Properties of Linear Contrails Detected in 2012 Northern Hemisphere MODIS Imagery
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.
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.
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.
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.)
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.
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.
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.
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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.
Energy Technology Data Exchange (ETDEWEB)
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?
Directory of Open Access Journals (Sweden)
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
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.
Impact of biofuels on contrail warming
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.
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
Directory of Open Access Journals (Sweden)
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
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
A numerical simulation of a contrail
Energy Technology Data Exchange (ETDEWEB)
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.
Remote sensing of contrails and aircraft altered cirrus clouds
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
Microphysical properties of contrails and natural cirrus clouds
Energy Technology Data Exchange (ETDEWEB)
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.
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
Energy Technology Data Exchange (ETDEWEB)
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.
Microphysical properties of contrails and natural cirrus clouds
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
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)
Measurement of Contrails Using ADS-B Data
Directory of Open Access Journals (Sweden)
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.
Detection of jet contrails from satellite images
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.
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.
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.
Aircraft clouds: from chemtrail pseudoscience to the science of contrails
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...
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.
Directory of Open Access Journals (Sweden)
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 %.
Variability of the contrail radiative forcing due to crystal shape
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
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.
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 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.
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)
Directory of Open Access Journals (Sweden)
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.
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.
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
Directory of Open Access Journals (Sweden)
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 >1×10^{15} (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.
In-situ observations of young contrails – overview and selected results from the CONCERT campaign
Directory of Open Access Journals (Sweden)
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 (SO_{2}, reactive nitrogen and halogen species (NO, NO_{y}, HNO_{3}, HONO, HCl, ozone (O_{3} 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 H_{2}SO_{4} (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.
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.
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.
Directory of Open Access Journals (Sweden)
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.
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.)
Off-Line Robust Constrained MPC for Linear Time-Varying Systems with Persistent Disturbances
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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.
The impact of diurnal variations of air traffic on contrail radiative forcing
Directory of Open Access Journals (Sweden)
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%.
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)
Ground-based mobile scanning LIDAR for remote sensing of contrails
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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.
Carbon balance of China constrained by CONTRAIL aircraft CO2 measurements
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.
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
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.)
Contrail Cirrus Forecasts for the ML-CIRRUS Experiment and Some Comparison Results
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
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.
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.
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.
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.
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...
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.
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....
Alternative-Fuel Effects on Contrails & Cruise Emissions (ACCESS-2) Flight Experiment
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.
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.
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
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.
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.
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
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.
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.
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.
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...
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.
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...
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...
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...
Modelling asymmetric persistence over the business cycle
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
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.
Multi-scale path planning for reduced environmental impact of aviation
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.
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
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)
International Nuclear Information System (INIS)
Vretenar, M
2014-01-01
The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics
Linearization Method and Linear Complexity
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.
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...
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
Solow, Daniel
2014-01-01
This text covers the basic theory and computation for a first course in linear programming, including substantial material on mathematical proof techniques and sophisticated computation methods. Includes Appendix on using Excel. 1984 edition.
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...
Berberian, Sterling K
2014-01-01
Introductory treatment covers basic theory of vector spaces and linear maps - dimension, determinants, eigenvalues, and eigenvectors - plus more advanced topics such as the study of canonical forms for matrices. 1992 edition.
Searle, Shayle R
2012-01-01
This 1971 classic on linear models is once again available--as a Wiley Classics Library Edition. It features material that can be understood by any statistician who understands matrix algebra and basic statistical methods.
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.
Linearly Refined Session Types
Directory of Open Access Journals (Sweden)
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.
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...
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
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
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....
Karloff, Howard
1991-01-01
To this reviewer’s knowledge, this is the first book accessible to the upper division undergraduate or beginning graduate student that surveys linear programming from the Simplex Method…via the Ellipsoid algorithm to Karmarkar’s algorithm. Moreover, its point of view is algorithmic and thus it provides both a history and a case history of work in complexity theory. The presentation is admirable; Karloff's style is informal (even humorous at times) without sacrificing anything necessary for understanding. Diagrams (including horizontal brackets that group terms) aid in providing clarity. The end-of-chapter notes are helpful...Recommended highly for acquisition, since it is not only a textbook, but can also be used for independent reading and study. —Choice Reviews The reader will be well served by reading the monograph from cover to cover. The author succeeds in providing a concise, readable, understandable introduction to modern linear programming. —Mathematics of Computing This is a textbook intend...
Persistent myalgia following whiplash.
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.
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...
Reduction of Linear Programming to Linear Approximation
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.
Persistent and recurrent hyperparathyroidism.
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.
Persistent luminescence nanothermometers
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.
Directory of Open Access Journals (Sweden)
Tanwiwat Jaikuna
2017-02-01
Full Text Available Purpose: To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL model. Material and methods : The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR, and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD2 was calculated using biological effective dose (BED based on the LQL model. The software calculation and the manual calculation were compared for EQD2 verification with pair t-test statistical analysis using IBM SPSS Statistics version 22 (64-bit. Results: Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV determined by D90%, 0.56% in the bladder, 1.74% in the rectum when determined by D2cc, and less than 1% in Pinnacle. The difference in the EQD2 between the software calculation and the manual calculation was not significantly different with 0.00% at p-values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT and 0.240, 0.320, and 0.849 for brachytherapy (BT in HR-CTV, bladder, and rectum, respectively. Conclusions : The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT.
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...
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
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.
Is corruption really persistent?
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
Persistent Hiccups Following Stapedectomy
Directory of Open Access Journals (Sweden)
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.
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...
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....
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....
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.
Linear interictal pain in Epicrania Fugax.
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.
Linear Algebra and Smarandache Linear Algebra
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...
Inflation persistence and flexible prices
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 ...
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.
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
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...
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...
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
Persistence extends reciprocity.
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.
Persistence of airline accidents.
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.
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.
Rotenone persistence model for montane streams
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.
Directory of Open Access Journals (Sweden)
Sabrina Araújo Pinho Costa
2015-01-01
Full Text Available Caliber-persistent artery (CPLA of the lip is a common vascular anomaly in which a main arterial branch extends to the surface of the mucous tissue with no reduction in its diameter. It usually manifests as pulsatile papule, is easily misdiagnosed, and is observed more frequently among older people, suggesting that its development may involve a degenerative process associated with aging; CPLA is also characterized by the loss of tone of the adjacent supporting connective tissue. Although the diagnosis is clinical, high-resolution Doppler ultrasound is a useful noninvasive tool for evaluating the lesion. This report describes the case of a 58-year-old male patient who complained of a lesion of the lower lip with bleeding and recurrent ulceration. The patient was successfully treated in our hospital after a diagnosis of CPLA and is currently undergoing a clinical outpatient follow-up with no complaints.
Directory of Open Access Journals (Sweden)
Francesco Cipollini
2007-03-01
Full Text Available Chronic cough is a stressful condition and can lead to extensive investigations. We report a case of a 48-year-old woman who had suffered from persistent chronic cough for more than 3 months. She had been treated with cough suppressant. However, her cough was not alleviated by these treatments, and the patient was referred to our hospital. She did not exhibit typical gastroesophageal reflux disease (GERD symptoms heartburn and regurgitation. Esophagoscopy did not disclose reflux esophagitis. The patient was treated with a proton-pump inhibitor, which markedly alleviated her cough. Chronic cough due to GERD was diagnosed. Although the diagnosis of chronic cough due to GERD is not easy when traditionally symptoms are not present, our case report underscores the importance of this association to the differential diagnosis of chronic cough. In these cases a relatively simple test as high dose proton pump-inhibitors trial may be useful to confirm GERD related cough.
Directory of Open Access Journals (Sweden)
Alok Tyagi
2012-01-01
Full Text Available New daily persistent headache (NDPH is a chronic headache developing in a person who does not have a past history of headaches. The headache begins acutely and reaches its peak within 3 days. It is important to exclude secondary causes, particularly headaches due to alterations in cerebrospinal fluid (CSF pressure and volume. A significant proportion of NDPH sufferers may have intractable headaches that are refractory to treatment. The condition is best viewed as a syndrome rather than a diagnosis. The headache can mimic chronic migraine and chronic tension-type headache, and it is also important to exclude secondary causes, particularly headaches due to alterations in CSF pressure and volume. A large proportion of NDPH sufferers have migrainous features to their headache and should be managed with treatments used for treating migraine. A small group of NDPH sufferers may have intractable headaches that are refractory to treatment.
Persistent idiopathic facial pain
DEFF Research Database (Denmark)
Maarbjerg, Stine; Wolfram, Frauke; Heinskou, Tone Bruvik
2017-01-01
Introduction: Persistent idiopathic facial pain (PIFP) is a poorly understood chronic orofacial pain disorder and a differential diagnosis to trigeminal neuralgia. To address the lack of systematic studies in PIFP we here report clinical characteristics and neuroimaging findings in PIFP. Methods...... pain 7 (13%), hypoesthesia 23 (48%), depression 16 (30%) and other chronic pain conditions 17 (32%) and a low prevalence of stabbing pain 21 (40%), touch-evoked pain 14 (26%) and remission periods 10 (19%). The odds ratio between neurovascular contact and the painful side was 1.4 (95% Cl 0.4–4.4, p = 0.......565) and the odds ratio between neurovascular contact with displacement of the trigeminal nerve and the painful side was 0.2 (95% Cl 0.0–2.1, p = 0.195). Conclusion: PIFP is separated from trigeminal neuralgia both with respect to the clinical characteristics and neuroimaging findings, as NVC was not associated...
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.
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
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...
Vermeij, Geerat J; Grosberg, Richard K
2018-01-01
Rarity is a population characteristic that is usually associated with a high risk of extinction. We argue here, however, that chronically rare species (those with low population densities over many generations across their entire ranges) may have individual-level traits that make populations more resistant to extinction. The major obstacle to persistence at low density is successful fertilisation (union between egg and sperm), and chronically rare species are more likely to survive when (1) fertilisation occurs inside or close to an adult, (2) mate choice involves long-distance signals, (3) adults or their surrogate gamete dispersers are highly mobile, or (4) the two sexes are combined in a single individual. In contrast, external fertilisation and wind- or water-driven passive dispersal of gametes, or sluggish or sedentary adult life habits in the absence of gamete vectors, appear to be incompatible with sustained rarity. We suggest that the documented increase in frequency of these traits among marine genera over geological time could explain observed secular decreases in rates of background extinction. Unanswered questions remain about how common chronic rarity actually is, which traits are consistently associated with chronic rarity, and how chronically rare species are distributed among taxa, and among the world's ecosystems and regions. © 2017 John Wiley & Sons Ltd/CNRS.
Foundations of linear and generalized linear models
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,
The persistence of depression score
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.
Persistence, resistance, resonance
Tsadka, Maayan
form of musical consumption and experience. The three pieces draw lines connecting different aspects of persistence, resistance, and resonance.
Ratio-based estimators for a change point in persistence.
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.
Teriparatide Induced Delayed Persistent Hypercalcemia
Directory of Open Access Journals (Sweden)
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.
Persistence in the Cryptocurrency Market
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...
Tuey, R. C.
1972-01-01
Computer solutions of linear programming problems are outlined. Information covers vector spaces, convex sets, and matrix algebra elements for solving simultaneous linear equations. Dual problems, reduced cost analysis, ranges, and error analysis are illustrated.
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.
Classifying Linear Canonical Relations
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.
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.
Persistent spin helices in 2D electron systems
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
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 *
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.
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.
Linear motor coil assembly and linear motor
2009-01-01
An ironless linear motor (5) comprising a magnet track (53) and a coil assembly (50) operating in cooperation with said magnet track (53) and having a plurality of concentrated multi-turn coils (31 a-f, 41 a-d, 51 a-k), wherein the end windings (31E) of the coils (31 a-f, 41 a-e) are substantially
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.
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.
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:...
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
Matrices and linear transformations
Cullen, Charles G
1990-01-01
""Comprehensive . . . an excellent introduction to the subject."" - Electronic Engineer's Design Magazine.This introductory textbook, aimed at sophomore- and junior-level undergraduates in mathematics, engineering, and the physical sciences, offers a smooth, in-depth treatment of linear algebra and matrix theory. The major objects of study are matrices over an arbitrary field. Contents include Matrices and Linear Systems; Vector Spaces; Determinants; Linear Transformations; Similarity: Part I and Part II; Polynomials and Polynomial Matrices; Matrix Analysis; and Numerical Methods. The first
Efficient Non Linear Loudspeakers
DEFF Research Database (Denmark)
Petersen, Bo R.; Agerkvist, Finn T.
2006-01-01
Loudspeakers have traditionally been designed to be as linear as possible. However, as techniques for compensating non linearities are emerging, it becomes possible to use other design criteria. This paper present and examines a new idea for improving the efficiency of loudspeakers at high levels...... by changing the voice coil layout. This deliberate non-linear design has the benefit that a smaller amplifier can be used, which has the benefit of reducing system cost as well as reducing power consumption....
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
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
Fault tolerant linear actuator
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.
Superconducting linear accelerator cryostat
International Nuclear Information System (INIS)
Ben-Zvi, I.; Elkonin, B.V.; Sokolowski, J.S.
1984-01-01
A large vertical cryostat for a superconducting linear accelerator using quarter wave resonators has been developed. The essential technical details, operational experience and performance are described. (author)
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...
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.
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.
DEFF Research Database (Denmark)
Hansen, Kis Boisen
2012-01-01
The note shows an example of an architure for buildin g stand-alone program, where the programming language is object oriented and the databas system is a relational database system. Together with the notes is an example program.......The note shows an example of an architure for buildin g stand-alone program, where the programming language is object oriented and the databas system is a relational database system. Together with the notes is an example program....
Linear colliders - prospects 1985
International Nuclear Information System (INIS)
Rees, J.
1985-06-01
We discuss the scaling laws of linear colliders and their consequences for accelerator design. We then report on the SLAC Linear Collider project and comment on experience gained on that project and its application to future colliders. 9 refs., 2 figs
International Nuclear Information System (INIS)
Richter, B.
1985-01-01
A report is given on the goals and progress of the SLAC Linear Collider. The author discusses the status of the machine and the detectors and give an overview of the physics which can be done at this new facility. He also gives some ideas on how (and why) large linear colliders of the future should be built
International Nuclear Information System (INIS)
Rogner, H.H.
1989-01-01
The submitted sections on linear programming are extracted from 'Theorie und Technik der Planung' (1978) by W. Blaas and P. Henseler and reformulated for presentation at the Workshop. They consider a brief introduction to the theory of linear programming and to some essential aspects of the SIMPLEX solution algorithm for the purposes of economic planning processes. 1 fig
International Nuclear Information System (INIS)
Rowe, C.H.; Wilton, M.S. de.
1979-01-01
An improved recirculating electron beam linear accelerator of the racetrack type is described. The system comprises a beam path of four straight legs with four Pretzel bending magnets at the end of each leg to direct the beam into the next leg of the beam path. At least one of the beam path legs includes a linear accelerator. (UK)
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
Axler, Sheldon
2015-01-01
This best-selling textbook for a second course in linear algebra is aimed at undergrad math majors and graduate students. The novel approach taken here banishes determinants to the end of the book. The text focuses on the central goal of linear algebra: understanding the structure of linear operators on finite-dimensional vector spaces. The author has taken unusual care to motivate concepts and to simplify proofs. A variety of interesting exercises in each chapter helps students understand and manipulate the objects of linear algebra. The third edition contains major improvements and revisions throughout the book. More than 300 new exercises have been added since the previous edition. Many new examples have been added to illustrate the key ideas of linear algebra. New topics covered in the book include product spaces, quotient spaces, and dual spaces. Beautiful new formatting creates pages with an unusually pleasant appearance in both print and electronic versions. No prerequisites are assumed other than the ...
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.
Linear ubiquitination in immunity.
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.
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
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
Schneider, Hans
1989-01-01
Linear algebra is one of the central disciplines in mathematics. A student of pure mathematics must know linear algebra if he is to continue with modern algebra or functional analysis. Much of the mathematics now taught to engineers and physicists requires it.This well-known and highly regarded text makes the subject accessible to undergraduates with little mathematical experience. Written mainly for students in physics, engineering, economics, and other fields outside mathematics, the book gives the theory of matrices and applications to systems of linear equations, as well as many related t
Linearity in Process Languages
DEFF Research Database (Denmark)
Nygaard, Mikkel; Winskel, Glynn
2002-01-01
The meaning and mathematical consequences of linearity (managing without a presumed ability to copy) are studied for a path-based model of processes which is also a model of affine-linear logic. This connection yields an affine-linear language for processes, automatically respecting open......-map bisimulation, in which a range of process operations can be expressed. An operational semantics is provided for the tensor fragment of the language. Different ways to make assemblies of processes lead to different choices of exponential, some of which respect bisimulation....
Amir-Moez, A R; Sneddon, I N
1962-01-01
Elements of Linear Space is a detailed treatment of the elements of linear spaces, including real spaces with no more than three dimensions and complex n-dimensional spaces. The geometry of conic sections and quadric surfaces is considered, along with algebraic structures, especially vector spaces and transformations. Problems drawn from various branches of geometry are given.Comprised of 12 chapters, this volume begins with an introduction to real Euclidean space, followed by a discussion on linear transformations and matrices. The addition and multiplication of transformations and matrices a
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
Is Farm Management Skill Persistent?
Li, Xin; Paulson, Nicholas
2014-01-01
Farm management skills can affect farm managers' performance. In this article, farm management performance is analyzed based on yearly Illinois Farm Business Farm Management (FBFM) panel data across 6,760 farms from 1996 through 2011. Two out-of-sample measures of skill are used to analyze the ability of farm managers that consistently perform well over yearly and longer time horizons. Persistence tests show management skills are consistent and predictable. Results also suggest that the most ...
Persistent Authentication in Smart Environments
DEFF Research Database (Denmark)
Hansen, Mads Syska; Kirschmeyer, Martin; Jensen, Christian D.
2008-01-01
present a proof-of-concept implementation of the proposed mechanism, which employs camera based tracking with a single stationary 3D camera that uses the "time of flight" principle. A preliminary evaluation of the proposed mechanism indicates that persistent authentication is technically possible...... with the proposed hardware. The proposed model is sufficiently general to allow the addition of more cameras or supplemental tracking technologies, which will improve the robustness and scalability of the proposed mechanism....
Long memory and changing persistence
DEFF Research Database (Denmark)
Kruse, Robinson; Sibbertsen, Philipp
We study the empirical behaviour of semi-parametric log-periodogram estimation for long memory models when the true process exhibits a change in persistence. Simulation results confirm theoretical arguments which suggest that evidence for long memory is likely to be found. A recently proposed test...... by Sibbertsen and Kruse (2009) is shown to exhibit noticeable power to discriminate between long memory and a structural change in autoregressive parameters....
How persistent is civilization growth?
Garrett, Timothy J.
2011-01-01
In a recent study (Garrett, 2011), I described theoretical arguments and empirical evidence showing how civilization evolution might be considered from a purely physical basis. One implication is that civilization exhibits the property of persistence in its growth. Here, this argument is elaborated further, and specific near-term forecasts are provided for key economic variables and anthropogenic CO2 emission rates at global scales. Absent some external shock, civilization wealth, energy cons...
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.
Callier, Frank M.; Desoer, Charles A.
1991-01-01
The aim of this book is to provide a systematic and rigorous access to the main topics of linear state-space system theory in both the continuous-time case and the discrete-time case; and the I/O description of linear systems. The main thrusts of the work are the analysis of system descriptions and derivations of their properties, LQ-optimal control, state feedback and state estimation, and MIMO unity-feedback systems.
Model-Checking of Linear-Time Properties in Multi-Valued Systems
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...
MOOCs and Persistence: Definitions and Predictors
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.
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...
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...
Distributed Persistent Identifiers System Design
Directory of Open Access Journals (Sweden)
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
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...
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.
International Nuclear Information System (INIS)
Mamyrin, B.A.; Shmikk, D.V.
1979-01-01
A description and operating principle of a linear mass reflectron with V-form trajectory of ion motion -a new non-magnetic time-of-flight mass spectrometer with high resolution are presented. The ion-optical system of the device consists of an ion source with ionization by electron shock, of accelerating gaps, reflector gaps, a drift space and ion detector. Ions move in the linear mass refraction along the trajectories parallel to the axis of the analyzer chamber. The results of investigations into the experimental device are given. With an ion drift length of 0.6 m the device resolution is 1200 with respect to the peak width at half-height. Small-sized mass spectrometric transducers with high resolution and sensitivity may be designed on the base of the linear mass reflectron principle
Olver, Peter J
2018-01-01
This textbook develops the essential tools of linear algebra, with the goal of imparting technique alongside contextual understanding. Applications go hand-in-hand with theory, each reinforcing and explaining the other. This approach encourages students to develop not only the technical proficiency needed to go on to further study, but an appreciation for when, why, and how the tools of linear algebra can be used across modern applied mathematics. Providing an extensive treatment of essential topics such as Gaussian elimination, inner products and norms, and eigenvalues and singular values, this text can be used for an in-depth first course, or an application-driven second course in linear algebra. In this second edition, applications have been updated and expanded to include numerical methods, dynamical systems, data analysis, and signal processing, while the pedagogical flow of the core material has been improved. Throughout, the text emphasizes the conceptual connections between each application and the un...
Banach, S
1987-01-01
This classic work by the late Stefan Banach has been translated into English so as to reach a yet wider audience. It contains the basics of the algebra of operators, concentrating on the study of linear operators, which corresponds to that of the linear forms a1x1 + a2x2 + ... + anxn of algebra.The book gathers results concerning linear operators defined in general spaces of a certain kind, principally in Banach spaces, examples of which are: the space of continuous functions, that of the pth-power-summable functions, Hilbert space, etc. The general theorems are interpreted in various mathematical areas, such as group theory, differential equations, integral equations, equations with infinitely many unknowns, functions of a real variable, summation methods and orthogonal series.A new fifty-page section (``Some Aspects of the Present Theory of Banach Spaces'''') complements this important monograph.
DEFF Research Database (Denmark)
Høskuldsson, Agnar
1996-01-01
Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four of these cri......Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four...... the basic problems in determining the dimension of linear models. Then each of the eight measures are treated. The results are illustrated by examples....
Linear programming using Matlab
Ploskas, Nikolaos
2017-01-01
This book offers a theoretical and computational presentation of a variety of linear programming algorithms and methods with an emphasis on the revised simplex method and its components. A theoretical background and mathematical formulation is included for each algorithm as well as comprehensive numerical examples and corresponding MATLAB® code. The MATLAB® implementations presented in this book are sophisticated and allow users to find solutions to large-scale benchmark linear programs. Each algorithm is followed by a computational study on benchmark problems that analyze the computational behavior of the presented algorithms. As a solid companion to existing algorithmic-specific literature, this book will be useful to researchers, scientists, mathematical programmers, and students with a basic knowledge of linear algebra and calculus. The clear presentation enables the reader to understand and utilize all components of simplex-type methods, such as presolve techniques, scaling techniques, pivoting ru...
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
Linearly Adjustable International Portfolios
Fonseca, R. J.; Kuhn, D.; Rustem, B.
2010-09-01
We present an approach to multi-stage international portfolio optimization based on the imposition of a linear structure on the recourse decisions. Multiperiod decision problems are traditionally formulated as stochastic programs. Scenario tree based solutions however can become intractable as the number of stages increases. By restricting the space of decision policies to linear rules, we obtain a conservative tractable approximation to the original problem. Local asset prices and foreign exchange rates are modelled separately, which allows for a direct measure of their impact on the final portfolio value.
Linearly Adjustable International Portfolios
International Nuclear Information System (INIS)
Fonseca, R. J.; Kuhn, D.; Rustem, B.
2010-01-01
We present an approach to multi-stage international portfolio optimization based on the imposition of a linear structure on the recourse decisions. Multiperiod decision problems are traditionally formulated as stochastic programs. Scenario tree based solutions however can become intractable as the number of stages increases. By restricting the space of decision policies to linear rules, we obtain a conservative tractable approximation to the original problem. Local asset prices and foreign exchange rates are modelled separately, which allows for a direct measure of their impact on the final portfolio value.
International Nuclear Information System (INIS)
Barkman, W.E.; Adams, W.Q.; Berrier, B.R.
1978-01-01
A linear induction motor has been operated on a test bed with a feedback pulse resolution of 5 nm (0.2 μin). Slewing tests with this slide drive have shown positioning errors less than or equal to 33 nm (1.3 μin) at feedrates between 0 and 25.4 mm/min (0-1 ipm). A 0.86-m (34-in)-stroke linear motor is being investigated, using the SPACO machine as a test bed. Initial results were encouraging, and work is continuing to optimize the servosystem compensation
Hogben, Leslie
2013-01-01
With a substantial amount of new material, the Handbook of Linear Algebra, Second Edition provides comprehensive coverage of linear algebra concepts, applications, and computational software packages in an easy-to-use format. It guides you from the very elementary aspects of the subject to the frontiers of current research. Along with revisions and updates throughout, the second edition of this bestseller includes 20 new chapters.New to the Second EditionSeparate chapters on Schur complements, additional types of canonical forms, tensors, matrix polynomials, matrix equations, special types of
Linear Algebra Thoroughly Explained
Vujičić, Milan
2008-01-01
Linear Algebra Thoroughly Explained provides a comprehensive introduction to the subject suitable for adoption as a self-contained text for courses at undergraduate and postgraduate level. The clear and comprehensive presentation of the basic theory is illustrated throughout with an abundance of worked examples. The book is written for teachers and students of linear algebra at all levels and across mathematics and the applied sciences, particularly physics and engineering. It will also be an invaluable addition to research libraries as a comprehensive resource book for the subject.
New-found fundamentals of bacterial persistence.
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.
2013-05-10
AND VICTIM- ~ vAP BLAMING 4. AMERICA, LINEARLY CYCUCAL AF IMT 1768, 19840901, V5 PREVIOUS EDITION WILL BE USED. C2C Jessica Adams Dr. Brissett...his desires, his failings, and his aspirations follow the same general trend throughout history and throughout cultures. The founding fathers sought
International Nuclear Information System (INIS)
Southworth, B.
1985-01-01
The peak of the construction phase of the Stanford Linear Collider, SLC, to achieve 50 GeV electron-positron collisions has now been passed. The work remains on schedule to attempt colliding beams, initially at comparatively low luminosity, early in 1987. (orig./HSI).
International Nuclear Information System (INIS)
Mafra Neto, F.
1992-01-01
The dose of gamma radiation from a linear source of cesium 137 is obtained, presenting two difficulties: oblique filtration of radiation when cross the platinum wall, in different directions, and dose connection due to the scattering by the material mean of propagation. (C.G.C.)
Resistors Improve Ramp Linearity
Kleinberg, L. L.
1982-01-01
Simple modification to bootstrap ramp generator gives more linear output over longer sweep times. New circuit adds just two resistors, one of which is adjustable. Modification cancels nonlinearities due to variations in load on charging capacitor and due to changes in charging current as the voltage across capacitor increases.
LINEAR COLLIDERS: 1992 workshop
International Nuclear Information System (INIS)
Settles, Ron; Coignet, Guy
1992-01-01
As work on designs for future electron-positron linear colliders pushes ahead at major Laboratories throughout the world in a major international collaboration framework, the LC92 workshop held in Garmisch Partenkirchen this summer, attended by 200 machine and particle physicists, provided a timely focus
Brameier, Markus
2007-01-01
Presents a variant of Genetic Programming that evolves imperative computer programs as linear sequences of instructions, in contrast to the more traditional functional expressions or syntax trees. This book serves as a reference for researchers, but also contains sufficient introduction for students and those who are new to the field
Dobbs, David E.
2013-01-01
A direct method is given for solving first-order linear recurrences with constant coefficients. The limiting value of that solution is studied as "n to infinity." This classroom note could serve as enrichment material for the typical introductory course on discrete mathematics that follows a calculus course.
International Nuclear Information System (INIS)
Takeda, Seishi
1992-01-01
The status of R and D of future e + e - linear colliders proposed by the institutions throughout the world is described including the JLC, NLC, VLEPP, CLIC, DESY/THD and TESLA projects. The parameters and RF sources are discussed. (G.P.) 36 refs.; 1 tab
Persistent cough in an adolescent.
Stein, M T; Harper, G; Chen, J
1999-12-01
Jessica, a 14-year-old girl with a history of asthma, went to her pediatrician's office because of a persistent cough. She had been coughing for at least 3 months with occasional cough-free periods of less than a few days. The cough was nonproductive and was not accompanied by fever, rhinorrhea, or facial or chest pain. Jessica and her mother observed that the cough increased with exercise and typically was not present during sleep. She has used two metered-dose inhalers--albuterol and cromolyn--without any change in the cough pattern. For the past 5 years, Jessica has had mild asthma responsive to albuterol. She enjoys running on the cross-country team, soccer, and dancing. She is an average student and denies any change in academic performance. She has never been hospitalized or had an emergency department visit for asthma or pneumonia. There has been no recent travel or exposure to a person with a chronic productive cough, tobacco smoke, or a live-in pet. Jessica lives with her mother and younger sister in a 10-year-old, carpeted apartment without any evidence of mold or recent renovation. In the process of taking the history, the pediatrician noticed that Jessica coughed intermittently, with two or three coughs during each episode. At times, the cough was harsh; at other times, it was a quiet cough, as if she were clearing her throat. She was cooperative, without overt anxiety or respiratory distress. After a complete physical examination with normal findings, the pediatrician interviewed Jessica and her mother alone. Jessica's parents had been divorced for the past 6 years. She lived with her mother but visited her father, and his new family with two young children, every weekend. She spoke about this arrangement comfortably and said that she loved her father and mother but didn't like the tension she experienced at her father's home. "I don't like adults arguing when kids are around." When asked why she thought the cough persisted so long, she commented in a
Persistent homology and string vacua
Energy Technology Data Exchange (ETDEWEB)
Cirafici, Michele [Center for Mathematical Analysis, Geometry and Dynamical Systems,Instituto Superior Técnico, Universidade de Lisboa,Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Institut des Hautes Études Scientifiques,Le Bois-Marie, 35 route de Chartres, F-91440 Bures-sur-Yvette (France)
2016-03-08
We use methods from topological data analysis to study the topological features of certain distributions of string vacua. Topological data analysis is a multi-scale approach used to analyze the topological features of a dataset by identifying which homological characteristics persist over a long range of scales. We apply these techniques in several contexts. We analyze N=2 vacua by focusing on certain distributions of Calabi-Yau varieties and Landau-Ginzburg models. We then turn to flux compactifications and discuss how we can use topological data analysis to extract physical information. Finally we apply these techniques to certain phenomenologically realistic heterotic models. We discuss the possibility of characterizing string vacua using the topological properties of their distributions.
Coping with persistent environmental problems
DEFF Research Database (Denmark)
Varjopuro, Riku; Andrulewicz, Eugeniusz; Brandt, Urs Steiner
2014-01-01
to a decision to taking action and several years further for actual implementation. Ecosystem responses to measures illustrate that feedback can keep the ecosystem in a certain state and cause a delay in ecosystem response. These delays can operate on decadal scales. Our aim in this paper...... involved in the implementation are keys to improve understanding of the systemic delays. The improved understanding is necessary for the adaptive management of a persistent environmental problem. In addition to the state of the environment, the monitoring and analysis should be targeted also......; (2) implementation delay: the time from the launch of a policy to the actual implementation; (3) ecosystem delay: the time difference between the implementation and an actual measurable effects. A policy process is one characterized by delays. It may take years from problem identification...
Bilateral persistent hyperplastic primary vitreous
Directory of Open Access Journals (Sweden)
Jain Tarun
2009-01-01
Full Text Available A case of bilateral persistent hyperplastic primary vitreous (PHPV in a 3-month-old male infant, who had bilateral leukokoria, is presented. The child was referred for imaging with a clinical suspicion of retinoblastoma. Gray-scale ultrasound evaluation revealed an echogenic band in the posterior segment of both globes, extending from the posterior surface of the lens capsule to the optic disc. Doppler examination revealed the presence of arterial flow in the band in both globes. Associated echogenic hemorrhage was also seen, which was confirmed by computed tomography. Most cases of PHPV are sporadic and unilateral, and bilateral PHPV is rare. The imaging features in this case suggest the diagnosis of bilateral PHPV and differentiate it from retinoblastoma. This entity, although infrequent, should be considered in the differential diagnosis while evaluating bilateral leukokoria.
Persistence of antimuscarinic drug use
DEFF Research Database (Denmark)
Brostrøm, Søren; Hallas, Jesper
2009-01-01
PURPOSE: Evidence suggests antimuscarinic drugs for the overactive-bladder syndrome only confer modest improvements in quality of life. We wanted to describe the persistence of therapy, including an extended analysis beyond the 1-year follow-up employed in other studies. METHODS: All prescriptions...... for drugs in ATC category G04BD were retrieved for the period 1999-2006 from a regional database with complete capture of all reimbursed prescriptions. Kaplan-Meyer curves were generated for duration of treatment for each substance and analyzed for determinants of termination. RESULTS: With the exception...... of trospium chloride, all drugs had continuation rates of less than 50% at 6 months, less than 25% at 1 year, and less than 10% at 2 years and longer. Trospium chloride, however, exhibited continuation rates of 46% at 6 months, 36% at 1 year, 22% at 2 years, and 16% at 3 years. CONCLUSIONS: In a setting...
Dematerialization: Variety, caution, and persistence.
Ausubel, Jesse H; Waggoner, Paul E
2008-09-02
Dematerialization, represented by declining consumption per GDP of energy or of goods, offers some hope for rising environmental quality with development. The declining proportion of income spent on staples as affluence grows, which income elasticity <1.0 measures, makes dematerialization widespread. Further, as learning improves efficiency of resource use, the intensity of environmental impact per production of staples often declines. We observe that combinations of low income elasticity for staples and of learning by producers cause a variety of dematerializations and declining intensities of impact, from energy use and carbon emission to food consumption and fertilizer use, globally and in countries ranging from the United States and France to China, India, Brazil, and Indonesia. Because dematerialization and intensity of impact are ratios of parameters that may be variously defined and are sometimes difficult to estimate, their fluctuations must be interpreted cautiously. Nevertheless, substantial declining intensity of impact, and especially, dematerialization persisted between 1980 and 2006.
Finite-dimensional linear algebra
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
Persisting roughness when deposition stops.
Schwartz, Moshe; Edwards, S F
2004-12-01
Useful theories for growth of surfaces under random deposition of material have been developed by several authors. The simplest theory is that introduced by Edwards and Wilkinson (EW), which is linear and soluble. Its nonlinear generalization by Kardar, Parisi, and Zhang (KPZ) resulted in many subsequent studies. Yet both EW and KPZ theories contain an unphysical feature. When deposition of material is stopped, both theories predict that as time tends to infinity, the surface becomes flat. In fact, of course, the final surface is not flat, but simply has no gradients larger than the gradient related to the angle of repose. We modify the EW and KPZ theories to accommodate this feature and study the consequences for the simpler system which is a modification of the EW equation. In spite of the fact that the equation describing the evolution of the surface is not linear, we find that the steady state in the presence of noise is not very different in the long-wavelength limit from that of the linear EW equation. The situation is quite different from that of EW when deposition stops. Initially there is still some rearrangement of the surface, but that stops as everywhere on the surface the gradient is less than that related to the angle of repose. The most interesting feature observed after deposition stops is the emergence of history-dependent steady-state distributions.
Long-term persistence of oral human papillomavirus type 16: the HPV Infection in Men (HIM) study.
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.
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 ...
Kuznetsov, N.; Maz'ya, V.; Vainberg, B.
2002-08-01
This book gives a self-contained and up-to-date account of mathematical results in the linear theory of water waves. The study of waves has many applications, including the prediction of behavior of floating bodies (ships, submarines, tension-leg platforms etc.), the calculation of wave-making resistance in naval architecture, and the description of wave patterns over bottom topography in geophysical hydrodynamics. The first section deals with time-harmonic waves. Three linear boundary value problems serve as the approximate mathematical models for these types of water waves. The next section uses a plethora of mathematical techniques in the investigation of these three problems. The techniques used in the book include integral equations based on Green's functions, various inequalities between the kinetic and potential energy and integral identities which are indispensable for proving the uniqueness theorems. The so-called inverse procedure is applied to constructing examples of non-uniqueness, usually referred to as 'trapped nodes.'
The International Linear Collider
Directory of Open Access Journals (Sweden)
List Benno
2014-04-01
Full Text Available The International Linear Collider (ILC is a proposed e+e− linear collider with a centre-of-mass energy of 200–500 GeV, based on superconducting RF cavities. The ILC would be an ideal machine for precision studies of a light Higgs boson and the top quark, and would have a discovery potential for new particles that is complementary to that of LHC. The clean experimental conditions would allow the operation of detectors with extremely good performance; two such detectors, ILD and SiD, are currently being designed. Both make use of novel concepts for tracking and calorimetry. The Japanese High Energy Physics community has recently recommended to build the ILC in Japan.
The International Linear Collider
List, Benno
2014-04-01
The International Linear Collider (ILC) is a proposed e+e- linear collider with a centre-of-mass energy of 200-500 GeV, based on superconducting RF cavities. The ILC would be an ideal machine for precision studies of a light Higgs boson and the top quark, and would have a discovery potential for new particles that is complementary to that of LHC. The clean experimental conditions would allow the operation of detectors with extremely good performance; two such detectors, ILD and SiD, are currently being designed. Both make use of novel concepts for tracking and calorimetry. The Japanese High Energy Physics community has recently recommended to build the ILC in Japan.
DEFF Research Database (Denmark)
Høskuldsson, Agnar
1996-01-01
Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four...... the basic problems in determining the dimension of linear models. Then each of the eight measures are treated. The results are illustrated by examples....... of these criteria are widely used ones, while the remaining four are ones derived from the H-principle of mathematical modeling. Many examples from practice show that the criteria derived from the H-principle function better than the known and popular criteria for the number of components. We shall briefly review...
Goldowsky, Michael P. (Inventor)
1987-01-01
A reciprocating linear motor is formed with a pair of ring-shaped permanent magnets having opposite radial polarizations, held axially apart by a nonmagnetic yoke, which serves as an axially displaceable armature assembly. A pair of annularly wound coils having axial lengths which differ from the axial lengths of the permanent magnets are serially coupled together in mutual opposition and positioned with an outer cylindrical core in axial symmetry about the armature assembly. One embodiment includes a second pair of annularly wound coils serially coupled together in mutual opposition and an inner cylindrical core positioned in axial symmetry inside the armature radially opposite to the first pair of coils. Application of a potential difference across a serial connection of the two pairs of coils creates a current flow perpendicular to the magnetic field created by the armature magnets, thereby causing limited linear displacement of the magnets relative to the coils.
International Nuclear Information System (INIS)
Henneaux, Marc; Teitelboim, Claudio
2005-01-01
We show that duality transformations of linearized gravity in four dimensions, i.e., rotations of the linearized Riemann tensor and its dual into each other, can be extended to the dynamical fields of the theory so as to be symmetries of the action and not just symmetries of the equations of motion. Our approach relies on the introduction of two superpotentials, one for the spatial components of the spin-2 field and the other for their canonically conjugate momenta. These superpotentials are two-index, symmetric tensors. They can be taken to be the basic dynamical fields and appear locally in the action. They are simply rotated into each other under duality. In terms of the superpotentials, the canonical generator of duality rotations is found to have a Chern-Simons-like structure, as in the Maxwell case
International Nuclear Information System (INIS)
Phinney, N.
1992-01-01
The SLAC Linear Collider has begun a new era of operation with the SLD detector. During 1991 there was a first engineering run for the SLD in parallel with machine improvements to increase luminosity and reliability. For the 1992 run, a polarized electron source was added and more than 10,000 Zs with an average of 23% polarization have been logged by the SLD. This paper discusses the performance of the SLC in 1991 and 1992 and the technical advances that have produced higher luminosity. Emphasis will be placed on issues relevant to future linear colliders such as producing and maintaining high current, low emittance beams and focusing the beams to the micron scale for collisions. (Author) tab., 2 figs., 18 refs
Linear waves and instabilities
International Nuclear Information System (INIS)
Bers, A.
1975-01-01
The electrodynamic equations for small-amplitude waves and their dispersion relation in a homogeneous plasma are outlined. For such waves, energy and momentum, and their flow and transformation, are described. Perturbation theory of waves is treated and applied to linear coupling of waves, and the resulting instabilities from such interactions between active and passive waves. Linear stability analysis in time and space is described where the time-asymptotic, time-space Green's function for an arbitrary dispersion relation is developed. The perturbation theory of waves is applied to nonlinear coupling, with particular emphasis on pump-driven interactions of waves. Details of the time--space evolution of instabilities due to coupling are given. (U.S.)
Extended linear chain compounds
Linear chain substances span a large cross section of contemporary chemistry ranging from covalent polymers, to organic charge transfer com plexes to nonstoichiometric transition metal coordination complexes. Their commonality, which coalesced intense interest in the theoretical and exper imental solid state physics/chemistry communities, was based on the obser vation that these inorganic and organic polymeric substrates exhibit striking metal-like electrical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous aniso tropic electrical, optical, magnetic, and mechanical properties, the conver gence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallog...
Diamond, Jared M.
1966-01-01
1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall-bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes. 2. As in many other tissues, water flow was found to vary with gradient in a markedly non-linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow. 3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186-825 m-osM. 4. The resistance to water flow was the same when the gall-bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities. 5. Of the theories advanced to explain non-linear osmosis in other tissues, flow-induced membrane deformations, unstirred layers, asymmetrical series-membrane effects, and non-osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non-linear osmosis in rabbit gall-bladder is due to a decrease in water permeability with increasing osmolarity. 6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered. PMID:5945254
Fundamentals of linear algebra
Dash, Rajani Ballav
2008-01-01
FUNDAMENTALS OF LINEAR ALGEBRA is a comprehensive Text Book, which can be used by students and teachers of All Indian Universities. The Text has easy, understandable form and covers all topics of UGC Curriculum. There are lots of worked out examples which helps the students in solving the problems without anybody's help. The Problem sets have been designed keeping in view of the questions asked in different examinations.
Sander, K F
1964-01-01
Linear Network Theory covers the significant algebraic aspect of network theory, with minimal reference to practical circuits. The book begins the presentation of network analysis with the exposition of networks containing resistances only, and follows it up with a discussion of networks involving inductance and capacity by way of the differential equations. Classification and description of certain networks, equivalent networks, filter circuits, and network functions are also covered. Electrical engineers, technicians, electronics engineers, electricians, and students learning the intricacies
Non linear viscoelastic models
DEFF Research Database (Denmark)
Agerkvist, Finn T.
2011-01-01
Viscoelastic eects are often present in loudspeaker suspensions, this can be seen in the displacement transfer function which often shows a frequency dependent value below the resonance frequency. In this paper nonlinear versions of the standard linear solid model (SLS) are investigated....... The simulations show that the nonlinear version of the Maxwell SLS model can result in a time dependent small signal stiness while the Kelvin Voight version does not....
Relativistic Linear Restoring Force
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
Superconducting linear colliders
International Nuclear Information System (INIS)
Anon.
1990-01-01
The advantages of superconducting radiofrequency (SRF) for particle accelerators have been demonstrated by successful operation of systems in the TRISTAN and LEP electron-positron collider rings respectively at the Japanese KEK Laboratory and at CERN. If performance continues to improve and costs can be lowered, this would open an attractive option for a high luminosity TeV (1000 GeV) linear collider
Perturbed asymptotically linear problems
Bartolo, R.; Candela, A. M.; Salvatore, A.
2012-01-01
The aim of this paper is investigating the existence of solutions of some semilinear elliptic problems on open bounded domains when the nonlinearity is subcritical and asymptotically linear at infinity and there is a perturbation term which is just continuous. Also in the case when the problem has not a variational structure, suitable procedures and estimates allow us to prove that the number of distinct crtitical levels of the functional associated to the unperturbed problem is "stable" unde...
Miniature linear cooler development
International Nuclear Information System (INIS)
Pruitt, G.R.
1993-01-01
An overview is presented of the status of a family of miniature linear coolers currently under development by Hughes Aircraft Co. for use in hand held, volume limited or power limited infrared applications. These coolers, representing the latest additions to the Hughes family of TOP trademark [twin-opposed piston] linear coolers, have been fabricated and tested in three different configurations. Each configuration is designed to utilize a common compressor assembly resulting in reduced manufacturing costs. The baseline compressor has been integrated with two different expander configurations and has been operated with two different levels of input power. These various configuration combinations offer a wide range of performance and interface characteristics which may be tailored to applications requiring limited power and size without significantly compromising cooler capacity or cooldown characteristics. Key cooler characteristics and test data are summarized for three combinations of cooler configurations which are representative of the versatility of this linear cooler design. Configurations reviewed include the shortened coldfinger [1.50 to 1.75 inches long], limited input power [less than 17 Watts] for low power availability applications; the shortened coldfinger with higher input power for lightweight, higher performance applications; and coldfingers compatible with DoD 0.4 Watt Common Module coolers for wider range retrofit capability. Typical weight of these miniature linear coolers is less than 500 grams for the compressor, expander and interconnecting transfer line. Cooling capacity at 80K at room ambient conditions ranges from 400 mW to greater than 550 mW. Steady state power requirements for maintaining a heat load of 150 mW at 80K has been shown to be less than 8 Watts. Ongoing reliability growth testing is summarized including a review of the latest test article results
Directory of Open Access Journals (Sweden)
Avram Mihai
2017-01-01
Full Text Available The paper presents a linear pneumatic actuator with short working stroke. It consists of a pneumatic motor (a simple stroke cylinder or a membrane chamber, two 2/2 pneumatic distributors “all or nothing” electrically commanded for controlling the intake/outtake flow to/from the active chamber of the motor, a position transducer and a microcontroller. There is also presented the theoretical analysis (mathematical modelling and numerical simulation accomplished.
Avram Mihai; Niţu Constantin; Bucşan Constantin; Grămescu Bogdan
2017-01-01
The paper presents a linear pneumatic actuator with short working stroke. It consists of a pneumatic motor (a simple stroke cylinder or a membrane chamber), two 2/2 pneumatic distributors “all or nothing” electrically commanded for controlling the intake/outtake flow to/from the active chamber of the motor, a position transducer and a microcontroller. There is also presented the theoretical analysis (mathematical modelling and numerical simulation) accomplished.
International Nuclear Information System (INIS)
Scheffel, J.
1984-03-01
The linear Grad-Shafranov equation for a toroidal, axisymmetric plasma is solved analytically. Exact solutions are given in terms of confluent hyper-geometric functions. As an alternative, simple and accurate WKBJ solutions are presented. With parabolic pressure profiles, both hollow and peaked toroidal current density profiles are obtained. As an example the equilibrium of a z-pinch with a square-shaped cross section is derived.(author)
Buttram, M.T.; Ginn, J.W.
1988-06-21
A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.
Springer, T A
1998-01-01
"[The first] ten chapters...are an efficient, accessible, and self-contained introduction to affine algebraic groups over an algebraically closed field. The author includes exercises and the book is certainly usable by graduate students as a text or for self-study...the author [has a] student-friendly style… [The following] seven chapters... would also be a good introduction to rationality issues for algebraic groups. A number of results from the literature…appear for the first time in a text." –Mathematical Reviews (Review of the Second Edition) "This book is a completely new version of the first edition. The aim of the old book was to present the theory of linear algebraic groups over an algebraically closed field. Reading that book, many people entered the research field of linear algebraic groups. The present book has a wider scope. Its aim is to treat the theory of linear algebraic groups over arbitrary fields. Again, the author keeps the treatment of prerequisites self-contained. The material of t...
Parametric Linear Dynamic Logic
Directory of Open Access Journals (Sweden)
Peter Faymonville
2014-08-01
Full Text Available We introduce Parametric Linear Dynamic Logic (PLDL, which extends Linear Dynamic Logic (LDL by temporal operators equipped with parameters that bound their scope. LDL was proposed as an extension of Linear Temporal Logic (LTL that is able to express all ω-regular specifications while still maintaining many of LTL's desirable properties like an intuitive syntax and a translation into non-deterministic Büchi automata of exponential size. But LDL lacks capabilities to express timing constraints. By adding parameterized operators to LDL, we obtain a logic that is able to express all ω-regular properties and that subsumes parameterized extensions of LTL like Parametric LTL and PROMPT-LTL. Our main technical contribution is a translation of PLDL formulas into non-deterministic Büchi word automata of exponential size via alternating automata. This yields a PSPACE model checking algorithm and a realizability algorithm with doubly-exponential running time. Furthermore, we give tight upper and lower bounds on optimal parameter values for both problems. These results show that PLDL model checking and realizability are not harder than LTL model checking and realizability.
Quantum linear Boltzmann equation
International Nuclear Information System (INIS)
Vacchini, Bassano; Hornberger, Klaus
2009-01-01
We review the quantum version of the linear Boltzmann equation, which describes in a non-perturbative fashion, by means of scattering theory, how the quantum motion of a single test particle is affected by collisions with an ideal background gas. A heuristic derivation of this Lindblad master equation is presented, based on the requirement of translation-covariance and on the relation to the classical linear Boltzmann equation. After analyzing its general symmetry properties and the associated relaxation dynamics, we discuss a quantum Monte Carlo method for its numerical solution. We then review important limiting forms of the quantum linear Boltzmann equation, such as the case of quantum Brownian motion and pure collisional decoherence, as well as the application to matter wave optics. Finally, we point to the incorporation of quantum degeneracies and self-interactions in the gas by relating the equation to the dynamic structure factor of the ambient medium, and we provide an extension of the equation to include internal degrees of freedom.
International Nuclear Information System (INIS)
Emma, P.
1995-01-01
The Stanford Linear Collider (SLC) is the first and only high-energy e + e - linear collider in the world. Its most remarkable features are high intensity, submicron sized, polarized (e - ) beams at a single interaction point. The main challenges posed by these unique characteristics include machine-wide emittance preservation, consistent high intensity operation, polarized electron production and transport, and the achievement of a high degree of beam stability on all time scales. In addition to serving as an important machine for the study of Z 0 boson production and decay using polarized beams, the SLC is also an indispensable source of hands-on experience for future linear colliders. Each new year of operation has been highlighted with a marked improvement in performance. The most significant improvements for the 1994-95 run include new low impedance vacuum chambers for the damping rings, an upgrade to the optics and diagnostics of the final focus systems, and a higher degree of polarization from the electron source. As a result, the average luminosity has nearly doubled over the previous year with peaks approaching 10 30 cm -2 s -1 and an 80% electron polarization at the interaction point. These developments as well as the remaining identifiable performance limitations will be discussed
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)
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
Drought Persistence Errors in Global Climate Models
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.
Translating Romans: some persistent headaches
Directory of Open Access Journals (Sweden)
A.B. du Toit
2010-07-01
Full Text Available Translating Romans: some persistent headaches Gone are the days when it was axiomatic that expertise in biblical languages automatically qualified one as a Bible translator. In 1949, Ronald Knox, who for nine years conscientiously struggled with translating the Bible for his generation, published a booklet under the title The trials of a translator. At that stage Bible translation as the subject of scientific study was still in its infancy. Since then, research into the intricacies of communicating the biblical message in an authentic but understandable manner, has made significant progress (cf. Roberts, 2009. However, the frustrations of Bible translators, first of all to really understand what the biblical authors wanted to convey to their original addressees, and then to commu-nicate that message to their own targeted readers in a meaningful way, have not disappeared. In fact, the challenge to meet the vary-ing requirements of the multiple kinds of translation that are present-ly in vogue, has only increased.
Energy savings: persuasion and persistence
Energy Technology Data Exchange (ETDEWEB)
Eijadi, David; McDougall, Tom; Leaf, Kris; Douglas, Jim; Steinbock, Jason; Reimer, Paul [The Weidt Group, Minnetonka, MN (United States); Gauthier, Julia [Xcel Energy, Minneapolis, MN (United States); Wild, Doug; Richards McDaniel, Stephanie [BWBR Architects, Inc., Saint Paul, MN (United States)
2005-07-01
In this study, the architects, sponsoring utility and energy simulation specialist joined together to investigate the persistence of energy savings in three completed projects: a college library; a municipal transportation facility; and a hospital. The primary question being 'How well did the design decisions made with the help of simulation analysis translate into building operations over several years?' Design simulation and metered performance data are compared for specific energy-saving strategies. The paper provides a brief overview of the basis of selection of the three projects, the energy design assistance methods employed and the decisions made, along with their savings expectations. For each case, design characteristics, modelling assumptions, selected strategies and actual metered performance are outlined. We find evidence of appropriate levels of energy conservation, but they are not the absolute values predicted. In each case, the discrepancies between modelling assumptions and final construction or operating procedures are identified, examined and rectified. The paper illustrates that while owners are saving energy, they are not always getting the full savings potential for what they install. The paper concludes with a re-examination of the overall process. It evaluates the potential for additional savings of individual technologies and related larger utility incentives to design teams and building owners.
Inflation Persistence under Semi-Fixed Exchange Rate Regimes:The European Evidence 1974-1998
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
Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes
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.
International Nuclear Information System (INIS)
Garbet, X.; Mourgues, F.; Samain, A.
1987-01-01
Among the various instabilities which could explain the anomalous electron heat transport observed in tokamaks during additional heating, a microtearing turbulence is a reasonable candidate since it affects directly the magnetic topology. This turbulence may be described in a proper frame rotating around the majors axis by a static potential vector. In strong non linear regimes, the flow of electrons along the stochastic field lines induces a current. The point is to know whether this current can sustain the turbulence. The mechanisms of this self-consistency, involving the combined effects of the thermal diamagnetism and of the electric drift are presented here
Wangler, Thomas P
2008-01-01
Thomas P. Wangler received his B.S. degree in physics from Michigan State University, and his Ph.D. degree in physics and astronomy from the University of Wisconsin. After postdoctoral appointments at the University of Wisconsin and Brookhaven National Laboratory, he joined the staff of Argonne National Laboratory in 1966, working in the fields of experimental high-energy physics and accelerator physics. He joined the Accelerator Technology Division at Los Alamos National Laboratory in 1979, where he specialized in high-current beam physics and linear accelerator design and technology. In 2007
International Nuclear Information System (INIS)
Richter, B.; Bell, R.A.; Brown, K.L.
1980-06-01
The SLAC LINEAR COLLIDER is designed to achieve an energy of 100 GeV in the electron-positron center-of-mass system by accelerating intense bunches of particles in the SLAC linac and transporting the electron and positron bunches in a special magnet system to a point where they are focused to a radius of about 2 microns and made to collide head on. The rationale for this new type of colliding beam system is discussed, the project is described, some of the novel accelerator physics issues involved are discussed, and some of the critical technical components are described
Lopez, Cesar
2014-01-01
MATLAB is a high-level language and environment for numerical computation, visualization, and programming. Using MATLAB, you can analyze data, develop algorithms, and create models and applications. The language, tools, and built-in math functions enable you to explore multiple approaches and reach a solution faster than with spreadsheets or traditional programming languages, such as C/C++ or Java. MATLAB Linear Algebra introduces you to the MATLAB language with practical hands-on instructions and results, allowing you to quickly achieve your goals. In addition to giving an introduction to
Special set linear algebra and special set fuzzy linear algebra
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...
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Munehiro, H
1980-05-29
When driving the carriage of a printer through a rotating motor, there are problems regarding the limited accuracy of the carriage position due to rotation or contraction and ageing of the cable. In order to solve the problem, a direct drive system was proposed, in which the printer carriage is driven by a linear motor. If one wants to keep the motor circuit of such a motor compact, then the magnetic flux density in the air gap must be reduced or the motor travel must be reduced. It is the purpose of this invention to create an electrodynamic linear motor, which on the one hand is compact and light and on the other hand has a relatively high constant force over a large travel. The invention is characterised by the fact that magnetic fields of alternating polarity are generated at equal intervals in the magnetic field, and that the coil arrangement has 2 adjacent coils, whose size corresponds to half the length of each magnetic pole. A logic circuit is provided to select one of the two coils and to determine the direction of the current depending on the signals of a magnetic field sensor on the coil arrangement.
International Nuclear Information System (INIS)
Kozarov, A.; Petrov, O.; Antonov, J.; Sotirova, S.; Petrova, B.
2006-01-01
The purpose of the linear wind-power generator described in this article is to decrease the following disadvantages of the common wind-powered turbine: 1) large bending and twisting moments to the blades and the shaft, especially when strong winds and turbulence exist; 2) significant values of the natural oscillation period of the construction result in the possibility of occurrence of destroying resonance oscillations; 3) high velocity of the peripheral parts of the rotor creating a danger for birds; 4) difficulties, connected with the installation and the operation on the mountain ridges and passages where the wind energy potential is the largest. The working surfaces of the generator in questions driven by the wind are not connected with a joint shaft but each moves along a railway track with few oscillations. So the sizes of each component are small and their number can be rather large. The mechanical trajectory is not a circle but a closed outline in a vertical plain, which consists of two rectilinear sectors, one above the other, connected in their ends by semi-circumferences. The mechanical energy of each component turns into electrical on the principle of the linear electrical generator. A regulation is provided when the direction of the wind is perpendicular to the route. A possibility of effectiveness is shown through aiming of additional quantities of air to the movable components by static barriers
Mastering NServiceBus and persistence
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.
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.
The Persistence of Mutual Fund Performance.
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.
A model for persistency of egg production
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
Lymphogranuloma venereum causing a persistent genital ulcer.
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.
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
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...
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.
Persistent Identifiers as Boundary Objects
Parsons, M. A.; Fox, P. A.
2017-12-01
In 1989, Leigh Star and Jim Griesemer defined the seminal concept of `boundary objects'. These `objects' are what Latour calls `immutable mobiles' that enable communication and collaboration across difference by helping meaning to be understood in different contexts. As Star notes, they are a sort of arrangement that allow different groups to work together without (a priori) consensus. Part of the idea is to recognize and allow for the `interpretive flexibility' that is central to much of the `constructivist' approach in the sociology of science. Persistent Identifiers (PIDs) can clearly act as boundary objects, but people do not usually assume that they enable interpretive flexibility. After all, they are meant to be unambiguous, machine-interpretable identifiers of defined artifacts. In this paper, we argue that PIDs can fill at least two roles: 1) That of the standardized form, where there is strong agreement on what is being represented and how and 2) that of the idealized type, a more conceptual concept that allows many different representations. We further argue that these seemingly abstract conceptions actually help us implement PIDs more effectively to link data, publications, various other artifacts, and especially people. Considering PIDs as boundary objects can help us address issues such as what level of granularity is necessary for PIDs, what metadata should be directly associated with PIDs, and what purpose is the PID serving (reference, provenance, credit, etc.). In short, sociological theory can improve data sharing standards and their implementation in a way that enables broad interdisciplinary data sharing and reuse. We will illustrate this with several specific examples of Earth science data.
A characterization of persistence at short times in the WFC3/IR detector
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.
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.
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
On the linear programming bound for linear Lee codes.
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.
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)
Linear Darier's disease: A case with bilateral presentation
Directory of Open Access Journals (Sweden)
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.
Persistence Characteristics of Australian Rainfall Anomalies
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.
Introduction to linear elasticity
Gould, Phillip L
2013-01-01
Introduction to Linear Elasticity, 3rd Edition, provides an applications-oriented grounding in the tensor-based theory of elasticity for students in mechanical, civil, aeronautical, and biomedical engineering, as well as materials and earth science. The book is distinct from the traditional text aimed at graduate students in solid mechanics by introducing the subject at a level appropriate for advanced undergraduate and beginning graduate students. The author's presentation allows students to apply the basic notions of stress analysis and move on to advanced work in continuum mechanics, plasticity, plate and shell theory, composite materials, viscoelasticity and finite method analysis. This book also: Emphasizes tensor-based approach while still distilling down to explicit notation Provides introduction to theory of plates, theory of shells, wave propagation, viscoelasticity and plasticity accessible to advanced undergraduate students Appropriate for courses following emerging trend of teaching solid mechan...
International Nuclear Information System (INIS)
Haniger, L.; Elger, R.; Kocandrle, L.; Zdebor, J.
1986-01-01
A linear step drive is described developed in Czechoslovak-Soviet cooperation and intended for driving WWER-1000 control rods. The functional principle is explained of the motor and the mechanical and electrical parts of the drive, power control, and the indicator of position are described. The motor has latches situated in the reactor at a distance of 3 m from magnetic armatures, it has a low structural height above the reactor cover, which suggests its suitability for seismic localities. Its magnetic circuits use counterpoles; the mechanical shocks at the completion of each step are damped using special design features. The position indicator is of a special design and evaluates motor position within ±1% of total travel. A drive diagram and the flow chart of both the control electronics and the position indicator are presented. (author) 4 figs
International Nuclear Information System (INIS)
Tjutju, R.L.
1977-01-01
Pulse amplifier is standard significant part of spectrometer. Apart from other type of amplification, it's a combination of amplification and pulse shaping. Because of its special purpose the device should fulfill the following : High resolution is desired to gain a high yield comparable to its actual state of condition. High signal to noise is desired to nhν resolution. High linearity to facilitate calibration. A good overload recovery, in order to the device will capable of analizing a low energy radiation which appear joinly on the high energy fields. Other expections of the device are its economical and practical use its extentive application. For that reason it's built on a standard NIM principle. Taking also into account the above mentioned considerations. High quality component parts are used throughout, while its availability in the domestic market is secured. (author)
International Nuclear Information System (INIS)
1976-01-01
This report covers the activity of the Linear Accelerator Laboratory during the period June 1974-June 1976. The activity of the Laboratory is essentially centered on high energy physics. The main activities were: experiments performed with the colliding rings (ACO), construction of the new colliding rings and beginning of the work at higher energy (DCI), bubble chamber experiments with the CERN PS neutrino beam, counter experiments with CERN's PS and setting-up of equipment for new experiments with CERN's SPS. During this period a project has also been prepared for an experiment with the new PETRA colliding ring at Hamburg. On the other hand, intense collaboration with the LURE Laboratory, using the electron synchrotron radiation emitted by ACO and DCI, has been developed [fr
Van Atta, C.M.; Beringer, R.; Smith, L.
1959-01-01
A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.
Tip, A.
1998-06-01
Starting from Maxwell's equations for a linear, nonconducting, absorptive, and dispersive medium, characterized by the constitutive equations D(x,t)=ɛ1(x)E(x,t)+∫t-∞dsχ(x,t-s)E(x,s) and H(x,t)=B(x,t), a unitary time evolution and canonical formalism is obtained. Given the complex, coordinate, and frequency-dependent, electric permeability ɛ(x,ω), no further assumptions are made. The procedure leads to a proper definition of band gaps in the periodic case and a new continuity equation for energy flow. An S-matrix formalism for scattering from lossy objects is presented in full detail. A quantized version of the formalism is derived and applied to the generation of Čerenkov and transition radiation as well as atomic decay. The last case suggests a useful generalization of the density of states to the absorptive situation.
On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock
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.
Computer Program For Linear Algebra
Krogh, F. T.; Hanson, R. J.
1987-01-01
Collection of routines provided for basic vector operations. Basic Linear Algebra Subprogram (BLAS) library is collection from FORTRAN-callable routines for employing standard techniques to perform basic operations of numerical linear algebra.
Quaternion Linear Canonical Transform Application
Bahri, Mawardi
2015-01-01
Quaternion linear canonical transform (QLCT) is a generalization of the classical linear canonical transfom (LCT) using quaternion algebra. The focus of this paper is to introduce an application of the QLCT to study of generalized swept-frequency filter
Recursive Algorithm For Linear Regression
Varanasi, S. V.
1988-01-01
Order of model determined easily. Linear-regression algorithhm includes recursive equations for coefficients of model of increased order. Algorithm eliminates duplicative calculations, facilitates search for minimum order of linear-regression model fitting set of data satisfactory.
Dynamical systems and linear algebra
Colonius, Fritz (Prof.)
2007-01-01
Dynamical systems and linear algebra / F. Colonius, W. Kliemann. - In: Handbook of linear algebra / ed. by Leslie Hogben. - Boca Raton : Chapman & Hall/CRC, 2007. - S. 56,1-56,22. - (Discrete mathematics and its applications)
Linear spaces: history and theory
Albrecht Beutelspracher
1990-01-01
Linear spaces belong to the most fundamental geometric and combinatorial structures. In this paper I would like to give an onerview about the theory of embedding finite linear spaces in finite projective planes.
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.
Monahan, John F
2008-01-01
Preface Examples of the General Linear Model Introduction One-Sample Problem Simple Linear Regression Multiple Regression One-Way ANOVA First Discussion The Two-Way Nested Model Two-Way Crossed Model Analysis of Covariance Autoregression Discussion The Linear Least Squares Problem The Normal Equations The Geometry of Least Squares Reparameterization Gram-Schmidt Orthonormalization Estimability and Least Squares Estimators Assumptions for the Linear Mean Model Confounding, Identifiability, and Estimability Estimability and Least Squares Estimators F
Laboratory diagnosis of persistent human chlamydial infection
Directory of Open Access Journals (Sweden)
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.
Persistent insomnia is associated with mortality risk.
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.
Templates for Linear Algebra Problems
Bai, Z.; Day, D.; Demmel, J.; Dongarra, J.; Gu, M.; Ruhe, A.; Vorst, H.A. van der
1995-01-01
The increasing availability of advanced-architecture computers is having a very signicant eect on all spheres of scientic computation, including algorithm research and software development in numerical linear algebra. Linear algebra {in particular, the solution of linear systems of equations and
Linearization of CIF through SOS
Nadales Agut, D.E.; Reniers, M.A.; Luttik, B.; Valencia, F.
2011-01-01
Linearization is the procedure of rewriting a process term into a linear form, which consist only of basic operators of the process language. This procedure is interesting both from a theoretical and a practical point of view. In particular, a linearization algorithm is needed for the Compositional
DEFF Research Database (Denmark)
Engberg, Uffe Henrik; Winskel, Glynn
This article shows how individual Petri nets form models of Girard's intuitionistic linear logic. It explores questions of expressiveness and completeness of linear logic with respect to this interpretation. An aim is to use Petri nets to give an understanding of linear logic and give some apprai...
International Nuclear Information System (INIS)
Richards, J.A.
1977-01-01
A linear particle accelerator which provides a pulsed beam of charged particles of uniform energy is described. The accelerator is in the form of an evacuated dielectric tube, inside of which a particle source is located at one end of the tube, with a target or window located at the other end of the dielectric tube. Along the length of the tube are externally located pairs of metal plates, each insulated from each other in an insulated housing. Each of the plates of a pair are connected to an electrical source of voltage of opposed polarity, with the polarity of the voltage of the plates oriented so that the plate of a pair, nearer to the particle source, is of the opposed polarity to the charge of the particle emitted by the source. Thus, a first plate about the tube located nearest the particle source, attracts a particle which as it passes through the tube past the first plate is then repelled by the reverse polarity of the second plate of the pair to continue moving towards the target
Generalized Linear Covariance Analysis
Carpenter, James R.; Markley, F. Landis
2014-01-01
This talk presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into solve-for'' and consider'' parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and textita priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the variance sandpile'' and the sensitivity mosaic,'' and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.
Equipartitioning in linear accelerators
International Nuclear Information System (INIS)
Jameson, R.A.
1982-01-01
Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined. At the same time, Hofmann has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. Evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown
Equipartitioning in linear accelerators
International Nuclear Information System (INIS)
Jameson, R.A.
1981-01-01
Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined below. At the same time, Hofmann, using powerful analytical and computational methods, has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. This is an important generalization. Work that he will present at this conference shows that the results are essentially the same in r-z coordinates for transport systems, and evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems also. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown
International Nuclear Information System (INIS)
Briggs, R.J.
1986-06-01
The development of linear induction accelerators has been motivated by applications requiring high-pulsed currents of charged particles at voltages exceeding the capability of single-stage, diode-type accelerators and at currents too high for rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multi-stage induction machine, but the 50-MeV, 10-kA Advanced Test Accelerator (ATA) at LLNL is the highest voltage machine in existence at this time. The advent of magnetic pulse power systems makes sustained operation at high-repetition rates practical, and this capability for high-average power is very likely to open up many new applications of induction machines in the future. This paper surveys the US induction linac technology with primary emphasis on electron machines. A simplified description of how induction machines couple energy to the electron beam is given, to illustrate many of the general issues that bound the design space of induction linacs
Berkeley Proton Linear Accelerator
Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.
1953-10-13
A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.
Global estimation of long-term persistence in annual river runoff
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.
Random linear codes in steganography
Directory of Open Access Journals (Sweden)
Kamil Kaczyński
2016-12-01
Full Text Available Syndrome coding using linear codes is a technique that allows improvement in the steganographic algorithms parameters. The use of random linear codes gives a great flexibility in choosing the parameters of the linear code. In parallel, it offers easy generation of parity check matrix. In this paper, the modification of LSB algorithm is presented. A random linear code [8, 2] was used as a base for algorithm modification. The implementation of the proposed algorithm, along with practical evaluation of algorithms’ parameters based on the test images was made.[b]Keywords:[/b] steganography, random linear codes, RLC, LSB
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.
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.
The persistent stereotype: children's images of scientists
Emens McAdam, Janice
1990-03-01
Through their reading children learn to regard scientists as eccentrics. It is shown that this stereotype has persisted for over thirty years and affects many adult attitudes. Some methods of breaking the author-reader cycle are suggested.
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
Persisting nutritional neuropathy amongst former war prisoners.
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...
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.
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 ...
Hyperthyroidism as a cause of persistent vomiting.
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.
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.
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.
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.
Non-Linear Dynamics of Saturn's Rings
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
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....
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.
Linear Programming and Network Flows
Bazaraa, Mokhtar S; Sherali, Hanif D
2011-01-01
The authoritative guide to modeling and solving complex problems with linear programming-extensively revised, expanded, and updated The only book to treat both linear programming techniques and network flows under one cover, Linear Programming and Network Flows, Fourth Edition has been completely updated with the latest developments on the topic. This new edition continues to successfully emphasize modeling concepts, the design and analysis of algorithms, and implementation strategies for problems in a variety of fields, including industrial engineering, management science, operations research
Herbicide Persistence in Seawater Simulation Experiments.
Directory of Open Access Journals (Sweden)
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
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
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
Gasoline on hands: preliminary study on collection and persistence.
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.
Elementary linear programming with applications
Kolman, Bernard
1995-01-01
Linear programming finds the least expensive way to meet given needs with available resources. Its results are used in every area of engineering and commerce: agriculture, oil refining, banking, and air transport. Authors Kolman and Beck present the basic notions of linear programming and illustrate how they are used to solve important common problems. The software on the included disk leads students step-by-step through the calculations. The Second Edition is completely revised and provides additional review material on linear algebra as well as complete coverage of elementary linear program
Hood, John Linsley
2013-01-01
The Art of Linear Electronics presents the principal aspects of linear electronics and techniques in linear electronic circuit design. The book provides a wide range of information on the elucidation of the methods and techniques in the design of linear electronic circuits. The text discusses such topics as electronic component symbols and circuit drawing; passive and active semiconductor components; DC and low frequency amplifiers; and the basic effects of feedback. Subjects on frequency response modifying circuits and filters; audio amplifiers; low frequency oscillators and waveform generato
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 ...
The linear programming bound for binary linear codes
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.
Linear operator inequalities for strongly stable weakly regular linear systems
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
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)
Advanced statistics: linear regression, part I: simple linear regression.
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.
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.
Generating Dynamic Persistence in the Time Domain
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.
Persistent agents in Axelrod's social dynamics model
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.
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.
Directory of Open Access Journals (Sweden)
Crasmareanu Mircea
2017-12-01
Full Text Available We consider the paracomplex version of the notion of mixed linear spaces introduced by M. Jurchescu in [4] by replacing the complex unit i with the paracomplex unit j, j2 = 1. The linear algebra of these spaces is studied with a special view towards their morphisms.
Linear Algebra and Image Processing
Allali, Mohamed
2010-01-01
We use the computing technology digital image processing (DIP) to enhance the teaching of linear algebra so as to make the course more visual and interesting. Certainly, this visual approach by using technology to link linear algebra to DIP is interesting and unexpected to both students as well as many faculty. (Contains 2 tables and 11 figures.)
Efficient Searching with Linear Constraints
DEFF Research Database (Denmark)
Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff
2000-01-01
We show how to preprocess a set S of points in d into an external memory data structure that efficiently supports linear-constraint queries. Each query is in the form of a linear constraint xd a0+∑d−1i=1 aixi; the data structure must report all the points of S that satisfy the constraint. This pr...
Johnson, Bruce G.; Gerver, Michael J.; Hawkey, Timothy J.; Fenn, Ralph C.
1993-01-01
Improved linear actuator comprises air slide and linear electric motor. Unit exhibits low friction, low backlash, and more nearly even acceleration. Used in machinery in which positions, velocities, and accelerations must be carefully controlled and/or vibrations must be suppressed.
Linear morphoea follows Blaschko's lines.
Weibel, L; Harper, J I
2008-07-01
The aetiology of morphoea (or localized scleroderma) remains unknown. It has previously been suggested that lesions of linear morphoea may follow Blaschko's lines and thus reflect an embryological development. However, the distribution of linear morphoea has never been accurately evaluated. We aimed to identify common patterns of clinical presentation in children with linear morphoea and to establish whether linear morphoea follows the lines of Blaschko. A retrospective chart review of 65 children with linear morphoea was performed. According to clinical photographs the skin lesions of these patients were plotted on to standardized head and body charts. With the aid of Adobe Illustrator a final figure was produced including an overlay of all individual lesions which was used for comparison with the published lines of Blaschko. Thirty-four (53%) patients had the en coup de sabre subtype, 27 (41%) presented with linear morphoea on the trunk and/or limbs and four (6%) children had a combination of the two. In 55 (85%) children the skin lesions were confined to one side of the body, showing no preference for either left or right side. On comparing the overlays of all body and head lesions with the original lines of Blaschko there was an excellent correlation. Our data indicate that linear morphoea follows the lines of Blaschko. We hypothesize that in patients with linear morphoea susceptible cells are present in a mosaic state and that exposure to some trigger factor may result in the development of this condition.
Campagnoli, Patrizia; Petris, Giovanni
2009-01-01
State space models have gained tremendous popularity in as disparate fields as engineering, economics, genetics and ecology. Introducing general state space models, this book focuses on dynamic linear models, emphasizing their Bayesian analysis. It illustrates the fundamental steps needed to use dynamic linear models in practice, using R package.
Linear Programming across the Curriculum
Yoder, S. Elizabeth; Kurz, M. Elizabeth
2015-01-01
Linear programming (LP) is taught in different departments across college campuses with engineering and management curricula. Modeling an LP problem is taught in every linear programming class. As faculty teaching in Engineering and Management departments, the depth to which teachers should expect students to master this particular type of…
Introduction to RF linear accelerators
International Nuclear Information System (INIS)
Weiss, M.
1994-01-01
The basic features of RF linear accelerators are described. The concept of the 'loaded cavity', essential for the synchronism wave-particle, is introduced, and formulae describing the action of electromagnetic fields on the beam are given. The treatment of intense beams is mentioned, and various existing linear accelerators are presented as examples. (orig.)
Spatial Processes in Linear Ordering
von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud
2016-01-01
Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A -- B -- C -- D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial…
DEFF Research Database (Denmark)
Andersen, O. Krogh
1975-01-01
of Korringa-Kohn-Rostoker, linear-combination-of-atomic-orbitals, and cellular methods; the secular matrix is linear in energy, the overlap integrals factorize as potential parameters and structure constants, the latter are canonical in the sense that they neither depend on the energy nor the cell volume...
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.
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 toxic substances: sources, fates and effects.
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.
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.
Introduction to generalized linear models
Dobson, Annette J
2008-01-01
Introduction Background Scope Notation Distributions Related to the Normal Distribution Quadratic Forms Estimation Model Fitting Introduction Examples Some Principles of Statistical Modeling Notation and Coding for Explanatory Variables Exponential Family and Generalized Linear Models Introduction Exponential Family of Distributions Properties of Distributions in the Exponential Family Generalized Linear Models Examples Estimation Introduction Example: Failure Times for Pressure Vessels Maximum Likelihood Estimation Poisson Regression Example Inference Introduction Sampling Distribution for Score Statistics Taylor Series Approximations Sampling Distribution for MLEs Log-Likelihood Ratio Statistic Sampling Distribution for the Deviance Hypothesis Testing Normal Linear Models Introduction Basic Results Multiple Linear Regression Analysis of Variance Analysis of Covariance General Linear Models Binary Variables and Logistic Regression Probability Distributions ...
Acoustic emission linear pulse holography
International Nuclear Information System (INIS)
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-01-01
This paper describes the emission linear pulse holography which produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. A thirty two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The concept behind the AE linear pulse holography is illustrated, and a block diagram of a data acquisition system to implement the concept is given. Array element spacing, synthetic frequency criteria, and lateral depth resolution are specified. A reference timing transducer positioned between the array and the inspection zone and which inititates the time-of-flight measurements is described. The results graphically illustrate the technique using a one-dimensional FFT computer algorithm (ie. linear backward wave) for an AE image reconstruction
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.
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.
Linear and Generalized Linear Mixed Models and Their Applications
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
Persisting nutritional neuropathy amongst former war prisoners.
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
PERSISTENCY ANALYSIS OF PARTICIPANTS OF PENSION PLANS
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...
Amnestically Induced Persistence in Random Walks
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 of Long Work Hours
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...
Ferencz, Donald C.; Viterna, Larry A.
1991-01-01
ALPS is a computer program which can be used to solve general linear program (optimization) problems. ALPS was designed for those who have minimal linear programming (LP) knowledge and features a menu-driven scheme to guide the user through the process of creating and solving LP formulations. Once created, the problems can be edited and stored in standard DOS ASCII files to provide portability to various word processors or even other linear programming packages. Unlike many math-oriented LP solvers, ALPS contains an LP parser that reads through the LP formulation and reports several types of errors to the user. ALPS provides a large amount of solution data which is often useful in problem solving. In addition to pure linear programs, ALPS can solve for integer, mixed integer, and binary type problems. Pure linear programs are solved with the revised simplex method. Integer or mixed integer programs are solved initially with the revised simplex, and the completed using the branch-and-bound technique. Binary programs are solved with the method of implicit enumeration. This manual describes how to use ALPS to create, edit, and solve linear programming problems. Instructions for installing ALPS on a PC compatible computer are included in the appendices along with a general introduction to linear programming. A programmers guide is also included for assistance in modifying and maintaining the program.
Linear and quasi-linear equations of parabolic type
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.
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.
Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review.
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.
Using Benchmarking To Strengthen the Assessment of Persistence.
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.
The Theory of Linear Prediction
Vaidyanathan, PP
2007-01-01
Linear prediction theory has had a profound impact in the field of digital signal processing. Although the theory dates back to the early 1940s, its influence can still be seen in applications today. The theory is based on very elegant mathematics and leads to many beautiful insights into statistical signal processing. Although prediction is only a part of the more general topics of linear estimation, filtering, and smoothing, this book focuses on linear prediction. This has enabled detailed discussion of a number of issues that are normally not found in texts. For example, the theory of vecto
Correlation and simple linear regression.
Zou, Kelly H; Tuncali, Kemal; Silverman, Stuart G
2003-06-01
In this tutorial article, the concepts of correlation and regression are reviewed and demonstrated. The authors review and compare two correlation coefficients, the Pearson correlation coefficient and the Spearman rho, for measuring linear and nonlinear relationships between two continuous variables. In the case of measuring the linear relationship between a predictor and an outcome variable, simple linear regression analysis is conducted. These statistical concepts are illustrated by using a data set from published literature to assess a computed tomography-guided interventional technique. These statistical methods are important for exploring the relationships between variables and can be applied to many radiologic studies.
Saravanan, R
2018-01-01
Non-linear optical materials have widespread and promising applications, but the efforts to understand the local structure, electron density distribution and bonding is still lacking. The present work explores the structural details, the electron density distribution and the local bond length distribution of some non-linear optical materials. It also gives estimation of the optical band gap, the particle size, crystallite size, and the elemental composition from UV-Visible analysis, SEM, XRD and EDS of some non-linear optical materials respectively.
Optimal control linear quadratic methods
Anderson, Brian D O
2007-01-01
This augmented edition of a respected text teaches the reader how to use linear quadratic Gaussian methods effectively for the design of control systems. It explores linear optimal control theory from an engineering viewpoint, with step-by-step explanations that show clearly how to make practical use of the material.The three-part treatment begins with the basic theory of the linear regulator/tracker for time-invariant and time-varying systems. The Hamilton-Jacobi equation is introduced using the Principle of Optimality, and the infinite-time problem is considered. The second part outlines the
The Enigmatic Persistence of Anorexia Nervosa
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
Nitrogen uptake dynamics of a persistent cyanobacterium ...
African Journals Online (AJOL)
Worldwide, persistent cyanobacterial blooms are becoming more frequent and are often associated with effects of global climate change. In June 2009, a widespread bloom of the unicellular cyanobacterium, Cyanothece sp., appeared in North Lake and False Bay of Lake St Lucia – a large (360 km2) estuarine lake system ...
Persistent Functional Languages: Toward Functional Relational Databases
Wevers, L.
2014-01-01
Functional languages provide new approaches to concurrency control, based on techniques such as lazy evaluation and memoization. We have designed and implemented a persistent functional language based on these ideas, which we plan to use for the implementation of a relational database system. With
Persistent pain after mastectomy with reconstruction.
LENUS (Irish Health Repository)
Hickey, Oonagh T
2011-09-01
To determine the prevalence of persistent postsurgical pain (PPSP) and its influence on functional status, and to examine associations between PPSP and single nucleotide polymorphisms of the catechol-O-methyltransferase (COMT) gene and the guanosine triphosphate cyclohydrolase 1 (GCH1) gene following mastectomy and reconstruction.
Persistent ovarian masses and pregnancy outcomes.
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.
Persistence of Change: Fume Hood Campaign Lessons
Feder, Elah; Robinson, Jennifer; Wakefield, Sarah
2012-01-01
Purpose: Sustainability initiatives typically operate for a limited time period, but it is often unclear whether they have lasting effects. The purpose of this paper is to examine a laboratory fume hood campaign, in order to identify factors that might contribute or detract from long-term change persistence. Design/methodology/approach: The…
Treatment of persistent pain from torture
DEFF Research Database (Denmark)
Williams, Amanda C de C; Amris, Kirstine
2017-01-01
the nature of persistent pain means that pain is largely overlooked and untreated in torture survivors. We carried out a systematic review on treatments for pain from torture, but found few studies and little use of current understanding and evidence. We discuss this in the context of treating pain...
Reserve design to maximize species persistence
Robert G. Haight; Laurel E. Travis
2008-01-01
We develop a reserve design strategy to maximize the probability of species persistence predicted by a stochastic, individual-based, metapopulation model. Because the population model does not fit exact optimization procedures, our strategy involves deriving promising solutions from theory, obtaining promising solutions from a simulation optimization heuristic, and...
Retrospective review of neonates with persistent pulmonary ...
African Journals Online (AJOL)
Persistent pulmonary hypertension of the newborn (PPHN) is a clinical condition characterised by severe respiratory failure and hypoxaemia.[1] Its incidence is estimated at around 2 per 1 000 live births worldwide and it is associated with a high morbidity and mortality.[2,3] Despite the progress in treating PPHN, it remains a.
A Neonate with persistent hypoglycemia and seizures.
African Journals Online (AJOL)
MBY
disorder was diagnosed and managed with limited success as the episodes hydroglycemic seizures persisted. ... the presence of hyperinsulinemia as the cause of the hypoglycemic dependent seizures. Case Presentation. A three day old girl was admitted to the neonatal .... the Prader-Willi syndrome, has been reported.
Persistent Pain and Sensory Abnormalities after Abdominoplasty
DEFF Research Database (Denmark)
Presman, Benjamin; Finnerup, Kenneth; Andresen, Sven Robert
2015-01-01
and characteristics of persistent pain after abdominoplasty, which is one of the most frequent cosmetic surgical procedures. METHODS: In September 2014, a link to a web-based questionnaire was mailed to 217 patients who had undergone abdominoplasty between 2006 and 2014 at the Department of Plastic Surgery, Aalborg...
The Myth of Persistence of Vision Revisited.
Anderson, Joseph; Anderson, Barbara
1993-01-01
Argues that "persistence of vision" myth (the succession of still images perceived as continuous motion) has a place in the history of film scholarship but can no longer be given currency in film theory. Suggests replacement of the concept of the passive viewer implied by the myth by an enlightened understanding of how viewers actually…
Forecasting autoregressive time series under changing persistence
DEFF Research Database (Denmark)
Kruse, Robinson
Changing persistence in time series models means that a structural change from nonstationarity to stationarity or vice versa occurs over time. Such a change has important implications for forecasting, as negligence may lead to inaccurate model predictions. This paper derives generally applicable...
Persistence Modeling for Assessing Marketing Strategy Performance
M.G. Dekimpe (Marnik); D.M. Hanssens (Dominique)
2003-01-01
textabstractThe question of long-run market response lies at the heart of any marketing strategy that tries to create a sustainable competitive advantage for the firm or brand. A key challenge, however, is that only short-run results of marketing actions are readily observable. Persistence modeling
Persistent trophoblast disease following partial molar pregnancy.
Wielsma, S.; Kerkmeijer, L.G.W.; Bekkers, R.L.M.; Pyman, J.; Tan, J.; Quinn, M.
2006-01-01
OBJECTIVE: Human chorionic gonadotrophin (hCG) follow-up data were analysed retrospectively in all patients registered in the Hydatidiform Mole Registry at the Royal Women's Hospital, Melbourne from January 1992 to January 2001 to determine the risk of persistent trophoblast disease following
Intermediates, Catalysts, Persistence, and Boundary Steady States
DEFF Research Database (Denmark)
Marcondes de Freitas, Michael; Feliu, Elisenda; Wiuf, Carsten
2017-01-01
networks without breaking known necessary or sufficient conditions for persistence, by iteratively removing socalled intermediates and catalysts from the network. The procedures are easy to apply and, in many cases, lead to highly simplified network structures, such as monomolecular networks. For specific...
Diversity of Lactase Persistence Alleles in Ethiopia
DEFF Research Database (Denmark)
Jones, BL; Raga, TO; Liebert, Anke
2013-01-01
The persistent expression of lactase into adulthood in humans is a recent genetic adaptation that allows the consumption of milk from other mammals after weaning. In Europe, a single allele (−13910∗T, rs4988235) in an upstream region that acts as an enhancer to the expression of the lactase gene ...
Hyperthyroidism as a cause of persistent vomiting.
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
Ethnic Differences in Persistence with COPD Medications
DEFF Research Database (Denmark)
Hu, Yusun; Cantarero-Arévalo, Lourdes; Frølich, Anne
2017-01-01
BACKGROUND: Long-acting bronchodilators (LABDs) are recommended as a first-line maintenance therapy in patients with moderate or severe chronic obstructive pulmonary disease (COPD). The aim of the study was to explore potential ethnic differences in persistence with LABD in COPD patients. METHODS...
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.
Persistence of Value-Driven Attentional Capture
Anderson, Brian A.; Yantis, Steven
2013-01-01
Stimuli that have previously been associated with the delivery of reward involuntarily capture attention when presented as unrewarded and task-irrelevant distractors in a subsequent visual search task. It is unknown how long such effects of reward learning on attention persist. One possibility is that value-driven attentional biases are plastic…
Retrospective review of neonates with persistent pulmonary ...
African Journals Online (AJOL)
Background. Persistent pulmonary hypertension of the newborn (PPHN) is a clinical syndrome characterised by high pulmonary pressures, low systemic pressures and severe hypoxaemia due to circulation transition failure after birth. Objective. To determine the incidence of and describe the risk factors, infant ...
Judgment of facial expressions and depression persistence
Hale, WW
1998-01-01
In research it has been demonstrated that cognitive and interpersonal processes play significant roles in depression development and persistence. The judgment of emotions displayed in facial expressions by depressed patients allows for a better understanding of these processes. In this study, 48
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.
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
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
Persistence of undergraduate women in STEM fields
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
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.
Extending and implementing the Persistent ID pillars
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.
Cellular Automata Rules and Linear Numbers
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.
Feedback systems for linear colliders
Hendrickson, L; Himel, Thomas M; Minty, Michiko G; Phinney, N; Raimondi, Pantaleo; Raubenheimer, T O; Shoaee, H; Tenenbaum, P G
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an intregal part of the design. Feedback requiremetns for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at hi...
An introduction to linear algebra
Mirsky, L
2003-01-01
Rigorous, self-contained coverage of determinants, vectors, matrices and linear equations, quadratic forms, more. Elementary, easily readable account with numerous examples and problems at the end of each chapter.
CLIC: developing a linear collider
Laurent Guiraud
1999-01-01
Compact Linear Collider (CLIC) is a CERN project to provide high-energy electron-positron collisions. Instead of conventional radio-frequency klystrons, CLIC will use a low-energy, high-intensity primary beam to produce acceleration.
1988 linear accelerator conference proceedings
International Nuclear Information System (INIS)
1989-06-01
This report contains papers presented at the 1988 Linear Accelerator Conference. A few topics covered are beam dynamics; beam transport; superconducting components; free electron lasers; ion sources; and klystron research
CERN balances linear collider studies
ILC Newsline
2011-01-01
The forces behind the two most mature proposals for a next-generation collider, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) study, have been steadily coming together, with scientists from both communities sharing ideas and information across the technology divide. In a support of cooperation between the two, CERN in Switzerland, where most CLIC research takes place, recently converted the project-specific position of CLIC Study Leader to the concept-based Linear Collider Study Leader. The scientist who now holds this position, Steinar Stapnes, is charged with making the linear collider a viable option for CERN’s future, one that could include either CLIC or the ILC. The transition to more involve the ILC must be gradual, he said, and the redefinition of his post is a good start. Though not very much involved with superconducting radiofrequency (SRF) technology, where ILC researchers have made significant advances, CERN participates in many aspect...
Linear Methods for Image Interpolation
Pascal Getreuer
2011-01-01
We discuss linear methods for interpolation, including nearest neighbor, bilinear, bicubic, splines, and sinc interpolation. We focus on separable interpolation, so most of what is said applies to one-dimensional interpolation as well as N-dimensional separable interpolation.
Klumpp, A. R.; Lawson, C. L.
1988-01-01
Routines provided for common scalar, vector, matrix, and quaternion operations. Computer program extends Ada programming language to include linear-algebra capabilities similar to HAS/S programming language. Designed for such avionics applications as software for Space Station.
Acoustic emission linear pulse holography
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-10-25
This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.
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...
Functionalized linear and cyclic polyolefins
Energy Technology Data Exchange (ETDEWEB)
Tuba, Robert; Grubbs, Robert H.
2018-02-13
This invention relates to methods and compositions for preparing linear and cyclic polyolefins. More particularly, the invention relates to methods and compositions for preparing functionalized linear and cyclic polyolefins via olefin metathesis reactions. Polymer products produced via the olefin metathesis reactions of the invention may be utilized for a wide range of materials applications. The invention has utility in the fields of polymer and materials chemistry and manufacture.
Directory of Open Access Journals (Sweden)
Rumen Daskalov
2017-07-01
Full Text Available Let an $[n,k,d]_q$ code be a linear code of length $n$, dimension $k$ and minimum Hamming distance $d$ over $GF(q$. One of the most important problems in coding theory is to construct codes with optimal minimum distances. In this paper 22 new ternary linear codes are presented. Two of them are optimal. All new codes improve the respective lower bounds in [11].
Explorative methods in linear models
DEFF Research Database (Denmark)
Høskuldsson, Agnar
2004-01-01
The author has developed the H-method of mathematical modeling that builds up the model by parts, where each part is optimized with respect to prediction. Besides providing with better predictions than traditional methods, these methods provide with graphic procedures for analyzing different feat...... features in data. These graphic methods extend the well-known methods and results of Principal Component Analysis to any linear model. Here the graphic procedures are applied to linear regression and Ridge Regression....
Polarized Electrons for Linear Colliders
International Nuclear Information System (INIS)
Clendenin, J.
2004-01-01
Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%
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
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.
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
Emotional persistence in online chatting communities
Garas, Antonios; Garcia, David; Skowron, Marcin; Schweitzer, Frank
2012-05-01
How do users behave in online chatrooms, where they instantaneously read and write posts? We analyzed about 2.5 million posts covering various topics in Internet relay channels, and found that user activity patterns follow known power-law and stretched exponential distributions, indicating that online chat activity is not different from other forms of communication. Analysing the emotional expressions (positive, negative, neutral) of users, we revealed a remarkable persistence both for individual users and channels. I.e. despite their anonymity, users tend to follow social norms in repeated interactions in online chats, which results in a specific emotional ``tone'' of the channels. We provide an agent-based model of emotional interaction, which recovers qualitatively both the activity patterns in chatrooms and the emotional persistence of users and channels. While our assumptions about agent's emotional expressions are rooted in psychology, the model allows to test different hypothesis regarding their emotional impact in online communication.
Persistent hyperlactacidaemia: about a clinical case.
Oliveira, Ana Rita Saraiva; Valente, Rosalina; Ramos, José; Ventura, Lurdes
2013-05-22
Lactate is the endogenous end product of the anaerobic glycolysis, whose production is favoured in situations of hypoperfusion or mitochondrial dysfunction. Leigh syndrome is a rare, progressive encephalomyopathy that represents a spectrum of mitochondrial genetic diseases phenotypically distinct, but with neuroradiological and pathological uniform presentation. We present the case of a 7-month-old infant, with a history of prematurity, psychomotor retardation and epilepsy, admitted to the paediatric intensive care unit (PICU) due to cardio-respiratory arrest because of respiratory infection. Hyperlactacidaemia was detected and was persistent. The study of redox potential was normal but MRI with spectroscopy identified bilateral and symmetrical lesions involving thalamic and basal ganglia, with small lactate peaks at T2 flair, findings that were suggestive of Leigh syndrome. Subsequent enzymatic study identified lack of pyruvate dehydrogenase. Persistent hyperlactacidaemia, in the appropriate clinical context, should lead to the screening of mitochondrial diseases.
Persistent pulmonary hypertension of the newborn.
Nair, P M C; Bataclan, Maria Flordeliz A
2004-06-01
This article attempts to define a complicated, yet not rare disease of the neonate, which presents with extreme hypoxemia due to increased pulmonary vascular resistance, resulting in diversion of the pulmonary venous blood through persistent fetal channels, namely ductus arteriosus and foramen ovale. Pathophysiology, diagnostic approach and the various modalities of management are analyzed. Persistent pulmonary hypertension of the newborn is multi-factorial, which is reflected in the management as well. These babies are extremely labile to hypoxia and should be stabilized with minimum handling. One hundred percent oxygen and ventilation are the mainstay of treatment. The role of hyperventilation, alkalinization, various non-specific vasodilators such as tolazoline, magnesium sulphate, selective vasodilators such as inhaled nitric oxide, adenosine and the role of high frequency oscillatory ventilation and extra corporeal membrane oxygenation are discussed. With the newer modalities of management, the outlook has improved with mortality of less than 20% and fewer long-term deficits.
Patients with persistent medically unexplained physical symptoms
DEFF Research Database (Denmark)
A, Aamland; Malterud, Kirsti; Werner, E.
2014-01-01
for all variables and split analysis on gender and age. RESULTS: The GPs registered 526 patients among their total of 17 688 consultations, giving a consultation prevalence of persistent MUPS of 3%. The mean age of patients was 46 years, and 399 (76%) were women. The most frequent group of symptoms...... was musculoskeletal problems, followed by asthenia/fatigue. There was no significant gender difference in symptom pattern. Almost half of the patients were currently working (45%), significantly more men. The major GP management strategy was supportive counseling. CONCLUSION: A consultation prevalence rate of 3......% implies that patients with persistent MUPS are common in general practice. Our study disclosed heterogeneity among the patients such as differences in employment status, which emphasizes the importance of personalized focus rather than unsubstantiated stereotyping of "MUPS patients" as a group....
Persistent Identifiers for Dutch cultural heritage institutions
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
Persistent Aerial Tracking system for UAVs
Mueller, Matthias
2016-12-19
In this paper, 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 evaluate several state-of-the-art trackers on the VIVID aerial video dataset and additional sequences that are specifically tailored to low altitude UAV target tracking. Based on the evaluation, we select the leading tracker and improve upon it by optimizing for both speed and performance, 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.
Persistent Aerial Tracking system for UAVs
Mueller, Matthias; Sharma, Gopal; Smith, Neil; Ghanem, Bernard
2016-01-01
In this paper, 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 evaluate several state-of-the-art trackers on the VIVID aerial video dataset and additional sequences that are specifically tailored to low altitude UAV target tracking. Based on the evaluation, we select the leading tracker and improve upon it by optimizing for both speed and performance, 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.
Imaging approach to persistent neonatal jaundice
International Nuclear Information System (INIS)
Kirks, D.; Coleman, R.E.; Filston, H.C.; Rosenberg, E.R.; Merten, D.F.
1984-01-01
Fifteen patients with persistent neonatal jaundice were evaluated by sonography and radionuclide scintigraphy. The sonographic features of both neonatal hepatitis and biliary atresia are nonspecific. Hepatobiliary scintigraphy after phenobarbital pretreatment in patients with neonatal hepatitis demonstrates normal hepatic extraction and delayed tracer excretion into the gastrointestinal tract. If there is neonatal hepatitis with severe hepatocellular damage, the hepatic extraction of tracer activity is decreased and excretion may be delayed or absent. Patients under 3 months of age with biliary atresia have normal hepatic extraction of tracer with no excretion into the gastrointestinal tract. Sonography in patients with a choledochal cyst shows a cystic mass in the porta hepatis with associated bile-duct dilatation. Hepatobiliary scintigraphy confirms that the choledochal cyst communicates with the biliary system. Initial sonography demonstrates hepatobiliary anatomy; subsequent phenobarbital-enhanced radionuclide scintigraphy determines hepatobiliary function. An expedient diagnostic approach is recommended for the evaluation of persistent neonatal jaundice
Persistent hepatitis virus infection and immune homeostasis
ZHOU Yun
2014-01-01
Homeostasis between the host and viruses is naturally maintained. On the one hand, the immune system activates the immune response to kill or eliminate viruses; on the other hand, the immune system controls the immune response to maintain immune homeostasis. The cause of persistent infections with hepatitis viruses such as HBV and HCV is that viral molecules damage the immune system of the host and their variants escape immune clearance. Long-term coexistence of the host and viruses is the pr...
The persistence of marketing effects on sales
Dekimpe, Marnik; Hanssens, DM
1993-01-01
Are marketing efforts able to affect long-term trends in sales or other performance measures? Answering this question is essential for the creation of marketing strategies that deliver a sustainable competitive advantage. This paper introduces persistence modeling to derive long-term marketing effectiveness from time-series observations on sales and marketing expenditures. First, we use unit-root tests to determine whether sales are stable or evolving (trending) over time. If they are evolvin...
Mobility-induced persistent chimera states
Petrungaro, Gabriela; Uriu, Koichiro; Morelli, Luis G.
2017-12-01
We study the dynamics of mobile, locally coupled identical oscillators in the presence of coupling delays. We find different kinds of chimera states in which coherent in-phase and antiphase domains coexist with incoherent domains. These chimera states are dynamic and can persist for long times for intermediate mobility values. We discuss the mechanisms leading to the formation of these chimera states in different mobility regimes. This finding could be relevant for natural and technological systems composed of mobile communicating agents.
Understanding and Responding to Persistently High Unemployment
2012-02-01
Persistent Effects of Job Displacement: The Importance of Multiple Job Losses,” Journal of Labor Economics , vol. 15, no. 1, part 1 (January 1997), pp...Capital: Evidence from Displaced Workers,” Journal of Labor Economics , vol. 13, no. 4 (October 1995), pp. 653–677.one-third had trouble meeting...Effects of Worker Displacement,” Journal of Labor Economics , vol. 26, no. 3 (July 2008), pp. 455–483. completed its most recent economic forecast), that
Actinomyces associated with persistent vaginal granulation tissue.
Wai, Clifford Y; Nihira, Mikio A; Drewes, Peter G; Chang, Joe S; Siddiqui, Momin T; Hemsell, David L
2005-01-01
BACKGROUND: We report a case of symptomatic actinomycosis associated with vaginal suture erosion and granulation tissue refractory to conservative management, in an outpatient setting. CASE: Three months after total vaginal hysterectomy and uterosacral ligament vaginal vault suspension, a woman complained of painless, intermittent vaginal discharge and spotting. Despite cauterization of granulation tissue, vaginal spotting persisted for another month. On re-examination, braided polyester sutu...
Persistent postsurgical pain: risk factors and prevention
DEFF Research Database (Denmark)
Kehlet, Henrik; Jensen, Troels Staehelin; Woolf, Clifford J.
2006-01-01
therapy for postoperative pain should be investigated, since the intensity of acute postoperative pain correlates with the risk of developing a persistent pain state. Finally, the role of genetic factors should be studied, since only a proportion of patients with intraoperative nerve damage develop...... chronic pain. Based on information about the molecular mechanisms that affect changes to the peripheral and central nervous system in neuropathic pain, several opportunities exist for multimodal pharmacological intervention. Here, we outline strategies for identification of patients at risk...
Information persistence using XML database technology
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
Anomaly equations and the persistent mass condition
International Nuclear Information System (INIS)
Cohen, E.; Frishman, Y.
1982-01-01
Vector SU(Nsub(c)) gauge theories with nsub(f) flavors in the fundamental representation are considered. We prove that if the persistent mass condition is assumed, the two anomaly equations are identical and flavor independent for nsub(f) >= 3. Integer solutions exist only for nsub(f) = 2. The necessity of a separate discussion for 2 <= nsub(f) <= Nsub(c) is explained. (orig.)
[Persistent duodenal septum in an adult].
Helwing, E; Echtermeyer, V; Otten, G
1977-02-01
A case of duodenal obstruction by a congenital duodenal web in a 34-year-old woman is presented. A mucosal diaphragm obstructed the duodenum. It showed an excentric opening of 0.8 cm diameter, but the dilated diaphragm caused a total stop during the last months. Despite a typical history, exact X-ray, and endoscopic examination, the correct preoperative diagnosis was not found, because nobody thought it possible, that a mucosal diapharm of the duodenum could persist for 34 years.
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)
Lactase Non-persistence and Lactose Intolerance.
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...
Persistent producer-scrounger relationships in bats.
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.
Overview of persistent pain in older adults.
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.
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)
University Experiences and Women Engineering Student Persistence
Ayers, LoAnn Debra Gienger
Riverside University (a pseudonym), like many universities, has not significantly increased the number of women who graduate with bachelor's degrees in engineering. The purpose of the study is to understand how the university experiences of women students influence the decision to persist in an undergraduate engineering degree and to understand the role of self-perception in how the students perceive experiences as supporting or hindering their persistence in the major. Archival data, documents and artifacts, observations, individual interviews, and a focus group with women engineering students provide insights into students' perceived barriers and supports of student success. Analysis of the data results in two major themes. First, students' self-confidence and self-efficacy influence how women assimilate university experiences as either supportive or diminishing of academic success. Second, university policies and practices shape the campus environment within which student experiences are formed and influence a student's level of institutional, academic, and social integration. The results of the study indicate opportunities for university leadership to enhance strategies that positively shape students' institutional, academic and social integration as precursors toward increasing the number of women students who successfully complete undergraduate engineering degrees at Riverside University. Future research is indicated to better understand how gender and gender identity intersects with other demographic factors, such as socio-economic status, immigration status, and life stage (e.g., traditional versus non-traditional students), to support or deter the persistence of engineering students to degree completion.
Reoperation for persistent or recurrent secondary hyperparathyroidism.
Abruzzo, Alida; Gioviale, Maria Concetta; Damiano, Giuseppe; Palumbo, Vincenzo Davide; Buscemi, Salvatore; Lo Monte, Giulia; Gulotta, Leonardo; Buscemi, Giuseppe; Lo Monte, Attilio Ignazio
2017-10-23
Secondary hyperparathyroidism is a common acquired disorder seen in chronic renal failure. Its pathophysiology is mainly due to hyperphosphatemia and vitamin D deficiency and resistance. When medical treatment fails, subtotal and total parathyroidectomy with autotransplantation are the standard procedures, although both are associated with high recurrence rates. 4 patients experienced persistence and 9 relapse. The first 4 were subjected to reoperation after 6 months for the persistence of symptoms due to the finding of a supernumerary adenomatous gland while the remaining patients at the reoperation showed in 5 cases 2 more glands in over thymic position, and 4 an hyperplasia of the residual glandular tissue. A classic cervicotomy was sufficient to remove the residual parathyroid in patients with persistent hyperparathyroidism. For cases of recurrent hyperparathyroidism it was enough a medial approach and sometimes lateral for the complete excision of the hyperplastic tissue. The advent of the intraoperative technique of parathyroid hormone dosage allowed a better performance of the surgical technique for the last 3 patients undergoing reoperation. After reoperation all patients had immediate regression of clinical symptoms with normalization of serum calcium and PTH levels. On the basis of these considerations, diagnostic imaging has a not negligible role because during the first intervention helps to have an idea of the possible location of the glands and thus to avoid the risk of recurrence and relapse due to ectopic or supernumerary tissue.
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.)
Advanced statistics: linear regression, part II: multiple linear regression.
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.
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.)
Linearization: Geometric, Complex, and Conditional
Directory of Open Access Journals (Sweden)
Asghar Qadir
2012-01-01
Full Text Available Lie symmetry analysis provides a systematic method of obtaining exact solutions of nonlinear (systems of differential equations, whether partial or ordinary. Of special interest is the procedure that Lie developed to transform scalar nonlinear second-order ordinary differential equations to linear form. Not much work was done in this direction to start with, but recently there have been various developments. Here, first the original work of Lie (and the early developments on it, and then more recent developments based on geometry and complex analysis, apart from Lie’s own method of algebra (namely, Lie group theory, are reviewed. It is relevant to mention that much of the work is not linearization but uses the base of linearization.
Window observers for linear systems
Directory of Open Access Journals (Sweden)
Utkin Vadim
2000-01-01
Full Text Available Given a linear system x ˙ = A x + B u with output y = C x and a window function ω ( t , i.e., ∀ t , ω ( t ∈ {0,1 }, and assuming that the window function is Lebesgue measurable, we refer to the following observer, x ˆ = A x + B u + ω ( t L C ( x − x ˆ as a window observer. The stability issue is treated in this paper. It is proven that for linear time-invariant systems, the window observer can be stabilized by an appropriate design under a very mild condition on the window functions, albeit for linear time-varying system, some regularity of the window functions is required to achieve observer designs with the asymptotic stability. The corresponding design methods are developed. An example is included to illustrate the possible applications
Topics in quaternion linear algebra
Rodman, Leiba
2014-01-01
Quaternions are a number system that has become increasingly useful for representing the rotations of objects in three-dimensional space and has important applications in theoretical and applied mathematics, physics, computer science, and engineering. This is the first book to provide a systematic, accessible, and self-contained exposition of quaternion linear algebra. It features previously unpublished research results with complete proofs and many open problems at various levels, as well as more than 200 exercises to facilitate use by students and instructors. Applications presented in the book include numerical ranges, invariant semidefinite subspaces, differential equations with symmetries, and matrix equations. Designed for researchers and students across a variety of disciplines, the book can be read by anyone with a background in linear algebra, rudimentary complex analysis, and some multivariable calculus. Instructors will find it useful as a complementary text for undergraduate linear algebra courses...
Towards the International Linear Collider
International Nuclear Information System (INIS)
Lopez-Fernandez, Ricardo
2006-01-01
The broad physics potential of e+e- linear colliders was recognized by the high energy physics community right after the end of LEP in 2000. In 2007, the Large Hadron Collider (LHC) now under construction at CERN will obtain its first collisions. The LHC, colliding protons with protons at 14 TeV, will discover a standard model Higgs boson over the full potential mass range, and should be sensitive to new physics into the several TeV range. The program for the Linear Collider (LC) will be set in the context of the discoveries made at the LHC. All the proposals for a Linear Collider will extend the discoveries and provide a wealth of measurements that are essential for giving deeper understanding of their meaning, and pointing the way to further evolution of particle physics in the future. For the mexican groups is the right time to join such an effort
Linear Synchronous Motor Repeatability Tests
International Nuclear Information System (INIS)
Ward, C.R.
2002-01-01
A cart system using linear synchronous motors was being considered for the Plutonium Immobilization Plant (PIP). One of the applications in the PIP was the movement of a stack of furnace trays, filled with the waste form (pucks) from a stacking/unstacking station to several bottom loaded furnaces. A system was ordered to perform this function in the PIP Ceramic Prototype Test Facility (CPTF). This system was installed and started up in SRTC prior to being installed in the CPTF. The PIP was suspended and then canceled after the linear synchronous motor system was started up. This system was used to determine repeatability of a linear synchronous motor cart system for the Modern Pit Facility
Linearly polarized photons at ELSA
Energy Technology Data Exchange (ETDEWEB)
Eberhardt, Holger [Physikalisches Institut, Universitaet Bonn (Germany)
2009-07-01
To investigate the nucleon resonance regime in meson photoproduction, double polarization experiments are currently performed at the electron accelerator ELSA in Bonn. The experiments make use of a polarized target and circularly or linearly polarized photon beams. Linearly polarized photons are produced by coherent bremsstrahlung from an accurately aligned diamond crystal. The orientation of the crystal with respect to the electron beam is measured using the Stonehenge-Technique. Both, the energy of maximum polarization and the plane of polarization, can be deliberately chosen for the experiment. The linearly polarized beam provides the basis for the measurement of azimuthal beam asymmetries, such as {sigma} (unpolarized target) and G (polarized target). These observables are extracted in various single and multiple meson photoproduction channels.
Linear programming foundations and extensions
Vanderbei, Robert J
2001-01-01
Linear Programming: Foundations and Extensions is an introduction to the field of optimization. The book emphasizes constrained optimization, beginning with a substantial treatment of linear programming, and proceeding to convex analysis, network flows, integer programming, quadratic programming, and convex optimization. The book is carefully written. Specific examples and concrete algorithms precede more abstract topics. Topics are clearly developed with a large number of numerical examples worked out in detail. Moreover, Linear Programming: Foundations and Extensions underscores the purpose of optimization: to solve practical problems on a computer. Accordingly, the book is coordinated with free efficient C programs that implement the major algorithms studied: -The two-phase simplex method; -The primal-dual simplex method; -The path-following interior-point method; -The homogeneous self-dual methods. In addition, there are online JAVA applets that illustrate various pivot rules and variants of the simplex m...
Uniqueness theorems in linear elasticity
Knops, Robin John
1971-01-01
The classical result for uniqueness in elasticity theory is due to Kirchhoff. It states that the standard mixed boundary value problem for a homogeneous isotropic linear elastic material in equilibrium and occupying a bounded three-dimensional region of space possesses at most one solution in the classical sense, provided the Lame and shear moduli, A and J1 respectively, obey the inequalities (3 A + 2 J1) > 0 and J1>O. In linear elastodynamics the analogous result, due to Neumann, is that the initial-mixed boundary value problem possesses at most one solution provided the elastic moduli satisfy the same set of inequalities as in Kirchhoffs theorem. Most standard textbooks on the linear theory of elasticity mention only these two classical criteria for uniqueness and neglect altogether the abundant literature which has appeared since the original publications of Kirchhoff. To remedy this deficiency it seems appropriate to attempt a coherent description ofthe various contributions made to the study of uniquenes...
Bayes linear statistics, theory & methods
Goldstein, Michael
2007-01-01
Bayesian methods combine information available from data with any prior information available from expert knowledge. The Bayes linear approach follows this path, offering a quantitative structure for expressing beliefs, and systematic methods for adjusting these beliefs, given observational data. The methodology differs from the full Bayesian methodology in that it establishes simpler approaches to belief specification and analysis based around expectation judgements. Bayes Linear Statistics presents an authoritative account of this approach, explaining the foundations, theory, methodology, and practicalities of this important field. The text provides a thorough coverage of Bayes linear analysis, from the development of the basic language to the collection of algebraic results needed for efficient implementation, with detailed practical examples. The book covers:The importance of partial prior specifications for complex problems where it is difficult to supply a meaningful full prior probability specification...
Scalar-tensor linear inflation
Energy Technology Data Exchange (ETDEWEB)
Artymowski, Michał [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Racioppi, Antonio, E-mail: Michal.Artymowski@uj.edu.pl, E-mail: Antonio.Racioppi@kbfi.ee [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia)
2017-04-01
We investigate two approaches to non-minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for a non-minimal coupling to gravity of the form of f (φ) R /2; b) the particle physics approach, where we motivate the form of the Jordan frame potential by loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced gravity inflationary scenario, but instead of the Starobinsky attractor they lead to linear inflation in the strong coupling limit.
An Offline Formulation of MPC for LPV Systems Using Linear Matrix Inequalities
Directory of Open Access Journals (Sweden)
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.
Permafrost Hazards and Linear Infrastructure
Stanilovskaya, Julia; Sergeev, Dmitry
2014-05-01
The international experience of linear infrastructure planning, construction and exploitation in permafrost zone is being directly tied to the permafrost hazard assessment. That procedure should also consider the factors of climate impact and infrastructure protection. The current global climate change hotspots are currently polar and mountain areas. Temperature rise, precipitation and land ice conditions change, early springs occur more often. The big linear infrastructure objects cross the territories with different permafrost conditions which are sensitive to the changes in air temperature, hydrology, and snow accumulation which are connected to climatic dynamics. One of the most extensive linear structures built on permafrost worldwide are Trans Alaskan Pipeline (USA), Alaska Highway (Canada), Qinghai-Xizang Railway (China) and Eastern Siberia - Pacific Ocean Oil Pipeline (Russia). Those are currently being influenced by the regional climate change and permafrost impact which may act differently from place to place. Thermokarst is deemed to be the most dangerous process for linear engineering structures. Its formation and development depend on the linear structure type: road or pipeline, elevated or buried one. Zonal climate and geocryological conditions are also of the determining importance here. All the projects are of the different age and some of them were implemented under different climatic conditions. The effects of permafrost thawing have been recorded every year since then. The exploration and transportation companies from different countries maintain the linear infrastructure from permafrost degradation in different ways. The highways in Alaska are in a good condition due to governmental expenses on annual reconstructions. The Chara-China Railroad in Russia is under non-standard condition due to intensive permafrost response. Standards for engineering and construction should be reviewed and updated to account for permafrost hazards caused by the
A Linear Electromagnetic Piston Pump
Hogan, Paul H.
Advancements in mobile hydraulics for human-scale applications have increased demand for a compact hydraulic power supply. Conventional designs couple a rotating electric motor to a hydraulic pump, which increases the package volume and requires several energy conversions. This thesis investigates the use of a free piston as the moving element in a linear motor to eliminate multiple energy conversions and decrease the overall package volume. A coupled model used a quasi-static magnetic equivalent circuit to calculate the motor inductance and the electromagnetic force acting on the piston. The force was an input to a time domain model to evaluate the mechanical and pressure dynamics. The magnetic circuit model was validated with finite element analysis and an experimental prototype linear motor. The coupled model was optimized using a multi-objective genetic algorithm to explore the parameter space and maximize power density and efficiency. An experimental prototype linear pump coupled pistons to an off-the-shelf linear motor to validate the mechanical and pressure dynamics models. The magnetic circuit force calculation agreed within 3% of finite element analysis, and within 8% of experimental data from the unoptimized prototype linear motor. The optimized motor geometry also had good agreement with FEA; at zero piston displacement, the magnetic circuit calculates optimized motor force within 10% of FEA in less than 1/1000 the computational time. This makes it well suited to genetic optimization algorithms. The mechanical model agrees very well with the experimental piston pump position data when tuned for additional unmodeled mechanical friction. Optimized results suggest that an improvement of 400% of the state of the art power density is attainable with as high as 85% net efficiency. This demonstrates that a linear electromagnetic piston pump has potential to serve as a more compact and efficient supply of fluid power for the human scale.
Sparse Linear Identifiable Multivariate Modeling
DEFF Research Database (Denmark)
Henao, Ricardo; Winther, Ole
2011-01-01
and bench-marked on artificial and real biological data sets. SLIM is closest in spirit to LiNGAM (Shimizu et al., 2006), but differs substantially in inference, Bayesian network structure learning and model comparison. Experimentally, SLIM performs equally well or better than LiNGAM with comparable......In this paper we consider sparse and identifiable linear latent variable (factor) and linear Bayesian network models for parsimonious analysis of multivariate data. We propose a computationally efficient method for joint parameter and model inference, and model comparison. It consists of a fully...
Quantized, piecewise linear filter network
DEFF Research Database (Denmark)
Sørensen, John Aasted
1993-01-01
A quantization based piecewise linear filter network is defined. A method for the training of this network based on local approximation in the input space is devised. The training is carried out by repeatedly alternating between vector quantization of the training set into quantization classes...... and equalization of the quantization classes linear filter mean square training errors. The equalization of the mean square training errors is carried out by adapting the boundaries between neighbor quantization classes such that the differences in mean square training errors are reduced...
Correct Linearization of Einstein's Equations
Directory of Open Access Journals (Sweden)
Rabounski D.
2006-06-01
Full Text Available Regularly Einstein's equations can be reduced to a wave form (linearly dependent from the second derivatives of the space metric in the absence of gravitation, the space rotation and Christoffel's symbols. As shown here, the origin of the problem is that one uses the general covariant theory of measurement. Here the wave form of Einstein's equations is obtained in the terms of Zelmanov's chronometric invariants (physically observable projections on the observer's time line and spatial section. The obtained equations depend on solely the second derivatives even if gravitation, the space rotation and Christoffel's symbols. The correct linearization proves: the Einstein equations are completely compatible with weak waves of the metric.
Basic linear partial differential equations
Treves, Francois
1975-01-01
Focusing on the archetypes of linear partial differential equations, this text for upper-level undergraduates and graduate students features most of the basic classical results. The methods, however, are decidedly nontraditional: in practically every instance, they tend toward a high level of abstraction. This approach recalls classical material to contemporary analysts in a language they can understand, as well as exploiting the field's wealth of examples as an introduction to modern theories.The four-part treatment covers the basic examples of linear partial differential equations and their
Introduction to computational linear algebra
Nassif, Nabil; Erhel, Jocelyne
2015-01-01
Introduction to Computational Linear Algebra introduces the reader with a background in basic mathematics and computer programming to the fundamentals of dense and sparse matrix computations with illustrating examples. The textbook is a synthesis of conceptual and practical topics in ""Matrix Computations."" The book's learning outcomes are twofold: to understand state-of-the-art computational tools to solve matrix computations problems (BLAS primitives, MATLAB® programming) as well as essential mathematical concepts needed to master the topics of numerical linear algebra. It is suitable for s
Linear feedback controls the essentials
Haidekker, Mark A
2013-01-01
The design of control systems is at the very core of engineering. Feedback controls are ubiquitous, ranging from simple room thermostats to airplane engine control. Helping to make sense of this wide-ranging field, this book provides a new approach by keeping a tight focus on the essentials with a limited, yet consistent set of examples. Analysis and design methods are explained in terms of theory and practice. The book covers classical, linear feedback controls, and linear approximations are used when needed. In parallel, the book covers time-discrete (digital) control systems and juxtapos
Passive longitudinal phase space linearizer
Directory of Open Access Journals (Sweden)
P. Craievich
2010-03-01
Full Text Available We report on the possibility to passively linearize the bunch compression process in electron linacs for the next generation x-ray free electron lasers. This can be done by using the monopole wakefields in a dielectric-lined waveguide. The optimum longitudinal voltage loss over the length of the bunch is calculated in order to compensate both the second-order rf time curvature and the second-order momentum compaction terms. Thus, the longitudinal phase space after the compression process is linearized up to a fourth-order term introduced by the convolution between the bunch and the monopole wake function.
Generalized, Linear, and Mixed Models
McCulloch, Charles E; Neuhaus, John M
2011-01-01
An accessible and self-contained introduction to statistical models-now in a modernized new editionGeneralized, Linear, and Mixed Models, Second Edition provides an up-to-date treatment of the essential techniques for developing and applying a wide variety of statistical models. The book presents thorough and unified coverage of the theory behind generalized, linear, and mixed models and highlights their similarities and differences in various construction, application, and computational aspects.A clear introduction to the basic ideas of fixed effects models, random effects models, and mixed m
Emittance control in linear colliders
International Nuclear Information System (INIS)
Ruth, R.D.
1991-01-01
Before completing a realistic design of a next-generation linear collider, the authors must first learn the lessons taught by the first generation, the SLC. Given that, they must make designs fault tolerant by including correction and compensation in the basic design. They must also try to eliminate these faults by improved alignment and stability of components. When these two efforts cross, they have a realistic design. The techniques of generation and control of emittance reviewed here provide a foundation for a design which can obtain the necessary luminosity in a next-generation linear collider
Linear contextual modal type theory
DEFF Research Database (Denmark)
Schack-Nielsen, Anders; Schürmann, Carsten
Abstract. When one implements a logical framework based on linear type theory, for example the Celf system [?], one is immediately con- fronted with questions about their equational theory and how to deal with logic variables. In this paper, we propose linear contextual modal type theory that gives...... a mathematical account of the nature of logic variables. Our type theory is conservative over intuitionistic contextual modal type theory proposed by Nanevski, Pfenning, and Pientka. Our main contributions include a mechanically checked proof of soundness and a working implementation....
Adolescents' experience of complex persistent pain.
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
Trustworthy persistent identifier systems of the future
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
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.
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.
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....
Factors associated with persistent airflow limitation in severe asthma
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
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 ...
Vanilla Technicolor at Linear Colliders
DEFF Research Database (Denmark)
T. Frandsen, Mads; Jarvinen, Matti; Sannino, Francesco
2011-01-01
We analyze the reach of Linear Colliders (LC)s for models of dynamical electroweak symmetry breaking. We show that LCs can efficiently test the compositeness scale, identified with the mass of the new spin-one resonances, till the maximum energy in the center-of-mass of the colliding leptons. In ...
Variational linear algebraic equations method
International Nuclear Information System (INIS)
Moiseiwitsch, B.L.
1982-01-01
A modification of the linear algebraic equations method is described which ensures a variational bound on the phaseshifts for potentials having a definite sign at all points. The method is illustrated by the elastic scattering of s-wave electrons by the static field of atomic hydrogen. (author)
Feedback Systems for Linear Colliders
International Nuclear Information System (INIS)
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies
Aspects of robust linear regression
Davies, P.L.
1993-01-01
Section 1 of the paper contains a general discussion of robustness. In Section 2 the influence function of the Hampel-Rousseeuw least median of squares estimator is derived. Linearly invariant weak metrics are constructed in Section 3. It is shown in Section 4 that $S$-estimators satisfy an exact
Periodic linear differential stochastic processes
Kwakernaak, H.
1975-01-01
Periodic linear differential processes are defined and their properties are analyzed. Equivalent representations are discussed, and the solutions of related optimal estimation problems are given. An extension is presented of Kailath and Geesey’s [1] results concerning the innovations representation
Linear colliders for photon collisions
International Nuclear Information System (INIS)
Anon.
1994-01-01
The enthusiasm of the first international workshop on photonphoton colliders and associated physics, held at the Lawrence Berkeley Laboratory from 28 March - 1 April, could have set a ball rolling. According to proponents of this physics, the particle physics one can study with a high energy linear collider is special and complements that of a hadron supercollider
Saturation and linear transport equation
International Nuclear Information System (INIS)
Kutak, K.
2009-03-01
We show that the GBW saturation model provides an exact solution to the one dimensional linear transport equation. We also show that it is motivated by the BK equation considered in the saturated regime when the diffusion and the splitting term in the diffusive approximation are balanced by the nonlinear term. (orig.)
Parameterized Linear Longitudinal Airship Model
Kulczycki, Eric; Elfes, Alberto; Bayard, David; Quadrelli, Marco; Johnson, Joseph
2010-01-01
A parameterized linear mathematical model of the longitudinal dynamics of an airship is undergoing development. This model is intended to be used in designing control systems for future airships that would operate in the atmospheres of Earth and remote planets. Heretofore, the development of linearized models of the longitudinal dynamics of airships has been costly in that it has been necessary to perform extensive flight testing and to use system-identification techniques to construct models that fit the flight-test data. The present model is a generic one that can be relatively easily specialized to approximate the dynamics of specific airships at specific operating points, without need for further system identification, and with significantly less flight testing. The approach taken in the present development is to merge the linearized dynamical equations of an airship with techniques for estimation of aircraft stability derivatives, and to thereby make it possible to construct a linearized dynamical model of the longitudinal dynamics of a specific airship from geometric and aerodynamic data pertaining to that airship. (It is also planned to develop a model of the lateral dynamics by use of the same methods.) All of the aerodynamic data needed to construct the model of a specific airship can be obtained from wind-tunnel testing and computational fluid dynamics
Linear Methods for Image Interpolation
Directory of Open Access Journals (Sweden)
Pascal Getreuer
2011-09-01
Full Text Available We discuss linear methods for interpolation, including nearest neighbor, bilinear, bicubic, splines, and sinc interpolation. We focus on separable interpolation, so most of what is said applies to one-dimensional interpolation as well as N-dimensional separable interpolation.
Directivity of basic linear arrays
DEFF Research Database (Denmark)
Bach, Henning
1970-01-01
For a linear uniform array ofnelements, an expression is derived for the directivity as a function of the spacing and the phase constants. The cases of isotropic elements, collinear short dipoles, and parallel short dipoles are included. The formula obtained is discussed in some detail and contour...
Data Compression with Linear Algebra
Etler, David
2015-01-01
A presentation on the applications of linear algebra to image compression. Covers entropy, the discrete cosine transform, thresholding, quantization, and examples of images compressed with DCT. Given in Spring 2015 at Ocean County College as part of the honors program.
175 Years of Linear Programming
Indian Academy of Sciences (India)
polynomial-time solvability of linear programming, that is, testing if a polyhedron Q E ~ ... Q is rational, i.e. all extreme points and rays of Q are ra- tional vectors or ..... rithrll terminates with an interior solution, a post-processing step is usually ...
175 Years of Linear Programming
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. 175 Years of Linear Programming - Max Flow = Min Cut. Vijay Chandru M R Rao. Series Article Volume 4 Issue 10 October 1999 pp 22-39. Fulltext. Click here to view fulltext PDF. Permanent link:
Linear collider systems and costs
International Nuclear Information System (INIS)
Loew, G.A.
1993-05-01
The purpose of this paper is to examine some of the systems and sub-systems involved in so-called ''conventional'' e + e - linear colliders and to study how their design affects the overall cost of these machines. There are presently a total of at least six 500 GeV c. of m. linear collider projects under study in the world. Aside from TESLA (superconducting linac at 1.3 GHz) and CLIC (two-beam accelerator with main linac at 30GHz), the other four proposed e + e - linear colliders can be considered ''conventional'' in that their main linacs use the proven technique of driving room temperature accelerator sections with pulsed klystrons and modulators. The centrally distinguishing feature between these projects is their main linac rf frequency: 3 GHz for the DESY machine, 11.424 GHz for the SLAC and JLC machines, and 14 GHz for the VLEPP machine. The other systems, namely the electron and positron sources, preaccelerators, compressors, damping rings and final foci, are fairly similar from project to project. Probably more than 80% of the cost of these linear colliders will be incurred in the two main linacs facing each other and it is therefore in their design and construction that major savings or extra costs may be found
Linear accelerators of the future
International Nuclear Information System (INIS)
Loew, G.A.
1986-07-01
Some of the requirements imposed on future linear accelerators to be used in electron-positron colliders are reviewed, as well as some approaches presently being examined for meeting those requirements. RF sources for use in these linacs are described, as well as wakefields, single bunches, and multiple-bunch trains
175 Years of Linear Programming
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 5. 175 Years of Linear Programming - Pune's Gift. Vijay Chandru M R Rao. Series Article Volume 4 Issue 5 May ... Computer Science and Automation, IISc Bangalore 560012, India. Director, Indian Institute of Management, Bannerghatta Road, ...
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.
Spaces of Piecewise Linear Manifolds
DEFF Research Database (Denmark)
Gomez Lopez, Mauricio Esteban
Abstract In this thesis we introduce Δ-set ψPLd(RN) which we regard as the piecewise linear analogue of the space ψd(RN) of smooth d-dimensional submanifoldsin RN introduced by Galatius in [4]. Using ψPLd(RN) we define a bi-Δ-set Cd(RN)•,• ( whose geometric realization BCPLd(RN) = llCd(RN)•,•ll ......Abstract In this thesis we introduce Δ-set ψPLd(RN) which we regard as the piecewise linear analogue of the space ψd(RN) of smooth d-dimensional submanifoldsin RN introduced by Galatius in [4]. Using ψPLd(RN) we define a bi-Δ-set Cd(RN)•,• ( whose geometric realization BCPLd(RN) = ll...... BCPLd (RN) ≅ ΩN–1lψPLd (RN)•l when N — d ≥ 3. The proof of the main theorem relies on properties of ψPLd (RN) • which arise from the fact that this Δ-set can be obtained from a more general contravariant functor PL op → Sets defined on the category of finite dimensional polyhedraand piecewise linear...... maps, and on a fiberwise transversality result for piecewise linear submersions whose fibers are contained in R × (-1,1)N-1 ⊆ RN . For the proof of this transversality result we use a theorem of Hudson on extensions of piecewise linear isotopies which is why we need to include the condition N — d ≥ 3...
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....