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Sample records for air kerma index

  1. Volume computed tomography air kerma index and image quality evaluation in Brazil

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the image quality of 29 computed tomography (CT) scanners in Brazil and to perform estimations of patient dose and image quality of common CT examinations at these equipment. The volume CT air kerma indexes (C VOL) were estimated, using normalised weighted air kerma indexes, supplied by the ImPACT group. The image quality tests were performed using the phantom and accreditation protocol from the American College of Radiology (ACR). The C VOL values for head scans varied between 8.7 and 108 mGy. The Hi-res chest examinations presented C VOL values varying from 0.4 to 32 mGy. For abdominal scans, the estimated C VOL values varied between 4.1 and 94 mGy. This wide variation of air kerma between different centres is related to the scanner type and also to the scanning parameters. The results also showed that the image quality did not attend all ACR CT accreditation requirements. (authors)

  2. Image quality and volume computed tomography air kerma index (Cvol) evaluation in Recife

    International Nuclear Information System (INIS)

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (CVOL) and air kerma length product (PKL,CT) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms (nCW), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the CVOL values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the PKL,CT, from 150 to 750 mGy·cm. The CVOL values for routine chest procedures varied from 3 to 26 mGy and the PKL,CT, between 120 and 460 mGy·cm. In relation to Hi-resolution chest exams, CVOL values were from 1.0 to 2.7 mGy and the PKL,CT values varied between 24 and 67 mGy·cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the ACR requirements, suggesting the need to implement quality assurance programs at the evaluated institutions. (author)

  3. Image quality and volume computed tomography air kerma index (C{sub vol}) evaluation in Recife; Avaliacao da qualidade de imagem e do indice volumetrico de Kerma ar em tomografia computadorizada (C{sub vol}) em Recife

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marcos Ely Almeida

    2008-07-01

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (C{sub VOL}) and air kerma length product (P{sub KL,CT}) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms ({sub n}C{sub W}), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the C{sub VOL} values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the P{sub KL,CT}, from 150 to 750 mGy{center_dot}cm. The C{sub VOL} values for routine chest procedures varied from 3 to 26 mGy and the P{sub KL,CT}, between 120 and 460 mGy{center_dot}cm. In relation to Hi-resolution chest exams, C{sub VOL} values were from 1.0 to 2.7 mGy and the P{sub KL,CT} values varied between 24 and 67 mGy{center_dot}cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the ACR requirements, suggesting the need to implement quality assurance programs at the evaluated institutions. (author)

  4. Air kerma rates measurement in an interventional cardiology suite

    International Nuclear Information System (INIS)

    In Interventional Cardiology (IC), the assessment of the radiation that the physicians are exposed to is extremely important because the irradiation is not uniform and the received doses are substantially high. During the procedure, the radiation control is complex and there are several reasons for the high exposure levels. It is necessary to perform dosimetric assessments in different parts of the physicians' body and in different specific points of the examination room. By analyzing this information it is possible to determine the probable causes and to provide recommendations, aiming at optimizing the radiological protection. This work had the following objectives: to assess the exposition levels at representative points of critical anatomical regions of the physicians' body who perform IC examinations; to provide means to implement personal monitoring procedures; and to make them aware of the radiation risks. Measurements of air kerma rates were performed in 45 points around the examination table, along the room. Such measurements were made in the conditions frequently used in coronary angiography and coronary angioplasties procedures: adult patient phantom; RAO, LAO and AP incidences; fluoro and digital modes; 13cm and 17cm magnification modes; frequencies of 30f/s (fluoro) and 15 f/s (digital); typical field size used during examinations. Data were obtained at the lenses, chest, hands, gonads and knees levels. For AP incidence, the lowest contributions for scattidence, the lowest contributions for scattered radiation and a more homogeneous distribution of radiation were observed. The highest air kerma rates were obtained during digital acquisition mode and for LAO incidence on interventional radiologists, anaesthesists and nurses. The most critical anatomical regions were the knees and gonads. Air kerma rates of about 7,8mGy/h were registered in some places. At physicians' hands position, rates of about 5mGy/h were reached. In several points and levels measured (workload ? 6 examinations/day), this air kerma rates would produce a higher dose than the annual limits. This work shows the need to implement additional protection devices; to elaborate safety guidelines; to train staff on radiological protection, and to implement the use of additional dosemeters attached to critical points. (author)

  5. Status of air kerma and absorbed dose standards in India

    International Nuclear Information System (INIS)

    Full text: The Radiation Safety Systems Division of Bhabha Atomic Research Centre, India maintains Primary and Secondary Standards of various parameters of radiation measurements and provides calibration services to various users of radiation in the country. This is an apex laboratory in India and plays a pivotal role in ensuring accurate radiological measurements. The laboratory coordinates national intercomparisons of radiation measurements to maintain their uniformity and traceability and is linked through various programmes with the other International organizations such as Bureau Internationale des Poids et Mesures (BIPM) Paris, International Atomic Energy Agency (IAEA) Vienna, Asia Pacific Metrology Programme (APMP) Taiwan. It is the recognized Regional Secondary Standards Dosimetry Laboratory (SSDL) of IAEA/WHO (World Health Organisation). This paper brings out the status of various primary and secondary standards for radiological measurements maintained at BARC. 1. Primary Exposure/Air-kerma standard at Co-60 energy (therapy level): The primary standard for exposure/ air-kerma measurements maintained at BARC is a graphite cavity chamber of volume 4.362 cc with an internal diameter of 1.8 cm, internal height of 1.78 cm and wall thickness of 704.3mg/cm2. Correction factors for the difference between electron stopping powers, photon mass energy absorption coefficients of air and graphite wall, correction for recombination, radiation field non-uniformity, stem scatter and polarity effect are applied and the maximum overall uncertainty in the realisation of exposure/air-kerma is around ±1%. This standard has been intercompared with IAEA and BIPM through transfer standard and the agreement in the results are better than ±1%. An intercomparison under the APMP programme is to be held during May, 2002. 2. Primary Exposure/Air-kerma standard at protection and brachytherapy level: A set of three spherical graphite-walled cavity chambers of different air-volumes are maintained as primary standards for protection level and brachytherapy measurements of Ir-192, Cs-137 and Co-60 sources. These chambers are made of high purity reactor-grade graphite of density 1700 kg/m3. The three chambers have different wall thickness, the external diameters of all the chambers being equal. A reference standard in the form of a re-entrant chamber developed at BARC, calibrated against this primary standard was intercompared with a reference standard from M.D Anderson Centre, Houston, U.S.A and the results showed a good agreement. Recently one of the chambers was used for the Cs-137 intercomparison with IAEA and showed an agreement of better than ± 1%. 3. Primary Standard for X-rays - the free air chamber (FAC): This facility is utilized in conjunction with a Philips RT-250 X-ray machine for calibrating secondary standard dosemeters at different X-ray qualities in the 75 to 250 kV range. The total uncertainty in the realization of air kerma is around ±1% using the free air chamber. Accuracy of calibration of the secondary standards is estimated to be better than ±2%. The FAC has been intercompared via transferable transfer standards with FACs at BIPM (1971), BNM (France) RCL (Canada) and Kriss (Korea), which showed good agreement within ±1% after necessary correction for the spectral differences in X-ray beams. BARC is just now taking part in intercomparisons of X-ray air kerma calibration factors organised by Institute of Nuclear Energy Research (INER), Taiwan under Asia Pacific Metrology Programme. In addition to the above-mentioned primary standards, the SSDL is also maintaining the following secondary standards. For air kerma measurements at Co-60 gamma energy, ionisation chambers of Exradin A3, NE2571, NE2577 and Victoreen 415 types are calibrated and maintained. For Co-60 radiation dose to water measurements, NE 2571 and NE 2577 chambers calibrated at BIPM in terms of ND,W are maintained. For air kerma at medium energy x-rays, chambers of the type Exradin A2, NE 2571, NE2577, Victoreen 415 B, Victoreen 415, Exradin A3 and NE 2581 are

  6. Comparison of air kerma measurements in mammography using thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    A co-ordinated research project, Image Quality and Patient Dose Optimization in Mammography in Eastern European Countries, was conducted by the IAEA, which aimed at defining a methodology for the implementation of a quality assurance programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in eastern European countries.A comparison of dosimetry systems has been organized to ensure that dose measurements carried out within the framework of the project are comparable. Selected mammography units from the Czech Republic, Hungary, Poland, Romania, Slovakia and Spain participated in the exercise. The thermoluminescence method was selected for the comparison. The dosimeters were irradiated free in air to values of air kerma in the range of 5 mGy to 9 mGy and mailed to the participants for evaluation. Deviations of measured values from the true values of less than 10% were considered a measure of good dosimetry performance. The results of the comparison showed that about 70% of reported values of air kerma were outside the 10% acceptance limit. Two follow-up exercises were organized. The first follow-up resulted in only 20% of reported values exceeding the limit, and during the second follow-up all results were within the acceptance limit

  7. Estimation of the peak entrance surface air kerma for patients undergoing computed tomography-guided procedures

    International Nuclear Information System (INIS)

    The purpose of this work was to develop a method for estimating the patient peak entrance surface air kerma from measurements using a pencil ionisation chamber on dosimetry phantoms exposed in a computed tomography (CT) scanner. The method described is especially relevant for CT fluoroscopy and CT perfusion procedures where the peak entrance surface air kerma is the risk-related quantity of primary concern. Pencil ionisation chamber measurements include scattered radiation, which is outside the primary radiation field, and that must be subtracted in order to derive the peak entrance surface air kerma. A Monte Carlo computer model has therefore been used to calculate correction factors, which may be applied to measurements of the CT dose index obtained using a pencil ionisation chamber in order to estimate the peak entrance surface air kerma. The calculations were made for beam widths of 5, 7, 10 and 20 mm, for seven positions of the phantom, and for the geometry of a GE HiSpeed CT/i scanner. The program was validated by comparing measurements and calculations of CTDI for various vertical positions of the phantom and by directly estimating the peak ESAK using the program. Both validations showed agreement within statistical uncertainties (standard deviation of 2.3% or less). For the GE machine, the correction factors vary by ?10% with slice width for a fixed phantom position, being largest for the 20 mm beam width, and at that beam width range from 0.87 when the phanbeam width range from 0.87 when the phantom surface is at the iso-centre to 1.23 when it is displaced vertically by 24 cm. (authors)

  8. Air Kerma above environmental radiometric calibration facility for field equipment

    International Nuclear Information System (INIS)

    The use of gamma ray spectrometers broadened the aims of gamma ray surveys, stead of measuring only the gross radiation, as was done with the GM tubes, it is now possible to be used for uranium exploration, geological mapping as an aid to the exploration of non radioactive ores like gold and tin, radiation background measurements to identify hot spots for radiation hazard evaluation and environmental monitoring of fallout from radiological and nuclear accidents. It became necessary to carefully and precisely calibrate the field equipment to be used to get all the information from such uses. There is an environmental radiometric calibration facility for field equipment, consisting of eight radioactive concrete sources, at the Institute of Radioprotection and Dosimetry - IRD (CNEN/Brazil). These sources are cylindrical with 3 m diameter, 0.5 m thick and weigh about 7.5 tons each. The amount and type of the radioactive material, 238 U and 232 Th and 40 K ores in secular radioactive equilibrium, added to the concrete to simulate rock outcrops, varies in order to obtain different gamma fields, varying in both energy and intensity. These different radiation fields were measured with a HPGe portable detector, specifically calibrated for spectrum stripping, and the air kerma energy distribution was determined for each concrete source and compared with the total air kerma calculated from the nuclide concentration and by others radiometric methocentration and by others radiometric methods. (author)

  9. Computation of air kerma rate around an industrial radiography source

    International Nuclear Information System (INIS)

    Use of Iridium-192 and Cobalt-60 sources in Industrial Radiography has recorded a steep rise in the last three decades in India. There are about 425 institutions in possession of 1100 radiography equipment's. Widespread use of these sources call for meticulous radiation safety programme in the use of these sources. A gamma radiography exposure device comprises of adequately shielded source holder assembly and accessories such as remote control cable and guide tube with suitable mechanism to facilitate radiation exposure in a safe manner for industrial radiography work. The source holder assembly is driven out of the shielded container through the guide tube by means of a suitable drive mechanism. Various built-in design safety features are incorporated in these devices to ensure safe operation and to avoid untoward incidents. In spite of effective regulatory control, accidents may take place. For example, an accident situation may arise due to decoupling of the source assembly which may lead to the source falling on the ground and consequent exposure of people around the source and also the personnel involved in source retrieval operations. A knowledge of the air kerma distribution around the source will be of use in estimating the doses to the concerned personnel. This paper discusses the air kerma distribution around and iridium-192 radiography source computed using Monte Carlo method

  10. Routine measurement of gamma ray air kerma rate in the environment

    International Nuclear Information System (INIS)

    This Note, issued by Her Majesty's Inspectorate of Pollution, provides technical guidance on the routine measurement of gamma ray air kerma rate in the environment. It includes a protocol for the measurement, interpretation and reporting of environmental gamma ray air kerma rates and appendices reviewing existing techniques, instruments, calibration facilities and the physics of such measurements. (UK)

  11. X-rays spectrum and air Kerma during a mammography study; Espectro de los rayos X y Kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)], e-mail: fermineutron@yahoo.com

    2009-10-15

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +{sub -} 0.03 m G, while the other obtained by the calculations was of 0.96 +{sub -} 0.06 mGy, to compare both do not exist significant differences. (author)

  12. Correlation of reference air kerma rate and activity for indigenous brachytherapy sources

    International Nuclear Information System (INIS)

    The Board of Radiation and Isotope Technology (BRIT), DAE, supplies 137Cs tube sources for manual after-loading intracavitary applications and 192Ir wire sources for manual after-loading interstitial applications. The nominal activities of these sources are quoted in terms of mCi or mCi/cm, based on measurements in a re-entrant ionization chamber. The internationally recommended unit for specification of brachytherapy sources is Reference Air Kerma Rate, the air kerma rate at 1m. To correlate the supplier quoted activity to reference air kerma rate, traceable to international standards, measurements have been carried out using a calibrated well-type ionization chamber and a reference 137Cs source. The measured air kerma rate constants of 0.078 ?Gy.h-1.m2 MBq-1 (2.90 ?Gy. h-1.m2. mCi-1) for 137Cs tube source is in good agreement with other reported values. The measured air kerma rate constant for 0.3mm diameter 192Ir wire is 0.102 ?Gy.h-1.m2. MBq-1 (3.80 ?Gy.h-1.m2.mCi1) by well chamber measurements and 0.103 ?Gy.h-1m2. MBq- (380 ?Gy.h-1.m2.mCi-1) by in-air measurements. These values, although are consistent with our earlier measurements and published values for similar type wire from Amersham, are considerably low from Amersham, are considerably lower than the values generally used and quoted in referenced literature. It is, therefore, recommended that the suppliers should quote the strength of brachytherapy sources only in terms of reference air kerma rate or air kerma strength. The users may convert into unit required for the computer, using appropriate conversion factors. (author)

  13. X-rays spectrum and air Kerma during a mammography study

    International Nuclear Information System (INIS)

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO2+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the other obtained by the calculations was of 0.96 +- 0.06 mGy, to compare both do not exist significant differences. (author)

  14. Reference air kerma and kerma-area product as estimators of peak skin dose for fluoroscopically guided interventions

    International Nuclear Information System (INIS)

    Purpose: To determine more accurate regression formulas for estimating peak skin dose (PSD) from reference air kerma (RAK) or kerma-area product (KAP). Methods: After grouping of the data from 21 procedures into 13 clinically similar groups, assessments were made of optimal clustering using the Bayesian information criterion to obtain the optimal linear regressions of (log-transformed) PSD vs RAK, PSD vs KAP, and PSD vs RAK and KAP. Results: Three clusters of clinical groups were optimal in regression of PSD vs RAK, seven clusters of clinical groups were optimal in regression of PSD vs KAP, and six clusters of clinical groups were optimal in regression of PSD vs RAK and KAP. Prediction of PSD using both RAK and KAP is significantly better than prediction of PSD with either RAK or KAP alone. The regression of PSD vs RAK provided better predictions of PSD than the regression of PSD vs KAP. The partial-pooling (clustered) method yields smaller mean squared errors compared with the complete-pooling method.Conclusion: PSD distributions for interventional radiology procedures are log-normal. Estimates of PSD derived from RAK and KAP jointly are most accurate, followed closely by estimates derived from RAK alone. Estimates of PSD derived from KAP alone are the least accurate. Using a stochastic search approach, it is possible to cluster together certain dissimilar types of procedures to minimize the total error sum of squares.

  15. Air kerma rate estimation by means of in-situ gamma spectrometry: A Bayesian approach

    International Nuclear Information System (INIS)

    Full text: Bayesian inference is used to determine the Air Kerma Rate based on a set of in situ environmental gamma spectra measurements performed with a NaI(Tl) scintillation detector. A natural advantage of such approach is the possibility to quantify uncertainty not only in the Air Kerma Rate estimation but also for the gamma spectra which is unfolded within the procedure. The measurements were performed using a 3'' x 3'' NaI(Tl) scintillation detector. The response matrices of such detection system were calculated using a Monte Carlo code. For the calculations of the spectra as well as the Air Kerma Rate the WinBugs program was used. WinBugs is a dedicated software for Bayesian inference using Monte Carlo Markov chain methods (MCMC). The results of such calculations are shown and compared with other non-Bayesian approachs such as the Scofield-Gold iterative method and the Maximum Entropy Method

  16. X-Rays spectrum and air kerma during a mammography study;Espectro de los rayos X y kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur No. 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Chacon R, A.; Vega C, H. R., E-mail: ramirezgonzalezjaime@yahoo.com.m [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2009-10-15

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the obtained by means of the calculations was of 0.96 +- 0.06 mGy, when comparing both significant differences do not exist. (Author)

  17. Energy-absorption buildup factors, effective atomic numbers and air-kerma for human body parts, vitamins and tissue substitutes

    International Nuclear Information System (INIS)

    Effective atomic numbers Zeff, air-kerma and energy-absorption buildup factors, EABF for some human organs and tissues, vitamins and tissue substitutes have been computed in the present work. Geometric-Progression (G-P) fitting method was applied for computation of EABF. It is observed that the EABF and air-kerma are dependent upon Zeff and chemical compositions. The EABF, Zeff and air-kerma of calcium carbonate and lithium carbonate are found in good agreement with cortical bone and fat, respectively. The EABF in the present work could be useful in medical diagnostics, radiation therapy procedures and also personal monitoring. (author)

  18. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray

    International Nuclear Information System (INIS)

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm2, for patients with 1 to 5 years old range from 17 to 192 mGy.cm2, and from 30,4 to 136,2 mGy.cm2 for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  19. Determination of calibration factors in terms of air kerma and absorbed dose to water in the 60Co ? rays

    International Nuclear Information System (INIS)

    The method of calibration of an instrument, as performed at the BIPM in the 60Co field in terms of air kerma or absorbed dose to water, is described in detail. The influence of various parameters which can affect the calibration factor is analyzed. The uncertainty is of order 0.3% and 0.5% for calibration factors in terms of air kerma and of absorbed dose to water, respectively. (author). 14 refs, 10 figs, 3 tabs

  20. Calculated neutron air kerma strength conversion factors for a generically encapsulated Cf-252 brachytherapy source

    CERN Document Server

    Rivard, M J; D'Errico, F; Tsai, J S; Ulin, K; Engler, M J

    2002-01-01

    The sup 2 sup 5 sup 2 Cf neutron air kerma strength conversion factor (S sub K sub N /m sub C sub f) is a parameter needed to convert the radionuclide mass (mu g) provided by Oak Ridge National Laboratory into neutron air kerma strength required by modern clinical brachytherapy dosimetry formalisms indicated by Task Group No. 43 of the American Association of Physicists in Medicine (AAPM). The impact of currently used or proposed encapsulating materials for sup 2 sup 5 sup 2 Cf brachytherapy sources (Pt/Ir-10%, 316L stainless steel, nitinol, and Zircaloy-2) on S sub K sub N /m sub C sub f was calculated and results were fit to linear equations. Only for substantial encapsulation thicknesses, did S sub K sub N /m sub C sub f decrease, while the impact of source encapsulation composition is increasingly negligible as Z increases. These findings are explained on the basis of the non-relativistic kinematics governing the majority of sup 2 sup 5 sup 2 Cf neutron interactions. Neutron kerma and energy spectra resul...

  1. Effect of pressure, temperature and humidity in air on photon fluence and air kerma values at low photon energies

    International Nuclear Information System (INIS)

    An investigation into the effect of pressure, temperature and humidity in air on photon fluence at a typical mammography, low bremsstrahlung energy (25 kVp), has been carried out. Pressure values corrected for humidity at varying temperatures were employed to determine the density of moist air. Using the corrected moist air densities, the X-ray photon fluence remaining after air attenuation has been computed assuming an X-ray focal spot-detector distance of 65 cm. Bremsstrahlung spectral distributions and the effects of pressure, temperature and humidity on the photon fluence from molybdenum and tungsten targets are illustrated. Comparative results suggest that such effects could be significant and need to be considered when calculating exposure levels from low-energy photons. The investigation showed that air kerma values from an X-ray spectrum that has significant lower-energy components is likely to be more sensitive to changes in pressure, temperature and humidity than the air kerma from an X-ray spectrum with lower-energy components less pronounced. Non-negligible air kerma values are involved

  2. Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast

    Scientific Electronic Library Online (English)

    Andréa, Gonçalves; João Manuel Domingos de Almeida, Rollo; Marcelo, Gonçalves; Francisco, Haiter Neto; Frab Norberto, Bóscolo.

    2004-12-01

    Full Text Available Este estudo avaliou a redução da taxa de kerma no ar, o espectro de energia dos raios X e alterações na qualidade da imagem radiográfica. Comparações com várias espessuras do filtro de liga de alumínio-cobre em três diferentes porcentagens foram feitas com o filtro de alumínio. Os experimentos foram [...] feitos utilizando-se um aparelho de raios X odontológico convencional, obtendo radiografias com auxílio de um fantoma de segmento de mandíbula e de uma escala de densidade confeccionada com alumínio laminado. Dependendo da espessura da filtração da liga de alumínio-cobre, o feixe de raios X pôde ser endurecido em relação ao filtro de alumínio. O uso do filtro de liga de alumínio-cobre resultou em 8,40% a 47,33% de redução da taxa média de kerma no ar e indicou contraste da imagem radiográfica sem alteração, quando comparado com a filtração de alumínio, mostrando que os filtros de liga de alumínio-cobre tornam-se alternativas aceitáveis em relação aos filtros de alumínio. Abstract in english This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were [...] made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and were made on mandible phantom and on step-wedge. Depending on the thickness of aluminum-copper alloy filtration, the beam could be hardened and filtrated. The use of the aluminum-copper alloy filter resulted in reductions in air kerma rate from 8.40% to 47.33%, and indicated the same image contrast when compared to aluminum filtration. Aluminum-copper alloy filtration may be considered a good alternative to aluminum filtration.

  3. Sensitivity/uncertainty analysis for free-in-air tissue kerma due to initial radiation at Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Uncertainty estimates and cross correlations by range/survivor have been calculated for the Hiroshima and Nagasaki free-in-air (FIA) tissue kerma obtained from two-dimensional air/ground transport calculations. The uncertainties due to modeling parameter and basic nuclear transport data uncertainties were calculated for 700-, 1000-, and 1500-m ground ranges. Only the FIA tissue kerma due to initial radiation was treated in the analysis; the uncertainties associated with terrain and building shielding and phantom attenuation were not considered in this study. Uncertainties of --20% were obtained for the prompt neutron and secondary gamma kerma and 30% for the prompt gamma kerma at both cities. The uncertainties on the total prompt kerma at Hiroshima and Nagasaki are --18 and 15%, respectively. The estimated uncertainties vary only slightly by ground range and are fairly highly correlated. The total prompt kerma uncertainties are dominated by the secondary gamma uncertainties, which in turn are dominated by the modeling parameter uncertainties, particularly those associated with the weapon yield and radiation sources

  4. Product kerma in the air-area and radiation dose in dental radiodiagnosis

    International Nuclear Information System (INIS)

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  5. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-rayProduct estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray

    International Nuclear Information System (INIS)

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm2, for patients with 1 to 5 years old range from 17 to 192 mGy.cm2, and from 30,4 to 136,2 mGy.cm2 for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm2, for patients with 1 to 5 years old range from 17 to 192 mGy.cm2, and from 30,4 to 136,2 mGy.cm2 for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  6. Preliminary study on quality audit for air kerma strength determination of high dose rate brachytherapy sources

    International Nuclear Information System (INIS)

    Brachytherapy is one of the modes of treatment of cancerous cells. High dose rate (HDR) brachytherapy using high activity 192Ir source has become very popular for all brachytherapy applications worldwide. The accurate dose delivery to the patient depends on many dosimetric parameters. Air Kerma Strength is one of the clinical parameters which is recommended by many international bodies to specify the brachytherapy source strength and used in the TG-43 dosimetry formalism. Our study concludes that TLD based Quality Audit method can be used for postal audit of HDR brachytherapy sources strength verification

  7. Monte-Carlo Simulation of Conversion Coefficient for Air Kerma From Photon Fluence

    International Nuclear Information System (INIS)

    The conversion coefficients for air kerma from photon fluence were calculated using Monte-Carlo code EGS5 with photon energy range from 10 keV to 10 MeV. The calculated results of Monte-Carlo simulation show good agreement with the data recommended by ICRP74, ICRU47 reports within ±2.0%, ±3.5%, respectively.The calculated results were fitted to a parametric formula. The values of the formula were in agreement within ±4.0%, ±7.0% compared to the data recommended by ICRP74, ICRU47 reports, respectively. (authors)

  8. Measurement of air kerma rate for Cs-137 using different ionization chambers

    International Nuclear Information System (INIS)

    Due to the importance of radiation doses in medical field quality assurance should be established in order to maintain a reasonable balance between the purpose of application and exposure. This study had been carried out to achieve quality control for protection based on air kerma rate. Measurements were performed by using Cs-137 for the comparison of two working ionization chambers in secondary standard dosimetry laboratory of Sudan. Spherical ionization chamber L S-01 1000 cc S/N 912 and Farmer ionization chamber 2675 A 600 cc S/N 0511, respectively. The results obtained from this study have been represented as mean and their standard deviations shown in most cases remains at 5% uncertainly. Comparison between kinetic energy released per unit mass in air rate (air kerma rate) were obtained by using spherical ionization chamber L S-01 1000 cc S/N 912 and results have been determined using inverse square law. The differences have been represented as means and standard deviations with significant P-value less than 0.05. Spherical ionization chamber gives accurate, reproducible results with acceptable uncertainty which is more suitable for calibration of radiation detectors.(Author)

  9. Product kerma in the air-area and radiation dose in dental radiodiagnosis; Produto kerma ar-area e dose efetiva em radiodiagnostico odontologico

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alessandro Martins da, E-mail: amcosta@usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica

    2014-07-01

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  10. Avaliação do kerma no ar na superfície de entrada e da qualidade da imagem em radiografias de tórax / Evaluation of entrance surface air kerma rate and clinical images quality in chest radiography

    Scientific Electronic Library Online (English)

    Angelo Bernardo Brasil de, Souza; Simone Kodlulovich, Dias; Fernando Mecca, Augusto; Winston Andrade, Marques.

    2009-10-01

    Full Text Available OBJETIVO: Avaliar os fatores de técnica utilizados durante exames de tórax póstero-anterior em pacientes-padrão e correlacioná-los aos valores de kerma no ar na superfície de entrada e à qualidade das imagens clínicas. MATERIAIS E MÉTODOS: O estudo foi realizado em três hospitais do Rio de Janeiro, [...] num total de cinco salas de raios X, com dez pacientes por sala. As imagens foram avaliadas pelos radiologistas dos serviços segundo o protocolo europeu. O kerma no ar na superfície de entrada foi estimado a partir da curva de rendimento do equipamento de raios X, que foi obtida utilizando câmara de ionização acoplada a um eletrômetro. Análise de variância foi realizada para verificar se a diferença entre os valores de kerma no ar na superfície de entrada é significativa. RESULTADOS: Os valores de kerma no ar na superfície de entrada variaram entre 0,05 e 0,26 mGy, com média 60% inferior ao nível de referência publicado na Portaria 453. Das imagens avaliadas, 98% atenderam acima de 65% dos critérios de qualidade. CONCLUSÃO: Para um padrão de qualidade da imagem, aceitável para o diagnóstico, verificou-se ampla variação do kerma no ar na superfície de entrada para pacientes-padrão. Isto demonstra a falta de padronização dos fatores de técnica e a existência de um potencial de redução do valor do kerma no ar na superfície de entrada. Abstract in english OBJECTIVE: To evaluate technical factors involved in posteroanterior chest radiography in standard patients, and correlating them with entrance surface air kerma rate and with the clinical images quality. MATERIALS AND METHODS: The present study was developed at three hospitals in Rio de Janeiro, Br [...] azil, involving a total of five x-ray rooms, with ten patients per room. The images were evaluated by the radiologists of the institutions, in accordance with the European protocol. The estimation of surface entrance air kerma rate was based on the x-ray equipment output curve obtained with an ionization chamber coupled with an electrometer. Variance analysis was performed to evaluate the significance of the difference between entrance surface air kerma rates. RESULTS: Entrance surface air kerma rates ranged between 0.05 and 0.26 mGy, with a mean value 60% lower than the reference level established by the Order (Portaria) 453. Among the images evaluated, 98% fulfilled > 65% of the images quality criteria. CONCLUSION: For a standard image quality that is acceptable for diagnosis purposes, a significant variation was observed in the entrance surface air kerma rate for standard patients, demonstrating the lack of technical factors standardization and a potential for decreasing the entrance surface air kerma rate.

  11. Avaliação do kerma no ar na superfície de entrada e da qualidade da imagem em radiografias de tórax Evaluation of entrance surface air kerma rate and clinical images quality in chest radiography

    Directory of Open Access Journals (Sweden)

    Angelo Bernardo Brasil de Souza

    2009-10-01

    Full Text Available OBJETIVO: Avaliar os fatores de técnica utilizados durante exames de tórax póstero-anterior em pacientes-padrão e correlacioná-los aos valores de kerma no ar na superfície de entrada e à qualidade das imagens clínicas. MATERIAIS E MÉTODOS: O estudo foi realizado em três hospitais do Rio de Janeiro, num total de cinco salas de raios X, com dez pacientes por sala. As imagens foram avaliadas pelos radiologistas dos serviços segundo o protocolo europeu. O kerma no ar na superfície de entrada foi estimado a partir da curva de rendimento do equipamento de raios X, que foi obtida utilizando câmara de ionização acoplada a um eletrômetro. Análise de variância foi realizada para verificar se a diferença entre os valores de kerma no ar na superfície de entrada é significativa. RESULTADOS: Os valores de kerma no ar na superfície de entrada variaram entre 0,05 e 0,26 mGy, com média 60% inferior ao nível de referência publicado na Portaria 453. Das imagens avaliadas, 98% atenderam acima de 65% dos critérios de qualidade. CONCLUSÃO: Para um padrão de qualidade da imagem, aceitável para o diagnóstico, verificou-se ampla variação do kerma no ar na superfície de entrada para pacientes-padrão. Isto demonstra a falta de padronização dos fatores de técnica e a existência de um potencial de redução do valor do kerma no ar na superfície de entrada.OBJECTIVE: To evaluate technical factors involved in posteroanterior chest radiography in standard patients, and correlating them with entrance surface air kerma rate and with the clinical images quality. MATERIALS AND METHODS: The present study was developed at three hospitals in Rio de Janeiro, Brazil, involving a total of five x-ray rooms, with ten patients per room. The images were evaluated by the radiologists of the institutions, in accordance with the European protocol. The estimation of surface entrance air kerma rate was based on the x-ray equipment output curve obtained with an ionization chamber coupled with an electrometer. Variance analysis was performed to evaluate the significance of the difference between entrance surface air kerma rates. RESULTS: Entrance surface air kerma rates ranged between 0.05 and 0.26 mGy, with a mean value 60% lower than the reference level established by the Order (Portaria 453. Among the images evaluated, 98% fulfilled > 65% of the images quality criteria. CONCLUSION: For a standard image quality that is acceptable for diagnosis purposes, a significant variation was observed in the entrance surface air kerma rate for standard patients, demonstrating the lack of technical factors standardization and a potential for decreasing the entrance surface air kerma rate.

  12. Establishment of air kerma reference standard for low dose rate Cs-137 brachytherapy sources.

    Science.gov (United States)

    Sharma, Sunil Dutt; Kumar, Sudhir; Srinivasan, P; Chourasiya, G

    2011-01-01

    A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fabricated for use as a reference standard for low-dose rate 137Cs brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin's general cavity theory, as well as by the Monte Carlo simulation and validated experimentally using Amersham CDCS-J-type 137Cs reference source. In the analytical method, the N(K) was calculated for 662 keV gamma rays of 137Cs brachytherapy source. In the Monte Carlo method, the geometry of the measurement setup and physics-related input data of the 137Cs source and the surrounding material were simulated using the Monte Carlo N-Particle code. The photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficient. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber, and the N(K) was determined. The analytical and Monte Carlo values of N(K) of the cylindrical graphite ionization chamber for 137Cs brachytherapy source are in agreement within 1.07%. The deviation of analytical and Monte Carlo values from experimental values of N(K) is 0.36% and 0.72%, respectively. This agreement validates the analytical value, and establishes this chamber as a reference standard for RAKR or AKS measurement of 137Cs brachytherapy sources. PMID:22089009

  13. Relationship between absorbed dose-rate in water and reference air kerma-rate for I-125 seeds

    International Nuclear Information System (INIS)

    To clinically utilize measured relative three-dimensional dose distribution about I-125 seeds in water, the absolute dose-rate in medium per source strength specification unit must be known at one point. Source strength is defined as air kerma-rate in free space along the transverse bisector of the source at a reference distance. The author has used the Monte Carlo method to calculate the dose-rate in water 1 cm from the source along its perpendicular bisector per unit reference air-kerma rate for model 6711, 6701, and 6702 seeds. The results indicate that published dose-rate constants overestimate this quantity by 10%-17%

  14. Kerma rate evaluation in the air in a room interventional cardiology; Avaliacao da taxa de Kerma no ar em uma sala de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2014-07-01

    In recent years, the number of interventional cardiology procedures is increasing. However, due to the long time of fluoroscopy in these procedures, care teams can receive high doses of radiation. The radiation scattered by the patient is not uniform, and their assessment is of utmost importance. This study aimed to estimate and map the kerma rate in the air at the time of the gonads, in an interventional cardiology room, seeking to optimize the dose absorbed by individuals occupationally exposed to ionizing radiation. For data collection, the room was divided into quadrants of 1m{sup 2}, totaling 40 collection points. The simulator was positioned so that its entry surface was located in the interventional reference point. Were chosen the conditions that simulate angiography and angioplasty procedures performed in the service. The data were obtained for height of 1 meter, gonad region. The results obtained for kerma rates in air, in quadrants, show that higher measured values was in the vicinity of the X-ray tube. Has been found that the medical staff are more exposed, because of its location during the procedure, around the table. The law of the inverse square distance of the farthest points of the X-ray tube were verified.

  15. Energy required to produce an ion pair in gas in the function of the measurement of kerma in air

    International Nuclear Information System (INIS)

    Average energy for producing an ion pair, mean W, was defined. So is its dependence on type of particles, relative partial pressure of the steam and relative humidity. Measurement methods were outlined. Energy W for different gases was presented in a Table, with an accent on the air. For the air, as the most interesting gas, the most recent determined value was given. Relationship between W, exposition X and air kerma K was explained (author)

  16. Air kerma standardization for diagnostic radiology in a secondary standard laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Manoel M.O.; Peixoto, J. Guilherme P. [Instituto de Radioprotecao e Dosimetria (IRD-CNEN/RJ), Rio de Janeiro, RJ (Brazil)], e-mail: mmoramos@ird.gov.br, e-mail: guilherm@ird.gov.br; Lopes, Ricardo T. [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)], e-mail: ricardo@lin.ufrj.br

    2009-07-01

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Brazilian Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. The objective of this work was to implement the standardization of the air kerma for the unatenuated qualities (RQR) of IEC 61267 in the National Laboratory of Metrology of the Ionizing Radiations (LNMRI) of the Institute of Radiation Protection and Dosimetry (IRD). Technical procedures were developed together with uncertainty budget. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. (author)

  17. The ratios of effective dose to entrance skin dose to the air kerma for some medical sources

    International Nuclear Information System (INIS)

    Results are presented for the ratios of the effective dose to skin entrance dose and to air kerma for broad beams of radiation expected to be encountered by medical workers. These workers are monitored by the Personal Radiation Monitoring Service (PRMS) using thermoluminescent dosimeters worn at the front of the body to provide estimates of the entrance skin dose. Factors are given for converting estimates of entrance skin dose to effective dose as defined by the International Commission on Radiological Protection (ICRP 1991) for beams incident on the body by one of three modes-from the front of the subject, from the back of the subject or by rotation around the subject. Additional tables are also given to calculate effective dose for these beams from a measurement of air kerma free-in-air

  18. Survivor dosimetry. Part B. DS02 free-in-air neutron and gamma tissue kerma relative to DS86

    International Nuclear Information System (INIS)

    The major determinant of the radiation dose to a survivor at a given location with respect to the hypocenter of a bomb detonation is the radiation field in the open at that location. Therefore, a change in free-in-air (FIA) kerma at any given distance from the bomb has a proportional effect on the doses of all survivors at that distance, if the shielding is not changed. The fluence-to-kerma coefficients used in the DS02 studies are discussed in Chapter 12, Part A, where one can see that the differences between the newer DS02 and older DS86 kerma coefficients for soft tissues of the body are quite small at the neutron and gamma-ray energies that are most important in the radiation dosimetry for the survivors. Thus, the differences in DS02 and DS86 FIA tissue kermas from neutrons and photons are due essentially to differences in the DS02 and DS86 source term and transport calculations discussed in Chapters 2 and 3. (J.P.N.)

  19. Comparison of the standards of air kerma of the OMH and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison between the standards for air kerma of the Orszagos Meresugyi Hivatal (OMH) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in the 60Co radiation beams of the BIPM. The result, expressed as a ratio of the OMH and the BIPM standards for air kerma, indicates a relative difference of 10.9 x 10-3 with a combined standard uncertainty of 2.2 x 10-3. This new result agrees at the level of 0.4 x 10-3 with the earlier direct comparisons performed in 1986 and 1994, as modified in 2001 by the application of wall and axial non-uniformity correction factors, calculated for the OMH standards using the Monte Carlo method. (authors)

  20. Comparison of the standards of air kerma of the LNE-LNHB and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Laboratoire National de Metrologie et d'Essais - Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in December 2003. The results, expressed as ratios of the LNE-LNHB and the BIPM standards for air kerma, indicate a relative difference of 3.5 x 10-3 with a combined standard uncertainty of 2.7 x 10-3. The earlier direct comparison in 60Co ? rays, made in 1993, resulted in an agreement of the two standards within 2.5 x 10-3. (authors)

  1. Linearity of the air kerma values in relation to exposure times in a dental X radiation system

    International Nuclear Information System (INIS)

    The objective of this study was the evaluation of a dental X radiation system intensity variation studying the linearity of the air kerma rate in relation to the exposure time. This study was performed in a Dabi Atlante dental X radiation system. For the exposure time measurements the cone spacer was positioned perpendicular to the detector and the time was varied from 0 to 1.5 s. The air kerma measurements were made in the same conditions for FDD=20.0 cm and 27.5 cm. After that, the obtained values were plotted and a linear adjust was done for each set of measurements. The results showed that the maximum variation obtained was 7% for the third group of measurements for the exposure time of 1.5 s. This variation is less than the recommended limit of 20% published by the Brazilian Health Ministry Regulation 453. (author)

  2. Monte Carlo simulations in CT for the study of the surface air kerma and energy imparted to phantoms of varying size and position

    International Nuclear Information System (INIS)

    A Monte Carlo computational model of CT has been developed and used to investigate the effect of various physical factors on the surface air kerma length product, the peak surface air kerma, the air kerma length product within a phantom and the energy imparted. The factors investigated were the bow-tie filter and the size, shape and position of a phantom which simulates the patient. The calculations show that the surface air kerma length product and the maximum surface air kerma are mainly dependent on phantom position and decrease along the vertical axis of the CT plane as the phantom surface moves away from the isocentre along this axis. As a result, measurements using standard body dosimetry phantoms may underestimate the skin dose for real patients. This result is specially important for CT fluoroscopic procedures: for an adult patient the peak skin dose can be 37% higher than that estimated with a standard measurement on the body AAPM (American Association of Physicists in Medicine) phantom. The results also show that the energy imparted to a phantom is mainly influenced by phantom size and is nearly independent of phantom position (within 3%) and shape (up to 5% variation). However, variations of up to 30% were found for the air kerma to regions within the AAPM body phantom when it is moved vertically. This highlights the importance of calculating doses to organs taking into account their size and position within the gantrytry

  3. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories

    International Nuclear Information System (INIS)

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  4. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy

    International Nuclear Information System (INIS)

    This work aims to estimate the average conversion factor of Kerma in air to H * (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm2, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  5. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories; Padronizacao da grandeza Kerma no ar para radiodiagnostico e proposta de requisitos para laboratorios de calibracao

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Manoel Mattos Oliveira

    2009-07-01

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  6. Study and determination of the national dosimetric standards in terms of air kerma for X-rays radiation fields of low and medium-energies; Etude et realisation des references dosimetriques nationales en termes de kerma dans l'air pour les faisceaux de rayons X de basses et moyennes energies

    Energy Technology Data Exchange (ETDEWEB)

    Ksouri, W

    2008-12-15

    Progress in radiation protection and radiotherapy, and the increased needs in terms of accuracy lead national metrology institutes to improve the standard. For ionizing radiation, the standard is defined by an absolute instrument used for air kerma rate measurement. The aim of the thesis is to establish standards, in terms of air kerma for X-rays beams of low and medium-energies. This work enables to complement the standard beam range of the Laboratoire National Henri Becquerel (LNHB). Two free-air chambers have been developed, WK06 for medium-energy and WK07 for low-energy. The air-kerma rate is corrected by several correction factors. Some are determined experimentally; and the others by using Monte Carlo simulations. The uncertainty budget of the air-kerma rate at one standard deviation has been established. These dosimetric standards were compared with those of counterparts' laboratories and are consistent in terms of degree of equivalence. (author)

  7. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures

    International Nuclear Information System (INIS)

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences and recommendations) and establish a permanent radiation protection training programs. (author)

  8. Comparison of the standards for air kerma of the ENEA-INMRI and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. The comparison result, declared in 2002, is 1.0103 (0.0026). The difference between the ENEA-INMRI and BIPM standards is consistent with the various changes that have been introduced since the previous comparisons that were in agreement within the comparison uncertainties. (authors)

  9. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133 Ba, 241 Am and 57 Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and backscatter factors were 12% and 6% respectively. (author)

  10. Air kerma standard for calibration of well-type chambers in Brazil using 192Ir HDR sources and its traceability

    International Nuclear Information System (INIS)

    In Brazil there are over 100 high dose rate (HDR) brachytherapy facilities using well-type chambers for the determination of the air kerma rate of 192Ir sources. This paper presents the methodology developed and extensively tested by the Laboratorio de Ciencias Radiologicas (LCR) and presently in use to calibrate those types of chambers. The system was initially used to calibrate six well-type chambers of brachytherapy services, and the maximum deviation of only 1.0% was observed between the calibration coefficients obtained and the ones in the calibration certificate provided by the UWADCL. In addition to its traceability to the Brazilian National Standards, the whole system was taken to University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) for a direct comparison and the same formalism to calculate the air kerma was used. The comparison results between the two laboratories show an agreement of 0.9% for the calibration coefficients. Three Brazilian well-type chambers were calibrated at the UWADCL, and by LCR, in Brazil, using the developed system and a clinical HDR machine. The results of the calibration of three well chambers have shown an agreement better than 1.0%. Uncertainty analyses involving the measurements made both at the UWADCL and LCR laboratories are discussed.

  11. Conversion coefficients from air-kerma to ambient dose equivalent for the International Standards Organisation's wide, narrow and low series of reference filtered X-radiations

    International Nuclear Information System (INIS)

    This report provides conversion coefficients from air-kerma to ambient dose equivalent for the International Standards Organisation's Wide, Narrow and Low Series of reference filtered X-radiations. The validity of the theoretical spectra used in the calculations is tested by detailed comparison with experimental results. Also, sensitivity analyses are performed to demonstrate the effect of tolerances in tube potential and filtration on the measured values of mean energy, first half-value layer and air-kerma rate. The theoretical spectral distributions of all members of the series are included within this report. (author)

  12. Evaluation of Wall Correction Factor of INER's Air-Kerma Primary Standard Chamber and Dose Variation by Source Displacement for HDR 192Ir Brachytherapy

    OpenAIRE

    Lee, J.H.; Wang, J. N.; T. T. Huang; S. H. Su; B. J. Chang; Su, C. H.; S. M. Hsu

    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...

  13. Bilateral comparison COOMET.RI(I)-S2 of the air-kerma standards of the IAEA and the VNIIM, Russian Federation in medium energy x-rays

    International Nuclear Information System (INIS)

    A bilateral comparison has been made between the air-kerma standards of the IAEA and the VNIIM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the stated standard uncertainty for the comparison of 4.1 parts in 103. The comparison result, based on the calibration coefficients for a transfer chamber, is expressed as a ratio of the IAEA and the VNIIM standards for air kerma, suitable for entry in the BIPM key comparison database. (authors)

  14. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2014. The comparison result, evaluated as a ratio of the PTB and the BIPM standards for air kerma, is 1.0036 with a combined standard uncertainty of 1.7 * 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  15. Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the PTB, Germany and the BIPM in 137Cs gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in March 2014. The comparison result, evaluated as a ratio of the PTB and the BIPM standards for air kerma, is 1.0024 with a combined standard uncertainty of 2.7 * 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  16. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the ININ, Mexico and the BIPM in 60Co gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Instituto Nacional de Investigaciones Nucleares (ININ), Mexico, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in 2012. The comparison result, evaluated as a ratio of the ININ and the BIPM standards for air kerma, is 1.0035 with a combined standard uncertainty of 2.1*10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  17. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the LNE-LNHB, France and the BIPM in 60Co gamma radiation

    International Nuclear Information System (INIS)

    An indirect comparison of the standards for air kerma of the Laboratoire National de Metrologie et d'Essais - Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in April 2013. The comparison result, evaluated as a ratio of the LNE-LNHB and the BIPM standards for air kerma, is 0.9994 with a combined standard uncertainty of 1.8*10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  18. Comparison BIPM.RI(I)-K8 of high dose rate 192Ir brachytherapy standards for reference air kerma rate of the NPL and the BIPM

    International Nuclear Information System (INIS)

    An indirect comparison of the standards for reference air kerma rate (RAKR) for 192Ir high dose rate (HDR) brachytherapy sources of the National Physical Laboratory (NPL), United Kingdom, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the NPL in June 2010. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NPL and the BIPM standards for reference air kerma rate, is 0.9989 with a combined standard uncertainty of 0.0057. (authors)

  19. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    International Nuclear Information System (INIS)

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the VSL and the BIPM standards for reference air kerma rate, is 0.9873 with a combined standard uncertainty of 0.0061. (authors)

  20. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    DEFF Research Database (Denmark)

    Alvarez, J.T.; De Pooter, J.A.

    2014-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the VSL and the BIPM standards for reference air kerma rate, is 0.9873 with a combined standard uncertainty of 0.0061.

  1. Calculation of factors to convert from air kerma to absorbed dose to water for medium energy photons

    International Nuclear Information System (INIS)

    The IPEMB code of practice for the determination of absorbed dose for X-rays below 300 kV generating potential is a dedicated dosimetry protocol for the determination of absorbed dose based on the air kerma evaluation method for medium energy X-rays. Three separate energy ranges are dealt with in the code of practice, however, this report is only attempting to reproduce the factors in one particular range (0.5 - 4.0 nun Cu HVL) for X-rays generated at 135 and 280 kV. These X-ray qualities are used in the NPL therapy level calibration service. This new method includes the use of an air kerma calibration factor, NK, for the ionisation chamber, and the ratio of the mass-energy absorption coefficients of water to air and factors that account for the change in the response of a NE2561 ionisation chamber between calibration in air and measurement in a water phantom, kch, instead of the old F factor. This report describes the work that was undertaken to reproduce the product of the ratio of the mass-energy absorption coefficients of water to air and the kch factors. The majority of this work was carried out using Monte Carlo techniques based on the EGS4 code system. The factors calculated in this report were found to agree with values quoted in the IPEMB code of practice to within 4.2%. The quoted uncertainty for this work is 1.4% and the uncertainties for the factors quoted in the EPEMB code of practice are 3%. Hence this is reasonable agreeice are 3%. Hence this is reasonable agreement. Possible discrepancies in the values may be due either to limitations in the EGS4 code system, simplifications made in the chamber geometry or on the reliance on experimental data which is not quite applicable to its' use in this work. (author)

  2. The performance of the INER improved free-air ionization chamber in the comparison of air kerma calibration coefficients for medium-energy X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.-H. E-mail: jhlee@iner.gov.tw; Kotler, L.H.; Bueermann, Ludwig; Hwang, W.-S.; Chiu, J.-H.; Wang, C.-F

    2005-01-01

    This paper describes modifications to an original design, correction factors and uncertainty evaluations for an improved free-air ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). In addition, a comparison of secondary standard air kerma calibration coefficients for 100-250 kV medium-energy X-rays was performed to verify the experimental accuracy and measurement consistency of the improved chamber. The comparison results showed a satisfactory agreement in the measurements which were within the combined expanded uncertainties (k=2)

  3. The performance of the INER improved free-air ionization chamber in the comparison of air kerma calibration coefficients for medium-energy X-rays

    International Nuclear Information System (INIS)

    This paper describes modifications to an original design, correction factors and uncertainty evaluations for an improved free-air ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). In addition, a comparison of secondary standard air kerma calibration coefficients for 100-250 kV medium-energy X-rays was performed to verify the experimental accuracy and measurement consistency of the improved chamber. The comparison results showed a satisfactory agreement in the measurements which were within the combined expanded uncertainties (k=2)

  4. Re-establishment of the air kerma and ambient dose equivalent standards for the BIPM protection-level 60Co beam

    International Nuclear Information System (INIS)

    The air kerma and ambient dose equivalent standards for the protection-level 60Co beam have been re-established following the repositioning of the irradiator and modifications to the beam. Details concerning the standards and the new uncertainty budgets are described in this report with their implications for dosimetry comparisons and calibrations. (authors)

  5. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate

    International Nuclear Information System (INIS)

    The 6- to 7-MeV high-energy gamma-ray calibration field by the 19F(p, ??)16O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. (authors)

  6. Construction of a laboratory for the implantation of primary standardization of the magnitude kerma in the air for the X-ray beams used in mammography

    International Nuclear Information System (INIS)

    Aiming to diminish the uncertainty in each phase of the metrological chain, and the uncertainty in dosimetry processed at the X-ray beam applied in the mammography, is necessary that the LNMRI/IRD to develop a reference primary standard for the absolute form to the magnitude kerma in the air

  7. Final report of the SIM 60Co Air-Kerma comparison (KCDB Entry SIM.RI(I)-K1)

    International Nuclear Information System (INIS)

    Transfer chambers were used to compare the standards for 60Co air kerma maintained by seven laboratories. Six of the laboratories are members of the Sistema Interamericano de Metrologia (SIM) regional metrology organization while the seventh is the International Atomic Energy Agency (IAEA) laboratory in Vienna. The National Research Council (NRC) acted as the pilot laboratory for the comparison. Because of the participation of laboratories holding primary standards, the comparison results could be linked to the key comparison reference value maintained by the Bureau International des Poids et Mesures (BIPM). The results for all laboratories were within the expanded uncertainty (two standard deviations) of the reference value. The estimated relative standard uncertainty of the comparison between any pair of laboratories ranged from 0.5% to 1.0%. The largest discrepancy between any two laboratories was 1.0%. (authors)

  8. From Reference Air Kerma Rate to Nominal Absorbed Dose Rate to Water: Paradigm Shift in Photon Brachytherapy

    International Nuclear Information System (INIS)

    In brachytherapy (BT), photon radiation sources are presently calibrated in terms of the reference air kerma rate K? (or air kerma strength SK). By direct source calibration in terms of Dw,1, the nominal absorbed dose rate to water at the TG-43U1 reference position at 1 cm in water and with the ability to measure distributions of this quantity, the accuracy of clinical BT-dosimetry should increase due to decreased calibration uncertainties compared to present methods. Several Dw,1 primary standards are under development for high energy, high dose rate and low energy, low dose rate sources. To provide worldwide traceability and guidance for clinical medical physicists, an ISO standardization project, Clinical Dosimetry - Photon Radiation Sources Used in Brachytherapy, is considered, in continuation of ISO 21439 (2009) for beta sources. Clear terms and definitions are fundamental. Reclassification of BT-photon radiation qualities is also needed, introducing a range of medium energy photons with mean energies between 40 keV and 150 keV. Radionuclide BT-sources and electronic X ray BT-sources, BT-detectors and BT-phantoms should be characterized by sets of reference data, through which the clinical medical physicist could critically evaluate the data supplied by the manufacturer, prior to clinical application. Plastic scintillators have the potential for transfer standards of high accuracy and for verification measurements of Bcy and for verification measurements of BT-source output in phantoms. Based on and extending the AAPM TG-43U1 formalism, this planned ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainties. (author)

  9. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures; Distribuicao da taxa de kerma no ar em uma sala de hemodinamica para projecoes tipicas de procedimentos de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Mirtha Elizabet Gamarra

    2008-07-01

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences and recommendations) and establish a permanent radiation protection training programs. (author)

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

    Science.gov (United States)

    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.

  11. Physical parameters and correction factors for ionization chambers for absolute measurement of air kerma in ?-ray fields

    International Nuclear Information System (INIS)

    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

  12. Physical parameters and correction factors for ionization chambers for absolute measurement of air kerma in {gamma}-ray fields

    Energy Technology Data Exchange (ETDEWEB)

    Takata, N. [Ionizing Radiation Section, NMIJ, AIST, Tsukuba, Ibaraki 305-8568 (Japan)], E-mail: n.takata@aist.go.jp; Kurosawa, T. [Ionizing Radiation Section, NMIJ, AIST, Tsukuba, Ibaraki 305-8568 (Japan); Begum, A. [Department of Physics, BUET, Dhaka-1000 (Bangladesh); Sugita, T. [Science System Laboratory, 1342-6 Tomobe, Ibaraki 309-17 (Japan)

    2007-09-21

    Values of physical parameters and correction factors essential for the absolute measurement of air kerma in {sup 137}Cs and {sup 60}Co {gamma}-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 {gamma}-ray energy is reduced and is equal to 0.09 for {sup 137}Cs {gamma}-rays in a spherical ionization chamber of cavity diameter 12 cm. Correction factors for {gamma}-ray attenuation in chamber walls and those for the contribution of scattered {gamma}-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. Calculation of the uncertainty associated to the result of entrance surface air kerma for conventional radiology patients

    International Nuclear Information System (INIS)

    Radiation doses from diagnostic radiology are the largest contribution to the collective dose and the use of guidance (reference levels) has proven to be a tool for optimization of protection. Recently, with the support of the International Atomic Energy Agency (IAEA), eight countries of the Latin-American region have been working together on a programme to test methodologies for determining preliminary values of guidance levels for X-ray chest, lumbar spine and breast examinations. The approach used was to obtain entrance surface air kerma from measurements of X-ray tube outputs, corrected for distance and backscatter and later for real exposure parameters used with patients. For quality control, some of these values for a reduced number of patients were compared with direct TLD measurements directly placed on the patient during exposure. Given the number of parameters involved in the two methods, relatively large differences are deemed to be found in the comparison. The only way of deciding if measurements and calculations are outliers, for example, due to a systematic error or a mistake, is to compare these differences with the combined uncertainty. The aim of this paper is to present (in a detailed way) the methodology used in the pilot program ARCAL LXXV, the analyses of data performed within the survey and the estimated uncertainty. The parameters analyzed were: precision of the readings, positioning of the detector, reproducibility of the mAs and kV, long term stability of the instrument, radiation quality, kerma rate, radiation incidence, field size and field homogeneity, calibration factor of the equipment, temperature and pressure measurement, X-ray tube output curve adjustment, backscatter factor and focus-patient distance. The combined standard uncertainty for Ke in chest radiography in adult patients of standard complexion, was 12%, and the expanded uncertainty (k=2) was 24%. (author)

  14. Development of a primary standard in terms of reference air kerma rate for 125I brachytherapy seeds

    International Nuclear Information System (INIS)

    The LNE-LNHB is currently developing the French primary standard in low dose rate brachytherapy. The method is based on a free-in-air ionization chamber for 125I seeds. Such sealed radioactive sources are used for treatment of ophthalmic and prostatic cancers. Low dose rate brachytherapy seeds are of small size, about 0.8 mm in diameter and 4.5 mm in length, cylindrically shaped and of complex internal design. This causes an anisotropy of emission in both planes, longitudinal and transverse. The reference air kerma rate is theoretically defined in this latter plane at a point positioned in a small volume of air at a one meter distance from the source center, the source and the air volume being surrounded by vacuum. To overcome the difficulties linked to a transversal anisotropic emission and to an expected low signal-to-noise ratio, a circular ring-shaped free-in-air ionization chamber has been designed. The 125I source seed is placed at the center of this ring detector in a tube of a low attenuated material. This paper presents an extended characterization of the circular ring-shaped free-in-air ionisation chamber. This one deals with the signal-to-noise ratio optimization, the detection volume assessment (taking into account the electric field distribution within it) and the sensitivity of the measurement linked to the source positioning. Furthermore, the correction factors to apply to the measurement results are described and their estimation esults are described and their estimation using Monte Carlo codes of particle transport are presented for the Bebig iodine seed sources, referenced I125 S16

  15. Attenuation factors in terms of air kerma to ambient dose equivalent and effective dose for diagnostic X rays rooms

    International Nuclear Information System (INIS)

    In the present study, the attenuation of the quantities fluence and air kerma free-in-air by various layers of lead was compared with that of the quantities effective dose, E, and ambient dose equivalent, H*(d). This work aims to calculate the attenuation factors from 50 kV, 125 kV and 150 kV of X ray beams used for medical diagnostic, after transmission through barriers of lead. The X ray qualities used were those recommended by the Birch and Marshall for primary diagnostic X rays. Several lead layers were irradiated with a 50 cm x 50 cm field of primary X ray spectra. The transmitted spectra were calculated to obtain the attenuation factors for beams found in radiodiagnostic services. The calculations were done using the MCNPX Monte Carlo code and voxel model MAX. The values obtained were compared with data derived from the literature. In addition, attenuation factors for X ray qualities after penetration of lead layers were studied to get data which might be of interest in shielding of diagnostic rooms. (author)

  16. Determination of air-kerma strength for the 192Ir GammaMedplus iX pulsed-dose-rate brachytherapy source

    International Nuclear Information System (INIS)

    Purpose: Pulsed-dose-rate (PDR) brachytherapy was originally proposed to combine the therapeutic advantages of high-dose-rate (HDR) and low-dose-rate brachytherapy. Though uncommon in the United States, several facilities employ pulsed-dose-rate brachytherapy in Europe and Canada. Currently, there is no air-kerma strength standard for PDR brachytherapy 192Ir sources traceable to the National Institute of Standards and Technology. Discrepancies in clinical measurements of the air-kerma strength of the PDR brachytherapy sources using HDR source-calibrated well chambers warrant further investigation.Methods: In this research, the air-kerma strength for an 192Ir PDR brachytherapy source was compared with the University of Wisconsin Accredited Dosimetry Calibration Laboratory transfer standard well chambers, the seven-distance technique [B. E. Rasmussen et al., “The air-kerma strength standard for 192Ir HDR sources,” Med. Phys. 38, 6721–6729 (2011)], and the manufacturer's stated value. Radiochromic film and Monte Carlo techniques were also employed for comparison to the results of the measurements.Results: While the measurements using the seven-distance technique were within + 0.44% from the manufacturer's determination, there was a + 3.10% difference between the transfer standard well chamber measurements and the manufacturer's stated value. Results showed that the PDR brachytherapy source has geometric and thus radiological qualities that exhthus radiological qualities that exhibit behaviors similar to a point source model in contrast to a conventional line source model.Conclusions: The resulting effect of the pointlike characteristics of the PDR brachytherapy source likely account for the differences observed between well chamber and in-air measurements

  17. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the PTB and the BIPM

    Science.gov (United States)

    Kessler, C.; Allisy-Roberts, P. J.; Selbach, H. J.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate (RAKR) for 192Ir high dose rate (HDR) brachytherapy sources of the Physikalisch-Technische Bundesanstalt (PTB), Germany, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the PTB in September 2011. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the PTB and the BIPM standards for reference air kerma rate, is 1.0003 with a combined standard uncertainty of 0.0099. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the NIM, China, and the BIPM in 137Cs gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Li, D.; Wang, P.

    2015-01-01

    A direct comparison of the standards for air kerma of the National Institute of Metrology (NIM), Beijing, China, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in September 2014. The comparison result, evaluated as a ratio of the NIM and the BIPM standards for air kerma, is 0.9967 with a combined standard uncertainty of 2.1 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  19. NOTE: Room scatter studies in the air kerma strength standardization of the Amersham CDCS-J-type 137Cs source: a Monte Carlo study

    Science.gov (United States)

    Palani Selvam, T.; Rajan, K. N. Govinda; Nagarajan, P. S.; Bhatt, B. C.; Sethulakshmi, P.

    2002-05-01

    Corrections for room scatter, [ksc(d, H)]RM, as a function of source-to-detector distance, d, and source-to-floor-height, H, and also departure from constant room scatter, ksl, have been computed for rooms of various sizes using Monte Carlo methods for air kerma strength standardization of the Amersham CDCS-J-type 137Cs brachytherapy source. These corrections will also be applicable to any type of 137Cs source that may be considered for standardization. It was found that, depending upon the relative position of the source with respect to the surrounding concrete scattering surfaces (side walls, floor and ceiling) and different set of d values, the assumption of constant room scatter overestimated the air kerma strength, Sk, by between 0.2% and 0.6%.

  20. Room scatter studies in the air kerma strength standardization of the Amersham CDCS-J-type 137Cs source: a Monte Carlo study

    International Nuclear Information System (INIS)

    Corrections for room scatter, [ksc(d, H)]RM, as a function of source-to-detector distance, d, and source-to-floor-height, H, and also departure from constant room scatter, ksl, have been computed for rooms of various sizes using Monte Carlo methods for air kerma strength standardization of the Amersham CDCS-J-type 137Cs brachytherapy source. These corrections will also be applicable to any type of 137Cs source that may be considered for standardization. It was found that, depending upon the relative position of the source with respect to the surrounding concrete scattering surfaces (side walls, floor and ceiling) and different set of d values, the assumption of constant room scatter overestimated the air kerma strength, Sk, by between 0.2% and 0.6%. (author)

  1. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the PTB, Germany and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the PTB, Germany and the BIPM in the low-energy X-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 2.1 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  2. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the PTB, Germany and the BIPM in medium-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the PTB, Germany and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the expanded uncertainty (k = 2) of the comparison of 5.0 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  3. Measuring instruments of the Physikalisch-Technische Bundesanstalt for realization of the units of the dosimetric quantities standard ion dose, photon-equivalent dose and air-kerma

    International Nuclear Information System (INIS)

    The realization of the units of the dosimetric quantities exposure, air-kerma and photon-equivalent dose is an important task of the Physikalisch-Technische Bundesanstalt. The report describes the measuring instruments and other technical equipment as well as the determination of the numerous corrections needed. All data and correction factors required for the realization of the units mentioned above are given in many diagrams and tables. (orig.)

  4. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the ENEA, Italy and the BIPM in medium-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the ENEA, Italy and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the expanded uncertainty (k = 2) of the comparison of 6.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  5. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the VSL, Netherlands and the BIPM in mammography x-rays

    International Nuclear Information System (INIS)

    A first key comparison has been made between the air-kerma standards of the VSL and the BIPM in mammography x-ray beams. The results show the standards to be in agreement within the standard uncertainty of 5.7 parts in 103. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  6. Comparison of the air kerma standards of the IAEA and the BIPM in mammography x-rays

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Czap, L.; Csete, I.; Gomola, I.

    2013-01-01

    The Dosimetry Laboratory of the International Atomic Energy Agency (IAEA), Seibersdorf, Austria, calibrates reference standards in mammography x-ray beams for IAEA/WHO SSDL Network members (more than 80 laboratories worldwide). As a signatory of the Mutual Recognition Arrangement (CIPM MRA), the IAEA laboratory maintains a Quality Management System (QMS) complying with ISO 17025 and requires updated 'supporting evidence' for its dosimetry calibration and measurement capabilities (CMC), first published in Appendix C of the CIPM MRA key comparison database in 2007. For this purpose, an indirect comparison has been made between the air kerma standards of the IAEA and the Bureau International des Poids et Mesures (BIPM) in the mammography x-ray range from 25 kV to 35 kV, using as transfer instruments two thin-window parallel-plate ionization chambers belonging to the IAEA. The IAEA and BIPM standards for mammography x-rays are shown to be in agreement within the standard uncertainty of the comparison of 5.5 parts in 103. This agreement can be used to support the calibration and measurements capabilities of the IAEA listed in Appendix C of the key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Coomet Project 445: Comparison of National Measurement Standards of Air Kerma for Cs-137 Gamma Radiation at Protection Level

    International Nuclear Information System (INIS)

    A COOMET supplementary comparison of the national measurement standards of air kerma for Cs-137 gamma radiation at protection level (?10 mGy/h) was carried out between May 2011 and February 2013. Participants were VNIIM (Russia), BelGIM (Belarus), CPHR (Cuba), GEOSTM (Georgia), INSM (Moldova), NSC-'IM' (Ukraine), SMU (Slovakia), PTB (Germany), BIM (Bulgaria), VMT/FTMC (Lithuania) and the International Atomic Energy Agency (IAEA). The PTB acted as the pilot laboratory. The comparison reference value (CRV) was obtained as the mean of the results obtained by PTB and VNIIM, both of which had previously taken part in the key comparison BIPM-RI (I)-K5. Results will be published in Appendix B of the BIPM key comparison database (KCDB) using the identifier COOMET.RI(I)-S1 as soon as the Draft B report is accepted. The comparison was organized within an extended COOMET project (identified as Project 445/DE/08), the aim of which was not only to compare national standards but also for educational purposes. Some of the participants had taken part in such a comparison for the first time and, therefore, an introductory seminar was held at PTB in May 2011. The seminar was open for participation also to those countries of the COOMET region which did not participate in the comparison and to nonMRA signatories and countries without an approved quality management system in order to acquire measurement routine and theoretical as well as organizational knowledge for future comparisons. The main goal of this seminar was to prepare the participants for the procedure of having entries accepted for the CMC list in the metrological area of Ionising Radiation, Section I, x and gamma rays

  8. Intercomparison of the air kerma and absorbed dose to water therapy calibrations provided by NRPA and CPRH SSDLs

    International Nuclear Information System (INIS)

    The primary goal of any calibration laboratory is to routinely provide calibration services of the highest accuracy. To this end, the laboratory should be equipped with measuring standards of the highest metrological quality traceable to the international measuring system, should establish the appropriate calibration conditions and implement good measuring and working practices. In the case of the Secondary Standard Dosimetry Laboratory (SSDL) members of the IAEA/WHO Network of SSDLs, a great deal of the service quality relies on the appropriate laboratory design and implementation of the recommended calibration practices. Different approaches have been used by SSDLs to guarantee the traceability of the reference standard to the international measurement system. These include calibration of their standards at the IAEA Dosimetry Laboratory, direct calibration at a primary standards laboratory or at a national calibration laboratory. The stability of reference and working standards is usually checked by means of radioactive check source measurements. The most comprehensive way that a laboratory could test its overall measurement competence is by taking part in comparisons with other laboratories of the same or higher metrological level. Regular efforts have been done at the regional scale by organizing such intercomparison exercises where the evaluation of the accuracy of secondary standards or the validation of new calibration methods has been the main objectives. Perhmethods has been the main objectives. Perhaps, the most important contribution to the assessment of SSDLs quality has been the periodical external measurement audit provided by the IAEA during the last years. Mos of these efforts have, however, only been focused on in-air and recently in-water calibration at the 60Co radiation quality. An intercomparison of the therapy calibration services available at the SSDLs of the Norwegian Radiation Protection Authority (NRPA) and of the Center for Radiation Protection and Hygiene (CPHR) was organized in February 2000. The comparison comprised the calibration of a field class ionization chamber in terms of air kerma at low and medium-energy kilo voltage X-ray qualities and 60Co as well as the calibration in terms of absorbed dose to water (at 60Co radiation quality). The intercomparison represents for the CPHR the validation of the newly implemented calibration service at X-ray qualities. The NRPA SSDL has in recent years participated in EUROMET and IAEA dosimetry intercomparisons with satisfactory results. Experiences derived from the present comparison are discussed and summarized in this report. Recommendations to the SSDL members of the IAEA/WHO Network in order to encourage regional cooperation by organizing similar intercomparison exercises as well as the possibility for the IAEA to extend the present audit services, to cover certain X-ray beam qualities, are also commented

  9. Proposed specification for a primary standard of air kerma for sup 6 sup 0 Co, sup 1 sup 3 sup 7 Cs and sup 1 sup 9 sup 2 Ir gamma-ray sources

    CERN Document Server

    Angliss, R; Nutbrown, R

    2001-01-01

    The three cavity chambers, the mean response of which constitutes the primary standard of air kerma for sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays in the United Kingdom, have been in continuous, almost daily, use at the National Physical Laboratory (NPL) since 1956. These chambers were initially designed for use with 2 MV X-rays at therapy level air kerma rates. However since 1978 they have also been used for protection level air kerma rates, initially, with X-rays generated at 1 MV and 2 MV and more recently with sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays. They have been used for therapy level air kerma calibrations with sup 6 sup 0 Co gamma-rays since 1997 following the demise of the NPL 2 MV Van de Graaff generator. This report describes the proposals for a new primary standard and the methods that will be used to give a better performance than the present standard when used with air kerma rates from as high as 1 Gy min sup - sup 1 down to 10 mGy hr sup - sup 1. The design will also seek to...

  10. Revised comparison of the standards for air kerma of the ENEA-INMRI and the BIPM for 60Co gamma rays

    International Nuclear Information System (INIS)

    In 1998 a comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 60Co radiation. The comparison result, declared in 2003, is 1.0044 (0.0026) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the expanded uncertainty (k = 2). (authors)

  11. Construction of a laboratory for the implantation of primary standardization of the magnitude kerma in the air for the X-ray beams used in mammography; Construcao de um laboratorio para a implantacao da padronizacao primaria da grandeza kerma no ar para os feixes de raios X empregados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, W.L.; Magalhes, L.A.A.M.F.; Peixoto, J.G.P., E-mail: wagnerlc@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    Aiming to diminish the uncertainty in each phase of the metrological chain, and the uncertainty in dosimetry processed at the X-ray beam applied in the mammography, is necessary that the LNMRI/IRD to develop a reference primary standard for the absolute form to the magnitude kerma in the air

  12. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy; Calculo dos fatores de conversao de Kerma no ar para equivalente de dose ambiental em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Marco Antonio Frota

    2000-03-01

    This work aims to estimate the average conversion factor of Kerma in air to H {sup *} (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm{sup 2}, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  13. Kerma in the air at entry surface in thorax pediatric examinations at public hospital in Parana, Brazil; Kerma no ar na superficie de entrada em exames pediatricos de torax em hospital publico no Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Amanda; Porto, Lorena; Bunick, Ana; Paschuk, Sergei; Denyak, Valeriy, E-mail: schelin@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Schelin, Hugo; Tilly, Joao, E-mail: joao.tilly@derax.com.b [DERAX Desenvolvimento Radiologico, Curitiba, PR (Brazil); Khoury, Helen, E-mail: hjkhoury@gmail.co [Universidade Federal de Pernambuco (DOIN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Dosimetria e Instrumentacao Nuclear; Ferreira, Jose [Universidade Estadual do Oeste do Parana (UNIOESTE), Cascavel, PR (Brazil)

    2011-07-01

    This work consisted in the evaluation of the entrance skin air kerma (ESAK) in pediatric chest x-ray examinations. A study of 186 exams in anterior-posterior, posterior-anterior and lateral projections was carried out for patients with ages ranging from 0 to 15 years. The ESAK was measured with the DoseCal software and Li-Fl thermoluminescent dosimeters. The results were compared with measurements done recently at the same place and with the reference dose values established by the European Community. It was observed that the optimization of the technique and the routine changes suggested in the previous study were not maintained. The charge (mAs) and the ESAK values found in the present study were much higher than the previous one, and the voltage (kVp) values found was lower. The results suggest that the implementation of the Quality Assurance Program could adequate these parameters to the established levels and keep the pediatric examinations more uniform. (author)

  14. Determination of air kerma rate at IEN/CNEN, due to cyclotron RDS-111 and the radioactive waste deposit

    International Nuclear Information System (INIS)

    The Instituto de Engenharia Nuclear - IEN - (Institute of Nuclear Engineering) is a branch of CNEN (Comissao Nacional de Energia Nuclear), the national regulatory authority, established in 1962 with the commitment to carry out research aiming the nuclear technological development in Brazil. In 1995, PERES, S.S., carried out measurements, using thermoluminescent dosemeter of CaSO4: Dy and LiF: Mg, Ti; and a Saphymo SRAT SPP2-NF scintillation detector, for the evaluation of the effect on environment of the activities developed in the IEN. Since that time, the Institute Radioactive Waste Deposit stores a greater amount of radioactive waste, accumulated during the operational life of IEN, and also a new cyclotron particle accelerator has been installed, the RDS-111, in operation since 2003, which is currently used for the production 18F - fluorodeoxyglucose, FDG, a radiopharmaceutical of great use in Positron Emission of Tomography (PET). In this work, measurements of ambient kerma have been carried out, using thermoluminescent dosemeter of LiF:Mg, Cu, P, TLD - 100 H, manufactured by Harshaw, and the same scintillation detector used by PERES, with the intention of verify the contribution of these two radioactive installations in the values of the ambient kerma of the IEN. The results have shown good conformity among the data obtained with the TLD and scintillation detectors. Moreover, the variation of ambient kerma of IEN presently found to the measured value bEN presently found to the measured value by PERES in 1995 was not significant. (author)

  15. Evaluation of wall correction factor of INER's air-kerma primary standard chamber and dose variation by source displacement for HDR ¹?²Ir brachytherapy.

    Science.gov (United States)

    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

  16. Estimation of mean-glandular dose from monitoring breast entrance skin air kerma using a high sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeter system in mammography

    International Nuclear Information System (INIS)

    Estimation of mean-glandular dose (MGD) has been investigated in recent years due to the potential risks of radiation-induced carcinogenesis associated with the mammographic examination for diagnostic radiology. In this study, a new technique for immediate readout of breast entrance skin air kerma (BESAK) using high sensitivity MOSFET dosimeter after mammographic projection was introduced and a formula for the prediction of tube output with exposure records was developed. A series of appropriate conversion factors was applied to the MGD determination from the BESAK. The study results showed that signal response of the high sensitivity MOSFET exhibited excellent linearity within mammographic dose ranges, and that the energy dependence was less than 3% for each anode/filter combination at the tube potentials 25-30 kV. Good agreement was observed between the BESAK and the tube exposure output measurement for breasts thicker than 30 mm. In addition, the air kerma estimated from our prediction formula provided sufficient accuracy for thinner breasts. The average MGD from 120 Asian females was 1.5 mGy, comparable to other studies. Our results suggest that the high sensitivity MOSFET dosimeter system is a good candidate for immediately readout of BESAK after mammographic procedures

  17. Use of a new breast phantom for dosimetric determination of incident air kerma and mean glandular dose in digital mammography system

    International Nuclear Information System (INIS)

    Mammography aims to achieve a high image quality associated with a dose in the patient as low as feasible. Values of average glandular dose, DG, can be obtained by means of two dosimetric methods: one based on the measurement of incident air kerma, Ki, associated with tables of conversion factors that depend on the half value layer, the thickness and the glandular composition of the breast. And the one that makes the measure directly to thermoluminescent dosimeters, TLDs, placed in a new dosimetric phantom. Thus, this study aims to determine the incident air kerma (Ki) and average glandular dose (DG) applied on patients in a digital mammography system (DR) using the phantom dosimetric developed. Another objective is to compare the results with the values of DG determined from Ki and also with the values of Ki and DG indicated in the examination of each patient by the digital mammography unit. The result of the average values measured in 77 patients with compressed breast thickness within the range of 5.5 cm and 6.5 cm, shows that the Ki values ranged around 7.9% between the methods of action. The result of the values of DG ranged around 14.7% between the two methods of action. It is observed that the estimate of DG by the software is higher than the values measured with the dosimetric phantom. (author)

  18. Comparisons of the standards for air kerma of the PTB and the BIPM for 60Co and 137Cs gamma radiation

    International Nuclear Information System (INIS)

    Direct comparisons of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB, Germany) and of the Bureau International des Poids et Mesures (BIPM) were carried out in the 60Co and 137 Cs radiation beams of the BIPM in 2000. The results, expressed as ratios of the PTB and the BIPM standards for air kerma, indicate a relative difference in 60Co of 9.9 x 10-3 with a combined standard uncertainty of 1.8 x 10-3, and in 137Cs of 6.4 x 10-3 with a combined standard uncertainty of 2.8 x 10-3. The earlier comparisons in 60Co ? rays made in 1971 (direct) and 1989 (indirect) resulted in an agreement of the two standards within 2 x 10-3. The differences obtained now are due to the application of new correction factors for wall effects and point source non-uniformity of the beam, kwall and kpn, for the PTB standards, which were calculated using Monte Carlo methods. (authors)

  19. A PROPOSED UNIFORM AIR POLLUTION INDEX

    Science.gov (United States)

    A uniform air pollution index for the U.S. is proposed. The index was developed from ten criteria identified in a survey of all the air pollution indices currently in use in the U.S. and Canada. The proposed index, named the Pollutant Standards Index (PSI), was designed to overco...

  20. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the BEV, Austria and the BIPM in mammography x-rays

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Steurer, A.; Tiefenboeck, W.; Bauer, M.

    2015-01-01

    A first key comparison has been made between the air-kerma standards of the BEV and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the combined standard uncertainty of 3.4 parts in 103. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the VSL, Netherlands and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the VSL, Netherlands and the BIPM in the low-energy X-ray range. The results for the direct comparison show the standards to be in general agreement for the 10 kV, 30 kV and 25 kV radiation qualities at the level of the expanded uncertainty for the comparison of 6.6 parts in 103. For the 50 kV qualities, differences approaching twice the expanded uncertainty are observed. The results for an indirect comparison made at the same time are not consistent with the direct results, in the worst case (10 kV) differing by 4 parts in 102. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  2. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NMIJ, Japan and the BIPM in low-energy x-rays

    Science.gov (United States)

    Burns, D. T.; Kessler, C.; Tanaka, T.; Kurosawa, T.; Saito, N.

    2015-01-01

    A key comparison has been made between the air-kerma standards of the NMIJ and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 3.0 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the BEV, Austria and the BIPM in medium-energy x-rays

    Science.gov (United States)

    Burns, D. T.; Kessler, C.; Steurer, A.; Tiefenboeck, W.; Bauer, M.

    2015-01-01

    A key comparison has been made between the air-kerma standards of the BEV, Austria and the BIPM in the medium-energy x ray range. The results show the standards to be in general agreement at the level of the expanded uncertainty (k = 2) of the comparison of 6.4 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  4. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the BEV, Austria and the BIPM in low-energy x-rays

    Science.gov (United States)

    Burns, D. T.; Kessler; Steurer, A.; Tiefenboeck, W.; Bauer, M.

    2015-01-01

    A key comparison has been made between the air-kerma standards of the BEV and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the combined standard uncertainty of 4.7 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  5. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    Energy Technology Data Exchange (ETDEWEB)

    Crosbie, Jeffrey C.; Rogers, Peter A. W. [Department of Obstetrics and Gynaecology, University of Melbourne, The Royal Women' s Hospital, Parkville, Victoria 3052 (Australia); Stevenson, Andrew W. [CSIRO Materials Science and Engineering, Clayton, Victoria 3169 (Australia); Hall, Christopher J. [Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168 (Australia); Lye, Jessica E. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085 (Australia); Nordstroem, Terese [KTH Royal Institute of Technology, Stockholm SE-100 44 (Sweden); Midgley, Stewart M. [School of Physics, Monash University, Clayton, Victoria 3800 (Australia); Lewis, Robert A. [Department of Medical Imaging and Radiation Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation curve on the IMBL using a simple experimental method, namely, HVL measurements. The HVL measurements strongly supports the x-ray beam spectrum, which in turn has a profound effect on x-ray dosimetry.

  6. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD

    International Nuclear Information System (INIS)

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air ??·, dose speed absorbed in water D?·, and speed absorbed dose in air D?·, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups ?? and that of long term by means of the standard deviation among groups ??, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) ??·, in radiation field of 60Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) D?),en radiation field of 60Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of 90Sr-90Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases ??, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of ??. For example with sizes of subgroup ?? 30 data, or with a number of subgroups ??. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the determinations of the temperature to diminish their influence in the U. c. The percentage difference of the magnitudes dosemeters carried out by it patterns are consistent with U certain. However, it is necessary to diminish the uncertainty in the physical factors different to ?? and ?? for the one case of the primary patterns; because these they should be those of smaller value of U. d. In the case of the secondary patterns and tertiary for the realization of the??· is necessary to determine the corrections explicitly for recombination and polarization; and to analyze their contribution in the U. e. It is necessary to recover the tracking for the mensurations of the humidity. f. It is recommended to continue the control mensurations for each pattern, taking its the least a measure every fifteen days, that it corresponds at two measured for month and 24 at the year. g. The operation of the air conditioned perturb the measurement for such as it recommends not to use it, and alone to leave in balance the chamber with the air of the engine room. (Author)

  7. Neutron kerma factors, and water equivalence of some tissue substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad, 580003 (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    The kerma factors and kerma relative to air and water of 24 compounds used as tissue substitutes were calculated for neutron energy from 2.53 x 10{sup -8} up to 29 MeV. The kerma ratio of the tissue substitutes relative to air and water were calculated by the ratio of kerma factors of the tissue substitute to air and water respectively. The water equivalence of the selected tissue substitutes was observed above neutron energies 100 eV. Kerma ratio relative to the air for Poly-vinylidene fluoride and Teflon are found to be nearest to unity in very low energy (up to 1 eV) and above 63 eV respectively. It was found that the natural rubber as a water equivalent tissue substitute compound. The results of the kerma factors in our investigation shows a very good agreement with those published in ICRU-44. We found that at higher neutron energies, the kerma factors and kerma ratios of the selected tissue substitute compounds are approximately same, but differences are large for energies below 100 eV. (Author)

  8. Neutron kerma factors, and water equivalence of some tissue substitutes

    International Nuclear Information System (INIS)

    The kerma factors and kerma relative to air and water of 24 compounds used as tissue substitutes were calculated for neutron energy from 2.53 x 10-8 up to 29 MeV. The kerma ratio of the tissue substitutes relative to air and water were calculated by the ratio of kerma factors of the tissue substitute to air and water respectively. The water equivalence of the selected tissue substitutes was observed above neutron energies 100 eV. Kerma ratio relative to the air for Poly-vinylidene fluoride and Teflon are found to be nearest to unity in very low energy (up to 1 eV) and above 63 eV respectively. It was found that the natural rubber as a water equivalent tissue substitute compound. The results of the kerma factors in our investigation shows a very good agreement with those published in ICRU-44. We found that at higher neutron energies, the kerma factors and kerma ratios of the selected tissue substitute compounds are approximately same, but differences are large for energies below 100 eV. (Author)

  9. Estudo comparativo da qualidade da imagem e do kerma, de entrada e de saída, em simulador de tórax utilizando sistemas analógico e digitalizado CR de aquisição de imagens / Comparative study of image quality and entrance and exit air kerma measurements on chest phantom utilizing analog and CR digital imaging systems

    Scientific Electronic Library Online (English)

    Renata Matos da, Luz; Gabriela, Hoff.

    2010-02-01

    Full Text Available OBJETIVO: O processo de migração de sistemas analógicos para digitalizados, para aplicações diagnósticas, requer cuidados específicos, a fim de manter a qualidade das imagens e minimizar a dose no paciente. Este trabalho tem como objetivo analisar e comparar a qualidade da imagem e o kerma num simul [...] ador não antropomórfico de tórax gerados por sistemas analógicos e digitalizados CR. MATERIAIS E MÉTODOS: Foram analisados a qualidade da imagem e o kerma, de entrada e saída, no simulador para dois equipamentos de raios X diferentes (Siemens e Emic), com diferentes sistemas de retificação de onda (12 pulsos e alta frequência). Ambos os sistemas (analógico e digitalizado) estavam sendo utilizados no mesmo local. Foram geradas imagens em filme e em image plates. RESULTADOS: Foi observado aumento na tensão e/ou na carga transportada pelo tubo de raios X quando houve a migração para o sistema CR, para manutenção das características diagnósticas da imagem. Isto resultou em aumento de kerma coletado. CONCLUSÃO: As maiores diferenças determinadas (aumento de dose e redução da qualidade da imagem) foram observadas no equipamento com retificação de onda de 12 pulsos e transdutor de imagem CR (image plates). Abstract in english OBJECTIVE: The process of migration from analog to digital imaging system requires specific attention to preserve images quality and minimizing the dose to the patients. The present study was aimed at analyzing and comparing images quality and entrance and exist air kerma measurements in a non-anthr [...] opomorphic chest phantom with analog and CR digital imaging systems. MATERIALS AND METHODS: Two different X-ray units (Siemens and Emic) with different wave rectification systems (12-pulse and high-frequency) were utilized in a single institution along the process of migration from analog to CR digital imaging system. Images were acquired on films and image plates. RESULTS: An increase on the X-ray tube peak voltage and/or load was observed in the migration from analog to CR digital system to preserve the diagnostic quality of the image. As a result, an increase in the air kerma rate was observed. CONCLUSION: The greatest differences (increase in dose and decrease in image quality) were observed with the 12-pulse wave rectification system with the CR image transducer (imaging plates).

  10. APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.H.; Hwang, W.S. [Institute of Nuclear Energy Research, Longtan, Taiwan (China); Kotler, L.H.; Webb, D.V. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie (Australia); Buermann, L. [Physikalisch Technische Bundesanstalt, Braunschweig (Germany); Burns, D.T. [Bureau International de Poids et Mesures, 92 - Sevres (France); Takeyeddin, M. [Atomic Energy Commission, Damascus (Syrian Arab Republic); Shaha, V.V. [Bhabha Atomic Research Centre, Mumbai (India); Srimanoroth, S. [Department of Medical Sciences, Nonthaburi (Thailand); Meghzifene, A. [International Atomic Energy Agency, Vienna (Austria); Hah, S.H.; Chun, K.J. [Korea Research Institute of Standards and Science, Yusong (Korea, Republic of); Kadni, T.B. [Malaysian Nuclear Agency, Kajang (Malaysia); Takata, N. [National Metrology Institute of Japan, Tsukuba (Japan); Msimang, Z. [National Metrology Institute of South Africa, Pretoria (South Africa)

    2008-10-15

    The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. (authors)

  11. Air kerma to personal dose equivalent conversion factors for ICRU and ISO recommended slab phantoms for photons from 20 keV to 1 MeV

    International Nuclear Information System (INIS)

    The present report summarizes the studies carried out at ENEA-AMB-PRO-IRP (Institute for Radiation Protection) that were addressed to the determination of air kerma to personal dose equivalent conversion coefficients for two practical phantoms as proposed by ICRU (International Commission for Radiation Units and Measurements) and by ISO (International Standard Organization) for photon personal dosimeters' calibration procedure. The analyses, developed using the MCNP Monte Carlo code, were mainly aimed at establishing which of the two proposed phantoms better approximates the ICRU theoretical one. Furthermore a complete tabulation of the conversion coefficients is supplied for monoenergetic photon beams from 20 keV to 1 MeV as well as for the two ISO X-ray reference series Wide Spectrum and Narrow Spectrum. The study has been performed in the framework of the CEC Contract F13P-CT92-0064 'The Measurement of the Spectral and Angular Distribution of External Radiations in Workplace and Implications for Personal Dosimetry

  12. Modelling the contribution of individual radionuclides to the total gamma air kerma rate for the sediments of the Ribble Estuary, NW England

    International Nuclear Information System (INIS)

    The aim of this study was to test the performance of a published dose-rate model, investigate the contribution of individual radionuclides to the total gamma air kerma rate (GAKR) and derive external doses to man in the Ribble Estuary, NW England. GAKRs were measured and sediment cores were collected in order to determine radionuclide specific activities with depth. The latter values were used as input data for the external dose-rate model. The model has a slight tendency to over-predict the GAKR, but, on average, the model predictions fall within ±26% of the measured value. Improvements, in the present case, might be made by accounting for core shortening and variations in soil density in the input data. The model predicted that, for exposed intertidal mud sites, a range of GAKRs between 0.011 and 0.022 ?Gy h-1 was attributable to Springfields discharges alone. The contribution due to 234mPa and 234Th ranged between 20 and 60%. An excess GAKR (GAKR arising from anthropogenic emissions alone) of 0.139-0.150 ?Gy ?Gy h-1, used in conjunction with relevant habit-survey data (for a potential critical group) and conversion factors, yielded a dose to man of 0.029-0.031 mSv year-1. (author)

  13. Air kerma to HP(3) conversion coefficients for photons from 10 keV to 10 MeV, calculated in a cylindrical phantom

    International Nuclear Information System (INIS)

    In the framework of the ORAMED project (Optimization of Radiation protection for Medical staff), funded by the European Union Seventh Framework Programme, different studies were aimed at improving the quality of radiation protection in interventional radiology and nuclear medicine. The main results of the project were presented during a final workshop held in Barcelona in January 2011, the proceedings of which are available in the open literature. One of the ORAMED tasks was focused on the problem of eye-lens photon exposure of the medical staff, a topic that gained more importance especially after the ICRP decision to lower the limiting equivalent dose to 20 mSv per year. The present technical note has the scope, besides briefly summarising the physical reasons of the proposal and the practical implications, to provide, in tabular form, a set of air kerma to Hp(3) conversion coefficients based on the adoption of a theoretical cylindrical model that is well suited for reproduction of the mass and the shape of a human head. (authors)

  14. Implementation of the method air-kerma product area in KAP camera calibration with reference qualities of X-ray series at the SSDL RQR of Mexico

    International Nuclear Information System (INIS)

    The X-Ray machines, at a reference laboratory for the instrument calibration in diagnostic radiology, should compliance with the ISO requirements. Sometimes there is not available as much laboratories as needed in Latin American countries. So this project shows the KAP ionization chamber implementation method using the TRS-457 radiation quality from the IAEA at the SSDL of Mexico. The KAP instruments calibration method consists in doing a substitution comparison using a standard reference with traceability to a primary laboratory and a transmission-monitoring chamber that measures the number of photons of the X-ray primary beam. A KAP chamber calibration requires a special array that consists in collocating the chamber in two different positions of its calibration process. Then, with air kerma-area product coefficient together with a corrected electrometer measure at referential conditions, the patient dosimetry magnitudes are calculated. The dosimetry necessity at hospitals always will be in function of possessing a highly reliable calibration coefficient chamber for making these measures. That dosimetry results will help in reducing the total or partial irradiation emitted to the human body of the patient. This is how stochastic risks will be lessened due to diagnostic studies. The purpose of this project is to have a synergy with calibration for making known that the SSDL of Mexico has the technical capacity to act as a link between primary standard dosimetry laboratories and the ionizing radiation equipment users who require that their KAP chamber have traceability from the primary standard to the user. (author)

  15. APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)

    International Nuclear Information System (INIS)

    The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. (authors)

  16. Investigation of the air kerma response of spherical ionization chambers for unfolded pulse height distributions of 60Co and 137Cs using the EGS4 Monte Carlo code

    International Nuclear Information System (INIS)

    Data required for the determination of the absolute air kerma rate for 60Co and 137Cs gamma-rays using spherical cavity chambers were calculated using the EGS4 Monte Carlo system. Mass energy-absorption coefficient ratio and the stopping power ratio were calculated for a 10 cm3 primary standard graphite-walled ionization chamber from the unfolded energy pulse height distributions of 60Co and 137Cs sources. Wall correction factors and non-uniformity correction factors for two graphite and one air equivalent plastic walled ionization chambers were also calculated with EGS4 code. The wall correction factors were compared with those determined by an experimental extrapolation method. To check the accuracy of the calculations the results were compared with those obtained from other primary standard laboratories such as NIST and NRCC. For a 10 cm3 graphite ionization chamber, the mass energy-absorption coefficient ratios were 0.99917 for 60Co and 1.0004 for 137Cs. The values differed by 0.02?0.05% for 60Co and 0.11% for 137Cs from those of two laboratories. The stopping power ratios were 0.99984 for 60Co and 1.0087 for 137Cs. Comparison with NIST values showed differences of 0.06% for 60Co and 0.04% for 137Cs. The wall correction factors were obtained and they were different by 0.6?1.1% for 60Co and 137?1.1% for 60Co and 137Cs compared to the experimental linear extrapolation method. These values were compared with Monte Carlo derived values from other laboratories. The non-uniformity correction factors were also calculated and they differed from unity, the traditional value used in most standard national metrology laboratories. (author)

  17. Comparison of the air-kerma standards of the PTB and the BIPM in the low-energy X-ray range

    International Nuclear Information System (INIS)

    A direct comparison has been made between the air-kerma standards of the Physikalisch-Technische Bundesanstalt (PTB), Germany, and the Bureau International des Poids et Mesures (BIPM) in the x-ray range from 10 kV to 50 kV. Additional measurements were made at 80 kV and 100 kV to provide information on the electron-loss correction for the BIPM standard at these qualities. The comparison took place at the BIPM in March 1999 using the reference conditions recommended by the CCRI. There is general agreement at the level of one standard uncertainty, although there is a significant trend in the results between 30 kV and 50 kVa. This is in part due to the treatment of fluorescence radiation. The effect of fluorescence for the BIPM standard has been calculated using the Monte Carlo code EGSnrc and the fluorescence correction calculated in this way and the effect of including these new values in the present comparison are given. It should be noted, however, that these new correction factors for the BIPM standard have not yet been adopted. The result at 10 kV is significantly different from the others. This is not uncommon and raises a number of possibilities, for example the large corrections for air attenuation and guard wire attenuation, or unexplained aperture effects that have arisen in certain comparisons. In this respect, it is possible that the uncertainties for the 10 kV quality are underestimated. The measurements at 80 kV and 100 kV were made principally to test the correction factors for the BIPM standard, making use of the fact that the large electrode separation of the PTB PK100 chamber results in very little electron loss. (authors)

  18. Ozone - Current Air Quality Index

    Science.gov (United States)

    ... Providers | Smoke from Fires Learning Center Kids | Students | Teachers | Older Adults | Weathercasters | School Flag Program | Picture Book Apps Facebook Webcams Videos AirNow on Google Earth EnviroFlash Email ...

  19. From reference air-kerma-rate to nominal absorbed dose-rate to water Paradigm shift in photon brachytherapy: ISO new work item proposal

    International Nuclear Information System (INIS)

    Full text: Over decades, photon radiation brachytherapy (BT) has proven worldwide as an essential modality of high precision radiation oncology for certain primary tumor sites. The dosimetric uncertainty of photon brachytherapy, however, is currently much larger than in external beam radiotherapy due to several factors including: calibration to the reference air-kerma-rate K.R K.R (or air-kerma strength), dose calculation model, dosimetric functions and dose measurement complexity, besides the geometrical dose uncertainties in high dose-gradient BT-fields. In addition, many photon sources are applied with quite different dosimetric properties requiring much skill from the medical physicist. This work proposes increased accuracy of brachytherapy through improvements in source calibration and clinical dosimetry methodology. Currently, BT-photon sources are calibrated free in air, at 100 cm distance, and in terms of K.R. By calibrating BT-photon sources directly to the TG-43U1 reference point at 1 cm in water, to be named the nominal absorbed dose-rate to water, D.w,1, the number of calibration steps in the traceability chain is reduced from 6 to 4, thus reducing the expanded uncertainty in dose delivery for patient treatment. With a target combined uncertainty of ucue.w,1 primary standards, whi/sup>w,1 primary standards, which will soon become available for high energy and low energy, high and low dose-rate BT-photon sources. This is a paradigm shift that requires: international consensus, metrologic work and guidance. Thus, there is a need for an ISO standard based on and extending the AAPM TG-43U1 formalism. Taking into account the results and conclusions of the AAPM 2010 discussions, a draft for an ISO new work item proposal on Clinical dosimetry - Photon radiation sources for brachytherapy will be presented. This standardization project could be launched within ISO TC 85/SC 2/WG 22, in continuation of ISO 21439 (2009) for beta radiation sources. Clear terms and definitions are basic requirements for this standard. It is proposed that BT-photon radiation qualities need to be reclassified as: high-energy >100 keV, medium energy 40 keV to 100 keV, and low energy photons .w,1-recalibrated special transfer standards like well-type ionization-chambers) and as fast, direct reading dosemeter with high spatial and temporal resolution as required for detailed acceptance tests of BT-sources, -software, -planning, and -verification. This ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainty of this new quantity. Most standardized procedures can be given by referring to AAPM-reports and ESTRO-documents. General quality assurance issues, radiation protection and safety issues are outside the scope. Recommendations will be prepared to replace the K.R K.R by D.w,1 as basic dosimetric quantity, to become consistent with external beam radiotherapy and to reduce the dosimetric uncertainty in brachytherapy

  20. Nuclear heating constant KERMA library

    International Nuclear Information System (INIS)

    Based on evaluated nuclear data file JENDL-3, published in April 1990, we produced a nuclear group constant KERMA library for fusion nuclear group constant set FUSION-J3 instead of the KERMA library for GICX40. Neutron KERMA factors were calculated directly by considering the kinematics in collisions, called 'Direct Method'. In this method, uncertainties in calculated KERMA factors are expected to be reduced since subtraction between great numbers is not necessary as in the energy balance method. Gamma ray KERMA factors were calculated by the energy balance method. In case of gamma ray, there is no problem in calculating gamma ray KERMA by the energy balance method since gamma ray heating means energy deposition of kinetic energy in gamma ray. Produced KERMA library is applicable to fusion neutronics calculations. It is expected that highly accurate results will be obtained in nuclear heating calculations for fusion reactor designs. (author)

  1. Final report on APMP.RI(I)-K1: APMP/TCRI key comparison report of measurement of air kerma for 60Co gamma-rays

    International Nuclear Information System (INIS)

    The APMP.RI(I)-K1 key comparison of the measurement standards of air kerma for 60Co gamma-rays was undertaken by the APMP/TCRI Dosimetry Working Group between 2004 and 2006, coordinated by the Korean Research Institute of Standards and Science (KRISS). In total, 10 institutes took part in the comparison, among which 7 were APMP member laboratories. Three Farmer-type commercial cavity chambers were used as transfer chambers and circulated among the participants. All the participants carried out their measurements according to the guidelines for the comparison established by the KRISS with the cooperation of the ARPANSA. For each transfer chamber, an NMI calibration coefficient was obtained and a ratio derived by dividing by the average result from the linking laboratories, ARPANSA and NMIJ. The APMP comparison reference value for each chamber was calculated as the mean of the NMI-determined calibration coefficients divided by the average result from the linking laboratories. The results showed that the maximum difference between the APMP linked ratio of a participating NMI and the APMP reference value was 1.76 %. The measured ratios of the calibration coefficient NMI, BIPM R between the participating NMI and the BIPM via the link laboratories for the transfer chambers were obtained. The maximum expanded uncertainty of NMI, BIPM R for any participating laboratory was 2.0 %. The degree of equivalence of each participating laboratory with respect to the key coming laboratory with respect to the key comparison reference value was also evaluated. The expanded uncertainty of the difference between the results ranged from 0.5 % to 1.2 %. The pair-wise degree of equivalence between each pair of laboratories was also obtained and the largest difference of the expanded uncertainty of the difference for any pair-wise degree of equivalence was within the expanded uncertainty of the measurement for the pair of laboratories. (authors)

  2. CityAIR : a new air quality index for cities

    OpenAIRE

    Mendes, José F. G.; Silva, Lígia Torres

    2008-01-01

    Due to a generalised increase of mobility and road traffic in urban areas, the total emissions from road traffic have risen significantly, assuming the main responsibility for the disregard of air quality standards. Pollutant concentrations are evaluated through monitoring, using permanent measurement stations or mobile units, and prediction models based on emissions and meteorological conditions. In order to find an air quality index, the pollutant concentrations are comb...

  3. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams; Determinacao experimental dos coeficientes de conversao de Kerma no ar para o equivalente de dose pessoal, Hp(d), e fatores de retroespalhamento em feixes de raios-x diagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves

    2008-07-01

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm{sup 3} Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with {sup 133} Ba, {sup 241} Am and {sup 57} Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and backscatter factors were 12% and 6% respectively. (author)

  4. Kinematic kerma factors

    International Nuclear Information System (INIS)

    The HEATR module of NJOY computes heat production by energy-balance (usually); that is, it assumes that the energy available for charged-particle emission and nuclear recoil can be obtained from the available energy (E + Q) minus the energy carried away by neutrons (E/sub n/) and the energy carried away by photons (anti E/sub ?/). If there are errors in either anti E/sub n/ or anti E /sub ?/, the local heating will be incorrect. In a large enough system, this heating error will be exactly compensated for by photon energy deposition, and the correct result for total heating will be obtained. However, in very small systems where most of the photons escape, the local heating can have very large errors resulting from a lack of energy conservation in the nuclear data evaluation. Accurate values for this local heating can be computed for some reactions by kinematics (radiative capture, elastic and inelastic neutron scattering). Reactions that emit charged particles are more difficult because the ENDF/B files do not contain the required particle spectra or angular distributions. Nevertheless, it is possible to establish an upper limit for the kinematic kerma factor by assuming that such reactions emit no photons. The HEATR module has been modified to add kinematic kerma factors computed in this way to the NJOY calculational path. This means that they are available for either multigroup or Monte Carlo processing

  5. CDC WONDER: Daily Air Temperatures and Heat Index

    U.S. Department of Health & Human Services — The Daily Air Temperature and Heat Index data available on CDC WONDER are county-level daily average air temperatures and heat index measures spanning the years...

  6. Key Comparison APMP.RI(I)-K2 of air kerma standards for the CCRI reference radiation qualities for low-energy x-rays, including a supplementary comparison for the ISO 4037 narrow spectrum series

    International Nuclear Information System (INIS)

    An indirect comparison was performed between nine national standards for air kerma for the CCRI radiation qualities from 10 kV to 50 kV (APMP.RI(I)-K2) and for the ISO 4037 narrow spectrum series (15 kV and 40 kV). Among the nine institutes that participated in the comparison, seven institutes were APMP member laboratories. Three commercially available thin window parallel plate ionization chambers were used as transfer instruments and circulated among the participants. The pilot laboratory, the NMIJ/AIST, served also as the link to the corresponding BIPM.RI(I)-K2 comparison. The results show general agreement within the combined uncertainties, although certain results for Nuclear Malaysia, the BARC and the OAP show larger differences. (authors)

  7. Comparison of factors given in ICRU Report 23 and IAEA TRS 277 for converting from exposure/air kerma to absorbed dose to water for medium energy X-rays

    International Nuclear Information System (INIS)

    New values of the factors required to convert the reading of an ionization chamber calibrated in terms of air kerma (or exposure) to absorbed dose to water for medium energy X-rays were given in a Code of Practice published by the IAEA in 1987. These factors differ by a maximum of 12.5% at 0.15 mm Cu HVL from those given in ICRU Report 23. This paper discusses the difference between the ICRU and IAEA conversion factors and forms the basis of the recommendation of the IPSM low and medium energy X-ray dosimetry working party, that dosimetry in the U.K. should continue to be based on ICRU Report 23 and therefore on the current HPA Code of Practice. (author)

  8. Neutron KERMA factors of Human Tissues

    OpenAIRE

    Martin-martin, A.; Gutierrez-villanueva, J. L.; Barquero, R.; Manzanares-acun?a, E.; Vega-carrillo, H. R.

    2007-01-01

    A program to calculate the neutron KERMA in human tissues has been developed. The program was developed in Mathcad and contains the neutron kerma factors of those elements that are present in different human tissues. Having the elemental composition of any human tissue the neutron kerma can be easily calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic. Neutron kerma for adipose and muscle tissue for normal...

  9. A new method for calculation of an air quality index

    Energy Technology Data Exchange (ETDEWEB)

    Ilvessalo, P. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1995-12-31

    Air quality measurement programs in Finnish towns have expanded during the last few years. As a result of this it is more and more difficult to make use of all the measured concentration data. Citizens of Finnish towns are nowadays taking more of an interest in the air quality of their surroundings. The need to describe air quality in a simplified form has increased. Air quality indices permit the presentation of air quality data in such a way that prevailing conditions are more easily understandable than when using concentration data as such. Using an air quality index always means that some of the information about concentrations of contaminants in the air will be lost. How much information is possible to extract from a single index number depends on the calculation method. A new method for the calculation of an air quality index has been developed. This index always indicates the overstepping of an air quality guideline level. The calculation of this air quality index is performed using the concentrations of all the contaminants measured. The index gives information both about the prevailing air quality and also the short-term trend. It can also warn about the expected exceeding of guidelines due to one or several contaminants. The new index is especially suitable for the real-time monitoring and notification of air quality values. The behaviour of the index was studied using material from a measurement period in the spring of 1994 in Kaepylae, Helsinki. Material from a pre-operational period in the town of Oulu was also available. (author)

  10. Comparison of air kerma-length product measurements between the PTB and the IAEA for x-radiation qualities used in computed tomography (EURAMET.RI(I)-S12, EURAMET project #1327)

    Science.gov (United States)

    Csete, István; Büermann, Ludwig; Alikhani, Babak; Gomola, Igor

    2015-01-01

    A comparison of air kerma-length product determinations for standard radiation qualities defined for use in computed tomography was performed between the PTB and the IAEA as EURAMET project #1327, registered in the KCDB as the EURAMET.RI(I)-S12 comparison. A pencil type reference-class ionization chamber of the IAEA and the three RQT beam qualities established according to the IEC standard 61627:2005 were selected for the comparison. The calibration coefficients for the transfer chamber in terms of Gycm/C at the PTB and the IAEA using the partial irradiation method recommended in the IAEA TRS 457 were determined. The results show the calibration coefficients of both laboratories were in a very good agreement of about 0.2 % well within the estimated relative standard uncertainty of the comparison of about 0.8 %. Residual correction due to the additional aperture required for partial irradiation of pencil chambers and feasibility of the full irradiation method were also studied. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. The influence of micro location on the air freezing index

    Directory of Open Access Journals (Sweden)

    Mazi? Branko

    2004-01-01

    Full Text Available In this paper are exposed research results of air freezing index values occurring in area of Bosnia and Herzegovina. Theoretic probabilities of air freezing index occurrence are calculated, based on data of 26 meteorological stations, in order to determine its return periods of appearing (the probability of air freezing index appearance average once in period considered. To this purpose five the most frequent in praxis theoretic distribution functions are used: GAUSS, GALTON, LOG-PEARSON, PEARSON and GUMBEL. As the most appropriate function for all meteorogic stations the LOG-PEARSON was selected because it on the best way approximates values of calculated air freezing index. Regarding to influence of micro location on the value of air freezing index some independent parameters of location which are measurable (variables and have supposed influence, are took in analysis. To this purpose the mathematic model of multi variant regression analysis was used and the regression equation of the associated influence of independent parameters was determined. Using this discovered equation designers of road pavement can for each micro-location cutted by the road line, calculate the air freezing index and check the pavement structure on the harmful freezing effects.

  12. Neutron KERMA factors of human tissues

    International Nuclear Information System (INIS)

    A program to calculate the neutron KERMA in human tissues has been developed. The program was developed in Mathcad and contains the neutron kerma factors of those elements that are present in different human tissues. Having the elemental composition of any human tissue the neutron kerma can be easily calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic. Neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large (au)

  13. Calculation of neutron kerma in tissues

    International Nuclear Information System (INIS)

    Neutron kerma of normal and tumor tissues has been calculated using the tissues elemental concentration. A program developed in Math cad contains the kerma factors of C, H, O, N, Na, Mg, P, S, Cl, K, etc. that are in normal and tumor human tissues. Having the elemental composition of any human tissue the neutron kerma can be calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic, also neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large. (Author)

  14. Evaluation of kerma rate in radioactive waste disposal; Avaliacao da taxa de kerma em deposito de rejeitos radioativos

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Rodolfo O.; Silva, Joao C.P.; Santos, Joao R. dos, E-mail: oliveira@ien.gov.br, E-mail: jcarlos@ien.gov.br, E-mail: regis@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This study aims to assess the progression of kerma rate levels in the air due to the increase of collection, storing and storage of radioactive waste in the new building (after expansion) of the radioactive waste disposal (RWD) of the Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Brazil. This review is carried out every six months at IEN with thermoluminescent dosimeter lithium fluoride LiF: Mg, Cu, P (TLD-100H). Here are the average values of kerma rate for the period 2008- 2012. In this context, the methodology used for selection and choices of detectors used in dosimeters is presented. The detectors were chosen through homogeneity criteria of the pack, standardization factor and coefficient of variation (CV%). The monitoring points and the exposure time of the detectors are chosen considering various factors, including the rate of occupation and indoor and outdoor positions to RWD. These evaluations showed that the contribution of the new waste disposal in increasing kerma rate of IEN, has proved to be insignificant, that is, the presence of RWD does not contribute to increased environmental kerma rate in the region around this installation.

  15. KERMA received in neck by woman subject to mammography survey

    International Nuclear Information System (INIS)

    This paper provides information about the Air KERMA received in the neck by women subjected to mammography surveys. In this investigation we demonstrated that the protection given in mammography units is insufficient because the neck protector is only made up of plastic, in consequence the neck receives unnecessary doses. We used for the radiological survey an Electrometer RADCAL, model: 9060, serial 99-1724 and an Ionization Chamber 180 cc. RADCAL, model: 10X5-60, serial: 18304.We carried out 15 Quality Control inspections in different mammography units used for screening breast cancer from different manufacturers and these QC inspections included radiological surveys. These inspections were made in a two year period. The ionization chamber was placed around the thyroid protector (left, front and right) and the Air KERMA was measured under clinical condition. We found inadequate protection in the thyroid protector. The Air KERMA around the thyroid protector was between 40 and 80 mGy/min. This investigation demonstrates that is impossible to postpone the need to demand mammography manufacturer to modify and reinforce the thyroid protector, and we urge all International Radiological Protection Association to take steps to insure the well being of our patients and to pursuit manufacturers to meet security standards required in order to reduce the exposure of the patient's neck. (author)

  16. 1 to 100: creating an air quality index in Pittsburgh.

    Science.gov (United States)

    Longhurst, James

    2005-07-01

    Air pollution indices and other environmental quality indicators have often been subjects of debate. This article presents a case study of the creation and criticism of an air pollution index in Pittsburgh, Pennsylvania. Long known for its industrial production and the resulting pollution, Pittsburgh was home to engineers, scientists, institutions and corporations that developed new air pollution monitoring technologies in the years after World War II. These newly automated instruments were used as a part of a computerized monitoring network built in the late 1960s by the Allegheny County Health Department. County engineers created a daily air pollution index to summarize the information from the network, leading to public debates over the intent, meaning, and representation of air quality data. This case study serves to illustrate the inherent complexity of creating accessible, understandable, and uniformly acceptable indices of environmental quality. It also emphasizes the importance of understanding the social and political context in which data is collected, organized, and interpreted. PMID:16001710

  17. A novel, fuzzy-based air quality index (FAQI) for air quality assessment

    Science.gov (United States)

    Sowlat, Mohammad Hossein; Gharibi, Hamed; Yunesian, Masud; Tayefeh Mahmoudi, Maryam; Lotfi, Saeedeh

    2011-04-01

    The ever increasing level of air pollution in most areas of the world has led to development of a variety of air quality indices for estimation of health effects of air pollution, though the indices have their own limitations such as high levels of subjectivity. Present study, therefore, aimed at developing a novel, fuzzy-based air quality index (FAQI ) to handle such limitations. The index developed by present study is based on fuzzy logic that is considered as one of the most common computational methods of artificial intelligence. In addition to criteria air pollutants (i.e. CO, SO 2, PM 10, O 3, NO 2), benzene, toluene, ethylbenzene, xylene, and 1,3-butadiene were also taken into account in the index proposed, because of their considerable health effects. Different weighting factors were then assigned to each pollutant according to its priority. Trapezoidal membership functions were employed for classifications and the final index consisted of 72 inference rules. To assess the performance of the index, a case study was carried out employing air quality data at five different sampling stations in Tehran, Iran, from January 2008 to December 2009, results of which were then compared to the results obtained from USEPA air quality index (AQI). According to the results from present study, fuzzy-based air quality index is a comprehensive tool for classification of air quality and tends to produce accurate results. Therefore, it can be considered useful, reliable, and suitable for consideration by local authorities in air quality assessment and management schemes. Fuzzy-based air quality index (FAQI).

  18. The air pollution index system in Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Lee, F.Y.P.; Gervat, G.P. [Hong Kong Government, Wanchai (Hong Kong). Environmental Protection Dept.

    1995-12-31

    The Hong Kong Environmental Protection Department (EPD) is currently operating an air quality monitoring network in the territory. There are nine monitoring stations, each with air quality monitoring equipment, meteorological instruments and a data logger. Five minute averaged data are transmitted through telephone lines to the central computer at the EPD Air Laboratory and are also stored in the data logger on site, as backup. At present, the EPD releases its air quality measurements to the public via monthly and special press releases, and annual reports. However, as public awareness of air pollution problems has increased, there has been an urgent need for timely and simpler information about air pollution levels. The development and operation of an Air Pollution Index (API) system has addressed that need. This presentation discusses the API computation, the information and advice released to the general public and how they can access the API information. Some API results are also presented. (author)

  19. Hold your breath: A new index of air pollution

    International Nuclear Information System (INIS)

    Environmental quality and climate change have been discussed prominently as urgent problems that – due to air pollution – produce severe consequences affecting the everyday life of millions of people. Using a Multiple Indicators Multiple Causes (MIMIC) model, we calculate a new index of air pollution and provide a ranking for 122 countries for every fifth year between 1985 and 2005. The empirical analysis supports the Environmental Kuznets Curve (EKC) hypothesis and shows a significant influence of determinants such as energy efficiency, industrial production, the electricity produced from coal sources, and demographic transition on air pollution. According to the index, Norway, Switzerland, Japan, Luxembourg, and Iceland are among the top 5 countries in terms of air quality performance. Eritrea, Mozambique, Tajikistan, the Democratic Republic of Congo, and Ethiopia performed worst in 2005. - Highlights: ? We calculate a new index of air pollution and provide a ranking for 122 countries. ? The empirical analysis supports the EKC hypothesis. ? Country ranking of this air pollution index is comparable across the period 1985 to 2005. ? Definition of the underlying variables does not change and the methodology is consistent

  20. Experimental comparison among the laboratories accredited within the framework of the European Co-operation for Accreditation on the calibration of a radiation protection dosimeters in the terms of the quantity air Kerma

    International Nuclear Information System (INIS)

    The European co-operation for Accreditation (EA) formalises the collaboration of the Accreditation Bodies of the Member States of the European Union and the European Free Trade Association covering all conformity assessment activities. This collaboration is based on a Memorandum of Understanding dated the 27 November 1997 and aims at developing and maintain Multilateral Agreements (MLAs) within EA and with non-members accreditation bodies. MLAs Signatories guarantee uniformity of accreditation by continuous and rigorous evaluation. Based on mutual confidence, the MLAs recognise the equivalence of the accreditation systems administered by EA Members and of certificates and reports issued by bodies accredited under these systems. A basic element of the program to establish and maintain mutual confidence among calibration services is the participation of the accredited laboratories in experimental interlaboratory comparisons (ILC) organised by EA members or other international organisations. The aim of these ILC is to verify the technical equivalence of calibration services within the EA. The ILC which it is dealt with in the present work was recently carried out over a period of two years, ending in May 2002. It interested the laboratories accredited in the ionising radiation field for calibration of dosimeters at radiation protection levels in terms of the quantity air kerma (Kair) due to 60Co and 137Cs gamma radiation. The ILC was planned by the EA expert group on Ionising radiation and radioactivity and approved by the EA General Assembly in December 1999 with the title Calibration of a Radiation Protection Dosimeter under the code IR3. The need of this comparison also resulted from an inquiry carried out in 1998 by the expert group among the different Accreditation Bodies members of EA and associated to EA. The organization of the ILC was carried out according to the EA rules by the Italian Accreditation Body in the ionising radiation field, the SIT-ENEA , in cooperation with the Italian National Metrology Institute in the ionising radiation field, the ENEA-INMRI, as the reference laboratory

  1. The use of air quality index (AQI) in environmental management

    International Nuclear Information System (INIS)

    The air quality index (AQI) is considered a global air quality index in a particular moment or day and in a specific monitoring station. The AQI is to be interpreted as a guiding air quality index for the general public. Specialists should take into account other factors when studying the pollution levels. The behaviour of air pollution is studied by using the AQI in two monitoring points in Regla, where the main pollutants are measured: SO2, NO2 and total suspended particulates. It was founded that particulates and NO2 are the pollutants that contribute most to the air quality deterioration, which occurs with greater frequency-days in the categories Poor and Bad, and show an increase in the categories Terrible and Critical. The necessary recommendations for the reduction of air pollution are given. The use of this AQI for assessing air pollution in settlements is recommended as a good tool for environmental information and management. A visual scale is proposed to improve and facilitate the public's understanding

  2. Determination of backscatter factors for diagnostic x-ray beams by experimental and Monte Carlo Methods and determination of air kerma to dose equivalent conversion factors for the calibration of personal monitors

    International Nuclear Information System (INIS)

    Backscatter measurements are essential for the determination of the Dose Equivalent quantity H(0.07) in phantoms or H'(0.07) in ICRU sphere, both for area monitoring and individual monitoring purposes. Backscatter factor data for the diagnostic x-ray beams are sparsely Some of the published data are entirely from calculations for idealised irradiation conditions available. A Siemens Polymat 501 diagnostic x-ray machine was used for the investigations. Variations in kV, mA and time of exposure of the machine are microprocessor-controlled, giving a highly stable output. A light beam diaphragm was attached to the x-ray tube and the total inherent filtration was estimated as 2.9 mm Al. The spectra in terms of exposure per keV interval as well as Photon fluence per keV interval of the three collimated reference beams of 40 kV, 60 kV, 81 kV were determined by attenuation analysis method, using a free air chamber and pure aluminium and copper attenuators. A 3 c.c. spherical Shonka C-552 chamber and a 0.2 c.c. Nuclear Enterprises type 2577 graphite walled chamber which were calibrated against low kV primary standard free air chamber were used to determine back scatter factors for PMMA and water phantom respectively. The measuring set-up consisted of locally designed Varactor input operational amplifier in conjunction with a Philips digital voltmeter and 1 nano Farad reference capacitance. Back scatter factors were determined using 30 cm x 30 cm x 15 cm PMMA phantom and a 30 ccm x 30 cm x 15 cm PMMA phantom and a 30 cm x 30 cm x 25.6 cm reference water phantom and conversion coefficients in terms of H(0.07)/Air kerma were determined, which can be used to calibrate personal monitors. The Monte Carlo Code for Neutrons and Photons (MCNP) was also used to find out the Back scatter factors and back scattered spectra for the PMMA and water phantom. The paper gives the details of the experiment and results and comparisons with published data. Typical Results: The ratio of measured to Monte Carlo determined backscatter values were with ±3% at the three beams used. The Monte Carlo values showed an agreement of better than ±6% with Physikalische Technische Bundesanstat (PTB) Monte Carlo values of nearest narrow spectra. (author)

  3. Hold Your Breath. A New Index of Air Quality

    International Nuclear Information System (INIS)

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005.The empirical analysis supports the EKC hypothesis (Environmental Kuznets Curve) and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urbanization on air quality. According to our index, Luxemburg, Norway, Iceland, Switzerland, and Japan are among the top 5 countries in terms of air quality performance. The Democratic Republic of Congo, Eritrea, Ethiopia, Togo, and Nepal performed worst in 2005.

  4. Hold Your Breath. A New Index of Air Quality

    Energy Technology Data Exchange (ETDEWEB)

    Buehn, A. [Utrecht School of Economics, Utrecht University, Utrecht (Netherlands); Reza Farzanega, M. [Dresden University of Technology and ZEW Mannheim, Mannheim (Germany)

    2011-12-15

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005.The empirical analysis supports the EKC hypothesis (Environmental Kuznets Curve) and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urbanization on air quality. According to our index, Luxemburg, Norway, Iceland, Switzerland, and Japan are among the top 5 countries in terms of air quality performance. The Democratic Republic of Congo, Eritrea, Ethiopia, Togo, and Nepal performed worst in 2005.

  5. Hold your breath: A new index of air quality

    OpenAIRE

    Buehn, Andreas; Farzanegan, Mohammad Reza

    2012-01-01

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005. The empirical analysis supports the EKC hypothesis and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urba...

  6. Developing a risk-based air quality health index

    Science.gov (United States)

    Wong, Tze Wai; Tam, Wilson Wai San; Yu, Ignatius Tak Sun; Lau, Alexis Kai Hon; Pang, Sik Wing; Wong, Andromeda H. S.

    2013-09-01

    We developed a risk-based, multi-pollutant air quality health index (AQHI) reporting system in Hong Kong, based on the Canadian approach. We performed time series studies to obtain the relative risks of hospital admissions for respiratory and cardiovascular diseases associated with four air pollutants: sulphur dioxide, nitrogen dioxide, ozone, and particulate matter with an aerodynamic diameter less than 10 ?m (PM10). We then calculated the sum of excess risks of the hospital admissions associated with these air pollutants. The cut-off points of the summed excess risk, for the issuance of different health warnings, were based on the concentrations of these pollutants recommended as short-term Air Quality Guidelines by the World Health Organization. The excess risks were adjusted downwards for young children and the elderly. Health risk was grouped into five categories and sub-divided into eleven bands, with equal increments in excess risk from band 1 up to band 10 (the 11th band is 'band 10+'). We developed health warning messages for the general public, including at-risk groups: young children, the elderly, and people with pre-existing cardiac or respiratory diseases. The new system addressed two major shortcomings of the current standard-based system; namely, the time lag between a sudden rise in air pollutant concentrations and the issue of a health warning, and the reliance on one dominant pollutant to calculate the index. Hence, the AQHI represents an improvement over Hong Kong's existing air pollution index.

  7. Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

    International Nuclear Information System (INIS)

    The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature. - Highlights: • Scenarios of external photon exposures were performed in VMC code. • The VOXTISS8 simulator was irradiated in standing and sitting postures. • The irradiation geometry used was the antero-posterior (AP). • The DCCs for standing and sitting postures were compared. • Significant differences between the DCCs in both postures were observed

  8. Comparison of conversion coefficients for equivalent dose in terms of air kerma using a sitting and standing female adult voxel simulators exposure to photons in antero-posterior irradiation geometry

    International Nuclear Information System (INIS)

    Due to the difficulty in implementing invasive techniques for calculations of dose for some exposure scenarios, computational simulators have been created to represent as realistically as possible the structures of the human body and through radiation transport simulations to obtain conversion coefficients (CCs) to estimate dose. In most published papers simulators are implemented in the standing posture and this may not describe a real scenario of exposure. In this work we developed exposure scenarios in the Visual Monte Carlo (VMC) code using a female simulator in standing and sitting postures. The simulator was irradiated in the antero-posterior (AP) geometry by a plane source of monoenergetic photons with energy from 10 keV to 2 MeV. The conversion coefficients for equivalent dose in terms of air kerma (HT/Kair) were calculated for both scenarios and compared. The results show that the percentage difference of CCs for the organs of the head and thorax was not significant (less than 5%) since the anatomic position of the organs is the same in both postures. The percentage difference is more significant to the ovaries (71% for photon energy of 20 keV), to the bladder (39% at 60 keV) and to the uterus (37% at 100 keV) due to different processes of radiation interactions in the legs of the simulator when its posture is changed. For organs and tissues that are distributed throughout the entire body, such as bone (21% at 100 keV) and muscle (30% at 80 keV) the percentage difference of CCs reflects a reduction of interaction of photons with the legs of the simulator. Therefore, the calculation of conversion coefficients using simulators in the sitting posture is relevant for a more accurate dose estimation in real exposures to radiation. - Highlights: ? Scenarios of external photon exposures were performed in VMC code. ? The FAX simulator was irradiated in sitting and standing postures. ? The irradiation geometry used was the antero-posterior (AP). ? The conversion coefficients for sitting and standing postures were compared. ? Photoelectric and Compton effects were the main processes of energy deposition

  9. AIRS-CloudSat cloud mask and radar reflectivities collocation indexes V3.1

    National Aeronautics and Space Administration — This is AIRS-AMSU-CloudSat collocation indexes, in ASCII format. These data map CloudSat profile indexes to the collocated AMSU field of views, and AIRS IR...

  10. Seasonal variation of air pollution index: Hong Kong case study.

    Science.gov (United States)

    Wang, Xie-Kang; Lu, Wei-Zhen

    2006-05-01

    Air pollution is an important and popular topic in Hong Kong as concerns have been raised about the health impacts caused by vehicle exhausts in recent years. In Hong Kong, sulphur dioxide SO2, nitrogen dioxide (NO2), nitric oxide (NO), carbon monoxide (CO), and respirable suspended particulates (RSP) are major air pollutants caused by the dominant usage of diesel fuel by goods vehicles and buses. These major pollutants and the related secondary pollutant, e.g., ozone (O3), become and impose harmful impact on human health in Hong Kong area after the northern shifting of major industries to Mainland China. The air pollution index (API), a referential parameter describing air pollution levels, provides information to enhance the public awareness of air pollutions in time series since 1995. In this study, the varying trends of API and the levels of related air pollutants are analyzed based on the database monitored at a selected roadside air quality monitoring station, i.e., Causeway Bay, during 1999-2003. Firstly, the original measured pollutant data and the resultant APIs are analyzed statistically in different time series including daily, monthly, seasonal patterns. It is found that the daily mean APIs in seasonal period can be regarded as stationary time series. Secondly, the auto-regressive moving average (ARMA) method, implemented by Box-Jenkins model, is used to forecast the API time series in different seasonal specifications. The performance evaluations of the adopted models are also carried out and discussed according to Bayesian information criteria (BIC) and root mean square error (RMSE). The results indicate that the ARMA model can provide reliable, satisfactory predictions for the problem interested and is expecting to be an alternative tool for practical assessment and justification. PMID:16325232

  11. Índice integrado de calidad del aire para ciudades colombianas / Integrated air quality index for Colombian cities

    Scientific Electronic Library Online (English)

    Mauricio, Jaramillo; Daniel Enrique, González; María Eugenia, Núñez; Gloria, Portilla.

    2009-06-01

    Full Text Available En este trabajo se propone un índice que integra información sobre los dos contaminantes criterio de mayor incidencia sobre la salud humana en las ciudades colombianas, ozono (O3) y material particulado con diámetro menor a 10?m (PM10), utilizando lógica difusa. El índice se calcula para las normas [...] de calidad del aire que rigen actualmente en Colombia, aunque su adaptación a otras reglamentaciones es sencilla. Abstract in english In this work an integrated index is proposed using fuzzy logic which incorporates information on the two criteria pollutants of highest incidence on human health in Colombian cities, ozone (O3) and particulate matter with diameter less than 10?m (PM10). The index is calculated for current Colombian [...] air quality standards, although its adaptation to others is straightforward.

  12. A tandem calibration method for kerma-area product meters

    International Nuclear Information System (INIS)

    Full text: The kerma-area product (KAP) of an X ray beam is the surface integral of air kerma over a plane perpendicular to the beam. The quantity is commonly used in diagnostic radiology to evaluate radiation exposure to patients. It can be measured, closely according to definition, using a KAP meter with a transmission ionization chamber. To achieve adequate accuracy in measurements, appropriate calibration of the KAP meter is needed. An uncertainty of lower than 7% (with a coverage factor k = 2) is pursued in air kerma measurements in diagnostic X ray beams. The same level of accuracy can be seen as a challenging goal also for KAP measurements. According to international standard IEC 60580 a combined standard uncertainty of 25% (k 2) should not be exceeded in KAP measurements. The aim of this study was to investigate whether better accuracy can be achieved by improving the calibration procedures for KAP meters. The KAP meter should indicate the kerma-area product of the X ray beam delivered through the chamber to the patient. It is also generally recommended that calibration of a KAP meter of an X ray equipment (field KAP meter) should be performed using the actual X ray stand and irradiation geometry, mainly because of the characteristics of extra focal and stray radiation specific to the X ray equipment. A portable KAP meter can also be calibrated in a calibration laboratory but the effects of extra focal and stray radiation should be tested separately with the Xion should be tested separately with the X ray equipment in which the KAP meter is used. In calibrations on user's site the KAP reference value is usually determined by approximating the surface integral by the product of the X ray field area and the air kerma measured in the centre of the field. This beam area method works well in uniform, sharp-edged X ray fields. Non-uniformities and irregularities of the field may cause distorted dependence on field size to the determined calibration coefficients. Another important source of uncertainty is the measurement of field size. The accuracy of calibration can be improved by measuring the reference KAP value as an integral according the definition. Larsson, et al. have used TLDs to measure this surface integral. In this work a tandem calibration method was introduced in which the reference KAP value is measured using a KAP meter. In this approach the reference KAP chamber is placed in the X ray beam simultaneously with the field KAP chamber, using a distance of 30 cm between the chambers. The reference KAP meter has to be calibrated for the incident beam. In tandem method the measurement distance is not critical and field area measurements are not needed. As the reference KAP value is based on the measurement of the surface integral, the nonuniformities of the X ray field are inherently included. Because of remarkable dependence of the response on energy, the main uncertainties arise from the interpolation of the calibration coefficient of the reference KAP meter between X ray beam qualities. For tandem method, preliminary results indicate that uncertainty of 5% or lower could be achieved in the calibration of a field KAP meter. However, to achieve this level of accuracy, a comprehensive calibration of the reference KAP meter is required. Independent of calibration methods, the aim of 7% uncertainty in patient measurements is possible to achieve only in limited conditions of use and (or) by instruments of improved quality. This work has a contribution to the IAEA Coordinated Research Project for Testing of the Implementation of the IAEA Code of Practice on Dosimetry in X ray Diagnostic Radiology. (author)

  13. Tolerance Levels of Roadside Trees to Air Pollutants Based on Relative Growth Rate and Air Pollution Tolerance Index

    OpenAIRE

    SULISTIJORINI; ZAINAL ALIM MAS’UD; NIZAR NASRULLAH; AHMAD BEY; SOEKISMAN TJITROSEMITO

    2008-01-01

    Motor vehicles release carbon monoxide, nitrogen dioxide, sulphur dioxide, and particulate matters to the air as pollutants. Vegetation can absorb these pollutants through gas exchange processes. The objective of this study was to examine the combination of the relative growth rate (RGR) and physiological responses in determining tolerance levels of plant species to air pollutants. Physiological responses were calculated as air pollution tolerance index (APTI). Eight roadside tree species wer...

  14. Laminar burning velocity and explosion index of LPG-air and propane-air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    A.S. Huzayyin; H.A. Moneib; M.S. Shehatta; A.M.A. Attia [Benha University, Benha (Egypt). High Institute of Technology]. ali_maattia@yahoo.com

    2008-01-15

    The determination of burning velocity is very important for the calculations used in hazardous waste explosion protection and fuel tank venting, which has a direct impact on environmental protection. The scope of the present study encompass an extensive study to map the variations of the laminar burning velocity and the explosion index of LPG-air and propane-air mixtures over wide ranges of equivalence ratio ({phi} = 0.7-2.2) and initial temperature (Ti = 295-400 K) and pressure (P{sub I} = 50-400 kPa). For this purpose a cylindrical combustion bomb was developed. The burning velocity was determined using different models depending on the pressure history (P-t) of the central ignition combustion process at the minimum ignition energy. The data obtained for the laminar burning velocity is correlated to S{sub L} = S{sub L0}(T/T{sub O}){sup {alpha}}(P/P{sub O}){sup {beta}} where S{sub L0} is the burning velocity at NPT, {alpha} and {beta} are the temperature and pressure exponents respectively. The value of {beta} is observed to slightly vary with the equivalence ratio for both fuels. However, propane exhibits higher pressure dependency than that of LPG. The maximum laminar burning velocity found for propane is nearly 455 mm/s at {phi} = 1.1, while that for LPG is nearly 432 mm/s at 4.5% fuel percent ({phi}{approx} 1.5). The maximum explosion index, commonly called the 'explosion severity parameter', is calculated from the determined laminar burning velocity and is found to be 93 bar m/s for propane, and nearly 88 bar m/s for LPG. 53 refs., 20 figs., 5 tabs.

  15. Kerma factors in interaction of neutrons with boron carbide

    International Nuclear Information System (INIS)

    Heat generation in neutron interactions with boron carbide B10; B11 and 12C is calculated. Kerma-factors (kerma-kinetic energy released in materials) were calculated for neutron energies between 10-4 eV and 15 MeV. No major simplifying assumptions are introduced, and the accuracy of the calculated kerma-factors depends only on availability and accuracy of the basic nuclear data. The ENDF/B-4 data and recent experimental information are used for the calculation of kerma-factors. Plots of these kerma-factors are presented in units of eVxb/atom and wtxsec/(cmxn) as a function of neutron energy

  16. Air refractivity index in optical region: formulas and measurement in CZ.

    Czech Academy of Sciences Publication Activity Database

    Pešice, Petr; Fišer, Ond?ej; Chládová, Zuzana; Brázda, Vladimír

    Portsmouth : University of Portsmouth, 2012, COST IC0802/1-COST IC0802/7. [MCM 7. Portsmouth (GB), 16.04.2012-18.04.2012] R&D Projects: GA MŠk OC09027 Institutional support: RVO:68378289 Keywords : Refractivity index * structure index * free-space optics * temperature * humidity * air pressure Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  17. AIR QUALITY MONITORING WITH THE LICHEN BIODIVERSITY INDEX (LBI IN THE DISTRICT OF FAENZA (ITALY

    Directory of Open Access Journals (Sweden)

    Manuela Cioffi

    2009-07-01

    Full Text Available The Lichen Biodiversity Index (LBI is a method for monitoring air pollution. This method employs lichens living on lime trees because they are sensitive to NOx and SOx, and it considers the variations in their communities. This study was performed in 16 stations located in the suburbs of Faenza city town and the result shows a more than acceptable air quality although in some stations the air was affected by the polluting effects of the vehicle traffic.

  18. 29 - Comparing air quality in Italy, Germany and Poland using BC indexes

    OpenAIRE

    Bodnar, Olha; Cameletti, Michela; FASSO', ALESSANDRO; Schmid, Wolfgang

    2007-01-01

    In this paper we discuss air quality assessment in three Italian, German and Polish regions using the index methodology proposed in Bruno and Cocchi (2002, 2007). This analysis focuses first of all on the quality of the air in each of the countries being taken into consideration, and then adopts a more general approach in order to compare pollution severity and toxicity. This is interesting in a global European perspective where all countries are commonly involved in assessing air quality and...

  19. Comparing air quality among Italy, Germany and Poland using BC indexes

    OpenAIRE

    Bodnar, Olha; Cameletti, Michela; FASSO', ALESSANDRO; Schmid, Wolfgang

    2008-01-01

    In this paper we discuss air quality assessment in three Italian, German and Polish regions using the index methodology proposed in Bruno and Cocchi (2002, 2007). This analysis focuses first of all on the quality of the air in each of the countries being taken into consideration, and then adopts a more general approach in order to compare pollution severity and toxicity. This is interesting in a global European perspective where all countries are commonly involved in assessing air quality and...

  20. Tsp and Pm10 Measurement and Description of Air Quality Index (Aqi in the Ambient Air in Shariati Hospital District

    Directory of Open Access Journals (Sweden)

    A.S Mesbah

    2004-06-01

    Full Text Available Apparently, breathing clean air is of significant importance to human beings and thus attention to what enters our body through inhalation is on the increase. Tehran’s air pollution has received considerable media coverage in recent years: Since particulate matter (TSP and PM10 is one of the important pollutants in this city, an attempt was made to study TSP and PM10 concentrations and to make a qualitative assessment of air using the Air Quality Index (AQI, with TSP and PM10 sampling both daily and on a monthly basis. Shariati Hospital district was selected as study area from 22 December 2001 to 20 April 2002. To determine the amount of TSP and PM10 according to EPA and WHO standards, 61 samples were taken for TSP and 61 samples for PM10 with High Volume Sampler. The results indicated that: •As for TSP and PM10, the period extending from 20 February to 20 March (Esfand was the most heavily polluted one in this study. The cleanest spell was observed from 21 March to 20 April (Farvardin. •Saturdays and Mondays were the most polluted days of the week for TSP and PM10 and Fridays were the cleanest. •As for TSP, In 51 percent of the samples the Air Quality Index (AQI was below 100 (AQI100. •In the case of PM10, in 75.5 percent of samples the Air Quality Index (AQI was below 100 (AQI100.

  1. Precision interferometric measurements of refractive index of polymers in air and liquid

    Science.gov (United States)

    Marcus, Michael A.; Hadcock, Kyle J.; Gibson, Donald S.; Herbrand, Matthew E.; Ignatovich, Filipp V.

    2013-09-01

    We have developed a procedure for precise measurement of the group refractive index for materials in air and liquid environments, using a low coherence interferometer. For example, in manufacturing of soft contact lenses, the lenses are always kept hydrated in a saline solution. Knowing accurate refractive index of the lens is important to metrology and quality control purposes. The small refractive index difference between the liquid and the lens makes such tasks especially challenging. The developed procedure allows us to obtain measurement repeatability for group refractive index less than 1 x 10-3 for materials with thicknesses on the order of 100 microns, when measured in liquid. The measurement repeatability further improves for measurements in air, or for thicker materials.

  2. Measurement of high order Kerr refractive index of major air components

    OpenAIRE

    Loriot, V.; Hertz, E.; Faucher, O.; Lavorel, B.

    2009-01-01

    We measure the instantaneous electronic nonlinear refractive index of N2 , O2 , and Ar at room temperature for a 90 fs and 800 nm laser pulse. Measurements are calibrated by post-pulse molecular alignment through a polarization technique. At low intensity, quadratic coef?cients n2 are determined. At higher intensities, a strong negative contribution with a higher nonlinearity appears, which leads to an overall negative nonlinear Kerr refractive index in air above 26 TW/cm2 .

  3. Estimation of Air Temperature Using Temperature-Vegetation Index (TVX Method

    Directory of Open Access Journals (Sweden)

    L. Parviz

    2011-07-01

    Full Text Available The determination of air temperature is important in the energy balance calculation, hydrology and meteorological studies. In this regard, the limited number of meteorological stations is one of the serious problems for air temperature determination on a large spatial scale. The remote sensing technique by covering large areas and using updated satellite images might be appropriate for estimation of this parameter. In this research, the negative correlation between land surface temperature and vegetation index (NDVI has been used for air temperature estimation through TVX method in which the inference of air temperature is based on the hypothesis that the temperature of the dense vegetation canopy is close to air temperature. For investigation the performance of TVX method, images of MODIS sensor have been applied for the Sefidrod River basin in the years 1381- 1382-1384. The spilt window technique which was developed by Price has been used for land surface temperature calculation. The mean difference between observed and estimated land surface temperature using Price algorithm was about 6.2Co. This error can affect the air temperature values. Because of using NDVI index in TVX method, this method has the sensitivity to the vegetation density, though in the parts with sparse vegetation, the value of error increases. 4 percent variation of air temperature against the 0.05 increasing of maximum NDVI indicates the high performance of TVX method for air temperature estimation in large areas.

  4. Forecasting of Air Quality Index in Delhi Using Neural Network Based on Principal Component Analysis

    Science.gov (United States)

    Kumar, Anikender; Goyal, P.

    2013-04-01

    Forecasting of the air quality index (AQI) is one of the topics of air quality research today as it is useful to assess the effects of air pollutants on human health in urban areas. It has been learned in the last decade that airborne pollution has been a serious and will be a major problem in Delhi in the next few years. The air quality index is a number, based on the comprehensive effect of concentrations of major air pollutants, used by Government agencies to characterize the quality of the air at different locations, which is also used for local and regional air quality management in many metro cities of the world. Thus, the main objective of the present study is to forecast the daily AQI through a neural network based on principal component analysis (PCA). The AQI of criteria air pollutants has been forecasted using the previous day's AQI and meteorological variables, which have been found to be nearly same for weekends and weekdays. The principal components of a neural network based on PCA (PCA-neural network) have been computed using a correlation matrix of input data. The evaluation of the PCA-neural network model has been made by comparing its results with the results of the neural network and observed values during 2000-2006 in four different seasons through statistical parameters, which reveal that the PCA-neural network is performing better than the neural network in all of the four seasons.

  5. Arima and integrated arfima models for forecasting air pollution index in Shah Alam, Selangor

    International Nuclear Information System (INIS)

    Air pollution is one of the major issues that has been affecting human health, agricultural crops, forest species and ecosystems. Since 1980, Malaysia has had a series of haze episodes and the worst ever was reported in 1997. As a result, the government has established the Malaysia Air Quality Guidelines, the Air Pollution Index (API) and Haze Action Plan, to improve the air quality. The API was introduced as an index system for classifying and reporting the ambient air quality in Malaysia. The API for a given period is calculated based on the sub-index value (sub-API) for all the five air pollutants, namely sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and particulate matter below 10 micron size (PM10). The forecast of air pollution can be used for air pollution assessment and management. It can serve as information and warning to the public in cases of high air pollution levels and for policy management of many different chemical compounds. Hence, the objective of this project is to fit and illustrate the use of time series models in forecasting the API in Shah Alam, Selangor. The data used in this study consists of 70 monthly observations of API (from March 1998 to December 2003) published in the Annual Reports of the Department of Environment, Selangor. The time series models that were being considered were the Integrated Autoregressive Moving Average (ARIMA) and the Integrated Long Memoerage (ARIMA) and the Integrated Long Memory Model (ARFIMA) models. The lowest MAE, RMSE and MAPE values were used as the model selection criteria. Between these two models considered, the integrated ARFIMA model appears to be the better model as it has the lowest MAPE value. However, the actual value of May 2003 falls outside the 95% forecast interval, probably due to emissions from mobile sources (i.e., motor vehicles), industrial emissions, burning of solid wastes and forest fires. (author)

  6. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy; Preparacion y determinacion del kerma de fuentes de iridio-192 de baja tasa de dosis para braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    Tendilla, J.I.; Tovar M, V.; Mitsoura, E.; Aguilar H, F.; Alanis M, J. [Instituto Nacional de Investigaciones Nucleares, C.P. 52045-1, Salazar, Esrado de Mexico, D.F. (Mexico)

    2000-07-01

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 {+-} 0.531 M Bq and kerma in air 0.03200 {+-} 0.00006 m Gy m/h A. (Author)

  7. Index to the 1st through 16th AEC/ERDA/DOE nuclear air cleaning conferences

    International Nuclear Information System (INIS)

    The Proceedings of the sixteen conferences comprise a vertible encyclopedia on the technology of nuclear air and gas treatment and the control of airborne nuclear waste. These Proceedings cover the history of the technology; describe most of the research and developments in the field, worldwide, since the early 1950's; describe the problems that have been encountered and the solutions found to those problems; and summarize experience with equipment and systems developed for the control of airborne radioactive wastes in laboratory, radiochemical, and reactor operations, both government and commercial. The problem with this encyclopedia is that there has been no index to it; there has been no easy way for searching it to find what was available. This index fills the gap. The first conference was an informal meeting of a number of interested parties from among the then AEC contractors. Consequently, there were no proceedings for that meeting. The subsequent conferences, with their years, locations, and Proceedings numbers, are listed. This index consists of three parts: a tabulation of papers and their authors by paper number (Part I); a tabulation of papers and their paper numbers by author (Part II); and a key-word-in context (KWIC) index of papers. The paper number is a two-part designation consisting of the number of the conference (2, 3...16) followed by the page number of the paper in the corresponding Proceedings. The author index lists each author who has particior index lists each author who has participated in the air cleaning conferences over the years, and the paper index lists all authors of the respective papers. The KWIC index is, in effect, a comprehensive subject cross index; each paper is listed as many times, by keyword, as there are major terms (i.e., keywords) in its title. Although this multiple listing results in a lengthy list, it provides a very deep cross-indexing of the papers

  8. Frequency measurement of refraction index of air for high-resolution laser interferometry.

    Czech Academy of Sciences Publication Activity Database

    ?íp, Ond?ej; Petr?, František; Matoušek, V.; Lazar, Josef

    Bellingham : SPIE, 2004, s. 273-277. ISBN 0-8194-5380-3. ISSN 0277-786X. [Optical Micro - and Nanometrology in Manufacturing Technology. Strasbourg (FR), 29.04.2004-30.04.2004] R&D Projects: GA AV ?R(CZ) IAB2065001 Keywords : index of refraction of air * high-resolution laser interferometry * Edlen formula Subject RIV: BH - Optics, Masers, Lasers

  9. Direct Measurement of Index of Refraction of Air by Means of High-Resolution Laser Interferometry.

    Czech Academy of Sciences Publication Activity Database

    ?íp, Ond?ej; Petr?, František; Matoušek, Vít; Lazar, Josef

    T118, - (2005), s. 48-50. ISSN 0031-8949 R&D Projects: GA ?R(CZ) GA102/02/1318 Keywords : index of refraction of air * optical resonator Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.661, year: 2004

  10. Effect of scintillometer height on structure parameter of the refractive index of air measurements

    Science.gov (United States)

    Scintillometers measure amount of scintillations by emitting a beam of light over a horizontal path and expresses as the atmospheric turbulence structure parameter as the refractive index of air (Cn**2). Cn**2 represents the turbulent strength of the atmosphere and describes the ability of the atmos...

  11. A proper method of kerma-length product measurement during QC procedures in panoramic radiography

    International Nuclear Information System (INIS)

    As a relevant dose descriptor in panoramic radiography, product of kerma and length PKL is used. The introduction of PKL was recommended by NRPB. Anyway, NRPB termed this quantity dose-width product (DWP), the name product of kerma and length comes from a new dosimetry formalism being developed by IAEA and ICRU. The product of kerma and length in panoramic radiography is an integral of kerma profile created at a front side of the secondary collimator along a line perpendicular to the collimator. The PKL should be measured at a place of maximum intensity of the beam with respect to vertical direction. The signal is integrated over the whole exposure cycle as well. Currently, no dose descriptor in panoramic radiography is measured in the Czech Republic during the QC measurements. Therefore the measurement of PKL should be included in QC procedures as well. A pilot study using three different methods of PKL measurement is being done in the Czech Republic since 2005. The measurements are performed by an X ray film attached to the front side of a secondary collimator, by a column of thermoluminescent detectors (TLDs) and pencil ionization chamber placed perpendicular to the secondary collimator. The results obtained through the mentioned methods agree within 10% generally. The film based method has a significant disadvantage. Air kerma in a profile maximum reaches values up to 30 mGy. Standard X ray films have no dosim30 mGy. Standard X ray films have no dosimetric properties for such a high dose, because the response lies in a region of plateau at a characteristic curve of the film. Therefore, a primary collimator has to be covered by a shielding material. It increases energy dependence of the detection system naturally. An advantage of the film based method is knowledge of a complete kerma distribution within an X ray field. This information is used for proper positioning of a CT pencil ionization chamber or a stack of TLDs within an X ray beam. In the study, monochromatic films Foma Medix XBU (18x24 cm) and a attenuating filter with thickness of 1 mm Cu were used. For film scanning, a laser scanner Lumisys LS50 was used, with scanning resolution 0,2 mm. Before each measurement, the scanner was calibrated by a PTW calibration film in a range of optical densities 0.08/3.4. The simplest and the fastest method is the pencil ionization chamber method. Pencil ionization chambers designed for CT dosimetry were used in the study, especially a type 10X5-3CT with an electrometer Radcal 9015 and a type CT 77336 with an electrometer PTW Nomex 7723. Dependent on a way of calibration of a relevant chamber and an electrometer, a quantity indicated by the electrometer is either integral of kerma profile along a chamber length (Nomex system), which is the required PKL, or just air kerma (Radcal system). In the latter case, indicated air kerma is multiplied by a chamber effective length. Calibration factor of the chambers was verified for beam qualities relevant to panoramic radiography, which are different from those in CT. For a beam quality 50 kV, total filtration 1 mm Al and effective energy Eef 22,7 keV, there was only a 5% difference in calibration factor according to CT energy range. For the TLD measurements, a column of 30 sintered pellets of LiF:Mg, Ti was used. Total length of the TLD column is 27 mm, which is a sufficient length to cover a useful part of the kerma profile. A manual TLD reader Harshaw 4500 was used for the readout of detectors. For routine measurements of several exposure settings at a given X ray unit, TLDs are not appropriate because of time consuming preparation and readout of the dosemeters. The TLD and X ray film systems were calibrated using a reference X ray machine Planmeca Intra in a national reference laboratory for X ray dosimetry. Beam quality for calibration was 70 kV, total filtration 2,2 mm Al, Eef 31 keV. It seems to be most user-friendly and appropriate to measure PKL by means of pencil ionization chamber, for which the calibration factor will be verified for beam qualities relevant to panoramic r

  12. Association of geographical distribution of air quality index and type 2 diabetes mellitus in Isfahan, Iran

    Science.gov (United States)

    Tahmasebi, Azadeh; Amin, Mohammad Mehdi; Poursafa, Parinaz; Iraj, Bijan; Sadeghiyan, Hamidreza; Kelishadi, Roya; Sadeghian, Babak

    2015-01-01

    Objectives: Air pollution is a hazardous environmental problem with several adverse health effects including its impact on the development of chronic diseases as diabetes mellitus. This study aimed to investigate the association of geographical distribution of air quality index (AQI) and type 2 diabetes mellitus in an air-polluted city by using geographic information system (GIS). Methods: This cross-sectional study was conducted in Isfahan, Iran. The records that have been registered from 2009 to 2012 in major referral public diabetes clinics were gathered; they included data of 1467 diabetic patients. Their living area was represented with spots in the city map. AQI data were also interpolated from monitoring stations spreading around the city. The GIS maps of air pollutants and diabetes were developed and the associations were determined. Results: The density of diabetic population was higher in highly polluted areas compared with areas with the lower levels of air pollution. No significant correlation was documented between the distribution of diabetic patients and air pollution level throughout the city. Conclusion: Although the density of diabetic patients was higher in areas with higher air pollution, but the lack of association between AQI and the prevalence of diabetes might be because the air of different parts of the city was highly polluted, and we could not compare the prevalence of diabetes in areas with clean and polluted air.

  13. Air Quality Index (AQI) -- A Guide to Air Quality and Your Health

    Science.gov (United States)

    ... the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents ... for some pollutants there may be a moderate health concern for a very small number of people who ... Unhealthy for Sensitive Groups 101 to 150 Members ...

  14. Comparison of TLD air kerma measurements in mammography

    International Nuclear Information System (INIS)

    The mammography examination is usually targeted at asymptomatic women so the narrow balance between benefit and undesirable effects is important. During the past few decades there have been significant advances in the equipment used for mammography. Even when the latest equipment and imaging systems are used, there is considerable variation from centre-to-centre in the choice of imaging parameters and techniques. There may be quite large differences in image quality and breast dose among the centres. A Co-ordinated Research Programme on 'Image quality and patient dose optimization in mammography in Eastern European Countries' was conducted by the IAEA, aiming at defining a methodology for the implementation of a quality assurance (QA) programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in East European countries. Selected mammography clinics from Czech Republic, Hungary, Poland, Romania and Slovakia participate in the project. The teams consisted of experienced clinicians and physicists. They were supported by a group of experts (clinicians and medical physicists) from France, Italy and Spain. As an outcome of the project, improvements in these indicators (image quality and patient dose) after the implementation of the QA programme are expected. A comparison of dosimetry systems has been organized to assure that dosimetry measurements done in the frame of the project are comparable and traceable to the international measurement system. All five East European countries plus Spain took part in the exercise. The thermoluminescent (TL) method was selected for the comparison

  15. Effects of Age, Gender and Body Mass Index on Reaction to Air Condition

    OpenAIRE

    Uwaoma, Nkwam C.; Anthony Nkwocha

    2011-01-01

    Abstract: This study investigated the effect of age, gender, and body mass index (BMI) on reaction to air condition. Forty eight undergraduates (21 males and 27 females) randomly selected from Imo State University, Owerri, Nigeria within the age range of 17-30 years participated in the study. 26 of them were of normal weight (BMI 24). They were exposed to an air conditioned room for two hours and then their reaction to cold measured using Response to Cold questionnaire. Employing t-test and A...

  16. Simultaneous measurements of radar reflectivity and refractive index spectra in clear air convection.

    Science.gov (United States)

    Konrad, T. G.; Robison, F. L.

    1972-01-01

    Simultaneous measurements of radar reflectivity and radio refractive index at several altitudes in clear air convection have been made. The experimental data were compared with the theoretical relationship which relates the reflectivity to the refractivity spectrum. The agreement between the measurements and the theory is excellent and shows that the radar returns in clear air are the result of, and can be quantitatively described as being from, fine-scale refractivity fluctuations due to turbulent mixing. Further, the data give strong support to the -5/3 spectral decay of the refractivity spectrum in the inertial subrange.

  17. A novel air pollution index based on the relative risk of daily mortality associated with short-term exposure to common air pollutants

    Science.gov (United States)

    Cairncross, Eugene K.; John, Juanette; Zunckel, Mark

    Communication of the complex relationship between air pollutant exposure and ill health is essential to an air pollution information system. We propose a novel air pollution index (API) system based on the relative risk of the well-established increased daily mortality associated with short-term exposure to common air pollutants: particulate matter (PM 10, PM 2.5), sulphur dioxide, ozone, nitrogen dioxide and carbon monoxide. To construct our index system, the total incremental daily mortality risk of exposure to these pollutants was associated with an index value ranging from 0 to 10. The index scale is linear with respect to incremental risk. The index is open ended, although, for convenience, an index of 10 is assigned for exposures yielding indices ?10. To illustrate the application of this API system, a set of published relative risk factors are used to calculate sub-index values for each pollutant, in the range of air pollutant concentrations commonly experienced in urban areas. To account for the reality of ubiquitous simultaneous exposure to a mixture of the common air pollutants, the final API is the sum of the normalised values of the individual indices for PM 10, PM 2.5, sulphur dioxide, ozone, nitrogen dioxide and carbon monoxide. This establishes a self-consistent index system where a given index value corresponds to the same daily mortality risk associated with the combined exposure to the common air pollutants. To facilitate health-risk communication, index values are colour coded and associated with broad health-risk descriptors. The utility of the proposed API is illustrated by applying it to monitored ambient concentration data for the City of Cape Town, South Africa.

  18. Tolerance Levels of Roadside Trees to Air Pollutants Based on Relative Growth Rate and Air Pollution Tolerance Index

    Directory of Open Access Journals (Sweden)

    SULISTIJORINI

    2008-09-01

    Full Text Available Motor vehicles release carbon monoxide, nitrogen dioxide, sulphur dioxide, and particulate matters to the air as pollutants. Vegetation can absorb these pollutants through gas exchange processes. The objective of this study was to examine the combination of the relative growth rate (RGR and physiological responses in determining tolerance levels of plant species to air pollutants. Physiological responses were calculated as air pollution tolerance index (APTI. Eight roadside tree species were placed at polluted (Jagorawi highway and unpolluted (Sindangbarang field area. Growth and physiological parameters of the trees were recorded, including plant height, leaf area, total ascorbate, total chlorophyll, leaf-extract pH, and relative water content. Scoring criteria for the combination of RGR and APTI method was given based on means of the two areas based on two-sample t test. Based on the total score of RGR and APTI, Lagerstroemia speciosa was categorized as a tolerant species; and Pterocarpus indicus, Delonix regia, Swietenia macrophylla were categorized as moderately tolerant species. Gmelina arborea, Cinnamomum burmanii, and Mimusops elengi were categorized as intermediate tolerant species. Lagerstroemia speciosa could be potentially used as roadside tree. The combination of RGR and APTI value was better to determinate tolerance level of plant to air pollutant than merely APTI method.

  19. X ray beam quality specification for kerma area product meters

    International Nuclear Information System (INIS)

    Full text: The kerma area product (KAP) in a diagnostic X ray beam is usually measured with a plane parallel transmission ionization chamber. The response of KAP chambers depend significantly on the energy distribution of radiation, and KAP meters are commonly calibrated with a discrete set of radiation qualities. Appropriate specification of radiation quality is needed to allow interpolation between the measured calibration coefficients. This is especially evident when calibration coefficients for laboratory radiation qualities are converted to clinical qualities. Radiation quality of an X ray beam can be specified explicitly by the tube voltage and total filtration, together with anode angle and material. The half value layer (HVL) of the X ray beam is a generally used beam quality specifier and depends on all these parameters. When a high quality cavity ionization chamber is used properly, the response of the chamber depends on energy rather smoothly and the HVL can be used to specify radiation quality and to interpolate the calibration coefficients between radiation qualities. This is not the case with KAP chambers, however. The energy dependence of the response is affected by the materials and design of the KAP chamber. IEC standard for KAP meters sets a requirement of maximum overall uncertainty of 25% (2 SD) for the accuracy of KAP measurement, including the maximum deviation of ±8% arising from X ray tube voltage variation, in the range of 50 kV to 150 kV wittion, in the range of 50 kV to 150 kV with a 2,5 mm aluminium filtration. No requirements for the response are stated in the standard for other filtrations. ICRU recommendations for diagnostic dosimetry state a maximum overall uncertainty of 7% (2 SD) for KAP measurements. This also emphasizes the need for accurate beam quality specification. In this work the energy dependence of KAP ionization chambers was investigated using a tungsten anode X ray tube (anode angle 20 deg.) with a set of standard and clinical radiation qualities. Tube voltages of 40 kV-150 kV and filtrations from 1,3 mm to 5 mm Al, and 4 mm Al with 0,1 mm and 0,2 mm Cu were used. The HVL values ranged from 1 mm to 9 mm Al. A diaphragm providing a strictly defined radiation field was designed and the KAP measurements were performed at 5 cm distance from the diaphragm. The reference value for the kerma area product was determined as the product of air kerma measured in the field centre and the area of the field at the same distance. For a KAP meter the calibration coefficient was determined as a quotient of the reference value by the measured KAP value. Calibration coefficients were expressed relative to different beam quality specifiers: HVL, tube voltage and filtration. For any individual KAP meter the variation of calibration coefficients was in the range of 20%-30% for the used beam qualities, yet the behaviour of the response relative to radiation quality was clearly different for KAP chambers of different design. For constant HVL values the variation of calibration coefficients ranged up to 10% among typical clinical radiation qualities used in this study, and thus the HVL alone cannot specify the radiation quality adequately. At least two beam quality specifiers need to be known to describe the response of a KAP meter. For a KAP meter, it is not possible to interpolate calibration coefficients between different X ray qualities relative to the HVL alone. Adequate and convenient specifiers in practice are the tube voltage and total filtration or, if one of these parameters is not known, the HVL instead of that. To allow the interpolations, measured calibration coefficients should cover the range of all clinically used radiation qualities. This work is part of the IAEA coordinated research project for testing the implementation of the IAEA Code of Practice on Dosimetry in X ray Diagnostic Radiology. (author)

  20. Trends of air pollution in Denmark - Normalised by a simple weather index model

    International Nuclear Information System (INIS)

    This report is a part of the Traffic Pool projects on 'Traffic and Environments', 1995-99, financed by the Danish Ministry of Transport. The Traffic Pool projects included five different projects on 'Surveillance of the Air Quality', 'Atmospheric Modelling', 'Atmospheric Chemistry Modelling', 'Smog and ozone' and 'Greenhouse effects and Climate', [Rasmussen, 2000]. This work is a part of the project on 'Surveillance of the Air Quality' with the main objectives to make trend analysis of levels of air pollution from traffic in Denmark. Other participants were from the Road Directory mainly focusing on measurement of traffic and trend analysis of the air quality utilising a nordic model for the air pollution in street canyons called BLB (Beregningsmodel for Luftkvalitet i Byluftgader) [Vejdirektoratet 2000], National Environmental Research Institute (HERI) mainly focusing on. measurements of air pollution and trend analysis with the Operational Street Pollution Model (OSPM) [DMU 2000], and the Copenhagen Environmental Protection Agency mainly focusing on measurements. In this study a more simple statistical model has been developed for trend analysis of the air quality. The model is filtering out the influence of the variations from year to year in the meteorological conditions on the air pollution levels. The weather factors found most important are wind speed, wind direction and mixing height. Measurements of CO, NO and NO2 from three streets in Copenhagen h2 from three streets in Copenhagen have been used, these streets are Jagtvej, Bredgade and H. C. Andersen's Boulevard (HCAB). The years 1994-1996 were used for evaluation of the method and annual indexes of air pollution index dependent only on meteorological parameters, called WEATHIX, were calculated for the years 1990-1997 and used for normalisation of the observed air pollution trends. Meteorological data were taken from either the background stations at the H.C. Oersted - building situated close to one of the street stations or the synoptic station at Kastrup Airport just outside Copenhagen. The mixing height was calculated using a bulk Richardson method on vertical profiles provided by the Numerical Weather Prediction model DMI-HIRLAM (Danish Meteorological Institute - High Resolution Limited Area Model). The model in general gives a good explanation of variations from year to year in the air quality. (au)

  1. Calibration of Kerma Area Product Meters with a Patient Dose Calibrator

    International Nuclear Information System (INIS)

    Kerma area product (KAP) meters used in X ray imaging for monitoring patient exposure were calibrated using different reference meters. Typically, the reference KAP value is the product of the air kerma and the X ray field size. In the tandem method, the reference value is measured with another KAP meter; in this study, a large KAP meter of novel type, the patient dose calibrator (PDC), was used for this purpose. The properties of the PDC meter were studied and the use of the meter as a reference meter was reviewed throughout the whole train of events from calibration in a secondary standard dosimetry laboratory to using the meter in clinical situations. Compared to conventional KAP meters, the advantages of the PDC are the lower energy dependence of response and the possibility to use larger field sizes. In laboratory measurements, the properties of the PDC meter were proved suitable to be used as a reference meter. The uncertainty related to the differences in X ray tube output used in calibration at the laboratory and in measurements at the clinic is highlighted. The calibration coefficients for field KAP meters calibrated by the PDC meter and by other meters were congruent on the average within 4%. Clinical measurements emphasized the need for in situ calibration of clinical KAP meters. Particularly in the under-couch situation, the calibration should be performed with the couch in the beam. (author)

  2. Development of a calibration methodology and tests of kerma area product meters; Desenvolvimento de uma metodologia de calibracao e testes de medidores de produto Kerma-Area

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nathalia Almeida

    2013-07-01

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  3. Air quality trends and potential health effects - Development of an aggregate risk index

    Science.gov (United States)

    Sicard, Pierre; Lesne, Olivia; Alexandre, Nicolas; Mangin, Antoine; Collomp, Rémy

    2011-02-01

    The "Provence Alpes Côte d'Azur" (PACA) region, in the South East of France, is one of Europe's regions most influenced by the atmospheric pollution. During the last 15 years, the industrial emissions decrease caused an evolution of the atmospheric pollution nature. Nowadays, atmospheric pollution is more and more influenced by the road traffic, the dominating pollution source in urban zones for the PACA region. Combined with this intense road traffic, the strong hot season of the Mediterranean climate contributes to the region bad air quality; it is known to be one of the worse in Europe. The recognized air pollution effects over public health include increased risk of hospital admissions and mortality by respiratory or cardiovascular diseases. The combination of these serious pollution related health hazards with senior and children vulnerabilities leads to serious sanitary concerns. Over the 1990-2005 period, we obtained, using the non-parametric Mann-Kendall test from annual mortality dataset (CépiDC), decreasing trends for Asthma (-5.00% year -1), Cardiovascular (-0.73% year -1), Ischemic (-0.69% year -1) and cerebrovascular diseases (-3.10% year -1). However, for "Other heart diseases" (+0.10% year -1) and "Respiratory" (+0.10% year -1) an increase was observed. The development of an adequate tool to understand impacts of pollution levels is of utmost importance. Different pollutants have different health endpoints, information may be lost through the use of a single index consequently, in this study we present the modified formula of air quality index, based on Cairncross's concept the Aggregate Risk Index (ARI). ARI is based on the relative risk of the well-established increased daily mortality, or morbidity, enabling an assessment of additive effects of short-term exposure to the main air pollutants: PM 2.5, PM 10, SO 2, O 3 and NO 2 in order to account for the reality of the multiple exposures impacts of chemical agents. The ARI, developed per pathology, takes into account the possible adverse effects associated with the coexistence of all pollutants. This index will enable to communicate the health risks associated, from modelled or monitored pollutant concentrations, to the general population. The second step will consist in the construction of a prediction model of this sanitary index.

  4. Review of kerma-area product and total energy incident on patients in radiography, mammography and CT

    International Nuclear Information System (INIS)

    This study estimated the energy incident on patients in radiography, mammography and CT using data related to X-ray beam quantity and quality. The total X-ray beam quantity is the average Air Kerma multiplied by the X-ray beam area and expressed as the Kerma-Area Product (Gy cm-2). The X-ray beam quality primarily depends on the target material (and anode angle), X-ray voltage (and ripple) as well as X-ray beam filtration. For any X-ray spectra, dividing total energy (fluence x mean energy) by the X-ray beam Kerma-Area Product yields the energy per Kerma-Area Product value (?/KAP). Published data on X-ray spectra characteristics and energy fluence per Air Kerma conversion factors were used to determine 1/KAP factors. In radiography, ?/KAP increased from 6 mJ Gy-1 cm-2 at the lowest X-ray tube voltage (50 kV) to 25 mJ Gy-1 cm-2 at the highest X-ray tube voltage (140 kV). 1/KAP values ranged between 1 and 5 mJ Gy-1 cm-2 in mammography and between 24 and 42 mJ Gy-1 cm-2 in CT. Changes in waveform ripple resulted in variations in ?/KAP of up to 15 %, similar to the effect of changes resulting in the choice of anode angle. For monoenergetic X-ray photons, there was a sigmoidal-type increase in ?/KAP from 2 mJ Gy-1 cm-2 at 20 keV to 42 mJ Gy-1 cm-2 at 80 keV. However, between 80 and 150 keV, the ?/KAP shows variations with changing photon energy of <10 %. Taking the average spectrum energy to consist of monoenergetic X rays generally overestimates the true value of ?/KAP. This study illustrated that the energy incident on a patient in any area of radiological imaging can be estimated from the total X-ray beam intensity (KAP) when X-ray beam quality is taken into account. Energy incident on the patient can be used to estimate the energy absorbed by the patient and the corresponding patient effective dose. (authors)

  5. Review of Kerma-Area Product and total energy incident on patients in radiography, mammography and CT.

    Science.gov (United States)

    Yao, Hai; Huda, Walter; Mah, Eugene; He, Wenjun

    2015-02-01

    This study estimated the energy incident on patients in radiography, mammography and CT using data related to X-ray beam quantity and quality. The total X-ray beam quantity is the average Air Kerma multiplied by the X-ray beam area and expressed as the Kerma-Area Product (Gy cm(-2)). The X-ray beam quality primarily depends on the target material (and anode angle), X-ray voltage (and ripple) as well as X-ray beam filtration. For any X-ray spectra, dividing total energy (fluence × mean energy) by the X-ray beam Kerma-Area Product yields the energy per Kerma-Area Product value (?/KAP). Published data on X-ray spectra characteristics and energy fluence per Air Kerma conversion factors were used to determine ?/KAP factors. In radiography, ?/KAP increased from 6 mJ Gy(-1) cm(-2) at the lowest X-ray tube voltage (50 kV) to 25 mJ Gy(-1) cm(-2) at the highest X-ray tube voltage (140 kV). ?/KAP values ranged between 1 and 5 mJ Gy(-1) cm(-2) in mammography and between 24 and 42 mJ Gy(-1) cm(-2) in CT. Changes in waveform ripple resulted in variations in ?/KAP of up to 15 %, similar to the effect of changes resulting in the choice of anode angle. For monoenergetic X-ray photons, there was a sigmoidal-type increase in ?/KAP from 2 mJ Gy(-1) cm(-2) at 20 keV to 42 mJ Gy(-1) cm(-2) at 80 keV. However, between 80 and 150 keV, the ?/KAP shows variations with changing photon energy of <10 %. Taking the average spectrum energy to consist of monoenergetic X rays generally overestimates the true value of ?/KAP. This study illustrated that the energy incident on a patient in any area of radiological imaging can be estimated from the total X-ray beam intensity (KAP) when X-ray beam quality is taken into account. Energy incident on the patient can be used to estimate the energy absorbed by the patient and the corresponding patient effective dose. PMID:24821931

  6. Compressed Air Energy Storage System Control and Performance Assessment Using Energy Harvested Index

    Directory of Open Access Journals (Sweden)

    Hanif SedighNejad

    2014-01-01

    Full Text Available In this paper a new concept for control and performance assessment of compressed air energy storage (CAES systems in a hybrid energy system is introduced. The proposed criterion, based on the concept of energy harvest index (HEI, measures the capability of a storage system to capture renewable energy. The overall efficiency of the CAES system and optimum control and design from the technical and economic point of view is presented. A possible application of this idea is an isolated community with significant wind energy resource. A case study reveals the usefulness of the proposed criterion in design, control and implementation of a small CAES system in a hybrid power system (HPM for an isolated community. Energy harvested index and its effectiveness in increasing the wind penetration rate in the total energy production is discussed.

  7. Experimental hydrogen kerma factors for incident neutron energies from 25 to 75 MeV

    International Nuclear Information System (INIS)

    Hydrogen kerma factors and their uncertainties are deduced on an experimental basis, starting from our previously measured differential cross sections completed with available data from the literature, in the incident neutron energy range 25 to 75 MeV. The deduced experimental kerma factors are compared with theoretical predictions. A simple to use parametrization of the hydrogen kerma factor values in the incident neutron energy range 0.3 to 100 MeV is also proposed. (author)

  8. Spatial and seasonal variations of the air pollution index and a driving factors analysis in china.

    Science.gov (United States)

    Jiang, Hong-Yue; Li, Hai-Rong; Yang, Lin-Sheng; Li, Yong-Hua; Wang, Wu-Yi; Yan, Ya-Chen

    2014-11-01

    In this study, the daily air pollution index (API) of 110 cities based on ground monitoring was conducted on the 2011 data set from the Ministry of Environmental Protection of China. The pollutant concentrations, seasonal variations, and spatial autocorrelations were evaluated. The results show that the major principal pollutants in China are inhalable particles. In addition, the total number of clean days (API ? 50) is apparently smaller in the northern cities than in the southern cities as a result of fuel utilization and large-scale organized central heating. Seasonally, air pollution is most severe in winter and is caused by low-frequency rainfall, strong northwest winds, dry climate, and high energy consumption; this is followed by spring, which is a season of frequent sandstorms. According to spatial autocorrelation analysis, clusters with high API value agglomeration (High-High clusters) are mainly concentrated in the middle and northern parts of China, whereas clusters with low API agglomeration (Low-Low clusters) are principally concentrated in the southern parts of China due to a favorable climate and abundant rainfall. Meteorological data, including wind speed and temperature, have great impacts on API. The air quality effects of industrial structure, energy use, urban greening, and traffic congestion were also analyzed. With the ecological function of purifying the air, industries that use natural resources and urban greening could help to reduce API, whereas secondary industry and gas use, which have a positive coefficient, increase the API value. The risk of exposure to poor air quality is largest in the winter, smallest in the summer, and remains relatively unchanged in the spring and autumn. PMID:25602202

  9. [Evaluation of calibration error for applying exposure index].

    Science.gov (United States)

    Ariga, Eiji

    2011-01-01

    Exposure indicators of digital radiography systems have been termed by manufacturers individually. The International Electrotechnical Commission (IEC) provided a concept of exposure index (EI) that unified the exposure indicators in order to recognize the deviations from the intended exposure. Although the IEC determined the calibration conditions between the exposure indicator and the air kerma at the detector surface, the tolerance was described was limited concerning the beam conditions. The purpose of this study is to evaluate the calibration error regarding the geometry and the added filtrations. The relative errors of calibrations based on the IEC condition were derived using the value of exposure indicators at EI value of 200, 500 and 1000 for field size of 10×10 cm, 20×20 cm, 30×30 cm and 43×43 cm, and source-image receptor distance (SID) of 100 cm, 120 cm, 150 cm and 200 cm. The beam qualities using added filtrations of 0.5 mm Cu+2 mm Al, 0.6 mm Cu and 21 mm Al were adjusted to RQA 5. The air kerma at the detector surface over the clinical use ranged from 0.18 to 26.3 µGy. Consequently, the relative errors for the calibrations were less than 6% at a field size of more than 10 × 10 cm and at SID of more than 100 cm with all added filtrations. PMID:22104235

  10. The ambient air quality accounts for the Nova Scotia Genuine Progress Index

    International Nuclear Information System (INIS)

    The Nova Scotia Genuine Progress Index (GPI) is a measure of sustainable development which provides a complete and accurate picture of our well-being as a society. The GPI assigns explicit values to environmental quality, population health, livelihood security, equity, free time, and educational attainment. The Nova Scotia GPI includes 22 social, economic and environmental components, including ambient air quality. This report investigates Nova Scotia's ambient air concentrations and emissions of carbon monoxide (CO), total particulate matter (PM), sulphur dioxide (SO2), nitrogen oxides (NOx), and volatile organic compounds (VOC). The costs of damages caused by the these key air pollutants are also examined. Exposure to these pollutants results in negative impacts on human health, damage to materials, agricultural crops and changes in forest productivity. From 1979 to 1996, national ambient concentrations of each of these pollutants decreased significantly. However, the national average concentration of ground-level ozone increased by 34 per cent during the same time period. In Nova Scotia, concentrations of CO, PM and SO2 have declined dramatically since 1979, but the trends for NO2 and ground-level ozone do not show significant declines. On a per capita basis, SOx emissions from electric power generation in the province are more than 8 times the Canadian average. The province also had higher per capita emissions of CO, PM, SOx and VOper capita emissions of CO, PM, SOx and VOCs than all reporting OECD countries. Electric power generation is the greatest source of fuel combustion emissions in the province, followed by industrial and transportation sources. This report also described some individual actions that can be taken to reduce air pollutant emissions. 174 refs., 37 tabs., 60 figs

  11. Radioactive Aerosols as an Index of Air Pollution in the City of Thessaloniki, Greece

    International Nuclear Information System (INIS)

    This study summarizes results of an investigation done in order to find out how the radioactive aerosols of 7Be could serve as indicators of air pollution conditions. Beryllium-7 is a cosmic-ray produced radionuclide with an important fraction of its production to take place in the upper troposphere. Once it is formed is rapidly associated with submicron aerosol particles and participates in the formation and growth of the accumulation mode aerosols, which is a major reservoir of pollutants in the atmosphere. In order to define any influence of AMAD of 7Be aerosols by air pollution conditions, the aerodynamic size distribution of 7Be aerosols was determined by collecting samples at different locations in the suburban area of the city of Thessaloniki, including rural areas, industrial areas, high elevations, marine environment and the airport area. The aerodynamic size distribution of 7Be aerosols in different locations was obtained by using Andersen 1-ACFM cascade impactors and the Activity Median Aerodynamic Diameter (AMAD) was determined. Some dependency of the AMADs on height has been observed, while in near marine environment the 7Be activity size distribution was dominant in the upper size range of aerosol particles. Low AMADs as low as 0.62 to 0.74 ?m of 7Be aerosols have been observed at locations characterized with relative low pollution, while it is concluded that in the activity size distribucluded that in the activity size distribution of ambient aerosols, 7Be changes to larger particle sizes in the presence of pollutants, since low AMADs of 7Be aerosols have been observed at low polluted locations. Preliminary data of simultaneous measurements of 214Pb and 212Pb with gaseous air pollutants CO, NO, NOX, SO2 and total suspended particulate matter (TSP) show that radon decay products near the ground could be a useful index of air pollution potential conditions and transport processes in the boundary layer.

  12. Development of a calibration methodology and tests of kerma area product meters

    International Nuclear Information System (INIS)

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  13. Analysis of the Tandem Calibration Method for Kerma Area Product Meters Via Monte Carlo Simulations

    International Nuclear Information System (INIS)

    The IAEA recommends that uncertainties of dosimetric measurements in diagnostic radiology for risk assessment and quality assurance should be less than 7% on the confidence level of 95%. This accuracy is difficult to achieve with kerma area product (KAP) meters currently used in clinics. The reasons range from the high energy dependence of KAP meters to the wide variety of configurations in which KAP meters are used and calibrated. The tandem calibration method introduced by Poeyry, Komppa and Kosunen in 2005 has the potential to make the calibration procedure simpler and more accurate compared to the traditional beam-area method. In this method, two positions of the reference KAP meter are of interest: (a) a position close to the field KAP meter and (b) a position 20 cm above the couch. In the close position, the distance between the two KAP meters should be at least 30 cm to reduce the effect of back scatter. For the other position, which is recommended for the beam-area calibration method, the distance of 70 cm between the KAP meters was used in this study. The aim of this work was to complement existing experimental data comparing the two configurations with Monte Carlo (MC) simulations. In a geometry consisting of a simplified model of the VacuTec 70157 type KAP meter, the MCNP code was used to simulate the kerma area product, PKA, for the two (close and distant) reference planes. It was found that PKA values for the tube voltage of 40 kV web> values for the tube voltage of 40 kV were about 2.5% lower for the distant plane than for the close one. For higher tube voltages, the difference was smaller. The difference was mainly caused by attenuation of the X ray beam in air. Since the problem with high uncertainties in PKA measurements is also caused by the current design of X ray machines, possible solutions are discussed. (author)

  14. Effects of Age, Gender and Body Mass Index on Reaction to Air Condition

    Directory of Open Access Journals (Sweden)

    Nkwam C. Uwaoma

    2011-04-01

    Full Text Available Abstract: This study investigated the effect of age, gender, and body mass index (BMI on reaction to air condition. Forty eight undergraduates (21 males and 27 females randomly selected from Imo State University, Owerri, Nigeria within the age range of 17-30 years participated in the study. 26 of them were of normal weight (BMI 24. They were exposed to an air conditioned room for two hours and then their reaction to cold measured using Response to Cold questionnaire. Employing t-test and ANOVA for data analyses, the results showed that body size, age, and gender had no statistically significant effect on reaction to cold condition while exposure to cold condition had a significant influence on both systolic and diastolic blood pressures of all participants. Key words: Body mass index; Air condition; Reaction; Blood pressure; Systolic blood pressure; Diastolic blood pressure; Cold Résumé: Cette étude a examiné l'effet de l'âge, du sexe et de l’indice de masse corporelle (IMC sur la réaction des gens envers l’air climatisé. Quarante-huit étudiants de premier cycle (21 hommes et 27 femmes sélectionnés au hasard dans l'Université de l’état d’Imo à Owerri au Nigeria dans une tranche d'âge de 17 ans à 30 ans ont participé à cette étude. 26 d'entre eux avaient un poids normal (IMC 24. Ils ont été exposés dans une salle climatisée pour deux heures, puis leur réaction au froid a été mesuré en utilisant le questionnaire de Réponse au froid. Après le t-test et une analyse de variance des données, les résultats ont montré que la taille corporelle, l'âge et le sexe n'avaient aucun d’effet statistiquement significatif sur la réaction à l'état froid, tandis que l'exposition à l'état froid avait une influence significative sur les pressions artérielles systoliques et diastoliques de tous les participants. Mots clés: Indice de masse corporelle; Climatisation; Iréaction; Pression artérielle; Pression artérielle systolique; Pression artérielle diastolique; Froid

  15. Output Energy Estimation of Si-Based Photovoltaic Modules Using Clearness Index and Air Mass

    Science.gov (United States)

    Takei, Ryosuke; Minemoto, Takashi; Yoshida, Shota; Takakura, Hideyuki

    2012-10-01

    The output energy estimation of photovoltaic (PV) modules was carried out using contour maps as a function of average photon energy (APE), which is an index of solar spectral irradiance and module temperature (Tmod) in our previous report. This method is useful for not only crystalline Si PV modules but also thin film Si PV modules, which have a narrow spectral response. However, this method requires spectrum measurement to obtain APE using a spectroradiometer, which is not widely installed in various locations. In this study, we used clearness index (Kt) and air mass (AM), which have a strong correlation with APE and Tmod. Kt and AM can be calculated easily from irradiance, time, and location. The comparison between the output energy estimation using Kt and AM and that using APE and Tmod was carried out. Results indicate that the accuracy of the output energy estimation using Kt and AM is as high as that using APE and Tmod. The proposed method using Kt and AM is useful for estimating the output energy of the PV modules.

  16. Exploring EKC, trends of growth patterns and air pollutants concentration level in Malaysia: A Nemerow Index Approach

    Science.gov (United States)

    Bekhet, Hussain A.; >Tahira Yasmin,

    2013-06-01

    The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996-2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.

  17. Exploring EKC, trends of growth patterns and air pollutants concentration level in Malaysia: A Nemerow Index Approach

    International Nuclear Information System (INIS)

    The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996–2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.

  18. Estimation of Anticipated Performance Index and Air Pollution Tolerance Index and of vegetation around the marble industrial areas of Potwar region: bioindicators of plant pollution response.

    Science.gov (United States)

    Noor, Mehwish Jamil; Sultana, Shazia; Fatima, Sonia; Ahmad, Mushtaq; Zafar, Muhammad; Sarfraz, Maliha; Balkhyour, Masour A; Safi, Sher Zaman; Ashraf, Muhammad Aqeel

    2015-06-01

    Mitigating industrial air pollution is a big challenge, in such scenario screening of plants as a bio monitor is extremely significant. It requires proper selection and screening of sensitive and tolerant plant species which are bio indicator and sink for air pollution. The present study was designed to evaluate the Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) of the common flora. Fifteen common plant species from among trees, herb and shrubs i.e. Chenopodium album (Chenopodiaceae), Parthenium hysterophorus (Asteraceae), Amaranthus viridis (Amaranthaceae), Lantana camara (Verbenaceaea), Ziziphus nummulari (Rhamnaceae), Silibum merianum (Asteraceae), Cannabis sativa (Cannabinaceae), Calatropis procera (Asclepediaceae), Ricinus communis (Euphorbiaceae), Melia azadirachta (Meliaceae), Psidium guajava (Myrtaceae), Eucalyptus globules (Myrtaceae), Broussonetia papyrifera (Moraceae), Withania somnifera (Solanaceae) and Sapium sabiferum (Euphorbiaceae) were selected growing frequently in vicinity of Marble industries in Potwar region. APTI and API of selected plant species were analyzed by determining important biochemical parameter i.e. total chlorophyll, ascorbic acid, relative water content and pH etc. Furthermore the selected vegetation was studied for physiological, economic, morphological and biological characteristics. The soil of studied sites was analyzed. It was found that most the selected plant species are sensitive to air pollution. However B. papyrifera, E. globulus and R. communis shows the highest API and therefore recommended for plantation in marble dust pollution stress area. PMID:25503327

  19. Analysis of the tandem calibration method for kerma-area product meters via Monte Carlo simulations

    International Nuclear Information System (INIS)

    The kerma-area product PKA is defined as PKA=?A Kc,airdA, where Kc,air is the air collision kerma, and A is the integration area at a reference plane perpendicular to the beam axis. The kerma-area product is measured by KAP-meters. The calibration coefficient of a KAP-meter is affected by the choice of the reference plane and integration area. A procedure standardizing the measurement of the calibration coefficient was proposed. In this beam area method, the reference KAP-meter is placed at the distance of 100 cm from the focal spot. The field KAP-meter is placed between the reference KAP-meter and the focal spot; its precise location is not critical. The main advantage of this method is that the field KAP-meter measures PKA at a plane close to the patient. The disadvantage is that photons scattered in the field KAP-meter and collimator housing may pass beside the relatively small reference KAP-meter. To mitigate the problem, the tandem calibration method was proposed. In this method, the reference KAP-meter is placed at an optimal distance from the field KAP-meter so that (i) it registers most of the radiation passing through the field KAP-meter, and (ii) the amount of radiation backscattered from the reference KAP-meter does not significantly affect the signal of the field KAP-meter. A suitable distance was found to be 30-40 cm for the Diamentor M4 (PTW) KAP-meters, and the distance of 30 cm was receters, and the distance of 30 cm was recommended in general. Measurements showed that the difference between the beam area and tandem calibration methods is relatively small. The aim of our work was to obtained more detailed information about this difference via computer simulations. The MCNP Monte Carlo code was used to calculate PKA values for an ideal reference KAP-meter placed at (i) the distance of 30 cm from the field KAP-meter and (ii) the patient plane 100 cm from the focal spot; these positions correspond to calibrations via the tandem and beam area methods, respectively. The VacuTec's type 70157 field KAP-meter was modelled using a set of cylinders with radii of 8 cm. X-ray spectra were taken from the catalogue of x-ray spectra and filtered with 5 mm of Al. Beam radius was 5.24 cm at 100 cm from the focal spot. The tandem calibration method underestimated PKA values at the patient plane by approximately 2.5% for the tube voltage of 40 kV. A larger integration area (r > 8 cm) resulted in a smaller relative difference, about 1.5% for the radius of 20 cm. Variations between results for different x-ray tube voltages were mostly caused by attenuation of the beam in air

  20. DISDOS, Kerma in Model Man from External Gamma Source

    International Nuclear Information System (INIS)

    1 - Description of problem or function: The absorbed dose (actually Kerma) is calculated for simplified human phantoms (elliptical cylinders) irradiated by external photon sources. The phantoms are divided into three parts: head, trunk, and legs. Three source distributions are considered: collimated beam, point source, and isotropic irradiation; other sources may be considered since the codes are segmented. 2 - Method of solution: Monte Carlo calculations provide estimates of the dose and the standard deviation in each zone. The source energy spectrum may be discrete, uniformly distributed in an energy range, or given by a piece-wise continuous function. 3 - Restrictions on the complexity of the problem: Pair production is accounted for in the field of the nuclei only. Electron binding corrections to Compton scattering are omitted. The body has 22 organs

  1. Development of a health-based air quality index for Canada : public opinion research 2004-05 : final report

    International Nuclear Information System (INIS)

    Canadians rely on an air quality indexes (AQIs) to inform them about air pollution conditions in their communities. However, there is no AQI common to all of Canada, and there is a lack of consistency in the way in which air quality is calculated and reported, as well as in the use of health-based messages. This paper reported findings of a public opinion research survey conducted to gauge Canadians' awareness, perceptions and behavioural responses to air quality, air pollution and AQIs. The aim of the study was to guide the development of health messages to more effectively communicate the AQI to Canadians with respect to the health risks associated with poor air quality. Telephone surveys were conducted immediately following a poor air quality episode to measure the public's awareness and response to these events, as well as residents' general awareness and use of AQIs. A separate research project was then conducted which consisted of in-depth qualitative interviews with 28 individuals recruited from the general population. A comprehensive national telephone survey was then conducted following the summer 2004 'smog season', which focused on the public's awareness of air pollution and AQIs. Results from the first 2 phases of the research were then presented at a workshop comprised of health and environmental communities specializing in air issues in Canada. Focus groups were then held to test public reaction to new AQI communications concepts derived from the researcications concepts derived from the research. Results indicated that Canadians widely identify air pollution as a significant environmental problem. However, the information from AQIs had a limited impact in terms of prompting actions to reduce personal exposure. A new type of national AQI for Canada was developed that conveyed information on air quality conditions and their significance. Key features include a 0 to 10 point unbounded scale showing current air quality conditions; a forecast of future conditions; standardized information covering health risks; targeted information for groups most at risk; and recommended activities

  2. Solar radiation estimation using sunshine hour and air pollution index in China

    International Nuclear Information System (INIS)

    Highlights: • Aerosol can affect coefficients of A–P equation to estimate solar radiation. • Logarithmic model performed best, according to MBE, MABE, MPE, MAPE, RMSE and NSE. • Parameters of A–P model can be adjusted by API, geographical position and altitude. • A general equation to estimate solar radiation was established in China. - Abstract: Angström–Prescott (A–P) equation is the most widely used empirical relationship to estimate global solar radiation from sunshine hours. A new approach based on Air Pollution Index (API) data is introduced to adjust the coefficients of A–P equation in this study. Based on daily solar radiation, sunshine hours and API data at nine meteorological stations from 2001 to 2011 in China, linear, exponential and logarithmic models are developed and validated. When evaluated by performance indicators of mean bias error, mean absolute bias error, mean percentage error, mean absolute percentage error, root mean square error, and Nash–Sutcliffe Equation, it is demonstrated that logarithmic model performed better than the other models. Then empirical coefficients for three models are given for each station and the variations of these coefficients are affected by API, geographical position, and altitude. This indicates that aerosol can play an important role in estimation solar radiation from sunshine hours, especially in those highly polluted regions. Finally, a countrywide general equation is established based on the sunshine hour data, API and geographical parameters, which can be used to estimate the daily solar radiation in areas where the radiation data is not available

  3. Partial kerma factor data for nitrogen and oxygen for fast neutrons

    International Nuclear Information System (INIS)

    The kerma for fast neutrons consists of partial kerma contributions from events such as (n,n), (n,n'), (n,p), (n,alpha) and other (n, charged particle) reactions. Improved fast neutron partial kerma values for (n,p) and (m,alpha) events for nitrogen and oxygen are evaluated using the available data on the break up of (n,p) and (n, alpha) cross sections corresponding to the ground and the various excited states of the residual nucleus in each of these two reactions. (author)

  4. An evaluation model for air quality in underground uranium mines based on integrated scale index on weights of generalized contrast

    International Nuclear Information System (INIS)

    The shortcomings of traditional methods for evaluating air quality in underground uranium mines are analysis. Based on the analysis results and the principle that the concentration of the contaminants in a mine varies in a constant ratio and the degree of their hazard varies in an arithmetic progression, the evaluating indicators were determined for the air quality in a uranium mine, and an evaluation model was proposed for the evaluation of the air quality in a uranium mine based on integrated scale index on weights of generalized contrast. the model overcomes the shortcoming of traditional methods that the radiation hazard is considered mainly in all these methods. the model was used to evaluate the air quality of four places in an underground uranium mine, the grade of the air quality and the correspondingmeasures for controlling the air quality in the four places are determined. The evaluation results show that the model is applicable to the design of a ventilation system for an underground uranium mine and the evaluation of the air quality in the system. (authors)

  5. Automatic unit for measuring refractive index of air based on Ciddor equation and its verification using direct interferometric measurement method.

    Czech Academy of Sciences Publication Activity Database

    Hucl, Václav; ?ížek, Martin; Hrabina, Jan; Mikel, B?etislav; ?e?ucha, Šimon; Buchta, Zden?k; Jedli?ka, Petr; Lešundák, Adam; Oulehla, Jind?ich; Mr?a, Libor; Šarbort, Martin; Šmíd, Radek; Lazar, Josef; ?íp, Ond?ej

    Bellingham : SPIE, 2013, 878837:1-9. ISBN 978-0-8194-9604-1. [Optical Measurement Systems for Industrial Inspection /8./. Munich (DE), 13.05.2013-16.05.2013] R&D Projects: GA ?R GAP102/10/1813; GA ?R GPP102/11/P819 Institutional support: RVO:68081731 Keywords : refractive index of air * precise measurement * laser interferometer Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. Position sensing with suppression of the drift of the refractive index of air for high resolution interferometry.

    Czech Academy of Sciences Publication Activity Database

    Holá, Miroslava; Buchta, Zden?k; ?íp, Ond?ej; Lazar, Josef

    Piscataway : IEEE, 2014. ISBN 978-1-4673-5225-3. [URSI General Assembly and Scientific Symposium (URSI GASS) 2014 /31./. Beijing (CN), 16.08.2014-23.08.2014] R&D Projects: GA TA ?R TA02010711; GA TA ?R TE01020233; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : refractive index of air * interferometry * Edlen formula Subject RIV: BH - Optics, Masers, Lasers

  7. High-accuracy correction of air refractive index by using two-color heterodyne interferometry of optical frequency combs

    International Nuclear Information System (INIS)

    High-accuracy two-color heterodyne interferometry based on fundamental and second harmonic of frequency combs for air refractive index correction is developed. A monitor interferometer as well as a probe interferometer is constructed to compensate the phase noises and drifts, which are caused by introducing the acousto-optic modulators for heterodyne interferometer, to realize high-accuracy measurement of optical distance. A relative stability of 10?10 to the total length for 500 s is achieved in the measurement of an optical path length difference between two wavelengths. In long-term measurements, the interferometric measurement results and the calculations from empirical equation of air refractive indices are in good agreement with a standard deviation of 4.1 × 10?10 throughout the 10 h period. By applying the two-color method, high-accuracy correction of air refractive index with an uncertainty of 8.9 × 10?8 is achieved during 10 h continuous measurements while the total refractive index changes with a range of 2.0 × 10?6. (paper)

  8. Humidity dependence in kerma area product meter used in diagnostic X ray examinations

    International Nuclear Information System (INIS)

    The air-kerma area product, PKA, is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. PKA has the unit Gym2 and can be directly measured by use of a Kerma Area Product (KAP) meter placed in the radiation beam. PKA is the recommended quantity for use in the establishment of diagnostic reference levels (DRLs) for conventional x-ray examinations and is also a good indicator for when threshold doses for deterministic effects are reached in interventional x-ray procedures. Most modern x-ray equipment provides the operator with the total PKA from the examination or procedure. This PKA is either obtained from PKA measurements from a built-in KAP meter or calculated from exposure parameters. To get a reliable estimate of DRLs and the patient dose, it is essential that the PKA measurement is correct. Thus all environmental influences on the KAP meter should be taken into account. These influences can either be corrected for or included in the measurement uncertainty. These have to be considered both in the calibration of the KAP-meters, in the use of the KAP meters and in the determination of DRLs. A KAP meter is an electrometer and a plane parallel ion chamber with an active area of typical 15 cm X 15 cm. The KAP meter usually consist of three plastic plates (PMMA) which is coated with a conductates (PMMA) which is coated with a conducting layer made of indium oxide doped with tin (In2O3:Sn). This coating is used due to its transparency to light. The air layers between the plates (sensitive volume) are open to the air. Thus the readings from the KAP meter have to be corrected for air pressure and temperature as for other ion chambers. It has been assumed that the humidity dependence of the KAP meter is so small that no correction has been necessary. This work will show that KAP meter with PMMA plastic plates coated with In2O3:Sn shows a humidity dependence so large that corrections should be considered. The measurements were performed by carefully controlling the humidity in the laboratory. Between each measurement the humidity was changed with steps of 5 to 10 %RH in the range 20-60 %RH. The measurements were performed two days after the humidity change, so the humidity inside the chamber could stabilise. The setup was as for a substitution calibration with the KAP meter 100 cm from the x- ray source and exposed to a beam limited by a aperture of 5 cm X 5 cm at 95 cm as described in TRS-457. A Capintec PR-30 was used as a monitor chamber. This chamber is made of C-552 and has small humidity dependence. Two KAP-chambers were tested. Both chambers showed the same humidity dependence. The humidity dependence for the chambers was (0.24 ± 0.10) % pr. %RH (k=2). The transmission factor of the chambers showed no humidity dependence. One of the chambers were tested at five different qualities from 40 kV to 150 kV (RQR2, RQR5, RQR8, RQR9, RQR 10). The humidity dependence was the same for all qualities. In an environment with no humidity control the humidity can typically vary from 20 %RH to 80 %RH. According to the results this can lead to about 14 % change in the KAP reading. This is a larger effect than recommended for KAP meters, ± 3.0 %, in the IEC 60580 standard. The observed humidity dependence means that great care have to be take when calibrating and using KAP meter for dose measurements. The humidity effect is not fully understood but it seems that the conducting layer on the PMMA is the origin of the effect

  9. How the consumer confidence index could increase air travel demand forecast accuracy?

    OpenAIRE

    Teyssier, Narjesse

    2012-01-01

    Because of the complex nature of the air transportation industry with continuous changes in the environment, the past records of air traffic forecasters, either using trend extrapolation or causal models or even more sophisticated methods have not produced accurate results. In recent years, the trend has been to develop air travel demand forecasts based on econometric equations, which specify a relationship between passenger traffic and a number of traditional key economic variables. However ...

  10. Air

    Science.gov (United States)

    ... to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... comes from the natural breakdown of uranium in soil, rock, and water and gets into the air ...

  11. A CRITICAL REVIEW OF AIR POLLUTION INDEX SYSTEMS IN THE UNITED STATES AND CANADA

    Science.gov (United States)

    An extensive survey was conducted of all the air pollution indices that are presently utilized or are available. The data were obtained from a literature review; from telephone discussions with personnel in State, local, and Provincial air pollution control agencies; and from mat...

  12. A radiation exposure index for CT.

    Science.gov (United States)

    Huda, Walter

    2013-12-01

    The purpose of this study is to define an Exposure Index for CT (EI(CT)) and to estimate the magnitude of the EI(CT) for common clinical CT examinations. For a single-axial rotation of a CT X-ray tube that includes only rays that pass through the patient, the CT Exposure Index (EI(CT)) is defined as the average Air Kerma that would be incident on an extended 360° detector array completely surrounding the patient. For an axial scan of a uniform cylindrical phantom, EI(CT) can be approximated as T × [(CTDI(air))/4] × [?°/360°] where T is the fractional transmission through the cylinder, CTDI(air) is the CT Dosimetry Index-determined 'free in air' at isocentre, and ?/2 is the fan beam angle that will completely irradiate a cylindrical phantom at isocentre. The value of CTDI(air) can be estimated from the weighted CTDI (CTDI(w)) for a given CT examination, and the angle ? depends on the irradiation geometry that can be obtained from the cylinder diameter (r) and the focus to isocentre distance (R). At a voltage of 120 kV, transmission through an adult head was ?2.6%, through an adult abdomen?0.4% and through a 5-y-old paediatric abdomen ?3%. Average ratios of CTDI(air)/CTDI(w) were 1.42 ± 0.12 in 16-cm dosimetry phantom and 2.82 ± 0.37 in 32-cm phantom. Values of ? ranged from 30.1° (R = 61 cm and r=8 cm) to 85.3° (R = 55 cm and r=20 cm). For an adult head CT examination, EI(CT) was estimated to be?70 µGy at a CTDI(vol) of 75 mGy (16 cm), and for an adult abdominal CT examination, EI(CT) was estimated to be?11 µGy at a CTDI(vol) of 25 mGy (32 cm). For an abdomen CT examination in a 5-y-old child, EI(CT) was estimated to be ?21 µGy at a CTDI(vol) of 20 mGy (16 cm). The EI(CT) is introduced that provides a quantitative measure of the amount of the radiation used to generate images in any CT examination and is analogous to the average image receptor Exposure Index recently proposed for use in projection imaging. The EI(CT) metric provides operators with an objective index of the amount of the radiation used to create CT images and can be used to control quantum mottle in CT. PMID:23690648

  13. Methods of direct measurement of the refraction index of air using high-resolution laser interferometry.

    Czech Academy of Sciences Publication Activity Database

    ?íp, Ond?ej; Petr?, František; Matoušek, V.; Buchta, Z.; Lazar, Josef

    2004-01-01

    Ro?. 49, ?. 3 (2004), s. 88-90. ISSN 0447-6441 R&D Projects: GA AV ?R IBS2065009 Keywords : laser interferometry * refraction index * Fabry-Perot interferometer Subject RIV: BH - Optics, Masers, Lasers

  14. The role of air pollution in the relationship between a heat stress index and human mortality in Toronto

    International Nuclear Information System (INIS)

    In this study we considered confounding from air pollutants and chronological variables in the relation between humidex, a summer temperature and humidity index, and nonaccidental mortality, from 1980-1996 in Toronto, Canada. Changes in the risk of death by age group, gender, and combined cardiac-respiratory cause of death were estimated for both 1 deg. C and 50-95th percentile increases in humidex using a generalized additive linear model. With air pollution terms in the models, relative risk (RR) point estimates narrowly exceeded 1.0 for all groups. Humidex effects were most apparent for females (RR=1.006, 95% CI=1.004-1.008 per 1 deg. C humidex and RR=1.089, 95% CI=1.058-1.121 for 50th to 95th percentile humidex). When air pollution was omitted from the model, RR in the 50-95th percentile analysis increased less than 1.71% for all groups except females, for which RR decreased 1.42%. Differences in RR per 1 deg. C humidex were all less than 0.12%. Confidence intervals narrowed slightly for all groups investigated. Heat stress has a statistically significant, yet minimal impact on Toronto populations, and air pollution does appear to have a small, but consistent confounding effect on humidex effect estimates

  15. Evaluation of the Chinese New Air Quality Index (GB3095-2012) : Based on Comparison with the US AQI System and the WHO AQGs

    OpenAIRE

    Gao, Fanyu

    2013-01-01

    The “PM2.5 issue” was the tipping point for China’s clean air movement last year and the incentive for implementation of the new Air Quality Index (GB3095-2012). It is necessary to carry out an evaluation of the Chinese new AQI system based on comparison with developed countries and improve the system afterwards. The study evaluates the Chinese new Air Quality Index through comparison with the EPA AQI system and with the WHO AQGs as reference. The six mutual indicators have been sele...

  16. Comparison of entry kerma in the skin with the variation of automatic exposure control in mammography

    International Nuclear Information System (INIS)

    The purpose of this work was to analyze the entry kerma values in the skin in comparison with the automatic exposure control tests. To achieve that, 44 mammographies were evaluatecl in the city of Rio de Janeiro. The reference values adopted were taken from the current Brazilian legislation, 'Portaria no. 453/98 do Ministerio da Saude', where the reference entry kerma value in the skin corresponds to 10 mGy and the maximum variation accepted to the automatic exposure control test corresponds to 30 optic unities. It was observed that 46.7% of the analyzecl mammographies presented entry kerma values in the skin above the reference level established, whereas the automatic exposition control for these same mammographies was within the acceptability parameters. (author)

  17. Investigation of Humidity Effect on the Air Refractive Index using an Optical Fiber Design

    OpenAIRE

    Golnabi, H.; Mehrabani, A.

    2011-01-01

    In this study operation of an optical design based on the intensity modulation for the refractive index change has been described. The reported instrument measures the transmitted output power depending up on the medium refractive index in the light path of a fiber-to-fiber design. A liquid cell is located between the fibers in the light path and power variations for different cold and hot water levels in the cell are measured. By using a reference humidity meter the calibration curve represe...

  18. PLAM - a meteorological pollution index for air quality and its applications in fog-haze forecasts in north China

    Science.gov (United States)

    Yang, Y.; Wang, J.; Gong, S.; Zhang, X.; Wang, H.; Wang, Y.; Wang, J.; Li, D.; Guo, J.

    2015-03-01

    Using surface meteorological observation and high resolution emission data, this paper discusses the application of PLAM/h Index (Parameter Linking Air-quality to Meteorological conditions/haze) in the prediction of large-scale low visibility and fog-haze events. Based on the two-dimensional probability density function diagnosis model for emissions, the study extends the diagnosis and prediction of the meteorological pollution index PLAM to the regional visibility fog-haze intensity. The results show that combining the influence of regular meteorological conditions and emission factors together in the PLAM/h parameterization scheme is very effective in improving the diagnostic identification ability of the fog-haze weather in North China. The correlation coefficients for four seasons (spring, summer, autumn and winter) between PLAM/h and visibility observation are 0.76, 0.80, 0.96 and 0.86 respectively and all their significance levels exceed 0.001, showing the ability of PLAM/h to predict the seasonal changes and differences of fog-haze weather in the North China region. The high-value correlation zones are respectively located in Jing-Jin-Ji (Beijing, Tianjin, Hebei), Bohai Bay rim and the southern Hebei-northern Henan, indicating that the PLAM/h index has relations with the distribution of frequent heavy fog-haze weather in North China and the distribution of emission high-value zone. Comparatively analyzing the heavy fog-haze events and large-scale fine weather processes in winter and summer, it is found that PLAM/h index 24 h forecast is highly correlated to the visibility observation. Therefore, PLAM/h index has better capability of doing identification, analysis and forecasting.

  19. Calculated photon KERMA factors based on the LLNL EGDL [Evaluated Gamma-Ray Data Library] data file

    International Nuclear Information System (INIS)

    Photon (Gamma-Ray) KERMA factors calculated from the LLNL EGDL (Evaluated Gamma-Ray Data Library) file are tabulated for the elements from Z=1 to Z=30 and for 15 composite materials. The KERMA factors are presented for 191 energy groups over the incident photon energy range from 100 eV to 100 MeV. 3 refs

  20. Development of an Aggregate Air Quality Index Using a PCA-Based Method: A Case Study of the US Transportation Sector

    Directory of Open Access Journals (Sweden)

    Jaesung Choi

    2015-02-01

    Full Text Available For the past couple of decades, the transportation sector has made efforts to preserve and improve air quality for public health and sustainable growth between current and future generations. An easily understandable tool to measure the level of air pollution in the transportation sector by considering multiple air pollutants together might raise awareness about clean air to the public, practitioners, state policy planners, and the government. For this reason, this study develops an aggregate air quality index to help prepare decision makers, which could rank a state according to the different levels of multiple air pollutants. The index is developed for use with principal com-ponent analysis and an algebra about a line segment, and then applied to the US transportation sector using data on five air pollutants (CO, NOx, PM, SO2, and VOCs in 2008. This study finds that some states were less polluted or more polluted in terms of the index, although their GDP levels for a transport mode were similar to each other. Thus, this finding implies that the necessary actions for stricter air quality standards must be taken in their boundaries.

  1. Air Pollution Tolerance Index (APTI) of some tree species growing near rail roads of Madurai, Tamil Nadu (India).

    Science.gov (United States)

    Thambavani, D Sarala; Kamala, C

    2010-10-01

    Biological monitoring and assessment studies due to urban--rail road pollutants were carried out using Air Pollution Tolerance Index (APTI) of plants. Four plant (leaf) parameters--namely ascorbic acid, total chlorophyll, relative water content and leaf extract pH were combined together in a formulation signifying the APTI of plants. APTI was calculated for five different species such as Azadirachta indica, Delonix regia, Ficus religiosa, Pongamia pinnata and Polyalthia longifolia growing in two different areas, i.e. control area and along the railway track of Madurai, Tamil Nadu (India). The control site was selected in the college campus. None of the four plant parameters indicated a consistent response to pollutants. In the present study, Delonix regia and Pongamia pinnata lost the tolerance towards air pollutants and became more sensitive, but Azadirachta indica, Ficus religiosa, and Polyalthia longifolia indicated high APTI values over control area and hence considered as tolerant species. The APTI of plants showed a marked gradation as the pollutant load decreased from rail road to control area. The APTI can be used as a good indicator of impact of the air pollution on plants. PMID:22312796

  2. New calculation method of neutron kerma coefficients for carbon and oxygen below 30 MeV

    International Nuclear Information System (INIS)

    On the basis of the statistical theory of a neutron-induced light nucleus reaction, a new kerma coefficient calculation formula, expressed as k?=NijkEijk(En)?ijk(En), is developed in this paper. In an analysis of the n+12C and n+16O reactions below 30 MeV, the average energies Eijk of emitted particles of all kinds in the laboratory frame are derived in detail for different channels, allowing an exact energy balance. The optical model parameters of neutron and charged particles, which had reproduced very well the outgoing neutron double-differential cross sections in our early works, are used to obtain the cross sections ?ijk. The calculated partial, elastic recoil, and total kerma coefficients for carbon and oxygen are consistent with existing experimental kerma coefficient data. The elastic cross sections and the first Legendre coefficients of elastic angular distribution derived from EBDF/B-VIIb3 are used in this paper to improve significantly the elastic recoil and total kerma coefficients

  3. New calculation method of neutron kerma coefficients for carbon and oxygen below 30 MeV

    Science.gov (United States)

    Sun, Xiaojun; Qu, Wenjing; Duan, Junfeng; Zhang, Jingshang

    2008-11-01

    On the basis of the statistical theory of a neutron-induced light nucleus reaction, a new kerma coefficient calculation formula, expressed as k?=N?ijk?ijk(En)?ijk(En), is developed in this paper. In an analysis of the n+12C and n+16O reactions below 30 MeV, the average energies ?ijk of emitted particles of all kinds in the laboratory frame are derived in detail for different channels, allowing an exact energy balance. The optical model parameters of neutron and charged particles, which had reproduced very well the outgoing neutron double-differential cross sections in our early works, are used to obtain the cross sections ?ijk. The calculated partial, elastic recoil, and total kerma coefficients for carbon and oxygen are consistent with existing experimental kerma coefficient data. The elastic cross sections and the first Legendre coefficients of elastic angular distribution derived from EBDF/B-VIIb3 are used in this paper to improve significantly the elastic recoil and total kerma coefficients.

  4. Review of the research and application of KERMA factor and DPA cross section

    International Nuclear Information System (INIS)

    The data for recoil atom spectra, KERMA factor and displacement cross sections from neutron-induced reactions are calling increasing interest for applications to the study of radiation damage, calculation of heat generation in reactor, neutron therapy and biological research. PKA spectra sub-working group was recently established in Japanese Nuclear Data Committee as a part of developing JENDL Special Purpose Data Files. Current status of the data and various features of application of the KERMA-related problems were reviewed and discussed at the first meeting of the sub-working group. Present report is a compilation of the items presented at the meeting, covering a brief review of the existing research and the data, method of calculation, the KERMA factor data in neutron therapy, the deduction of KERMA factor of C-12 from neutron reaction measurement and analysis, the data base for radiation damage, the damage simulation calculation, and the method of storaging the evaluated data in ENDF/B-VI format. (author)

  5. Precision positioning with suppression of the influence of refractive index of air.

    Czech Academy of Sciences Publication Activity Database

    Holá, Miroslava; Hrabina, Jan; Oulehla, Jind?ich; ?ížek, Martin; Mikel, B?etislav; ?e?ucha, Šimon; Buchta, Zden?k; ?íp, Ond?ej; Lazar, Josef

    Bellingham : SPIE, 2013, 878831:1-7. ISBN 978-0-8194-9604-1. [Optical Measurement Systems for Industrial Inspection /8./. Munich (DE), 13.05.2013-16.05.2013] R&D Projects: GA ?R GA102/09/1276; GA ?R GPP102/11/P820; GA TA ?R TA02010711; GA TA ?R TE01020233; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : nanometrology * refractometry * interferometry * refractive index * nanoscale Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. Assessment of skin entrance Kerma in the United States: the nationwide evaluation of X ray trends (next)

    International Nuclear Information System (INIS)

    The Nationwide Evaluation of X ray Trends (NEXT) is an annual survey programme to estimate national skin entrance air kerma, free-in-air, for representative diagnostic X ray examinations. It is conducted in the United States cooperatively between the federal government's Food and Drug Administration (FDA) and the various state and local governments through the coordinating agency known as the conference of Radiation Control Program Directors (CRCPD). NEXT originally began in 1973 and in 1983 it underwent a major change; limiting the annual survey to one examination, using standard attenuation phantoms for the measurement of exposure, empirically evaluating film processing, and the collection of comprehensive technical data such as tube potential, half value layer (HVL), type of film, screen, grid, and optical density of the resulting phantom radiograph. Surveys have been performed for chest radiography (1984 and 1986), the abdomen and lumbosacral spine examination (1987 and 1989), mammography (1985 and 1988), computerised tomography (CT) (1990), and currently fluoroscopy (1991). The mammography and fluoroscopy examinations differ from the other surveys by incorporating image quality test objects

  7. Elucidating inequality in Nubia: an examination of entheseal changes at Kerma (Sudan).

    Science.gov (United States)

    Schrader, Sarah A

    2015-02-01

    Located 10 km south of the Third Cataract of the Nile River, the ancient city of Kerma was once capital to the second largest state in Africa. The Eastern Cemetery at Kerma (?4 km east of city center) encompasses 80+ hectares and was used over a period of 1,500 years (3,200-1,500 BC). Excavated in the early 20th century by George Reisner, the cemetery contained an estimated 20,000-40,000 individuals. Reisner classified these burials into multiple categories, including chiefs and human sacrifices, based on burial position and grave goods. This study investigates the skeletal embodiment of social inequality by examining variation in entheseal severity between the Kerma burial classifications. Seventeen entheses were examined using the Hawkey and Merbs (1995) scoring method (n?=?205 individuals); age, sex, and body size variables were considered by employing Mann-Whitney U tests and partial Spearman's correlations. This analysis suggests that significant differences in entheseal changes existed between select burial types. Specifically, "corridor sacrifices" had significantly higher rates of entheseal changes while "chiefs" and "subsidiary burials" had similar entheseal changes; furthermore, within these burial categories, males had higher entheseal scores despite body size controls. The elevated entheseal changes in the sacrificial burials may be due to an intensive agro-pastoral lifestyle or other demanding forms of manual labor. In conclusion, the disparity of entheseal markers between burial subgroups at Kerma might reflect a degree of social inequality within this state level society. This bioarchaeological research informs our understanding of socially-defined categories of persons as well as everyday life in Ancient Kerma. PMID:25327628

  8. Spatial and temporal analysis of Air Pollution Index and its timescale-dependent relationship with meteorological factors in Guangzhou, China, 2001–2011

    International Nuclear Information System (INIS)

    There is an increasing interest in spatial and temporal variation of air pollution and its association with weather conditions. We presented the spatial and temporal variation of Air Pollution Index (API) and examined the associations between API and meteorological factors during 2001–2011 in Guangzhou, China. A Seasonal-Trend Decomposition Procedure Based on Loess (STL) was used to decompose API. Wavelet analyses were performed to examine the relationships between API and several meteorological factors. Air quality has improved since 2005. APIs were highly correlated among five monitoring stations, and there were substantial temporal variations. Timescale-dependent relationships were found between API and a variety of meteorological factors. Temperature, relative humidity, precipitation and wind speed were negatively correlated with API, while diurnal temperature range and atmospheric pressure were positively correlated with API in the annual cycle. Our findings should be taken into account when determining air quality forecasts and pollution control measures. - Highlights: • Air pollution is still serious in Guangzhou, China. • Air Pollution Index was associated with a variety of meteorological parameters. • The temporal relationships were timescale-dependent. • The findings should be taken into account in air quality forecasts and pollution control. - Spatial and temporal variation of API and its timescale-dependent relationship with meteorological factors in Guangzhou were demonstrated

  9. A consistent set of neutron kerma coefficients from thermal to 150 MeV for biologically important materials

    International Nuclear Information System (INIS)

    Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determine kerma coefficients for calculations of energy deposition by neutrons in matter. Methods used to evaluate the neutron cross sections above 20 MeV, using nuclear model calculations and experimental data, are described. Below 20 MeV, the evaluated cross sections from the ENDF/B-VI library are adopted. Comparisons are shown between the evaluated charged-particle production cross sections and measured data. Kerma coefficients are derived from the neutron cross sections, for major isotopes of H, C, N, O, Al, Si, P, Ca, Fe, Cu, W, Pb, and for ICRU-muscle, A-150 tissue-equivalent plastic, and other compounds important for treatment planning and dosimetry. Numerous comparisons are made between our kerma coefficients and experimental kerma coefficient data, to validate our results, and agreement is found to be good. An important quantity in neutron dosimetry is the kerma coefficient ratio of ICRU-muscle to A-150 plastic. When this ratio is calculated from our kerma coefficient data, and averaged over the neutron energy spectra for higher-energy clinical therapy beams [three p(68)+Be beams, and a d(48.5)+Be beam], a value of 0.94±0.03 is obtained. Kerma ratios e of 0.94±0.03 is obtained. Kerma ratios for water to A-150 plastic, and carbon to oxygen, are also compared with measurements where available. copyright 1999 American Association of Physicists in Medicine

  10. Use of Segregation Indices, Townsend Index, and Air Toxics Data to Assess Lifetime Cancer Risk Disparities in Metropolitan Charleston, South Carolina, USA

    Directory of Open Access Journals (Sweden)

    LaShanta J. Rice

    2014-05-01

    Full Text Available Background: Studies have demonstrated a relationship between segregation and level of education, occupational opportunities, and risk behaviors, yet a paucity of research has elucidated the association between racial residential segregation, socioeconomic deprivation, and lifetime cancer risk. Objectives: We examined estimated lifetime cancer risk from air toxics by racial composition, segregation, and deprivation in census tracts in Metropolitan Charleston. Methods: Segregation indices were used to measure the distribution of groups of people from different races within neighborhoods. The Townsend Index was used to measure economic deprivation in the study area. Poisson multivariate regressions were applied to assess the association of lifetime cancer risk with segregation indices and Townsend Index along with several sociodemographic measures. Results: Lifetime cancer risk from all pollution sources was 28 persons/million for half of the census tracts in Metropolitan Charleston. Isolation Index and Townsend Index both showed significant correlation with lifetime cancer risk from different sources. This significance still holds after adjusting for other sociodemographic measures in a Poisson regression, and these two indices have stronger effect on lifetime cancer risk compared to the effects of sociodemographic measures. Conclusions: We found that material deprivation, measured by the Townsend Index and segregation measured by the Isolation index, introduced high impact on lifetime cancer risk by air toxics at the census tract level.

  11. Studies on mass attenuation coefficient, mass energy absorption coefficient and kerma of some vitamins

    International Nuclear Information System (INIS)

    Highlights: ? Kerma is essential for nuclear medicine, diagnostics and radiation dosimeter. ? The values of ?m and ?e/? depends on the photon energy and chemical content of vitamins. ? New experiments should be performed to study physical parameters of biomolecules. -- Abstract: The mass attenuation coefficients for some vitamins (retinol, beta-carotene, thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, biotin, folic acid, cyanocobalamin, ascorbic acid, cholecalciferol, alpha-tocopherol, ketamine, hesperidin) were determined experimentally and theoretically at 356.61, 661.66, 1250 and 1408.01 keV photon energies by using a NaI(Tl) scintillation detector. Also, the mass energy absorption coefficients and kerma have been calculated. The calculated values were compared with the semi-empirical values for vitamins.

  12. A simple device for the measurement of kerma based on commercial PIN photo diodes.

    Czech Academy of Sciences Publication Activity Database

    Kushpil, Vasilij; Kushpil, Svetlana; Hu?a, Zden?k

    Cedex : EDP Sciences, 2012, s. 1-9. ISBN 978-88-7438-069-5. ISSN 2100-014X. [International Conference on Environmental Radioactivity - New Frontiers and Developments. ?ím (IT), 25.10.2010-27.10.2010] R&D Projects: GA MŠk LC07048 Institutional support: RVO:61389005 Keywords : PIN diode * kerma measurement Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  13. Determination of the kerma in the neutron field produced by a fast reactor

    International Nuclear Information System (INIS)

    A description is given of the principle, method and technology to determine the tissue kerma rates of the neutron and ?-rays in a fission neutron field produced by a fast reactor with a IRM81-TE1 tissue-equivalent ionization chamber made in China and a low neutron sensitivity energy-compensated G-M counter. Meanwhile, measurements are made with a FWTIC-17A tissue-equivalent ionization chamber. The results determined with the two chambers agree well with each other

  14. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.

    2008-01-01

    The effective atomic number, Z(eff), the effective electron density, N-el, and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. The significant variation of Z(eff) and N-el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z(eff) and N-el are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z(eff) and N-el are found at intermediate energies, typically 0.05 MeV kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the MeV range, where Compton scattering is the main interaction process.

  15. Measurement of air-refractive-index fluctuation from laser frequency shift with uncertainty of order 10?9

    International Nuclear Information System (INIS)

    In the previous work (Ishige et al 2009 Meas. Sci. Technol. 20 084019), we presented a method of measuring the relative air-refractive-index fluctuation (?nair) from the laser frequency shift with the measurement uncertainty of order 10?8 using a phase modulation homodyne interferometer (Basile et al 1991 Metrologia 28 455), which was supported by an ultralow thermal expansion material (ULTEM) and an external cavity laser diode (ECLD). In this paper, an improvement in the uncertainty of the ?nair measurement is presented. The improvement method is based on a Fabry–Perot cavity constructed on the ULTEM, which has a thermal expansion coefficient of 2 × 10?8 K?1 and an ECLD. The Pound–Drever–Hall method (Drever et al 1983 Appl. Phys. B 31 97) is also used to control the ECLD frequency to track the resonance of the cavity. ?nair can be derived from the ECLD frequency shift. The estimated measurement uncertainty of ?nair for a short time (?150 s) in the experiment is of order 2.5 × 10?9 or less

  16. Calibration of dosimeters used in diagnostic radiology in terms of air kerma rate

    International Nuclear Information System (INIS)

    This study was performed to determine IEC reference radiation beam quality for calibrating dosimeters used in diagnostic radiology. Additional filtration required to establish certain IEC quality was estimated from beam transmission measurements using Al absorbers. The experiment was carried out using medical x-ray equipment at Neelain Medical Center, Khartoum. The required added filtration thickness required to establish RQA quality was estimated according to the the method described in the IEC standard. The required filtration was estimated for each of radiation quality (40, 60, 80, 100, 120,) kV. Result showed the maximum deviation of 2.3%, for the half value-layers, which complied with the standard requirement of 3%, the additional filtration required for the RQA qualities was found to as follows: 1.2 mmAL (RQA2, 40 kV), 11.0 mmAL (RQA3, 60 kV), 20.7 mmAL ( RQA4, 80 kV), 29.5 mmAL (RQA5, 100 kV) and 33.0 mmAL (AQA6, 120 kV), those qualities recommended to be applied to calibration of the diagnostic radiology measurements instruments in Sudan.(Author)

  17. Doses monitoring in radiology: calibration of air kerma-area product (PKA) meters

    International Nuclear Information System (INIS)

    Materials and methods: different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm3 cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results: the lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion: the calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference. (author)

  18. Primary standardization of 137Cs Amersham source in terms of air kerma strength

    International Nuclear Information System (INIS)

    The objective of the present work was to determine the AKS of the source using the primary graphite chamber and compare with the value quoted in the certificate so as to have an indirect intercomparison with NIST, USA

  19. A design of brachytherapy source calibration template for air kerma rate/activity measurement

    International Nuclear Information System (INIS)

    This simple template can be used for the purpose of calibration of brachytherapy source, if the department does not have the calibration-track stand. One can design this template in the hospital itself as per the requirement, availability and facility, and the expenses also will be less. It is fully made up of a very thin 0.75 mm thickness of paper cardboard and this is the speciality. Currently this template is being utilized for accurate and easy calibration purposes

  20. BIPM and COMECON comparisons of air kerma standards in X- and ?-radiation fields

    International Nuclear Information System (INIS)

    The results of comparisons undertaken by a regional metrology organization at several x- and ?-ray qualities are compared with those of BIPM international comparisons. The results are statistically coherent in most cases. (authors)

  1. The smart electronic unit for precise measurement of refractive index of air in a nano-positioning stage for scanning probe microscopy (SPM).

    Czech Academy of Sciences Publication Activity Database

    Hucl, Václav; ?ížek, Martin; Buchta, Zden?k; Mikel, B?etislav; Lazar, Josef; ?íp, Ond?ej

    Ostrava : TANGER Ltd, 2012, s. 817-821. ISBN 978-80-87294-32-1. [NANOCON 2012. International Conference /4./. Brno (CZ), 23.10.2012-25.10.2012] R&D Projects: GA MPO FR-TI2/705; GA MPO FR-TI1/241; GA ?R GAP102/10/1813 Institutional support: RVO:68081731 Keywords : refractive index of air * precise measurement * laser interferometer Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Doses monitoring in radiology: calibration of air kerma-area product (PKA) meters / Monitoração de doses em radiologia: a calibração de medidores do produto kerma-área (PKA)

    Scientific Electronic Library Online (English)

    Ricardo Andrade, Terini; Maria Carolina de Santana, Campelo; Jose Neres de, Almeida Jr.; Silvio Bruni, Herdade; Marco Aurelio Guedes, Pereira.

    2013-12-01

    Full Text Available Objective The authors have sought to study the calibration of a clinical PKA meter (Diamentor E2) and a calibrator for clinical meters (PDC) in the Laboratory of Ionizing Radiation Metrology at Instituto de Energia e Ambiente - Universidade de São Paulo. Materials and Methods Different qualities [...] of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm3 cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results The lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion The calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference.

  3. Scattering study at free air ionization chamber diaphragm

    International Nuclear Information System (INIS)

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are kRQR-M1=0,9946, kRQR-M2=0,9932, kRQR-M3=0,9978 and kRQR-M4=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  4. Comparison of entry kerma in the skin with the variation of automatic exposure control in mammography;Comparacao do kerma de entrada na pele com a variacao do controle automatico de exposicao em exames mamograficos

    Energy Technology Data Exchange (ETDEWEB)

    Macao Junior, J.L. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Mecca, F.A. [Instituto Nacional de Cancer (INCa), Rio de Janeiro, RJ (Brazil); Gomes, B.C. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The purpose of this work was to analyze the entry kerma values in the skin in comparison with the automatic exposure control tests. To achieve that, 44 mammographies were evaluatecl in the city of Rio de Janeiro. The reference values adopted were taken from the current Brazilian legislation, 'Portaria no. 453/98 do Ministerio da Saude', where the reference entry kerma value in the skin corresponds to 10 mGy and the maximum variation accepted to the automatic exposure control test corresponds to 30 optic unities. It was observed that 46.7% of the analyzecl mammographies presented entry kerma values in the skin above the reference level established, whereas the automatic exposition control for these same mammographies was within the acceptability parameters. (author)

  5. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources

    International Nuclear Information System (INIS)

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 106 n/s-?g and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for En > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with En > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of 252Cf, to optimize and to individualize the patients treatments. (Author)

  6. The variability in kerma output and radiation quality of medical diagnostic x-ray units

    International Nuclear Information System (INIS)

    The use of diagnostic x-ray tubes results in an increased roughness of the anode surface. This effect of tube ageing increases the inherent filtration of the x-ray tube, hereby reducing kerma output and changing radiation quality. To study this effect, used rotating anodes were collected; the surface profiles and surface roughness of 8 focal tracks were determined. The surface profiles were then used to calculate x-ray spectra using a computer code. The results indicate that an increased roughness induces an additional filtration in the tungsten anode. The roughest surface (Ra=5.22 ?m) yields a mean additional absorber thickness in direction of the x-ray beam of about 18 ?m with a corresponding loss in kerma output of about 30 % at 70 kV. The effects on mean photon energy and HVL are rather small but highest around 70 kV and lowest at 140 kV. This is due to the K-edge in the attenuation coefficients of tungsten at 69.5 keV. To study the influence of tube ageing on beam quality with clinical x-ray units, kerma measurements were made for 19 samples as to determine attenuation curves. A fit method for the determination of total filtration including the effects of anode surface deterioration was devised. The thicknesses of the tungsten layers obtained using this method vary from 2.43 ?m to 11.89 ?m with an associated surface roughness Ra from 1.5 to 4.5 ?m corresponding very well to the thicknesses of the additional absorbing layers determined for rough anodes. A detrs determined for rough anodes. A determination of additional filtration in terms of an equivalent aluminium filter gave thicknesses from 0.34 to 1.72 mm aluminium. The results showed that the effects of tube ageing on the x-rays could be described by an additional filtration of aluminium. (author)

  7. Air

    International Nuclear Information System (INIS)

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  8. Using daily air temperature thresholds to evaluate snow melting occurrence and amount on Alpine glaciers by T-index models: the case study of the Forni Glacier (Italy)

    Science.gov (United States)

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

    2014-10-01

    Glacier melt conditions (i.e., null surface temperature and positive energy budget) can be assessed by analyzing data acquired by a supraglacial automatic weather station (AWS), such as the station installed on the surface of Forni Glacier (Italian Alps). When an AWS is not present, the assessment of actual melt conditions and the evaluation of the melt amount is more difficult and simple methods based on T-index (or degree days) models are generally applied. These models require the choice of a correct temperature threshold. In fact, melt does not necessarily occur at daily air temperatures higher than 0 °C. In this paper, we applied both energy budget and T-index approaches with the aim of solving this issue. We start by distinguishing between the occurrence of snowmelt and the reduction in snow depth due to actual ablation (from snow depth data recorded by a sonic ranger). Then we find the daily average temperature thresholds (by analyzing temperature data acquired by an AWS on Forni Glacier) which, on the one hand, best capture the occurrence of significant snowmelt conditions and, on the other, make it possible, using the T-index, to quantify the actual snow ablation amount. Finally we investigated the applicability of the mean tropospheric lapse rate to reproduce air temperature conditions at the glacier surface starting from data acquired by weather stations located outside the glacier area. We found that the mean tropospheric lapse rate allows for a good and reliable reconstruction of glacier air temperatures and that the choice of an appropriate temperature threshold in T-index models is a very important issue. From our study, the application of the +0.5 °C temperature threshold allows for a consistent quantification of snow ablation while, instead, for detecting the beginning of the snow melting processes a suitable threshold has proven to be at least -4.6 °C.

  9. Kerma factors for neutrons of 14 MeV to 60 MeV in elemental H, C, N and O

    International Nuclear Information System (INIS)

    Total kerma factors, and partial kerma factors for production of specified charged H and He particles and heavier recoils, have been computed using basic theoretical and experimental nuclear data for neutrons at energies between 14 MeV and 60 MeV in the main tissue elements and in ICRU muscle tissue. All the more recent computations of total kerma factors, along with those determined from direct experimental measurements of partial kerma factors, now form a reasonably consistent set of data enabling average total kerma factors with coefficients of better than 3% for hydrogen, 16% for carbon, 23% for nitrogen and 9% for oxygen to be recommended for application to medical dosimetry and radiation protection. Total kerma factors for ICRU muscle tissue have a precision of better than 2.5% over the neutron energy range considered. Although there is adequate precision for total kerma factors for soft tissue, nevertheless analysis of the partial kerma factors indicates that caution must be exercised in use of the information for quality specification, e.g. in microdose spectra, and that more detailed basic reaction data is required for fast neutrons. (author)

  10. Local control related to Kerma rate in T2/T3 breast cancers treated by external irradiation and brachytherapy

    International Nuclear Information System (INIS)

    Introduction: This study was conducted to determine the impact of the brachytherapy parameters on local control in patients treated with irradiation alone for breast cancer. Material and Methods: From 1985 to 1991, 241 patients with T2 (187pts) T3 (54 pts) N0 (196 pts) N1 (45 pts) M0 breast cancer have been treated with the combination of external irradiation and brachytherapy boost without surgery. Doses delivered to the whole breast and the regional nodes were 54 Gy and 50 Gy respectively (1.8 or 2 Gy/fraction, 5 fr/wk). Twenty Gy were then boosted to the primary tumor, according to the tumor shrinkage, by Ir 192 implants. Plastic tubes and rigid needles were used in 85 % and 15 % of the cases respectively. The brachytherapy boost was delivered at 85% of the basal dose rate (Reference dose rate) according to the Paris system. In some instances, dose distribution heterogeneities were observed leading to the choice of another reference isodose. Results: Median follow-up for the entire population was 75 months (9-122). Local control at 6 years follow-up for T2 and T3 was 76% (+/- 6%). Age, SBR grading and steroid receptors were found to be significantly correlated to local control. The role of the brachytherapy boost was analysed. Reference dose rate was not found to have any impact on local control, (? 0.6 vs > 0.6 Gy/h). This result was perhaps linked to the particular choice of the reference isodose. To avoid this bias we have evaluated the impact of the Kerma ratve evaluated the impact of the Kerma rate (Activity x Time x total length) on local control. Median kerma rate was 8600 ?Gy h-1 cm-1 m2 (2200-16600). Local control rate for T2 at 6 years was 77% +/- 8% (Kerma >8600) and 73 %+/- 10% (Kerma ? 8600). For T3 local control rate was 82% +/-12% (Kerma >8600) and 37 % +/- 34 % (p<0.0002). Conclusion: This study demonstrated that the impact of brachytherapy on local control was better evaluated by the Kerma rate than by the reference dose rate. Whereas the basal dose rate cannot be changed after the application, it may be possible to adapt the kerma parameters (activity, length, treatment duration) in order to achieve a more efficient treatment

  11. Obtención de un índice de riesgo de erosión eólica y su aplicación en la provincia de Buenos Aires, Argentina Erosion risk index attainment and its application in the Buenos Aires province, Argentina

    Directory of Open Access Journals (Sweden)

    Susana Goldberg

    2004-12-01

    Full Text Available En este trabajo se propone un índice climático para estimar el riesgo de ocurrencia de erosión eólica basado en las leyes físicas que cuantifican el efecto de la agresión del medio (turbulencia atmosférica sobre la resistencia del sistema (textura del suelo. Este indicador es obtenido en función de observaciones meteorológicas estándar a partir de un modelo que incluye la alteración del perfil vertical del viento ocasionada por la presencia de partículas de suelo en el aire y es expresado en términos de la probabilidad de que la potencia del viento supere las condiciones umbrales para el comienzo del proceso. Si bien el índice fue obtenido para suelo seco y desnudo, la metodología permite avanzar hacia un modelo de evaluación de riesgo más general, si se determinan previamente los valores de velocidad de fricción umbral que corresponden a distintas condiciones que afectan la resistencia del suelo tales como la humedad del suelo, el contenido de materia orgánica, cobertura y uso de la tierra. Este modelo ha sido utilizado para evaluar la distribución espacial del riesgo de erosión eólica en la Provincia de Buenos Aires, Argentina.This paper proposes a climatic index to estimate the wind erosion risk based upon physical laws that quantify the effect of environment's aggression (atmospheric turbulence on system resistance (soil texture. This index is obtained as a function of standard meteorological observations including the alteration of the wind profile produced by the presence of soil particles in the air and it is expressed in terms of the probability for the wind power to exceed the threshold conditions. Although this index was obtained for dry and bare soil, it may mean an advance towards a more general model for risk evaluation if other factors intervening in soil resistance, such as soil humidity, organic material content, land cover and use are included. This model has been used to evaluate the spatial distribution of the wind erosion risk in Buenos Aires Province, Argentina.

  12. High-Q and high-sensitivity width-modulated photonic crystal single nanobeam air-mode cavity for refractive index sensing.

    Science.gov (United States)

    Yang, Daquan; Tian, Huiping; Ji, Yuefeng

    2015-01-01

    We propose a novel optical sensor based on a one-dimensional (1D) photonic crystal (PhC) single nanobeam air-mode cavity (SNAC). The performance of the device is investigated theoretically. By introducing a quadratically modulated width tapering structure, a waveguide-coupled 1D-PhC SNAC with a calculated high quality factor of 5.16×106 and an effective mode volume of Veff?2.18(?/nsi)3 can be achieved. For the air mode mentioned above, the light field can be strongly localized inside the air region (low index) and overlaps sufficiently with the analytes. Thus, the suggested PhC SNAC can be used for high-sensitivity refractive index sensing with an estimated high sensitivity of 537.8 nm/RIU. To the best of our knowledge, this is the first PhC single nanobeam geometry that features both high Q-factors and high sensitivity, and is potentially an ideal platform for realizing ultracompact lab-on-a-chip applications with dense arrays of functionalized spots for multiplexed sensing. PMID:25966999

  13. Measurement of air-refractive-index fluctuation from frequency change using a phase modulation homodyne interferometer and an external cavity laser diode

    International Nuclear Information System (INIS)

    We present a method for air-refractive-index (nair) fluctuation measurement using a laser interferometer. The method is based on a combination of a phase modulation homodyne interferometer (PMHI), an external cavity laser diode (ECLD) and an ultralow thermal expansion material (ULTEM). The PMHI utilizes a Michelson interferometer which is constructed on the ULTEM plate under the condition of an air temperature fluctuation of less than 10 mK, so that the optical path change or the air-refractive-index fluctuation (?nair) caused by the thermal disturbance can be neglected. Meanwhile, the ECLD is controlled by adjusting its frequency to track some of the dark fringes of the interferometer, so that ?nair can be derived from the ECLD frequency change. The uncertainty of the ?nair measurement in the experiment is of 10?8 order. However, it will be possible to decrease the uncertainty to 10?9 or less if the signal-to-noise ratio (SNR) of the control system is improved

  14. Applicability of the Environmental Relative Moldiness Index for Quantification of Residential Mold Contamination in an Air Pollution Health Effects Study

    Science.gov (United States)

    As part of the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS) investigating the respiratory health impacts of traffic-related air pollutants on asthmatic children in Detroit, Michigan, residential dust samples were collected to quantify mold exposure. Sett...

  15. Is Human Development Index (HDI) a reflector of quality of air? a comparative study on developed and developing countries

    OpenAIRE

    Santra, Swarup

    2014-01-01

    Economic Indicators alone cannot capture the totality of ‘Quality of Life’ (QOL). The Most acceptable Measure of QOL is the ‘Human Development Index’ (HDI) of UNDP. HDI is a composite Index of three Indicators of three essential dimensions of life. These three indicators are of per capita GDP adjusted to purchasing power, life expectancy at birth, and adult literacy rate(including the gross school enrollment ratios). While, the measurement of HDI is considered as a measure of Human...

  16. Tissue kerma vs distance relationships for initial nuclear radiation from the atomic devices detonated over Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Initial nuclear radiation is comprised of prompt neutrons and prompt primary gammas from an exploding nuclear device, prompt secondary gammas produced by neutron interactions in the environment, and delayed neutrons and delayed fission-product gammas from the fireball formed after the nuclear device explodes. These various components must all be considered in establishing tissue kerma vs distance relationships which describe the decrease of initial nuclear radiation with distance in Hiroshima and in Nagasaki. The tissue kerma at ground evel from delayed fission-product gammas and delayed neutrons was investigated using the NUIDEA code developed by Science Applications, Inc. This code incorporates very detailed models which can take into account such features as the rise of the fireball, the rapid radioactive decay of fission products in it, and the perturbation of the atmosphere by the explosion. Tissue kerma vs distance relationships obtained by summing results of these current state-of-the-art calculations will be discussed. Our results clearly show that the prompt secondary gammas and delayed fission-product gammas are the dominant components of total tissue kerma from initial nuclear radiation in the cases of the atomic (or pure-fission) devices detonated over Hiroshima and Nagasaki

  17. Neutron spectra and neutron kerma derived from activation and fission detector measurements in a d + T neutron therapy beam

    International Nuclear Information System (INIS)

    Neutron spectra at different positions in a phantom have been derived from activation foil and fission counter measurements for the collimated beam of the Amsterdam d + T fast-neutron therapy facility. The spectra show that the fraction of lower-energy neutrons increases with increasing depth in the phantom as well as with increasing distance from the central axis of the beam. Calculation of the ratios of kerma values in tissue and tissue-equivalent (TE) plastic and of Wsub(N) values for the spectra at five positions in the phantom, showed that the variations in these quantities are less than 0.5%. Kerma values have been derived from the neutron spectra and from the fission counter measurements separately. These neutron kerma values were compared with the neutron absorbed dose values derived from combined TE ionisation chamber and GM counter measurements. The dose values have been obtained applying recommendations given in the European protocol for neutron dosimetry for external beam therapy. At 50 mm and 100 mm depth along the central axis of the beam in the phantom, the agreement between the three methods was within 2%. In the penumbra region a maximum difference of about 7% has been observed between the three methods. The contribution from thermal neutrons to the total kerma is less than 1% in the beam as well as in the penumbra. (author)

  18. Uncontrolled combustion of shredded tires in a landfill - Part 2: Population exposure, public health response, and an air quality index for urban fires

    Science.gov (United States)

    Singh, Ashish; Spak, Scott N.; Stone, Elizabeth A.; Downard, Jared; Bullard, Robert L.; Pooley, Mark; Kostle, Pamela A.; Mainprize, Matthew W.; Wichman, Michael D.; Peters, Thomas M.; Beardsley, Douglas; Stanier, Charles O.

    2015-03-01

    The Iowa City Landfill in eastern Iowa, United States, experienced a fire lasting 18 days in 2012, in which a drainage layer of over 1 million shredded tires burned, generating smoke that impacted the surrounding metropolitan area of 130,000 people. This emergency required air monitoring, risk assessment, dispersion modeling, and public notification. This paper quantifies the impact of the fire on local air quality and proposes a monitoring approach and an air quality index (AQI) for use in future tire fires and other urban fires. Individual fire pollutants are ranked for acute and cancer relative risks using hazard ratios, with the highest acute hazard ratios attributed to SO2, particulate matter, and aldehydes. Using a dispersion model in conjunction with the new AQI, we estimate that smoke concentrations reached unhealthy outdoor levels for sensitive groups out to distances of 3.1 km and 18 km at 24-h and 1-h average times, respectively. Modeled and measured concentrations of PM2.5 from smoke and other compounds such as VOCs and benzo[a]pyrene are presented at a range of distances and averaging times, and the corresponding cancer risks are discussed. Through reflection on the air quality response to the event, consideration of cancer and acute risks, and comparison to other tire fires, we recommend that all landfills with shredded tire liners plan for hazmat fire emergencies. A companion paper presents emission factors and detailed smoke characterization.

  19. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil

    International Nuclear Information System (INIS)

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  20. Precision refractive index measurements of air, N2, O2, Ar, and CO2 with a frequency comb

    International Nuclear Information System (INIS)

    We report precision measurements of the refractive indices of dry air, N2, O2, Ar, and CO2, performed by using a frequency comb as the light source in a Mach-Zehnder interferometer setup. Improved dispersion formulas for all gases are derived with a sensitivity level of 10-9. These results are valid for a wavelength range from 740 to 860 nm and are in good agreement with measurements from other groups

  1. Nuclear data evaluation for 12C in the energy region more than 20 MeV and kerma factor calculation

    International Nuclear Information System (INIS)

    We have developed a practical code system to calculate double differential cross sections of all emitted particles and kerma factors for the n+12C reaction in the energy region from 20 to 80 MeV, and compared the results calculated using the code system with experimental data. As a result, it has been found that the code system is applicable to nuclear data evaluation of 12C in JENDL high energy file. (author)

  2. High NDVI and Potential Canopy Photosynthesis of South American Subtropical Forests despite Seasonal Changes in Leaf Area Index and Air Temperature

    Directory of Open Access Journals (Sweden)

    Piedad M. Cristiano

    2014-02-01

    Full Text Available The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI, chlorophyll concentration, and air temperatures of NE Argentina subtropical forests throughout the year. We included in the analysis several tree plantations (Pinus, Eucalyptus and Araucaria species that are known to have high productivity. Field studies in native forests and tree plantations were conducted; stem growth rates, LAI and leaf chlorophyll concentration were measured. MODIS satellite-derived LAI (1 km SIN Grid and NDVI (250m SIN Grid from February 2000 to 2012 were used as a proxy of seasonal dynamics of potential photosynthetic activity at the stand level. The remote sensing LAI of the subtropical forests decreased every year from 6 to 5 during the cold season, similar to field LAI measurements, when temperatures were 10 °C lower than during the summer. The yearly maximum NDVI values were observed during a few months in autumn and spring (March through May and November, respectively because high and low air temperatures may have a small detrimental effect on photosynthetic activity during both the warm and the cold seasons. Leaf chlorophyll concentration was higher during the cold season than the warm season which may have a compensatory effect on the seasonal variation of the NDVI values. The NDVI of the subtropical forest stands remained high and fairly constant throughout the year (the intra-annual coefficient of variation was 1.9%, and were comparable to the values of high-yield tree plantations. These results suggest that the humid subtropical forests in NE Argentina potentially could maintain high canopy photosynthetic activity throughout the year and thus this ecosystem may be a large carbon sink.

  3. Uncertainty of kerma factors in neutron dosimetry at Esub(n) = 14.5 MeV

    International Nuclear Information System (INIS)

    Assuming that the dominant part of the uncertainty in the kerma ratio is due to the kerma factors of Carbon and Oxygen, it is concluded that the uncertainty in tissue-equivalent ion chamber or calorimeter measurements of absorbed dose in tissue results from calculation of the kerma factors alone before other component uncertainties are considered. In the case of carbon the following conclusions are made: 1) In the reaction 12C(n,n'3?) the energy partition between n' and 3? should be investigated. 2) The uncertainties in the elastic scattering data should be reduced. 3) The uncertainties in the total cross section data should be reduced. In the case of oxygen it is concluded that the elastic scattering data should be accurately measured to allow application of the sum rule in order to extract cross-sections of three and more particle decay reactions such as 16O(n,n'?) and 16O(n,n'p). Also, the energy partition between the n' and the charged particles in these reactions should be studied. (U.K.)

  4. Patient Specific Kerma Area Product as an Exposure Estimator in Computed Tomography: The Concept and Typical Values

    International Nuclear Information System (INIS)

    Monitoring of exposure levels in computed tomography is important from the radiation safety point of view. In this paper, the concept suggested by Huda of using the patient specific kerma area product as an exposure estimator is extended by providing both a rigorous definition of this quantity and a method for its evaluation. The method was demonstrated on an axial scan of the standard CT dosimetry head phantom taken with a Siemens Somatom Open CT scanner. The resulting patient specific kerma area product was 0.25 Gy cm2 for the X ray tube voltage of 120 kV, tube current of 100 mA, scanning time of 1 s, and beam width at the isocentre of 1.2 cm. To implement this method, the CT scanner must be equipped with a KAP meter, and the calculation procedure must be added to the scanner's software. Alternatively, the patient specific kerma area product can be calculated by the CT scanner without using a KAP meter. In this case, however, the extra safety feature provided by the direct monitoring of the X ray beam by the KAP meter is lost. (author)

  5. Measurement of the structure coefficient of refractive index fluctuations in a turbulent premixed butane-air flame by means of a laser-based interferometer technique

    Science.gov (United States)

    Ngo Nyobe, Elisabeth; Pemha, Elkana; Hona, Jacques; Bilong, Jean; Lamara, Maurice

    2014-08-01

    With a view to measuring the structure coefficient of refractive index fluctuations in a turbulent premixed butane-air flame, a thin laser beam is sent into the flame perpendicular to the flow direction. The laser beam generally undergoes fluctuations of direction, phase, and amplitude. Only the random deflections of the laser beam may be taken into account. After having traversed the flame, the perturbed laser beam enters into an interferometric system. Materials and experimental procedure are described. In the unperturbed interference pattern, the zones only sensitive to fluctuations of the angle-of-arrival of the laser beam are detected. From the random displacements of the central bright fringe, the structure coefficient of refractive index fluctuations in the flame is measured. To prove that the method of measurement is satisfactory, the result obtained is applied for computing the power spectral density of the angle-of-arrival of the laser beam from the formula of correlations of the laser beam deflection angles which we have demonstrated in previous works. This computed power spectral density is compared to that measured from the effective position of the detector. A good agreement is observed between the two results.

  6. A Distributed Air Index Based on Maximum Boundary Rectangle over Grid-Cells for Wireless Non-Flat Spatial Data Broadcast

    Directory of Open Access Journals (Sweden)

    Seokjin Im

    2014-06-01

    Full Text Available In the pervasive computing environment using smart devices equipped with various sensors, a wireless data broadcasting system for spatial data items is a natural way to efficiently provide a location dependent information service, regardless of the number of clients. A non-flat wireless broadcast system can support the clients in accessing quickly their preferred data items by disseminating the preferred data items more frequently than regular data on the wireless channel. To efficiently support the processing of spatial window queries in a non-flat wireless data broadcasting system, we propose a distributed air index based on a maximum boundary rectangle (MaxBR over grid-cells (abbreviated DAIM, which uses MaxBRs for filtering out hot data items on the wireless channel. Unlike the existing index that repeats regular data items in close proximity to hot items at same frequency as hot data items in a broadcast cycle, DAIM makes it possible to repeat only hot data items in a cycle and reduces the length of the broadcast cycle. Consequently, DAIM helps the clients access the desired items quickly, improves the access time, and reduces energy consumption. In addition, a MaxBR helps the clients decide whether they have to access regular data items or not. Simulation studies show the proposed DAIM outperforms existing schemes with respect to the access time and energy consumption.

  7. Retrieval of structure functions of air temperature and refractive index from large eddy simulations of the atmospheric boundary layer

    Science.gov (United States)

    Wilson, Chris; van Eijk, Alexander M.; Fedorovich, Evgeni

    2013-09-01

    A methodology is presented to infer the refractive-index structure function parameter and the structure parameters for temperature and humidity from numerical simulations of the turbulent atmospheric convective boundary layer (CBL). The method employs spatial and temporal averaging of multiple realizations of the CBL flow field reproduced by a large-eddy simulation (LES) of the atmosphere. The Cn2 values yielded by LES-based approach agree fairly well with Cn2 values predicted by the Monin-Obukhov similarity theory. In this respect, the Cn2 retrieval from the LES data is promising for evaluating the vertical profile of Cn2 throughout the entire CBL. Under the considered CBL conditions and for the selected optical wavelength of 0.55 ?m the value of Cn2 was found to be dominated by the CT2 contribution in the first few hundred meters above the surface, whereas the CTq contribution became significant aloft.

  8. Air Pollution Quality Index (AQI and Density of PM1, PM2.5 and PM10 in the Air of Qom

    Directory of Open Access Journals (Sweden)

    Safdari M

    2011-06-01

    Full Text Available Background and Objectives: Air pollution has broad social, economical, political and technical aspects. one of the major issues in this regard is taking measures to prevent its increase. Since suspended particles are among the standard pollutants, the present study was carried out with the aim of measuring the amounts of these particles.Methods: In the present study, the suspended particles ( PM1, PM2.5 and PM10 were measured at two sites in Qom city. For each of them, 60 samples were selected with the Enviro Check during five consecutive months during summer (2 months and fall.Results: During sampling, PM10 in the period between October 22'th to November 22nd 2007 had the maximum amount with the mean of 117µg/m3 and in the period between September 22'th to October 22nd 2007 it had the minimum amount with the mean of 83µg/m3. PM2.5 in the period between November 22nd to December 22nd 2007 with the mean of 33µg/m3 had the maximum amount and in the period between July 22nd to October 22nd 2007 it had the minimum amount with the mean of 8µg/m3. Conclusion: Based on the findings of this study, the densities of suspended particles PM1, PM2.5 and PM10 were below the standard levels on most occasions. The amounts of AQI for them were normal and acceptable.

  9. A Hybrid Method to Improve Forecasting Accuracy - An Introduction of a Day of the Week Index for Air Cargo Weight Data

    Directory of Open Access Journals (Sweden)

    Tatsuhiro Kuroda

    2012-11-01

    Full Text Available Air cargo loading weight forecasting is an important factor for managers in the aviation industry because revenue is dependent on the amount of weight loaded. In this paper, we propose a new method to improve forecasting accuracy and confirm them by the numerical example. Focusing that the equation of exponential smoothing method(ESM is equivalent to (1,1 order ARMA model equation, a new method of estimation of smoothing constant in exponential smoothing method is proposed before by us which satisfies minimum variance of forecasting error. Generally, smoothing constant is selected arbitrarily. But in this paper, we utilize above stated theoretical solution. Firstly, we make estimation of ARMA model parameter and then estimate smoothing constants. Thus theoretical solution is derived in a simple way and it may be utilized in various fields. Combining the trend removing method with this method, we aim to improve forecasting accuracy. Furthermore, “a day of the week index” is newly introduced for the daily air cargo weight data and we have obtained good result. The effectiveness of this method should be examined in various cases.

  10. Air Pollution Quality Index (AQI and Density of PM1, PM2.5 and PM10 in the Air of Qom

    Directory of Open Access Journals (Sweden)

    M Azizifar

    2012-05-01

    Full Text Available

    Background and Objectives: Air pollution has broad social, economical, political and technical aspects. one of the major issues in this regard is taking measures to prevent its increase. Since suspended particles are among the standard pollutants, the present study was carried out with the aim of measuring the amounts of these particles.

     

    Methods: In the present study, the suspended particles ( PM1, PM2.5 and PM10 were measured at two sites in Qom city. For each of them, 60 samples were selected with the Enviro Check during five consecutive months during summer (2 months and fall.

     

    Results: During sampling, PM10 in the period between October 22'th to November 22nd 2007 had the maximum amount with the mean of 117µg/m3 and in the period between September 22'th to October 22nd 2007 it had the minimum amount with the mean of 83µg/m3. PM2.5 in the period between November 22nd to December 22nd 2007 with the mean of 33µg/m3 had the maximum amount and in the period  between July 22nd to October 22nd 2007 it had the minimum amount with the mean of 8µg/m3.

     

    Conclusion: Based on the findings of this study, the densities of suspended particles PM1, PM2.5 and PM10 were below the standard levels on most occasions. The amounts of AQI for them were normal and acceptable.

  11. Air pollution reduction with respect to the conversion of biomass into electricity and heat. Emission and cost indexes

    International Nuclear Information System (INIS)

    Although biomass conversion is considered to be a CO2-free method of producing electricity and heat other emissions have to be taken into account: SO2, NOx, HCl, HF, Hg, Cd, dusts, etc. The aim of the study on the title subject is to support the Dutch Ministry of Housing, Planning and Environment (VROM) in the determination of feasible emission standards for bioconversion installations. The Centre for Energy conservation and clean technology (CE) compiled information on the costs for flue gas purification for different degrees of purification. Because of the fact that the composition of flue gases strongly depends on the biomass flow and the applied conversion technique, both biomass flows and conversion techniques must be distinguished. The following biomass conversion techniques were studied: large-scale combustion of wood wastes and sludges, large-scale gasification of wood wastes, cocombustion of wood wastes and sludges, small-scale combustion of wood wastes and chicken manure, small-scale gasification of wood wastes, and fermentation of wastes from vegetables, fruits and gardens. For each combination it is determined what the emissions are in case of a minimal flue gas purification, what the emissions are and how much additional costs are involved in case the regulations in the BLA (decree on air pollution of waste incineration) are taken into account, and what the emissions are and how much additional costs are involved for a number of levels in between the two for a number of levels in between the two fore-mentioned cases. refs

  12. Scattering study at free air ionization chamber diaphragm; Estudo do espalhamento no diafragma da camara de ionizacao de ar livre

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Alexandre Lo Bianco dos

    2011-07-01

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are k{sub RQR-M1}=0,9946, k{sub RQR} {sub -M2}=0,9932, k{sub RQR-M3}=0,9978 and k{sub RQR-M4}=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  13. PTRAC file utilization for calculation of free-air ionization chamber correction factors by MCNPX

    International Nuclear Information System (INIS)

    A free-air ionization chamber is used as a standard of photon air-kerma. Several correction factors are applied to the air-kerma value. Correction factors for electron loss: k(loss) and for additional ionization current caused by photon scatter: k(sc), photon fluorescence: k(fl), photon transmission through diaphragm edge k(dtr), and photon scatter from the surface of the diaphragm aperture k(dsc) were determined by the MCNPX code utilizing information stored in Particle Track (PTRAC) output files. Individual steps of the procedure are described and the calculated values of the correction factors are presented. The values are in agreement with the correction factors published in the literature for similar free-air chambers and low-energy photons. (authors)

  14. Use of an index to reflect the aggregate burden of long-term exposure to criteria air pollutants in the United States.

    OpenAIRE

    Kyle, Amy D.; Woodruff, Tracey J.; Buffler, Patricia A.; Davis, Devra L.

    2002-01-01

    Air pollution control in the United States for five common pollutants--particulate matter, ground-level ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide--is based partly on the attainment of ambient air quality standards that represent a level of air pollution regarded as safe. Regulatory and health agencies often focus on whether standards for short periods are attained; the number of days that standards are exceeded is used to track progress. Efforts to explain air pollution to ...

  15. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

    International Nuclear Information System (INIS)

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,?) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends. (author)

  16. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil; Avaliacao de kerma de entrada na pele em exames radiologicos no Hospital de Clinicas do Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Lorena E.; Schelin, Hugo R.; Santos, Amanda C. dos; Bunick, Ana Paula; Paschuk, Sergei; Denyak, Valeriy [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Tilly Junior, Joao G. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Hospital de Clinicas; Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE/DEN), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-10-26

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  17. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography

    International Nuclear Information System (INIS)

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  18. Determination of mass attenuation coefficients, effective atomic numbers, effective electron numbers and kermas for Earth and Martian soils

    Energy Technology Data Exchange (ETDEWEB)

    Un, A., E-mail: ademun25@yahoo.com [Agr Latin-Small-Letter-Dotless-I Ibrahim Cecen University, Faculty of Arts and Sciences, Department of Physics, 04100 Agr Latin-Small-Letter-Dotless-I (Turkey); Sahin, Y. [Atatuerk University, Faculty of Sciences, Department of Physics, 25240 Erzurum (Turkey)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer The present work have been expected to be lead to extraterrestrial research. Black-Right-Pointing-Pointer Our work have thrown light on the radiation physics and the applications. Black-Right-Pointing-Pointer The data which are used to shielding application are not available in the literature. - Abstract: Total mass attenuation coefficients, effective atomic numbers, effective electron numbers and kerma values for Earth and Martian soils are calculated in the energy range from 1 keV to 100 GeV. The values of mass attenuation and absorption coefficients used in calculations are taken from the WinXCOM program and correct data base. Contributions of different scatterings on the total mass attenuation coefficients of the soils are presented. In addition, the obtained results for Martian soils are compared with the results for Earth soils. The similarities of Earth and Martian soils are also investigated.

  19. Study of effective atomic numbers and electron densities, kerma of alcohols, phantom and human organs, and tissues substitutes

    Directory of Open Access Journals (Sweden)

    Singh Vishwanath P.

    2013-01-01

    Full Text Available Effective atomic numbers (ZPIeff and electron densities of eighteen alcohols such as wood alcohol, CH3OH; grain alcohol, C2H5OH; rubbing alcohol, C3H7OH; butanol, C4H9OH; amyl alcohol, C5H11OH; cetyl alcohol, C16H33OH; ethylene glycol, C2H4(OH2; glycerin, C3H5(OH3; PVA, C2H4O; erythritol, C4H6(OH4; xylitol, C5H7(OH5; sorbitol, C6H8(OH6; volemitol, C7H9(OH7; allyl alcohol, C3H5OH; geraniol, C10H17OH; propargyl alcohol, C3H3OH; inositol, C6H6(OH6, and menthol, C10H19OH have been calculated in the photon energy region of 1 keV-100 GeV. The estimated values have been compared with experimental values wherever possible. The comparison of ZPIeff of the alcohols with water phantom and PMMA phantom indicate that the ethylene glycol, glycerin, and PVA are substitute for PMMA phantom and PVA is substitute of water phantom. ZPIeff of alcohols have also been compared with human organs and tissues. Ethylene glycol, glycerin and PVA, allyl alcohol, and wood alcohols are found tissue substitutes for most of human organs. Kerma which is the product of the energy fluence and mass energy-absorption coefficient, have been calculated in the energy region from 1 keV to 20 MeV for the alcohols. The results show the kerma is more or less independent of energy above 100 keV.

  20. Calculation of the backscattering in water and compared to the values in air; Calculo del factor de retrodispersion en agua y comparativa con los valores en aire

    Energy Technology Data Exchange (ETDEWEB)

    Minano Herrero, J. A.; Sarasa Rubio, A.; Roldan Arjona, J. M.

    2011-07-01

    The purpose of this paper is to calculate values of BSF in water and comparison with data on air 11SF found in the literature. For this simulations have been performed by the Monte Carlo method for calculating values ??kerma water in the presence of a manikin of this material and in the absence thereof. The simulations were performed for monoenergetic beams in order to facilitate the calculation of the BSF for any spectral distribution of those found in the field of radiology.

  1. The tree BVOC index

    International Nuclear Information System (INIS)

    Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes in BVOC emissions are calculated as the result of transitioning to a lower-emitting species mix in future planting. A simplified method for calculating the emissions reduction and a Tree BVOC index based on the calculated reduction is described. An example illustrates the use of the index as a tool for implementation and monitoring of a tree program designed to reduce BVOC emissions as a control measure being developed as part of the State Implementation Plan (SIP) for the Sacramento Federal Nonattainment Area. - Highlights: ? A Tree BVOC index based on reduced emissions from low emitting trees is described. ? An example illustrates use of the index as an implementation and monitoring tool. ? This index could be useful for including urban trees in air quality mitigation plans. - A tree BVOC index is presented that calculates reduced BVOC emissions from planting lower-emitting urban tree species that has potential application for SIP compliance.

  2. Development of improved free-air ionisation chamber as absolute dosimetry standard for low-energy X rays in INER

    International Nuclear Information System (INIS)

    The National Radiation Standard Laboratory of the Inst. of Nuclear Energy Research (INER) designed and constructed an improved Attix style free-air ionisation chamber (FAC) for low-energy X-ray measurements. Clinically, X rays in this energy range are used in mammography radiology. This chamber is also used to perform air-kerma measurements. The original Attix two-sectional design was redesigned by INER using the piston design. The correction factors were determined experimentally for volume estimation, ion recombination and air attenuation. The aperture transmission, wall transmission, electron loss and photon scatter correction factors were determined using Monte Carlo calculations. INER established the Bureau International des Poids et Mesures (BIPM) X-ray beam code and performed a comparison of secondary standard air-kerma calibration factors for 10-50 kV low- energy X rays to verify the experimental accuracy and measurement consistency of the improved chamber. The INER-NMIJ/National Inst. of Advanced Industrial Science and Technology (AIST) experimental results comparison using a transfer chamber yielded a difference <1.0% at the 95% confidence level in calibration factors. The overall uncertainty for the X-ray measurement in terms of air kerma was <0.6% at the 95% confidence level. These results indicated that the improved FAC is capable of serving as a primary standard as well as a trace standard in low-energy X-ray calibration services in Taiwan and even formiibration services in Taiwan and even forming a basis for the future mammography X-ray air-kerma primary standard. (authors)

  3. Calculation and evaluation of cross-sections and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B. [California Univ., Livermor, CA (United States). Lawrence Livermore National Lab.; Young, P.G.

    1997-03-01

    We present evaluations of the interaction of neutrons with energies between 20 and 100 MeV with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A {<=} 4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. (author). 52 refs.

  4. Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on 16O and 14N

    International Nuclear Information System (INIS)

    We present evaluations of the interaction of 20 to 100 MeV neutrons with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra, for light ejectiles with A?4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al.. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. The evaluated data libraries are available as electronic files

  5. Doses monitoring in radiology: calibration of air kerma-area product (P{sub KA}) meters; Monitoracao de doses em radiologia: a calibracao de medidores do produto kerma-area (P{sub KA})

    Energy Technology Data Exchange (ETDEWEB)

    Terini, Ricardo Andrade; Campelo, Maria Carolina de Santana; Almeida Junior, Jose Neres de, E-mail: rterini@pucsp.br [Pontificia Universidade Catolica de Sao Paulo (PUC-SP), SP (Brazil); Herdade, Silvio Bruni; Pereira, Marco Aurelio Guedes [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Instituto de Energia e Ambiente

    2013-11-15

    Materials and methods: different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm{sup 3} cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results: the lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion: the calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference. (author)

  6. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation.

    Science.gov (United States)

    Pignol, J P; Slabbert, J

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends. PMID:11233567

  7. Detection and estimation trends linked to air quality and mortality on French Riviera over the 1990-2005 period to develop a prediction model of an aggregate risk index

    Science.gov (United States)

    Sicard, P.; Mangin, A.; Hebel, P.; Lesne, O.; Malléa, P.

    2009-04-01

    There is a profound relation between human health and well being from the one side and air pollution levels from the other. Air quality in South of France and more specifically in Nice, is known to be bad, especially in summer. The main objectives are to establish correlations between air pollution, exposure of people and reactivity of these people to this aggression, to validate a risk index built from air quality and pollen data in the area of Nice and to construct a prediction model of this sanitary index. The spatial extent of the experiment will be mainly the territory of "Alpes Maritimes". All the tasks are performed in collaboration with the "Heath-Environment Network" of the "Centre Hospitalier Universitaire" of Nice. The development of an adequate tool for observation (health index and/or indices per pathology) to understand impacts of pollution levels in an area is of utmost importance. These indexes should take into account the possible adverse effects associated with the coexistence of all the pollutants and environmental parameters. This tool must be able to inform the citizens about the levels of pollution in an adequate and understandable way but also to be used by relevant authorities to take a series of predetermined measures to protect the health of the population. This paper describes the first step to construct a prediction model of this sanitary index with a confidence interval 99% (and 95%): detection and estimation trends observed in concentrations of pollutants, emissions and mortality over the 1990-2005 period in the "Alpes Maritimes" area. The non-parametric Mann-Kendall test has been developed for detecting and estimating monotonic trends in the time series and applied in our study at annual values of pollutants air concentrations. An important objective of many environmental monitoring programs is to detect changes or trends in pollution levels over time. Over the period 1990-2005, concerning the emissions of the main pollutants, we obtained significant decreasing trends. Between 1994 and 2005, from the SO2 concentrations, decreasing trends of 1.2 %.year-1 (urban stations) and of 5.4 %.year-1 (traffic stations) were calculated. Over the same period, we obtained a decreasing trend of 1.3 %.year-1 for the NO2 concentrations (urban stations) and of 3.1 %.year-1 for the traffic stations. In addition, a decreasing trend of 0.5 %.year-1 was calculated for the suburban stations over the 1998-2005 period. Globally, the concentration of the major pollutants showed a clear downward trend and those main reductions have reflected the reduction policy of the emissions over twenty years. By considering the ozone mean values in urban areas over the 1997-2005 period, an increasing of 3.0 %.year-1 was obtained with annual averages and 3.9 %.year-1 with median values. Over the 1990-2005 period, we obtained significant decreasing trends concerning the "ischemic heart diseases" (- 1.20 %.year-1) and "asthma" (- 4.03 %.year-1) categories. No significant sex-related difference was identified for these groups. An annual change rate of + 0.31 %.year-1 for the "airway diseases" and of + 2.50%.year-1 for the "unknown causes" were identified. For these categories, we noted a sex-related difference. In fact, we obtained for males a decreasing trend contrary to females.

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

    OpenAIRE

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

    2014-01-01

    The glacier melt conditions (i.e.: null surface temperature and positive energy budget) can be assessed by analyzing meteorological and energy data acquired by a supraglacial Automatic Weather Station (AWS). In the case this latter is not present the assessment of actual melting conditions and the evaluation of the melt amount is difficult and simple methods based on T-index (or degree days) models are generally applied. These models require the choice of a correct temperatu...

  9. Heat Index

    Science.gov (United States)

    ... Heat! Summer Weather Safety and Survival The Heat Index Your local weather experts at the National Weather ... hot weather "feels" to the body. The Heat Index is based on work by R.G. Steadman ...

  10. Power and polarization beam-splitters, mirrors, and integrated interferometers based on air-hole photonic crystals and lateral large index-contrast waveguides.

    Science.gov (United States)

    Pottier, Pierre; Mastroiacovo, Sara; De La Rue, Richard M

    2006-06-12

    Air hole 2D photonic crystals (PhC) and air slots have been used in association with semiconductor ridge waveguides to produce highly compact beam-splitters (less than 10 microm x10 microm) for power or polarization separators and mirrors. An efficiency of 99 % (in both 2D and 3D formulations) has been obtained for the power beam-splitter using finite-difference time-domain (FDTD) simulations - and around 95 % has been measured experimentally for structures realized in silicon-on-insulator (SOI) waveguides. In the polarization splitter, an extinction ratio as large as 11 dB was also reached experimentally. Examples of combinations of these elements in the form of interferometers are also presented. PMID:19516730

  11. A Hybrid Method to Improve Forecasting Accuracy - An Introduction of a Day of the Week Index for Air Cargo Weight Data

    OpenAIRE

    Tatsuhiro Kuroda; Keiko Nagata; Kazuhiro Takeyasu

    2012-01-01

    Air cargo loading weight forecasting is an important factor for managers in the aviation industry because revenue is dependent on the amount of weight loaded. In this paper, we propose a new method to improve forecasting accuracy and confirm them by the numerical example. Focusing that the equation of exponential smoothing method(ESM) is equivalent to (1,1) order ARMA model equation, a new method of estimation of smoothing constant in exponential smoothing method is proposed before by us whic...

  12. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography; Caracterizacao de uma camara de ionizacao de ar-livre em feixes diretos de raios X utilizados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Mateus Hilario de

    2014-08-01

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  13. Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on 12C

    International Nuclear Information System (INIS)

    A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on 12C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements where they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A?and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV

  14. Design and preliminary test of a free-air ionization chamber for low-energy X-ray

    International Nuclear Information System (INIS)

    A free-air ionization chamber in low-energy X-ray has been designed and manufactured at the National Institute of Metrology (NIM, China) according to the definition of air-kerma. The results of a preliminary test show that the leakage current of ionization chamber is around 2 x 10-15A, and the correction factor of ion recombination for the ionization chamber is also obtained. The free-air ionization chamber is suitable for the primary standard in low-energy X-rays. (authors)

  15. A QUANTITATIVE EVALUATION OF THE POLLUTANT STANDARDS INDEX

    Science.gov (United States)

    The U.S. Environmental Protection Agency has recommended a daily air pollution index for use by State and local air pollution control agencies--the Pollutant Standards Index (PSI). The new index makes use of segmented linear functions which convert measured concentrations of each...

  16. Evaluation of cross sections and calculation of kerma factors for neutrons up to 80 MeV on {sup 12}C

    Energy Technology Data Exchange (ETDEWEB)

    Harada, M.; Watanabe, Y. [Kyushu Univ., Fukuoka (Japan); Chiba, S.; Fukahori, T.

    1997-03-01

    We have evaluated the cross sections for neutrons with incident energies from 20 to 80 MeV on {sup 12}C for the JENDL high-energy file. The total cross sections were determined by a generalized least-squares method with available experimental data. The cross sections of elastic and inelastic scattering to the first 2{sup +} were evaluated with the theoretical calculations. The optical potentials necessary for these calculations were derived using a microscopic approach by Jeukenne-Lejeune-Mahaux. For the evaluation of double differential emission cross sections (DDXs), we have developed a code system SCINFUL/DDX in which total 35 reactions including the 3-body simultaneous breakup process (n+{sup 12}C {yields} n+{alpha}+{sup 8}Be) can be taken into consideration in terms of a Monte Carlo method, and have calculated the DDXs of all light-emissions (A{<=}4) and heavier reaction products. The results for protons, deuterons, and alphas showed overall good agreement with experimental data. The code is also applicable for calculations of total and partial kerma factors. Total kerma factors calculated for energies from 20 to 80 MeV were compared with the measurements and the other latest evaluations from the viewpoints of medical application and nuclear heating estimation. (author)

  17. Photon and neutron fluence-to-kerma conversion factors for ICRP-1975 reference man using improved elemental compositions for bone and marrow of the skeleton

    International Nuclear Information System (INIS)

    A twelve-element approximation of the total-body, soft-tissue and skeletal components of ICRP-1975 Reference Man is used to investigate particle fluence-to-kerma conversion factors for photons with energies between 1 keV and 20 MeV and neutrons with energies between 0.0253 eV and 20 MeV. Several recent ICRP revisions to the elemental composition of Reference Man, which have not been included in other kerma-factor calculations, are taken into account. This work suggests some additional revisions to the major-element content (i.e., H, C, N, and O) and to the mineral and trace-element content (i.e., Na, Mg, P, S, Cl, K, Ca, and Fe) of various total-body, soft-tissue, and skeletal components of Reference Man. The revisions to the bone and red marrow of the skeleton offer significant new refinements in red-bone-marrow dosimetry

  18. Immigration Index

    Science.gov (United States)

    Striving to become the "immigration resource directory on the net," the Immigration Index is a newly launched Website dedicated to news and information about immigration worldwide. Along with breaking headlines from a variety of news sources about immigration-related issues such as asylum, migration, trafficking and women, and much more, the site contains a fully annotated collection of links to immigration materials all around the World Wide Web. Only a month old, some of the categories in the Index's hierarchy still need some filling in. In time, however, the Immigration Index promises to become an invaluable resource for interested parties.

  19. Index Morganagus

    Science.gov (United States)

    Developed by Eric Lease Morgan, a Systems Librarian for the North Carolina State University Libraries, the eponymous Index Morganagus is a full-text index that collects, organizes, and disseminates articles from over 80 library-related electronic serials. Each electronic serial in the browseable list of indexed titles links to its corresponding Website. The search engine for the index supports Boolean operators and truncation, as well as phrase, compound, and case-sensitive searching. Advanced users have the option to control other query variables--such as number of results allowed or output format--through the manipulation of radio buttons. Extensive help is available online. Mr. Morgan has created a valuable resource for researchers, library students, librarians, and information professionals.

  20. Intelligent indexing

    International Nuclear Information System (INIS)

    In this paper we discuss the relevance of artificial intelligence to the automatic indexing of natural language text. We describe the use of domain-specific semantically-based thesauruses and address the problem of creating adequate knowledge bases for intelligent indexing systems. We also discuss the relevance of the Hilbert space ?2 to the compact representation of documents and to the definition of the similarity of natural language texts. (author). 17 refs., 2 figs

  1. Variacion temporal de índices de precipitaciones extremas en el centro de la provincia de Buenos Aires / Temporal variation of extreme precipitations indexes in the centre of Buenos Aires province

    Scientific Electronic Library Online (English)

    Mónica, Gelmi; Rafael, Seoane.

    2013-06-01

    Full Text Available El objetivo de esta investigación consiste en estudiar la evolución temporal de precipitaciones diarias para detectar la presencia de tendencias y la frecuencia de eventos extremos. Las series de precipitaciones observadas corresponden a cuatro estaciones meteorológicas ubicadas en el centro de la P [...] rovincia de Buenos Aires, Argentina. Los cambios en las precipitaciones extremas a nivel diario se evalúan con los índices propuestos por la World Meteorological Organization-Commission for Climatology (WMO-CCL) y el World Climate Research Programme (WCRP) - Climate Variability and Predictability. Para estudiar los posibles cambios en la relación período de retorno - precipitaciones máximas se aplicaron a las series dos funciones de densidad de probabilidades, la Generalizada de Valores Extremos y la Gamma de dos parámetros. Los resultados estimados con las dos funciones de densidad de probabilidades de la precipitación máxima, generalmente muestran un incremento de la precipitación asociado a la misma probabilidad de ocurrencia en el período 1971-1999 respecto a 1951-1970. Los eventos de precipitación que produjeron crecidas, ocurridos en Olavarría y Azul desde la década del 80 son una clara indicación del interés del estudio de este tema tanto por sus implicancias sociales asociadas con las inundaciones, como por la necesidad de actualizar las estimaciones de los parámetros de diseño de obras hidráulicas. Los valores de los índices estimados indican la existencia de una tendencia positiva en la precipitación en la mayoría de las estaciones meteorológicas y una mayor frecuencia de ocurrencia de valores extremos para el periodo 1971-1999 en relación al periodo 1951-1970. Abstract in english The objective of this research is to study the temporal evolution of daily precipitation in order to detect the presence of trends and to estimate the frequency of extreme events. The observed precipitation series correspond to four meteorological stations located in the center of the Province of Bu [...] enos Aires, Argentina. Changes in daily extreme precipitation were assessed through the indices proposed by the World Meteorological Organization-Commission for Climatology (WMO-CCL) and the World Climate Research Program (WCRP) -Climate Variability and Predictability. In order to analyze possible changes in the return period - maximum precipitation relationship, two probability density functions were applied to the series, the Generalized Extreme Values and the two parameters Gamma. The obtained results show, in general, a higher probability of occurrence of greater precipitations over the period 1971-1999 respect of period 1951-1970. The rainfall events that caused floods in Olavarría and Azul since the '80s clearly show the interest of studying this subject, not only because of its social implications associated to floods, but the demand of developing techniques to update the estimation of design parameters of hydraulic works. The estimated indices suggest a positive trend in the precipitation at most of the analyzed meteorological stations and a higher frequency of occurrence of extreme values over the period 1971-1999 compared to the period 1951-1970.

  2. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam.

    Science.gov (United States)

    Groetz, J-E; Ounoughi, N; Mavon, C; Belafrites, A; Fromm, M

    2014-08-01

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™ and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays. PMID:25173259

  3. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    International Nuclear Information System (INIS)

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays

  4. Louisiana ESI: INDEX (Index Polygons)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all the hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

  5. Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber

    International Nuclear Information System (INIS)

    Along the latest years, the LNMRI has been proceeding a continuous research work with a concentric cylinders type free air ionizing chamber (VICTOREEN, model 481), aiming to establish it as a new national standard, and, as a consequence, replace the worldwide accepted secondary standard, calibrated by PTB. Taking into account that the absolute determination of kerma in air with a free air ionizing chamber implies the acquirement of a number of correction factors. The main objective of the present work comprises the determination of the two factors, specifically, electronic loss (ke) and air attenuation (ka). The correction factors were obtained through mammography qualities reference spectrum, using Monte Carlo simulation method. The Penelope code was used in the simulation procedures. Simulations took place in two stages, the acquirement of specters related to the qualities of interest (mammography) with the x ray tube (Pantak, model HF160 e Panalytical, model XRF window), and the free-air ionization chamber. The data were compared to those related to the BIPM chamber, to electronic loss were not detected. The comparison between air attenuation factors was obtained data bellow 0.13%. (author)

  6. Jung Index

    Science.gov (United States)

    1999-01-01

    Compiled by Matthew Clapp of the University of Georgia, the Jung Index is a collection of more than 300 online resources about and related to the life and work of Carl Jung, the Swiss psychologist and psychiatrist who founded analytic psychology. Resources are indexed into ten major topic areas and include sections such as Research Resources, Jungian Psychology, and Psychoanalysis, among others. A What's New? section, a What's Cool? section, and the JungNet Newsletter keep frequent visitors up to date on the latest and greatest resources in analytic psychology. In addition, the site provides a glossary of Jungian terms, a gallery of Jungian images, and a moderated forum for Jungian discussion.

  7. GCUBE Indexing

    Directory of Open Access Journals (Sweden)

    M.Laxmaiah

    2013-07-01

    Full Text Available Spatial Online Analytical Processing System involves the non-categorical attribute information alsowhereas standard online analytical processing system deals with only categorical attributes. Providingspatial information to the data warehouse (DW; twomajor challenges faced are; 1.Defining andAggregation of Spatial or Continues values and 2.Representation, indexing, updating and efficient queryprocessing. In this paper, we present GCUBE (Geographical Cube storage and indexing procedure toaggregate the spatial information/Continuous values. We employed the proposed approach storing andindexing using synthetic and real data sets and evaluated its build, update and Query time. It is observedthat the proposed procedure offers significant performance advantage.

  8. 30 CFR 7.89 - Test to determine the particulate index.

    Science.gov (United States)

    2010-07-01

    ...surface. (9) The particulate index for the mass particulate shall...n PI—Particulate Index (cfm) (ii) When calculating...the intake air, % pa =saturation vapor pressure of the intake...Determination of particulate index for the mass particulate...

  9. Population Index

    Science.gov (United States)

    Two excellent bibliographic resources for population studies are the "Population Index" from the Office of Population Research at Princeton University, and "Population Organizations: Finder's Guide" from the Center for Demography and Ecology at the University of Wisconsin-Madison. "Population Index" is a quarterly publication that has been available since 1935. It "covers all fields of interest to demographers, including fertility, mortality, population size and growth, migration, nuptiality and the family, research methodology, projections and predictions, historical demography, and demographic and economic interrelations. Input is derived from original publications including monographs, journal articles, other serial publications, working papers, doctoral dissertations, machine-readable data files, and relevant acquisitions lists and bibliographies." About 3,500 citations are produced annually. Full text for the Index is available at the "Population Index" Web site for 1986-present (Vol. 52-present). Indexes can be searched by author, subject matter, geographical region, or publication year. There is now an experimental free text search capability for the 1994-present issues. "Population Organizations: Finder's Guide" is a no frills "practical tool for population professionals who need a single source for the quick location of organizations that publish and distribute or post population or family planning documents." It contains hundreds of citations, providing organization addresses, phone and FAX numbers, and Internet addresses when available. The Guide is updated every six months and is maintained by Ruth Sandor, Director of the Library of the Center for Demography and Ecology. Office of Population Research, Princeton University: http://opr.princeton.edu/ "Population Organizations: Finder's Guide": gopher://cde2.ssc.wisc.edu:70/00/addazlis gopher to: cde2.ssc.wisc.edu select: Population Organizations: Finder's Guide Center for Demography and Ecology, University of Wisconsin-Madison: http://www.ssc.wisc.edu/cde/

  10. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    International Nuclear Information System (INIS)

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of 125I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for 125I selectSeedTM brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range

  11. Spatial variability of air dry bulb temperature and black globe humidity index in a broiler house during the heating phase / Variabilidade espacial de variáveis ambientais em um galpão avícola durante a fase de aquecimento

    Scientific Electronic Library Online (English)

    Patrícia F., Ponciano; Tadayuki, Yanagi Junior; Gabriel A. E S., Ferraz; João D., Scalon; Leonardo, Schiassi.

    2013-06-01

    Full Text Available A temperatura de bulbo seco do ar (t bs) bem como o índice de temperatura do globo negro e umidade (ITGU) exercem grande influência no desenvolvimento de frangos de corte durante a fase de aquecimento. Sendo assim, o objetivo deste trabalho foi analisar a estrutura e a magnitude da variabilidade esp [...] acial da t bs e ITGU, utilizando ferramentas da geoestatística por meio de análise de semivariograma e, ainda, a produção de mapas de isolinhas por meio de interpolação por krigagem. O experimento foi conduzido na mesorregião oeste de Minas Gerais, na primavera de 2010, em um galpão comercial com sistema de aquecimento constituído de duas fornalhas de aquecimento indireto do ar, durante os primeiros 14 dias de vida das aves. Os dados foram registrados em intervalos de cinco minutos, no período das 8 às 10 horas. As variáveis foram avaliadas por semivariograma ajustado pelo método da máxima verossimilhança restrita (REML), testando-se os modelos esférico e exponencial. Os mapas de krigagem foram produzidos baseados no melhor método de ajuste do semivariograma. As técnicas da geoestatística possibilitaram caracterizar a variabilidade da t bs e ITGU, permitindo a observação da dependência espacial. Além disso, com a utilização da geoestatística e dos mapas de distribuição, pode-se identificar falhas no sistema de aquecimento, em regiões do galpão que poderiam vir a prejudicar o desenvolvimento dos pintinhos. Abstract in english The air dry-bulb temperature (t db),as well as the black globe humidity index (BGHI), exert great influence on the development of broiler chickens during their heating phase. Therefore, the aim of this study was to analyze the structure and the magnitude of the t db and BGHI spatial variability, usi [...] ng geostatistics tools such as semivariogram analysis and also producing kriging maps. The experiment was conducted in the west mesoregion of the states of Minas Gerais in 2010, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the firsts 14 days of the birds' life. The data were registered at intervals of five minutes in the period from 8 a.m. to 10 a.m. The variables were evaluated by variograms fitted by residual maximum likelihood (REML) testing the Spherical and Exponential models. Kriging maps were generated based on the best model used to fit the variogram. It was possible to characterize the variability of the t db and BGHI, which allowed observing the spatial dependence by using geostatistics techniques. In addition, the use of geostatistics and distribution maps made possible to identify problems in the heating system in regions inside the broiler house that may harm the development of chicks.

  12. Air Quality Guide for Ozone

    Science.gov (United States)

    ... En Español) School Flag Program Smoke Advisories Students Teachers UV Index Visibility Cameras Weathercasters What You Can Do Privacy and Security | Accessibility | Contact Us | AirNow on Facebook | Subscribe to RSS | Follow us on Twitter

  13. Air Pollution

    Science.gov (United States)

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

  14. ZZ DLC-14 AIR, Group Constant Library of Secondary Gamma Transport in Air for ANISN Calculation

    International Nuclear Information System (INIS)

    1 - Nature of physical problem solved: Format: ANISN, DOT, MORSE (FIDO format); Number of groups: 22 neutron / 18 gamma-ray; Nuclides: air; Origin: ENDF/B for neutron cross sections, DLC-4/HPIC for gamma-ray and DLC-12/POPLIB for secondary gamma-ray production. Weighting spectrum: 1/E for neutron cross sections. The basic idea behind the distribution of this ANISN input data is to allow potential users to repeat the ANISN calculations reported in ref. (1). It is felt that it will be more economical to repeat the calculations rather than to distribute the results of the Straker-Gritzner (1) calculations. However, the cross section part of the data can actually be used in DOT or MORSE or any transport code which will accept input cross section in the FIDO format. 2 - Method of solution: The sample input data for ANISN are for a P5, S16 calculation of the transport of neutrons and secondary gamma-rays from a 12.2 to 15 MeV point neutron source in an infinite air medium. The source is actually uniformly distributed in the first interval (500 cm radius) of a spherical medium of air with radius 3005 meters. The problem is set up for calculating various 'detector responses' by means of the 'activity' option available with ANISN. This is accomplished by providing a cross section table for a 'material' which has detector responses in certain table positions. Then the inclusion of appropriate input data for 22$ and 23$ arrays causes the group fluxes to be multiplied by the grou group fluxes to be multiplied by the group response function values to give the desired answer. The neutron detector responses calculated by this sample problem are Henderson tissue dose, Snyder-Neufeld dose, tissue kerma, and air kerma. The gamma-ray response functions calculated are Henderson tissue dose and air kerma. The neutron cross sections were first reduced from point data from ENDF/B to a 104 fine group structure with a modified version of CSP, assuming a 1/E weighting factor. The gamma-ray data were reduced from point data from DLC-4/HPIC to an 18 group structure using MUG. The POPOP-4 code was used to convert secondary gamma-ray production data from DLC-12/POPLIB to neutron-to-gamma-ray group transfer cross sections. The coupled set (104 neutron, 18 gamma-ray groups) was then collapsed to 22 neutron and 18 gamma-ray groups with ANISN, using as the weighting function the spectrum from a spatially uniform source of 14 MeV neutrons in an infinite air medium with a density of 1.11 mg/cc. The resulting data are coupled macroscopic multigroup, P5 expansion cross sections for air punched on cards and suitable for input to the ANISN code

  15. Determining Weight for Multicriteria Indexes

    Directory of Open Access Journals (Sweden)

    Abdul Aziz Jemain

    2004-06-01

    Full Text Available This paper discusses methods determining weight for each criterion used in the development of an index representing social indicators. Examples to show computing for weights are also given. Data for percent of household in all districts in the country, obtained from 1991 census, of that owned defined facilities such as car, radio, television, telephone, washing machine, and air-condition are used as example how such weights were computed

  16. Determining Weight for Multicriteria Indexes

    OpenAIRE

    Abdul Aziz Jemain

    2004-01-01

    This paper discusses methods determining weight for each criterion used in the development of an index representing social indicators. Examples to show computing for weights are also given. Data for percent of household in all districts in the country, obtained from 1991 census, of that owned defined facilities such as car, radio, television, telephone, washing machine, and air-condition are used as example how such weights were computed

  17. Photon and neutron fluence-to-kerma conversion factors for ICRP-1975 reference man using improved elemental compositions for bone and marrow of the skeleton

    International Nuclear Information System (INIS)

    Findings of a recent ORNL review, and of other reviews, which have been discussed at the Late Effects Workshop on Dosimetry of Atomic Bomb Survivors, 29th Annual Meeting of the Radiation Research Society, Minneapolis, Minnesota, 31 May 1981, and the Symposium on Reevaluations of Dosimetric Factors, Hiroshima and Nagasaki, US Department of Energy, Germantown, Maryland, 5 and 6 September 1981, have clearly established a need to revise the dosimetry for the A-bomb survivors. This effort will involve several divisions at ORNL, several other national laboratories, and several consulting firms. One of the main tasks of the Health and Safety Research Division at ORNL is to provide revised estimates of various organ-dose parameters related to a survivor's neutron and gamma-ray exposures. The objectives of the work summarized in this report were: (a) to better define the elemental composition of various skeletal components of ICRP-1975 Reference Man, and (b) to investigate photon and neutron fluence-to-kerma conversion factors for various total-body and organ-tissue components of ICRP-1975 Reference man as revised here. Scaled down mathematical descriptions of the volumes and shapes of the total body and internal organs of Reference Man will be used, of course, in the organ-dose calculations for A-bomb survivors

  18. Calculation of photon scattering and transmission correction factors for a free air ionization chamber at Nuclear Science and Technology Research Institute in Iran

    International Nuclear Information System (INIS)

    Highlights: ? Transmission and scattering correction factors are calculated by using MCNP 4C. ? Transmission correction factor (ktr) is determined to be 1 for 6 cm aperture radius. ? Determined ktr is 0.9999 for photon energies above 85 keV for 4 cm aperture radius. ? Obtained scattering correction factor for 125I is 0.9987, for 4 cm aperture radius. ? Calculated scattering correction factor for 103Pd is 0.9992, for the same aperture. - Abstract: In primary standard dosimetry laboratories, the air kerma strength of low energy brachytherapy sources 125I and 103Pd is measured by standard free air ionization chambers. At present, one of these free air ionization chambers is constructed in Radiation Application Research School, in Nuclear Science and Technology Research Institute in Iran. The transmission and scattering correction factors are needed for the absolute determination of air kerma strength. Transmission and scattering correction factors were calculated for a monoenergetic point isotropic source with energies from 5 keV to 100 keV for ionization chamber with 4 cm and 6 cm aperture radii by using the MCNP 4C code. The calculated scattering correction factors for 125I and 103Pd brachytherapy sources are 0.9987 and 0.9992, respectively and determined transmission correction is one for our free air ionization chamber of aperture radius 4 cm. cm.

  19. Air Abrasion

    Science.gov (United States)

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

  20. Refractive index of plant cell walls

    Science.gov (United States)

    Gausman, H. W.; Allen, W. A.; Escobar, D. E.

    1974-01-01

    Air was replaced with media of higher refractive indices by vacuum infiltration in leaves of cucumber, blackeye pea, tomato, and string bean plants, and reflectance of noninfiltrated and infiltrated leaves was spectrophotometrically measured. Infiltrated leaves reflected less light than noninfiltrated leaves over the 500-2500-nm wavelength interval because cell wall-air interfaces were partly eliminated. Minimal reflectance should occur when the average refractive index of plant cell walls was matched by the infiltrating fluid. Although refractive indices that resulted in minimal reflectance differed among the four plant genera, an average value of 1.425 approximates the refractive index of plant cell walls for the four plant genera.

  1. Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

    International Nuclear Information System (INIS)

    We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient (?) to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of ?/KAP by a factor of 1.3 and of ?/ESD by up to a factor of 2. While KAP is preferred to determine ?, the results show no strong preference of KAP over ESD in determining E.nce of KAP over ESD in determining E. The mean absorbed dose D-bar in the patient obtained by dividing ? (determined using KAP) by the patient's mass was found to be the most robust measure of E. (author)

  2. Glycemic Index and Diabetes

    Science.gov (United States)

    ... Size: A A A Listen En Español Glycemic Index and Diabetes The glycemic index, or GI, measures how a carbohydrate-containing food ... Carbohydrates Carbohydrate Counting Make Your Carbs Count Glycemic Index and Diabetes Sugar and Desserts Sugar Alcohols Low- ...

  3. Index Funds Online

    Science.gov (United States)

    Matthew Roberts recently released Index Funds Online in response to the lack of index investment fund information on the Internet. Site features include the market performance newsletter Indexing Quarterly, background and definitional information on major US Indexes such as the S&P 500, and a library of new and interesting financial Websites, articles, and book reviews. Links to current index performance figures are also provided as well as a simple site search system and index fund discussion board.

  4. Neutron and gamma transport in air by TRIPOLI-2 time dependent energy deposition and electron current calculation

    International Nuclear Information System (INIS)

    The electromagnetic field due to an air explosion is here studied: neutron and the gamma-rays, generated by neutronic reactions, deposit energy which ionizes atmosphere; recoil electrons are also created by gamma collisions. This data set allows to solve the Maxwell equations which manage the electromagnetic field. The TRIPOLI-2 code studies the coupled neutron-gamma transport in 3D- geometries by the Monte Carlo method. The code has been modified to calculate the photon energy deposited in matter and the recoil electron current created by Compton effect. The method is tested wiht a simple case; then neutron and gamma transport is studied in air kerma, deposited photon energy, electron current are calculated as functions of space and time and the contributions of the different neutronic reactions are separately evaluated. The calculations presented here are only part of studies about this subject. Developments will relate three dimensional calculations and the existence of several materials (ground, various air densities)

  5. Clean Air Markets - Quick Facts and Trends

    U.S. Environmental Protection Agency — The Quick Facts and Trends module is part of a suite of Clean Air Markets-related tools that are accessible at http://camddataandmaps.epa.gov/gdm/index.cfm. The...

  6. National Wildlife Federation 1974 EQ Index

    Science.gov (United States)

    National Wildlife, 1974

    1974-01-01

    The National Wildlife Federation's Fifth Environmental Quality (EQ) Index reports a continuing downward trend in the battle against environmental deterioration. All EQ indicators, except air, are lower than the previous year. Also discusses the political factors which tend to inhibit the progress of environmental and conservation efforts. (JR)

  7. Compressed Air

    Science.gov (United States)

    This website includes an animation which demonstrates a basic overview of compressed air for use in machines. Objective: Describe the different tools that can be used with compressed air. You can find the animation under the heading "Automation Technology."

  8. Air Pollution.

    Science.gov (United States)

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  9. Rapid doubling of Alzheimer’s amyloid-?40 and 42 levels in brains of mice exposed to a nickel nanoparticle model of air pollution [v1; ref status: indexed, http://f1000r.es/T5Rxeo

    Directory of Open Access Journals (Sweden)

    Soong Ho Kim

    2012-12-01

    Full Text Available Background: Over 20 genetic risk factors have been confirmed to associate with elevated risk for Alzheimer’s disease (AD, but the identification of environmental and/or acquired risk factors has been more elusive. At present, recognized acquired risks for AD include traumatic brain injury, hypercholesterolemia, obesity, hypertension, and type 2 diabetes. Methods: Based on reports associating various inhalants with AD pathology, we investigated the possibility that air pollution might contribute to AD risk by exposing wild-type mice to a standard air pollution modeling system employing nickel nanoparticle-enriched atmosphere for 3 hr. Results: Mice exposed to air pollution showed 72-129% increases in brain levels of both amyloid-? peptides A?40 and A?42, as well as A?42/40 (p <0.01. Conclusions: These effects on elevation of brain A? exceed those associated with trisomy 21, a known risk for early onset AD pathology, raising the possibility that clinical importance might be attached. Further work is required to establish the molecular and physiological basis for these phenomena. The rapid, dramatic effect, if verified, would suggest that inhalant exposures should be evaluated for their possible roles in contributing to the environmental risk for common forms of AD.

  10. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    SØrensen, Henrik Rokkjær; Jensen, Jesper Bevensee

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.

  11. Monitoring of Air Polution by Using Fuzzy Logic

    OpenAIRE

    Dr. Gopal Upadhyaya,; Mr. Nilesh Dashore

    2010-01-01

    The Air Quality Index is a simple and generalized way to describe the air quality in China, Hong Kong, Malaysia and now in India. Indian Air Quality Index (IND-AQI) is mainly a health related index with the descriptor words: “Good (0- 100)”, “Moderate (101-200 )”, “Poor (201-300)”, “Very Poor (301-400)”, “Severe (401-500)”. State Environment Protection Agency (SEPA ) is responsible for measuring the level of air pollution in China . In China the AQI is based on the level of 5 atmospheric poll...

  12. Index of Glossary Terms

    Science.gov (United States)

    ... of this website will be limited. Search Help? Index of Glossary Terms Share this page: Was this ... Tests Inside the Lab In the News Article Index Tests Conditions Screening Features News Glossary About This ...

  13. UV Index Widget

    U.S. Environmental Protection Agency — The UV Index Widget displays the ultraviolet (UV) Index providing a daily forecast of the expected risk of overexposure to the sun for a user-specified area of...

  14. Liberalizing air cargo services in APEC

    OpenAIRE

    Geloso Grosso, Massimo; Shepherd, Ben

    2009-01-01

    This study aims at assessing the link between a more liberal air cargo regime and increased bilateral merchandise trade in the Asia Pacific region, under the auspices of APEC. Using the gravity model and employing the Air Liberalisation Index (ALI) developed by the WTO Secretariat, this paper finds strong support for two hypotheses. First, more liberal air services policies are positively, significantly and robustly associated with higher bilateral trade in merchandise. The results also sh...

  15. The Europe 2020 Index

    Science.gov (United States)

    Pasimeni, Paolo

    2013-01-01

    This paper presents a new index to quantify, measure and monitor the progress towards the objectives of the Europe 2020 strategy. This index is based on a set of relevant, accepted, credible, easy to monitor and robust indicators presented by the European Commission at the time the strategy was launched. The internal analysis of the index shows…

  16. North Slope, Alaska ESI: INDEX (Index Polygons)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries used for the production of the hardcopy maps as part of the Environmental Sensitivity Index (ESI)...

  17. Stamping Forming Quality Index

    Directory of Open Access Journals (Sweden)

    Yanping Zheng

    2013-01-01

    Full Text Available The study proposes that stamping forming quality index should include defect quality index and thickness variation uniformity quality index and different types of stamping parts focus on different defect quality index .Moreover, the fracture and wrinkle quality index can be demonstrated by the distance between the major strain of the simulation unit and the critical curve of the fracture and wrinkle trend in FLD, while thickness variation uniformity quality index can be expressed by variance of sheet metal thinning rate. It takes the automobile back plate reinforcement as the example, select stamping quality index as optimization objectives and constraint conditions based on numerical simulation technology, then apply the technical means that contain with orthogonal test design, neural network and genetic algorithm to optimize the process variables. The result indicates that the method of this study is feasible and effective and has application value in engineering.

  18. Air Pollution

    Science.gov (United States)

    Integrated Teaching and Learning Program,

    Students are introduced to the concept of air quality by investigating the composition, properties, atmospheric layers and everyday importance of air. They explore the sources and effects of visible and invisible air pollution. By learning some fundamental meteorology concepts (air pressure, barometers, prediction, convection currents, temperature inversions), students learn the impact of weather on air pollution control and prevention. Looking at models and maps, they explore the consequences of pollutant transport via weather and water cycles. Students are introduced to acids, bases and pH, and the environmental problem of acid rain, including how engineers address this type of pollution. Using simple models, they study the greenhouse effect, the impact of increased greenhouse gases on the planet's protective ozone layer and the global warming theory. Students explore the causes and effects of the Earth's ozone holes through an interactive simulation. Students identify the types and sources of indoor air pollutants in their school and home, evaluating actions that can be taken to reduce and prevent poor indoor air quality. By building and observing a few simple models of pollutant recovery methods, students explore the modern industrial technologies designed by engineers to clean up and prevent air pollution.

  19. Synchrotron emission in air

    Science.gov (United States)

    Rafat, M. Z.; Melrose, D. B.

    2015-05-01

    A conventional astrophysical treatment of synchrotron emission is modified to include the refractive index of air, written as n = 1 + 1/(2? 02), with ?0 ? 1. The angular distribution of emission by an electron with Lorentz factor ? is broadened, from a range of |? - ?| ? 1/? in vacuo (? = emission angle, ? = pitch angle) to |? - ?| ? max{1/?, 1/?0} in air. The emission spectrum in air is almost unchanged from that in vacuo at sufficiently low frequencies and it is modified by extending to higher frequencies with increasing ?/?0 1. We interpret the enhanced high-frequency emission as Cerenkov-like, and attribute it to the formation of caustic surfaces that sweep across the observer; we use a geometric model based on Huygens construction to support this interpretation. The geometric model predicts that the so-called Cerenkov ring present at high frequencies may be circular, elliptical, or crescent shaped. In the astrophysical treatment of synchrotron emission, the dependence on azimuthal angle is lost in the expression for emissivity. A motivation for this investigation is the application to extensive air showers, and for this purpose the loss of azimuthal dependence is a limitation. We comment on methods to overcome this limitation. We show that when an observer can see emission from inside the Cerenkov cone, emission from outside the Cerenkov cone, on either side of it, arrives simultaneously; there are three emission times for a given observation time.

  20. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel [Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Cecilio, E-18012 Granada (Spain); Perez-Calatayud, Jose [Servicio de Radioterapia, Unidad de Radiofísica, Hospital Universitario y Politécnico La Fe, E-46026 Valencia (Spain); Simancas, Fernando; Lallena, Antonio M. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Gazdic-Santic, Maja [Department of Medical Physics and Radiation Safety, Clinical Centre of Sarajevo University, 71000 Sarajevo (Bosnia and Herzegovina)

    2013-12-15

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range.

  1. A Study on the Use of a Statistical Analysis Model to Monitor Air Pollution Status in an Air Quality Total Quantity Control District

    OpenAIRE

    Shu-Lung Kuo; Edward Ming-Yang Wu

    2013-01-01

    The air quality in Taiwan, at present, is determined by a pollution standard index (PSI) that is applied to areas of possible serious air pollution and Air Quality Total Quantity Control Districts (AQTQCD). Many studies, both in Taiwan and in other countries have examined the characteristics and levels of air pollution with PSI. This study uses air quality data collected from eight automatic air quality monitoring stations in an AQTQCD in central Taiwan and discusses the correlation between a...

  2. Eco-Index

    Science.gov (United States)

    Eco-Index, a project of the Rainforest Alliance, is "a searchable almanac of current and past conservation projects in Mesoamerica, with project descriptions, goals, achievements, lessons learned, and more." With current, well-presented features covering a range of biodiversity conservation issues, Eco-Index offers an excellent way for conservation researchers and practitioners to keep abreast of activity in their field. Users are encouraged to add their own project descriptions to the Eco-Index database. Available in English or Spanish.

  3. Addiction Severity Index (ASI)

    Department of Veterans Affairs — The Addiction Severity Index (ASI) records and stores information about Veterans with substance abuse problems. Substance abuse patients are administered a standard...

  4. Supplement: Commodity Index Report

    Commodity Futures Trading Commission — Shows index traders in selected agricultural markets. These traders are drawn from the noncommercial and commercial categories. The noncommercial category includes...

  5. Human Development Index Data

    Science.gov (United States)

    United Nations

    This data set traces the varying patterns of national progress in recent decades, documenting impressive long-term Human Development Index (HDI) gains even in most low-income countries. The data set also includes three innovative new measurements: the Inequality-adjusted Human Development Index (IHDI), the Gender Inequality Index (GII) and the Multidimensional Poverty Index (MPI). The data set is available in both CSV and SDMX file formats and contains more than 100 indicators that measure quality of life for all UN member states.

  6. Air filter

    International Nuclear Information System (INIS)

    An air filter consists of an upright cylinder of corrugated or pleated filter fabric, joined at its upper end to a tubular right-angled elbow. The open end of the elbow includes an internal lip seal, so the elbow can be slid onto a horizontal spigot in an air filter unit. The filter can be cleaned by subjecting the fabric to a reverse pressure pulse from a nozzle. The construction facilitates removal of the filter into a plastic bag secured round a frame behind a door, when the unit is used to filter radioactive dust from air. (author)

  7. A Ventilation Index for Tropical Cyclones

    OpenAIRE

    Tang, Brian; Emanuel, Kerry Andrew

    2012-01-01

    An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of low-entropy air into the center of the tropical cyclone. Based on a theoretical framework, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the nondimensional midlevel entropy deficit divided by the potential intensity. T...

  8. Air Pollution and Cardiovascular System

    Directory of Open Access Journals (Sweden)

    Ejder Kardesoglu

    2011-02-01

    Full Text Available Air pollution is one of the environmental problems that threaten the public health. The air is a gas mixture. Air pollution is defined as the existence in the amount of pollutants harmful to humans and other organisms in the atmosphere as a result of the natural or human activity thereby changing to the gas rates in the air. The negative effects of pollution-causing particles on the health are closely related to the chemical structure of particles, whether causing a fibrotic reaction, whether having an amorphous shape and the aerodynamic diameters of particles. The particles larger than 10 microns in aerodynamic diameter can not reach up to the alveoli, and can be removed by mucociliary system. If the particles are smaller than 10 microns, these particles can reach to the alveoli, and are closely associated with the cardiovascular mortality and morbidity. The concentration of these particles (PM10 is used as an indicator of pollution, and creates the basis for air quality index. Air pollution has several negative effects such as blood pressure changes, atherosclerosis, endothelial dysfunction, autonomic dysfunction, inflammation, oxidative stress etc. In this review, the effects of air pollution on the cardiovascular system will be examined, and the importance of this issue will be emphasized. [TAF Prev Med Bull 2011; 10(1.000: 97-106

  9. Consumer Price Index

    Science.gov (United States)

    According to the Consumer Price Index for March 2000, the Consumer Price Index for All Urban Consumers (CPI-U) rose 0.8 percent in March. This is a 3.7 percent increase since March 1999. After seasonal adjustments, the CPI-U rose 0.7 percent, after a 0.5 percent increase in February 2000.

  10. Dow's chemical exposure index guide

    International Nuclear Information System (INIS)

    A number of events in the 1970's and 1980's impacted the course of process safety. Incidents such as Flixborough, Seveso, Three-Mile Island, and Bhopal are well known throughout industry and are recognized as examples of major disasters. Even though events leading up to these disasters were completely different they had one common element between them: a substance was released from a manufacturing unit, became airborne and presented a hazard of such magnitude as to place the safety of both employees and the surrounding public in jeopardy. As a result, industry became increasingly concerned regarding potential loss, in human and economic terms, as plants and equipment grew in size. The Flixborough incident raised the level of concern for process safety, particularly in terms of the hazards presented by fire and explosion. Seveso and Three-Mile Island emphasized the need to consider far-field exposure. The Bhopal incident created an urgent need to recognize and understand the expected downwind impact of potential releases of acutely toxic substances to the air. In order to meet this need, the Dow Chemical Company, a recognized leader in the area of safety and loss prevention, presented a Chemical Exposure Index in 1986. AIChE has recently published an updated version entitled Dow's Chemical Exposure Index Guide. 7 refs., 5 figs

  11. INDEXING OF ONLINE SIGNATURES

    Directory of Open Access Journals (Sweden)

    NAGASUNDARA K.B., MANJUNATH S., GURU D.S.

    2011-09-01

    Full Text Available In this paper, a model for representation and indexing of online signatures for person identification is proposed. Insome applications, where the database is supposed to be very large, the identification process typically has an unacceptablylong response time. A solution to speed up the identification process is to design an indexing model prior to identificationwhich reduces the number of candidate hypotheses to be considered during matching by the identification algorithm. In thispaper, we study the suitability of Kd-tree indexing mechanism for person identification based on online signatures. Forrepresentation of online signatures, we considered a set of 100 global features of (MCYT online signature database onlinesignature and index by Kd-tree. Experimental results reveal that indexing prior to identification is faster than conventionalidentification method in terms of time for online signatures

  12. Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber; Determinacao da atenuacao do ar e perda eletronica para a camara de ionizacao de ar livre de cilindros concentricos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Hebert Pinto Silveira de

    2010-07-01

    Along the latest years, the LNMRI has been proceeding a continuous research work with a concentric cylinders type free air ionizing chamber (VICTOREEN, model 481), aiming to establish it as a new national standard, and, as a consequence, replace the worldwide accepted secondary standard, calibrated by PTB. Taking into account that the absolute determination of kerma in air with a free air ionizing chamber implies the acquirement of a number of correction factors. The main objective of the present work comprises the determination of the two factors, specifically, electronic loss (k{sub e}) and air attenuation (k{sub a}). The correction factors were obtained through mammography qualities reference spectrum, using Monte Carlo simulation method. The Penelope code was used in the simulation procedures. Simulations took place in two stages, the acquirement of specters related to the qualities of interest (mammography) with the x ray tube (Pantak, model HF160 e Panalytical, model XRF window), and the free-air ionization chamber. The data were compared to those related to the BIPM chamber, to electronic loss were not detected. The comparison between air attenuation factors was obtained data bellow 0.13%. (author)

  13. Structure and Implementation of Multiuser Collaborative in Duty Cycling Control of Central Air Conditioning

    OpenAIRE

    Chen, Cheng

    2014-01-01

    Proposed optimization model of duty cycling control in central air conditioning based on human comfort index. The human comfort index is incorporated into the process of duty cycling control in central air conditioning, and we found that the range of reducing air conditioning load is affected by temperature and humidity parameters. When ensure the premise of human comfort, there exists a maximum volume of reducing air conditioning load. The changing of indoor and outdoor temperature determine...

  14. Air surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Patton, G.W.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995).

  15. Hedonic House Price Index

    OpenAIRE

    Sa?terbrink, Filip

    2013-01-01

    Nasdaq OMX Valueguard-KTH Housing Index (HOX) is a hedonic price index that illustrates the price development of condominiums in Sweden, and that is obtained by using regression technique. Concerns have been raised regarding the influence of the monthly fee on the index. Low fee condominiums could be more popular because of the low monthly cost, high fee condominiums tend to sell for a lower price due to the high monthly cost. As the price of a condominium rises the importance of the monthly ...

  16. Introduction of a Cooling-Fan Efficiency Index

    DEFF Research Database (Denmark)

    Schiavon, S.; Melikov, Arsen Krikor

    2009-01-01

    In a warm environment, air movement with elevated velocity is a well-known cooling strategy. The local air movement is typically generated by cooling fans (e.g., ceiling fan, table fans, etc.). Appearance, power input, and price are the main parameters considered today when purchasing cooling fans, while cooling capacity and efficiency of energy use are unknown. To address this knowledge gap, this paper introduces the cooling-fan efficiency (CFE) index, defined as the ratio between the cooling effect (measured with a thermal manikin) generated by the device and its power consumption. The index was determined for a ceiling fan, a desk fan, standing fan, and a tower fan in a real office at three room air temperatures and at different fan speed levels. The results reveal that the index is sensitive enough to identify differences in the performance of the cooling devices. A standard method for testing fan cooling effect and an index for determining fan efficiency, such as the CFE index proposed in this study, need to be developed. The cooling fans generate a nonuniform velocity field around occupants, which cannot be described with a single air-velociry value. Therefore, it is not clear how to apply in practice the recommended elevated velocities in warm environments presented in the present standards. The standards need to be revised.

  17. Graded index porous optical fibers - dispersion management in terahertz range.

    Science.gov (United States)

    Ma, Tian; Markov, Andrey; Wang, Lili; Skorobogatiy, Maksim

    2015-03-23

    A graded index porous optical fiber incorporating an air-hole array featuring variable air-hole diameters and inter-hole separations is proposed, fabricated, and characterized in a view of the fiber potential applications in low-loss, low-dispersion terahertz guidance. The proposed fiber features simultaneously low modal and intermodal dispersions, as well as low loss in the terahertz spectral range. We experimentally demonstrate that graded index porous fibers exhibit smaller pulse distortion, larger bandwidth, and higher excitation efficiency when compared to fibers with uniform porosity. PMID:25837124

  18. Air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Papetti, R.A.; Gilmore, F.R.

    1971-01-01

    Air pollution is an old problem to large-town dwellers, but a new and urgent one to people in many other parts of the world. This article discusses its sources, distribution, harmful effects, and mathematical modelling. As the pace of industrialization increases, the relatively simple and inexpensive measures that reduce only part of the pollutant emissions become inadequate, and much more costly changes must be made. In such circumstances, much expense and inconvenience may be saved by using mathematical models of pollutant transport, photochemical reaction, and dispersion to determine the best way to maintain the desired air quality throughout a populated region.

  19. A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy

    Directory of Open Access Journals (Sweden)

    Arshed Waheed

    2010-01-01

    Full Text Available An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained within a range of 0% to ±1.7% for the PTW UNIDOS dosimetry system. This means that although the recommended method is in-water calibration, under exceptional circumstances, in-air calibration may be used as well.

  20. Neural computing thermal comfort index for HVAC systems

    International Nuclear Information System (INIS)

    The primary purpose of a heating, ventilating and air conditioning (HVAC) system within a building is to make occupants comfortable. Without real time determination of human thermal comfort, it is not feasible for the HVAC system to yield controlled conditions of the air for human comfort all the time. This paper presents a practical approach to determine human thermal comfort quantitatively via neural computing. The neural network model allows real time determination of the thermal comfort index, where it is not practical to compute the conventional predicted mean vote (PMV) index itself in real time. The feed forward neural network model is proposed as an explicit function of the relation of the PMV index to accessible variables, i.e. the air temperature, wet bulb temperature, globe temperature, air velocity, clothing insulation and human activity. An experiment in an air conditioned office room was done to demonstrate the effectiveness of the proposed methodology. The results show good agreement between the thermal comfort index calculated from the neural network model in real time and those calculated from the conventional PMV model

  1. National Death Index

    U.S. Department of Health & Human Services — The National Death Index (NDI) is a centralized database of death record information on file in state vital statistics offices. Working with these state offices,...

  2. The Index of Refraction

    Science.gov (United States)

    WGBH Educational Foundation

    2011-10-25

    In this media-rich lesson plan, students explore the refraction of light at the boundary between materials: they learn about the refractive indices of various materials and measure the index of refraction of plastic or gelatin.

  3. Vegetation Drought Response Index

    U.S. Geological Survey, Department of the Interior — VegDRI, short for Vegetation Drought Response Index, is a drought-monitoring tool developed by scientists at EROS in collaboration with the National Drought...

  4. Regional Snowfall Index (RSI)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Climatic Data Center is now producing the Regional Snowfall Index (RSI) for significant snowstorms that impact the eastern two thirds of the U.S....

  5. CAD Centre - Index Searcher

    Science.gov (United States)

    A searchable index of the CAD Centre, a postgraduate teaching and research unit in design manufacture and engineering management, with research focused on design methods and computer support of the design process for engineering applications.

  6. Indexing Nearest Neighbor Queries

    OpenAIRE

    Truong, Thanh

    2010-01-01

    In database technology, one very well known problem is K nearest neighbor (KNN). However, the cost of finding a solution of the KNN problem may be expensive with the increase of database size. In order to achieve efficient data mining of large amounts of data, it is important to index high dimensional data to support KNN search. Xtree, an index structure for high dimensional data, was investigated and then integrated into Amos II, an extensible functional Database Management System (DBMS). Th...

  7. Calculating a Biodiversity Index

    Science.gov (United States)

    In this Biodiversity Counts activity, students learn how scientists calculate a biodiversity index using a page from the phone book as their data source. The printable five-page PDF handout includes a series of inquiry-based questions to get students thinking about what they already know about biodiversity and how living and non-living things are connected, step-by-step directions for calculating a biodiversity index, and a worksheet that includes brainstorming questions and areas for recording answers.

  8. Enabling Mobile Air Quality App Development with an AirNow API

    Science.gov (United States)

    Dye, T.; White, J. E.; Ludewig, S. A.; Dickerson, P.; Healy, A. N.; West, J. W.; Prince, L. A.

    2013-12-01

    The U.S. Environmental Protection Agency's (EPA) AirNow program works with over 130 participating state, local, and federal air quality agencies to obtain, quality control, and store real-time air quality observations and forecasts. From these data, the AirNow system generates thousands of maps and products each hour. Each day, information from AirNow is published online and in other media to assist the public in making health-based decisions related to air quality. However, an increasing number of people use mobile devices as their primary tool for obtaining information, and AirNow has responded to this trend by publishing an easy-to-use Web API that is useful for mobile app developers. This presentation will describe the various features of the AirNow application programming interface (API), including Representational State Transfer (REST)-type web services, file outputs, and RSS feeds. In addition, a web portal for the AirNow API will be shown, including documentation on use of the system, a query tool for configuring and running web services, and general information about the air quality data and forecasts available. Data published via the AirNow API includes corresponding Air Quality Index (AQI) levels for each pollutant. We will highlight examples of mobile apps that are using the AirNow API to provide location-based, real-time air quality information. Examples will include mobile apps developed for Minnesota ('Minnesota Air') and Washington, D.C. ('Clean Air Partners Air Quality'), and an app developed by EPA ('EPA AirNow').

  9. Index of Refraction

    Science.gov (United States)

    Refraction is an important behavior of light that can be used to explain the operation of lenses, prisms, and optical fiber, as well as natural phenomena such as rainbows and mirages. The index of refraction, or refractive index, is defined as the ratio of the speed of light in a vacuum to the speed of light in a material. The index of refraction is an important property of optical materials and one that can be easily measured in the laboratory.This lesson begins with a video that introduces the concept of refraction. Students learn firsthand how when a wave of light travels from one medium to another, the change in the wave's speed leads to a change in its wavelength and the bending of the wave. Next, students investigate index of refraction through an interactive media asset, research, and a class discussion. Following a video about the index of refraction and Snell's law, students work in groups to conduct their own laboratory experiment to measure the index of refraction of gelatin (or plastic).Note: This is the first of two optics lesson plans. You may want to follow this lesson with the Fiber Optics Lesson Plan.

  10. 2005 Environmental Sustainability Index (ESI)

    National Aeronautics and Space Administration — The 2005 Environmental Sustainability Index (ESI) is a measure of overall progress towards environmental sustainability, developed for 146 countries. The index...

  11. Influence of local air velocity from air conditioner evaluated by salivary and skin biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Masaki; Takahashi, Takayuki; Yoshino, Yuichiro; Sasaki, Makoto [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Nishimiya, Hajime [Asahi Kasei Homes Corporation, R and D Laboratories, 2-1 Samejima, Fuji, Shizuoka 416-8501 (Japan)

    2010-11-15

    The purpose of this paper is to reveal both the psychosomatic and the physical effects of local air velocity from an air conditioner using biomarkers which can be collected noninvasively. Salivary {alpha}-amylase activity (SAA) and salivary cortisol were used as the indexes of psychosomatic effects. The total protein (TP) collected from stratum corneum was used as an index of the physical condition of dry skin. A continuous experiment over a 5 days period in summer was conducted using 8 healthy young male adults for 2-types of airflow conditioners, a whole ceiling-type air conditioner (without local air velocity) and a normal-type air conditioner (with local air velocity). The subjects felt cool, windy, dry and uncomfortable when under the normal-type air conditioner as determined in a subjective evaluation. The SAA under the normal-type air conditioner fluctuated more widely than with the whole ceiling-type air conditioner. The level of salivary cortisol decreased more in a day under the normal-type air conditioner than with the whole ceiling-type air conditioner. These results showed that reducing local air velocity may provide more healthy psychosomatic conditions over the long-term. Moreover, the TP of a drying-exposed skin area showed a significant change during this experiment whereas the TP of drying-protected area was relatively unchanged. It was indicated that one week's exposure to local air velocity conditions possibly influences the drying of facial skin. Thus, air movement at low velocity can be provides more comfortable conditions not only psychosomatically but also physically. (author)

  12. Inhalation dose due to presence of 131I in air above septic tank system of an endocrinology hospital

    International Nuclear Information System (INIS)

    We present here measurements of the 131I concentration for both: Gaseous and aerosol fraction of 131I in the air above the septic tank containing wastes from medical application of this isotope. Aerosols were collected using air filters, whereas gaseous forms of iodine were trapped in KI impregnated charcoal double layer cartridge. Besides an active method (pumping of the air through system of filters) an attempt for using a passive method (charcoal traps) for monitoring of radio-iodine is described. For better characterisation of a site the external kerma was determined by means of G - M and TLD techniques as well as the activity kept in the septic tank was measured by gamma spectrometry. Results show that the activity of the aerosol fraction can be neglected compared to that of the gaseous fraction. He measured activity of air is low, on the level of 1 Bq m-3, even during simulated failure of the ventilation system. Estimated inhalation dose for the serviceman of septic tanks is low (?10%) compared with external dose obtained by such person due to gamma radiation from the tank (on the level ?500 nSv h-1). Therefore, the concept of passive monitoring of the iodine in air was abandoned. Also estimated is the efficiency of 131I reduction by a charcoal filter of the ventilation system and 131I input to the environment by the ventilation chimney. (authors)

  13. Air pollution.

    Science.gov (United States)

    Le, Nhu D; Sun, Li; Zidek, James V

    2010-01-01

    Toxic air pollutants are continuously released into the air supply. Various pollutants come from chemical facilities and small businesses, such as automobile service stations and dry cleaning establishments. Others, such as nitrogen oxides, carbon monoxide and other volatile organic chemicals, arise primarily from the incomplete combustion of fossil fuels (coal and petroleum) and are emitted from sources that include car exhausts, home heating and industrial power plants. Pollutants in the atmosphere also result from photochemical transformations; for example, ozone is formed when molecular oxygen or nitrogen interacts with ultraviolet radiation. An association between air pollution exposure and lung cancer has been observed in several studies. The evidence for other cancers is far less conclusive. Estimates of the population attributable risk of cancer has varied substantially over the last 40 years, reflecting the limitations of studies; these include insufficient information on confounders, difficulties in characterizing associations due to a likely lengthy latency interval, and exposure misclassification. Although earlier estimates were less than one percent, recent cohort studies that have taken into account some confounding factors, such as smoking and education amongst others, suggest that approximately 3.6% of lung cancer in the European Union could be due to air pollution exposure, particularly to sulphate and fine particulates. A separate cohort study estimated 5-7% of lung cancers in European never smokers and ex-smokers could be due to air pollution exposure. Therefore, while cigarette smoking remains the predominant risk factor, the proportion of lung cancers attributable to air pollution may be higher than previously thought. Overall, major weaknesses in all air-pollution-and-cancer studies to date have been inadequate characterization of long-term air pollution exposure and imprecise or no measurements of covariates. It has only been in the last decade that measurements to PM2.5 become more widely available. A key weakness of many studies is using fixed-site monitoring data and assuming everyone in a region had the same exposure. This ignores spatial variability, and does not take into account how individuals' exposures differ with pollution sources inside, outside, both at work, home and elsewhere. More recent efforts to model indicators of vehicular traffic, and residential distances to major roads and highway can allow for some of this spatial variability to be better controlled for. However, this still does not take into account differences in activity patterns. If the effect is small, these biases will compromise the ability to detect an association. In most situations, the resulting estimates tend to be biased toward the null (i.e., no effect). For misclassification of exposure the inability to adequately control for confounding variables may cause bias in either direction. Recent improvements in statistical methodology use measurements at fixed sites combined with residential histories to estimate individuals' cumulative exposures. They also recognize measurement errors associated with covariates in the analysis to improve estimates of effects. Other challenges include the fact that measurements of exposure and confounders can change over time and long term data are needed due to the anticipated latency interval between harmful exposures and development of cancer. PMID:21199603

  14. The Quilt Index

    Science.gov (United States)

    With the goal of creating a single, comprehensive index to American quilts, the Quilt Index builds on the work of 4 state quilt documentation and digitization projects: the Michigan Quilt Project, Kentucky Quilt Project, Illinois Quilt Research Project, and Quilts of Tennessee (more information about these projects is at the site). Currently almost 900 quilt images and pieces of information are searchable in the Quilt Index. The project has established standards for data elements to be collected, and forms to facilitate the addition of quilt documentation from other states. Quilts dating from 1800 to 1999 can be searched by pattern name, quilter's name, location made, date, and collection or documentation project. Searches by pattern name (baby blocks, ocean waves, wedding ring) are possible, but the interface is quite picky about singular and plural. Several ways to browse are also available, such as by collection, period, and style/technique, or choose "view the entire index" to display 887 quilts and records. The Quilt Index is hosted by MATRIX, the humanities technology center at Michigan State University that also hosts H-Net, Humanities and Social Sciences OnLine.

  15. Air Cannon

    Science.gov (United States)

    Twin Cities Public Television, Inc.

    2005-01-01

    In this activity (page 1 of PDF), learners will construct an air cannon by cutting a hole in the bottom of a bucket and stretching a garbage bag over the other end. Then, they aim the cannon at a paper target and try to knock it over by giving the plastic bag a good whack. Learners also experiment with hole size to make the cannon more effective. Relates to the linked video, DragonflyTV: Forecasting.

  16. Air pollution

    International Nuclear Information System (INIS)

    Australian cites experience a number of current and emerging air pollution problems. Concentrations of traditional primary pollutants such as CO, lead and dust have fallen in recent years as a consequence of air pollutant control measures, and the widespread introduction of lead-free petrol. However, recommended guidelines for ozone, the principal component of photochemical smog, are regularly exceeded in major capital cities in the summer months. In addition, it is predicted that extensive urban expansion will lead to much greater dependence on the motor vehicle as the primary means of transportation. Effects of air pollution are felt at a variety of scales. Traditionally, concerns about gaseous and particulate emissions from industrial and vehicular sources were focused on local impacts due to exposure to toxic species such as CO and lead. As noted above, concentrations of these pollutants have been reduced by a variety of control measures. Pollutants which have effects at a regional scale, such as photochemically-produced ozone, and acidic gases and particles have proved more difficult to reduce. In general, these pollutants arc not the result of direct emissions to atmosphere, but result from complex secondary processes driven by photochemical reactions of species such as NO2 and aldehydes. In addition, global effects of gaseous and particulate emissions to the atmosphere have received significant recent attention, concentrations of atmospheric CO2on, concentrations of atmospheric CO2 with predicted impacts on global climate, and ozone depletion due to anthropogenic emissions of chlorine-containing chemicals are the two major examples. Combustion processes from petrol- and diesel-fuelled vehicles, make major contributions to air pollution, and the magnitude of this contribution is discussed in this article

  17. ResearchIndex

    Science.gov (United States)

    Sponsored by the NEC Research Institute, ResearchIndex was created to improve the dissemination, functionality, usability, and efficiency of online scientific literature by demonstrating and providing "algorithms, techniques, and software that can be used in other digital libraries." The current demonstration database indexes over 150,000 computer science articles containing over 2 million citations. Searchable by keyword only, database returns feature several options. Users can review a list of citations to a given paper with links to the full text articles (Postscript or .pdf format), view related articles, and sign up to have new citations for selected articles emailed to them. In the future, users should also be able to review a dynamically created and continuously updated bibliography. Additional resources at the site include a collection of papers about citation indexing, digital libraries, Web analysis, and neural networks. Users may also submit papers to the database and subscribe to be notified when additional databases become available at the site.

  18. Internet Corruption Perception Index

    Science.gov (United States)

    The Internet Corruption Perception Index is provided by Transparency International and Goettingen University, Germany. The goal of the site to "rank countries by the extent of corruption in public administration." The ranking can then be used to help assess country risks. The Internet Corruption Perception Index is published annually and is based on "surveys undertaken by Gallup International, the World Competitiveness Yearbook, assessments by Political & Economic Risk Consultancy in Hong Kong, DRI/McGraw Hill Global Risk Service, Political Risk Services in Syracuse, USA, and data gathered from internet sources directly." The index for 1997 covers 52 countries, including both developed and developing countries. Recently added to the site is the report on the bribery propensity of leading exporting nations; this section investigates the "propensity to pay bribes for the acquisition of contracts in international trade." At the site, visitors can provide their own input on a country's bribery propensity.

  19. Sustainability index for Taipei

    International Nuclear Information System (INIS)

    Sustainability indicators are an effective means of determining whether a city is moving towards sustainable development (SD). After considering the characteristics of Taipei, Taiwan, discussions with experts, scholars and government departments and an exhaustive literature review, this study selected 51 sustainability indicators corresponding to the socio-economic characteristic of Taipei City. Such indicators should be regarded as a basis for assessing SD in Taipei City. The 51 indicators are classified into economic, social, environmental and institutional dimensions. Furthermore, statistical data is adopted to identify the trend of SD from 1994 to 2004. Moreover, the sustainability index is calculated for the four dimensions and for Taipei as a whole. Analysis results demonstrate that social and environmental indicators are moving towards SD, while economic and institutional dimensions are performing relatively poorly. However, since 2002, the economic sustainability index has gradually moved towards SD. Overall, the Taipei sustainability index indicates a gradual trend towards sustainable development during the past 11 years

  20. City Noise-Air : an environmental quality index for cities

    OpenAIRE

    Silva, Lígia Torres; Mendes, José F. G.

    2012-01-01

    Global population growth has led to an increase of the number of people living in urban areas. As a consequence, stresses on space, ecosystems, infrastructures, facilities and personal lifestyles have been enhanced. Problems related to the quality of life in cities are increasingly relevant, especially with regard to environmental issues. Domestic and industrial sources and, primarily, motorised traffic are responsible for pollutant emissions and noise that decisively affect life ...

  1. Air refractive index measurement using low-coherence interferometry.

    Czech Academy of Sciences Publication Activity Database

    Pikálek, Tomáš; Buchta, Zden?k

    2015-01-01

    Ro?. 54, ?. 16 (2015), s. 5024-5020. ISSN 1559-128X R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212; GA ?R GB14-36681G Institutional support: RVO:68081731 Keywords : updated edlen equantion * frequency combs * laser * refractometry Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.784, year: 2014

  2. Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación / The spatial distribution of population exposure to outdoor air pollution in Valencia (Spain) and its association with a privation index

    Scientific Electronic Library Online (English)

    Marisa, Estarlich; Carmen, Iñiguez; Ana, Esplugues; Enrique, Mantilla; Òscar, Zurriaga; Andreu, Nolasco; Ferran, Ballester.

    2013-04-01

    Full Text Available Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 p [...] untos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asignaron niveles de contaminación para cada SC. Se analizó la relación entre los niveles de NO2, un índice de privación con cinco categorías y la edad (>65 años). Resultados: El modelo LUR resultó el método más preciso. Más del 99% de la población superó los niveles de seguridad propuestos por la Organización Mundial de la Salud. Se encontró una relación inversa entre los niveles de NO2 y el índice de privación (? = -2,01?g/m³ en el quintil de mayor privación respecto al de menor, IC95%: -3,07 a -0,95), y una relación directa con la edad (? = 0,12?g/m³ por incremento en unidad porcentual de población >65 años, IC95%: 0,08 a 0,16). Conclusiones: El método permitió obtener mapas de contaminación y describir la relación entre niveles de NO2 y características sociodemográficas. Abstract in english Objective: To evaluate spatial variation in exposure to nitrogen dioxide (NO2) air pollution in the city of Valencia, Spain, and its association with socioeconomic deprivation and age. Methods: Census tract population data were obtained from the National Statistics Institute of Spain. Outdoor NO2 wa [...] s monitored in 100 sites in the study area, through the use of passive samplers, in three campaigns between 2002 and April 2004. Land use regression (LUR) was used to obtain a map of NO2 levels. The LUR predictions were compared with the NO2 level obtained by: a) the nearest sampler of the monitoring network, b) the nearest passive sampler, c) the mean distance-weighted levels of the samplers in the neighborhood, and d) the NO2 level obtained by using Kriging. For each census tract, the NO2 levels were obtained. The association of NO2 air pollution exposure with population age (>65 years) and the 5-category deprivation index was analyzed. Results: The LUR models showed less error than the other prediction methods. The safety levels proposed by the World Health Organization were exceeded in more than 99% of the population. An inverse relationship was found between NO2 levels and the deprivation index (? = -2.01?g/m³ in the most deprived quintile compared with lower deprivation, 95%CI: -3.07; -0.95) and a direct relationship was found with age (? = 0.12?g/m³ per unit increase in percentage of the population > 65 years, 95%CI: 0.08; 0.16). Conclusions: The method allowed pollution maps to be obtained and the association between NO2 levels and sociodemographic characteristics to be described.

  3. Fiber optic refractive index monitor

    Science.gov (United States)

    Weiss, Jonathan David (Albuquerque, NM)

    2002-01-01

    A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

  4. An Index of Factorial Simplicity

    Science.gov (United States)

    Kaiser, Henry F.

    1974-01-01

    An index of factorial simplicity, employing a quartimax transformational criteria, is developed. This index is both for each row separately and for a factor pattern matrix as a whole. The index varies between zero and one. The problem of calibrating the index is discussed. (Author/RC)

  5. Student Derived KP Index

    Science.gov (United States)

    This is an activity about the Kp index, a quantification of fluctuations in the Earth's magnetic field due to the relative strength of a magnetic storm. Learners will take a reading from a magnetometer site and make a Kp index estimate to predict whether or not an aurora display will occur near that site. This resource is designed to support student analysis of THEMIS (Time History of Events and Macroscale Interactions during Substorms) Magnetometer line-plot data. This activity requires the use of a computer with Internet access. This is activity 18 in Exploring Magnetism: Earth’s Magnetic Personality.

  6. GeoIndex

    Science.gov (United States)

    The GeoIndex Search Engine, which is continually updated, contains some new features making a regular reviewing of the site worthwhile. GeoIndex is "a powerful Search Engine developed, owned and maintained by Datasurge Company to specifically fill a need for the Geo-Environmental professional" by covering geotechnical, environmental, hydrogeology, geology, mining, and petroleum topics. The highlights of the site include the clear and descriptive search results, and the well-designed and browsable "nested" categories including companies, associations, education, and government Web sites. [JAB

  7. Fourth Indexing Course

    Directory of Open Access Journals (Sweden)

    Director DESIDOC

    1982-04-01

    Full Text Available The fourth training course in 'Indexing' was organised by DESIDOC at Metcalfe House, Delhi from 24 Feb to 6 Mar 1982. The course was intended for information personnel of DRDO Labs/Estts located in the north zone. The curriculum covered various aspects of indexing techniques and systems including computer processing. Besides the lectures and practical assignments, audiovisual demonstration on NTIS services was also screened. Visits to DRDO Computer Centre to familiarise the participants with the working of the computer, and INSDOC/National Science Library were also arranged.

  8. AirData

    U.S. Environmental Protection Agency — The AirData site provides access to yearly summaries of United States air pollution data, taken from EPA's air pollution databases. AirData has information about...

  9. Determining the Thickness and Refractive Index of a Mirror

    Science.gov (United States)

    Uysal, Ahmet

    2010-01-01

    When a laser beam reflects from a back surface glass mirror and falls on a screen, a pattern of discrete bright spots is created by partial reflection and refraction of the light at the air-glass interface and reflection at the mirror surface (Fig. 1). This paper explains how this phenomenon can be used to determine the refractive index and the…

  10. 17th DOE nuclear air cleaning conference: proceedings. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    First, M.W. (ed.)

    1983-02-01

    Volume 2 contains papers presented at the following sessions: adsorption; noble gas treatment; personnel education and training; filtration and filter testing; measurement and instrumentation; air cleaning equipment response to accident related stress; containment venting air cleaning; and an open end session. Twenty-eight papers were indexed separately for inclusion in the Energy Data Base. Ten papers had been entered earlier.

  11. 17th DOE nuclear air cleaning conference: proceedings. Volume 2

    International Nuclear Information System (INIS)

    Volume 2 contains papers presented at the following sessions: adsorption; noble gas treatment; personnel education and training; filtration and filter testing; measurement and instrumentation; air cleaning equipment response to accident related stress; containment venting air cleaning; and an open end session. Twenty-eight papers were indexed separately for inclusion in the Energy Data Base. Ten papers had been entered earlier

  12. Methods to Calculate the Heat Index as an Exposure Metric in Environmental Health Research

    OpenAIRE

    Anderson, G. Brooke; Bell, Michelle L.; Peng, Roger D.

    2013-01-01

    Background: Environmental health research employs a variety of metrics to measure heat exposure, both to directly study the health effects of outdoor temperature and to control for temperature in studies of other environmental exposures, including air pollution. To measure heat exposure, environmental health studies often use heat index, which incorporates both air temperature and moisture. However, the method of calculating heat index varies across environmental studies, which could mean tha...

  13. Dept and field size dependence of ratios of mass energy absorption coefficient, water to air, for kilovoltage X ray dosimetry

    International Nuclear Information System (INIS)

    Values of the ratio of the mass energy absorption coefficient, water to air, (?-baren/?)w,air, are required for insertion into the expression recommended for determining absorbed dose to water, Dw, in kilovoltage X ray beams using an air kerma calibrated ionization chamber. Values for both primary (i.e. free-in-air) spectra and spectra at depths within a water phantom have been calculated for low and medium energy X rays using the Monte Carlo method. These are [(?-baren/?)w,air]p, for HVLs between 0.05 and 22 mm A1 (0.03 and 6 mm Cu), and (?-baren(z, f)/?)w,air, for HVLs between 1 and 22 mm A1 (0.01 and 6 mm Cu), at depths (z) between 0 and 10 cm with circular field sizes (f) between 0.5 and 30 cm2 equivalent square. Primary spectra and the corresponding HVLs (in mm Cu or A1) were calculated using he programs of Birch and Marshall. X ray unit target angles and inherent/added filtrations were consistent with those used for the measured spectra of Seelentag et al. The EGS4 (Electron Gamma Shower version 4) Monte Carlo package was used to simulate photon transport within a water phantom through adaptation of the user code FLURZ. Monoenergetic ?-baren/? data were extracted from the work of Hubbell. It is evident that the first HVL is inadequate as a unique look-up parameter for (?-baren/?)w,air. The variation of (?-barenariation of (?-baren(z, f)/?)w,air with f and z is shown. The dependence of (?-baren(z, f)/?)w,air on f is significant, especially for less than 10 cm square fields. The corresponding dependence on z is less critical. (author). 14 refs, 4 figs, 1 tab

  14. A Social Capital Index

    Science.gov (United States)

    Gonzàlez-Aranguena, Enrique; Khmelnitskaya, Anna; Manuel, Conrado; del Pozo, Mónica

    2011-09-01

    We define an index of social capital using game-theoretical concepts. We assume that interests of individuals are presented by means of a cooperative game which take into account possible different players abilities whereas the network of relations is modeled by a graph. The social capital of each actor is then measured as the difference between his Myerson value and his Shapley value.

  15. Anomalies and index theory

    International Nuclear Information System (INIS)

    There is at present considerable interest among physicists in various anomalies that occur in gauge theories and their relation to the index theory of the Dirac operator. Numerous papers have appeared on the subject and it is the purpose of this paper to provide a general introduction and guide to the subject. The author concentrates on the main ideas since the detailed calculations are fully available in the literature. He begins by a brief review of the index theorem in its simplest form. This also enables him to establish the notation and terminology he uses which (inevitably) tends to differ slightly from that used in physics. He then goes on to describe a more general version of the index theorem, dealing with parameters. It is this version which is related to the anomalies that turn up in relation to the difficulties of defining gauge invariant determinants. After dealing with determinants he returns to the index theory explaining further refinements all of which help to throw further light on anomalies

  16. On indexed actions

    CERN Document Server

    Pisani, Claudio

    2012-01-01

    We present some laws relating the $\\Cat$-indexed categories of left, right and bi-actions: by defining $(A\\comp M)x = Mx^{Ax}$ one gets a biclosed monoidal action of $\\Set^{X\\op}$ on $(\\Set^X)\\op$, while $\\B X$ and $\\Cat/X$ act (partially) on their opposites by exponentials; both the inclusions $(\\B X,\\B X)\\to (\\Set^{X\\op},\\Set^X) \\to (\\Cat/X,\\Cat/X)$ preserve the (cartesian) monoidal structures and the actions, and the same holds for substitutions along functors. These strong morphisms of strong indexed monoidal actions have in fact a wider range of applications; in particular, replacing $\\Set$ with any (co)complete symmetric monoidal closed category $\\V$, we consider the pair of indexed categories $(\\V_0^{X\\op},\\V_0^X ; X\\in\\Cat)$ with the pair of biclosed indexed monoidal actions of each one on the opposite of the other one and its formal relationships with biactions and constant actions. Some of the resulting laws also hold in a fragment of biclosed bicategory (with an object supporting a symmetric monoid...

  17. Gradient Refractive Index Lenses.

    Science.gov (United States)

    Morton, N.

    1984-01-01

    Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

  18. Rederivation of Dst Index

    Science.gov (United States)

    Svalgaard, L.

    2005-12-01

    Derivation of the Dst geomagnetic index involves removing the quiet diurnal variation (Sq) caused by thermal winds and tides in the ionosphere maintained by solar EUV radiation. The standard procedure has been to fit average, smoothed curves to the Sq computed from the five internationally quietest days of each month and to use these curves on all days to remove Sq from the observed values of the horizontal component of the geomagnetic field for three stations in the northern hemsphere and one station in the southern hemisphere, then to average the resulting values (weigthed by latitude) into a global Dst index. This procedure is problematic because 1) the day-to-day variability of the regular diurnal variation (Sr) is as large as the variation itself and 2) an annual variation of the level of horizontal component is not properly compensated for by using an unequal number of northern and southern stations. We show how these problems can be avoided by using only nighttime values and by using an equal number of stations in both hemispheres and calculate a new index Dsv back to 1930 (potentially back to 1900 or beyond). Using this new index, the long-term trend, semiannual variation, and average storm signature (superposed epoch around SSCs) are studied.

  19. Air Transportation

    Science.gov (United States)

    Leske, Cavin.

    2002-01-01

    Air transportation is vitally important to the world's economy, as well as the thousands of people each day who make routine, long distance trips. While it is easy to take this convenience for granted, it is almost impossible to imagine life without it.Nearly a century has passed since the Wright brother's momentous flight, and preparations for next year's celebration are already underway. Two sites provide information about scheduled events for the festivities and help raise awareness of the history of flight. The first is operated by the American Institute of Aeronautics and Astronautics (AIAA) (1), and the other serves as the home page for the congressionally mandated Centennial of Flight Commission (2). The AIAA site has more background information, with a detailed timeline, biographies of flight pioneers, and interactive activities. The later site has video and sound clips, as well as details about webcasts that will be held for the celebration. A lot of educational materials are offered at the Dryden Flight Research Center (3). There are in-depth sections on flight testing and aeronautics, and many links to other useful resources are also given. The Air Transport Association (4) maintains an extensive handbook on several aspects of air transportation, ranging from economic view of the airline industry to the principles of flight and air traffic control. Technical specifications, design characteristics, and images are given in the aircraft museum on this site (5). Additionally, there are discussions of aerospike engines and hypersonic theory. A remarkable innovation in aircraft design is described here (6), the creators of the FanWing home page. This technology generates lift with "a horizontal-axis wing rotor," a technique that has not been successful until now. Details of the FanWing operation, including videos and news articles, are provided on the Web site. A NASA technical publication (7) documents the test results of a small, inflatable-winged aircraft. This unique design is thoroughly explained in this report, complete with diagrams that illustrate the components and operation of the craft. The Airworthiness Assurance Nondestructive Inspection Validation Center at Sandia National Laboratories (8) has a long history of assessing airplane conditions, and its work can be crucial to flight safety. The center's Web site discusses the accomplishments made since its inception.

  20. Disparities in exposure to air pollution during pregnancy.

    OpenAIRE

    Woodruff, Tracey J.; Parker, Jennifer D.; Kyle, Amy D.; Schoendorf, Kenneth C.

    2003-01-01

    Previous research shows poorer birth outcomes for racial and ethnic minorities and for persons with low socioeconomic status (SES). We evaluated whether mothers in groups at higher risk for poor birth outcomes live in areas of higher air pollution and whether higher exposure to air pollution contributes to poor birth outcomes. An index representing long-term exposure to criteria air pollutants was matched with birth certificate data at the county level for the United States in 1998-1999. We u...

  1. Response of air stagnation frequency to anthropogenically enhanced radiative forcing

    OpenAIRE

    Horton, Daniel E.; Harshvardhan,; Diffenbaugh, Noah S.

    2012-01-01

    Stagnant atmospheric conditions can lead to hazardous air quality by allowing ozone and particulate matter to accumulate and persist in the near-surface environment. By changing atmospheric circulation and precipitation patterns, global warming could alter the meteorological factors that regulate air stagnation frequency. We analyze the response of the National Climatic Data Center (NCDC) Air Stagnation Index (ASI) to anthropogenically enhanced radiative forcing using global climate model pro...

  2. Acute management of vascular air embolism

    Directory of Open Access Journals (Sweden)

    Shaikh Nissar

    2009-01-01

    Full Text Available Vascular air embolism (VAE is known since early nineteenth century. It is the entrainment of air or gas from operative field or other communications into the venous or arterial vasculature. Exact incidence of VAE is difficult to estimate. High risk surgeries for VAE are sitting position and posterior fossa neurosurgeries, cesarean section, laparoscopic, orthopedic, surgeries invasive procedures, pulmonary overpressure syndrome, and decompression syndrome. Risk factors for VAE are operative site 5 cm? above the heart, creation of pressure gradient which will facilitate entry of air into the circulation, orogenital sex during pregnancy, rapid ascent in scuba (self contained underwater breathing apparatus divers and barotrauma or chest trauma. Large bolus of air can lead to right ventricular air lock and immediate fatality. In up to 35% patient, the foramen ovale is patent which can cause paradoxical arterial air embolism. VAE affects cardiovascular, pulmonary and central nervous system. High index of clinical suspicion is must to diagnose VAE. The transesophgeal echocardiography is the most sensitive device which will detect smallest amount of air in the circulation. Treatment of VAE is to prevent further entrainment of air, reduce the volume of air entrained and haemodynamic support. Mortality of VAE ranges from 48 to 80%. VAE can be prevented significantly by proper positioning during surgery, optimal hydration, avoiding use of nitrous oxide, meticulous care during insertion, removal of central venous catheter, proper guidance, and training of scuba divers.

  3. Definitions and methodological issues regarding airline network concentration indexes [paper in Portuguese

    Directory of Open Access Journals (Sweden)

    Leandro M. Capitani

    2009-07-01

    Full Text Available This work aims to develop a review of recent articles regarding concentration of airline networks. Here I discuss the main concentration indexes proposed by recent papers and balance its advantages and disadvantages, with the aim of highlighting the effect that indexes have on the direction of air transportation policies.

  4. Critical dimension where the macroscopic definition of refractive index can be applied at a nanometric scale

    Science.gov (United States)

    Lebihan, Vincent; Pillonnet, Anne; Amans, David; Ledoux, Gilles; Marty, Olivier; Dujardin, Christophe

    2008-09-01

    This Brief Report reports a measurement of the critical dimension where the macroscopic definition of refractive index could be applied at nanometric scale. A fluorescent nanolayer is used as a local probe of the refractive index via its radiative lifetime. By covering the emitting layer with nanofilms of high refractive index material the sphere radius R in which the effective-medium theory has to be applied is estimated as ?/4 in air.

  5. EQ Index, 1971.

    Science.gov (United States)

    National Wildlife Federation, Washington, DC.

    To assess the status of our environmental quality and determine if we are winning or losing the campaign to save our environment, the National Wildlife Federation has developed this "EQ" kit. Multi-media materials help measure one's attitudes and activities in the areas of air, water, forests, wildlife, minerals, and soil conservation. Living…

  6. New Economy Index

    Science.gov (United States)

    The New Economy Index is a series of indicators that are "gathered from existing public and private data, to illustrate fundamental structural changes in the US economy, to show what those changes mean in the lives of working Americans, and to measure the nation's progress in several key foundation areas for future economic growth." The data in this excellent resource are divided into three sections. What's New About the New Economy includes thirteen indications that show the uniqueness and structure of the new technology-based and innovation-based economy. The second section considers the ways in which the New Economy will affect the lives of American workers. Finally, the third section, Foundations for Future Growth, projects the future growth of technology in the US. The site also includes information about the data sources, endnotes, and several side articles. Although the New Economy Index was created in 1998, the information is still valid and useful.

  7. Glycaemic index methodology.

    OpenAIRE

    Brouns, F.; Bjorck, I; Frayn, KN; Gibbs, AL; Lang, V.; SLAMA, G; Wolever, TM

    2005-01-01

    The glycaemic index (GI) concept was originally introduced to classify different sources of carbohydrate (CHO)-rich foods, usually having an energy content of >80 % from CHO, to their effect on post-meal glycaemia. It was assumed to apply to foods that primarily deliver available CHO, causing hyperglycaemia. Low-GI foods were classified as being digested and absorbed slowly and high-GI foods as being rapidly digested and absorbed, resulting in different glycaemic responses. Low-GI foods were ...

  8. A proteome quality index.

    Science.gov (United States)

    Zaucha, Jan; Stahlhacke, Jonathan; Oates, Matt E; Thurlby, Natalie; Rackham, Owen J L; Fang, Hai; Smithers, Ben; Gough, Julian

    2015-01-01

    We present the Proteome Quality Index (PQI; http://pqi-list.org), a much-needed resource for users of bacterial and eukaryotic proteomes. Completely sequenced genomes for which there is an available set of protein sequences (the proteome) are given a one- to five-star rating supported by 11 different metrics of quality. The database indexes over 3000 proteomes at the time of writing and is provided via a website for browsing, filtering and downloading. Previous to this work, there was no systematic way to account for the large variability in quality of the thousands of proteomes, and this is likely to have profoundly influenced the outcome of many published studies, in particular large-scale comparative analyses. The lack of a measure of proteome quality is likely due to the difficulty in producing one, a problem that we have approached by integrating multiple metrics. The continued development and improvement of the index will require the contribution of additional metrics by us and by others; the PQI provides a useful point of reference for the scientific community, but it is only the first step towards a 'standard' for the field. PMID:25339269

  9. 2001 Environmental Sustainability Index (ESI)

    National Aeronautics and Space Administration — The 2001 Environmental Sustainability Index (ESI) utilizes a refined methodology based on the 2000 Pilot ESI effort, to construct an index covering 122 countries...

  10. ISOTHERMAL AIR INGRESS VALIDATION EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Chang H Oh; Eung S Kim

    2011-09-01

    Idaho National Laboratory carried out air ingress experiments as part of validating computational fluid dynamics (CFD) calculations. An isothermal test loop was designed and set to understand the stratified-flow phenomenon, which is important as the initial air flow into the lower plenum of the very high temperature gas cooled reactor (VHTR) when a large break loss-of-coolant accident occurs. The unique flow characteristics were focused on the VHTR air-ingress accident, in particular, the flow visualization of the stratified flow in the inlet pipe to the vessel lower plenum of the General Atomic’s Gas Turbine-Modular Helium Reactor (GT-MHR). Brine and sucrose were used as heavy fluids, and water was used to represent a light fluid, which mimics a counter current flow due to the density difference between the stimulant fluids. The density ratios were changed between 0.87 and 0.98. This experiment clearly showed that a stratified flow between simulant fluids was established even for very small density differences. The CFD calculations were compared with experimental data. A grid sensitivity study on CFD models was also performed using the Richardson extrapolation and the grid convergence index method for the numerical accuracy of CFD calculations . As a result, the calculated current speed showed very good agreement with the experimental data, indicating that the current CFD methods are suitable for predicting density gradient stratified flow phenomena in the air-ingress accident.

  11. Sensitivity/uncertainty analysis for the Hiroshima dosimetry reevaluation effort

    International Nuclear Information System (INIS)

    Uncertainty estimates and cross correlations by range/survivor location have been obtained for the free-in-air (FIA) tissue kerma for the Hiroshima atomic event. These uncertainties in the FIA kerma include contributions due to various modeling parameters and the basic cross section data and are given at three ground ranges, 700, 1000 and 1500 m. The estimated uncertainties are nearly constant over the given ground ranges and are approximately 27% for the prompt neutron kerma and secondary gamma kerma and 35% for the prompt gamma kerma. The total kerma uncertainty is dominated by the secondary gamma kerma uncertainties which are in turn largely due to the modeling parameter uncertainties

  12. EPA Student Center: Air

    Science.gov (United States)

    Here are links to EPA and non-EPA resources to help students learn more about air quality and pollution prevention. These links provide information about acid rain, ozone depletion, the Clean Air Act, smog, indoor air quality, community air pollution information, UV radiation, and national air quality status and trends.

  13. Witten index from lattice simulation

    CERN Document Server

    Kanamori, Issaku

    2010-01-01

    I propose a method for measuring the Witten index using a lattice simulation. The index is useful to discuss spontaneous breaking of supersymmetry. As a test of the method, I also report some numerical results for the supersymmetric quantum mechanics, for which the index is known.

  14. Research on Translation of Index ?-Net based on Index ?-Calculus

    Directory of Open Access Journals (Sweden)

    Hui Kang

    2013-03-01

    Full Text Available In terms of the definitions and features of index ?-calculus, a new kind of index ?-net is proposed in this paper, which can reflect the system actions of index ?-calculus system. This article presents definitions of Index ?-calculus places, transitions and arcs. Meanwhile, the conditions to activate a transition and the effects on the tokens of its successor place are given as well. We try not to disturb the nature of petri net while defining index ?-nets and expound the structural congruence relationship between them which verifies the semantic correctness of index ?-nets. Finally, a simplified model of index ?-nets is built, and a complete procedure about how the internal channel can be exposed to the external system is offered according to the model.

  15. Air movement and perceived air quality

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Kaczmarczyk, J.

    2012-01-01

    The impact of air movement on perceived air quality (PAQ) and sick building syndrome (SBS) symptoms was studied. In total, 124 human subjects participated in four series of experiments performed in climate chambers at different combinations of room air temperature (20, 23, 26 and 28 °C), relative humidity (30, 40 and 70%) and pollution level (low and high). Most of the experiments were performed with and without facially applied airflow at elevated velocity. The importance of the use of recirculated room air and clean, cool and dry outdoor air was studied. The exposures ranged from 60. min to 235. min. Acceptability of PAQ and freshness of the air improved when air movement was applied. The elevated air movement diminished the negative impact of increased air temperature, relative humidity and pollution level on PAQ. The degree of improvement depended on the pollution level, the temperature and the humidity of the room air. At a low humidity level of 30% an increased velocity could compensate for the decreasein perceived air quality due to an elevated temperature ranging from 20 °C to 26 °C. In a room with 26 °C, increased air movement was also able to compensate for an increase in humidity from 30% to 60%, but not to 70%. The elevated velocity of recirculated polluted room air did not decrease the intensity of SBS symptoms, but movement of clean, cool and dry air did so. Energy-saving strategy of improving occupants' comfort in rooms by moving room air at high velocity and maintaining room temperature high at reduced supply of outdoor air or by a decrease of indoor air enthalpy should be cautiously implemented in buildings because the pollution level may still cause negative health effects. © 2011 Elsevier Ltd.

  16. Inline fiber interference-based refractive-index sensor

    Science.gov (United States)

    Gong, Zhenfeng; Zhang, Xinpu; Liu, Yun; Liu, Zigeng; Yu, Qingxu; Peng, Wei

    2014-11-01

    We report two fiber multiple-mode interferometers formed in photonic crystal fiber (PCF). The interference between the core and the cladding modes of a PCF is utilized. We use two methods to form a coupling point, and the cladding modes are excited from the fundamental core mode. One method is blowing compressed gas into the air holes and discharging at the coupling point; the air holes will expand due to gas expansion in the discharge process. Similarly, the other is discharging at the coupling point after the air is exhausted from the air holes, and the holes will contract during the process. By making another coupling point at a different location along the fiber, the proposed PCF interferometers are implemented. Experimental results show that the sensitivities of the two devices can achieve 1.54 and 1.45 nm for a 0.01 refractive index change.

  17. Clean air Hamilton 2001 progress report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-05-01

    This community initiative called Clean Air Hamilton was established to improve air quality in Hamilton, Ontario. It has been mandated to annually report on progress and provide advice with regard to current air quality issues. The quality of life of residents is improved as a result of the work performed by Clean Air Hamilton, and it also enhances Hamilton's image. Numerous inquiries have been received from City officials in several municipalities such as Toronto, Kitchener-Waterloo and Windsor as a testament to the success of the initiative. Financial support is received from all levels of government. The funding received from the Council has helped in attracting additional donations in support of this initiative. Clean Air Hamilton was involved in one capacity or another in research, emissions reduction projects and public awareness campaigns during 2001, and its contributions were valued at approximately 500,000 dollars. The City of Hamilton was awarded the United Nations for Human Settlements award as a result of Clean Air Hamilton's community process in local air quality improvement. In addition, the City received the Dubai International Award for Best Practices in Improving the Living Environment. Clean Air Hamilton is ready to move to the next phase, which requires moving current structures that supplements voluntary commitments with committed funding from key stakeholders. Since June 1996, the advisory level of 32 on the Air Pollution Index has not been reached, and rarely goes over 20. Throughout the 1990s, levels of toxics have decreased significantly. A three-year self-sustaining program should be developed and funding sought for those initiatives, discussions should be facilitated among industrial stakeholders when they address air quality issues, and research should continue to be supported and advice on current air quality issues be provided to City Council. 1 fig.

  18. Negative refractive index metamaterials

    Directory of Open Access Journals (Sweden)

    Willie J. Padilla

    2006-07-01

    Full Text Available Engineered materials composed of designed inclusions can exhibit exotic and unique electromagnetic properties not inherent in the individual constituent components. These artificially structured composites, known as metamaterials, have the potential to fill critical voids in the electromagnetic spectrum where material response is limited and enable the construction of novel devices. Recently, metamaterials that display negative refractive index – a property not found in any known naturally occurring material – have drawn significant scientific interest, underscoring the remarkable potential of metamaterials to facilitate new developments in electromagnetism.

  19. Refractive index based measurements

    DEFF Research Database (Denmark)

    SØrensen, Henrik SchiØtt Technical University of Denmark,

    In a method for performing a refractive index based measurement of a property of a fluid such as chemical composition or temperature by observing an apparent angular shift in an interference fringe pattern produced by back or forward scattering interferometry, ambiguities in the measurement caused by the apparent shift being consistent with one of a number of numerical possibilities for the real shift which differ by 2n are resolved by combining measurements performed on the same sample using light paths therethrough of differing lengths.

  20. About Air Toxics

    Science.gov (United States)

    ... Toxics Web site About Air Toxics About Air Toxics What are toxic air pollutants? What are the ... emissions? Controls for industrial and commercial sources of toxics -- EPA has issued rules covering over 80 categories ...

  1. Air Travel and Diabetes

    Science.gov (United States)

    ... Size: A A A Listen Air Travel and Diabetes We continue to advocate for the rights travelers ... to people with diabetes. Explore: Air Travel and Diabetes Fact Sheet: Air Travel and Diabetes This fact ...

  2. Flat lenses constructed by graded negative index-based photonic crystals with tuned configurations

    International Nuclear Information System (INIS)

    Flat lenses are designed by means of graded negative refractive index-based photonic crystals (PCs) constructed using air-holes tuned with different shapes. By gradually modifying the filling factor along the transverse direction, we obtain the graded negative index-based lenses for the purpose of focusing an incident plane wave. The finite-difference and time-domain (FDTD) algorithm is adopted for numerical calculation. Our calculation results indicate that these lenses can finely focus incident plane waves. Moreover, for the same size of air-holes, the focusing properties of the lens with rectangular air-holes are better than those with the other shaped air-holes. The graded negative index PCs lenses could possibly enable new applications in optoelectronic systems. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  3. Shelter and indoor air.

    OpenAIRE

    Stolwijk, J A

    1990-01-01

    Improvements in outdoor air quality that were achieved through the implementation of the Clean Air Act accentuate the quality of the indoor air as an important, if not dominant, factor in the determination of the total population exposure to air contaminants. A number of developments are adding important new determinants of indoor air quality. Energy conservation strategies require reductions in infiltration of outdoor air into buildings. New materials introduced in the construction and in th...

  4. Six Common Air Pollutants

    Science.gov (United States)

    The EPA's site about the six common air pollutants is a great resource for the public, or for anyone studying or teaching about air pollution and other environmental issues. Air pollution trends are outlined on the site and a brief backround shows highlights of air pollutant history including the Clean Air Act and different standards. This site is a great place to find the most recent information about air pollutants and quality in the U.S.

  5. Air Quality System (AQS)

    U.S. Environmental Protection Agency — The Air Quality System (AQS) database contains measurements of air pollutant concentrations from throughout the United States and its territories. The measurements...

  6. Generalizations of Wiener polarity index and terminal Wiener index

    CERN Document Server

    Ilic, Aleksandar

    2011-01-01

    In theoretical chemistry, distance-based molecular structure descriptors are used for modeling physical, pharmacologic, biological and other properties of chemical compounds. We introduce a generalized Wiener polarity index $W_k (G)$ as the number of unordered pairs of vertices $\\{u, v\\}$ of $G$ such that the shortest distance $d (u, v)$ between $u$ and $v$ is $k$. For $k = 3$, we get standard Wiener polarity index. Furthermore, we generalize the terminal Wiener index $TW_k (G)$ as the sum of distances between all pairs of vertices of degree $k$. For $k = 1$, we get standard terminal Wiener index. In this paper we describe a linear time algorithm for computing these indices for trees and partial cubes, and characterize extremal trees maximizing the generalized Wiener polarity index and generalized terminal Wiener index among all trees of given order $n$.

  7. Graded Index Microstructured Polymer Optical Fibers for Terahertz Applications

    CERN Document Server

    Ma, Tian; Wang, Lili; Skorobogatiy, Maksim

    2014-01-01

    Graded index microstructured polymer optical fiber incorporating a specially designed air-hole array featuring variable air-hole diameters and inter-hole separation is proposed, fabricated and characterized in view of the fiber potential applications in low-loss, low-dispersion terahertz guidance. The proposed fiber features simultaneously low chromatic and intermodal dispersions, as well as low loss in the terahertz spectral range. We then experimentally demonstrate that proposed fibers exhibit smaller pulse distortion, larger bandwidth and more reliable excitation when compared to the porous fibers of comparable geometry.

  8. Effect of Preventive Maintenance on Performance of Air Heater in a Power Plant

    International Nuclear Information System (INIS)

    Air heater used in power plant helps increase the thermal efficiency of the boiler by recovering the heat from the boiler flue gas and thus preventing the loss of useful heat. This study investigates the effect of preventive maintenance on the performance of the air heater in a power plant. Performance indexes for the air heater are calculated to observe the changes in the performance and operation status of the air heater before and after preventive maintenance. The major performance indexes considered are temperature efficiency of the flue gas side, air leakage rate, heat recovery rate, heat transmission rate, and heat capacity ratio. The performance of the air heater is evaluated before and after preventive maintenance; our results show that all the above mentioned performance indexes are improved after the maintenance

  9. 2012 Environmental Performance Index and Pilot Trend Environmental Performance Index

    National Aeronautics and Space Administration — The 2012 Environmental Performance Index (EPI) ranks 132 countries on 22 performance indicators in the following 10 policy categories: environmental burden of...

  10. A short survey on Air Quality Indicators: properties, use and (mis)use

    OpenAIRE

    Franceschini, Fiorenzo; Galetto, Maurizio; Maisano, Domenico Augusto Francesco

    2005-01-01

    Purpose - Analysis and comparison of three existing indicators of the air quality: the American air quality index, the French Atmo, and the Italian Indice di Qualita` dell'Aria. Design/methodology/approach - International general and organic regulations to control air quality do not exist yet. Consequently many countries have independently implemented specific indicators to monitor the air pollution and then alert people of resulting health risks. The paper focuses on three of them. Each one ...

  11. September Consumer Price Index

    Science.gov (United States)

    Missner, Emily D.

    On Tuesday October 19, 1999, the US Department of Labor released its September 1999 Consumer Price Index (CPI), which showed a rise of 0.4 percent, the third monthly rise in a row. Wall Street breathed a sigh of relief at the news of the report as recent anxiety over the rising CPI and the threat of interest rates had sent the Nasdaq plunging. Tuesday, after the release of the report, stocks jumped over 200 points. The higher prices of tobacco and apparel boosted the CPI, and industries such as transportation, food, and lodging also showed the effects of inflation. The following nine resources include news briefs, commentary, and documents examining the impact of the September CPI as well as some of the unease about the US economy and inflation.

  12. Global Enhanced Vegetation Index

    Science.gov (United States)

    2002-01-01

    By carefully measuring the wavelengths and intensity of visible and near-infrared light reflected by the land surface back up into space, the Moderate-resolution Imaging Spectroradiometer (MODIS) Team can quantify the concentrations of green leaf vegetation around the world. The above MODIS Enhanced Vegetation Index (EVI) map shows the density of plant growth over the entire globe. Very low values of EVI (white and brown areas) correspond to barren areas of rock, sand, or snow. Moderate values (light greens) represent shrub and grassland, while high values indicate temperate and tropical rainforests (dark greens). The MODIS EVI gives scientists a new tool for monitoring major fluctuations in vegetation and understanding how they affect, and are affected by, regional climate trends. For more information, read NASA Unveils Spectacular Suite of New Global Data Products from MODIS. Image courtesy MODIS Land Group/Vegetation Indices, Alfredo Huete, Principal Investigator, and Kamel Didan, University of Arizona

  13. Indexing contamination surveys

    International Nuclear Information System (INIS)

    The responsibility for safely managing the Tank Farms at Hanford belongs to Lockheed Martin Hanford Corporation which is part of the six company Project Hanford Management Team led by Fluor Daniel Hanford, Inc.. These Tank Farm Facilities contain numerous outdoor contamination areas which are surveyed at a periodicity consistent with the potential radiological conditions, occupancy, and risk of changes in radiological conditions. This document describes the survey documentation and data tracking method devised to track the results of contamination surveys this process is referred to as indexing. The indexing process takes a representative data set as an indicator for the contamination status of the facility. The data are further manipulated into a single value that can be tracked and trended using standard statistical methodology. To report meaningful data, the routine contamination surveys must be performed in a manner that allows the survey method and the data collection process to be recreated. Three key criteria are necessary to accomplish this goal: Accurate maps, consistent documentation, and consistent consolidation of data meeting these criteria provides data of sufficient quality to be tracked. Tracking of survey data is accomplished by converting the individual survey results into a weighted value, corrected for the actual number of survey points. This information can be compared over time using standard statistical analysis to identify trends. At the Tank Farms, the need to track and trend the facility's radiological status presents unique challenges. Many of these Tank Farm facilities date back to the second world war. The Tank Farm Facilities are exposed to weather extremes, plant and animal intrusion, as well as all of the normal challenges associated with handling radiological waste streams. Routine radiological surveys did not provide a radiological status adequate for continuing comparisons

  14. Refractive Index Compensation in Over-Determined Interferometric Systems

    Directory of Open Access Journals (Sweden)

    Zden?k Buchta

    2012-10-01

    Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.

  15. Hazardous air pollutants

    International Nuclear Information System (INIS)

    This chapter presents an overview of the requirements of Title 3 of the 1990 Amendments to the Clean Air Act. The following topics are included: listed air toxics; sources covered by the program; standards for regulation of air toxics; area source program; air toxics permit program; prevention of accidental releases; and duties of the Risk Assessment and Management Commission

  16. Improved price index for condominiums

    OpenAIRE

    Song, Han-Suck; Wilhelmsson, Mats

    2009-01-01

    This paper proposes a price index construction methodology that can increase the quality ofprice index data for condominiums in Sweden. Currently, officially published market priceindexes for condominiums and houses in Sweden suffer from a number of shortcomings.Notably they do not control for quality, or they are based on dates when transfer of ownershipof the home occurs, and not the contract date. We develop a new price index that both controlsfor quality and reflect most recent price leve...

  17. Prevalent Color Extraction and Indexing

    OpenAIRE

    Thyagharajan, K. K.; Minu, R. I.

    2014-01-01

    Colors in an image provides tremendous amount of information. Using this color information images can be segmented, analyzed, labeled and indexed. In content based image retrieval system, color is one of the basic primitive features used. In Prevalent Color Extraction and indexing, the most extensive color on an image is identified and it is used for indexing. For implementation, Asteroideae flower family image dataset is used. It consist of more than 16,000 species, among them nearly 100 spe...

  18. The Smart Beta Indexing Puzzle

    OpenAIRE

    Cazalet, Zelia; Grison, Pierre; Roncalli, Thierry

    2013-01-01

    In this article, we consider smart beta indexing, which is an alternative to capitalization-weighted (CW) indexing. In particular, we focus on risk-based (RB) indexing, the aim of which is to capture the equity risk premium more effectively. To achieve this, portfolios are built which are more diversified and less volatile than CW portfolios. However, RB portfolios are less liquid than CW portfolios by construction. Moreover, they also present two risks in terms of passive management: trackin...

  19. Air filtration and indoor air quality

    DEFF Research Database (Denmark)

    Bekö, Gabriel

    2006-01-01

    Demands for better indoor air quality are increasing, since we spend most of our time indoors and we are more and more aware of indoor air pollution. Field studies in different parts of the world have documented that high percentage of occupants in many offices and buildings find the indoor air quality (IAQ) unacceptable and suffer from Sick Building Syndrome (SBS) symptoms (e.g. respiratory, headache, fatigue, etc.). In addition, prevalence of asthma and other respiratory and allergic diseases have increased during the past decades. The effect is most likely related to the environment. Without decent ventilation and air cleaning/air filtration, high indoor air quality cannot be accomplished. The need for effective air filtration has increased with increasing evidence on the hazardous effects of fine particles. Moreover, the air contains gaseous pollutants, removal of which requires various air cleaning techniques. Supply air filter is one of the key components in the ventilation system. Studies have shown that used ventilation filters themselves can be a significant source of indoor air pollution with consequent impact on perceived air quality, sick building syndrome symptoms and performance. Usually, increasing the ventilation rate improves the air quality, however in the case of used ventilation filters the benefits from increasing the airflow are smaller than usual. Moreover, the ever-increasing pressure drop of bag filters tends to raise energy costs of ventilation systems. These contradictions should motivate manufacturers and researchers to develop new efficient filtration techniques and/or improve the existing ones. Development of low polluting filtration techniques, which are at the same time easy and inexpensive to maintain is the way forward in the future.

  20. DESCRIPTION OF EVALUATION INDEXES FOR PERFORMANCE OF PHYSICAL EDUCATION TEACHERS

    Directory of Open Access Journals (Sweden)

    Mehr Ali Hemmatinezhad

    2012-03-01

    Full Text Available MIRKAZEMI, S.A. ; ALIYANI, M.H. ; KASHTIDAR, M. ; HEMMATINEZHAD, M.A. Description of evaluation indexes for performance of physical education teachers. Brazilian Journal of Biomotricity. v. 6, n. 1, p. 33-42, 2012. This paper presents evaluation indexes for performance of physical education teachers, because they play a vital role in the training and education. Research society include all of experts in the school sporting affairs , that we select them purposely .we use to research from self-designed question air and its validity byconsensus of experts .we use Alpha cronbach correlation (0.78 for its reliability. Based on the experts opinions (Delphi method, we modify them during four stages. After modifications of each stages, we suggest another modification to them and finally, we reach to a consensus based on the Kendall coefficient (w=0.702 regarding to evaluation indexes. The results show that among 40 proposed indexes. In the 9 dimensions, 8 indexes are very necessary and 4 indexes are less necessary. Teacher evaluation needs to compile standard, thereby we evaluate performances effectively and efficiently. Thus we suggest that reviewin the teachers evaluation system can show our system weaknesses and strengthens and we evaluate teacher's performance efficiently.

  1. 2008 Environmental Performance Index (EPI)

    National Aeronautics and Space Administration — The 2008 Environmental Performance Index (EPI) centers on two broad environmental protection objectives: (1) reducing environmental stresses on human health, and...

  2. Viva the h-index

    OpenAIRE

    Waaijers, Leo

    2011-01-01

    In their article 'The inconsistency of the h-index' Ludo Waltman and Nees Jan van Neck give three examples to demonstrate the inconsistency of the h-index. As will be explained, a little extension of their examples just illustrate the opposite, a stable feature of the h-index. For starting authors it, the h-index that is, focusses on the number of articles; for experienced authors its focus shifts towards the citation scores. This feature may be liked or not but does not mak...

  3. Curvature Index of Pincer Nail

    Directory of Open Access Journals (Sweden)

    Tetsuji Yabe, MD, PhD

    2013-10-01

    Full Text Available Summary: Pincer nails are a common problem, and various treatments have been reported. However, there is no simple assessment of severity. We designed a curvature index for the nail plate to assess the severity of pincer nail. Measurement of the curvature index was as follows. The apparent width of the nail tip was defined as A, and the traced length of the nail tip was defined as B. The curvature index was defined as B divided by A (B/A. With this curvature index, it is easy to describe the severity of the pincer nail and to compare the improvement before and after treatment.

  4. 2002 Environmental Sustainability Index (ESI)

    National Aeronautics and Space Administration — The 2002 Environmental Sustainability Index (ESI) measures overall progress toward environmental sustainability for 142 countries based on environmental systems,...

  5. 2010 Environmental Performance Index (EPI)

    National Aeronautics and Space Administration — The 2010 Environmental Performance Index (EPI) ranks 163 countries on environmental performance based on twenty-five indicators grouped within ten core policy...

  6. Advances in air to air refuelling

    Science.gov (United States)

    Thomas, Peter R.; Bhandari, Ujjar; Bullock, Steve; Richardson, Thomas S.; du Bois, Jonathan L.

    2014-11-01

    An increasing interest over the last decade in developing unmanned aerial systems' technologies has prompted research into methods for automating air to air refuelling processes. Furthermore, for systems with increased autonomy the necessary logic and flight control systems to perform autonomous air to air refuelling is now being pursued. There has already been significant research in position tracking, rendezvous scheduling, apparatus modelling, wake effects, and vision-based sensors to support refuelling of unmanned systems and to increase the autonomy in manned aircraft refuelling. Many of these build upon considerable research and understanding that has matured for manned air to air refuelling. This paper reviews the current, and future, state of research in this area.

  7. Temperature insensitive lower-index-mode photonic crystal nanobeam cavity.

    Science.gov (United States)

    Zhang, Yuguang; Shi, Yaocheng

    2015-01-15

    We present the design, fabrication, and characterization of a temperature insensitive lower-index-mode photonic crystal (PhC) nanobeam (NB) cavity by overlaying SU-8 cladding. The lower-index-mode is utilized to control the amount of light confined in the SU-8 cladding to compensate for the thermo-optic effect of silicon. The temperature sensitivity of the PhC NB cavity can be tuned by changing the radius of the air holes. The temperature dependence of the PhC NB cavity with SU-8 cladding is demonstrated to be 5.1??pm/°C over 50°C temperature range. The measured quality factor of the temperature insensitive lower-index-mode PhC NB cavity is ?1×10(4). PMID:25679860

  8. Air movement and perceived air quality

    OpenAIRE

    Melikov, Arsen Krikor; J. Kaczmarczyk

    2011-01-01

    The impact of air movement on perceived air quality (PAQ) and sick building syndrome (SBS) symptoms was studied. In total, 124 human subjects participated in four series of experiments performed in climate chambers at different combinations of room air temperature (20, 23, 26 and 28 °C), relative humidity (30, 40 and 70%) and pollution level (low and high). Most of the experiments were performed with and without facially applied airflow at elevated velocity. The importance of the use of reci...

  9. Beyond KERMA - neutron data for biomedical applications

    International Nuclear Information System (INIS)

    Presently, many new applications of fast neutrons are emerging or under development, like dose effects due to cosmic-ray neutrons for airplane crew, fast-neutron cancer therapy, studies of electronic failures induced by cosmic-ray neutrons, and accelerator-driven incineration of nuclear waste and energy production technologies. All these areas would benefit from improved neutron dosimetry. In this paper, the present rapid progress on measurements of double-differential neutron-induced nuclear reaction data are described. With such data at hand, the full response of, in principle, any system, including human tissue, can be calculated in detail. This could potentially revolutionise our understanding of biological effects in tissue due to fast neutrons. (author)

  10. Honey and Glycemic Index

    Directory of Open Access Journals (Sweden)

    Sibel Silici

    2015-02-01

    Full Text Available Honey is a natural substance produced by honeybees (Apis mellifera L. from the nectar of blossoms or from secretions of living parts of plants or excretions of plant sucking insects on the living parts of plants, which honeybees collect, transform and combine with specific substances of their own, store and leave in the honey comb to ripen and mature. Besides being of carbohydrate-rich food, honey has been used as a functional food for its potential health benefits. To explain how different kinds of carbohydrate-rich foods directly affect blood sugar, the researchers developed the concept of the “glycemic index” (GI that ranks carbohydrates on a scale based on how quickly and how much they raise blood sugar levels after eating. The diet should include adequate and healthy balance of nutrients, and according to many health professionals the concept of GI provides a useful means of selecting the most appropriate carbohydrate containing foods for the maintenance of health and the treatment of several disease states. There have been some studies on determining the GI of honey. Further more, we need to determine the GI of various honey types with different botanical and geografical origin. Researches on the issue will serve to bring awareness in the public consciousness.

  11. State of the air report 2007 in British Columbia

    International Nuclear Information System (INIS)

    This report provided details of local and regional air quality measurements and provided updates on information related to climate change in British Columbia (BC). A description of the new air quality health index pilot for users in BC was provided. The report was created by the BC Lung Association and various municipal, regional, provincial, and federal air quality protection agencies in order to develop a better understanding of issues that affect air quality. The report provided details of common air pollutants in BC, as well as details of pollution levels from various monitoring sites in the province. Ground-level ozone measurements were presented, as well as ambient levels of nitrogen dioxide (NO2) and sulphur dioxide (SO2). Details of the Quesnel airshed management plan were outlined. Updates on locomotive emissions and woodburning stove emissions in the province were provided. New methods of disposing agricultural plastics were discussed. Recent air pollution bylaws, regulations, and program management plans were also outlined. 17 figs

  12. Maslov index for Hamiltonian systems

    Directory of Open Access Journals (Sweden)

    Alessandro Portaluri

    2008-01-01

    Full Text Available The aim of this article is to give an explicit formula for computing the Maslov index of the fundamental solutions of linear autonomous Hamiltonian systems in terms of the Conley-Zehnder index and the map time one flow.

  13. Simplifying the Water Poverty Index

    Science.gov (United States)

    Cho, Danny I.; Ogwang, Tomson; Opio, Christopher

    2010-01-01

    In this paper, principal components methodology is used to derive simplified and cost effective indexes of water poverty. Using a well known data set for 147 countries from which an earlier five-component water poverty index comprising of "Resources," "Access," "Capacity," "Use" and "Environment" was constructed, we find that a simplified…

  14. Infrared refractive index of diamond

    International Nuclear Information System (INIS)

    The refractive index of natural Type IIa diamond is reported for spectral region 2.5--25mm. The data have been filtered to a Herzberger-type dispersion formula with a quality of fit of a few places in the fifth decimal place. The resultant index uncertainty is abut 10-3

  15. Estrada index and Chebyshev polynomials

    Science.gov (United States)

    Ginosar, Yuval; Gutman, Ivan; Mansour, Toufik; Schork, Matthias

    2008-03-01

    Let G be a graph whose eigenvalues are ?1, ?2,…, ?n. The Estrada index of G is equal to ?i=1ne. We point out certain classes of graphs whose characteristic polynomials are closely connected to the Chebyshev polynomials of the second kind. Various relations, in particular approximations, for the Estrada index of these graphs are obtained.

  16. VISCOSITY INDEX OF RAPESEED OIL

    Directory of Open Access Journals (Sweden)

    IOANA STANCIU

    2011-09-01

    Full Text Available In this paper were determined viscosity index of rapeseed oil using two methods. Viscosity index is calculated from the measured viscosity at 40 and 1000C using ASTM D 2270 and method graphically using ASTM D 341. The viscosity-temperature coefficient of rapeseed oil was calculated from the measured viscosity at 40 and 1000C.

  17. Factor Simplicity Index and Transformations

    Science.gov (United States)

    Bentler, P. M.

    1977-01-01

    A scale-invariant index of factorial simplicity is proposed as a summary statistic for principal components and factor analysis. The index ranges from zero to one, and attains its maximum when all variables are simple rather than factorially complex. (Author/JKS)

  18. Employment Cost Index, March 2001

    Science.gov (United States)

    The Employment Cost Index "measures changes in compensation costs, which include wages, salaries, and employer costs for employee benefits." Released on April 26, 2001, the Employment Cost Index for March 2001 was 152.5, which shows a rise of 4.1 percent from March 2000.

  19. Review of air pollution and health impacts in Malaysia

    International Nuclear Information System (INIS)

    In the early days of abundant resources and minimal development pressures, little attention was paid to growing environmental concerns in Malaysia. The haze episodes in Southeast Asia in 1983, 1984, 1991, 1994, and 1997 imposed threats to the environmental management of Malaysia and increased awareness of the environment. As a consequence, the government established Malaysian Air Quality Guidelines, the Air Pollution Index, and the Haze Action Plan to improve air quality. Air quality monitoring is part of the initial strategy in the pollution prevention program in Malaysia. Review of air pollution in Malaysia is based on the reports of the air quality monitoring in several large cities in Malaysia, which cover air pollutants such as Carbon monoxide (CO), Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2), Ozone (O3), and Suspended Particulate Matter (SPM). The results of the monitoring indicate that Suspended Particulate Matter (SPM) and Nitrogen Dioxide (NO2) are the predominant pollutants. Other pollutants such as CO, Ox, SO2, and Pb are also observed in several big cities in Malaysia. The air pollution comes mainly from land transportation, industrial emissions, and open burning sources. Among them, land transportation contributes the most to air pollution. This paper reviews the results of the ambient air quality monitoring and studies related to air pollution and health impactsd health impacts

  20. Long period gratings in air-core photonic bandgap fibers.

    Science.gov (United States)

    Wang, Yiping; Jin, Wei; Ju, Jian; Xuan, Haifeng; Ho, Hoi Lut; Xiao, Limin; Wang, Dongning

    2008-02-18

    Long period fiber gratings in hollow-core air-silica photonic bandgap fibers were produced by use of high frequency, short duration, CO2 laser pulses to periodically modify the size, shape and distribution of air holes in the microstructured cladding. The resonant wavelength of these gratings is highly sensitivity to strain but insensitive to temperature, bend and external refractive index. These gratings can be used as stable spectral filters and novel sensors. PMID:18542362

  1. Proceedings of the international conference on residential air pollution

    International Nuclear Information System (INIS)

    The proceedings of the International conference on Residential Air Pollution are presented. The perceptions and aspirations of residents with regard to clean air was the main theme of the conference. Emphasis was also placed on the pollution and effects brought about by the domestic burning of fuels for heating and cooking in third world environments. Only two papers were indexed for INIS. The remaining papers were considered to be outside the subject scope of INIS

  2. Terahertz Wave Guiding by Femtosecond Laser Filament in Air

    OpenAIRE

    Zhao, Jiayu; Zhang, Yizhu; Wang, Zhi; chu, Wei; Zeng, Bin; Cheng, Ya; Xu, Zhizhan; Liu, Weiwei

    2013-01-01

    Femtosecond laser filament generates strong terahertz (THz) pulse in air. In this paper, THz pulse waveform generated by femtosecond laser filament has been experimentally investigated as a function of the length of the filament. Superluminal propagation of THz pulse has been uncovered, indicating that the filament creates a THz waveguide in air. Numerical simulation has confirmed that the waveguide is formed because of the radially non-uniform refractive index distribution ...

  3. EXPERIMENTAL INVESTIGATION ON ROOM AIR FLOW PATTERN & THERMAL COMFORT QUANTIFICATION

    Directory of Open Access Journals (Sweden)

    Yogesh S. Fulpagare

    2013-08-01

    Full Text Available It is well known that indoor environment is an important factor not only for occupants’ comfort as a whole, but also for their health and productivity. Air distribution achieves the acceptable levels of temperature, humidity, cleanliness and air motion in the occupied zone of conditioned area. All this is done in such a manner that the occupant does not experience any draft. Airflow and transport phenomena play an important role in air quality, thermal comfort and energy consumption in buildings. Air movement is one of the six main variables determining human thermal comfort. The present work focuses on the room air flow pattern in terms of temperature and velocity along with thermal comfort quantification by varying clothing index. Room air flow pattern in the two test rooms, University conference hall and RAC (Refrigeration and Air Conditioning Lab are studied under four conditions; natural, only fan, only AC, fan with AC. Effect of air conditioner position on the room air flow pattern is also studied. Thermal comfort is quantified using standard ASHRAE sensational equation based on the feelings of the four B. Tech students at various clothing index and exposure period. The contour of the flow patterns are plotted using ORIGIN 6.1 software.It is advisable to operate the ceiling fan at moderate speed with air conditioner to get the uniform flow pattern with respect to temperature and velocity which leads to saving in energy. Air flow pattern depends on the location of the air conditioner. Thermal comfort depends on the clothing resistance and activity level.

  4. Vegetation fires and air pollution in Vietnam.

    Science.gov (United States)

    Le, Thanh Ha; Thanh Nguyen, Thi Nhat; Lasko, Kristofer; Ilavajhala, Shriram; Vadrevu, Krishna Prasad; Justice, Chris

    2014-12-01

    Forest fires are a significant source of air pollution in Asia. In this study, we integrate satellite remote sensing data and ground-based measurements to infer fire-air pollution relationships in selected regions of Vietnam. We first characterized the active fires and burnt areas at a regional scale from MODIS satellite data. We then used satellite-derived active fire data to correlate the resulting atmospheric pollution. Further, we analyzed the relationship between satellite atmospheric variables and ground-based air pollutant parameters. Our results show peak fire activity during March in Vietnam, with hotspots in the Northwest and Central Highlands. Active fires were significantly correlated with UV Aerosol Index (UVAI), aerosol extinction absorption optical depth (AAOD), and Carbon Monoxide. The use of satellite aerosol optical thickness improved the prediction of Particulate Matter (PM) concentration significantly. PMID:25108840

  5. Air conditioning systems to clean radioactive air

    International Nuclear Information System (INIS)

    The author reports a study by the Institutes fuer Klimatechnik and Umweltschutz Giessen that shows that air conditioning systems not only make the atmosphere more comfortable, they also extract dust particles. This cleaning action is also valid for radioactively contaminated air. (G.T.H./Auth.)

  6. Louisiana ESI: LG_INDEX (Large Index Polygons)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all the hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

  7. Guam and the Northern Mariana Islands ESI: INDEX (Index Polygons)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

  8. ?????? ????????? ??????? airBaltic

    Index Scriptorium Estoniae

    2011-01-01

    Läti valitsus peab lähiajal otsustama lennufirma airBaltic likiviidsuse küsimuse. Bookinghouse'i valdav firma JSC Interno Partners teatas, et lennufirma Air Baltic segane finantsseis sunnib neid ettevõtte piletimüügi peatama

  9. Lead in Air

    Science.gov (United States)

    ... more Learn about lead in paint, dust and soil Lead (Pb) is a metal found naturally in ... about lead: Basic Information - Basics about lead air pollution. Health - Effects of lead air pollution. Lead Standards - ...

  10. Indoor air pollution control

    International Nuclear Information System (INIS)

    This book presents an overview of indoor air pollution control. Asbestos, combustion-generated pollutants, and radon are among the problems considered. Source control, policy and regulatory considerations, and air quality diagnostics are discussed

  11. AirCompare

    U.S. Environmental Protection Agency — AirCompare contains air quality information that allows a user to compare conditions in different localities over time and compare conditions in the same location...

  12. Indoor Air Pollution

    Science.gov (United States)

    We usually think of air pollution as being outdoors, but the air in your house or office could also be polluted. Sources of indoor pollution include Mold and pollen Tobacco smoke Household products ...

  13. Air Quality Facilities

    Iowa State University GIS Support and Research Facility — Facilities with operating permits for Title V of the Federal Clean Air Act, as well as facilities required to submit an air emissions inventory, and other...

  14. Impact coverage of the success-index

    OpenAIRE

    Egghe, Leo

    2014-01-01

    We show mathematically that the success-index can be any of the following impact indices, dependent on the value of the threshold used in the definition of the success-index: Hirsch-index (h-index), g-index, generalized Wu- and Kosmulski-indices, the average.

  15. The spiral index of knots

    CERN Document Server

    Adams, Colin; Hudson, Rachel; Morrison, Ralph; Starkston, Laura; Taylor, Samuel; Turanova, Olga

    2009-01-01

    Two new invariants that are closely related to Milnor's curvature-torsion invariant are introduced. The first, the spiral index of a knot, captures the minimum number of maxima among all knot projections that are free of inflection points. This invariant is closely related to both the bridge and braid index of the knot. The second, the projective superbridge index, provides a method of counting the greatest number of maxima that occur in a given knot projection. In addition to investigating how these invariants are related to the classical invariants, we utilize them to determine all knots with curvature-torsion invariant equal to 6 pi.

  16. The 3D Indexing Problem

    OpenAIRE

    Breuel, Thomas M.

    1993-01-01

    This paper discusses the problem of 3D indexing. That is, given a collection of 3D object models (CAD models, formalized as collections of labeled 3D points), an indexing algorithm may perform off-line pre-processing to generate a data structure that allows it to decide quickly whether a given 2D image was contains any of the objects represented by the 3D models. We first review and develop some mathematical machinery. Next, the indexing problem is related to well-known point-location and sea...

  17. A STUDY ON VARIATION IN BIOCHEMICAL ASPECTS OF DIFFERENT TREE SPECIES WITH TOLERANCE AND PERFORMANCE INDEX

    OpenAIRE

    MEHA BORA; NAMITA JOSHI

    2014-01-01

    The present study was undertaken to evaluate the variation between biochemical characteristics and air pollution tolerance index (APTI) of 6 different plant species. The results of the present study indicate that APTI was significantly correlated with total chlorophyll, ascorbic acid, leaf pH for all species and are the most significant and determining factors on which the tolerance depends. The order of tolerance index of plant species is as follows Saraca indica (13.71), Azadira...

  18. Improving the Performance of Temperature Index Snowmelt Model of SWAT by Using MODIS Land Surface Temperature Data

    OpenAIRE

    Yan Yang; Takeo Onishi; Ken Hiramatsu

    2014-01-01

    Simulation results of the widely used temperature index snowmelt model are greatly influenced by input air temperature data. Spatially sparse air temperature data remain the main factor inducing uncertainties and errors in that model, which limits its applications. Thus, to solve this problem, we created new air temperature data using linear regression relationships that can be formulated based on MODIS land surface temperature data. The Soil Water Assessment Tool model, which includes an imp...

  19. Air Sensor Guidebook

    Science.gov (United States)

    This Air Sensor Guidebook has been developed by the U.S. EPA to assist those interested in potentially using lower cost air quality sensor technologies for air quality measurements. Its development was in direct response to a request for such a document following a recent scienti...

  20. Air Pollution Training Programs.

    Science.gov (United States)

    Public Health Service (DHEW), Rockville, MD.

    This catalog lists the universities, both supported and not supported by the Division of Air Pollution, which offer graduate programs in the field of air pollution. The catalog briefly describes the programs and their entrance requirements, the requirements, qualifications and terms of special fellowships offered by the Division of Air Pollution.…

  1. Healthy Air at School

    Science.gov (United States)

    ... 2015 Bring the Fight for Air to your smartphone. Top Stories More about Healthy Air Unlocking the Asthma-Allergy Connection May 7, 2015 Every Breath You Take: State of the Air 2015 April 29, 2015 How Public Health Issues Affect Lung Health April 7, 2015 » ...

  2. Healthy Air at Work

    Science.gov (United States)

    ... 2015 Bring the Fight for Air to your smartphone. Top Stories More about Healthy Air Unlocking the Asthma-Allergy Connection May 7, 2015 Every Breath You Take: State of the Air 2015 April 29, 2015 How Public Health Issues Affect Lung Health April 7, 2015 » ...

  3. Healthy Air Outdoors

    Science.gov (United States)

    ... 2015 Bring the Fight for Air to your smartphone. Top Stories More about Healthy Air Unlocking the Asthma-Allergy Connection May 7, 2015 Every Breath You Take: State of the Air 2015 April 29, 2015 How Public Health Issues Affect Lung Health April 7, 2015 » ...

  4. Remote steering of laser beams by radar- and laser-induced refractive-index gradients in the atmosphere

    International Nuclear Information System (INIS)

    Refractive-index gradients induced in the atmospheric air by properly tailored laser and microwave fields are shown to enable a remote steering of laser beams. Heating-assisted modulation of the refractive index of the air by microwave radiation is shown to support small-angle laser-beam bending with bending angles on the order of 10-2. Ionization of the atmospheric air by dyads of femto- and nanosecond laser pulses, on the other hand, can provide beam deflection angles in excess of ?/5, offering an attractive strategy for radiation transfer, free-space communications, and laser-based standoff detection

  5. Energy Index For Aircraft Maneuvers

    Science.gov (United States)

    Chidester, Thomas R. (Inventor); Lynch, Robert E. (Inventor); Lawrence, Robert E. (Inventor); Amidan, Brett G. (Inventor); Ferryman, Thomas A. (Inventor); Drew, Douglas A. (Inventor); Ainsworth, Robert J. (Inventor); Prothero, Gary L. (Inventor); Romanowski, Tomothy P. (Inventor); Bloch, Laurent (Inventor)

    2006-01-01

    Method and system for analyzing, separately or in combination, kinetic energy and potential energy and/or their time derivatives, measured or estimated or computed, for an aircraft in approach phase or in takeoff phase, to determine if the aircraft is or will be put in an anomalous configuration in order to join a stable approach path or takeoff path. A 3 reference value of kinetic energy andor potential energy (or time derivatives thereof) is provided, and a comparison index .for the estimated energy and reference energy is computed and compared with a normal range of index values for a corresponding aircraft maneuver. If the computed energy index lies outside the normal index range, this phase of the aircraft is identified as anomalous, non-normal or potentially unstable.

  6. Introduction to indexing and abstracting

    CERN Document Server

    Cleveland, Ana

    2013-01-01

    Successful information access in the digital information age requires robust systems of indexing and abstracting. This book provides a complete introduction to the subject that covers the many recent changes in the field.

  7. A Zig-Zag Index

    CERN Document Server

    Agarwal, Prarit; Mariotti, Alberto

    2013-01-01

    We study the large N superconformal index of quiver gauge theories describing the worldvolume of D3 branes probing toric Calabi Yau singularities. The index has been previously noticed to factorize over the set of the extremal BPS mesonic operators of the gauge theory. We review this factorization and reformulate it in terms of zig-zag paths in the dimer model associated to the quiver. By using this reformulation, we argue that the factorization is valid not only for the exact R charge but for every set of R_{trial} respecting the marginality constraints. Moreover, we show the factorization of the index also in theories with orbifold singularities, previously not investigated. We conclude by providing an expression for the index in terms of the toric data of the dual geometry.

  8. Air quality and thermal comfort levels under extreme hot weather

    Science.gov (United States)

    Papanastasiou, D. K.; Melas, D.; Kambezidis, H. D.

    2015-01-01

    Meteorological (T and RH values) and air pollution data (PM10, NO2 and O3 concentrations) observed in Athens, Thessaloniki and Volos were analyzed to assess the air quality and the thermal comfort conditions and to study their synergy, when extreme hot weather prevailed in Greece during the period 2001-2010. The identification of a heat wave day was based on the suggestion made by the IPCC to define an extreme weather event. According to it, a heat wave day is detected when the daily maximum hourly temperature value exceeds its 90th percentile. This temperature criterion was applied to the data recorded at the cities center. Air quality was assessed at three sites in Athens (city center, near the city center, suburb), at two sites in Thessaloniki (city center, suburb) and at one site in Volos (city center), while thermal comfort conditions were assessed at the cities center. Mean pollution levels during the heat wave days and the non-heat wave days were calculated in order to examine the impact of the extreme hot weather on air quality. For this purpose, the distributions of the common air quality index and the exceedances of the air quality standards in force during the heat wave days and the non-heat wave days were also studied. Additionally, the variation of the daily maximum hourly value of Thom's discomfort index was studied in order to investigate the effect of extreme hot weather on people's thermal comfort. Moreover, the values of the common air quality index and Thom's discomfort index were comparatively assessed so as to investigate their synergy under extreme hot weather.

  9. Nonlinear Quality of Life Index

    OpenAIRE

    Zinovyev, A.; Gorban, A. N.

    2010-01-01

    We present details of the analysis of the nonlinear quality of life index for 171 countries. This index is based on four indicators: GDP per capita by Purchasing Power Parities, Life expectancy at birth, Infant mortality rate, and Tuberculosis incidence. We analyze the structure of the data in order to find the optimal and independent on expert's opinion way to map several numerical indicators from a multidimensional space onto the one-dimensional space of the quality of lif...

  10. Movie indexing via event detection

    OpenAIRE

    Lehane, Bart; O Connor, Noel E.

    2006-01-01

    The past number of years has seen a large increase in the number of movies, and therefore movie databases, created. As movies are typically quite long, locating relevant clips in these databases is quite difficult unless a well defined index is in place. As movies are creatively made, creating automatic indexing algorithms is a challenging task. However, there are a number of underlying film grammar principles that are universally followed. By detecting and examining the use of these principl...

  11. 1999 Bribe Payers Index (BPI)

    Science.gov (United States)

    Lambsdorff, Johann Graf.

    Transparency International has put together the Bribe Payers Perceptions Index (BPI), which ranks the leading nineteen exporting countries "in terms of the degree to which their corporations are perceived to be paying bribes abroad." According to the Bribe Payers Index (BPI), Sweden ranks the highest, followed by Australia and Canada, tying for second place. The United States comes in at seventh. This site links to the press release, background information, and framework document as well as the actual data.

  12. 13 CFR 102.9 - Public Index.

    Science.gov (United States)

    2010-01-01

    ... 2010-01-01 2010-01-01 false Public Index. 102.9 Section 102.9 Business Credit and... Disclosure of Information § 102.9 Public Index. (a) The Public Index is a document that provides identifying...

  13. 30 CFR 250.1401 - Index table.

    Science.gov (United States)

    2010-07-01

    ...2010-07-01 false Index table. 250.1401 Section 250...Penalties § 250.1401 Index table. The following table is an index of the sections in...notified of the Reviewing Officer's decision? § 250.1408 What are...

  14. Use of crop water stress index for monitoring water stress in some sinanthropic plant species

    OpenAIRE

    Ros?escu, Marinela Roxana; Chit?u, Emil

    2010-01-01

    The water stress indicator (crop water stress index, CWSI) is a measure of the transpiration rate of a plant, influenced by the leaf and air temperature difference from the plant’s vicinity and the air pressure deficit of the water vapors from the atmosphere. The experiments were realized in July-August 2008 and 2009 for six species in the cities Pitesti, Mioveni and Maracineni: Cichorium intybus L., Conyza canadensis (L.) Cronq., Erigeron annuus L. (Pers.), Lactuca serriola Torn., Polygonu...

  15. Microbes in indoor air

    Energy Technology Data Exchange (ETDEWEB)

    Viitanen, H.; Haikara, A.

    1988-01-01

    The level of fungal spores and bacteria in indoor air varies widely with the season, the outdoor air, humidity, movement in rooms, air filtration, ventilation equipment and moisture and rot damage. In different studies of indoor air, the levels of bacteria were 10-5000 CFU/m/sup 3/ and the levels of moulds 10-6000 CFU/m/sup 3/. The air tightness of buildings had no effect on the level of microbes. Moisture and rot damage in buildings is mainly caused by water leakages, construction defects and insufficient ventilation.

  16. Trajectory Indexing Using Movement Constraints

    DEFF Research Database (Denmark)

    Pfoser, D.; Jensen, Christian SØndergaard

    2005-01-01

    With the proliferation of mobile computing, the ability to index efficiently the movements of mobile objects becomes important. Objects are typically seen as moving in two-dimensional (x,y) space, which means that their movements across time may be embedded in the three-dimensional (x,y,t) space. Further, the movements are typically represented as trajectories, sequences of connected line segments. In certain cases, movement is restricted; specifically, in this paper, we aim at exploiting that movements occur in transportation networks to reduce the dimensionality of the data. Briefly, the idea is to reduce movements to occur in one spatial dimension. As a consequence, the movement occurs in two-dimensional (x,t) space. The advantages of considering such lower-dimensional trajectories are that the overall size of the data is reduced and that lower-dimensional data is to be indexed. Since off-the-shelf database management systems typically do not offer higher-dimensional indexing, this reduction in dimensionality allows us to use existing DBMSes to store and index trajectories. Moreover, we argue that, given the right circumstances, indexing these dimensionality-reduced trajectories can be more efficient than using a three-dimensional index. A decisive factor here is the fractal dimension of the network.the lower, the more efficient is the proposed approach. This hypothesis is verified by an experimental study that incorporates trajectories stemming from real and synthetic road networks. Udgivelsesdato: JUN

  17. Indexing from thesauri to the semantic web

    CERN Document Server

    de Keyser, Piet

    2012-01-01

    Indexing consists of both novel and more traditional techniques. Cutting-edge indexing techniques, such as automatic indexing, ontologies, and topic maps, were developed independently of older techniques such as thesauri, but it is now recognized that these older methods also hold expertise. Indexing describes various traditional and novel indexing techniques, giving information professionals and students of library and information sciences a broad and comprehensible introduction to indexing. This title consists of twelve chapters: an Introduction to subject readings and theasauri; Automatic i

  18. Indexes to Nuclear Regulatory Commission Issuances

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    Digests and indexes for issuances of the Commission (CLI), the Atomic Safety and licensing Board Panel (LBP), the Administrative Law Judges (ALJ) the Directors` Decisions (DD), and the Decisions on Petitions for Rulemaking (DPRM) are presented in this document. These digests and indexes are intended to serve as a guide to the issuances. Information elements are displayed in one or more of five separate formats arranged as follows: Case Name Index; Headers and Digests; Legal Citations Index; Subject Index; and Facility Index.

  19. Restoran Buenos Aires = Restaurant Buenos Aires

    Index Scriptorium Estoniae

    2008-01-01

    Restorani Buenos Aires (Narva mnt. 5, Tallinn) sisekujundusest. Sisearhitektid: Janno Roos ja Andres Labi (Ruumilabor OÜ). Laudu eraldavad 400 vardasse aetud puukuuli. Sisearhitektidest, nende tähtsamad tööd. I-III korruse plaan, 12 värv. vaadet, fotod sisearhitektidest

  20. Health Effects of Air Pollution

    Science.gov (United States)

    ... Health effects of air pollution Health effects of air pollution Breathing air that is not clean can hurt ... important to know about the health effects that air pollution can have on you and others. Once you ...