations have persisted versus those that have not. Predicted persistence can be modeled with predictor covariates to identify factors correlated with species persistence. We demonstrate how to model persistence based on changes in occupancy that can include adjustments for detection probability. Using a known historical distribution of the western grebe (Aechmophorus occidentalis, we adapted methods originally developed for occupancy modeling to evaluate how environmental covariates including emergent vegetation and human developments have affected western grebe persistence in Alberta. The relative probability of persistence was correlated with the extent of shoreline bulrush (Scirpus lacustris, which is important vegetation for nesting cover. We also documented that western grebe populations were less likely to persist on lakes in the boreal forest, primarily located on the northern boundary of the species' range. Factors influencing occupancy were different than those determining persistence by western grebes; persistence and occupancy were not correlated. Persistence was more likely on lakes with recreational development, reflecting reliance by grebes on the larger, fish-bearing waterbodies that also are attractive for lakeshore development. Unfortunately, the correlation with recreational development on Alberta's lakes puts grebes at risk for loss of brood-rearing habitats--primary threats to altricial birds--if steps are not taken to prevent disturbance to bulrush stands. Identifying factors related to the persistence of a species--especially one in decline--is a fundamental step in conservation management.
Advanced statistics: linear regression, part I: simple linear regression.

Science.gov (United States)

Marill, Keith A

2004-01-01

Simple linear regression is a mathematical technique used to model the relationship between a single independent predictor variable and a single dependent outcome variable. In this, the first of a two-part series exploring concepts in linear regression analysis, the four fundamental assumptions and the mechanics of simple linear regression are reviewed. The most common technique used to derive the regression line, the method of least squares, is described. The reader will be acquainted with other important concepts in simple linear regression, including: variable transformations, dummy variables, relationship to inference testing, and leverage. Simplified clinical examples with small datasets and graphic models are used to illustrate the points. This will provide a foundation for the second article in this series: a discussion of multiple linear regression, in which there are multiple predictor variables.
Quantification of image persistence in a digital angiography system

International Nuclear Information System (INIS)

Okkalides, D.P.; Raptou, P.D.

1993-01-01

Image persistence, as a characteristic of video imaging systems affecting the quality of fast moving fluoroscopic images, is shown to vary considerably. A simple quantitative method for measuring image persistence in a digital angiography system is presented, together with a series of image intensifier exposure-response curves. For the Saticon tube, used with the Siemens 3VA Digitron, it was found that persistence increased for low exposure rates and may increase to 31% at a 120 ms interval. In addition, a sharp increase in image persistence, from 8.3% to 33%, was observed within 18 months from installation of the system. (author)
Genetic design of interpolated non-linear controllers for linear plants

International Nuclear Information System (INIS)

Ajlouni, N.

2000-01-01

The techniques of genetic algorithms are proposed as a means of designing non-linear PID control systems. It is shown that the use of genetic algorithms for this purpose results in highly effective non-linear PID control systems. These results are illustrated by using genetic algorithms to design a non-linear PID control system and contrasting the results with an optimally tuned linear PID controller. (author)
Diagnostic usefulness of segmental and linear enhancement in dynamic breast MRI

International Nuclear Information System (INIS)

Morakkabati-Spitz, N.; Leutner, C.; Schild, H.; Traeber, F.; Kuhl, C.

2005-01-01

prevalence of a ductal or a segmental enhancement pattern on breast MRI is low. But this finding has a high specificity and a moderate positive predictive value for intraductal neoplastic changes. We conclude that if segmental or linear enhancement is identified on breast MRI further work-up is necessary. We recommend either direct MR-guided vacuum-assisted core biopsy or short-term follow-up breast MRI within 3 months. If ductal enhancement then persists, MR-guided biopsy should be recommended even in the absence of mammographically visible signs of DCIS. (orig.)
Similarities and Differences Between Warped Linear Prediction and Laguerre Linear Prediction

NARCIS (Netherlands)

Brinker, Albertus C. den; Krishnamoorthi, Harish; Verbitskiy, Evgeny A.

2011-01-01

Linear prediction has been successfully applied in many speech and audio processing systems. This paper presents the similarities and differences between two classes of linear prediction schemes, namely, Warped Linear Prediction (WLP) and Laguerre Linear Prediction (LLP). It is shown that both
From stripe to slab confinement for DNA linearization in nanochannels

Science.gov (United States)

Cifra, Peter; Benkova, Zuzana; Namer, Pavol

We investigate suggested advantageous analysis in the linearization experiments with macromolecules confined in a stripe-like channel using Monte Carlo simulations. The enhanced chain extension in a stripe that is due to significant excluded volume interactions between monomers in two dimensions weakens on transition to experimentally feasible slit-like channel. Based on the chain extension-confinement strength dependence and the structure factor behavior for the chain in stripe we infer the excluded volume regime typical for two-dimensional systems. On transition to the slab geometry, the advantageous chain extension decreases and the Gaussian regime is observed for not very long semiflexible chains. The evidence for pseudo-ideality in confined chains is based on indicators such as the extension curves, variation of the extension with the persistence length or the structure factor. The slab behavior is observed when the stripe (originally of monomer thickness) reaches the thickness larger than cca 10nm in the third dimension. This maximum height of the slab to retain the advantage of the stripe is very low and this have implication for DNA linearization experiments. The presented analysis, however, has a broader relevance for confined polymers. Support from Slovak R&D Agency (SRDA-0451-11) is acknowledged.
Persistent Mullerian Duct Syndrome with Transverse Testicular ...

African Journals Online (AJOL)

Eastham JA, McEvoy K, Sullivan R, Chandrasoma P. A case of simultaneous bilateral nonseminomatous testicular tumors in persistent müllerian duct syndrome. J Urol 1992;148:407-8. 8. Shinmura Y, Yokoi T, Tsutsui Y. A case of clear cell adenocarcinoma of the müllerian duct in persistent müllerian duct syndrome: The first ...
Lymphogranuloma venereum causing a persistent genital ulcer.

Science.gov (United States)

Marcotte, Terrence; Lee, Yer; Pandori, Mark; Jain, Vivek; Cohen, Stephanie Elise

2014-04-01

Lymphogranuloma venereum (LGV) is a sexually transmitted cause of inguinal lymphadenopathy and proctocolitis. We report a patient with a persistent genital ulcer due to LGV (serovar L2b), an unusual presentation among US men who have sex with men. Lymphogranuloma venereum should be considered when evaluating persistent genital ulcers, and LGV-specific testing should be sought.
Persistent ovarian masses and pregnancy outcomes.

Science.gov (United States)

Goh, William A; Rincon, Monica; Bohrer, Justin; Tolosa, Jorge E; Sohaey, Roya; Riaño, Rene; Davis, James; Zalud, Ivica

2013-07-01

To determine if persistent ovarian masses in pregnancy are associated with increased adverse outcomes. This is a retrospective cohort of 126 pregnant women with a persistent ovarian mass measuring 5 cm or greater who delivered at two university hospitals between 2001 and 2009. Maternal outcomes included gestational age (GA) at diagnosis, delivery and surgery as well as miscarriage, preterm birth (PTB), ovarian torsion and hospital admission for pain. Neonatal outcomes included birth weight, respiratory distress syndrome (RDS), intra-ventricular hemorrhage (IVH), death and sepsis. A total of 1225 ovarian masses were identified (4.9%) in 24,868 patients. A persistent ovarian mass was found in 0.7%. Average GA at diagnosis was 17.8 weeks. Miscarriage rate was 3.3%. Average GA at delivery was 37.9 weeks. Of the patients, 8.5% had ovarian torsion, 10.3% had admission for pain and 9.3% had PTBs. The mean cesarean delivery rate was 46.3%. The average neonatal weight was 3273 g. There was one neonatal death in this cohort. The rate of RDS was 2.8%, IVH 0.9% and neonatal sepsis 1.9%. The most common surgical pathologic diagnosis was dermoids (37.6%). No overt malignancies were seen. A persistent ovarian mass in pregnancy does not confer an increased risk of adverse pregnancy outcomes.
Lesion progression in post-treatment persistent endodontic lesions.

Science.gov (United States)

Yu, Victoria Soo Hoon; Messer, Harold Henry; Shen, Liang; Yee, Robert; Hsu, Chin-ying Stephen

2012-10-01

Radiographic lesions related to root-filled teeth may persist for long periods after treatment and are considered to indicate failure of initial treatment. Persistent lesions are found in a proportion of cases, but information on lesion progression is lacking. This study examined the incidence of lesion improvement, remaining unchanged, and deterioration among persistent lesions in a group of patients recruited from a university-based clinic and identified potential predictors for lesion progression. Patients of a university clinic with persistent endodontic lesions at least 4 years since treatment and with original treatment radiographs available were recruited with informed consent. Data were obtained by interview and from dental records and clinical and radiographic examinations. Univariate and multivariate statistical analyses were carried out by using SPSS (version 19). One hundred fifty-one persistent lesions were identified in 114 patients. A majority of the lesions (107, 70.9%) received treatment between 4 and 5 years prior. Eighty-six lesions (57.0%) improved, 18 (11.9%) remained unchanged, and 47 (31.1%) deteriorated since treatment. Potential predictors for lesions that did not improve included recall lesion size, pain on biting at recall examination, history of a postobturation flare-up, and a non-ideal root-filling length (P < .05). Lesions that had persisted for a longer period appeared less likely to be improving (relative risk, 1.038; 95% confidence interval, 1.000-1.077). A specific time interval alone should not be used to conclude that a lesion will not resolve without intervention. This study identified several clinical factors that are associated with deteriorating persistent lesions, which should aid in identifying lesions that require further intervention. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Living with persistent rheumatoid arthritis: a BARFOT study.

Science.gov (United States)

Bala, Sidona-Valentina; Samuelson, Karin; Hagell, Peter; Fridlund, Bengt; Forslind, Kristina; Svensson, Björn; Thomé, Bibbi

2017-09-01

To describe and understand the meaning of living with persistent rheumatoid arthritis. A considerable number of patients with rheumatoid arthritis live with an ongoing active and symptomatic illness despite access to potent antirheumatic treatment. There is, however, a lack of knowledge about the meaning of living with this severe long-term illness, defined as persistent rheumatoid arthritis. A descriptive design based on a hermeneutic phenomenological method was used. Ten adults with persistent rheumatoid arthritis and at least five years disease duration were interviewed. The interviews were analysed according to van Manen's method. Living with persistent rheumatoid arthritis revealed four overall themes: an existence dominated by painful symptoms and treatment, radical changes and limitations in one's life, a continual struggle to cope with one's life and to master the illness, and a dependency on those who are close by and the world around. The lifeworld was affected to a varying extent and in various ways by the illness but also by the dependence on its treatment and care that was not experienced as sufficiently meeting needs in terms of security, access to and coordination of care as well as team and rehabilitation services. Persistent rheumatoid arthritis and its treatment entail a radical effect on the person's life and quality of life. Current ordinary rheumatology care does not seem to meet the individual needs of the person with persistent rheumatoid arthritis in an optimal way. A greater knowledge about and understanding of the person who lives with persistent rheumatoid arthritis is important for facilitating the development of care and the relief of suffering. A holistic alternative to conventional clinical practice, such as person-centred care, could be tested as an innovative model of care. Our findings might serve as material for educational and counselling purposes for healthcare professionals. © 2016 John Wiley & Sons Ltd.
Transposon mutagenesis identifies novel genes associated with Staphylococcus aureus persister formation

Directory of Open Access Journals (Sweden)

Wang ewenjie

2015-12-01

Full Text Available Pathogenic bacterial persisters are responsible for the recalcitrance of chronic and persistent infections to antimicrobial therapy. Although the mechanisms of persister formation and survival have been widely studied in Escherichia coli, persistence mechanisms in S. aureus remain largely unknown. Here, we screened a transposon mutant library of a clinical methicillin-resistant Staphylococcus aureus（MRSA）strain, USA500 (ST8, under antibiotic pressure and identified 13 genes whose insertion mutations resulted in a defect in persistence. These candidate genes were further confirmed by evaluating the survival of the mutants upon exposure to levofloxacin and several other stress conditions. We found 13 insertion mutants with significantly lower persister numbers under several stress conditions, including sdhA, sdhB, ureG, mnhG1, fbaA, ctaB, clpX, parE, HOU_0223, HOU_0587, HOU_2091, HOU_2315 and HOU_2346, which mapped into pathways of oxidative phosphorylation, TCA cycle, glycolysis, cell cycle and ABC transporters, suggesting that these genes and pathways may play an important role in persister formation and survival. The newly constructed knockout strains of ureG, sdhA and sdhB and their complemented strains were also tested for defect in persisters following exposure to levofloxacin and several other stress conditions. The results from these experiments were consistent with the screening results, which indicated that deletion of these genes in MRSA USA500 leads to persister defect. These findings provide novel insights into the mechanisms of persister formation and survival in S. aureus and offer new targets for the development of persister-directed antibiotics for the improved treatment of chronic and persistent infections.
The Persistence of Long Work Hours

OpenAIRE

Robert Drago; David Black; Mark Wooden

2005-01-01

Previous research hypothesizes that long working hours are related to consumerism, the ideal worker norm, high levels of human capital, and a high cost-of-job-loss. The authors test these hypotheses using panel data on working hours for an Australian sample of full-time employed workers. Analyses include a static cross-sectional model and a persistence model for long hours over time. The results suggest that long hours (50 or more hours in a usual week) are often persistent, and provide stron...
The Persistence of Profits in Azerbaijan's Banking System

Directory of Open Access Journals (Sweden)

K. Batu TUNAY

2015-06-01

Full Text Available In this research, the persistence of profits in Azerbaijan's banking sector in the short-run and the long-run is investigated. Although there are a lot of researches done in the case of different countries, enough study has been implemented for the case of Azerbaijan despite of its high speed economic growth. This research analysis continuity of profits by using system panel data method. Obtained results indicate that profits demonstrate no persistence or a little persistence. In this context, existence of competitive powers in the sector can be stated.

Finite-dimensional linear algebra

CERN Document Server

Gockenbach, Mark S

2010-01-01

Some Problems Posed on Vector SpacesLinear equationsBest approximationDiagonalizationSummaryFields and Vector SpacesFields Vector spaces Subspaces Linear combinations and spanning sets Linear independence Basis and dimension Properties of bases Polynomial interpolation and the Lagrange basis Continuous piecewise polynomial functionsLinear OperatorsLinear operatorsMore properties of linear operatorsIsomorphic vector spaces Linear operator equations Existence and uniqueness of solutions The fundamental theorem; inverse operatorsGaussian elimination Newton's method Linear ordinary differential eq
Linear algebra

CERN Document Server

Said-Houari, Belkacem

2017-01-01

This self-contained, clearly written textbook on linear algebra is easily accessible for students. It begins with the simple linear equation and generalizes several notions from this equation for the system of linear equations and introduces the main ideas using matrices. It then offers a detailed chapter on determinants and introduces the main ideas with detailed proofs. The third chapter introduces the Euclidean spaces using very simple geometric ideas and discusses various major inequalities and identities. These ideas offer a solid basis for understanding general Hilbert spaces in functional analysis. The following two chapters address general vector spaces, including some rigorous proofs to all the main results, and linear transformation: areas that are ignored or are poorly explained in many textbooks. Chapter 6 introduces the idea of matrices using linear transformation, which is easier to understand than the usual theory of matrices approach. The final two chapters are more advanced, introducing t...
Linear gate

International Nuclear Information System (INIS)

Suwono.

1978-01-01

A linear gate providing a variable gate duration from 0,40μsec to 4μsec was developed. The electronic circuity consists of a linear circuit and an enable circuit. The input signal can be either unipolar or bipolar. If the input signal is bipolar, the negative portion will be filtered. The operation of the linear gate is controlled by the application of a positive enable pulse. (author)
Nutrient transitions are a source of persisters in Escherichia coli biofilms.

Directory of Open Access Journals (Sweden)

Stephanie M Amato

Full Text Available Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.
Nutrient transitions are a source of persisters in Escherichia coli biofilms.

Science.gov (United States)

Amato, Stephanie M; Brynildsen, Mark P

2014-01-01

Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.
Persistent genital arousal disorder

DEFF Research Database (Denmark)

Eibye, Simone; Jensen, Hans Mørch

2014-01-01

We report a case of a woman suffering from persistent genital arousal disorder (PGAD) after paroxetine cessation. She was admitted to a psychiatric department and diagnosed with agitated depression. Physical investigation showed no gynaecological or neurological explanation; however, a pelvic MRI...
Shoreline type and subsurface oil persistence in the Exon Valdez spill zone of Prince William Sound, Alaska

Energy Technology Data Exchange (ETDEWEB)

Page, D.S. [Bowdoin College, Brunswick, ME (United States). Dept. of Chemistry; Boehm, P.D. [Exponent Inc., Maynard, MA (United States); Neff, J.M. [Neff and Associates, Duxbury, MA (United States)

2008-07-01

The grounding of the Exxon Valdez in Prince William Sound (PWS), Alaska in the spring of 1989 resulted in the release of 258,000 barrels of Alaska North Slope crude oil into the marine environment. Nearly 800 km of shoreline were oiled to some degree. There was an unprecedented oil spill cleanup effort following the spill. The shoreline surveys of the spill zone were synthesized in this paper in an effort to demonstrate the relationship between shoreline type and persistence of subsurface oil (SSO) residues. Shoreline surveys of surface and SSO indicate rapid initial oil loss with a decline from about 800 linear km of PWS shoreline in 1989 to about 10 km of oiled shoreline in 1992. The period of rapid loss was attributed to natural physical process, biodegradation and cleanup activities that removed accessible spill remnants from shorelines. This was followed by a slower natural average loss rate for less accessible surface and SSO deposits of about 22 per cent per year for the period 1992-2001. This paper emphasized that shoreline type plays a key role in determining SSO persistence. The geology of PWS is complex. Many of the shorelines where SSO persists have armouring layers composed of hard, dense clasts, such as the quartzite boulders and cobblestones that can protect SSO deposits. Eighteen years after the spill, persistent SSO deposits in PWS shorelines remain protected from tidal water-washing and biodegradation by a surface boulder/cobble armour and low sediment porosity. The SSO deposits are in a physical/chemical form and location where they do not pose a health risk to intertidal biological communities and animals. The surveys continue to substantiate that remaining SSO deposits in PWS continue to degrade and go away slowly. 37 refs., 5 tabs., 7 figs.
On the causes of persistent apical periodontitis: a review.

Science.gov (United States)

Nair, P N R

2006-04-01

Apical periodontitis is a chronic inflammatory disorder of periradicular tissues caused by aetiological agents of endodontic origin. Persistent apical periodontitis occurs when root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. Problems that lead to persistent apical periodontitis include: inadequate aseptic control, poor access cavity design, missed canals, inadequate instrumentation, debridement and leaking temporary or permanent restorations. Even when the most stringent procedures are followed, apical periodontitis may still persist as asymptomatic radiolucencies, because of the complexity of the root canal system formed by the main and accessory canals, their ramifications and anastomoses where residual infection can persist. Further, there are extraradicular factors -- located within the inflamed periapical tissue -- that can interfere with post-treatment healing of apical periodontitis. The causes of apical periodontitis persisting after root canal treatment have not been well characterized. During the 1990s, a series of investigations have shown that there are six biological factors that lead to asymptomatic radiolucencies persisting after root canal treatment. These are: (i) intraradicular infection persisting in the complex apical root canal system; (ii) extraradicular infection, generally in the form of periapical actinomycosis; (iii) extruded root canal filling or other exogenous materials that cause a foreign body reaction; (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues; (v) true cystic lesions, and (vi) scar tissue healing of the lesion. This article provides a comprehensive overview of the causative factors of non-resolving periapical lesions that are seen as asymptomatic radiolucencies post-treatment.
Modeling Real Exchange Rate Persistence in Chile

Directory of Open Access Journals (Sweden)

Leonardo Salazar

2017-07-01

Full Text Available The long and persistent swings in the real exchange rate have for a long time puzzled economists. Recent models built on imperfect knowledge economics seem to provide a theoretical explanation for this persistence. Empirical results, based on a cointegrated vector autoregressive (CVAR model, provide evidence of error-increasing behavior in prices and interest rates, which is consistent with the persistence observed in the data. The movements in the real exchange rate are compensated by movements in the interest rate spread, which restores the equilibrium in the product market when the real exchange rate moves away from its long-run benchmark value. Fluctuations in the copper price also explain the deviations of the real exchange rate from its long-run equilibrium value.
The linear programming bound for binary linear codes

NARCIS (Netherlands)

Brouwer, A.E.

1993-01-01

Combining Delsarte's (1973) linear programming bound with the information that certain weights cannot occur, new upper bounds for dmin (n,k), the maximum possible minimum distance of a binary linear code with given word length n and dimension k, are derived.
Inflation persistence in African countries: Does inflation targeting matter?

OpenAIRE

Phiri, Andrew

2016-01-01

This study investigates inflation persistence in annual CPI inflation collected between 1994 and 2014 for 46 African countries. We group these countries into panels according to whether they are inflation targeters or not and conduct estimations for pre and post inflation targeting periods. Interestingly enough, we find that inflation persistence was much higher for inflation targeters in periods before adopting their inflation targeting regimes and inflation persistence dropped by 40 percent...
Salt stress-induced transcription of σB- and CtsR-regulated genes in persistent and non-persistent Listeria monocytogenes strains from food processing plants.

Science.gov (United States)

Ringus, Daina L; Ivy, Reid A; Wiedmann, Martin; Boor, Kathryn J

2012-03-01

Listeria monocytogenes is a foodborne pathogen that can persist in food processing environments. Six persistent and six non-persistent strains from fish processing plants and one persistent strain from a meat plant were selected to determine if expression of genes in the regulons of two stress response regulators, σ(B) and CtsR, under salt stress conditions is associated with the ability of L. monocytogenes to persist in food processing environments. Subtype data were also used to categorize the strains into genetic lineages I or II. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to measure transcript levels for two σ(B)-regulated genes, inlA and gadD3, and two CtsR-regulated genes, lmo1138 and clpB, before and after (t=10 min) salt shock (i.e., exposure of exponential phase cells to BHI+6% NaCl for 10 min at 37°C). Exposure to salt stress induced higher transcript levels relative to levels under non-stress conditions for all four stress and virulence genes across all wildtype strains tested. Analysis of variance (ANOVA) of induction data revealed that transcript levels for one gene (clpB) were induced at significantly higher levels in non-persistent strains compared to persistent strains (p=0.020; two-way ANOVA). Significantly higher transcript levels of gadD3 (p=0.024; two-way ANOVA) and clpB (p=0.053; two-way ANOVA) were observed after salt shock in lineage I strains compared to lineage II strains. No clear association between stress gene transcript levels and persistence was detected. Our data are consistent with an emerging model that proposes that establishment of L. monocytogenes persistence in a specific environment occurs as a random, stochastic event, rather than as a consequence of specific bacterial strain characteristics.
Is corruption really persistent?

NARCIS (Netherlands)

Seldadyo, H.; de Haan, J.

Theoretical and empirical research on corruption generally concludes that corruption is persistent. However, using International Country Risk Guide data for the period 1984-2008 for 101 countries, we find strong evidence that corruption changes over time. In the present study, corruption levels of
Persistence of environmental DNA in freshwater ecosystems.

Directory of Open Access Journals (Sweden)

Tony Dejean

Full Text Available The precise knowledge of species distribution is a key step in conservation biology. However, species detection can be extremely difficult in many environments, specific life stages and in populations at very low density. The aim of this study was to improve the knowledge on DNA persistence in water in order to confirm the presence of the focus species in freshwater ecosystems. Aquatic vertebrates (fish: Siberian sturgeon and amphibian: Bullfrog tadpoles were used as target species. In control conditions (tanks and in the field (ponds, the DNA detectability decreases with time after the removal of the species source of DNA. DNA was detectable for less than one month in both conditions. The density of individuals also influences the dynamics of DNA detectability in water samples. The dynamics of detectability reflects the persistence of DNA fragments in freshwater ecosystems. The short time persistence of detectable amounts of DNA opens perspectives in conservation biology, by allowing access to the presence or absence of species e.g. rare, secretive, potentially invasive, or at low density. This knowledge of DNA persistence will greatly influence planning of biodiversity inventories and biosecurity surveys.
Energy Savings Lifetimes and Persistence

Energy Technology Data Exchange (ETDEWEB)

Hoffman, Ian M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schiller, Steven R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Billingsley, Megan A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Goldman, Charles A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schwartz, Lisa C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-02-01

This technical brief explains the concepts of energy savings lifetimes and savings persistence and discusses how program administrators use these factors to calculate savings for efficiency measures, programs and portfolios. Savings lifetime is the length of time that one or more energy efficiency measures or activities save energy, and savings persistence is the change in savings throughout the functional life of a given efficiency measure or activity. Savings lifetimes are essential for assessing the lifecycle benefits and cost effectiveness of efficiency activities and for forecasting loads in resource planning. The brief also provides estimates of savings lifetimes derived from a national collection of costs and savings for electric efficiency programs and portfolios.
Search along persistent random walks

International Nuclear Information System (INIS)

Friedrich, Benjamin M

2008-01-01

Optimal search strategies and their implementations in biological systems are a subject of active research. Here we study a search problem which is motivated by the hunt of sperm cells for the egg. We ask for the probability for an active swimmer to find a target under the condition that the swimmer starts at a certain distance from the target. We find that success probability is maximal for a certain level of fluctuations characterized by the persistence length of the swimming path of the swimmer. We derive a scaling law for the optimal persistence length as a function of the initial target distance and search time by mapping the search on a polymer physics problem
Persistent Memory in Single Node Delay-Coupled Reservoir Computing.

Directory of Open Access Journals (Sweden)

André David Kovac

Full Text Available Delays are ubiquitous in biological systems, ranging from genetic regulatory networks and synaptic conductances, to predator/pray population interactions. The evidence is mounting, not only to the presence of delays as physical constraints in signal propagation speed, but also to their functional role in providing dynamical diversity to the systems that comprise them. The latter observation in biological systems inspired the recent development of a computational architecture that harnesses this dynamical diversity, by delay-coupling a single nonlinear element to itself. This architecture is a particular realization of Reservoir Computing, where stimuli are injected into the system in time rather than in space as is the case with classical recurrent neural network realizations. This architecture also exhibits an internal memory which fades in time, an important prerequisite to the functioning of any reservoir computing device. However, fading memory is also a limitation to any computation that requires persistent storage. In order to overcome this limitation, the current work introduces an extended version to the single node Delay-Coupled Reservoir, that is based on trained linear feedback. We show by numerical simulations that adding task-specific linear feedback to the single node Delay-Coupled Reservoir extends the class of solvable tasks to those that require nonfading memory. We demonstrate, through several case studies, the ability of the extended system to carry out complex nonlinear computations that depend on past information, whereas the computational power of the system with fading memory alone quickly deteriorates. Our findings provide the theoretical basis for future physical realizations of a biologically-inspired ultrafast computing device with extended functionality.
The Enigmatic Persistence of Anorexia Nervosa

Science.gov (United States)

Walsh, B. Timothy

2014-01-01

Objective In this review, based on recent advances in cognitive neuroscience, the author presents a formulation in which the marked persistence of anorexia nervosa can be usefully understood as a well-ingrained maladaptive habit. Method The author reviewed the relevant literature on the development and course of anorexia nervosa and interpreted critical features in light of developments in cognitive neuroscience. Results Anorexia nervosa is a well characterized disorder with remarkable persistence both across history and among affected individuals. Food restriction, the salient behavioral feature of the disorder, often begins innocently but gradually takes on a life of its own. Over time, it becomes highly entrenched and resistant to change through either psychological or pharmacological treatment. Cognitive neuroscience has described two related but distinct processes that underlie the acquisition of new patterns of behavior, namely, action-outcome and stimulus-response learning. It is likely that both processes are engaged in the development of anorexia nervosa and that stimulus-response learning (that is, habit formation) is critical to the persistence of the dieting behavior. Conclusions The formulation of the dieting behavior characteristic of anorexia nervosa as a well-entrenched habit provides a basis for understanding the striking persistence of this disorder. This model helps explain the resistance of anorexia nervosa to interventions that have established efficacy in related disorders and implies that addressing the dieting behavior is critical, especially early in the course of the illness, before it has become ingrained. PMID:23429750
Extending and implementing the Persistent ID pillars

Science.gov (United States)

Car, Nicholas; Golodoniuc, Pavel; Klump, Jens

2017-04-01

The recent double decade anniversary of scholarly persistent identifier use has triggered journal special editions such as "20 Years of Persistent Identifiers". For such a publication, it is apt to consider the longevity of some persistent identifier (PID) mechanisms (Digital Object Identifiers) and the partial disappearance of others (Life Sciences IDs). We have previously postulated a set of "PID Pillars" [1] which are design principles aimed at ensuring PIDs can survive technology and social change and thus persist for the long term that we have drawn from our observations of PIDs at work over many years. The principles: describe how to ensure identifiers' system and organisation independence; codify the delivery of essential PID system functions; mandate a separation of PID functions from data delivery mechanisms; and require generation of policies detailing how change is handled. In this presentation, first we extend on our previous work of introducing the pillars by refining their descriptions, giving specific suggestions for each and presenting some work that addresses them. Second, we propose a baseline data model for persistent identifiers that, if used, would assist the separation of PID metadata and PID system functioning. This would allow PID system function specifics to change over time (e.g. resolver services or even resolution protocols) and yet preserve the PIDs themselves. Third, we detail our existing PID system — the PID Service [2] — that partially implements the pillars and describe both its successes and shortcomings. Finally, we describe our planned next-generation system that will aim to use the baseline data model and fully implement the pillars.
Handbook on linear motor application

International Nuclear Information System (INIS)

1988-10-01

This book guides the application for Linear motor. It lists classification and speciality of Linear Motor, terms of linear-induction motor, principle of the Motor, types on one-side linear-induction motor, bilateral linear-induction motor, linear-DC Motor on basic of the motor, linear-DC Motor for moving-coil type, linear-DC motor for permanent-magnet moving type, linear-DC motor for electricity non-utility type, linear-pulse motor for variable motor, linear-pulse motor for permanent magneto type, linear-vibration actuator, linear-vibration actuator for moving-coil type, linear synchronous motor, linear electromagnetic motor, linear electromagnetic solenoid, technical organization and magnetic levitation and linear motor and sensor.

Reflections on Student Persistence

Directory of Open Access Journals (Sweden)

Vincent Tinto

2017-07-01

Full Text Available The Feature for this issue Reflections on Student Persistence has been prepared by Professor Vincent Tinto, Distinguished University Professor Emeritus at Syracuse University, United States of America (USA and a longtime friend and supporter of STARS. Vincent explores the case for motivation to be considered as a significant aspect of the tertiary student psyche by drawing on theoretical frameworks, research and practical experiences related to the issue. He synthesises this extensive, detailed, rich but often somewhat impenetrable data into a trilogy of clear and credible key dimensions of the motivation construct student self efficacy, sense of belonging and perceived value of the curriculum. This interpretation of the literature is a personal but informed reflection and is a timely piece which highlights the breadth and profundity of the presentations at this year's conference in Adelaide, Australia where students in all their diversity are central to our focus on enhancing the student experience. In this opening article, Vincent refers directly to the STARS papers selected for this Conference issue of the Journal which also address the importance of student persistence, self-efficacy and building the sense of belonging within their own institutional communities (Fernandes, Ford, Rayner & Pretorius; Kahu, Nelson, & Picton; McFarlane, Spes-Skrbis & Taib; Naylor; Smallhorn. Echoing his position on social justice and his advocacy for underserved students, Vincent reminds us that educational equity gaps still exist, and he encourages us to see the issue of persistence through the eyes of the students to support their perseverance and completion and thereby help reduce educational disadvantage.
Entropy measurements in paroxysmal and persistent atrial fibrillation

International Nuclear Information System (INIS)

Cervigón, R; Moreno, J; Pérez-Villacastín, J; Reilly, R B; Millet, J; Castells, F

2010-01-01

Recent studies on atrial fibrillation (AF) have identified different activation patterns in paroxysmal and persistent AF. In this study, bipolar intra-atrial registers from 28 patients (14 paroxysmal AF and 14 persistent AF) were analyzed in order to find out regional differences in the organization in both types of arrhythmias. The organization of atrial electrical activity was assessed in terms of nonlinear parameters, such as entropy measurements. Results showed differences between the atrial chambers with a higher disorganization in the left atrium in paroxysmal AF patients and a more homogenous behavior along the atria in persistent AF patients
Multiresolution persistent homology for excessively large biomolecular datasets

Energy Technology Data Exchange (ETDEWEB)

Xia, Kelin; Zhao, Zhixiong [Department of Mathematics, Michigan State University, East Lansing, Michigan 48824 (United States); Wei, Guo-Wei, E-mail: wei@math.msu.edu [Department of Mathematics, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (United States)

2015-10-07

Although persistent homology has emerged as a promising tool for the topological simplification of complex data, it is computationally intractable for large datasets. We introduce multiresolution persistent homology to handle excessively large datasets. We match the resolution with the scale of interest so as to represent large scale datasets with appropriate resolution. We utilize flexibility-rigidity index to access the topological connectivity of the data set and define a rigidity density for the filtration analysis. By appropriately tuning the resolution of the rigidity density, we are able to focus the topological lens on the scale of interest. The proposed multiresolution topological analysis is validated by a hexagonal fractal image which has three distinct scales. We further demonstrate the proposed method for extracting topological fingerprints from DNA molecules. In particular, the topological persistence of a virus capsid with 273 780 atoms is successfully analyzed which would otherwise be inaccessible to the normal point cloud method and unreliable by using coarse-grained multiscale persistent homology. The proposed method has also been successfully applied to the protein domain classification, which is the first time that persistent homology is used for practical protein domain analysis, to our knowledge. The proposed multiresolution topological method has potential applications in arbitrary data sets, such as social networks, biological networks, and graphs.
Hyperthyroidism as a cause of persistent vomiting.

Science.gov (United States)

Hoogendoorn, E H; Cools, B M

2004-09-01

A 32-year-old woman presented with persistent vomiting, epigastric pain and weight loss. A sinus tachycardia was the clue to the diagnosis of hyperthyroidism due to Graves' disease. On treatment with propylthiouracil and a beta-blocking agent, her symptoms resolved within one day, even though her free thyroxine level was still high. Hyperthyroidism is an uncommon, but previously reported cause of persistent vomiting.
Hyperthyroidism as a cause of persistent vomiting.

OpenAIRE

Hoogendoorn, E.H.; Cools, B.M.

2004-01-01

A 32-year-old woman presented with persistent vomiting, epigastric pain and weight loss. A sinus tachycardia was the clue to the diagnosis of hyperthyroidism due to Graves' disease. On treatment with propylthiouracil and a beta-blocking agent, her symptoms resolved within one day, even though her free thyroxine level was still high. Hyperthyroidism is an uncommon, but previously reported cause of persistent vomiting.
Solving non-linear Horn clauses using a linear Horn clause solver

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick; Ganty, Pierre

2016-01-01

In this paper we show that checking satisfiability of a set of non-linear Horn clauses (also called a non-linear Horn clause program) can be achieved using a solver for linear Horn clauses. We achieve this by interleaving a program transformation with a satisfiability checker for linear Horn...... clauses (also called a solver for linear Horn clauses). The program transformation is based on the notion of tree dimension, which we apply to a set of non-linear clauses, yielding a set whose derivation trees have bounded dimension. Such a set of clauses can be linearised. The main algorithm...... dimension. We constructed a prototype implementation of this approach and performed some experiments on a set of verification problems, which shows some promise....
Multiscale Persistent Functions for Biomolecular Structure Characterization

Energy Technology Data Exchange (ETDEWEB)

Xia, Kelin [Nanyang Technological University (Singapore). Division of Mathematical Sciences, School of Physical, Mathematical Sciences and School of Biological Sciences; Li, Zhiming [Central China Normal University, Wuhan (China). Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics; Mu, Lin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division

2017-11-02

Here in this paper, we introduce multiscale persistent functions for biomolecular structure characterization. The essential idea is to combine our multiscale rigidity functions (MRFs) with persistent homology analysis, so as to construct a series of multiscale persistent functions, particularly multiscale persistent entropies, for structure characterization. To clarify the fundamental idea of our method, the multiscale persistent entropy (MPE) model is discussed in great detail. Mathematically, unlike the previous persistent entropy (Chintakunta et al. in Pattern Recognit 48(2):391–401, 2015; Merelli et al. in Entropy 17(10):6872–6892, 2015; Rucco et al. in: Proceedings of ECCS 2014, Springer, pp 117–128, 2016), a special resolution parameter is incorporated into our model. Various scales can be achieved by tuning its value. Physically, our MPE can be used in conformational entropy evaluation. More specifically, it is found that our method incorporates in it a natural classification scheme. This is achieved through a density filtration of an MRF built from angular distributions. To further validate our model, a systematical comparison with the traditional entropy evaluation model is done. Additionally, it is found that our model is able to preserve the intrinsic topological features of biomolecular data much better than traditional approaches, particularly for resolutions in the intermediate range. Moreover, by comparing with traditional entropies from various grid sizes, bond angle-based methods and a persistent homology-based support vector machine method (Cang et al. in Mol Based Math Biol 3:140–162, 2015), we find that our MPE method gives the best results in terms of average true positive rate in a classic protein structure classification test. More interestingly, all-alpha and all-beta protein classes can be clearly separated from each other with zero error only in our model. Finally, a special protein structure index (PSI) is proposed, for the first
The Economy of Persistence: Mario the Tailor

Directory of Open Access Journals (Sweden)

Prudence Black

2016-03-01

Full Text Available Mario Conte has had a tailor shop in King Street, Newtown since the mid 1960s. Taking an interview with Mario as its point of departure, this article describes the persistence of a skilled worker whose practices and techniques remain the same in a world that has long changed. While inattentive to what rules might be used to decorate a shop window, Mario continues to make and sew in the way that he learnt in post-war Italy. Mario’s persistence could be described as all the skills and other elements that need to be in place to keep him working, in particular the tradition of tailoring techniques he has remained true to over the last fifty years. The hand stitching of his tailoring is like a metronome of that persistence.
Cortical dynamics of feature binding and reset: control of visual persistence.

Science.gov (United States)

Francis, G; Grossberg, S; Mingolla, E

1994-04-01

An analysis of the reset of visual cortical circuits responsible for the binding or segmentation of visual features into coherent visual forms yields a model that explains properties of visual persistence. The reset mechanisms prevent massive smearing of visual percepts in response to rapidly moving images. The model simulates relationships among psychophysical data showing inverse relations of persistence to flash luminance and duration, greater persistence of illusory contours than real contours, a U-shaped temporal function for persistence of illusory contours, a reduction of persistence due to adaptation with a stimulus of like orientation, an increase of persistence with spatial separation of a masking stimulus. The model suggests that a combination of habituative, opponent, and endstopping mechanisms prevent smearing and limit persistence. Earlier work with the model has analyzed data about boundary formation, texture segregation, shape-from-shading, and figure-ground separation. Thus, several types of data support each model mechanism and new predictions are made.
Linear and non-linear simulation of joints contact surface using ...

African Journals Online (AJOL)

The joint modelling including non-linear effects needs accurate and precise study of their behaviors. When joints are under the dynamic loading, micro, macro- slip happens in contact surface which is non-linear reason of the joint contact surface. The non-linear effects of joint contact surface on total behavior of structure are ...
Linear shaped charge

Energy Technology Data Exchange (ETDEWEB)

Peterson, David; Stofleth, Jerome H.; Saul, Venner W.

2017-07-11

Linear shaped charges are described herein. In a general embodiment, the linear shaped charge has an explosive with an elongated arrowhead-shaped profile. The linear shaped charge also has and an elongated v-shaped liner that is inset into a recess of the explosive. Another linear shaped charge includes an explosive that is shaped as a star-shaped prism. Liners are inset into crevices of the explosive, where the explosive acts as a tamper.
Persistent puhnonary hypertension ofthe neonate in a developing ...

African Journals Online (AJOL)

'PFC syndrome (persistence ofthe feral circulation). Circulation 1969; 40: Ill. 2. Fox WW, Duara S. Persistent pulmonary hypertension in the neonate: diagnosis and management. J Pediatr 1983; 103: 505-. 508. 3. Dworetz AR, Moya FR, Sabo B, Gladstone I, Gross 1. Survival of infants with persisteot pulmonary hypertension ...
Persistence and vulnerability: retaining biodiversity in the landscape ...

Indian Academy of Sciences (India)

Unknown

An objective of biodiversity conservation activities is to minimize the exposure of biodiversity features to threatening processes and to ensure, as far as possible, that biodiversity persists in the landscape. We discuss how issues of vulnerability and persistence can and should be addressed at all stages of the conservation.
Supporting Academic Persistence in Low-Skilled Adult Learners

Science.gov (United States)

O'Neill, Susan; Thomson, Margareta Maria

2013-01-01

The current literature review explores the factors that contribute to academic persistence for adult learners. The aim of the study is to identify current research-based strategies aimed at supporting learner persistence, particularly for low-skilled adults. Elements of three theoretical frameworks, namely, expectancy-value theory (EVT), goal…
Coral reef fish populations can persist without immigration

KAUST Repository

Salles, Océane C.

2015-11-18

Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase.
Neural processes underlying cultural differences in cognitive persistence.

Science.gov (United States)

Telzer, Eva H; Qu, Yang; Lin, Lynda C

2017-08-01

Self-improvement motivation, which occurs when individuals seek to improve upon their competence by gaining new knowledge and improving upon their skills, is critical for cognitive, social, and educational adjustment. While many studies have delineated the neural mechanisms supporting extrinsic motivation induced by monetary rewards, less work has examined the neural processes that support intrinsically motivated behaviors, such as self-improvement motivation. Because cultural groups traditionally vary in terms of their self-improvement motivation, we examined cultural differences in the behavioral and neural processes underlying motivated behaviors during cognitive persistence in the absence of extrinsic rewards. In Study 1, 71 American (47 females, M=19.68 years) and 68 Chinese (38 females, M=19.37 years) students completed a behavioral cognitive control task that required cognitive persistence across time. In Study 2, 14 American and 15 Chinese students completed the same cognitive persistence task during an fMRI scan. Across both studies, American students showed significant declines in cognitive performance across time, whereas Chinese participants demonstrated effective cognitive persistence. These behavioral effects were explained by cultural differences in self-improvement motivation and paralleled by increasing activation and functional coupling between the inferior frontal gyrus (IFG) and ventral striatum (VS) across the task among Chinese participants, neural activation and coupling that remained low in American participants. These findings suggest a potential neural mechanism by which the VS and IFG work in concert to promote cognitive persistence in the absence of extrinsic rewards. Thus, frontostriatal circuitry may be a neurobiological signal representing intrinsic motivation for self-improvement that serves an adaptive function, increasing Chinese students' motivation to engage in cognitive persistence. Copyright © 2017 Elsevier Inc. All rights
Human macrophages support persistent transcription from unintegrated HIV-1 DNA

International Nuclear Information System (INIS)

Kelly, Jeremy; Beddall, Margaret H.; Yu Dongyang; Iyer, Subashini R.; Marsh, Jon W.; Wu Yuntao

2008-01-01

Retroviruses require integration of their RNA genomes for both stability and productive viral replication. In HIV infection of non-dividing, resting CD4 T cells, where integration is greatly impeded, the reverse transcribed HIV DNA has limited biological activity and a short half-life. In metabolically active and proliferating T cells, unintegrated DNA rapidly diminishes with cell division. HIV also infects the non-dividing but metabolically active macrophage population. In an in vitro examination of HIV infection of macrophages, we find that unintegrated viral DNA not only has an unusual stability, but also maintains biological activity. The unintegrated linear DNA, 1-LTR, and 2-LTR circles are stable for at least 30 days. Additionally, there is persistent viral gene transcription, which is selective and skewed towards viral early genes such as nef and tat with highly diminished rev and vif. One viral early gene product Nef was measurably synthesized. We also find that independent of integration, the HIV infection process in macrophages leads to generation of numerous chemokines
Demonstration of persistent contamination of a cooked egg product production facility with Salmonella enterica serovar Tennessee and characterization of the persistent strain.

Science.gov (United States)

Jakočiūnė, D; Bisgaard, M; Pedersen, K; Olsen, J E

2014-08-01

The aim of this study was to investigate whether continuous contamination of light pasteurized egg products with Salmonella enterica serovar Tennessee (S. Tennessee) at a large European producer of industrial egg products was caused by persistent contamination of the production facility and to characterize the persistent strains. Seventy-three S. Tennessee isolates collected from products over a 3-year period with intermittent contamination, and 15 control strains were compared by pulsed field gel electrophoresis (PFGE) using two enzymes. Forty-five case isolates distributed throughout the full period were shown to belong to one profile type. Isolates representing different PFGE profiles were all assigned to ST 319 by multilocus sequence typing (MLST). The case isolates did not show a higher ability to form biofilm on a plastic surface than noncase isolates. Characteristically, members of the persistent clone were weak producers of H2 S in laboratory medium. S. Tennessee isolated from the case was able to grow better in pasteurized egg product compared with other serovars investigated. It was concluded that the contamination was caused by a persistent strain in the production facility and that this strain apparently had adapted to grow in the relevant egg product. S. Tennessee has previously been associated with persistence in hatching facilities. This is the first report of persistent contamination of an egg production facility with this serovar. © 2014 The Society for Applied Microbiology.
Lactase Non-persistence and Lactose Intolerance.

Science.gov (United States)

Bayless, Theodore M; Brown, Elizabeth; Paige, David M

2017-05-01

To evaluate the clinical and nutritional significance of genetically determined lactase non-persistence and potential lactose and milk intolerance in 65-70% of the world's adult population. Milk consumption is decreasing in the USA and is the lowest in countries with a high prevalence of lactase non-persistence. The dairy industry and Minnesota investigators have made efforts to minimize the influence of lactose intolerance on milk consumption. Some lactose intolerant individuals, without co-existent irritable bowel syndrome, are able to consume a glass of milk with a meal with no or minor symptoms. The high frequency of lactase persistence in offspring of Northern European countries and in some nomadic African tribes is due to mutations in the promoter of the lactase gene in association with survival advantage of milk drinking. Educational and commercial efforts to improve calcium and Vitamin D intake have focused on urging consumption of tolerable amounts of milk with a meal, use of lowered lactose-content foods including hard cheeses, yogurt, and lactose-hydrolyzed milk products.
Persistent physical symptoms as perceptual dysregulation

DEFF Research Database (Denmark)

Henningsen, Peter; Gündel, Harald; Kop, Willem J

2018-01-01

OBJECTIVE: The mechanisms underlying the perception and experience of persistent physical symptoms are not well understood, and in the models, the specific relevance of peripheral input versus central processing, or of neurobiological versus psychosocial factors in general, is not clear.In this a......OBJECTIVE: The mechanisms underlying the perception and experience of persistent physical symptoms are not well understood, and in the models, the specific relevance of peripheral input versus central processing, or of neurobiological versus psychosocial factors in general, is not clear.......In this article, we propose a model for this clinical phenomenon that is designed to be coherent with an underlying, relatively new model of the normal brain functions involved in the experience of bodily signals. METHODS: Based on a review of recent literature we describe central elements of this model and its...... of predictions and sensory input. Two possibilities exist: adaptation of the generative model underlying the predictions or alteration of the sensory input via autonomic nervous activation (in the case of interoception). Following this model, persistent physical symptoms can be described as "failures...

Adolescents' experience of complex persistent pain.

Science.gov (United States)

Sørensen, Kari; Christiansen, Bjørg

2017-04-01

Persistent (chronic) pain is a common phenomenon in adolescents. When young people are referred to a pain clinic, they usually have amplified pain signals, with pain syndromes of unconfirmed ethology, such as fibromyalgia and complex regional pain syndrome (CRPS). Pain is complex and seems to be related to a combination of illness, injury, psychological distress, and environmental factors. These young people are found to have higher levels of distress, anxiety, sleep disturbance, and lower mood than their peers and may be in danger of entering adulthood with mental and physical problems. In order to understand the complexity of persistent pain in adolescents, there seems to be a need for further qualitative research into their lived experiences. The aim of this study was to explore adolescents' experiences of complex persistent pain and its impact on everyday life. The study has an exploratory design with individual in-depth interviews with six youths aged 12-19, recruited from a pain clinic at a main referral hospital in Norway. A narrative approach allowed the informants to give voice to their experiences concerning complex persistent pain. A hermeneutic analysis was used, where the research question was the basis for a reflective interpretation. Three main themes were identified: (1) a life with pain and unpleasant bodily expressions; (2) an altered emotional wellbeing; and (3) the struggle to keep up with everyday life. The pain was experienced as extremely strong, emerging from a minor injury or without any obvious causation, and not always being recognised by healthcare providers. The pain intensity increased as the suffering got worse, and the sensation was hard to describe with words. Parts of their body could change in appearance, and some described having pain-attacks or fainting. The feeling of anxiety was strongly connected to the pain. Despair and uncertainty contributed to physical disability, major sleep problems, school absence, and withdrawal from
Prevalence of Persistent Proteinuria using Urine Protein/Creatinine ...

African Journals Online (AJOL)

Age and social class did not contribute significantly to having persistent proteinuria. Conclusion: The prevalence of persistent proteinuria in these asymptomatic children using UPC ratio was almost similar to the repeat urinalysis done after two weeks. It is hereby recommended that where UPC ratio is not available a positive ...
Persistence and extinction for a stochastic logistic model with infinite delay

OpenAIRE

Chun Lu; Xiaohua Ding

2013-01-01

This article, studies a stochastic logistic model with infinite delay. Using a phase space, we establish sufficient conditions for the extinction, nonpersistence in the mean, weak persistence, and stochastic permanence. A threshold between weak persistence and extinction is obtained. Our results state that different types of environmental noises have different effects on the persistence and extinction, and that the delay has no impact on the persistence and ext...
Linear algebra

CERN Document Server

Stoll, R R

1968-01-01

Linear Algebra is intended to be used as a text for a one-semester course in linear algebra at the undergraduate level. The treatment of the subject will be both useful to students of mathematics and those interested primarily in applications of the theory. The major prerequisite for mastering the material is the readiness of the student to reason abstractly. Specifically, this calls for an understanding of the fact that axioms are assumptions and that theorems are logical consequences of one or more axioms. Familiarity with calculus and linear differential equations is required for understand
Trends in prescribing and persistence with antihypertensive therapy: results of the study PAPEETE (Population-based Analysis of Persistence and Economics of treatment with telmisartan study

Directory of Open Access Journals (Sweden)

Francesco Vittorio Costa

2009-12-01

Full Text Available This paper summarizes the results of the PAPEETE study (Population-based Analysis of PErsistence with treatment and Economics of TElmisartan that assessed trends in prescriptions, determinants and timing of treatment discontinuation and/or changes in antihypertensive drug therapy in a cohort of hypertensive patients living in Pavia. In the study were included all new users 18 years old or over receiving a first prescription for diuretics, beta-blockers, calcium channel-blockers, ACE inhibitors (ACEi or angiotensin receptor blockers (ARBs between 1 January 2003 and 31 December 2006. The follow-up period for each patient was 12 months starting from enrolment date. Based in the presence of continuous therapy, patients were defined as persistent and non-persistent users. A total of 61,493 patients was included in the study of whom 11.2% were persistent. Persistence with the treatment seems to be associated with patient-related factors and with the class of anti-hypertensive drug initially prescribed with the lowest persistence to antihypertensive treatment with diuretics (3.0% and the highest with ARBs (18.8%.
Basic linear algebra

CERN Document Server

Blyth, T S

2002-01-01

Basic Linear Algebra is a text for first year students leading from concrete examples to abstract theorems, via tutorial-type exercises. More exercises (of the kind a student may expect in examination papers) are grouped at the end of each section. The book covers the most important basics of any first course on linear algebra, explaining the algebra of matrices with applications to analytic geometry, systems of linear equations, difference equations and complex numbers. Linear equations are treated via Hermite normal forms which provides a successful and concrete explanation of the notion of linear independence. Another important highlight is the connection between linear mappings and matrices leading to the change of basis theorem which opens the door to the notion of similarity. This new and revised edition features additional exercises and coverage of Cramer's rule (omitted from the first edition). However, it is the new, extra chapter on computer assistance that will be of particular interest to readers:...
Toward Rechargeable Persistent Luminescence for the First and Third Biological Windows via Persistent Energy Transfer and Electron Trap Redistribution.

Science.gov (United States)

Xu, Jian; Murata, Daisuke; Ueda, Jumpei; Viana, Bruno; Tanabe, Setsuhisa

2018-05-07

Persistent luminescence (PersL) imaging without real-time external excitation has been regarded as the next generation of autofluorescence-free optical imaging technology. However, to achieve improved imaging resolution and deep tissue penetration, developing new near-infrared (NIR) persistent phosphors with intense and long duration PersL over 1000 nm is still a challenging but urgent task in this field. Herein, making use of the persistent energy transfer process from Cr 3+ to Er 3+ , we report a novel garnet persistent phosphor of Y 3 Al 2 Ga 3 O 12 codoped with Er 3+ and Cr 3+ (YAG G:Er-Cr), which shows intense Cr 3+ PersL (∼690 nm) in the deep red region matching well with the first biological window (NIR-I, 650-950 nm) and Er 3+ PersL (∼1532 nm) in the NIR region matching well with the third biological window (NIR-III, 1500-1800 nm). The optical imaging through raw-pork tissues (thickness of 1 cm) suggests that the emission band of Er 3+ can achieve higher spatial resolution and more accurate signal location than that of Cr 3+ due to the reduced light scattering at longer wavelengths. Furthermore, by utilizing two independent electron traps with two different trap depths in YAG G:Er-Cr, the Cr 3+ /Er 3+ PersL can even be recharged in situ by photostimulation with 660 nm LED thanks to the redistribution of trapped electrons from the deep trap to the shallow one. Our results serve as a guide in developing promising NIR (>1000 nm) persistent phosphors for long-term optical imaging.
Persistence extends reciprocity.

Science.gov (United States)

Kurokawa, Shun

2017-04-01

One key potential explanation for the evolution of cooperation is conditional cooperation. This allows cooperation to evolve for cooperators who switch their behavior on the basis of information about the opponent's behavior or reputation. However, information about the opponent's behavior or reputation is sometimes unavailable, and previous studies have assumed that a player cooperates with some default probability when no information about the opponent's previous behavior or reputation is available. This default probability has been interpreted as the player's "optimism". Here, we make use of the fact that even if a player cannot observe the opponent's previous behavior or reputation, he may still condition his future behavior based on his own past behavior and in such a case, he can behave persistently. In this paper, we especially consider the case where information about the opponent's "behavior" is sometimes absent and the iterated prisoner's dilemma game between the same two individuals is played. Here, we examine the evolution of strategies that can refer to the own behavior in the previous round. Using evolutionarily stable strategy (ESS) analysis and analyzing replicator dynamics, we find that conditioning his future behavior based on his own past behavior is beneficial for the evolution. Persistence facilitates the evolution of cooperation. Copyright © 2017 Elsevier Inc. All rights reserved.
Linear algebra

CERN Document Server

Liesen, Jörg

2015-01-01

This self-contained textbook takes a matrix-oriented approach to linear algebra and presents a complete theory, including all details and proofs, culminating in the Jordan canonical form and its proof. Throughout the development, the applicability of the results is highlighted. Additionally, the book presents special topics from applied linear algebra including matrix functions, the singular value decomposition, the Kronecker product and linear matrix equations. The matrix-oriented approach to linear algebra leads to a better intuition and a deeper understanding of the abstract concepts, and therefore simplifies their use in real world applications. Some of these applications are presented in detailed examples. In several ‘MATLAB-Minutes’ students can comprehend the concepts and results using computational experiments. Necessary basics for the use of MATLAB are presented in a short introduction. Students can also actively work with the material and practice their mathematical skills in more than 300 exerc...
Persistency of milk yield in Indonesian Holstein cows

Science.gov (United States)

Widyas, N.; Putra, F. Y.; Nugroho, T.; Pramono, A.; Susilowati, A.; Sutarno; Prastowo, S.

2018-03-01

Milk yield is an important trait in dairy industry; thus, information regarding this phenotype is essential to measure the productivity of a farm. Total milk yield in one lactation period was often predicted using information from samples collected within certain time intervals. The rate of change of milk production between two-time intervals is defined as persistency. This article aims to estimate the persistency of milk yield between lactation 1, 2 and 3 in Indonesian Friesian Holstein (IFH) cows. Data was collected from Limpakuwus stable, Baturraden Dairy Cattle Breeding Centre, Central Java Indonesia. Records were obtained from cows which started lactating on 2013 until the end of third lactation around the beginning of 2016. Milk yield from the first (L1), second (L2) and third (L3) lactations of 21 cows were recorded in kilograms. Samples were collected in 30 days basis interval started from the 10th day of lactation up to the 10th month. In this population, the cows first calving was around February – April 2013; while the second and third calving occurred all over the relevant year. The mean of milk yield for L1, L2 and L3 were 17.77±3.70, 16.09±5.17 and 13.73±4.02 Kg respectively. The peak of milk yields was achieved at the second month of the lactation for L1, L2 and L3. The persistency from the second to the tenth test days were 97, 93 and 94% for L1, L2 and L3, respectively. Milk yield persistency is representing ability of cow in maintain milk production after peak during lactation period. The more persistent shows better performance of dairy cattle as well as farm management. For that, persistency value could be used as valuable information in evaluating the management in Indonesian dairy farms.
Connectivity, cycles, and persistence thresholds in metapopulation networks.

Directory of Open Access Journals (Sweden)

Yael Artzy-Randrup

2010-08-01

Full Text Available Synthesising the relationships between complexity, connectivity, and the stability of large biological systems has been a longstanding fundamental quest in theoretical biology and ecology. With the many exciting developments in modern network theory, interest in these issues has recently come to the forefront in a range of multidisciplinary areas. Here we outline a new theoretical analysis specifically relevant for the study of ecological metapopulations focusing primarily on marine systems, where subpopulations are generally connected via larval dispersal. Our work determines the qualitative and quantitative conditions by which dispersal and network structure control the persistence of a set of age-structured patch populations. Mathematical modelling combined with a graph theoretic analysis demonstrates that persistence depends crucially on the topology of cycles in the dispersal network which tend to enhance the effect of larvae "returning home." Our method clarifies the impact directly due to network structure, but this almost by definition can only be achieved by examining the simplified case in which patches are identical; an assumption that we later relax. The methodology identifies critical migration routes, whose presence are vital to overall stability, and therefore should have high conservation priority. In contrast, "lonely links," or links in the network that do not participate in a cyclical component, have no impact on persistence and thus have low conservation priority. A number of other intriguing criteria for persistence are derived. Our modelling framework reveals new insights regarding the determinants of persistence, stability, and thresholds in complex metapopulations. In particular, while theoretical arguments have, in the past, suggested that increasing connectivity is a destabilizing feature in complex systems, this is not evident in metapopulation networks where connectivity, cycles, coherency, and heterogeneity all tend
Linear and Generalized Linear Mixed Models and Their Applications

CERN Document Server

Jiang, Jiming

2007-01-01

This book covers two major classes of mixed effects models, linear mixed models and generalized linear mixed models, and it presents an up-to-date account of theory and methods in analysis of these models as well as their applications in various fields. The book offers a systematic approach to inference about non-Gaussian linear mixed models. Furthermore, it has included recently developed methods, such as mixed model diagnostics, mixed model selection, and jackknife method in the context of mixed models. The book is aimed at students, researchers and other practitioners who are interested
Immunological aspects of persistent hepatitis B in children

Directory of Open Access Journals (Sweden)

Harsoyo Notoatmojo

2006-08-01

Full Text Available We studied the immunological status of 203 children having persistence Hepatitis B (positive HBsAg ranging in age from 6 to 14 years in Semarang Municipality. The results of humoral immunity examination (IgM Anti-HBc showed that all were negative, indicating that they are not in acute phase of hepatitis B infection. Cellular immunity examination, i.e., CMI skin test has shown positive result in 64.9% on persistent and 65.2% in non persistent hepatitis B (p>0.05. T cell examination showed statistically significant difference (p<0.01 between persistenct and non persistent hepatitis B patients, there was is also significant difference (p<0.01 on CD4 cell examination. These findings indicated that there was difference in immunoregulation function and response repression of antivirus between both groups of patients. On the other hand CD4/ CD8 ratio and T cell function showed no significant difference between the two gorups of patients; similarly the specific function of cytotoxic T cell was not significantly difference.
Immune Evasion Strategies and Persistence of Helicobacter pylori.

Science.gov (United States)

Mejías-Luque, Raquel; Gerhard, Markus

Helicobacter pylori infection is commonly acquired during childhood, can persist lifelong if not treated, and can cause different gastric pathologies, including chronic gastritis, peptic ulcer disease, and eventually gastric cancer. H. pylori has developed a number of strategies in order to cope with the hostile conditions found in the human stomach as well as successful mechanisms to evade the strong innate and adaptive immune responses elicited upon infection. Thus, by manipulating innate immune receptors and related signaling pathways, inducing tolerogenic dendritic cells and inhibiting effector T cell responses, H. pylori ensures low recognition by the host immune system as well as its persistence in the gastric epithelium. Bacterial virulence factors such as cytotoxin-associated gene A, vacuolating cytotoxin A, or gamma-glutamyltranspeptidase have been extensively studied in the context of bacterial immune escape and persistence. Further, the bacterium possesses other factors that contribute to immune evasion. In this chapter, we discuss in detail the main evasion and persistence strategies evolved by the bacterium as well as the specific bacterial virulence factors involved.
PAQ: Persistent Adaptive Query Middleware for Dynamic Environments

Science.gov (United States)

Rajamani, Vasanth; Julien, Christine; Payton, Jamie; Roman, Gruia-Catalin

Pervasive computing applications often entail continuous monitoring tasks, issuing persistent queries that return continuously updated views of the operational environment. We present PAQ, a middleware that supports applications' needs by approximating a persistent query as a sequence of one-time queries. PAQ introduces an integration strategy abstraction that allows composition of one-time query responses into streams representing sophisticated spatio-temporal phenomena of interest. A distinguishing feature of our middleware is the realization that the suitability of a persistent query's result is a function of the application's tolerance for accuracy weighed against the associated overhead costs. In PAQ, programmers can specify an inquiry strategy that dictates how information is gathered. Since network dynamics impact the suitability of a particular inquiry strategy, PAQ associates an introspection strategy with a persistent query, that evaluates the quality of the query's results. The result of introspection can trigger application-defined adaptation strategies that alter the nature of the query. PAQ's simple API makes developing adaptive querying systems easily realizable. We present the key abstractions, describe their implementations, and demonstrate the middleware's usefulness through application examples and evaluation.
Linear and non-linear energy barriers in systems of interacting single-domain ferromagnetic particles

International Nuclear Information System (INIS)

Petrila, Iulian; Bodale, Ilie; Rotarescu, Cristian; Stancu, Alexandru

2011-01-01

A comparative analysis between linear and non-linear energy barriers used for modeling statistical thermally-excited ferromagnetic systems is presented. The linear energy barrier is obtained by new symmetry considerations about the anisotropy energy and the link with the non-linear energy barrier is also presented. For a relevant analysis we compare the effects of linear and non-linear energy barriers implemented in two different models: Preisach-Neel and Ising-Metropolis. The differences between energy barriers which are reflected in different coercive field dependence of the temperature are also presented. -- Highlights: → The linear energy barrier is obtained from symmetry considerations. → The linear and non-linear energy barriers are calibrated and implemented in Preisach-Neel and Ising-Metropolis models. → The temperature and time effects of the linear and non-linear energy barriers are analyzed.
Persister formation in Staphylococcus aureus is associated with ATP depletion

Energy Technology Data Exchange (ETDEWEB)

Conlon, Brian P.; Rowe, Sarah E.; Gandt, Autumn Brown; Nuxoll, Austin S.; Donegan, Niles P.; Zalis, Eliza A.; Clair, Geremy; Adkins, Joshua N.; Cheung, Ambrose L.; Lewis, Kim

2016-04-18

Persisters are dormant phenotypic variants of bacterial cells that are tolerant to killing by antibiotics1. Persisters are associated with chronic bacterial infection and antibiotic treatment failure. In Escherichia coli, toxin/antitoxin (TA) modules are responsible for persister formation. The mechanism of persister formation in Gram positive bacteria is unknown. Staphylococcus aureus is a major human pathogen, responsible for a variety of chronic and relapsing infections such as osteomyelitis, endocarditis and infections of implanted devices. Deleting TA modules in S. aureus did not affect the level of persisters. Here we show that S. aureus persisters are produced due to a stochastic entrance to stationary phase accompanied by a drop in intracellular ATP. Cells expressing stationary state markers are present throughout the growth phase, increasing in frequency with cell density. Cell sorting revealed that expression of stationary markers was associated with a 100-1000 fold increased likelihood of survival to antibiotic challenge. We find that the antibiotic tolerance of these cells is due to a drop in intracellular ATP. The ATP level of the cell is predictive of bactericidal antibiotic efficacy and explains bacterial tolerance to antibiotic treatment.
Persistent increased PKMζ in long-term and remote spatial memory.

Science.gov (United States)

Hsieh, Changchi; Tsokas, Panayiotis; Serrano, Peter; Hernández, A Iván; Tian, Dezhi; Cottrell, James E; Shouval, Harel Z; Fenton, André Antonio; Sacktor, Todd Charlton

2017-02-01

PKMζ is an autonomously active PKC isoform that is thought to maintain both LTP and long-term memory. Whereas persistent increases in PKMζ protein sustain the kinase's action in LTP, the molecular mechanism for the persistent action of PKMζ during long-term memory has not been characterized. PKMζ inhibitors disrupt spatial memory when introduced into the dorsal hippocampus from 1day to 1month after training. Therefore, if the mechanisms of PKMζ's persistent action in LTP maintenance and long-term memory were similar, persistent increases in PKMζ would last for the duration of the memory, far longer than most other learning-induced gene products. Here we find that spatial conditioning by aversive active place avoidance or appetitive radial arm maze induces PKMζ increases in dorsal hippocampus that persist from 1day to 1month, coinciding with the strength and duration of memory retention. Suppressing the increase by intrahippocampal injections of PKMζ-antisense oligodeoxynucleotides prevents the formation of long-term memory. Thus, similar to LTP maintenance, the persistent increase in the amount of autonomously active PKMζ sustains the kinase's action during long-term and remote spatial memory maintenance. Copyright © 2016. Published by Elsevier Inc.
Linearity and Non-linearity of Photorefractive effect in Materials ...

African Journals Online (AJOL)

Linearity and Non-linearity of Photorefractive effect in Materials using the Band transport ... For low light beam intensities the change in the refractive index is ... field is spatially phase shifted by /2 relative to the interference fringe pattern, which ...
Linear integrated circuits

CERN Document Server

Carr, Joseph

1996-01-01

The linear IC market is large and growing, as is the demand for well trained technicians and engineers who understand how these devices work and how to apply them. Linear Integrated Circuits provides in-depth coverage of the devices and their operation, but not at the expense of practical applications in which linear devices figure prominently. This book is written for a wide readership from FE and first degree students, to hobbyists and professionals.Chapter 1 offers a general introduction that will provide students with the foundations of linear IC technology. From chapter 2 onwa

Persistent Model #2

DEFF Research Database (Denmark)

2013-01-01

Tensegrity structures and Inflatable membranes can be considered analogous. They can both be described as pressure based systems in which a coherent envelope is tensioned through compressive force in order to achieve a state of self-equilibrium. Persistent Model #2 is a full-scale speculative pro...... Modelling and a sustained critical investigation of the roles digital tools can play in extending the ways in which we think, design, realise and experience architecture....
Persistent fluctuations in stride intervals under fractal auditory stimulation.

Science.gov (United States)

Marmelat, Vivien; Torre, Kjerstin; Beek, Peter J; Daffertshofer, Andreas

2014-01-01

Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals.
Persisting nutritional neuropathy amongst former war prisoners.

OpenAIRE

Gill, G V; Bell, D R

1982-01-01

Of 898 former Far East prisoners of war, assessed between 1968 and 1981, 49 (5.5%) had evidence of persisting symptomatic neurological disease dating back to their periods of malnutrition in captivity. The commonest syndromes were peripheral neuropathy (often of "burning foot" type), optic atrophy, and sensori-neural deafness. Though nutritional neuropathies disappeared soon after release in most ex-Far East prisoners of war, in some they have persisted up to 36 years since exposure to the nu...
A minimally invasive option for the treatment of persistent ...

African Journals Online (AJOL)

. Hospital, King Saud ... We present two patients with persistent esophageal leak after compli- .... easy, and quite effective in the management of persistent ... 6 Rakocz M, Mazar A, Varon D, Spierer S, Blinder D, Martinowitz U. Dental extractions ...
Persistence drives gene clustering in bacterial genomes

Directory of Open Access Journals (Sweden)

Rocha Eduardo PC

2008-01-01

Full Text Available Abstract Background Gene clustering plays an important role in the organization of the bacterial chromosome and several mechanisms have been proposed to explain its extent. However, the controversies raised about the validity of each of these mechanisms remind us that the cause of this gene organization remains an open question. Models proposed to explain clustering did not take into account the function of the gene products nor the likely presence or absence of a given gene in a genome. However, genomes harbor two very different categories of genes: those genes present in a majority of organisms – persistent genes – and those present in very few organisms – rare genes. Results We show that two classes of genes are significantly clustered in bacterial genomes: the highly persistent and the rare genes. The clustering of rare genes is readily explained by the selfish operon theory. Yet, genes persistently present in bacterial genomes are also clustered and we try to understand why. We propose a model accounting specifically for such clustering, and show that indispensability in a genome with frequent gene deletion and insertion leads to the transient clustering of these genes. The model describes how clusters are created via the gene flux that continuously introduces new genes while deleting others. We then test if known selective processes, such as co-transcription, physical interaction or functional neighborhood, account for the stabilization of these clusters. Conclusion We show that the strong selective pressure acting on the function of persistent genes, in a permanent state of flux of genes in bacterial genomes, maintaining their size fairly constant, that drives persistent genes clustering. A further selective stabilization process might contribute to maintaining the clustering.
Real exchange rate persistence and the excess return puzzle

DEFF Research Database (Denmark)

Juselius, Katarina; Assenmacher, Katrin

2017-01-01

The PPP puzzle refers to the wide swings of nominal exchange rates around their long-run equilibrium values whereas the excess return puzzle represents the persistent deviation of the domestic-foreign interest rate differential from the expected change in the nominal exchange rate. Using the I(2......) cointegrated VAR model, much of the excess return puzzle disappears when an uncertainty premium in the foreign exchange market, proxied by the persistent PPP gap, is introduced. Self-reinforcing feedback mechanisms seem to cause the persistence in the Swiss-US parity conditions. These results support imperfect...
Postnatal persistent infection with classical Swine Fever virus and its immunological implications.

Directory of Open Access Journals (Sweden)

Sara Muñoz-González

Full Text Available It is well established that trans-placental transmission of classical swine fever virus (CSFV during mid-gestation can lead to persistently infected offspring. The aim of the present study was to evaluate the ability of CSFV to induce viral persistence upon early postnatal infection. Two litters of 10 piglets each were infected intranasally on the day of birth with low and moderate virulence CSFV isolates, respectively. During six weeks after postnatal infection, most of the piglets remained clinically healthy, despite persistent high virus titres in the serum. Importantly, these animals were unable to mount any detectable humoral and cellular immune response. At necropsy, the most prominent gross pathological lesion was a severe thymus atrophy. Four weeks after infection, PBMCs from the persistently infected seronegative piglets were unresponsive to both, specific CSFV and non-specific PHA stimulation in terms of IFN-γ-producing cells. These results suggested the development of a state of immunosuppression in these postnatally persistently infected pigs. However, IL-10 was undetectable in the sera of the persistently infected animals. Interestingly, CSFV-stimulated PBMCs from the persistently infected piglets produced IL-10. Nevertheless, despite the addition of the anti-IL-10 antibody in the PBMC culture from persistently infected piglets, the response of the IFN-γ producing cells was not restored. Therefore, other factors than IL-10 may be involved in the general suppression of the T-cell responses upon CSFV and mitogen activation. Interestingly, bone marrow immature granulocytes were increased and targeted by the virus in persistently infected piglets. Taken together, we provided the first data demonstrating the feasibility of CSFV in generating a postnatal persistent disease, which has not been shown for other members of the Pestivirus genus yet. Since serological methods are routinely used in CSFV surveillance, persistently infected pigs
Transient, but not persistent, adult food insecurity influences toddler development.

Science.gov (United States)

Hernandez, Daphne C; Jacknowitz, Alison

2009-08-01

In this study, we examined characteristics associated with experiencing persistent and transitional adult food insecurity and how persistent and transitional adult food insecurity influences toddler cognitive and motor development, along with toddler's weight and health status. Using the first 2 waves of the Early Childhood Longitudinal Study-Birth Cohort, 4 mutually exclusive variables capturing persistent and transitional adult food insecurity were created to capture those adults that experience adult food insecurity in the following: both waves, in 1 wave (at 9 or 24 mo after birth), and never experience food insecurity. We used logistic regression models to estimate characteristics associated with the likelihood of experiencing persistent and transitional adult food insecurity. Ordinary least squares regression models were used to estimate how persistent and transitional adult food insecurity influences toddler development. Similar factors influenced one's likelihood of experiencing adult transitional and persistent food insecurity; individuals who experienced any food insecurity were more economically disadvantaged. Thus, outreach efforts do not need to vary by duration of food insecurity. Whereas negative effects of food insecurity on school-aged children are found in the literature, it appears toddlers are buffered from the effects of persistent adult food insecurity. Our findings suggest that toddlers residing with a temporarily food-insecure adult compared with a never food-insecure adult experienced immediate, but small, negative effects on their development. Hence, outreach and assistance may lessen immediate impacts of food insecurity on toddler development.
Information persistence using XML database technology

Science.gov (United States)

Clark, Thomas A.; Lipa, Brian E. G.; Macera, Anthony R.; Staskevich, Gennady R.

2005-05-01

The Joint Battlespace Infosphere (JBI) Information Management (IM) services provide information exchange and persistence capabilities that support tailored, dynamic, and timely access to required information, enabling near real-time planning, control, and execution for DoD decision making. JBI IM services will be built on a substrate of network centric core enterprise services and when transitioned, will establish an interoperable information space that aggregates, integrates, fuses, and intelligently disseminates relevant information to support effective warfighter business processes. This virtual information space provides individual users with information tailored to their specific functional responsibilities and provides a highly tailored repository of, or access to, information that is designed to support a specific Community of Interest (COI), geographic area or mission. Critical to effective operation of JBI IM services is the implementation of repositories, where data, represented as information, is represented and persisted for quick and easy retrieval. This paper will address information representation, persistence and retrieval using existing database technologies to manage structured data in Extensible Markup Language (XML) format as well as unstructured data in an IM services-oriented environment. Three basic categories of database technologies will be compared and contrasted: Relational, XML-Enabled, and Native XML. These technologies have diverse properties such as maturity, performance, query language specifications, indexing, and retrieval methods. We will describe our application of these evolving technologies within the context of a JBI Reference Implementation (RI) by providing some hopefully insightful anecdotes and lessons learned along the way. This paper will also outline future directions, promising technologies and emerging COTS products that can offer more powerful information management representations, better persistence mechanisms and
Factors associated with persistent airflow limitation in severe asthma

NARCIS (Netherlands)

ten Brinke, A.; Zwinderman, A. H.; Sterk, P. J.; Rabe, K. F.; Bel, E. H.

2001-01-01

Persistent airflow limitation can develop in nonsmoking patients with asthma. However, the prevalence and risk factors for airways obstruction with incomplete reversibility in asthma are unknown. We assessed the prevalence of persistent airflow limitation (defined as postbronchodilator FEV(1) or
The relationship between crude oil spot and futures prices: Cointegration, linear and nonlinear causality

International Nuclear Information System (INIS)

Bekiros, Stelios D.; Diks, Cees G.H.

2008-01-01

The present study investigates the linear and nonlinear causal linkages between daily spot and futures prices for maturities of one, two, three and four months of West Texas Intermediate (WTI) crude oil. The data cover two periods October 1991-October 1999 and November 1999-October 2007, with the latter being significantly more turbulent. Apart from the conventional linear Granger test we apply a new nonparametric test for nonlinear causality by Diks and Panchenko after controlling for cointegration. In addition to the traditional pairwise analysis, we test for causality while correcting for the effects of the other variables. To check if any of the observed causality is strictly nonlinear in nature, we also examine the nonlinear causal relationships of VECM filtered residuals. Finally, we investigate the hypothesis of nonlinear non-causality after controlling for conditional heteroskedasticity in the data using a GARCH-BEKK model. Whilst the linear causal relationships disappear after VECM cointegration filtering, nonlinear causal linkages in some cases persist even after GARCH filtering in both periods. This indicates that spot and futures returns may exhibit asymmetric GARCH effects and/or statistically significant higher order conditional moments. Moreover, the results imply that if nonlinear effects are accounted for, neither market leads or lags the other consistently, videlicet the pattern of leads and lags changes over time. (author)
Engineering success: Undergraduate Latina women's persistence in an undergradute engineering program

Science.gov (United States)

Rosbottom, Steven R.

The purpose and focus of this narrative inquiry case study were to explore the personal stories of four undergraduate Latina students who persist in their engineering programs. This study was guided by two overarching research questions: a) What are the lived experiences of undergraduate Latina engineering students? b) What are the contributing factors that influence undergraduate Latina students to persist in an undergraduate engineering program? Yosso's (2005) community cultural wealth was used to the analyze data. Findings suggest through Yosso's (2005) aspirational capital, familial capital, social capital, navigational capital, and resistant capital the Latina student persisted in their engineering programs. These contributing factors brought to light five themes that emerged, the discovery of academic passions, guidance and support of family and teachers, preparation for and commitment to persistence, the power of community and collective engagement, and commitment to helping others. The themes supported their persistence in their engineering programs. Thus, this study informs policies, practices, and programs that support undergraduate Latina engineering student's persistence in engineering programs.
Amnestically Induced Persistence in Random Walks

Science.gov (United States)

Cressoni, J. C.; da Silva, Marco Antonio Alves; Viswanathan, G. M.

2007-02-01

We study how the Hurst exponent α depends on the fraction f of the total time t remembered by non-Markovian random walkers that recall only the distant past. We find that otherwise nonpersistent random walkers switch to persistent behavior when inflicted with significant memory loss. Such memory losses induce the probability density function of the walker’s position to undergo a transition from Gaussian to non-Gaussian. We interpret these findings of persistence in terms of a breakdown of self-regulation mechanisms and discuss their possible relevance to some of the burdensome behavioral and psychological symptoms of Alzheimer’s disease and other dementias.
The persistence in a Lotka-Volterra competition systems with impulsive

International Nuclear Information System (INIS)

Zhen Jin; Han Maoan; Li Guihua

2005-01-01

In this paper, a nonautonomous two-dimensional competitive Lotka-Volterra system with impulsive is considered. we study the persistence and extinction, giving two inequalities involving averages of the growth rates and impulsive value, which guarantees persistence of the system. An extension of the principle of competition exclusion is obtained in this paper. Moreover, several examples are also worked out, they show that the impulsive can change the persistence of the system
Effects of interferon on cultured cells persistently infected with viruses

Energy Technology Data Exchange (ETDEWEB)

Crespi, M

1986-01-01

The role of interferon (IFN) in viral persistence at the cellular level was investigated. Two types of persistent infections were chosen. The first type was cell lines which contained hepatitis B virus (HBV) DNA (PLC/PRF/5 and Hep 3B cells) uninfected control hepatoma cells, (Mahlavu, HA22T and Hep G2 cells) or simian virus 40 (SV40) DNA (C2, C6, C11 cells) and control uninfected (CV-1 cells). In the second type of infection Vero cells persistently infected with SSPE or Sendai virus were used. The aim of this work was to determine what effect IFN had in these infections in terms of its antiviral and antiproliferative effects; which of the two major IFN-induced pathways, E enzyme or protein kinase were induced; whether there were any differences in sensitivity to IFN between the DNA and RNA virus persistent infections. The anti-viral effect of IFN was examined by its ability to inhibit Sindbis virus replication using a radioimmunoassay system. The antiproliferative effect of IFN was determined by cell counting and /sup 3/H-thymidine incorporation. The activation of the ribonuclease F, determined by the inhibition of /sup 3/H-leucine incorporation after introduction of 2-5 actin into the cells, was variable, being activated in all cell lines with the exception of the PLC/PRF/5, Hep 3B and Hep G2 cells. Major differences between the two DNA persistent infections and the two RNA persistent infections were found. No correlation was found between the presence of HBV or SV40 persistent infections and the sensitivity of the cell lines to IFN. Both the SSPE and Sendai virus persistent infections were resistant to the antiviral and antiproliferative effect of IFN.
Persisting nutritional neuropathy amongst former war prisoners.

Science.gov (United States)

Gill, G V; Bell, D R

1982-01-01

Of 898 former Far East prisoners of war, assessed between 1968 and 1981, 49 (5.5%) had evidence of persisting symptomatic neurological disease dating back to their periods of malnutrition in captivity. The commonest syndromes were peripheral neuropathy (often of "burning foot" type), optic atrophy, and sensori-neural deafness. Though nutritional neuropathies disappeared soon after release in most ex-Far East prisoners of war, in some they have persisted up to 36 years since exposure to the nutritional insult. PMID:6292369
Long - Memory Persistence in African Stock Markets

Directory of Open Access Journals (Sweden)

Emmanuel Numapau Gyamfi

2016-05-01

Full Text Available Emerging stock markets are said to become efficient with time. This study seeks to investigate this assertion by analyzing long - memory persistence in 8 African stock markets covering the period from 28 August 2000 to 28 August 2015. The Hurst exponent is used as our efficiency measure which is evaluated by the Detrended Fluctuation Analysis (DFA. Our findings show strong evidence of long - memory persistence in the markets studied therefore violating the weak - form Efficient Market Hypothesis (EMH.
Remanent radiation fields around medical linear accelerators due to the induced radionuclides

International Nuclear Information System (INIS)

Sabol, J.; Khalifa, O.; Berka, Z.; Stankus, P.; Frencl, L.

1998-01-01

Radiation fields around two linear accelerators, Saturn 43 and a Saturn 2 Plus, installed at radiotherapy department is Prague, were measured and interpreted. The measurements included the determination of the dose equivalent rate resulting from photons emitted by induced radionuclides produced in reactions of high-energy photons with certain elements present in air and accelerator components as well as in the shielding and building materials in the treatment rooms, which are irradiated by high-energy X-rays, and due to radionuclides formed by capture of photoneutrons. While scattered photons and photoneutrons are only present during the accelerator operation, residual radioactivity creates a remanent radiation field persisting for some time after the instrument shutdown. The activity induced in the accessories is also an important source of exposure. (P.A.)
Persistence of airline accidents.

Science.gov (United States)

Barros, Carlos Pestana; Faria, Joao Ricardo; Gil-Alana, Luis Alberiko

2010-10-01

This paper expands on air travel accident research by examining the relationship between air travel accidents and airline traffic or volume in the period from 1927-2006. The theoretical model is based on a representative airline company that aims to maximise its profits, and it utilises a fractional integration approach in order to determine whether there is a persistent pattern over time with respect to air accidents and air traffic. Furthermore, the paper analyses how airline accidents are related to traffic using a fractional cointegration approach. It finds that airline accidents are persistent and that a (non-stationary) fractional cointegration relationship exists between total airline accidents and airline passengers, airline miles and airline revenues, with shocks that affect the long-run equilibrium disappearing in the very long term. Moreover, this relation is negative, which might be due to the fact that air travel is becoming safer and there is greater competition in the airline industry. Policy implications are derived for countering accident events, based on competition and regulation. © 2010 The Author(s). Journal compilation © Overseas Development Institute, 2010.
Persistence and extinction for a stochastic logistic model with infinite delay

Directory of Open Access Journals (Sweden)

Chun Lu

2013-11-01

Full Text Available This article, studies a stochastic logistic model with infinite delay. Using a phase space, we establish sufficient conditions for the extinction, nonpersistence in the mean, weak persistence, and stochastic permanence. A threshold between weak persistence and extinction is obtained. Our results state that different types of environmental noises have different effects on the persistence and extinction, and that the delay has no impact on the persistence and extinction for the stochastic model in the autonomous case. Numerical simulations illustrate the theoretical results.

Persistent fluctuations in stride intervals under fractal auditory stimulation

NARCIS (Netherlands)

Marmelat, V.C.M.; Torre, K.; Beek, P.J.; Daffertshofer, A.

2014-01-01

Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may
Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov–Casher effect

International Nuclear Information System (INIS)

Qiu, R.Z.; Chen, C.H.; Cheng, Y.H.; Hsueh, W.J.

2015-01-01

We propose strongly localized persistent spin current in one-dimensional defect-free quasiperiodic Thue–Morse rings with Aharonov–Casher effect. The results show that the characteristics of these localized persistent currents depend not only on the radius filling factor, but also on the strength of the spin–orbit interaction. The maximum persistent spin currents in systems always appear in the ring near the middle position of the system array whether or not the Thue–Morse rings array is symmetrical. The magnitude of the persistent currents is proportional to the sharpness of the resonance peak, which is dependent on the bandwidth of the allowed band in the band structure. The maximum persistent spin currents also increase exponentially as the generation order of the system increases. - Highlights: • Strongly localized persistent spin current in quasiperiodic AC rings is proposed. • Localized persistent spin currents are much larger than those produced by traditional mesoscopic rings. • Characteristics of the localized persistent currents depend on the radius filling factor and SOI strength. • The maximum persistent current increases exponentially with the system order. • The magnitude of the persistent currents is related to the sharpness of the resonance
On spurious anti-persistence in the US stock indices

International Nuclear Information System (INIS)

Kristoufek, Ladislav

2010-01-01

We reexamine the results of Serletis and Rosenberg [Serletis A, Rosenberg A. Mean reversion in the US stock market. Chaos, Solitons and Fractals 2009;40:2007-2015.] who claim that the returns of the most important US stock indices (DJI, NASDAQ, NYSE and S and P500) are strongly anti-persistent and thus mean reverting. We apply various methods to detect long-range dependence - detrending moving average, detrended fluctuation analysis, generalized Hurst exponent approach, classical rescaled range analysis and modified rescaled range analysis. We show that there are no signs of anti-persistence in any of the indices. Moreover, we discuss that the authors did not find any anti-persistence but rather showed returns of the said assets do not follow the scaling power law around their moving average with varying window length. Anti-persistence is thus spurious and due to wrong application of detrending moving average method.
The linear-non-linear frontier for the Goldstone Higgs

International Nuclear Information System (INIS)

Gavela, M.B.; Saa, S.; Kanshin, K.; Machado, P.A.N.

2016-01-01

The minimal SO(5)/SO(4) σ-model is used as a template for the ultraviolet completion of scenarios in which the Higgs particle is a low-energy remnant of some high-energy dynamics, enjoying a (pseudo) Nambu-Goldstone-boson ancestry. Varying the σ mass allows one to sweep from the perturbative regime to the customary non-linear implementations. The low-energy benchmark effective non-linear Lagrangian for bosons and fermions is obtained, determining as well the operator coefficients including linear corrections. At first order in the latter, three effective bosonic operators emerge which are independent of the explicit soft breaking assumed. The Higgs couplings to vector bosons and fermions turn out to be quite universal: the linear corrections are proportional to the explicit symmetry-breaking parameters. Furthermore, we define an effective Yukawa operator which allows a simple parametrization and comparison of different heavy-fermion ultraviolet completions. In addition, one particular fermionic completion is explored in detail, obtaining the corresponding leading low-energy fermionic operators. (orig.)
The linear-non-linear frontier for the Goldstone Higgs

Energy Technology Data Exchange (ETDEWEB)

Gavela, M.B.; Saa, S. [IFT-UAM/CSIC, Universidad Autonoma de Madrid, Departamento de Fisica Teorica y Instituto de Fisica Teorica, Madrid (Spain); Kanshin, K. [Universita di Padova, Dipartimento di Fisica e Astronomia ' G. Galilei' , Padua (Italy); INFN, Padova (Italy); Machado, P.A.N. [IFT-UAM/CSIC, Universidad Autonoma de Madrid, Departamento de Fisica Teorica y Instituto de Fisica Teorica, Madrid (Spain); Fermi National Accelerator Laboratory, Theoretical Physics Department, Batavia, IL (United States)

2016-12-15

The minimal SO(5)/SO(4) σ-model is used as a template for the ultraviolet completion of scenarios in which the Higgs particle is a low-energy remnant of some high-energy dynamics, enjoying a (pseudo) Nambu-Goldstone-boson ancestry. Varying the σ mass allows one to sweep from the perturbative regime to the customary non-linear implementations. The low-energy benchmark effective non-linear Lagrangian for bosons and fermions is obtained, determining as well the operator coefficients including linear corrections. At first order in the latter, three effective bosonic operators emerge which are independent of the explicit soft breaking assumed. The Higgs couplings to vector bosons and fermions turn out to be quite universal: the linear corrections are proportional to the explicit symmetry-breaking parameters. Furthermore, we define an effective Yukawa operator which allows a simple parametrization and comparison of different heavy-fermion ultraviolet completions. In addition, one particular fermionic completion is explored in detail, obtaining the corresponding leading low-energy fermionic operators. (orig.)
Thermal, Catalytic Conversion of Alkanes to Linear Aldehydes and Linear Amines.

Science.gov (United States)

Tang, Xinxin; Jia, Xiangqing; Huang, Zheng

2018-03-21

Alkanes, the main constituents of petroleum, are attractive feedstocks for producing value-added chemicals. Linear aldehydes and amines are two of the most important building blocks in the chemical industry. To date, there have been no effective methods for directly converting n-alkanes to linear aldehydes and linear amines. Here, we report a molecular dual-catalyst system for production of linear aldehydes via regioselective carbonylation of n-alkanes. The system is comprised of a pincer iridium catalyst for transfer-dehydrogenation of the alkane using t-butylethylene or ethylene as a hydrogen acceptor working sequentially with a rhodium catalyst for olefin isomerization-hydroformylation with syngas. The system exhibits high regioselectivity for linear aldehydes and gives high catalytic turnover numbers when using ethylene as the acceptor. In addition, the direct conversion of light alkanes, n-pentane and n-hexane, to siloxy-terminated alkyl aldehydes through a sequence of Ir/Fe-catalyzed alkane silylation and Ir/Rh-catalyzed alkane carbonylation, is described. Finally, the Ir/Rh dual-catalyst strategy has been successfully applied to regioselective alkane aminomethylation to form linear alkyl amines.
Improving persistence in red clover: Insights from QTL analysis and comparative phenotypic evaluation

DEFF Research Database (Denmark)

Herrmann, Dorris; Boller, Beat; Studer, Bruno

2008-01-01

, persistence is difficult to improve. The objectives of this study were to optimize the phenotypic evaluation of persistence, to identify quantitative trait loci (QTLs) for this important trait, and to investigate the association of persistence with other important traits. A weighted average of vigor scores...... assessed during two winters and three growing seasons was identified as the optimal method to phenotype persistence. For this index, one QTL explaining 12.2% of the total phenotypic variation was identified. While there was no negative correlation between persistence and seed yield, persistence...
Persistent toxic substances: sources, fates and effects.

Science.gov (United States)

Wong, Ming H; Armour, Margaret-Ann; Naidu, Ravi; Man, Ming

2012-01-01

Persistent toxic substances (PTS) include the Stockholm persistent organic pollutants, like dichlorodiphenyltrichloroethane, polychlorinated biphenyls, dioxin/furan, etc., and organometallic compounds, like organomercury, organotin, and organolead, which all share the same characteristics of being persistent, toxic, bioaccumulative, and able to travel long distances through different media. The adverse health effects of some of the emerging chemicals like pentabromodiphenyl ether, bisphenol A, and di(2-ethylhexyl)phthalate, which are widely used in daily appliances (e.g., TVs, computers, mobile phones, plastic baby bottles), have become a public health concern due to more evidence now available showing their adverse effects like disturbance of the endocrine system and cancer. This article is an attempt to review the current status of PTS in our environment, citing case studies in China and North America, and whether our existing drinking water treatment and wastewater treatment processes are adequate in removing them from water. Some management issues of these emerging chemicals of concern are also discussed.
Persistent Identifiers for Dutch cultural heritage institutions

Science.gov (United States)

Ras, Marcel; Kruithof, Gijsbert

2016-04-01

Over the past years, more and more collections belonging to archives, libraries, media, museums, and knowledge institutes are being digitised and made available online. These are exciting times for ALM institutions. They are realising that, in the information society, their collections are goldmines. Unfortunately most heritage institutions in the Netherlands do not yet meet the basic preconditions for long-term availability of their collections. The digital objects often have no long lasting fixed reference yet. URL's and web addresses change. Some digital objects that were referenced in Europeana and other portals can no longer be found. References in scientific articles have a very short life span, which is damaging for scholarly research. In 2015, the Dutch Digital Heritage Network (NDE) has started a two-year work program to co-ordinate existing initiatives in order to improve the (long-term) accessibility of the Dutch digital heritage for a wide range of users, anytime, anyplace. The Digital Heritage Network is a partnership established on the initiative of the Ministry of Education, Culture and Science. The members of the NDE are large, national institutions that strive to professionally preserve and manage digital data, e.g. the National Library, The Netherlands Institute for Sound and Vision, the Netherlands Cultural Heritage Agency, the Royal Netherlands Academy of Arts and Sciences, the National Archive of the Netherlands and the DEN Foundation, and a growing number of associations and individuals both within and outside the heritage sector. By means of three work programmes the goals of the Network should be accomplished and improve the visibility, the usability and the sustainability of digital heritage. Each programme contains of a set of projects. Within the sustainability program a project on creating a model for persistent identifiers is taking place. The main goals of the project are (1) raise awareness among cultural heritage institutions on the
Linear-Algebra Programs

Science.gov (United States)

Lawson, C. L.; Krogh, F. T.; Gold, S. S.; Kincaid, D. R.; Sullivan, J.; Williams, E.; Hanson, R. J.; Haskell, K.; Dongarra, J.; Moler, C. B.

1982-01-01

The Basic Linear Algebra Subprograms (BLAS) library is a collection of 38 FORTRAN-callable routines for performing basic operations of numerical linear algebra. BLAS library is portable and efficient source of basic operations for designers of programs involving linear algebriac computations. BLAS library is supplied in portable FORTRAN and Assembler code versions for IBM 370, UNIVAC 1100 and CDC 6000 series computers.
Long-term persistence of pioneer species in tropical forest soil seed banks

Energy Technology Data Exchange (ETDEWEB)

Dalling, J W; Brown, T A

2008-10-05

In tropical forests, pioneer species regenerate from seeds dispersed directly into canopy gaps, and from seeds that persisted in soil seed banks before gap formation. However, life-history models suggest that selection for long-term persistence of seeds in soil should be weak, as persistence incurs a fitness cost resulting from prolonged generation time. We use a carbon dating technique to provide the first direct measurements of seed persistence in undisturbed tropical forest seed banks. We show that seeds germinate successfully from surface soil microsites up to 38 years after dispersal. Decades-long persistence may be common in pioneers with relatively large mass, and appears to be unrelated to specific regeneration requirements. In Croton billbergianus, a sub-canopy tree that recruits in abundant small gaps, long-term persistence is associated with short-distance ballistic seed dispersal. In Trema micrantha, a canopy tree with widespread dispersal, persistence is associated with a requirement for large gaps that form infrequently in old-growth forest.
Persistent fluctuations in stride intervals under fractal auditory stimulation.

Directory of Open Access Journals (Sweden)

Vivien Marmelat

Full Text Available Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals.
Impact of innate and environmental factors on wheezing persistence during childhood.

Science.gov (United States)

Just, Jocelyne; Belfar, Samira; Wanin, Stéphanie; Pribil, Céline; Grimfeld, Alain; Duru, Gérard

2010-05-01

Persistent asthma in adults starts often early in childhood and is associated with alterations in respiratory function that occur early in life. The aim of this study was to evaluate the importance of innate and environmental factors associated with occurrence of asthma during childhood in a population of recurrent wheezing infants followed prospectively. A cohort of infants less than 30 months old with recurrent wheezing was established in order to assess severity of respiratory symptoms and to look for the presence of atopy and environmental risk factors. At the age of 6 years, they were reevaluated with respect to remission or persistence of wheezing over the previous 12-month period. Data were available for 219 subjects aged 15 +/- 5 months. In 27% of the infants with recurrent wheeze, wheezing persisted until the age of 6 years. In multivariate analysis, stepwise logit analysis showed that the risk factors for persistent wheezing are eosinophilia >or=470/mm(3), allergenic sensitization, and a father with asthma. Environmental factors present during the first year of life that protect from persistence of wheezing are ( 1 ) breastfeeding for longer than 3 months, ( 2 ) pets at home, and ( 3 ) >or=3 siblings. The detection rate for persistent wheezing in this model is 72%. The persistence score showed good specificity 91% but low sensitivity 35%. This study confirms the role of atopic host factors on wheezing persistence during childhood and detected protective environmental factors.
THE MOLECULAR MECHANISMS OF EPSTEINBARR VIRUS PERSISTENCE IN THE HUMAN ORGANISM

Directory of Open Access Journals (Sweden)

Volyanskiy A.Yu.

2014-12-01

Full Text Available This review describes advances in molecular aspects of EBV infection and disease. We discuss the spectrum of clinical illness due to EBV persistent infection. The main characteristic of Epstein-Barr virus (EBV is that initial infection results in lifelong persistence. EBV infects nearly all humans by the time they reach adulthood. Healthy humans have approximately 1 to 50 infected cells per million leukocytes. EBV is one of the eight known human herpesviruses. EBV virions have a doublestranded linear DNA and 100 genes had been described in virus genome. Initial infection is thought to occur in the oral compartment. The host cells of EBV are mainly lymphocytes and epithelial cells. EBV attaches to B cells via binding of the viral gp350 protein to CD21 receptor. The consequence of EBV infection is cells proliferation and differentiation into memory B lymphocyte in the germinal center. Infected memory B cells are released into the peripheral circulation. EBV persists mostly in the memory B cell. Latency is the state of persistent viral infection without active viral production. In latently infected B cells EBV virus exist as episomes. During the latent phase episomal replication occurs via host DNA polymerase. Genes of the nuclear antigens (EBNA and latent membrane proteins (LMP are transcribed during latency. These include EBNA1, EBNA2, EBNA3A, EBNA3B, EBNA3C, EBNA leader protein (EBNALP, LMP1 and LMP2 genes. All nuclear antigens are transcription transactivators which bind to cis-regulatory DNA elements of cell or virus genomes directly or in complex with other proteins. LMP2A and LMP1 can function to coordinately mimic B-cell receptor and CD40 coreceptor signaling in latently infected B cells. LMP proteins activate cell signaling systems and as the consequence different gene expression programs. Characterization of gene expression patterns in different cell lines and pathologic conditions has revealed that there are at least three different
Compensation of the Persistent Current Multipoles in the LHC Dipoles by making the Coil Protection Sheet from Soft Magnetic Material

CERN Document Server

Völlinger, C

2000-01-01

This note presents a scheme for compensating the persistent current multipole errors of the LHC dipoles by making the coil protection sheets from soft magnetic material of 0.5 mm thickness. The material properties assumed in this study are those of iron sheets with a very low content of impurities (99.99% pure Fe). The non-linearities in the upramp cycle on the b3 multipole component can be reduced by the factor of four (while decreasing the b5 variation by the factor of two. Using sheets of slightly different thicknesses offers a tuning possibility for the series magnet coils and can compensate deviations arising from cables of different suppliers. The calculation method is based on a semi-analytical hysteresis model for hard superconductors and an M(B) - iteration using the method of coupled boundary elements - finite elements (BEM - FEM). It is now possible to compute persistent current multipole errors of geometries with arbitrarily shaped iron yokes and thin layers of soft magnetic material such as tunin...
Lidocaine Patch (5%) in Treatment of Persistent Inguinal Postherniorrhaphy Pain

DEFF Research Database (Denmark)

Bischoff, Joakim M; Petersen, Marian; Uçeyler, Nurcan

2013-01-01

Evidence-based pharmacological treatment options for patients with persistent inguinal postherniorrhaphy pain are lacking.......Evidence-based pharmacological treatment options for patients with persistent inguinal postherniorrhaphy pain are lacking....
Model Predictive Control for Linear Complementarity and Extended Linear Complementarity Systems

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Bambang Riyanto

2005-11-01

Full Text Available In this paper, we propose model predictive control method for linear complementarity and extended linear complementarity systems by formulating optimization along prediction horizon as mixed integer quadratic program. Such systems contain interaction between continuous dynamics and discrete event systems, and therefore, can be categorized as hybrid systems. As linear complementarity and extended linear complementarity systems finds applications in different research areas, such as impact mechanical systems, traffic control and process control, this work will contribute to the development of control design method for those areas as well, as shown by three given examples.
O risco de incidência e persistência da obesidade entre adultos Brasileiros segundo seu estado nutricional ao final da adolescência The risk of incidence and persistence of obesity among Brazilian adults according to their nutritional status at the end of adolescence

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Wolney Lisboa Conde

2011-09-01

Full Text Available INTRODUÇÃO: A prevalência da obesidade vem aumentando entre adultos nos países desenvolvidos e em desenvolvimento. No Brasil, a obesidade entre adultos atingiu entre 2008 a 2009 pelo menos 10% da população. OBJETIVOS: Com base nos dados do VIGITEL, neste trabalho, serão estimadas a incidência e a persistência da obesidade entre brasileiros adultos no período de 2006 a 2009. MÉTODOS: Nas amostras de 2006 a 2009, foram utilizados casos com registros demográficos, socioeconômicos e antropométricos completos. As estimativas foram expandidas para a população brasileira em 2007. A estimativa do risco relativo (RR para incidência e persistência da obesidade ou excesso de peso entre homens e mulheres foi feita com regressão múltipla de Poisson, e ajustada para hábito de fumar, idade e atividade física. RESULTADOS: A incidência do excesso de peso entre indivíduos com peso baixo ou normal, aos 20 anos, é estimada em 40%, no sexo masculino, e em 30%, no feminino. A persistência da obesidade, por sua vez, é estimada em 65%, no sexo masculino, e em 47%, no feminino. O gradiente da obesidade como função da escolarização é virtualmente nulo no sexo masculino. Entre mulheres, o gradiente é negativo, com associações lineares e estatisticamente significantes. CONCLUSÃO: Essas características, associadas à forte expansão da obesidade entre adultos jovens detectada em outros estudos, apontam a urgência da utilização de políticas públicas mais incisivas e efetivas, que reduzam a exposição da população à alimentação com má qualidade nutricional e desenvolvam ações voltadas à promoção da atividade física.INTRODUCTION: The prevalence of obesity has increased among adults living in developed or developing countries. In Brazil, obesity among adults affected at least 10% of population from 2008 to 2009. OBJECTIVES: Based on data from VIGITEL, we will estimate the incidence and persistence of obesity among Brazilian
Assessing the persistence of pharmaceuticals in the aquatic environment: Challenges and needs

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Qingwei Bu

2016-09-01

Full Text Available Chemical’s persistence is known to be an important parameter applied for decades to identify persistent organic pollutants in hazard and/or risk assessments. Nevertheless it is greatly challenged in the case of emerging contaminants such as pharmaceuticals because the persistence of these chemicals could be more affected by environmental conditions. This fact brings more challenges to the current system for evaluating the persistence of chemical contaminants. In this paper, challenges in assessing the persistence of pharmaceuticals were identified, and more importantly research needs were addressed based on the existing data and knowledge.
Linear and quasi-linear equations of parabolic type

CERN Document Server

Ladyženskaja, O A; Ural′ceva, N N; Uralceva, N N

1968-01-01

Equations of parabolic type are encountered in many areas of mathematics and mathematical physics, and those encountered most frequently are linear and quasi-linear parabolic equations of the second order. In this volume, boundary value problems for such equations are studied from two points of view: solvability, unique or otherwise, and the effect of smoothness properties of the functions entering the initial and boundary conditions on the smoothness of the solutions.

Persistence of Salmonid Redds

Science.gov (United States)

Buffington, J. M.; Buxton, T.; Fremier, A. K.; Hassan, M. A.; Yager, E.

2013-12-01

The construction of redds by spawning salmonids modifies fluvial processes in ways that are beneficial to egg and embryo survival. Redd topography induces hyporheic flow that oxygenates embryos incubating within the streambed and creates form drag that reduces bed mobility and scour of salmonid eggs. Winnowing of fine material during redd construction also coarsens the streambed, increasing bed porosity and hyporheic flow and reducing bed mobility. In addition to the biological benefits, redds may influence channel morphology by altering channel hydraulics and bed load transport rates depending on the size and extent of redds relative to the size of the channel. A key question is how long do the physical and biological effects of redds last? Field observations indicate that in some basins redds are ephemeral, with redd topography rapidly erased by subsequent floods, while in other basins, redds can persist for years. We hypothesize that redd persistence is a function of basin hydrology, sediment supply, and characteristics of the spawning fish. Hydrology controls the frequency and magnitude of bed mobilizing flows following spawning, while bed load supply (volume and caliber) controls the degree of textural fining and consequent bed mobility after spawning, as well as the potential for burial of redd features. The effectiveness of flows in terms of their magnitude and duration depend on hydroclimate (i.e., snowmelt, rainfall, or transitional hydrographs), while bed load supply depends on basin geology, land use, and natural disturbance regimes (e.g., wildfire). Location within the stream network may also influence redd persistence. In particular, lakes effectively trap sediment and regulate downstream flow, which may promote long-lived redds in stream reaches below lakes. These geomorphic controls are modulated by biological factors: fish species (size of fish controls size of redds and magnitude of streambed coarsening); life history (timing of spawning and
Changes in persistence, spurious regressions and the Fisher hypothesis

DEFF Research Database (Denmark)

Kruse, Robinson; Ventosa-Santaulària, Daniel; Noriega, Antonio E.

Declining inflation persistence has been documented in numerous studies. When such series are analyzed in a regression framework in conjunction with other persistent time series, spurious regressions are likely to occur. We propose to use the coefficient of determination R2 as a test statistic to...
Rapid Elimination of the Persistent Synergid through a Cell Fusion Mechanism

KAUST Repository

Maruyama, Daisuke

2015-05-01

In flowering plants, fertilization-dependent degeneration of the persistent synergid cell ensures one-on-one pairings of male and female gametes. Here, we report that the fusion of the persistent synergid cell and the endosperm selectively inactivates the persistent synergid cell in Arabidopsis thaliana. The synergid-endosperm fusion causes rapid dilution of pre-secreted pollen tube attractant in the persistent synergid cell and selective disorganization of the synergid nucleus during the endosperm proliferation, preventing attractions of excess number of pollen tubes (polytubey). The synergid-endosperm fusion is induced by fertilization of the central cell, while the egg cell fertilization predominantly activates ethylene signaling, an inducer of the synergid nuclear disorganization. Therefore, two female gametes (the egg and the central cell) control independent pathways yet coordinately accomplish the elimination of the persistent synergid cell by double fertilization. Two female gametes (the egg cell and the central cell) in flowering plants coordinately prevent attractions of excess number of pollen tubes via two mechanisms to inactivate persistent synergid cell. © 2015 Elsevier Inc.
Coupling effect of nodes popularity and similarity on social network persistence.

Science.gov (United States)

Jin, Xiaogang; Jin, Cheng; Huang, Jiaxuan; Min, Yong

2017-02-21

Network robustness represents the ability of networks to withstand failures and perturbations. In social networks, maintenance of individual activities, also called persistence, is significant towards understanding robustness. Previous works usually consider persistence on pre-generated network structures; while in social networks, the network structure is growing with the cascading inactivity of existed individuals. Here, we address this challenge through analysis for nodes under a coevolution model, which characterizes individual activity changes under three network growth modes: following the descending order of nodes' popularity, similarity or uniform random. We show that when nodes possess high spontaneous activities, a popularity-first growth mode obtains highly persistent networks; otherwise, with low spontaneous activities, a similarity-first mode does better. Moreover, a compound growth mode, with the consecutive joining of similar nodes in a short period and mixing a few high popularity nodes, obtains the highest persistence. Therefore, nodes similarity is essential for persistent social networks, while properly coupling popularity with similarity further optimizes the persistence. This demonstrates the evolution of nodes activity not only depends on network topology, but also their connective typology.
Competitive inhibition can linearize dose-response and generate a linear rectifier.

Science.gov (United States)

Savir, Yonatan; Tu, Benjamin P; Springer, Michael

2015-09-23

Many biological responses require a dynamic range that is larger than standard bi-molecular interactions allow, yet the also ability to remain off at low input. Here we mathematically show that an enzyme reaction system involving a combination of competitive inhibition, conservation of the total level of substrate and inhibitor, and positive feedback can behave like a linear rectifier-that is, a network motif with an input-output relationship that is linearly sensitive to substrate above a threshold but unresponsive below the threshold. We propose that the evolutionarily conserved yeast SAGA histone acetylation complex may possess the proper physiological response characteristics and molecular interactions needed to perform as a linear rectifier, and we suggest potential experiments to test this hypothesis. One implication of this work is that linear responses and linear rectifiers might be easier to evolve or synthetically construct than is currently appreciated.
An Updated Global Picture of Cigarette Smoking Persistence among Adults

Science.gov (United States)

Troost, Jonathan P.; Barondess, David A.; Storr, Carla L.; Wells, J. Elisabeth; Al-Hamzawi, Ali Obaid; Andrade, Laura Helena; Bromet, Evelyn; Bruffaerts, Ronny; Florescu, Silvia; de Girolamo, Giovanni; de Graaf, Ron; Gureje, Oye; Haro, Josep Maria; Hu, Chiyi; Huang, Yueqin; Karam, Aimee N.; Kessler, Ronald C.; Lepine, Jean-Pierre; Matschinger, Herbert; Medina-Mora, Maria Elena; O'Neill, Siobhan; Posada-Villa, Jose; Sagar, Rajesh; Takeshima, Tadashi; Tomov, Toma; Williams, David R.; Anthony, James C.

2012-01-01

Background Cross-national variance in smoking prevalence is relatively well documented. The aim of this study is to estimate levels of smoking persistence across 21 countries with a hypothesized inverse relationship between country income level and smoking persistence. Methods Data from the World Health Organization World Mental Health Survey Initiative were used to estimate cross-national differences in smoking persistence–the proportion of adults who started to smoke and persisted in smoking by the date of the survey. Result There is large variation in smoking persistence from 25% (Nigeria) to 85% (China), with a random-effects meta-analytic summary estimate of 55% with considerable cross-national variation. (Cochran's heterogeneity Q statistic=6,845; p<0.001). Meta-regressions indicated observed differences are not attributable to differences in country income level, age distribution of smokers, or how recent the onset of smoking began within each country. Conclusion While smoking should remain an important public health issue in any country where smokers are present, this report identifies several countries with higher levels of smoking persistence (namely, China and India). PMID:23626929
Activated ClpP kills persisters and eradicates a chronic biofilm infection.

Energy Technology Data Exchange (ETDEWEB)

Conlon, Brian P.; Nakayasu, Ernesto S.; Fleck, Laura E.; LaFleur, Michael D.; Isabella, Vincent M.; Coleman, K.; Leonard, Steve N.; Smith, Richard D.; Adkins, Joshua N.; Lewis, Kim

2013-11-21

The current antibiotic crisis stems from two distinct phenomena-drug resistance, and drug tolerance. Resistance mechanisms such as drug efflux or modification prevent antibiotics from binding to their targets 1, allowing pathogens to grow. Antibiotic tolerance is the property of persister cells, phenotypic variants of regular bacteria 2. Antibiotics kill by corrupting targets, but these are inactive in dormant persisters, leading to tolerance. Persisters were first identified by Joseph Bigger in 1944, when he discovered a surviving sub-population of Staphylococcus following treatment with penicillin3. Persisters are largely responsible for recalcitrance of chronic diseases such as tuberculosis, and various infections associated with biofilms - endocarditis, osteomyelitis, infections of catheters and indwelling devices, and deep-seated infections of soft tissues 4. There are a number of redundant pathways involved in persister formation5,6 precluding development of drugs inhibiting their formation. The acyldepsipeptide antibiotic (ADEP 4) has been shown to activate the ClpP protease resulting in death of growing cells 7. Here we show that ADEP4 activated ClpP becomes a fairly non-specific protease and kills persister cells by degradation of over 400 intracellular targets. clpP mutants are resistant to ADEP4 7, but we find that they display increased susceptibility to killing by a range of conventional antibiotics. Combining ADEP4 with rifampicin leads to eradication of persisters, stationary and biofilm populations of Staphylococcus aureus in vitro and in a deep-seated murine infection. Target corruption/activation provides an approach to killing persisters and eradicating chronic infections.
Why They Stay: Women Persisting in US Engineering Careers

Science.gov (United States)

Buse, Kathleen; Bilimoria, Diana; Perelli, Sheri

2013-01-01

Purpose: Women remain dramatically underrepresented in the engineering profession and far fewer women than men persist in the field. This study aims to identify individual and contextual factors that distinguish women who persist in engineering careers in the US. Design/methodology/approach: Qualitative research was conducted based on…
PERSISTENCY ANALYSIS OF PARTICIPANTS OF PENSION PLANS

OpenAIRE

ROBERTA DE SOUZA CHUN

2007-01-01

O tema central deste trabalho é apresentar modelos de persistência. As probabilidades de persistência na carteira de um produto de determinada empresa de seguros e previdência serão estudadas de forma agregada, de tal forma que se torna possível a elaboração de outros estudos, como por exemplo, de análise de lucratividade, mesmo com poucos dados, o que inviabiliza a elaboração de tábuas de múltiplos decrementos. Serão avaliadas as possíveis causas de saí...
Environmental Persistence Influences Infection Dynamics for a Butterfly Pathogen.

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Dara A Satterfield

Full Text Available Many pathogens, including those infecting insects, are transmitted via dormant stages shed into the environment, where they must persist until encountering a susceptible host. Understanding how abiotic conditions influence environmental persistence and how these factors influence pathogen spread are crucial for predicting patterns of infection risk. Here, we explored the consequences of environmental transmission for infection dynamics of a debilitating protozoan parasite (Ophryocystis elektroscirrha that infects monarch butterflies (Danaus plexippus. We first conducted an experiment to observe the persistence of protozoan spores exposed to natural conditions. Experimental results showed that, contrary to our expectations, pathogen doses maintained high infectivity even after 16 days in the environment, although pathogens did yield infections with lower parasite loads after environmental exposure. Because pathogen longevity exceeded the time span of our experiment, we developed a mechanistic model to better explore environmental persistence for this host-pathogen system. Model analysis showed that, in general, longer spore persistence led to higher infection prevalence and slightly smaller monarch population sizes. The model indicated that typical parasite doses shed onto milkweed plants must remain viable for a minimum of 3 weeks for prevalence to increase during the summer-breeding season, and for 11 weeks or longer to match levels of infection commonly reported from the wild, assuming moderate values for parasite shedding rate. Our findings showed that transmission stages of this butterfly pathogen are long-lived and indicated that this is a necessary condition for the protozoan to persist in local monarch populations. This study provides a modeling framework for future work examining the dynamics of an ecologically important pathogen in an iconic insect.
Persistence Mechanisms of Conjugative Plasmids

DEFF Research Database (Denmark)

Bahl, Martin Iain; Hansen, Lars H.; Sørensen, Søren Johannes

2009-01-01

Are plasmids selfish parasitic DNA molecules or an integrated part of the bacterial genome? This chapter reviews the current understanding of the persistence mechanisms of conjugative plasmids harbored by bacterial cells and populations. The diversity and intricacy of mechanisms affecting the suc...
Sputum Neutrophilia in Severe Persistent Asthmatics

International Nuclear Information System (INIS)

Naseem, A.; Zaidi, S. B. H.; Liaqat, J.; Iftikhar, R.

2014-01-01

Objective: To determine the frequency of sputum neutrophilia in patients with severe persistent bronchial asthma. Study Design: A cross-sectional study. Place and Duration of Study: Department of Medicine, Military Hospital, Rawalpindi, from November 2009 to November 2010. Methodology: Cases of severe persistent bronchial asthma, aged between 12 and 40 years, were included. Sputum samples were collected by induction with hypertonic saline (4.5%). All samples were centrifuged and differential neutrophil count was calculated. Data was analyzed using SPSS 11. Results: Out of 195 patients, there were 129 (66.2%) males and 66 (33.8%) females. The mean age was 27.01 A +- 6.92 years. Mean sputum neutrophilic count was 126.47 A +- 16.52 x 106/ml and the mean neutrophilic percentage was 63.187 A +- 8.3363. Sputum neutrophilia was present in 84 patients (43.1%), out of whom, 56 were males and 28 females. In patients with sputum neutrophilia, mean neutrophilic count was 142.40 A +- 8.49 x 106/ml and the mean neutrophilic percentage was 71.2024 A +- 4.2441%. Conclusion: Sputum neutrophilia is a frequent finding in cases with severe persistent bronchial asthma. Presence of sputum neutrophilia in such cases can lessen the inappropriate use of corticosteroids with their associated long-term side effects. (author)
Atmospheric circulation associated with extreme generalized frosts persistence in central-southern South America

Energy Technology Data Exchange (ETDEWEB)

Mueller, Gabriela V. [Centro de Investigaciones Cientificas y Transferencia de Tecnologia a la Produccion, Diamante (CICYTTTP-CONICET), Diamante, Entre Rios (Argentina); Berri, Guillermo J. [Servicio Meteorologico Nacional - CONICET, Buenos Aires (Argentina)

2012-03-15

Generalized frosts (GF) in central-southern South America have a strong impact due to their spatial extension, and they are especially important when they become persistent. This paper aims at identifying the atmospheric circulation features that determine the extreme GF persistence, i.e. very persistent and without persistence, and the differences between them, during the 1961-1990 winters. Since the GF without persistence group outnumbers the other one, two subgroups are composed with events selected from winters with maximum and minimum frequency of GF occurrence, respectively. Additionally, the individual event of July 1988 within the very persistent GF group is analyzed due to its exceptional persistence. GF persistence is mainly conditioned by two large-scale dynamic factors. One is the Rossby wave train propagation across the Pacific Ocean, and the other one is the location with respect to the continent and the magnitude of the confluence in the jet entrance region in subtropical latitudes. A predominantly meridional Rossby wave train propagation with a confluence region to the west of the continent prior to the event favors GF with intermediate (null) persistence depending on the greater (lesser) jet acceleration. This is conditioned by the magnitude of the confluence, which, in turn, depends on the disposition of the wave train propagation pattern. Instead, an essentially zonal propagation with a confluence region to the east of the continent favors the GF persistence for several days, yet if there is no confluence the event does not persist. The greatest persistence of an event combines the confluence/diffluence of the jet entrance/exit region, which depends on the disposition with respect to the continent of the zonally propagating Rossby wave trains. (orig.)
Linear versus non-linear structural information limit in high-resolution transmission electron microscopy

International Nuclear Information System (INIS)

Van Aert, S.; Chen, J.H.; Van Dyck, D.

2010-01-01

A widely used performance criterion in high-resolution transmission electron microscopy (HRTEM) is the information limit. It corresponds to the inverse of the maximum spatial object frequency that is linearly transmitted with sufficient intensity from the exit plane of the object to the image plane and is limited due to partial temporal coherence. In practice, the information limit is often measured from a diffractogram or from Young's fringes assuming a weak phase object scattering beyond the inverse of the information limit. However, for an aberration corrected electron microscope, with an information limit in the sub-angstrom range, weak phase objects are no longer applicable since they do not scatter sufficiently in this range. Therefore, one relies on more strongly scattering objects such as crystals of heavy atoms observed along a low index zone axis. In that case, dynamical scattering becomes important such that the non-linear and linear interaction may be equally important. The non-linear interaction may then set the experimental cut-off frequency observed in a diffractogram. The goal of this paper is to quantify both the linear and the non-linear information transfer in terms of closed form analytical expressions. Whereas the cut-off frequency set by the linear transfer can be directly related with the attainable resolution, information from the non-linear transfer can only be extracted using quantitative, model-based methods. In contrast to the historic definition of the information limit depending on microscope parameters only, the expressions derived in this paper explicitly incorporate their dependence on the structure parameters as well. In order to emphasize this dependence and to distinguish from the usual information limit, the expressions derived for the inverse cut-off frequencies will be referred to as the linear and non-linear structural information limit. The present findings confirm the well-known result that partial temporal coherence has
Electronic States and Persistent Currents in Nanowire Quantum Ring

Science.gov (United States)

Kokurin, I. A.

2018-04-01

The new model of a quantum ring (QR) defined inside a nanowire (NW) is proposed. The one-particle Hamiltonian for electron in [111]-oriented NW QR is constructed taking into account both Rashba and Dresselhaus spin-orbit coupling (SOC). The energy levels as a function of magnetic field are found using the exact numerical diagonalization. The persistent currents (both charge and spin) are calculated. The specificity of SOC and arising anticrossings in energy spectrum lead to unusual features in persistent current behavior. The variation of magnetic field or carrier concentration by means of gate can lead to pure spin persistent current with the charge current being zero.
Linearization of the Lorenz system

International Nuclear Information System (INIS)

Li, Chunbiao; Sprott, Julien Clinton; Thio, Wesley

2015-01-01

A partial and complete piecewise linearized version of the Lorenz system is proposed. The linearized versions have an independent total amplitude control parameter. Additional further linearization leads naturally to a piecewise linear version of the diffusionless Lorenz system. A chaotic circuit with a single amplitude controller is then implemented using a new switch element, producing a chaotic oscillation that agrees with the numerical calculation for the piecewise linear diffusionless Lorenz system. - Highlights: • A partial and complete piecewise linearized version of the Lorenz system are addressed. • The linearized versions have an independent total amplitude control parameter. • A piecewise linear version of the diffusionless Lorenz system is derived by further linearization. • A corresponding chaotic circuit without any multiplier is implemented for the chaotic oscillation
Linearization of the Lorenz system

Energy Technology Data Exchange (ETDEWEB)

Li, Chunbiao, E-mail: goontry@126.com [School of Electronic & Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Engineering Technology Research and Development Center of Jiangsu Circulation Modernization Sensor Network, Jiangsu Institute of Commerce, Nanjing 211168 (China); Sprott, Julien Clinton [Department of Physics, University of Wisconsin–Madison, Madison, WI 53706 (United States); Thio, Wesley [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210 (United States)

2015-05-08

A partial and complete piecewise linearized version of the Lorenz system is proposed. The linearized versions have an independent total amplitude control parameter. Additional further linearization leads naturally to a piecewise linear version of the diffusionless Lorenz system. A chaotic circuit with a single amplitude controller is then implemented using a new switch element, producing a chaotic oscillation that agrees with the numerical calculation for the piecewise linear diffusionless Lorenz system. - Highlights: • A partial and complete piecewise linearized version of the Lorenz system are addressed. • The linearized versions have an independent total amplitude control parameter. • A piecewise linear version of the diffusionless Lorenz system is derived by further linearization. • A corresponding chaotic circuit without any multiplier is implemented for the chaotic oscillation.
Lactase persistence genotypes and malaria susceptibility in Fulani of Mali

Directory of Open Access Journals (Sweden)

Dolo Amagana

2011-01-01

Full Text Available Abstract Background Fulani are a widely spread African ethnic group characterized by lower susceptibility to Plasmodium falciparum, clinical malaria morbidity and higher rate of lactase persistence compared to sympatric tribes. Lactase non-persistence, often called lactose intolerance, is the normal condition where lactase activity in the intestinal wall declines after weaning. Lactase persistence, common in Europe, and in certain African people with traditions of raising cattle, is caused by polymorphisms in the enhancer region approximately 14 kb upstream of the lactase gene. Methods To evaluate the relationship between malaria and lactase persistence genotypes, a 400 bp region surrounding the main European C/T-13910 polymorphism upstream of the lactase gene was sequenced. DNA samples used in the study originated from 162 Fulani and 79 Dogon individuals from Mali. Results Among 79 Dogon only one heterozygote of the lactase enhancer polymorphism was detected, whereas all others were homozygous for the ancestral C allele. Among the Fulani, the main European polymorphism at locus C/T-13910 was by far the most common polymorphism, with an allele frequency of 37%. Three other single-nucleotide polymorphisms were found with allele frequencies of 3.7%, 1.9% and 0.6% each. The novel DNA polymorphism T/C-13906 was seen in six heterozygous Fulani. Among the Fulani with lactase non-persistence CC genotypes at the C/T-13910 locus, 24% had malaria parasites detectable by microscopy compared to 18% for lactase persistent genotypes (P = 0.29. Pooling the lactase enhancer polymorphisms to a common presumptive genotype gave 28% microscopy positives for non-persistent and 17% for others (P = 0.11. Conclusions Plasmodium falciparum parasitaemia in asymptomatic Fulani is more common in individuals with lactase non-persistence genotypes, but this difference is not statistically significant. The potential immunoprotective properties of dietary cow milk as a reason
Persistent fetal vasculature: ocular features, management of cataract and outcomes

Directory of Open Access Journals (Sweden)

Marcia Beatriz Tartarella

2013-06-01

Full Text Available PURPOSES: To describe ocular features, management of cataract and functional outcomes in patients with persistent fetal vasculature. METHODS: Retrospective, descriptive case series of patients with persistent fetal vasculature. Data were recorded from the Congenital Cataract Section of Federal University of São Paulo, Brazil from 2001 to 2012. All patients were evaluated for sex, age at diagnosis, systemic findings, laterality, age at surgery, and initial and final follow-up visual acuities. Follow-up and complications after cataract surgery were recorded. Ultrasound was performed in all cases and ocular eco-Doppler was performed in most. RESULTS: The study comprised 53 eyes from 46 patients. Age at diagnosis ranged from 5 days of life to 10 years-old (mean 22.7 months. Twenty-seven patients were male (58.7%. Persistent fetal vasculature was bilateral in 7 patients (15.2%. Forty-two eyes (79.2% had combined (anterior and posterior forms PFV presentation, 5 eyes (9.4% had only anterior persistent fetal vasculature presentation and 6 eyes (11.3% had posterior persistent fetal vasculature presentation. Thirty-eight eyes (71.7% were submitted to cataract surgery. Lensectomy combined with anterior vitrectomy was performed in 18 eyes (47.4%. Phacoaspiration with intraocular lens implantation was performed in 15 eyes (39.5%, and without lens implantation in 5 eyes (13.2%. Mean follow-up after surgery was 44 months. Postoperative complications were posterior synechiae (3 cases, retinal detachment (2 cases, phthisis (3 cases, posterior capsular opacification (8 cases, inflammatory pupillary membrane (5 cases, glaucoma (4 cases, intraocular lens implantation displacement (1 case and vitreous hemorrhage (2 cases. Complications were identified in 19 (50% of the 38 operated eyes. Visual acuity improved after cataract surgery in 83% of the eyes. CONCLUSIONS: Patients with persistent fetal vasculature have variable clinical presentation. There is an
PERSISTENCE AND ACADEMIC ACHIEVEMENT IN FOREIGN LANGUAGE IN NATURAL SCIENCES STUDENTS

Directory of Open Access Journals (Sweden)

Alexandr I Krupnov

2017-12-01

Full Text Available The article discusses the results of empirical study of the association between variables of persistence and academic achievement in foreign languages. The sample includes students of the Faculty of Physics, Mathematics and Natural Science at the RUDN University ( n = 115, divided into 5 subsamples, two of which are featured in the present study (the most and the least successful students subsamples. Persistence as a personality trait is studied within A.I. Krupnov’s system-functional approach. A.I. Krupnov’s paper-and-pencil test was used to measure persistence variables. Academic achievement was measured according to the four parameters: Phonetics, Grammar, Speaking and Political vocabulary based on the grades students received during the academic year. The analysis revealed that persistence displays different associations with academic achievement variables in more and less successful students subsamples, the general prominence of this trait is more important for unsuccessful students. Phonetics is the academic achievement variable most associated with persistence due to its nature, a skill one can acquire through hard work and practice which is the definition of persistence. Grammar as an academic achievement variable is not associated with persistence and probably relates to other factors. Unsuccessful students may have difficulties in separating various aspects of language acquisition from each other which should be taken into consideration by the teachers.

Classifying Linear Canonical Relations

OpenAIRE

Lorand, Jonathan

2015-01-01

In this Master's thesis, we consider the problem of classifying, up to conjugation by linear symplectomorphisms, linear canonical relations (lagrangian correspondences) from a finite-dimensional symplectic vector space to itself. We give an elementary introduction to the theory of linear canonical relations and present partial results toward the classification problem. This exposition should be accessible to undergraduate students with a basic familiarity with linear algebra.
Linearity enigmas in ecology

Energy Technology Data Exchange (ETDEWEB)

Patten, B.C.

1983-04-01

Two issues concerning linearity or nonlinearity of natural systems are considered. Each is related to one of the two alternative defining properties of linear systems, superposition and decomposition. Superposition exists when a linear combination of inputs to a system results in the same linear combination of outputs that individually correspond to the original inputs. To demonstrate this property it is necessary that all initial states and inputs of the system which impinge on the output in question be included in the linear combination manipulation. As this is difficult or impossible to do with real systems of any complexity, nature appears nonlinear even though it may be linear. A linear system that displays nonlinear behavior for this reason is termed pseudononlinear. The decomposition property exists when the dynamic response of a system can be partitioned into an input-free portion due to state plus a state-free portion due to input. This is a characteristic of all linear systems, but not of nonlinear systems. Without the decomposition property, it is not possible to distinguish which portions of a system's behavior are due to innate characteristics (self) vs. outside conditions (environment), which is an important class of questions in biology and ecology. Some philosophical aspects of these findings are then considered. It is suggested that those ecologists who hold to the view that organisms and their environments are separate entities are in effect embracing a linear view of nature, even though their belief systems and mathematical models tend to be nonlinear. On the other hand, those who consider that organism-environment complex forms a single inseparable unit are implictly involved in non-linear thought, which may be in conflict with the linear modes and models that some of them use. The need to rectify these ambivalences on the part of both groups is indicated.
Mössbauer spectra linearity improvement by sine velocity waveform followed by linearization process

Science.gov (United States)

Kohout, Pavel; Frank, Tomas; Pechousek, Jiri; Kouril, Lukas

2018-05-01

This note reports the development of a new method for linearizing the Mössbauer spectra recorded with a sine drive velocity signal. Mössbauer spectra linearity is a critical parameter to determine Mössbauer spectrometer accuracy. Measuring spectra with a sine velocity axis and consecutive linearization increases the linearity of spectra in a wider frequency range of a drive signal, as generally harmonic movement is natural for velocity transducers. The obtained data demonstrate that linearized sine spectra have lower nonlinearity and line width parameters in comparison with those measured using a traditional triangle velocity signal.
The Infection Efficiency and Replication Ability of Circularized HBV DNA Optimized the Linear HBV DNA in Vitro and in Vivo

Science.gov (United States)

Li, Xiaosong; Zhu, Junke; Lai, Guoqi; Yan, Lei; Hu, Jieli; Chen, Juan; Tang, Ni; Huang, Ailong

2015-01-01

Studies on molecular mechanisms of the persist infection of hepatitis B virus have been hampered by a lack of a robust animal model. We successfully established a simple, versatile, and reproducible HBV persist infection model in vitro and in vivo with the circularized HBV DNA. The cells and mice were transfected or injected with circularized HBV DNA and pAAV/HBV1.2, respectively. At the indicated time, the cells, supernatants, serum samples, and liver tissues were collected for virological and serological detection. Both in vitro and in vivo, the circularized HBV DNA and pAAV/HBV1.2 could replicate and transcribe efficiently, but the infection effect of the former was superior to the latter (p HBV genome DNA into the mice robustly supported HBV infection and approximately 80% of HBV infected mice established persistent infection for at least 10 weeks. This study demonstrated that the infection efficiency and replication ability of the circularized structure of HBV DNA overmatched that of the expression plasmid containing the linear structure of HBV DNA in vitro and in vivo. Meanwhile, this research results could provide useful tools and methodology for further study of pathogenic mechanisms and potential antiviral treatments of human chronic HBV infection in vitro and in vivo. PMID:25751726
Multilevel lumbar fusion and postoperative physiotherapy rehabilitation in a patient with persistent pain.

Science.gov (United States)

Pons, Tracey; Shipton, Edward A

2011-04-01

There are no comparative randomised controlled trials of physiotherapy modalities for chronic low back and radicular pain associated with multilevel fusion. Physiotherapy-based rehabilitation to control pain and improve activation levels for persistent pain following multilevel fusion can be challenging. This is a case report of a 68-year-old man who was referred for physiotherapy intervention 10 months after a multilevel spinal fusion for spinal stenosis. He reported high levels of persistent postoperative pain with minimal activity as a consequence of his pain following the surgery. The physiotherapy interventions consisted of three phases of rehabilitation starting with pool exercise that progressed to land-based walking. These were all combined with transcutaneous electrical nerve stimulation (TENS) that was used consistently for up to 8 hours per day. As outcome measures, daily pain levels and walking distances were charted once the pool programme was completed (in the third phase). Phase progression was determined by shuttle test results. The pain level was correlated with the distance walked using linear regression over a 5-day average. Over a 5-day moving average, the pain level reduced and walking distance increased. The chart of recorded pain level and walking distance showed a trend toward decreased pain with the increased distance walked. In a patient undergoing multilevel lumbar fusion, the combined use of TENS and a progressive walking programme (from pool to land) reduced pain and increased walking distance. This improvement was despite poor medication compliance and a reported high level of postsurgical pain.
Reactivity-induced time-dependencies of EBR-II linear and non-linear feedbacks

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1988-01-01

Time-dependent linear feedback reactivities are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a kinetic code analysis of an experiment in which the change in power resulted from the dropping of a control rod. Shown with these linear reactivities are the reactivity associated with the control-rod shaft contraction and also time-dependent non-linear (mainly bowing) component deduced from the inverse kinetics of the experimentally measured fission power and the calculated linear reactivities. (author)
Bioindicator demonstrates high persistence of sulfentrazone in dry soil

Directory of Open Access Journals (Sweden)

Renato Coradello Lourenço

2015-09-01

Full Text Available In sugarcane crop areas, the application of preemergence herbicides with long residual effect in the soil has been frequently necessary. The herbicide persistence in the soil must be high especially because of applications during the dry season of the year, after sugarcane harvest. This study aimed at estimating the sulfentrazone persistence and dissipation in dry soil using bioindicator. Five experiments were carried out, divided into two phases. In the first phase, three dose-response curves were adjusted to select the best bioindicator to be adopted in the second phase. Niger was adopted due to its lower sensibility to sulfentrazone. In the second phase, a new dose-response curve was carried out, with six doses of sulfentrazone, in order to standardize the bioindicator sensibility to sulfentrazone. At the end, another experiment with six periods of sulfentrazone persistence in dry clay soil was developed. Persistence periods were: 182, 154, 125, 98 and 30 days. The bioindicator was seeded at the application day in treated plots and control. In this experiment, the sulfentrazone dose applied was 800 g ha-1. Niger was considered a good species to estimate the sulfentrazone persistence in dry soil. The sulfentrazone phytotoxic activity was identified up to 182 days after application, and its average dissipation rate was 2.15 g ha-1 day-1, with half-life higher than 182 days.
Overview of persistent pain in older adults.

Science.gov (United States)

Molton, Ivan R; Terrill, Alexandra L

2014-01-01

With the shifting age demographics of the U.S. population, more psychologists will be asked to provide clinical services to older adults. Given the high prevalence of persistent pain in aging, in many cases this will mean providing empirically supported interventions for pain and the interference it creates. The purpose of this review is to provide a broad overview of the scope and impact of persistent pain in older people and to discuss mechanisms by which persistent geriatric pain can lead to suffering and disability. We consider the unique context of pain in older adulthood and review differences between older and younger people in terms of pain perception, the social network, beliefs about pain, pain-related coping, and adherence to pain medication. Finally, we discuss special issues affecting pain management in older adults, including dementia, polypharmacy, and barriers to accessing adequate pain care. This review also highlights a need for greater provider training in pain management to meet the needs of a changing U.S. population. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Trustworthy persistent identifier systems of the future

Science.gov (United States)

Golodoniuc, Pavel; Klump, Jens; Car, Nicholas

2016-04-01

Over the last two decades, persistent identifier (PID) systems have seen some significant changes in their governance policies, system capabilities, and technology. The development of most systems was driven by two main application areas, namely archives and libraries. Guidelines and criteria for trustworthy PID systems have been clearly devised (Bütikofer, 2009) and many PID system implementations for the identification of static digital objects have been built (e.g., PURL). However systems delivering persistent identifiers for dynamic datasets are not yet mature. There has been a rapid proliferation of different PID systems caused by the specific technical or organisational requirements of various communities that could not be met by existing systems such as DOI, ISBN, and EAN. Many of these different systems were limited by their inability to provide native means of persistent identifier resolution. This has prompted a decoupling of PID-associated data from the resolution service and this is where the Handle system has played a significant role. The Handle allowed to build a distributed system of independently managed resolver services. A trustworthy PID system must be designed to outlive the objects it provides persistent identifiers for, which may cease to exist or otherwise be deprecated, and the technology used to implement it, which will certainly need to change with time. We propose that such a system should rest on four pillars of agreements - (i) definitions, (ii) policies, (iii) services, and (iv) data services, to ensure longevity. While we believe all four pillars are equally important, we intentionally leave regulating aspects of issuing of identifiers and their registration out of the scope of this paper and focus on the agreements that have to be established between PID resolver services and the data sources indicated by the persistent identifiers. We propose an approach to development of PID systems that combines the use of (a) the Handle system
Persistent phosphors for painting, medical and biological applications

International Nuclear Information System (INIS)

Nazarov, M.

2013-01-01

Multiphase micro and nanoparticle persistent phosphors are synthesized and applied for different fields including painting, medical and biological investigations. A lot of examples show a broad range of applications of persistent luminescence from bulk materials to high tech products, especially in medicine. The development of high efficiency nanosized phosphor makes it possible to propose persistent materials as very good candidates for photodynamic therapy of cancer. An artificial block from slag, concrete, and sand covered with SrAl 2 O 4 :Eu 2+ , Dy 3+ based phosphor is prepared, and a new direction in biology for algae cultivation and artificial reef is discussed. For the first time, underwater luminescence is experimentally studied under real sea conditions. Bright blue-green long-lasting afterglow is registered at a depth of 5 m. The fishes are attracted by the light of the artificial reef. (author)
Saffold Virus Type 3 (SAFV-3) Persists in HeLa Cells

Science.gov (United States)

Himeda, Toshiki; Hosomi, Takushi; Okuwa, Takako; Muraki, Yasushi; Ohara, Yoshiro

2013-01-01

Saffold virus (SAFV) was identified as a human cardiovirus in 2007. Although several epidemiological studies have been reported, they have failed to provide a clear picture of the relationship between SAFV and human diseases. SAFV genotype 3 has been isolated from the cerebrospinal fluid specimen of patient with aseptic meningitis. This finding is of interest since Theiler’s murine encephalomyelitis virus (TMEV), which is the closely related virus, is known to cause a multiple sclerosis-like syndrome in mice. TMEV persistently infects in mouse macrophage cells in vivo and in vitro, and the viral persistence is essential in TMEV-induced demyelinating disease. The precise mechanism(s) of SAFV infection still remain unclear. In order to clarify the SAFV pathogenicity, in the present study, we studied the possibilities of the in vitro persistent infection of SAFV. The two distinct phenotypes of HeLa cells, HeLa-N and HeLa-R, were identified. In these cells, the type of SAFV-3 infection was clearly different. HeLa-N cells were lyticly infected with SAFV-3 and the host suitable for the efficient growth. On the other hand, HeLa-R cells were persistently infected with SAFV-3. In addition, the SAFV persistence in HeLa-R cells is independent of type I IFN response of host cells although the TMEV persistence in mouse macrophage cells depends on the response. Furthermore, it was suggested that SAFV persistence may be influenced by the expression of receptor(s) for SAFV infection on the host cells. The present findings on SAFV persistence will provide the important information to encourage the research of SAFV pathogenicity. PMID:23308162
The impact of GI events on persistence and adherence to osteoporosis treatment: 3-, 6-, and 12-month findings in the MUSIC-OS study.

Science.gov (United States)

Modi, A; Sen, S; Adachi, J D; Adami, S; Cortet, B; Cooper, A L; Geusens, P; Mellström, D; Weaver, J P; van den Bergh, J P; Keown, P; Sajjan, S

2018-02-01

The goal of this multinational, prospective, observational study was to examine the relationship between gastrointestinal (GI) events and self-reported levels of medication adherence and persistence in postmenopausal women. A total of 73.9% of patients remained on their osteoporosis (OP) therapy at month 12, although the presence of a GI event at baseline, month 3, and month 6 significantly reduced month 12 persistence among new users. The odds of a month-12 ADEOS score ≥ 20 were significantly lower among patients who experienced a GI event between baseline and month 6. The occurrence of GI events was observed to be associated with a lower likelihood of patient adherence and persistence to OP medication. This study examines the relationship between gastrointestinal (GI) events and self-reported adherence and persistence with initial osteoporosis (OP) therapy over the course of the first 12 months of treatment. The Medication Use Patterns, Treatment Satisfaction, and Inadequate Control of Osteoporosis Study was a multinational, prospective, observational study examining the impact of GI events on OP management in postmenopausal women. Information regarding GI events was collected at the time of enrollment and at months 3, 6, and 12 of follow-up. Patients reported GI events and medication persistence and completed the 12-item Adherence Evaluation of Osteoporosis treatment (ADEOS) questionnaire. Multivariate logistic and general linear models examined the association between GI events at various time points and persistence and adherence at month 12. The study enrolled 2943 women; 22.8% were classified as new users of OP therapy and the remainder were considered experienced users. Across all patients, 68.1% reported GI events at baseline; by month 12, over 80% of subjects who completed follow-up reported at least one GI problem. The majority of patients (86.7%) were treated only with bisphosphonates at baseline. At month 12, 73.9% of patients remained on therapy
Modelling female fertility traits in beef cattle using linear and non-linear models.

Science.gov (United States)

Naya, H; Peñagaricano, F; Urioste, J I

2017-06-01

Female fertility traits are key components of the profitability of beef cattle production. However, these traits are difficult and expensive to measure, particularly under extensive pastoral conditions, and consequently, fertility records are in general scarce and somehow incomplete. Moreover, fertility traits are usually dominated by the effects of herd-year environment, and it is generally assumed that relatively small margins are kept for genetic improvement. New ways of modelling genetic variation in these traits are needed. Inspired in the methodological developments made by Prof. Daniel Gianola and co-workers, we assayed linear (Gaussian), Poisson, probit (threshold), censored Poisson and censored Gaussian models to three different kinds of endpoints, namely calving success (CS), number of days from first calving (CD) and number of failed oestrus (FE). For models involving FE and CS, non-linear models overperformed their linear counterparts. For models derived from CD, linear versions displayed better adjustment than the non-linear counterparts. Non-linear models showed consistently higher estimates of heritability and repeatability in all cases (h 2 linear models; h 2 > 0.23 and r > 0.24, for non-linear models). While additive and permanent environment effects showed highly favourable correlations between all models (>0.789), consistency in selecting the 10% best sires showed important differences, mainly amongst the considered endpoints (FE, CS and CD). In consequence, endpoints should be considered as modelling different underlying genetic effects, with linear models more appropriate to describe CD and non-linear models better for FE and CS. © 2017 Blackwell Verlag GmbH.
Further linear algebra

CERN Document Server

Blyth, T S

2002-01-01

Most of the introductory courses on linear algebra develop the basic theory of finite dimensional vector spaces, and in so doing relate the notion of a linear mapping to that of a matrix. Generally speaking, such courses culminate in the diagonalisation of certain matrices and the application of this process to various situations. Such is the case, for example, in our previous SUMS volume Basic Linear Algebra. The present text is a continuation of that volume, and has the objective of introducing the reader to more advanced properties of vector spaces and linear mappings, and consequently of matrices. For readers who are not familiar with the contents of Basic Linear Algebra we provide an introductory chapter that consists of a compact summary of the prerequisites for the present volume. In order to consolidate the student's understanding we have included a large num ber of illustrative and worked examples, as well as many exercises that are strategi cally placed throughout the text. Solutions to the ex...
Impact of persistent cytomegalovirus infection on human neuroblastoma cell gene expression

International Nuclear Information System (INIS)

Hoever, Gerold; Vogel, Jens-Uwe; Lukashenko, Polina; Hofmann, Wolf-Karsten; Komor, Martina; Doerr, Hans Wilhelm; Cinatl, Jindrich

2005-01-01

In a model of human neuroblastoma (NB) cell lines persistently infected with human cytomegalovirus (HCMV) we previously showed that persistent HCMV infection is associated with an increased malignant phenotype, enhanced drug resistance, and invasive properties. To gain insights into the mechanisms of increased malignancy we analyzed the global changes in cellular gene expression induced by persistent HCMV infection of human neuroblastoma cells by use of high-density oligonucleotide microarrays (HG-U133A, Affymetrix) and RT-PCR. Comparing the gene expression of different NB cell lines with persistently infected cell sub-lines revealed 11 host cell genes regulated in a similar manner throughout all infected samples. Nine of these 11 genes may contribute to the previously observed changes in malignant phenotype of persistently HCMV infected NB cells by influencing invasive growth, apoptosis, angiogenesis, and proliferation. Thus, this work provides the basis for further functional studies
SLAC linear collider and a few ideas on future linear colliders

International Nuclear Information System (INIS)

Loew, G.A.

1984-04-01

This paper comes in two parts. The first part is a progress report on the SLAC Linear Collider (SLC) with emphasis on those systems which are of special interest to linear accelerator designers; it sets the stage for a number of contributed papers on specific topics which are also presented at this conference. The second part presents some ideas which are of interest to the design of future linear colliders of higher energies
The existence and persistence of household financial hardship

OpenAIRE

Brown, S.; Ghosh, P.; Taylor, K.

2012-01-01

We investigate the existence and persistence of financial hardship at the household level using data from the British Household Panel Survey. Our modelling strategy makes three important contributions to the existing literature on household finances. Firstly, we model nine different types of household financial problems within a joint framework, allowing for correlation in the random effects across the nine equations. Secondly, we develop a dynamic framework in order to model the persistence ...
Professional Role Confidence and Gendered Persistence in Engineering

OpenAIRE

Cech, Erin; Rubineau, Brian; Seron, Caroll; Silbey, Susan S.

2011-01-01

Social psychological research on gendered persistence in science, technology, engineering, and mathematics (STEM) professions is dominated by two explanations: women leave because they perceive their family plans to be at odds with demands of STEM careers, and women leave due to low self-assessment of their skills in STEM’s intellectual tasks, net of their performance. This study uses original panel data to examine behavioral and intentional persistence among students who enter an engineering...
Topics in computational linear optimization

DEFF Research Database (Denmark)

Hultberg, Tim Helge

2000-01-01

Linear optimization has been an active area of research ever since the pioneering work of G. Dantzig more than 50 years ago. This research has produced a long sequence of practical as well as theoretical improvements of the solution techniques avilable for solving linear optimization problems...... of high quality solvers and the use of algebraic modelling systems to handle the communication between the modeller and the solver. This dissertation features four topics in computational linear optimization: A) automatic reformulation of mixed 0/1 linear programs, B) direct solution of sparse unsymmetric...... systems of linear equations, C) reduction of linear programs and D) integration of algebraic modelling of linear optimization problems in C++. Each of these topics is treated in a separate paper included in this dissertation. The efficiency of solving mixed 0-1 linear programs by linear programming based...
Linearly constrained minimax optimization

DEFF Research Database (Denmark)

Madsen, Kaj; Schjær-Jacobsen, Hans

1978-01-01

We present an algorithm for nonlinear minimax optimization subject to linear equality and inequality constraints which requires first order partial derivatives. The algorithm is based on successive linear approximations to the functions defining the problem. The resulting linear subproblems...

Modeling the Environmental Impact of Air Traffic Operations

Science.gov (United States)

Chen, Neil

2011-01-01

There is increased interest to understand and mitigate the impacts of air traffic on the climate, since greenhouse gases, nitrogen oxides, and contrails generated by air traffic can have adverse impacts on the climate. The models described in this presentation are useful for quantifying these impacts and for studying alternative environmentally aware operational concepts. These models have been developed by leveraging and building upon existing simulation and optimization techniques developed for the design of efficient traffic flow management strategies. Specific enhancements to the existing simulation and optimization techniques include new models that simulate aircraft fuel flow, emissions and contrails. To ensure that these new models are beneficial to the larger climate research community, the outputs of these new models are compatible with existing global climate modeling tools like the FAA's Aviation Environmental Design Tool.
Linear operator inequalities for strongly stable weakly regular linear systems

NARCIS (Netherlands)

Curtain, RF

2001-01-01

We consider the question of the existence of solutions to certain linear operator inequalities (Lur'e equations) for strongly stable, weakly regular linear systems with generating operators A, B, C, 0. These operator inequalities are related to the spectral factorization of an associated Popov
Autologous Blood Pleurodesis In Patients With Persistent Air Leaks

Directory of Open Access Journals (Sweden)

Agkajanzadeh M

2003-10-01

Full Text Available Persistent air leaks occur after Spontaneous pneumothorax both primary and secondary, and after lungs trauma and lung surgeries are sever problems encountered chest surgeons with. Persistent air leak causes longer patients hospitalization."nMaterials and Methods: We used autologous blood pleurodesis in patients with persistent air leak for 30patients with more than 8 days air leaks, during a three years period 1377-1380 (1999-2002."nResults: The patients had 19 years up to 70 years old. Eight patients had thoracotomy and lobectomy and /or segmentectomies 6 with primary pneumothorax, 10 with secondary pneumothorax, and four with penetrated or blunt thoracic traumas. Blood was obtained from femoral or brachial veins and 70-150 mis. Injected in chest tubes. Chest bottle was first lied 80cm higher than body levels. After 24 hours repositioned in normal levels, and patients were supervised. Via chest tube we injected blood 70-100ml.for young patients, and 100-150 ml for older patients into intra pleural space. There were no clamped chest tubes. There were no pain, respiratory distress, fever, or cough in pleurodesized patients. The only patient's complaint was local pain in femoral vein or brachial vein because blood sampling and blood obtaining, although there was no local visible complication as hematoma or bleeding. After 48 hours in 24 patients air leak ceased. In six patients because persistent air leak autologous blood pleurodesis repeated, two patients after 48hours"nair leak ceased, remaining four patients underwent for thoracotomies, success rate"nwas 86.6%."nConclusion: According above success rate we suggest autologous blood pleurodesis in patients with persistent air leak is a reliable, effective, and no complicated procedure for persistent air leaks.
Advanced analysis technique for the evaluation of linear alternators and linear motors

Science.gov (United States)

Holliday, Jeffrey C.

1995-01-01

A method for the mathematical analysis of linear alternator and linear motor devices and designs is described, and an example of its use is included. The technique seeks to surpass other methods of analysis by including more rigorous treatment of phenomena normally omitted or coarsely approximated such as eddy braking, non-linear material properties, and power losses generated within structures surrounding the device. The technique is broadly applicable to linear alternators and linear motors involving iron yoke structures and moving permanent magnets. The technique involves the application of Amperian current equivalents to the modeling of the moving permanent magnet components within a finite element formulation. The resulting steady state and transient mode field solutions can simultaneously account for the moving and static field sources within and around the device.
Persistent Mullerian Duct Syndrome (PMDS With Large Intraabdominal Seminoma

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Della Harigovind

2017-07-01

Full Text Available Persistent Mullerian Duct Syndrome, a form of male pseudohermaphroditism is characterized by the presence of the Mullerian duct derivatives in an otherwise phenotypically as well as genotypically normal male. We report a case of large intra abdominal seminoma in a male patient with cryptorchidism, along with persistence of Mullerian duct derivatives (uterus.
Higher persistence with valsartan compared with enalapril in daily practice

Directory of Open Access Journals (Sweden)

Satu J Siiskonen

2008-01-01

Full Text Available Satu J Siiskonen1, Nancy S Breekveldt-Postma1, Gábor Vincze2, Zeba M Khan3, Joëlle A Erkens1, Ron MC Herings11PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands; 2Novartis Pharma AG, Basel, Switzerland; 3Novartis Pharmaceuticals Corporation, East Hanover, NJ, USAObjective: To compare persistence with valsartan and enalapril in daily practice.Methods: The PHARMO Record Linkage System includes various data registries including drug dispensing and hospitalizations for ≥2 million subjects in the Netherlands. Patients newly treated with valsartan or enalapril in the period of 1999–2002 were selected. Persistence was calculated by summing up the number of days of continuous treatment. Patients who remained on therapy with valsartan or enalapril for 12 or 24 months were defined as persistent at 1 or 2 years, respectively.Results: 3364 patients received valsartan and 9103 patients received enalapril. About 62% of patients treated with valsartan and 55% of patients treated with enalapril remained on therapy at 12 months after the initial dispensing, while 48% of patients treated with valsartan and 43% of patients treated with enalapril were persistent at 24 months. Patients treated with valsartan were about 20% more likely to stay on treatment than patients treated with enalapril (1 year RRadj: 1.23, 95% CI: 1.16–1.32; 2 years RRadj: 1.16, 95% CI: 1.11–1.23.Conclusions: Real-life persistence is higher with valsartan than with enalapril. The results of this and other studies on persistence in daily practice should be taken into account when deciding upon drug treatment for hypertension.Keywords: persistence, antihypertensive, valsartan, enalapril, angiotensin-converting enzyme inhibitors, angiotensin-2-receptor blockers
Persistent renal enhancement after intra-arterial versus intravenous iodixanol administration

International Nuclear Information System (INIS)

Chou, Shinn-Huey; Wang, Zhen J.; Kuo, Jonathan; Cabarrus, Miguel; Fu Yanjun; Aslam, Rizwan; Yee, Judy; Zimmet, Jeffrey M.; Shunk, Kendrick; Elicker, Brett; Yeh, Benjamin M.

2011-01-01

Purpose: To examine the clinical significance of persistent renal enhancement after iodixanol administration. Methods: We retrospectively studied 166 consecutive patients who underwent non-enhanced abdominopelvic CT within 7 days after receiving intra-arterial (n = 99) or intravenous (n = 67) iodixanol. Renal attenuation was measured for each non-enhanced CT scan. Persistent renal enhancement was defined as CT attenuation >55 Hounsfield units (HU). Contrast-induced nephropathy (CIN) was defined as a rise in serum creatinine >0.5 mg/dL within 5 days after contrast administration. Results: While the intensity and frequency of persistent renal enhancement was higher after intra-arterial (mean CT attenuation of 73.7 HU, seen in 54 of 99 patients, or 55%) than intravenous contrast material administration (51.8 HU, seen in 21 of 67, or 31%, p < 0.005), a multivariate regression model showed that the independent predictors of persistent renal enhancement were a shorter time interval until the subsequent non-enhanced CT (p < 0.001); higher contrast dose (p < 0.001); higher baseline serum creatinine (p < 0.01); and older age (p < 0.05). The route of contrast administration was not a predictor of persistent renal enhancement in this model. Contrast-induced nephropathy was noted in 9 patients who received intra-arterial (9%) versus 3 who received intravenous iodixanol (4%), and was more common in patients with persistent renal enhancement (p < 0.01). Conclusion: Persistent renal enhancement at follow-up non-contrast CT suggests a greater risk for contrast-induced nephropathy, but the increased frequency of striking renal enhancement in patients who received intra-arterial rather than intravenous contrast material also reflects the larger doses of contrast and shorter time to subsequent follow-up CT scanning for such patients.
On persistently positively expansive maps

Directory of Open Access Journals (Sweden)

Alexander Arbieto

2010-06-01

Full Text Available In this paper, we prove that any C¹-persistently positively expansive map is expanding. This improves a result due to Sakai (Sakai 2004.Neste artigo, mostramos que todo mapa C¹-persistentemente positivamente expansivo e expansor. Isto melhora um resultado devido a Sakai (Sakai 2004.
Brain differences between persistent and remitted attention deficit hyperactivity disorder.

Science.gov (United States)

Mattfeld, Aaron T; Gabrieli, John D E; Biederman, Joseph; Spencer, Thomas; Brown, Ariel; Kotte, Amelia; Kagan, Elana; Whitfield-Gabrieli, Susan

2014-09-01

Previous resting state studies examining the brain basis of attention deficit hyperactivity disorder have not distinguished between patients who persist versus those who remit from the diagnosis as adults. To characterize the neurobiological differences and similarities of persistence and remittance, we performed resting state functional magnetic resonance imaging in individuals who had been longitudinally and uniformly characterized as having or not having attention deficit hyperactivity disorder in childhood and again in adulthood (16 years after baseline assessment). Intrinsic functional brain organization was measured in patients who had a persistent diagnosis in childhood and adulthood (n = 13), in patients who met diagnosis in childhood but not in adulthood (n = 22), and in control participants who never had attention deficit hyperactivity disorder (n = 17). A positive functional correlation between posterior cingulate and medial prefrontal cortices, major components of the default-mode network, was reduced only in patients whose diagnosis persisted into adulthood. A negative functional correlation between medial and dorsolateral prefrontal cortices was reduced in both persistent and remitted patients. The neurobiological dissociation between the persistence and remittance of attention deficit hyperactivity disorder may provide a framework for the relation between the clinical diagnosis, which indicates the need for treatment, and additional deficits that are common, such as executive dysfunctions. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Fano resonance and persistent current of a quantum ring

International Nuclear Information System (INIS)

Xiong Yongjian; Liang Xianting

2004-01-01

We investigate electron transport and persistent current of a quantum ring weakly attached to current leads. Assuming there is direct coupling (weakly or strongly) between two leads, electrons can transmit by the inter-lead coupling or tunneling through the quantum ring. The interference between the two paths yields asymmetric Fano line shape for conductance. In presence of interior magnetic flux, there is persistent current along the ring with narrow resonance peaks. The positions of the conductance resonances and the persistent current peaks correspond to the quasibound levels of the closed ring. This feature is helpful to determine the energy spectrum of the quantum ring. Our results show that the proposed setup provides a tunable Fano system
Term Structure Persistence

OpenAIRE

Abbritti, M. (Mirko); Gil-Alana, L.A. (Luis A.); Lovcha, Y. (Yuliya); Moreno, A. (Antonio)

2012-01-01

Stationary I(0) models employed in yield curve analysis typically imply an unrealistically low degree of volatility in long-run short-rate expectations due to fast mean reversion. In this paper we propose a novel multivariate affine term structure model with a two-fold source of persistence in the yield curve: Long-memory and short-memory. Our model, based on an I(d) specification, nests the I(0) and I(1) models as special cases and the I(0) model is decisively rejected by the data. Our model...
Persistent postsurgical pain

DEFF Research Database (Denmark)

Werner, Mads Utke; Bischoff, Joakim Mutahi

2014-01-01

The prevalences of severe persistent postsurgical pain (PPP) following breast cancer surgery (BCS), groin hernia repair (GHR), and lung cancer surgery (LCS) are 13, 2, and 4-12 %, respectively. Estimates indicate that 80,000 patients each year in the U.S.A. are affected by severe pain...... duration of surgery, repeat surgery, more invasive surgical techniques, and intraoperative nerve lesion have been associated with PPP. One of the most consistent predictive factors for PPP is high intensity acute postsurgical pain, but also psychological factors including anxiety, catastrophizing trait...
Persistent hyperthyroidism and de novo Graves' ophthalmopathy after total thyroidectomy.

Science.gov (United States)

Tay, Wei Lin; Loh, Wann Jia; Lee, Lianne Ai Ling; Chng, Chiaw Ling

2017-01-01

We report a patient with Graves' disease who remained persistently hyperthyroid after a total thyroidectomy and also developed de novo Graves' ophthalmopathy 5 months after surgery. She was subsequently found to have a mature cystic teratoma containing struma ovarii after undergoing a total hysterectomy and salpingo-oophorectomy for an incidental ovarian lesion. It is important to investigate for other causes of primary hyperthyroidism when thyrotoxicosis persists after total thyroidectomy.TSH receptor antibody may persist after total thyroidectomy and may potentially contribute to the development of de novo Graves' ophthalmopathy.
Quad-copter UAV BLDC Motor Control: Linear v/s non-linear control maps

Directory of Open Access Journals (Sweden)

Deep Parikh

2015-08-01

Full Text Available This paper presents some investigations and comparison of using linear versus non-linear static motor-control maps for the speed control of a BLDC (Brush Less Direct Current motors used in quad-copter UAV (Unmanned Aerial Vehicles. The motor-control map considered here is the inverse of the static map relating motor-speed output to motor-voltage input for a typical out-runner type Brushless DC Motors (BLDCM. Traditionally, quad-copter BLDC motor speed control uses simple linear motor-control map defined by the motor-constant specification. However, practical BLDC motors show non-linear characteristic, particularly when operated across wide operating speed-range as is commonly required in quad-copter UAV flight operations. In this paper, our investigations to compare performance of linear versus non-linear motor-control maps are presented. The investigations cover simulation-based and experimental study of BLDC motor speed control systems for quad-copter vehicle available. First the non-linear map relating rotor RPM to motor voltage for quad-copter BLDC motor is obtained experimentally using an optical speed encoder. The performance of the linear versus non-linear motor-control-maps for the speed control are studied. The investigations also cover study of time-responses for various standard test input-signals e.g. step, ramp and pulse inputs, applied as the reference speed-commands. Also, simple 2-degree of freedom test-bed is developed in our laboratory to help test the open-loop and closed-loop experimental investigations. The non-linear motor-control map is found to perform better in BLDC motor speed tracking control performance and thereby helping achieve better quad-copter roll-angle attitude control.
Role of Prefrontal Persistent Activity in Working Memory

Science.gov (United States)

Riley, Mitchell R.; Constantinidis, Christos

2016-01-01

The prefrontal cortex is activated during working memory, as evidenced by fMRI results in human studies and neurophysiological recordings in animal models. Persistent activity during the delay period of working memory tasks, after the offset of stimuli that subjects are required to remember, has traditionally been thought of as the neural correlate of working memory. In the last few years several findings have cast doubt on the role of this activity. By some accounts, activity in other brain areas, such as the primary visual and posterior parietal cortex, is a better predictor of information maintained in visual working memory and working memory performance; dynamic patterns of activity may convey information without requiring persistent activity at all; and prefrontal neurons may be ill-suited to represent non-spatial information about the features and identity of remembered stimuli. Alternative interpretations about the role of the prefrontal cortex have thus been suggested, such as that it provides a top-down control of information represented in other brain areas, rather than maintaining a working memory trace itself. Here we review evidence for and against the role of prefrontal persistent activity, with a focus on visual neurophysiology. We show that persistent activity predicts behavioral parameters precisely in working memory tasks. We illustrate that prefrontal cortex represents features of stimuli other than their spatial location, and that this information is largely absent from early cortical areas during working memory. We examine memory models not dependent on persistent activity, and conclude that each of those models could mediate only a limited range of memory-dependent behaviors. We review activity decoded from brain areas other than the prefrontal cortex during working memory and demonstrate that these areas alone cannot mediate working memory maintenance, particularly in the presence of distractors. We finally discuss the discrepancy between
Sequencing of Escherichia coli that cause persistent and transient Mastitis

Science.gov (United States)

The genomes of two strains of Escherichia coli that cause bovine mastitis were sequenced. These strains are known to be associated with persistent and transient mastitis: strain ECA-B causes a transient infection, and ECC-M leads to a persistent infection....
Persistent organic pollutants–are our methods sensitive and selective enough?

NARCIS (Netherlands)

de Boer, J.

2012-01-01

Due to the exponential growth of the world population and a strong worldwide economic development, humans are increasingly exposed to chemicals. This is particularly true for persistent, toxic chemicals that accumulate in organisms including humans. The presence of these persistent organic
Considerations of persistence and security in CHOICES, an object-oriented operating system

Science.gov (United States)

Campbell, Roy H.; Madany, Peter W.

1990-01-01

The current design of the CHOICES persistent object implementation is summarized, and research in progress is outlined. CHOICES is implemented as an object-oriented system, and persistent objects appear to simplify and unify many functions of the system. It is demonstrated that persistent data can be accessed through an object-oriented file system model as efficiently as by an existing optimized commercial file system. The object-oriented file system can be specialized to provide an object store for persistent objects. The problems that arise in building an efficient persistent object scheme in a 32-bit virtual address space that only uses paging are described. Despite its limitations, the solution presented allows quite large numbers of objects to be active simultaneously, and permits sharing and efficient method calls.
Survival of Bactericidal Antibiotic Treatment by a Persister Subpopulation of Listeria monocytogenes

DEFF Research Database (Denmark)

Knudsen, Gitte Maegaard; Ng, Yin; Gram, Lone

2013-01-01

Listeria monocytogenes can cause the serious infection listeriosis, which despite antibiotic treatment has a high mortality. Understanding the response of L. monocytogenes to antibiotic exposure is therefore important to ensure treatment success. Some bacteria survive antibiotic treatment...... by formation of persisters, which are a dormant antibiotic-tolerant subpopulation. The purpose of this study was to determine whether L. monocytogenes can form persisters and how bacterial physiology affects the number of persisters in the population. A stationary-phase culture of L. monocytogenes was adjusted...... that eradication of persisters is possible. Our study adds L. monocytogenes to the list of bacterial species capable of surviving bactericidal antibiotics in a dormant stage, and this persister phenomenon should be borne in mind when developing treatment regimens....
NH125 kills methicillin-resistant Staphylococcus aureus persisters by lipid bilayer disruption.

Science.gov (United States)

Kim, Wooseong; Fricke, Nico; Conery, Annie L; Fuchs, Beth Burgwyn; Rajamuthiah, Rajmohan; Jayamani, Elamparithi; Vlahovska, Petia M; Ausubel, Frederick M; Mylonakis, Eleftherios

2016-01-01

NH125, a known WalK inhibitor kills MRSA persisters. However, its precise mode of action is still unknown. The mode of action of NH125 was investigated by comparing its spectrum of antimicrobial activity and its effects on membrane permeability and giant unilamellar vesicles (GUVs) with walrycin B, a WalR inhibitor and benzyldimethylhexadecylammonium chloride (16-BAC), a cationic surfactant. NH125 killed persister cells of a variety of Staphylococcus aureus strains. Similar to 16-BAC, NH125 killed MRSA persisters by inducing rapid membrane permeabilization and caused the rupture of GUVs, whereas walrycin B did not kill MRSA persisters or induce membrane permeabilization and did not affect GUVs. NH125 kills MRSA persisters by interacting with and disrupting membranes in a detergent-like manner.

Primordial black holes in linear and non-linear regimes

Energy Technology Data Exchange (ETDEWEB)

Allahyari, Alireza; Abolhasani, Ali Akbar [Department of Physics, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Firouzjaee, Javad T., E-mail: allahyari@physics.sharif.edu, E-mail: j.taghizadeh.f@ipm.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)

2017-06-01

We revisit the formation of primordial black holes (PBHs) in the radiation-dominated era for both linear and non-linear regimes, elaborating on the concept of an apparent horizon. Contrary to the expectation from vacuum models, we argue that in a cosmological setting a density fluctuation with a high density does not always collapse to a black hole. To this end, we first elaborate on the perturbation theory for spherically symmetric space times in the linear regime. Thereby, we introduce two gauges. This allows to introduce a well defined gauge-invariant quantity for the expansion of null geodesics. Using this quantity, we argue that PBHs do not form in the linear regime irrespective of the density of the background. Finally, we consider the formation of PBHs in non-linear regimes, adopting the spherical collapse picture. In this picture, over-densities are modeled by closed FRW models in the radiation-dominated era. The difference of our approach is that we start by finding an exact solution for a closed radiation-dominated universe. This yields exact results for turn-around time and radius. It is important that we take the initial conditions from the linear perturbation theory. Additionally, instead of using uniform Hubble gauge condition, both density and velocity perturbations are admitted in this approach. Thereby, the matching condition will impose an important constraint on the initial velocity perturbations δ {sup h} {sub 0} = −δ{sub 0}/2. This can be extended to higher orders. Using this constraint, we find that the apparent horizon of a PBH forms when δ > 3 at turn-around time. The corrections also appear from the third order. Moreover, a PBH forms when its apparent horizon is outside the sound horizon at the re-entry time. Applying this condition, we infer that the threshold value of the density perturbations at horizon re-entry should be larger than δ {sub th} > 0.7.
A linear evolution for non-linear dynamics and correlations in realistic nuclei

International Nuclear Information System (INIS)

Levin, E.; Lublinsky, M.

2004-01-01

A new approach to high energy evolution based on a linear equation for QCD generating functional is developed. This approach opens a possibility for systematic study of correlations inside targets, and, in particular, inside realistic nuclei. Our results are presented as three new equations. The first one is a linear equation for QCD generating functional (and for scattering amplitude) that sums the 'fan' diagrams. For the amplitude this equation is equivalent to the non-linear Balitsky-Kovchegov equation. The second equation is a generalization of the Balitsky-Kovchegov non-linear equation to interactions with realistic nuclei. It includes a new correlation parameter which incorporates, in a model-dependent way, correlations inside the nuclei. The third equation is a non-linear equation for QCD generating functional (and for scattering amplitude) that in addition to the 'fan' diagrams sums the Glauber-Mueller multiple rescatterings
Piecewise Linear-Linear Latent Growth Mixture Models with Unknown Knots

Science.gov (United States)

Kohli, Nidhi; Harring, Jeffrey R.; Hancock, Gregory R.

2013-01-01

Latent growth curve models with piecewise functions are flexible and useful analytic models for investigating individual behaviors that exhibit distinct phases of development in observed variables. As an extension of this framework, this study considers a piecewise linear-linear latent growth mixture model (LGMM) for describing segmented change of…
The regular indefinite linear-quadratic problem with linear endpoint constraints

NARCIS (Netherlands)

Soethoudt, J.M.; Trentelman, H.L.

1989-01-01

This paper deals with the infinite horizon linear-quadratic problem with indefinite cost. Given a linear system, a quadratic cost functional and a subspace of the state space, we consider the problem of minimizing the cost functional over all inputs for which the state trajectory converges to that
A test of the linear-no threshold theory of radiation carcinogenesis

International Nuclear Information System (INIS)

Cohen, B.L.

1990-01-01

It has been pointed out that, while an ecological study cannot determine whether radon causes lung cancer, it can test the validity of a linear-no threshold relationship between them. The linear-no threshold theory predicts a substantial positive correlation between the average radon exposure in various counties and their lung cancer mortality rates. Data on living areas of houses in 411 counties from all parts of the United States exhibit, rather, a substantial negative correlation with the slopes of the lines of regression differing from zero by 10 and 7 standard deviations for males and females, respectively, and from the positive slope predicted by the theory by at least 16 and 12 standard deviations. When the data are segmented into 23 groups of states or into 7 regions of the country, the predominantly negative slopes and correlations persist, applying to 18 of the 23 state groups and 6 of the 7 regions. Five state-sponsored studies are analyzed, and four of these give a strong negative slope (the other gives a weak positive slope, in agreement with our data for that state). A strong negative slope is also obtained in our data on basements in 253 counties. A random selection-no charge study of 39 high and low lung cancer counties (+4 low population states) gives a much stronger negative correlation. When nine potential confounding factors are included in a multiple linear regression analysis, the discrepancy with theory is reduced only to 12 and 8.5 standard deviations for males and females, respectively. When the data are segmented into four groups by population, the multiple regression vs radon level gives a strong negative slope for each of the four groups. Other considerations are introduced to reduce the discrepancy, but it remains very substantial
Persistent Modelling

DEFF Research Database (Denmark)

2012-01-01

The relationship between representation and the represented is examined here through the notion of persistent modelling. This notion is not novel to the activity of architectural design if it is considered as describing a continued active and iterative engagement with design concerns – an evident....... It also provides critical insight into the use of contemporary modelling tools and methods, together with an examination of the implications their use has within the territories of architectural design, realisation and experience....... on this subject, this book makes essential reading for anyone considering new ways of thinking about architecture. In drawing upon both historical and contemporary perspectives this book provides evidence of the ways in which relations between representation and the represented continue to be reconsidered...
Persistent Modelling

DEFF Research Database (Denmark)

The relationship between representation and the represented is examined here through the notion of persistent modelling. This notion is not novel to the activity of architectural design if it is considered as describing a continued active and iterative engagement with design concerns – an evident....... It also provides critical insight into the use of contemporary modelling tools and methods, together with an examination of the implications their use has within the territories of architectural design, realisation and experience....... on this subject, this book makes essential reading for anyone considering new ways of thinking about architecture. In drawing upon both historical and contemporary perspectives this book provides evidence of the ways in which relations between representation and the represented continue to be reconsidered...
Linear collider: a preview

Energy Technology Data Exchange (ETDEWEB)

Wiedemann, H.

1981-11-01

Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.
Linear collider: a preview

International Nuclear Information System (INIS)

Wiedemann, H.

1981-11-01

Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center
Persistent pain and sensory disturbances after treatment for breast cancer

DEFF Research Database (Denmark)

Mejdahl, Mathias Kvist; Andersen, Kenneth Geving; Gärtner, Rune

2013-01-01

To examine the development of persistent pain after treatment for breast cancer and to examine risk factors associated with continuing pain.......To examine the development of persistent pain after treatment for breast cancer and to examine risk factors associated with continuing pain....
Photocarcinogenesis and persistent hyperplasia in UV-irradiated SENCAR mouse skin

International Nuclear Information System (INIS)

Strickland, P.T.

1986-01-01

Susceptibility to photocarcinogenesis has been examined in several mouse strains and stocks including SENCAR, CD-1, BALB/c, C3H, C57Bl, and NZB. SENCAR mice are hypersusceptible to tumorigenesis caused by single high dose exposures to ultraviolet (UV) radiation but not by chronic low-dose exposures. SENCAR mice also exhibit an exaggerated and persistent epidermal hyperplasia in response to UV-induced tissue damage. The persistent hyperplasia is apparently due to a sustained proliferation of the epithelial basal cells, rather than to delayed cell differentiation. SENCAR mice did not exhibit persistent hyperplasia following other forms of tissue damage (surgical or thermal). In related studies, the levels of thymine dimers induced in SENCAR epidermis by UV radiation were comparable to those observed in BALB/c epidermis. In addition, no differences were found in the tissue distribution or persistence of thymine dimers in SENCAR and BALB/c skin
Applied linear regression

CERN Document Server

Weisberg, Sanford

2013-01-01

Praise for the Third Edition ""...this is an excellent book which could easily be used as a course text...""-International Statistical Institute The Fourth Edition of Applied Linear Regression provides a thorough update of the basic theory and methodology of linear regression modeling. Demonstrating the practical applications of linear regression analysis techniques, the Fourth Edition uses interesting, real-world exercises and examples. Stressing central concepts such as model building, understanding parameters, assessing fit and reliability, and drawing conclusions, the new edition illus
Linearizing W-algebras

International Nuclear Information System (INIS)

Krivonos, S.O.; Sorin, A.S.

1994-06-01

We show that the Zamolodchikov's and Polyakov-Bershadsky nonlinear algebras W 3 and W (2) 3 can be embedded as subalgebras into some linear algebras with finite set of currents. Using these linear algebras we find new field realizations of W (2) 3 and W 3 which could be a starting point for constructing new versions of W-string theories. We also reveal a number of hidden relationships between W 3 and W (2) 3 . We conjecture that similar linear algebras can exist for other W-algebra as well. (author). 10 refs
Semidefinite linear complementarity problems

International Nuclear Information System (INIS)

Eckhardt, U.

1978-04-01

Semidefinite linear complementarity problems arise by discretization of variational inequalities describing e.g. elastic contact problems, free boundary value problems etc. In the present paper linear complementarity problems are introduced and the theory as well as the numerical treatment of them are described. In the special case of semidefinite linear complementarity problems a numerical method is presented which combines the advantages of elimination and iteration methods without suffering from their drawbacks. This new method has very attractive properties since it has a high degree of invariance with respect to the representation of the set of all feasible solutions of a linear complementarity problem by linear inequalities. By means of some practical applications the properties of the new method are demonstrated. (orig.) [de
Persistent Notochord in a Fetus with COL2A1 Mutation

Directory of Open Access Journals (Sweden)

Elisabeth Codsi

2015-01-01

Full Text Available Multiple anomalies including micromelia, poor mineralization of the vertebrae, and a persistent notochord were identified on second trimester ultrasound in a fetus with a COL2A1 mutation. To our knowledge, this represents the first case of a persistent notochord associated with a COL2A1 mutation in humans. In this case report, we describe ultrasound and postmortem findings and review the pathogenesis associated with a persistent notochord.
The existence and persistence of long work hours

OpenAIRE

Drago, Robert William; Black, David; Wooden, Mark

2005-01-01

Previous research hypothesizes that long working hours are related to consumerism, the ideal worker norm, high levels of human capital, and a high cost-of-job-loss. The authors test these hypotheses using panel data on working hours for an Australian sample of full-time employed workers. Analyses include a static cross-sectional model and a persistence model for long hours over time. The results suggest that long hours (50 or more hours in a usual week) are often persistent, and provide stron...
Persistence of, and interrelation between, horizontal and vertical technology alliances

NARCIS (Netherlands)

Belderbos, R.; Gilsing, V.A.; Lokshin, B.

2012-01-01

The authors explore to what extent there is persistence in, and interrelation between, alliance strategies with different partner types (customers, suppliers, competitors). In a panel data set of innovation-active firms in the Netherlands from 1996 to 2004, the authors find persistence in alliance
Persistent Breech Presentation in a Bicornuate Uterus: A Case Report

African Journals Online (AJOL)

We report a case of persistent breech presentation in a primigravida with bicornuate uterus that was initially diagnosed by early ultrasound scan. Persistent breech presentation later in the pregnancy necessitated an elective caesarean section at term. The diagnosis was confirmed intraoperatively by exteriorizing the uterus.
Study on microbial persistence in end-stage idiopathic dilated cardiomyopathy.

NARCIS (Netherlands)

Leeuw, N. de; Melchers, W.J.G.; Balk, A.H.M.M.; Jonge, N. de; Galama, J.M.D.

1999-01-01

Microbial persistence may be involved in the pathogenesis of idiopathic dilated cardiomyopathy (IDC). Therefore, we evaluated the role of various cardiopathogenic microorganisms in patients with end-stage IDC. In a previous study, we did not find evidence for the persistence of enterovirus RNA in
Near-total pancreatectomy for persistent hyperinsulinemic ...

African Journals Online (AJOL)

of persistent hypoglycemia in infancy with consequences ... (PHHI) is the most common cause of recurrent and per- sistent hypoglycemia in infancy and childhood. Causes .... a high rate of pancreatic surgery in the neonatal-onset group.

Endorectal magnetic resonance imaging in persistent hemospermia

International Nuclear Information System (INIS)

Prando, Adilson

2008-01-01

Objective: To present the spectrum of abnormalities found at endorectal magnetic resonance imaging (E-MRI), in patients with persistent hemospermia. Materials and methods: A review of E-MRI findings observed in 86 patients with persistent hemospermia was performed and results compared with those reported in the literature. Follow-up was possible in 37 of 86 (43%) patients with hemospermia. Results: E-MRI showed abnormal findings in 52 of 86 (60%) patients with hemospermia. These findings were: a) hemorrhagic seminal vesicle and ejaculatory duct, isolated (n = 11 or 21%) or associated with complicated midline prostatic cyst (n = 10 or 19.0%); b) hemorrhagic chronic seminal vesiculitis, isolated (n = 14 or 27%) or associated with calculi within dilated ejaculatory ducts (n = 2 or 4 %); c) hemorrhagic seminal vesicle associated with calculi within dilated ejaculatory duct (n = 4 or 7.7%) or within seminal vesicle (n = 4 or 7.7%); d) non-complicated midline prostatic cyst (n = 6 or 11.5%); and e) prostate cancer (n = 1 or 2%). Successful treatment was more frequent in patients with chronic inflammatory and/or obstructive abnormalities. Conclusion: E-MRI should be considered the modality of choice, for the evaluation of patients with persistent hemospermia. (author)
Endorectal magnetic resonance imaging in persistent hemospermia

Energy Technology Data Exchange (ETDEWEB)

Prando, Adilson [Vera Cruz Hospital, Campinas, SP (Brazil). Dept. of Radiology and Diagnostic Imaging

2008-03-15

Objective: To present the spectrum of abnormalities found at endorectal magnetic resonance imaging (E-MRI), in patients with persistent hemospermia. Materials and methods: A review of E-MRI findings observed in 86 patients with persistent hemospermia was performed and results compared with those reported in the literature. Follow-up was possible in 37 of 86 (43%) patients with hemospermia. Results: E-MRI showed abnormal findings in 52 of 86 (60%) patients with hemospermia. These findings were: a) hemorrhagic seminal vesicle and ejaculatory duct, isolated (n = 11 or 21%) or associated with complicated midline prostatic cyst (n = 10 or 19.0%); b) hemorrhagic chronic seminal vesiculitis, isolated (n = 14 or 27%) or associated with calculi within dilated ejaculatory ducts (n = 2 or 4 %); c) hemorrhagic seminal vesicle associated with calculi within dilated ejaculatory duct (n = 4 or 7.7%) or within seminal vesicle (n = 4 or 7.7%); d) non-complicated midline prostatic cyst (n = 6 or 11.5%); and e) prostate cancer (n = 1 or 2%). Successful treatment was more frequent in patients with chronic inflammatory and/or obstructive abnormalities. Conclusion: E-MRI should be considered the modality of choice, for the evaluation of patients with persistent hemospermia. (author)
Symptom persistence in a community cohort of women with interstitial cystitis/bladder pain syndrome (IC/BPS): 3-, 6-, 9-, and 12-month follow-up from the RICE cohort.

Science.gov (United States)

Suskind, Anne M; Berry, Sandra H; Suttorp, Marika J; Elliott, Marc N; Clemens, J Quentin

2014-12-01

The persistence of interstitial cystitis/bladder pain syndrome (IC/BPS) symptoms has been described in women seeking medical care. The purpose of this study was to determine whether symptoms persist among a population-based sample of women. A probability sample of US women was identified through a two-stage telephone screening process using the Research and Development (RAND) Interstitial Cystitis Epidemiology (RICE) high-sensitivity case definition. A randomly selected subgroup (n = 508) was enrolled in a longitudinal study and interviewed about their symptoms at baseline, 3, 6, 9, and 12 months. Bivariate and multivariate linear regression analyses determined predictors of persistence of symptoms over the four waves. A total of 436 women with a mean age of 47.5 years responding to all waves were included in the analysis. Forty-one percent met the RICE high-sensitivity case definition at baseline and in all four waves; an additional 21 % met the definition at baseline and in three waves. Women with a college degree (+12 % vs. no college, p = 0.02) and who were younger (-5 % per decade of age, p standard deviation higher on the continuity of symptoms and the O'Leary-Sant Interstitial Cystitis Symptom index increased the chances of symptom persistence by 4 % and 2 %, respectively (both p < 0.01). The majority of women demonstrated symptom persistence across at least three of four waves over 12 months. These women tended to be younger, college-educated, and to have reported a history of greater continuity of symptoms and higher severity of symptoms at baseline.
Persistent current through a semiconductor quantum dot with Gaussian confinement

International Nuclear Information System (INIS)

Boyacioglu, Bahadir; Chatterjee, Ashok

2012-01-01

The persistent diamagnetic current in a GaAs quantum dot with Gaussian confinement is calculated. It is shown that except at very low temperature or at high temperature, the persistent current increases with decreasing temperature. It is also shown that as a function of the dot size, the diamagnetic current exhibits a maximum at a certain confinement length. It is furthermore shown that for a shallow potential, the persistent current shows an interesting maximum structure as a function of the depth of the potential. At low temperature, the peak structure is pretty sharp but becomes broader and broader with increasing temperature.
The effects of acute stress on the calibration of persistence.

Science.gov (United States)

Lempert, Karolina M; McGuire, Joseph T; Hazeltine, Danielle B; Phelps, Elizabeth A; Kable, Joseph W

2018-02-01

People frequently fail to wait for delayed rewards after choosing them. These preference reversals are sometimes thought to reflect self-control failure. Other times, however, continuing to wait for a delayed reward may be counterproductive (e.g., when reward timing uncertainty is high). Research has demonstrated that people can calibrate how long to wait for rewards in a given environment. Thus, the role of self-control might be to integrate information about the environment to flexibly adapt behavior, not merely to promote waiting. Here we tested effects of acute stress, which has been shown to tax control processes, on persistence, and the calibration of persistence, in young adult human participants. Half the participants (n = 60) performed a task in which persistence was optimal, and the other half (n = 60) performed a task in which it was optimal to quit waiting for reward soon after each trial began. Each participant completed the task either after cold pressor stress or no stress. Stress did not influence persistence or optimal calibration of persistence. Nevertheless, an exploratory analysis revealed an "inverted-U" relationship between cortisol increase and performance in the stress groups, suggesting that choosing the adaptive waiting policy may be facilitated with some stress and impaired with severe stress.
THE ROLE OF EARNINGS PERSISTENCE IN VALUATION ACCURACY AND THE TIME HORIZON

Directory of Open Access Journals (Sweden)

Renê Coppe Pimentel

2016-02-01

Full Text Available Based on the assumption that earnings persistence has implications for both financial analysis and compensation contracts, the aim of this paper is to investigate the role of earnings persistence assuming that (i more persistent earnings are likely to be a better input to valuation models and (ii more persistent earnings are likely to serve as a proxy for long-term market and managerial orientation. The analysis is based on Brazilian listed firms from 1995 to 2013, and while we document strong support for the relevance of earnings persistence in financial analysis and valuation, we fail to document a significant relationship between earnings persistence and long-term value orientation. These results are sensitive to different specifications, and additional results suggest that firms’ idiosyncratic risk (total risk is relevant to explain the focus on short-term outcomes (short-termism across firms. The main contribution of this paper is to offer empirical evidence for the relevance of accounting numbers in both valuation and contractual theories in an emergent market.
Linear models with R

CERN Document Server

Faraway, Julian J

2014-01-01

A Hands-On Way to Learning Data AnalysisPart of the core of statistics, linear models are used to make predictions and explain the relationship between the response and the predictors. Understanding linear models is crucial to a broader competence in the practice of statistics. Linear Models with R, Second Edition explains how to use linear models in physical science, engineering, social science, and business applications. The book incorporates several improvements that reflect how the world of R has greatly expanded since the publication of the first edition.New to the Second EditionReorganiz
Fault tolerant linear actuator

Science.gov (United States)

Tesar, Delbert

2004-09-14

In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.
LINEAR ACCELERATOR

Science.gov (United States)

Christofilos, N.C.; Polk, I.J.

1959-02-17

Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.
Analysis of Nonlinear Dynamics in Linear Compressors Driven by Linear Motors

Science.gov (United States)

Chen, Liangyuan

2018-03-01

The analysis of dynamic characteristics of the mechatronics system is of great significance for the linear motor design and control. Steady-state nonlinear response characteristics of a linear compressor are investigated theoretically based on the linearized and nonlinear models. First, the influence factors considering the nonlinear gas force load were analyzed. Then, a simple linearized model was set up to analyze the influence on the stroke and resonance frequency. Finally, the nonlinear model was set up to analyze the effects of piston mass, spring stiffness, driving force as an example of design parameter variation. The simulating results show that the stroke can be obtained by adjusting the excitation amplitude, frequency and other adjustments, the equilibrium position can be adjusted by adjusting the DC input, and to make the more efficient operation, the operating frequency must always equal to the resonance frequency.
Linear ubiquitination in immunity.

Science.gov (United States)

Shimizu, Yutaka; Taraborrelli, Lucia; Walczak, Henning

2015-07-01

Linear ubiquitination is a post-translational protein modification recently discovered to be crucial for innate and adaptive immune signaling. The function of linear ubiquitin chains is regulated at multiple levels: generation, recognition, and removal. These chains are generated by the linear ubiquitin chain assembly complex (LUBAC), the only known ubiquitin E3 capable of forming the linear ubiquitin linkage de novo. LUBAC is not only relevant for activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) in various signaling pathways, but importantly, it also regulates cell death downstream of immune receptors capable of inducing this response. Recognition of the linear ubiquitin linkage is specifically mediated by certain ubiquitin receptors, which is crucial for translation into the intended signaling outputs. LUBAC deficiency results in attenuated gene activation and increased cell death, causing pathologic conditions in both, mice, and humans. Removal of ubiquitin chains is mediated by deubiquitinases (DUBs). Two of them, OTULIN and CYLD, are constitutively associated with LUBAC. Here, we review the current knowledge on linear ubiquitination in immune signaling pathways and the biochemical mechanisms as to how linear polyubiquitin exerts its functions distinctly from those of other ubiquitin linkage types. © 2015 The Authors. Immunological Reviews Published by John Wiley & Sons Ltd.
Viral Interference and Persistence in Mosquito-Borne Flaviviruses

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Juan Santiago Salas-Benito

2015-01-01

Full Text Available Mosquito-borne flaviviruses are important pathogens for humans, and the detection of two or more flaviviruses cocirculating in the same geographic area has often been reported. However, the epidemiological impact remains to be determined. Mosquito-borne flaviviruses are primarily transmitted through Aedes and Culex mosquitoes; these viruses establish a life-long or persistent infection without apparent pathological effects. This establishment requires a balance between virus replication and the antiviral host response. Viral interference is a phenomenon whereby one virus inhibits the replication of other viruses, and this condition is frequently associated with persistent infections. Viral interference and persistent infection are determined by several factors, such as defective interfering particles, competition for cellular factors required for translation/replication, and the host antiviral response. The interaction between two flaviviruses typically results in viral interference, indicating that these viruses share common features during the replicative cycle in the vector. The potential mechanisms involved in these processes are reviewed here.
Persistent ectopic pregnancy after milking procedure: Case report

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Semra Kayataş

2014-03-01

Full Text Available Ectopic pregnancy is the settlement of the pregnancy product at any site other than the endometrium. The incidence of ectopic pregnancy have increased in the last 20 years. Increased frequency and early diagnosis has led to conservative treatment methods to become more favorable. Follow-up, medical management and surgical managements are considered as conservative methods. As salpingostomy is the most common conservative surgical method, milking is considered as an alternative conservative surgical method. The most important complication of the conservative surgery is the persistence of ectopic pregnancy because of the residual trophoblastic tissue. Since the prediction of the persistent ectopic pregnancy is difficult after the conservative surgery, β-HCG follow up is so important for early diagnosis. In this case report we have discussed the case of the patient who admitted to our clinic with persistent ectopic pregnancy with acute abdomen, after the treatment with milking procedure whom than treated by salpingectomy procedure.
[Persistence of the primordial vitreous body and buphthalmos].

Science.gov (United States)

Cernea, P; Simionescu, C; Bosun, I

1995-01-01

Persistence of the hyperplasic primordial vitreous body is determined by a deletion of embryonal development of the vitreous body and of the hyaloid vascular system. Infant aged 3.5 years presents persistence of primordial vitreous body with crystalline dislocation in the camera aquosa and secondary buphthalmos of the left eye and microphthalmos with dislocation of the crystalline in the vitreous body of the right eye. At the back of the right eye we noticed a whitish mass, richly vascularized with vestiges from the hyaloid artery, but the posterior half of the vitreous cavity is filled with microscopic blood; the fibrovascular membrane is made of conjunctive tissue set in parallel layers and vessels with macrolipophagic degeneration. Microscopic investigation of retina reveals glial hyperplasia zones in the neighbourhood of the vitreous body. In the present paper the authors show the persistence of the primordial vitreous body in the left eye and bilateral dislocation of the crystalline, revealing multiple ocular malformations.
Linear Colliders

International Nuclear Information System (INIS)

Alcaraz, J.

2001-01-01

After several years of study e''+ e''- linear colliders in the TeV range have emerged as the major and optimal high-energy physics projects for the post-LHC era. These notes summarize the present status form the main accelerator and detector features to their physics potential. The LHC era. These notes summarize the present status, from the main accelerator and detector features to their physics potential. The LHC is expected to provide first discoveries in the new energy domain, whereas an e''+ e''- linear collider in the 500 GeV-1 TeV will be able to complement it to an unprecedented level of precision in any possible areas: Higgs, signals beyond the SM and electroweak measurements. It is evident that the Linear Collider program will constitute a major step in the understanding of the nature of the new physics beyond the Standard Model. (Author) 22 refs
Linear regression

CERN Document Server

Olive, David J

2017-01-01

This text covers both multiple linear regression and some experimental design models. The text uses the response plot to visualize the model and to detect outliers, does not assume that the error distribution has a known parametric distribution, develops prediction intervals that work when the error distribution is unknown, suggests bootstrap hypothesis tests that may be useful for inference after variable selection, and develops prediction regions and large sample theory for the multivariate linear regression model that has m response variables. A relationship between multivariate prediction regions and confidence regions provides a simple way to bootstrap confidence regions. These confidence regions often provide a practical method for testing hypotheses. There is also a chapter on generalized linear models and generalized additive models. There are many R functions to produce response and residual plots, to simulate prediction intervals and hypothesis tests, to detect outliers, and to choose response trans...
Persistent Aerial Tracking

KAUST Repository

Mueller, Matthias

2016-04-13

In this thesis, we propose a new aerial video dataset and benchmark for low altitude UAV target tracking, as well as, a photo-realistic UAV simulator that can be coupled with tracking methods. Our benchmark provides the rst evaluation of many state of-the-art and popular trackers on 123 new and fully annotated HD video sequences captured from a low-altitude aerial perspective. Among the compared trackers, we determine which ones are the most suitable for UAV tracking both in terms of tracking accuracy and run-time. We also present a simulator that can be used to evaluate tracking algorithms in real-time scenarios before they are deployed on a UAV "in the field", as well as, generate synthetic but photo-realistic tracking datasets with free ground truth annotations to easily extend existing real-world datasets. Both the benchmark and simulator will be made publicly available to the vision community to further research in the area of object tracking from UAVs. Additionally, we propose a persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc.) integrating multiple UAVs with a stabilized RGB camera. A novel strategy is employed to successfully track objects over a long period, by \\'handing over the camera\\' from one UAV to another. We integrate the complete system into an off-the-shelf UAV, and obtain promising results showing the robustness of our solution in real-world aerial scenarios.
Long persistence of rigor mortis at constant low temperature.

Science.gov (United States)

Varetto, Lorenzo; Curto, Ombretta

2005-01-06

We studied the persistence of rigor mortis by using physical manipulation. We tested the mobility of the knee on 146 corpses kept under refrigeration at Torino's city mortuary at a constant temperature of +4 degrees C. We found a persistence of complete rigor lasting for 10 days in all the cadavers we kept under observation; and in one case, rigor lasted for 16 days. Between the 11th and the 17th days, a progressively increasing number of corpses showed a change from complete into partial rigor (characterized by partial bending of the articulation). After the 17th day, all the remaining corpses showed partial rigor and in the two cadavers that were kept under observation "à outrance" we found the absolute resolution of rigor mortis occurred on the 28th day. Our results prove that it is possible to find a persistence of rigor mortis that is much longer than the expected when environmental conditions resemble average outdoor winter temperatures in temperate zones. Therefore, this datum must be considered when a corpse is found in those environmental conditions so that when estimating the time of death, we are not misled by the long persistence of rigor mortis.
Association of hypovitaminosis Dwith persistent non-specific musculoskeletal pains

International Nuclear Information System (INIS)

Alam, H.M.A.; Kamran, M.; Rehman, S.U.; Khan, D.A.; Hussain, K.

2017-01-01

The study was conducted in Pakistani population to find association of vitamin D deficiency with persistent non-specific musculoskeletal pains by comparing with pain free controls. Study Design: Case control study. Material and Methods: Patients aged 12 years or more presenting to Medical OPD with persistent nonspecific musculoskeletal pains for more than 3 months were selected as cases, while healthy individuals served as controls Results: A total of 60 cases (patients with persistent non-specific pains) presenting to medical outpatients department at Military Hospital Rawalpindi and 60 controls were studied. Mean age of cases was 43.9 +- 14.0 years and amongst controls were 33.2 +- 17.8 years. Mean serum vitamin D level of 32.8 nmol/L was reported in cases whereas mean serum vitamin D level amongst controls was 26.7 +- 17.8 nmol/L. Hypovitaminosis D amongst cases and controls was 86.6% and 95% respectively. The proportion of vitamin D deficiency did not differ significantly as compared to controls. There was non-significant difference in proportion of deficiency amongst cases and controls. Conclusion: Overall there was no association between persistent non-specific musculoskeletal pains and vitamin D deficiency. (author)
A Clinical Drug Library Screen Identifies Tosufloxacin as Being Highly Active against Staphylococcus aureus Persisters

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Hongxia Niu

2015-07-01

Full Text Available To identify effective compounds that are active against Staphylococcus aureus (S. aureus persisters, we screened a clinical drug library consisting of 1524 compounds and identified six drug candidates that had anti-persister activity: tosufloxacin, clinafloxacin, sarafloxacin, doxycycline, thiostrepton, and chlorosalicylanilide. Among them, tosufloxacin had the highest anti-persister activity, which could completely eradicate S. aureus persisters within 2 days in vitro. Clinafloxacin ranked the second with very few persisters surviving the drug exposure. Interestingly, we found that both tosufloxacin and trovafloxacin that had high activity against persisters contained at the N-1 position the 2,4-difluorophenyl group, which is absent in other less active quinolones and may be associated with the high anti-persister activity. Further studies are needed to evaluate tosufloxacin in animal models and to explain its unique activity against bacterial persisters. Our findings may have implications for improved treatment of persistent bacterial infections.

Persistency of atmospheric diffusion conditions in Angra dos Reis - Brazil

International Nuclear Information System (INIS)

Nicolli, D.

1981-12-01

Based on a 2 year observation period, the diffusion conditions at the Almirante Alvaro Alberto N.P.P. site, in Angra dos Reis, are analized with respect to persistency as a function of the wind direction, the Pasquill stability class and the time of the day. The Pasquill stability class relates to the bulk vertical temperature gradient measured between 2m and 50m in the atmosphere; the wind direction is measured at 50m height. The persistency is defined in this report as the probability that the wind direction will remain longer than a given time in a sector without change in the diffusion category by more than a certain stage. During the day the persistency is mostly affected by the sea breeze with predominance of the unstable and neutral categories. At night the stable categories dominate. The alternating sea and land breezes disturb daily the trade wind field resulting in low persistency of the diffusion conditions. (Author) [pt
Persistent Skin Reactions and Aluminium Hypersensitivity Induced by Childhood Vaccines.

Science.gov (United States)

Salik, Elaha; Løvik, Ida; Andersen, Klaus E; Bygum, Anette

2016-11-02

There is increasing awareness of reactions to vaccination that include persistent skin reactions. We present here a retrospective investigation of long-lasting skin reactions and aluminium hypersensitivity in children, based on medical records and questionnaires sent to the parents. In the 10-year period 2003 to 2013 we identified 47 children with persistent skin reactions caused by childhood vaccinations. Most patients had a typical presentation of persisting pruritic subcutaneous nodules. Five children had a complex diagnostic process involving paediatricians, orthopaedics and plastic surgeons. Two patients had skin biopsies performed from their skin lesions, and 2 patients had the nodules surgically removed. Forty-two children had a patch-test performed with 2% aluminium chloride hexahydrate in petrolatum and 39 of them (92%) had a positive reaction. The persistent skin reactions were treated with potent topical corticosteroids and disappeared slowly. Although we advised families to continue vaccination of their children, one-third of parents omitted or postponed further vaccinations.
Regional Persistent Organic Pollutants' Environmental Impact Assessment and Control Model

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Jurgis Staniskis

2008-10-01

Full Text Available The sources of formation, environmental distribution and fate of persistent organic pollutants (POPs are increasingly seen as topics to be addressed and solved at the global scale. Therefore, there are already two international agreements concerning persistent organic pollutants: the Protocol of 1998 to the 1979 Convention on the Long-Range Transboundary Air Pollution on Persistent Organic Pollutants (Aarhus Protocol; and the Stockholm Convention on Persistent Organic Pollutants. For the assessment of environmental pollution of POPs, for the risk assessment, for the evaluation of new pollutants as potential candidates to be included in the POPs list of the Stokholmo or/and Aarhus Protocol, a set of different models are developed or under development. Multimedia models help describe and understand environmental processes leading to global contamination through POPs and actual risk to the environment and human health. However, there is a lack of the tools based on a systematic and integrated approach to POPs management difficulties in the region.
Genetic Screen Reveals the Role of Purine Metabolism in Staphylococcus aureus Persistence to Rifampicin

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Rebecca Yee

2015-12-01

Full Text Available Chronic infections with Staphylococcus aureus such as septicemia, osteomyelitis, endocarditis, and biofilm infections are difficult to treat because of persisters. Despite many efforts in understanding bacterial persistence, the mechanisms of persister formation in S. aureus remain elusive. Here, we performed a genome-wide screen of a transposon mutant library to study the molecular mechanisms involved in persistence of community-acquired S. aureus. Screening of the library for mutants defective in persistence or tolerance to rifampicin revealed many genes involved in metabolic pathways that are important for antibiotic persistence. In particular, the identified mutants belonged to metabolic pathways involved in carbohydrate, amino acid, lipid, vitamin and purine biosynthesis. Five mutants played a role in purine biosynthesis and two mutants, purB, an adenylosuccinate lyase, and purM, a phosphoribosylaminoimidazole synthetase, were selected for further confirmation. Mutants purB and purM showed defective persistence compared to the parental strain USA300 in multiple stress conditions including various antibiotics, low pH, and heat stress. The defect in persistence was restored by complementation with the wildtype purB and purM gene in the respective mutants. These findings provide new insights into the mechanisms of persistence in S. aureus and provide novel therapeutic targets for developing more effective treatment for persistent infections due to S. aureus.
Early life innate immune signatures of persistent food allergy.

Science.gov (United States)

Neeland, Melanie R; Koplin, Jennifer J; Dang, Thanh D; Dharmage, Shyamali C; Tang, Mimi L; Prescott, Susan L; Saffery, Richard; Martino, David J; Allen, Katrina J

2017-11-14

Food allergy naturally resolves in a proportion of food-allergic children without intervention; however the underlying mechanisms governing the persistence or resolution of food allergy in childhood are not understood. This study aimed to define the innate immune profiles associated with egg allergy at age 1 year, determine the phenotypic changes that occur with the development of natural tolerance in childhood, and explore the relationship between early life innate immune function and serum vitamin D. This study used longitudinally collected PBMC samples from a population-based cohort of challenge-confirmed egg-allergic infants with either persistent or transient egg allergy outcomes in childhood to phenotype and quantify the functional innate immune response associated with clinical phenotypes of egg allergy. We show that infants with persistent egg allergy exhibit a unique innate immune signature, characterized by increased numbers of circulating monocytes and dendritic cells that produce more inflammatory cytokines both at baseline and following endotoxin exposure when compared with infants with transient egg allergy. Follow-up analysis revealed that this unique innate immune signature continues into childhood in those with persistent egg allergy and that increased serum vitamin D levels correlate with changes in innate immune profiles observed in children who developed natural tolerance to egg. Early life innate immune dysfunction may represent a key immunological driver and predictor of persistent food allergy in childhood. Serum vitamin D may play an immune-modulatory role in the development of natural tolerance. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.
Ascent, descent, nullity, defect, and related notions for linear relations in linear spaces

NARCIS (Netherlands)

Sandovici, Adrian; de Snoo, Henk; Winkler, Henrik

2007-01-01

For a linear relation in a linear space the concepts of ascent, descent, nullity, and defect are introduced and studied. It is shown that the results of A.E. Taylor and M.A. Kaashoek concerning the relationship between ascent, descent, nullity, and defect for the case of linear operators remain
Persistent marine debris

International Nuclear Information System (INIS)

Levy, E.M.

1992-01-01

In this paper the distribution of persistent marine debris, adrift on world oceans and stranded on beaches globally, is reviewed and related to the known inputs and transport by the major surface currents. Since naturally occurring processes eventually degrade petroleum in the environment, international measures to reduce the inputs have been largely successful in alleviating oil pollution on a global, if not on a local, scale. Many plastics, however, are so resistant to natural degradation that merely controlling inputs will be insufficient, and more drastic and costly measures will be needed to cope with the emerging global problem posed by these materials
Prophages and growth dynamics confound experimental results with antibiotic-tolerant persister cells

DEFF Research Database (Denmark)

Harms, Alexander; Fino, Cinzia; Sørensen, Michael Askvad

2017-01-01

the validity of our model of persister formation in a refined assay setup that uses robust culture conditions and unravels the dynamics of persister cells through all bacterial growth stages. Our results confirm the importance of (p)ppGpp and Lon but no longer support a role of TA modules in E. coli persister......) modules. This model found considerable support among researchers studying persisters but also generated controversy as part of recent debates in the field. In this study, we therefore used our previous work as a model to critically examine common experimental procedures to understand and overcome......-tolerant persisters via induction of cryptic prophages. Similarly, the inadvertent infection of mutant strains with bacteriophage φ80, a notorious laboratory contaminant, apparently caused several of the phenotypes that we reported in our previous studies. We therefore reconstructed all infected mutants and probed...
A proof-of-concept implementation of persistence in a hierarchical storage system

International Nuclear Information System (INIS)

Grossman, R.; Qin, Xiao; Lifka, D.

1992-01-01

The concept of providing transparent access to a collection of files in a mass storage system is a familiar one. The goal of this project was to investigate the feasibility of providing similar access to a collection of persistent, complex objects. We describe an architecture for interfacing a persistent store of complex objects to a hierarchical storage system. Persistent object stores support the uniform creation, storage, and access of complex objects, regardless of their lifetimes. In other words, a mechanism is provided so that persistent objects outlive the processes which create them and can be accessed in a uniform manner by other processes. We validated this architecture by implementing a proof-of-concept system and testing the system on two stores of data. These tests indicate that this architecture supports the creation. storage and access of very large persistent object stores
Foxp3+ regulatory T cells control persistence of viral CNS infection.

Directory of Open Access Journals (Sweden)

Dajana Reuter

Full Text Available We earlier established a model of a persistent viral CNS infection using two week old immunologically normal (genetically unmodified mice and recombinant measles virus (MV. Using this model infection we investigated the role of regulatory T cells (Tregs as regulators of the immune response in the brain, and assessed whether the persistent CNS infection can be modulated by manipulation of Tregs in the periphery. CD4(+ CD25(+ Foxp3(+ Tregs were expanded or depleted during the persistent phase of the CNS infection, and the consequences for the virus-specific immune response and the extent of persistent infection were analyzed. Virus-specific CD8(+ T cells predominantly recognising the H-2D(b-presented viral hemagglutinin epitope MV-H(22-30 (RIVINREHL were quantified in the brain by pentamer staining. Expansion of Tregs after intraperitoneal (i.p. application of the superagonistic anti-CD28 antibody D665 inducing transient immunosuppression caused increased virus replication and spread in the CNS. In contrast, depletion of Tregs using diphtheria toxin (DT in DEREG (depletion of regulatory T cells-mice induced an increase of virus-specific CD8(+ effector T cells in the brain and caused a reduction of the persistent infection. These data indicate that manipulation of Tregs in the periphery can be utilized to regulate virus persistence in the CNS.
Persistent insomnia: the role of objective short sleep duration and mental health.

Science.gov (United States)

Vgontzas, Alexandros N; Fernandez-Mendoza, Julio; Bixler, Edward O; Singareddy, Ravi; Shaffer, Michele L; Calhoun, Susan L; Liao, Duanping; Basta, Maria; Chrousos, George P

2012-01-01

Few population-based, longitudinal studies have examined risk factors for persistent insomnia, and the results are inconsistent. Furthermore, none of these studies have examined the role of polysomnographic (PSG) variables such as sleep duration or sleep apnea on the persistence of insomnia. Representative longitudinal study. Sleep laboratory. From a random, general population sample of 1741 individuals of the adult Penn State Cohort, 1395 were followed-up after 7.5 years. Individuals underwent one-night PSG and full medical evaluation at baseline and a telephone interview at follow-up. PSG sleep duration was analyzed as a continuous variable and as a categorical variable: insomnia persistence, partial remission, and full remission were 44.0%, 30.0%, and 26.0%, respectively. Objective short sleep duration significantly increased the odds of persistent insomnia as compared to normal sleep (OR = 3.19) and to fully remitted insomnia (OR = 4.92). Mental health problems at baseline were strongly associated with persistent insomnia as compared to normal sleep (OR = 9.67) and to a lesser degree compared to fully remitted insomnia (OR = 3.68). Smoking, caffeine, and alcohol consumption and sleep apnea did not predict persistent insomnia. Objective short sleep duration and mental health problems are the strongest predictors of persistent insomnia. These data further support the validity and clinical utility of objective short sleep duration as a novel marker of the biological severity of insomnia.
Increased serum concentrations of persistent organic pollutants among prediabetic individuals

DEFF Research Database (Denmark)

Færch, Kristine Villum; Højlund, Kurt; Vind, Birgitte Falbe

2012-01-01

There is a need for a better understanding of the potential role of persistent organic pollutants (POPs) in the pathogenesis of type 2 diabetes.......There is a need for a better understanding of the potential role of persistent organic pollutants (POPs) in the pathogenesis of type 2 diabetes....
Investigating Students' Modes of Thinking in Linear Algebra: The Case of Linear Independence

Science.gov (United States)

Çelik, Derya

2015-01-01

Linear algebra is one of the most challenging topics to learn and teach in many countries. To facilitate the teaching and learning of linear algebra, priority should be given to epistemologically analyze the concepts that the undergraduate students have difficulty in conceptualizing and to define their ways of reasoning in linear algebra. After…
Distributed Persistent Identifiers System Design

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Pavel Golodoniuc

2017-06-01

Full Text Available The need to identify both digital and physical objects is ubiquitous in our society. Past and present persistent identifier (PID systems, of which there is a great variety in terms of technical and social implementation, have evolved with the advent of the Internet, which has allowed for globally unique and globally resolvable identifiers. PID systems have, by in large, catered for identifier uniqueness, integrity, and persistence, regardless of the identifier’s application domain. Trustworthiness of these systems has been measured by the criteria first defined by Bütikofer (2009 and further elaborated by Golodoniuc 'et al'. (2016 and Car 'et al'. (2017. Since many PID systems have been largely conceived and developed by a single organisation they faced challenges for widespread adoption and, most importantly, the ability to survive change of technology. We believe that a cause of PID systems that were once successful fading away is the centralisation of support infrastructure – both organisational and computing and data storage systems. In this paper, we propose a PID system design that implements the pillars of a trustworthy system – ensuring identifiers’ independence of any particular technology or organisation, implementation of core PID system functions, separation from data delivery, and enabling the system to adapt for future change. We propose decentralisation at all levels — persistent identifiers and information objects registration, resolution, and data delivery — using Distributed Hash Tables and traditional peer-to-peer networks with information replication and caching mechanisms, thus eliminating the need for a central PID data store. This will increase overall system fault tolerance thus ensuring its trustworthiness. We also discuss important aspects of the distributed system’s governance, such as the notion of the authoritative source and data integrity
Persistent producer-scrounger relationships in bats.

Science.gov (United States)

Harten, Lee; Matalon, Yasmin; Galli, Naama; Navon, Hagit; Dor, Roi; Yovel, Yossi

2018-02-01

Social foraging theory suggests that group-living animals gain from persistent social bonds, which lead to increased tolerance in competitive foraging and information sharing. Bats are among the most social mammals, often living in colonies of tens to thousands of individuals for dozens of years, yet little is known about their social foraging dynamics. We observed three captive bat colonies for over a year, quantifying >13,000 social foraging interactions. We found that individuals consistently used one of two foraging strategies, either producing (collecting) food themselves or scrounging it directly from the mouth of other individuals. Individual foraging types were consistent over at least 16 months except during the lactation period when females shifted toward producing. Scroungers intentionally selected whom to interact with when socially foraging, thus generating persistent nonrandom social relationships with two to three specific producers. These persistent producer-scrounger relationships seem to reduce aggression over time. Finally, scrounging was highly correlated with vigilance, and we hypothesize that vigilant-prone individuals turn to scrounging in the wild to mitigate the risk of landing on a potentially unsafe fruit tree. We find the bat colony to be a rich and dynamic social system, which can serve as a model to study the role that social foraging plays in the evolution of mammalian sociality. Our results highlight the importance of considering individual tendencies when exploring social behavior patterns of group-living animals. These tendencies further emphasize the necessity of studying social networks over time.
Efficient non-linear two-photon effects from the Cesium 6D manifold

Science.gov (United States)

Haluska, Nathan D.; Perram, Glen P.; Rice, Christopher A.

2018-02-01

We report several non-linear process that occur when two-photon pumping the cesium 6D states. Cesium vapor possess some of the largest two-photon pump cross sections in nature. Pumping these cross sections leads to strong amplified spontaneous emission that we observe on over 17 lasing lines. These new fields are strong enough to couple with the pump to create additional tunable lines. We use a heat pipe with cesium densities of 1014 to 1016 cm-3 and 0 to 5 Torr of helium buffer gas. The cesium 6D States are interrogated by both high energy pulses and low power CW sources. We observe four-wave mixing, six-wave mixing, potential two-photon lasing, other unknown nonlinear processes, and the persistence of some processes at low thresholds. This system is also uniquely qualified to support two-photon lasing under the proper conditions.
Non linear system become linear system

Directory of Open Access Journals (Sweden)

Petre Bucur

2007-01-01

Full Text Available The present paper refers to the theory and the practice of the systems regarding non-linear systems and their applications. We aimed the integration of these systems to elaborate their response as well as to highlight some outstanding features.
Medical and sociodemographic factors predict persistent smoking after coronary events.

Science.gov (United States)

Sverre, Elise; Otterstad, Jan Erik; Gjertsen, Erik; Gullestad, Lars; Husebye, Einar; Dammen, Toril; Moum, Torbjørn; Munkhaugen, John

2017-09-06

Understanding the determinants of persistent smoking after a coronary event constitutes the basis of modelling interventions of smoking cessation in secondary prevention programs. We aim to identify the potentially modifiable medical, sociodemographic and psychosocial factors, comprising the study factors, associated with unfavourable risk factor control after CHD events. A cross-sectional explorative study used logistic regression analysis to investigate the association between study factors and smoking status in 1083 patients hospitalized with myocardial infarction and/or coronary revascularization. Hospital record data, a self-report questionnaire, clinical examination and blood samples were applied. At the index hospitalization, 390 patients were smoking and at follow-up after 2-36 months 167 (43%) of these had quit, while 230 reported persistent smoking. In adjusted analyses, unemployed or disability benefits (Odds ratio (OR) 4.1), low education (OR 3.5), longer smoking duration (OR 2.3) and not having ST-elevation myocardial infarction (STEMI) as index event (OR 2.3) were significantly associated with persistent smoking. Psychosocial factors at follow-up were not associated with persistent smoking. Smokers reported high motivation for cessation, with 68% wanting help to quit. Only 42% had been offered nicotine replacement therapy or other cessation aids. Smokers rated use of tobacco as the most important cause of their coronary disease (6.8 on a 1-10 Likert scale). Low socioeconomic status, prior duration of smoking, and not having STEMI as index event were associated with persisting smoking. Persistent smokers in this study seem to have an acceptable risk perception and were motivated to cease smoking, but needed assistance through cessation programs including prescription of pharmacological aids. Registered at ClinicalTrials.gov: NCT02309255 , registered retrospectively.
Cloud and radiance measurements with the VIS/NIR Daylight Whole Sky Imager at Lindenberg (Germany)

Energy Technology Data Exchange (ETDEWEB)

Feister, U. [Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg (Germany); Shields, J. [Scripps Inst. of Oceanography, Univ. of California, San Diego (United States)

2005-10-01

Ground-based cloud data acquired with the whole sky imager (WSI) are analyzed in relation to measurements of solar radiation performed at the Lindenberg Meteorological Observatory. Cloud fractions derived by the cloud detection algorithm from WSI images acquired during daylight hours between 2002 and 2004 are compared with conventional cloud observations for the two sites Potsdam and Lindenberg, and also with ceilometer data of cloud-base heights at Lindenberg. The comparison statistics are discussed in the context of different principles of measurement. A few case studies illustrate the strong scattering effect of clouds on solar radiance and irradiance measured at the ground in different spectral regions. Particularly clouds close to the apparent position of the sun lead to strong enhancements of solar diffuse irradiance incident on horizontal planes and hemispheres that substantially exceed corresponding clear-sky values. Irradiances derived from WSI sky radiance fields are shown in comparison to pyranometer data of diffuse irradiance and radiative transfer model calculations performed for clear sky conditions. Examples of spectral sky radiances with moving contrails illustrate the significant enhancement the contrails have compared to clear sky, even though they may have a relatively small direct effect on global irradiance values. As contrails are observed at Lindenberg for about 18 to 19% of daylight hours, and part of them become clouds, the indirect impact of these changes on solar irradiance received at the ground may not be negligible. (orig.)
Linear algebra

CERN Document Server

Edwards, Harold M

1995-01-01

In his new undergraduate textbook, Harold M Edwards proposes a radically new and thoroughly algorithmic approach to linear algebra Originally inspired by the constructive philosophy of mathematics championed in the 19th century by Leopold Kronecker, the approach is well suited to students in the computer-dominated late 20th century Each proof is an algorithm described in English that can be translated into the computer language the class is using and put to work solving problems and generating new examples, making the study of linear algebra a truly interactive experience Designed for a one-semester course, this text adopts an algorithmic approach to linear algebra giving the student many examples to work through and copious exercises to test their skills and extend their knowledge of the subject Students at all levels will find much interactive instruction in this text while teachers will find stimulating examples and methods of approach to the subject

Non-nutritional factors affecting lactation persistency in dairy ewes: a review

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Antonello Cannas

2010-01-01

Full Text Available Milk production is largely related to the shape of the lactation curve. Key elements of the lactation pattern are peak yield, which is the maximum daily yield reached during lactation, and lactation persistency, which is the medium rate of milk yield decrease after the lactation peak. The ideal lactation curve should have a reasonably high peak and a flat trend afterwards. A more persistent lactation is desirable because it is related to better animal health and reduction of feeding costs. Effective strategies to improve lactation persistency require a deep understanding of the main factors that affect this trait, including genetics, hormonal status and administration, udder morphology, seasonal changes, management, animal health (e.g. mastitis, stress and nutrition. This review covers the effects of non-nutritional factors on lactation persistency in dairy sheep.
Persistent Skin Reactions and Aluminium Hypersensitivity Induced by Childhood Vaccines

DEFF Research Database (Denmark)

Salik, Elaha; Løvik, Ida; Andersen, Klaus E

2016-01-01

There is increasing awareness of reactions to vaccination that include persistent skin reactions. We present here a retrospective investigation of long-lasting skin reactions and aluminium hypersensitivity in children, based on medical records and questionnaires sent to the parents. In the 10-year...... period 2003 to 2013 we identified 47 children with persistent skin reactions caused by childhood vaccinations. Most patients had a typical presentation of persisting pruritic subcutaneous nodules. Five children had a complex diagnostic process involving paediatricians, orthopaedics and plastic surgeons...... treated with potent topical corticosteroids and disappeared slowly. Although we advised families to continue vaccination of their children, one-third of parents omitted or postponed further vaccinations....
PERSISTENCE IN PERFORMANCE FOR MUTUAL FUNDS IN PERIODS OF CRISIS

Directory of Open Access Journals (Sweden)

Theodoros KARGIDIS

2012-09-01

Full Text Available The study investigates the persistence in performance for a sample of South European funds, domiciled in Portugal, Italy, Greece and Spain. Employing the Sharpe ratio, risk adjusted performance is measured in an attempt to judge the influence of the 2008 crisis and the current debt crisis on funds’ inclination to persist in their previous returns record. Examination period extends from January 2004 to December 2010 incorporating stages of relative stability in the stock and bond markets while also capturing the early stages of the eurozone crisis. We categorize funds as winners and losers in consecutive 6-monthly periods, thus being able to judge persistence in the short run, while our results suggest that the identification of winners and losers could enable us to investigate the possibility to gain investment advantages through this finding. Overall results suggest evidence of persistent results, whether positive or negative, both during the 2008 crisis and the current debt crisis, leading us to deduce that factors leading to performance persistence are not affected by market changes, since medium to long term persistence bypasses any temporary market mischief. This finding could be of use for fund managers aiming at establishing viable investment strategies, at their epicenter being the exploitation of such clues, suggesting persistence in returns. A fund of funds manager employing funds both in equities and fixed income could potentially choose to invest exclusively or more heavily in the winners of previous periods and avoid accordingly poor performers, thus achieving higher returns on average. For this purpose simple investment strategies are employed where we test the outcome of an investment strategy that would invest on fixed income securities by choosing those funds that were winners in the distribution of returns in the previous 6-monthly period, while disinvesting from poor performers and funds switching sides in performance
Return-Volatility Relationship: Insights from Linear and Non-Linear Quantile Regression

NARCIS (Netherlands)

D.E. Allen (David); A.K. Singh (Abhay); R.J. Powell (Robert); M.J. McAleer (Michael); J. Taylor (James); L. Thomas (Lyn)

2013-01-01

textabstractThe purpose of this paper is to examine the asymmetric relationship between price and implied volatility and the associated extreme quantile dependence using linear and non linear quantile regression approach. Our goal in this paper is to demonstrate that the relationship between the
No Exit: Predicting Student Persistence. AIR 1990 Annual Forum Paper.

Science.gov (United States)

Beil, Cheryl; Shope, Janet H.

A longitudinal study was conducted to determine the factors influencing college student persistence in remaining in school. Persistence was examined at two points: after the first year and 4 years after enrollment. The study was conducted at an urban university using the American College Testing's Entering Student Survey and Student Opinion…
Comparison of linear and non-linear models for predicting energy expenditure from raw accelerometer data.

Science.gov (United States)

Montoye, Alexander H K; Begum, Munni; Henning, Zachary; Pfeiffer, Karin A

2017-02-01

This study had three purposes, all related to evaluating energy expenditure (EE) prediction accuracy from body-worn accelerometers: (1) compare linear regression to linear mixed models, (2) compare linear models to artificial neural network models, and (3) compare accuracy of accelerometers placed on the hip, thigh, and wrists. Forty individuals performed 13 activities in a 90 min semi-structured, laboratory-based protocol. Participants wore accelerometers on the right hip, right thigh, and both wrists and a portable metabolic analyzer (EE criterion). Four EE prediction models were developed for each accelerometer: linear regression, linear mixed, and two ANN models. EE prediction accuracy was assessed using correlations, root mean square error (RMSE), and bias and was compared across models and accelerometers using repeated-measures analysis of variance. For all accelerometer placements, there were no significant differences for correlations or RMSE between linear regression and linear mixed models (correlations: r = 0.71-0.88, RMSE: 1.11-1.61 METs; p > 0.05). For the thigh-worn accelerometer, there were no differences in correlations or RMSE between linear and ANN models (ANN-correlations: r = 0.89, RMSE: 1.07-1.08 METs. Linear models-correlations: r = 0.88, RMSE: 1.10-1.11 METs; p > 0.05). Conversely, one ANN had higher correlations and lower RMSE than both linear models for the hip (ANN-correlation: r = 0.88, RMSE: 1.12 METs. Linear models-correlations: r = 0.86, RMSE: 1.18-1.19 METs; p linear models for the wrist-worn accelerometers (ANN-correlations: r = 0.82-0.84, RMSE: 1.26-1.32 METs. Linear models-correlations: r = 0.71-0.73, RMSE: 1.55-1.61 METs; p models offer a significant improvement in EE prediction accuracy over linear models. Conversely, linear models showed similar EE prediction accuracy to machine learning models for hip- and thigh
Advanced statistics: linear regression, part II: multiple linear regression.

Science.gov (United States)

Marill, Keith A

2004-01-01

The applications of simple linear regression in medical research are limited, because in most situations, there are multiple relevant predictor variables. Univariate statistical techniques such as simple linear regression use a single predictor variable, and they often may be mathematically correct but clinically misleading. Multiple linear regression is a mathematical technique used to model the relationship between multiple independent predictor variables and a single dependent outcome variable. It is used in medical research to model observational data, as well as in diagnostic and therapeutic studies in which the outcome is dependent on more than one factor. Although the technique generally is limited to data that can be expressed with a linear function, it benefits from a well-developed mathematical framework that yields unique solutions and exact confidence intervals for regression coefficients. Building on Part I of this series, this article acquaints the reader with some of the important concepts in multiple regression analysis. These include multicollinearity, interaction effects, and an expansion of the discussion of inference testing, leverage, and variable transformations to multivariate models. Examples from the first article in this series are expanded on using a primarily graphic, rather than mathematical, approach. The importance of the relationships among the predictor variables and the dependence of the multivariate model coefficients on the choice of these variables are stressed. Finally, concepts in regression model building are discussed.
Cellular Automata Rules and Linear Numbers

OpenAIRE

Nayak, Birendra Kumar; Sahoo, Sudhakar; Biswal, Sagarika

2012-01-01

In this paper, linear Cellular Automta (CA) rules are recursively generated using a binary tree rooted at "0". Some mathematical results on linear as well as non-linear CA rules are derived. Integers associated with linear CA rules are defined as linear numbers and the properties of these linear numbers are studied.
The relation between persistent coma and brain ischemia after severe brain injury.

Science.gov (United States)

Cheng, Quan; Jiang, Bing; Xi, Jian; Li, Zhen Yan; Liu, Jin Fang; Wang, Jun Yu

2013-12-01

To investigate the relation between brain ischemia and persistent vegetative state after severe traumatic brain injury. The 66 patients with severe brain injury were divided into two groups: The persistent coma group (coma duration ≥10 d) included 51 patients who had an admission Glasgow Coma Scale (GCS) of 5-8 and were unconscious for more than 10 d. There were 15 patients in the control group, their admission GCS was 5-8, and were unconscious for less than 10 d. The brain areas, including frontal, parietal, temporal, occipital lobes and thalamus, were measured by Single Photon Emission Computed Tomography (SPECT). In the first SPECT scan, multiple areas of cerebral ischemia were documented in all patients in both groups, whereas bilateral thalamic ischemia were presented in all patients in the persistent coma group and were absented in the control group. In the second SPECT scan taken during the period of analepsia, with an indication that unilateral thalamic ischemia were persisted in 28 of 41 patients in persistent coma group(28/41,68.29%). Persistent coma after severe brain injury is associated with bilateral thalamic ischemia.
Persistence of Overseeded Cool-Season Grasses in Bermudagrass Turf

OpenAIRE

Thomas Serensits; Matthew Cutulle; Jeffrey F. Derr

2011-01-01

Cool-season grass species are commonly overseeded into bermudagrass turf for winter color. When the overseeded grass persists beyond the spring; however, it becomes a weed. The ability of perennial ryegrass, Italian (annual) ryegrass, intermediate ryegrass, and hybrid bluegrass to persist in bermudagrass one year after seeding was determined. Perennial ryegrass, intermediate ryegrass, and Italian ryegrass produced acceptable ground cover in the spring after fall seeding. Hybrid bluegrass di...
Determination and Correction of Persistent Biases in Quantum Annealers

Science.gov (United States)

2016-08-25

for all of the qubits. Narrowing of the bias distribution. To show the correctability of the persistent biases , we ran the experiment described above...this is a promising application for bias correction . Importantly, while the J biases determined here are in general smaller than the h biases , numerical...1Scientific RepoRts | 6:18628 | DOI: 10.1038/srep18628 www.nature.com/scientificreports Determination and correction of persistent biases in quantum
Incidence and Risk Factors of Persistent Hyperparathyroidism After Kidney Transplantation.

Science.gov (United States)

Nakai, K; Fujii, H; Ishimura, T; Fujisawa, M; Nishi, S

Persistent hyperparathyroidism after kidney transplantation is related to graft function, but pre-transplantation risk factors of persistent hyperparathyroidism have not been evaluated in detail. We enrolled 86 patients who had undergone kidney transplantation between 2008 and 2014. Nine patients showed persistent hyperparathyroidism characterized by the following: 1) serum parathyroid hormone levels >65 pg/mL and serum calcium levels >10.5 mg/dL at 1 year after kidney transplantation; 2) parathyroidectomy after kidney transplantation; and 3) reintroduction of cinacalcet after kidney transplantation. Compared with other patients, these 9 patients had significantly longer duration of dialysis therapy (186 ± 74 mo vs 57 ± 78 mo) and more frequent treatment with cinacalcet during dialysis (89% vs 12%). Multivariate analysis showed that dialysis vintage, calcium phosphate products, and cinacalcet use before kidney transplantation were independent risk factors of persistent hyperparathyroidism after kidney transplantation. A receiver operating characteristic curve showed 72 months as the cutoff value of dialysis vintage and 55 as the cutoff value of calcium phosphate products. In conclusion, dialysis vintage >6 years, calcium phosphate products >55 (mg/dL) 2 , and cinacalcet use before kidney transplantation are strong predictors of persistent hyperparathyroidism. High-risk patients should be evaluated for parathyroid enlargement, and parathyroidectomy must be considered before kidney transplantation. Copyright © 2016 Elsevier Inc. All rights reserved.
Linear Colliders TESLA

International Nuclear Information System (INIS)

Anon.

1994-01-01

The aim of the TESLA (TeV Superconducting Linear Accelerator) collaboration (at present 19 institutions from seven countries) is to establish the technology for a high energy electron-positron linear collider using superconducting radiofrequency cavities to accelerate its beams. Another basic goal is to demonstrate that such a collider can meet its performance goals in a cost effective manner. For this the TESLA collaboration is preparing a 500 MeV superconducting linear test accelerator at the DESY Laboratory in Hamburg. This TTF (TESLA Test Facility) consists of four cryomodules, each approximately 12 m long and containing eight 9-cell solid niobium cavities operating at a frequency of 1.3 GHz
Modelling the role of Tax expression in HTLV-I persistence in vivo.

Science.gov (United States)

Li, Michael Y; Lim, Aaron G

2011-12-01

Human T-lymphotropic virus type I (HTLV-I) is a persistent human retrovirus characterized by life-long infection and risk of developing HAM/TSP, a progressive neurological and inflammatory disease, and adult T-cell leukemia (ATL). Chronically infected individuals often harbor high proviral loads despite maintaining a persistently activated immune response. Based on a new hypothesis for the persistence of HTLV-I infection, a three-dimensional compartmental model is constructed that describes the dynamic interactions among latently infected target cells, target-cell activation, and immune responses to HTLV-I, with an emphasis on understanding the role of Tax expression in the persistence of HTLV-I.
Intergenerational Top Income Persistence

DEFF Research Database (Denmark)

Munk, Martin D.; Bonke, Jens; Hussain, M. Azhar

2016-01-01

In this paper, we investigate intergenerational top earnings and top income mobility in Denmark. Access to administrative registers allowed us to look at very small fractions of the population. We find that intergenerational mobility is lower in the top when including capital income in the income...... measure— for the rich top 0.1% fathers and sons the elasticity is 0.466. Compared with Sweden, however, the intergenerational top income persistence is about half the size in Denmark....
Dynamics of unsymmetric piecewise-linear/non-linear systems using finite elements in time

Science.gov (United States)

Wang, Yu

1995-08-01

The dynamic response and stability of a single-degree-of-freedom system with unsymmetric piecewise-linear/non-linear stiffness are analyzed using the finite element method in the time domain. Based on a Hamilton's weak principle, this method provides a simple and efficient approach for predicting all possible fundamental and sub-periodic responses. The stability of the steady state response is determined by using Floquet's theory without any special effort for calculating transition matrices. This method is applied to a number of examples, demonstrating its effectiveness even for a strongly non-linear problem involving both clearance and continuous stiffness non-linearities. Close agreement is found between available published findings and the predictions of the finite element in time approach, which appears to be an efficient and reliable alternative technique for non-linear dynamic response and stability analysis of periodic systems.
Low Socioeconomic Status Men Persisting in College: A Phenomenological Study

Science.gov (United States)

Crichton, Dusten D.

2017-01-01

The purpose of this phenomenological study was to explore and to tell the stories of low socioeconomic status (SES) men in college who persisted beyond the halfway point of college at a Midwestern metropolitan university. Prior research suggested men from low socioeconomic status backgrounds matriculated and persisted in college at the lowest…
Linear and non-linear amplification of high-mode perturbations at the ablation front in HiPER targets

Energy Technology Data Exchange (ETDEWEB)

Olazabal-Loume, M; Breil, J; Hallo, L; Ribeyre, X [CELIA, UMR 5107 Universite Bordeaux 1-CNRS-CEA, 351 cours de la Liberation, 33405 Talence (France); Sanz, J, E-mail: olazabal@celia.u-bordeaux1.f [ETSI Aeronauticos, Universidad Politecnica de Madrid, Madrid 28040 (Spain)

2011-01-15

The linear and non-linear sensitivity of the 180 kJ baseline HiPER target to high-mode perturbations, i.e. surface roughness, is addressed using two-dimensional simulations and a complementary analysis by linear and non-linear ablative Rayleigh-Taylor models. Simulations provide an assessment of an early non-linear stage leading to a significant deformation of the ablation surface for modes of maximum linear growth factor. A design using a picket prepulse evidences an improvement in the target stability inducing a delay of the non-linear behavior. Perturbation evolution and shape, evidenced by simulations of the non-linear stage, are analyzed with existing self-consistent non-linear theory.
Persistence of canine distemper virus in the Greater Yellowstone Ecosystem's carnivore community

Science.gov (United States)

Almberg, E.S.; Cross, P.C.; Smith, D.W.

2010-01-01

Canine distemper virus (CDV) is an acute, highly immunizing pathogen that should require high densities and large populations of hosts for long-term persistence, yet CDV persists among terrestrial carnivores with small, patchily distributed groups. We used CDV in the Greater Yellowstone ecosystem's (GYE) wolves (Canis lupus) and coyotes (Canis latrans) as a case study for exploring how metapopulation structure, host demographics, and multi-host transmission affect the critical community size and spatial scale required for CDV persistence. We illustrate how host spatial connectivity and demographic turnover interact to affect both local epidemic dynamics, such as the length and variation in inter-epidemic periods, and pathogen persistence using stochastic, spatially explicit susceptible-exposed-infectious-recovered simulation models. Given the apparent absence of other known persistence mechanisms (e.g., a carrier or environmental state, densely populated host, chronic infection, or a vector), we suggest that CDV requires either large spatial scales or multi-host transmission for persistence. Current GYE wolf populations are probably too small to support endemic CDV. Coyotes are a plausible reservoir host, but CDV would still require 50 000-100 000 individuals for moderate persistence (>50% over 10 years), which would equate to an area of 1-3 times the size of the GYE (60000-200000 km2). Coyotes, and carnivores in general, are not uniformly distributed; therefore, this is probably a gross underestimate of the spatial scale of CDV persistence. However, the presence of a second competent host species can greatly increase the probability of long-term CDV persistence at much smaller spatial scales. Although no management of CDV is currently recommended for the GYE, wolf managers in the region should expect periodic but unpredictable CDV-related population declines as often as every 2-5 years. Awareness and monitoring of such outbreaks will allow corresponding
Persistence of canine distemper virus in the Greater Yellowstone ecosystem's carnivore community.

Science.gov (United States)

Almberg, Emily S; Cross, Paul C; Smith, Douglas W

2010-10-01

Canine distemper virus (CDV) is an acute, highly immunizing pathogen that should require high densities and large populations of hosts for long-term persistence, yet CDV persists among terrestrial carnivores with small, patchily distributed groups. We used CDV in the Greater Yellowstone ecosystem's (GYE) wolves (Canis lupus) and coyotes (Canis latrans) as a case study for exploring how metapopulation structure, host demographics, and multi-host transmission affect the critical community size and spatial scale required for CDV persistence. We illustrate how host spatial connectivity and demographic turnover interact to affect both local epidemic dynamics, such as the length and variation in inter-epidemic periods, and pathogen persistence using stochastic, spatially explicit susceptible-exposed-infectious-recovered simulation models. Given the apparent absence of other known persistence mechanisms (e.g., a carrier or environmental state, densely populated host, chronic infection, or a vector), we suggest that CDV requires either large spatial scales or multi-host transmission for persistence. Current GYE wolf populations are probably too small to support endemic CDV. Coyotes are a plausible reservoir host, but CDV would still require 50000-100000 individuals for moderate persistence (> 50% over 10 years), which would equate to an area of 1-3 times the size of the GYE (60000-200000 km2). Coyotes, and carnivores in general, are not uniformly distributed; therefore, this is probably a gross underestimate of the spatial scale of CDV persistence. However, the presence of a second competent host species can greatly increase the probability of long-term CDV persistence at much smaller spatial scales. Although no management of CDV is currently recommended for the GYE, wolf managers in the region should expect periodic but unpredictable CDV-related population declines as often as every 2-5 years. Awareness and monitoring of such outbreaks will allow corresponding adjustments

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