Sample records for temperature correction factor

  1. An experimental and computational investigation of the standard temperature-pressure correction factor for ion chambers in kilovoltage x rays

    Microsoft Academic Search

    D. W. O. Rogers; Malcolm McEwen; Daniel J. La Russa

    2007-01-01

    For ion chambers with cavities open to the surrounding atmosphere, the response measured at a given temperature and pressure must be corrected using the standard temperature-pressure correction factor (P{sub TP}). A previous paper based solely on Monte Carlo simulations [D. J. La Russa and D. W. O. Rogers, Med. Phys. 33, 4590-4599 (2006)] pointed out the shortcomings of the P{sub

  2. Optimizing Power Factor Correction

    E-print Network

    Phillips, R. K.; Burmeister, L. C.

    OPTIMIZING POWER FACTOR CORRECTION Robert K. Phillips and Louis C. Burmeister, Mechanical Engineering, University of Kansas, Lawrence, KS The optimal investment for power factor correcting capacitors for Kansas Power and Light Company large... that varles from utility to utility and even between different rate schedules of the same utility. Two examples show the difference between utilities. The Kansas City Power and Light Company "General Service Large" Rate Schedule l-GL provides no penalty...

  3. Determining the temporal variability in atmospheric temperature profiles measured using radiosondes and assessment of correction factors for different launch schedules

    NASA Astrophysics Data System (ADS)

    Butterfield, D.; Gardiner, T.

    2015-01-01

    Radiosondes provide one of the primary sources of upper troposphere and stratosphere temperature data for numerical weather prediction, the assessment of long-term trends in atmospheric temperature, study of atmospheric processes and provide intercomparison data for other temperature sensors, e.g. satellites. When intercomparing different temperature profiles it is important to include the effect of temporal mismatch between the measurements. To help quantify this uncertainty the atmospheric temperature variation through the day needs to be assessed, so that a correction and uncertainty for time difference can be calculated. Temperature data from an intensive radiosonde campaign, at Manus Island in Papua New Guinea, were analysed to calculate the hourly rate of change in temperature at different altitudes and provide recommendations and correction factors for different launch schedules. Using these results, three additional longer term data sets were analysed (Lindenberg 1999 to 2008; Lindenberg 2009 to 2012; and Southern Great Plains 2006 to 2012) to assess the diurnal variability of temperature as a function of altitude, time of day and season of the year. This provides the appropriate estimation of temperature differences for given temporal separation and the uncertainty associated with them. A general observation was that 10 or more repeat measurements would be required to get a standard error of the mean of less than 0.1 K per hour of temporal mismatch.

  4. An experimental and computational investigation of the standard temperature-pressure correction factor for ion chambers in kilovoltage x rays

    SciTech Connect

    La Russa, Daniel J.; McEwen, Malcolm; Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Ottawa Carleton Institute of Physics, Carleton University, Ottawa, ON K1S 5B6 (Canada); Ionizing Radiation Standards, National Research Council of Canada, M-35 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Carleton Laboratory for Radiotherapy Physics, Ottawa Carleton Institute of Physics, Carleton University, Ottawa, ON K1S 5B6 (Canada)

    2007-12-15

    For ion chambers with cavities open to the surrounding atmosphere, the response measured at a given temperature and pressure must be corrected using the standard temperature-pressure correction factor (P{sub TP}). A previous paper based solely on Monte Carlo simulations [D. J. La Russa and D. W. O. Rogers, Med. Phys. 33, 4590-4599 (2006)] pointed out the shortcomings of the P{sub TP} correction factor when used to correct the response of non-air-equivalent chambers for low-energy x-ray beams. This work presents the results of several experiments that corroborate these calculations for a number of ion chambers. Monte Carlo simulations of the experimental setup revealed additional insight into the various factors affecting the extent of the breakdown of P{sub TP}, including the effect of impurities and the sensitivity to chamber dimensions. For an unfiltered 60 kV beam, the P{sub TP}-corrected response of an NE 2571 ion chamber measured at 0.7 atm was 2.5% below the response measured at reference conditions. In general, Monte Carlo simulations of the experimental setup using EGSnrc were within 0.5% of measured values. EGSnrc-calculated values of air kerma calibration coefficients (N{sub K}) at low x-ray energies are also provided as a means of estimating the level of impurities in the chambers investigated. Calculated values of N{sub K} normalized to the value measured for a 250 kV beam were obtained for three chambers and were within 1% of experiment with one exception, the Exradin A12 in a 50 kV beam.

  5. An experimental and computational investigation of the standard temperature-pressure correction factor for ion chambers in kilovoltage x rays.

    PubMed

    La Russa, Daniel J; McEwen, Malcolm; Rogers, D W O

    2007-12-01

    For ion chambers with cavities open to the surrounding atmosphere, the response measured at a given temperature and pressure must be corrected using the standard temperature-pressure correction factor (P(TP)). A previous paper based solely on Monte Carlo simulations [D. J. La Russa and D. W. O. Rogers, Med. Phys. 33, 4590-4599 (2006)] pointed out the shortcomings of the P(TP) correction factor when used to correct the response of non-air-equivalent chambers for low-energy x-ray beams. This work presents the results of several experiments that corroborate these calculations for a number of ion chambers. Monte Carlo simulations of the experimental setup revealed additional insight into the various factors affecting the extent of the breakdown of P(TP), including the effect of impurities and the sensitivity to chamber dimensions. For an unfiltered 60 kV beam, the P(TP)-corrected response of an NE 2571 ion chamber measured at 0.7 atm was 2.5% below the response measured at reference conditions. In general, Monte Carlo simulations of the experimental setup using EGSnrc were within 0.5% of measured values. EGSnrc-calculated values of air kerma calibration coefficients (N(K)) at low x-ray energies are also provided as a means of estimating the level of impurities in the chambers investigated. Calculated values of N(K) normalized to the value measured for a 250 kV beam were obtained for three chambers and were within 1% of experiment with one exception, the Exradin A12 in a 50 kV beam. PMID:18196796

  6. Optimal power factor correction

    SciTech Connect

    Mostafa, M. (Electrical and Computer Engineering Dept., College of Engineering and Petroleum, Kuwait Univ. (KW))

    1988-08-01

    This paper discusses the different parameters affecting the economic feasibility of power factor correction. It will be shown that the specific costs of the transmission and compensation elements as well as those of the electric energy and power losses have a decisive influence on the achievable overall saving. After formulating an objective function representing this overall saving, taking also the load factor into account an analytical approach to the determination of the optimal size of the compensation equipment is presented. A generalized chart is given which enables the designer to know whether the power factor correction is feasible or not under any circumstances. Also, the most suitable degree of reactive power compensation can be directly found. The results obtained from a digital program are also given to indicate the sensitivity of the optimal compensation factor to changes in system parameters such as the specific energy loss cost and the annual rate of interest and depreciation. Moreover, the good agreement of the results of the digital computation with those determined using the suggested simple generalized chart, could be realized.

  7. Theoretical full power correction factors as related to changes in ambient temperature, pressure and absolute humidity for aircraft turbine engines 

    E-print Network

    Raphael, Michel Antoun

    1969-01-01

    for any process. Applying equation 3. 5 to each one of the state points characterizing the Brayton cycle we get: Ahl hl hA 2=h ? h 2 B Ah =h ? h Ah =h ? h 4 4 where we also have: dh = 6h = c dT Jn thus, 28 Ah 1 c dT P Ah 2 c dT P Ah 3 c dT P... we get Ah 1 r A p A c dT + (1 ? gTivdp Tl P p At the compressor inlet section we assume constant temperature, therefore, Ahl A (1 ? gT)vdp (3. 9) where r A c dT = 0 since Tl P T 1 TA At state point 2 we have T Ah = cdT+ 2 j p r p...

  8. QED radiative corrections to impact factors

    E-print Network

    E. A. Kuraev; L. N. Lipatov; T. V. Shishkina

    2000-09-12

    We consider the radiative corrections to the impact factors of electron and photon. According to a generalized eikonal representation the e\\bar e scattering amplitude at high energies and fixed momentum transfers is proportional to the electron form factor. But we show that this representation is violated due to the presence of non-planar diagrams. One loop correction to the photon impact factor for small virtualities of the exchanged photon is obtained using the known results for the cross section of the e\\bar e production at photon-nuclei interactions.

  9. NLO corrections to the photon impact factor

    E-print Network

    Stefan Gieseke

    2002-08-15

    We review the program of the calculation of next-to-leading order corrections to the virtual photon impact factor. Following a brief introduction we present some technical aspects for the various contributions. Recently obtained results for transversely polarised virtual photons are discussed and an outline of how infrared divergences are cancelled is given. Implications of the subtraction of leading energy logarithms are discussed.

  10. Correction of SiPM temperature dependencies

    NASA Astrophysics Data System (ADS)

    Kaplan, A.; Calice Collaboration

    2009-10-01

    The performance of a high granular analogue hadronic calorimeter (AHCAL) using scintillator tiles with built-in Silicon Photomultiplier (SiPM) readout is reported. A muon beam is used for the minimum ionizing particle (MIP) based calibration of the single cells. The calibration chain including corrections for the non-linearity of the SiPM is presented. The voltage and temperature dependencies of the SiPM signal have been investigated using the versatile LED system of the AHCAL. Monitoring and correction methods are discussed. Measurements from the operation 2006 and 2007 at the CERN SPS test beam and data provided by the Institute for Theoretical and Experimental Physics (ITEP) in Moscow are compared.

  11. A temperature correction method for expanding atmospheres

    NASA Astrophysics Data System (ADS)

    Hamann, W.-R.; Gräfener, G.

    2003-11-01

    Model atmospheres form the basis for the interpretation of stellar spectra. A major problem in those model calculations is to establish the temperature stratification from the condition of radiative equilibrium. Dealing with non-LTE models for spherically expanding atmospheres of Wolf-Rayet stars, we developed a new temperature correction method. Its basic idea dates back to 1955 when it was proposed by Unsöld for grey, static and plane-parallel atmospheres in LTE. The equations were later generalized to the non-grey case by Lucy. In the present paper we furthermore drop the Eddington approximation, proceed to spherical geometry and allow for expansion of the atmosphere. Finally the concept of an ``approximate lambda operator'' is employed to speed up the convergence. Tests for Wolf-Rayet type models demonstrate that the method works fine even in situations of strong non-LTE.

  12. Development of a Pressure Sensitive Paint System with Correction for Temperature Variation

    NASA Technical Reports Server (NTRS)

    Simmons, Kantis A.

    1995-01-01

    Pressure Sensitive Paint (PSP) is known to provide a global image of pressure over a model surface. However, improvements in its accuracy and reliability are needed. Several factors contribute to the inaccuracy of PSP. One major factor is that luminescence is temperature dependent. To correct the luminescence of the pressure sensing component for changes in temperature, a temperature sensitive luminophore incorporated in the paint allows the user to measure both pressure and temperature simultaneously on the surface of a model. Magnesium Octaethylporphine (MgOEP) was used as a temperature sensing luminophore, with the pressure sensing luminophore, Platinum Octaethylporphine (PtOEP), to correct for temperature variations in model surface pressure measurements.

  13. Comparing capacitive and LC compensators for power factor correction

    Microsoft Academic Search

    M. M. Abdel Azu; E. E. Abou Elzahab; A. M. Ibrahim; A. F. Zobaa

    2002-01-01

    A method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor and maximizes the efficiency. The performance

  14. Fermilab's Booster Correction Element Power Supply Silicon Temperature Rise

    SciTech Connect

    Krafczyk, G.; Jensen, C.; Pfeffer, H.; Warchol, G.; /Fermilab

    2009-05-01

    Fermilab is in the process of upgrading its Booster Correction Element System to include full field correction element magnets to correct position and chromaticity throughout the booster cycle. For good reliability of the switchmode power supplies designed to power the magnets, it is important to limit both the maximum temperature and the repetitive temperature cycling of the silicon junctions of the switching elements. We will describe how we measured these parameters and the results of our measurements.

  15. NLO Corrections to the Photon Impact Factor: Combining Real and Virtual Corrections

    E-print Network

    J. Bartels; D. Colferai; S. Gieseke; A. Kyrieleis

    2002-08-30

    In this third part of our calculation of the QCD NLO corrections to the photon impact factor we combine our previous results for the real corrections with the singular pieces of the virtual corrections and present finite analytic expressions for the quark-antiquark-gluon intermediate state inside the photon impact factor. We begin with a list of the infrared singular pieces of the virtual correction, obtained in the first step of our program. We then list the complete results for the real corrections (longitudinal and transverse photon polarization). In the next step we define, for the real corrections, the collinear and soft singular regions and calculate their contributions to the impact factor. We then subtract the contribution due to the central region. Finally, we combine the real corrections with the singular pieces of the virtual corrections and obtain our finite results.

  16. Temperature correction of PSP measurement using dual-luminophor coating

    Microsoft Academic Search

    K. Mitsuo; K. Asai; M. Hayasaka; M. Kameda

    2003-01-01

    We developed a dual-luminophor pressure\\/temperature sensitive paint (DPTSP) to correct the temperature dependence of pressure-sensitive\\u000a paint. The DPTSP is composed of two sensor molecules, PtTFPP and Rhodamine B (RhB), and Poly-IBM-co-TFEM as a binder. Temperature\\u000a was determined from the image of RhB, and the temperature dependence of PtTFPP was corrected using the calculated temperature.\\u000a To validate the capability of DPTSP

  17. Spectral and temperature correction of silicon photovoltaic solar radiation detectors

    Microsoft Academic Search

    J. J. Michalsky; R. Perez; L. Harrison; B. A. LeBaron

    1991-01-01

    Silicon photovoltaic sensors are an inexpensive alternative to standard thermopile sensors for the measurement of solar radiation. However, their temperature and spectral response render them less accurate for global horizontal irradiance and unsuitable for direct beam and diffuse horizontal irradiance unless they can be reliably corrected. A correction procedure for the rotating shadowband radiometer, which measures all three components, based

  18. Corrected Hawking Temperature in Snyder's Quantized Space-time

    NASA Astrophysics Data System (ADS)

    Ma, Meng-Sen; Liu, Fang; Zhao, Ren

    2015-06-01

    In the quantized space-time of Snyder, generalized uncertainty relation and commutativity are both included. In this paper we analyze the possible form for the corrected Hawking temperature and derive it from the both effects. It is shown that the corrected Hawking temperature has a form similar to the one of noncommutative geometry inspired Schwarzschild black hole, however with an requirement for the noncommutative parameter 𝜃 and the minimal length a.

  19. Neural networks to predict exosphere temperature corrections

    NASA Astrophysics Data System (ADS)

    Choury, Anna; Bruinsma, Sean; Schaeffer, Philippe

    2013-10-01

    Precise orbit prediction requires a forecast of the atmospheric drag force with a high degree of accuracy. Artificial neural networks are universal approximators derived from artificial intelligence and are widely used for prediction. This paper presents a method of artificial neural networking for prediction of the thermosphere density by forecasting exospheric temperature, which will be used by the semiempirical thermosphere Drag Temperature Model (DTM) currently developed. Artificial neural network has shown to be an effective and robust forecasting model for temperature prediction. The proposed model can be used for any mission from which temperature can be deduced accurately, i.e., it does not require specific training. Although the primary goal of the study was to create a model for 1 day ahead forecast, the proposed architecture has been generalized to 2 and 3 days prediction as well. The impact of artificial neural network predictions has been quantified for the low-orbiting satellite Gravity Field and Steady-State Ocean Circulation Explorer in 2011, and an order of magnitude smaller orbit errors were found when compared with orbits propagated using the thermosphere model DTM2009.

  20. Corrections to Observed Rocketsonde and Balloonsonde Temperatures

    Microsoft Academic Search

    Harold N. Ballard; Roberto Rubio

    1968-01-01

    Atmospheric temperature sensing elements studied in this report are presently being used at Meteorological Rocket Network stations. The steady-state solution to the heat transfer equation is given for a thermistor which is attached to an instrument package by some type of mounting configuration, the instrument in turn being supported by a parachute. The solution includes the effects of aerodynamic heating

  1. Application of bottom-hole temperature corrections in geothermal studies

    SciTech Connect

    Deming, D. (Dept. of Geology and Geophysics, Louisiana State Univ., Baton Rouge, LA (US))

    1989-01-01

    Bottom-hole temperature (BHT) data measured in oil and gas wells constitute a large, low-quality set of temperature observations commonly used in geothermal studies. Raw BHT data are, on the average, cooler than true formation temperatures. To estimate true formation temperatures, corrections must be applied. Empirical BHT corrections may be applied to BHT data for which only depths of measurement are known, but may not be valid outside of the area for which they are calibrated. If multiple BHT measurements from successive logging runs are available, the Horner plot correction procedure can be used. The accuracy of the Horner plot is limited by simplifying assumptions made in its derivation, and by the common lack of information on parameters such as duration of mud circulation. More detailed and complete treatments provide insight into the borehole equilibration process, but their application is similarly limited by a common lack of data regarding borehole thermal properties. A new type of empirical correction procedure may be derived in some areas and allows a correction to be made for BHTs for which only a depth and time of measurement are known.

  2. Power Factor Correction Using Magnetic Energy Recovery Current Switches

    NASA Astrophysics Data System (ADS)

    Takaku, Taku; Isobe, Takanori; Narushima, Jun; Tsutsui, Hiroaki; Shimada, Ryuichi

    In this paper, we propose a Magnetic Energy Recovery Switch (MERS). The switch consists of four MOSFET elements and one capacitor. A power factor improvement is automatically possible regardless of the impedance and power frequency of the load by synchronized switching of MERS with a power supply. MERS itself generates voltage and compensates for the inductance voltage unlike a conventional series capacitor, so that another dc power supply is not needed. An experiment was carried out to demonstrate the automatic correction of the power factor. We can also expect energy saving of electromachies such as an electric motor by the power factor correction with MERS.

  3. Second-Order Corrections to QED Coupling at Low Temperature

    NASA Astrophysics Data System (ADS)

    Masood, Samina S.; Haseeb, Mahnaz

    We calculate the second-order corrections to vacuum polarization tensor of photons at low temperatures, i.e. T ? 1010 K (T ? me). The thermal contributions to the QED coupling constant are evaluated at temperatures below the electron mass that is T < me. Renormalization of QED at these temperatures has explicitly been checked. The electromagnetic properties of such a thermal medium are modified. Parameters like electric permittivity and magnetic permeability of such a medium are no more constant and become functions of temperature.

  4. Biotic attrition from tropical forests correcting for truncated temperature niches

    E-print Network

    Silman, Miles R.

    Biotic attrition from tropical forests correcting for truncated temperature niches K E N N E T H J to `biotic attrition,' or loss of local diversity, in areas where the number of species emigrating or going locally extinct exceeds the number immigrating. Biotic attrition is predicted be especially severe

  5. Correcting for focal-plane-array temperature dependence in

    E-print Network

    Shaw, Joseph A.

    : infrared imaging; radiometry; infrared systems; infrared detectors. Paper 121438SS received Oct. 2, 2012 in uncooled microbolom- eter detector arrays, which enable much smaller, lighter, and lower-cost infraredCorrecting for focal-plane-array temperature dependence in microbolometer infrared cameras lacking

  6. An EGSnrc investigation of correction factors for ion chamber dosimetry

    NASA Astrophysics Data System (ADS)

    Buckley, Lesley A.

    Radiation dosimetry is used to quantify the dose delivered during radiation therapy by using ionization chambers with several correction factors. Knowledge of these factors is needed at well below the 1% level in order to maintain the overall uncertainty on the reference dosimetry near 1-2%. The small magnitude of the corrections renders measurements very difficult. Monte Carlo calculations are widely used for this purpose, however they require very low statistical uncertainties. A new user-code, CSnrc, for the EGSnrc Monte Carlo system is described. CSnrc uses a correlated sampling variance reduction technique to reduce the uncertainty for dose ratio calculations. Compared to an existing EGSnrc user-code from which it was developed, CSnrc shows gains in efficiency of up to a factor of 64 and achieves much lower statistical uncertainties on correction factors than previously published. CSnrc is used to compute the central electrode correction factor, Pcel, in a broader range of beams than previously used and at the depths relevant to modern protocols. For photon beams, the CSnrc values compare well with the values used in dosimetry protocols whereas for electron beams, CSnrc shows up to a 0.2% correction for a graphite electrode, a correction currently ignored by dosimetry protocols. The difference from currently used values is slightly less for an aluminum electrode. CSnrc is also used to compute the wall correction factor, P wall. For cylindrical chambers in photon beams, the CSnrc calculations are compared to the currently used Almond-Svensson formalism and differ from this formalism by as much as 0.8%. The CSnrc values are used to explain some previously published experiments showing problems with Pwall . For electron beams, where dosimetry protocols assume a Pwall of unity, CSnrc calculations show a correction as large as 0.6%. For parallel-plate chambers, there is little information available regarding Pwall in photon beams. CSnrc shows corrections of over 2% for some chambers. In electron beams, Pwall has been assumed to be unity, despite previously published evidence suggesting otherwise. CSnrc shows that for some chambers at lower energies, Pwall is nearly 1.02.

  7. Filtering and Temperature Correction Algorithms for Smog Interference in Temperature Measurement Based on CCD Image Sensor

    Microsoft Academic Search

    Xiaoqi Peng; Yuan Sun

    2009-01-01

    The visible radiation would be absorbed and scattered by the smog diffusing around the radiator and on the path of the radiation, which distorts the results of temperature measurement by two-color thermometry based on CCD image sensor. In this paper, an approach for filtering smog interference of high-temperature radiator and correcting temperature is proposed. Firstly, by the image target recognition

  8. NLO Corrections to the ?* Impact Factor: First Numerical Results for the Real Corrections to ?*_L

    E-print Network

    J. Bartels; A. Kyrieleis

    2004-12-02

    We analytically perform the transverse momentum integrations in the real corrections to the longitudinal \\gamma*_L impact factor. The resulting integrals are Feynman parameter integrals, and we provide a MATHEMATICA file which contains the integrands. The remaining integrals are carried out numerically. We perform a numerical test, and we compute those parts of the impact factor which depend upon the energy scale s_0: they are found to be negative and, with decreasing values of s_0, their absolute value increases.

  9. Solar Correction Factors of Building Envelope in Tebei 

    E-print Network

    Wang, D.; Tang, M.

    2006-01-01

    Tebei has very rich solar energy in China and needs heating in winter,but the present energy building design code has no solar correction factor for the overall heat transfer coefficient of building envelope for Tebei. Based on the typical year...

  10. Solar Correction Factors of Building Envelope in Tebei

    E-print Network

    Wang, D.; Tang, M.

    2006-01-01

    Tebei has very rich solar energy in China and needs heating in winter,but the present energy building design code has no solar correction factor for the overall heat transfer coefficient of building envelope for Tebei. Based on the typical year...

  11. Status of the NLO Corrections to the Photon Impact Factor

    E-print Network

    Stefan Gieseke

    2002-06-20

    We present the status of the programme of calculating the next-to-leading order corrections to the virtual photon impact factor. In particular, we discuss new results for the transversely polarized photon. We briefly outline the definition of infrared finite terms and the subtraction of the leading logarithmic parts.

  12. A well-type ionization chamber geometric correction factor

    NASA Astrophysics Data System (ADS)

    Meiler, R. J.; Sibata, C. H.; Ho, A. K.; de Souza, C.; Shin, K. H.

    1996-07-01

    To correct for the influence of source configuration on the measured activity of spherical and cylindrical brachytherapy sources, a geometric correction factor was calculated for the Standard Imaging HDR-1000 well-type ionization chamber. A Fortran program modelled each source as a lattice of point sources. Because of the cylindrical symmetry of the well chamber, it could be uniquely modelled by point detectors along the perimeter of the radial plane of the detection volume. Path lengths were calculated and attenuation factors were applied to each source - detector point combination individually. The total dose rate at each detection point was found through a Sievert summation of the point source contributions. For sources with identical activities, a correction factor of was calculated, equal to the ratio of the dose rate of the cylindrical source to that of the sphere. Experimental verification using a Nuclear Associates 67-809 series cylindrical source and an Amersham spherical source yielded a correction factor of .

  13. Quantum Mechanical Corrections to Simulated Shock Hugoniot Temperatures

    SciTech Connect

    Goldman, N; Reed, E; Fried, L E

    2009-07-17

    The authors present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a grueneisen equation of state and a quasi-harmonic approximation to the vibrational energies, they derive a simple, post-processing method for calculation of the quantum corrected Hugoniot temperatures. They have used our novel technique on ab initio simulations of both shock compressed water and methane. Our results indicate significantly closer agreement with all available experimental temperature data for these two systems. Our formalism and technique can be easily applied to a number of different shock compressed molecular liquids or covalent solids, and has the potential to decrease the large uncertainties inherent in many experimental Hugoniot temperature measurements of these systems.

  14. Quantum mechanical corrections to simulated shock Hugoniot temperatures.

    PubMed

    Goldman, Nir; Reed, Evan J; Fried, Laurence E

    2009-11-28

    We present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a Gruneisen equation of state and a quasiharmonic approximation to the vibrational energies, we derive a simple, postprocessing method for calculation of the quantum corrected Hugoniot temperatures. We have used our novel technique on ab initio simulations of shock compressed water and methane. Our results indicate significantly closer agreement with all available experimental temperature data for these two systems. Our formalism can be easily applied to a number of different shock compressed molecular liquids or solids, and has the potential to decrease the large uncertainties inherent in many experimental Hugoniot temperature measurements of these systems. PMID:19947671

  15. Establishing local workplace field correction factors for neutron personal dosemeters.

    PubMed

    Vanhavere, Filip; Cauwels, Vanessa

    2014-10-01

    The present personal neutron dosemeters still need local correction factors to be able to provide accuracy comparable with photon dosemeters. Characterisation of the local neutron field is an indispensable part of neutron dosimetry to obtain such correction factors. It is often overlooked that besides characterisation in the neutron energy also the directional distribution of neutrons plays a crucial part in this characterisation. The authors have done such characterisation in the energy and angle for four workplace fields in Paks NPP. For this a relatively simple approximation method was used using the Nprobe for the energy distribution and measurements on the six sides of the slab phantom with personal dosemeters for the directional distribution. This allowed one to estimate a reference neutron Hp(10) rate and to compare it with the response of several neutron personal dosemeters. PMID:24962515

  16. Recent Developments in Single-Phase Power Factor Correction

    Microsoft Academic Search

    Zhonghui BingI; Min Chen; S. K. T. Miller; Y. Nishida; Jian Sun

    2007-01-01

    The development of single-phase power factor correction (PFC) technologies was traditionally driven by the need for computers, telecommunication, lighting, and other electronic devices and systems to meet harmonic current limits defined by IEC 61000-3-2 and other regulatory standards. Recently, several new applications have emerged as additional drivers for the development of the technologies. One such application is commercial transport airplanes

  17. Soft-switching single-stage power factor correction converter

    Microsoft Academic Search

    Khalid Rustom; Issa Batarseh

    2001-01-01

    A single-stage, ZVT-PWM, power factor correction converter is proposed in this paper. Zero-voltage switching for the main switch and zero-current switching for the auxiliary switch are realized by utilizing the leakage inductance of the output transformer and the capacitance of the switches. As a result, no additional resonant components need to be added. ZVS operation is realized for a wide

  18. An EGSnrc investigation of the P{sub TP} correction factor for ion chambers in kilovoltage x rays

    Microsoft Academic Search

    Daniel J. La Russa; D. W. O. Rogers

    2006-01-01

    As part of the standard practice for obtaining consistent ion chamber measurements with cavities open to the surrounding atmosphere, the raw measured response is corrected to the response at a reference temperature and pressure using the standard temperature-pressure correction factor (P{sub TP}). In this study, the EGSnrc Monte Carlo code was used to investigate the validity of the P{sub TP}

  19. Correction factors for gravimetric measurement of peritumoural oedema in man.

    PubMed

    Bell, B A; Smith, M A; Tocher, J L; Miller, J D

    1987-01-01

    The water content of samples of normal and oedematous brain in lobectomy specimens from 16 patients with cerebral tumours has been measured by gravimetry and by wet and dry weighing. Uncorrected gravimetry underestimated the water content of oedematous peritumoural cortex by a mean of 1.17%, and of oedematous peritumoural white matter by a mean of 2.52%. Gravimetric correction equations calculated theoretically and from an animal model of serum infusion white matter oedema overestimate peritumoural white matter oedema in man, and empirical gravimetric error correction factors for oedematous peritumoural human white matter and cortex have therefore been derived. These enable gravimetry to be used to accurately determine peritumoural oedema in man. PMID:3268140

  20. Well correction factors for three-dimensional reservoir simulation

    E-print Network

    Fjerstad, Paul Albert

    1985-01-01

    for various penetration ratios and an equation for calculating partial penetration skin, s is p \\ developed. The equation is given by: = 4 1216(h 1) - 0. 1016( ? - 1) P ' h ' h 1V The equivalent conditions for each of the radial model runs were simulated... sizes, fully penetrating well 30 33 5 Partial penetration skin correlations 34 Numerically calculated pwf from the radial model and 3-D model 53 Correction factor s3D due to cell discretization and penetration retro 56 LIST OF FIGURES FIGURE...

  1. 76 FR 19913 - Compliance Testing Procedures: Correction Factor for Room Air Conditioners

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-11

    ...than standard pressure (due to greater moisture content in the air, which generally increases latent heat removal). As a result, the correction factor...No. 42 at p. 2) DOE notes that the removal of the correction factor in ASHRAE...

  2. Finite-temperature electron correlations in the framework of a dynamic local-field correction

    SciTech Connect

    Schweng, H.K.; Boehm, H.M. (Institut fuer Theoretische Physik, Johannes Kepler Universitaet Linz, A-4040 Linz-Auhof (Austria))

    1993-07-15

    The quantum-mechanical version of the Singwi-Tosi-Land-Sjoelander (STLS) approximation is applied to finite temperatures. This approximation has two main advantages. First, it includes a dynamic local-field correction and second, it gives positive values for the pair-distribution function in the short-range region at zero temperature. This is even valid for rather low densities. After a description of the numerical difficulties arising with the use of a dynamic approximation, the results for the static-structure factor and the pair-distribution function are discussed thoroughly. Detailed work is performed on the static part of the local-field correction, with special emphasis put on the investigation of its structure. A peak is found at a wave vector [ital q][approx]2.8 (in units of the Fermi wave vector) for small temperatures, which tends towards higher values of [ital q] with increasing temperature. This peak causes an attractive particle-hole interaction in a certain [ital q] region and thus gives rise to the appearance of a charge-density wave. A parametric description is given for the static local-field correction in order to simplify further applications. Furthermore, the exchange-and-correlation free energy is considered. The results are compared with the STLS results and with the modified convolution approach.

  3. The perturbation correction factors for cylindrical ionization chambers in high-energy photon beams

    Microsoft Academic Search

    Fumiaki Yoshiyama; Fujio Araki; Takeshi Ono

    2010-01-01

    In this study, we calculated perturbation correction factors for cylindrical ionization chambers in high-energy photon beams\\u000a by using Monte Carlo simulations. We modeled four Farmer-type cylindrical chambers with the EGSnrc\\/Cavity code and calculated\\u000a the cavity or electron fluence correction factor, P\\u000a cav, the displacement correction factor, P\\u000a dis, the wall correction factor, P\\u000a wall, the stem correction factor, P\\u000a stem,

  4. Production of element correction factors for thermoluminescent dosimeters

    SciTech Connect

    Plato, P.; Miklos, J.

    1985-11-01

    Approximately 80 processors of personal dosimetry in the United States use thermoluminescent dosimeters (TLDs). Recent demands that dosimetry processors be able to measure radiation doses to within +/- 50% of the correct value have focused attention on the reproducibility of the TL elements within each TLD. The phosphors for these TLDs are manufactured by three companies. A dosimetry processor faces three options concerning the quality of the TL elements purchased; trust the supplier's quality control program, screen new TL elements and discard those that are extremely bad, or use element correction factors (ECFs). The first option results in dosimetry processors failing the +/- 50% accuracy requirement due to excessive variability among the TL elements. The second option still permits large precision errors that come close to the +/- 50% accuracy requirement. This paper advocates the third option and presents a 10-step procedure to produce ECFs. The procedure ensures that the ECFs represent only variations among the TL elements and not variations caused by stability problems with the TLD reader. Following is an example of ECF production for 3000 TLDs.

  5. Temperature Dependence of Factors Controlling Isoprene Emissions

    NASA Technical Reports Server (NTRS)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  6. An EGSnrc investigation of the P{sub TP} correction factor for ion chambers in kilovoltage x rays

    SciTech Connect

    La Russa, Daniel J.; Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Ottawa-Carleton Institute for Physics, Carleton University, Ottawa, ON, K1S 5B6 (Canada)

    2006-12-15

    As part of the standard practice for obtaining consistent ion chamber measurements with cavities open to the surrounding atmosphere, the raw measured response is corrected to the response at a reference temperature and pressure using the standard temperature-pressure correction factor (P{sub TP}). In this study, the EGSnrc Monte Carlo code was used to investigate the validity of the P{sub TP} correction factor for kilovoltage x rays incident on various geometrically distinct ion chambers. The calculated P{sub TP}-corrected chamber response deviated by over 2% relative to expected values for a 40 kV spectrum incident on a graphite thimble chamber at an air density typical of Mexico City. The relative deviation from the expected response was much worse for a large spherical graphite chamber, exceeding 16% at an air density of 0.6 kg/m{sup 3} ({approx_equal}0.5 atm at 22 deg. C) for the same beam energy. The breakdown of the P{sub TP} correction factor was also observed for a 26 kV mammography spectrum incident on two mammography chambers. For {sup 60}Co beams, the P{sub TP} correction factor behaved as expected. For day-to-day variations in pressure, only a negligible of the P{sub TP} correction factor was observed with low x-ray energies. Factors contributing to the breakdown of the P{sub TP} correction factor at low x-ray energies and large pressure variations, such as the range of electrons, the material of the wall, the chamber dimensions and air-photon interactions, are discussed in depth.

  7. An Egsnrc investigation of the P(TP) correction factor for ion chambers in kilovoltage X rays.

    PubMed

    La Russa, Daniel J; Rogers, D W O

    2006-12-01

    As part of the standard practice for obtaining consistent ion chamber measurements with cavities open to the surrounding atmosphere, the raw measured response is corrected to the response at a reference temperature and pressure using the standard temperature-pressure correction factor (P(TP)). In this study, the EGSnrc Monte Carlo code was used to investigate the validity of the P(TP) correction factor for kilovoltage x rays incident on various geometrically distinct ion chambers. The calculated P(TP)-corrected chamber response deviated by over 2% relative to expected values for a 40 kV spectrum incident on a graphite thimble chamber at an air density typical of Mexico City. The relative deviation from the expected response was much worse for a large spherical graphite chamber, exceeding 16% at an air density of 0.6 kg/m3 (approximately 0.5 atm at 22 degrees C) for the same beam energy. The breakdown of the P(TP) correction factor was also observed for a 26 kV mammography spectrum incident on two mammography chambers. For 60Co beams, the P(TP) correction factor behaved as expected. For day-to-day variations in pressure, only a negligible of the P(TP) correction factor was observed with low x-ray energies. Factors contributing to the breakdown of the P(TP) correction factor at low x-ray energies and large pressure variations, such as the range of electrons, the material of the wall, the chamber dimensions and air-photon interactions, are discussed in depth. PMID:17278811

  8. Effects of temperature gradient correction of carbon dioxide absorbent on carbon dioxide absorption

    Microsoft Academic Search

    G. Hirabayashi; H. Uchino; T. Sagara; T. Kakinuma; Y. Ogihara; N. Ishii

    2006-01-01

    Background. The effects of temperature gradients in CO2 absorbents on water content and CO2 absorption are not clear. We constructed a novel temperature gradient correction (TGC) canister, and investigated the effects of temperature gradient correction on the water content and longevity (time to exhaustion) of CO2 absorbent using a simulated anaesthesia circuit. Methods. Experiments were divided into two groups according

  9. Surface temperature correction for active infrared reflectance measurements of natural materials

    NASA Astrophysics Data System (ADS)

    Snyder, William C.; Wan, Zhengming

    1996-05-01

    Land surface temperature algorithms for the moderate resolution imaging spectroradiometer satellite instrument will require the spectral bidirectional reflectance distribution function (BRDF) of natural surfaces in the thermal infrared. We designed the spectral infrared bidirectional reflectance and emissivity instrument to provide such measurements by the use of a Fourier transform infrared spectrometer. A problem we encountered is the unavoidable surface heating caused by the source irradiance. For our system, the effects of the heating can cause a 30% error in the measured BRDF. The error caused by heating is corrected by temporally curve fitting the radiance signal. This curve-fitting technique isolates the radiance caused by reflected irradiance. With this correction, other factors dominate the BRDF error. It is now approximately 5% and can be improved further. The method is illustrated with measurements of soil BRDF. infrared, spectrometer.

  10. Apparatus and method for temperature correction and expanded count rate of inorganic scintillation detectors

    DOEpatents

    Ianakiev, Kiril D. (Los Alamos, NM); Hsue, Sin Tao (Santa Fe, NM); Browne, Michael C. (Los Alamos, NM); Audia, Jeffrey M. (Abiquiu, NM)

    2006-07-25

    The present invention includes an apparatus and corresponding method for temperature correction and count rate expansion of inorganic scintillation detectors. A temperature sensor is attached to an inorganic scintillation detector. The inorganic scintillation detector, due to interaction with incident radiation, creates light pulse signals. A photoreceiver processes the light pulse signals to current signals. Temperature correction circuitry that uses a fast light component signal, a slow light component signal, and the temperature signal from the temperature sensor to corrected an inorganic scintillation detector signal output and expanded the count rate.

  11. Correction of 2 m-temperature forecasts using Kalman Filtering technique

    NASA Astrophysics Data System (ADS)

    Libonati, Renata; Trigo, Isabel; DaCamara, Carlos C.

    2008-02-01

    Numerical weather prediction (NWP) models generally exhibit systematic errors in the forecast of near-surface weather parameters due to a wide number of factors, including poor resolution of model topography, or deficient physical parameterizations. In this work, deviations between 2 m-temperature observations and forecasts provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) are analysed at 12 synoptic stations located in Portugal. Systematic errors vary considerably with geographical location and time of day as well as throughout the year. The Kalman Filter theory provides a suitable tool to correct systematic errors of this type and therefore improve model forecasts. Accordingly, a Kalman Filter is applied to 2 m-temperature forecasts issued in 2003, a year marked by one of the most severe heat waves in Europe. It is shown that the developed methodology is versatile in adapting its coefficients to different seasons and weather conditions. The proposed Kalman Filter allows an objective forecast correction for 2 m-temperature, reducing the bias of the forecasts at each station to values close to zero, and improving the root mean square error from 10% up to over 70%, with respect to the raw ECMWF forecasts.

  12. Analytical approach to heterogeneity correction factor calculation for brachytherapy.

    PubMed

    Daskalov, G M; Kirov, A S; Williamson, J F

    1998-05-01

    In brachytherapy treatment planning, the effects of tissue and applicator heterogeneities are commonly neglected due to lack of accurate, general, and fast three-dimensional (3D) dose-computational algorithms. A novel approach, based on analytical calculation of scattered photon fluxes inside and around a disk-shaped heterogeneity, has been developed for use in the three-dimensional scatter-subtraction algorithm. Specifically, our model predicts the central-ray dose distribution for a collimated photon isotropic source or brachytherapy "minibeam" in the presence of a slab of heterogeneous material. The model accounts for the lateral dimensions, location, composition, density, and thickness of the heterogeneity using precalculated scatter-to-primary ratios (SPRs) for the corresponding homogeneous problem. The model is applicable to the entire brachytherapy energy range (25 to 662 keV) and to a broad range of materials having atomic numbers of 13 to 82, densities of 2.7 g.cm-3 (Al) to 21.45 g.cm-3 (Pt) and thicknesses up to 1 mean free path. For this range of heterogeneous materials, the heterogeneity correction factors (HCFs) vary from 0.09 to 0.75. The model underestimates HCF when multiple scattering prevails and overestimates HCF when absorption dominates. However, the analytic model agrees with Monte Carlo photon transport (MCPT) benchmark calculations within 1.8% to 10% for 125I, 169Yb, 192Ir, and 137Cs for a wide variety of materials, with the exception of Ag. For 125I shielded by Ag, where the mean discrepancy can exceed 25%, the error is due to K-edge characteristic x rays originating within the heterogeneity. The proposed approach provides reductions in CPU time required of 5 x 10(4)-10(5) and 100 in comparison with direct MCPT simulation and 1D numerical integration, respectively. The limitations of model applicability, as determined by the physical properties of heterogeneity material and accuracy required, are also discussed. PMID:9608484

  13. A New Correction Technique for Strain-Gage Measurements Acquired in Transient-Temperature Environments

    NASA Technical Reports Server (NTRS)

    Richards, W. Lance

    1996-01-01

    Significant strain-gage errors may exist in measurements acquired in transient-temperature environments if conventional correction methods are applied. As heating or cooling rates increase, temperature gradients between the strain-gage sensor and substrate surface increase proportionally. These temperature gradients introduce strain-measurement errors that are currently neglected in both conventional strain-correction theory and practice. Therefore, the conventional correction theory has been modified to account for these errors. A new experimental method has been developed to correct strain-gage measurements acquired in environments experiencing significant temperature transients. The new correction technique has been demonstrated through a series of tests in which strain measurements were acquired for temperature-rise rates ranging from 1 to greater than 100 degrees F/sec. Strain-gage data from these tests have been corrected with both the new and conventional methods and then compared with an analysis. Results show that, for temperature-rise rates greater than 10 degrees F/sec, the strain measurements corrected with the conventional technique produced strain errors that deviated from analysis by as much as 45 percent, whereas results corrected with the new technique were in good agreement with analytical results.

  14. Elevation correction factors for E-PERM radon monitors.

    PubMed

    Kotrappa, P; Stieff, L R

    1992-01-01

    E-PERM radon monitors are based on the principle of electret ion chambers and are usually calibrated in a standard radon chamber located at sea level. Corrections are needed if the monitors are used at elevations other than sea level. These were experimentally determined for three models of commercially available electret ion chambers (E-PERM) as functions of elevation above sea level. These corrections are minor and should be applied for obtaining more accurate results. PMID:1727416

  15. Power Factor Correction of Single-Phase Induction Motor Using Magnetic Energy Recovery Switch

    NASA Astrophysics Data System (ADS)

    Takaku, Taku; Narushima, Jun; Isobe, Takanori; Kitahara, Tadayuki; Shimada, Ryuichi

    Magnetic energy recovery switch (MERS) has a function of automatic power factor correction of series connected load. The MERS is applied for a single-phase induction motor to improve the power factor. Two control methods of the MERS for power factor correction are described in this paper. Experiments were carried out and confirmed that the input power factor of a single-phase induction motor is improved.

  16. Spatial correction factors for YALINA Booster facility loaded with medium and low enriched fuels

    SciTech Connect

    Talamo, A.; Gohar, Y. [Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439 (United States); Bournos, V.; Fokov, Y.; Kiyavitskaya, H.; Routkovskaya, C. [Joint Inst. for Power and Nuclear Research-Sosny, 99 Academician A.K.Krasin Str, Minsk 220109 (Belarus)

    2012-07-01

    The Bell and Glasstone spatial correction factor is used in analyses of subcritical assemblies to correct the experimental reactivity as function of the detector position. Besides the detector position, several other parameters affect the correction factor: the energy weighting function of the detector, the detector size, the energy-angle distribution of source neutrons, and the reactivity of the subcritical assembly. This work focuses on the dependency of the correction factor on the detector material and it investigates the YALINA Booster subcritical assembly loaded with medium (36%) and low (10%) enriched fuels. (authors)

  17. Virtual Next-to-Leading Corrections to the Impact Factors in the High-Energy Limit

    E-print Network

    Vittorio Del Duca; Carl R. Schmidt

    1997-11-12

    We compute the virtual next-to-leading corrections to the impact factors or off-shell coefficient functions in the high-energy limit. When combined with the known real corrections, these results will provide the complete NLO corrections to the impact factors, which are necessary to use the BFKL resummation at NLL for jet production at both lepton-hadron and hadron-hadron colliders.

  18. Well correction factors for three-dimensional reservoir simulation with nonsquare grid blocks and anisotropic permeability 

    E-print Network

    Kim, Dukmin

    1988-01-01

    * ** *ee Case a kz+h Ax p/ t po pmf s3D pwf pmf 1 1 2 2 3 1 4 1 5 4 6 1 7 2 8 1 9 1 10 4 11 1 12 2 13 4 14 1 15 4 16 1 17 2 18 4 19 1 20 4 1. 0 32. 1. 0 32. 1. 0 128. 0. 5 32. 0. 5 32. 1. 0 32. 1. 0 32, 1. 0 128. 0. 5 32. 0. 5 32...-D WELL CORRECTION FACTOR& a 2, kz/kh - 1 48 49 50 51 52 59 85 86 C3 3-D WELL CORRECTION FACTOR, a 4 kz/kh 1 87 C4 C5 3 D WELL CORRECTION FACTOR~ a 8~ kz/kh 1 3 D WELL CORRECTION FACTOR a 1 kz/kh 0 5 88 89 C6 3-D WELL CORRECTION FACTOR...

  19. A simple and fast atmospheric correction for spaceborne remote sensing of surface temperature

    Microsoft Academic Search

    A. N French; J. M Norman; M. C Anderson

    2003-01-01

    Accurate surface temperature retrieval using thermal infrared observations from satellites is important for surface energy balance modeling; however it is difficult to achieve without proper correction for atmospheric effects. Typically the atmospheric correction is obtained from radiosonde profiles and a radiative transfer model (RTM). But rigorous RTM processing is impractical for routine continental scale modeling because of long computational times.

  20. The surface-brightness method and the dependence of the bolometric correction on star effective temperature

    Microsoft Academic Search

    A. N. Gubochkin; A. S. Miroshnichenko

    1991-01-01

    Studies of the physical characteristics of 228 stars (Tef > 4700K) are used to plot the surface-brightness parameter against the (B-V)0 and (V-R)0 color indices (corrected for interstellar reddening) and the bolometric correction against effective temperature. Simple analytic expressions are derived for these relationships.

  1. Weld pool penetration measurement using ultrasound with thermal gradient correction factors

    NASA Astrophysics Data System (ADS)

    Anderton, John Martin

    Weld penetration is critical to final weld performance. There are many techniques for determining surface parameters of weld pools but the transient nature of the pools, high temperatures and intense electromagnetic energy make direct measurement of the penetration of weld pools difficult. In order to determine weld pool penetration ultrasonically from below the weld pool it is necessary to compensate for the variation in the time of flight of the ultrasound wave due to temperature gradients. This requires both a precise understanding of the location and magnitude of the temperature gradients and the time of flight of ultrasound at the range of temperatures seen in the gradients. Given this information it is possible to develop a correction factor to an ultrasonic time of flight reading that accurately represents the actual penetration of a weld pool. This research examines the electroslag surfacing (ESS) processing of AISI 1005 low carbon steel clad onto a ductile iron substrate. The high temperature cladding on low temperature substrate provides a deep weld penetration. Ultrasonic time of flight measurements were made from a piezoelectric transducer on the backside of the substrate to the solid/liquid interface of the weld pool during welding. The speed of ultrasound over a range of temperatures was determined from furnace heated ductile iron substrates. The sample was stepped and contact piezoelectric methods used to determine time of flight. A finite element model was developed and analyzed to predict thermal gradients in the substrate around the weld pool. The model was correlated to thermocouple data of substrate heating during welding. The predicted thermal gradients and speed/temperature curves are combined with the time of flight measurement to determine the location of the solid/liquid weld interface. An automated seam tracking system for ESS was also developed. This system utilizes a line laser at right angles to the view of a CCD camera which illuminates the relief of the existing bead for the camera. Optimas software was used to locate the edge of the bead and determine the correct location for the weld head to overlap the existing bead.

  2. The late Pleistocene ground surface temperature and corrected heat flow density for northern part of Poland

    NASA Astrophysics Data System (ADS)

    Szewczyk, J.; Gientka, D.

    2003-04-01

    Paleoclimatic ground surface temperature (GST) changes in last 100 ka years are a major factor causing vertical variation of terrestrial heat flow density (HFD). The value of this parameter important for thermal and rheological modelling may be considerably influenced by paleoclimatic factor and should be corrected for this reason. Very important criteria for studying paleoclimatic events on boreholes is the knowledge of depth distribution of thermal conductivity. However, core samples from majority of deep boreholes are hardly available and laboratory measurements of thermal conductivity are very scarce and sometimes not confident. We used a method of estimating the thermal conductivity from well logging data interpretation. The thermal conductivity was calculated using volumetric model of rock with mean geometric formula. The synthetic temperature logs (T_s) based on this data are an "active" method of investigation of vertical variation of HFD and GST determination. For a majority of deep boreholes in Polish Lowlands in uppermost part (<2000 m) we have observed dramatic disagreement between measured temperature (T) and synthetic data (T_s). We consider that the observed vertical variations of HFD in shallow part of profiles are mainly due to Holocene warming. The lower parts of profiles are still in thermal regime of the Weichselian glaciation. Presented results of GST in the Late Pleistocene for the representative data for 59 deep boreholes for the N of Poland. The GST was -5.17 +/- 5.45^oC. The observed big scatter of presented results seems to be consequence of unstable thermal conditions and bad calibration of old temperature logs. The amplitude of post glacial warming (?GST) is not less then +13.1^oC. The history of climate for the last 500 ka years shows that this time was spent mainly in ice age and this is "normal" state of HFD. The presented method of investigations seems to be very effective for determination of HFD for this condition.

  3. Correction of the frequency characteristic of the waveguide circuit of an acoustic-jet temperature transducer

    NASA Astrophysics Data System (ADS)

    Gimadiev, A. G.; Kozlov, A. Iu.; Ishal, V. A.

    For the waveguide circuit of an acoustic-jet temperature transducer, a correction device is proposed which consists of in-series acoustic amplifier and vibration damper, with a pressure fluctuation transducer between them. A procedure for selecting the parameters of the correction device is described. Experimental results are presented which demonstrate an increase in the characteristic stability of the temperature transducer of an aviation gas turbine engine.

  4. IEEE 1451 Correction Engine to Temperature-compensation of Magnetoresistive Transducers

    Microsoft Academic Search

    Helena Ramos; O. Postolache; M. Pereira; P. Girao

    2005-01-01

    The paper presents the comparison between polynomial approximation and artificial neural networks (ANNs) to compensate temperature dependence of a magnetic field transducer. The sensing elements are a magnetoresistance whose value can vary almost 20% in the experimental operating temperature range (20degC-100degC) and a two terminal integrated temperature sensor. The first technique to correct the temperature drift in the magnetoresistance is

  5. A new high performance AC to DC rectifier with input power factor correction and harmonic reduction capacity

    E-print Network

    Martinez, Roberto

    1994-01-01

    correction input characteristics. . . . . . , . . . . 81 57 600W load without PF correction . . 84 58 Smart Power implementation with 600W load and PF correction . 84 LIST OF TABLES TABLE Page Limits for Class A and Class B equipment, . 14 Limits... for Class C equipment . Limits for Class D equipment . 15 15 Measured experimental data without power factor correction . 82 Measured experimental data with power factor correction 83 CHAPTER I INTRODUCTION The input power factor is an important...

  6. Three-Dimensional Thermal Boundary Layer Corrections for Circular Heat Flux Gauges Mounted in a Flat Plate with a Surface Temperature Discontinuity

    NASA Technical Reports Server (NTRS)

    Kandula, M.; Haddad, G. F.; Chen, R.-H.

    2006-01-01

    Three-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been performed in an effort to determine thermal boundary layer correction factors for circular convective heat flux gauges (such as Schmidt-Boelter and plug type)mounted flush in a flat plate subjected to a stepwise surface temperature discontinuity. Turbulent flow solutions with temperature-dependent properties are obtained for a free stream Reynolds number of 1E6, and freestream Mach numbers of 2 and 4. The effect of gauge diameter and the plate surface temperature have been investigated. The 3-D CFD results for the heat flux correction factors are compared to quasi-21) results deduced from constant property integral solutions and also 2-D CFD analysis with both constant and variable properties. The role of three-dimensionality and of property variations on the heat flux correction factors has been demonstrated.

  7. Factors Influencing the Design, Establishment, Administration, and Governance of Correctional Education for Females

    ERIC Educational Resources Information Center

    Ellis, Johnica; McFadden, Cheryl; Colaric, Susan

    2008-01-01

    This article summarizes the results of a study conducted to investigate factors influencing the organizational design, establishment, administration, and governance of correctional education for females. The research involved interviews with correctional and community college administrators and practitioners representing North Carolina female…

  8. Aerosol Correction for Remotely Sensed Sea Surface Temperatures From the NOAA AVHRR: Phase II

    Microsoft Academic Search

    N. R. Nalli; A. Ignatov

    2002-01-01

    For over two decades, the National Oceanic and Atmospheric Administration (NOAA) has produced global retrievals of sea surface temperature (SST) using infrared (IR) data from the Advanced Very High Resolution Radiometer (AVHRR). The standard multichannel retrieval algorithms are derived from regression analyses of AVHRR window channel brightness temperatures against in situ buoy measurements under non-cloudy conditions thus providing a correction

  9. LIGHT-DUTY DIESEL EMISSION CORRECTION FACTORS FOR AMBIENT CONDITIONS

    EPA Science Inventory

    Since emission measurements from passenger cars are performed at one standard set of ambient conditions and since emission rates of HC, CO, and NOx are sensitive to temperature and humidity, it is necessary to determine the influence of ambient conditions on emissions from major ...

  10. Perturbation correction factors for cylindrical ionization chambers in high-energy electron beams

    Microsoft Academic Search

    Takeshi Ono; Fujio Araki; Fumiaki Yoshiyama

    2010-01-01

    The aim of the study was to evaluate the perturbation correction factors at a reference depth for cylindrical ionization chambers\\u000a in high-energy electron beams by means of the EGSnrc Monte Carlo user code cavity. The cylindrical chambers used in this study\\u000a were the Farmer-type of PTW30010, PTW30011, PTW30012, and PTW30013 models. We calculated the wall correction factor, P\\u000a wall, the

  11. Beta and Gamma Correction Factors for the Eberline R0-20 Ionization Chamber Survey Instrument

    Microsoft Academic Search

    Michelle L Johnson; Bruce A Rathbone; Tom Bratvold

    2001-01-01

    This technical document provides details of derived correction factors for the Eberline R0-20 survey meter, which uses an ionization chamber to measure ambient exposure rates. A thin end window allows the instrument to measure exposure rates from non-penetrating radiation (i.e., beta radiation). Correction factors are provided for contact measurements with beta and gamma disk sources, gamma beams and, finally, general

  12. Symmetry-breaking corrections to heavy meson form-factor relations

    Microsoft Academic Search

    Benjam??n Grinstein; Dan Pirjol

    2002-01-01

    In the heavy quark limit, the form factors for semileptonic and rare radiative B decays into light mesons are related by heavy quark spin symmetry. Here we compute the leading corrections of order ?\\/mQ to these symmetry relations, showing also how to include hard gluon effects systematically to any order in ?s(mQ). The subleading correction to the form factor relation

  13. Analysis and design of soft-switching power factor correction converter

    Microsoft Academic Search

    Jaber Abu-Qahouq; H. Wei; W. Gu; I. Batarseh

    2000-01-01

    A single-stage power factor correction converter with soft-switching is proposed in this paper. The topology of this converter is derived by adding a resonant circuit to an existing Single-Stage, Single-Switch Power Factor Correction (S4 PFC) converter. As a result, zero-voltage-switching and zero-current-switching are achieved for the main switch and the auxiliary switch, respectively. High frequency operation of the proposed converter

  14. Corrections to kerma factor measurements made by integral techniques

    Microsoft Academic Search

    P. M. de Luca; H. H. Barschall; C. L. Hartmann; D. W. Pearson

    1989-01-01

    Integral determinations of fast neutron kerma factors with low pressure proportional counters usually assume that either neutron interactions with the counting gas do not significantly contribute to the total energy deposited by charged particles in the gas or else that the wall and gas kerma are identical. This condition can be achieved for hydrogenous or graphite walled instruments. For elements

  15. Perturbation correction factors for cylindrical ionization chambers in high-energy electron beams.

    PubMed

    Ono, Takeshi; Araki, Fujio; Yoshiyama, Fumiaki

    2010-07-01

    The aim of the study was to evaluate the perturbation correction factors at a reference depth for cylindrical ionization chambers in high-energy electron beams by means of the EGSnrc Monte Carlo user code cavity. The cylindrical chambers used in this study were the Farmer-type of PTW30010, PTW30011, PTW30012, and PTW30013 models. We calculated the wall correction factor, P (wall), the cavity or electron fluence correction factor, P (cav), the stem correction factor, P (stem), the central electrode correction factor, P (cel), and the overall perturbation correction factor, P (Q), for each chamber. The calculated P (cav) values were higher by from 2 to 1% than those recommended by the IAEA-TRS-398 code of practice, in an energy range of 6-18 MeV. The P (wall) values almost agreed with the analytical calculation performed with IAEA-TRS-398. The P (cel) values agreed with those of Ma and Nahum, performed with IAEA-TRS-398. The P (stem) values were approximately 0.995 on average and were independent of the electron beam energy. P (stem) needs to be considered in future dosimetry protocols. The P (Q) values were higher from 1 to 2% than those of IAEA-TRS-398 in an energy range of 6-18 MeV. PMID:20821081

  16. Global analysis of proton elastic form factor data with two-photon exchange corrections

    SciTech Connect

    J. Arrington; W. Melnitchouk; J. A. Tjon

    2007-09-01

    We use the world's data on elastic electron-proton scattering and calculations of two-photon exchange effects to extract corrected values of the proton's electric and magnetic form factors over the full Q^2 range of the existing data. Our analysis combines the corrected Rosenbluth cross section and polarization transfer data, and is the first extraction of G_Ep and G_Mp including explicit two-photon exchange corrections and their associated uncertainties. In addition, we examine the angular dependence of the corrected cross sections, and discuss the possible nonlinearities of the cross section as a function of epsilon.

  17. Binding two-loop vacuum-polarization corrections to the bound-electron g factor

    E-print Network

    U. D. Jentschura

    2009-04-06

    We commence the evaluation of the one- and two-loop binding corrections to the $g factor for an electron in a hydrogenlike system of order alpha^2 (Z alpha)^5 and consider diagrams with closed fermion loops. The one-loop vacuum-polarization correction is rederived and confirmed. For the two-loop vacuum-polarization correction, due to a specific gauge-invariant set of diagrams with closed fermion loops, we find a correction delta g = 7.442 (alpha/pi)^2 (Z alpha)^5. Based on the numerical trend of the coefficients inferred from the gauge-invariant subset, we obtain a numerically large tentative estimate for the complete two-loop binding correction to the g factor (sum of self-energy and vacuum polarization).

  18. [Occupational risk factors and medical prevention in corrections officers].

    PubMed

    Mennoial, Nunzio Valerio; Napoli, Paola; Battaglia, Andrea; Candura, Stefano M

    2014-01-01

    In Italy, the Law n. 395/1990 defines the tasks and attributions of prison officers. According to the article 25 of the Legislative Decree n. 81/2008, the occupational physician should participate to risk assessment, and carry out the sanitary surveillance. This report analyzes the various tasks of prison staff, identifies the risk factors, and discusses the preventive strategies, including workers formation and education. Biological agents and work-related stress are the main risk factors, as a consequence of prison overcrowding, personnel shortage and work organization complexity. In his preventive action, and particularly in formulating the judgment on work fitness, the occupational physician often clashes with inadequate ministerial funding. PMID:25558744

  19. Correction improves z-factor values for high gas density

    SciTech Connect

    Borges, P.R. (Petrobras, Rio de Janeiro (BR))

    1991-03-04

    A simple modification is suggested to improve the z-factor values obtained from the subroutines developed from the Dranchuk, et al., and Abou-Kassem equations of state. These correlations are commonly included in some software available for general use in the petroleum industry. The original subroutines, proposed by these authors, return inaccurate values for high gas density within the application range stated by the authors.

  20. Joint bias correction of temperature and precipitation in climate model simulations

    NASA Astrophysics Data System (ADS)

    Li, Chao; Sinha, Eva; Horton, Daniel E.; Diffenbaugh, Noah S.; Michalak, Anna M.

    2014-12-01

    Bias correction of meteorological variables from climate model simulations is a routine strategy for circumventing known limitations of state-of-the-art general circulation models. Although the assessment of climate change impacts often depends on the joint variability of multiple variables, commonly used bias correction methodologies treat each variable independently and do not consider the relationship among variables. Independent bias correction can therefore produce non-physical corrections and may fail to capture important multivariate relationships. Here, we introduce a joint bias correction methodology (JBC) and apply it to precipitation (P) and temperature (T) fields from the fifth phase of the Climate Model Intercomparison Project (CMIP5) model ensemble. This approach is based on a general bivariate distribution of P-T and can be seen as a multivariate extension of the commonly used univariate quantile mapping method. It proceeds by correcting either P or T first and then correcting the other variable conditional upon the first one, both following the concept of the univariate quantile mapping. JBC is shown to not only reduce biases in the mean and variance of P and T similarly to univariate quantile mapping, but also to correct model-simulated biases in P-T correlation fields. JBC, using methods such as the one presented here, thus represents an important step in impacts-based research as it explicitly accounts for inter-variable relationships as part of the bias correction procedure, thereby improving not only the individual distributions of P and T, but critically, their joint distribution.

  1. The perturbation correction factor of ionisation chambers in beta-radiation fields.

    PubMed

    Böhm, J

    1980-01-01

    In determining the absorbed dose in a solid medium by means of gas-filled ionisation chambers, the perturbation of the radiation field by the chamber needs to be taken into account. So far, an appropriate correction factor has neither been calculated nor measured for beta-radiation. This work describes its experimental determination for an extrapolation chamber and beta-radiation fields of 147Pm, 204Tl, and 90Sr + 90Y. The results show that the correction factor may be assumed to be the product of a shield factor and a scatter factor the magnitudes of which depend on the chamber geometry and the radiation field. The change of the perturbation correction factor with phantom depth is important for the measurement of depth dose curves. This is demonstrated by an example. PMID:7360793

  2. Quantum gravitational correction to the Hawking temperature from the Lemaitre-Tolman-Bondi model

    E-print Network

    Rabin Banerjee; Claus Kiefer; Bibhas Ranjan Majhi

    2010-08-11

    We solve the quantum constraint equations of the Lemaitre-Tolman-Bondi model in a semiclassical approximation in which an expansion is performed with respect to the Planck length. We recover in this way the standard expression for the Hawking temperature as well as its first quantum gravitational correction. We then interpret this correction in terms of the one-loop trace anomaly of the energy-momentum tensor and thereby make contact with earlier work on quantum black holes.

  3. Quantum gravitational correction to the Hawking temperature from the Lemaitre-Tolman-Bondi model

    SciTech Connect

    Banerjee, Rabin; Majhi, Bibhas Ranjan [S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata-700098 (India); Kiefer, Claus [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany)

    2010-08-15

    We solve the quantum constraint equations of the Lemaitre-Tolman-Bondi model in a semiclassical approximation in which an expansion is performed with respect to the Planck length. We recover in this way the standard expression for the Hawking temperature as well as its first quantum gravitational correction. We then interpret this correction in terms of the one-loop trace anomaly of the energy-momentum tensor and thereby make contact with earlier work on quantum black holes.

  4. A digital power factor correction (PFC) control strategy optimized for DSP

    Microsoft Academic Search

    Wanfeng Zhang; Guang Feng; Yan-Fei Liu; Bin Wu

    2004-01-01

    A predictive algorithm for digital control power factor correction (PFC) is presented in this paper. Based on this algorithm, all of the duty cycles required to achieve unity power factor in one half line period are calculated in advance by digital signal processors (DSP). A boost converter controlled by these precalculated duty cycles can achieve sinusoidal current waveform. One main

  5. The Real Corrections to the Gamma* Impact Factor: First Numerical Results

    E-print Network

    Albrecht Kyrieleis

    2004-07-29

    We have performed analytically the transverse momentum integrations in the real corrections to the longitudinal \\gamma^*_L impact factor and carried out numerically the remaining integrations. I outline the analytical integration and present the numerical results: we have performed a numerical test and computed those parts of the impact factor that depend upon the energy scale s_0.

  6. Temperature corrections to the thermodynamic functions of a degenerate neutron gas in a magnetic field

    SciTech Connect

    Skobelev, V. V., E-mail: v.skopbelev@inbox.ru [Moscow State Industrial University (Russian Federation)

    2011-08-15

    Temperature corrections to the basic thermodynamic functions calculated in our earlier publication for a degenerate neutron gas in a magnetic field are determined taking into account the anomalous magnetic moment of a neutron. The heat capacity and entropy of the degenerate neutron gas, as well as the temperature correction to the magnetic susceptibility, are also calculated. Additional arguments supporting the effect of an increase in the pulse frequency of pulsars mentioned in the previous publication are formulated; the results of that publication are refined.

  7. A New High-precision Correction Method of Temperature Distribution in Model Stellar Atmospheres

    NASA Astrophysics Data System (ADS)

    Sapar, A.; Poolamäe, R.; Sapar, L.

    The main features of the temperature correction methods, suggested and used in modeling of plane-parallel stellar atmospheres, are discussed. The main features of the new method are described. Derivation of the formulae for a version of the Unsöld-Lucy method, used by us in the SMART (Stellar Model Atmospheres and Radiative Transport) software for modeling stellar atmospheres, is presented. The method is based on a correction of the model temperature distribution based on minimizing differences of flux from its accepted constant value and on the requirement of the lack of its gradient, meaning that local source and sink terms of radiation must be equal. The final relative flux constancy obtainable by the method with the SMART code turned out to have the precision of the order of 0.5 %. Some of the rapidly converging iteration steps can be useful before starting the high-precision model correction. The corrections of both the flux value and of its gradient, like in Unsöld-Lucy method, are unavoidably needed to obtain high-precision flux constancy. A new temperature correction method to obtain high-precision flux constancy for plane-parallel LTE model stellar atmospheres is proposed and studied. The non-linear optimization is carried out by the least squares, in which the Levenberg-Marquardt correction method and thereafter additional correction by the Broyden iteration loop were applied. Small finite differences of temperature (? T/T=10-3) are used in the computations. A single Jacobian step appears to be mostly sufficient to get flux constancy of the order 10-2 %. The dual numbers and their generalization -- the dual complex numbers (the duplex numbers) -- enable automatically to get the derivatives in the nilpotent part of the dual numbers. A version of the SMART software is in the stage of refactorization to dual and duplex numbers, what enables to get rid of the finite differences, as an additional source of lowering precision of the computed results.

  8. Second-Order Corrections to the Magnetic Moment of Electron at Finite Temperature

    NASA Astrophysics Data System (ADS)

    Masood, Samina S.; Haseeb, Mahnaz Q.

    2012-12-01

    Magnetic moment of electron at finite temperature is directly related to the modified electron mass in the background heat bath. Magnetic moment of electron gets modified at finite temperature also, when it couples with the magnetic field, through its temperature-dependent physical mass. We show that the second-order corrections to the magnetic moment of electron is a complicated function of temperature. We calculate the self-mass induced thermal contributions to the magnetic moment of electron, up to the two-loop level, for temperatures valid around the era of primordial nucleosynthesis. A comparison of thermal behavior of the magnetic moment is also quantitatively studied in detail, around the temperatures below and above the nucleosynthesis temperature.

  9. Correcting temperature dependence in miniature spectrometers used in cold polar environments.

    PubMed

    Wang, Hangzhou; Song, Hong; Chen, Ying; Laney, Samuel R

    2015-04-10

    Measurement biases arising from changes in temperature can be a major concern when using miniature spectrometers in extreme environments, particularly when temperature stabilization approaches are not feasible. Here, temperature-related biases of a low-power field spectrometry system comprised of a CMOS miniature monolithic spectrometer module and custom driver electronics were examined between -40°C and +25.6°C, well below the stated operating range of this particular spectrometer. Using these observations, a predictive model was developed to estimate the dark output of the spectrometry system within this extended operating range. This information was used to correct the signal at any measured integration time and temperature to that which would be measured at a reference integration time and temperature. This approach provides a general framework for assessing the temperature dependence of monolithic spectrometers whose field use will occur at temperatures outside of the range examined by the manufacturer. PMID:25967300

  10. Heavy-to-light B meson form factors at large recoil energy—spectator-scattering corrections

    Microsoft Academic Search

    M. Beneke; D. Yang

    2006-01-01

    We complete the investigation of loop corrections to hard spectator-scattering in exclusive B meson to light meson transitions by computing the short-distance coefficient (jet-function) from the hard-collinear scale. Adding together the two coefficients from matching QCD?SCETI?SCETII, we investigate the size of loop effects on the ratios of heavy-to-light meson form factors at large recoil. We find the corrections from the

  11. Parameterized nonuniformity corrections (NUC) for non-temperature stabilized InGaAs SWIR sensing

    Microsoft Academic Search

    Jesse Battaglia; Vincent Burzi; Bruce Moyer; Thomas Sudol; Joseph Passe

    2010-01-01

    Military applications for conventional InGaAs SWIR sensing have been limited by the requirement of thermoelectric cooler (TEC) temperature stabilization for nonuniformity correction (NUC). TEC operation restricts the operating temperature range and size, weight, and power (SWAP) of these systems. For battery-powered man portable and micro UAV applications elimination of the TEC is critical. This paper discusses the advantages of our

  12. Mach-uniformity through the coupled pressure and temperature correction algorithm

    SciTech Connect

    Nerinckx, Krista [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Krista.Nerinckx@UGent.be; Vierendeels, Jan [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Jan.Vierendeels@UGent.be; Dick, Erik [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Erik.Dick@UGent.be

    2005-07-01

    We present a new type of algorithm: the coupled pressure and temperature correction algorithm. It is situated in between the fully coupled and the fully segregated approach, and is constructed such that Mach-uniform accuracy and efficiency are obtained. The essential idea is the separation of the convective and the acoustic/thermodynamic phenomena: a convective predictor is followed by an acoustic/thermodynamic corrector. For a general case, the corrector consists of a coupled solution of the energy and the continuity equations for both pressure and temperature corrections. For the special case of an adiabatic perfect gas flow, the algorithm reduces to a fully segregated method, with a pressure-correction equation based on the energy equation. Various test cases are considered, which confirm that Mach-uniformity is obtained.

  13. Water temperature-influential factors, field measurement, and data presentation

    USGS Publications Warehouse

    Stevens, Herbert H.; Ficke, John F.; Smoot, George F.

    1975-01-01

    This manual contains suggested procedures for collecting and reporting of water-temperature data on streams, lakes and reservoirs, estuaries, and ground water. Among the topics discussed are the selection of equipment and measuring sites, objectives and accuracy of measurements, and data processing and presentation. Background information on the influence of temperature on water quality and the factors influencing water temperature are also presented.

  14. Skin Temperature Analysis and Bias Correction in a Coupled Land-Atmosphere Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Radakovich, Jon D.; daSilva, Arlindo; Todling, Ricardo; Verter, Frances

    2006-01-01

    In an initial investigation, remotely sensed surface temperature is assimilated into a coupled atmosphere/land global data assimilation system, with explicit accounting for biases in the model state. In this scheme, an incremental bias correction term is introduced in the model's surface energy budget. In its simplest form, the algorithm estimates and corrects a constant time mean bias for each gridpoint; additional benefits are attained with a refined version of the algorithm which allows for a correction of the mean diurnal cycle. The method is validated against the assimilated observations, as well as independent near-surface air temperature observations. In many regions, not accounting for the diurnal cycle of bias caused degradation of the diurnal amplitude of background model air temperature. Energy fluxes collected through the Coordinated Enhanced Observing Period (CEOP) are used to more closely inspect the surface energy budget. In general, sensible heat flux is improved with the surface temperature assimilation, and two stations show a reduction of bias by as much as 30 Wm(sup -2) Rondonia station in Amazonia, the Bowen ratio changes direction in an improvement related to the temperature assimilation. However, at many stations the monthly latent heat flux bias is slightly increased. These results show the impact of univariate assimilation of surface temperature observations on the surface energy budget, and suggest the need for multivariate land data assimilation. The results also show the need for independent validation data, especially flux stations in varied climate regimes.

  15. Implementation of Coupled Skin Temperature Analysis and Bias Correction in a Global Atmospheric Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Radakovich, Jon; Bosilovich, M.; Chern, Jiun-dar; daSilva, Arlindo

    2004-01-01

    The NASA/NCAR Finite Volume GCM (fvGCM) with the NCAR CLM (Community Land Model) version 2.0 was integrated into the NASA/GMAO Finite Volume Data Assimilation System (fvDAS). A new method was developed for coupled skin temperature assimilation and bias correction where the analysis increment and bias correction term is passed into the CLM2 and considered a forcing term in the solution to the energy balance. For our purposes, the fvDAS CLM2 was run at 1 deg. x 1.25 deg. horizontal resolution with 55 vertical levels. We assimilate the ISCCP-DX (30 km resolution) surface temperature product. The atmospheric analysis was performed 6-hourly, while the skin temperature analysis was performed 3-hourly. The bias correction term, which was updated at the analysis times, was added to the skin temperature tendency equation at every timestep. In this presentation, we focus on the validation of the surface energy budget at the in situ reference sites for the Coordinated Enhanced Observation Period (CEOP). We will concentrate on sites that include independent skin temperature measurements and complete energy budget observations for the month of July 2001. In addition, MODIS skin temperature will be used for validation. Several assimilations were conducted and preliminary results will be presented.

  16. An improved method for correction of air temperature measured using different radiation shields

    NASA Astrophysics Data System (ADS)

    Cheng, Xinghong; Su, Debin; Li, Deping; Chen, Lu; Xu, Wenjing; Yang, Meilin; Li, Yongcheng; Yue, Zhizhong; Wang, Zijing

    2014-11-01

    The variation of air temperature measurement errors using two different radiation shields (DTR502B Vaisala, Finland, and HYTFZ01, Huayun Tongda Satcom, China) was studied. Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012. Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers (FRP) Stevenson screen. In most cases, the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield. The measured errors changed sharply at sunrise and sunset, and reached maxima at noon. Their diurnal variation characteristics were, naturally, related to changes in solar radiation. The relationships between the record errors, global radiation, and wind speed were nonlinear. An improved correction method was proposed based on the approach described by Nakamura and Mahrt (2005) (NM05), in which the impact of the solar zenith angle (SZA) on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively. Measurement errors were reduced significantly after correction by either method for both shields. The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3% and 40.4% higher than those using the NM05 method, respectively.

  17. OBSERVATIONS OF SIMILARITY THEORY STABILITY CORRECTION TERMS FOR MOMENTUM AND TEMPERATURE, OVER AGRICULTURAL FIELDS AND FORESTS.

    EPA Science Inventory

    Many observations of temperature and wind speed profiles have been taken over "ideal" terrain and analyzed to develop the stability correction terms which are commonly used in the application of similarity theory. Fewer observations have been taken and analyzed in this manner ov...

  18. Development of Self-Correcting Algorithms for Complete Failure of Supply Air Temperature Sensors 

    E-print Network

    Monfet, D.; Choiniere, D.; Padilla, M.

    2013-01-01

    Development of self-correcting algorithms for complete failure of supply air temperature sensors by D. Monfet1,D. Choini?re2, M. Padilla2 1?cole de technologie sup?rieure 2Natural Resources Canada INTERNATIONAL CONFERENCE FOR ENHANCED...

  19. Impact of the neutron detector choice on Bell and Glasstone spatial correction factor for subcriticality measurement

    NASA Astrophysics Data System (ADS)

    Talamo, Alberto; Gohar, Y.; Cao, Y.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.

    2012-03-01

    In subcritical assemblies, the Bell and Glasstone spatial correction factor is used to correct the measured reactivity from different detector positions. In addition to the measuring position, several other parameters affect the correction factor: the detector material, the detector size, and the energy-angle distribution of source neutrons. The effective multiplication factor calculated by computer codes in criticality mode slightly differs from the average value obtained from the measurements in the different experimental channels of the subcritical assembly, which are corrected by the Bell and Glasstone spatial correction factor. Generally, this difference is due to (1) neutron counting errors; (2) geometrical imperfections, which are not simulated in the calculational model, and (3) quantities and distributions of material impurities, which are missing from the material definitions. This work examines these issues and it focuses on the detector choice and the calculation methodologies. The work investigated the YALINA Booster subcritical assembly of Belarus, which has been operated with three different fuel enrichments in the fast zone either: high (90%) and medium (36%), medium (36%), or low (21%) enriched uranium fuel.

  20. Correction of temperature influence on the wind retrieval from a mobile Rayleigh Doppler lidar

    NASA Astrophysics Data System (ADS)

    Zhao, Ruo-Can; Xia, Hai-Yun; Dou, Xian-Kang; Sun, Dong-Song; Han, Yu-Li; Shangguan, Ming-Jia; Guo, Jie; Shu, Zhi-Feng

    2015-02-01

    A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km–60 km away from ground. Before the inversion of the Doppler shift due to wind, the Rayleigh response function should be calculated, which is a convolution of the laser spectrum, Rayleigh backscattering function, and the transmission function of the Fabry–Perot interferometer used as the frequency discriminator in the lidar. An analysis of the influence of the temperature on the accuracy of the line-of-sight winds shows that real-time temperature profiles are needed because the bandwidth of the Rayleigh backscattering function is temperature-dependent. An integration method is employed in the inversion of the temperature, where the convergence of this method and the high signal-to-noise ratio below 60 km ensure the accuracy and precision of the temperature profiles inverted. Then, real-time and on-site temperature profiles are applied to correct the wind instead of using temperature profiles from a numerical prediction system or atmosphere model. The corrected wind profiles show satisfactory agreement with the wind profiles acquired from radiosondes, proving the reliability of the method. Project supported by the National Natural Science Foundation of China (Grant Nos. 41174130, 41174131, 41274151, and 41304123).

  1. Estimation of bioconcentration factors of nonionic organic compounds in fish by molecular connectivity indices and polarity correction factors.

    PubMed

    Lu, X; Tao, S; Hu, H; Dawson, R W

    2000-11-01

    A bioconcentration factor (BCF) estimation model for a wide range of nonionic organic compounds was developed on the basis of molecular connectivity indices and polarity correction factors. The nonlinear topological modeling using polarity correction factors resulted in the best BCF estimation quality for all of the 239 compounds studied, with a mean absolute estimation error of 0.478 log units. Residual analysis indicated that the estimation errors came from many sources including BCF measurement, test species, and selection of descriptors. Statistical robustness of the developed model was validated by modified jackknifed tests where random deletion of a set of compounds and specific deletion of a class of compounds were both performed. Comparison between the MCI-based (molecular connectivity indices) model and a Kow-based (octanol/water partition coefficient) model revealed that the BCF estimation based on topological parameters was as good as that achieved by Kow. PMID:11057696

  2. Communication: The effect of dispersion corrections on the melting temperature of liquid water

    NASA Astrophysics Data System (ADS)

    Yoo, Soohaeng; Xantheas, Sotiris S.

    2011-03-01

    The melting temperature (Tm) of liquid water with the Becke-Lee-Yang-Parr (BLYP) density functional including dispersion corrections (BLYP-D) and the Thole-type, version 3 (TTM3-F) ab-initio based flexible, polarizable classical potential is reported via constant pressure and constant enthalpy (NPH) molecular dynamics simulations of an ice Ih-liquid coexisting system. Dispersion corrections to BLYP lower Tm to about 360 K, a large improvement over the value of Tm > 400 K previously obtained with the original BLYP functional under the same simulation conditions. For TTM3-F, Tm = 248 K from classical molecular dynamics simulations.

  3. The perturbation correction factors for cylindrical ionization chambers in high-energy photon beams.

    PubMed

    Yoshiyama, Fumiaki; Araki, Fujio; Ono, Takeshi

    2010-07-01

    In this study, we calculated perturbation correction factors for cylindrical ionization chambers in high-energy photon beams by using Monte Carlo simulations. We modeled four Farmer-type cylindrical chambers with the EGSnrc/Cavity code and calculated the cavity or electron fluence correction factor, P (cav), the displacement correction factor, P (dis), the wall correction factor, P (wall), the stem correction factor, P (stem), the central electrode correction factor, P (cel), and the overall perturbation correction factor, P (Q). The calculated P (dis) values for PTW30010/30013 chambers were 0.9967 +/- 0.0017, 0.9983 +/- 0.0019, and 0.9980 +/- 0.0019, respectively, for (60)Co, 4 MV, and 10 MV photon beams. The value for a (60)Co beam was about 1.0% higher than the 0.988 value recommended by the IAEA TRS-398 protocol. The P (dis) values had a substantial discrepancy compared to those of IAEA TRS-398 and AAPM TG-51 at all photon energies. The P (wall) values were from 0.9994 +/- 0.0020 to 1.0031 +/- 0.0020 for PTW30010 and from 0.9961 +/- 0.0018 to 0.9991 +/- 0.0017 for PTW30011/30012, in the range of (60)Co-10 MV. The P (wall) values for PTW30011/30012 were around 0.3% lower than those of the IAEA TRS-398. Also, the chamber response with and without a 1 mm PMMA water-proofing sleeve agreed within their combined uncertainty. The calculated P (stem) values ranged from 0.9945 +/- 0.0014 to 0.9965 +/- 0.0014, but they are not considered in current dosimetry protocols. The values were no significant difference on beam qualities. P (cel) for a 1 mm aluminum electrode agreed within 0.3% with that of IAEA TRS-398. The overall perturbation factors agreed within 0.4% with those for IAEA TRS-398. PMID:20821090

  4. An active power factor correction technique for three-phase diode rectifiers

    Microsoft Academic Search

    A. R. Prasad; Phoivos D. Ziogas; Stefanos Manias

    1991-01-01

    A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It

  5. An active power factor correction technique for three-phase diode rectifiers

    Microsoft Academic Search

    A. R. Prasad; P. D. Ziogas; S. Manias

    1989-01-01

    A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single-switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It is

  6. A single-stage power factor correction switched mode power supply

    Microsoft Academic Search

    Cícero S. Postiglione; Arnaldo J. Perin; Claudinor B. Nascimento

    2007-01-01

    This paper presents a single-stage power factor corrected ac-dc converter based on a half-bridge topology. The proposed converter make use of the charge-pump and interleaving techniques resulting in near unity power factor and ripple free input current, meeting the IEC 61000-3-2 regulations for wide-load ranges. It is also a cost effective and competitive solution for 100 - 600 W applications

  7. A power factor corrected PMBLDCM drive for air-conditioner using bridge converter

    Microsoft Academic Search

    Sanjeev Singh; Bhim Singh

    2010-01-01

    This paper aims at a power factor corrected (PFC) buck bridge DC-DC converter for a permanent magnet brushless DC motor (PMBLDCM) for an air conditioner. This PFC converter is fed from a single-phase AC mains through a diode bridge rectifier (DBR) and connected to a voltage source inverter (VSI) feeding the PMBLDCM. The Speed of the proposed PMBLDCM drive is

  8. The perturbation correction factor of ionisation chambers in beta -radiation fields

    Microsoft Academic Search

    J. Bohm

    1980-01-01

    In determining the absorbed dose in a solid medium by means of gas-filled ionisation chambers, the perturbation of the radiation field by the chamber needs to be taken into account. So far, an appropriate correction factor has neither been calculated nor measured for beta -radiation. This work describes its experimental determination for an extrapolation chamber and beta -radiation fields of

  9. A comparative study on current control methods for load balancing and power factor correction using STATCOM

    Microsoft Academic Search

    Amin Hasanzadeh; Mostafa Parniani; S. Mohammad Reza Sadriyeh

    2005-01-01

    This paper investigates several current control methods for load balancing and power factor correction based on distribution static compensator (STATCOM). Two different configurations are considered for STATCOM; a three leg inverter, and three single phase inverters. It is assumed that the STATCOM is associated with a load that is remote from the supply. After a brief introduction, control structure based

  10. Comparison of Correction Factors for Shell-and-Tube Heat Exchangers with Segmental or Helical Baffles

    Microsoft Academic Search

    P. Stehlík; J. Nemcanský; D. Kral; L. W. Swanson

    1994-01-01

    Heat transfer and pressure drop correction factors based on the Bell-Delaware method have been compared for an optimized segmental baffle heat exchanger and a helical baffle heat exchanger. In general, the results showed that properly designed helical baffles offer a significant improvement in heat transfer while providing a reduced exchanger pressure drop. The enhancement in heat transfer for helical baffles

  11. A DSP based controller for power factor correction (PFC) in a rectifier circuit

    Microsoft Academic Search

    M. Fu; Q. Chen

    2001-01-01

    In this paper a digital signal processor (DSP) based power factor correction (PFC) scheme is presented. A dual-loop controller is designed to control the average input AC current as well as DC bus voltage. The DSP controller is implemented and tested. Design methodologies and trade-offs such as discrete-time implementation methods are also presented

  12. Correcting gene expression data when neither the unwanted variation nor the factor of interest are observed

    E-print Network

    El Karoui, Noureddine

    Correcting gene expression data when neither the unwanted variation nor the factor of interest samples can be used to estimate unwanted variation in gene expression, and discuss how this information methods are then evaluated on three gene expression datasets. They generally manage to remove unwanted

  13. The accuracy of climate models' simulated season lengths and the effectiveness of grid scale correction factors

    SciTech Connect

    Winterhalter, Wade

    2011-09-01

    Global climate change is expected to impact biological populations through a variety of mechanisms including increases in the length of their growing season. Climate models are useful tools for predicting how season length might change in the future. However, the accuracy of these models tends to be rather low at regional geographic scales. Here, I determined the ability of several atmosphere and ocean general circulating models (AOGCMs) to accurately simulate historical season lengths for a temperate ectotherm across the continental United States. I also evaluated the effectiveness of regional-scale correction factors to improve the accuracy of these models. I found that both the accuracy of simulated season lengths and the effectiveness of the correction factors to improve the model's accuracy varied geographically and across models. These results suggest that regional specific correction factors do not always adequately remove potential discrepancies between simulated and historically observed environmental parameters. As such, an explicit evaluation of the correction factors' effectiveness should be included in future studies of global climate change's impact on biological populations.

  14. An attempt to correct strain data measured with vault-housed extensometers under variations in temperature

    NASA Astrophysics Data System (ADS)

    Yamazaki, Ken'ichi

    2013-06-01

    Strain data obtained by vault-housed extensometers have precisions on the order of nanostrains, but they are distorted by variations in temperature, which cause two types of noise: "actual variations" due to the thermo-elastic effect of the Earth's crust, and "false variations" due to the thermal expansion of extensometer, which occurs when the extensometers themselves are subjected to variations in temperature. Here, I explore a method of removing false variations, which are severe when the vault is located at shallow depths. If variations in temperature at arbitrary points inside a vault are estimated, false variations can be removed from the recorded variations in strain. I derive formulae that enable variations in temperature to be estimated at various points in a vault, based on measured variations at reference points. The formulation is valid if some simplification is allowed. I examined whether variations in temperature inside a vault can be estimated in terms of the derived formulae, and obtained the following results. When the reference temperature data are obtained from adequate points in the vault, variations in temperature at another point can be estimated with an accuracy of 0.1 °C. However, when the reference temperature data are obtained from outside the vault, estimated variations in temperature are rather inaccurate, which means that the false variations in strain cannot be removed accurately. Moreover, the data indicate that the thermal diffusivity of the ground is temporally variable, and this introduces another difficulty in correcting false variations in strain data. These results indicate that correcting the distortions in strain data due to variations in temperature is much more difficult than anticipated.

  15. Temperature effects and corrections in volume measurements based on liquid-level detection

    SciTech Connect

    Suda, S.; Keisch, B.

    1993-08-01

    Temperature changes affect volume measurements in several ways. The dimensions of the tank, and the density and level of the liquid it contains vary with temperature. In addition, the response signal of the sensor and hence the response of the liquid-level detection device may change with temperature. Level measurement devices can be grouped according to four measurement points of reference: tip of probe, response proportional to the length of probe, top of tank, and liquid surface. This paper describes the physical principles of pressure, capacitance probe, sonic reflections, and visual scales. These are representative of the four types of liquid level detection techniques. Development of the temperature correction algorithm requires that the measurement process be clearly defined, conditions or limitations specified, and that a temperature-effects test be run. Although not difficult or necessarily time-consuming to run, good practice requires a test plan following demonstrated guidelines. Measurement control procedures for remeasurement of the process solution in the tank during normal operation can provide data to validate temperature correction algorithms.

  16. Neutrino-pair bremsstrahlung in dense stars. III - Low-temperature quantum corrections in the liquid metal phase

    Microsoft Academic Search

    N. Itoh; Y. Kohyama; N. Matsumoto; M. Seki

    1984-01-01

    Low-temperature quantum corrections to the neutrino-pair bremsstrahlung rate are calculated for dense stellar matter in the liquid metal phase. The corrections arise from the quantum nature of semiclassical ions. The numerical results are parameterized in the form of analytic formulae in order to facilitate applications. The typical corrections are on the order of 5 % or less in the density-temperature

  17. Communication: The Effect of Dispersion Corrections on the Melting Temperature of Liquid Water

    SciTech Connect

    Yoo, Soohaeng; Xantheas, Sotiris S.

    2011-03-28

    We report the results of the melting temperature (Tm) of liquid water for the Becke-Lee- Yang-Parr (BLYP) density functional including Dispersion corrections (BLYP-D) and the TTM3-F ab-initio based classical potential via constant pressure and constant enthalpy (NPH) ensemble molecular dynamics simulations of an ice Ih-liquid coexisting system. The inclusion of dispersion corrections to BLYP lowers the melting temperature of liquid water to Tm=360 K, which is a large improvement over the value of Tm > 400 K obtained with the original BLYP functional. The ab-initio based flexible, polarizable Thole-type model (TTM3-F) produces Tm=248 K from classical molecular dynamics simulations.

  18. Many-Electron QED Corrections to the g Factor of Lithiumlike Ions

    NASA Astrophysics Data System (ADS)

    Volotka, A. V.; Glazov, D. A.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.

    2014-06-01

    A rigorous QED evaluation of the two-photon exchange corrections to the g factor of lithiumlike ions is presented. The screened self-energy corrections are calculated for the intermediate-Z region, and its accuracy for the high-Z region is essentially improved in comparison with that of previous calculations. As a result, the theoretical accuracy of the g factor of lithiumlike ions is significantly increased. The theoretical prediction obtained for the g factor of Si2811+ gth=2.000 889 892(8) is in an excellent agreement with the corresponding experimental value gexp=2.000 889 889 9(21) [A. Wagner et al., Phys. Rev. Lett. 110, 033003 (2013)].

  19. Reconstructing past sea surface temperatures: Correcting for diagenesis of bulk marine carbonate

    Microsoft Academic Search

    Daniel P. Schrag; Donald J. DePaolo; Frank M. Richter

    1995-01-01

    A numerical model which describes oxygen isotope exchange during burial and recrystallization of deep-sea carbonate is used to obtain information on how sea surface temperatures have varied in the past by correcting measured ?18O values of bulk carbonate for diagenetic overprinting. Comparison of bulk carbonate and planktonic foraminiferal ?18O records from ODP site 677A indicates that the oxygen isotopic composition

  20. Empirical effective temperatures and bolometric corrections for early-type stars

    NASA Technical Reports Server (NTRS)

    Code, A. D.; Bless, R. C.; Davis, J.; Brown, R. H.

    1976-01-01

    An empirical effective temperature for a star can be found by measuring its apparent angular diameter and absolute flux distribution. The angular diameters of 32 bright stars in the spectral range O5f to F8 have recently been measured with the stellar interferometer at Narrabri Observatory, and their absolute flux distributions have been found by combining observations of ultraviolet flux from the Orbiting Astronomical Observatory (OAO-2) with ground-based photometry. In this paper, these data have been combined to derive empirical effective temperatures and bolometric corrections for these 32 stars.

  1. Bias correction of temperature and precipitation data for regional climate model application to the Rhine basin

    NASA Astrophysics Data System (ADS)

    Terink, W.; Hurkmans, R. T. W. L.; Uijlenhoet, R.; Torfs, P. J. J. F.; Warmerdam, P. M. M.

    2009-04-01

    The Hydrology and Quantitative Water Management group of Wageningen University is involved in the EU research project NeWater. The objective of this project is to develop tools which provide medium range hydrological predictions by coupling catchment-scale water balance models and ensembles from mesoscale climate models. The catchment-scale distributed hydrological model used in this study is the Variable Infiltration Capacity (VIC) model. This hydrological model in combination with an ensemble from the climate model ECHAM5 (developed by Max Plank Institute für Meteorologie (MPI-M), Hamburg) is being used to evaluate the effects of climate change on the hydrological regime of the Rhine basin and to assess the uncertainties involved in the ensembles from the climate model used in this study. Three future scenarios (2001-2100) are used in this study, which are downscaled ECHAM5 runs which were forced by the IPCC carbon emission scenarios B1, A1B and A2. A downscaled ECHAM5 "Climate of the 20th Century" run (1951-2000) is used as the reference climate. Downscaled ERA15 data is used to calibrate the VIC model. Downscaling of both the ECHAM5 and ERA15 model was carried out with the regional climate model REMO at MPI-M to a resolution of 0.088 degrees. The assessment of uncertainties involved in the climate model ensembles is performed by comparing the model (ECHAM5-REMO and ERA15-REMO) ensemble precipitation and temperature data with observations. This resulted in the detection of a bias in both the downscaled reference climate data and downscaled ERA15 data. A bias-correction has been applied to both the downscaled ERA15 data and the reference climate data. This bias-correction corrects for the mean and coefficient of variation for precipitation and the mean and standard deviation for temperature. The results of the applied bias-correction are analyzed spatially and temporally. Despite the fact that the bias-correction only uses two parameters, the coefficient of variation, standard deviation and mean of the bias-corrected data sets showed significant improvements for both precipitation and temperature. Even statistics that were not taken into account in the bias-correction, such as the fraction of wet days, the lag-one autocorrelation and the exceedance probabilities have improved as well.

  2. Source localization corrections for airborne acoustic platforms based on a climatological assessment of temperature and wind velocity profiles

    NASA Astrophysics Data System (ADS)

    Ostashev, Vladimir E.; Cheinet, Sylvain; Collier, Sandra L.; Reiff, Christian; Ligon, David A.; Wilson, D. Keith; Noble, John M.; Alberts, W. C. Kirkpatrick, II

    2012-06-01

    Acoustic sensors are being employed on airborne platforms, such as Persistent Threat Detection System (PTDS) and Persistent Ground Surveillance System (PGSS), for source localization. Under certain atmospheric conditions, airborne sensors oer a distinct advantage over ground sensors. The performance of both ground and airborne sensors is aected by environmental factors, such as atmospheric turbulence and wind and temperature proles. For airborne sensors, the eects of refraction must be accounted for in order to determine the source coordinates. Such a method for ground-to-air applications has been developed and is further rened here. Ideally, knowledge of the exact atmospheric proles will allow for the most accurate mitigation of refractive eects. However, acoustic sensors deployed in theater are rarely supported by atmospheric sensing systems that retrieve real-time temperature and wind elds. Atmospheric conditions evolve through seasons, time of day, and are strongly location dependent. Therefore, the development of an atmospheric proles database based on a long time series climatological assessment will provide knowledge for use in physics-based bearing estimation algorithms, where otherwise no correction would have been performed. Long term atmospheric data sets from weather modeling systems are used for a climatological assessment of the refraction corrections and localization errors over selected sites.

  3. An evaluation of substrate degradation patterns in the composting process. Part 2: temperature-corrected profiles.

    PubMed

    Mason, I G

    2008-01-01

    In this paper, the patterns of 44 substrate degradation profiles obtained from the composting literature are examined following their correction to a constant temperature of 40 degrees C, using a new procedure presented in this work. The applicability of a single exponential model, a double exponential model and a non-logarithmic Gompertz model in describing their behaviour is then evaluated. Multi-phase profiles were most commonly seen, with convex shapes observed in only a relatively small proportion of the profiles. Convex shapes were also embedded within other profiles, either preceeded by a lag phase, or followed by non-convex behaviour. Sigmoidal patterns were relatively rare. Of the temperature-corrected data sets examined, 33 were found to be either not well modelled by, or inappropriate for, any of the above models. Two fits rated as good were obtained when using the single exponential model, and one fit rated as excellent, plus one fit rated as good, were obtained when using the double exponential model. A single fit rated as excellent was found when using the non-logarithmic Gompertz model. The lag phase, which was observed in many data sets, was successfully modelled using the non-logarithmic Gompertz function where excellent and good fits were obtained, but as expected this phase of the profile could not be modelled by either the single or double exponential functions. When the lag phase or post-convex curve data was removed from 20 data sets, use of the single exponential function resulted in three fits rated as excellent and two rated as good. When a double exponential model was applied to these data sets, three fits rated as good were obtained, whilst application of the modified Gompertz model gave one fit rated as good. The remainder of the fits were rated as moderate to fair. It is concluded that the evidence supporting the use of the single exponential model, the double exponential model or the non-logarithmic Gompertz model to describe full substrate degradation profiles in composting following their adjustment for temperature effects is limited. Further work is suggested in order to investigate the nature of those profiles which were not well modelled, to more precisely ascertain the cardinal temperatures for composting used in the function of Rosso et al. (1993) [Rosso, L., Lobry, J.R., Flandrois, J.P., 1993. An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. J. Theor. Biol 162, 447-463.], which was employed in the present temperature correction procedure, and to incorporate correction for varying moisture and oxygen concentrations. PMID:17855070

  4. Frequency Scalable Non-Linear Waveform Generator for Mixed-Simal Power-Factor-Correction IC Controller'

    E-print Network

    Frequency Scalable Non-Linear Waveform Generator for Mixed-Simal Power-Factor-Correction IC mixed-signal IC controller for power-factor-correction (PFC) of high-frequency switching AC controllers have also been proposed [9]-[ll],but are limited to high-power (high-cost), low-frequency

  5. Stress Intensity Factor Plasticity Correction for Flaws in Stress Concentration Regions

    SciTech Connect

    Friedman, E.; Wilson, W.K.

    2000-02-01

    Plasticity corrections to elastically computed stress intensity factors are often included in brittle fracture evaluation procedures. These corrections are based on the existence of a plastic zone in the vicinity of the crack tip. Such a plastic zone correction is included in the flaw evaluation procedure of Appendix A to Section XI of the ASME Boiler and Pressure Vessel Code. Plasticity effects from the results of elastic and elastic-plastic explicit flaw finite element analyses are examined for various size cracks emanating from the root of a notch in a panel and for cracks located at fillet fadii. The results of these caluclations provide conditions under which the crack-tip plastic zone correction based on the Irwin plastic zone size overestimates the plasticity effect for crack-like flaws embedded in stress concentration regions in which the elastically computed stress exceeds the yield strength of the material. A failure assessment diagram (FAD) curve is employed to graphically c haracterize the effect of plasticity on the crack driving force. The Option 1 FAD curve of the Level 3 advanced fracture assessment procedure of British Standard PD 6493:1991, adjusted for stress concentration effects by a term that is a function of the applied load and the ratio of the local radius of curvature at the flaw location to the flaw depth, provides a satisfactory bound to all the FAD curves derived from the explicit flaw finite element calculations. The adjusted FAD curve is a less restrictive plasticity correction than the plastic zone correction of Section XI for flaws embedded in plastic zones at geometric stress concentrators. This enables unnecessary conservatism to be removed from flaw evaluation procedures that utilize plasticity corrections.

  6. Determination of ion recombination correction factors for a liquid ionization chamber in megavoltage photon beams

    NASA Astrophysics Data System (ADS)

    Choi, Sang Hyoun; Kim, Kum-Bae; Ji, Young Hoon; Kim, Chan Hyeong; Kim, Seonghoon; Huh, Hyun Do

    2015-05-01

    The aim of this study is to determine the ion recombination correction factor for a liquid ionization chamber in a high energy photon beam by using our experimental method. The ion recombination correction factors were determined by using our experimental method and were compared with theoretical and experimental methods proposed by using the theoretical method (Greening, Johansson) and the two-dose rate method in a cobalt beam and a high energy photon beam. In order to apply the liquid ionization chamber in a reference and small field dosimetry, we acquired the absorbed dose to water correction coefficient, the beam quality correction factor, and the influence quantities for the microLion chamber according to the TRS-398 protocol and applied the results to a high energy photon beam used in clinical fields. As a result, our experimental method for ion recombination in a cobalt beam agreed with the results from the heoretical method (Greening theory) better than it did with the results from the two-dose rate method. For high energy photon beams, the two-dose rate and our experimental methods were in good agreement, less than 2% deviation, while the theoretical general collection efficiency (Johansson et al.) deviated greatly from the experimental values. When we applied the factors for the absorbed dose to water measurement, the absorbed dose to water for the microLion chamber was in good agreement, within 1%, compared with the values for the PTW 30013 chamber in 6 and 10 MV Clinac iX and 6 and 15 MV Oncor impression. With these results, not only can the microLion ionization chamber be used to measure the absorbed dose to water in a reference condition, it can also be used to a the chamber for small, non-standard field dosimetry.

  7. Digital control of a Full-Bridge — Flyback isolated current rectifier with power factor correction

    Microsoft Academic Search

    Janderson Duarte; Cassiano Rech; Marcello Mezaroba; Leandro Michels

    2009-01-01

    This paper presents the modeling and control of a single-stage isolated current rectifier with power factor correction based on full-bridge and flyback topologies. The state-space averaged model of the converter for step-down and step-up operation modes is presented, as well as the design and analysis of the digital control system. Experimental results based on a 3.5 kW prototype are presented

  8. Power Factor Correction of Direct Torque Controlled Brushless DC Motor Drive

    Microsoft Academic Search

    Salih Baris Ozturk; Oh Yang; H. A. Toliyat

    2007-01-01

    In this paper, an algorithm for power factor correction (PFC) of direct torque control (DTC) brushless dc motor drive in the constant torque region is presented. The proposed DTC approach introduces a two-phase conduction mode as opposed to the conventional three-phase DTC drives. Unlike conventional six-step PWM current control, by properly selecting the inverter voltage space vectors of the two-phase

  9. Comparison of Boundary Correction Factor Solutions for Two Symmetric Cracks in a Straight-Shank Hole

    Microsoft Academic Search

    John G. Bakuckas

    1999-01-01

    Abstract: This report compares the mode I boundary correction factor solutions for two symmetric elliptical cracks emanating from a straight-shank hole. A variety of methods were used to generate the solutions. A global-intermediate-local (GIL) hierarchical approach was developed using the finite element method (FEM). Comparisons were made with the following methods: the FEM with the equivalent domain integral, semiempirical boundary

  10. A soft-switching mode rectifier with power factor correction and high frequency transformer link

    Microsoft Academic Search

    Chang-Ming Liaw; Thin-Huo Chen

    2000-01-01

    This paper presents a soft-switching mode rectifier (SSMR) consisting of a power factor correction zero-voltage-transition-pulse-width-modulated (PFC ZVT-PWM) converter and a high-frequency transformer-coupled DC\\/DC zero voltage switching clamped voltage (ZVS-CV) converter. An easily implemented ZVT soft-switching mechanism is developed to reduce the switching losses and stresses of the power switches in the PFC ZVT-PWM converter. The operations of the proposed SSMR

  11. Current waveform distortion in power factor correction circuits employing discontinuous-mode boost converters

    Microsoft Academic Search

    Kwang-Hwa Liu; Yung-Lin Lin

    1989-01-01

    For active power factor correction circuits employing discontinuous-mode boost converters, the line current will automatically follow the sinusoidal line-voltage waveform. However, due to the modulation of the input inductor current discharging time, there is certain distortion in the AC line-current waveform. It is found that the modulation of inductor current discharging time is a function of the line voltage and

  12. Soft-switched single-switch three-phase rectifier with power factor correction

    Microsoft Academic Search

    Slobodan GatariC; Dushan Boroyevich; Fred C. Lee

    1994-01-01

    Novel, zero-voltage-transition (ZVT) and zero-current-transition (ZCT) topologies of the single-switch three-phase boost power factor correction rectifier are proposed. The soft transition is achieved with a low-power auxiliary circuit employing an additional switch. The ZVT circuit is suitable for MOSFETs operating above 100 kHz, while the ZCT circuit can be used with IGBTs up to 50 kHz. Operation of the ZCT

  13. Correction factors for body mass bias in military physical fitness tests.

    PubMed

    Vanderburgh, Paul M

    2007-07-01

    Recent research findings combined with the theoretical laws of biological similarity make the compelling case that all physical fitness test items for the Army, Air Force, and Navy impose a 15 to 20% physiological bias against heavier, not fatter, men and women. Using the published findings that actual scores of muscle and aerobic endurance scale by body mass raised to the 1/3 power, correction factor tables were developed. This correction factor can be multiplied by one's actual score (e.g., push-ups, sit-ups, abdominal crunches, or curl-up repetitions or distance run time) to yield adjusted scores that are free of body mass bias. These adjusted scores eliminate this bias, become better overall indicators of physical fitness relevant to military tasks, are easily applied to the scoring tables used in the present physical fitness tests, and do not reward body fatness. Use of these correction factors should be explored by all military services to contribute to more relevant fitness tests. PMID:17691687

  14. Nuclear recoil correction to the g factor of boron-like argon

    NASA Astrophysics Data System (ADS)

    Shchepetnov, A. A.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.

    2015-01-01

    The nuclear recoil effect to the g factor of boron-like ions is investigated. The one-photon-exchange correction to the nuclear recoil effect is calculated in the nonrelativistic approximation for the nuclear recoil operator and in the Breit approximation for the interelectronic-interaction operator. The screening potential is employed to estimate the higher-order contributions. The updated g-factor values are presented for the ground 2P1/2 and first excited 2P3/2 states of B-like argon 40Ar13+, which are presently being measured by the ARTEMIS group at GSI.

  15. Correcting infrared satellite estimates of sea surface temperature for atmospheric water vapor attenuation

    NASA Technical Reports Server (NTRS)

    Emery, William J.; Yu, Yunyue; Wick, Gary A.; Schluessel, Peter; Reynolds, Richard W.

    1994-01-01

    A new satellite sea surface temperature (SST) algorithm is developed that uses nearly coincident measurements from the microwave special sensor microwave imager (SSM/I) to correct for atmospheric moisture attenuation of the infrared signal from the advanced very high resolution radiometer (AVHRR). This new SST algorithm is applied to AVHRR imagery from the South Pacific and Norwegian seas, which are then compared with simultaneous in situ (ship based) measurements of both skin and bulk SST. In addition, an SST algorithm using a quadratic product of the difference between the two AVHRR thermal infrared channels is compared with the in situ measurements. While the quadratic formulation provides a considerable improvement over the older cross product (CPSST) and multichannel (MCSST) algorithms, the SSM/I corrected SST (called the water vapor or WVSST) shows overall smaller errors when compared to both the skin and bulk in situ SST observations. Applied to individual AVHRR images, the WVSST reveals an SST difference pattern (CPSST-WVSST) similar in shape to the water vapor structure while the CPSST-quadratic SST difference appears unrelated in pattern to the nearly coincident water vapor pattern. An application of the WVSST to week-long composites of global area coverage (GAC) AVHRR data demonstrates again the manner in which the WVSST corrects the AVHRR for atmospheric moisture attenuation. By comparison the quadratic SST method underestimates the SST corrections in the lower latitudes and overestimates the SST in th e higher latitudes. Correlations between the AVHRR thermal channel differences and the SSM/I water vapor demonstrate the inability of the channel difference to represent water vapor in the midlatitude and high latitudes during summer. Compared against drifting buoy data the WVSST and the quadratic SST both exhibit the same general behavior with the relatively small differences with the buoy temperatures.

  16. Correction factors for source strength determination in HDR brachytherapy using the in-phantom method.

    PubMed

    Ubrich, Frank; Wulff, Jörg; Engenhart-Cabillic, Rita; Zink, Klemens

    2014-05-01

    For the purpose of clinical source strength determination for HDR brachytherapy sources, the German society for Medical Physics (DGMP) recommends in their report 13 the usage of a solid state phantom (Krieger-phantom) with a thimble ionization chamber. In this work, the calibration chain for the determination of the reference air-kerma rate Ka,100 and reference dose rate to waterDw,1 by ionization chamber measurement in the Krieger-phantom was modeled via Monte Carlo simulations. These calculations were used to determine global correction factors k(tot), which allows a user to directly convert the reading of an ionization chamber calibrated in terms of absorbed dose to water, into the desired quantity Ka,100 or Dw,1. The factor k(tot) was determined for four available (192)Ir sources and one (60)Co source with three different thimble ionization chambers. Finally, ionization chamber measurements on three ?Selectron V2 HDR sources within the Krieger-phantom were performed and Ka,100 was determined according to three different methods: 1) using a calibration factor in terms of absorbed dose to water with the global correction factor [Formula: see text] according DGMP 13 2) using a global correction factor calculated via Monte Carlo 3) using a direct reference air-kerma rate calibration factor determined by the national metrology institute PTB. The comparison of Monte Carlo based [Formula: see text] with those from DGMP 13 showed that the DGMP data were systematically smaller by about 2-2.5%. The experimentally determined [Formula: see text] , based on the direct Ka,100 calibration were also systematically smaller by about 1.5%. Despite of these systematical deviations, the agreement of the different methods was in almost all cases within the 1? level of confidence of the interval of their respective uncertainties in a Gaussian distribution. The application of Monte Carlo based [Formula: see text] for the determination of Ka,100 for three ?Selectron V2 sources revealed the smallest deviation to the manufacturer's source certificate. With the calculated [Formula: see text] for a (60)Co source, the user is now able to accurately determine Ka,100 of a HDR (60)Co source via in-phantom measurement. Moreover, using the presented global correction factor [Formula: see text] , the user is able to determine the future source specification quantity Dw,1 with the same in-phantom setup. PMID:24021956

  17. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient

    NASA Astrophysics Data System (ADS)

    Hindasageri, V.; Vedula, R. P.; Prabhu, S. V.

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

  18. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.

    PubMed

    Hindasageri, V; Vedula, R P; Prabhu, S V

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively. PMID:23464237

  19. Monte Carlo calculations of correction factors for plastic phantoms in clinical photon and electron beam dosimetry

    SciTech Connect

    Araki, Fujio; Hanyu, Yuji; Fukuoka, Miyoko; Matsumoto, Kenji; Okumura, Masahiko; Oguchi, Hiroshi [Department of Radiological Technology, Kumamoto University School of Health Sciences, 4-24-1, Kuhonji, Kumamoto, 862-0976 (Japan); Division of Radiation Oncology, Tokyo Women's Medical University Hospital, Tokyo, 162-8666 (Japan); Department of Central Radiology, Kinki University Hospital, Osaka, 589-8511 (Japan); Department of Central Radiology, Shinshu University Hospital, Matsumoto, 390-8621 (Japan)

    2009-07-15

    The purpose of this study is to calculate correction factors for plastic water (PW) and plastic water diagnostic-therapy (PWDT) phantoms in clinical photon and electron beam dosimetry using the EGSnrc Monte Carlo code system. A water-to-plastic ionization conversion factor k{sub pl} for PW and PWDT was computed for several commonly used Farmer-type ionization chambers with different wall materials in the range of 4-18 MV photon beams. For electron beams, a depth-scaling factor c{sub pl} and a chamber-dependent fluence correction factor h{sub pl} for both phantoms were also calculated in combination with NACP-02 and Roos plane-parallel ionization chambers in the range of 4-18 MeV. The h{sub pl} values for the plane-parallel chambers were evaluated from the electron fluence correction factor {phi}{sub pl}{sup w} and wall correction factors P{sub wall,w} and P{sub wall,pl} for a combination of water or plastic materials. The calculated k{sub pl} and h{sub pl} values were verified by comparison with the measured values. A set of k{sub pl} values computed for the Farmer-type chambers was equal to unity within 0.5% for PW and PWDT in photon beams. The k{sub pl} values also agreed within their combined uncertainty with the measured data. For electron beams, the c{sub pl} values computed for PW and PWDT were from 0.998 to 1.000 and from 0.992 to 0.997, respectively, in the range of 4-18 MeV. The {phi}{sub pl}{sup w} values for PW and PWDT were from 0.998 to 1.001 and from 1.004 to 1.001, respectively, at a reference depth in the range of 4-18 MeV. The difference in P{sub wall} between water and plastic materials for the plane-parallel chambers was 0.8% at a maximum. Finally, h{sub pl} values evaluated for plastic materials were equal to unity within 0.6% for NACP-02 and Roos chambers. The h{sub pl} values also agreed within their combined uncertainty with the measured data. The absorbed dose to water from ionization chamber measurements in PW and PWDT plastic materials corresponds to that in water within 1%. Both phantoms can thus be used as a substitute for water for photon and electron dosimetry.

  20. Study of corrections to the geometrical factor in the space charge impedance for the IPNS upgrade

    SciTech Connect

    Harkay, K.C.

    1995-03-17

    Collective instabilities are an important consideration in the 2-GeV rapidly-cycling synchrotron (RCS) of the proposed 1-MW spallation neutron source upgrade due to the very high beam intensity of 1.04{times}10{sup 14} protons per pulse. Collective instabilities are intensity-dependent effects which arise due to the electromagnetic wake fields generated by the beam as it interacts with its surroundings. The interactions are characterized by the coupling impedance, which in the RCS is dominated by space charge effects. To minimize the space charge impedance, the vacuum chamber is constructed with a special wire rf shield. Estimating the longitudinal and transverse impedance due to space charge is critical for the beam stability analysis. The standard geometrical factors used to evaluate the space charge impedance assume a uniform, round, unbunched beam in a cylindrical, smooth beam pipe. Two corrections to the geometrical factors have been proposed to account separately for the wire rf-screening cage and the more realistic varying elliptical beam cross-section. These corrections are studied in the case of the RCS. It is found that including these details results in a correction of less than 20%.

  1. Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments.

    PubMed

    Lee, K W; Sheu, R J

    2015-04-01

    High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6? standard sphere). PMID:25280480

  2. New electron backscatter correction factors for accurate skin depth dose calculation from skin contamination by hot particles.

    PubMed

    Chibani, O

    2001-10-01

    New backscatter correction factors have been calculated using the GEPTS Monte Carlo code system for the case of an isotropic electron point source located at the boundary of a semi-infinite water medium. The backscatter correction factor is defined as the ratio of the dose in a semi-infinite medium to the dose, at the same point, in an infinite medium. It is found that the backscatter correction factor variation with position inside the medium is significant. However, the backscatter correction factor variation with energy is quite small for electron energies less than 1 MeV. The backscatter correction factor data are tabulated for energies of 1, 2, 3, and 4 MeV as functions of radial distance and angular direction. The proposed backscatter correction factors can be used for skin depth-dose calculations from beta particles emitted by either point sources or planar sources. Arbitrary target volumes and beta particle spectra can be considered. The new backscatter correction factors provide an alternative to the current data for accurate skin depth-dose calculations from skin contamination by hot particles. PMID:11569636

  3. Correcting winds measured with a Rayleigh Doppler lidar from pressure and temperature effects

    NASA Astrophysics Data System (ADS)

    Dabas, A.; Denneulin, M. L.; Flamant, P.; Loth, C.; Garnier, A.; Dolfi-Bouteyre, A.

    2008-03-01

    The molecular channel of the space-based Doppler lidar ADM-Aeolus relies on a double Fabry-Perot (FP) interferometer. The difference in photon numbers transmitted by the two FPs divided by their sum- the so-called Rayleigh response-is a function of the central frequency of the spectrum of the laser light backscattered by the atmosphere, so that a proper inversion enables the measurement of Doppler shifts and line-of-sight wind velocities. In this paper, it is shown that the relation-ship between the Rayleigh response and the Doppler shift does not depend on the sole characteristics of the instrument, but also on the atmospheric pressure and temperature (through the Rayleigh-Brillouin effect), and the likely presence of a narrow-band radiation due to particle scattering. The impact of these on the precision of inverted Doppler shifts (or line-of-sight winds) is assessed showing that a correction is needed. As they are lacking the appropriate precision, climatology profiles of pressure, temperature or aerosols cannot be used as an input. It is proposed to use data predicted by a numerical weather prediction system instead. A possible correction scheme is proposed. Its implication on the quality of retrieved Rayleigh winds is discussed.

  4. QCD corrections to $B \\to \\pi$ form factors from light-cone sum rules

    E-print Network

    Wang, Yu-Ming

    2015-01-01

    We compute perturbative corrections to $B \\to \\pi$ form factors from QCD light-cone sum rules with $B$-meson distribution amplitudes. Applying the method of regions we demonstrate factorization of the vacuum-to-$B$-meson correlation function defined with an interpolating current for pion, at one-loop level, explicitly in the heavy quark limit. The short-distance functions in the factorization formulae of the correlation function involves both hard and hard-collinear scales; and these functions can be further factorized into hard coefficients by integrating out the hard fluctuations and jet functions encoding the hard-collinear information. Resummation of large logarithms in the short-distance functions is then achieved via the standard renormalization-group approach. We further show that structures of the factorization formulae for $f_{B \\pi}^{+}(q^2)$ and $f_{B \\pi}^{0}(q^2)$ at large hadronic recoil from QCD light-cone sum rules match that derived in QCD factorization. In particular, we perform an explorato...

  5. Factor analysis for spillover correction or movement detection in dynamic PET studies

    NASA Astrophysics Data System (ADS)

    Wu, Han-Ming; Hoh, Carl K.; Huang, Sung-Cheng

    1996-04-01

    In this study, we applied factor analysis of dynamic structures (FADS) techniques in dynamic PET images to (1) extract the arterial time activity curve (TAC) from human adult or small monkey dynamic FDG PET; and (2) investigate the use of FADS generated factor images and factor curves to detect large subject movements during dynamic GA-68 EDTA scans of brain tumor patients. The results showed that a blood sample constraint improved the accuracy of FADS technique in extracting the `pure' blood pool TAC from dynamic PET studies that have large spillover problems. The studies of GA-68 EDTA brain PET studies showed that three major factors were extracted from images using FADS. For studies with little patient movement, a standard pattern of three factor curves and three factor images were obtained. However, large patient movement changed the outcomes of FADS results. We conclude that (1) FADS technique with a blood sample allows the extraction of the `pure' blood pool TAC directly from quantitative PET images without requiring multiple blood samples, region-of- interest drawing or spillover correction; and (2) FADS technique provides a sensitive way to detect large patient movements in dynamic PET studies.

  6. Reliability of IGBT in a STATCOM for Harmonic Compensation and Power Factor Correction

    SciTech Connect

    Gopi Reddy, Lakshmi Reddy [ORNL; Tolbert, Leon M [ORNL; Ozpineci, Burak [ORNL; Xu, Yan [ORNL; Rizy, D Tom [ORNL

    2012-01-01

    With smart grid integration, there is a need to characterize reliability of a power system by including reliability of power semiconductors in grid related applications. In this paper, the reliability of IGBTs in a STATCOM application is presented for two different applications, power factor correction and harmonic elimination. The STATCOM model is developed in EMTP, and analytical equations for average conduction losses in an IGBT and a diode are derived and compared with experimental data. A commonly used reliability model is used to predict reliability of IGBT.

  7. Measured inhomogeneity correction factors for lung in electron beam treatments of the chest wall

    SciTech Connect

    Moldon, C.; El-Khatib, E. (McGill Univ., Montreal (Canada))

    1989-01-01

    A set of clinically relevant measurements of percentage depth dose and inhomogeneity correction factors for electron beam irradiation of the chest wall and underlying lung is given. Electron beam nominal energies of 9, 12, 15, and 18 MeV and lung densities of 0.22 g/cm{sup 3} and 0.404 g/cm{sup 3} are considered. This data can serve in treatment planning to indicate the penetration of the beam into the lung and serve as a comparison for calculation algorithms which are used to calculate electron dose absorption in heterogeneous phantoms.

  8. Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation

    SciTech Connect

    Collell, Julien; Galliero, Guillaume, E-mail: guillaume.galliero@univ-pau.fr [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR-5150 with CNRS and Total, Université de Pau et des Pays de l'Adour, BP 1155, 64013 Pau (France)] [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR-5150 with CNRS and Total, Université de Pau et des Pays de l'Adour, BP 1155, 64013 Pau (France)

    2014-05-21

    The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. [“Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects,” Mol. Phys. 110, 1069–1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effects of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations.

  9. Experimental setup for the determination of the correction factors of the neutron doseratemeters in fast neutron fields

    SciTech Connect

    Iliescu, Elena; Bercea, Sorin; Dudu, Dorin; Celarel, Aurelia [National Institute of R and D for Physics and Nuclear Engineering-Horia Hulubei, Reactorului 30 St, P.O.BOX MG-6,Magurele, cod 077125 (Romania)

    2013-12-16

    The use of the U-120 Cyclotron of the IFIN-HH allowed to perform a testing bench with fast neutrons in order to determine the correction factors of the doseratemeters dedicated to neutron measurement. This paper deals with researchers performed in order to develop the irradiation facility testing the fast neutrons flux generated at the Cyclotron. This facility is presented, together with the results obtain in determining the correction factor for a doseratemeter dedicated to the neutron dose equivalent rate measurement.

  10. Nuclear and QED corrections to the bound-electron g factor

    NASA Astrophysics Data System (ADS)

    Zatorski, Jacek; Oreshkina, Natalia S.; Keitel, Christoph H.; Harman, Zoltán

    2012-06-01

    We calculate nuclear shape and quantum electrodynamic corrections to the g factor of a bound electron [1,2]. These theoretical studies are motivated by the current improvement of experimental possibilities: on the one hand, in a recent Penning trap measurement [2], the g factor of ^28Si^13+ has been determined with an unprecedented 5 .10-10 relative uncertainty. A novel experimental technique will further improve accuracy to the 10-11 level. On the other hand, experiments with ions as heavy as ^238U^91+ will be performed soon at the HITRAP-FAIR facility. For such heavy ions, nuclear effects play an important role. The leading relativistic nuclear deformation correction has been derived analytically and also its influence on one-loop quantum electrodynamic terms has been evaluated. We present results for medium- and high-Z hydrogenlike ions, which become significant already for mid-Z ions, and for very heavy elements it even reaches the 10-6 level, as we show in [1].[4pt] [1] J. Zatorski, N. S. Oreshkina, C. H. Keitel, and Z. Harman, Phys. Rev. Lett., in press; arXiv:1110.3330 [2] S. Sturm, A. Wagner, B. Schabinger, J. Zatorski, et al., Phys. Rev. Lett. 107, 023002 (2011).

  11. Correction factors for the INER-improved free-air ionization chambers calculated with the Monte Carlo method.

    PubMed

    Lin, Uei-Tyng; Chu, Chien-Hau

    2006-05-01

    Monte Carlo method was used to simulate the correction factors for electron loss and scattered photons for two improved cylindrical free-air ionization chambers (FACs) constructed at the Institute of Nuclear Energy Research (INER, Taiwan). The method is based on weighting correction factors for mono-energetic photons with X-ray spectra. The newly obtained correction factors for the medium-energy free-air chamber were compared with the current values, which were based on a least-squares fit to experimental data published in the NBS Handbook 64 [Wyckoff, H.O., Attix, F.H., 1969. Design of free-air ionization chambers. National Bureau Standards Handbook, No. 64. US Government Printing Office, Washington, DC, pp. 1-16; Chen, W.L., Su, S.H., Su, L.L., Hwang, W.S., 1999. Improved free-air ionization chamber for the measurement of X-rays. Metrologia 36, 19-24]. The comparison results showed the agreement between the Monte Carlo method and experimental data is within 0.22%. In addition, mono-energetic correction factors for the low-energy free-air chamber were calculated. Average correction factors were then derived for measured and theoretical X-ray spectra at 30-50 kVp. Although the measured and calculated spectra differ slightly, the resulting differences in the derived correction factors are less than 0.02%. PMID:16427292

  12. Monte Carlo calculated and experimentally determined output correction factors for small field detectors in Leksell Gamma Knife Perfexion beams

    NASA Astrophysics Data System (ADS)

    Benmakhlouf, H.; Johansson, J.; Paddick, I.; Andreo, P.

    2015-05-01

    The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the international formalism published by Alfonso (2008 Med. Phys. 35 5179–86), standardize the determination of OFs for small photon beams by correcting detector-reading ratios to yield OFs in terms of absorbed-dose ratios. In this work output correction factors for a number of detectors have been determined for LGK Perfexion™ 60Co ?-ray beams by Monte Carlo (MC) calculations and measurements. The calculations were made with the MC system PENELOPE, scoring the energy deposited in the active volume of the detectors and in a small volume of water; the detectors simulated were two silicon diodes, one liquid ionization chamber (LIC), alanine and TLD. The calculated LIC output correction factors were within?±?0.4%, and this was selected as the reference detector for experimental determinations where output correction factors for twelve detectors were measured, normalizing their readings to those of the LIC. The MC-calculated and measured output correction factors for silicon diodes yielded corrections of up to 5% for the smallest LGK collimator size of 4 mm diameter. The air ionization chamber measurements led to extremely large output correction factors, caused by the well-known effect of partial volume averaging. The corrections were up to 7% for the natural diamond detector in the 4 mm collimator, also due to partial volume averaging, and decreased to within about?±?0.6% for the smaller synthetic diamond detector. The LIC, showing the smallest corrections, was used to investigate machine-to-machine output factor differences by performing measurements in four LGK units with different dose rates. These resulted in OFs within?±?0.6% and?±?0.2% for the 4 mm and 8 mm collimators, respectively, providing evidence for the use of generic OFs for these LGK beams. Using the experimentally derived output correction factors, OFs can be measured using a wide range of commercially available detectors.

  13. Monte Carlo calculated and experimentally determined output correction factors for small field detectors in Leksell Gamma Knife Perfexion beams.

    PubMed

    Benmakhlouf, H; Johansson, J; Paddick, I; Andreo, P

    2015-05-21

    The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the international formalism published by Alfonso (2008 Med. Phys. 35 5179-86), standardize the determination of OFs for small photon beams by correcting detector-reading ratios to yield OFs in terms of absorbed-dose ratios. In this work output correction factors for a number of detectors have been determined for LGK Perfexion™ (60)Co ?-ray beams by Monte Carlo (MC) calculations and measurements. The calculations were made with the MC system PENELOPE, scoring the energy deposited in the active volume of the detectors and in a small volume of water; the detectors simulated were two silicon diodes, one liquid ionization chamber (LIC), alanine and TLD. The calculated LIC output correction factors were within?±?0.4%, and this was selected as the reference detector for experimental determinations where output correction factors for twelve detectors were measured, normalizing their readings to those of the LIC. The MC-calculated and measured output correction factors for silicon diodes yielded corrections of up to 5% for the smallest LGK collimator size of 4 mm diameter. The air ionization chamber measurements led to extremely large output correction factors, caused by the well-known effect of partial volume averaging. The corrections were up to 7% for the natural diamond detector in the 4 mm collimator, also due to partial volume averaging, and decreased to within about?±?0.6% for the smaller synthetic diamond detector. The LIC, showing the smallest corrections, was used to investigate machine-to-machine output factor differences by performing measurements in four LGK units with different dose rates. These resulted in OFs within?±?0.6% and?±?0.2% for the 4 mm and 8 mm collimators, respectively, providing evidence for the use of generic OFs for these LGK beams. Using the experimentally derived output correction factors, OFs can be measured using a wide range of commercially available detectors. PMID:25909660

  14. Gravity Dual Corrections to the Heavy Quark Potential at Finite-Temperature

    E-print Network

    Hovhannes R. Grigoryan; Yuri V. Kovchegov

    2011-06-23

    We apply gauge/gravity duality to compute $1/N^2_c$ corrections to the heavy quark potentials of a quark--anti-quark pair ($Q\\bar Q$) and of a quark--quark pair ($QQ$) immersed into the strongly coupled N = 4 SYM plasma. On the gravity side these corrections come from the exchanges of supergravity modes between two string worldsheets stretching from the UV boundary of AdS space to the black hole horizon in the bulk and smeared over $S^5$. We find that the contributions to the $Q\\bar Q$ potential coming from the exchanges of all of the relevant modes (such as dilaton, massive scalar, 2-form field, and graviton) are all attractive, leading to an attractive net $Q\\bar Q$ potential. We show that at large separations $r$ and/or high-temperature $T$ the potential is of Yukawa-type, dominated by the graviton exchange, in agreement with earlier findings. On the other hand, at small-$r T$ the $Q\\bar Q$ potential scales as $\\sim (1/r) \\ln (1/rT)$. In the case of $QQ$ potential the 2-form contribution changes sign and becomes repulsive: however, the net $QQ$ potential remains attractive. At large-$r T$ it is dominated by the graviton exchange, while at small-$r T$ the $QQ$ potential becomes Coulomb-like.

  15. Temperature variation of the structure factor of liquid helium

    NASA Astrophysics Data System (ADS)

    Isihara, A.

    1981-07-01

    The temperature variation of the structure factor S( q) of liquid helium follows S(q) = h?2q 2{{1 + 2f(?)}}/{2}m? , where f(?) is the Bose distribution function of the quasiparticles of energy ?( q). For very low temperatures, the formula predicts that S( q) increases linearly with q starting from a constant, S(0) = {kT}/{mc 2}. This trend changes at temperatures higher than T I = {c h?}/{k}?24? 1, where ? 1 is the coefficient to q2 of the energy dispersion relation. Therefore, above around 2.78 K, a minimum of S( q) is expected. These theoretical predictions are in good agreement with the recent experimental data of Sears, Svensson, Woods and Martel based on neutron diffraction and of Hallock obtained by X-ray scattering.

  16. Meson-nucleon vertex form factors at finite temperature using a soft pion form factor

    Microsoft Academic Search

    U. T. Yakhshiev; A. W. Thomas; F. C. Khanna

    2003-01-01

    The temperature and density dependence of the meson-nucleon vertex form factors is studied in the framework of thermofield dynamics. Results are obtained for two rather different nucleon-nucleon potentials: the usual Bonn potential and the variation with a softer piNN form factor, due to Holinde and Thomas. In general, the results show only a modest degree of sensitivity to the choice

  17. Aerosol Correction for Remotely Sensed Sea Surface Temperatures From the NOAA AVHRR: Phase II

    NASA Astrophysics Data System (ADS)

    Nalli, N. R.; Ignatov, A.

    2002-05-01

    For over two decades, the National Oceanic and Atmospheric Administration (NOAA) has produced global retrievals of sea surface temperature (SST) using infrared (IR) data from the Advanced Very High Resolution Radiometer (AVHRR). The standard multichannel retrieval algorithms are derived from regression analyses of AVHRR window channel brightness temperatures against in situ buoy measurements under non-cloudy conditions thus providing a correction for IR attenuation due to molecular water vapor absorption. However, for atmospheric conditions with elevated aerosol levels (e.g., arising from dust, biomass burning and volcanic eruptions), such algorithms lead to significant negative biases in SST because of IR attenuation arising from aerosol absorption and scattering. This research presents the development of a 2nd-phase aerosol correction algorithm for daytime AVHRR SST. To accomplish this, a long-term (1990-1998), global AVHRR-buoy matchup database was created by merging the Pathfinder Atmospheres (PATMOS) and Oceans (PFMDB) data sets. The merged data are unique in that they include multi-year, global daytime estimates of aerosol optical depth (AOD) derived from AVHRR channels 1 and 2 (0.63 and 0.83 ? m, respectively), along with an effective Angstrom exponent derived from the AOD retrievals (Ignatov and Nalli, 2002). Recent enhancements in the aerosol data constitute an improvement over the Phase I algorithm (Nalli and Stowe, 2002) which relied only on channel 1 AOD and the ratio of normalized reflectance from channels 1 and 2. The Angstrom exponent and channel 2 AOD provide important statistical information about the particle size distribution of the aerosol. The SST bias can be parametrically expressed as a function of observed AVHRR channels 1 and 2 slant-path AOD, normalized reflectance ratio and the Angstrom exponent. Based upon these empirical relationships, aerosol correction equations are then derived for the daytime multichannel and nonlinear SST (MCSST and NLSST) algorithms. Separate sets of coefficients are utilized for two aerosol modes, these being stratospheric/tropospheric (e.g., volcanic aerosol) and tropospheric (e.g., dust, smoke). The algorithms are subsequently applied to retrospective PATMOS data to demonstrate the potential for climate applications. The minimization of cold biases in the AVHRR SST, as demonstrated in this work, should improve its overall utility for the general user community.

  18. Electrical and thermal conductivities of dense matter in the liquid metal phase. II - Low-temperature quantum corrections

    Microsoft Academic Search

    S. Mitake; S. Ichimaru; N. Itoh

    1984-01-01

    Corrections to the transport coefficients of the dense matter due to the quantum nature of semiclassical ions, using the frequency-moment sum rules and the Wigner expansion in powers of h\\/2 pi for the ionic correlation function are calculated. The numerical results are parameterized in analytic formulas. The corrections are less than 20 percent in the density-temperature region where the present

  19. Design and real time implementation of single phase boost power factor correction converter.

    PubMed

    Bouafassa, Amar; Rahmani, Lazhar; Mekhilef, Saad

    2015-03-01

    This paper presents a real time implementation of the single-phase power factor correction (PFC) AC-DC boost converter. A combination of higher order sliding mode controller based on super twisting algorithm and predictive control techniques are implemented to improve the performance of the boost converter. Due to the chattering effects, the higher order sliding mode control (HOSMC) is designed. Also, the predictive technique is modified taking into account the large computational delays. The robustness of the controller is verified conducting simulation in MATLAB, the results show good performances in both steady and transient states. An experiment is conducted through a test bench based on dSPACE 1104. The experimental results proved that the proposed controller enhanced the performance of the converter under different parameters variations. PMID:25457043

  20. Separating temperature from other factors in phenological measurements.

    PubMed

    Schwartz, Mark D; Hanes, Jonathan M; Liang, Liang

    2014-09-01

    Phenological observations offer a simple and effective way to measure climate change effects on the biosphere. While some species in northern mixed forests show a highly sensitive site preference to microenvironmental differences (i.e., the species is present in certain areas and absent in others), others with a more plastic environmental response (e.g., Acer saccharum, sugar maple) allow provisional separation of the universal "background" phenological variation caused by in situ (possibly biological/genetic) variation from the microclimatic gradients in air temperature. Moran's I tests for spatial autocorrelation among the phenological data showed significant (????0.05) clustering across the study area, but random patterns within the microclimates themselves, with isolated exceptions. In other words, the presence of microclimates throughout the study area generally results in spatial autocorrelation because they impact the overall phenological development of sugar maple trees. However, within each microclimate (where temperature conditions are relatively uniform) there is little or no spatial autocorrelation because phenological differences are due largely to randomly distributed in situ factors. The phenological responses from 2008 and 2009 for two sugar maple phenological stages showed the relationship between air temperature degree-hour departure and phenological change ranged from 0.5 to 1.2 days earlier for each additional 100 degree-hours. Further, the standard deviations of phenological event dates within individual microclimates (for specific events and years) ranged from 2.6 to 3.8 days. Thus, that range of days is inferred to be the "background" phenological variation caused by factors other than air temperature variations, such as genetic differences between individuals. PMID:23995622

  1. Replacement correction factors for plane-parallel ion chambers in electron beams

    SciTech Connect

    Wang, Lilie L. W.; Rogers, David W. O. [Ottawa Carleton Institute of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada)

    2010-02-15

    Purpose: Plane-parallel chambers are recommended by dosimetry protocols for measurements in (especially low-energy) electron beams. In dosimetry protocols, the replacement correction factor P{sub repl} is assumed unity for ''well-guarded'' plane-parallel chambers in electron beams when the front face of the cavity is the effective point of measurement. There is experimental evidence that ion chambers which are not well-guarded (e.g., Markus) have nonunity P{sub repl} values. Monte Carlo simulations are employed in this study to investigate the replacement correction factors for plane-parallel chambers in electron beams. Methods: Using previously established Monte Carlo calculation methods, the values of P{sub repl} are calculated with high statistical precision for the cavities of a variety of plane-parallel chambers in a water phantom irradiated by various electron beams. The dependences of the values of P{sub repl} on the beam quality, phantom depth, as well as the guard ring width are studied. Results: In the dose fall-off region for low-energy beams, the P{sub repl} values are very sensitive to depth. It is found that this is mainly due to the gradient effect, which originates from the fact that the effective point of measurement for many plane-parallel chambers should not be at the front face of the cavity but rather shifted toward the center of the cavity by a fraction of a millimeter. Using the front face of the cavity as the effective point of measurement, the calculated values of P{sub repl} at d{sub ref} are not unity for some well-guarded plane-parallel chambers. The calculated P{sub repl} values for the Roos chamber are close to 1 for all electron beams. The calculation results for the Markus chamber are in good agreement with the measured values. Conclusions: The appropriate selection of the effective point of measurement for plane-parallel chambers in electron beams is an important issue. If the effective point of measurement is correctly accounted for, the P{sub repl} values would be almost independent of depth. Both the guard ring width and the ratio of the collecting volume diameter to the cavity thickness can influence the values of P{sub repl}. For a diameter to thickness ratio of 5 (e.g., NACP02 chamber), the guard width has to be 6 mm for the chamber to be considered as well-guarded, i.e., have a P{sub repl} value of 1.00.

  2. Error Detection, Factorization and Correction for Multi-View Scene Reconstruction from Aerial Imagery

    SciTech Connect

    Hess-Flores, M

    2011-11-10

    Scene reconstruction from video sequences has become a prominent computer vision research area in recent years, due to its large number of applications in fields such as security, robotics and virtual reality. Despite recent progress in this field, there are still a number of issues that manifest as incomplete, incorrect or computationally-expensive reconstructions. The engine behind achieving reconstruction is the matching of features between images, where common conditions such as occlusions, lighting changes and texture-less regions can all affect matching accuracy. Subsequent processes that rely on matching accuracy, such as camera parameter estimation, structure computation and non-linear parameter optimization, are also vulnerable to additional sources of error, such as degeneracies and mathematical instability. Detection and correction of errors, along with robustness in parameter solvers, are a must in order to achieve a very accurate final scene reconstruction. However, error detection is in general difficult due to the lack of ground-truth information about the given scene, such as the absolute position of scene points or GPS/IMU coordinates for the camera(s) viewing the scene. In this dissertation, methods are presented for the detection, factorization and correction of error sources present in all stages of a scene reconstruction pipeline from video, in the absence of ground-truth knowledge. Two main applications are discussed. The first set of algorithms derive total structural error measurements after an initial scene structure computation and factorize errors into those related to the underlying feature matching process and those related to camera parameter estimation. A brute-force local correction of inaccurate feature matches is presented, as well as an improved conditioning scheme for non-linear parameter optimization which applies weights on input parameters in proportion to estimated camera parameter errors. Another application is in reconstruction pre-processing, where an algorithm detects and discards frames that would lead to inaccurate feature matching, camera pose estimation degeneracies or mathematical instability in structure computation based on a residual error comparison between two different match motion models. The presented algorithms were designed for aerial video but have been proven to work across different scene types and camera motions, and for both real and synthetic scenes.

  3. Comparisons of image quality factors for phase aberration correction with diffuse and point targets: theory and experiments

    Microsoft Academic Search

    D. Zhao; G. E. Trahey

    1991-01-01

    The use of several alternative image-brightness-based quality factors for phase aberration correction with diffuse and point targets in coherent ultrasonic imaging systems is explored. The factors are similar to the sharpness functions proposed by R.A. Muller et al. (1974) for incoherent imaging systems. Different region of interest (ROI) sizes are used to compare the quality factors. Good agreement is found

  4. Region of validity of the finite–temperature Thomas–Fermi model with respect to quantum and exchange corrections

    SciTech Connect

    Dyachkov, Sergey, E-mail: serj.dyachkov@gmail.com [Joint Institute for High Temperatures RAS, Izhorskaya 13 bldg. 2, Moscow 125412 (Russian Federation) [Joint Institute for High Temperatures RAS, Izhorskaya 13 bldg. 2, Moscow 125412 (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow Region 141700 (Russian Federation); Levashov, Pavel, E-mail: pasha@ihed.ras.ru [Joint Institute for High Temperatures RAS, Izhorskaya 13 bldg. 2, Moscow 125412 (Russian Federation) [Joint Institute for High Temperatures RAS, Izhorskaya 13 bldg. 2, Moscow 125412 (Russian Federation); Tomsk State University, 36 Lenin Prospekt, Tomsk 634050 (Russian Federation)

    2014-05-15

    We determine the region of applicability of the finite–temperature Thomas–Fermi model and its thermal part with respect to quantum and exchange corrections. Very high accuracy of computations has been achieved by using a special approach for the solution of the boundary problem and numerical integration. We show that the thermal part of the model can be applied at lower temperatures than the full model. Also we offer simple approximations of the boundaries of validity for practical applications.

  5. Systematic uncertainties in the Monte Carlo calculation of ion chamber replacement correction factors.

    PubMed

    Wang, L L W; La Russa, D J; Rogers, D W O

    2009-05-01

    In a previous study [Med. Phys. 35, 1747-1755 (2008)], the authors proposed two direct methods of calculating the replacement correction factors (P(repl) or P(cav)P(dis)) for ion chambers by Monte Carlo calculation. By "direct" we meant the stopping-power ratio evaluation is not necessary. The two methods were named as the high-density air (HDA) and low-density water (LDW) methods. Although the accuracy of these methods was briefly discussed, it turns out that the assumption made regarding the dose in an HDA slab as a function of slab thickness is not correct. This issue is reinvestigated in the current study, and the accuracy of the LDW method applied to ion chambers in a 60Co photon beam is also studied. It is found that the two direct methods are in fact not completely independent of the stopping-power ratio of the two materials involved. There is an implicit dependence of the calculated P(repl) values upon the stopping-power ratio evaluation through the choice of an appropriate energy cutoff delta, which characterizes a cavity size in the Spencer-Attix cavity theory. Since the delta value is not accurately defined in the theory, this dependence on the stopping-power ratio results in a systematic uncertainty on the calculated P(repl) values. For phantom materials of similar effective atomic number to air, such as water and graphite, this systematic uncertainty is at most 0.2% for most commonly used chambers for either electron or photon beams. This uncertainty level is good enough for current ion chamber dosimetry, and the merits of the two direct methods of calculating P(repl) values are maintained, i.e., there is no need to do a separate stopping-power ratio calculation. For high-Z materials, the inherent uncertainty would make it practically impossible to calculate reliable P(repl) values using the two direct methods. PMID:19544797

  6. Meson-nucleon vertex form factors at finite temperature using a soft pion form factor

    Microsoft Academic Search

    U. T. Yakhshiev; A. W. Thomas; F. C. Khanna

    2003-01-01

    The temperature and density dependence of the meson-nucleon vertex form\\u000afactors is studied in the framework of thermofield dynamics. Results are\\u000aobtained for two rather different nucleon-nucleon potentials: the usual Bonn\\u000apotential and the variation with a softer $\\\\pi NN$ form factor, due to Holinde\\u000aand Thomas. In general, the results show only a modest degree of sensitivity to\\u000athe

  7. An investigation of factors affecting detector and geometric correction in normalisation of 3D PET data

    Microsoft Academic Search

    D. L. Bailey; D. W. Townsend; P. E. Kinahan; S. Grootoonk; T. Jones

    1995-01-01

    Normalisation in 3D PET comprises two aspects: correction for differential detector response and correction for geometric effects. Comparison of rotating rod source and uniform cylinder data suggest that the position of the source used to correct for sensitivity should be similar to that of the emission data. A plane source method has been devised which uses a moving line source

  8. An investigation of factors affecting detector and geometric correction in normalization of 3-D PET data

    Microsoft Academic Search

    Dale L. Bailey; David W. Townsend; Paul E. Kinahan; Sylke Grootoonk; Terry Jones

    1996-01-01

    Normalization in three-dimensional (3-D) positron emission tomography (PET) comprises two aspects: correction for differential detector response and correction for geometric effects. Comparison of rotating rod source and uniform cylinder data suggests that the position of the source used to correct for sensitivity should be similar to that of the emission data. A plane source method has been devised that uses

  9. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations.

    PubMed

    Palmans, H; Al-Sulaiti, L; Andreo, P; Shipley, D; Lühr, A; Bassler, N; Martinkovi?, J; Dobrovodský, J; Rossomme, S; Thomas, R A S; Kacperek, A

    2013-05-21

    The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024·zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024·zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues. PMID:23629423

  10. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Palmans, H.; Al-Sulaiti, L.; Andreo, P.; Shipley, D.; Lühr, A.; Bassler, N.; Martinkovi?, J.; Dobrovodský, J.; Rossomme, S.; Thomas, R. A. S.; Kacperek, A.

    2013-05-01

    The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024???zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024???zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues.

  11. Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-main-sequence Stars

    NASA Astrophysics Data System (ADS)

    Pecaut, Mark J.; Mamajek, Eric E.

    2013-09-01

    We present an analysis of the intrinsic colors and temperatures of 5-30 Myr old pre-main-sequence (pre-MS) stars using the F0- through M9-type members of nearby, negligibly reddened groups: the ? Cha cluster, the TW Hydra Association, the ? Pic Moving Group, and the Tucana-Horologium Association. To check the consistency of spectral types from the literature, we estimate new spectral types for 52 nearby pre-MS stars with spectral types F3 through M4 using optical spectra taken with the SMARTS 1.5 m telescope. Combining these new types with published spectral types and photometry from the literature (Johnson-Cousins BVIC , 2MASS JHKS and WISE W1, W2, W3, and W4), we derive a new empirical spectral type-color sequence for 5-30 Myr old pre-MS stars. Colors for pre-MS stars match dwarf colors for some spectral types and colors, but for other spectral types and colors, deviations can exceed 0.3 mag. We estimate effective temperatures (T eff) and bolometric corrections (BCs) for our pre-MS star sample through comparing their photometry to synthetic photometry generated using the BT-Settl grid of model atmosphere spectra. We derive a new T eff and BC scale for pre-MS stars, which should be a more appropriate match for T Tauri stars than often-adopted dwarf star scales. While our new T eff scale for pre-MS stars is within sime100 K of dwarfs at a given spectral type for stars

  12. Risk factors for adjacent segment degeneration after surgical correction of degenerative lumbar scoliosis

    PubMed Central

    Ha, Kee-yong; Son, Jong-Min; Im, Jin-Hyung; Oh, In-Soo

    2013-01-01

    Background: Degenerative lumbar scoliosis surgery can lead to development of adjacent segment degeneration (ASD) after lumbar or thoracolumbar fusion. Its incidence, risk factors, morbidity and correlation between radiological and clinical symptoms of ASD have no consensus. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and certain imperative parameters. Materials and Methods: 98 patients who had undergone surgical correction and lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative lumbar scoliosis with a minimum 5 year followup were included in the study. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and imperative patient parameters like age at operation, sex, body mass index (BMI), medical comorbidities and bone mineral density (BMD). The radiological parameters taken into consideration were Cobb's angle, angle type, lumbar lordosis, pelvic incidence, intercristal line, preoperative existence of an ASD on plain radiograph and magnetic resonance imaging (MRI) and surgical parameters were number of the fusion level, decompression level, floating OP (interlumbar fusion excluding L5-S1 level) and posterolateral lumbar interbody fusion (PLIF). Clinical outcomes were assessed with the Visual Analogue Score (VAS) and Oswestry Disability Index (ODI). Results: ASD was present in 44 (44.9%) patients at an average period of 48.0 months (range 6-98 months). Factors related to occurrence of ASD were preoperative existence of disc degeneration (as revealed by MRI) and age at operation (P = 0.0001, 0.0364). There were no statistically significant differences between radiological adjacent segment degeneration and clinical results (VAS, P = 0.446; ODI, P = 0.531). Conclusions: Patients over the age of 65 years and with preoperative disc degeneration (as revealed by plain radiograph and MRI) were at a higher risk of developing ASD. PMID:23960277

  13. Continuous correction of differential path length factor in near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Talukdar, Tanveer; Moore, Jason H.; Diamond, Solomon G.

    2013-05-01

    In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p<0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p<0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method.

  14. Continuous correction of differential path length factor in near-infrared spectroscopy.

    PubMed

    Talukdar, Tanveer; Moore, Jason H; Diamond, Solomon G

    2013-05-01

    In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p < 0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p < 0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method. PMID:23640027

  15. Continuous correction of differential path length factor in near-infrared spectroscopy

    PubMed Central

    Talukdar, Tanveer; Moore, Jason H.; Diamond, Solomon G.

    2013-01-01

    Abstract. In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p<0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p<0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method. PMID:23640027

  16. The effect of oblique rain on inclined surfaces: A nomograph for the rain-gauge correction factor

    NASA Astrophysics Data System (ADS)

    de Lima, J. L. M. P.

    1990-07-01

    Inclined rainfall leads to errors in the assessment of effective precipitation in areas with rugged relief. This affects many hydrological studies such as hydrological forecasts, water erosion, determination of conditions for flash flood formation, determination of cropping conditions, etc. In this paper a nomograph is presented for the rain-gauge correction factor ( Cgau), by which rainfall measured in a standard horizontal rain-gauge ( Pgau) may be corrected to obtain the rainfall flux actually received on the inclined surface under study ( Pact = Cgau × Pgau). The correction factor is assumed to be a function of wind (with constant wind velocity), type of rainfall, and inclination and orientation of the sloping surface with respect to the oblique rain.

  17. A new hybrid filter to dampen resonances and compensate harmonic currents in industrial power systems with power factor correction equipment

    Microsoft Academic Search

    Dirk Detjen; Joep Jacobs; Rik W. De Doncker; Hans-Georg Mall

    2001-01-01

    A new hybrid power filter is presented for three phase industrial power systems which include passive power factor correction equipment (PFC). The hybrid filter damps resonances occurring between line impedances and the PFC. In addition, the hybrid filter topology can be used to compensate harmonic currents. The capacitors of the PFC, which generally cause resonant problems in harmonic distorted networks,

  18. An AC-AC inverter with build-in power factor correction soft-switching and a unified controller

    Microsoft Academic Search

    Wennan Guo; Praveen K. Jain

    2001-01-01

    This paper presents a full bridge AC-AC inverter for high frequency power distribution system with power factor correction stage controlled by a unified controller. The proposed inverter has the following features: (1) load independent output voltage with constant frequency and very low total harmonic distortion; (2) soft switching of the full bridge switches for a wide range of input voltage

  19. Investigation of correction factors for non-reference conditions in ion chamber photon dosimetry with Monte-Carlo simulations.

    PubMed

    Wulff, Jörg; Heverhagen, Johannes T; Karle, Heiko; Zink, Klemens

    2010-01-01

    Current dosimetry protocols require geometrical reference conditions for the determination of absorbed dose in external radiotherapy. Whenever these geometrical conditions cannot be maintained the application of additional corrections becomes necessary, in principle. The current DIN6800-2 protocol includes a corresponding factor k(NR), but numerical values are lacking and no definite information about the magnitude of this correction is available yet. This study presents Monte-Carlo based calculations within the 6 MV-X photon field of a linear accelerator for a common used ion chamber (PTW31010) employing the EGSnrc code system. The linear accelerator model was matched to measurements, showing good agreement and is used as a realistic source. The individual perturbation correction factors as well as the resulting correction factor k(NR) were calculated as a function of depth for three field sizes, as a function of central axis distance for the largest field and within the build-up region. The behaviour of the ion chamber was further investigated for an idealized hypothetical field boundary. Within the field of the linear accelerator where charged particle equilibrium is achieved the factor k(NR) was generally below approximately 0.5%. In the build-up region a depth dependent correction of up to 2% was calculated when positioning the chamber according to DIN6800-2. Minimizing the depth dependence of the corrections in the build-up region lead to a slightly different positioning of the ion chamber as currently recommended. In regions of the hypothetical field boundary with missing charged particle equilibrium and high dose gradients, the ion chamber response changed by up to approximately 40%, caused by the comparatively large volume (0.125 cm(3)) of the investigated chamber. PMID:20211423

  20. Systematic uncertainties in the Monte Carlo calculation of ion chamber replacement correction factors

    SciTech Connect

    Wang, L. L. W.; La Russa, D. J.; Rogers, D. W. O. [Ottawa Carleton Institute of Physics, Carleton University, Campus Ottawa, Ottawa, Ontario KIS 5B6 (Canada)

    2009-05-15

    In a previous study [Med. Phys. 35, 1747-1755 (2008)], the authors proposed two direct methods of calculating the replacement correction factors (P{sub repl} or p{sub cav}p{sub dis}) for ion chambers by Monte Carlo calculation. By ''direct'' we meant the stopping-power ratio evaluation is not necessary. The two methods were named as the high-density air (HDA) and low-density water (LDW) methods. Although the accuracy of these methods was briefly discussed, it turns out that the assumption made regarding the dose in an HDA slab as a function of slab thickness is not correct. This issue is reinvestigated in the current study, and the accuracy of the LDW method applied to ion chambers in a {sup 60}Co photon beam is also studied. It is found that the two direct methods are in fact not completely independent of the stopping-power ratio of the two materials involved. There is an implicit dependence of the calculated P{sub repl} values upon the stopping-power ratio evaluation through the choice of an appropriate energy cutoff {Delta}, which characterizes a cavity size in the Spencer-Attix cavity theory. Since the {Delta} value is not accurately defined in the theory, this dependence on the stopping-power ratio results in a systematic uncertainty on the calculated P{sub repl} values. For phantom materials of similar effective atomic number to air, such as water and graphite, this systematic uncertainty is at most 0.2% for most commonly used chambers for either electron or photon beams. This uncertainty level is good enough for current ion chamber dosimetry, and the merits of the two direct methods of calculating P{sub repl} values are maintained, i.e., there is no need to do a separate stopping-power ratio calculation. For high-Z materials, the inherent uncertainty would make it practically impossible to calculate reliable P{sub repl} values using the two direct methods.

  1. Correction factors for ionization chamber dosimetry in CyberKnife: Machine-specific, plan-class, and clinical fields

    SciTech Connect

    Gago-Arias, Araceli; Antolin, Elena; Fayos-Ferrer, Francisco; Simon, Rocio; Gonzalez-Castano, Diego M.; Palmans, Hugo; Sharpe, Peter; Gomez, Faustino; Pardo-Montero, Juan [Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain); Servicio de Fisica Medica, Hospital Ruber Internacional, Madrid 28034 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); National Physical Laboratory, Teddington, Middx TW11 OLW (United Kingdom); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain)

    2013-01-15

    Purpose: The aim of this work is the application of the formalism for ionization chamber reference dosimetry of small and nonstandard fields [R. Alfonso, P. Andreo, R. Capote, M. S. Huq, W. Kilby, P. Kjaell, T. R. Mackie, H. Palmans, K. Rosser, J. Seuntjens, W. Ullrich, and S. Vatnitsky, 'A new formalism for reference dosimetry of small and nonstandard fields,' Med. Phys. 35, 5179-5186 (2008)] to the CyberKnife robotic radiosurgery system. Correction factors for intermediate calibration fields, a machine-specific reference field (msr) and two plan-class specific reference fields (pcsr), have been studied. Furthermore, the applicability of the new formalism to clinical dosimetry has been analyzed through the investigation of two clinical treatments. Methods: PTW31014 and Scanditronix-Wellhofer CC13 ionization chamber measurements were performed for the fields under investigation. Absorbed dose to water was determined using alanine reference dosimetry, and experimental correction factors were calculated from alanine to ionization chamber readings ratios. In addition, correction factors were calculated for the intermediate calibration fields and one of the clinical treatment fields using the Monte Carlo method and these were compared with the experimental values. Results: Overall correction factors deviating from unity by approximately 2% were obtained from both measurements and simulations, with values below and above unity for the studied intermediate calibration fields and clinical fields for the ionization chambers under consideration. Monte Carlo simulations yielded correction factors comparable with those obtained from measurements for the machine-specific reference field, although differences from 1% to 3.3% were observed between measured and calculated correction factors for the composite intermediate calibration fields. Dose distribution inhomogeneities are thought to be responsible for such discrepancies. Conclusions: The differences found between overall correction factors associated with the proposed intermediate calibration fields and the clinical fields under investigation show that depending on the clinical field and the detector used, either a machine-specific reference field or a plan-class specific reference field is more representative for the clinical field. Given the experimental and numerical uncertainties and the small number of clinical fields considered in this study the significance of these observations is limited and it remains unclear for the CyberKnife if there would be a significant gain in using a pcsr field rather than a msr field as reference field for relative dosimetry.

  2. Correction analysis for a supersonic water cooled total temperature probe tested to 1370 K

    NASA Technical Reports Server (NTRS)

    Lagen, Nicholas T.; Seiner, John M.

    1991-01-01

    The authors address the thermal analysis of a water cooled supersonic total temperature probe tested in a Mach 2 flow, up to 1366 K total temperature. The goal of this experiment was the determination of high-temperature supersonic jet mean flow temperatures. An 8.99 cm exit diameter water cooled nozzle was used in the tests. It was designed for exit Mach 2 at 1366 K exit total temperature. Data along the jet centerline were obtained for total temperatures of 755 K, 1089 K, and 1366 K. The data from the total temperature probe were affected by the water coolant. The probe was tested through a range of temperatures between 755 K and 1366 K with and without the cooling system turned on. The results were used to develop a relationship between the indicated thermocouple bead temperature and the freestream total temperature. The analysis and calculated temperatures are presented.

  3. A two-thermocouples probe for radiation corrections of measured temperatures in compartment fires

    Microsoft Academic Search

    S Brohez; C Delvosalle; G Marlair

    2004-01-01

    Bare-bead thermocouples are widely used for measuring temperature fields in compartment fires. It is well-known that temperature readings using such a device can be significantly affected by radiation errors, the apparent thermocouple junction temperature being thus different from the true gas temperature. However, a probe consisting of two thermocouples of unequal diameters, but made of the same material can be

  4. Zero-temperature equation of state of metals in the statistical model with density gradient correction

    Microsoft Academic Search

    F. Perrot

    1979-01-01

    The density gradient correction to kinetic energy (nine times smaller than the original von Weizsäcker correction) has been used within local density formalism to calculate the cold compression curve of metals. Numerical results are reported for Li, Be, Al and Cu. The modifications to the Thomas-Fermi-Dirac (TFD) results strongly depend, in the low compression range (varrho\\/varrho0 <= 5), on the

  5. Size-dependent correction factors for absorption measurements using filter-based photometers: PSAP and COSMOS

    Microsoft Academic Search

    T. Nakayama; Y. Kondo; N. Moteki; L. K. Sahu; T. Kinase; K. Kita; Y. Matsumi

    2010-01-01

    Filter-based absorption photometers have been widely used to measure mass concentrations of black carbon (BC) by measurement of the absorption coefficient of BC. In these techniques, correction for the effect of multiple scattering by the filter medium is necessary, even if only BC particles are extracted by evaporating co-existing volatile compounds using a heated inlet. The correction depends on particle

  6. Burnout, Job Stress and Job Satisfaction Among Southern Correctional Officers: Perceptions and Causal Factors.

    ERIC Educational Resources Information Center

    Lindquist, Charles A.; Whitehead, John T.

    1986-01-01

    Surveyed perceptions of burnout, job stress, and job satisfaction among a representative sample (N=241) of Alabama correctional officers. Examination of predictor variables revealed that social support; marital status; role conflict; age; correctional seniority; and extrinsic, organizational, and overload stressors significantly influenced…

  7. Monte-Carlo-based perturbation and beam quality correction factors for thimble ionization chambers in high-energy photon beams.

    PubMed

    Wulff, J; Heverhagen, J T; Zink, K

    2008-06-01

    This paper presents a detailed investigation into the calculation of perturbation and beam quality correction factors for ionization chambers in high-energy photon beams with the use of Monte Carlo simulations. For a model of the NE2571 Farmer-type chamber, all separate perturbation factors as found in the current dosimetry protocols were calculated in a fixed order and compared to the currently available data. Furthermore, the NE2571 Farmer-type and a model of the PTW31010 thimble chamber were used to calculate the beam quality correction factor kQ. The calculations of kQ showed good agreement with the published values in the current dosimetry protocols AAPM TG-51 and IAEA TRS-398 and a large set of published measurements. Still, some of the single calculated perturbation factors deviate from the commonly used ones; especially prepl deviates more than 0.5%. The influence of various sources of uncertainties in the simulations is investigated for the NE2571 model. The influence of constructive details of the chamber stem shows a negligible dependence on calculated values. A comparison between a full linear accelerator source and a simple collimated point source with linear accelerator photon spectra yields comparable results. As expected, the calculation of the overall beam quality correction factor is sensitive to the mean ionization energy of graphite used. The measurement setup (source-surface distance versus source-axis distance) had no influence on the calculated values. PMID:18460747

  8. Fatigue Crack Growth Rate and Stress-Intensity Factor Corrections for Out-of-Plane Crack Growth

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Herman, Dave J.; James, Mark A.

    2003-01-01

    Fatigue crack growth rate testing is performed by automated data collection systems that assume straight crack growth in the plane of symmetry and use standard polynomial solutions to compute crack length and stress-intensity factors from compliance or potential drop measurements. Visual measurements used to correct the collected data typically include only the horizontal crack length, which for cracks that propagate out-of-plane, under-estimates the crack growth rates and over-estimates the stress-intensity factors. The authors have devised an approach for correcting both the crack growth rates and stress-intensity factors based on two-dimensional mixed mode-I/II finite element analysis (FEA). The approach is used to correct out-of-plane data for 7050-T7451 and 2025-T6 aluminum alloys. Results indicate the correction process works well for high DeltaK levels but fails to capture the mixed-mode effects at DeltaK levels approaching threshold (da/dN approximately 10(exp -10) meter/cycle).

  9. A Physically Based Algorithm for Non-Blackbody Correction of Cloud-Top Temperature and Application to Convection Study

    NASA Technical Reports Server (NTRS)

    Wang, Chunpeng; Lou, Zhengzhao Johnny; Chen, Xiuhong; Zeng, Xiping; Tao, Wei-Kuo; Huang, Xianglei

    2014-01-01

    Cloud-top temperature (CTT) is an important parameter for convective clouds and is usually different from the 11-micrometers brightness temperature due to non-blackbody effects. This paper presents an algorithm for estimating convective CTT by using simultaneous passive [Moderate Resolution Imaging Spectroradiometer (MODIS)] and active [CloudSat 1 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] measurements of clouds to correct for the non-blackbody effect. To do this, a weighting function of the MODIS 11-micrometers band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat and CALIPSO retrievals and temperature and humidity profiles based on ECMWF analyses into a radiation transfer model.Among 16 837 tropical deep convective clouds observed by CloudSat in 2008, the averaged effective emission level (EEL) of the 11-mm channel is located at optical depth; approximately 0.72, with a standard deviation of 0.3. The distance between the EEL and cloud-top height determined by CloudSat is shown to be related to a parameter called cloud-top fuzziness (CTF), defined as the vertical separation between 230 and 10 dBZ of CloudSat radar reflectivity. On the basis of these findings a relationship is then developed between the CTF and the difference between MODIS 11-micrometers brightness temperature and physical CTT, the latter being the non-blackbody correction of CTT. Correction of the non-blackbody effect of CTT is applied to analyze convective cloud-top buoyancy. With this correction, about 70% of the convective cores observed by CloudSat in the height range of 6-10 km have positive buoyancy near cloud top, meaning clouds are still growing vertically, although their final fate cannot be determined by snapshot observations.

  10. Shutterless solution for simultaneous focal plane array temperature estimation and nonuniformity correction in uncooled long-wave infrared camera.

    PubMed

    Cao, Yanpeng; Tisse, Christel-Loic

    2013-09-01

    In uncooled long-wave infrared (LWIR) microbolometer imaging systems, temperature fluctuations of the focal plane array (FPA) result in thermal drift and spatial nonuniformity. In this paper, we present a novel approach based on single-image processing to simultaneously estimate temperature variances of FPAs and compensate the resulting temperature-dependent nonuniformity. Through well-controlled thermal calibrations, empirical behavioral models are derived to characterize the relationship between the responses of microbolometer and FPA temperature variations. Then, under the assumption that strong dependency exists between spatially adjacent pixels, we estimate the optimal FPA temperature so as to minimize the global intensity variance across the entire thermal infrared image. We make use of the estimated FPA temperature to infer an appropriate nonuniformity correction (NUC) profile. The performance and robustness of the proposed temperature-adaptive NUC method are evaluated on realistic IR images obtained by a 640 × 512 pixels uncooled LWIR microbolometer imaging system operating in a significantly changed temperature environment. PMID:24085086

  11. Temperature effects and corrections in volume measurements based on liquid-level detection

    Microsoft Academic Search

    S. Suda; B. Keisch

    1993-01-01

    Temperature changes affect volume measurements in several ways. The dimensions of the tank, and the density and level of the liquid it contains vary with temperature. In addition, the response signal of the sensor and hence the response of the liquid-level detection device may change with temperature. Level measurement devices can be grouped according to four measurement points of reference:

  12. Physical parameters and correction factors for ionization chambers for absolute measurement of air kerma in �³-ray fields

    NASA Astrophysics Data System (ADS)

    Takata, N.; Kurosawa, T.; Begum, A.; Sugita, T.

    2007-09-01

    Values of physical parameters and correction factors essential for the absolute measurement of air kerma in 137Cs and 60Co ?-ray fields were obtained using an EGS5 program for spherical, cylindrical and pancake ionization chambers. The mean mass collision stopping power ratio for graphite and air, was found to vary depending on the cutoff energy of electrons employed in calculation. The ratio between the energies deposited in cavity air due to Compton electrons emitted from the air and those from the graphite wall increases as the chamber size is increased. It also increases as the ?-ray energy is reduced and is equal to 0.09 for 137Cs ?-rays in a spherical ionization chamber of cavity diameter 12 cm. Correction factors for ?-ray attenuation in chamber walls and those for the contribution of scattered ?-rays to chamber responses were obtained separately. The wall correction factor, which is equal to the product of these two factors, is close to unity for pancake chambers.

  13. Voluntary STD testing and treatment program at a metropolitan correctional facility: evaluation of test acceptability and associated risk factors.

    PubMed

    Brown, Christopher K; Earley, Mary; Shaikh, Raees; Fickenscher, Jillian; Ott, Jessica; Person, Austin; Islam, K M Monirul; Simonsen, Kari; Sandkovsky, Uriel; Kaiser, Katherine Laux; Foxall, Mark; Margalit, Ruth

    2014-01-01

    Few studies have addressed challenges of diagnosis and treatment of sexually transmitted diseases (STDs) within correctional facilities. Initiatives that screen all inmates can be cost-prohibitive, while symptom-based screening undoubtedly fails to recognize significant numbers of asymptomatically infected persons. This study discusses a voluntary STD screening and treatment program developed at the Douglas County (Nebraska) Department of Corrections where student volunteers interviewed, screened, and educated 456 inmates. Inmate urine samples and interview responses about risk behaviors and motivators for participation in the screening program were analyzed. The results support the ongoing project method to screen and treat inmates in the community correctional facility. Risk factor analysis suggests that targeted testing and treatment efforts may have a role in providing cost-effective care for STD among the incarcerated population. PMID:24352406

  14. The NLO contributions to the scalar pion form factors and the O (?s2) annihilation corrections to the B ? ?? decays

    NASA Astrophysics Data System (ADS)

    Cheng, Shan; Zhang, Ya-Lan; Xiao, Zhen-Jun

    2015-07-01

    In this paper, by employing the kT factorization theorem, we made the first calculation for the space-like scalar pion form factor Q2 F (Q2) at the leading order (LO) and the next-to-leading order (NLO) level, and then found the time-like scalar pion form factor Fa,I? (1) by analytic continuation from the space-like one. From the analytical evaluations and the numerical results, we found the following points: (a) the NLO correction to the space-like scalar pion form factor has an opposite sign with the LO one but is very small in magnitude, can produce at most 10% decrease to the LO result in the considered Q2 region; (b) the NLO time-like scalar pion form factor Fa,I? (1) describes the O (?s2) contribution to the factorizable annihilation diagrams of the considered B ? ?? decays, i.e. the NLO annihilation correction; (c) the NLO part of the form factor Fa,I? (1) is very small in size, and is almost independent of the variation of cutoff scale ?0, but this form factor has a large strong phase around - 55 ° and may play an important role in producing large CP violation for B ? ?? decays; and (d) for B0 ??+?- and ?0?0 decays, the newly known NLO annihilation correction can produce only a very small enhancement to their branching ratios, less than 3% in magnitude, and therefore we could not interpret the well-known ??-puzzle by the inclusion of this NLO correction to the factorizable annihilation diagrams. The pion form factors in ??? ? ? transition were calculated in Ref. [22]. The authors found that the NLO correction is only ?5% of the leading order (LO) one when the factorization scale is set to be equal to the momentum transfer. The pion electromagnetic form factors in ??? ? ? transition were calculated in Refs. [23,25]. The total NLO contribution can provide a roughly ?20% enhancement to the LO contribution in the considered ranges of the momentum transfer Q2; The B ? ? transition form factors involved in the semi-leptonic decay B ? ?l?bar were calculated in Refs. [24,26]. The NLO contribution from twist-2 part of the wave function can provide ?30% correction to the LO order one [24], but it is largely canceled by the NLO twist-3 contribution [26], and finally result in a net ?8% enhancement to the LO result. In Ref. [27], the combined analysis of the space-like and time-like electromagnetic pion form factors has been done in the light-cone pQCD, with the inclusion of the non-perturbative "soft" QCD and the twist-3 corrections. The NLO corrections to the time-like pion transition form factor and the electromagnetic pion form factors have been calculated in Ref. [28], where the NLO twist-2 correction to the magnitude (phase) is found to be smaller than 30% (30°) for the time-like pion transition form factors, and lower than 25% (10°) for the time-like electromagnetic form factors at the large invariant mass squared Q2 > 30 GeV2. One should note that the vertices for all above mentioned transitions and decay processes involve the vector currents only. The NLO corrections to the form factors with a scalar vertex, however, have not been evaluated up to now.As is well known, the B meson physics is an wonderful place to test the standard model (SM) and to search for the signal of the new physics (NP) beyond the SM. For the two body charmless hadronic B /Bs ?h1h2 decays (here hi refers to the light pseudo-scalar or vector mesons), such as B± ??±?0 and B0 ??+?- decays, the major contribution come from the factorizable emission diagrams, in which the space-like form factors with the vector current are involved. But for the color-suppressed B0 ??0?0 decay, along with a large cancellation between the emission diagrams, the contribution from the annihilation diagrams play an important role: the corresponding amplitude is proportional to the complex time-like scalar pion form factor.In the framework of the pQCD factorization approach, the calculations for the main part of the NLO contributions from various sources have been done during the past d

  15. Temperature Variations and Habitability: Activity B Relating Factors that Influence Planetary Temperature and Habitability

    NSDL National Science Digital Library

    In this activity, student teams create a knowledge map of the essential characteristics or factors of a planet with a habitable climate, identifying range of inputs, outputs and variables of a planetary environmental system. Identified characteristics are compared to extreme environments on Earth, such as the Antarctic or the Sahara desert, and are used to consider the real life challenge of searching for life in extreme environments. The resource includes a student data sheet, questions, teacher's guide and scoring rubric. This is Activity B of two activities in the first module, titled "Temperature variations and habitability," of the resource, Earth Climate Course: What Determines a Planet's Climate? The course aims to help students to develop an understanding of our environment as a system of human and natural processes that result in changes that occur over various space and time scales.

  16. Small field diode correction factors derived using an air core fibre optic scintillation dosimeter and EBT2 film

    NASA Astrophysics Data System (ADS)

    Ralston, Anna; Liu, Paul; Warrener, Kirbie; McKenzie, David; Suchowerska, Natalka

    2012-05-01

    There is no commercially available real-time dosimeter that can accurately measure output factors for field sizes down to 4 mm without the use of correction factors. Silicon diode detectors are commonly used but are not dosimetrically water equivalent, resulting in energy dependence and fluence perturbation. In contrast, plastic scintillators are nearly dosimetrically water equivalent. A fibre optic dosimeter (FOD) with a 0.8 mm3 plastic scintillator coupled to an air core light guide was used to measure the output factors for Novalis/BrainLab stereotactic cones of diameter 4-30 mm and Novalis MLC fields of width 5-100 mm. The FOD data matched the output factors measured by a 0.125 cm3 Semiflex ion chamber for the MLC fields above 30 mm and those measured with the EBT2 radiochromic film for the cones and MLC fields below 30 mm. Relative detector readings were obtained with four diode types (IBA SFD, EFD, PFD, PTW 60012) for the same fields. Empirical diode correction factors were determined by taking the ratio of FOD output factors to diode relative detector readings. The diodes were found to over-respond by 3%-16% for the smallest field. There was good agreement between different diodes of the same model number.

  17. Light and Temperature: Key Factors Affecting Walleye Abundance and Production

    Microsoft Academic Search

    Nigel P. Lester; Alan J. Dextrase; Robert S. Kushneriuk; Michael R. Rawson; Phil A. Ryan

    2004-01-01

    We used published information to determine optimum light and temperature conditions for walleye Sander vitreus (formerly Stizostedion vitreum) and then applied this simple niche definition to predict how water clarity, temperature, and bathymetry affect walleye habitat availability. Our model calculated thermal–optical habitat area (TOHA), the benthic area of a lake that supplies optimum light, and temperature conditions for walleye during

  18. Implicit temperature-correction-based immersed-boundary thermal lattice Boltzmann method for the simulation of natural convection.

    PubMed

    Seta, Takeshi

    2013-06-01

    In the present paper, we apply the implicit-correction method to the immersed-boundary thermal lattice Boltzmann method (IB-TLBM) for the natural convection between two concentric horizontal cylinders and in a square enclosure containing a circular cylinder. The Chapman-Enskog multiscale expansion proves the existence of an extra term in the temperature equation from the source term of the kinetic equation. In order to eliminate the extra term, we redefine the temperature and the source term in the lattice Boltzmann equation. When the relaxation time is less than unity, the new definition of the temperature and source term enhances the accuracy of the thermal lattice Boltzmann method. The implicit-correction method is required in order to calculate the thermal interaction between a fluid and a rigid solid using the redefined temperature. Simulation of the heat conduction between two concentric cylinders indicates that the error at each boundary point of the proposed IB-TLBM is reduced by the increment of the number of Lagrangian points constituting the boundaries. We derive the theoretical relation between a temperature slip at the boundary and the relaxation time and demonstrate that the IB-TLBM requires a small relaxation time in order to avoid temperature distortion around the immersed boundary. The streamline, isotherms, and average Nusselt number calculated by the proposed method agree well with those of previous numerical studies involving natural convection. The proposed IB-TLBM improves the accuracy of the boundary conditions for the temperature and velocity using an adequate discrete area for each of the Lagrangian nodes and reduces the penetration of the streamline on the surface of the body. PMID:23848803

  19. An Improvement on Horn's Parallel Analysis Methodology for Selecting the Correct Number of Factors to Retain

    Microsoft Academic Search

    Louis W. Glorfeld

    1995-01-01

    One of the most important decisions that can be made in the use of factor analysis is the number of factors to retain. Numerous studies have consistently shown that Horn's parallel analysis is the most nearly accurate methodology for determining the number of factors to retain in an exploratory factor analysis. Although Horn's procedure is relatively accurate, it still tends

  20. A Fully Digital Controlled 3KW, Single-Stage Power Factor Correction Converter Based on Full-Bridge Topology

    Microsoft Academic Search

    Hang Li-jun; Yang Yue-feng; Su Bin; Lu Zheng-yu; Qian Zhao-ming

    2006-01-01

    This paper deals with a 3 KW power factor correction (PFC) circuit based on the isolated full-bridge (FB) converter. The operation principle of the very converter is simply analyzed. Digital design consideration based on the small-signal dynamic modeling of the isolated PFC converter is specified in this paper. Implementation strategy and cost effectiveness of digital control for the single-stage PFC

  1. Calculable Corrections to Brane Black Hole Decay II:Greybody Factors for Spin 1\\\\\\/2 and 1

    Microsoft Academic Search

    Panagiota Kanti; John David March-Russell

    2002-01-01

    The production of black holes in extra-dimensional brane-world theories can lead to detectable signals via the Hawking evaporation of the black hole to brane-localized Standard Model modes. We calculate, as a function of partial wave number and number of toroidally compactified extra dimensions, the leading correction to the energy spectrum of such Hawking radiation (the greybody factors) for decay into

  2. Calculable corrections to brane black hole decay. II. Greybody factors for spin 1\\/2 and 1

    Microsoft Academic Search

    Panagiota Kanti; John March-Russell

    2003-01-01

    The production of black holes in extra-dimensional brane-world theories can lead to detectable signals via the Hawking evaporation of the black hole to brane-localized standard model modes. We calculate, as a function of partial wave number and number of toroidally compactified extra dimensions, the leading correction to the energy spectrum of such Hawking radiation (the greybody factors) for decay into

  3. Conversion and correction factors for historical measurements of Iodine-131 in Hanford-area vegetation, 1945--1947: Draft

    SciTech Connect

    Mart, E.I.; Denham, D.H.; Thiede, M.E.

    1993-05-01

    This report is a result of the Hanford Environmental Dose Reconstruction (HEDR) Project whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the US Department of Energy's (DOE) Hanford Site near Richland, Washington. The report describes in detail the reconstructed conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation which was collected from the beginning of October 1945 through the end of December 1947.

  4. Sustained phenotypic correction of hemophilia B dogs with a factor IX null mutation by liver-directed gene therapy

    Microsoft Academic Search

    Jane D. Mount; Roland W. Herzog; D. Michael Tillson; Susan A. Goodman; Nancy Robinson; Mark L. McCleland; Dwight Bellinger; Timothy C. Nichols; Valder R. Arruda; Clinton D. Lothrop Jr; Katherine A. High

    2002-01-01

    Hemophilia B is an X-linked coagulopathy caused by absence of functional coagula- tion factor IX (FIX). Using adeno-associ- ated virus (AAV)-mediated, liver-directed gene therapy, we achieved long-term (> 17 months) substantial correction of canine hemophilia B in 3 of 4 animals, including 2 dogs with an FIX null mutation. This was accomplished with a comparatively low dose of 1 3

  5. Relative Response to Low-Energy Photons and Determination of Instrument Correction Factors for Portable Radiation Instrumentation 

    E-print Network

    Wagoner, David Andrew

    2011-10-21

    RELATIVE RESPONSE TO LOW-ENERGY PHOTONS AND DETERMINATION OF INSTRUMENT CORRECTION FACTORS FOR PORTABLE RADIATION INSTRUMENTATION A Thesis by DAVID ANDREW WAGONER Submitted to the Office of Graduate Studies of Texas A&M... RADIATION INSTRUMENTATION A Thesis by DAVID ANDREW WAGONER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Co-Chairs of Committee...

  6. Adding active clamping and soft switching to boost-flyback single-stage isolated power-factor-corrected power supplies

    Microsoft Academic Search

    Yim-Shu Lee; Bo-Tao Lin

    1997-01-01

    Single-stage isolated power-factor-corrected power supplies (SSIPP) have the attractive features of fast regulation and a single control loop. However, SSIPP circuits also have higher voltage stress and heavier loss (when compared with a normal DC-DC power converter), which severely limit their practical applications. In this paper, the authors propose to add active clamping to SSIPP to recycle the energy trapped

  7. Space vector modulated three-phase to three-phase matrix converter with input power factor correction

    Microsoft Academic Search

    L. Huber; D. Borojevic

    1995-01-01

    Analysis, design, and implementation of the space vector modulated three-phase to three-phase matrix converter with input power factor correction are presented. The majority of published research results on the matrix converter control are given an overview, and the one which employs simultaneous output-voltage and input-current space vector modulation, is systematically reviewed. The modulation algorithm is theoretically derived from the desired

  8. Factors influencing softening temperature and hot-strength of geopolymers

    Microsoft Academic Search

    Zhu Pan; Jay G. Sanjayan

    This paper presents the effects of cation type, silicate concentration, compositions of low-calcium fly ash and test load on softening temperature and hot-strength (loaded while at high temperature) of fly ash-based geopolymers. It was found that softening temperature (Ts) of sodium (Na) based-geopolymer remained the same (610°C±20°C) regardless of the silicate concentration, fly ash composition, and test load. However, when

  9. Single-image-based solution for optics temperature-dependent nonuniformity correction in an uncooled long-wave infrared camera.

    PubMed

    Cao, Yanpeng; Tisse, Christel-Loic

    2014-02-01

    In this Letter, we propose an efficient and accurate solution to remove temperature-dependent nonuniformity effects introduced by the imaging optics. This single-image-based approach computes optics-related fixed pattern noise (FPN) by fitting the derivatives of correction model to the gradient components, locally computed on an infrared image. A modified bilateral filtering algorithm is applied to local pixel output variations, so that the refined gradients are most likely caused by the nonuniformity associated with optics. The estimated bias field is subtracted from the raw infrared imagery to compensate the intensity variations caused by optics. The proposed method is fundamentally different from the existing nonuniformity correction (NUC) techniques developed for focal plane arrays (FPAs) and provides an essential image processing functionality to achieve completely shutterless NUC for uncooled long-wave infrared (LWIR) imaging systems. PMID:24487887

  10. Absolute spectrophotometry of galactic Wolf-Rayet stars - Effective temperatures and bolometric corrections

    Microsoft Academic Search

    Jong Ok Woo

    1988-01-01

    The recent data of absolute measurements of flux emitted in the visible continua of some galactic Wolf-Rayet stars are presented. Correction of interstellar reddening is made in detail, prior to the determinations of color excesses, E(B-V). The dereddened fluxes combined with IUE and ANS ultraviolet measurements are then compared to those of LTE plane-parallel model atmospheres of Kurucz (1979) and

  11. Correction Factors Applied to Finger Dosimetry: A Theoretical Assessment of Appropriate Values for Use in Handling Radiopharmaceuticals

    SciTech Connect

    Sherbini, Sami [NRC; Ilas, Dan [ORNL; Eckerman, Keith F [ORNL; DeCicco, Joseph [NRC

    2011-01-01

    United States Nuclear Regulatory Commission (USNRC) regulations limit the dose to the skin to 500 mSv per year. This is also the dose limit recommended by the International Commission on Radiological Protection (ICRP). The operational quantity recommended by ICRP for quantifying dose to the skin is the personal dose equivalent, Hp(0.07) and is identical to NRC s shallow dose equivalent, Hs, also measured at a skin depth of 7 mg cm 2. However, whereas ICRP recommends averaging the dose to the skin over an area of 1 cm2 regardless of the size of the exposed area of skin, USNRC requires the shallow dose equivalent to be averaged over 10 cm2. To monitor dose to the skin of the hands of workers handling radioactive materials and particularly in radiopharmaceutical manufacturing facilities, which is the focus of this work, workers are frequently required to wear finger ring dosimeters. The dosimeters monitor the dose at the location of the sensitive element, but this is not the dose required to show compliance (i.e., the dose averaged over the highest exposed contiguous 10 cm2 of skin). Therefore, it may be necessary to apply a correction factor that enables estimation of the required skin dose from the dosimeter reading. This work explored the effects of finger ring placement and of the geometry of the radioactive materials being handled by the worker on the relationship between the dosimeter reading and the desired average dose. A mathematical model of the hand was developed for this purpose that is capable of positioning the fingers in any desired grasping configuration, thereby realistically modeling manipulation of any object. The model was then used with the radiation transport code MCNP to calculate the dose distribution on the skin of the hand when handling a variety of radioactive vials and syringes, as well as the dose to the dosimeter element. Correction factors were calculated using the results of these calculations and examined for any patterns that may be useful in establishing an appropriate correction factor for this type of work. It was determined that a correction factor of one applied to the dosimeter reading, with the dosimeter placed at the base of the middle finger, provides an adequate estimate of the required average dose during a monitoring period for most commonly encountered geometries. Different correction factors may be required for exceptional or unusual source geometries and must be considered on a case-by-case basis.

  12. Tackling Fluctuation Corrections in the Bec/bcs Crossover at Nonzero Temperatures

    NASA Astrophysics Data System (ADS)

    Tempere, J.; Klimin, S. N.; Devreese, J. T.

    2008-11-01

    The investigation of superfluid atomic Fermi gases in the regime of strong interactions is conveniently investigated with the path-integral method at temperature zero, or at the critical temperature where the gap vanishes, by taking particle-pair or hole-pair fluctuations into account. Here, we also take the particle-hole excitations into account, which is important to investigate intermediate temperatures. The additional terms in the fluctuation propagator are identified, and a contour integral representation is used to calculate the contribution of these terms to the free energy and to the density of noncondensed fermions.

  13. Early Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction factors

    E-print Network

    Royer, Dana

    isotopic offsets appear to have changed through the Cenozoic, either (1) as a result of evolutionaryEarly Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information

  14. [Measurement of peak correction factor of Farmer chamber for calibration of flattening filter free (FFF) clinical photon beams].

    PubMed

    Kontra, Gábor; Major, Tibor; Polgár, Csaba

    2015-06-01

    Farmer-type ionization chambers are considered the most reliable detectors and for this reason they are most frequently used for the calibration of photon beams of medical linear accelerators. Flattening filter free (FFF) photon beams of linear accelerators have recently started to be used in radiotherapy. The dose profile of FFF beams is peaked in the center of the field and the dose distribution will be inhomogeneous along the axis of the 2.3 cm long measuring volume of the Farmer chamber. The peaked radiation field will result in volume averaging effects in the large Farmer chamber, therefore this chamber will underestimate the true central axis dose. Our objective was to determine the value of the peak correction factor (Kp) of Farmer-type chamber with measurements to avoid the underestimation of the central axis dose during the calibration of FFF radiation fields. Measurements were made with 6 MV and 10 MV flattened (6X and 10X) and FFF beams (6XFFF and 10XFFF) of a Varian TrueBeam medical linear accelerator in a solid water phantom at 10 cm depth. The source surface distance (SSD) was 100 cm, the field size was 10×10 cm and the dose rate was always 400 MU/min during the measurements. We delivered 100 MU in each measurement and the absorbed dose to water was calculated according to the IAEA TRS-398 dosimetry protocol. The measured signals of the ionization chambers were always corrected for the ion recombination loss. The ion recombination correction factors (Kr) were determined with the two-voltage method separately for the used ion chambers and for flattened and unflattened beams. First, we measured the dose to water with PTW TM30012 Farmer chamber in 6XFFF and 6X beams, then calculated the ratio of doses of 6XFFF and 6X beams (R6,Farmer). Immediately after this we repeated the above measurements with PTW TM31010 Semiflex chamber and determined the ratio of doses of 6XFFF and 6X beams again (R6,Semiflex). The length of the sensitive volume of the Semiflex chamber is only 6.5 mm. According to our dose profile measurements the peak correction factor of this chamber equals to unity for both photon energies. As a consequence R6,Semiflex is larger than R6,Farmer and Kp6XFFF = R6,Semiflex / R6,Farmer, where Kp6XFFF is the peak correction factor of the Farmer chamber in 6XFFF beam. The advantage of this method is that we have to calculate ratio of doses, so it is not necessary to know the calibration factors of the chambers. Repeating the above measurements with 10X and 10XFFF beams we determined the peak correction factor of Farmer chamber for 10XFFF beam, too (Kp10XFFF). According to our measurements Kp6XFFF = 1.0025 and Kp10XFFF = 1.009. The bigger peak correction factor for 10XFFF beam is in accordance with the fact that the peak of dose profile is steeper for higher photon energy. The above described method for the determination of Kp can be used for other photon energies and other large volume ionization chambers. PMID:26035159

  15. Arctic Wave Glider data processing and correction Sea temperature data from two Arctic Wave Gliders (WG-1 and WG-2) have been processed and

    E-print Network

    Arctic Wave Glider data processing and correction Sea temperature data from two Arctic Wave Gliders on the Wave Gliders were batch calibrated at the time of manufacture. To achieve credible accuracy we compared

  16. Low-Temperature Thermoelectric Power Factor Enhancement by Controlling

    E-print Network

    significantly. The improvement could be large (up to 450% for GaAs) especially at low temperatures when nanoparticles inside semiconductor host materials to improve their thermoelec- tric properties2,3 either

  17. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    PubMed

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibi?, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. PMID:25266988

  18. A feedforward compensation design in critical conduction mode boost power factor correction for low-power low totalharmonic distortion

    NASA Astrophysics Data System (ADS)

    Yani, Li; Yintang, Yang; Zhangming, Zhu; Wei, Qiang

    2012-03-01

    For low-power low total harmonic distortion (THD), based on the CSMC 0.5 ?m BCD process, a novel boost power factor correction (PFC) converter in critical conduction mode is discussed and analyzed. Feedforward compensation design is introduced in order to increase the PWM duty cycle and supply more conversion energy near the input voltage zero-crossing points, thus regulating the inductor current of the PFC converter and compensating the system loop gain change with ac line voltage. Both theoretical and practical results reveal that the proposed PFC converter with feedforward compensation cell has better power factor and THD performance, and is suitable for low-power low THD design applications. The experimental THD of the boost PFC converter is 4.5%, the start-up current is 54 ?A, the stable operating current is 3.85 mA, the power factor is 0.998 and the efficiency is 95.2%.

  19. Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region.

    PubMed

    Röttgers, Rüdiger; McKee, David; Utschig, Christian

    2014-10-20

    The light absorption coefficient of water is dependent on temperature and concentration of ions, i.e. the salinity in seawater. Accurate knowledge of the water absorption coefficient, a, and/or its temperature and salinity correction coefficients, ?(T) and ?(S), respectively, is essential for a wide range of optical applications. Values are available from published data only at specific narrow wavelength ranges or at single wavelengths in the visible and infrared regions. ?(T) and ?(S) were therefore spectrophotometrically measured throughout the visible, near, and short wavelength infrared spectral region (400 to ~2700 nm). Additionally, they were derived from more precise measurements with a point-source integrating-cavity absorption meter (PSICAM) for 400 to 700 nm. When combined with earlier measurements from the literature in the range of 2600 - 14000 nm (wavenumber: 3800 - 700 cm(-1)), the coefficients are provided for 400 to 14000 nm (wavenumber: 25000 to 700 cm(-1)). PMID:25401542

  20. Review of mathematics, numerical factors, and corrections for dark matter experiments based on elastic nuclear recoil

    Microsoft Academic Search

    J. D. Lewin; P. F. Smith

    1996-01-01

    We present a systematic derivation and discussion of the practical formulae needed to design and interpret direct searches for nuclear recoil events caused by hypothetical weakly interacting dark matter particles. Modifications to the differential energy spectrum arise from the Earth's motion, recoil detection efficiency, instrumental resolution and threshold, multiple target elements, spin-dependent and coherent factors, and nuclear form factor. We

  1. Nuclear-polarization correction to the bound-electron g factor in heavy hydrogenlike ions.

    PubMed

    Nefiodov, A V; Plunien, G; Soff, G

    2002-08-19

    The influence of nuclear polarization on the bound-electron g factor in heavy hydrogenlike ions is investigated. Numerical calculations are performed for the K- and L-shell electrons taking into account the dominant virtual nuclear excitations. This determines the ultimate limit for tests of QED utilizing measurements of the bound-electron g factor in highly charged ions. PMID:12190457

  2. Temperature is a dominant factor in governing the distribution patterns of ectothermic marine organisms (Fields

    E-print Network

    Stillman, Jonathon

    between adaptation temperature and enzyme thermal stability are less clear. Although the thermal stabilityTemperature is a dominant factor in governing the distribution patterns of ectothermic marine closely reflect differences in habitat temperature that result from different latitudinal and vertical

  3. Evaluation of Cold Temperatures and Density as Mortality Factors of the Eucalyptus Longhorned Borer

    E-print Network

    Hanks, Lawrence M.

    Evaluation of Cold Temperatures and Density as Mortality Factors of the Eucalyptus Longhorned Borer semipunctata F., in California is limited by winter temperature con- ditions. The cold tolerance of prepupal stages was tested by exposing infested logs to cold temperature treatments of -5, 0, +5, and + l

  4. Early Time Points Perfusion Imaging: Theoretical Analysis of Correction Factors for relative cerebral blood flow Estimation Given Local Arterial Input Function

    PubMed Central

    Kwong, Kenneth K.; Chesler, David A.

    2011-01-01

    If local arterial input function (AIF) could be identified, we present a theoretical approach to generate a correction factor based on local AIF for the estimation of relative cerebral blood flow (rCBF) under the framework of early time points perfusion imaging (ET). If C(t), the contrast agent bolus concentration signal time course, is used for rCBF estimation in ET, the correction factor for C(t) is the integral of its local AIF. The recipe to apply the correction factor is to divide C(t) by the integral of its local AIF to obtain the correct rCBF. By similar analysis, the correction factor for the maximum derivative (MD1) of C(t) is the maximum signal of AIF and the correction factor for the maximum second derivative (MD2) of C(t) is the maximum derivative of AIF. In the specific case of using normalized gamma-variate function as a model for AIF, the correction factor for C(t) (but not for MD1) at the time to reach the maximum derivative is relatively insensitive to the shape of the local AIF. PMID:21497658

  5. Partial correction of a severe molecular defect in hemophilia A, because of errors during expression of the factor VIII gene

    SciTech Connect

    Young, M.; Antonarakis, S.E. [Univ. of Geneva (Switzerland); Inaba, Hiroshi [Tokyo Medical College (Japan)] [and others

    1997-03-01

    Although the molecular defect in patients in a Japanese family with mild to moderately severe hemophilia A was a deletion of a single nucleotide T within an A{sub 8}TA{sub 2} sequence of exon 14 of the factor VIII gene, the severity of the clinical phenotype did not correspond to that expected of a frameshift mutation. A small amount of functional factor VIII protein was detected in the patient`s plasma. Analysis of DNA and RNA molecules from normal and affected individuals and in vitro transcription/translation suggested a partial correction of the molecular defect, because of the following: (i) DNA replication/RNA transcription errors resulting in restoration of the reading frame and/or (ii) {open_quotes}ribosomal frameshifting{close_quotes} resulting in the production of normal factor VIII polypeptide and, thus, in a milder than expected hemophilia A. All of these mechanisms probably were promoted by the longer run of adenines, A{sub 10} instead of A{sub 8}TA{sub 2}, after the delT. Errors in the complex steps of gene expression therefore may partially correct a severe frameshift defect and ameliorate an expected severe phenotype. 36 refs., 6 figs.

  6. PHYSICOCHEMICAL FACTORS AFFECTING TOXICITY IN FRESHWATER: HARDNESS, PH, AND TEMPERATURE

    EPA Science Inventory

    A search of the literature for effects of hardness, pH, or temperature on the toxicity of chemicals to freshwater organisms suggested that the amount of reliable and useful data is limited. uch of the disparity among results reported in the literature was caused by improperly des...

  7. Characterization of temperature correction method for kinetic methods of analysis with the extended Kalman filter

    SciTech Connect

    Corcoran, C.A.; Rutan, S.C.

    1988-11-15

    An extended Kalman filter for compensating for within-run temperature variations in kinetic methods of analysis is critically evaluated with first-order synthetic data. The kinetic data represent values ranging from 0.7 to 14 half-lives and include a random noise contribution to give approximate signal-to-noise ratios of 100, 1000, and 10,000. The theoretical and experimental performances of the method are compared by evaluating the data with three data analysis programs based on the extended Kalman filter algorithm. The effects of variations in temperature data morphologies are also considered. Criteria for selection of an appropriate data analysis method are presented, based on the results obtained in the comparative study.

  8. Linking the loading dependence of the Maxwell Stefan diffusivity of linear alkanes in zeolites with the thermodynamic correction factor

    NASA Astrophysics Data System (ADS)

    Krishna, R.; van Baten, J. M.

    2006-03-01

    Molecular dynamics simulations have been carried out to determine the Maxwell-Stefan diffusivity ? of C1-C4 linear alkanes for a range of molecular loadings, q, in AFI, MOR, MTW, and MFI zeolites. Configurational-Bias Monte Carlo simulations were used to determine the thermodynamic correction factor, ? ? ? ln f/? ln q. For diffusion in the large 1D pores of AFI, ? is proportional to 1/ ?. In other zeolite topologies with smaller pore sizes, though such a direct proportionality is not observed, the ?-q dependence appears to be closely linked to the 1/ ?- q characteristics, especially when the latter exhibits strong inflection.

  9. The Process ?^{*}_L+ q \\to q\\bar{q}g + q: Real Corrections to the Virtual Photon Impact Factor

    E-print Network

    J. Bartels; S. Gieseke; A. Kyrieleis

    2001-07-13

    We calculate, for the longitudinally polarized virtual photon, the cross section of the process \\gamma^{*}+q\\to (q\\bar{q}g)+q at high energies with a large rapidity gap between the fragmentation system q\\bar{q}g and the other quark. This process provides the real corrections of the virtual photon impact factor in the next-to leading order. Evidence is given for the appearance of a new q\\bar{q}g Fock-component of the photon state.

  10. Metabolic Correction of Congenital Erythropoietic Porphyria with iPSCs Free of Reprogramming Factors

    PubMed Central

    Bedel, Aurélie; Taillepierre, Miguel; Guyonnet-Duperat, Véronique; Lippert, Eric; Dubus, Pierre; Dabernat, Sandrine; Mautuit, Thibaud; Cardinaud, Bruno; Pain, Catherine; Rousseau, Benoît; Lalanne, Magalie; Ged, Cécile; Duchartre, Yann; Richard, Emmanuel; de Verneuil, Hubert; Moreau-Gaudry, François

    2012-01-01

    Congenital erythropoietic porphyria (CEP) is due to a deficiency in the enzymatic activity of uroporphyrinogen III synthase (UROS); such a deficiency leads to porphyrin accumulation and results in skin lesions and hemolytic anemia. CEP is a candidate for retrolentivirus-mediated gene therapy, but recent reports of insertional leukemogenesis underscore the need for safer methods. The discovery of induced pluripotent stem cells (iPSCs) has opened up new horizons in gene therapy because it might overcome the difficulty of obtaining sufficient amounts of autologous hematopoietic stem cells for transplantation and the risk of genotoxicity. In this study, we isolated keratinocytes from a CEP-affected individual and generated iPSCs with two excisable lentiviral vectors. Gene correction of CEP-derived iPSCs was obtained by lentiviral transduction of a therapeutic vector containing UROS cDNA under the control of an erythroid-specific promoter shielded by insulators. One iPSC clone, free of reprogramming genes, was obtained with a single proviral integration of the therapeutic vector in a genomic safe region. Metabolic correction of erythroblasts derived from iPSC clones was demonstrated by the disappearance of fluorocytes. This study reports the feasibility of porphyria gene therapy with the use of iPSCs. PMID:22795135

  11. A Fourier approach for estimating and correcting the topographic perturbation of low-temperature thermochronological data

    NASA Astrophysics Data System (ADS)

    Glotzbach, C.; Braun, J.; van der Beek, P.

    2015-05-01

    Thermochronology is a unique tool to reconstruct the long-term exhumation history of outcropping rocks. Pronounced (palaeo-) topography can markedly perturb near-surface isotherms, which can result in erroneous exhumation histories derived from age-elevation relationships but also offers the possibility to reconstruct palaeo-topography. Here we use a synthetic dataset to illustrate the complex non-linear relationships between the degree of topographic perturbation of thermochronological ages on one hand, and exhumation rate, geothermal gradient, and topographic wavelength and relief on the other. The dataset reveals that, in theory, relief changes can be retrieved for wavelengths as low as 5 km, and wavelength changes are possible to detect for relief as low as 0.5 km. In addition, the data attest that even in regions characterised by very slow exhumation rates (e.g. 0.03 km/Ma), changes in palaeo-topography can be successfully retrieved. Coupling of this dataset with a Fast Fourier Transform (FFT) algorithm to decompose complex 2D topography into sinusoidal functions allows a rapid and accurate estimation of the topographic perturbation and resulting thermochronological ages assuming steady-state exhumation. This coupled method was successfully implemented to (i) predict most promising sample sites for the estimation of palaeo-topography and (ii) correct exhumation rates derived from non-vertical age-elevation profiles.

  12. On the importance of high-frequency air-temperature fluctuations for spectroscopic corrections of open-path carbon dioxide flux measurements

    NASA Astrophysics Data System (ADS)

    Bogoev, Ivan; Helbig, Manuel; Sonnentag, Oliver

    2015-04-01

    A growing number of studies report systematic differences in CO2 flux estimates obtained with the two main types of gas analyzers: compared to eddy-covariance systems based on closed-path (CP) gas analyzers, systems with open-path (OP) gas analyzers systematically overestimate CO2 uptake during daytime periods with high positive sensible heat fluxes, while patterns for differences in nighttime CO2 exchange are less obvious. These biases have been shown to correlate with the sign and the magnitude of the sensible heat flux and to introduce large uncertainties when calculating annual CO2 budgets. In general, CP and OP gas analyzers commonly used to measure the CO2 density in the atmosphere operate on the principle of infrared light absorption approximated by Beer-Lambert's law. Non-dispersive interference-based optical filter elements are used to select spectral bands with strong attenuation of light transmission, characteristic to the gas of interest. The intensity of the light passing through the optical sensing path depends primarily on the amount of absorber gas in the measurement volume. Besides the density of the gas, barometric pressure and air temperature are additional factors affecting the strength and the half-width of the absorption lines. These so-called spectroscopic effects are accounted for by measuring barometric pressure and air temperature in the sensing path and scaling the light-intensity measurements before applying the calibration equation. This approach works well for CP gas analyzers with an intake tube that acts as a low-pass filter on fast air-temperature fluctuations. Low-frequency response temperature sensors in the measurement cell are therefore sufficient to account for spectroscopic temperature effects. In contrast, OP gas analyzers are exposed to high-frequency air-temperature fluctuations associated with the atmospheric surface-layer turbulent heat exchange. If not corrected adequately, these fast air-temperature variations can cause systematic errors in the CO2 density measurements. Under conditions of high positive or negative sensible heat flux, air-temperature fluctuations are correlated with fluctuations of the vertical wind component and can lead to significant biases in the CO2 flux estimates. This study demonstrates that sonically derived fast-response air temperature in the optical sensing path of an OP gas analyzer can replace the slow-response measurements from the temperature sensor as a scaling parameter in the calibration model to correct for these air temperature-induced spectroscopic effects. Our approach is evaluated by comparison between different OP and CP gas analyzer-based eddy-covariance systems in ecosystems with low CO2 uptake under a range of sensible heat flux regimes and varying meteorological parameters. We show that ignoring high-frequency spectroscopic effects can lead to false interpretations of net ecosystem CO2 exchange for specific site and environmental conditions.

  13. In Vivo Gene Therapy of Hemophilia B: Sustained Partial Correction in Factor IX-Deficient Dogs

    NASA Astrophysics Data System (ADS)

    Kay, Mark A.; Rothenberg, Steven; Landen, Charles N.; Bellinger, Dwight A.; Leland, Frances; Toman, Carol; Finegold, Milton; Thompson, Arthur R.; Read, M. S.; Brinkhous, Kenneth M.; Woo, Savio L. C.

    1993-10-01

    The liver represents a model organ for gene therapy. A method has been developed for hepatic gene transfer in vivo by the direct infusion of recombinant retroviral vectors into the portal vasculature, which results in the persistent expression of exogenous genes. To determine if these technologies are applicable for the treatment of hemophilia B patients, preclinical efficacy studies were done in a hemophilia B dog model. When the canine factor IX complementary DNA was transduced directly into the hepatocytes of affected dogs in vivo, the animals constitutively expressed low levels of canine factor IX for more than 5 months. Persistent expression of the clotting. factor resulted in reductions of whole blood clotting and partial thromboplastin times of the treated animals. Thus, long-term treatment of hemophilia B patients may be feasible by direct hepatic gene therapy in vivo.

  14. Correcting instruments applied to displacement and turbine gas meters

    Microsoft Academic Search

    Comerford

    1984-01-01

    Correcting instruments offer an advantage over conventional chart recording instruments in that the correction factors for varying line pressures and temperatures are automatically applied to gas flow volume to give a direct readout of corrected volume. This eliminates the need for handling and integrating circular charts. MERCOR III CORRECTORS retain the flexibility, however, to be mounted with a circular chart

  15. Correcting for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown Dwarfs

    E-print Network

    Stassun, Keivan G; Scholz, Aleks; Dupuy, Trent J

    2012-01-01

    We present empirical relations for determining the amount by which the effective temperatures and radii---and therefore the estimated masses---of low-mass stars and brown dwarfs are altered due to chromospheric activity. Accurate estimates of stellar radii are especially important in the context of searches for transiting exoplanets, which rely upon the assumed stellar radius/density to infer the planet radius/density. Our relations are based on a large set of well studied low-mass stars in the field and on a set of benchmark low-mass eclipsing binaries. The relations link the amount by which an active object's temperature is suppressed, and its radius inflated, to the strength of its Halpha emission. These relations are found to approximately preserve bolometric luminosity. We apply these relations to the peculiar brown-dwarf eclipsing binary 2M0535-05, in which the active, higher-mass brown dwarf has a cooler temperature than its inactive, lower-mass companion. The relations correctly reproduce the observed...

  16. Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

  17. Stress intensity factor correction for asymmetric through-thickness fatigue cracks at holes

    Microsoft Academic Search

    D. Stefanescu; L. Edwards; M. E. Fitzpatrick

    2003-01-01

    This study concerns the growth of fatigue cracks from fastener holes. Cracks growing from fastener holes may evolve a complex eccentric shape, which makes calculation of the stress intensity factor problematic. This is particularly true for cases such as cold expanded holes, where there can be a through-thickness variation in the residual stress field. A methodology for the empirical derivation

  18. A high density 48 V 200 A rectifier with power factor correction-an engineering overview

    Microsoft Academic Search

    D. Chapman; D. James; C. J. Tuck

    1993-01-01

    In telecommunications installations it is desirable for power equipment to draw a balanced three phase current at unity power factor with zero neutral current. A compact 48 V, 200 A rectifier weighing 32 kg has been commercially developed for this need. The rectifier employs the power conversion techniques first reported at INTELEC 1989 by Dennis Chapman of Swichtec Power Systems

  19. Single current sensor control for single-phase active power factor correction

    Microsoft Academic Search

    D.-Y. Qiu; S.-C. Yip; H. S. H. Chung; S. Y. R. Hui

    2002-01-01

    This paper presents the realization of a boost-type active power factor corrector (APFC) using a single current sensor to sense the inductor current for input current shaping and output voltage regulation. Neither input voltage nor output voltage sensing is needed. The sensed inductor current is used for two main functions. The first one is for comparing with a sawtooth signal

  20. Impact of gamma-V vertex corrections on the V-P-gamma transition form factors

    E-print Network

    Sergii Raspopov

    2014-02-06

    The aim of this paper is to present an effective field theory description of the conversion transition of the vector meson V into the pseudoscalar P and the lepton-pair l+l-. The normalized form factor for omega to pi^0 gamma^ast transition is presented and compared to the available data and to the predictions of other models.

  1. Low temperature coefficient of resistance and high gage factor in beryllium-doped silicon

    NASA Technical Reports Server (NTRS)

    Robertson, J. B.; Littlejohn, M. A.

    1974-01-01

    The gage factor and resistivity of p-type silicon doped with beryllium was studied as a function of temperature, crystal orientation, and beryllium doping concentration. It was shown that the temperature coefficient of resistance can be varied and reduced to zero near room temperature by varying the beryllium doping level. Similarly, the magnitude of the piezoresistance gage factor for beryllium-doped silicon is slightly larger than for silicon doped with a shallow acceptor impurity such as boron, whereas the temperature coefficient of piezoresistance is about the same for material containing these two dopants. These results are discussed in terms of a model for the piezoresistance of compensated p-type silicon.

  2. Correction factors for the determination of bromine with NAA through the activation of {sup 79}Br

    SciTech Connect

    Biegalski, S.R.; Landsberger, S.

    1994-12-31

    The study of environmental aerosol samples often includes analysis of the element bromine. This element is found in most environments and has both anthropogenic and natural sources. Bromine is a trace element in the uncontrolled particulate emissions of oil combustion at utilities, industrial processes with iron and steel, and also a by-product of gypsum production. A major source for bromine in urban areas has been auto emissions. In rural and remote areas, bromine quite often emanates from marine origin. In fact Bottenheim et al. have examined the depletion of ozone during the Arctic sunrise and its correlation to the increase of bromine. Neutron activation analysis (NAA) has been used as an elemental detection method in aerosol and other environmental samples for many elements including bromine. However, Tobler et al. indicated that corrections must be made in calculations of bromine concentrations due to the {sup 79}Br(n, {gamma}){sup 80m}Br {yields} {sup 80}Br reaction. The {sup 80m}Br has a half-life of 4.2 h, while {sup 80}Br has a half-life of 17.7 min. Since for short-lived NAA, the irradiation, decay, and counting times vary, it is desirable to have an equation that will account for the additional {sup 80}Br resulting from {sup 80m}Br. This equation may then be used in any NAA irradiation/decay/counting scheme. The derivation of such an equation, discussion of errors, and validation using experimental results are discussed in this paper.

  3. Transforming growth factor-? superfamily ligand trap ACE-536 corrects anemia by promoting late-stage erythropoiesis.

    PubMed

    Suragani, Rajasekhar N V S; Cadena, Samuel M; Cawley, Sharon M; Sako, Dianne; Mitchell, Dianne; Li, Robert; Davies, Monique V; Alexander, Mark J; Devine, Matthew; Loveday, Kenneth S; Underwood, Kathryn W; Grinberg, Asya V; Quisel, John D; Chopra, Rajesh; Pearsall, R Scott; Seehra, Jasbir; Kumar, Ravindra

    2014-04-01

    Erythropoietin (EPO) stimulates proliferation of early-stage erythrocyte precursors and is widely used for the treatment of chronic anemia. However, several types of EPO-resistant anemia are characterized by defects in late-stage erythropoiesis, which is EPO independent. Here we investigated regulation of erythropoiesis using a ligand-trapping fusion protein (ACE-536) containing the extracellular domain of human activin receptor type IIB (ActRIIB) modified to reduce activin binding. ACE-536, or its mouse version RAP-536, produced rapid and robust increases in erythrocyte numbers in multiple species under basal conditions and reduced or prevented anemia in murine models. Unlike EPO, RAP-536 promoted maturation of late-stage erythroid precursors in vivo. Cotreatment with ACE-536 and EPO produced a synergistic erythropoietic response. ACE-536 bound growth differentiation factor-11 (GDF11) and potently inhibited GDF11-mediated Smad2/3 signaling. GDF11 inhibited erythroid maturation in mice in vivo and ex vivo. Expression of GDF11 and ActRIIB in erythroid precursors decreased progressively with maturation, suggesting an inhibitory role for GDF11 in late-stage erythroid differentiation. RAP-536 treatment also reduced Smad2/3 activation, anemia, erythroid hyperplasia and ineffective erythropoiesis in a mouse model of myelodysplastic syndromes (MDS). These findings implicate transforming growth factor-? (TGF-?) superfamily signaling in erythroid maturation and identify ACE-536 as a new potential treatment for anemia, including that caused by ineffective erythropoiesis. PMID:24658078

  4. Sunshine-Factor Model with Treshold GARCH for Predicting Temperature of Weather Contracts

    E-print Network

    Paris-Sud XI, Université de

    Sunshine-Factor Model with Treshold GARCH for Predicting Temperature of Weather Contracts Hélène Hamisultane August 28, 2008 ABSTRACT Climate changes have sparked growing interest for the weather in the literature to model the behaviour of the temperature which is the basis of most of the traded weather

  5. 674 BULLETIN OF THE BUREAU OF FISHERIES FACTORS GOVERNING THE TEMPERATURE OF THE

    E-print Network

    The temperature of the gulf, like that of other boreal seas, is governed by a. complex of factors into which. The absorption of heat by the water from warm air blowing over its surface exerts much less effect on the sea temperature. This last statement rests on the fact that the capacity of sea water for heat (technically its

  6. Correction of Hypertension by Normalization of Endothelial Levels of Fibroblast Growth Factor and Nitric Oxide Synthase in Spontaneously Hypertensive Rats

    NASA Astrophysics Data System (ADS)

    Cuevas, Pedro; Garcia-Calvo, Margarita; Carceller, Fernando; Reimers, Diana; Zazo, Mercedes; Cuevas, Begona; Munoz-Willery, Isabel; Martinez-Coso, Victoria; Lamas, Santiago; Gimenez-Gallego, Guillermo

    1996-10-01

    Acidic and basic fibroblast growth factors (FGFs) share a wide range of diverse biological activities. To date, low levels of FGF have not been correlated with a pathophysiologic state. We report that blood vessels of spontaneously hypertensive rats are shown to be associated with a marked decrement in endothelial basic FGF content. This decrement correlates both with hypertension and with a decrease in the endothelial content of nitric oxide synthase. restoration of FGF to physiological levels in the vascular wall, either by systemic administration or by in vivo gene transfer, significantly augmented the number of endothelial cells with positive immunostaining for nitric oxide synthase, corrected hypertension, and ameliorated endothelial-dependent responses to vasoconstrictors. These results suggest an important role for FGFs in blood pressure homeostasis and open new avenues for the understanding of the etiology and treatment of hypertension.

  7. A zymogen-like factor Xa variant corrects the coagulation defect in hemophilia.

    PubMed

    Ivanciu, Lacramioara; Toso, Raffaella; Margaritis, Paris; Pavani, Giulia; Kim, Haein; Schlachterman, Alexander; Liu, Jian-Hua; Clerin, Valerie; Pittman, Debra D; Rose-Miranda, Rosalind; Shields, Kathleen M; Erbe, David V; Tobin, James F; Arruda, Valder R; Camire, Rodney M

    2011-11-01

    Effective therapies are needed to control excessive bleeding in a range of clinical conditions. We improve hemostasis in vivo using a conformationally pliant variant of coagulation factor Xa (FXa(I16L)) rendered partially inactive by a defect in the transition from zymogen to active protease. Using mouse models of hemophilia, we show that FXa(I16L) has a longer half-life than wild-type FXa and does not cause excessive activation of coagulation. Once clotting mechanisms are activated to produce its cofactor FVa, FXa(I16L) is driven to the protease state and restores hemostasis in hemophilic animals upon vascular injury. Moreover, using human or murine analogs, we show that FXa(I16L) is more efficacious than FVIIa, which is used to treat bleeding in hemophilia inhibitor patients. FXa(I16L) may provide an effective strategy to enhance blood clot formation and act as a rapid pan-hemostatic agent for the treatment of bleeding conditions. PMID:22020385

  8. Hydrogen isotopic fractionation factor between brucite and water in the temperature range from 100° to 510° C

    Microsoft Academic Search

    Hiroshi Satake; Sadao Matsuo

    1984-01-01

    The hydrogen isotopic fractionation factor between brucite and water has been determined in the temperature range of 100°–510° C. Brucite is always depleted in deuterium relative to the coexisting water, and the degree of depletion becomes larger with decreasing temperature. The fractionation factor changes smoothly in the temperature range of 144°–510° C and its temperature dependence was obtained by the

  9. An Empirical Correction for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown Dwarfs

    E-print Network

    Stassun, Keivan G; Scholz, Aleks; Dupuy, Trent J

    2012-01-01

    We present an empirical relations for correcting the estimated masses, effective temperatures, and radii of chromospherically active low-mass stars and brown dwarfs. We base our corrections on a large set of low-mass stars in the field with Halpha activity measurements, and on a set of low-mass eclipsing binaries with X-ray activity measurements from which we indirectly infer the Halpha activity. Both samples yield consistent relations linking the amount by which an active object's temperature is suppressed, and the amount by which its radius is inflated, to the strength of its Halpha emission. Bolometric luminosity is found to be approximately preserved by these temperature and radius corrections. We apply these relations to the peculiar brown-dwarf eclipsing binary 2M0535-05, in which the active, higher-mass brown dwarf has a cooler temperature than its inactive, lower-mass companion. We find that the Halpha-corrected temperatures bring the inferred masses of the brown dwarfs into agreement with theoretical...

  10. Experimental determination of mode correction factors for thermal method spring constant calibration of AFM cantilevers using laser Doppler vibrometry.

    PubMed

    Gates, Richard S; Osborn, William A; Pratt, Jon R

    2013-06-28

    Mode correction factors (MCFs) represent a significant adjustment to the spring constant values measured using the thermal cantilever calibration method. Usually, the ideal factor of 0.971 for a tipless rectangular cantilever is used, which adjusts the value by 3% for the first flexural mode. An experimental method for determining MCFs has been developed that relies on measuring the areas under the first few resonance peaks for the flexural mode type. Using this method, it has been shown that MCFs for the first flexural mode of commercially available atomic force microscope cantilevers actually vary from 0.95 to 1.0, depending on the shape and end mass of the cantilever. Triangular shaped cantilevers tend to lower MCFs with tipless versions providing the lowest values. Added masses (including tips) tend to increase the first flexural mode's MCF to higher values with large colloid probes at the high extreme. Using this understanding and applying it to the recently developed laser Doppler vibrometry thermal calibration method it is now possible to achieve very accurate and precise cantilever spring constant calibrations (uncertainties close to ±1%) with commonly available commercial cantilevers such as tipped rectangular and triangular cantilevers, and colloid probes. PMID:23723188

  11. Temperature Data Assimilation with Salinity Corrections: Validation for the NSIPP Ocean Data Assimilation System in the Tropical Pacific Ocean, 1993-1998

    NASA Technical Reports Server (NTRS)

    Troccoli, Alberto; Rienecker, Michele M.; Keppenne, Christian L.; Johnson, Gregory C.

    2003-01-01

    The NASA Seasonal-to-Interannual Prediction Project (NSIPP) has developed an Ocean data assimilation system to initialize the quasi-isopycnal ocean model used in our experimental coupled-model forecast system. Initial tests of the system have focused on the assimilation of temperature profiles in an optimal interpolation framework. It is now recognized that correction of temperature only often introduces spurious water masses. The resulting density distribution can be statically unstable and also have a detrimental impact on the velocity distribution. Several simple schemes have been developed to try to correct these deficiencies. Here the salinity field is corrected by using a scheme which assumes that the temperature-salinity relationship of the model background is preserved during the assimilation. The scheme was first introduced for a zlevel model by Troccoli and Haines (1999). A large set of subsurface observations of salinity and temperature is used to cross-validate two data assimilation experiments run for the 6-year period 1993-1998. In these two experiments only subsurface temperature observations are used, but in one case the salinity field is also updated whenever temperature observations are available.

  12. SU-E-T-101: Determination and Comparison of Correction Factors Obtained for TLDs in Small Field Lung Heterogenous Phantom Using Acuros XB and EGSnrc

    SciTech Connect

    Soh, R [Nanyang Technological University, Singapore (Singapore); Lee, J [National Cancer Centre Singapore, Singapore (Singapore); Harianto, F [Institute of Technology Bandung (Indonesia)

    2014-06-01

    Purpose: To determine and compare the correction factors obtained for TLDs in 2 × 2cm{sup 2} small field in lung heterogenous phantom using Acuros XB (AXB) and EGSnrc. Methods: This study will simulate the correction factors due to the perturbation of TLD-100 chips (Harshaw/Thermoscientific, 3 × 3 × 0.9mm{sup 3}, 2.64g/cm{sup 3}) in small field lung medium for Stereotactic Body Radiation Therapy (SBRT). A physical lung phantom was simulated by a 14cm thick composite cork phantom (0.27g/cm{sup 3}, HU:-743 ± 11) sandwiched between 4cm thick Plastic Water (CIRS,Norfolk). Composite cork has been shown to be a good lung substitute material for dosimetric studies. 6MV photon beam from Varian Clinac iX (Varian Medical Systems, Palo Alto, CA) with field size 2 × 2cm{sup 2} was simulated. Depth dose profiles were obtained from the Eclipse treatment planning system Acuros XB (AXB) and independently from DOSxyznrc, EGSnrc. Correction factors was calculated by the ratio of unperturbed to perturbed dose. Since AXB has limitations in simulating actual material compositions, EGSnrc will also simulate the AXB-based material composition for comparison to the actual lung phantom. Results: TLD-100, with its finite size and relatively high density, causes significant perturbation in 2 × 2cm{sup 2} small field in a low lung density phantom. Correction factors calculated by both EGSnrc and AXB was found to be as low as 0.9. It is expected that the correction factor obtained by EGSnrc wlll be more accurate as it is able to simulate the actual phantom material compositions. AXB have a limited material library, therefore it only approximates the composition of TLD, Composite cork and Plastic water, contributing to uncertainties in TLD correction factors. Conclusion: It is expected that the correction factors obtained by EGSnrc will be more accurate. Studies will be done to investigate the correction factors for higher energies where perturbation may be more pronounced.

  13. Dependence of Yb-169 absorbed dose energy correction factors on self-attenuation in source material and photon buildup in water

    SciTech Connect

    Medich, David C.; Munro, John J. III [Radiation Laboratory, University of Massachusetts Lowell, 1 University Avenue, Lowell, Massachusetts 01854 (United States); Source Production and Equipment Co., Inc., 113 Teal Street, St. Rose, Louisiana 70087 (United States)

    2010-05-15

    Purpose: Absorbed dose energy correction factors, used to convert the absorbed dose deposited in a LiF thermoluminescent dosimeter (TLD) into the clinically relevant absorbed dose to water, were obtained for both spherical volumetric sources and for the model 4140 HDR Yb-169 source. These correction factors have a strong energy dependence below 200 keV; therefore, spectral changes were quantified as Yb-169 photons traveled through both source material (Yb{sub 2}O{sub 3}) and water with the corresponding absorbed dose energy correction factors, f(r,{theta}), calculated as a function of location in a phantom. Methods: Using the MCNP5 Monte Carlo radiation transport simulation program, the Yb-169 spectrum emerging from spherical Yb{sub 2}O{sub 3} sources (density 6.9 g/cm{sup 3}) with radii between 0.2 and 0.9 mm were analyzed and their behavior compared against those for a point-source. The absorbed dose deposited to both LiF and H{sub 2}O materials was analyzed at phantom depths of 0.1-10 cm for each source radius and the absorbed dose energy correction factor calculated as the ratio of the absorbed dose to water to that of LiF. Absorbed dose energy correction factors for the Model 4140 Yb-169 HDR brachytherapy source similarly were obtained and compared against those calculated for the Model M-19 Ir-192 HDR source. Results: The Yb-169 average spectral energy, emerging from Yb{sub 2}O{sub 3} spherical sources 0.2-0.9 mm in radius, was observed to harden from 7% to 29%; as these photons traveled through the water phantom, the photon average energy softened by as much as 28% at a depth of 10 cm. Spectral softening was dependent on the measurement depth in the phantom. Energy correction factors were found to vary both as a function of source radius and phantom depth by as much as 10% for spherical Yb{sub 2}O{sub 3} sources. The Model 4140 Yb-169 energy correction factors depended on both phantom depth and reference angle and were found to vary by more than 10% between depths of 1 and 10 cm and angles of 0 deg. and 180 deg. This was in contrast to that of the Model M-19 Ir-192 source which exhibited approximately 3.5%-4.4% variation in its energy correction factors from phantom depths of 0.5-10 cm. The absorbed dose energy correction factor for the Ir-192 source, on the other hand, was independent of angle to within 1%. Conclusions: The application of a single energy correction factor for Yb-169 TLD based dosimetry would introduce a high degree of measurement uncertainty that may not be reasonable for the clinical characterization of a brachytherapy source; rather, an absorbed dose energy correction function will need to be developed for these sources. This correction function should be specific to each source model, type of TLD used, and to the experimental setup to obtain accurate and precise dosimetric measurements.

  14. Two-factor simplex optimization of a programmed temperature gas chromatographic separation. [Ethylbenzene, butycyclohexane

    SciTech Connect

    Walters, F.H.; Deming, S.N.

    1984-01-01

    Simplex optimization was used to optimize the temperature programmed gas chromatographic separation of octane, 2-methyl-tetrahydrofuran, butylcyclohexane, and ethylbenzene. The initial temperature and the programming rate were the factors studied and a 5 minute time constraint was placed on the system. The Chromatographic Response Function (CRF) used by Deming and Morgan was used as an operational measure of performance. Further experiments in the region of the optimum and regression analysis of the data obtained were carried out to further understand the factor effects. 9 references, 2 figures, 2 tables.

  15. Temperature and donor concentration dependence of the conduction electron Lande g-factor in silicon

    SciTech Connect

    Konakov, Anton A.; Ezhevskii, Alexander A.; Soukhorukov, Andrey V.; Guseinov, Davud V.; Popkov, Sergey A.; Burdov, Vladimir A. [Department of Physics, University of Nizhniy Novgorod, Gagarin ave. 23, Nizhniy Novgorod, 603950 (Russian Federation)

    2013-12-04

    Temperature and donor concentration dependence of the conduction electron g-factor in silicon has been investigated both experimentally and theoretically. We performed electron spin resonance experiments on Si samples doped with different densities of phosphorus and lithium. Theoretical consideration is based on the renormalization of the electron energy in a weak magnetic field by the interaction with possible perturbing agents, such as phonons and impurity centers. In the second-order perturbation theory interaction of the electron subsystem with the lattice vibrations as well as ionized donors results in decreasing the conduction electron g-factor, which becomes almost linear function both of temperature and impurity concentration.

  16. Correction factors kE and kQ for LiF-TLDs for dosimetry in megavoltage electron and photon beams.

    PubMed

    Bruggmoser, Gregor; Saum, Rainer; Saum, Felicitas; Gainey, Mark; Pychlau, Christian; Kapsch, Ralf-Peter; Zink, Klemens

    2015-06-01

    For the determination of absorbed dose to water D,using thermolumeniscence (TL) probes in a beam different from that used for calibration, correction factors for radiation type and radiation quality kE and kQ are needed. Values for kE and kQ for two different shapes of LiF probes (rods and disks) were obtained for high-energy photon and electron beams. The relation between the absorbed dose to the medium (water) D, measured by ion-chambers according to DIN 6800-2, 2008 and TL-probes having a (60)Co-calibration factor, leads for each shape and each batch of LiF probes to correction factors for radiation type and radiation quality kE and kQ.. The influence of the shape on the correction factor of the probes amounts in our experiment up to 2%. Therefore, it is recommended that the correction factors kE and kQ for rods and disks should be checked for each batch of LiF-detectors. PMID:24973310

  17. An algorithm for temperature correcting substrate moisture measurements: aligning substrate moisture responses with environmental drivers in polytunnel-grown strawberry plants

    NASA Astrophysics Data System (ADS)

    Goodchild, Martin; Janes, Stuart; Jenkins, Malcolm; Nicholl, Chris; Kühn, Karl

    2015-04-01

    The aim of this work is to assess the use of temperature corrected substrate moisture data to improve the relationship between environmental drivers and the measurement of substrate moisture content in high porosity soil-free growing environments such as coir. Substrate moisture sensor data collected from strawberry plants grown in coir bags installed in a table-top system under a polytunnel illustrates the impact of temperature on capacitance-based moisture measurements. Substrate moisture measurements made in our coir arrangement possess the negative temperature coefficient of the permittivity of water where diurnal changes in moisture content oppose those of substrate temperature. The diurnal substrate temperature variation was seen to range from 7° C to 25° C resulting in a clearly observable temperature effect in substrate moisture content measurements during the 23 day test period. In the laboratory we measured the ML3 soil moisture sensor (ThetaProbe) response to temperature in Air, dry glass beads and water saturated glass beads and used a three-phase alpha (?) mixing model, also known as the Complex Refractive Index Model (CRIM), to derive the permittivity temperature coefficients for glass and water. We derived the ? value and estimated the temperature coefficient for water - for sensors operating at 100MHz. Both results are good agreement with published data. By applying the CRIM equation with the temperature coefficients of glass and water the moisture temperature coefficient of saturated glass beads has been reduced by more than an order of magnitude to a moisture temperature coefficient of

  18. Identification of possible factors influencing temperatures elevation during implant site preparation with piezoelectric technique

    PubMed Central

    Lamazza, Luca; Laurito, Domenica; Lollobrigida, Marco; Brugnoletti, Orlando; Garreffa, Girolamo; De Biase, Alberto

    2014-01-01

    Summary Background Overheating during implant site preparation negatively affects the osseointegration process as well the final outcome of implant rehabilitations. Piezoelectric techniques seem to provide to a gentle implant preparation although few scientific reports have investigated the heat generation and its underlying factors. Purpose To investigate, through a proper methodological approach, the main factors influencing temperature rise during piezoelectric implant site preparation. Materials and methods Different piezoelectric tips (IM1s, IM2, P2-3, IM3, Mectron Medical Technology, Carasco, Italy) have been tested. The experimental set-up consisted in a mechanical positioning device equipped with a load cell and a fluoroptic thermometer. Results The first tip of the sequence (IM1s) generated the highest temperature increasing (?T). The diamond tips (IM1s and P2-3) determined higher ?T values than the smooth tips (IM2 and IM3). Further tests with IM1s suggested that the temperature elevation during the first thirty seconds may be predictive of the maximal temperature as well as of the overall thermal impact. Conclusions Working load, working movements management and bone features resulted to be the main factors influencing temperature rise during piezoelectric implant site preparation. Irrigant temperature and clogging effect may also synergically contribute to the heat generation. PMID:25774245

  19. Field calibration of multi-scattering correction factor for aethalometer aerosol absorption coefficient during CAPMEX Campaign, 2008

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Kim, S. W.; Yoon, S. C.; Park, R.; Ogren, J. A.

    2014-12-01

    Filter-based instrument, such as aethalometer, is being widely used to measure equivalent black carbon(EBC) mass concentration and aerosol absorption coefficient(AAC). However, many other previous studies have poited that AAC and its aerosol absorption angstrom exponent(AAE) are strongly affected by the multi-scattering correction factor(C) when we retrieve AAC from aethalometer EBC mass concentration measurement(Weingartner et al., 2003; Arnott et al., 2005; Schmid et al., 2006; Coen et al., 2010). We determined the C value using the method given in Weingartner et al. (2003) by comparing 7-wavelngth aethalometer (AE-31, Magee sci.) to 3-wavelength Photo-Acoustic Soot Spectrometer (PASS-3, DMT) at Gosan climate observatory, Korea(GCO) during Cheju ABC plume-asian monsoon experiment(CAPMEX) campaign(August and September, 2008). In this study, C was estimated to be 4.04 ± 1.68 at 532 nm and AAC retrieved with this value was decreased as approximately 100% as than that retrieved with soot case value from Weingartner et al (2003). We compared the AAC determined from aethalomter measurements to that from collocated Continuous Light Absorption Photometer (CLAP) measurements from January 2012 to December 2013 at GCO and found good agreement in both AAC and AAE. This result suggests the determination of site-specific C is crucially needed when we calculate AAC from aethalometer measurements.

  20. Monte Carlo calculations of monoenergetic electron depth dose distributions in LiF chips: skin dose correction factors for beta rays.

    PubMed

    Horowitz, Y S; Hirning, C R; Yuen, P; Wong, P

    1994-10-01

    Monte Carlo calculations have been carried out for monoenergetic electrons from 0.1 to 4 MeV irradiating LiF chips in both perpendicular and isotropic geometry. This enabled the calculation of skin dose correction factors (beta factors) for typical beta energy spectra as measured with a beta-ray spectrometer at CANDU nuclear generating stations. The correction factors were estimated by averaging the depth dose distributions for the monoenergetic electrons over the experimentally measured beta-ray spectra. The calculations illustrate the large uncertainty in beta factors arising from the unknown angular distribution of the beta-ray radiation field and uncertainties in the shape of the beta-ray spectra below 500 keV. PMID:8083045

  1. Systematic Error Correction of Dynamical Seasonal Prediction of Sea Surface Temperature Using a Stepwise Pattern Project Method

    Microsoft Academic Search

    Jong-Seong Kug; June-Yi Lee; In-Sik Kang

    2008-01-01

    Every dynamical climate prediction model has significant errors in its mean state and anomaly field, thus degrading its performance in climate prediction. In addition to correcting the model's systematic errors in the mean state, it is also possible to correct systematic errors in the predicted anomalies by means of dynamical or statistical postprocessing. In this study, a new statistical model

  2. Factors controlling cloud microphysics, precipitation rate, and brightness temperature of tropical convective and stratiform clouds

    Microsoft Academic Search

    T. Hashino; D. Casella; A. Mugnai; P. Sano; E. A. Smith; G. Tripoli

    2008-01-01

    This paper discusses factors controlling cloud microphysics, precipitation rate and brightness temperature of tropical convective and stratiform clouds. Tropical convective and stratiform clouds are important in radiative forcing of climates and distribution of precipitation over the ocean. The possible effects of climate change on these clouds are still not well understood. Recent studies show that the higher CCN concentration in

  3. Estradiol and Incubation Temperature Modulate Regulation of Steroidogenic Factor 1 in the Developing

    E-print Network

    Crews, David

    in the development of testes. In mammals, steroi- dogenic factor 1 (SF-1) regulates most genes required for estrogen determination. In chickens, for example, in- hibiting aromatase, the enzyme that converts testosterone- bated at a temperature that produces only females. Ap- plication of aromatase inhibitor (AI) to eggs

  4. FACTORS INFLUENCING YEAR-CLASS STRENGTH OF PERCIDS: A SUMMARY AND A MODEL OF TEMPERATURE EFFECTS

    EPA Science Inventory

    Factors regulating year-class strength in the percid genera Stizostedion and Perca are summarized. Some index of water temperature regime correlates significantly with year-class strength of percids in many waterbodies, in several lakes in North America. A probablistic model is p...

  5. Experimental investigation on altitude correction factor of positive dc corona inception voltages of transmission lines based on the mobile corona cage

    Microsoft Academic Search

    Xingming Bian; Liming Wang; Zhicheng Guan; Jing Cao; Yingjian Yang; Xiong Wu

    2010-01-01

    In order to obtain the altitude correction factor of corona inception voltage of HVDC transmission lines within the range 23 to 4000 meters, a mobile corona test cage was used to research the influence of altitude changes on positive DC corona characteristics of several kinds of conductors. Photons released as a result of corona discharge on the conductors were detected

  6. Relations of Tualatin River water temperatures to natural and human-caused factors

    USGS Publications Warehouse

    Risley, John C.

    1997-01-01

    Aquatic research has long shown that the survival of cold-water fish, such as salmon and trout, decreases markedly as water temperatures increase above a critical threshold, particularly during sensitive life stages of the fish. In an effort to improve the overall health of aquatic ecosystems, the State of Oregon in 1996 adopted a maximum water-temperature standard of 17.8 degrees Celsius (68 degrees Fahrenheit), based on a 7-day moving average of daily maximum temperatures, for most water bodies in the State. Anthropogenic activities are not permitted to raise the temperature of a water body above this level. In the Tualatin River, a tributary of the Willamette River located in northwestern Oregon, water temperatures periodically surpass this threshold during the low-flow summer and fall months.An investigation by the U.S. Geological Survey quantified existing seasonal, diel, and spatial patterns of water temperatures in the main stem of the river, assessed the relation of water temperatures to natural climatic conditions and anthropogenic factors (such as wastewater-treatment-plant effluent and modification of riparian shading), and assessed the impact of various flow management practices on stream temperatures. Half-hourly temperature measurements were recorded at 13 monitoring sites from river mile (RM) 63.9 to RM 3.4 from May to November of 1994. Four synoptic water- temperature surveys also were conducted in the upstream and downstream vicinities of two wastewater-treatment-plant outfalls. Temperature and streamflow time-series data were used to calibrate two dynamic-flow heat-transfer models, DAFLOW-BLTM (RM 63.9-38.4) and CE-QUAL-W2 (RM 38.4-3.4).Simulations from the models provided a basis for approximating 'natural' historical temperature patterns, performing effluent and riparian-shading sensitivity analyses, and evaluating mitigation management scenarios under 1994 climatic conditions. Findings from the investigation included (1) under 'natural' conditions the temperature of the river would exceed the State standard of 17.8 degrees Celsius at many locations during the low-flow season, (2) current operation of wastewater-treatment plants increases the temperature of the river downstream of the plants under low-flow conditions, (3) river temperature is significantly affected by riparian shade variations along both the tributaries and the main stem, (4)flow releases during the low-flow season from the Henry Hagg Lake reservoir decrease the river temperature in the upper section, and (5) removal of a low diversion dam at RM 3.4 would slightly decrease temperatures below RM 10.0.

  7. Factors That Affect Riverbank Filtrate Water Temperature in Daesan Plants, Changwon, Korea

    NASA Astrophysics Data System (ADS)

    Shin, J.; Lim, J.; Lee, K.; Jung, W.; Kim, H.

    2008-12-01

    City of Changwon, Korea, has been using some of riverbank filtrate water for the indoor air-conditioning of Daesan purification plants since 2006. In this method, the most important factor to determine efficiency of heating and cooling is the temperature of the filtrate water. Thus, it is required to predict the available range of groundwater temperature in the case of changing pumping rate, pumping location or in the case of long term operation. Numerical simulation of temperature profile of riverbank filtrate water in Daesan plants using HydroGeoSphere shows that the primary factor in determining filtrate water temperature is the pumping rate. Distance from the river to the wells is long enough to equalize subsurface water temperature through its penetration path and all of the well screen sections are located at the depth of 30 m below surface which is part of the local aquifer. This is why the horizontal distance from the river to each well and the installed screen depth are less important than the pumping rate to determine filtrate water temperature in this facility. It also shows that maintaining the facility operation with present pumping rate for the next 30 years will not cause any significant change of water temperature. However, following the new plan of the city to install additional 37 wells with 6 times higher pumping rate than the current rate might cause about 2? decrease in filtrate water temperature in 10 years after the extension. All of these results demonstrate that basic hydrological study such as aquifer heterogeneity or pumping capacity is prerequisite for calculating and predicting extracted water temperature in riverbank filtration system.

  8. High Temperature as a Risk Factor for Infectious Diarrhea in Shanghai, China

    PubMed Central

    Zhou, Xiaodan; Zhou, Yanbing; Chen, Renjie; Ma, Wenjuan; Deng, Haiju; Kan, Haidong

    2013-01-01

    Background Recent studies indicate that ambient temperature could be a risk factor for infectious diarrhea, but evidence for such a relation is limited in China. Methods We investigated the short-term association between daily temperature and physician-diagnosed infectious diarrhea during 2008–2010 in Shanghai, China. We adopted a time-series approach to analyze the data and a quasi-Poisson regression model with a natural spline-smoothing function to adjust for long-term and seasonal trends, as well as other time-varying covariates. Results There was a significant association between temperature and outpatient visits for diarrhea. A 1°C increase in the 6-day moving average of temperature was associated with a 2.68% (95% CI: 1.83%, 3.52%) increase in outpatient visits for diarrhea. We did not find a significant association between rainfall and infectious diarrhea. Conclusions High temperature might be a risk factor for infectious diarrhea in Shanghai. Public health programs should focus on preventing diarrhea related to high temperature among city residents. PMID:23994865

  9. A New Method to Measure Temperature and Burner Pattern Factor Sensing for Active Engine Control

    NASA Technical Reports Server (NTRS)

    Ng, Daniel

    1999-01-01

    The determination of the temperatures of extended surfaces which exhibit non-uniform temperature variation is very important for a number of applications including the "Burner Pattern Factor" (BPF) of turbine engines. Exploratory work has shown that use of BPF to control engine functions can result in many benefits, among them reduction in engine weight, reduction in operating cost, increase in engine life, while attaining maximum engine efficiency. Advanced engines are expected to operate at very high temperature to achieve high efficiency. Brief exposure of engine components to higher than design temperatures due to non-uniformity in engine burner pattern can reduce engine life. The engine BPF is a measure of engine temperature uniformity. Attainment of maximum temperature uniformity and high temperatures is key to maximum efficiency and long life. A new approach to determine through the measurement of just one radiation spectrum by a multiwavelength pyrometer is possible. This paper discusses a new temperature sensing approach and its application to determine the BPF.

  10. Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Grimbergen, T. W. M.; van Dijk, E.; de Vries, W.

    1998-11-01

    A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range.

  11. Proteomic comparison of Ralstonia solanacearum strains reveals temperature dependent virulence factors

    PubMed Central

    2014-01-01

    Background Ralstonia solanacearum, the causal agent of bacterial wilt, is a genetically diverse bacterial plant pathogen present in tropical and subtropical regions of the world that infects more than 200 plant species, including economically important solanaceous crops. Most strains of R. solanacearum are only pathogenic at temperatures between 25 to 30°C with strains that can cause disease below 20°C considered a threat to agriculture in temperate areas. Identifying key molecular factors that distinguish strains virulent at cold temperatures from ones that are not is needed to develop effective management tools for this pathogen. We compared protein profiles of two strains virulent at low temperature and two strains not virulent at low temperature when incubated in the rhizosphere of tomato seedlings at 30 and 18°C using quantitative 2D DIGE gel methods. Spot intensities were quantified and compared, and differentially expressed proteins were sequenced and identified by mass spectrometry (MS/MS). Results Four hundred and eighteen (418) differentially expressed protein spots sequenced produced 101 unique proteins. The identified proteins were classified in the Gene Ontology biological processes categories of metabolism, cell processes, stress response, transport, secretion, motility, and virulence. Identified virulence factors included catalase (KatE), exoglucanase A (ChbA), drug efflux pump, and twitching motility porin (PilQ). Other proteins identified included two components of a putative type VI secretion system. We confirmed differential expression of 13 candidate genes using real time PCR techniques. Global regulators HrpB and HrpG also had temperature dependent expression when quantified by real time PCR. Conclusions The putative involvement of the identified proteins in virulence at low temperature is discussed. The discovery of a functional type VI secretion system provides a new potential virulence mechanism to explore. The global regulators HrpG and HrpB, and the protein expression profiles identified suggest that virulence at low temperatures can be partially explained by differences in regulation of virulence factors present in all the strains. PMID:24725348

  12. Induction temperature of human heat shock factor is reprogrammed in a Drosophila cell environment

    NASA Astrophysics Data System (ADS)

    Clos, Joachim; Rabindran, Sridhar; Wisniewski, Jan; Wu, Carl

    1993-07-01

    HEAT shock factor (HSF)1,2, the transcriptional activator of eukaryotic heat shock genes, is induced to bind DNA by a monomer to trimer transition involving leucine zipper interactions3,4. Although this mode of regulation is shared among many eukaryotic species, there is variation in the temperature at which HSF binding activity is induced. We investigated the basis of this variation by analysing the response of a human HSF expressed in Drosophila cells and Drosophila HSF expressed in human cells. We report here that the temperature that induces DNA binding and trimerization of human HSF in Drosophila was decreased by ~10 °C to the induction temperature for the host cell, whereas Drosophila HSF expressed in human cells was constitutively active. The results indicate that the activity of HSF in vivo is not a simple function of the absolute environmental temperature.

  13. The effect of temperature on the formation resistivity factor of porous media

    E-print Network

    Brannan, Geryl Owen

    1972-01-01

    TlIE EFFECT OF TEI1PERATU1K ON TllE FOIQEATION RESISTIVITY FACTOR OP POROUS 11EDIA A Thesis by Geryl Omen Ersnncn Submittccl to the G aUvate College of Tc::ss A&N University ic Purtis1 fulfillment of the requirement for th = clegrc of. Pl...ASTER OF SCIENCE December. 1972 major S?b jcct: Petroleum Pnfinccrinf THE EFFECT OF TEMPERATURE ON THE FORMATION RESISTIVITY FACTOR OF POROUS MEDIA A Thesis by Geryl Owen Brannan Approved as to style and content by: Chairman of Committee Head...

  14. A new high performance AC to DC rectifier with input power factor correction and harmonic reduction capacity 

    E-print Network

    Martinez, Roberto

    1994-01-01

    correction and reduced current harmonics. The proposed approach has many advantages which include fewer semiconductor components, simplified control, high performance features, satisfies IEC-555 harmonic current standards, and lends itself to modularization...

  15. Induction temperature of human heat shock factor is reprogrammed in a Drosophila cell environment

    Microsoft Academic Search

    Joachim Clos; Sridhar Rabindran; Jan Wisniewski; Carl Wu

    1993-01-01

    HEAT shock factor (HSF)1,2, the transcriptional activator of eukaryotic heat shock genes, is induced to bind DNA by a monomer to trimer transition involving leucine zipper interactions3,4. Although this mode of regulation is shared among many eukaryotic species, there is variation in the temperature at which HSF binding activity is induced. We investigated the basis of this variation by analysing

  16. Dependence of the form factor of ganglioside micelles on a conformational change with temperature

    NASA Astrophysics Data System (ADS)

    Corti, Mario; Boretta, Marco; Cantù, Laura; Del Favero, Elena; Lesieur, Pierre

    1996-09-01

    The gangliosides GM2, GM1 and GD1b, biological amphiphiles with a double tail hydrophobic part and an oligosaccharide chain headgroup, form micelles in solution. Light scattering experiments have shown that ganglioside micelles which have gone through a temperature cycle have a smaller molecular mass and hydrodynamic radius than those which have been kept at room temperature. This fact has been interpreted with the hypothesis that, with temperature, the ganglioside molecules undergo a conformational change which affects their micellar properties appreciably. Careful small angle X-ray experiments, aimed to confirm the light scattering data and to evidence differences in the micellar internal structure are presented. Ganglioside micelles are quite inhomogeneous particles with respect to X-ray scattering, since there is a large contrast variation between the inner lipid part and the external hydrated sugar layer. Experimental form factors are fitted with a double-shell oblate-ellipsoid model.

  17. Conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation 1948--1951. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Denham, D.H.; Mart, E.I.; Thiede, M.E.

    1993-09-01

    This report is a part of the Hanford Environmental Dose Reconstruction (HEDR) Project, whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The key radionuclide emitted that would affect the radiation dose was iodine-131 (Napier 1992). Because the early methods of measuring iodine-131 were not comparable to later techniques, conversion and correction factors are needed to convert the historical measurement data into concentration values that would be determined using today`s knowledge and technologies. This report describes the conversion and correction factors developed for reconstructing historical measurements of iodine-131 in Hanford-area vegetation, which was collected from 1948 through the end of December 1951.

  18. Determining desorption pre-exponential factors from temperature-programmed desorption spectra when the surface is nonuniform

    SciTech Connect

    Brown, L.F.; Chemburkar, R.M.

    1991-03-15

    To find desorption pre-exponential factors from temperature-programmed desorption (TPD) spectra, we develop procedures using both the TPD spectra and their derivatives. First, an approximate method is derived using peak temperatures. This method is formally identical with one used for determining pre-exponential factors and desorption activation energies when desorptions are energetically uniform. The method can be used when the pre-exponential factor is constant. We next develop an iterative process that also uses peak temperatures, and again is usable when the pre-exponential factor is constant. This iterative approach should give more exact values of pre-exponential factors than the approximate approach. Using the first derivatives of TPD spectra over the entire range of temperatures leads to a second iterative process. This last procedure allows determination of energy-dependent pre-exponential factors. 8 refs., 13 figs.

  19. Conversion and correction factors for historical measurements of Iodine-131 in Hanford-area vegetation, 1945--1947: Draft. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Mart, E.I.; Denham, D.H.; Thiede, M.E.

    1993-05-01

    This report is a result of the Hanford Environmental Dose Reconstruction (HEDR) Project whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The report describes in detail the reconstructed conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation which was collected from the beginning of October 1945 through the end of December 1947.

  20. Evaluation of AlGaN\\/GaN Heterostructure Field-Effect Transistors on Si Substrate in Power Factor Correction Circuit

    Microsoft Academic Search

    Shinichi Iwakami; Osamu Machida; Yoshimichi Izawa; Ryohei Baba; Masataka Yanagihara; Toshihiro Ehara; Nobuo Kaneko; Hirokazu Goto; Akio Iwabuchi

    2007-01-01

    A new device of high-power AlGaN\\/GaN heterostructure field-effect transistors (HFETs) fabricated on a Si substrate is proposed. Its application of the power factor correction (PFC) circuit is presented for the first time. The AlGaN\\/GaN HFETs fabricated on the Si substrate with a gate width of 152 mm exhibited a breakdown voltage of more than 800 V, an on-resistance of 65

  1. A Family of Zero-Voltage-Transition Bridgeless Power-Factor-Correction Circuits With a Zero-Current-Switching Auxiliary Switch

    Microsoft Academic Search

    Hsien-Yi Tsai; Tsun-Hsiao Hsia; Dan Chen

    2011-01-01

    A novel zero-voltage-transition high-efficiency bridgeless power-factor-correction (PFC) circuit with a zero- current-switching auxiliary switch was proposed, analyzed, and experimentally verified. An assist circuit, consisting of a resonant inductor, two blocking diodes, a clamping circuit, an autotransformer, and an auxiliary MOSFET switch, was used to reduce the turn-on switching loss of the two main switches of the bridgeless PFC circuit and

  2. Correction factors for A1SL ionization chamber dosimetry in TomoTherapy: Machine-specific, plan-class, and clinical fields

    SciTech Connect

    Gago-Arias, Araceli; Rodriguez-Romero, Ruth; Sanchez-Rubio, Patricia; Miguel Gonzalez-Castano, Diego; Gomez, Faustino; Nunez, Luis; Palmans, Hugo; Sharpe, Peter; Pardo-Montero, Juan [Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela (Spain); Servicio de Radiofisica, Hospital Universitario Puerta de Hierro, Madrid 28222 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela, 15782 (Spain) and Radiation Physics Laboratory, Universidad de Santiago de Compostela, 15782 (Spain); Servicio de Radiofisica, Hospital Universitario Puerta de Hierro, Madrid, 28222 (Spain); National Physical Laboratory, Teddington, Middx, TW11 OLW (United Kingdom); Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela, 15782 (Spain)

    2012-04-15

    Purpose: Recently, an international working group on nonstandard fields presented a new formalism for ionization chamber reference dosimetry of small and nonstandard fields [Alfonso et al., Med. Phys. 35, 5179-5186 (2008)] which has been adopted by AAPM TG-148. This work presents an experimental determination of the correction factors for reference dosimetry with an Exradin A1SL thimble ionization chamber in a TomoTherapy unit, focusing on: (i) machine-specific reference field, (ii) plan-class-specific reference field, and (iii) two clinical treatments. Methods: Ionization chamber measurements were performed in the TomoTherapy unit for intermediate (machine-specific and plan-class-specific) calibration fields, based on the reference conditions defined by AAPM TG-148, and two clinical treatments (lung and head-and-neck). Alanine reference dosimetry was employed to determine absorbed dose to water at the point of interest for the fields under investigation. The corresponding chamber correction factors were calculated from alanine to ionization chamber measurements ratios. Results: Two different methods of determining the beam quality correction factor k{sub Q,Q{sub 0}} for the A1SL ionization chamber in this TomoTherapy unit, where reference conditions for conventional beam quality determination cannot be met, result in consistent values. The observed values of overall correction factors obtained for intermediate and clinical fields are consistently around 0.98 with a typical expanded relative uncertainty of 2% (k = 2), which when considered make such correction factors compatible with unity. However, all of them are systematically lower than unity, which is shown to be significant when a hypothesis test assuming a t-student distribution is performed (p=1.8x10{sup -2}). Correction factors k{sub Q{sub c{sub l{sub i{sub n,Q{sub p{sub c{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub p}{sub c}{sub s}{sub r}}}}}}}}}} and k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}, which are needed for the computation of field factors for relative dosimetry of clinical beams, have been found to be very close to unity for two clinical treatments. Conclusions: The results indicate that the helical field deliveries in this study (including two clinical fields) do not introduce changes on the ion chamber correction factors for dosimetry. For those two specific clinical cases, ratios of chamber readings accurately represent field output factors. The values observed here for intermediate calibration fields are in agreement with previously published data based on alanine dosimetry but differ from values recently reported obtained via radiochromic dosimetry.

  3. Calculation of perturbation correction factors for some reference dosimeters in high-energy photon beams with the Monte Carlo code PENELOPE.

    PubMed

    Mazurier, J; Gouriou, J; Chauvenet, B; Barthe, J

    2001-06-01

    The BNM-LNHB (formerly BNM-LPRI, the French national standard laboratory for ionizing radiation) is equipped with a SATURNE 43 linear accelerator (GE Medical Systems) dedicated to establishing national references of absorbed dose to water for high-energy photon and electron beams. These standards are derived from a dose measurement with a graphite calorimeter and a transfer procedure to water using Fricke dosimeters. This method has already been used to obtain the reference of absorbed dose to water for cobalt-60 beams. The correction factors rising from the perturbations generated by the dosimeters were determined by Monte Carlo calculations. To meet these applications, the Monte Carlo code PENELOPE was used and user codes were specially developed. The first step consisted of simulating the electron and photon showers produced by primary electrons within the accelerator head to determine the characteristics of the resulting photon beams and absorbed dose distributions in a water phantom. These preliminary computations were described in a previous paper. The second step, described in this paper, deals with the calculation of the perturbation correction factors of the graphite calorimeter and of Fricke dosimeters. To point out possible systematic biases, these correction factors were calculated with another Monte Carlo code, EGS4, widely used for years in the field of dose metrology applications. Comparison of the results showed no significant bias. When they were possible, experimental verifications confirmed the calculated values. PMID:11419629

  4. Functional adaptations of the bacterial chaperone trigger factor to extreme environmental temperatures.

    PubMed

    Godin-Roulling, Amandine; Schmidpeter, Philipp A M; Schmid, Franz X; Feller, Georges

    2015-07-01

    Trigger factor (TF) is the first molecular chaperone interacting cotranslationally with virtually all nascent polypeptides synthesized by the ribosome in bacteria. Thermal adaptation of chaperone function was investigated in TFs from the Antarctic psychrophile Pseudoalteromonas haloplanktis, the mesophile Escherichia coli and the hyperthermophile Thermotoga maritima. This series covers nearly all temperatures encountered by bacteria. Although structurally homologous, these TFs display strikingly distinct properties that are related to the bacterial environmental temperature. The hyperthermophilic TF strongly binds model proteins during their folding and protects them from heat-induced misfolding and aggregation. It decreases the folding rate and counteracts the fast folding rate imposed by high temperature. It also functions as a carrier of partially folded proteins for delivery to downstream chaperones ensuring final maturation. By contrast, the psychrophilic TF displays weak chaperone activities, showing that these functions are less important in cold conditions because protein folding, misfolding and aggregation are slowed down at low temperature. It efficiently catalyses prolyl isomerization at low temperature as a result of its increased cellular concentration rather than from an improved activity. Some chaperone properties of the mesophilic TF possibly reflect its function as a cold shock protein in E.?coli. PMID:25389111

  5. Factors Influencing the Completion of the GED in a Federal Correctional Setting a Multiple Regression Correlation-Predictive Study

    ERIC Educational Resources Information Center

    Akers, Kimberly

    2013-01-01

    Correctional education's primary goal is to reduce recidivism and increase employment among ex-offenders. The Bureau of Prison's practical goal in its mandatory GED program is to maximize the number of inmates obtaining the GED in a given time period. The purpose of this research is to model the number of instructional hours an inmate…

  6. Accuracy of Spencer-Attix cavity theory and calculations of fluence correction factors for the air kerma formalism

    SciTech Connect

    La Russa, D. J.; Rogers, D. W. O. [Ottawa Carleton Institute of Physics, Carleton University Campus, Ottawa, Ontario K1S 5B6 (Canada)

    2009-09-15

    EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for {sup 60}Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (K{sub fl}) by the presence of the cavity. The need for K{sub fl} corrections arises from the fact that the standard prescription for choosing the low-energy threshold {Delta} in the SA restricted stopping-power ratio consistently underestimates the values of {Delta} needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing {Delta}, but it is not clear how {Delta} can be calculated from first principles. Values of {Delta} required to avoid K{sub fl} corrections were found to be consistently higher than {Delta} values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of K{sub fl} have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%.

  7. Accuracy of Spencer-Attix cavity theory and calculations of fluence correction factors for the air kerma formalism.

    PubMed

    La Russa, D J; Rogers, D W O

    2009-09-01

    EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for 60Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (K(fl)) by the presence of the cavity. The need for K(fl) corrections arises from the fact that the standard prescription for choosing the low-energy threshold delta in the SA restricted stopping-power ratio consistently underestimates the values of delta needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing delta, but it is not clear how delta can be calculated from first principles. Values of delta required to avoid K(fl) corrections were found to be consistently higher than delta values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of K(fl) have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%. PMID:19810491

  8. Location specific forecasting of maximum and minimum temperatures over India by using the statistical bias corrected output of global forecasting system

    NASA Astrophysics Data System (ADS)

    Durai, V. R.; Bhardwaj, Rashmi

    2014-06-01

    The output from Global Forecasting System (GFS) T574L64 operational at India Meteorological Department (IMD), New Delhi is used for obtaining location specific quantitative forecast of maximum and minimum temperatures over India in the medium range time scale. In this study, a statistical bias correction algorithm has been introduced to reduce the systematic bias in the 24-120 hour GFS model location specific forecast of maximum and minimum temperatures for 98 selected synoptic stations, representing different geographical regions of India. The statistical bias correction algorithm used for minimizing the bias of the next forecast is Decaying Weighted Mean (DWM), as it is suitable for small samples. The main objective of this study is to evaluate the skill of Direct Model Output (DMO) and Bias Corrected (BC) GFS for location specific forecast of maximum and minimum temperatures over India. The performance skill of 24-120 hour DMO and BC forecast of GFS model is evaluated for all the 98 synoptic stations during summer (May-August 2012) and winter (November 2012-February 2013) seasons using different statistical evaluation skill measures. The magnitude of Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) for BC GFS forecast is lower than DMO during both summer and winter seasons. The BC GFS forecasts have higher skill score as compared to GFS DMO over most of the stations in all day-1 to day-5 forecasts during both summer and winter seasons. It is concluded from the study that the skill of GFS statistical BC forecast improves over the GFS DMO remarkably and hence can be used as an operational weather forecasting system for location specific forecast over India.

  9. Polysaccharide peptide induces a tumor necrosis factor-?-dependent drop of body temperature in rats.

    PubMed

    Jedrzejewski, Tomasz; Piotrowski, Jakub; Wrotek, Sylwia; Kozak, Wieslaw

    2014-08-01

    Polysaccharide peptide (PSP) extracted from the Coriolus versicolor mushroom is frequently suggested as an adjunct to the chemo- or radiotherapy in cancer patients. It improves quality of the patients' life by decreasing pain, fatigue, loss of appetite, nausea, and vomiting. However, the effect of PSP on body temperature has not thus far been studied, although it is well known that treatment with other polysaccharide adjuvants, such as lipopolysaccharides, may induce fever. The aim of the present study, therefore, was to investigate the influence of PSP on temperature regulation in rats. We report that intraperitoneal injection of PSP provoked a dose-dependent decrease of temperature in male Wistar rats equipped with biotelemetry devices to monitor deep body temperature (Tb). The response was rapid (i.e., with latency of 15-20min), transient (lasting up to 5h post-injection), and accompanied by a significant elevation of the blood tumor necrosis factor-? (TNF-?) level. Pretreatment of the rats with anti-TNF-? antibody prevented the PSP-induced drop in Tb. Based on these data, we conclude that rats may develop an anapyrexia-like response to the injection of peptidopolysaccharide rather than fever, and the response was TNF-?-dependent. PMID:25086966

  10. Extrahepatic sources of factor VIII potentially contribute to the coagulation cascade correcting the bleeding phenotype of mice with hemophilia A

    PubMed Central

    Zanolini, Diego; Merlin, Simone; Feola, Maria; Ranaldo, Gabriella; Amoruso, Angela; Gaidano, Gianluca; Zaffaroni, Mauro; Ferrero, Alessandro; Brunelleschi, Sandra; Valente, Guido; Gupta, Sanjeev; Prat, Maria; Follenzi, Antonia

    2015-01-01

    A large fraction of factor VIII in blood originates from liver sinusoidal endothelial cells although extrahepatic sources also contribute to plasma factor VIII levels. Identification of cell-types other than endothelial cells with the capacity to synthesize and release factor VIII will be helpful for therapeutic approaches in hemophilia A. Recent cell therapy and bone marrow transplantation studies indicated that Küpffer cells, monocytes and mesenchymal stromal cells could synthesize factor VIII in sufficient amount to ameliorate the bleeding phenotype in hemophilic mice. To further establish the role of blood cells in expressing factor VIII, we studied various types of mouse and human hematopoietic cells. We identified factor VIII in cells isolated from peripheral and cord blood, as well as bone marrow. Co-staining for cell type-specific markers verified that factor VIII was expressed in monocytes, macrophages and megakaryocytes. We additionally verified that factor VIII was expressed in liver sinusoidal endothelial cells and endothelial cells elsewhere, e.g., in the spleen, lungs and kidneys. Factor VIII was well expressed in sinusoidal endothelial cells and Küpffer cells isolated from human liver, whereas by comparison isolated human hepatocytes expressed factor VIII at very low levels. After transplantation of CD34+ human cord blood cells into NOD/SCID?Null-hemophilia A mice, fluorescence activated cell sorting of peripheral blood showed >40% donor cells engrafted in the majority of mice. In these animals, plasma factor VIII activity 12 weeks after cell transplantation was up to 5% and nine of 12 mice survived after a tail clip-assay. In conclusion, hematopoietic cells, in addition to endothelial cells, express and secrete factor VIII: this information should offer further opportunities for understanding mechanisms of factor VIII synthesis and replenishment. PMID:25911555

  11. Extrahepatic sources of factor VIII potentially contribute to the coagulation cascade correcting the bleeding phenotype of mice with hemophilia A.

    PubMed

    Zanolini, Diego; Merlin, Simone; Feola, Maria; Ranaldo, Gabriella; Amoruso, Angela; Gaidano, Gianluca; Zaffaroni, Mauro; Ferrero, Alessandro; Brunelleschi, Sandra; Valente, Guido; Gupta, Sanjeev; Prat, Maria; Follenzi, Antonia

    2015-07-01

    A large fraction of factor VIII in blood originates from liver sinusoidal endothelial cells although extrahepatic sources also contribute to plasma factor VIII levels. Identification of cell-types other than endothelial cells with the capacity to synthesize and release factor VIII will be helpful for therapeutic approaches in hemophilia A. Recent cell therapy and bone marrow transplantation studies indicated that Küpffer cells, monocytes and mesenchymal stromal cells could synthesize factor VIII in sufficient amount to ameliorate the bleeding phenotype in hemophilic mice. To further establish the role of blood cells in expressing factor VIII, we studied various types of mouse and human hematopoietic cells. We identified factor VIII in cells isolated from peripheral and cord blood, as well as bone marrow. Co-staining for cell type-specific markers verified that factor VIII was expressed in monocytes, macrophages and megakaryocytes. We additionally verified that factor VIII was expressed in liver sinusoidal endothelial cells and endothelial cells elsewhere, e.g., in the spleen, lungs and kidneys. Factor VIII was well expressed in sinusoidal endothelial cells and Küpffer cells isolated from human liver, whereas by comparison isolated human hepatocytes expressed factor VIII at very low levels. After transplantation of CD34(+) human cord blood cells into NOD/SCID?Null-hemophilia A mice, fluorescence activated cell sorting of peripheral blood showed >40% donor cells engrafted in the majority of mice. In these animals, plasma factor VIII activity 12 weeks after cell transplantation was up to 5% and nine of 12 mice survived after a tail clip-assay. In conclusion, hematopoietic cells, in addition to endothelial cells, express and secrete factor VIII: this information should offer further opportunities for understanding mechanisms of factor VIII synthesis and replenishment. PMID:25911555

  12. A physically based algorithm for non-blackbody correction of the cloud top temperature for the convective clouds

    NASA Astrophysics Data System (ADS)

    Wang, C.; Luo, Z. J.; Chen, X.; Zeng, X.; Tao, W.; Huang, X.

    2012-12-01

    Cloud top temperature is a key parameter to retrieval in the remote sensing of convective clouds. Passive remote sensing cannot directly measure the temperature at the cloud tops. Here we explore a synergistic way of estimating cloud top temperature by making use of the simultaneous passive and active remote sensing of clouds (in this case, CloudSat and MODIS). Weighting function of the MODIS 11?m band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat retrievals and temperature and humidity profiles based on ECMWF ERA-interim reanalysis into a radiation transfer model. Among 19,699 tropical deep convective clouds observed by the CloudSat in 2008, the averaged effective emission level (EEL, where the weighting function attains its maximum) is at optical depth 0.91 with a standard deviation of 0.33. Furthermore, the vertical gradient of CloudSat radar reflectivity, an indicator of the fuzziness of convective cloud top, is linearly proportional to, d_{CTH-EEL}, the distance between the EEL of 11?m channel and cloud top height (CTH) determined by the CloudSat when d_{CTH-EEL}<0.6km. Beyond 0.6km, the distance has little sensitivity to the vertical gradient of CloudSat radar reflectivity. Based on these findings, we derive a formula between the fuzziness in the cloud top region, which is measurable by CloudSat, and the MODIS 11?m brightness temperature assuming that the difference between effective emission temperature and the 11?m brightness temperature is proportional to the cloud top fuzziness. This formula is verified using the simulated deep convective cloud profiles by the Goddard Cumulus Ensemble model. We further discuss the application of this formula in estimating cloud top buoyancy as well as the error characteristics of the radiative calculation within such deep-convective clouds.

  13. Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam.

    PubMed

    Pham, C H; Vu, C C; Sommer, S G; Bruun, S

    2014-07-01

    This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

  14. Influence of the interface in quantum corrections on the low-temperature resistance of La2/3Sr1/3MnO3 trilayer masking thin films.

    PubMed

    Jin, Yuan; Cui, Xiao-Peng; Han, Wei-Hua; Cao, Shi-Xun; Gao, Yu-Ze; Zhang, Jin-Cang

    2015-05-01

    We report the low-temperature resistance upturn in sandwiched structures of La2/3Sr1/3MnO3/ZrO2/La2/3Sr1/3MnO3 and La2/3Sr1/3MnO3/LaMnO3/La2/3Sr1/3MnO3, while it disappeared when the interlayer was replaced by YBa2Cu3O7. The experimental data have been analyzed qualitatively and quantitatively. The results show that the low temperature resistance upturn is mainly due to the quantum correction effects driven by the weak localization and the electron-electron interaction in such a strongly correlated system, and the contribution of each factor varies with grain boundaries. Moreover, the resistance upturns are suppressed by a local magnetic field. These findings will help to further understand the physical mechanism of low-temperature resistance upturn in colossal magnetoresistance manganites. Furthermore, it is also helpful to reveal the intrinsic transport mechanism at the interfaces of semiconductor/ferromagnetism and antiferromagnetism/ferromagnetism. PMID:25907104

  15. Do current models correctly predict the L-band terrestrial brightness temperature when crops begin to senesce?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microwave terrestrial brightness temperature is sensitive to soil moisture, the water content of the first few centimeters of Earth's surface. The European Space Agency will soon launch the Soil Moisture and Ocean Salinity (SMOS) mission, the world's first soil moisture satellite that will measu...

  16. Atmospheric correction of infrared measurements of sea surface temperature using channels at 3.7, 11 and 12 Mum

    Microsoft Academic Search

    P. Y. Deschamps; T. Phulpin

    1980-01-01

    Atmospheric effects upon the radiometric determination of surface temperature were studied for channels centered at 3.7, 11 and 12 Mum. The error due to the atmosphere is least for the channel centered at 3.7 Mum, which is a real advantage. The use of a linear combination of two or all three of these channels allows one to eliminate most of

  17. Factors controlling cloud microphysics, precipitation rate, and brightness temperature of tropical convective and stratiform clouds

    NASA Astrophysics Data System (ADS)

    Hashino, T.; Casella, D.; Mugnai, A.; Sano, P.; Smith, E. A.; Tripoli, G.

    2008-12-01

    This paper discusses factors controlling cloud microphysics, precipitation rate and brightness temperature of tropical convective and stratiform clouds. Tropical convective and stratiform clouds are important in radiative forcing of climates and distribution of precipitation over the ocean. The possible effects of climate change on these clouds are still not well understood. Recent studies show that the higher CCN concentration in a convective cloud can lead to more vigorous updrafts and a higher evaporation/precipitation ratio. The stronger updraft often means stronger downdraft and gust fronts, which can trigger convection nearby. This implies that increases in CCN concentration can result in an increase in area coverage and persistence of tropical cirrus and stratiform clouds. The increased cloudiness would then be expected to lower sensible and latent heat flux from the ocean by lowering sea surface temperature, affecting the future development of convective clouds. The sea surface temperature may also change in a local area due to change of ocean circulation in climate change scenarios. Satellite remote sensing is a powerful tool to study tropical and global precipitation distribution. Many physically-based passive-microwave (MW) satellite precipitation algorithms make use of cloud radiation databases (CRDs), which typically consist of microphysical profiles from cloud resolving model (CRMs) and simulated MW brightness temperature (Tb). Thus, it is important to validate Tb simulated by a CRM against the observed Tb. Also, it is important to study how any changes in the tropical clouds due to aerosols and sea surface temperature translate into the precipitation and brightness temperature. The case study chosen is KWAJEX campaign that took place from 23 July to 14 September 1999. Authors have developed microphysical physical framework (Advanced Microphysics Prediction System) to predict ice particle properties explicitly in a CRM (University of Wisconsin-Nonhydrostatic Modeling System) (Hashino and Tripoli, 2007). AMPS also predicts aerosol and liquid spectrum by explicitly resolving sizes. For this study UW-NMS AMPS is set up for 2D simulation with periodic conditions over KWAJEX campaign area with synoptic forcing. The microphysical prediction of AMPS is then validated against in-situ microphysical observations and TRMM TMI measurements. Finally, sensitivity tests to study effects of aerosol properties and sea surface temperature on precipitation rate and Tb are discussed.

  18. Monte Carlo modelling of diode detectors for small field MV photon dosimetry: detector model simplification and the sensitivity of correction factors to source parameterization

    NASA Astrophysics Data System (ADS)

    Cranmer-Sargison, G.; Weston, S.; Evans, J. A.; Sidhu, N. P.; Thwaites, D. I.

    2012-08-01

    The goal of this work was to examine the use of simplified diode detector models within a recently proposed Monte Carlo (MC) based small field dosimetry formalism and to investigate the influence of electron source parameterization has on MC calculated correction factors. BEAMnrc was used to model Varian 6?MV jaw-collimated square field sizes down to 0.5 cm. The IBA stereotactic field diode (SFD), PTW T60016 (shielded) and PTW T60017 (un-shielded) diodes were modelled in DOSRZnrc and isocentric output ratios (OR_{\\det _{MC} }^{f_{clin} }) calculated at depths of d = 1.5, 5.0 and 10.0 cm. Simplified detector models were then tested by evaluating the percent difference in OR_{det_{MC} }^{f_{clin} }between the simplified and complete detector models. The influence of active volume dimension on simulated output ratio and response factor was also investigated. The sensitivity of each MC calculated replacement correction factor (\\mathop k\

  19. [Variation of apple tree canopy-air temperature difference and its relations to environment factors].

    PubMed

    Meng, Ping; Zhang, Jin-Song; Gao, Jun; Wang, He-Song; Ren, Qing-Fu

    2007-09-01

    By using portable infrared thermometer, the canopy temperature (Tc) of apple tree in its main growth season was measured in 2002-2005. Combined with the synchronous micro-meteorological data on the canopy, such as net radiation (Rn), wind speed (V), air temperature (Ta) and relative humidity (RH), as well as the soil water content (SW) at 0-80 cm depth, the variation of apple tree canopy-air temperature differential (DeltaT) and its relationships to environmental factor were analyzed. The results showed that from bud stage to fruit-developing stage, there were several peaks in the diurnal curve of DeltaT, with the maximum at 12:00-13:00 in fine days, and the absolute value of DeltaT in fine days was higher than that in overcast days. Based on data of 2003 and 2004, the DeltaT at 14:00 was significantly correlated with the RH, V, Rn, SW in fine days, and the regression equation was DeltaT = 7.159 - 0.002Rn - 0.061V - 0.7RH - 46.0SW (P < 0.01, r = 0.825). The partial coefficient for Rn, RH, V and SW was 0.125, -0.078, -0.036, -0.874, respectively, and the stepwise regression equation was DeltaT = 5.317 - 43.1SW (P < 0.01), suggesting that SW was the most important environmental factor affecting DeltaT. After validated with the measured data in 2002 and 2005, it was found that the measured DeltaT was highly accorded with the simulated one (r = 0.9083, P < 0.01, n = 40), and thus, it was of possibility to use the data of DeltaT at 14:00 in fine days to predict the soil water content in apple orchard. PMID:18062308

  20. Somatosensory factors in taste perception: Effects of active tasting and solution temperature

    PubMed Central

    Green, Barry G.; Nachtigal, Danielle

    2012-01-01

    Touch and temperature are recognized as important factors in food perception, but much remains to be learned about how they contribute to the perception of flavor. The present paper describes human psychophysical studies that investigated two recently discovered effects of mechanical and thermal stimulation on taste: (1) enhancement of the savory taste of MSG by active tongue and mouth movements, and (2) modulation of the rate of adaptation to sucrose sweetness by temperature. The first study provides evidence that for MSG but not other taste stimuli, movement of the tongue against the palate enhances taste intensity both by increasing spatial summation between opposing gustatory surfaces and by a hypothesized interaction with touch/kinesthesis. The second study shows that the rate of adaptation to sucrose sweetness (but not quinine bitterness) on the tongue tip is strongly influenced by temperature. It is hypothesized that warming slows adaptation to sucrose by increasing the sensitivity of an early stage of taste transduction. Together these results demonstrate that models of flavor perception must include somatosensory stimuli both as components of flavor perception and as modulators of taste. PMID:22609629

  1. Factors associated with survival in the herd for dairy cows following surgery to correct left displaced abomasum.

    PubMed

    Reynen, Jennifer L; Kelton, David F; LeBlanc, Stephen J; Newby, Nathalie C; Duffield, Todd F

    2015-06-01

    Left displaced abomasum (LDA) is a common problem in dairy cows. There have been numerous studies focused on predicting prognosis for right displaced abomasal corrective surgery, but a paucity of studies exist focused on more common LDA surgeries. Our objective was to determine if survival to 60d or 1yr after surgery could be predicted from the physical exam findings, periparturient disease status, and a biochemical profile from a blood sample obtained at the time of LDA diagnosis. Blood ?-hydroxybutyrate (BHBA) concentrations were measured immediately using a hand-held meter. Data obtained from CanWest DHI (Guelph, ON, Canada) for all of the study subjects (n=179 cases, by 24 veterinarians from 4 clinics), including cull date, cull reason, and test-day milk production. Cows were classified based on whether or not they were culled within 60d or 1yr of surgery. Based on logistic regression, cows that had dystocia [odds ratio (OR)=13, 95% confidence interval (CI)=7-26] or were not ketotic (blood BHBA <1.2mmol/L; OR=3, 95% CI=1.03-9) at the time of corrective surgery were more likely to be culled within 60 d. Higher serum concentrations of BHBA (OR=0.95, 95% CI=0.92-0.98), nonesterified fatty acids (OR=0.81, 95% CI=0.75-0.88), and Mg (OR=0.49, 95% CI=0.35-0.68) all had a protective effect against culling within 1yr of LDA surgery. Based on survival analysis, longevity in the herd for 365d following corrective surgery was associated with higher BHBA and Mg at the time of LDA diagnosis before surgery, as well as milk production following surgery. PMID:25892696

  2. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    SciTech Connect

    Dimakis, Nicholas [University of Texas-Pan American, Edinburg, TX 78539 (United States); Bunker, Grant [Illinois Institute of Technology, Chicago IL 60616 (United States)

    2007-02-02

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained.

  3. Conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation, 1945--1947. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Mart, E.I.; Denham, D.H.; Thiede, M.E.

    1993-12-01

    This report is a result of the Hanford Environmental Dose Reconstruction (HEDR) Project whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the U.S. Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is conducted by Battelle, Pacific Northwest Laboratories (BNW). One of the radionuclides emitted that would affect the radiation dose was iodine-131. This report describes in detail the reconstructed conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation which was collected from the beginning of October 1945 through the end of December 1947.

  4. WINDOW-WALL INTERFACE CORRECTION FACTORS: THERMAL MODELING OF INTEGRATED FENESTRATION AND OPAQUE ENVELOPE SYSTEMS FOR IMPROVED PREDICTION OF ENERGY USE

    SciTech Connect

    Bhandari, Mahabir S [ORNL] [ORNL; Ravi, Dr. Srinivasan [University of Florida, Gainesville] [University of Florida, Gainesville

    2012-01-01

    The boundary conditions for thermal modeling of fenestration systems assume an adiabatic condition between the fenestration system installed and the opaque envelope system. This theoretical adiabatic boundary condition may not be appropriate owing to heat transfer at the interfaces, particularly for aluminum- framed windows affixed to metal- framed walls. In such scenarios, the heat transfer at the interface may increase the discrepancy between real world thermal indices and laboratory measured or calculated indices based on NFRC Rating System.This paper discusses the development of window-wall Interface Correction Factors (ICF) to improve energy impacts of building envelope systems

  5. Political Correctness--Correct?

    ERIC Educational Resources Information Center

    Boase, Paul H.

    1993-01-01

    Examines the phenomenon of political correctness, its roots and objectives, and its successes and failures in coping with the conflicts and clashes of multicultural campuses. Argues that speech codes indicate failure in academia's primary mission to civilize and educate through talk, discussion, thought,166 and persuasion. (SR)

  6. D.A. Stone A.J. Weaver Factors contributing to diurnal temperature range trends in twentieth

    E-print Network

    model repre- senting the atmosphere, ocean, sea ice, and land surface systems. Consistent with pastD.A. Stone Æ A.J. Weaver Factors contributing to diurnal temperature range trends in twentieth temperature range (DTR) are examined in the late twentieth and the twenty-first centuries in a coupled climate

  7. Correction of the characteristics of strongly irradiated SiC-based nuclear radiation detectors by increasing the working temperature

    Microsoft Academic Search

    A. M. Ivanov; N. B. Strokan; A. A. Lebedev

    2009-01-01

    Owing to the wide bandgap of silicon carbide, p- n structures based on this semiconductor are characterized by low densities of the generation current. For this reason, it is possible to increase the working temperature of SiC-based p- n detectors of nuclear radiation so as to control the time of emission of nonequilibrium carriers from defect-related trapping centers. We have

  8. Correction of the characteristics of strongly irradiated SiC-based nuclear radiation detectors by increasing the working temperature

    Microsoft Academic Search

    A. M. Ivanov; N. B. Strokan; A. A. Lebedev

    2009-01-01

    Owing to the wide bandgap of silicon carbide, p-n structures based on this semiconductor are characterized by low densities of the generation current. For this reason, it\\u000a is possible to increase the working temperature of SiC-based p-n detectors of nuclear radiation so as to control the time of emission of nonequilibrium carriers from defect-related trapping\\u000a centers. We have studied strongly

  9. A practical methodology to measure unbiased gas chromatographic retention factor vs. temperature relationships.

    PubMed

    Peng, Baijie; Kuo, Mei-Yi; Yang, Panhia; Hewitt, Joshua T; Boswell, Paul G

    2014-12-29

    Compound identification continues to be a major challenge. Gas chromatography-mass spectrometry (GC-MS) is a primary tool used for this purpose, but the GC retention information it provides is underutilized because existing retention databases are experimentally restrictive and unreliable. A methodology called "retention projection" has the potential to overcome these limitations, but it requires the retention factor (k) vs. T relationship of a compound to calculate its retention time. Direct methods of measuring k vs. T relationships from a series of isothermal runs are tedious and time-consuming. Instead, a series of temperature programs can be used to quickly measure the k vs. T relationships, but they are generally not as accurate when measured this way because they are strongly biased by non-ideal behavior of the GC system in each of the runs. In this work, we overcome that problem by using the retention times of 25 n-alkanes to back-calculate the effective temperature profile and hold-up time vs. T profiles produced in each of the six temperature programs. When the profiles were measured this way and taken into account, the k vs. T relationships measured from each of two different GC-MS instruments were nearly as accurate as the ones measured isothermally, showing less than two-fold more error. Furthermore, temperature-programmed retention times calculated in five other laboratories from the new k vs. T relationships had the same distribution of error as when they were calculated from k vs. T relationships measured isothermally. Free software was developed to make the methodology easy to use. The new methodology potentially provides a relatively fast and easy way to measure unbiased k vs. T relationships. PMID:25496658

  10. Impact of aerosol on sea surface temperature over the subtropical Atlantic Ocean: A potential trigger factor of the NAO phase

    E-print Network

    Yu, Fangqun

    Impact of aerosol on sea surface temperature over the subtropical Atlantic Ocean: A potential trigger factor of the NAO phase conversion? Gan Luo,1,2 Fangqun Yu,1 and Zifa Wang2 Received 18 September variations over SAO appear to be a trigger factor of NAO phase conversion. A new conceptual model, which

  11. Study of effective carrier lifetime and ideality factor of BPW 21 and BPW 34B photodiodes from above room temperature to liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Dalapati, P.; Manik, N. B.; Basu, A. N.

    2015-01-01

    In the present work we have studied the temperature dependence of two most important characteristics of the photodiodes (BPW 21and BPW 34B), namely, the ideality factor and the carrier lifetime; both of which are found to change significantly at low temperature. The effective carrier lifetime measured by the Open Circuit Voltage Decay method (OCVD) shows a gradual increase in value from 350 K to about 250 K then sharply decreases by about thirty percent of its highest value at liquid nitrogen temperature, the trend being similar for both the devices. The dark forward current-voltage characteristics over the same temperature range yield the value of ideality factor which increases nearly by a factor of three for both the photodiodes at the liquid nitrogen temperature. The nature of variation of both the parameters has been qualitatively accounted for in terms of the recent tunneling models. The data generated for the first time for the devices and their broad theoretical understanding will help to improve design and application of the photodiodes, particularly at low temperature.

  12. Correcting human heart 31P NMR spectra for partial saturation. Evidence that saturation factors for PCr/ATP are homogeneous in normal and disease states

    NASA Astrophysics Data System (ADS)

    Bottomley, Paul A.; Hardy, Christopher J.; Weiss, Robert G.

    Heart PCr/ATP ratios measured from spatially localized 31P NMR spectra can be corrected for partial saturation effects using saturation factors derived from unlocalized chest surface-coil spectra acquired at the heart rate and approximate Ernst angle for phosphor creatine (PCr) and again under fully relaxed conditions during each 31P exam. To validate this approach in studies of normal and disease states where the possibility of heterogeneity in metabolite T1 values between both chest muscle and heart and normal and disease states exists, the properties of saturation factors for metabolite ratios were investigated theoretically under conditions applicable in typical cardiac spectroscopy exams and empirically using data from 82 cardiac 31P exams in six study groups comprising normal controls ( n = 19) and patients with dilated ( n = 20) and hypertrophic ( n = 5) cardiomyopathy, coronary artery disease ( n = 16), heart transplants ( n = 19), and valvular heart disease ( n = 3). When TR ? T1,(PCr), with T1(PCr) ? T1(ATP), the saturation factor for PCr/ATP lies in the range 1.5 ± 0.5, regardless of the T1 values. The precise value depends on the ratio of metabolite T1 values rather than their absolute values and is insensitive to modest changes in TR. Published data suggest that the metabolite T1 ratio is the same in heart and muscle. Our empirical data reveal that the saturation factors do not vary significantly with disease state, nor with the relative fractions of muscle and heart contributing to the chest surface-coil spectra. Also, the corrected myocardial PCr/ATP ratios in each normal or disease state bear no correlation with the corresponding saturation factors nor the fraction of muscle in the unlocalized chest spectra. However, application of the saturation correction (mean value, 1.36 ± 0.03 SE) significantly reduced scatter in myocardial PCr/ATP data by 14 ± 11% (SD) ( p ? 0.05). The findings suggest that the relative T1 values of PCr and ATP are substantially the same in chest and heart muscle and are unchanged in these disease states. The mean value for T1 (PCr)/ T1(ATP) is 2.16 ± 0.29 SE.

  13. Low temperature resistivity, thermoelectricity, and power factor of Nb doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Ja?imovi?, J.; Gaál, R.; Magrez, A.; Piatek, J.; Forró, L.; Nakao, S.; Hirose, Y.; Hasegawa, T.

    2013-01-01

    The resistivity of a very high quality anatase TiO2 doped with 6% of Nb was measured from 300 K down to 40 mK. No sign of superconductivity was detected. Instead, a minute quantity of cation vacancies resulted in a Kondo scattering. Measurements of thermo-electric power and resistivity were extended up to 600 K. The calculated power factor has a peak value of 14 ?W/(K2cm) at 350 K, which is comparable to that of Bi2Te3 [Venkatasubramanian et al., Nature 413, 597 (2001)], the archetype thermolectrics. Taking the literature value for the thermal conductivity of Nb doped TiO2 thin films, the calculated figure of merit (ZT) is in the range of 0.1 above 300 K. This value is encouraging for further engineering of the material in order to reach ZT of 1 suitable for high temperature thermoelectrics.

  14. Two-Dimensional Thermal Boundary Layer Corrections for Convective Heat Flux Gauges

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Haddad, George

    2007-01-01

    This work presents a CFD (Computational Fluid Dynamics) study of two-dimensional thermal boundary layer correction factors for convective heat flux gauges mounted in flat plate subjected to a surface temperature discontinuity with variable properties taken into account. A two-equation k - omega turbulence model is considered. Results are obtained for a wide range of Mach numbers (1 to 5), gauge radius ratio, and wall temperature discontinuity. Comparisons are made for correction factors with constant properties and variable properties. It is shown that the variable-property effects on the heat flux correction factors become significant

  15. Temperature-averaged and total free-free Gaunt factors for $\\kappa$ and Maxwellian distributions of electrons

    E-print Network

    de Avillez, Miguel A

    2015-01-01

    Aims. Optically thin plasmas may deviate from thermal equilibrium and thus, electrons (and ions) are no longer described by the Maxwellian distribution. Instead they can be described by $\\kappa$-distributions. The free-free spectrum and radiative losses depend on the temperature-averaged (over the electrons distribution) and total Gaunt factors, respectively. Thus, there is a need to calculate and make available these factors to be used by any software that deals with plasma emission. Methods. We recalculated the free-free Gaunt factor for a wide range of energies and frequencies using hypergeometric functions of complex arguments and the Clenshaw recurrence formula technique combined with approximations whenever the difference between the initial and final electron energies is smaller than $10^{-10}$ in units of $z^2Ry$. We used double and quadruple precisions. The temperature- averaged and total Gaunt factors calculations make use of the Gauss-Laguerre integration with 128 nodes. Results. The temperature-av...

  16. Unity input displacement factor correction principle for direct AC to AC matrix converters based on modulation strategy

    Microsoft Academic Search

    M. Milanovic; Bojan Dobaj

    2000-01-01

    Modulation strategies for a matrix structured direct AC to AC converter are developed. In principle, for a given set of input three-phase voltages, any desired set of output voltages can be synthesized by suitable toggling matrix switches. Mathematical proof that the direct AC to AC matrix converter can operate with unity displacement factor is provided by analyses based on the

  17. Adaptation of Extremophilic Proteins with Temperature and Pressure: Evidence from Initiation Factor 6.

    PubMed

    Calligari, Paolo A; Calandrini, Vania; Ollivier, Jacques; Artero, Jean-Baptiste; Härtlein, Michael; Johnson, Mark; Kneller, Gerald R

    2015-06-25

    In this work, we study dynamical properties of an extremophilic protein, Initiation Factor 6 (IF6), produced by the archeabacterium Methanocaldococcus jannascii, which thrives close to deep-sea hydrothermal vents where temperatures reach 80 °C and the pressure is up to 750 bar. Molecular dynamics simulations (MD) and quasi-elastic neutron scattering (QENS) measurements give new insights into the dynamical properties of this protein with respect to its eukaryotic and mesophilic homologue. Results obtained by MD are supported by QENS data and are interpreted within the framework of a fractional Brownian dynamics model for the characterization of protein relaxation dynamics. IF6 from M. jannaschii at high temperature and pressure shares similar flexibility with its eukaryotic homologue from S. cerevisieae under ambient conditions. This work shows for the first time, to our knowledge, that the very common pattern of corresponding states for thermophilic protein adaptation can be extended to thermo-barophilic proteins. A detailed analysis of dynamic properties and of local structural fluctuations reveals a complex pattern for "corresponding" structural flexibilities. In particular, in the case of IF6, the latter seems to be strongly related to the entropic contribution given by an additional, C-terminal, 20 amino-acid tail which is evolutionary conserved in all mesophilic IF6s. PMID:25996652

  18. Long-Term Expression of Human Coagulation Factor VIII and Correction of Hemophilia A after in vivo Retroviral Gene Transfer in Factor VIII-Deficient Mice

    Microsoft Academic Search

    Thierry Vandendriessche; Veerle Vanslembrouck; Inge Goovaerts; Hans Zwinnen; Marie-Line Vanderhaeghen; Desire Collen; Marinee K. L. Chuah

    1999-01-01

    Hemophilia A is caused by a deficiency in coagulation factor VIII (FVIII) and predisposes to spontaneous bleeding that can be life-threatening or lead to chronic disabilities. It is well suited for gene therapy because a moderate increase in plasma FVIII concentration has therapeutic effects. Improved retroviral vectors expressing high levels of human FVIII were pseudotyped with the vesicular stomatitis virus

  19. Finite-temperature corrections to the time-domain equations of motion for perpendicular propagation in nonuniform magnetized plasmas

    SciTech Connect

    Tierens, W.; De Zutter, D. [Department of Information Technology, Ghent University, Sint-Pietersnieuwstraat 41, Ghent (Belgium)

    2012-11-15

    In this paper we extend the new techniques of W. Tierens and D. D. Zutter, J. Comput. Phys. 231, 5144 (2012) to include finite Larmor radius effects up to second order in the Larmor radius. We limit ourselves to the case of propagation perpendicular to the background magnetic field B(vector sign){sub 0}. We show that our time-domain technique is able to produce the lowest-order Bernstein wave (a wave believed to be useful for heating fusion devices [H. P. Laqua, Plasma Phys. Controlled Fusion 49, R1 (2007)]). The discrete equations retain many of the favourable properties described in W. Tierens and D. D. Zutter, J. Comput. Phys. 231, 5144 (2012), i.e., unconditional stability and a straightforward relation between the second-order accurate continuous dispersion relation and the dispersion relation of the discretized problem. The theory is illustrated by a place-independent and a place-dependent temperature numerical example.

  20. Quark-gluon plasma fireball evolution with one-loop correction in the mean-field potential

    NASA Astrophysics Data System (ADS)

    Singh, S. Somorendro; Ramanathan, R.

    2014-10-01

    The study of the free energy evolution of quark-gluon plasma (QGP) with one-loop correction factor in the mean-field potential is discussed. The energy evolution with the effect of the correction factor in potential shows a higher transition temperature in the range of T=180 to 250MeV in comparison to the transition temperature without the one-loop correction factor. The transition temperature is also affected by the dynamical flow parameter of quark and gluon used in the potential and it results in decreasing observable QGP droplets of stable radius 2.5-4.5 fm.

  1. Factors influencing bacterial dynamics along a transect from supraglacial runoff to proglacial lakes of a high Arctic glacier [corrected].

    PubMed

    Mindl, Birgit; Anesio, Alexandre M; Meirer, Katrin; Hodson, Andrew J; Laybourn-Parry, Johanna; Sommaruga, Ruben; Sattler, Birgit

    2007-02-01

    Bacterial production in glacial runoff and aquatic habitats along a c. 500 m transect from the ablation area of a Svalbard glacier (Midre Lovénbreen, 79 degrees N, 12 degrees E) down to a series of proglacial lakes in its forefield were assessed. In addition, a series of in situ experiments were conducted to test how different nutrient sources (glacial flour and dissolved organic matter derived from goose faeces) and temperature affect bacterial abundance and production in these ecosystems. Bacterial abundance and production increased significantly along this transect and reached a maximum in the proglacial lakes. Bacterial diversity profiles as assessed by denaturing gradient gel electrophoresis indicated that communities in glacial runoff were different from those in proglacial lakes. Heterotrophic bacterial production was mainly controlled by temperature and phosphorus limitation. Addition of both glacial flour and dissolved organic matter derived from goose faeces stimulated bacterial production in those lakes. The results suggest that glacial runoff sustains an active bacterial community which is further stimulated in proglacial lakes by higher temperatures and nutrient inputs from bird faeces. Thus, as in maritime temperate and Antarctic settings, bacterial communities developing in the recently deglaciated terrain of Svalbard receive important inputs of nutrients via faunal transfers from adjacent ecosystems. PMID:17313580

  2. Assessment of the nitrogen correction factor in evaluating metabolizable energy of corn and soybean meal in diets for broilers.

    PubMed

    Lopez, G; Leeson, S

    2008-02-01

    Three experiments were carried out to determine AME and AMEn of corn and soybean meal (SMB) in diets for growing broilers. In experiments 1 and 2, ingredient-specific basal diets or a combination of these basal diets with corn and SBM were prepared. For corn, the substitution was 25, 50, or 75% of the total diet, whereas SBM substitution was at 10, 20, or 30%. In experiment 1, birds were fed the experimental diets continuously from 0 to 33 d, and AME and AMEn were determined during 9 to 12 d and 30 to 33 d of age. In experiment 2, birds were fed the experimental diets only around the time of the collection period. The AMEn of corn was 95 to 97% of corresponding AME, whereas for SBM, AMEn was 93 to 88% of AME. Linear regression was used as an alternative method of calculating ingredient energy values resulting in a significant regression of diet AME and AMEn content on inclusion level, for each period of time and for each ingredient (corn and SBM). Based on varying inclusion levels of test ingredients in the diet, the extrapolated AME and AMEn of corn were estimated more precisely (R2 = 0.90 to 0.95) than those of SBM (R2 = 0.57 to 0.85), suggesting that the variability of AME and AMEn is better explained by a linear regression of AME or AMEn on percentage of inclusion. For corn, AME and AMEn were little affected by age, and the effect of N correction was consistent at around 3%. Determined energy values of SBM were more variable. Experiment 3 was conducted to assess the effect of formulating diets based on either AME or AMEn on broiler performance. A 2-sample t-test was implemented examining AME vs. AMEn formulation. The analyses for numerous production and carcass traits were nonsignificant except for the case of less abdominal fat in birds fed diets formulated to AME rather than AMEn (P < 0.01). These results showed that the use of the N correction imposed a penalty to corn of 3 to 5% and SBM of 7 to 12%. PMID:18212373

  3. Mac1, a fission yeast transmembrane protein localizing to the poles and septum, is required for correct cell separation at high temperatures.

    PubMed

    Grandin, Nathalie; Charbonneau, Michel

    2002-06-01

    Schizosaccharomyces pombe represents a genetic model system for studying cell polarity and division in eukaryotes. We report here the identification of Mac1, a novel fission yeast protein that localized predominantly to the cell tips and septum. Sequences corresponding to roughly the first 180 amino acids of Mac1, which exhibited weak homology to the transmembrane domains of the Aspergillus Pall protein [Mol. Microbiol. 30 (1998) 259], were found to specify localization to the cell periphery. The other 574 amino acids of Mac1 localized to the cytoplasm when expressed alone, thus suggesting that the N-terminal part of Mac1 functions as a plasma membrane anchor for the rest of the protein. In pom1 null mutant cells, which never switch from unipolar to bipolar growth but, instead, grow exclusively at the randomly chosen end [Genes Dev. 12 (1998) 1356], Mac1 was, nevertheless, found at both poles, thus suggesting that Mac1 does not specifically localize to the sites of growth. mac1 null mutant cells had no overt phenotype at 22-32 degrees C, but, nevertheless, displayed a marked decrease in viability at 34-36 degrees C, accompanied by severe separation defects. Overexpression of mac1 resulted in similar defects. Our data suggest that a correct dosage of Mac1 is needed for correct cell separation at elevated temperatures of growth. PMID:12206652

  4. Second-order power corrections in the heavy-quark effective theory. I. Formalism and meson form factors

    Microsoft Academic Search

    Adam F. Falk; Matthias Neubert

    1993-01-01

    In the heavy-quark effective theory, hadronic matrix elements of currents between two hadrons containing a heavy quark are expanded in inverse powers of the heavy-quark masses, with coefficients that are functions of the kinematic variable v.v'. For the ground-state pseudoscalar and vector mesons, this expansion is constructed at order 1\\/m2Q. A minimal set of universal form factors is defined in

  5. Correction of the Jicamarca electron-ion temperature ratio problem: Verifying the effect of electron Coulomb collisions on the incoherent scatter spectrum

    NASA Astrophysics Data System (ADS)

    Aponte, Néstor; Sulzer, Michael P.; González, Sixto A.

    2001-11-01

    Ever since the first attempts to fit Jicamarca autocorrelation function (ACF) measurements in the 1970s using a full nonlinear least squares analysis, an apparent electron-ion temperature ratio below unity has been deduced for a large portion of the F region data. The cause of this unexpected and geophysically unreasonable result has been a mystery until recently, when Sulzer and González [1999] (herein SG) explained how electron Coulomb collisions can distort, or narrow, the incoherent backscatter spectrum, and that for this narrowing to be observable two conditions must be met. First, the radar k vector must lie in a small range near perpendicular to the magnetic field, and second, the radar wavelength must be sufficiently long. Both of these conditions are true at Jicamarca. The accurate calculations from the SG theory are now available in a compact library, which we have incorporated into an incoherent scatter least squares fitting code. Using this code, we have reduced Jicamarca ACF data taken with the Faraday double-pulse mode, and find that the SG theory correctly interprets the ACF data from Jicamarca, thereby solving the longstanding Te/Ti ratio problem and thus allowing accurate electron and ion temperature measurements.

  6. Exposure levels due to WLAN devices in indoor environments corrected by a time-amplitude factor of distribution of the quasi-stochastic signals.

    PubMed

    Miclaus, Simona; Bechet, Paul; Stratakis, Dimitrios

    2014-12-01

    With the development of radiofrequency technology, radiating quasi-stochastic signals like the wireless local area networks (WLAN), a proper procedure of exposure level assessment is needed. No standardised procedure exists at the moment. While channel power measurement proved to overestimate the field strength, weighting techniques were proposed. The paper compares the exposure levels determined by three different procedures, two of them correcting the field level by weighting. Twenty-three experimental cases of WLAN traffic load are analysed in an indoor environment in controlled conditions. The results show the differences obtained when the duty cycle (DC) method is applied comparatively with the application of weighting based on an amplitude-time correction. Significant exposure level reductions of 52.6-79.2 % from the field determined by frequency domain method and of 36.5-72.8 % from the field determined by the DC weighting method were obtained by time-amplitude method. Specificities of weighting factors probability density functions were investigated and regression analysis was applied for a detailed characterisation of this procedure. PMID:24591729

  7. Evaluation of wall correction factor of INER's air-kerma primary standard chamber and dose variation by source displacement for HDR ¹?²Ir brachytherapy.

    PubMed

    Lee, J H; Wang, J N; Huang, T T; Su, S H; Chang, B J; Su, C H; Hsu, S M

    2013-01-01

    The aim of the present study was to estimate the wall effect of the self-made spherical graphite-walled cavity chamber with the Monte Carlo method for establishing the air-kerma primary standard of high-dose-rate (HDR) ¹?²Ir brachytherapy sources at the Institute of Nuclear Energy Research (INER, Taiwan). The Monte Carlo method established in this paper was also employed to respectively simulate wall correction factors of the ¹?²Ir air-kerma standard chambers used at the National Institute of Standards and Technology (NIST, USA) and the National Physical Laboratory (NPL, UK) for comparisons and verification. The chamber wall correction calculation results will be incorporated into INER's HDR ¹?²Ir primary standard in the future. For the brachytherapy treatment in the esophagus or in the bronchi, the position of the isotope may have displacement in the cavity. Thus the delivered dose would differ from the prescribed dose in the treatment plan. We also tried assessing dose distribution due to the position displacement of HDR ¹?²Ir brachytherapy source in a phantom with a central cavity by the Monte Carlo method. The calculated results could offer a clinical reference for the brachytherapy within the human organs with cavity. PMID:24222907

  8. Evaluation of Wall Correction Factor of INER's Air-Kerma Primary Standard Chamber and Dose Variation by Source Displacement for HDR 192Ir Brachytherapy

    PubMed Central

    Lee, J. H.; Wang, J. N.; Huang, T. T.; Su, S. H.; Chang, B. J.; Su, C. H.; Hsu, S. M.

    2013-01-01

    The aim of the present study was to estimate the wall effect of the self-made spherical graphite-walled cavity chamber with the Monte Carlo method for establishing the air-kerma primary standard of high-dose-rate (HDR) 192Ir brachytherapy sources at the Institute of Nuclear Energy Research (INER, Taiwan). The Monte Carlo method established in this paper was also employed to respectively simulate wall correction factors of the 192Ir air-kerma standard chambers used at the National Institute of Standards and Technology (NIST, USA) and the National Physical Laboratory (NPL, UK) for comparisons and verification. The chamber wall correction calculation results will be incorporated into INER's HDR 192Ir primary standard in the future. For the brachytherapy treatment in the esophagus or in the bronchi, the position of the isotope may have displacement in the cavity. Thus the delivered dose would differ from the prescribed dose in the treatment plan. We also tried assessing dose distribution due to the position displacement of HDR 192Ir brachytherapy source in a phantom with a central cavity by the Monte Carlo method. The calculated results could offer a clinical reference for the brachytherapy within the human organs with cavity. PMID:24222907

  9. Energy factors and temperature distribution in insulated built-up roofs. Technical note July 1977January 1980

    Microsoft Academic Search

    J. R. Keeton; R. L. Alumbaugh

    1981-01-01

    Surface temperatures of 4-ply built-up roofs insulated with (1) 1 inch of perlite (R = 2.8) and 2-1\\/2 inches of urethane (R = 19.2) and (2) 1 inch of urethane (R = 7.1) and 1-7\\/8 inches of glass fiber (R = 7.7) are presented. Energy factors are shown in terms of temperature-time areas defined as solar heat response, cooling (heating)

  10. Temperature dependence of the Westcott g-factor for neutron capture reactions in ENDF/B-VI

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The Westcott g-factors, which allow the user to determine reaction rates for nuclear reactions taking place at various temperatures, have been calculated using data from the Evaluated Neutron Nuclear Data library, ENDF-VI. The nuclides chosen have g-factors which are significantly different from unity and result in different reaction rates compared to nuclides whose neutron capture cross section varies as the reciprocal of the neutron`s velocity. Values are presented as a function of temperature up to 400{degrees}C.

  11. Spatial downscaling and correction of precipitation and temperature time series to high resolution hydrological response units in the Canadian Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Kienzle, Stefan

    2015-04-01

    Precipitation is the central driving force of most hydrological processes, and is also the most variable element of the hydrological cycle. As the precipitation to runoff ratio is non-linear, errors in precipitation estimations are amplified in streamflow simulations. Therefore, the accurate estimate of areal precipitation is essential for watershed models and relevant impacts studies. A procedure is presented to demonstrate the spatial distribution of daily precipitation and temperature estimates across the Rocky Mountains within the framework of the ACRU agro-hydrological modelling system (ACRU). ACRU (Schulze, 1995) is a physical-conceptual, semi-distributed hydrological modelling system designed to be responsive to changes in land use and climate. The model has been updated to include specific high-mountain and cold climate routines and is applied to simulate impacts of land cover and climate change on the hydrological behaviour of numerous Rocky Mountain watersheds in Alberta, Canada. Both air temperature and precipitation time series need to be downscaled to hydrological response units (HRUs), as they are the spatial modelling units for the model. The estimation of accurate daily air temperatures is critical for the separation of rain and snow. The precipitation estimation procedure integrates a spatially distributed daily precipitation database for the period 1950 to 2010 at a scale of 10 by 10 km with a 1971-2000 climate normal database available at 2 by 2 km (PRISM). Resulting daily precipitation time series are further downscaled to the spatial resolution of hydrological response units, defined by 100 m elevation bands, land cover, and solar radiation, which have an average size of about 15 km2. As snow measurements are known to have a potential under-catch of up to 40%, further adjustment of snowfall may need to be increased using a procedure by Richter (1995). Finally, precipitation input to HRUs with slopes steeper than 10% need to be further corrected, because the true, sloped area, has a larger area than the planimetric area derived from a GIS. The omission of correcting for sloped areas would result in incorrect calculations of interception volumes, soil moisture storages, groundwater recharge rates, actual evapotranspiration volumes, and runoff coefficients. Daily minimum and maximum air temperatures are estimated for each HRU by downscaling the 10km time series to the HRUs by (a) applying monthly mean lapse rates, estimated either from surrounding climate stations or from the PRISM climate normal dataset in combination with a digital elevation model, (b) adjusting further for aspect of the HRU based on monthly mean incoming solar radiation, and (c) adjusting for canopy cover using the monthly mean leaf area indices. Precipitation estimates can be verified using independent snow water equivalent measurements derived from snow pillow or snow course observations, while temperature estimates are verified against either independent temperature measurements from climate stations, or from fire observation towers.

  12. Monte Carlo computed machine-specific correction factors for reference dosimetry of TomoTherapy static beam for several ion chambers

    SciTech Connect

    Sterpin, E.; Mackie, T. R.; Vynckier, S. [Department of Molecular Imaging, Radiation and Oncology, Universite Catholique de Louvain, Avenue Hippocrate 54, 1200 Brussels (Belgium); Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Department of Molecular Imaging, Radiation and Oncology, Universite Catholique de Louvain, Avenue Hippocrate 54, 1200 Brussels (Belgium)

    2012-07-15

    Purpose: To determine k{sub Q{sub m{sub s{sub r,Q{sub o}{sup f{sub m}{sub s}{sub r},f{sub o}}}}}} correction factors for machine-specific reference (msr) conditions by Monte Carlo (MC) simulations for reference dosimetry of TomoTherapy static beams for ion chambers Exradin A1SL, A12; PTW 30006, 31010 Semiflex, 31014 PinPoint, 31018 microLion; NE 2571. Methods: For the calibration of TomoTherapy units, reference conditions specified in current codes of practice like IAEA/TRS-398 and AAPM/TG-51 cannot be realized. To cope with this issue, Alfonso et al. [Med. Phys. 35, 5179-5186 (2008)] described a new formalism introducing msr factors k{sub Q{sub m{sub s{sub r,Q{sub o}{sup f{sub m}{sub s}{sub r},f{sub o}}}}}} for reference dosimetry, applicable to static TomoTherapy beams. In this study, those factors were computed directly using MC simulations for Q{sub 0} corresponding to a simplified {sup 60}Co beam in TRS-398 reference conditions (at 10 cm depth). The msr conditions were a 10 Multiplication-Sign 5 cm{sup 2} TomoTherapy beam, source-surface distance of 85 cm and 10 cm depth. The chambers were modeled according to technical drawings using the egs++ package and the MC simulations were run with the egs{sub c}hamber user code. Phase-space files used as the source input were produced using PENELOPE after simulation of a simplified {sup 60}Co beam and the TomoTherapy treatment head modeled according to technical drawings. Correlated sampling, intermediate phase-space storage, and photon cross-section enhancement variance reduction techniques were used. The simulations were stopped when the combined standard uncertainty was below 0.2%. Results: Computed k{sub Q{sub m{sub s{sub r,Q{sub o}{sup f{sub m}{sub s}{sub r},f{sub o}}}}}} values were all close to one, in a range from 0.991 for the PinPoint chamber to 1.000 for the Exradin A12 with a statistical uncertainty below 0.2%. Considering a beam quality Q defined as the TPR{sub 20,10} for a 6 MV Elekta photon beam (0.661), the additional correction k{sub Q{sub m{sub s{sub r{sub ,Q}{sup f{sub m}{sub s}{sub r}{sub ,}f{sub r}{sub e}{sub f}}}}}} to k{sub Q,Q{sub o}} defined in Alfonso et al. [Med. Phys. 35, 5179-5186 (2008)] formalism was in a range from 0.997 to 1.004.Conclusion: The MC computed factors in this study are in agreement with measured factors for chamber types already studied in literature. This work provides msr correction factors for additional chambers used in reference dosimetry. All of them were close to one (within 1%).

  13. Factoring

    NSDL National Science Digital Library

    Mr Clark

    2012-10-31

    Test your factoring skills Factors and Multiples Jeopardy How much do you know about factoring and multiples? Play Jeopardy and find out! Prime Factoring Turkey Shoot Blast these turkeys using your factoring skills. Help the Professor Super save the planet by "cooking" the Giant Frozen Turkeys of Destruction. Math Lines 12 X-Factor Shoot the ball at the other factors to get a product of 12. You can also ...

  14. Long-term monitoring of hydrogeological activation behaviour of an active landslide system using time-lapse temperature-corrected electrical resistance geophysical measurements

    NASA Astrophysics Data System (ADS)

    Merritt, Andrew; Murphy, William; Chambers, Jonathan; Wilkinson, Paul; West, Jared; Uhlemann, Sebastian

    2015-04-01

    If the effects of landslides are to be mitigated and avoided then the causes of landslide activations - and re-activations - must be better understood. The most common subsurface property change in the lead up to rainfall-triggered landslide activation is the moisture content of slope material and associated pore water pressure rises and/or consistency changes. If these characteristic subsurface physical properties can be observed in advance of activation then early warning of imminent slope activation may be possible. Recent advances in geoelectrical monitoring techniques reveal that time-lapse electrical resistivity tomography (ERT) is a useful tool, capable of observing hillslope hydrogeological processes. However, most previous studies lasted a short time-frame and compared few tomograms. Therefore, a geophysical imaging system through which the progressive wetting of the ground in response to rainfall leading to saturation and then sliding can be observed would seem to be a sensible approach to explore the forecasting of imminent landslide movement. Presented here is the analysis and interpretation of the results of a four and a half year, long-term and high temporal resolution monitoring campaign of a periodically active inland landslide, located in the UK, by a geoelectrical monitoring system called Automated time-Lapse Electrical Resistivity Tomography (ALERT). Time-lapse temperature-corrected transfer resistances reveal that the system responds very well to rises and falls in piezometric level and seasonal trends of soil desiccation during warmer, drier months and crack annealing and soil moisture accumulation in response to wetter periods. The existence of threshold slope moisture contents, and hence electrical resistances, above which the slope activates are not observed in resistance/resistivity results most probably due to the complex nature of the landslide system, the monitoring system resolution and a number of physical slope processes taking place. An exciting development is our improved understanding of shallow earthflow pre-activation hydrogeological behaviour. When interpreted alongside piezometry, an apparent increase in resistance in the months preceding earthflow activation reveals subtle geomechanical processes occurring, including slip surface drainage, due to soil dilation, as strain develops. Correlation between piezometric level fall and associated temperature-corrected resistance rise highlight the sensitivity of the geophysical monitoring system to landslide hydrogeological processes.

  15. Metabolic shift in liver: Correlation between perfusion temperature and hypoxia inducible factor-1?

    PubMed Central

    Ferrigno, Andrea; Di Pasqua, Laura Giuseppina; Bianchi, Alberto; Richelmi, Plinio; Vairetti, Mariapia

    2015-01-01

    AIM: To study at what temperature the oxygen carried by the perfusate meets liver requirements in a model of organ perfusion. METHODS: In this study, we correlated hypoxia inducible factor (HIF)-1? expression to the perfusion temperature and the hepatic oxygen uptake in a model of isolated perfused rat liver. Livers from Wistar rats were perfused for 6 h with an oxygenated medium at 10, 20, 30 and 37?°C. Oxygen uptake was measured by an oxygen probe; lactate dehydrogenase activity, lactate release and glycogen were measured spectrophotometrically; bile flow was gravitationally determined; pH of the perfusate was also evaluated; HIF-1? mRNA and protein expression were analyzed by real time-polymerase chain reaction and ELISA, respectively. RESULTS: Livers perfused at 10 and 20?°C showed no difference in lactate dehydrogenase release after 6 h of perfusion (0.96 ± 0.23 vs 0.93 ± 0.09 mU/min per g) and had lower hepatic damage as compared to 30 and 37?°C (5.63 ± 0.76 vs 527.69 ± 45.27 mU/min per g, respectively, Ps < 0.01). After 6 h, tissue ATP was significantly higher in livers perfused at 10 and 20?°C than in livers perfused at 30 and 37?°C (0.89 ± 0.06 and 1.16 ± 0.05 vs 0.57 ± 0.09 and 0.33 ± 0.08 nmol/mg, respectively, Ps < 0.01). No sign of hypoxia was observed at 10 and 20?°C, as highlighted by low lactate release respect to livers perfused at 30 and 37?°C (121.4 ± 12.6 and 146.3 ± 7.3 vs 281.8 ± 45.3 and 1094.5 ± 71.7 nmol/mL, respectively, Ps < 0.02), and low relative HIF-1? mRNA (0.40 ± 0.08 and 0.20 ± 0.03 vs 0.60 ± 0.20 and 1.47 ± 0.30, respectively, Ps < 0.05) and protein (3.72 ± 0.16 and 3.65 ± 0.06 vs 4.43 ± 0.41 and 6.44 ± 0.82, respectively, Ps < 0.05) expression. CONCLUSION: Livers perfused at 10 and 20?°C show no sign of liver injury or anaerobiosis, in contrast to livers perfused at 30 and 37?°C. PMID:25632183

  16. The Retrieval of Ice Water Content from Radar Reflectivity Factor and Temperature and Its Use in Evaluating a Mesoscale Model

    E-print Network

    Hogan, Robin

    The Retrieval of Ice Water Content from Radar Reflectivity Factor and Temperature and Its Use form 11 June 2005) ABSTRACT Ice clouds are an important yet largely unvalidated component of weather, demonstrating that, for stratiform midlatitude ice clouds, radar reflectivity in the Rayleigh-scattering regime

  17. Detergents and water temperature as factors in methyl parathion removal from denim fabrics

    Microsoft Academic Search

    C. B. Easley; J. M. Laughlin; R. E. Gold; K. Schmidt

    1982-01-01

    Conclusions Based on the results of this investigation, contaminated denim fabrics should not be laundered in 30°C (85°F) temperature; hotter temperatures are more effective. Although detergents could not be statistically separated, heavy duty liquid detergents appeared to excel in providing higher levels of pesticide removal in water temperatures of 49°C and 60°C. To determine the optimal conditions for pesticide removal

  18. Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature.

    PubMed

    He, Xiaodong; Miao, Shiguang; Shen, Shuanghe; Li, Ju; Zhang, Benzhi; Zhang, Ziyue; Chen, Xiujie

    2015-03-01

    Sky view factor (SVF), which is an indicator of urban canyon geometry, affects the surface energy balance, local air circulation, and outdoor thermal comfort. This study focused on a continuous and long-term meteorological observation system to investigate the effects of SVF on outdoor thermal conditions and physiological equivalent temperature (PET) in the central business district (CBD) of Beijing (which is located within Chaoyang District), specifically addressed current knowledge gaps for SVF-PET relationships in cities with typical continental/microthermal climates. An urban sub-domain scale model and the RayMan model were used to diagnose wind fields and to calculate SVF and long-term PET, respectively. Analytical results show that the extent of shading contributes to variations in thermal perception distribution. Highly shaded areas (SVF <0.3) typically exhibit less frequent hot conditions during summer, while enduring longer periods of cold discomfort in winter than moderately shaded areas (0.3< SVF <0.5) and slightly shaded areas (SVF >0.5), and vice versa. Because Beijing has a monsoon-influenced humid continental climate with hot summers and long, cold, windy, and dry winters, a design project that ideally provides moderate shading should be planned to balance hot discomfort in summer and cold discomfort in winter, which effectively prolongs the comfort periods in outdoor spaces throughout the entire year. This research indicate that climate zone characteristics, urban environmental conditions, and thermal comfort requirements of residents must be accounted for in local-scale scientific planning and design, i.e., for urban canyon streets and residential estates. PMID:24842520

  19. Quantitative Analysis of the Head Scatter and Jaw Transmission Correction Factor for Commissioning of Enhanced Dynamic Wedge Fields Using a MapCHECK 2 Diode Array

    NASA Astrophysics Data System (ADS)

    Dickerson, Edward C.

    Quality assurance in radiation oncology treatment planning requires independent verification of dose to be delivered to a patient through "second check" calculations for simple plans as well as planar dose fluence measurements for more complex treatments, such as intensity modulated radiation treatments (IMRT). Discrepancies between treatment planning system (TPS) and second check calculations created a need for treatment plan verification using a two dimensional diode array for Enhanced Dynamic Wedge (EDW) fields. While these measurements met clinical standards for treatment, they revealed room for improvement in the EDW model. The purpose of this study is to analyze the head scatter and jaw transmission effects of the moving jaw in EDW fields by measuring dose profiles with a two dimensional diode array in order to minimize differences between the manufacturer provided fluence table (Golden Segmented Treatment Table) and actual machine output. The jaw transmission effect reduces the dose gradient in the wedge direction due to transmission photons adding dose to the heel region of the field. The head scatter effect also reduces the gradient in the dose profile due to decreased accelerator output at increasingly smaller field sizes caused by the moving jaw. The field size continuously decreases with jaw motion, and thus the toe region of the wedge receives less dose than anticipated due to less head scatter contribution for small field sizes. The Golden Segmented Treatment Table (GSTT) does not take these factors into account since they are specific to each individual machine. Thus, these factors need to be accounted for in the TPS to accurately model the gradient of the wedge. The TPS used in this clinic uses one correction factor (transmission factor) to account for both effects since both factors reduce the dose gradient of the wedge. Dose profile measurements were made for 5x5 cm2, 10x10 cm2, and 20x20 cm2 field sizes with open fields and 10°, 15°, 20°, 25°, 30°, 45°, and 60° wedges for 6 MV and 18 MV beams and compared with TPS generated profiles. The transmission factor was adjusted for the 18 MV beam to obtain a better correlation between planned and measured dose gradient by reducing the gradient of the wedge in the TPS. This correction resulted in an average and maximum pass rate improvement for patient plans at a distance to agreement of 3% 3mm of 1.07% and 3.9% respectively. The off axis ratio data in the second check calculation software was also adjusted to bring the dose agreement between the initial TPS calculation and second check calculation within clinical standards. This study demonstrated the ability to adjust the EDW gradient in a treatment planning system to improve the differences in machine output specific to each machine and the manufacturer provided GSTT.

  20. Temperature change and its effect factors in the Yangtze Delta, China

    NASA Astrophysics Data System (ADS)

    Shi, Jun; Tang, Xu; Cui, Linli; Gao, Zhiqiang

    2007-09-01

    Based on the meteorological data, land use date from TM images and social statistical data, the evidences of regional temperature change with the elements of mean annual temperature, mean annual maximum and minimum temperature, and extreme high and low temperature from 1959 to 2005, were detected, and the impact of human activities on temperature was analyzed in the Yangtze Delta region. The results indicated an increase in mean annual temperature, mean annual maximum and minimum temperature. Mean annual temperature in all cities in the region increased, and the increase rate in winter was greater than that in spring and autumn. The increase of mean annual maximum and minimum temperature was similar to that of mean annual temperature spatially. In 3 stations of Shanghai, Nanjing and Hangzhou, most hot days, least cold days and the highest mean temperature all appeared in the first 5 years in this century. Land use changed greatly, and a large amount of cropland was replaced with residential and constructional areas (R/C areas) from 1980 to 2000 in the Yangtze Delta region. The change of mean annual temperature was partly corresponding to the change of land use. Total registered population increased rapidly in 16 cities of the Yangtze Delta region, and a good linear correlation between the tendency ratio of total registered population and the mean annual temperature in 16 cities from 1978 to 2005. Total amount of energy consumption and GDP increased in 3 provinces of Shanghai, Jiangsu and Zhejiang where the Yangtze Delta located, both the final consumption of energy by industry and GDP had a relatively good linear relationship with the mean annual temperature in Shanghai from 1952 to 2005. This paper will help the understanding and attribution of climate change and simulation of the future response of weather-related disasters under various global change scenarios.

  1. SUMMER STREAM TEMPERATURES, JUVENILE COHO CONDITION FACTORS AND BLACK SPOT INFECTION IN THE OREGON COAST RANGE

    EPA Science Inventory

    We monitored stream temperatures at 35 locations throughout the West Fork Smith River watershed in the Oregon Coast Range during the summer of 2002. Between July 24 and August 24, maximum seven-day moving average high daily temperatures ranged from 21.8 C near the catchment's mo...

  2. Effect of design factors on surface temperature and wear in disk brakes

    NASA Technical Reports Server (NTRS)

    Santini, J. J.; Kennedy, F. E.; Ling, F. F.

    1976-01-01

    The temperatures, friction, wear and contact conditions that occur in high energy disk brakes are studied. Surface and near surface temperatures were monitored at various locations in a caliper disk brake during drag type testing, with friction coefficient and wear rates also being determined. The recorded transient temperature distributions in the friction pads and infrared photographs of the rotor disk surface both showed that contact at the friction surface was not uniform, with contact areas constantly shifting due to nonuniform thermal expansion and wear. The effect of external cooling and of design modifications on friction, wear and temperatures was also investigated. It was found that significant decreases in surface temperature and in wear rate can be achieved without a reduction in friction either by slotting the contacting face of the brake pad or by modifying the design of the pad support to improve pad compliance. Both design changes result in more uniform contact conditions on the friction surface.

  3. Trends in 1970-2010 summertime coastal California air temperatures:how HCN-corrections to COOP-data eliminated coastal-cooling

    NASA Astrophysics Data System (ADS)

    Bornstein, R. D.; Ghebreegziabher, A. T.; Lebassi, B.; González, J. E.

    2011-12-01

    The analysis of California COOP-site monthly-averaged summer Tmax-trends (1970-2005) by Lebassi et al. (2009, in J. of Climate) has been extended by: (a) lengthening the period to 2010, (b) trend-comparisons with newly released HCN data, and (c) calculation of trends in annual Tmax-values. HCN data sets are NCDC-homogenized subsets of the "most trusted" COOP sites; they include 12 (of the 52 COOP sites) in the San Francisco Bay Area and four (of 28) in the Southern California Air Basin (SoCAB). COOP data used as HCN1 data were adjusted by NCDC for the following biases: (a) time-of-observations, (b) spatial inhomogeneity, (c) missing values, (d) changes in thermometer type, and (e) urban warming, while HCN2 data do not include the last two corrections. Comparison of the 35- and 40-year COOP monthly-averaged Tmax-trends at the 16 HCN sites showed a high correlation (0.96). It also showed, however, that as the six inland warming-sites (COOP sites also HCN sites) of Lebassi et al. are now generally warming a slightly lower rate than five years ago, the seven comparable coastal-cooling sites are thus now generally cooling at a slightly lower rate. Coastal-cooling was shown by Lebassi et al. as a "reverse-reaction" to regional warming in inland areas, which triggers coastal sea breezes, and which thus increased cooling onshore flows. Comparison of HCN1 and COOP 35-year Tmax-trends shows little correlation (0.15), as the HCN1-corrections changed six of the seven COOP cooling-sites into HCN1 warming-sites. Only the site with largest original COOP cooling also showed HCN1 cooling. Similar comparisons between the COOP and HCN2 sites showed that HCN2-corrections changed fewer (only four) cooling-sites to warming (and with lower warming-rates); a low correlation (0.44) thus existed between trend-values. As many climate-change impacts (e.g., brown outs, heat stress, ozone peaks) depend on extreme Tmax-values, and not just averaged-monthly Tmax-values, the SoCAB distribution of the highest COOP Tmax-values anytime (at each of its 28 sites) during the period from 1970-2010 shows three sub-areas, with a boundary-temperature of 340C (and with the following ranges): (a) cool coastal (27-340C), (b) cool mountain-tops (28-340C), and (c) in-between hot-area (34-400C). The spatial distribution of the trends in these extreme Tmax-values show decreases up to -0.80C/dec in the coastal cooling areas and increases up to 0.60C/dec in the inland and mountain warming areas. Note that these trends are larger than the monthly-averaged Tmax-trends (about ±0.30C/dec) in Lebassi et al.

  4. Fluctuation corrections on thermodynamic functions: Finite size effect

    E-print Network

    Sudarson Sekhar Sinha; Arnab Ghosh; Deb Shankar Ray

    2013-04-26

    The explicit thermodynamic functions, in particular, the specific heat of a spin system interacting with a spin bath which exerts finite dissipation on the system are determined. We show that the specific heat is a sum of the products of a thermal equilibration factor that carries the temperature dependence and a dynamical correction factor, characteristic of the dissipative energy flow under steady state from the system. The variation of specific heat with temperature is accompanied by an abrupt transition that depends on these dynamical factors characteristic of the finite system size.

  5. JAIBA, a class-II HD-ZIP transcription factor involved in the regulation of meristematic activity, and important for correct gynoecium and fruit development in Arabidopsis.

    PubMed

    Zúñiga-Mayo, Victor M; Marsch-Martínez, Nayelli; de Folter, Stefan

    2012-07-01

    The gynoecium is one of the most complex organs of a plant. After fertilization, it becomes a fruit, which has two important functions: to protect the seeds while they develop and to disperse them at maturity. The development and patterning of the gynoecium and later fruit must be finely regulated to ensure the survival of the species that produces them. The process that leads to successful fruit formation starts at early stages of floral meristem development and follows a series of chronologically successive events. In this work we report the functional characterization of the class-II homeodomain leucine zipper (HD-ZIP) JAIBA (JAB) gene. Mutant jab plants show sporophytic defects in male and female reproductive development, and combined with crabs claw cause defects in the floral meristem (FM) determination process and gynoecium medial tissue development. This suggests that proper FM determination is required for gynoecium medial tissue development, and indicates that JAB and CRC are necessary for both processes. Furthermore, the JAB protein interacts with transcription factors known to regulate meristematic activity, fruit development, and floral meristem determinacy. The sporophytic effect on pollen and embryo sac development might be an independent and later function of JAB. In summary, we present data that indicates that the JAB gene regulates meristematic activity in different tissues, and that it is necessary for the correct formation of the gynoecium at different stages, contributing to a crucial process in plant life: proper fruit development. PMID:22409594

  6. Temperature

    NASA Technical Reports Server (NTRS)

    Berenson, P. J.; Robertson, W. G.

    1973-01-01

    The problems in human comfort in heat stress are emphasized, with less emphasis placed upon cold exposure problems. Physiological parameters related to human thermal interactions are discussed, as well as data concerning thermal protective clothing. The energy balance equation, heat transfer equation, thermal comfort, heat stress, and cold stress are also considered. A two node model of human temperature regulation in FORTRAN is appended.

  7. Proposal to Acquire Experimental Data and to Model the Results with a Monte Carlo Calculation of a Secondary Source Correction Factor for Area Source Acquisitions of Holdup y-PHA Measurements

    SciTech Connect

    Dewberry, R.

    2003-02-10

    This report describes an interference observed when acquiring y-ray holdup data. The interference comes from secondary contaminated surfaces that contribute to the y-ray signal when acquiring data in the area source configuration. It is often the case that these unwanted contributions can not be isolated and eliminated, so it is necessary to mathematically correct for the contribution. In this report we propose experiments to acquire the necessary data to determine the experimental correction factor specifically for highly enriched uranium holdup measurements. We then propose to use the MCNP Monte Carlo computer code to model the contribution in several acquisition configurations and for multiple interfering y-ray energies. Results will provide a model for calculation of this secondary source correction factor for future holdup measurements. We believe the results of the experiments and modeling of the data acquired in this proposal will have a significant impact on deactivation and de commissioning activities throughout the DOE weapons complex.

  8. Effect of temperature, density, and technical factors on the shock-wave sensitivity of plastic TATB

    Microsoft Academic Search

    Y. A. Vlasov; V. B. Kosolapov; L. V. Fomicheva; I. P. Khabarov

    1998-01-01

    Results are presented from a study of the shock-wave sensitivity of plastic TATB over a wide range of temperatures. It is\\u000a shown that the temperature dependence of the shock-wave sensitivity of this explosive material is explained to a great extent\\u000a by the change in density owing to thermal expansion, and by relaxation processes that occur in the samples.

  9. Absorbed dose beam quality correction factors kappaQ for the NE2571 chamber in a 5 MV and a 10 MV photon beam.

    PubMed

    Palmans, H; Mondelaers, W; Thierens, H

    1999-03-01

    Dose to water (Dw) determination in clinical high-energy photon beams with ionization chambers calibrated in terms of absorbed dose to water has been proposed as an alternative to ionization chamber dosimetry based on air kerma calibrations. Dw in the clinical beam is derived using a kappaQ factor that scales the absorbed dose calibration factor in the reference beam to the absorbed dose calibration factor in the user beam. In the present study kappaQ values were determined for the NE2571 chamber in a 5 MV and a 10 MV high-energy photon beam generated at the 15 MeV high-intensity electron linac of the University of Gent. A set of three NE2571 chambers was calibrated relative to the Gent sealed water calorimeter both in 60Co and in the linac beam at a depth of 5 cm and a source to detector distance of 100 cm. Two high-purity chemical water systems were used in the detection vessel of the calorimeter, H2-saturated and Ar-saturated pure water, which are both supposed to give a zero heat defect. TPR20(10) and %dd(10) have been evaluated as beam quality specifiers. Simulations using the BEAM/DOSXYZ Monte Carlo system were performed to evaluate potential corrections on the measured beam qualities. The average kappaQ values measured for the three NE2571 chambers in the 5 MV and 10 MV photon beams are 0.995 +/- 0.005 and 0.979 +/- 0.005 respectively. For the three chambers used, the maximum deviation of individual kappaQ values is 0.2%. The measured beam quality specifiers %dd(10) and TPR20(10) are 67.0 and 0.705 for the 5 MV beam and 75.0 and 0.759 for the 10 MV beam. Although our beam design is very different from those used by other investigators for the measurement of kappaQ values, the agreement with their results is satisfactory showing a slightly better agreement when %dd(10) is used as the beam quality specifier. PMID:10211800

  10. Role of Hot Water System Design on Factors Influential to Pathogen Regrowth: Temperature, Chlorine Residual, Hydrogen Evolution, and Sediment

    PubMed Central

    Brazeau, Randi H.; Edwards, Marc A.

    2013-01-01

    Abstract Residential water heating is linked to growth of pathogens in premise plumbing, which is the primary source of waterborne disease in the United States. Temperature and disinfectant residual are critical factors controlling increased concentration of pathogens, but understanding of how each factor varies in different water heater configurations is lacking. A direct comparative study of electric water heater systems was conducted to evaluate temporal variations in temperature and water quality parameters including dissolved oxygen levels, hydrogen evolution, total and soluble metal concentrations, and disinfectant decay. Recirculation tanks had much greater volumes of water at temperature ranges with potential for increased pathogen growth when set at 49°C compared with standard tank systems without recirculation. In contrast, when set at the higher end of acceptable ranges (i.e., 60°C), this relationship was reversed and recirculation systems had less volume of water at risk for pathogen growth compared with conventional systems. Recirculation tanks also tended to have much lower levels of disinfectant residual (standard systems had 40–600% higher residual), 4–6 times as much hydrogen, and 3–20 times more sediment compared with standard tanks without recirculation. On demand tankless systems had very small volumes of water at risk and relatively high levels of disinfectant residual. Recirculation systems may have distinct advantages in controlling pathogens via thermal disinfection if set at 60°C, but these systems have lower levels of disinfectant residual and greater volumes at risk if set at lower temperatures. PMID:24170969

  11. The effects of incomplete annealing on the temperature dependence of sheet resistance and gage factor in aluminum and phosphorus implanted silicon on sapphire

    NASA Technical Reports Server (NTRS)

    Pisciotta, B. P.; Gross, C.

    1976-01-01

    Partial annealing of damage to the crystal lattice during ion implantation reduces the temperature coefficient of resistivity of ion-implanted silicon, while facilitating controlled doping. Reliance on this method for temperature compensation of the resistivity and strain-gage factor is discussed. Implantation conditions and annealing conditions are detailed. The gage factor and its temperature variation are not drastically affected by crystal damage for some crystal orientations. A model is proposed to account for the effects of electron damage on the temperature dependence of resistivity and on silicon piezoresistance. The results are applicable to the design of silicon-on-sapphire strain gages with high gage factors.

  12. Hsp90 binds and regulates Gcn2, the ligand-inducible kinase of the alpha subunit of eukaryotic translation initiation factor 2 [corrected].

    PubMed

    Donzé, O; Picard, D

    1999-12-01

    The protein kinase Gcn2 stimulates translation of the yeast transcription factor Gcn4 upon amino acid starvation. Using genetic and biochemical approaches, we show that Gcn2 is regulated by the molecular chaperone Hsp90 in budding yeast Saccharomyces cerevisiae. Specifically, we found that (i) several Hsp90 mutant strains exhibit constitutive expression of a GCN4-lacZ reporter plasmid; (ii) Gcn2 and Hsp90 form a complex in vitro as well as in vivo; (iii) the specific inhibitors of Hsp90, geldanamycin and macbecin I, enhance the association of Gcn2 with Hsp90 and inhibit its kinase activity in vitro; (iv) in vivo, macbecin I strongly reduces the levels of Gcn2; (v) in a strain expressing the temperature-sensitive Hsp90 mutant G170D, both the accumulation and activity of Gcn2 are abolished at the restrictive temperature; and (vi) the Hsp90 cochaperones Cdc37, Sti1, and Sba1 are required for the response to amino acid starvation. Taken together, these data identify Gcn2 as a novel target for Hsp90, which plays a crucial role for the maturation and regulation of Gcn2. PMID:10567567

  13. Ambient temperature: a factor affecting performance and physiological response of broiler chickens

    NASA Astrophysics Data System (ADS)

    Donkoh, A.

    1989-12-01

    An experiment was conducted to elucidate the influence of four constant ambient temperatures (20°, 25°, 30° and 35°C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20°, 25°, 30° and 35°C treatments showed highly significant ( P<0.0001) depression in growth rate, food intake and efficiency of food utilization, and a significant increase in water consumption for the 30° and 35°C groups. Mortality was, however, not affected by the temperature treatments. Changes in physiological status, such as increased rectal temperatures, decreased concentration of red blood cells, haemoglobin, haematocrit, and total plasma protein were observed in birds housed in the higher temperature (30° and 35°C) environments. Moreover, in these broiler chickens, there was an increased blood glucose concentration and a decreased thyroid gland weight. These results indicate that continuous exposure of broiler chickens to high ambient temperatures markedly affects their performance and physiological response.

  14. Uncovering different masking factors on wrist skin temperature rhythm in free-living subjects.

    PubMed

    Martinez-Nicolas, Antonio; Ortiz-Tudela, Elisabet; Rol, Maria Angeles; Madrid, Juan Antonio

    2013-01-01

    Most circadian rhythms are controlled by a major pacemaker located in the hypothalamic suprachiasmatic nucleus. Some of these rhythms, called marker rhythms, serve to characterize the timing of the internal temporal order. However, these variables are susceptible to masking effects as the result of activity, body position, light exposure, environmental temperature and sleep. Recently, wrist skin temperature (WT) has been proposed as a new index for evaluating circadian system status. In light of previous evidence suggesting the important relationship between WT and core body temperature regulation, the aim of this work was to purify the WT pattern in order to obtain its endogenous rhythm with the application of multiple demasking procedures. To this end, 103 subjects (18-24 years old) were recruited and their WT, activity, body position, light exposure, environmental temperature and sleep were recorded under free-living conditions for 1 week. WT demasking by categories or intercepts was applied to simulate a "constant routine" protocol (awakening, dim light, recumbent position, low activity and warm environmental temperature). Although the overall circadian pattern of WT was similar regardless of the masking effects, its amplitude was the rhythmic parameter most affected by environmental conditions. The acrophase and mesor were determined to be the most robust parameters for characterizing this rhythm. In addition, a circadian modulation of the masking effect was found for each masking variable. WT rhythm exhibits a strong endogenous component, despite the existence of multiple external influences. This was evidenced by simultaneously eliminating the influence of activity, body position, light exposure, environmental temperature and sleep. We therefore propose that it could be considered a valuable and minimally-invasive means of recording circadian physiology in ambulatory conditions. PMID:23577201

  15. Uncovering Different Masking Factors on Wrist Skin Temperature Rhythm in Free-Living Subjects

    PubMed Central

    Martinez-Nicolas, Antonio; Ortiz-Tudela, Elisabet; Rol, Maria Angeles; Madrid, Juan Antonio

    2013-01-01

    Most circadian rhythms are controlled by a major pacemaker located in the hypothalamic suprachiasmatic nucleus. Some of these rhythms, called marker rhythms, serve to characterize the timing of the internal temporal order. However, these variables are susceptible to masking effects as the result of activity, body position, light exposure, environmental temperature and sleep. Recently, wrist skin temperature (WT) has been proposed as a new index for evaluating circadian system status. In light of previous evidence suggesting the important relationship between WT and core body temperature regulation, the aim of this work was to purify the WT pattern in order to obtain its endogenous rhythm with the application of multiple demasking procedures. To this end, 103 subjects (18–24 years old) were recruited and their WT, activity, body position, light exposure, environmental temperature and sleep were recorded under free-living conditions for 1 week. WT demasking by categories or intercepts was applied to simulate a “constant routine” protocol (awakening, dim light, recumbent position, low activity and warm environmental temperature). Although the overall circadian pattern of WT was similar regardless of the masking effects, its amplitude was the rhythmic parameter most affected by environmental conditions. The acrophase and mesor were determined to be the most robust parameters for characterizing this rhythm. In addition, a circadian modulation of the masking effect was found for each masking variable. WT rhythm exhibits a strong endogenous component, despite the existence of multiple external influences. This was evidenced by simultaneously eliminating the influence of activity, body position, light exposure, environmental temperature and sleep. We therefore propose that it could be considered a valuable and minimally-invasive means of recording circadian physiology in ambulatory conditions. PMID:23577201

  16. Environmental Factors Influencing the Hyperfine Structure of Manganous Low-Temperature Electron Paramagnetic Resonance Spectra

    PubMed Central

    Nebert, D. W.; Allen, B. T.

    1966-01-01

    Hyperfine structure is observed in low temperature (T = -180°C) EPR (electron paramagnetic resonance) spectra of a number of solutions containing Mn++ ions 13, 15) which have characteristics in common with low temperature EPR spectra from biological substances such as mitochondria and microsomes (1-4). This investigation is an attempt to understand the features of these signals in terms of the molecular environment of the manganous ion, and a qualitative explanation for the observations reported here is advanced in terms of the amount of axial distortion of a manganese hydrate in different environments. PMID:4289642

  17. Assessing the correctional orientation of corrections officers in South Korea.

    PubMed

    Moon, Byongook; Maxwell, Sheila Royo

    2004-12-01

    The correctional goal in South Korea has recently changed from the straightforward punishment of inmates to rehabilitation. Currently, emphases are being placed on education, counseling, and other treatment programs. These changes have consequently begun to also change the corrections officers' roles from a purely custodial role to a human service role, in which officers are expected to manage rehabilitation and treatment programs. Despite these changes, few studies have examined the attitudes of corrections officers toward rehabilitation programming. This is an important dimension to examine in rehabilitation programming, as corrections officers play a major role in the delivery of institutional programs. This study examines the attitudes of South Korean corrections officers toward rehabilitation programs. Approximately 430 corrections officers were sampled. Results show that correctional attitudes are largely influenced by not only officers' own motivations for joining corrections but also by institutional factors such as job stress. Policy implications are discussed. PMID:15538029

  18. Temperature-dependent regulation of a heterologous transcriptional activation domain fused to yeast heat shock transcription factor.

    PubMed Central

    Bonner, J J; Heyward, S; Fackenthal, D L

    1992-01-01

    The heat shock transcription factor (HSF) of the yeast Saccharomyces cerevisiae is posttranslationally modified. At low growth temperatures, it activates transcription of heat shock genes only poorly; after shift to high temperatures, it activates transcription readily. In an effort to elucidate the mechanism of this regulation, we constructed a series of HSF-VP16 fusions that join the HSF DNA-binding domain to the strong transcriptional activation domain from the VP16 gene of herpes simplex virus. Replacement of the endogenous C-terminal transcriptional activation domain with that of VP16 generates an HSF derivative that exhibits behavior reminiscent of HSF itself: low transcriptional activation activity at normal growth temperature and high activity after heat shock. HSF can thus restrain the activity of the heterologous VP16 transcriptional activation domain. To determine what is required for repression of activity at low temperature, we deleted portions of HSF from this HSF-VP16 fusion to map the regulatory domain. We also isolated point mutations that convert the HSF-VP16 fusion into a constitutive transcriptional activator. We conclude that the central, evolutionarily conserved domain of HSF, encompassing the DNA-binding and multimerization domains, contains a major determinant of temperature-dependent regulation. Images PMID:1545786

  19. A Monte Carlo method to evaluate the impact of positioning errors on detector response and quality correction factors in nonstandard beams.

    PubMed

    Bouchard, Hugo; Seuntjens, Jan; Kawrakow, Iwan

    2011-04-21

    During experimental procedures, an adequate evaluation of all sources of uncertainty is necessary to obtain an overall uncertainty budget. In specific radiation dosimetry applications where a single detector is used, common methods to evaluate uncertainties caused by setup positioning errors are not applicable when the dose gradient is not known a priori. This study describes a method to compute these uncertainties using the Monte Carlo method. A mathematical formalism is developed to calculate unbiased estimates of the uncertainties. The method is implemented in egs_chamber, an EGSnrc-based code that allows for the efficient calculation of detector doses and dose ratios. The correct implementation of the method into the egs_chamber code is validated with an extensive series of tests. The accuracy of the developed mathematical formalism is verified by comparing egs_chamber simulation results to the theoretical expectation in an ideal situation where the uncertainty can be computed analytically. Three examples of uncertainties are considered for realistic models of an Exradin A12 ionization chamber and a PTW 60012 diode, and results are computed for parameters representing nearly realistic positioning error probability distributions. Results of practical examples show that uncertainties caused by positioning errors can be significant during IMRT reference dosimetry as well as small field output factor measurements. The method described in this paper is of interest in the study of single-detector response uncertainties during nonstandard beam measurements, both in the scope of daily routine as well as when developing new dosimetry protocols. It is pointed out that such uncertainties should be considered in new protocols devoted to single-detector measurements in regions with unpredictable dose gradients. The method is available within the egs_chamber code in the latest official release of the EGSnrc system. PMID:21454927

  20. Rockslides in a changing climate: evaluating rainfall and temperature as triggering factors in southwestern Norway

    Microsoft Academic Search

    S. Dunlop; D. J. Hutchinson

    2009-01-01

    Climatic conditions such as rainfall and temperature often play an important role in the triggering of geohazards, such as landslides, rockfalls and snow avalanches. This is especially true in coastal, mountainous areas such as Norway. In the last 150 years, geohazards have resulted in over 2,000 casualties in Norway, making it an important area of study. With recent climate research

  1. Ambient temperature: a factor affecting performance and physiological response of broiler chickens

    Microsoft Academic Search

    A. Donkoh

    1989-01-01

    An experiment was conducted to elucidate the influence of four constant ambient temperatures (20°, 25°, 30° and 35°C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20°, 25°,

  2. Temperature and nutrition as factors in conditioning broodstock of the commercial scallop Pecten fumatus Reeve

    Microsoft Academic Search

    Michael. P. Heasman; Wayne. A. O'Connor; Allen. W. Frazer

    1996-01-01

    Difficulty in obtaining ripe broodstock of the commercial scallop Pecten fumatus from wild populations in New South Wales prompted the development of hatchery conditioning protocols. Microalgal diets, feeding rates and holding temperatures conducive to rapid gonadal growth and development were identified. Results of microalgal clearance rate experiments indicated that the species Pavlova lutheri, Tahitian Isochrysis aff. galbana, Chroomonas salina and

  3. Calibration factor of track etch detectors at different temperatures of water 

    E-print Network

    Yasmeen, Nuzhat

    1997-01-01

    with the increase of integrated radon exposures in water. The CR-39 etch detector is observed to be more sensitive to alpha particles than LR 115 Type 2 film. The exposure period ranged from 1 to 10 days. The linearity test was done at room temperature. The actual...

  4. Creep and stress relaxation in a longitudinal polymer liquid crystal: Prediction of the temperature shift factor

    E-print Network

    North Texas, University of

    University of Technology, 412-96 Gothenburg, Sweden Robert Maksimovd) Institute of Polymer Mechanics 17 February 1999 The polymer liquid crystal PLC is the PET/0.6PHB copolymer; PET poly ethylene data for a polymer liquid crystal PLC . The PLC in its service temperature range contains four phases,2

  5. Comparison of models for the free-free Gaunt factor at low temperatures and frequencies

    SciTech Connect

    Collins, L.A.; Merts, A.L.

    1985-01-01

    We perform calculations for the free-free Gaunt factor at electron and photon energies below 1 Ry in the dipole approximation to the radiation field for a variety of representations of the scattering potential. We consider the static-exchange, static-exchange + model polarization, model exchange, and static models. Within each model, the resulting Schroedinger equation is solved exactly using a linear algebraic prescription. We investigate the rare gas and alkali systems. We find great sensitivity to the models for energies below four electron volts (4 eV). Above this energy, the Gaunt factors for the various models come into better agreement. 31 refs., 3 figs., 1 tab.

  6. Sensitivity of the hydrological cycle to corrections of the sea surface temperature biases over southern Africa in a regional climate model

    NASA Astrophysics Data System (ADS)

    Weber, Torsten; Hänsler, Andreas; Jacob, Daniela

    2015-04-01

    High resolution climate change projections of the hydrological cycle are of particular importance for southern Africa since possible changes of the climate will affect the water availability and thus the lives of the people in this region. In order to obtain high resolution climate change information for the future, regional climate models (RCMs) are used to downscale climate change projections generated with general circulation models (GCMs). These GCMs are usually coupled with an ocean model providing ocean parameters such as sea surface temperature (SST) needed by GCMs. The hydrological cycle in southern Africa is strongly affected by the moisture transport from the Atlantic and Indian Ocean and, consequently, from their SSTs. In the Atlantic Ocean, the cold up-welling Benguela current flows up the west coast of southern Africa whereas the Agulhas current flows down the east coast in the Indian Ocean. Deficiencies in the description and representation of such currents in ocean models cause biases in simulated SSTs and affect the moisture uptake of lower air layers. Initially, a historical simulation conducted with the general circulation model ECHAM6 was downscaled with the regional climate model REMO to a spatial resolution of 50 x 50 km² for the whole African continent. To analyse the sensitivity of the hydrological cycle to SST corrections, five experiments were carried out with REMO covering five simulation years. The five sensitivity experiments were downscaled with REMO to a spatial resolution of 25 x 25 km² for southern Africa using the coarser simulation as input. In the first experiment, the entire SST in the coupled ECHAM6 simulation both of the Atlantic and Indian ocean was replaced by the SST from the ERA-Interim reanalysis data, and in two another ones, only the Atlantic Ocean with the Benguela current and the Indian Ocean including the Agulhas current were replaced by the SST from the ERA-Interim reanalysis data, respectively. Besides a control experiment, in which the SST from the coupled ECHAM6 simulation has been kept unchanged, an experiment with perturbed atmospheric conditions was performed with REMO to assess the internal model variability. The results show a distinct impact of the SST biases on the hydrological cycle in southern Africa. In particular, the contribution of the SST bias of the Atlantic Ocean is stronger, which should be taken into account for climate change projections.

  7. Temperature, Relative Humidity and Pathogen Factors Influencing Phytophthora Infestans Development on Hairy Nightshade

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hairy nightshade (Solanum sarrachoides Sendt) is a common weed that can serve as an alternate host for potato late blight. Although environmental and pathogen factors are key variables affecting the development of late blight, little is known regarding their potential effects on infection of hairy n...

  8. Developmental Expression of Steroidogenic Factor 1 in a Turtle with Temperature-Dependent Sex Determination

    E-print Network

    Crews, David

    tissues of the red-eared slider turtle (Trachemys scripta), a TSD species, detected a single primary SF-1 Key Words: steroidogenic factor 1, SF-1; Ad4BP; FTZ-F1; reptile; turtle; Trachemys scripta-eared slider turtle (Trachemys scripta), only males are pro- duced when eggs are incubated at 26°C, and only

  9. Assessment of factors limiting Klamath River fall Chinook salmon production potential using historical flows and temperatures

    USGS Publications Warehouse

    Bartholow, John M.; Henriksen, James A.

    2006-01-01

    We parameterized and applied a deterministic salmon production model to infer the degree to which river flows and temperatures may limit freshwater production potential of the Klamath River in California. Specific parameter requirements, data sources, and significant assumptions are discussed in detail. Model simulations covered a wide variety of historical hydrologic and meteorologic conditions for 40+ years of environmental data. The model was calibrated only qualitatively, appearing to perform well in predicted outmigrant timing, but overestimating growth. Egg-to-outmigrant survival was near that reported for other rivers north of the Klamath River. Predicted production potential appeared to be determined by multiple causes involving both regularly occurring habitat-related constraints and irregularly occurring exposure to high water temperatures. Simulated production was greatest in years of intermediate water availability and was constrained in both dry and wet years, but for different reasons. Reducing mortality associated with limitations to juvenile habitat, if possible, would be expected to have the highest payoff in increasing production. Water temperature was important in determining predicted production in some years but overall was not predicted to be as important as physical microhabitat. No single mortality cause acted as a true a??bottlenecka?? on productiona?|

  10. Factoring

    NSDL National Science Digital Library

    Mrs. Taylor

    2010-10-19

    In this lesson we will explore prime numbers and factors A prime number has only two factors, 1 and itself. The Greek scholar, Eratosthenes of Cyrene lived from approximately 275 to 195 BC. He is know for being the first to have computed the size of the Earth and served as the director of the famous library in

  11. Factorize

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students find factor pairs for a given number and then create a rectangle with those dimensions on a coordinate plane. This activity allows students to explore factorizations of numbers and how they relate to rectangles with that number as an area. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  12. Microstructural factors influencing critical-current densities of high-temperature superconductors

    SciTech Connect

    Suenaga, M.

    1992-12-31

    Microstructural defects are the primary determining factors for the values of critical current densities in superconductors. A review is made to assess, (1) what would be the maximum achievable critical-current density in the oxide superconductors if nearly ideal pinning sites were introduced? and (2) what types of pinning defects are currently introduced in these superconductors and how effective are these in pinning the vortices? Only the case where the applied field is parallel to the c-axis is considered here.

  13. Microstructural factors influencing critical-current densities of high-temperature superconductors

    SciTech Connect

    Suenaga, M.

    1992-01-01

    Microstructural defects are the primary determining factors for the values of critical current densities in superconductors. A review is made to assess, (1) what would be the maximum achievable critical-current density in the oxide superconductors if nearly ideal pinning sites were introduced and (2) what types of pinning defects are currently introduced in these superconductors and how effective are these in pinning the vortices Only the case where the applied field is parallel to the c-axis is considered here.

  14. Genotype-specific risk factors for Staphylococcus aureus in Swiss dairy herds with an elevated yield-corrected herd somatic cell count.

    PubMed

    Berchtold, B; Bodmer, M; van den Borne, B H P; Reist, M; Graber, H U; Steiner, A; Boss, R; Wohlfender, F

    2014-08-01

    Bovine mastitis is a frequent problem in Swiss dairy herds. One of the main pathogens causing significant economic loss is Staphylococcus aureus. Various Staph. aureus genotypes with different biological properties have been described. Genotype B (GTB) of Staph. aureus was identified as the most contagious and one of the most prevalent strains in Switzerland. The aim of this study was to identify risk factors associated with the herd-level presence of Staph. aureus GTB and Staph. aureus non-GTB in Swiss dairy herds with an elevated yield-corrected herd somatic cell count (YCHSCC). One hundred dairy herds with a mean YCHSCC between 200,000 and 300,000cells/mL in 2010 were recruited and each farm was visited once during milking. A standardized protocol investigating demography, mastitis management, cow husbandry, milking system, and milking routine was completed during the visit. A bulk tank milk (BTM) sample was analyzed by real-time PCR for the presence of Staph. aureus GTB to classify the herds into 2 groups: Staph. aureus GTB-positive and Staph. aureus GTB-negative. Moreover, quarter milk samples were aseptically collected for bacteriological culture from cows with a somatic cell count ?150,000cells/mL on the last test-day before the visit. The culture results allowed us to allocate the Staph. aureus GTB-negative farms to Staph. aureus non-GTB and Staph. aureus-free groups. Multivariable multinomial logistic regression models were built to identify risk factors associated with the herd-level presence of Staph. aureus GTB and Staph. aureus non-GTB. The prevalence of Staph. aureus GTB herds was 16% (n=16), whereas that of Staph. aureus non-GTB herds was 38% (n=38). Herds that sent lactating cows to seasonal communal pastures had significantly higher odds of being infected with Staph. aureus GTB (odds ratio: 10.2, 95% CI: 1.9-56.6), compared with herds without communal pasturing. Herds that purchased heifers had significantly higher odds of being infected with Staph. aureus GTB (rather than Staph. aureus non-GTB) compared with herds without purchase of heifers. Furthermore, herds that did not use udder ointment as supportive therapy for acute mastitis had significantly higher odds of being infected with Staph. aureus GTB (odds ratio: 8.5, 95% CI: 1.6-58.4) or Staph. aureus non-GTB (odds ratio: 6.1, 95% CI: 1.3-27.8) than herds that used udder ointment occasionally or regularly. Herds in which the milker performed unrelated activities during milking had significantly higher odds of being infected with Staph. aureus GTB (rather than Staph. aureus non-GTB) compared with herds in which the milker did not perform unrelated activities at milking. Awareness of 4 potential risk factors identified in this study guides implementation of intervention strategies to improve udder health in both Staph. aureus GTB and Staph. aureus non-GTB herds. PMID:24881801

  15. Genetically distinct populations of northern shrimp, Pandalus borealis, in the North Atlantic: adaptation to different temperatures as an isolation factor.

    PubMed

    Jorde, Per Erik; Søvik, Guldborg; Westgaard, Jon-Ivar; Albretsen, Jon; André, Carl; Hvingel, Carsten; Johansen, Torild; Sandvik, Anne Dagrun; Kingsley, Michael; Jørstad, Knut Eirik

    2015-04-01

    The large-scale population genetic structure of northern shrimp, Pandalus borealis, was investigated over the species' range in the North Atlantic, identifying multiple genetically distinct groups. Genetic divergence among sample localities varied among 10 microsatellite loci (range: FST = -0.0002 to 0.0475) with a highly significant average (FST = 0.0149; P < 0.0001). In contrast, little or no genetic differences were observed among temporal replicates from the same localities (FST = 0.0004; P = 0.33). Spatial genetic patterns were compared to geographic distances, patterns of larval drift obtained through oceanographic modelling, and temperature differences, within a multiple linear regression framework. The best-fit model included all three factors and explained approximately 29% of all spatial genetic divergence. However, geographic distance and larval drift alone had only minor effects (2.5-4.7%) on large-scale genetic differentiation patterns, whereas bottom temperature differences explained most (26%). Larval drift was found to promote genetic homogeneity in parts of the study area with strong currents, but appeared ineffective across large temperature gradients. These findings highlight the breakdown of gene flow in a species with a long pelagic larval phase (up to 3 months) and indicate a role for local adaptation to temperature conditions in promoting evolutionary diversification and speciation in the marine environment. PMID:25782085

  16. Stress, temperature, heart rate, and hibernating factors in hamsters. [pathophysiological conditions resulting from exposure to zero gravity

    NASA Technical Reports Server (NTRS)

    Musacchia, X. J.

    1974-01-01

    Pathophysiological conditions resulting from prolonged exposure to zero gravity, cabin constraint, altered ambient environment, whether it be noise, vibrations, high temperatures, or combinations of such factors, are studied in laboratory animals and applied to manned space flight. Results and plans for further study are presented. Specific topics covered include: thermoregulation and its role in reflecting stress and adaptation to the gravity free environment and cabin confinement with its altered circadian forcings; renal function and its measurement in electrolyte distribution and blood flow dynamics; gastronintestinal function and an assessment of altered absorptive capacity in the intestinal mucosa; and catecholamine metabolism in terms of distribution and turnover rates in specific tissues.

  17. The time of day differently influences fatigue and locomotor activity: is body temperature a key factor?

    PubMed

    Machado, Frederico Sander Mansur; Rodovalho, Gisele Vieira; Coimbra, Cândido Celso

    2015-03-01

    The aim of this study was to verify the possible interactions between exercise capacity and spontaneous locomotor activity (SLA) during the oscillation of core body temperature (Tb) that occurs during the light/dark cycle. Wistar rats (n=11) were kept at an animal facility under a light/dark cycle of 14/10h at an ambient temperature of 23°C and water and food ad libitum. Initially, in order to characterize the daily oscillation in SLA and Tb of the rats, these parameters were continuously recorded for 24h using an implantable telemetric sensor (G2 E-Mitter). The animals were randomly assigned to two progressive exercise test protocols until fatigue during the beginning of light and dark-phases. Fatigue was defined as the moment rats could not keep pace with the treadmill. We assessed the time to fatigue, workload and Tb changes induced by exercise. Each test was separated by 3days. Our results showed that exercise capacity and heat storage were higher during the light-phase (p<0.05). In contrast, we observed that both SLA and Tb were higher during the dark-phase (p<0.01). Notably, the correlation analysis between the amount of SLA and the running capacity observed at each phase of the daily cycle revealed that, regardless of the time of the day, both types of locomotor physical activity have an important inherent component (r=0.864 and r=0.784, respectively, p<0.01) without a direct relationship between them. This finding provides further support for the existence of specific control mechanisms for each type of physical activity. In conclusion, our data indicate that the relationship between the body temperature and different types of physical activity might be affected by the light/dark cycle. These results mean that, although exercise performance and spontaneous locomotor activity are not directly associated, both are strongly influenced by daily cycles of light and dark. PMID:25479573

  18. Factors affecting sorption of nitro explosives to biochar: pyrolysis temperature, surface treatment, competition, and dissolved metals.

    PubMed

    Oh, Seok-Young; Seo, Yong-Deuk

    2015-05-01

    The application of rice straw-derived biochar for removing nitro explosives, including 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), from contaminated water was investigated through batch experiments. An increase in the pyrolysis temperature from 250 to 900°C in general led to higher pH, surface area, cation exchange capacity (CEC), point of zero charge, and C:O ratio of biochar. The maximum sorption capacity estimated by a mixed sorption-partition model increased when pyrolysis temperatures were elevated from 250 to 900°C, indicating that C content and aromaticity of biochar were strongly related to the sorption of nitro explosives to biochar. Surface treatment with acid or oxidant increased the sorption capacity of biochar for the two strong ?-acceptor compounds (DNT and TNT) but not for RDX. However, the enhancement of sorption capacity was not directly related to increased surface area and CEC. Compared with single-sorption systems, coexistence of explosives or cationic metals resulted in decreased sorption of each explosive to biochar, suggesting that sorption of nitro explosives and cationic metals to electron-rich portions in biochar was competitive. Our results suggest that ?-? electron donor acceptor interactions are main sorption mechanisms and that changing various conditions can enhance or reduce the sorption of nitro explosives to biochar. PMID:26024263

  19. RECIPES FOR WRITING ALGORITHMS FOR ATMOSPHERIC CORRECTIONS AND TEMPERATURE/EMISSIVITY SEPARATIONS IN THE THERMAL REGIME FOR A MULTI-SPECTRAL SENSOR

    SciTech Connect

    C. BOREL; W. CLODIUS

    2001-04-01

    This paper discusses the algorithms created for the Multi-spectral Thermal Imager (MTI) to retrieve temperatures and emissivities. Recipes to create the physics based water temperature retrieval, emissivity of water surfaces are described. A simple radiative transfer model for multi-spectral sensors is developed. A method to create look-up-tables and the criterion of finding the optimum water temperature are covered. Practical aspects such as conversion from band-averaged radiances to brightness temperatures and effects of variations in the spectral response on the atmospheric transmission are discussed. A recipe for a temperature/emissivity separation algorithm when water surfaces are present is given. Results of retrievals of skin water temperatures are compared with in-situ measurements of the bulk water temperature at two locations are shown.

  20. Light, temperature and nutrients as factors in photosynthetic adjustment to elevated carbon dioxide

    SciTech Connect

    Bunce, J.; Lee, D. (Dept. of Agriculture, Beltsville, MD (United States))

    1991-05-01

    It has been noted many times that the short-term stimulation of photosynthesis by elevated carbon dioxide usually observed in C3 plants may not persist in the long-term. Experiments were designed to test the hypotheses that photosynthetic adjustment to elevated carbon dioxide is due to (a) feedback inhibition resulting from excess photosynthate production relative to use, and (b) nutrient deficiency resulting from more rapid growth. Soybeans and sugarbeets were grown in controlled environment chambers at 350 and 700 ppm carbon dioxide, at two temperatures, two levels of photosynthetically active radiation, and with three nutrient regimes in a factorial design. Net carbon dioxide uptake rates of individual leaves from all growth conditions were measured at both 350 and 700 ppm carbon dioxide to assay photosynthetic adjustment to the elevated carbon dioxide. Growth at elevated carbon dioxide reduced rates of photosynthesis measured at standard carbon dioxide levels in both species. Photosynthetic rates measured at 350 ppm were lower on average by 33% in sugarbeet and 23% in soybean after growth at elevated carbon dioxide. Photosynthetic adjustment to elevated carbon dioxide was not greater after growth at 1.0 than 0.5 mmol m{sup {minus}2}s{sup {minus}1} PPFD, was not greater at 20 than 25C growth temperature, and could not be overcome by high rates of nutrient application. These results do not support either the feedback inhibition nor nutrient deficiency hypotheses of photosynthetic adjustment to elevated carbon dioxide. In soybeans, complete photosynthetic adjustment could be induced by a single night at elevated carbon dioxide.

  1. Effects of obstetric factors and storage temperatures on the yield of endothelial colony forming cells from umbilical cord blood.

    PubMed

    Coldwell, Kate E; Lee, Stephanie J; Kean, Jennifer; Khoo, Cheen P; Tsaknakis, Grigorios; Smythe, Jon; Watt, Suzanne M

    2011-09-01

    As umbilical cord blood (UCB) is a rich source of endothelial colony-forming cells (ECFC), our aim was twofold: (1) to examine potential obstetric selection criteria for achieving the highest ECFC yields from UCB units, and (2) to determine whether transient storage temperatures of fresh UCB and cryopreservation of UCB units affected ECFC yield and function. ECFC quality was assessed before and after cryopreservation by their clonogenic proliferative potential. Of the 20 factors examined, placental weight was the only statistically significant obstetric factor that predicted ECFC frequency in UCB. Studies on the effects of storage revealed that transient storage of fresh UCB at 4°C reduced ECFC yield compared with storage at 22°C, while cryopreservation of UCB MNCs significantly reduced ECFC recoveries. To our knowledge, this is the first demonstration that placental weight and temperature of storage prior to processing or culture have significant effects on ECFC frequency in UCB. Our studies further support the evidence that cryopreservation of UCB MNCs compromises ECFC recovery. PMID:21720855

  2. Factors affecting the wettability of different surface materials with vegetable oil at high temperatures and its relation to cleanability

    NASA Astrophysics Data System (ADS)

    Ashokkumar, Saranya; Adler-Nissen, Jens; Møller, Per

    2012-12-01

    The main aim of the work was to investigate the wettability of different surface materials with vegetable oil (olive oil) over the temperature range of 25-200 °C to understand the differences in cleanability of different surfaces exposed to high temperatures in food processes. The different surface materials investigated include stainless steel (reference), PTFE (polytetrafluoroethylene), silicone, quasicrystalline (Al, Fe, Cr) and ceramic coatings: zirconium oxide (ZrO2), zirconium nitride (ZrN) and titanium aluminum nitride (TiAlN). The ceramic coatings were deposited on stainless steel with two different levels of roughness. The cosine of the contact angle of olive oil on different surface materials rises linearly with increasing temperature. Among the materials analyzed, polymers (PTFE, silicone) gave the lowest cos ? values. Studies of the effect of roughness and surface flaws on wettability revealed that the cos ? values increases with increasing roughness and surface flaws. Correlation analysis indicates that the measured contact angle values gave useful information for grouping easy-clean polymer materials from the other materials; for the latter group, there is no direct relation between contact angle and cleanability. In addition to surface wettability with oil many other factors such as roughness and surface defects play an essential role in determining their cleanability.

  3. Estradiol and Incubation Temperature Modulate Regulation of Steroidogenic Factor 1 in the Developing Gonad of the Red-Eared Slider Turtle

    Microsoft Academic Search

    ALICE FLEMING; DAVID CREWS

    2010-01-01

    Red-eared slider turtles are genetically bipotential for sex deter- mination, with incubation temperature of the egg determining go- nadal sex. At higher incubation temperatures, females are produced, possibly due to increased biosynthesis of estrogen. Exogenous estro- gen causes the formation of ovaries, and prevention of estrogen bio- synthesis results in the development of testes. In mammals, steroi- dogenic factor 1

  4. Temperature-related risk factors associated with the colonization of broiler-chicken flocks with Campylobacter spp. in Iceland, 2001-2004

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to identify temperature-related risk factors associated with the colonization of broiler-chicken flocks with Campylobacter spp. in Iceland, with an underlying assumption that at minimum ambient temperatures, flies (Musca domestica) play a role in the epidemiology and seasonality of...

  5. THE DETERMINATION OF THE FREQUENCY FACTOR AND THE TRAP DEPTH FROM THE TEMPERATURE DEPENDENCE OF THE ELECTROLUMINESCENCE OF ZnS PHOSPHORS

    Microsoft Academic Search

    D. Hahn; W. Kernchen

    1963-01-01

    The temperature dependence of the a-c electroluminescence of ZnS-; phosphors showed characteristic features which are closely related to the ; energetic distribution of traps. Measurements over a wide range of exciting ; field frequencies were used to determine frequency factors and trap depths with ; high accuracy. The order of magnitude of the obtained frequency factors agreed ; with theoretical

  6. Soil moisture surpasses elevated CO 2 and temperature as a control on soil carbon dynamics in a multi-factor climate change experiment

    Microsoft Academic Search

    Charles T. Garten Jr; Aimée T. Classen; Richard J. Norby

    2009-01-01

    Some single-factor experiments suggest that elevated CO2 concentrations can increase soil carbon, but few experiments have examined the effects of interacting environmental factors\\u000a on soil carbon dynamics. We undertook studies of soil carbon and nitrogen in a multi-factor (CO2 × temperature × soil moisture) climate change experiment on a constructed old-field ecosystem. After four growing seasons,\\u000a elevated CO2 had no

  7. Stable isotope composition in Daphnia is modulated by growth, temperature, and toxic exposure: implications for trophic magnification factor assessment.

    PubMed

    Ek, Caroline; Karlson, Agnes M L; Hansson, Sture; Garbaras, Andrius; Gorokhova, Elena

    2015-06-01

    The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on ?(15)N and ?(13)C values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. The cladoceran Daphnia magna was used in two experiments that were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative effect of growth rate and a positive effect of temperature on the consumer-diet discrimination factor for ?(15)N and ?(13)C, with no effects on the C:N ratio (Experiment 1). In lindane-exposed daphnids, a significant growth inhibition was observed, with concomitant increase in metabolic costs and significantly elevated size-specific ?(15)N and ?(13)C values. Moreover, a significantly higher incorporation of carbon relative to nitrogen, yet a concomitant decrease in C:N ratio was observed in the exposed animals. Together, these results have methodological implications for determining trophic positions and TMF in polluted environments, where elevated ?(15)N values would translate into overestimated trophic positions and underestimated TMF. Furthermore, altered ?(13)C values may lead to erroneous food-chain assignment of the consumer in question. PMID:25893846

  8. A 320fs-RMS-jitter and 300kHz-BW all-digital fractional-N PLL with self-corrected TDC and fast temperature tacking loop for WiMax\\/WLAN 11n

    Microsoft Academic Search

    Hsiang-Hui Chang; Chia-Huang Fu; Monty Chiu

    2009-01-01

    This paper presents a 3.9-to-5.39GHz all-digital fractional-N PLL for WiMax\\/WLAN 11n application. The ADPLL uses a self-corrected TDC to achieve meta-stable-error-free operation, wide dynamic range and high timing resolution in a small chip area. The rms jitter from 1kHz to 40MHz is 320fs at 4.51GHz while the calibrated bandwidth is 300KHz. With aid of the fast temperature tracking loop, the

  9. A Sporulation Factor Is Involved in the Morphological Change of Clostridium perfringens Biofilms in Response to Temperature

    PubMed Central

    Obana, Nozomu; Nakamura, Kouji

    2014-01-01

    Biofilm formation has been associated with bacterial pathogenesis, such as nosocomial and chronic infections, as the resistance of biofilms to environmental stresses has increased. Clostridium perfringens is a Gram-positive spore-forming anaerobic pathogen. This organism survives antibiotic treatment through the formation of biofilms or spores, but the environmental and regulatory factors involved in the biofilm formation remain unclear. Here, we observed that temperature regulates C. perfringens biofilm morphology. At 37°C, C. perfringens adhered to the substrate surface and formed a flat, thin biofilm, herein referred to as adhered biofilm. However, at 25°C, this bacterium did not adhere and produced a threadlike extracellular matrix, forming a viscous, thick biofilm, herein referred to as pellicle biofilm. Pellicle biofilm formation requires the sporulation master regulator, Spo0A, and the toxin regulator, CtrAB, and is enhanced in the absence of the global repressor, AbrB. These transcriptional regulator genes are regulated by each other and temperature. Adhered-biofilm formation requires AbrB and pilA2, which encodes a component of type IV pili (TFP). TFP expression was activated at 37°C and regulated through Spo0A, AbrB, and CtrAB. These results indicate that the morphology of C. perfringens biofilm is dependent on temperature through the differential production of extracellular matrix and the activity of TFP. Moreover, pellicle biofilm formation is involved in sporulation and toxin production. Here, we demonstrated that clostridial biofilm formation is closely associated with sporulation and that the morphological change of the biofilms could play an important role in the pathogenesis of this organism. PMID:24509316

  10. The iron- and temperature-regulated haemolysin YhlA is a virulence factor of Yersinia ruckeri.

    PubMed

    Fernández, Lucía; Prieto, Miguel; Guijarro, José A

    2007-02-01

    Yersinia ruckeri causes the enteric redmouth disease or yersiniosis, an important systemic fish infection. In an attempt to dissect the virulence mechanisms of this bacterium, a gene encoding a putative protein involved in the secretion/activation of a haemolysin (yhlB), which had been previously identified by in vivo expression technology, was further analysed. The gene yhlB precedes another ORF (yhlA) encoding a Serratia-type haemolysin. Other toxins belonging to this group have been identified in genomic analyses of human-pathogenic yersiniae, although their role and importance in pathogenicity have not been defined yet. In spite of its being an in vivo-induced gene, the expression of yhlA can be induced under certain in vitro conditions similar to those encountered in the host, as deduced from the results obtained by using a yhlB : : lacZY fusion. Thus, higher levels of expression were obtained at 18 degrees C, the temperature of occurrence of disease outbreaks, than at 28 degrees C, the optimal growth temperature. The expression of the haemolysin also increased under iron-starvation conditions. This confirmed the decisive role of iron and temperature as environmental cues that regulate and coordinate the expression of genes encoding extracellular factors involved in the virulence of Y. ruckeri. LD(50) and cell culture experiments, using yhlB and yhlA insertional mutant strains, demonstrated the participation of the haemolysin in the virulence of Y. ruckeri and also its cytolytic properties against the BF-2 fish cell line. Finally, a screening for the production of haemolytic activity and the presence of yhlB and yhlA genes in 12 Y. ruckeri strains proved once more the genetic homogeneity of this species, since all possessed both haemolytic activity and the yhlB and yhlA genes. PMID:17259619

  11. Metabolic fingerprinting of gilthead seabream (Sparus aurata) liver to track interactions between dietary factors and seasonal temperature variations.

    PubMed

    Silva, Tomé S; da Costa, Ana M R; Conceição, Luís E C; Dias, Jorge P; Rodrigues, Pedro M L; Richard, Nadège

    2014-01-01

    Farmed gilthead seabream is sometimes affected by a metabolic syndrome, known as the "winter disease", which has a significant economic impact in the Mediterranean region. It is caused, among other factors, by the thermal variations that occur during colder months and there are signs that an improved nutritional status can mitigate the effects of this thermal stress. For this reason, a trial was undertaken where we assessed the effect of two different diets on gilthead seabream physiology and nutritional state, through metabolic fingerprinting of hepatic tissue. For this trial, four groups of 25 adult gilthead seabream were reared for 8 months, being fed either with a control diet (CTRL, low-cost commercial formulation) or with a diet called "Winter Feed" (WF, high-cost improved formulation). Fish were sampled at two time-points (at the end of winter and at the end of spring), with liver tissue being taken for FT-IR spectroscopy. Results have shown that seasonal temperature variations constitute a metabolic challenge for gilthead seabream, with hepatic carbohydrate stores being consumed over the course of the inter-sampling period. Regarding the WF diet, results point towards a positive effect in terms of performance and improved nutritional status. This diet seems to have a mitigating effect on the deleterious impact of thermal shifts, confirming the hypothesis that nutritional factors can affect the capacity of gilthead seabream to cope with seasonal thermal variations and possibly contribute to prevent the onset of "winter disease". PMID:25210655

  12. Metabolic fingerprinting of gilthead seabream (Sparus aurata) liver to track interactions between dietary factors and seasonal temperature variations

    PubMed Central

    da Costa, Ana M.R.; Conceição, Luís E.C.; Dias, Jorge P.; Rodrigues, Pedro M.L.; Richard, Nadège

    2014-01-01

    Farmed gilthead seabream is sometimes affected by a metabolic syndrome, known as the “winter disease”, which has a significant economic impact in the Mediterranean region. It is caused, among other factors, by the thermal variations that occur during colder months and there are signs that an improved nutritional status can mitigate the effects of this thermal stress. For this reason, a trial was undertaken where we assessed the effect of two different diets on gilthead seabream physiology and nutritional state, through metabolic fingerprinting of hepatic tissue. For this trial, four groups of 25 adult gilthead seabream were reared for 8 months, being fed either with a control diet (CTRL, low-cost commercial formulation) or with a diet called “Winter Feed” (WF, high-cost improved formulation). Fish were sampled at two time-points (at the end of winter and at the end of spring), with liver tissue being taken for FT-IR spectroscopy. Results have shown that seasonal temperature variations constitute a metabolic challenge for gilthead seabream, with hepatic carbohydrate stores being consumed over the course of the inter-sampling period. Regarding the WF diet, results point towards a positive effect in terms of performance and improved nutritional status. This diet seems to have a mitigating effect on the deleterious impact of thermal shifts, confirming the hypothesis that nutritional factors can affect the capacity of gilthead seabream to cope with seasonal thermal variations and possibly contribute to prevent the onset of “winter disease”. PMID:25210655

  13. Curvature-correction-based time-domain CMOS smart temperature sensor with an inaccuracy of -0.8?°C-1.2?°C after one-point calibration from -40?°C to 120?°C.

    PubMed

    Chen, Chun-Chi; Lin, Shih-Hao; Lin, Yi

    2014-06-01

    This paper proposes a time-domain CMOS smart temperature sensor featuring on-chip curvature correction and one-point calibration support for thermal management systems. Time-domain inverter-based temperature sensors, which exhibit the advantages of low power and low cost, have been proposed for on-chip thermal monitoring. However, the curvature is large for the thermal transfer curve, which substantially affects the accuracy as the temperature range increases. Another problem is that the inverter is sensitive to process variations, resulting in difficulty for the sensors to achieve an acceptable accuracy for one-point calibration. To overcome these two problems, a temperature-dependent oscillator with curvature correction is proposed to increase the linearity of the oscillatory width, thereby resolving the drawback caused by a costly off-chip second-order master curve fitting. For one-point calibration support, an adjustable-gain time amplifier was adopted to eliminate the effect of process variations, with the assistance of a calibration circuit. The proposed circuit occupied a small area of 0.073 mm(2) and was fabricated in a TSMC CMOS 0.35-?m 2P4M digital process. The linearization of the oscillator and the effect cancellation of process variations enabled the sensor, which featured a fixed resolution of 0.049?°C/LSB, to achieve an optimal inaccuracy of -0.8?°C to 1.2?°C after one-point calibration of 12 test chips from -40?°C to 120?°C. The power consumption was 35 ?W at a sample rate of 10 samples/s. PMID:24985845

  14. Positive matrix factorization of a 32-month series of daily PM2.5 speciation data with incorporation of temperature stratification

    NASA Astrophysics Data System (ADS)

    Xie, Mingjie; Piedrahita, Ricardo; Dutton, Steven J.; Milford, Jana B.; Hemann, Joshua G.; Peel, Jennifer L.; Miller, Shelly L.; Kim, Sun-Young; Vedal, Sverre; Sheppard, Lianne; Hannigan, Michael P.

    2013-02-01

    This study presents source apportionment results for PM2.5 from applying positive matrix factorization (PMF) to a 32-month series of daily PM2.5 compositional data from Denver, CO, including concentrations of sulfate, nitrate, bulk elemental carbon (EC) and organic carbon (OC), and 51 organic molecular markers (OMMs). An optimum 8-factor solution was determined primarily based on the interpretability of the PMF results and rate of matching factors from bootstrapped PMF solutions with those from the base case solution. These eight factors were identified as inorganic ion, n-alkane, EC/sterane, light n-alkane/polycyclic aromatic hydrocarbon (PAH), medium alkane/alkanoic acid, PAH, winter/methoxyphenol and summer/odd n-alkane. The inorganic ion factor dominated the reconstructed PM2.5 mass (sulfate + nitrate + EC + OC) in cold periods (daily average temperature <10 °C; 43.7% of reconstructed PM2.5 mass) whereas the summer/odd n-alkane factor dominated in hot periods (>20 °C; 53.1%). The two factors had comparable relative contributions of 26.5% and 27.1% in warm periods with temperatures between 10 °C and 20 °C. Each of the seven factors resolved in a previous study (Dutton et al., 2010b) using a 1-year data set from the same location matches one factor from the current work based on comparing factor profiles. Six out of the seven matched pairs of factors are linked to similar source classes as suggested by the strong correlations between factor contributions (r = 0.89-0.98). Temperature-stratified source apportionment was conducted for three subsets of the data in the current study, corresponding to the cold, warm and hot periods mentioned above. The cold period (7-factor) solution exhibited a similar distribution of reconstructed PM2.5 mass as the full data set solution. The factor contributions of the warm period (7-factor) solution were well correlated with those from the full data set solution (r = 0.76-0.99). However, the reconstructed PM2.5 mass was distributed more to inorganic ion, n-alkane and medium alkane/alkanoic acid factors in the warm period solution than in the full data set solution. For the hot period (6-factor) solution, PM2.5 mass distribution was quite different from that of the full data set solution, as illustrated by regression slopes as low as 0.2 and as high as 4.8 of each matched pair of factors across the two solutions.

  15. Quantum field theory of dilute homogeneous Bose-Fermi mixtures at zero temperature: General formalism and beyond mean-field corrections

    Microsoft Academic Search

    Alexander P. Albus; Simon A. Gardiner; Fabrizio Illuminati; Martin Wilkens

    2002-01-01

    We consider a dilute homogeneous mixture of bosons and spin-polarized\\u000afermions at zero temperature. We first construct the formal scheme for carrying\\u000aout systematic perturbation theory in terms of single particle Green's\\u000afunctions. We introduce a new relevant object, the renormalized boson-fermion\\u000aT-matrix which we determine to second order in the boson-fermion s-wave\\u000ascattering length. We also discuss how to

  16. A Correction.

    PubMed

    Darrow, K K

    1946-01-18

    Please correct a detail on page 17 of your issue of 4 January. You describe and quote from certain resolutions passed by the Metropolitan Section of the American Physical Society on 9 November; and in the course of your description, you unluckily speak of the position of the "Society" rather than that of the Section. Now, the fact is that fewer than five per cent of the members of the Society were present at that meeting, of which no one had been notified in advance except the members living in and near New York and a few others. The resolutions cannot therefore be taken as an expression of the' Society, even though many-myself included-think that a majority of the Society agree with them. PMID:17732768

  17. Continuous and pulsed room temperature lasing behaviour at 1.55 ?m on high quality factor photonic crystal microcavities

    NASA Astrophysics Data System (ADS)

    Postigo, P. A.; Martínez, L. J.; Alén, B.; Prieto, I.; Fuster, D.; González, Y.; González, L.; Dotor, M. L.; Muñoz, L. E.; Kaldirim, M.

    2010-08-01

    In this work we show room temperature continuous (CW) lasing at 1.5 ?m in photonic crystal microcavities with a single layer of self-assembled quantum wires (QWRs). Low threshold values in the range of 1-20 ?W (depending on the excitation type, pulsed or CW) have been measured, along high quality factors exceeding Q=55000 using L7-type photonic crystal microcavities. Solid-source molecular beam epitaxy has been used for the synthesis of the InP/InAs epitaxial material comprising a single layer of InAs QWRs. The main axis of the cavity is always parallel to the QWRs, which are more than 1ìm in length along the [1-10] direction. No lasing has been obtained for L7 cavities with axis parallel to the [110] (i.e., perpendicular to the direction of the QWRs), showing the strong one-dimensional character of the QWRs inside the photonic cavity. Under inhomogeneous pulsed excitation the lasing spectra show asymmetric lineshapes and peak splittings first in the ?eV and later in the meV ranges as the excitation power is increased.

  18. The efficiency calibration and development of environmental correction factors for an in situ high-resolution gamma spectroscopy well logging system

    SciTech Connect

    Giles, J.R.

    1996-05-01

    A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. Absolute efficiency calibration of the GSLS was performed using simple cylindrical borehole geometry. The calibration source incorporated naturally occurring radioactive material (NORM) that emitted photons ranging from 186-keV to 2,614-keV. More complex borehole geometries were modeled using commercially available shielding software. A linear relationship was found between increasing source thickness and relative photon fluence rates at the detector. Examination of varying porosity and moisture content showed that as porosity increases, relative photon fluence rates increase linearly for all energies. Attenuation effects due to iron, water, PVC, and concrete cylindrical shields were found to agree with previous studies. Regression analyses produced energy-dependent equations for efficiency corrections applicable to spectral gamma-ray well logs collected under non-standard borehole conditions.

  19. Radiosondes Corrected for Inaccuracy in RH Measurements

    SciTech Connect

    Miloshevich, Larry

    2008-01-15

    Corrections for inaccuracy in Vaisala radiosonde RH measurements have been applied to ARM SGP radiosonde soundings. The magnitude of the corrections can vary considerably between soundings. The radiosonde measurement accuracy, and therefore the correction magnitude, is a function of atmospheric conditions, mainly T, RH, and dRH/dt (humidity gradient). The corrections are also very sensitive to the RH sensor type, and there are 3 Vaisala sensor types represented in this dataset (RS80-H, RS90, and RS92). Depending on the sensor type and the radiosonde production date, one or more of the following three corrections were applied to the RH data: Temperature-Dependence correction (TD), Contamination-Dry Bias correction (C), Time Lag correction (TL). The estimated absolute accuracy of NIGHTTIME corrected and uncorrected Vaisala RH measurements, as determined by comparison to simultaneous reference-quality measurements from Holger Voemel's (CU/CIRES) cryogenic frostpoint hygrometer (CFH), is given by Miloshevich et al. (2006).

  20. Radiosondes Corrected for Inaccuracy in RH Measurements

    DOE Data Explorer

    Miloshevich, Larry

    Corrections for inaccuracy in Vaisala radiosonde RH measurements have been applied to ARM SGP radiosonde soundings. The magnitude of the corrections can vary considerably between soundings. The radiosonde measurement accuracy, and therefore the correction magnitude, is a function of atmospheric conditions, mainly T, RH, and dRH/dt (humidity gradient). The corrections are also very sensitive to the RH sensor type, and there are 3 Vaisala sensor types represented in this dataset (RS80-H, RS90, and RS92). Depending on the sensor type and the radiosonde production date, one or more of the following three corrections were applied to the RH data: Temperature-Dependence correction (TD), Contamination-Dry Bias correction (C), Time Lag correction (TL). The estimated absolute accuracy of NIGHTTIME corrected and uncorrected Vaisala RH measurements, as determined by comparison to simultaneous reference-quality measurements from Holger Voemel's (CU/CIRES) cryogenic frostpoint hygrometer (CFH), is given by Miloshevich et al. (2006).

  1. Factors Influencing Oral Corrective Feedback Provision in the Spanish Foreign Language Classroom: Investigating Instructor Native/Nonnative Speaker Status, SLA Education, & Teaching Experience

    ERIC Educational Resources Information Center

    Gurzynski-Weiss, Laura

    2010-01-01

    The role of interactional feedback has been a critical area of second language acquisition (SLA) research for decades and while findings suggest interactional feedback can facilitate SLA, the extent of its influence can vary depending on a number of factors, including the native language of those involved in communication. Although studies have…

  2. CTI Correction Code

    NASA Astrophysics Data System (ADS)

    Massey, Richard; Stoughton, Chris; Leauthaud, Alexie; Rhodes, Jason; Koekemoer, Anton; Ellis, Richard; Shaghoulian, Edgar

    2013-07-01

    Charge Transfer Inefficiency (CTI) due to radiation damage above the Earth's atmosphere creates spurious trailing in images from Charge-Coupled Device (CCD) imaging detectors. Radiation damage also creates unrelated warm pixels, which can be used to measure CTI. This code provides pixel-based correction for CTI and has proven effective in Hubble Space Telescope Advanced Camera for Surveys raw images, successfully reducing the CTI trails by a factor of ~30 everywhere in the CCD and at all flux levels. The core is written in java for speed, and a front-end user interface is provided in IDL. The code operates on raw data by returning individual electrons to pixels from which they were unintentionally dragged during readout. Correction takes about 25 minutes per ACS exposure, but is trivially parallelisable to multiple processors.

  3. Factors influencing the body temperature of 3-4 month old infants at home during the day.

    PubMed

    Anderson, E S; Petersen, S A; Wailoo, M P

    1990-12-01

    Continuous recordings of rectal temperature were made from 40 normal infants, aged 3-4 months, at home during two days of normal activities. We found that the rectal temperature of a normal, healthy baby may vary from 36.0 degrees C at night to 37.8 degrees C during active periods of the day. During daytime sleep rectal temperature fell, but to a lesser extent, and for less time than during night time sleeps. Feeds raised the temperature unless the baby slept, when they reduced the rate of fall of temperature. Bottle feeds affected temperature more quickly than breast feeds. The changes in temperature during sleep and after feeds were independent of the room temperature or thermal insulation of clothing and wrapping. PMID:2270937

  4. Temperature anomalies and mortality events in marine communities: insights on factors behind differential mortality impacts in the NW Mediterranean.

    PubMed

    Crisci, Carolina; Bensoussan, Nathaniel; Romano, Jean-Claude; Garrabou, Joaquim

    2011-01-01

    Two large-scale mass mortality events (MMEs) of unprecedented extent and severity affecting rocky benthic communities occurred during the summers of 1999 and 2003 along the coasts of the NW Mediterranean Sea. These mortality outbreaks were associated with positive thermal anomalies. In this study, we performed an analysis of inter-regional and inter-annual differences in temperature (T) conditions associated with MMEs of the red gorgonian Paramuricea clavata by analyzing high resolution T time series (hourly records for 3 to 8 years) from four regions of the NW Mediterranean with differing hydrological conditions and biological impacts. High resolution records allowed a detailed analysis using classical and new descriptors to characterize T anomalies. We were able to determine that the MMEs were triggered by two main types of positive thermal anomalies, with the first type being characterized by short periods (2 to 5 days) with high Mean T reaching more than 27°C in some regions and being associated with high intra-day and intra-period variability, while the second type of anomaly presented long duration (near one month) at warm T (24°C) with low intra-period variability. Inter-regional patterns arose; some regions displayed both types of anomalies, while others exhibited only one type. The results showed that T conditions should be considered as the main factor that explains the observed inter-regional and inter-annual differences in mortality impacts. In explaining these differences, the late timing of T anomalies, in addition to their magnitude was found to be determinant. Finally, by combining thermotolerance experimental data with the maximal T stress conditions observed in the four regions, we were able to determine the differential risk of mass mortality across regions. We conclude that expanding high resolution T series is important for the development of sound management and conservation plans to protect Mediterranean marine biodiversity in the face of climate change. PMID:21931615

  5. An Arabidopsis mutation in translation elongation factor 2 causes superinduction of CBF/DREB1 transcription factor genes but blocks the induction of their downstream targets under low temperatures

    PubMed Central

    Guo, Yan; Xiong, Liming; Ishitani, Manabu; Zhu, Jian-Kang

    2002-01-01

    Low temperature regulates gene expression in bacteria, yeast, and animals as well as in plants. However, the signal transduction cascades mediating the low temperature responses are not well understood in any organism. To identify components in low temperature signaling genetically, we isolated Arabidopsis thaliana mutants in which cold-responsive genes are no longer induced by low temperatures. One of these mutations, los1–1, specifically blocks low temperature-induced transcription of cold-responsive genes. Surprisingly, cold-induced expression of the early response transcriptional activators, C-repeat/dehydration responsive element binding factors (CBF/DREB1s), is enhanced by the los1–1 mutation. The los1–1 mutation also reduces the capacity of plants to develop freezing tolerance but does not impair the vernalization response. Genetic analysis indicated that los1–1 is a recessive mutation in a single nuclear gene. The LOS1 gene encodes a translation elongation factor 2-like protein. Protein labeling studies show that new protein synthesis is blocked in los1–1 mutant plants specifically in the cold. These results reveal a critical role of new protein synthesis in the proper transduction of low temperature signals. Our results also suggest that cold-induced transcription of CBF/DREB1s is feedback inhibited by their gene products or by products of their downstream target genes. PMID:12032361

  6. Factors associated with failure to correct the international normalised ratio following fresh frozen plasma administration among patients treated for warfarin-related major bleeding. An analysis of electronic health records.

    PubMed

    Menzin, J; White, L A; Friedman, M; Nichols, C; Menzin, J; Hoesche, J; Bergman, G E; Jones, C

    2012-04-01

    This study assessed the frequency and factors associated with failure to correct international normalised ratio (INR) in patients administered fresh frozen plasma (FFP) for warfarin-related major bleeding. This retrospective database analysis used electronic health records from an integrated health system. Patients who received FFP between 01/01/2004 and 01/31/2010, and who met the following criteria were selected: major haemorrhage diagnosis the day before to the day after initial FFP administration; INR ?2 on the day before or the day of FFP and another INR result available; warfarin prescription within 90 days. INR correction (defined as INR ?1.3) was evaluated at the last available test up to one day following FFP. A total of 414 patients met selection criteria (mean age 75 years, 53% male, mean Charlson score 2.5). Patients presented with gastrointestinal bleeding (58%), intracranial haemorrhage (38%) and other bleed types (4%). The INR of 67% of patients remained uncorrected at the last available test up to one day following receipt of FFP. In logistic regression analysis, the INR of patients who were older, those with a Charlson score of 4 or greater, and those with non-ICH bleeds (odds ratio vs. intracranial bleeding 0.48; 95% confidence interval 0.31-0.76) were more likely to remain uncorrected within one day following FFP administration. In an alternative definition of correction, (INR ?1.5), 39% of patients' INRs remained uncorrected. For a substantial proportion of patients, the INRs remain inadequately or uncorrected following FFP administration, with estimates varying depending on the INR threshold used. PMID:22318400

  7. Factors influencing the body temperature of 3-4 month old infants at home during the day

    Microsoft Academic Search

    E S Anderson; S A Petersen; M P Wailoo

    1990-01-01

    Continuous recordings of rectal temperature were made from 40 normal infants, aged 3-4 months, at home during two days of normal activities. We found that the rectal temperature of a normal, healthy baby may vary from 36.0 degrees C at night to 37.8 degrees C during active periods of the day. During daytime sleep rectal temperature fell, but to a

  8. Transcription factors and anthocyanin genes related to low-temperature tolerance in rd29A:RdreB1BI transgenic strawberry.

    PubMed

    Gu, Xianbin; Chen, Yahua; Gao, Zhihong; Qiao, Yushan; Wang, Xiuyun

    2015-04-01

    Dehydration-responsive element-binding (DREB) transcription factors play critical roles in plant stress responses and signal transduction. To further understand how DREB regulates genes expression to promote cold-hardiness, Illumina/Solexa sequencing technology was used to compare the transcriptomes of non-transgenic and rd29A:RdreB1BI transgenic strawberry plants exposed to low temperatures. Approximately 3.5 million sequence tags were obtained from non-transgenic (NT) and transgenic (T) strawberry untreated (C) or low-temperature treated (LT) leaf samples. Over 1000 genes were differentially expressed between the NT-C and T-C plants, and also the NT-C and NT-LT, as well as the T-C and T-LT plants. Analysis of the genes up-regulated following low-temperature treatment revealed that the majority are linked to metabolism, biosynthesis, transcription and signal transduction. Uniquely up-regulated transcription factors as well as anthocyanin biosynthetic pathway genes are discussed. Accumulation of anthocyanin in the stolon and the base of the petiole differed between non-treated NT and T plants, and this correlated with gene expression patterns. The differentially expressed genes that encode transcription factors and anthocyanin enzymes may contribute to the cold hardiness of RdreB1BI transgenic strawberry. The transcriptome data provide a valuable resource for further studies of strawberry growth and development and DREB-mediated gene regulation under low-temperature stress. PMID:25686702

  9. Self-Correcting Quantum Computers

    E-print Network

    H. Bombin; R. W. Chhajlany; M. Horodecki; M. A. Martin-Delgado

    2012-09-26

    Is the notion of a quantum computer resilient to thermal noise unphysical? We address this question from a constructive perspective and show that local quantum Hamiltonian models provide self-correcting quantum computers. To this end, we first give a sufficient condition on the connect- edness of excitations for a stabilizer code model to be a self-correcting quantum memory. We then study the two main examples of topological stabilizer codes in arbitrary dimensions and establish their self-correcting capabilities. Also, we address the transversality properties of topological color codes, showing that 6D color codes provide a self-correcting model that allows the transversal and local implementation of a universal set of operations in seven spatial dimensions. Finally, we give a procedure to initialize such quantum memories at finite temperature.

  10. Self-correcting quantum computers

    NASA Astrophysics Data System (ADS)

    Bombin, H.; Chhajlany, R. W.; Horodecki, M.; Martin-Delgado, M. A.

    2013-05-01

    Is the notion of a quantum computer (QC) resilient to thermal noise unphysical? We address this question from a constructive perspective and show that local quantum Hamiltonian models provide self-correcting QCs. To this end, we first give a sufficient condition on the connectedness of excitations for a stabilizer code model to be a self-correcting quantum memory. We then study the two main examples of topological stabilizer codes in arbitrary dimensions and establish their self-correcting capabilities. Also, we address the transversality properties of topological color codes, showing that six-dimensional color codes provide a self-correcting model that allows the transversal and local implementation of a universal set of operations in seven spatial dimensions. Finally, we give a procedure for initializing such quantum memories at finite temperature.

  11. Investigation of the Dominant Factors Influencing the ERA15 Temperature Increments at the Subtropical and Temperate Belts with a Focus over the Eastern Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Alpert, Pinhas; Hirsch-Eshkol, Tali; Baharad, Anat

    2015-04-01

    A Stepwise Multi Regression-based statistics was employed for prioritizing the influence of several factors, both anthropogenic and natural, on the ERA15 temperature increments. The 5 factors which are defined as predictors are;topography, aerosol index (TOMS-AI), atmospheric vertical velocity along with two anthropogenic factors population density and land use changes (LUCI and NDVI trends). The seismic hazard assessment factor was also chosen as the "dummy variable", for validity. Special focus was given to the land use change factor, which was based on two different data sets; HITE data of historical land use/ land cover data and of NDVI trends during 1982- 1991. The Increment Analysis Updates of temperature (IAU(T)), the predicted data, was obtained from the ERA15 (1979-1993) reanalysis. The research consists of both spatial and vertical analyses as well as potential synergies of the selected variables. The spatial geographic analysis is divided into three categories; (a) Coarse region (b) Sub regions analysis and (c) A "small cell" of 4°X4° analysis. It is shown that the following three factors;Topography, TOMS-AI and NDVI are statistically significant (at p<0.05 level) in being the most effective predictors of IAU(T), especially at the 700mb level during March - June. In contrast, the 850mb presents the weakest contribution to IAU(T)probably due to contradictive influence of the various variables at this level. The land use as expressed by the NDVI trends factor, shows a very clear dependency with height, i.e. decreasing, and is one of the most influential factors over the Eastern Mediterranean, which explains up to 20% of the temperature increments in January at 700mb. Moreover, its influence is significant (p<0.05) through all research stages and the different combinations of the multiple regression runs. A major finding not quantified earlier. Reference: T. Hirsch-Eshkol, A. Baharad and P. Alpert, "Investigation of the dominant factors influencing the ERA15 temperature increments at the subtropical and temperate belts with a focus over the Eastern Mediterranean region", Land, 3, 1015-1036; doi:10.3390/land3031015, 2014.

  12. The determination of x-ray temperature factors for aluminium and potassium chloride single crystals using nuclear resonant radiation

    Microsoft Academic Search

    N. M. Butt; D. A. OConnor

    1967-01-01

    The elastic scattering of 14.4 keV gamma rays from 57Fe by single crystals of aluminium and potassium chloride has been measured as a function of Bragg angle and temperature using the Mössbauer effect to distinguish between the elastic and inelastic scattering processes. From the results, using the Debye model, Debye temperatures of 202 ± 5 °K for KCl and 387

  13. Delivery of Full-Length Factor VIII Using a piggyBac Transposon Vector to Correct a Mouse Model of Hemophilia A

    PubMed Central

    Matsui, Hideto; Fujimoto, Naoko; Sasakawa, Noriko; Ohinata, Yasuhide; Shima, Midori; Yamanaka, Shinya; Sugimoto, Mitsuhiko; Hotta, Akitsu

    2014-01-01

    Viral vectors have been used for hemophilia A gene therapy. However, due to its large size, full-length Factor VIII (FVIII) cDNA has not been successfully delivered using conventional viral vectors. Moreover, viral vectors may pose safety risks, e.g., adverse immunological reactions or virus-mediated cytotoxicity. Here, we took advantages of the non-viral vector gene delivery system based on piggyBac DNA transposon to transfer the full-length FVIII cDNA, for the purpose of treating hemophilia A. We tested the efficiency of this new vector system in human 293T cells and iPS cells, and confirmed the expression of the full-length FVIII in culture media using activity-sensitive coagulation assays. Hydrodynamic injection of the piggyBac vectors into hemophilia A mice temporally treated with an immunosuppressant resulted in stable production of circulating FVIII for over 300 days without development of anti-FVIII antibodies. Furthermore, tail-clip assay revealed significant improvement of blood coagulation time in the treated mice.piggyBac transposon vectors can facilitate the long-term expression of therapeutic transgenes in vitro and in vivo. This novel gene transfer strategy should provide safe and efficient delivery of FVIII. PMID:25126862

  14. Effects of lipid and urea extraction on ?15N values of deep-sea sharks and hagfish: Can mathematical correction factors be generated?

    NASA Astrophysics Data System (ADS)

    Churchill, Diana A.; Heithaus, Michael R.; Dean Grubbs, R.

    2015-05-01

    Stable isotope analysis is broadly employed to investigate diverse ecological questions. In order to make appropriate comparisons among multiple taxa, however, it is necessary to standardize values to account for interspecific differences in factors that affect isotopic ratios. For example, varying concentrations of soluble nitrogen compounds, such as urea or trimethylamine oxide, can affect the analysis and interpretation of ?15N values of sharks or hagfish. The goal of this study was to assess the effects of a standard chloroform/methanol extraction on the stable isotope values of muscle tissue obtained from 10 species of sharks and three species of hagfish collected from poorly-known deep-water (>200 m) communities. We detected significant differences in ?15N, %N, and C:N values as a result of extractions in 8 of 10 shark and all three hagfish species. We observed increased ?15N values, but shifts in %N and C:N values were not unidirectional. Mathematical normalizations for ?15N values were successfully created for four shark and two hagfish species. However, they were not successful for two shark species. Therefore, performing extractions of all samples is recommended.

  15. Restudy of surface tension of QGP with one-loop correction in the mean-field potential

    NASA Astrophysics Data System (ADS)

    Singh, S. Somorendro; Gupta, K. K.; Jha, A. K.

    2014-07-01

    Surface tension of quark-gluon plasma (QGP) evolution with one-loop correction in the mean-field potential is studied. First, with the correction, the stable QGP droplet size decreases. Then, the value of surface tension is found to be improved and it approaches to the lattice value of surface tension 0.24Tc3. Moreover, the ratio of the surface tension to the cube of the critical temperature is found to increase the value in comparison to earlier studies without correction factor [R. Ramanathan, K. K. Gupta, A. K. Jha and S. S. Singh, Pram. J. Phys. 68, 757 (2007)].

  16. Evidence for cumulative temperature as an initiating and terminating factor in downstream migratory behavior of Atlantic salmon (Salmo salar) smolts

    USGS Publications Warehouse

    Zydlewski, G.B.; Haro, A.; McCormick, S.D.

    2005-01-01

    Temperature control of Atlantic salmon (Salmo salar) smolt migration was tested using a novel technique allowing nearly continuous monitoring of behavior with complete control over environmental conditions. Parr and presmolts were implanted with passive integrated transponder tags, placed in simulated streams, and monitored for upstream and downstream movements. Beginning 18 April, temperature was increased 1??C every third day (advanced), fourth day (ambient), and tenth day (delayed). Smolt downstream movements were initially low, peaked in mid-May, and subsequently declined under all conditions. Parr downstream movements were significantly lower than those of smolts in all treatments (0.8 ?? 0.5 movement??day-1 versus 26.5 ?? 4.5 movements??day-1, mean ?? SE) and showed no increase. At delayed temperatures, smolts sustained downstream movements through July; those under ambient and advanced conditions ceased activity by mid-June. Initiation and termination of downstream movements occurred at significantly different temperatures but at the same number of degree-days in all treatments. Physiological changes associated with smolting (gill Na+,K +-ATPase activity and plasma thyroxine) were coincident with behavioral changes. This is the first evidence of a behavioral component to the smolt window. We found that temperature experience over time is more relevant to initiation and termination of downstream movement than a temperature threshold. ?? 2005 NRC Canada.

  17. Cloud temperature measurement using rotational Raman lidar

    NASA Astrophysics Data System (ADS)

    Su, Jia; Patrick McCormick, M.; Wu, Yonghua; Lee, Robert B.; Lei, Liqiao; Liu, Zhaoyan; Leavor, Kevin R.

    2013-08-01

    Insufficient suppression of the elastic-scattering signal in the rotational Raman (RR) detection channels can result in a retrieval error particularly when the temperature of a thick cloud is measured using an RR lidar. To solve this problem, a technique is presented to obtain relative transmission factors for the two RR channels' thereby correcting for the influence of residual elastic-signal on the temperature retrieval. The feasibility of this technique is demonstrated by applying the algorithm to the Hampton University (HU) lidar measurements. Intercomparisons of these temperature retrievals from both water-phase and cirrus clouds show good agreement with radiosonde measurements.

  18. Temperature and pressure effects on capacitance probe cryogenic liquid level measurement accuracy

    NASA Technical Reports Server (NTRS)

    Edwards, Lawrence G.; Haberbusch, Mark

    1993-01-01

    The inaccuracies of liquid nitrogen and liquid hydrogen level measurements by use of a coaxial capacitance probe were investigated as a function of fluid temperatures and pressures. Significant liquid level measurement errors were found to occur due to the changes in the fluids dielectric constants which develop over the operating temperature and pressure ranges of the cryogenic storage tanks. The level measurement inaccuracies can be reduced by using fluid dielectric correction factors based on measured fluid temperatures and pressures. The errors in the corrected liquid level measurements were estimated based on the reported calibration errors of the temperature and pressure measurement systems. Experimental liquid nitrogen (LN2) and liquid hydrogen (LH2) level measurements were obtained using the calibrated capacitance probe equations and also by the dielectric constant correction factor method. The liquid levels obtained by the capacitance probe for the two methods were compared with the liquid level estimated from the fluid temperature profiles. Results show that the dielectric constant corrected liquid levels agreed within 0.5 percent of the temperature profile estimated liquid level. The uncorrected dielectric constant capacitance liquid level measurements deviated from the temperature profile level by more than 5 percent. This paper identifies the magnitude of liquid level measurement error that can occur for LN2 and LH2 fluids due to temperature and pressure effects on the dielectric constants over the tank storage conditions from 5 to 40 psia. A method of reducing the level measurement errors by using dielectric constant correction factors based on fluid temperature and pressure measurements is derived. The improved accuracy by use of the correction factors is experimentally verified by comparing liquid levels derived from fluid temperature profiles.

  19. Factors which affect the morphology of AlN particles made by self-propagating high-temperature synthesis (SHS)

    NASA Astrophysics Data System (ADS)

    Fu, R.; Chen, K.; Agathopoulos, S.; Ferreira, J. M. F.

    2006-10-01

    AlN was produced from Al powder via self-propagating high-temperature synthesis (SHS) at 8 and 12 MPa N 2 pressure. In the light of earlier studies, the discussion of the experimental results points out that AlN diluents, the endothermic nature of NH 4F decomposition, and the reducing capability of carbon black are features that can be considered for controlling the combustion temperature as well as the temperature and the prolongation of the after-burning period, which are all determinants of the morphology of the produced AlN particles. The presence of iron as mineralizer resulted in a complex microstructure, probably reflecting a complicate reaction mechanism.

  20. On the importance of appropriate rain-gauge catch correction for hydrological modelling at mid to high latitudes

    NASA Astrophysics Data System (ADS)

    Stisen, S.; Højberg, A. L.; Troldborg, L.; Refsgaard, J. C.; Christensen, B. S. B.; Olsen, M.; Henriksen, H. J.

    2012-03-01

    An existing rain gauge catch correction method addressing solid and liquid precipitation was applied both as monthly mean correction factors based on a 30 yr climatology (standard correction) and as daily correction factors based on daily observations of wind speed and temperature (dynamic correction). The two methods resulted in different winter precipitation rates for the period 1990-2010. The resulting precipitation data sets were evaluated through the comprehensive Danish National Water Resources model (DK-Model) revealing major differences in both model performance and optimized model parameter sets. Simulated stream discharge is improved significantly when introducing a dynamic precipitation correction, whereas the simulated hydraulic heads and multi-annual water balances performed similarly due to recalibration adjusting model parameters to compensate for input biases. The resulting optimized model parameters are much more physically plausible for the model based on dynamic correction of precipitation. A proxy-basin test where calibrated DK-Model parameters were transferred to another region without site specific calibration showed better performance for parameter values based on the dynamic correction. Similarly, the performances of the dynamic correction method were superior when considering two single years with a much dryer and a much wetter winter, respectively, as compared to the winters in the calibration period (differential split-sample tests). We conclude that dynamic precipitation correction should be carried out for studies requiring a sound dynamic description of hydrological processes and it is of particular importance when using hydrological models to make predictions for future climates when the snow/rain composition will differ from the past climate. This conclusion is expected to be applicable for mid to high latitudes especially in coastal climates where winter precipitation type (solid/liquid) fluctuate significantly causing climatological mean correction factors to be inadequate.

  1. Model for correcting global solar irradiance measured with rotating shadowband radiometer

    NASA Astrophysics Data System (ADS)

    Xing, Hongyan; Chong, Wei; Sha, Yizhuo; Lv, Wenhua

    2012-04-01

    Global horizontal irradiance (GHI) measured with rotating shadowband radiometer (RSR) is not accurate enough due to thermal sensitivity and nonuniform spectral response of the photovoltaic detector equipped inside. The purpose of this work is to develop a multiple regressive model to correct the errors posed by the temperature and spectrum. The ratio of the reference global horizontal irradiance (RGHI) to the RSR measured GHI is defined as correction factor, based on which, the model is built via device temperature, air mass, and solar zenith angle. Evaluated from various statistical tests such as coefficient of correlation R2, mean bias deviation, root mean square deviation, t-statistic, skewness, and kurtosis, results show that the corrected RSR GHI can be comparable with the high-quality RGHI, which indicates the validity of the model.

  2. Partial atmospheric correction with adaptive optics

    Microsoft Academic Search

    Peter Nisenson; Richard Barakat

    1987-01-01

    Some numerical experiments performed to test the concept of partial atmospheric correction with adaptive optics are described. Simulated one-dimensional atmospheric wave fronts are generated, correction factors are applied to the wave fronts for various spatial scales, and transfer functions, point-spread fucntions, and images are calculated for intercomparison. The results support the thesis that substantial improvement in imaging capabilities could be

  3. Optimal Countrates for Deadtime Corrections

    SciTech Connect

    Walko, D. A.; Arms, D. A.; Dufresne, E. M.; Landahl, E. C.

    2010-08-02

    The high x-ray flux available at synchrotron radiation sources can cause nonlinearities in photon-counting detectors unless deadtime corrections are employed. We compute the uncertainties associated with several common deadtime-correction formulas. At lower countrates, statistical noise dominates the error in the measured countrates; at higher countrates, the dominating factors are saturation of the response and uncertainty in the value of the deadtime parameter. In between, a range of countrates exists in which the signal-to-noise ratio can be optimized for photon-counting experiments.

  4. PREDICTIVE THERMAL INACTIVATION MODEL FOR SALMONELLA SEROTYPES WITH TEMPERATURE, SODIUM LACTATE, NAC1 AND SODIUM PYROPHOSPHATE AS CONTROLLING FACTORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analyses of survival data of an eight strain cocktail of Salmonella spp. in ground beef with different concentrations of salt, sodium pyrophosphate (SPP), and sodium lactate (NaL) obtained after heating at different temperatures (55, 60, 65, and 71.1°C) indicated that heat resistance of Salmonella i...

  5. Experimental determination of mode I stress intensity factors for elevated temperature fretting fatigue of a nickel-based superalloy

    Microsoft Academic Search

    Nathan J Tate

    2008-01-01

    The elevated temperature environment and variable amplitude load history associated with the dovetail notch configuration of the turbine blade root and disk create a critical location for fretting induced crack nucleation. Fretting contact loads induces very large-gradient tensile subsurface stress, acting parallel to the surface. This stress decays rapidly into the depth of the material and possible arrest of initiated

  6. Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature – high purity water

    Microsoft Academic Search

    Masahiko Tachibana; Kazushige Ishida; Yoichi Wada; Ryosuke Shimizu; Nobuyuki Ota; Nobuyoshi Hara

    2012-01-01

    In order to examine the anodic polarization characteristics of typical structural materials of boiling water reactors (BWRs), the anodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in deaerated high purity water at 553 K using the previously reported measurement method which was confirmed suitable for high temperature – high purity water. In order to

  7. Foliage temperature: Effects of environmental factors with implications for plant water stress assessment and the CO2/climate connection

    NASA Astrophysics Data System (ADS)

    Idso, Sherwood B.; Clawson, Kirk L.; Anderson, Michael G.

    1986-11-01

    Throughout the summer and fall of 1985, several day-long sets of foliage temperature measurements were obtained for healthy and potentially transpiring water hyacinth, cotton, and alfalfa plants growing in a sealed and unventilated greenhouse at Phoenix, Arizona, along with concurrent measurements of air temperature, vapor pressure and net radiation, plus, in the case of the water hyacinths, leaf diffusion resistance measurements. Some data for these plants were additionally obtained out of doors under natural conditions, while dead, nontranspiring stands of alfalfa and water hyacinth were also monitored, both out of doors and within the greenhouse. Analyses of the data revealed that plant nonwater-stressed baselines, i.e., plots of foliage-air temperature differential versus air vapor pressure deficit for potentially transpiring vegetation, were (1) curvilinear, as opposed to the straight lines which have so often appeared to be the case with much smaller and restricted data sets, and (2) that these baselines are accurately described by basic theory, utilizing independently measured values of plant foliage and aerodynamic resistances to water vapor transport. These findings lead to some slight adjustments in the procedure for calculating the Idso-Jackson plant water stress index and they suggest that plants can adequately respond to much greater atmospheric demands for evaporation than what has been believed possible in the past. In addition, they demonstrate that the likely net radiation enhancement due to a doubling of the atmospheric carbon dioxide concentration will have little direct effect on vegetation temperatures, but that the antitranspirant effect of atmospheric CO2 enrichment on foliage temperature may be substantial.

  8. Identifying the Most Important Factors Promoting Aflatoxin and Fumonisin Contamination in Maize (Corn): Effects of Temperature and Bt-Status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Background Maize (corn, Zea mays L.) is grown worldwide in both industrialized and developing countries. Maize is unusually susceptible to mycotoxin contamination, with aflatoxin being the most important mycotoxin. Our research program seeks to identify what pre-harvest factors are most important...

  9. Magnesium correction to the NaKCa chemical geothermometer

    USGS Publications Warehouse

    Fournier, R.O.; Potter, R.W., II

    1979-01-01

    Equations and graphs have been devised to correct for the adverse effects of magnesium upon the Na-K-Ca chemical geothermometer. Either the equations or graphs can be used to determine appropriate temperature corrections for given waters with calculated NaKCa temperatures > 70??C and R 50 are probably derived from relatively cool aquifers with temperatures approximately equal to the measured spring temperature, irrespective of much higher calculated Na-K-Ca temperatures. ?? 1979.

  10. Speed of sound in quark gluon plasma with one loop correction in mean field potential

    E-print Network

    S. Somorendro Singh; R. Ramanathan

    2015-05-14

    We study thermodynamic properties and speed of sound in a free en- ergy evolution of quark-gluon plasma (QGP) with one loop correction factor in the mean-field potential. The values of the thermodynamic prop- erties like pressure, entropy and specific heat are calculated for a range of temperatures. The results agree with the recent lattice results. The speed of sound is found to be C2 s = 0.3 independent of parameters used in the loop correction which matches almost with lattice calculations.

  11. Speed of sound in quark gluon plasma with one loop correction in mean field potential

    E-print Network

    Singh, S Somorendro

    2015-01-01

    We study thermodynamic properties and speed of sound in a free en- ergy evolution of quark-gluon plasma (QGP) with one loop correction factor in the mean-field potential. The values of the thermodynamic prop- erties like pressure, entropy and specific heat are calculated for a range of temperatures. The results agree with the recent lattice results. The speed of sound is found to be C2 s = 0.3 independent of parameters used in the loop correction which matches almost with lattice calculations.

  12. A dip-dependent divergence correction

    SciTech Connect

    Fazzari, F.

    1992-07-01

    A divergence correction is conventionally applied to zero-offset data in an effort to preserved amplitude information. The conventional divergence correction compensates for the geometrical spreading of a point source in a horizontally layered medium where velocity varies with depth only. The dip-dependent divergence correction extends the conventional correction for improved amplitude processing of dipping beds. The dip-dependent divergence correction is computed by dynamic ray tracing, and applied to stacked data using a dip decomposition technique. This correction decreases amplitudes relative to the conventional correction for steep dips and late times. In a data example from the Gulf of Mexico, the conventional correction over- amplified the reflection off a salt dome flank by a factor of 1.6. High amplitudes near salt flanks are also associated with the presence of hydrocarbons. Applying the dip-dependent divergence correction ensures that ``bright spots`` are not due to over-amplification of steep dips by the conventional correction. In areas like the Gulf of Mexico, where the velocity function varies primarily with depth, and steep beds are commonplace, the dip-dependent divergence correction is an inexpensive way to improve the amplitude information in seismic images.

  13. A dip-dependent divergence correction

    SciTech Connect

    Fazzari, F.

    1992-01-01

    A divergence correction is conventionally applied to zero-offset data in an effort to preserved amplitude information. The conventional divergence correction compensates for the geometrical spreading of a point source in a horizontally layered medium where velocity varies with depth only. The dip-dependent divergence correction extends the conventional correction for improved amplitude processing of dipping beds. The dip-dependent divergence correction is computed by dynamic ray tracing, and applied to stacked data using a dip decomposition technique. This correction decreases amplitudes relative to the conventional correction for steep dips and late times. In a data example from the Gulf of Mexico, the conventional correction over- amplified the reflection off a salt dome flank by a factor of 1.6. High amplitudes near salt flanks are also associated with the presence of hydrocarbons. Applying the dip-dependent divergence correction ensures that bright spots'' are not due to over-amplification of steep dips by the conventional correction. In areas like the Gulf of Mexico, where the velocity function varies primarily with depth, and steep beds are commonplace, the dip-dependent divergence correction is an inexpensive way to improve the amplitude information in seismic images.

  14. [Effects of abiotic factors (temperature, pH, heavy metals) on activities of glycosidases in invertebrate animals].

    PubMed

    Golovanova, I L

    2011-01-01

    We have established differences in amylolytical activity in the whole organisms of several invertebrate animals (larvae of chironomids Chironomnus plumosus, pond snail Limnaea stagnalis, orb snail Planorbis corneus, faucet snail Bithynia tentaculata, and zebra mussel Dreissena polymorpha)--potential objects of nutrition of fish benthophages under separate and combined actions of temperature (0, 10 or 20 degrees C), pH (5.0, 7.4 or 8.3), and ions of heavy metals (copper, zinc at a concentration of 10 mg/l) in vitro. The strongest inhibitory effect on the amylolytical activity in tissues of the studied animals was produced by a combination of the low temperature, acidic pH values, and the presence of the heavy metal ions. Enzymes of chironomids were more resistant to action of the studied agents as compared with mollusks. PMID:21469336

  15. Elevated air temperature alters an old-field insect community in a multi-factor climate change experiment

    SciTech Connect

    Villalpando, Sean [Appalachian State University; Williams, Ray [ORNL; Norby, Richard J [ORNL

    2009-01-01

    To address how multiple, interacting climate drivers may affect plant-insect community associations, we sampled the insect community from a constructed old-field plant community grown under simultaneous [CO2], temperature, and water manipulation. Insects were identified to morphospecies, assigned to feeding guilds and abundance, richness and evenness quantified. Warming significantly increased Order Thysanoptera abundance and reduced overall morphospecies richness and evenness. Non-metric multidimensional scaling clearly supported the effect of warming on insect community composition. Reductions in richness for herbivores and parasitoids suggest trophic-level effects within the insect community. Analysis of dominant insects demonstrated the effects of warming were limited to a relatively small number of morphospecies. Reported reductions in whole-community foliar N at elevated [CO2] unexpectedly did not result in any effects on herbivores. These results demonstrate climatic warming may alter certain insect communities via effects on insect species most responsive to higher temperature, contributing to a change in community structure.

  16. Effects of abiotic factors (temperature, pH, heavy metals) on activities of glycosidases in invertebrate animals

    Microsoft Academic Search

    I. L. Golovanova

    2011-01-01

    Differences in amylolytical activity have been established in the whole body of some invertebrate animals (larvae of chironomids\\u000a Chironomus plumosus, pond snail Limnaea stagnalis, orb snail Planorbis corneus, faucet snail Bithynia tentaculata, and zebra mussel Dreissena polymorpha-potential objects of nutrition of fish benthophages under separate and combined actions of temperature (0, 10 or 20°C), pH\\u000a (5.0, 7.4 or 8.3), and

  17. Effects of obstetric factors and storage temperatures on the yield of endothelial colony forming cells from umbilical cord blood

    Microsoft Academic Search

    Kate E. ColdwellStephanie; Stephanie J. Lee; Jennifer KeanCheen; Cheen P. Khoo; Grigorios Tsaknakis; Jon Smythe; Suzanne M. Watt

    As umbilical cord blood (UCB) is a rich source of endothelial colony-forming cells (ECFC), our aim was twofold: (1) to examine\\u000a potential obstetric selection criteria for achieving the highest ECFC yields from UCB units, and (2) to determine whether\\u000a transient storage temperatures of fresh UCB and cryopreservation of UCB units affected ECFC yield and function. ECFC quality\\u000a was assessed before

  18. Factors for consideration in the interpretation of the adverse effects of elevated environmental temperatures on reproduction in the male rat

    NASA Astrophysics Data System (ADS)

    Bedrak, E.; Chap, Z.; Fried, K.

    1980-06-01

    Continuous exposure of male rats to an elevated environmental temperature (33 35° C) for 3 weeks led to heat-acclimatized (HA) rats whose serum testosterone concentratrion was significantly lower (P<0.01) than that of control (C) rats (20 22° C). The decrease in the androgen level was independent of major changes in serum FSH and LH concentrations, as well as hypothalamic content of thyrotropin-releasing hormone (THR), gonadotropin-releasing hormone (GnRH) and prostaglandin E2 (PGE2). However, the prostaglandin F2?(PGF2?) content of the hypothalamus of HA rats was significantly lower (P < 0.05) than that of C. The number of receptors for human chorionic gonadotropin (hCG) was significantly lower in testicular tissue of HA rats as compared to C males. Histological examination of the testis disclosed that exposure to heat adversely affected the sperm production and integrity of the Sertoli cells. Activity of enzymes associated with testosterone biosynthesis in testicular tissue of rats incubated at temperatures similar to those prevailing in the scrotum of HA rats resembled the activity of these enzymes observed in HA animals. Catabolism of testosterone was enhanced when kidney and liver of C rats were incubated at temperatures similar to the deep-body temperatures of HA rats, supporting the thesis that acclimatization to heat is coupled, inter alin, with increase androgen catabolism and excretion. It is suggested that the lower reproductive performance of HA rats is associated with several phenomena: a low number of receptors for hCG in the testes, decreased testoster one production rate by the Leydig cells, increased cata bolism and excretion of androgen, and partial atrophy of seminiferous tubules and Sertoli cells. These changes appear to be independent of either alteration in serum gonadotropin concentration or hypothalamic contents of TRH, GnR H and PGE2. The physiological significance in the response of PGF2? awaits further clarification.

  19. 77 FR 72199 - Technical Corrections; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-05

    ...Region I office, correcting authority citations and typographical and spelling errors...that is cited in one of the authority citations in the final rule. DATES: The correction...authority that is cited in the authority citation for part 171 of Title 10 of the...

  20. Boots Corrections Syllabus Page 1 Corrections

    E-print Network

    O'Toole, Alice J.

    and prisons, alternatives to incarceration (e.g., probation and parole), capital punishment, and the public of punishment and treatment. Emphasis will be placed on correctional law, policies, practices, issues) explain the history of corrections and the rationales for punishment 2) discuss the contemporary issues

  1. Comparative gene expression of steroidogenic factor 1 in Chrysemys picta and Apalone mutica turtles with temperature-dependent and genotypic sex determination.

    PubMed

    Valenzuela, Nicole; LeClere, Andrea; Shikano, Takahito

    2006-01-01

    Characterizing the molecular network underlying temperature-dependent (TSD) and genotypic (GSD) sex determination, including patterns across closely related taxa, is crucial to elucidate the still enigmatic evolution of sex determining mechanisms in vertebrates. Here we examined the expression of an important gene for sexual differentiation common to both systems, Sf1, at male- and female-producing temperatures, in TSD (Chrysemys picta) and GSD turtles (Apalone mutica). We tested the hypotheses that Sf1 expression responds to temperature consistently across TSD turtles but is unaffected in GSD turtles, and that this differential expression starts no earlier than the onset of the thermosensitive period (TSP). As expected, Sf1 expression was thermally insensitive in A. mutica (GSD). Although Sf1 exhibited a differential expression by temperature in C. picta, the expression pattern differed from other TSD turtles (Trachemys scripta), perhaps reflecting divergence of the gene regulatory networks underlying sex determination over evolutionary time. Most notably, Sf1 was differentially expressed in C. picta (significantly higher at the male-producing temperature) before the onset of the TSP, implying that in TSD taxa significant thermal effects may occur early in development. This result may reconcile field observations where temperatures experienced prior to the TSP have an effect on sex ratios, thus challenging traditional TSP models. Importantly, the molecular factors that render TSD mechanisms thermosensitive remain unknown, and potential candidates are genes that express differentially before the onset of the TSP (genes shaping or opening the TSP-window rather those acting once the TSP window has opened). Therefore, our findings make Sf1 one such potential candidate. PMID:16925678

  2. Influence of processing parameters and formulation factors on the bioadhesive, temperature stability and drug release properties of hot-melt extruded films containing miconazole.

    PubMed

    Chen, Meiwan; Lu, Jiannan; Deng, Weibin; Singh, Abhilasha; Mohammed, Noorullah Naqvi; Repka, Michael A; Wu, Chuanbin

    2014-06-01

    This study investigated the processing parameters and formulation factors on the bioadhesive properties, temperature stability properties, and drug release properties of miconazole in PolyOx® and Klucel® matrix systems produced by Hot-melt Extrusion (HME) technology. Miconazole incorporated into these matrix systems were found to be stable for 8 months by X-ray diffraction (XRD). The addition of miconazole increased area under the curve (AUC) at contact time intervals of 30 and 60 sec, while the bioadhesion decreased with an increase in processing temperatures. The release profiles suggest that a sustained release of miconazole was observed from all of the tested HME film formulations for approximately 10 h. The release from the optimal HME film extruded at 205°C was found to be significantly different than that extruded at 190°C. Therefore, this matrix system may address the present shortcomings of currently available therapy for oral and pharyngeal candidiasis. PMID:24550099

  3. Statistical Corrections of HIRLAM and HARMONIE Forecasts for Greenland

    NASA Astrophysics Data System (ADS)

    Mahura, Alexander; Petersen, Claus; Amstrup, Bjarne; Sass, Bent

    2015-04-01

    Numerical Weather Prediction (NWP) for northern regions, and especially, in the Arctic is very complex due to multiple factors. Complexity of physical processes and interactions is not so well studied compared to other geographical regions and first of all, because of limited observational network. Model verification results show that forecasts have larger errors compared to other regions of the world. As a possible solution, statistical corrections to forecasts can be applied. Such corrections can be based on analysis of long-term time-series of meteorological observations and forecasts. The developed method is based on using forecasted meteorological parameters (2m air, dew point, and surface temperatures as well as 10m wind speed) and observations covering only a pre-historical period (ranging from 3 to 30 days). The singular value decomposition method is applied for faster calculations. Then, further improvement/adjustment of forecasts is based on generated statistics of forecasted meteorological parameters. For Greenland, DMI operationally runs two NWP models - HIRLAM (HIgh Resolution Limited Area Model) and HARMONIE (Hirlam Aladin Regional/Meso-scale Operational NWP In Europe). The 1st model (HIRLAM-K05, at 5 km horizontal resolution; runs at 00, 06, 12, and 18 UTC) is run over the entire territory of Greenland. The 2nd model (HARMONIE-GLB, at 2.5 km horizontal resolution; runs at 03, 09, 15, and 21 UTC) is run over the southern (most populated) part of Greenland. The operationalized procedure for statistical correction of the air temperature and wind speed forecasts has been implemented for both models outputs covering forecast lengths up to 48 hours. The procedure includes extraction of observational and model forecast data, assigning data to forecast lengths, calculation of statistical correction to selected meteorological parameters, evaluation of model performance (before vs. after correction applied) for current and previous days with decision-making on using corrections by each of synoptical stations, interpolation, visualisation of corrections and final fields, and storage/backup. Results of verifications for Greenland synoptical stations for both (HIRLAM and HARMONIE) models outputs are presented and evaluated, as well as steps based on application of non-parametric statistics towards correction of cloud cover, wind direction and precipitation for NWP operational forecasts are discussed.

  4. Correcting correlation function measurements

    NASA Astrophysics Data System (ADS)

    Ravan, Shantam; Pujahari, Prabhat; Prasad, Sidharth; Pruneau, Claude A.

    2014-02-01

    Correlation functions measured as a function of ?? ,?? have emerged as a powerful tool to study the dynamics of particle production in nuclear collisions at high energy. They are however subject, like any other observables, to instrumental effects which must be properly accounted for to extract meaningful physics results. We compare the merits of several techniques used towards measurement of these correlation functions in nuclear collisions. We discuss and distinguish the effects of finite acceptance, and detection efficiency that may vary with collision parameters such as the position of the event in the detector and the instantaneous luminosity of the beam. We focus in particular on instrumental effects which break the factorization of the particle pair detection efficiency, and describe a technique to recover the robustness of correlation observables. We finally introduce a multidimensional weight method to correct for efficiencies that vary simultaneously with particle pseudo rapidity, azimuthal angle, transverse momentum, and the collision vertex position. The method can be generalized to account for any number of "event variables" that may break the factorability of the pair efficiency.

  5. The platelet-derived growth factor signaling system in snapping turtle embryos, Chelydra serpentina: potential role in temperature-dependent sex determination and testis development.

    PubMed

    Rhen, Turk; Jangula, Adam; Schroeder, Anthony; Woodward-Bosh, Rikki

    2009-05-01

    The platelet-derived growth factor (Pdgf) signaling system is known to play a significant role during embryonic and postnatal development of testes in mammals and birds. In contrast, genes that comprise the Pdgf system in reptiles have never been cloned or studied in any tissue, let alone developing gonads. To explore the potential role of PDGF ligands and their receptors during embryogenesis, we cloned cDNA fragments of Pdgf-A, Pdgf-B, and receptors PdgfR-alpha and PdgfR-beta in the snapping turtle, a reptile with temperature-dependent sex determination (TSD). We then compared gene expression profiles in gonads from embryos incubated at a male-producing temperature to those from embryos at a female-producing temperature, as well as between hatchling testes and ovaries. Expression of Pdgf-B mRNA in embryonic gonads was significantly higher at a male temperature than at a female temperature, but there was no difference between hatchling testes and ovaries. This developmental pattern was reversed for Pdgf-A and PdgfR-alpha mRNA: expression of these genes did not differ in embryos, but diverged in hatchling testes and ovaries. Levels of PdgfR-beta mRNA in embryonic gonads were not affected by temperature and did not differ between testes and ovaries. However, expression of both receptors increased at least an order of magnitude from the embryonic to the post-hatching period. Finally, we characterized expression of these genes in several other embryonic tissues. The brain, heart, and liver displayed unique expression patterns that distinguished these tissues from each other and from intestine, lung, and muscle. Incubation temperature had a significant effect on expression of PdgfR-alpha and PdgfR-beta in the heart but not other tissues. Together, these findings demonstrate that temperature has tissue specific effects on the Pdgf system and suggest that Pdgf signaling is involved in sex determination and the ensuing differentiation of testes in the snapping turtle. PMID:19523392

  6. Coincidence summing corrections applied to volume sources.

    PubMed

    Lépy, Marie-Christine; Ferreux, Laurent; Pierre, Sylvie

    2012-09-01

    The numerical calculation of coincidence summing corrections requires both the total and full-energy peak efficiencies to be included in the corrective factors. Moreover, in the case of volume sources, the coincidence probability depends on the position of the photon emission inside the radioactive sample, thus it is necessary to calculate the coincidence summing corrective factors by integrating the elemental contributions for the entire volume. The software ETNA calculates coincidence summing corrective factors according to a deterministic method, for volume sources, two approaches are included in the software: the "simplified" calculation uses directly the efficiency of the volume source like in the case of point source, and the "complete" calculation performs the volume integration. To assess the difference between these, different geometrical cases are tested for several radionuclides using both methods. PMID:22410298

  7. Temperature dependence of the band emittance for nongray bodies

    NASA Astrophysics Data System (ADS)

    Staaf, Örjan; Ribbing, Carl G.; Andersson, Stefan K.

    1996-11-01

    The general problem of obtaining correct emittance values from broadband IR radiometric measurements on nongray samples is discussed. If the spectral emittance has structure in a band, the emittance, averaged over that band, will be temperature dependent, even if the spectral emittance is insensitive to the temperature change. We point out that a widely used expression, with correction for radiance from the surroundings reflected by the sample, is valid only if the spectral emittance is temperature and wavelength independent, i.e., gray. If the spectral emittance is nongray, the conventional emission factor, as determined by a broadband radiometer, is temperature dependent and the numerical value is significantly different from the averaged band emittance sought. Two algorithms are suggested to extract the correct band-averaged emittance from the temperature-dependent radiometric emission factor obtained with the conventional expression. The algorithms are demonstrated with a step model for the spectral emittance, and it is shown that the agreement with the correct average band emittance is significantly improved.

  8. Factors Affecting Date of Implantation, Parturition, and Den Entry Estimated from Activity and Body Temperature in Free-Ranging Brown Bears

    PubMed Central

    Friebe, Andrea; Evans, Alina L.; Arnemo, Jon M.; Blanc, Stéphane; Brunberg, Sven; Fleissner, Günther; Swenson, Jon E.; Zedrosser, Andreas

    2014-01-01

    Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD?=?12), the mean date of parturition was 26 January (SD?=?12), and the mean duration of the gestation period was 56 days (SD?=?2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human. PMID:24988486

  9. Factors affecting date of implantation, parturition, and den entry estimated from activity and body temperature in free-ranging brown bears.

    PubMed

    Friebe, Andrea; Evans, Alina L; Arnemo, Jon M; Blanc, Stéphane; Brunberg, Sven; Fleissner, Günther; Swenson, Jon E; Zedrosser, Andreas

    2014-01-01

    Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD?=?12), the mean date of parturition was 26 January (SD?=?12), and the mean duration of the gestation period was 56 days (SD?=?2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human. PMID:24988486

  10. Incubation temperature as a modifying factor on survival of Tenebrio molitor reared in selenium-containing media.

    PubMed

    Audas, A; Hogan, G R; Razniak, H

    1995-01-01

    Newly emerged Tenebrio molitor were reared at 4, 25, and 37 degrees C in nutrient media supplemented with sodium selenate (0.0125, 0.0200, 0.0500, and 0.1000%). Ten insects comprised each group. Controls were maintained in unsupplemented medium at the same temperatures as the experimental groups. Survival percentages were determined. Survival curves were estimated at given times postincubation. Controls at 4 and 37 degrees C showed an increased lethality compared to those insects at 25 degrees C. Data indicate that 4 degrees C had a protective effect on survival for insects reared in media containing the three highest concentrations of selenium. For insects at 37 degrees C, killing was striking and equivalent for all groups, irrespective of media supplementation. PMID:7823325

  11. On the relationship factor between the PV module temperature and the solar radiation on it for various BIPV configurations

    SciTech Connect

    Kaplanis, S., E-mail: kaplanis@teipat.gr; Kaplani, E., E-mail: kaplanis@teipat.gr [Renewable Energy Systems Lab., Mechanical Engineering Dept., Technological Educational Institute of Western Greece, Koukouli 26 334, Patra (Greece)

    2014-10-06

    Temperatures of c-Si, pc-Si and a-Si PV modules making part of a roof in a building or hanging outside windows with various inclinations were measured with respect to the Intensity of the solar radiation on them under various environmental conditions. A relationship coefficient f was provided whose values are compared to those from a PV array operating in a free standing mode on a terrace. A theoretical model to predict f was elaborated. According to the analysis, the coefficient f takes higher values for PV modules embedded on a roof compared to the free standing PV array. The wind effect is much stronger for the free standing PV than for any BIPV configuration, either the PV is part of the roof, or placed upon the roof, or is placed outside a window like a shadow hanger. The f coefficient depends on various parameters such as angle of inclination, wind speed and direction, as well as solar radiation. For very low wind speeds the effect of the angle of inclination, ?, of the PV module with respect to the horizontal on PV temperature is clear. As the wind speed increases, the heat transfer from the PV module shifts from natural flow to forced flow and this effect vanishes. The coefficient f values range from almost 0.01 m{sup 2°}C/W for free standing PV arrays at strong wind speeds, v{sub W}>7m/s, up to around 0.05 m{sup 2°}C/W for the case of flexible PV modules which make part of the roof in a BIPV system.

  12. Corrective Action Glossary

    SciTech Connect

    Not Available

    1992-07-01

    The glossary of technical terms was prepared to facilitate the use of the Corrective Action Plan (CAP) issued by OSWER on November 14, 1986. The CAP presents model scopes of work for all phases of a corrective action program, including the RCRA Facility Investigation (RFI), Corrective Measures Study (CMS), Corrective Measures Implementation (CMI), and interim measures. The Corrective Action Glossary includes brief definitions of the technical terms used in the CAP and explains how they are used. In addition, expected ranges (where applicable) are provided. Parameters or terms not discussed in the CAP, but commonly associated with site investigations or remediations are also included.

  13. Factors affecting ion kinetic temperature, number density, and containment time in the NASA Lewis bumpy-torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1977-01-01

    The degree of toroidal symmetry of the plasma, the number of midplane electrode rings, the configuration of electrode rings, and the location of the diagnostic instruments with respect to the electrode rings used to generate the plasma are discussed. Impurities were deliberately introduced into the plasma, and the effects of the impurity fraction on ion kinetic temperature and electron number density were observed. It is concluded that, if necessary precautions are taken, the plasma communicates extremely well along the magnetic field lines and displays a high degree of symmetry from sector to sector for a wide range of electrode ring configurations and operating conditions. Finally, some characteristic data taken under nonoptimized conditions are presented, which include the highest electron number density and the longest particle containment time (1.9 msec) observed. Also, evidence from a paired comparison test is presented which shows that the electric field acting along the minor radius of the toroidal plasma improves the plasma density and the calculated containment time more than an order of magnitude if the electric field points inward, relative to the values observed when it points (and pushes ions) radially outward.

  14. Bellows high temperature cycle life

    SciTech Connect

    Broyles, R.K. [Pathway Bellows, Inc., Oak Ridge, TN (United States)

    1995-11-01

    In most cases, the bellows elements in an expansion joint are separated or insulated from the hot flow stream and have an actual bellows metal temperature (ABMT) that is much lower than the flow stream temperature. However, when the bellows are externally insulated or when the expansion joint is located inside a hot vessel, the ABMT can be very high. For these situations, the effects of temperature on bellows cycle life should be carefully considered. The design equations presented in the Standards of the expansion Joint Manufacturers Association (EJMA), ASME Section 8, Division 1, and ASME B31.3 do not currently provide cycle life equations or temperature correction factors for bellows operating in the creep temperature range. Therefore, a method is proposed which is specifically tailored to bellows for the estimation of high temperature cycle life based upon available test results. Data is also presented which demonstrates the effect of temperatures above and below 800 F on the cycle life of various bellows materials.

  15. Carbon star effective temperatures

    Microsoft Academic Search

    S. T. Ridgway; G. H. Jacoby; R. R. Joyce; D. C. Wells

    1981-01-01

    Possible methods for measuring the effective temperatures of individual carbon stars are discussed. Since calibrations of broad or narrow-band photometric colors is impractical at present, empirical corrections to narrow band color temperatures is the only valid procedure. The effective temperature of the star TW Oph is estimated, based on preliminary reduction of the occultation and associated photometry

  16. Operator Quantum Error Correcting Subsystems for Self-Correcting Quantum Memories

    E-print Network

    Dave Bacon

    2005-07-04

    The most general method for encoding quantum information is not to encode the information into a subspace of a Hilbert space, but to encode information into a subsystem of a Hilbert space. Recently this notion has led to a more general notion of quantum error correction known as operator quantum error correction. In standard quantum error correcting codes, one requires the ability to apply a procedure which exactly reverses on the error correcting subspace any correctable error. In contrast, for operator error correcting subsystems, the correction procedure need not undo the error which has occurred, but instead one must perform correction only modulo the subsystem structure. This does not lead to codes which differ from subspace codes, but does lead to recovery routines which explicitly make use of the subsystem structure. Here we present two examples of such operator error correcting subsystems. These examples are motivated by simple spatially local Hamiltonians on square and cubic lattices. In three dimensions we provide evidence, in the form a simple mean field theory, that our Hamiltonian gives rise to a system which is self-correcting. Such a system will be a natural high-temperature quantum memory, robust to noise without external intervening quantum error correction procedures.

  17. Correcting reflux laparoscopically.

    PubMed

    Poulin, E C; Schlachta, C M; Mamazza, J

    1998-01-01

    Most operations in the abdominal cavity and chest can be performed using minimally invasive techniques. As yet it has not been determined which laparoscopic procedures are preferable to the same operations done through conventional laparotomy. However, most surgeons who have completed the learning curves of these procedures believe that most minimally invasive techniques will be scientifically recognized soon. The evolution, validation and justification of advanced laparoscopic surgical methods seem inevitable. Most believe that the trend towards procedures that minimize or eliminate the trauma of surgery while adhering to accepted surgical principles is irreversible. The functional results of laparoscopic antireflux surgery in the seven years since its inception have been virtually identical to the success curves generated with open fundoplication in past years. Furthermore, overall patient outcomes with laparoscopic procedures have been superior to outcomes with the traditional approach. Success is determined by patient selection and operative technique. Patient evaluation should include esophagogastroduodenoscopy, barium swallow, 24 h pH study and esophageal motility study. Gastric emptying also should be evaluated. Patients who have abnormal propulsion in the esophagus should not receive a complete fundoplication (Nissen) because it adds a factor of obstruction. Dor or Toupet procedures are adequate alternatives. Prokinetic agents, dilation or pyloroplasty are used for pyloric obstruction ranging from little to more severe. Correcting reflux laparoscopically is more difficult in patients with obesity, peptic strictures, paraesophageal hernias, short esophagus, or a history of previous upper abdominal or antireflux surgery. PMID:9773211

  18. Chromaticity Correction for the SSC Collider Rings

    SciTech Connect

    Ritson, David M

    2003-07-11

    The authors address the issue of correcting higher order chromaticities of the collider with one or more low {beta} insertions. The chromaticity contributed by the interaction regions (IRs) depends crucially on the maximum value of {beta} in the two IRs in a cluster, the phase advance between adjacent interaction points (IPs), and the choice of global tune. They propose a correction scheme in which the linear chromaticity is corrected by a global distribution of sextupoles and the second order chromaticity of each IR is corrected by a more local set of sextupoles. Compared to the case where only the linear chromaticity is corrected, this configuration increases the momentum aperture more than three times and also reduces the {beta} beat by this factor. With this scheme, the tune can be chosen to satisfy other constraints and the two IRs in a cluster can be operated independently at different luminosities without affecting the chromatic properties of the ring.

  19. Offset Correction Techniques for Voltage Sense Amplifiers

    Microsoft Academic Search

    S. Groeneveld

    2006-01-01

    This report deals with offset correction techniques for voltage sense amplifiers and is divided\\u000ainto two different parts: 1) mismatch and 2) offset correction techniques. First a literature\\u000astudy is done on the subject mismatch with specially focus on the future. Mismatch of a\\u000atransistor is determined by the mismatch factors ?VT and ?? which are depend strongly on the

  20. National Institute of Corrections

    NSDL National Science Digital Library

    The National Institute of Corrections hosts a wealth of information for anyone in criminal corrections, by "providing federal, state, and local corrections agencies with training, technical assistance, information services, and policy/program development assistance." Their left-hand navigation menu makes it easy to find your way through their site. The Training Services & Resources link allows users to find opportunities for learning, whether one is interested in classroom-based learning, or non-traditional studies via the Internet or other avenues. The Research Center hosts site-developed resources as well as links to other websites relevant to corrections.

  1. Dead-time Corrected Disdrometer Data

    DOE Data Explorer

    Bartholomew, Mary Jane

    Original and dead-time corrected disdrometer results for observations made at SGP and TWP. The correction is based on the technique discussed in Sheppard and Joe, 1994. In addition, these files contain calculated radar reflectivity factor, mean Doppler velocity and attenuation for every measurement for both the original and dead-time corrected data at the following wavelengths: 0.316, 0.856, 3.2, 5, and 10cm (W,K,X,C,S bands). Pavlos Kollias provided the code to do these calculations.

  2. Attenuation correction for small animal PET tomographs

    NASA Astrophysics Data System (ADS)

    Chow, Patrick L.; Rannou, Fernando R.; Chatziioannou, Arion F.

    2005-04-01

    Attenuation correction is one of the important corrections required for quantitative positron emission tomography (PET). This work will compare the quantitative accuracy of attenuation correction using a simple global scale factor with traditional transmission-based methods acquired either with a small animal PET or a small animal x-ray computed tomography (CT) scanner. Two phantoms (one mouse-sized and one rat-sized) and two animal subjects (one mouse and one rat) were scanned in CTI Concorde Microsystem's microPET® Focus™ for emission and transmission data and in ImTek's MicroCAT™ II for transmission data. PET emission image values were calibrated against a scintillation well counter. Results indicate that the scale factor method of attenuation correction places the average measured activity concentration about the expected value, without correcting for the cupping artefact from attenuation. Noise analysis in the phantom studies with the PET-based method shows that noise in the transmission data increases the noise in the corrected emission data. The CT-based method was accurate and delivered low-noise images suitable for both PET data correction and PET tracer localization.

  3. Corrections in spoken dialogue systems

    Microsoft Academic Search

    Marc Swerts; Diane J. Litman; Julia Hirschberg

    2000-01-01

    This study analyzes user corrections of system errors in the TOOT spoken dialogue system. We find that corrections differ from non- corrections prosodically, in ways consistent with hyperar ticulated speech, although many corrections are not hyperarticulated. Yet both are misrecognized more frequently than non-corrections — though no more likely to be rejected by the system. Corrections more distant from the

  4. Comments and Corrections to \\

    Microsoft Academic Search

    Ivan Stojmenovic

    2004-01-01

    The paper by I. Stojmenovic et al. (2002) generated a lot of interest among researchers in ad hoc networks. A number of researchers questioned, through their articles, or directly to the first author, the correctness of the described procedure, and the correctness of the claim that the procedure does not need any communication exchange between nodes, in addition to \\

  5. Interdepartmental Correction of

    E-print Network

    Texas at Austin, University of

    for it to be corrected. Corrections can only be done by the creator of the original document or by the office which owns" in the Action field, a brief explanation in the Summary field, "01" in Format and either the Document ID: -- COVER SHEET -- Document ID: ___________ Action: new Summary: transfer partial shipping charges for sept

  6. Wall interference assessment and corrections

    NASA Technical Reports Server (NTRS)

    Newman, P. A.; Kemp, W. B., Jr.; Garriz, J. A.

    1989-01-01

    Wind tunnel wall interference assessment and correction (WIAC) concepts, applications, and typical results are discussed in terms of several nonlinear transonic codes and one panel method code developed for and being implemented at NASA-Langley. Contrasts between 2-D and 3-D transonic testing factors which affect WIAC procedures are illustrated using airfoil data from the 0.3 m Transonic Cryogenic Tunnel and Pathfinder 1 data from the National Transonic Facility. Initial results from the 3-D WIAC codes are encouraging; research on and implementation of WIAC concepts continue.

  7. QUANTUM STATISTICAL CORRECTIONS TO ASTROPHYSICAL PHOTODISINTEGRATION RATES

    SciTech Connect

    Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Pehlivan, Yamac [Mimar Sinan Fine Arts University Besiktas, Istanbul 34349 (Turkey); Kajino, Toshitaka [National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan); Balantekin, A. B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Kusakabe, Motohiko, E-mail: gmathews@nd.edu, E-mail: yamac@physics.wisc.edu, E-mail: kajino@nao.ac.jp, E-mail: baha@physics.wisc.edu, E-mail: kusakabe@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan)

    2011-01-20

    Tabulated rates for astrophysical photodisintegration reactions make use of Boltzmann statistics for the photons involved as well as the interacting nuclei. Here, we derive analytic corrections for the Planck-spectrum quantum statistics of the photon energy distribution. These corrections can be deduced directly from the detailed balance condition without the assumption of equilibrium as long as the photons are represented by a Planck spectrum. Moreover, we show that these corrections affect not only the photodisintegration rates but also modify the conditions of nuclear statistical equilibrium as represented in the Saha equation. We deduce new analytic corrections to the classical Maxwell-Boltzmann statistics which can easily be added to the reverse reaction rates of existing reaction network tabulations. We show that the effects of quantum statistics, though generally quite small, always tend to speed up photodisintegration rates and are largest for nuclei and environments for which Q/kT {approx} 1. As an illustration, we examine possible effects of these corrections on the r-process, the rp-process, explosive silicon burning, the {gamma}-process, and big bang nucleosynthesis. We find that in most cases one is quite justified in neglecting these corrections. The correction is largest for reactions near the drip line for an r-process with very high neutron density, or an rp-process at high temperature.

  8. On the importance of appropriate precipitation gauge catch correction for hydrological modelling at mid to high latitudes

    NASA Astrophysics Data System (ADS)

    Stisen, S.; Højberg, A. L.; Troldborg, L.; Refsgaard, J. C.; Christensen, B. S. B.; Olsen, M.; Henriksen, H. J.

    2012-11-01

    Precipitation gauge catch correction is often given very little attention in hydrological modelling compared to model parameter calibration. This is critical because significant precipitation biases often make the calibration exercise pointless, especially when supposedly physically-based models are in play. This study addresses the general importance of appropriate precipitation catch correction through a detailed modelling exercise. An existing precipitation gauge catch correction method addressing solid and liquid precipitation is applied, both as national mean monthly correction factors based on a historic 30 yr record and as gridded daily correction factors based on local daily observations of wind speed and temperature. The two methods, named the historic mean monthly (HMM) and the time-space variable (TSV) correction, resulted in different winter precipitation rates for the period 1990-2010. The resulting precipitation datasets were evaluated through the comprehensive Danish National Water Resources model (DK-Model), revealing major differences in both model performance and optimised model parameter sets. Simulated stream discharge is improved significantly when introducing the TSV correction, whereas the simulated hydraulic heads and multi-annual water balances performed similarly due to recalibration adjusting model parameters to compensate for input biases. The resulting optimised model parameters are much more physically plausible for the model based on the TSV correction of precipitation. A proxy-basin test where calibrated DK-Model parameters were transferred to another region without site specific calibration showed better performance for parameter values based on the TSV correction. Similarly, the performances of the TSV correction method were superior when considering two single years with a much dryer and a much wetter winter, respectively, as compared to the winters in the calibration period (differential split-sample tests). We conclude that TSV precipitation correction should be carried out for studies requiring a sound dynamic description of hydrological processes, and it is of particular importance when using hydrological models to make predictions for future climates when the snow/rain composition will differ from the past climate. This conclusion is expected to be applicable for mid to high latitudes, especially in coastal climates where winter precipitation types (solid/liquid) fluctuate significantly, causing climatological mean correction factors to be inadequate.

  9. Atmospheric Refractivity Corrections in Satellite Laser Ranging

    Microsoft Academic Search

    JAMES B. ABSHIRE; CHESTER S. GARDNER

    1985-01-01

    Atmospheric refraction can cause significant errors in satellite laser ranging (SLR) systems. There are two techniques which can be used to correct for these errors. Atmospheric models based upon surface measurements of pressure, temperature, and relative humidity have been shown by ray tracing to be accurate to within a few centimeters at 20° elevation angle. The residual errors in the

  10. 78 FR 55169 - Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-10

    ...United States Government to the Syrian Opposition Coalition (SOC) and the Syrian Opposition's Supreme Military Council (SMC) Correction In Presidential document 2013-09860 beginning on page 24317 in the issue of Wednesday, April 24, 2013,...

  11. Cornell synchrotron tune correction

    SciTech Connect

    Dunnam, C.; Byrd, J.; Meller, R. (Laboratory of Nuclear Studies Wilson Laboratory, Cornell University, Ithaca, N.Y. (USA))

    1991-06-01

    Methods are described for measurement and stabilization of energy dependent transverse tunes observed in the Cornell synchrotron. For this accelerator, operating over an energy range of 0.15 to 5.5 GeV, tune correction is required to compensate the low energy offset contribution of synchrotron magnetic field errors. Without dynamic correction, synchrotron transport losses and beam instability limit injection rates into the CESR collider and may induce long-term damage in the CLEO detector. In the system described, a real-time digitization technique ( MIRABILE'') has been applied for analysis of tune spectra over the energy ramp cycle. FTM (frequency-time magnitude) plots derived from rapidly-digitized time domain data are analyzed to determine appropriate correction waveforms for excitation of vertical and horiozontal correction quadrupoles distributed about the synchrotron ring. A description of the synchrotron tune stabilization system and related operational data are presented.

  12. [Correction of Bechterew kyphosis].

    PubMed

    Böhm, H; Hehne, H J; Zielke, K

    1989-04-01

    The derangement of posture in advanced flexion deformity due to ankylosing spondylitis, as well as operative correction procedures are analysed. The "Dorsal Lordosating Spondylodesis", DLS, according to Zielke is introduced. This method of polysegmental correction and transpedicular fixation via USIS implants allows the recreation of a balanced upright posture by restoration of smooth lumbar lordosis. We present results of 173 patients corrected by DLS. Since the total amount of correction is split into 5-7 osteotomy sites, complication rates are substantially lower than in the monosegmental methods. Besides the gain of body height and immediate pain relief, the restoration of a horizontal axis of vision could be achieved. The latter, for all patients the most important feature, was maintained as up to 5 years follow-up's show. PMID:2734019

  13. Correcting Illumina data.

    PubMed

    Molnar, Michael; Ilie, Lucian

    2014-09-01

    Next-generation sequencing technologies revolutionized the ways in which genetic information is obtained and have opened the door for many essential applications in biomedical sciences. Hundreds of gigabytes of data are being produced, and all applications are affected by the errors in the data. Many programs have been designed to correct these errors, most of them targeting the data produced by the dominant technology of Illumina. We present a thorough comparison of these programs. Both HiSeq and MiSeq types of Illumina data are analyzed, and correcting performance is evaluated as the gain in depth and breadth of coverage, as given by correct reads and k-mers. Time and memory requirements, scalability and parallelism are considered as well. Practical guidelines are provided for the effective use of these tools. We also evaluate the efficiency of the current state-of-the-art programs for correcting Illumina data and provide research directions for further improvement. PMID:25183248

  14. Shift of the short-term temperature mortality relationship by a climate factor - some evidence necessary to take account of in estimating the health effect of global warming

    Microsoft Academic Search

    Yasushi Honda; Masaji Ono; Akihiko Sasaki; Iwao Uchiyama

    1998-01-01

    Several studies have reported a 'V'-shaped relationship between short-term temperature and mortality rates, characterized by mortality rates that are higher when the temperature is extremely low or high than when the temperature is moderate. To quantify the effect of adaptation to a certain climate on this V-shaped short-term temperature-mortality relationship, we studied the prefecture-specific relationship between daily maximum temperature and

  15. Quantum corrections to inflaton and curvaton dynamics

    SciTech Connect

    Markkanen, Tommi [Helsinki Institute of Physics and Department of Physics, University of Helsinki, P.O. Box 64, FI-00014, Helsinki (Finland); Tranberg, Anders, E-mail: tommi.markkanen@helsinki.fi, E-mail: anders.tranberg@nbi.dk [Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen (Denmark)

    2012-11-01

    We compute the fully renormalized one-loop effective action for two interacting and self-interacting scalar fields in FRW space-time. We then derive and solve the quantum corrected equations of motion both for fields that dominate the energy density (such as an inflaton) and fields that do not (such as a subdominant curvaton). In particular, we introduce quantum corrected Friedmann equations that determine the evolution of the scale factor. We find that in general, gravitational corrections are negligible for the field dynamics. For the curvaton-type fields this leaves only the effect of the flat-space Coleman-Weinberg-type effective potential, and we find that these can be significant. For the inflaton case, both the corrections to the potential and the Friedmann equations can lead to behaviour very different from the classical evolution. Even to the point that inflation, although present at tree level, can be absent at one-loop order.

  16. Factors influencing bruises and mortality of broilers during catching, transport, and lairage.

    PubMed

    Nijdam, E; Arens, P; Lambooij, E; Decuypere, E; Stegeman, J A

    2004-09-01

    A multilevel analysis was performed to identify and quantify risk factors associated with mortality and bruises occurring between catching and slaughter of broiler flocks. The effect of each factor in the final model was expressed as an odds ratio (OR). Data included 1,907 Dutch and German broiler flocks slaughtered in 2000 and 2001 at a Dutch processing plant. The mean dead on arrival (DOA) percentage was 0.46. Percentage of bruises was corrected for economic value. The mean corrected bruises percentage was 2.20. Factors associated with corrected bruises percentage were season, moment of transport, and ambient temperature. Unfortunately, these factors are quite difficult to manipulate. Factors associated with DOA percentage were ambient temperature, moment of transport, catching company, breed, flock size, mean BW, mean compartment stocking density, transport time, lairage time, and the interaction term transport time x ambient temperature. The most important factors that influence DOA percentage, and which can be reduced relatively easily, were compartment stocking density (OR = 1.09 for each additional bird in a compartment), transport time (OR = 1.06 for each additional 15 min), and lairage time (OR = 1.03 for each additional 15 min). In particular, reduction of transport and lairage times might have a major influence due to their large variations. Reducing or removing these factors will reduce DOA percentage. Consequently, profitability and animal welfare will increase. PMID:15384914

  17. Thermoelectric corrections to quantum voltage measurement

    NASA Astrophysics Data System (ADS)

    Stafford, Charles; Bergfield, Justin

    2014-03-01

    The voltage measured by a floating probe of a nonequilibrium quantum system is shown to exhibit nontrivial thermoelectric corrections at finite temperature. The voltage probe is modelled as a scanning potentiometer/thermometer that is allowed to equilibrate with a quantum system via local tunnel coupling. Once equilibrated, the net electrical and heat currents flowing into the probe are zero. This generalizes Buettiker's theory of voltage measurement at zero temperature to finite-temperature systems. In a quantum conductor with electrical bias, it is shown that the probe temperature generally differs from ambient temperature due to Peltier cooling/heating within the system, and that the temperature difference can be sizeable for modest bias voltages. Conversely, if the probe is held at ambient temperature, its voltage is shifted from the equilibrated value, leading to a significant error in voltage measurement. However, if there is a large thermal coupling of the probe to the ambient environment, thermal coupling between the probe and system becomes unimportant, and the voltage measurement becomes similar to the process at zero temperature, with negligible thermoelectric corrections. Work supported by U.S. Department of Energy under Award No. DE-SC0006699.

  18. Solar array model corrections from Mars Pathfinder lander data

    SciTech Connect

    Ewell, R.C.; Burger, D.R. [California Inst. of Tech., Pasadena, CA (United States). Jet Propulsion Lab.

    1997-12-31

    The MESUR solar array power model initially assumed values for input variables. After landing early surface variables such as array tilt and azimuth or early environmental variables such as array temperature can be corrected. Correction of later environmental variables such as tau versus time, spectral shift, dust deposition, and UV darkening is dependent upon time, on-board science instruments, and ability to separate effects of variables. Engineering estimates had to be made for additional shadow losses and Voc sensor temperature corrections. Some variations had not been expected such as tau versus time of day, and spectral shift versus time of day. Additions needed to the model are thermal mass of lander petal and correction between Voc sensor and temperature sensor. Conclusions are: the model works well; good battery predictions are difficult; inclusion of Isc and Voc sensors was valuable; and the IMP and MAE science experiments greatly assisted the data analysis and model correction.

  19. P3O-4 SiO2\\/Grooved Al-Electrodes\\/LiTaO3 Structures Having Large Reflection Coefficient, Large Coupling Factor, and Excellent Temperature Characteristics Even with Thick Al Electrode

    Microsoft Academic Search

    Michio Kadota; T. K. Murata

    2006-01-01

    A surface acoustic wave (SAW) substrate for a duplexer such as Personal Communication Service handy phone system in US is required to have a good temperature coefficient of frequency (TCF), an optimum electromechanical coupling factor, and a large reflection coefficient. However, there have been no SAW substrates satisfying all of them. Because the duplexer is composed of resonator-type devices such

  20. Correction of emission spectra in microspectrofluorimetry using a reference lamp: computations.

    PubMed

    Galassi, L

    1992-01-01

    Accurate correction of emission spectra in microspectrofluorimetry, using a reference lamp, may require that a factor for the emissivity of tungsten be introduced. This is only possible provided that the true temperature of the lamp filament is known. A method is given for obtaining the true temperature from the knowledge of the colour temperature. Also, the values of the spectral concentration of the radiance of the black body, either computed according to Planck's equation or taken from available published tables, have to be converted from energetic units to units of quanta since the photomultiplier is linear not to absorbed power but to units of quanta. When the fluorescence spectra to be corrected extend into the far red it is preferable to use a lower temperature (by lowering the supply voltage) than that for which the lamp is certified. It is possible to determine the new temperature (and then the corresponding spectral distribution) by taking a few pairs of measurements at different wavelengths both at the lower voltage and at the voltage for which the lamp is certified and then introducing these values in a non-linear regression soluble on a PC with a curve fitting program. The microscope tungsten halogen lamp can conveniently be used as a reference, thanks to its small size and its steady spectral characteristics. When high accuracy is required, however, the halogen lamp should be calibrated against a certified ribbon filament lamp. PMID:1380859

  1. Solar array model corrections from Mars Pathfinder Lander data

    Microsoft Academic Search

    R. C. Ewell; D. R. Burger

    1997-01-01

    The MESUR solar array power model for the Mars Pathfinder spacecraft initially assumed values for input variables. After landing, early surface variables such as array tilt and azimuth or early environmental variables such as array temperature can be corrected. Correction of later environmental variables such as tau versus time, spectral shift, dust deposition and UV darkening is dependent upon time,

  2. Peteye detection and correction

    NASA Astrophysics Data System (ADS)

    Yen, Jonathan; Luo, Huitao; Tretter, Daniel

    2007-01-01

    Redeyes are caused by the camera flash light reflecting off the retina. Peteyes refer to similar artifacts in the eyes of other mammals caused by camera flash. In this paper we present a peteye removal algorithm for detecting and correcting peteye artifacts in digital images. Peteye removal for animals is significantly more difficult than redeye removal for humans, because peteyes can be any of a variety of colors, and human face detection cannot be used to localize the animal eyes. In many animals, including dogs and cats, the retina has a special reflective layer that can cause a variety of peteye colors, depending on the animal's breed, age, or fur color, etc. This makes the peteye correction more challenging. We have developed a semi-automatic algorithm for peteye removal that can detect peteyes based on the cursor position provided by the user and correct them by neutralizing the colors with glare reduction and glint retention.

  3. Improved environmental corrections for compensated neutron logs

    SciTech Connect

    Galford, J.E.; Flaum, C.; Gilchrist, W.A. Jr.; Soran, P.D.; Gardner, J.S.

    1988-06-01

    The basic openhole responses and environmental correction algorithms for compensated neutron logging (CNL) tools have been updated. The improved processing is based on an extensive set of laboratory formation measurements to which mathematical modeling calculations have been added. In all, the new algorithms include basic responses for the three principal formation matrix types and corrections for seven environmental effects and formation-fluid salinity. A total of 467 laboratory formation measurements have been augmented with 245 data points generated through mathematical modeling. This data base has been used to define more accurately the effects on the tool response of variations in logging conditions from those considered standard in the laboratory. More accurate corrections for the effects of formation pressure, temperature, mudcake, natural or barite mud, and borehole salinity have been defined. Certain other effects depend on more than one parameters. For example, the effect of formation salinity is somewhat matrix-dependent; therefore, the corrections are handled differently for sandstone, limestone, and dolomite. The effect of tool standoff depends on the borehole size; consequently, the standoff correction is larger for larger boreholes. The porosity crossplots and environmental correction charts based on the new algorithms represent a significant evolutionary improvement over previous techniques. They should be an important aid to the use and interpretation of neutron logs.

  4. Target mass corrections revisited

    SciTech Connect

    Steffens, F.M. [NFC-FCBEE-Universidade Presbiteriana Mackenzie, Rua da Consolacao 930, 01302-907, Sao Paulo, SP, Brazil IFT-UNESP, Rua Pamplona 145, 01405-900, Sao Paulo, SP (Brazil); Melnitchouk, W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

    2006-05-15

    We propose a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite Q{sup 2} in the x{yields}1 limit. We illustrate the differences between the new approach and existing prescriptions by considering specific examples for the F{sub 2} and F{sub L} structure functions, and discuss the broader implications of our results, which call into question the notion of universal parton distribution at finite Q{sup 2}.

  5. Target Mass Corrections Revisited

    SciTech Connect

    W. Melnitchouk; F. Steffens

    2006-03-07

    We propose a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite Q{sup 2} in the x {yields} 1 limit. We illustrate the differences between the new approach and existing prescriptions by considering specific examples for the F{sub 2} and F{sub L} structure functions, and discuss the broader implications of our results, which call into question the notion of universal parton distribution at finite Q{sup 2}.

  6. Corrections and clarifications.

    PubMed

    1994-11-11

    The 1994 and 1995 federal science budget appropriations for two of the activities were inadvertently transposed in a table that accompanied the article "Hitting the President's target is mixed blessing for agencies" by Jeffrey Mervis (News & Comment, 14 Oct., p. 211). The correct figures for Defense Department spending on university research are $1.460 billion in 1994 and $1.279 billion in 1995; for research and development at NASA, the correct figures are $9.455 billion in 1994 and $9.824 billion in 1995. PMID:17779924

  7. Refraction corrections for surveying

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1979-01-01

    Optical measurements of range and elevation angle are distorted by the earth's atmosphere. High precision refraction correction equations are presented which are ideally suited for surveying because their inputs are optically measured range and optically measured elevation angle. The outputs are true straight line range and true geometric elevation angle. The 'short distances' used in surveying allow the calculations of true range and true elevation angle to be quickly made using a programmable pocket calculator. Topics covered include the spherical form of Snell's Law; ray path equations; and integrating the equations. Short-, medium-, and long-range refraction corrections are presented in tables.

  8. Experimental Determination of the Recovery Factor and Analytical Solution of the Conical Flow Field for a 20 deg Included Angle Cone at Mach Numbers of 4.6 and 6.0 and Stagnation Temperatures to 2600 degree R

    NASA Technical Reports Server (NTRS)

    Pfyl, Frank A.; Presley, Leroy L.

    1961-01-01

    The local recovery factor was determined experimentally along the surface of a thin-walled 20 deg included angle cone for Mach numbers near 6.0 at stagnation temperatures between 1200 deg R and 2600 deg R. In addition, a similar cone configuration was tested at Mach numbers near 4.5 at stagnation temperatures of approximately 612 deg R. The local Reynolds number based on flow properties at the edge of the boundary layer ranged between 0.1 x 10(exp 4) and 3.5 x 10(exp 4) for tests at temperatures above 1200 deg R and between 6 x 10(exp 4) and 25 x 10(exp 4) for tests at temperatures near 612 deg R. The results indicated, generally, that the recovery factor can be predicted satisfactorily using the square root of the Prandtl number. No conclusion could be made as to the necessity of evaluating the Prandtl number at a reference temperature given by an empirical equation, as opposed to evaluating the Prandtl number at the wall temperature or static temperature of the gas at the cone surface. For the tests at temperatures above 1200 deg R (indicated herein as the tests conducted in the slip-flow region), two definite trends in the recovery data were observed - one of increasing recovery factor with decreasing stagnation pressure, which was associated with slip-flow effects and one of decreasing recovery factor with increasing temperature. The true cause of the latter trend could not be ascertained, but it was shown that this trend was not appreciably altered by the sources of error of the magnitude considered herein. The real-gas equations of state were used to determine accurately the local stream properties at the outer edge of the boundary layer of the cone. Included in the report, therefore, is a general solution for the conical flow of a real gas using the Beattie-Bridgeman equation of state. The largest effect of temperature was seen to be in the terms which were dependent upon the internal energy of the gas. The pressure and hence the pressure drag terms were unaffected.

  9. Corrections to the Hall mobility

    SciTech Connect

    Hong, T.M. (Cavendish Laboratory, Madingley Road, Cambridge (Engand)); Wheatley, J.M. (Superconductivity Research Center, Cambridge University, Madingley Road, Cambridge (England))

    1990-10-01

    We present the solution of the linear transport problem for a charged particle undergoing quantum diffusion {ital a} {ital la} Caldeira-Leggett in a two-dimensional translationally invariant system subject to an external magnetic field. The analysis provides a general framework in which to understand corrections to the classical form of the Hall mobility of an isolated carrier, when the current relaxationtakes an arbitrary form. The Drude forms of the mobilities {sigma}{sup {ital x}{ital x}}({omega}) and {sigma}{sup {ital x}{ital y}}({omega}) are recovered for all relative values of the cyclotron frequency, frictional lifetime {tau}, and driving frequency {omega} as a limiting case of the model, when the upper cutoff on the dissipative bath spectral density is set to infinity. We make a quantitative estimate of the effect of a finite cutoff ({Omega}{sub {ital c}}) on the Hall coefficient. The Hall coefficient decreases in the presence of a finite cutoff; the correction grows as {approximately}{minus}({Omega}{sub {ital c}}{tau}){sup {minus}1} until ({Omega}{sub {ital c}}{tau}){approximately}1. We argue that this effect may account for part of the temperature-dependent Hall coefficient found in cuprate superconductors.

  10. Security of Error Correcting Code for biometric Encryption

    Microsoft Academic Search

    Alex Stoianov

    2010-01-01

    The importance of security of BE systems in relation to an Error Correcting Code (ECC) is emphasized. The security of the BE system proposed in Kanade et al paper “Three Factor Scheme For Biometric-Based Cryptographic Key Regeneration Using Iris” is analyzed. It is shown that the error correcting scheme with zero insertions, which was employed in the paper, can be

  11. Community Correctional Centers. Program Models.

    ERIC Educational Resources Information Center

    Carter, Robert M.; And Others

    Intended to help the correctional administrator make informed choices in planning, implementing, and improving community correctional centers, this program model on community correctional centers contains descriptions of three major program model options and information on how the correctional center should be operated. Components of the Des…

  12. Space charge stopband correction

    SciTech Connect

    Huang, Xiaobiao; /Fermilab /Indiana U.; Lee, S.Y.; /Indiana U.

    2005-09-01

    It is speculated that the space charge effect cause beam emittance growth through the resonant envelope oscillation. Based on this theory, we propose an approach, called space charge stopband correction, to reduce such emittance growth by compensation of the half-integer stopband width of the resonant oscillation. It is illustrated with the Fermilab Booster model.

  13. Consumer protection: Corrective measures

    Microsoft Academic Search

    E. Scott Maynes

    1979-01-01

    The failure of contemporary economies to give consumers “what they really want” manifests itself in a set of “consumer problems” that give rise to the demand for consumer protection. The pivotal problems: monopoly, informationally imperfect markets, consumer dissatisfaction or grievances, the underrepresentation of consumers, disadvantaged consumers. This article deals with the entire spectrum of measures designed to eliminate or correct

  14. Ionospheric Correction Using Tomography

    E-print Network

    Stanford University

    Ionospheric Correction Using Tomography Andrew J. Hansen Todd Walter Per Enge Stanford University to the ight crew within six seconds. The ionosphere is the foremost impedi- ment to satisfying for estimat- ing the ionosphere in real-time. Previous research has established a connection between

  15. Refraction corrections for surveying

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1980-01-01

    Optical measurements of range and elevation angles are distorted by refraction of Earth's atmosphere. Theoretical discussion of effect, along with equations for determining exact range and elevation corrections, is presented in report. Potentially useful in optical site surveying and related applications, analysis is easily programmed on pocket calculator. Input to equation is measured range and measured elevation; output is true range and true elevation.

  16. Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing

    SciTech Connect

    Hawke, J. [FOM Institute DIFFER – Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, 3430 BE Nieuwegein (Netherlands)] [FOM Institute DIFFER – Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, 3430 BE Nieuwegein (Netherlands); Scannell, R.; Maslov, M. [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)] [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Migozzi, J. B. [JBM Optique, 4 Rue du Calvaire Bâtiment 11, 92210 Saint Cloud (France)] [JBM Optique, 4 Rue du Calvaire Bâtiment 11, 92210 Saint Cloud (France); Collaboration: JET-EFDA Contributors

    2013-10-15

    This work isolated the cause of the observed discrepancy between the electron temperature (T{sub e}) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the stray light filters transmission functions due to the variations in the incidence angles of the collected photons impacted plasma measurements. To correct for this identified source of error, correction factors were developed using ray tracing models for the calibration and operational states of the diagnostic. The application of these correction factors resulted in an increase in the observed T{sub e}, resulting in the partial if not complete removal of the observed discrepancy in the measured T{sub e} between the JET core LIDAR TS diagnostic, High Resolution Thomson Scattering, and the Electron Cyclotron Emission diagnostics.

  17. Correction of the Sea State Impact in the L-Band Brightness Temperature by Means of Delay-Doppler Maps of Global Navigation Satellite Signals Reflected Over the Sea Surface

    Microsoft Academic Search

    Juan Fernando Marchan-Hernandez; Nereida Rodriguez-Alvarez; Adriano Camps; Xavier Bosch-Lluis; Isaac Ramos-Perez; Enric Valencia

    2008-01-01

    This paper presents an efficient procedure based on 2-D convolutions to obtain delay-Doppler maps (DDMs) of Global Navigation Satellite Signals reflected (GNSS-R) over the sea surface and collected by a spaceborne receiver. Two DDM-derived observables (area and volume) are proposed to link the sea-state-induced brightness temperature to the measured normalized DDM. Finally, the requirements to use Global Positioning System reflectometry

  18. Quantum gravity corrections to fermions' tunnelling radiation in the Taub-NUT spacetime

    NASA Astrophysics Data System (ADS)

    Zeng, Xiao-Xiong; Chen, Yang

    2015-04-01

    Incorporating effects of quantum gravity into the tunnelling method, we adopt the modified Dirac equation to study the tunnelling radiation of fermions in the Taub-NUT black hole. The corrected Hawking temperature is lower than the original temperature. The correction value is affected by the energy, mass and angular momentum of the emitted fermion. The quantum gravity correction slows down the increase of the temperature, which leads to the remnants left during the evaporation.

  19. Method and system for photoconductive detector signal correction

    DOEpatents

    Carangelo, Robert M. (Glastonbury, CT); Hamblen, David G. (East Hampton, CT); Brouillette, Carl R. (West Hartford, CT)

    1992-08-04

    A corrective factor is applied so as to remove anomalous features from the signal generated by a photoconductive detector, and to thereby render the output signal highly linear with respect to the energy of incident, time-varying radiation. The corrective factor may be applied through the use of either digital electronic data processing means or analog circuitry, or through a combination of those effects.

  20. A Review of Target Mass Corrections

    SciTech Connect

    I. Schienbein; V. Radescu; G. Zeller; M. E. Christy; C. E. Keppel; K. S. McFarland; W. Melnitchouk; F. I. Olness; M. H. Reno; F. Steffens; J.-Y. Yu

    2007-09-06

    With recent advances in the precision of inclusive lepton-nuclear scattering experiments, it has become apparent that comparable improvements are needed in the accuracy of the theoretical analysis tools. In particular, when extracting parton distribution functions in the large-x region, it is crucial to correct the data for effects associated with the nonzero mass of the target. We present here a comprehensive review of these target mass corrections (TMC) to structure functions data, summarizing the relevant formulas for TMCs in electromagnetic and weak processes. We include a full analysis of both hadronic and partonic masses, and trace how these effects appear in the operator product expansion and the factorized parton model formalism, as well as their limitations when applied to data in the x -> 1 limit. We evaluate the numerical effects of TMCs on various structure functions, and compare fits to data with and without these corrections.