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Sample records for a-150 tissue equivalent

  1. Anti W comparisons for A150 plastic-equivalent gases, TE gas, and air

    SciTech Connect

    Pearson, D.W.; DeLuca, P.M. Jr.; Schell, M.C.; Attix, F.H.; Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

    1981-01-01

    As part of our continuing evaluation of A150 plastic equivalent gases for neutron dosimetry, we have measured ionization ratios which are related to anti W ratios between gases in the p(66)Be(49) neutron beam at Fermilab. Additionally we have extended our earlier measurements (DeLuca, et al., 1980) at the UW gas target /sup 3/H(d,n)/sup 4/He neutron source to include an uncollimated beam geometry with ion chambers close to the target. Observed differences from the earlier results can probably be explained on the basis of neutron spectra, which await further determination.

  2. Comparison of plastics used in tissue equivalent proportional counters (TEPC) and development of a balloon borne TEPC

    NASA Astrophysics Data System (ADS)

    Collums, Tyler L.

    This study investigates alternatives to A-150 tissue equivalent plastic for use in the construction of tissue equivalent gas-filled detectors for the measurement of dosimetric quantities. This study looks at four different alternative plastics: acrylic, Nylon, polyethylene, and polystyrene. These alternative materials are more readily available and easier to machine than A-150 tissue equivalent plastic. In this study they are compared to A-150 tissue equivalent plastic to determine how they compare in the measurement of lineal energy spectra from energetic protons and heavy ions as found in the space radiation environment, as well as at relevant clinical energies used in proton and heavy ion therapy. In experiments carried out at the ProCure proton therapy center in Oklahoma City, five proportional counters possessing ionization cavities constructed of five different materials (A-150 tissue equivalent plastic, acrylic, Nylon, polyethylene, and polystyrene) were used to measure the lineal energy spectra of energetic proton beams of 87 MeV, 162 MeV, and 222 MeV. Exposures to energetic heavy ions were carried out at HIMAC in Japan using beams of 143 MeV/amu He, 265 MeV/amu C, 440 MeV/amu Si, 430 MeV/amu Ar, and 421 MeV/amu Fe. Monte Carlo simulations using FLUKA were also done for each detector for each proton beam and each heavy ion beam. Comparison of the measured data obtained at ProCure and HIMAC, as well as simulation results using the Monte Carlo code FLUKA, indicate that the responses of the four alternative plastics tested are very similar to the response of A-150 tissue equivalent plastic. FLUKA simulations done for a detector made of ICRU muscle are also shown to have a response similar to that of all five plastics. A flight version of the TEPCs has also been developed for a high altitude flight on a balloon or other vehicle.

  3. Response of a tissue equivalent proportional counter to neutrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Robbins, D. E.; Gibbons, F.; Braby, L. A.

    2002-01-01

    The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. c2002 Elsevier Science Ltd. All rights reserved.

  4. A study of a tissue equivalent gelatine based tissue substitute

    SciTech Connect

    Spence, J.L.

    1992-11-01

    A study of several tissue substitutes for use as volumetric dosimeters was performed. The tissue substitutes studied included tissue substitutes from previous studies and from ICRU 44. The substitutes were evaluated for an overall match to Reference Man which was used as a basis for this study. The evaluation was based on the electron stopping power, the mass attenuation coefficient, the electron density, and the specific gravity. The tissue substitute chosen also had to be capable of changing from a liquid into a solid form to maintain an even distribution of thermoluminesent dosimetry (TLD) powder and then back to a liquid for recovery of the TLD powder without adversely effecting the TLD powder. The gelatine mixture provided the closest match to the data from Reference Man tissue. The gelatine mixture was put through a series of test to determine it's usefulness as a reliable tissue substitute. The TLD powder was cast in the gelatine mixture and recovered to determine if the TLD powder was adversely effected. The distribution of the TLD powder after being cast into the gelatin mixture was tested in insure an even was maintained.

  5. A study of a tissue equivalent gelatine based tissue substitute

    SciTech Connect

    Spence, J.L.

    1992-11-01

    A study of several tissue substitutes for use as volumetric dosimeters was performed. The tissue substitutes studied included tissue substitutes from previous studies and from ICRU 44. The substitutes were evaluated for an overall match to Reference Man which was used as a basis for this study. The evaluation was based on the electron stopping power, the mass attenuation coefficient, the electron density, and the specific gravity. The tissue substitute chosen also had to be capable of changing from a liquid into a solid form to maintain an even distribution of thermoluminesent dosimetry (TLD) powder and then back to a liquid for recovery of the TLD powder without adversely effecting the TLD powder. The gelatine mixture provided the closest match to the data from Reference Man tissue. The gelatine mixture was put through a series of test to determine it`s usefulness as a reliable tissue substitute. The TLD powder was cast in the gelatine mixture and recovered to determine if the TLD powder was adversely effected. The distribution of the TLD powder after being cast into the gelatin mixture was tested in insure an even was maintained.

  6. Composition of MRI phantom equivalent to human tissues

    SciTech Connect

    Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Yoshida, Atsushi; Hanamoto, Katsumi; Kawasaki, Shoji; Shibuya, Koichi; Kanazawa, Susumu

    2005-10-15

    We previously developed two new MRI phantoms (called the CAG phantom and the CAGN phantom), with T1 and T2 relaxation times equivalent to those of any human tissue at 1.5 T. The conductivity of the CAGN phantom is equivalent to that of most types of human tissue in the frequency range of 1 to 130 MHz. In this paper, the relaxation times of human tissues are summarized, and the composition of the corresponding phantoms are provided in table form. The ingredients of these phantoms are carrageenan as the gelling agent, GdCl{sub 3} as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN{sub 3} as an antiseptic, and distilled water. The phantoms have T1 values of 202-1904 ms and T2 values of 38-423 ms when the concentrations of GdCl{sub 3} and agarose are varied from 0-140 {mu}mol/kg, and 0%-1.6%, respectively, and the CAGN phantom has a conductivity of 0.27-1.26 S/m when the NaCl concentration is varied from 0%-0.7%. These phantoms have sufficient strength to replicate a torso without the use of reinforcing agents, and can be cut by a knife into any shape. We anticipate the CAGN phantom to be highly useful and practical for MRI and hyperthermia-related research.

  7. Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

    NASA Astrophysics Data System (ADS)

    Bero, M. A.; Abukassem, I.

    2009-05-01

    Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

  8. Fricke Gel Dosimeter Tissue-Equivalence a Monte Carlo Study

    NASA Astrophysics Data System (ADS)

    Valente, M.; Bartesaghi, G.; Gambarini, G.; Brusa, D.; Castellano, G.; Carrara, M.

    2008-06-01

    Gel dosimetry has proved to be a valuable technique for absorbed dose distribution measurements in radiotherapy. FriXy-gel dosimeters consist of Fricke (ferrous sulphate) solution infused with xylenol orange. The solution is incorporated to a gel matrix in order to fix it to a solid structure allowing good spatial resolution and is imaged with a transportable optical system, measuring visible light transmittance before and after irradiation. This paper presents an evaluation of total photon mass attenuation coefficients at energies in the range of 50 keV-10MeV for the radiochromic FriXy gel dosimeter sensitive material. Mass attenuation coefficient estimations have been performed by means of Monte Carlo (PENELOPE) simulations. These calculations have been carried out for the FriXy gel sensitive material as well as for soft tissue (ICRU) and pure liquid water; a comparison of the obtained data shows good agreement between the different materials.

  9. Measurement of lineal-energy distributions for neutrons of 8 keV to 65 MeV by using a tissue-equivalent proportional counter.

    PubMed

    Nunomiya, T; Kim, E; Kurosaw, T; Taniguchi, S; Nakamura, T; Nakane, Y; Sakamoto, Y; Tanaka, S

    2002-01-01

    The lineal-energy spectra for monoenergetic and quasi-monoenergetic neutrons of 8 keV to 65 MeV were obtained using a tissue-equivalent proportional counter (TEPC). The frequency-mean lineal energy, the dose-average lineal energy and mean quality factor were estimated from the measured data. The neutron absorbed doses obtained with this TEPC were compared with the kerma coefticient for A-150 plastic defined by ICRP 26 and the mean quality factors were compared with the data of ICRP 74. respectively. These comparisons indicated good agreement between them.

  10. Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy

    PubMed Central

    Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S.

    2009-01-01

    Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient’s risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depth-dose equivalent curve should

  11. X-ray scattering from human breast tissues and breast-equivalent materials.

    PubMed

    Poletti, M E; Gonçalves, D; Mazzaro, I

    2002-01-07

    The angular distributions of photons scattered by human breast tissues (adipose and glandular) and by eight breast-equivalent materials (water, polymethylmethacrylate, nylon, polyethylene and four commercial breast-equivalent materials simulating different glandular-adipose proportions) have been measured at a photon energy of 17.44 keV (Kalpha-radiation of Mo). Transmission target geometry has been used with an acceptance of +/- 0.6 degrees and an uncertainty of approximately 7%. Experimental molecular form factors were extracted from diffraction patterns normalizing the number of scattered photons with theoretical data in regions where no structure is expected. Linear attenuation coefficients have been measured for all samples at this energy. The results for water, polymethylmethacrylate, nylon and adipose tissue agree with former reported data. The results for human breast tissues at low and medium scattering angle (1-25 degrees, corresponding to the momentum transfer region between 0.2 and 3 nm(-1)) differ from the breast-equivalent materials. The results for adipose tissue are similar to the corresponding values from commercial breast-equivalent materials while the results for glandular tissue are similar to those for water.

  12. Tissue-equivalent materials for construction of tomographic dosimetry phantoms in pediatric radiology.

    PubMed

    Jones, A K; Hintenlang, D E; Bolch, W E

    2003-08-01

    Tissue equivalent materials have a variety of uses, including routine quality assurance and quality control in both diagnostic and therapeutic physics. They are frequently used in a research capacity to measure doses delivered to patients undergoing various therapeutic procedures. However, very few tissue equivalent materials have been developed for research use at the low photon energies encountered in diagnostic radiology. In this paper, we present a series of tissue-equivalent (TE) materials designed to radiographically mimic human tissue at diagnostic photon energies. These tissue equivalent materials include STES-NB (newborn soft tissue substitute), BTES-NB (newborn bone tissue substitute), LTES (newborn as well as a child/adult lung tissue substitute), STES (child/adult soft tissue substitute), and BTES (child/adult bone tissue substitute). In all cases, targeted reference elemental compositions are taken from those specified in the ORNL stylized computational model series. For each material, reference values of mass density, mass attenuation coefficients (10-150 keV), and mass energy-absorption coefficients (10-150 keV) were matched as closely as permitted by material selection and manufacturing constraints. Values of mu/rho and mu(en)/rho for the newborn TE materials are noted to have maximum deviations from their ORNL reference values of from 0 to -3% and from +2% to -3%, respectively, over the diagnostic energy range 10-150 keV. For the child/adult TE materials, these same maximal deviations of mu/rho and mu(en)/rho are from +1.5% to -3% and from +3% to -3%, respectively. Simple calculations of x-ray fluence attenuation under narrow-beam geometry using a 66 kVp spectrum typical of newborn CR radiographs indicate that the tissue-equivalent materials presented here yield estimates of absorbed dose at depth to within 3.6% for STES-NB, 3.2% for BTES-NB, and 1.2% for LTES of the doses assigned to reference newborn soft, bone, and lung tissue, respectively.

  13. Characterization of a new tissue-engineered human skin equivalent with hair.

    PubMed

    Michel, M; L'Heureux, N; Pouliot, R; Xu, W; Auger, F A; Germain, L

    1999-06-01

    We designed a new tissue-engineered skin equivalent in which complete pilosebaceous units were integrated. This model was produced exclusively from human fibroblasts and keratinocytes and did not contain any synthetic material. Fibroblasts were cultured for 35 d with ascorbic acid and formed a thick fibrous sheet in the culture dish. The dermal equivalent was composed of stacked fibroblast sheets and exhibited some ultrastructural organization found in normal connective tissues. Keratinocytes seeded on this tissue formed a stratified and cornified epidermis and expressed typical markers of differentiation (keratin 10, filaggrin, and transglutaminase). After 4 wk of culture, a continuous and ultrastructurally organized basement membrane was observed and associated with the expression of laminin and collagen IV and VII. Complete pilosebaceous units were obtained by thermolysin digestion and inserted in this skin equivalent in order to assess the role of the transfollicular route in percutaneous absorption. The presence of hair follicles abolished the lag-time observed during hydrocortisone diffusion and increased significantly its rate of penetration in comparison to the control (skin equivalent with sham hair insertion). Therefore, this new hairy human skin equivalent model allowed an experimental design in which the only variable was the presence of pilosebaceous units and provided new data confirming the importance of hair follicles in percutaneous absorption.

  14. Polyurethane as a base for a family of tissue equivalent materials

    SciTech Connect

    Griffith, R.V.

    1980-01-01

    Polyurethane was used as a base material for a wide variety of tissue simulating applications. The technique in fabrication is similar to that of epoxy, however, the end products are generally more flexible for use in applications where flexibility is valuable. The material can be fabricated with relatively small laboratory equipment. The use of polyurethane provides the dosimetrist with the capability of making specific, accurate, on-the-spot tissue equivalent formulations to meet situations which require immediate calibration and response.

  15. TACI: a code for interactive analysis of neutron data produced by a tissue equivalent proportional counter

    SciTech Connect

    Cummings, F.M.

    1984-06-01

    The TEPC analysis code (TACI) is a computer program designed to analyze pulse height data generated by a tissue equivalent proportional counter (TEPC). It is written in HP BASIC and is for use on an HP-87XM personal computer. The theory of TEPC analysis upon which this code is based is summarized.

  16. Focused neutron beam dose deposition profiles in tissue equivalent materials: a pilot study for BNCT

    NASA Astrophysics Data System (ADS)

    Mayer, Rulon R.; Welsh, James; Chen-Mayer, Huaiyu H.

    1997-02-01

    Boron Neutron Capture Therapy (BNCT) has been limited by the inability to direct neutrons toward the therapeutic target and away from sensitive normal tissues. The recently developed Kumakhov lens has focused a broad incident low energy neutron beam in air to a sub-mm spot. This study examines the radiation does distribution of a converging beam passing through tissue equivalent materials. A neutron beam exiting a focusing lens is directed toward a stack of thin radiochromic media sandwiched between plastic sheets. The depth dose and beam profile within the tissue equivalent materials are determined by optical scanning and image processing of the individual radiochromic media sheets, a polymer based dosimetry medium which darkens upon exposure to ionizing radiation. The alpha particle emission from boron is examined by substituting a plastic sheet with a 6Li enriched lithium carbonate sheet positioned at the focal plane. The information will help determine the feasibility of applying the focused neutron beam to BNCT for therapy.

  17. Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

    NASA Astrophysics Data System (ADS)

    Albanese, Kathryn Elizabeth

    Scatter in medical imaging is typically cast off as image-related noise that detracts from meaningful diagnosis. It is therefore typically rejected or removed from medical images. However, it has been found that every material, including cancerous tissue, has a unique X-ray coherent scatter signature that can be used to identify the material or tissue. Such scatter-based tissue-identification provides the advantage of locating and identifying particular materials over conventional anatomical imaging through X-ray radiography. A coded aperture X-ray coherent scatter spectral imaging system has been developed in our group to classify different tissue types based on their unique scatter signatures. Previous experiments using our prototype have demonstrated that the depth-resolved coherent scatter spectral imaging system (CACSSI) can discriminate healthy and cancerous tissue present in the path of a non-destructive x-ray beam. A key to the successful optimization of CACSSI as a clinical imaging method is to obtain anatomically accurate phantoms of the human body. This thesis describes the development and fabrication of 3D printed anatomical scatter phantoms of the breast and lung. The purpose of this work is to accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Tissue-equivalent anatomical phantoms were designed to assess the capability of the CACSSI system to classify different types of breast tissue (adipose, fibroglandular, malignant). These phantoms were 3D printed based on DICOM data obtained from CT scans of prone breasts. The phantoms were tested through comparison of measured scatter signatures with those of adipose and fibroglandular tissue from literature. Tumors in the phantom were modeled using a variety of biological tissue including actual surgically excised benign and malignant tissue specimens. Lung based phantoms have also been printed for future

  18. Beam hardening correction for computed tomography images using a postreconstruction method and equivalent tissue concept.

    PubMed

    Chen, C Y; Chuang, K S; Wu, J; Lin, H R; Li, M J

    2001-06-01

    A postreconstruction method for correcting the beam-hardening artifacts in computed tomography (CT) images is proposed. This method does not require x-ray spectrum measurement. The authors assumed that a pixel in a CT image can be decomposed into equivalent tissue percentages, depending on its CT number. A scout view of the step wedges made of these equivalent tissues was performed to obtain a beam-hardening correction curve for each tissue. Projecting through the CT image from various angles generated simulated projection data and the total thickness of each tissue along the ray. The correction term was estimated using the tissue thickness traveled by the ray, and this term was then added to its corresponding projection data. A second reconstruction using the corrected projection data yielded a beam-hardening corrected image. The preliminary results show that this method reduces beam hardening artifacts by 14% for aluminum and increased the object contrast by 18% near the aluminum-water boundary. The variation in CT numbers at different locations were reduced, and the aluminum CT number also was restored.

  19. Positron range in tissue-equivalent materials: experimental microPET studies.

    PubMed

    Alva-Sánchez, H; Quintana-Bautista, C; Martínez-Dávalos, A; Ávila-Rodríguez, M A; Rodríguez-Villafuerte, M

    2016-09-07

    In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with (18)F, (13)N or (68)Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

  20. Accurate determination of the complex refractive index of solid tissue-equivalent phantom

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Ye, Qing; Deng, Zhichao; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2012-06-01

    Tissue-equivalent phantom is becoming widespread as a substitute in the biological field to verify optical theories, test measuring systems and study the tissue performances for varying boundary conditions, sample size and shape at a quantitative level. Compared with phantoms made with Intralipid solution, ink and other liquid substances, phantom in solid state is stable over time, reproducible, easy to handle and has been testified to be a suitable optical simulator in the visible and near-infrared region. We present accurate determination of the complex refractive index (RI) of a solid tissueequivalent phantom using extended derivative total reflection method (EDTRM). Scattering phantoms in solid state were measured for p-polarized and s-polarized incident light respectively. The reflectance curves of the sample as a function of incident angle were recorded. The real part of RI is directly determined by derivative of the reflectance curve, and the imaginary part is obtained from nonlinear fitting based on the Fresnel equation and Nelder-Mead simplex method. The EDTRM method is applicable for RI measurement of high scattering media such as biotissue, solid tissue-equivalent phantom and bulk material. The obtained RI information can be used in the study of tissue optics and biomedical field.

  1. Tissue-equivalent torso phantom for calibration of transuranic-nuclide counting facilities

    SciTech Connect

    Griffith, R.V.; Anderson, A.L.; Dean, P.N.; Fisher, J.C.; Sundbeck, C.W.

    1986-01-16

    Several tissue-equivalent human-torso phantoms have been constructed for the calibration of counting systems used for in-vivo measurement of transuranic radionuclides. The phantoms contain a simulated human rib cage (in some cases, real bone) and removable model organs, and they include tissue-equivalent chest plates that can be placed over the torso to simulate people with a wide range of statures. The organs included are the lungs, liver, and tracheobronchial lymph nodes. Polyurethane with varying concentrations of added calcium was used to simulate the linear photon-attenuation properties of various human tissues, including lean muscle, adipose-muscle mixtures, cartilage, and bone. Foamed polyurethane was used to simulate lung tissue. Organs have been loaded with highly pure /sup 238/Pu, /sup 239/Pu, /sup 241/Am, and other radionuclides of interest. The validity of the phantom as a calibration standard has been checked in separate intercomparison studies using human subjects whose lungs contained a plutonium simulant. The resulting phantom calibration factors generally compared to within +-20% of the average calibration factors obtained for the human subjects.

  2. Positron range in tissue-equivalent materials: experimental microPET studies

    NASA Astrophysics Data System (ADS)

    Alva-Sánchez, H.; Quintana-Bautista, C.; Martínez-Dávalos, A.; Ávila-Rodríguez, M. A.; Rodríguez-Villafuerte, M.

    2016-09-01

    In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with 18F, 13N or 68Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

  3. SU-E-T-329: Tissue-Equivalent Phantom Materials for Neutron Dosimetry in Proton Therapy

    SciTech Connect

    Halg, R; Lomax, A; Clarke, S; Wieger, B; Pryser, E; Arghal, R; Pozzi, S; Bashkirov, V; Schulte, R; Schneider, U

    2014-06-01

    Purpose: To characterize tissue equivalence of phantom materials in terms of secondary neutron production and dose deposition from neutrons produced in radiation therapy phantom materials in the context of proton therapy using Monte Carlo simulations and measurements. Methods: In order to study the influence of material choice on neutron production in therapeutic proton beams, Monte Carlo simulations using the Geant4 and MCNPX-PoliMi transport codes were performed to generate the neutron fields produced by protons of 155 and 200 MeV. A simple irradiation geometry was used to investigate the effect of different materials. The proton beams were stopped in slab phantoms to study the production of secondary neutrons. The investigated materials were water, Lucite, and tissue-equivalent phantom materials (CIRS Inc., Norfolk, VA). Neutron energy spectra and absorbed dose by neutrons and their secondary particles were scored. In addition, simulations were performed for reference tissues (ICRP/ICRU) to assess tissue equivalence with respect to neutron generation and transport. In order to benchmark the simulation results, measurements were performed with a system developed at the University of Michigan; organic liquid scintillators were used to detect the neutron emissions from the irradiation of tissue-equivalent materials. Additionally, the MPPost code was used to calculate the scintillator response from the MCNPX-PoliMi output. Results: The simulated energy spectra and depth dose curves of the neutrons produced in different phantom materials showed similar shape. The differences of spectra and fluences between all studied materials and reference tissues were well within the achievable precision of neutron dosimetry. The shape of the simulated detector response of the liquid scintillators agreed well with measurements on the proton beamline. Conclusion: Based on Geant4 and MCNPX-PoliMi simulations, the investigated materials appear to be suitable to study the production

  4. Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Romano, F.; D'Urso, D.; Licciardello, T.; Agodi, C.; Candiano, G.; Cappuzzello, F.; Cirrone, G. A. P.; Cuttone, G.; Musumarra, A.; Pandola, L.; Scuderi, V.

    2014-12-01

    When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned. Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u-1 12C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

  5. Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy.

    PubMed

    De Napoli, M; Romano, F; D'Urso, D; Licciardello, T; Agodi, C; Candiano, G; Cappuzzello, F; Cirrone, G A P; Cuttone, G; Musumarra, A; Pandola, L; Scuderi, V

    2014-12-21

    When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned.Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u(-1) (12)C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

  6. Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

    PubMed

    Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

    2015-10-01

    Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

  7. Sex-specific tissue weighting factors for effective dose equivalent calculations

    SciTech Connect

    Xu, X.G.; Reece, W.D.

    1996-01-01

    The effective dose equivalent was defined in the International Commission on Radiological Protection Publication 26 in 1977 and later adopted by the U.S. Nuclear REgulatory Commission. To calculate organ doses and effective dose equivalent for external exposures using Monte Carlo simulations, sex-specific anthropomorphic phantoms and sex-specific weighting factors are always employed. This paper presents detailed mathematical derivation of a set of sex-specific tissue weighting factors and the conditions which the weighting factors must satisfy. Results of effective dose equivalent calculations using female and male phantoms exposed to monoenergetic photon beams of 0.08, 0.3, and 1.0 MeV are provided and compared with results published by other authors using different sex-specific weighting factors and phantoms. The results indicate that females always receive higher effective dose equivalent than males for the photon energies and geometries considered and that some published data may be wrong due to mistakes in deriving the sex-specific weighting factors. 17 refs., 2 figs., 2 tabs.

  8. Shielding experiment of heavy-ion produced neutrons using a tissue-equivalent proportional counter.

    PubMed

    Nunomiya, T; Yonai, S; Takada, M; Fukumura, A; Nakamura, T

    2003-01-01

    A shielding experiment was performed at the HIMAC (Heavy Ion Medical Accelerator in Chiba), of National Institute of Radiological Sciences (NIRS), to measure neutron dose using a spherical TEPC (tissue-equivalent proportional counter) of 12.55 cm inner diameter. Neutrons are produced from a 5 cm thick stopping length Cu target bombarded by 400 MeV/nucleon C6+ ions and penetrate concrete or iron shields of various thicknesses at 0 degree to the beam direction. From this shielding experiment. y-distribution, mean lineal energy, absorbed dose, dose equivalent and mean-quality factor were obtained behind the shield as a function of shield thickness. The neutron dose attenuation lengths were also obtained as 126 g cm(-2) for concrete and 211 g cm(-2) for iron. The measured results were compared with the calculated results using the MARS Monte Carlo code.

  9. Improved MAGIC gel for higher sensitivity and elemental tissue equivalent 3D dosimetry

    SciTech Connect

    Zhu Xuping; Reese, Timothy G.; Crowley, Elizabeth M.; El Fakhri, Georges

    2010-01-15

    Purpose: Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements. Methods: Glucose and urea was added to the original MAGIC formulation to adjust the O/C ratio. The dose responses of the new formulations were tested with MRI transverse relaxation rate (R2) measurements. Results: The new ingredients improved not only the elemental composition but also the sensitivity of the MAGIC gel. The O/C ratios of our new gels agree with that of soft tissue within 1%. The slopes of dose response curves were 1.6-2.7 times larger with glucose. The melting point also increased by 5 deg. C. Further addition of urea resulted in a similar slope but with an increased intercept and a decreased melting point. Conclusions: Our improved MAGIC gel formulations have higher sensitivity and better elemental tissue equivalency for 3D dosimetry applications involving nuclear reactions.

  10. Analysis of biological tissues in infant chest for the development of an equivalent radiographic phantom

    SciTech Connect

    Pina, D. R.; Souza, Rafael T. F.; Duarte, Sergio B.; Alvarez, Matheus; Miranda, Jose R. A.

    2012-03-15

    Purpose: The main purpose of the present study was to determine the amounts of different tissues in the chest of the newborn patient (age {<=}1 year), with the aim of developing a homogeneous phantom chest equivalent. This type of phantom is indispensable in the development of optimization procedures for radiographic techniques, including dosimetric control, which is a crucial aspect of pediatric radiology. The authors present a systematic set of procedures, including a computational algorithm, to estimate the amounts of tissues and thicknesses of the corresponding simulator material plates used to construct the phantom. Methods: The Gaussian fit of computed tomographic (CT) analysis was applied to classify and quantify different biological tissues. The methodology is summarized with a computational algorithm, which was used to quantify tissues through automated CT analysis. The thicknesses of the equivalent homogeneous simulator material plates were determined to construct the phantom. Results: A total of 180 retrospective CT examinations with anterior-posterior diameter values ranging 8.5-13.0 cm were examined. The amounts of different tissues were evaluated. The results provided elements to construct a phantom to simulate the infant chest in the posterior-anterior or anterior-posterior (PA/AP) view. Conclusions: To our knowledge, this report represents the first demonstration of an infant chest phantom dedicated to the radiology of children younger than one year. This phantom is a key element in the development of clinical charts for optimizing radiographic technique in pediatric patients. Optimization procedures for nonstandard patients were reported previously [Pina et al., Phys. Med. Biol. 49, N215-N226 (2004) and Pina et al., Appl. Radiat. Isot. 67, 61-69 (2009)]. The constructed phantom represents a starting point to obtain radiologic protocols for the infant patient.

  11. Use of tissue equivalent proportional counters to characterize radiation quality on the space shuttle

    SciTech Connect

    Braby, L.A.; Conroy, T.J.; Elegy, D.C.; Brackenbush, L.W.

    1992-04-01

    Tissue equivalent proportional counters (TEPC) are essentially cavity ionization chambers operating at low pressure and with gas gain. A small, battery powered, TEPC spectrometer, which records lineal energy spectra at one minute intervals, has been used on several space shuttle missions. The data it has collected clearly show the South Atlantic anomaly and indicate a mean quality factor somewhat higher than expected. An improved type of instrument has been developed with sufficient memory to record spectra at 10 second intervals, and with increased resolution for low LET events. This type of instrument will be used on most future space shuttle flights and in some international experiments.

  12. Photoprotection by pistachio bioactives in a 3-dimensional human skin equivalent tissue model.

    PubMed

    Chen, C-Y Oliver; Smith, Avi; Liu, Yuntao; Du, Peng; Blumberg, Jeffrey B; Garlick, Jonathan

    2017-01-25

    Reactive oxygen species (ROS) generated during ultraviolet (UV) light exposure can induce skin damage and aging. Antioxidants can provide protection against oxidative injury to skin via "quenching" ROS. Using a validated 3-dimensional (3D) human skin equivalent (HSE) tissue model that closely mimics human skin, we examined whether pistachio antioxidants could protect HSE against UVA-induced damage. Lutein and γ-tocopherol are the predominant lipophilic antioxidants in pistachios; treatment with these compounds prior to UVA exposure protected against morphological changes to the epithelial and connective tissue compartments of HSE. Pistachio antioxidants preserved overall skin thickness and organization, as well as fibroblast morphology, in HSE exposed to UVA irradiation. However, this protection was not substantiated by the analysis of the proliferation of keratinocytes and apoptosis of fibroblasts. Additional studies are warranted to elucidate the basis of these discordant results and extend research into the potential role of pistachio bioactives promoting skin health.

  13. Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system

    NASA Astrophysics Data System (ADS)

    Petric, Martin Peter

    This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing field-by-field verification of IMRT plans. This work was motivated by an initial study comparing two IMRT treatment planning systems. The clinical functionality of BrainLAB's BrainSCAN and Varian's Helios IMRT treatment planning systems were compared in terms of implementation and commissioning, dose optimization, and plan assessment. Implementation and commissioning revealed differences in the beam data required to characterize the beam prior to use with the BrainSCAN system requiring higher resolution data compared to Helios. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. The dose optimization and plan assessment comparisons revealed that while both systems use considerably different optimization algorithms and user-control interfaces, they are both capable of producing substantially equivalent dose plans. The extensive use of dosimetric verification techniques in the IMRT treatment planning comparison study motivated the development and implementation of a novel IMRT dosimetric verification system. The system consists of a water-filled phantom with a tissue equivalent plastic scintillator sheet built into the top surface. Scintillation light is reflected by a plastic mirror within the phantom towards a viewing window where it is captured using a CCD camera. Optical photon spread is removed using a micro-louvre optical collimator and by deconvolving a glare kernel from the raw images. Characterization of this

  14. SINGLE ANODE TRIPLE GEM TISSUE EQUIVALENT PROPORTIONAL COUNTER AS THE BASIS FOR A PERSONAL NEUTRON DOSIMETER.

    PubMed

    Seydaliev, M; Dubeau, J; Ali, F

    2016-08-29

    This paper reports on a tissue-equivalent proportional counter (TEPC) based on a triple gas electron multiplier structure, with a single pad readout, as a basis for a personal neutron dosimeter. Its dosimetric response was studied using the (252)Cf neutron source at the Health Physics Generator Facility of the Canadian Nuclear Laboratories. Measured lineal energy spectra were found to be in agreement with numerical simulations performed with Monte Carlo N-Particle eXtended (MCNPX). Both simulations and measurements showed that the mean pathlength of secondary charged particles in the TEPC gas was best represented by the thickness of the drift region of the device. It was determined that the Cauchy Theorem, used to calculate the mean chord length in spherical and cylindrical TEPCs, overestimated the simulated mean chord length by nearly a factor of two. Important operational characteristics of the device were investigated, including gas gain, sensitivity and dosimetric response, as functions of tissue-equivalent gas pressure. This work demonstrates that the proposed design can serve as the basis for a personal neutron dosimeter device, which would satisfy the angular dosimetric response criteria of the personal dosimeter standard IEC61526.

  15. Measurement of the first Townsend ionization coefficient in a methane-based tissue-equivalent gas

    NASA Astrophysics Data System (ADS)

    Petri, A. R.; Gonçalves, J. A. C.; Mangiarotti, A.; Botelho, S.; Bueno, C. C.

    2017-03-01

    Tissue-equivalent gases (TEGs), often made of a hydrocarbon, nitrogen, and carbon dioxide, have been employed in microdosimetry for decades. However, data on the first Townsend ionization coefficient (α) in such mixtures are scarce, regardless of the chosen hydrocarbon. In this context, measurements of α in a methane-based tissue-equivalent gas (CH4 - 64.4%, CO2 - 32.4%, and N2 - 3.2%) were performed in a uniform field configuration for density-normalized electric fields (E/N) up to 290 Td. The setup adopted in our previous works was improved for operating at low pressures. The modifications introduced in the apparatus and the experimental technique were validated by comparing our results of the first Townsend ionization coefficient in nitrogen, carbon dioxide, and methane with those from the literature and Magboltz simulations. The behavior of α in the methane-based TEG was consistent with that observed for pure methane. All the experimental results are included in tabular form in the Supplementary material.

  16. The response of tissue-equivalent proportional counters to heavy ions

    NASA Technical Reports Server (NTRS)

    Nikjoo, Hooshang; Khvostunov, Igor K.; Cucinotta, Francis A.

    2002-01-01

    The paper presents a theoretical model for the response of a tissue-equivalent proportional counter (TEPC) irradiated with charged particles. Heavy ions and iron ions in particular constitute a significant part of radiation in space. TEPCs are used for all space shuttle and International Space Station (ISS) missions to estimate the dose and radiation quality (in terms of lineal energy) inside spacecraft. The response of the tissue-equivalent proportional counters shows distortions at the wall/cavity interface. In this paper, we present microdosimetric investigation using Monte Carlo track structure calculations to simulate the response of a TEPC to charged particles of various LET (1 MeV protons, 2.4 MeV alpha particles, 46 MeV/nucleon 20Ne, 55 MeV/nucleon 20Ne, 45 MeV/nucleon 40Ar, and 1.05 GeV/nucleon 56Fe). Data are presented for energy lost and energy absorbed in the counter cavity and wall. The model calculations are in good agreement with the results of Rademacher et al. (Radiat. Res. 149, 387-389, 1998), including the study of the interface between the wall and the sensitive region of the counter. It is shown that the anomalous response observed at large event sizes in the experiment is due to an enhanced entry of secondary electrons from the wall into the gas cavity.

  17. Acrylonitrile Butadiene Styrene (ABS) plastic based low cost tissue equivalent phantom for verification dosimetry in IMRT.

    PubMed

    Kumar, Rajesh; Sharma, S D; Deshpande, Sudesh; Ghadi, Yogesh; Shaiju, V S; Amols, H I; Mayya, Y S

    2009-12-17

    A novel IMRT phantom was designed and fabricated using Acrylonitrile Butadiene Styrene (ABS) plastic. Physical properties of ABS plastic related to radiation interaction and dosimetry were compared with commonly available phantom materials for dose measurements in radiotherapy. The ABS IMRT phantom has provisions to hold various types of detectors such as ion chambers, radiographic/radiochromic films, TLDs, MOSFETs, and gel dosimeters. The measurements related to pre-treatment dose verification in IMRT of carcinoma prostate were carried out using ABS and Scanditronics-Wellhoffer RW3 IMRT phantoms for five different cases. Point dose data were acquired using ionization chamber and TLD discs while Gafchromic EBT and radiographic EDR2 films were used for generating 2-D dose distributions. Treatment planning system (TPS) calculated and measured doses in ABS plastic and RW3 IMRT phantom were in agreement within +/-2%. The dose values at a point in a given patient acquired using ABS and RW3 phantoms were found comparable within 1%. Fluence maps and dose distributions of these patients generated by TPS and measured in ABS IMRT phantom were also found comparable both numerically and spatially. This study indicates that ABS plastic IMRT phantom is a tissue equivalent phantom and dosimetrically it is similar to solid/plastic water IMRT phantoms. Though this material is demonstrated for IMRT dose verification but it can be used as a tissue equivalent phantom material for other dosimetry purposes in radiotherapy.

  18. SU-E-T-388: Evaluation of Electronic Brachytherapy Dose Distributions in Tissue Equivalent Materials

    SciTech Connect

    Johnson, M; Ahmad, S; Johnson, D

    2015-06-15

    Purpose: To study the measured and calculated dose distributions for electronic brachytherapy (EBT) in various tissue equivalent homogenous materials. Methods: Calculated dose distributions in water were generated using published TG-43 parameters in Varian BrachyVision software for a 50 kVp, 50 cm Xoft source. Dose distributions were measured within a 3D-scanning tank using dosimeters including: PTW 0.125 cc, pin-point, and parallel-plate ion chambers, Sun Nuclear “Edge” diode and Gafchromic EBT3 film. Multi-channel film dosimetry was used in film analysis. EBT3 film curves were calibrated via radial dose comparison to both independently measured and published data. The resulting film calibration was utilized to measure dose distributions created by titanium filtered source utilized in clinical brachytherapy applications. Data was collected within homogenous PMMA, vinyl, polystyrene, paraffin, and water-equivalent plastic phantoms. Results: Ion-chamber data was corrected to effective points of measurement and normalized prior to comparison between calculated and measured dose distributions. Measurements made in water and water equivalent materials compared well with results from treatment planning software. The maximum percent differences (relative to water) observed between 1 cm and 3.5 cm depth from source for each of the phantom materials are as follows: PMMA 35%, polystyrene 41%, plastic-water 23%, vinyl 115%, and paraffin 46%. Conclusion: The increased probability of photoelectric interactions occurring within the patient during electronic brachytherapy will emphasize the radiological differences between varying human tissues in dose deposition. These differences can Result in clinically significant dose perturbations and it is therefore recommended to move to a model based dose calculation, as outlined in TG-186, to improve the dosimetric accuracy of low energy EBT.

  19. Miniature Tissue Equivalent Proportional Counter dosimeter for active personal radiation monitoring of astronauts

    NASA Astrophysics Data System (ADS)

    Watson Huber, Aubrey

    The accurate measurement of spaceflight crew radiation exposure is of utmost importance. If onboard instrumentation shows that the pre-determined limit for radiation exposure has been met or exceeded during a mission, that mission can be greatly affected by the implementation of precautionary measures, or, in more extreme cases, the crew's health being negatively affected. Large active regional monitors determine real-time radiation risks of the crew during spaceflight, while small passive personal badges detect individual astronaut total exposure levels upon their return to Earth. At present, there are no personal active radiation dosimeters that can assess the continuous radiation risk to individual astronauts during spaceflight. Personal active radiation devices would be ideal for current operations in low-Earth orbit (LEO), as well as upcoming extravehicular activities on the Moon, Mars, or other planetary bodies. This project focused on the miniaturization of the Tissue Equivalent Proportional Counters (TEPCs) presently being utilized on the International Space Station (ISS) and Space Shuttle, enabling them to become personal crew dosimeters. The miniaturized TEPC prototype design has dimensions of 7.6 x 10.1 x 2.54 cm (3 x 4 x 1 in). It is composed of a 3 x 4 array of 1.27 cm (0.5 in) spherical detectors for measurements equivalent to a 4.39 cm (1.73 in) spherical detector, with an additional standalone sphere of diameter 1.27 cm (0.5 in) for taking measurements in high-flux environments. The detector simulates a tissue-equivalent diameter of 2 microns, is sensitive to lineal energies of 0.3 -- 1000 keV/micron, and can measure charged particles and neutrons ranging from 0.01 -- 100 mGy/hr.

  20. Interpretation and use of electrical equivalent circuits in studies of epithelial tissues.

    PubMed

    Helman, S I; Thompson, S M

    1982-12-01

    Whereas transepithelial and intracellular voltages continue to be measured in renal and other epithelial tissues, the origins of these voltages, especially in renal epithelia, remain obscure. Because epithelial tissues have multiple transcellular and extracellular routes of ion transport, it is convenient to model them with electrical equivalent circuits and, in this way, attempt to understand the relative importance of and relationships between the parallel-series arrangements of the membranes and barriers involved. The interpretation of the equivalent electromotive forces and resistances can be complicated, however, by virtue of nonlinear current-voltage relationships of ionic channels. Thus, for ion transport pathways displaying nonlinear I-V relationships, it is important to distinguish between chord and slope formalisms in the use and interpretation of electrophysiological data. For ions like Na that are generally not at electrochemical equilibrium, the Thévenin electromotive force (emf) of the slope formalism is not synonymous with the Nernst equilibrium potential of the chord formalism nor are the slope and chord conductances equal or constant at all voltages. Thus, it is mandatory that the empirical data be calculated and interpreted in a way consistent with the formalism adopted. The existence of nonlinear behavior, characterized by either Goldman or other types of rectification, exacerbates determination of relative ionic permeabilities, fractional resistances, transference numbers, and other electrophysiological parameters for simple membranes and especially for epithelia. It is argued that the use and interpretation of electrical equivalent circuits of epithelia are not arbitrary but must take into account nonlinearities of the ionic current-voltage relationships and concentration and voltage dependencies of the emfs and conductances.

  1. Effects of selected materials and geometries on the beta dose equivalent rate in a tissue equivalent phantom immersed in infinite clouds of 133Xe.

    PubMed

    Piltingsrud, H V; Gels, G L

    1986-06-01

    Most calculations of dose equivalent (D.E.) rates at 70-micron tissue depths in tissue equivalent (T.E.) phantoms from infinite clouds (radius exceeds maximum beta range in air) of 133Xe do not consider the possible effects of clothing overlays. Consequently, a series of measurements were made using a 1-mm-thick plastic scintillation detector assembly mounted in a tissue equivalent (T.E.) phantom with an overlay of 70 micron of T.E. material. This assembly was placed in an infinite cloud containing a known concentration of 133Xe. Material samples were placed at selected distances from the detector phantom, both individually and in various combinations. Pulse-height spectra resulting from beta radiations were converted to relative D.E. rates at a 70-micron tissue depth. The relative D.E. rates were reduced from values with no clothing cover by as little as 45% when placing a single thin nylon cloth 1 cm from the phantom, to 94% for a T-shirt material plus wool material plus denim placed 1/2, 1 and 3 cm, respectively, from the phantom. The results indicate that even loosely fitting clothing can have an important effect on reducing the D.E. rate. Close-fitting clothing appears to provide better protection.

  2. Stability of A-150 plastic ionization chamber response over a ~30 year period

    SciTech Connect

    Kroc, Thomas K.; Lennox, Arlene J.; /Fermilab

    2007-08-01

    At the NIU Institute for Neutron Therapy at Fermilab, the clinical tissue-equivalent ionization chamber response is measured every treatment day using a cesium source that was configured to match readings obtained at the National Bureau of Standards. Daily measurements are performed in air using the air-to-tissue dose conversion factors given in AAPM Report no. 7. The measured exposure calibration factors have been tabulated and graphed as a function of time from 1978 to present. For A-150 plastic ionization chambers, these factors exhibit a sinusoidal variation with a period of approximately one year and amplitude of {+-} 1%. This variation, attributable to the hygroscopic nature of A-150 plastic, is correlated with the relative humidity of the facility, and is greater than the humidity corrections for gas described in the literature. Our data suggest that chamber calibration should be performed at least weekly to accommodate these variations.

  3. Multiscale Strain Analysis of Tissue Equivalents Using a Custom-Designed Biaxial Testing Device

    PubMed Central

    Bell, B.J.; Nauman, E.; Voytik-Harbin, S.L.

    2012-01-01

    Mechanical signals transferred between a cell and its extracellular matrix play an important role in regulating fundamental cell behavior. To further define the complex mechanical interactions between cells and matrix from a multiscale perspective, a biaxial testing device was designed and built. Finite element analysis was used to optimize the cruciform specimen geometry so that stresses within the central region were concentrated and homogenous while minimizing shear and grip effects. This system was used to apply an equibiaxial loading and unloading regimen to fibroblast-seeded tissue equivalents. Digital image correlation and spot tracking were used to calculate three-dimensional strains and associated strain transfer ratios at macro (construct), meso, matrix (collagen fibril), cell (mitochondria), and nuclear levels. At meso and matrix levels, strains in the 1- and 2-direction were statistically similar throughout the loading-unloading cycle. Interestingly, a significant amplification of cellular and nuclear strains was observed in the direction perpendicular to the cell axis. Findings indicate that strain transfer is dependent upon local anisotropies generated by the cell-matrix force balance. Such multiscale approaches to tissue mechanics will assist in advancement of modern biomechanical theories as well as development and optimization of preconditioning regimens for functional engineered tissue constructs. PMID:22455913

  4. Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

    NASA Astrophysics Data System (ADS)

    Conte, V.; Moro, D.; Grosswendt, B.; Colautti, P.

    2013-07-01

    Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/μm value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a 137Cs gamma source and a cylindrical TEPC equipped with a precision internal 244Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to 137Cesium sources, with an overall uncertainty of about 5%.

  5. Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

    SciTech Connect

    Conte, V.; Moro, D.; Colautti, P.; Grosswendt, B.

    2013-07-18

    Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/{mu}m value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a {sup 137}Cs gamma source and a cylindrical TEPC equipped with a precision internal {sup 244}Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to {sup 137}Cesium sources, with an overall uncertainty of about 5%.

  6. SU-E-T-424: Feasibility of 3D Printed Radiological Equivalent Customizable Tissue Like Materials

    SciTech Connect

    Johnson, D; Ferreira, C; Ahmad, S

    2015-06-15

    Purpose: To investigate the feasibility of 3D printing CT# specific radiological equivalent tissue like materials. Methods: A desktop 3D printer was utilized to create a series of 3 cm x 3 cm x 2 cm PLA plastic blocks of varying fill densities. The fill pattern was selected to be hexagonal (Figure 1). A series of blocks was filled with paraffin and compared to a series filled with air. The blocks were evaluated with a “GE Lightspeed” 16 slice CT scanner and average CT# of the centers of the materials was determined. The attenuation properties of the subsequent blocks were also evaluated through their isocentric irradiation via “TrueBeam” accelerator under six beam energies. Blocks were placed upon plastic-water slabs of 4 cm in thickness assuring electronic equilibrium and data was collected via Sun Nuclear “Edge” diode detector. Relative changes in dose were compared with those predicted by Varian “Eclipse” TPS. Results: The CT# of 3D printed blocks was found to be a controllable variable. The fill material was able to narrow the range of variability in each sample. The attenuation of the block tracked with the density of the total fill structure. Assigned CT values in the TPS were seen to fall within an expected range predicted by the CT scans of the 3D printed blocks. Conclusion: We have demonstrated that it is possible to 3D print materials of varying tissue equivalencies, and that these materials have radiological properties that are customizable and predictable.

  7. Prototype CMOS SSPM solar particle dosimeter with tissue-equivalent sensor

    NASA Astrophysics Data System (ADS)

    Stapels, C. J.; Johnson, E. B.; Mukhopadhyay, S.; Chapman, E. C.; Christian, J. F.; Benton, Eric

    2009-08-01

    A dosimeter-on-a-chip (DoseChip) comprised of a tissue-equivalent scintillator coupled to a solid-state photomultiplier (SSPM) built using CMOS (complementary metal-oxide semiconductor) technology represents an ideal technology for a space-worthy, real-time solar-particle monitor for astronauts. It provides a tissue-equivalent response to the relevant energies and types of radiation for Low-Earth Orbit (LEO) and interplanetary space flight to the moon or Mars. The DoseChip will complement the existing Crew Passive Dosimeters by providing real-time dosimetry and as an alarming monitor for solar particle events (SPEs).[1] A prototype of the DoseChip, comprised of a 3 x 3 x 3 mm3 cube of BC-430 plastic scintillator coupled to a 2000-pixel SSPM, has successfully demonstrated response to protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory and at the HIMAC facility in Japan. The dynamic range of the dose has been verified over four orders of magnitude for particles with LET ranging from 0.2 keV/μm to 200 keV/μm, which includes 1-GeV protons to 420-MeV/n Fe nuclei. To exploit the benefits of the CMOS SSPM, we have developed our first autonomous prototype using the DoseChip. An analog circuit is used to process the signals from the SSPM, and an on-board microprocessor is used to digitize and store the pulse height information. Power is distributed over the device from a single dual voltage supply through various regulators and boost converters to appropriate supply voltages to each of the components.

  8. MO-F-CAMPUS-I-03: Tissue Equivalent Material Phantom to Test and Optimize Coherent Scatter Imaging for Tumor Classification

    SciTech Connect

    Albanese, K; Morris, R; Lakshmanan, M; Greenberg, J; Kapadia, A

    2015-06-15

    Purpose: To accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Methods: A breast phantom has been designed to assess the capability of coded aperture coherent x-ray scatter imaging system to classify different types of breast tissue (adipose, fibroglandular, tumor). The tissue-equivalent phantom was modeled as a hollow plastic cylinder containing multiple cylindrical and spherical inserts that can be positioned, rearranged, or removed to model different breast geometries. Each enclosure can be filled with a tissue-equivalent material and excised human tumors. In this study, beef and lard, placed inside 2-mm diameter plastic Nalgene containers, were used as surrogates for fibroglandular and adipose tissue, respectively. The phantom was imaged at 125 kVp, 40 mA for 10 seconds each with a 1-mm pencil beam. The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor, or momentum transfer (q) spectrum of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: The tissue equivalent phantom was found to accurately model different types of breast tissue by qualitatively comparing our measured form factors to those of adipose and fibroglandular tissue from literature. Our imaging system has been able to define the location and composition of the various materials in the phantom. Conclusion: This work introduces a new tissue equivalent phantom for testing and optimization of our coherent scatter imaging system for material classification. In future studies, the phantom will enable the use of a variety of materials including excised human tissue specimens in evaluating and optimizing our imaging system using pencil- and fan-beam geometries. United States Department of Homeland Security Duke University

  9. Estimation of the effects of normal tissue sparing using equivalent uniform dose-based optimization

    PubMed Central

    Senthilkumar, K.; Maria Das, K. J.; Balasubramanian, K.; Deka, A. C.; Patil, B. R.

    2016-01-01

    In this study, we intend to estimate the effects of normal tissue sparing between intensity modulated radiotherapy (IMRT) treatment plans generated with and without a dose volume (DV)-based physical cost function using equivalent uniform dose (EUD). Twenty prostate cancer patients were retrospectively selected for this study. For each patient, two IMRT plans were generated (i) EUD-based optimization with a DV-based physical cost function to control inhomogeneity (EUDWith DV) and (ii) EUD-based optimization without a DV-based physical cost function to allow inhomogeneity (EUDWithout DV). The generated plans were prescribed a dose of 72 Gy in 36 fractions to planning target volume (PTV). Mean dose, D30%, and D5% were evaluated for all organ at risk (OAR). Normal tissue complication probability was also calculated for all OARs using BioSuite software. The average volume of PTV for all patients was 103.02 ± 27 cm3. The PTV mean dose for EUDWith DV plans was 73.67 ± 1.7 Gy, whereas for EUDWithout DV plans was 80.42 ± 2.7 Gy. It was found that PTV volume receiving dose more than 115% of prescription dose was negligible in EUDWith DV plans, whereas it was 28% in EUDWithout DV plans. In almost all dosimetric parameters evaluated, dose to OARs in EUDWith DV plans was higher than in EUDWithout DV plans. Allowing inhomogeneous dose (EUDWithout DV) inside the target would achieve better normal tissue sparing compared to homogenous dose distribution (EUDWith DV). Hence, this inhomogeneous dose could be intentionally dumped on the high-risk volume to achieve high local control. Therefore, it was concluded that EUD optimized plans offer added advantage of less OAR dose as well as selectively boosting dose to gross tumor volume. PMID:27217624

  10. Fabrication of injectable, cellular, anisotropic collagen tissue equivalents with modular fibrillar densities.

    PubMed

    Marelli, Benedetto; Ghezzi, Chiara E; James-Bhasin, Mark; Nazhat, Showan N

    2015-01-01

    Technological improvements in collagen gel fabrication are highly desirable as they may enable significant advances in the formation of tissue-equivalent biomaterials for regenerative medicine, three-dimensional (3D) in vitro tissue models, and injectable scaffolds for cell and drug delivery applications. Thus, strategies to modulate collagen gel fibrillar density and organization in the mesostructure have been pursued to fabricate collagenous matrices with extracellular matrix-like features. Herein, we introduce a robust and simple method, namely gel aspiration-ejection (GAE), to engineer 3D, anisotropic, cell seeded, injectable dense collagen (I-DC) gels with controllable fibrillar densities, without the use of crosslinking. GAE allows for the hybridization of collagen gels with bioactive agents for increased functionality and supports highly aligned homogenous cell seeding, thus providing I-DC gels with distinct properties when compared to isotropic DC gels of random fibrillar orientation. The hybridization of I-DC with anionic fibroin derived polypeptides resulted in the nucleation of carbonated hydroxyapatite within the aligned nanofibrillar network upon exposure to simulated body fluid, yielding a 3D, anisotropic, mineralized collagen matrix. In addition, I-DC gels accelerated the osteoblastic differentiation of seeded murine mesenchymal stem cells (m-MSCs) when exposed to osteogenic supplements, which resulted in the cell-mediated, bulk mineralization of the osteoid-like gels. In addition, and upon exposure to neuronal transdifferentiation medium, I-DC gels supported and accelerated the differentiation of m-MSCs toward neuronal cells. In conclusion, collagen GAE presents interesting opportunities in a number of fields spanning tissue engineering and regenerative medicine to drug and cell delivery.

  11. Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions

    PubMed Central

    Straume, T.; Braby, L.A.; Borak, T.B.; Lusby, T.; Warner, D.W.; Perez-Nunez, D.

    2015-01-01

    Abstract Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with γ rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h−1. Measurements of for 200 MeV n−1 carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%. PMID:26313585

  12. Characterization of a Tissue-Equivalent Dosimeter based on CMOS Solid-State Photomultipliers

    NASA Astrophysics Data System (ADS)

    Johnson, Erik; Benton, Eric; Stapels, Christopher; Chrsitian, James; Jie Chen, Xiao

    Available digital dosimeters are bulky and unable to provide real-time monitoring of dose from space radiation. The complexity of space-flight design requires reliable, fault-tolerant equip-ment capable of providing real-time dosimetry during a mission, which is not feasible with the existing thermoluminescent dosimeter (TLD) technology, especially during extravehicular activity (EVA). Real-time monitoring is important for low-Earth orbiting spacecraft and inter-planetary space flight to alert the crew when Solar Particle Events (SPE) increase the particle flux of the spacecraft environment. A dosimeter-on-a-chip for personal dosimetry is comprised of a tissue-equivalent scintillator coupled to a solid-state photomultiplier (SSPM) built using CMOS technology. The radiation sensitive component of the dosimeter is coupled to analog signal processing components and a microprocessor, which can maintain processing fidelity up to 5x105 events per second. The dynamic range of the dosimeter has been verified from 1-GeV protons (0.22 keV/µm in H20) to 420 MeV/n Fe (201.1 keV/µm in H20). The dosimeter confirmed doses to within 3

  13. Microdosimetry study of THOR BNCT beam using tissue equivalent proportional counter.

    PubMed

    Hsu, F Y; Hsiao, H W; Tung, C-J; Liu, H M; Chou, F I

    2009-07-01

    Boron neutron capture therapy (BNCT) is a cancer treatment modality using a nuclear reactor and a boron compound drug. In Taiwan, Tsing Hua open-pool reactor (THOR) has been modulated for the basic research of BNCT for years. A new BNCT beam port was built in 2004 and used to prepare the first clinical trial in the near future. This work reports the microdosimetry study of the THOR BNCT beam by means of the tissue equivalent proportional counter (TEPC). Two self-fabricated TEPCs (the boron-doped versus the boron-free counter wall) were introduced. These dual TEPCs were applied to measure the lineal energy distributions in air and water phantom irradiated by the THOR BNCT mixed radiation field. Dose contributions from component radiations of different linear energy transfers (LETs) were analyzed. Applying a lineal energy dependent biological weighting function, r(y), to the total and individual lineal energy distributions, the effective relative biological effectiveness (RBE), neutron RBE, photon RBE, and boron capture RBE (BNC RBE) were all determined at various depths of the water phantom. Minimum and maximum values of the effective RBE were 1.68 and 2.93, respectively. The maximum effective RBE occurred at 2cm depth in the phantom. The average neutron RBE, photon RBE, and BNC RBE values were 3.160+/-0.020, 1.018+/-0.001, and 1.570+/-0.270, respectively, for the THOR BNCT beam.

  14. Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.

    PubMed

    Straume, T; Braby, L A; Borak, T B; Lusby, T; Warner, D W; Perez-Nunez, D

    2015-10-01

    Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of yD (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with g rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h(-1). Measurements of yD for 200 MeV n(-1) carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%.

  15. Tissue Equivalent Proportional Counter Microdosimetry Measurements Utilized Aboard Aircraft and in Accelerator Based Space Radiation Shielding Studies

    NASA Technical Reports Server (NTRS)

    Gersey, Brad B.; Wilkins, Richard T.

    2010-01-01

    This slide presentation reviews the Tissue Equivalent Proportional Counter (TEPC), a description of the spatially restricted LET Model, high energy proton TEPC and the results of modeling, the study of shielding and the results from the flight exposures with the TEPC.

  16. Determination of tissue equivalent materials of a physical 8-year-old phantom for use in computed tomography

    NASA Astrophysics Data System (ADS)

    Akhlaghi, Parisa; Miri Hakimabad, Hashem; Rafat Motavalli, Laleh

    2015-07-01

    This paper reports on the methodology applied to select suitable tissue equivalent materials of an 8-year phantom for use in computed tomography (CT) examinations. To find the appropriate tissue substitutes, first physical properties (physical density, electronic density, effective atomic number, mass attenuation coefficient and CT number) of different materials were studied. Results showed that, the physical properties of water and polyurethane (as soft tissue), B-100 and polyvinyl chloride (PVC) (as bone) and polyurethane foam (as lung) agree more with those of original tissues. Then in the next step, the absorbed doses in the location of 25 thermoluminescent dosimeters (TLDs) as well as dose distribution in one slice of phantom were calculated for original and these proposed materials by Monte Carlo simulation at different tube voltages. The comparisons suggested that at tube voltages of 80 and 100 kVp using B-100 as bone, water as soft tissue and polyurethane foam as lung is suitable for dosimetric study in pediatric CT examinations. In addition, it was concluded that by considering just the mass attenuation coefficient of different materials, the appropriate tissue equivalent substitutes in each desired X-ray energy range could be found.

  17. A dosimetric evaluation of tissue equivalent phantom prepared using 270 Bloom gelatin for absorbed dose imaging in Gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Cavinato, C. C.; Rodrigues, O., Jr.; Cervantes, J. H.; Rabbani, S. R.; Campos, L. L.

    2009-05-01

    Tissue equivalent gel phantoms have been widely studied in radiation therapy for both relative and reference dosimetry. A Fricke xylenol gel (FXG) spherical phantom was evaluated by means of magnetic resonance image method (MRI) to measure absorbed dose distribution resulted from gamma knife irradiation. The FXG phantom was prepared using 270 Bloom gelatin. The gelatin is a tissue equivalent material, of easy preparation, can be used to mold phantoms into different shapes and volumes, is commercially available and inexpensive. The results show that the Fricke gel phantom prepared with 270 Bloom gelatin satisfy the requirements to be used for the quality control in stereotactic radiosurgery using Gamma Knife technique and may constitute one more option of dosimeter in radiation therapy applications.

  18. Dose equivalent near the bone-soft tissue interface from nuclear fragments produced by high-energy protons

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Poston, J. W.; Cucinotta, F. A.; Wilson, J. W.

    1996-01-01

    During manned space missions, high-energy nucleons of cosmic and solar origin collide with atomic nuclei of the human body and produce a broad linear energy transfer spectrum of secondary particles, called target fragments. These nuclear fragments are often more biologically harmful than the direct ionization of the incident nucleon. That these secondary particles increase tissue absorbed dose in regions adjacent to the bone-soft tissue interface was demonstrated in a previous publication. To assess radiological risks to tissue near the bone-soft tissue interface, a computer transport model for nuclear fragments produced by high energy nucleons was used in this study to calculate integral linear energy transfer spectra and dose equivalents resulting from nuclear collisions of 1-GeV protons transversing bone and red bone marrow. In terms of dose equivalent averaged over trabecular bone marrow, target fragments emitted from interactions in both tissues are predicted to be at least as important as the direct ionization of the primary protons-twice as important, if recently recommended radiation weighting factors and "worst-case" geometry are used. The use of conventional dosimetry (absorbed dose weighted by aa linear energy transfer-dependent quality factor) as an appropriate framework for predicting risk from low fluences of high-linear energy transfer target fragments is discussed.

  19. Calibration of a large hyperpure germanium array for in-vivo detection of the actinides with a tissue-equivalent torso phantom

    SciTech Connect

    Berger, C.D.; Lane, B.H.

    1983-01-01

    For calibration of the array for internally deposited /sup 238/Pu, /sup 239/Pu, and /sup 241/Am, a tissue-equivalent anthropomorphic phantom, was used for efficiency determinations at the ORNL facility. This phantom consists of a tissue-equivalent torso into which is imbedded an adult male skeleton, interchangeable organs containing a homogeneous distribution of various radionuclides, and two sets of chest overlay plates for simulation of progressively thicker tissue over the chest, as well as differing thoracic fat contents. (PSB)

  20. Equivalent of a cartilage tissue for simulations of laser-induced temperature fields

    SciTech Connect

    Kondyurin, A V; Sviridov, A P

    2008-07-31

    The thermal and optical properties of polyacrylamide hydrogels and cartilages are studied by the method of IR laser radiometry. The thermal diffusivity, heat capacity, and the effective absorption coefficient at a wavelength of 1.56 {mu}m measured for polyacrylamide gel with 70% water content and the degree of cross-linking 1:9 and for the nasal septum cartilage proved to be close. This allows the use of polyacrylamide hydrogels as equivalents of cartilages in simulations of laser-induced temperature fields. (biophotonics)

  1. 3D Functional Corneal Stromal Tissue Equivalent Based on Corneal Stromal Stem Cells and Multi-Layered Silk Film Architecture

    PubMed Central

    Marelli, Benedetto; Omenetto, Fiorenzo G.; Funderburgh, James L.; Kaplan, David L.

    2017-01-01

    The worldwide need for human cornea equivalents continues to grow. Few clinical options are limited to allogenic and synthetic material replacements. We hypothesized that tissue engineered human cornea systems based on mechanically robust, patterned, porous, thin, optically clear silk protein films, in combination with human corneal stromal stem cells (hCSSCs), would generate 3D functional corneal stroma tissue equivalents, in comparison to previously developed 2D approaches. Silk film contact guidance was used to control the alignment and distribution of hCSSCs on RGD-treated single porous silk films, which were then stacked in an orthogonally, multi-layered architecture and cultured for 9 weeks. These systems were compared similar systems generated with human corneal fibroblasts (hCFs). Both cell types were viable and preferentially aligned along the biomaterial patterns for up to 9 weeks in culture. H&E histological sections showed that the systems seeded with the hCSSCs displayed ECM production throughout the entire thickness of the constructs. In addition, the ECM proteins tested positive for keratocyte-specific tissue markers, including keratan sulfate, lumican, and keratocan. The quantification of hCSSC gene expression of keratocyte-tissue markers, including keratocan, lumican, human aldehyde dehydrogenase 3A1 (ALDH3A1), prostaglandin D2 synthase (PTDGS), and pyruvate dehydrogenase kinase, isozyme 4 (PDK4), within the 3D tissue systems demonstrated upregulation when compared to 2D single silk films and to the systems generated with the hCFs. Furthermore, the production of ECM from the hCSSC seeded systems and subsequent remodeling of the initial matrix significantly improved cohesiveness and mechanical performance of the constructs, while maintaining transparency after 9 weeks. PMID:28099503

  2. Design and realisation of tissue-equivalent dielectric simulators for dosimetric studies on microwave antennas for interstitial ablation.

    PubMed

    Lopresto, V; Pinto, R; Lodato, R; Lovisolo, G A; Cavagnaro, M

    2012-07-01

    Thermal ablation therapies, based on electromagnetic field sources (interstitial or intracavitary antennas) at radio and microwave frequencies, are increasingly used in medicine due to their proven efficacy in the treatment of many diseases (tumours, stenosis, etc). Such techniques need standardized procedures, still not completely consolidated, as to analyze the behaviour of antennas for treatment optimisation. Several tissue-equivalent dielectric simulators (also named phantoms) have been developed to represent human head tissues, and extensively used in the analysis of human exposure to the electromagnetic emissions from hand-held devices; yet, very few studies have considered other tissues, as those met in ablation therapies. The objective of this study was to develop phantoms of liver and kidney tissue to experimentally characterise interstitial microwave antennas in reference conditions. Phantom properties depend on the simulated target tissue (liver or kidney) and the considered frequency (2.45 GHz in this work), addressing the need for a transparent liquid to easily control the positioning of the probe with respect to the antenna under test. An experimental set-up was also developed and used to characterise microwave ablation antenna performances. Finally, a comparison between measurements and numerical simulations was performed for the cross-validation of the experimental set-up and the numerical model. The obtained results highlight the fundamental role played by dielectric simulators in the development of microwave ablation devices, representing the first step towards the definition of a procedure for the ablation treatment planning.

  3. Simultaneous optical coherence and multiphoton microscopy of skin-equivalent tissue models

    NASA Astrophysics Data System (ADS)

    Barton, Jennifer K.; Tang, Shuo; Lim, Ryan; Tromberg, Bruce J.

    2007-07-01

    Three-layer skin-equivalent models (rafts) were created consisting of a collagen/fibroblast layer and an air-exposed keratinocyte layer. Rafts were imaged with a tri-modality microscope including optical coherence (OC), two-photon excited fluorescence (TPEF), and second harmonic generation (SHG) channels. Some rafts were stained with Hoechst 33343 or rhodamine 123, and some were exposed to dimethyl sulfoxide (DMSO). OC microscopy revealed signal in cell cytoplasm and nuclear membranes, and a characteristic texture in the collagen/fibroblast layer. TPEF showed signal in cell cytoplasm and from collagen, and stained specimens revealed cell nuclei or mitochondria. There was little SHG in the keratinocyte layer, but strong signal from collagen bundles. Endogenous signals were severely attenuated in DMSO treated rafts; stained samples revealed shrunken and distorted cell structure. OC, TPEF, and SHG can provide complementary and non-destructive information about raft structure and effect of chemical agents.

  4. Factors limiting the linearity of response of tissue equivalent proportional counters used in micro- and nano-dosimetry

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2017-01-01

    Proportional counters filled with tissue equivalent gas mixtures are extremely useful instruments and are being used extensively as sensitive detectors for all types of radiations to measure the energy transferred to small tissue volumes. The linearity of their response is of primary importance. So the investigation and clarification of the physical phenomena taking place in the counter and of the limits within which useful results may be obtained would contribute to a more efficient use and a wider application of these counters. The linearity of response in the dose and in the gas gain has been determined. Linearity in the dose is limited by the total count rate effect, while linearity in the gas gain is limited by secondary processes occurring in the electron avalanche and by the self-induced space charge effect.

  5. Measurement and simulation of lineal energy distribution at the CERN high energy facility with a tissue equivalent proportional counter.

    PubMed

    Rollet, S; Autischer, M; Beck, P; Latocha, M

    2007-01-01

    The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

  6. Optical coherence tomography detection of shear wave propagation in inhomogeneous tissue equivalent phantoms and ex-vivo carotid artery samples.

    PubMed

    Razani, Marjan; Luk, Timothy W H; Mariampillai, Adrian; Siegler, Peter; Kiehl, Tim-Rasmus; Kolios, Michael C; Yang, Victor X D

    2014-03-01

    In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) in an inhomogeneous phantom and carotid artery samples based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs duration, applying acoustic radiation force (ARF) to inhomogeneous phantoms and carotid artery samples, synchronized with a swept-source OCT (SS-OCT) imaging system. The phantoms were composed of gelatin and titanium dioxide whereas the carotid artery samples were embedded in gel. Differential OCT phase maps, measured with and without the ARF, detected the microscopic displacement generated by shear wave propagation in these phantoms and samples of different stiffness. We present the technique for calculating tissue mechanical properties by propagating shear waves in inhomogeneous tissue equivalent phantoms and carotid artery samples using the ARF of an ultrasound transducer, and measuring the shear wave speed and its associated properties in the different layers with OCT phase maps. This method lays the foundation for future in-vitro and in-vivo studies of mechanical property measurements of biological tissues such as vascular tissues, where normal and pathological structures may exhibit significant contrast in the shear modulus.

  7. Nonlinear ultrasound propagation through layered liquid and tissue-equivalent media: computational and experimental results at high frequency.

    PubMed

    Williams, Ross; Cherin, Emmanuel; Lam, Toby Y J; Tavakkoli, Jahangir; Zemp, Roger J; Foster, F Stuart

    2006-11-21

    Nonlinear propagation has been demonstrated to have a significant impact on ultrasound imaging. An efficient computational algorithm is presented to simulate nonlinear ultrasound propagation through layered liquid and tissue-equivalent media. Results are compared with hydrophone measurements. This study was undertaken to investigate the role of nonlinear propagation in high frequency ultrasound micro-imaging. The acoustic field of a focused transducer (20 MHz centre frequency, f-number 2.5) was simulated for layered media consisting of water and tissue-mimicking phantom, for several wide-bandwidth source pulses. The simulation model accounted for the effects of diffraction, attenuation and nonlinearity, with transmission and refraction at layer boundaries. The parameter of nonlinearity, B/A, of the water and tissue-mimicking phantom were assumed to be 5.2 and 7.4, respectively. The experimentally measured phantom B/A value found using a finite-amplitude insert-substitution method was shown to be 7.4 +/- 0.6. Relative amounts of measured second and third harmonic pressures as a function of the fundamental pressures at the focus were in good agreement with simulations. Agreement within 3% was found between measurements and simulations of the beam widths of the fundamental and second harmonic signals following propagation through the tissue phantom. The results demonstrate significant nonlinear propagation effects for high frequency imaging beams.

  8. Feasibility of optical coherence elastography measurements of shear wave propagation in homogeneous tissue equivalent phantoms.

    PubMed

    Razani, Marjan; Mariampillai, Adrian; Sun, Cuiru; Luk, Timothy W H; Yang, Victor X D; Kolios, Michael C

    2012-05-01

    In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a 20 MHz piezoelectric transducer (circular element 8.5 mm diameter) transmitting sine-wave bursts of 400 μs, synchronized with the OCT swept source wavelength sweep. The acoustic radiation force (ARF) was applied to two gelatin phantoms (differing in gelatin concentration by weight, 8% vs. 14%). Differential OCT phase maps, measured with and without the ARF, demonstrate microscopic displacement generated by shear wave propagation in these phantoms of different stiffness. We present preliminary results of OCT derived shear wave propagation velocity and modulus, and compare these results to rheometer measurements. The results demonstrate the feasibility of shear wave OCE (SW-OCE) for high-resolution microscopic homogeneous tissue mechanical property characterization.

  9. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation.

    PubMed

    Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

    2013-09-07

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from (12)C (4.44 MeV) and (16)O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 10(7) oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from (16)O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring (16)O PG emission.

  10. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation

    PubMed Central

    Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

    2013-01-01

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from 12C (4.44 MeV) and 16O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 107 oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from 16O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring 16O PG emission. PMID:23920051

  11. Skin equivalent tissue-engineered construct: co-cultured fibroblasts/ keratinocytes on 3D matrices of sericin hope cocoons.

    PubMed

    Nayak, Sunita; Dey, Sancharika; Kundu, Subhas C

    2013-01-01

    The development of effective and alternative tissue-engineered skin replacements to autografts, allografts and xenografts has became a clinical requirement due to the problems related to source of donor tissue and the perceived risk of disease transmission. In the present study 3D tissue engineered construct of sericin is developed using co-culture of keratinocytes on the upper surface of the fabricated matrices and with fibroblasts on lower surface. Sericin is obtained from "Sericin Hope" silkworm of Bombyx mori mutant and is extracted from cocoons by autoclave. Porous sericin matrices are prepared by freeze dried method using genipin as crosslinker. The matrices are characterized biochemically and biophysically. The cell proliferation and viability of co-cultured fibroblasts and keratinocytes on matrices for at least 28 days are observed by live/dead assay, Alamar blue assay, and by dual fluorescent staining. The growth of the fibroblasts and keratinocytes in co-culture is correlated with the expression level of TGF-β, b-FGF and IL-8 in the cultured supernatants by enzyme-linked immunosorbent assay. The histological analysis further demonstrates a multi-layered stratified epidermal layer of uninhibited keratinocytes in co-cultured constructs. Presence of involucrin, collagen IV and the fibroblast surface protein in immuno-histochemical stained sections of co-cultured matrices indicates the significance of paracrine signaling between keratinocytes and fibroblasts in the expression of extracellular matrix protein for dermal repair. No significant amount of pro inflammatory cytokines (TNF-α, IL-1β and nitric oxide) production are evidenced when macrophages grown on the sericin matrices. The results all together depict the potentiality of sericin 3D matrices as skin equivalent tissue engineered construct in wound repair.

  12. SU-E-T-130: Dosimetric Evaluation of Tissue Equivalent Gel Dosimeter Using Saccharide in Radiotherapy System

    SciTech Connect

    Cho, Y; Lee, D; Jung, H; Ji, Y; Kim, K; Chang, U; Kwon, S

    2014-06-01

    Purpose: In this study, the dose responses of the MAGIC gel with various concentrations and type of saccharide are examined to clarify the roles of mono and disaccharide in the polymerization process. Then we focused on the tissue equivalence and dose sensitivity of MAGIC gel dosimeters. Methods: The gel is composed of HPLC, 8% gelatin, 2 × 10-3 M L-ascorbic acid, 1.8 × 10-2 M hydroquinone, 8 × 10-5 M copper(II)sulfate and 9% methacrylic acid, new polymer gels are synthesized by adding glucose(monosaccharide), sucrose(disaccharide) and urea in the concentration range of 5∼35%. For irradiation of the gel, cesium-137 gamma-ray irradiator was used, radiation dose was delivered from 5∼50 Gy. MRI images of the gel were acquired by using a 3.0 T MRI system. Results: When saccharide and urea were added, the O/C, O/N and C/N ratios agreed with those of soft tissue with 1.7%. The dose-response of glucose and sucrose gel have slope-to-intercept ratio of 0.044 and 0.283 respectively. The slope-to-ratio is one important determinant of gel sensitivity. R-square values of glucose and sucrose gel dosimeters were 0.984 and 0.994 respectively. Moreover when urea were added, the slope-to-intercept ratio is 0.044 and 0.073 respectively. R-square values of mono and disaccharide gel were 0.973 and 0.989 respectively. When a saccharide is added into the MAGIC gel dosimeter, dose sensitivity is increased. However when urea were added, dose sensitivity is slightly decreased. Conclusion: In this study, it was possible to obtain the following conclusions by looking at the dose response characteristics after adding mono-, di-saccharide and urea to a MAGIC gel dosimeter. Saccharide was a tendency of increasing dose sensitivity with disaccharide. Sa.ccharide is cost effective, safe, soft tissue equivalent, and can be used under various experimental conditions, making it a suitable dosimeter for some radiotherapy applications.

  13. Water and tissue equivalence of a new PRESAGE{sup Registered-Sign} formulation for 3D proton beam dosimetry: A Monte Carlo study

    SciTech Connect

    Gorjiara, Tina; Kuncic, Zdenka; Doran, Simon; Adamovics, John; Baldock, Clive

    2012-11-15

    Purpose: To evaluate the water and tissue equivalence of a new PRESAGE{sup Registered-Sign} 3D dosimeter for proton therapy. Methods: The GEANT4 software toolkit was used to calculate and compare total dose delivered by a proton beam with mean energy 62 MeV in a PRESAGE{sup Registered-Sign} dosimeter, water, and soft tissue. The dose delivered by primary protons and secondary particles was calculated. Depth-dose profiles and isodose contours of deposited energy were compared for the materials of interest. Results: The proton beam range was found to be Almost-Equal-To 27 mm for PRESAGE{sup Registered-Sign }, 29.9 mm for soft tissue, and 30.5 mm for water. This can be attributed to the lower collisional stopping power of water compared to soft tissue and PRESAGE{sup Registered-Sign }. The difference between total dose delivered in PRESAGE{sup Registered-Sign} and total dose delivered in water or tissue is less than 2% across the entire water/tissue equivalent range of the proton beam. The largest difference between total dose in PRESAGE{sup Registered-Sign} and total dose in water is 1.4%, while for soft tissue it is 1.8%. In both cases, this occurs at the distal end of the beam. Nevertheless, the authors find that PRESAGE{sup Registered-Sign} dosimeter is overall more tissue-equivalent than water-equivalent before the Bragg peak. After the Bragg peak, the differences in the depth doses are found to be due to differences in primary proton energy deposition; PRESAGE{sup Registered-Sign} and soft tissue stop protons more rapidly than water. The dose delivered by secondary electrons in the PRESAGE{sup Registered-Sign} differs by less than 1% from that in soft tissue and water. The contribution of secondary particles to the total dose is less than 4% for electrons and Almost-Equal-To 1% for protons in all the materials of interest. Conclusions: These results demonstrate that the new PRESAGE{sup Registered-Sign} formula may be considered both a tissue- and water-equivalent

  14. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents in tissues of birds at Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Jones, Paul D.; Giesy, John P.; Newsted, John L.; Verbrugge, David A.; Beaver, Donald L.; Ankley, Gerald T.; Tillitt, Donald E.; Lodge, Keith B.; Niemi, Gerald J.

    1993-01-01

    The environment has become contaminated with complex mixtures of planar, chlorinated hydrocarbons (PCHs) such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and structurally similar compounds. Because the potencies of individual congeners to cause the same adverse effects vary greatly and the relative as well as absolute concentrations of individual PCH vary among samples from different locations, it is difficult to assess the toxic effects of these mixtures on wildlife. These compounds can cause a number of adverse effects, however, because the toxic effects which occur at ecologically-relevant concentrations such as embryo-lethality and birth defects appear to be mediated through the same mechanism, the potency of individual congeners can be reported relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) which is the most toxic congener in the PCH class. The concentations of 2,3,7,8-TCDD Equivalents (TCDD-EQ) were determined in the tissues of aquatic and terrestrial birds of Green Bay, Wisconsin by the H4IIE bioassay system and compared toxic equivalency factors (TEFs) with the concentration predicted by the use of toxic equivalency factors applied to concentrations of PCH, which were determined by instrumental analyses. Concentrations of TCDD-EQ ranged from 0.52 to 440 ng/kg, wet weight. The greatest concentrations occurred in the fish-eating birds. Concentrations of TCDD-EQ, which were determined by the two methods were significantly correlated, but the additive model which used the TEFs with concentrations of measured PCB, PCDD and PCDF congeners underestimated the concentrations of TCDD-EQ measured by the H4IIE bioassay by an average of 57%. This is thought to be due to contributions from un-quantified PCH, which are known to occur in the environment. Of the quantified PCH congeners, PCDD and PCDF contributed a small portion of the TCDD-EQ in the aquatic birds, while most of the

  15. Tissue equivalent proportional counter microdosimetry measurements utililzed aboard aircraft and in accelerator based space radiation shielding studies

    NASA Astrophysics Data System (ADS)

    Gersey, Brad; Wilkins, Richard

    The space radiation environment presents a potential hazard to the humans, electronics and materials that are exposed to it. Particle accelerator facilities such as the NASA Space Ra-diation Laboratory (NSRL) and Loma Linda University Medical Center (LLUMC) provide particle radiation of specie and energy within the range of that found in the space radiation environment. Experiments performed at these facilities determine various endpoints for bio-logical, electronic and materials exposures. A critical factor in the performance of rigorous scientific studies of this type is accurate dosimetric measurements of the exposures. A Tissue Equivalent Proportional Counter (TEPC) is a microdosimeter that may be used to measure absorbed dose, average quality factor (Q) and dose equivalent of the particle beam utilized in these experiments. In this work, results from a variety of space radiation shielding studies where a TEPC was used to perform dosimetry in the particle beam will be presented. These results compare the absorbed dose and dose equivalent measured downstream of equal density thicknesses of stan-dard and multifunctional shielding materials. The standard materials chosen for these shielding studies included High-Density Polyethylene (HDPE) and aluminum alloy, while the multifunc-tional materials included carbon composite infused with single walled carbon nanotubes. High energy particles including proton, silicon and iron nuclei were chosen as the incident radia-tion for these studies. Further, TEPC results from measurements taken during flights aboard ER-2 and KC-135 aircraft will also be discussed. Results from these flight studies include TEPC measurements for shielded and unshielded conditions as well as the effect of vibration and electromagnetic exposures on the TEPC operation. The data selected for presentation will highlight the utility of the TEPC in space radiation studies, and in shielding studies in particular. The lineal energy response function of the

  16. Characterization of paraffin based breast tissue equivalent phantom using a CdTe detector pulse height analysis.

    PubMed

    Cubukcu, Solen; Yücel, Haluk

    2016-12-01

    In this study, paraffin was selected as a base material and mixed with different amounts of CaSO4·2H2O and H3BO3 compounds in order to mimic breast tissue. Slab phantoms were produced with suitable mixture ratios of the additives in the melted paraffin. Subsequently, these were characterized in terms of first half-value layer (HVL) in the mammographic X-ray range using a pulse-height spectroscopic analysis with a CdTe detector. Irradiations were performed in the energy range of 23-35 kVp under broad beam conditions from Mo/Mo and Mo/Rh target/filter combinations. X-ray spectra were acquired with a CdTe detector without and with phantom material interposition in increments of 1 cm thickness and then evaluated to obtain the transmission data. The net integral areas of the spectra for the slabs were used to plot the transmission curves and these curves were fitted to the Archer model function. The results obtained for the slabs were compared with those of standard mammographic phantoms such as CIRS BR series phantoms and polymethylmethacrylate plates (PMMA). From the evaluated transmission curves, the mass attenuation coefficients and HVLs of some mixtures are close to those of the commercially available standard mammography phantoms. Results indicated that when a suitable proportion of H3BO3 and CaSO4·2H2O is added to the paraffin, the resulting material may be a good candidate for a breast tissue equivalent phantom.

  17. Fabrication and characterisation of biomimetic, electrospun gelatin fibre scaffolds for tunica media-equivalent, tissue engineered vascular grafts.

    PubMed

    Elsayed, Y; Lekakou, C; Labeed, F; Tomlins, P

    2016-04-01

    It is increasingly recognised that biomimetic, natural polymers mimicking the extracellular matrix (ECM) have low thrombogenicity and functional motifs that regulate cell-matrix interactions, with these factors being critical for tissue engineered vascular grafts especially grafts of small diameter. Gelatin constitutes a low cost substitute of soluble collagen but gelatin scaffolds so far have shown generally low strength and suture retention strength. In this study, we have devised the fabrication of novel, electrospun, multilayer, gelatin fibre scaffolds, with controlled fibre layer orientation, and optimised gelatin crosslinking to achieve not only compliance equivalent to that of coronary artery but also for the first time strength of the wet tubular acellular scaffold (swollen with absorbed water) same as that of the tunica media of coronary artery in both circumferential and axial directions. Most importantly, for the first time for natural scaffolds and in particular gelatin, high suture retention strength was achieved in the range of 1.8-1.94 N for wet acellular scaffolds, same or better than that for fresh saphenous vein. The study presents the investigations to relate the electrospinning process parameters to the microstructural parameters of the scaffold, which are further related to the mechanical performance data of wet, crosslinked, electrospun scaffolds in both circumferential and axial tubular directions. The scaffolds exhibited excellent performance in human smooth muscle cell (SMC) proliferation, with SMCs seeded on the top surface adhering, elongating and aligning along the local fibres, migrating through the scaffold thickness and populating a transverse distance of 186 μm and 240 μm 9 days post-seeding for scaffolds of initial dry porosity of 74 and 83%, respectively.

  18. Controlling the 3D architecture of Self-Lifting Auto-generated Tissue Equivalents (SLATEs) for optimized corneal graft composition and stability.

    PubMed

    Gouveia, Ricardo M; González-Andrades, Elena; Cardona, Juan C; González-Gallardo, Carmen; Ionescu, Ana M; Garzon, Ingrid; Alaminos, Miguel; González-Andrades, Miguel; Connon, Che J

    2017-03-01

    Ideally, biomaterials designed to play specific physical and physiological roles in vivo should comprise components and microarchitectures analogous to those of the native tissues they intend to replace. For that, implantable biomaterials need to be carefully designed to have the correct structural and compositional properties, which consequently impart their bio-function. In this study, we showed that the control of such properties can be defined from the bottom-up, using smart surface templates to modulate the structure, composition, and bio-mechanics of human transplantable tissues. Using multi-functional peptide amphiphile-coated surfaces with different anisotropies, we were able to control the phenotype of corneal stromal cells and instruct them to fabricate self-lifting tissues that closely emulated the native stromal lamellae of the human cornea. The type and arrangement of the extracellular matrix comprising these corneal stromal Self-Lifting Analogous Tissue Equivalents (SLATEs) were then evaluated in detail, and was shown to correlate with tissue function. Specifically, SLATEs comprising aligned collagen fibrils were shown to be significantly thicker, denser, and more resistant to proteolytic degradation compared to SLATEs formed with randomly-oriented constituents. In addition, SLATEs were highly transparent while providing increased absorption to near-UV radiation. Importantly, corneal stromal SLATEs were capable of constituting tissues with a higher-order complexity, either by creating thicker tissues through stacking or by serving as substrate to support a fully-differentiated, stratified corneal epithelium. SLATEs were also deemed safe as implants in a rabbit corneal model, being capable of integrating with the surrounding host tissue without provoking inflammation, neo-vascularization, or any other signs of rejection after a 9-months follow-up. This work thus paves the way for the de novo bio-fabrication of easy-retrievable, scaffold-free human

  19. UVB-induced inflammatory cytokine release, DNA damage and apoptosis of human oral compared with skin tissue equivalents.

    PubMed

    Breger, Joyce; Baeva, Larissa; Agrawal, Anant; Shindell, Eli; Godar, Dianne E

    2013-01-01

    People can get oral cancers from UV (290-400 nm) exposures. Besides high outdoor UV exposures, high indoor UV exposures to oral tissues can occur when consumers use UV-emitting tanning devices to either tan or whiten their teeth. We compared the carcinogenic risks of skin to oral tissue cells after UVB (290-320 nm) exposures using commercially available 3D-engineered models for human skin (EpiDerm™), gingival (EpiGing™) and oral (EpiOral™) tissues. To compare the relative carcinogenic risks, we investigated the release of cytokines, initial DNA damage in the form of cyclobutane pyrimidine dimers (CPDs), repair of CPDs and apoptotic cell numbers. We measured cytokine release using cytometric beads with flow cytometry and previously developed a fluorescent immunohistochemical assay to quantify simultaneously CPD repair rates and apoptotic cell numbers. We found that interleukin-8 (IL-8) release and the initial CPDs are significantly higher, whereas the CPD repair rates and apoptotic cell numbers are significantly lower for oral compared with skin tissue cells. Thus, the increased release of the inflammatory cytokine IL-8 along with inefficient CPD repair and decreased death rates for oral compared with skin tissue cells suggests that mutations are accumulating in the surviving population of oral cells increasing people's risks for getting oral cancers.

  20. Influence of mechanical stimulation in the development of a medial equivalent tissue-engineered vascular construct using a gelatin-g-vinyl acetate co-polymer scaffold.

    PubMed

    Thomas, Lynda V; Nair, Prabha D

    2012-01-01

    Vascular regeneration in the area of small diameter (<6 mm) vessels via the tissue-engineering approach has been in focus for some time now. In this study, we report the development and evaluation of a tissue-engineered medial equivalent using gelatin-g-vinyl acetate co-polymer (GeVAc) as the scaffold material. GeVAc was synthesized by co-polymerizing gelatin and vinyl acetate monomer in the presence of AIBN as the initiator and subjected to physico-chemical characterization. A porous 3-D scaffold with open interconnected pores was then produced from GeVAc. The scaffold is non-cytotoxic with good smooth muscle cell proliferative capacity and high cell viability. Influence of smooth muscle cell phenotype in response to these scaffolds has been studied under mechanical stimulation. It was found that the cell-seeded tubular GeVAc constructs under mechanical stimulation preferentially supported the contractile phenotype of smooth muscle cells, as evidenced by the elevated expression of contractile protein markers such as alpha-SMA, calponin and SM22α. The mechanical properties and the ECM secretion were also increased on applying the mechanical stimulation. Hence, the results showed the promising potential of the GeVAc scaffolds in the regeneration of the medial equivalent tissue-engineered vascular construct.

  1. Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

    NASA Astrophysics Data System (ADS)

    Golightly, M. J.; Hardy, A. C.; Hardy, K.

    1994-10-01

    Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  2. Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

    NASA Technical Reports Server (NTRS)

    Golightly, M. J.; Hardy, A. C.; Hardy, K.

    1994-01-01

    Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  3. Results of time-resolved radiation exposure measurements made during U.S. Shuttle missions with a tissue equivalent proportional counter.

    PubMed

    Golightly, M J; Hardy, A C; Hardy, K

    1994-10-01

    Time-resolved radiation exposure measurements inside the crew compartment have been made during recent Shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28.5 degrees to 57 degrees, and altitudes from 200-600 km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high-LET particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Iso-dose rate contours have been developed from measurements made during the STS-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  4. Investigation of dose and flux dynamics in the Liulin-5 dosimeter of the tissue-equivalent phantom onboard the Russian segment of the International Space Station.

    PubMed

    Semkova, J; Koleva, R; Todorova, G; Kanchev, N; Petrov, V; Shurshakov, V; Benghin, V; Tchhernykh, I; Akatov, Yu; Redko, V

    2003-03-01

    Described is the Liulin-5 active dosimetric telescope designed for measurement of the space radiation dose depth-distribution in a human phantom on the Russian Segment of the International Space Station (ISS). The Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The MATROSHKA-R project is aimed to study the depth-dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is a long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different compartments. Energy deposition spectra, linear energy transfer spectra, and flux and dose rates for charged particles will be measured simultaneously with near real time resolution at different depths of the phantom by means of three silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, which verify the models of radiation environment in low Earth orbit. Presented are the test results of the prototype unit. Liulin-5 will be flown on the ISS in the year 2003.

  5. Study of the effect of high dose rate on tissue equivalent proportional counter microdosimetric measurements in mixed photon and neutron fields

    NASA Astrophysics Data System (ADS)

    Aslam; Qashua, N.; Waker, A. J.

    2011-10-01

    This study describes the measurement of lineal energy spectra carried out with a 5.1 cm (2 in.) diameter spherical tissue equivalent proportional counter (TEPC) simulating 2 μm tissue equivalent (TE) site diameter in low energy mixed photon-neutron fields with varying dose rates generated by employing the McMaster University 1.25 MV double stage Tandetron accelerator. The 7Li (p, n) 7Be reaction was employed to generate a variety of mixed fields of photons and low energy neutrons using proton beam energy ranging 1.89-2.56 MeV. The dose rate at a given beam energy was varied by changing the beam current. Dose rates that resulted in dead times as high as 75% were employed to study the effect of dose rate on quality, microdosimetric averages ( y¯F and y¯D), absorbed dose and dose equivalent. We have observed that high dose rates due to both photons and neutrons in a mixed field of radiation result in pile up of pulses and distort the lineal energy spectrum measured under these conditions. The pile up effect and hence the distortion in the lineal energy spectrum becomes prominent with dose rates, which result in dead times larger than 25% for the high linear energy transfer (LET) radiation component. Intense neutron fields, which may amount to 75% dead time, could result in a 50% or even larger increase in the values of the microsdosimetric averages and the neutron quality factor. This study demonstrates moderate dose rates that do not result in dead times of more than 20-25% due to either of the component radiation or due to both components of mixed field radiation generate results that are acceptable for radiation monitoring.

  6. The Effect of Pulsatile Loading and Scaffold Structure for the Generation of a Medial Equivalent Tissue Engineered Vascular Graft

    PubMed Central

    Thomas, Lynda V.

    2013-01-01

    Abstract A reliable and cost-effective scaffold for tissue-engineered vascular graft that would not only support cell proliferation and growth but also maintain cell phenotype has been a long-term challenge. In this study, we propose a biodegradable and biomimetic copolymer of gelatin with vinyl acetate synthesized via a graft copolymerization technique to generate tubular scaffolds for vascular tissue engineering. Two fabrication techniques, freeze drying and electrospinning, were used to generate the differing architectures for the scaffolds and characterized. The electrospun scaffolds were found to have a faster rate of mass loss in physiological saline of 81.72% within 4 months compared with 60% mass loss for the freeze-dried samples, though the materials were more crystalline. Vascular (v) smooth muscle cells (SMCs) were seeded on these tubes, which were then subjected to dynamic pulsatile stimulation on a vascular bioreactor for a week. Gross examination of the tissue-engineered constructs revealed that the cells secreted extensive extracellular matrix, with the dynamically conditioned samples exhibiting well-orientated SMCs and collagenous fibers in comparison with growth in static conditions. In addition, the alignment of cells in the direction of strain was greater in the electrospun constructs. The electrospun scaffolds maintained the characteristic contractile phenotype of SMCs, which was confirmed by higher gene expression rates of contractile protein markers like SM22α and calponin. A significant increase in the total matrix components (collagen and elastin) in the electrospun constructs compared with the freeze-dried samples was confirmed by biochemical analysis. The results of this study indicate that a combination approach involving a biomimetic scaffold with the nanofibrillar architecture and good mechanical strength conducive to the growth of SMCs and the use of the pulsatile forces to modulate the cell morphology and phenotypic plasticity of v

  7. Development of a stable and reproducible tissue-equivalent phantom for use in infrared spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

    Firbank, Michael; Hiraoka, Mutsuhisa; Delpy, David T.

    1993-09-01

    Much of the experimental work reported on the applications of near infrared spectroscopy and imaging for therapeutic purposes has been performed on multifarious tissue simulating materials, which often have unreproducible optical properties. To facilitate the quantitative testing of spectroscopy equipment, stable, reproducible phantoms which replicate the optical properties of tissue are needed. This paper describes one such phantom. The base material is a clear, non polymerized liquid polyester resin, which forms a solid on addition of a catalyst. The polyester has a low intrinsic absorption coefficient for infrared light and is nonscattering. Before the resin is set, measured quantities of scattering particle suspensions and absorbing dyes can be added. The scattering phase function of these particles has been measured, and the mean cosine of the scattering angle, g, calculated. Knowing this, by varying the concentration of scattering particles a range of materials with known transport scattering coefficients can be produced. By varying the concentration and mix of dyes, the absorption coefficient of the resin can be easily controlled. The resin can be easily machined or cast into arbitrary shapes, with regions of differing optical properties. Once set, the polyester is stable, in terms of both physical and optical properties.

  8. Feasibility of salvage interstitial microwave thermal therapy for prostate carcinoma following failed brachytherapy: studies in a tissue equivalent phantom.

    PubMed

    McCann, Claire; Kumaradas, J Carl; Gertner, Mark R; Davidson, Sean R H; Dolan, Alfred M; Sherar, Michael D

    2003-04-21

    Thermal therapy is an experimental treatment to destroy solid tumours by heating them to temperatures ranging from 55 degrees C to 90 degrees C, inducing thermal coagulation and necrosis of the tumour. We are investigating the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate cancer patients with local recurrence following failed brachytherapy. Due to the electrical and thermal conductivity of the brachytherapy seeds, we hypothesized that the seeds could scatter the microwave energy and cause unpredictable heating. To investigate this, a 915 MHz helical antenna was inserted into a muscle-equivalent phantom with and without brachytherapy seeds. Following a 10 W, 5 s input to the antenna, the temperature rise was used to calculate absorbed power, also referred to as specific absorption rate (SAR). Plane wave models based on Maxwell's equations were also used to characterize the electromagnetic scattering effect of the seeds. In addition, the phantom was heated with 8 W for 5 min to quantify the effect of the seeds on the temperature distribution during extended heating. SAR measurements indicated that the seeds had no significant effect on the shape and size of the SAR pattern of the antenna. However, the plane wave simulations indicated that the seeds could scatter the microwave energy resulting in hot spots at the seed edges. Lack of experimental evidence of these hot spots was probably due to the complex polarization of the microwaves emitted by the helical antenna. Extended heating experiments also demonstrated that the seeds had no significant effect on the temperature distributions and rates of temperature rise measured in the phantom. The results indicate that brachytherapy seeds are not a technical impediment to interstitial microwave thermal therapy as a salvage treatment following failed brachytherapy.

  9. Feasibility of salvage interstitial microwave thermal therapy for prostate carcinoma following failed brachytherapy: studies in a tissue equivalent phantom

    NASA Astrophysics Data System (ADS)

    McCann, Claire; Kumaradas, J. Carl; Gertner, Mark R.; Davidson, Sean R. H.; Dolan, Alfred M.; Sherar, Michael D.

    2003-04-01

    Thermal therapy is an experimental treatment to destroy solid tumours by heating them to temperatures ranging from 55 °C to 90 °C, inducing thermal coagulation and necrosis of the tumour. We are investigating the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate cancer patients with local recurrence following failed brachytherapy. Due to the electrical and thermal conductivity of the brachytherapy seeds, we hypothesized that the seeds could scatter the microwave energy and cause unpredictable heating. To investigate this, a 915 MHz helical antenna was inserted into a muscle-equivalent phantom with and without brachytherapy seeds. Following a 10 W, 5 s input to the antenna, the temperature rise was used to calculate absorbed power, also referred to as specific absorption rate (SAR). Plane wave models based on Maxwell's equations were also used to characterize the electromagnetic scattering effect of the seeds. In addition, the phantom was heated with 8 W for 5 min to quantify the effect of the seeds on the temperature distribution during extended heating. SAR measurements indicated that the seeds had no significant effect on the shape and size of the SAR pattern of the antenna. However, the plane wave simulations indicated that the seeds could scatter the microwave energy resulting in hot spots at the seed edges. Lack of experimental evidence of these hot spots was probably due to the complex polarization of the microwaves emitted by the helical antenna. Extended heating experiments also demonstrated that the seeds had no significant effect on the temperature distributions and rates of temperature rise measured in the phantom. The results indicate that brachytherapy seeds are not a technical impediment to interstitial microwave thermal therapy as a salvage treatment following failed brachytherapy.

  10. Study of microdosimetric energy deposition patterns in tissue-equivalent medium due to low-energy neutron fields using a graphite-walled proportional counter.

    PubMed

    Waker, A J; Aslam

    2011-06-01

    To improve radiation protection dosimetry for low-energy neutron fields encountered in nuclear power reactor environments, there is increasing interest in modeling neutron energy deposition in metrological instruments such as tissue-equivalent proportional counters (TEPCs). Along with these computational developments, there is also a need for experimental data with which to benchmark and test the results obtained from the modeling methods developed. The experimental work described in this paper is a study of the energy deposition in tissue-equivalent (TE) medium using an in-house built graphite-walled proportional counter (GPC) filled with TE gas. The GPC is a simple model of a standard TEPC because the response of the counter at these energies is almost entirely due to the neutron interactions in the sensitive volume of the counter. Energy deposition in tissue spheres of diameter 1, 2, 4 and 8 µm was measured in low-energy neutron fields below 500 keV. We have observed a continuously increasing trend in microdosimetric averages with an increase in neutron energy. The values of these averages decrease as we increase the simulated diameter at a given neutron energy. A similar trend for these microdosimetric averages has been observed for standard TEPCs and the Rossi-type, TE, spherical wall-less counter filled with propane-based TE gas in the same energy range. This implies that at the microdosimetric level, in the neutron energy range we employed in this study, the pattern of average energy deposited by starter and insider proton recoil events in the gas is similar to those generated cumulatively by crosser and stopper events originating from the counter wall plus starter and insider recoil events originating in the sensitive volume of a TEPC.

  11. On the Applicability of the Thermal Dose Cumulative Equivalent Minutes Metric to the Denaturation of Bovine Serum Albumin in a Polyacrylamide Tissue Phantom

    SciTech Connect

    Nandlall, Sacha D.; Arora, Manish; Schiffter, Heiko A.; Coussios, Constantin-C.

    2009-04-14

    Thermal dose has been proposed for various hyperthermic cancer treatment modalities as a measure of heat-induced tissue damage. However, the applicability of current thermal dose metrics to tissue is not well understood, particularly at the temperatures and rates of heating relevant to ablative cancer therapy using High-Intensity Focussed Ultrasound (HIFU). In this work, we assess whether the most widely employed thermal dose metric, Cumulative Equivalent Minutes (CEM), can adequately quantify heat-induced denaturation in a tissue-mimicking material (phantom) consisting of Bovine Serum Albumin (BSA) proteins embedded in a polyacrylamide matrix. The phantom is exposed to various temperature profiles and imaged under controlled lighting conditions against a black background as it denatures and becomes progressively more opaque. Under the assumption that the mean backscattered luminous intensity provides a good measure of the extent of BSA denaturation, we establish a relationship between the amount of thermal damage caused to the phantom, exposure time, and temperature. We demonstrate that, for monotonically increasing and bounded temperature profiles, the maximal degree to which the phantom can denature is dependent on the peak temperature it reaches, irrespective of exposure duration. We also show that when the CEM is computed using the commonly employed piecewise-constant approximation of the parameter R, the CEM values corresponding to the same degree of damage delivered using different temperature profiles do not agree well with each other in general.

  12. Results on Dose Distributions in a Human Body from the Matroshka-R Experiment onboard the ISS Obtained with the Tissue-Equivalent Spherical Phantom

    NASA Astrophysics Data System (ADS)

    Shurshakov, Vyacheslav; Nikolaev, Igor; Kartsev, Ivan; Tolochek, Raisa; Lyagushin, Vladimir

    The tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS in Matroshka-R experiment for more than 10 years. Both passive and active space radiation detectors can be located inside the phantom and on its surface. Due to the specially chosen phantom shape and size, the chord length distributions of the detector locations are attributed to self-shielding properties of the critical organs in a human body. Originally the spherical phantom was installed in the star board crew cabin of the ISS Service Module, then in the Piers-1, MIM-2, and MIM-1 modules of the ISS Russian segment, and finally in JAXA Kibo module. Total duration of the detector exposure is more than 2000 days in 9 sessions of the space experiment. In the first phase of the experiment with the spherical phantom the dose measurements were realized with only passive detectors (thermoluminescent and solid state track detectors). The detectors are placed inside the phantom along the axes of 20 containers and on the phantom outer surface in 32 pockets of the phantom jacket. After each session the passive detectors are returned to the ground. The results obtained show the dose difference on the phantom surface as much as a factor of 2, the highest dose being usually observed close to the outer wall of the compartment, and the lowest dose being in the opposite location along the phantom diameter. However, because of the ISS module shielding properties an inverse dose distribution in a human body can be observed when the dose rate maximum is closer to the geometrical center of the module. Maximum dose rate measured in the phantom is obviously due to the action of two radiation sources, namely, galactic cosmic rays (GCR) and Earth’ radiation belts. Minimum dose rate is produced mainly by the strongly penetrating GCR particles and is mostly observed behind more than 5 g/cm2 tissue shielding. Critical organ doses, mean-tissue

  13. Comparisons of LET distributions measured in low-earth orbit using tissue-equivalent proportional counters and the position-sensitive silicon-detector telescope (RRMD-III).

    PubMed

    Doke, T; Hayashi, T; Borak, T B

    2001-09-01

    Determinations of the LET distribution, phi(L), of charged particles within a spacecraft in low-Earth orbit have been made. One method used a cylindrical tissue-equivalent proportional counter (TEPC), with the assumption that for each measured event, lineal energy, y, is equal to LET and thus phi(L) = phi(y). The other was based on the direct measurement of LETs for individual particles using a charged-particle telescope consisting of position-sensitive silicon detectors called RRMD-III. There were differences of up to a factor of 10 between estimates of phi(L) using the two methods on the same mission. This caused estimates of quality factor to vary by a factor of two between the two methods.

  14. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Badiger, N. M.

    2014-11-01

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

  15. Optimization of optical and mechanical properties of real architecture for 3-dimensional tissue equivalents: Towards treatment of limbal epithelial stem cell deficiency.

    PubMed

    Massie, Isobel; Kureshi, Alvena K; Schrader, Stefan; Shortt, Alex J; Daniels, Julie T

    2015-09-01

    Limbal epithelial stem cell (LESC) deficiency can cause blindness. Transplantation of cultured human limbal epithelial cells (hLE) on human amniotic membrane (HAM) can restore vision but clinical graft manufacture can be unreliable. We have developed a reliable and robust tissue equivalent (TE) alternative to HAM, Real Architecture for 3D Tissue (RAFT). Here, we aimed to optimize the optical and mechanical properties of RAFT TE for treatment of LESC deficiency in clinical application. The RAFT TE protocol is tunable; varying collagen concentration and volume produces differing RAFT TEs. These were compared with HAM samples taken from locations proximal and distal to the placental disc. Outcomes assessed were transparency, thickness, light transmission, tensile strength, ease of handling, degradation rates and suitability as substrate for hLE culture. Proximal HAM samples were thicker and stronger with poorer optical properties than distal HAM samples. RAFT TEs produced using higher amounts of collagen were thicker and stronger with poorer optical properties than those produced using lower amounts of collagen. The 'optimal' RAFT TE was thin, transparent but still handleable and was produced using 0.6ml of 3mg/ml collagen. Degradation rates of the 'optimal' RAFT TE and HAM were similar. hLE achieved confluency on 'optimal' RAFT TEs at comparable rates to HAM and cells expressed high levels of putative stem cell marker p63α. These findings support the use of RAFT TE for hLE transplantation towards treatment of LESC deficiency.

  16. The response of a spherical tissue-equivalent proportional counter to iron particles from 200-1000 MeV/nucleon

    NASA Technical Reports Server (NTRS)

    Gersey, B. B.; Borak, T. B.; Guetersloh, S. B.; Zeitlin, C.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.; Chatterjee, A. (Principal Investigator)

    2002-01-01

    The radiation environment on board the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 particles are considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPCs) are used as active dosimeters on manned space flights. These TEPCs are further used to determine the average quality factor for each space mission. A TEPC simulating a 1-microm-diameter sphere of tissue was exposed as part of a particle spectrometer to (56)Fe particles at energies from 200-1000 MeV/nucleon. The response of TEPCs in terms of mean lineal energy, y(F), and dose mean lineal energy, y(D), as well as the energy deposited at different impact parameters through the detector was determined for six different incident energies of (56)Fe particles in this energy range. Calculations determined that charged-particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model, and the results were compared to experimental data.

  17. The response of a spherical tissue-equivalent proportional counter to 56-Fe particles from 200-1000 MeV/nucleon

    SciTech Connect

    Gersey, Bradford B.; Borak, Thomas B.; Guetersloh, Stephen B.; Zeitlin, Cary J.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.

    2001-09-04

    The radiation environment aboard the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 is considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPC) are used as active dosimeters on manned space flights. These TEPC's are further used to determine average quality factor for each space mission. A TEPC simulating a 1 micron diameter sphere of tissue was exposed as part of a particle spectrometer to iron-56 at energies from 200-1000 MeV/nucleon. The response of TEPC in terms of frequency-averaged lineal energy, dose-averaged lineal energy, as well as energy deposited at different impact parameters through detector was determined for six different incident energies of iron-56 in this energy range. Calculations determined that charged particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model and the results compared to experimental data.

  18. Studies on heavy charged particle interaction, water equivalence and Monte Carlo simulation in some gel dosimeters, water, human tissues and water phantoms

    NASA Astrophysics Data System (ADS)

    Kurudirek, Murat

    2015-09-01

    Some gel dosimeters, water, human tissues and water phantoms were investigated with respect to their radiological properties in the energy region 10 keV-10 MeV. The effective atomic numbers (Zeff) and electron densities (Ne) for some heavy charged particles such as protons, He ions, B ions and C ions have been calculated for the first time for Fricke, MAGIC, MAGAT, PAGAT, PRESAGE, water, adipose tissue, muscle skeletal (ICRP), muscle striated (ICRU), plastic water, WT1 and RW3 using mass stopping powers from SRIM Monte Carlo software. The ranges and straggling were also calculated for the given materials. Two different set of mass stopping powers were used to calculate Zeff for comparison. The water equivalence of the given materials was also determined based on the results obtained. The Monte Carlo simulation of the charged particle transport was also done using SRIM code. The heavy ion distribution along with its parameters were shown for the given materials for different heavy ions. Also the energy loss and damage events in water when irradiated with 100 keV heavy ions were studied in detail.

  19. SU-E-J-210: Characterizing Tissue Equivalent Materials for the Development of a Dual MRI-CT Heterogeneous Anthropomorphic Phantom Designed Specifically for MRI Guided Radiotherapy Systems

    SciTech Connect

    Steinmann, A; Stafford, R; Yung, J; Followill, D

    2015-06-15

    Purpose: MRI guided radiotherapy (MRIgRT) is an emerging technology which will eventually require a proficient quality auditing system. Due to different principles in which MR and CT acquire images, there is a need for a multi-imaging-modality, end-to-end QA phantom for MRIgRT. The purpose of this study is to identify lung, soft tissue, and tumor equivalent substitutes that share similar human-like CT and MR properties (i.e. Hounsfield units and relaxation times). Methods: Materials of interested such as common CT QA phantom materials, and other proprietary gels/silicones from Polytek, SmoothOn, and CompositeOne were first scanned on a GE 1.5T Signa HDxT MR. Materials that could be seen on both T1-weighted and T2-weighted images were then scanned on a GE Lightspeed RT16 CT simulator and a GE Discovery 750HD CT scanner and their HU values were then measured. The materials with matching HU values of lung (−500 to −700HU), muscle (+40HU) and soft tissue (+100 to +300HU) were further scanned on GE 1.5T Signa HDx to measure their T1 and T2 relaxation times from varying parameters of TI and TE. Results: Materials that could be visualized on T1-weighted and T2-weighted images from a 1.5T MR unit and had an appropriate average CT number, −650, −685, 46,169, and 168 HUs were: compressed cork saturated with water, Polytek Platsil™ Gel-00 combined with mini styrofoam balls, radiotherapy bolus material, SmoothOn Dragon-Skin™ and SmoothOn Ecoflex™, respectively. Conclusion: Post processing analysis is currently being performed to accurately map T1 and T2 values for each material tested. From previous MR visualization and CT examinations it is expected that Dragon-Skin™, Ecoflex™ and bolus will have values consistent with tissue and tumor substitutes. We also expect compressed cork statured with water, and Polytek™-styrofoam combination to have approximate T1 and T2 values suitable for lung-equivalent materials.

  20. A study of neutron radiation quality with a tissue-equivalent proportional counter for a low-energy accelerator-based in vivo neutron activation facility.

    PubMed

    Aslam; Waker, A J

    2011-02-01

    The accelerator-based in vivo neutron activation facility at McMaster University has been used successfully for the measurement of several minor and trace elements in human hand bones due to their importance to health. Most of these in vivo measurements have been conducted at a proton beam energy (E(p)) of 2.00 MeV to optimise the activation of the selected element of interest with an effective dose of the same order as that received in chest X rays. However, measurement of other elements at the same facility requires beam energies other than 2.00 MeV. The range of energy of neutrons produced at these proton beam energies comes under the region where tissue-equivalent proportional counters (TEPCs) are known to experience difficulty in assessing the quality factor and dose equivalent. In this study, the response of TEPCs was investigated to determine the quality factor of neutron fields generated via the (7)Li(p, n)(7)Be reaction as a function of E(p) in the range 1.884-2.56 MeV at the position of hand irradiation in the facility. An interesting trend has been observed in the quality factor based on ICRP 60, Q(ICRP60), such that the maximum value was observed at E(p)=1.884 MeV (E(n)=33±16 keV) and then continued to decline with increasing E(p) until achieving a minimum value at E(p)=2.0 MeV despite a continuous increase in the mean neutron energy with E(p). This observation is contrary to what has been observed with direct fast neutrons where the quality factor was found to increase continuously with an increase in E(p) (i.e. increasing E(n)). The series of measurements conducted with thermal and fast neutron fields demonstrate that the (14)N(n, p)(14)C produced 580 keV protons in the detector play an important role in the response of the counter under 2.0 MeV proton energy (E(n) ≤ 250 keV). In contrast to the lower response of TEPCs to low-energy neutrons, the quality factor is overestimated in the range 1-2 depending on beam energy <2.0 MeV. This study provides

  1. Comparison of the biological equivalence of two methods for isolating bone marrow mononuclear cells for fabricating tissue-engineered vascular grafts.

    PubMed

    Kurobe, Hirotsugu; Tara, Shuhei; Maxfield, Mark W; Rocco, Kevin A; Bagi, Paul S; Yi, Tai; Udelsman, Brooks V; Dean, Ethan W; Khosravi, Ramak; Powell, Heather M; Shinoka, Toshiharu; Breuer, Christopher K

    2015-06-01

    Our approach for fabricating tissue-engineered vascular grafts (TEVG), applied in the surgical management of congenital heart disease, is accomplished by seeding isolated bone marrow-derived mononuclear cells (BM-MNCs) onto biodegradable scaffolds. The current method used for isolation of BM-MNCs is density centrifugation in Ficoll. This is a time-consuming, labor-intensive, and operator-dependent method. We previously demonstrated that a simpler, faster, and operator-independent method for isolating BM-MNCs using a filter elution technique was feasible. In this study, we compare the use of each technique to determine if the BM-MNCs isolated by the filtration elution method are biologically equivalent to BM-MNCs isolated using density centrifugation. Scaffolds were constructed from a nonwoven poly(glycolic acid) fiber mesh coated with 50:50 poly(l-lactide-co-ɛ-caprolactone) sealant. BM-MNCs were isolated from the bone marrow of syngeneic C57BL/6 mice by either density centrifugation with Ficoll or filtration (Ficoll vs. Filter), then statically seeded onto scaffolds, and incubated overnight. The TEVG were implanted in 10-week-old C57BL/6 mice (n=23 for each group) as inferior vena cava interposition grafts and explanted at 14 days for analysis. At 14 days after implantation, there were no significant differences in graft patency between groups (Ficoll: 87% vs. Filter: 78%, p=0.45). Morphometric analysis by hematoxylin and eosin staining showed no difference of graft luminal diameter or neointimal thickness between groups (luminal diameter, Ficoll: 620.3±82.9 μm vs. Filter: 633.3±131.0 μm, p=0.72; neointimal thickness, Ficoll: 37.9±7.8 μm vs. Filter: 37.9±11.2 μm, p=0.99). Histologic examination demonstrated similar degrees of cellular infiltration and extracellular matrix deposition, and endothelial cell coverage on the luminal surface, in either group. Macrophage infiltration showed no difference in the number of F4/80-positive cells or macrophage

  2. Response of human limbal epithelial cells to wounding on 3D RAFT tissue equivalents: effect of airlifting and human limbal fibroblasts.

    PubMed

    Massie, Isobel; Levis, Hannah J; Daniels, Julie T

    2014-10-01

    Limbal epithelial stem cell deficiency can cause blindness but may be treated by human limbal epithelial cell (hLE) transplantation, normally on human amniotic membrane. Clinical outcomes using amnion can be unreliable and so we have developed an alternative tissue equivalent (TE), RAFT (Real Architecture for 3D Tissue), which supports hLE expansion, and stratification when airlifted. Human limbal fibroblasts (hLF) may be incorporated into RAFT TEs, where they support overlying hLE and improve phenotype. However, the impact of neither airlifting nor hLF on hLE function has been investigated. hLE on RAFT TEs (±hLF and airlifting) were wounded using heptanol and re-epithelialisation (fluorescein diacetate staining), and percentage putative stem cell marker p63α and proliferative marker Ki67 expression (wholemount immunohistochemistry), measured. Airlifted, hLF- RAFT TEs were unable to close the wound and p63α expression was 7 ± 0.2% after wounding. Conversely, non-airlifted, hLF- RAFT TEs closed the wound within 9 days and p63α expression was higher at 22 ± 5% (p < 0.01). hLE on both hLF- and hLF+ RAFT TEs (non-airlifted) closed the wound and p63α expression was 26 ± 8% and 36 ± 3% respectively (ns). Ki67 expression by hLE increased from 1.3 ± 0.5% before wounding to 7.89 ± 2.53% post-wounding for hLF- RAFT TEs (p < 0.01), and 0.8 ± 0.08% to 17.68 ± 10.88% for hLF+ RAFT TEs (p < 0.05), suggesting that re-epithelialisation was a result of proliferation. These data suggest that neither airlifting nor hLF are necessarily required to maintain a functional epithelium on RAFT TEs, thus simplifying and shortening the production process. This is important when working towards clinical application of regenerative medicine products.

  3. Limbal Fibroblasts Maintain Normal Phenotype in 3D RAFT Tissue Equivalents Suggesting Potential for Safe Clinical Use in Treatment of Ocular Surface Failure.

    PubMed

    Massie, Isobel; Dale, Sarah B; Daniels, Julie T

    2015-06-01

    Limbal epithelial stem cell deficiency can cause blindness, but transplantation of these cells on a carrier such as human amniotic membrane can restore vision. Unfortunately, clinical graft manufacture using amnion can be inconsistent. Therefore, we have developed an alternative substrate, Real Architecture for 3D Tissue (RAFT), which supports human limbal epithelial cells (hLE) expansion. Epithelial organization is improved when human limbal fibroblasts (hLF) are incorporated into RAFT tissue equivalent (TE). However, hLF have the potential to transdifferentiate into a pro-scarring cell type, which would be incompatible with therapeutic transplantation. The aim of this work was to assess the scarring phenotype of hLF in RAFT TEs in hLE+ and hLE- RAFT TEs and in nonairlifted and airlifted RAFT TEs. Diseased fibroblasts (dFib) isolated from the fibrotic conjunctivae of ocular mucous membrane pemphigoid (Oc-MMP) patients were used as a pro-scarring positive control against which hLF were compared using surrogate scarring parameters: matrix metalloproteinase (MMP) activity, de novo collagen synthesis, α-smooth muscle actin (α-SMA) expression, and transforming growth factor-β (TGF-β) secretion. Normal hLF and dFib maintained different phenotypes in RAFT TE. MMP-2 and -9 activity, de novo collagen synthesis, and α-SMA expression were all increased in dFib cf. normal hLF RAFT TEs, although TGF-β1 secretion did not differ between normal hLF and dFib RAFT TEs. Normal hLF do not progress toward a scarring-like phenotype during culture in RAFT TEs and, therefore, may be safe to include in therapeutic RAFT TE, where they can support hLE, although in vivo work is required to confirm this. dFib RAFT TEs (used in this study as a positive control) may be useful toward the development of an ex vivo disease model of Oc-MMP.

  4. Effect of Tissue Composition on Dose Distribution in Electron Beam Radiotherapy

    PubMed Central

    Ghorbani, M.; Tabatabaei, Z. S.; Vejdani Noghreiyan, A.; Vosoughi, H.; Knaup, C.

    2015-01-01

    Objective The aim of this study is to evaluate the effect of tissue composition on dose distribution in electron beam radiotherapy. Methods A Siemens Primus linear accelerator and a phantom were simulated using MCNPX Monte Carlo code. In a homogeneous cylindrical phantom, six types of soft tissue and three types of tissue-equivalent materials were investigated. The tissues included muscle (skeletal), adipose tissue, blood (whole), breast tissue, soft tissue (9-components) and soft tissue (4-component). The tissue-equivalent materials were water, A-150 tissue-equivalent plastic and perspex. Electron dose relative to dose in 9-component soft tissue at various depths on the beam’s central axis was determined for 8, 12, and 14 MeV electron energies. Results The results of relative electron dose in various materials relative to dose in 9-component soft tissue were reported for 8, 12 and 14 MeV electron beams as tabulated data. While differences were observed between dose distributions in various soft tissues and tissue-equivalent materials, which vary with the composition of material, electron energy and depth in phantom, they can be ignored due to the incorporated uncertainties in Monte Carlo calculations. Conclusion Based on the calculations performed, differences in dose distributions in various soft tissues and tissue-equivalent materials are not significant. However, due to the difference in composition of various materials, further research in this field with lower uncertainties is recommended. PMID:25973407

  5. Establishing Substantial Equivalence: Transcriptomics

    NASA Astrophysics Data System (ADS)

    Baudo, María Marcela; Powers, Stephen J.; Mitchell, Rowan A. C.; Shewry, Peter R.

    Regulatory authorities in Western Europe require transgenic crops to be substantially equivalent to conventionally bred forms if they are to be approved for commercial production. One way to establish substantial equivalence is to compare the transcript profiles of developing grain and other tissues of transgenic and conventionally bred lines, in order to identify any unintended effects of the transformation process. We present detailed protocols for transcriptomic comparisons of developing wheat grain and leaf material, and illustrate their use by reference to our own studies of lines transformed to express additional gluten protein genes controlled by their own endosperm-specific promoters. The results show that the transgenes present in these lines (which included those encoding marker genes) did not have any significant unpredicted effects on the expression of endogenous genes and that the transgenic plants were therefore substantially equivalent to the corresponding parental lines.

  6. A 150-base pair 5' region of the MHC class I HLA-B7 gene is sufficient to direct tissue-specific expression and locus control region activity: the alpha site determines efficient expression and in vivo occupancy at multiple cis-active sites throughout this region.

    PubMed

    Kushida, M M; Dey, A; Zhang, X L; Campbell, J; Heeney, M; Carlyle, J; Ganguly, S; Ozato, K; Vasavada, H; Chamberlain, J W

    1997-11-15

    To characterize cis- and trans-acting mechanisms that regulate MHC class I transcription during development and in adult tissues, we have used transgenic mice to study a series of human MHC (HLA)-B7 class I gene constructs. Previous studies identified the 5' -0.66-kb to -0.075-kb region as sufficient to direct appropriate and efficient tissue-specific levels of HLA-B7 RNA relative to H-2 class I. Results here show that DNA 5' of -0.26 kb is not required for any aspect of expression. As the expression level correlated with the transgene copy number, was comparable to H-2 or a per-gene copy basis and was independent of integration site, the -0.075 to -0.26-kb segment also functions as a locus control region. With this region, sequences 3' of -0.075 kb, possibly at the promoter, appear to direct the appropriate tissue distribution. Of conserved sequences in the -0.075 to -0.26-kb region, enhancer B box is nonessential. In contrast, in vivo "footprinting" implicated region I/ enhancer A/NF-kappaB, IFN consensus/response sequence, and alpha in class I regulation as they are "occupied" in a tissue-specific pattern that correlates with expression. Mutation of alpha leads to decreased expression and loss of occupancy not only at alpha but also at region I/enhancer A/NF-kappaB and IFN consensus/response sequence. Thus, site alpha is an essential class I regulatory element, the dominant function of which is to mediate tissue-specific occupancy at multiple adjacent cis-active sites, possibly by facilitating stable synergistic interactions between factors at these distinct elements.

  7. Microscopic study of superdeformation in the A = 150 mass region

    SciTech Connect

    Rigollet, C.; Gall, B.; Bonche, P.

    1996-12-31

    The authors are presently investigating the properties of superdeformed (SD) nuclear states in the A=150 mass region. For that purpose, they use the cranked HFB method in which pairing correlations are treated dynamically by means of the Lipkin-Nogami prescription. Their goal is to take advantage of the large amount of experimental data to test the predictive power of their microscopic approach and of the effective interaction. In the present communication, they focus on {sup 152}Dy and {sup 153}Dy for which there are recent experimental data. In particular lifetime measurements have allowed to extract electric quadrupole moments. The new Skyrme effective force SLy4 is used to describe the nucleon-nucleon interaction, while for the pairing channel the authors use a density-dependent zero-range interaction.

  8. Comparison of full-field digital mammography to screen-film mammography with respect to contrast and spatial resolution in tissue equivalent breast phantoms.

    PubMed

    Kuzmiak, Cherie M; Pisano, Etta D; Cole, Elodia B; Zeng, Donglin; Burns, Charles B; Roberto, Craig; Pavic, Dag; Lee, Yeonhee; Seo, Bo Kyoung; Koomen, Marcia; Washburn, David

    2005-10-01

    To determine if the improved contrast resolution of full-field digital mammography (FFDM) with reduced spatial resolution allows for superior or equal phantom object detection compared with screen-film mammography (SFM). Tissue equivalent breast phantoms simulating an adipose to glandular ratio of 50/50,30/70, and 20/80 were imaged according to each manufacturers' recommendation with four full-field digital mammography units (Fuji, Sectra, Fischer, and General Electric) and a screen-film mammography unit (MammoMatII 2000, Siemens, Munich, Germany). A total of 20 images were obtained in both hard- and soft-copy formats. For the purpose of soft-copy display, the screen-film hard-copy images were digitized with a 50 microm micron scanner. Six radiologists, experts in breast imaging, and three physicists, experts in scoring mammography phantoms, participated in a reader study where each reader scored each phantom for visibility of line-pairs and for 24 objects (fibers, clusters of specks, and masses). The data were recorded, entered into a database, and analyzed by a mixed-effect model. The limiting spatial resolution in line-pairs per millimeter visible with the digital units was less, regardless of display modality used, than that provided by the screen-film unit. The difference was statistically significant for the General Electric (p < 0.01) and Fuji digital mammography units (p = 0.03). With respect to the number of visible objects, a statistically significant higher number could be detected with the screen-film unit as compared to the Fischer (p < 0.01) and Sectra (p < 0.01) digital mammography units, but there was no significant difference between the other digital units and screen film. Overall, there was significantly better performance on the 50/50 phantom than with the 30/70 and 20/80 phantoms (p = 0.01, p < 0.01) for object visibility. For the digital mammography units, soft-copy display performed better than hard-copy display for the Fischer and Sectra

  9. Derivation of extracellular fluid volume fraction and equivalent dielectric constant of the cell membrane from dielectric properties of the human body. Part 2: A preliminary study for tracking the progression of surgical tissue injury.

    PubMed

    Tatara, T; Tsuzaki, K

    2000-07-01

    A study is conducted to determine whether the extracellular fluid (ECF) volume fraction and equivalent dielectric constant of the cell membrane epsilon m, derived from the dielectric properties of the human body can track the progression of surgical tissue injury. Frequency-dependent dielectric constants and electrical conductivities of body segments are obtained at surgical (trunk) and non-surgical sites (arm and leg) from five patients who have undergone oesophageal resections, before and at the end of surgery and on the day after the operation. The ECF volume fraction and the equivalent epsilon m of body segments are estimated by fitting the dielectric data for body segments to the cell suspension model incorporating fat tissue, and their time-course changes are compared between body segments. By the day after the operation, the estimated ECF volume fraction has increased in all body segments compared with that before surgery, by 0.13 in the arm, 0.16 in the trunk and 0.14 in the leg (p < 0.05), indicating postoperative fluid accumulation in the extracellular space. In contrast, the estimated equivalent epsilon m shows a different time course between body segments on the day after the operation, characterised by a higher change ratio of epsilon m of the trunk (1.34 +/- 0.66, p < 0.05), from that of the arm (0.66 +/- 0.34) and leg (0.61 +/- 0.11). The results suggest that the equivalent epsilon m of a body segment at a surgical site can track pathophysiological cell changes following surgical tissue injury.

  10. Plutonium 239 Equivalency Calculations

    SciTech Connect

    Wen, J

    2011-05-31

    This document provides the basis for converting actual weapons grade plutonium mass to a plutonium equivalency (PuE) mass of Plutonium 239. The conversion can be accomplished by performing calculations utilizing either: (1) Isotopic conversions factors (CF{sub isotope}), or (2) 30-year-old weapons grade conversion factor (CF{sub 30 yr}) Both of these methods are provided in this document. Material mass and isotopic data are needed to calculate PuE using the isotopic conversion factors, which will provide the actual PuE value at the time of calculation. PuE is the summation of the isotopic masses times their associated isotopic conversion factors for plutonium 239. Isotopic conversion factors are calculated by a normalized equation, relative to Plutonium 239, of specific activity (SA) and cumulated dose inhalation affects based on 50-yr committed effective dose equivalent (CEDE). The isotopic conversion factors for converting weapons grade plutonium to PuE are provided in Table-1. The unit for specific activity (SA) is curies per gram (Ci/g) and the isotopic SA values come from reference [1]. The cumulated dose inhalation effect values in units of rem/Ci are based on 50-yr committed effective dose equivalent (CEDE). A person irradiated by gamma radiation outside the body will receive a dose only during the period of irradiation. However, following an intake by inhalation, some radionuclides persist in the body and irradiate the various tissues for many years. There are three groups CEDE data representing lengths of time of 0.5 (D), 50 (W) and 500 (Y) days, which are in reference [2]. The CEDE values in the (W) group demonstrates the highest dose equivalent value; therefore they are used for the calculation.

  11. Use of maxillofacial laboratory materials to construct a tissue-equivalent head phantom with removable titanium implantable devices for use in verification of the dose of intensity-modulated radiotherapy.

    PubMed

    Morris, K

    2017-02-25

    The dose of radiotherapy is often verified by measuring the dose of radiation at specific points within a phantom. The presence of high-density implant materials such as titanium, however, may cause complications both during calculation and delivery of the dose. Numerous studies have reported photon/electron backscatter and alteration of the dose by high-density implants, but we know of no evidence of a dosimetry phantom that incorporates high density implants or fixtures. The aim of the study was to design and manufacture a tissue-equivalent head phantom for use in verification of the dose in radiotherapy using a combination of traditional laboratory materials and techniques and 3-dimensional technology that can incorporate titanium maxillofacial devices. Digital designs were used together with Mimics® 18.0 (Materialise NV) and FreeForm® software. DICOM data were downloaded and manipulated into the final pieces of the phantom mould. Three-dimensional digital objects were converted into STL files and exported for additional stereolithography. Phantoms were constructed in four stages: material testing and selection, design of a 3-dimensional mould, manufacture of implants, and final fabrication of the phantom using traditional laboratory techniques. Three tissue-equivalent materials were found and used to successfully manufacture a suitable phantom with interchangeable sections that contained three versions of titanium maxillofacial implants. Maxillofacial and other materials can be used to successfully construct a head phantom with interchangeable titanium implant sections for use in verification of doses of radiotherapy.

  12. Investigation of mass attenuation coefficient of almond gum bonded Rhizophora spp. particleboard as equivalent human tissue using XRF technique in the 16.6-25.3 keV photon energy.

    PubMed

    Ababneh, Baker; Tajuddin, Abd Aziz; Hashim, Rokiah; Shuaib, Ibrahim Lutfi

    2016-12-01

    This paper reports the novel use of almond gum as a binder in manufacturing Rhizophora spp. particleboard. X-ray fluorescence spectroscopy was employed for analysis under photon energy range of 16.6-25.3 keV. Results showed that almond gum-bonded Rhizophora spp. particleboard can be used as tissue-equivalent phantom in diagnostic radiation. The calculated mass attenuation coefficients of the particleboards were consistent with the values of water calculated using XCOM program for the same photon energies, with p values of 0.056, 0.069, and 0.077 for samples A8, C0, and C8, respectively. However, no direct relationship was found between the percentage of adhesive and the mass attenuation coefficient. The results positively supported the use of almond gum as a binding agent in the fabrication of particleboards, which can be used as a phantom material in dosimetric and quality control applications.

  13. Comparisons of LET Distributions for Protons with Energies between50 and 200 MeV Determined Using a Spherical Tissue-EquivalentProportional Counter (TEPC) and a Position-Sensitive Silicon Spectrometer(RRMD-III)

    SciTech Connect

    Borak, Thomas B.; Doke, Tadayoshi; Fuse, T.; Guetersloh, StephenB.; Heilbronn, Lawrence H.; Hara, K.; Moyers, Michael; Suzuki, S.; Taddei, Phillip; Terasawa, K.; Zeitlin, Cary J.

    2004-12-01

    Experiments have been performed to measure the response of a spherical tissue-equivalent proportional counter (TEPC) and a silicon-based LET spectrometer (RRMD-III) to protons with energies ranging from 50 200 MeV. This represents a large portion of the energy distribution for trapped protons encountered by astronauts in low-Earth orbit. The beam energies were obtained using plastic polycarbonate degraders with a monoenergetic beam that was extracted from a proton synchrotron. The LET spectrometer provided excellent agreement with the expected LET distribution emerging from the energy degraders. The TEPC cannot measure the LET distribution directly. However, the frequency mean value of lineal energy, y bar f, provided a good approximation to LET. This is in contrast to previous results for high-energy heavy ions wherey barf underestimated LET, whereas the dose-averaged lineal energy, y barD, provided a good approximation to LET.

  14. Hydrogen-rich water achieves cytoprotection from oxidative stress injury in human gingival fibroblasts in culture or 3D-tissue equivalents, and wound-healing promotion, together with ROS-scavenging and relief from glutathione diminishment.

    PubMed

    Xiao, Li; Miwa, Nobuhiko

    2017-04-01

    The aim of the present study is to investigate protective effects of hydrogen-rich water (HW) against reactive oxygen species (ROS)-induced cellular harmful events and cell death in human gingival fibroblasts (HGF) and three-dimensional (3D-) gingival tissue equivalents. HW was prepared with a magnesium stick in 600-mL double distilled water (DDW) overnight. Dissolved hydrogen was about 1460 ± 50 μg/L versus approximately 1600 μg/L for the saturated hydrogen. Under cell-free conditions, HW, dose-dependently, significantly scavenged peroxyl radicals (ROO·) derived from 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). Extract from HW-treated HGF cells scavenged ROO· more markedly than that from DDW-treated cells, suggesting that HW can increase the intracellular antioxidant capacity. Hydrogen peroxide dose-dependently increased the intracellular ROS generation, which was significantly repressed by HW, both in the cytoplasm and nuclei. LIVE/DEAD staining and our original cell viability dye-extraction assay showed that HW significantly protected HGF cells from hydrogen peroxide-induced cell death. Hydrogen peroxide also diminished the contents of intracellular glutathione, which were appreciably relieved by HW-pretreatment. Additionally, HW noticeably prevented cumene hydroperoxide-induced generation of cellular ROS in epidermis parts of 3D-gingival equivalents. The in vitro scratch assay showed that HW was able to diminish physical injury-induced ROS generation and promote wound healing in HGF cell monolayer sheets. In summary, HW was able to increase intracellular antioxidative capacity and to protect cells and tissue from oxidative damage. Thus, HW might be used for prevention/treatment of oxidative stress-related diseases.

  15. Equivalence principles and electromagnetism

    NASA Technical Reports Server (NTRS)

    Ni, W.-T.

    1977-01-01

    The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

  16. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV.

    PubMed

    Seidenbusch, M; Harder, D; Regulla, D

    2014-05-01

    The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual

  17. PATHOGEN EQUIVALENCY COMMITTEE UPDATE: PFRP EQUIVALENCY DETERMINATIONS

    EPA Science Inventory

    This presentation will:

    Review the mandate of the Pathogen Equivalency Committee
    Review the PEC's current membership of 10
    Discuss how a typical application is evaluated
    Note where information can be found
    List present deliberations/applications and describe t...

  18. Active microwave water equivalence

    NASA Technical Reports Server (NTRS)

    Boyne, H. S.; Ellerbruch, D. A.

    1980-01-01

    Measurements of water equivalence using an active FM-CW microwave system were conducted over the past three years at various sites in Colorado, Wyoming, and California. The measurement method is described. Measurements of water equivalence and stratigraphy are compared with ground truth. A comparison of microwave, federal sampler, and snow pillow measurements at three sites in Colorado is described.

  19. SU-E-T-409: Evaluation of Tissue Composition Effect On Dose Distribution in Radiotherapy with 6 MV Photon Beam of a Medical Linac

    SciTech Connect

    Ghorbani, M; Tabatabaei, Z; Noghreiyan, A Vejdani; Meigooni, A Soleimani

    2015-06-15

    Purpose: The aim of this study is to evaluate soft tissue composition effect on dose distribution for various soft tissues and various depths in radiotherapy with 6 MV photon beam of a medical linac. Methods: A phantom and Siemens Primus linear accelerator were simulated using MCNPX Monte Carlo code. In a homogeneous cubic phantom, six types of soft tissue and three types of tissue-equivalent materials were defined separately. The soft tissues were muscle (skeletal), adipose tissue, blood (whole), breast tissue, soft tissue (9-component) and soft tissue (4-component). The tissue-equivalent materials included: water, A-150 tissue-equivalent plastic and perspex. Photon dose relative to dose in 9-component soft tissue at various depths on the beam’s central axis was determined for the 6 MV photon beam. The relative dose was also calculated and compared for various MCNPX tallies including,F8, F6 and,F4. Results: The results of the relative photon dose in various materials relative to dose in 9-component soft tissue and using different tallies are reported in the form of tabulated data. Minor differences between dose distributions in various soft tissues and tissue-equivalent materials were observed. The results from F6 and F4 were practically the same but different with,F8 tally. Conclusion: Based on the calculations performed, the differences in dose distributions in various soft tissues and tissue-equivalent materials are minor but they could be corrected in radiotherapy calculations to upgrade the accuracy of the dosimetric calculations.

  20. Helical Tomotherapy vs. Intensity-Modulated Proton Therapy for Whole Pelvis Irradiation in High-Risk Prostate Cancer Patients: Dosimetric, Normal Tissue Complication Probability, and Generalized Equivalent Uniform Dose Analysis

    SciTech Connect

    Widesott, Lamberto; Pierelli, Alessio; Fiorino, Claudio; Lomax, Antony J.; Amichetti, Maurizio; Cozzarini, Cesare; Soukup, Martin; Schneider, Ralf; Hug, Eugen; Di Muzio, Nadia; Calandrino, Riccardo; Schwarz, Marco

    2011-08-01

    Purpose: To compare intensity-modulated proton therapy (IMPT) and helical tomotherapy (HT) treatment plans for high-risk prostate cancer (HRPCa) patients. Methods and Materials: The plans of 8 patients with HRPCa treated with HT were compared with IMPT plans with two quasilateral fields set up (-100{sup o}; 100{sup o}) and optimized with the Hyperion treatment planning system. Both techniques were optimized to simultaneously deliver 74.2 Gy/Gy relative biologic effectiveness (RBE) in 28 fractions on planning target volumes (PTVs)3-4 (P + proximal seminal vesicles), 65.5 Gy/Gy(RBE) on PTV2 (distal seminal vesicles and rectum/prostate overlapping), and 51.8 Gy/Gy(RBE) to PTV1 (pelvic lymph nodes). Normal tissue calculation probability (NTCP) calculations were performed for the rectum, and generalized equivalent uniform dose (gEUD) was estimated for the bowel cavity, penile bulb and bladder. Results: A slightly better PTV coverage and homogeneity of target dose distribution with IMPT was found: the percentage of PTV volume receiving {>=}95% of the prescribed dose (V{sub 95%}) was on average >97% in HT and >99% in IMPT. The conformity indexes were significantly lower for protons than for photons, and there was a statistically significant reduction of the IMPT dosimetric parameters, up to 50 Gy/Gy(RBE) for the rectum and bowel and 60 Gy/Gy(RBE) for the bladder. The NTCP values for the rectum were higher in HT for all the sets of parameters, but the gain was small and in only a few cases statistically significant. Conclusions: Comparable PTV coverage was observed. Based on NTCP calculation, IMPT is expected to allow a small reduction in rectal toxicity, and a significant dosimetric gain with IMPT, both in medium-dose and in low-dose range in all OARs, was observed.

  1. Equivalent Neutral Wind

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Tang, Wenqing

    1996-01-01

    The definition of equivalent neutral wind and the rationale for using it as the geophysical product of a spaceborne scatterometer are reviewed. The differences between equivalent neutral wind and actual wind, which are caused by atmospheric density stratification, are demonstrated with measurements at selected locations. A method of computing this parameter from ship and buoy measurements is described and some common fallacies in accounting for the effects of atmospheric stratification on wind shear are discussed. The computer code for the model to derive equivalent neutral wind is provided.

  2. Neutron dose equivalent meter

    DOEpatents

    Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

    1996-01-01

    A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

  3. Equivalent Dynamic Models.

    PubMed

    Molenaar, Peter C M

    2017-02-16

    Equivalences of two classes of dynamic models for weakly stationary multivariate time series are discussed: dynamic factor models and autoregressive models. It is shown that exploratory dynamic factor models can be rotated, yielding an infinite set of equivalent solutions for any observed series. It also is shown that dynamic factor models with lagged factor loadings are not equivalent to the currently popular state-space models, and that restriction of attention to the latter type of models may yield invalid results. The known equivalent vector autoregressive model types, standard and structural, are given a new interpretation in which they are conceived of as the extremes of an innovating type of hybrid vector autoregressive models. It is shown that consideration of hybrid models solves many problems, in particular with Granger causality testing.

  4. ETV Report: Siemens Model V-40R-A150 Open Channel UV System

    EPA Science Inventory

    Verification testing of the Siemens Barrier Sunlight V-40R-A150 UV System was completed at the UV Validation and Research Center of New York (UV Center), located in Johnstown, NY. The V-40R System supplied by Siemens utilizes 40 high-output, low-pressure amalgam lamps, oriented ...

  5. PATHOGEN EQUIVALENCY COMMITTEE (PEC)

    EPA Science Inventory

    The U.S. Environmental Protection Agency created the PEC in 1985 to make recommendations to EPA and State managers on the equivalency of unproven sewage sludge disinfection technologies/processes to either a Process to Significantly Reduce Pathogens (PSRP) or a Process to Further...

  6. Equivalent Colorings with "Maple"

    ERIC Educational Resources Information Center

    Cecil, David R.; Wang, Rongdong

    2005-01-01

    Many counting problems can be modeled as "colorings" and solved by considering symmetries and Polya's cycle index polynomial. This paper presents a "Maple 7" program link http://users.tamuk.edu/kfdrc00/ that, given Polya's cycle index polynomial, determines all possible associated colorings and their partitioning into equivalence classes. These…

  7. Five Equivalent d Orbitals

    ERIC Educational Resources Information Center

    Pauling, Linus; McClure, Vance

    1970-01-01

    Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)

  8. Establishing Substantial Equivalence: Metabolomics

    NASA Astrophysics Data System (ADS)

    Beale, Michael H.; Ward, Jane L.; Baker, John M.

    Modern ‘metabolomic’ methods allow us to compare levels of many structurally diverse compounds in an automated fashion across a large number of samples. This technology is ideally suited to screening of populations of plants, including trials where the aim is the determination of unintended effects introduced by GM. A number of metabolomic methods have been devised for the determination of substantial equivalence. We have developed a methodology, using [1H]-NMR fingerprinting, for metabolomic screening of plants and have applied it to the study of substantial equivalence of field-grown GM wheat. We describe here the principles and detail of that protocol as applied to the analysis of flour generated from field plots of wheat. Particular emphasis is given to the downstream data processing and comparison of spectra by multivariate analysis, from which conclusions regarding metabolome changes due to the GM can be assessed against the background of natural variation due to environment.

  9. Obtaining an equivalent beam

    NASA Technical Reports Server (NTRS)

    Butler, Thomas G.

    1990-01-01

    In modeling a complex structure the researcher was faced with a component that would have logical appeal if it were modeled as a beam. The structure was a mast of a robot controlled gantry crane. The structure up to this point already had a large number of degrees of freedom, so the idea of conserving grid points by modeling the mast as a beam was attractive. The researcher decided to make a separate problem of of the mast and model it in three dimensions with plates, then extract the equivalent beam properties by setting up the loading to simulate beam-like deformation and constraints. The results could then be used to represent the mast as a beam in the full model. A comparison was made of properties derived from models of different constraints versus manual calculations. The researcher shows that the three-dimensional model is ineffective in trying to conform to the requirements of an equivalent beam representation. If a full 3-D plate model were used in the complete representation of the crane structure, good results would be obtained. Since the attempt is to economize on the size of the model, a better way to achieve the same results is to use substructuring and condense the mast to equivalent end boundary and intermediate mass points.

  10. X-ray phase contrast imaging of the breast: Analysis of tissue simulating materials

    SciTech Connect

    Vedantham, Srinivasan; Karellas, Andrew

    2013-04-15

    that of adipose tissue, the tissue-equivalent material better approximated the adipose tissue in terms of {mu}. Polymethyl methacrylate, a commonly used tissue substitute, exhibited {delta} greater than fibroglandular tissue by {approx}12%. The A-150 plastic closely approximated the skin. Several materials exhibited {delta} between that of adipose and fibroglandular tissue. However, there was an energy-dependent mismatch in terms of equivalent fibroglandular weight fraction between {delta} and {mu} for these materials. For microcalcifications, aluminum and calcium carbonate were observed to straddle the {delta} and {mu} of calcium oxalate and calcium hydroxyapatite. Aluminum oxide, commonly used to represent microcalcifications in the American College of Radiology recommended phantoms for accreditation exhibited {delta} greater than calcium hydroxyapatite by {approx}23%. Conclusions: A breast phantom comprising A-150 plastic to represent the skin, commercially available adipose and fibroglandular tissue-equivalent formulations to represent adipose and fibroglandular tissue, respectively, was found to be best suited for x-ray phase-sensitive imaging of the breast. Calcium carbonate or aluminum can be used to represent microcalcifications.

  11. X-ray phase contrast imaging of the breast: Analysis of tissue simulating materials1

    PubMed Central

    Vedantham, Srinivasan; Karellas, Andrew

    2013-01-01

    material better approximated the adipose tissue in terms of μ. Polymethyl methacrylate, a commonly used tissue substitute, exhibited δ greater than fibroglandular tissue by ∼12%. The A-150 plastic closely approximated the skin. Several materials exhibited δ between that of adipose and fibroglandular tissue. However, there was an energy-dependent mismatch in terms of equivalent fibroglandular weight fraction between δ and μ for these materials. For microcalcifications, aluminum and calcium carbonate were observed to straddle the δ and μ of calcium oxalate and calcium hydroxyapatite. Aluminum oxide, commonly used to represent microcalcifications in the American College of Radiology recommended phantoms for accreditation exhibited δ greater than calcium hydroxyapatite by ∼23%. Conclusions: A breast phantom comprising A-150 plastic to represent the skin, commercially available adipose and fibroglandular tissue-equivalent formulations to represent adipose and fibroglandular tissue, respectively, was found to be best suited for x-ray phase-sensitive imaging of the breast. Calcium carbonate or aluminum can be used to represent microcalcifications. PMID:23556900

  12. Comments on TNT Equivalence

    SciTech Connect

    Cooper, P.W.

    1994-07-01

    The term ``TNT Equivalence`` is used throughout the explosives and related industries to compare the effects of the output of a given explosive to that of TNT. This is done for technical design reasons in scaling calculation such as for the prediction of blast waves, craters, and structural response, and is also used as a basis for government regulations controlling the shipping, handling and storage of explosive materials, as well as for the siting and design of explosive facilities. TNT equivalence is determined experimentally by several different types of tests, the most common of which include: plate dent, ballistic mortar, trauzl, sand crush, and air blast. All of these tests do not necessarily measure the same output property of the sample explosive. As examples of this, some tests depend simply upon the CJ pressure, some depend upon the PV work in the CJ zone and in the Taylor wave behind the CJ plane, some are functions of the total work which includes that from secondary combustion in the air mixing region of the fireball and are acutely effected by the shape of the pressure-time profile of the wave. Some of the tests incorporate systematic errors which are not readily apparent, and which have a profound effect upon skewing the resultant data. Further, some of the tests produce different TNT Equivalents for the same explosive which are a function of the conditions at which the test is run. This paper describes the various tests used, discusses the results of each test and makes detailed commentary on what the test is actually measuring, how the results may be interpreted, and if and how these results can be predicted by first principals based calculations. Extensive data bases are referred to throughout the paper and used in examples for each point in the commentaries.

  13. Local unitary equivalence of quantum states and simultaneous orthogonal equivalence

    NASA Astrophysics Data System (ADS)

    Jing, Naihuan; Yang, Min; Zhao, Hui

    2016-06-01

    The correspondence between local unitary equivalence of bipartite quantum states and simultaneous orthogonal equivalence is thoroughly investigated and strengthened. It is proved that local unitary equivalence can be studied through simultaneous similarity under projective orthogonal transformations, and four parametrization independent algorithms are proposed to judge when two density matrices on ℂd1 ⊗ ℂd2 are locally unitary equivalent in connection with trace identities, Kronecker pencils, Albert determinants and Smith normal forms.

  14. Optimization of silver nanoparticles production by laser ablation in water using a 150-ps laser

    NASA Astrophysics Data System (ADS)

    Stašić, J.; Živković, Lj.; Trtica, M.

    2016-12-01

    Silver nanoparticles were synthesized by laser ablation in liquid (water) using a 150-ps Nd:YAG laser. Due to their extraordinary characteristics, especially when obtained by this method providing high purity and high stability of colloids, silver NPs are nowadays highly important in various applications. The objective of this study was to optimize the process parameters in order to achieve the highest possible yield while retaining small particle size. Yield/mass concentration of the obtained particles was measured depending on different parameters: time of irradiation, pulse energy, position regarding the focus, and number of irradiation locations. The conditions providing relatively high yield, small particle size, highest production rate, and highest efficiency are 7 mJ, 15-min irradiation time (9000 pulses), and target position ˜4 mm in front of the lens focus. The results are compared with the results obtained by the longer nanosecond as well as the ultrashort pulsed lasers. A possible physical explanation is given.

  15. Depleted Monolithic Pixels (DMAPS) in a 150 nm technology: lab and beam results

    NASA Astrophysics Data System (ADS)

    Obermann, T.; Hemperek, T.; Hügging, F.; Krüger, H.; Pohl, D.-L.; Schwenker, B.; Wermes, N.

    2017-01-01

    The fully depleted monolithic active pixel sensor (DMAPS) is a new concept integrating full CMOS circuitry onto a fully depletable silicon substrate wafer. The realization of prototypes of the DMAPS concept relies on the availability of multiple well CMOS processes and high resistive substrates. The CMOS foundry ESPROS Photonics offers both and was chosen for prototyping. Two prototypes, EPCB01 and EPCB02, were developed in a 150 nm process on a high resistive n-type wafer of 50 μm thickness. The prototypes have 352 square pixels of 40 μm pitch and small n-well charge collection node with very low capacitance (n+-implantation size: 5 μm by 5 μm) and about 150 transistors per pixel (CSA and discriminator plus a small digital part).

  16. A 150 and 300 kW lightweight diesel aircraft engine design study

    NASA Technical Reports Server (NTRS)

    Brouwers, A. P.

    1980-01-01

    The diesel engine was reinvestigated as an aircraft powerplant through design study conducted to arrive at engine configurations and applicable advanced technologies. Two engines are discussed, a 300 kW six-cylinder engine for twin engine general aviation aircraft and a 150 kW four-cylinder engine for single engine aircraft. Descriptions of each engine include concept drawings, a performance analysis, stress and weight data, and a cost study. This information was used to develop two airplane concepts, a six-place twin and a four-place single engine aircraft. The aircraft study consists of installation drawings, computer generated performance data, aircraft operating costs, and drawings of the resulting airplanes. The performance data show a vast improvement over current gasoline-powered aircraft.

  17. Establishing Substantial Equivalence: Proteomics

    NASA Astrophysics Data System (ADS)

    Lovegrove, Alison; Salt, Louise; Shewry, Peter R.

    Wheat is a major crop in world agriculture and is consumed after processing into a range of food products. It is therefore of great importance to determine the consequences (intended and unintended) of transgenesis in wheat and whether genetically modified lines are substantially equivalent to those produced by conventional plant breeding. Proteomic analysis is one of several approaches which can be used to address these questions. Two-dimensional PAGE (2D PAGE) remains the most widely available method for proteomic analysis, but is notoriously difficult to reproduce between laboratories. We therefore describe methods which have been developed as standard operating procedures in our laboratory to ensure the reproducibility of proteomic analyses of wheat using 2D PAGE analysis of grain proteins.

  18. SU-E-T-353: Verification of Water Equivalent Thickness (WET) and Water Equivalent Spreadness (WES) of Proton Beam

    SciTech Connect

    Demez, N; Lee, T; Keppel, Cynthia

    2011-06-01

    Purpose: To verify calculated water equivalent thickness (WET) and water equivalent spreadness (WES) in various tissue equivalent media for proton therapy Methods: Water equivalent thicknesses (WET) of tissue equivalent materials have been calculated using the Bragg-Kleeman rule. Lateral spreadness and fluence reduction of proton beams both in those media were calculated using proton loss model (PLM) algorithm. In addition, we calculated lateral spreadness ratios with respect to that in water at the same WET depth and so the WES was defined. The WETs of those media for different proton beam energies were measured using MLIC (Multi-Layered Ionization Chamber). Also, fluence and field sizes in those materials of various thicknesses were measured with ionization chambers and films Results: Calculated WETs are in agreement with measured WETs within 0.5%. We found that water equivalent spreadness (WES) is constant and the fluence and field size measurements verify that fluence can be estimated using the concept of WES. Conclusions: Calculation of WET based on the Bragg-Kleeman rule as well as the constant WES of proton beams for tissue equivalent phantoms can be used to predict fluence and field sizes at the depths of interest both in tissue equivalent media accurately for clinically available protonenergies.

  19. Physeal bar equivalent.

    PubMed

    Peterson, Hamlet A; Shaughnessy, William J; Stans, Anthony A

    2016-09-29

    Premature partial physeal arrest without the formation of an osseous bar - physeal bar equivalent (PBE) - is uncommon. Four children with a PBE had an infection near the distal femoral physis before the age of 11 months. Some growth was achieved after resection of the PBE in each case. Of two cases diagnosed and treated early, one required only contralateral physeal arrests to achieve limb-length equality at maturity. The other, currently 8 years and 4 months old, has a 1.1-cm limb-length discrepancy 6 years after PBE resection and will require observation until maturity. Of two cases diagnosed and treated late, one required ipsilateral femoral lengthening and contralateral femoral shortening and physeal arrests to treat the limb-length discrepancy and angular deformity. The other, currently 7 years and 1 month old, has a 4.8-cm discrepancy and will need future surgical limb-length equalization. Early recognition and treatment of PBE is required to avoid severe limb-length inequality and angular deformity.

  20. Biomonitoring Equivalents for molybdenum.

    PubMed

    Hays, Sean M; Macey, Kristin; Poddalgoda, Devika; Lu, Ming; Nong, Andy; Aylward, Lesa L

    2016-06-01

    Molybdenum is an essential trace element for mammalian, plant, and other animal systems. The Institute of Medicine (IOM) has established an Estimated Average Requirement (EAR) to assure sufficient molybdenum intakes for human populations; however excessive exposures can cause toxicity. As a result, several agencies have established exposure guidance values to protect against molybdenum toxicity, including a Reference Dose (RfD), Tolerable Daily Intake (TDI) and a Tolerable Upper Intake Level (UL). Biomonitoring for molybdenum in blood or urine in the general population is being conducted by the Canadian Health Measures Survey (CHMS) and the U.S. National Health and Nutrition Examination Survey (NHANES). Using pharmacokinetic data from controlled human dosing studies, Biomonitoring Equivalents (BEs) were calculated for molybdenum in plasma, whole blood, and urine associated with exposure guidance values set to protect against both nutritional deficits and toxicity. The BEEAR values in plasma, whole blood and urine are 0.5, 0.45 and 22 μg/L, respectively. The BEs associated with toxicity range from 0.9 to 31 μg/L in plasma, 0.8-28 μg/L in whole blood and 200-7500 μg/L in urine. These values can be used to interpret molybdenum biomonitoring data from a nutritional and toxicity perspective.

  1. Biomonitoring Equivalents for selenium.

    PubMed

    Hays, Sean M; Macey, Kristin; Nong, Andy; Aylward, Lesa L

    2014-10-01

    Selenium is an essential nutrient for human health with a narrow range between essentiality and toxicity. Selenium is incorporated into several proteins that perform important functions in the body. With insufficient selenium intake, the most notable effect is Keshan disease, an endemic cardiomyopathy in children. Conversely, excessive selenium intake can result in selenosis, manifested as brittle nails and hair and gastro-intestinal disorders. As such, guidance values have been established to protect against both insufficient and excessive selenium exposures. Dietary Reference Intakes (DRIs) have been established as standard reference values for nutritional adequacy in North America. To protect against selenosis resulting from exposure to excessive amounts of selenium, several government and non-governmental agencies have established a range of guidance values. Exposure to selenium is primarily through the diet, but monitoring selenium intake is difficult. Biomonitoring is a useful means of assessing and monitoring selenium status for both insufficient and excessive exposures. However, to be able to interpret selenium biomonitoring data, levels associated with both DRIs and toxicity guidance values are required. Biomonitoring Equivalents (BEs) were developed for selenium in whole blood, plasma and urine. The BEs associated with assuring adequate selenium intake (Estimated Average Requirements - EAR) are 100, 80 and 10μg/L in whole blood, plasma and urine, respectively. The BEs associated with protection against selenosis range from 400 to 480μg/L in whole blood, 180-230μg/L in plasma, and 90-110μg/L in urine. These BE values can be used by both regulatory agencies and public health officials to interpret selenium biomonitoring data in a health risk context.

  2. Design assessment of a 150 kWt CFBC Test Unit

    SciTech Connect

    Batu, A.; Selcuk, N.; Kulah, G.

    2010-04-15

    For clean and efficient energy generation from coal, the most suitable technology known to date is 'Fluidized Bed Combustion' technology. Applications of circulating fluidized bed (CFB) combustion technology have been steadily increasing in both capacity and number over the past decade. Designs of these units have been based on the combustion tests carried out in pilot scale facilities to determine the combustion and desulfurization characteristics of coal and limestone reserves in CFB conditions. Similarly, utilization of Turkish lignites in CFB boilers necessitates adaptation of CFB combustion technology to these resources. However, the design of these test units are not based on firing coals with high ash, volatile matter and sulfur contents like Turkish lignites. For this purpose, a 150 kWt CFB combustor test unit is designed and constructed in Chemical Engineering Department of Middle East Technical University, based on the extensive experience acquired at the existing 0.3 MWt Bubbling Atmospheric Fluidized Bed Combustor (AFBC) Test Rig. Following the commissioning tests, a combustion test is carried out for investigation of combustion characteristics of Can lignite in CFB conditions and for assessment of the design of test unit. Comparison of the design outputs with experimental results reveals that most of the predictions and assumptions have acceptable agreement with the operating conditions. In conclusion, the performance of 150 kWt CFBC Test Unit is found to be satisfactory to be utilized for the long term research studies on combustion and desulfurization characteristics of indigenous lignite reserves in circulating fluidized bed combustors. (author)

  3. Structural Design and Analysis of a 150 kJ HTS SMES Cryogenic System

    NASA Astrophysics Data System (ADS)

    Han, Peng; Wu, Yu; Liu, Huajun; Li, Laifeng; Yang, Huihui

    A 150 kJ high temperature superconducting magnetic energy storage (HTS-SMES) system is under manufacturing in China. This paper focuses on the structural design and analysis of the SMES cryogenic system. The cryogenic system is designed and fabricated to maintain the working temperature. The system includes a vacuum vessel, its thermal radiation shield, its supporting devices, conduction plates, and current leads. Two G-M cryocoolers are used for the system cooling, the main one is connected to the HTS coils and the other is connected to the thermal shield and the lower ends of the current leads. In this study, the 3D models of the SMES cryogenic system were created with CATIA, a 3D model design software, and the analysis of the SMES cryogenic system was done by ANSYS. The mechanical analysis results on the vacuum vessel, suspension devices and supporting devices are presented, particularly the analyses on suspenders and shelf supports are of vital importance since the finished SMES system should meet vehicle-mounted requirements in long time transport. The heat load and the temperature distribution of the thermal shield were analyzed. A cooling experiment of the cryogenic system was made and the thermal shield was cooled down to about 50 K.

  4. Coenzyme Q10 production in a 150-l reactor by a mutant strain of Rhodobacter sphaeroides.

    PubMed

    Kien, Nguyen Ba; Kong, In-Soo; Lee, Min-Gyu; Kim, Joong Kyun

    2010-05-01

    For the commercial production of CoQ(10), batch-type fermentations were attempted in a 150-l fermenter using a mutant strain of R. sphaeroides. Optimum temperature and initial aeration rate were found to be 30 degrees C and 2 vvm, respectively. Under optimum fermentation conditions, the maximum value of specific CoQ(10) content was achieved reproducibly as 6.34 mg/g DCW after 24 h, with 3.02 g/l of DCW. During the fermentation, aeration shift (from the adequate aeration at the early growth phase to the limited aeration in active cellular metabolism) was a key factor in CoQ(10) production for scale-up. A higher value of the specific CoQ(10) content (8.12 mg/g DCW) was achieved in fed-batch fermentation and comparable to those produced by the pilot-scale fed-batch fermentations of A. tumefaciens, which indicated that the mutant strain of R. sphaeroides used in this study was a potential high CoQ(10) producer. This is the first detailed study to demonstrate a pilot-scale production of CoQ(10) using a mutant strain of R. sphaeroides.

  5. Estimating equivalence with quantile regression

    USGS Publications Warehouse

    Cade, B.S.

    2011-01-01

    Equivalence testing and corresponding confidence interval estimates are used to provide more enlightened statistical statements about parameter estimates by relating them to intervals of effect sizes deemed to be of scientific or practical importance rather than just to an effect size of zero. Equivalence tests and confidence interval estimates are based on a null hypothesis that a parameter estimate is either outside (inequivalence hypothesis) or inside (equivalence hypothesis) an equivalence region, depending on the question of interest and assignment of risk. The former approach, often referred to as bioequivalence testing, is often used in regulatory settings because it reverses the burden of proof compared to a standard test of significance, following a precautionary principle for environmental protection. Unfortunately, many applications of equivalence testing focus on establishing average equivalence by estimating differences in means of distributions that do not have homogeneous variances. I discuss how to compare equivalence across quantiles of distributions using confidence intervals on quantile regression estimates that detect differences in heterogeneous distributions missed by focusing on means. I used one-tailed confidence intervals based on inequivalence hypotheses in a two-group treatment-control design for estimating bioequivalence of arsenic concentrations in soils at an old ammunition testing site and bioequivalence of vegetation biomass at a reclaimed mining site. Two-tailed confidence intervals based both on inequivalence and equivalence hypotheses were used to examine quantile equivalence for negligible trends over time for a continuous exponential model of amphibian abundance. ?? 2011 by the Ecological Society of America.

  6. A 150-year variation of the Kuroshio transport inferred from coral nitrogen isotope signature

    NASA Astrophysics Data System (ADS)

    Yamazaki, Atsuko; Watanabe, Tsuyoshi; Tsunogai, Urumu; Iwase, Fumihito; Yamano, Hiroya

    2016-06-01

    The Kuroshio Current is a major global ocean current that drives the physical ocean-atmosphere system with heat transport from tropical to temperate zones in the North Pacific Ocean. We reconstructed the variability of the Kuroshio transport over the past 150 years using coral skeletal nitrogen isotopic composition (δ15Ncoral). A 150 year δ15Ncoral record (1859-2008 A.D.) is 4 times the length of the observational record (1971 to present) and could provide a direct comparison with global climate change, such as the Pacific Decadal Oscillation (PDO) index and El-Niño-Southern Oscillation (ENSO), through recent global warming. Coral cores from Porites were collected from Tatsukushi Bay in 2008 on the Pacific coast of Japan, which is located on the northern front of the Kuroshio Current. δ15Ncoral was used as a proxy to record the δ15N of nitrate (δ15Nnitrate) controlled by the upwelling of subtropical subsurface water (δ15Nnitrate; ~ +2 - +3‰), and δ15Ncoral was negatively correlated with observations of the Kuroshio transport (R = -0.69, P < 0.001) and the 2 year lagged PDO index (R = -0.63, P < 0.005) from 1972 to 2007. The 150 year record of δ15Ncoral suggested that the Kuroshio transport varied with ~25 year cycle, and the amplitude became more stable, and the volume was intensified through the twentieth century. The Kuroshio transport was intensified by the La Niña state in the early 1900s and by the El Niño-PDO state after the 1920s. Our results suggested that the Kuroshio transport was influenced by the combined climate modes of ENSO and PDO during the last century.

  7. Saponification equivalent of dasamula taila.

    PubMed

    Saxena, R B

    1994-07-01

    Saponification equivalent values of Dasamula taila are very useful for the technical and analytical work. It gives the mean molecular weight of the glycerides and acids present in Dasamula Taila. Saponification equivalent values of Dasamula taila are reported in different packings.

  8. Psychotropic dose equivalence in Japan.

    PubMed

    Inada, Toshiya; Inagaki, Ataru

    2015-08-01

    Psychotropic dose equivalence is an important concept when estimating the approximate psychotropic doses patients receive, and deciding on the approximate titration dose when switching from one psychotropic agent to another. It is also useful from a research viewpoint when defining and extracting specific subgroups of subjects. Unification of various agents into a single standard agent facilitates easier analytical comparisons. On the basis of differences in psychopharmacological prescription features, those of available psychotropic agents and their approved doses, and racial differences between Japan and other countries, psychotropic dose equivalency tables designed specifically for Japanese patients have been widely used in Japan since 1998. Here we introduce dose equivalency tables for: (i) antipsychotics; (ii) antiparkinsonian agents; (iii) antidepressants; and (iv) anxiolytics, sedatives and hypnotics available in Japan. Equivalent doses for the therapeutic effects of individual psychotropic compounds were determined principally on the basis of randomized controlled trials conducted in Japan and consensus among dose equivalency tables reported previously by psychopharmacological experts. As these tables are intended to merely suggest approximate standard values, physicians should use them with discretion. Updated information of psychotropic dose equivalence in Japan is available at http://www.jsprs.org/en/equivalence.tables/. [Correction added on 8 July 2015, after first online publication: A link to the updated information has been added.].

  9. Equivalence-Equivalence: Matching Stimuli with Same Discriminative Functions

    ERIC Educational Resources Information Center

    Carpentier, Franck; Smeets, Paul M.; Barnes-Holmes, Dermot

    2004-01-01

    Previous studies have shown that after being trained on A-B and A-C match-to-sample tasks, adults match not only same-class B and C stimuli (equivalence) but also BC compounds with same-class elements and with different-class elements (BC-BC). The assumption was that the BC-BC performances are based on matching equivalence and nonequivalence…

  10. Morita equivalence of noncommutative supertori

    NASA Astrophysics Data System (ADS)

    Chang-Young, Ee; Kim, Hoil; Nakajima, Hiroaki

    2010-06-01

    In this paper we study the extension of Morita equivalence of noncommutative tori to the supersymmetric case. The structure of the symmetry group yielding Morita equivalence appears to be intact but its parameter field becomes supersymmetrized having both body and soul parts. Our result is mainly in the two dimensional case in which noncommutative supertori have been constructed recently: The group SO(2,2,VZ0), where VZ0 denotes Grassmann even number whose body part belongs to Z, yields Morita equivalent noncommutative supertori in two dimensions.

  11. Morita equivalence of noncommutative supertori

    SciTech Connect

    Chang-Young, Ee; Kim, Hoil; Nakajima, Hiroaki

    2010-06-15

    In this paper we study the extension of Morita equivalence of noncommutative tori to the supersymmetric case. The structure of the symmetry group yielding Morita equivalence appears to be intact but its parameter field becomes supersymmetrized having both body and soul parts. Our result is mainly in the two dimensional case in which noncommutative supertori have been constructed recently: The group SO(2,2,V{sub Z}{sup 0}), where V{sub Z}{sup 0} denotes Grassmann even number whose body part belongs to Z, yields Morita equivalent noncommutative supertori in two dimensions.

  12. Optical metrics and projective equivalence

    SciTech Connect

    Casey, Stephen; Dunajski, Maciej; Gibbons, Gary; Warnick, Claude

    2011-04-15

    Trajectories of light rays in a static spacetime are described by unparametrized geodesics of the Riemannian optical metric associated with the Lorentzian spacetime metric. We investigate the uniqueness of this structure and demonstrate that two different observers, moving relative to one another, who both see the Universe as static may determine the geometry of the light rays differently. More specifically, we classify Lorentzian metrics admitting more than one hyper-surface orthogonal timelike Killing vector and analyze the projective equivalence of the resulting optical metrics. These metrics are shown to be projectively equivalent up to diffeomorphism if the static Killing vectors generate a group SL(2,R), but not projectively equivalent in general. We also consider the cosmological C metrics in Einstein-Maxwell theory and demonstrate that optical metrics corresponding to different values of the cosmological constant are projectively equivalent.

  13. Equivalent damage: A critical assessment

    NASA Technical Reports Server (NTRS)

    Laflen, J. R.; Cook, T. S.

    1982-01-01

    Concepts in equivalent damage were evaluated to determine their applicability to the life prediction of hot path components of aircraft gas turbine engines. Equivalent damage was defined as being those effects which influence the crack initiation life-time beyond the damage that is measured in uniaxial, fully-reversed sinusoidal and isothermal experiments at low homologous temperatures. Three areas of equivalent damage were examined: mean stress, cumulative damage, and multiaxiality. For each area, a literature survey was conducted to aid in selecting the most appropriate theories. Where possible, data correlations were also used in the evaluation process. A set of criteria was developed for ranking the theories in each equivalent damage regime. These criteria considered aspects of engine utilization as well as the theoretical basis and correlative ability of each theory. In addition, consideration was given to the complex nature of the loading cycle at fatigue critical locations of hot path components; this loading includes non-proportional multiaxial stressing, combined temperature and strain fluctuations, and general creep-fatigue interactions. Through applications of selected equivalent damage theories to some suitable data sets it was found that there is insufficient data to allow specific recommendations of preferred theories for general applications. A series of experiments and areas of further investigations were identified.

  14. Neutron Dosimetry Using a Tissue-Equivalent Ionization Chamber.

    DTIC Science & Technology

    1980-05-01

    procedures are described, and correction factors discussed. /’ On a montg et v~rifiA un systtme de niesure d’oZz la dose ou le kerma tissulaire neutronique ...tube 3.8 cm in diameter. At the same time, it is advantageous to keep the active volume as large as possible in order to maximize sensitivity. The...CHAMBER The construction of the FWT TE Ionization chamber is Illustrated in figure 1. The active volume lies between the central electrode and the

  15. Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams.

    PubMed

    Lourenço, A; Wellock, N; Thomas, R; Homer, M; Bouchard, H; Kanai, T; MacDougall, N; Royle, G; Palmans, H

    2016-11-07

    Water-equivalent plastics are frequently used in dosimetry for experimental simplicity. This work evaluates the water-equivalence of novel water-equivalent plastics specifically designed for light-ion beams, as well as commercially available plastics in a clinical high-energy carbon-ion beam. A plastic- to-water conversion factor [Formula: see text] was established to derive absorbed dose to water in a water phantom from ionization chamber readings performed in a plastic phantom. Three trial plastic materials with varying atomic compositions were produced and experimentally characterized in a high-energy carbon-ion beam. Measurements were performed with a Roos ionization chamber, using a broad un-modulated beam of 11  ×  11 cm(2), to measure the plastic-to-water conversion factor for the novel materials. The experimental results were compared with Monte Carlo simulations. Commercially available plastics were also simulated for comparison with the plastics tested experimentally, with particular attention to the influence of nuclear interaction cross sections. The measured [Formula: see text] correction increased gradually from 0% at the surface to 0.7% at a depth near the Bragg peak for one of the plastics prepared in this work, while for the other two plastics a maximum correction of 0.8%-1.3% was found. Average differences between experimental and numerical simulations were 0.2%. Monte Carlo results showed that for polyethylene, polystyrene, Rando phantom soft tissue and A-150, the correction increased from 0% to 2.5%-4.0% with depth, while for PMMA it increased to 2%. Water-equivalent plastics such as, Plastic Water, RMI-457, Gammex 457-CTG, WT1 and Virtual Water, gave similar results where maximum corrections were of the order of 2%. Considering the results from Monte Carlo simulations, one of the novel plastics was found to be superior in comparison with the plastic materials currently used in dosimetry, demonstrating that it is feasible to tailor

  16. Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams

    NASA Astrophysics Data System (ADS)

    Lourenço, A.; Wellock, N.; Thomas, R.; Homer, M.; Bouchard, H.; Kanai, T.; MacDougall, N.; Royle, G.; Palmans, H.

    2016-11-01

    Water-equivalent plastics are frequently used in dosimetry for experimental simplicity. This work evaluates the water-equivalence of novel water-equivalent plastics specifically designed for light-ion beams, as well as commercially available plastics in a clinical high-energy carbon-ion beam. A plastic- to-water conversion factor {{H}\\text{pl,w}} was established to derive absorbed dose to water in a water phantom from ionization chamber readings performed in a plastic phantom. Three trial plastic materials with varying atomic compositions were produced and experimentally characterized in a high-energy carbon-ion beam. Measurements were performed with a Roos ionization chamber, using a broad un-modulated beam of 11  ×  11 cm2, to measure the plastic-to-water conversion factor for the novel materials. The experimental results were compared with Monte Carlo simulations. Commercially available plastics were also simulated for comparison with the plastics tested experimentally, with particular attention to the influence of nuclear interaction cross sections. The measured H\\text{pl,w}\\exp correction increased gradually from 0% at the surface to 0.7% at a depth near the Bragg peak for one of the plastics prepared in this work, while for the other two plastics a maximum correction of 0.8%-1.3% was found. Average differences between experimental and numerical simulations were 0.2%. Monte Carlo results showed that for polyethylene, polystyrene, Rando phantom soft tissue and A-150, the correction increased from 0% to 2.5%-4.0% with depth, while for PMMA it increased to 2%. Water-equivalent plastics such as, Plastic Water, RMI-457, Gammex 457-CTG, WT1 and Virtual Water, gave similar results where maximum corrections were of the order of 2%. Considering the results from Monte Carlo simulations, one of the novel plastics was found to be superior in comparison with the plastic materials currently used in dosimetry, demonstrating that it is feasible to tailor plastic

  17. Equivalent Linear Logistic Test Models.

    ERIC Educational Resources Information Center

    Bechger, Timo M.; Verstralen, Huub H. F. M.; Verhelst, Norma D.

    2002-01-01

    Discusses the Linear Logistic Test Model (LLTM) and demonstrates that there are many equivalent ways to specify a model. Analyzed a real data set (300 responses to 5 analogies) using a Lagrange multiplier test for the specification of the model, and demonstrated that there may be many ways to change the specification of an LLTM and achieve the…

  18. Expanding the Interaction Equivalency Theorem

    ERIC Educational Resources Information Center

    Rodriguez, Brenda Cecilia Padilla; Armellini, Alejandro

    2015-01-01

    Although interaction is recognised as a key element for learning, its incorporation in online courses can be challenging. The interaction equivalency theorem provides guidelines: Meaningful learning can be supported as long as one of three types of interactions (learner-content, learner-teacher and learner-learner) is present at a high level. This…

  19. Representational Implications for Understanding Equivalence

    ERIC Educational Resources Information Center

    Capraro, Mary Margaret; Ding, Meixia; Matteson, Shirley; Capraro, Robert M.; Li, Xiaobao

    2007-01-01

    Teachers and researchers have long recognized that students tend to misunderstand the equal sign as an operator; that is, a signal for "doing something" rather than a relational symbol of equivalence or quantity sameness. Students' equal sign misconception has been researched for more than thirty years (Weaver, 1971, 1973) with little…

  20. USEPA PATHOGEN EQUIVALENCY COMMITTEE RETREAT

    EPA Science Inventory

    The Pathogen Equivalency Committee held its retreat from September 20-21, 2005 at Hueston Woods State Park in College Corner, Ohio. This presentation will update the PEC’s membership on emerging pathogens, analytical methods, disinfection techniques, risk analysis, preparat...

  1. Equivalence theorem in effective theories

    NASA Astrophysics Data System (ADS)

    Chicherin, D.; Gorbenko, V.; Vereshagin, V.

    2011-11-01

    The famous equivalence theorem is reexamined in order to make it applicable to the case of effective theories. We slightly modify the formulation of this theorem and prove it based on the notion of the generating functional for Green functions. This allows one to trace (directly in terms of graphs) the mutual cancellation of different groups of contributions.

  2. Development of a dielectric equivalent gel for better impedance matching for human skin.

    PubMed

    Sunaga, Takahiro; Ikehira, Hiroo; Furukawa, Shigeo; Tamura, Mitsuru; Yoshitome, Eiji; Obata, Takayuki; Shinkai, Hiroshi; Tanada, Shuji; Murata, Hajime; Sasaki, Yasuhito

    2003-04-01

    It would be useful to develop a tissue equivalent gel to improve the uniformity of the electromagnetic field in the human body, and for making a tissue equivalent dielectric human phantom. In this study, solid type, water based gelatin-honey gels were developed which have the electrical characteristics of skin tissue. It was demonstrated that a stable and homogeneous gel, with a relative dielectric constant epsilon ' chosen from desired ranges found in skin, can be made for 200-400 MHz.

  3. Mathematically Equivalent, Computationally Non-equivalent Formulas and Software Comprehensibility

    DTIC Science & Technology

    2016-06-07

    bears little resemblance to it for computational reasons. Therefore, although the flow of control of the coded algorithm may be visible to a...software. The computational algorithm used is often mathematically equivalent to the defining formula, but bears little resemblence to it for...computational considera- tions, and often bears little resemblence to the formulas that were used to define the transaction originally. Therefore, although the

  4. Equivalence theorem of uncertainty relations

    NASA Astrophysics Data System (ADS)

    Li, Jun-Li; Qiao, Cong-Feng

    2017-01-01

    We present an equivalence theorem to unify the two classes of uncertainty relations, i.e. the variance-based ones and the entropic forms, showing that the entropy of an operator in a quantum system can be built from the variances of a set of commutative operators. This means that an uncertainty relation in the language of entropy may be mapped onto a variance-based one, and vice versa. Employing the equivalence theorem, alternative formulations of entropic uncertainty relations are obtained for the qubit system that are stronger than the existing ones in the literature, and variance-based uncertainty relations for spin systems are reached from the corresponding entropic uncertainty relations.

  5. Comparison of CONDOR, FCI and MAFIA Calculations for a 150MW S-Band Klystron with Measurements

    SciTech Connect

    Sprehn, Daryl W

    2003-06-11

    To facilitate the design of high power klystrons an investigation into the reliability and accuracy of three modern particle-in-cell codes was performed. A 150 MW S-band klystron for which measurements were available was used for this comparison. The field calculations of the particle-in-cell codes are based on a finite difference time domain scheme, and use a port approximation to speed up the convergence to steady state. However, they differ in many details (e.g. calculation of E, B or A, {psi}; space charge correction; 2D or 3D modeling of output cavity).

  6. TNT Equivalency of Bulk Nitrocellulose

    DTIC Science & Technology

    1981-03-01

    9TIN ’IN AD-E400 576 CONTRACTOR REPORT ARLCD-CR-81007 TNT EQUIVALENCY OF BULK NITROCELLULOSE F. L. MCINTYRE COMPUTER SCIENCES CORPORATION NSTL...September 1978 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(S) 8. CONTRACT OR GRANT NUMBER(e) F. L. Mc~ntyre, Computer Sciences Corporation P. Price...PROJECT. TASK Computer Sciences Corporation AREA & WORK UNIT NUMBERS NSTL Station, MS 39529 MMT-5784285 II. CONTROLLING OFFICE NAME AND ADDRESS 12

  7. Equivalent circuit for birdcage resonators.

    PubMed

    Harpen, M D

    1993-02-01

    We present an equivalent circuit analysis for both low pass and high pass birdcage resonators loaded with lossy samples. In a generalization of the method of Hoult and Lauterbur (J. Magn. Reson. 34, 425 (1979)), we also derive circuit component values by application of the laws of electrodynamics. Measured resonance spectra, quality factors, and feed point impedances in a test resonator are shown to be in agreement with those predicted by the proposed model.

  8. Equivalent statistics and data interpretation.

    PubMed

    Francis, Gregory

    2016-10-14

    Recent reform efforts in psychological science have led to a plethora of choices for scientists to analyze their data. A scientist making an inference about their data must now decide whether to report a p value, summarize the data with a standardized effect size and its confidence interval, report a Bayes Factor, or use other model comparison methods. To make good choices among these options, it is necessary for researchers to understand the characteristics of the various statistics used by the different analysis frameworks. Toward that end, this paper makes two contributions. First, it shows that for the case of a two-sample t test with known sample sizes, many different summary statistics are mathematically equivalent in the sense that they are based on the very same information in the data set. When the sample sizes are known, the p value provides as much information about a data set as the confidence interval of Cohen's d or a JZS Bayes factor. Second, this equivalence means that different analysis methods differ only in their interpretation of the empirical data. At first glance, it might seem that mathematical equivalence of the statistics suggests that it does not matter much which statistic is reported, but the opposite is true because the appropriateness of a reported statistic is relative to the inference it promotes. Accordingly, scientists should choose an analysis method appropriate for their scientific investigation. A direct comparison of the different inferential frameworks provides some guidance for scientists to make good choices and improve scientific practice.

  9. Information Leakage from Logically Equivalent Frames

    ERIC Educational Resources Information Center

    Sher, Shlomi; McKenzie, Craig R. M.

    2006-01-01

    Framing effects are said to occur when equivalent frames lead to different choices. However, the equivalence in question has been incompletely conceptualized. In a new normative analysis of framing effects, we complete the conceptualization by introducing the notion of information equivalence. Information equivalence obtains when no…

  10. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    NASA Astrophysics Data System (ADS)

    Shtejer, K.; Arruda-Neto, J. D. T.; Schulte, R.; Wroe, A.; Rodrigues, T. E.; de Menezes, M. O.; Moralles, M.; Guzmán, F.; Manso, M. V.

    2008-08-01

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, α3He to the total dose compared to the GEANT4 physical models chosen in this work.

  11. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    SciTech Connect

    Shtejer, K.; Arruda-Neto, J. D. T.; Rodrigues, T. E.; Schulte, R.; Wroe, A.; Menezes, M. O. de; Moralles, M.

    2008-08-11

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, {alpha}{sup 3}He to the total dose compared to the GEANT4 physical models chosen in this work.

  12. Conformal dynamical equivalence and applications

    NASA Astrophysics Data System (ADS)

    Spyrou, N. K.

    2011-02-01

    The "Conformal Dynamical Equivalence" (CDE) approach is briefly reviewed, and some of its applications, at various astrophysical levels (Sun, Solar System, Stars, Galaxies, Clusters of Galaxies, Universe as a whole), are presented. According to the CDE approach, in both the Newtonian and general-relativistic theories of gravity, the isentropic hydrodynamic flows in the interior of a bounded gravitating perfect-fluid source are dynamically equivalent to geodesic motions in a virtual, fully defined fluid source. Equivalently, the equations of hydrodynamic motion in the former source are functionally similar to those of the geodesic motions in the latter, physically, fully defined source. The CDE approach is followed for the dynamical description of the motions in the fluid source. After an observational introduction, taking into account all the internal physical characteristics of the corresponding perfect-fluid source, and based on the property of the isentropic hydrodynamic flows (quite reasonable for an isolated physical system), we examine a number of issues, namely, (i) the classical Newtonian explanation of the celebrated Pioneer-Anomaly effect in the Solar System, (ii) the possibility of both the attractive gravity and the repulsive gravity in a non-quantum Newtonian framework, (iii) the evaluation of the masses - theoretical, dynamical, and missing - and of the linear dimensions of non-magnetized and magnetized large-scale cosmological structures, (iv) the explanation of the flat-rotation curves of disc galaxies, (v) possible formation mechanisms of winds and jets, and (vi) a brief presentation of a conventional approach - toy model to the dynamics of the Universe, characterized by the dominant collisional dark matter (with its subdominant luminous baryonic "contamination"), correctly interpreting the cosmological observational data without the need of the notions dark energy, cosmological constant, and universal accelerating expansion.

  13. On Vasyliunas's equivalent conductivity formalism

    NASA Technical Reports Server (NTRS)

    Pontius, D. H., Jr.

    1992-01-01

    The Vasyliunas's (1972) equivalent conductivity formalism (ECF) for representing the coupling of the ionosphere and the magnetosphere is discussed, and a new, simpler, derivation is presented of the ECF, in which certain of the underlying assumptions and their implications are made transparent. The derivation presented indicates that the only role of the ions in the ECF is to insure quasi-neutrality. It is shown that the ECF is not as robust as usually assumed and that caution must be used to insure that reasonable results are obtained.

  14. Therapeutic equivalents in clinical practice.

    PubMed

    Benson, M D

    2001-01-01

    With increasing debate over the rising expenses of health care, a variety of cost-saving measures has been attempted over the years. Use of primary care physicians as "gate keepers," reduction in the length of hospital stays, and pushing women toward vaginal birth after Cesarean section have all been utilized despite on going issues with patient satisfaction and even safety. One remarkable success in stretching health-care dollars that has often been overlooked is the prescription of therapeutic equivalents, or generic drugs. Although available on a limited basis for decades, off-brand manufacture of pharmaceuticals with identical active ingredients as those of the branded drug received a large boost through Congressional legislation in 1984 with the Hatch-Waxman Act. "Fast-track" FDA approval was initiated by Congress to introduce competition into the marketplace for drugs whose patients had expired. While giving close scrutiny to the manufacturing process and requiring the same level of regulatory supervision for factors such as bioavailability and shelf life, the Hatch-Waxman Act removed the burden and expense from generic manufacturers of proving the safety and efficacy all over again of a previously FDA-approved drug. With less than a 20% market share of all prescribed drugs in 1984, the generic drug industry has captured roughly 44% of the market in recent years while accounting for only 8% of expenditures on prescription medication. The prescription of therapeutic equivalents is one method of keeping health care costs down without compromising patient satisfaction or safety.

  15. Equivalent crystal theory of alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1991-01-01

    Equivalent Crystal Theory (ECT) is a new, semi-empirical approach to calculating the energetics of a solid with defects. The theory has successfully reproduced surface energies in metals and semiconductors. The theory of binary alloys to date, both with first-principles and semi-empirical models, has not been very successful in predicting the energetics of alloys. This procedure is used to predict the heats of formation, cohesive energy, and lattice parameter of binary alloys of Cu, Ni, Al, Ag, Au, Pd, and Pt as functions of composition. The procedure accurately reproduces the heats of formation versus composition curves for a variety of binary alloys. The results are then compared with other approaches such as the embedded atom and lattice parameters of alloys from pure metal properties more accurately than Vegard's law is presented.

  16. Foreword: Biomonitoring Equivalents special issue.

    PubMed

    Meek, M E; Sonawane, B; Becker, R A

    2008-08-01

    The challenge of interpreting results of biomonitoring for environmental chemicals in humans is highlighted in this Foreword to the Biomonitoring Equivalents (BEs) special issue of Regulatory Toxicology and Pharmacology. There is a pressing need to develop risk-based tools in order to empower scientists and health professionals to interpret and communicate the significance of human biomonitoring data. The BE approach, which integrates dosimetry and risk assessment methods, represents an important advancement on the path toward achieving this objective. The articles in this issue, developed as a result of an expert panel meeting, present guidelines for derivation of BEs, guidelines for communication using BEs and several case studies illustrating application of the BE approach for specific substances.

  17. Verification of an effective dose equivalent model for neutrons

    SciTech Connect

    Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.

    1991-10-01

    Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modeling techniques and a knowledge of the radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well-chosen measurements are required to confirm the theoretical models. Neutron measurements were performed in a RANDO phantom using thermoluminescent dosemeters, track etch dosemeters, and a 1/2-in. (1.27-cm) tissue equivalent proportional counter in order to estimate neutron doses and dose equivalents within the phantom at specific locations. The phantom was exposed to bare and D{sub 2}O-moderated {sup 252}Cf neutrons at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and calculate organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared to the calculations. 8 refs., 3 figs., 3 tabs.

  18. 46 CFR 110.20-1 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Equivalents. 110.20-1 Section 110.20-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING GENERAL PROVISIONS Equivalents... engineering evaluations and tests to demonstrate the equivalence of the substitute....

  19. 46 CFR 110.20-1 - Equivalents.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Equivalents. 110.20-1 Section 110.20-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING GENERAL PROVISIONS Equivalents... engineering evaluations and tests to demonstrate the equivalence of the substitute....

  20. 46 CFR 110.20-1 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Equivalents. 110.20-1 Section 110.20-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING GENERAL PROVISIONS Equivalents... engineering evaluations and tests to demonstrate the equivalence of the substitute....

  1. Testing the weak equivalence principle

    NASA Astrophysics Data System (ADS)

    Nobili, Anna M.; Comandi, Gian Luca; Pegna, Raffaello; Bramanti, Donato; Doravari, Suresh; Maccarone, Francesco; Lucchesi, David M.

    2010-01-01

    The discovery of Dark Energy and the fact that only about 5% of the mass of the universe can be explained on the basis of the current laws of physics have led to a serious impasse. Based on past history, physics might indeed be on the verge of major discoveries; but the challenge is enormous. The way to tackle it is twofold. On one side, scientists try to perform large scale direct observations and measurements - mostly from space. On the other, they multiply their efforts to put to the most stringent tests ever the physical theories underlying the current view of the physical world, from the very small to the very large. On the extremely small scale very exciting results are expected from one of the most impressive experiments in the history of mankind: the Large Hadron Collider. On the very large scale, the universe is dominated by gravity and the present impasse undoubtedly calls for more powerful tests of General Relativity - the best theory of gravity to date. Experiments testing the Weak Equivalence Principle, on which General Relativity ultimately lies, have the strongest probing power of them all; a breakthrough in sensitivity is possible with the “Galileo Galilei” (GG) satellite experiment to fly in low Earth orbit.

  2. It Pays to Be Organized: Organizing Arithmetic Practice around Equivalent Values Facilitates Understanding of Math Equivalence

    ERIC Educational Resources Information Center

    McNeil, Nicole M.; Chesney, Dana L.; Matthews, Percival G.; Fyfe, Emily R.; Petersen, Lori A.; Dunwiddie, April E.; Wheeler, Mary C.

    2012-01-01

    This experiment tested the hypothesis that organizing arithmetic fact practice by equivalent values facilitates children's understanding of math equivalence. Children (M age = 8 years 6 months, N = 104) were randomly assigned to 1 of 3 practice conditions: (a) equivalent values, in which problems were grouped by equivalent sums (e.g., 3 + 4 = 7, 2…

  3. AGR-2 Data Qualification Report for ATR Cycles 149B, 150A, 150B, 151A, and 151B

    SciTech Connect

    Michael L. Abbott; Binh T. Pham

    2012-06-01

    This report provides the data qualification status of AGR-2 fuel irradiation experimental data from Advanced Test Reactor (ATR) cycles 149B, 150A, 150B, 151A, and 151B), as recorded in the Nuclear Data Management and Analysis System (NDMAS). The AGR-2 data streams addressed include thermocouple temperatures, sweep gas data (flow rate, pressure, and moisture content), and fission product monitoring system (FPMS) data for each of the six capsules in the experiment. A total of 3,307,500 5-minute thermocouple and sweep gas data records were received and processed by NDMAS for this period. There are no AGR-2 data for cycle 150A because the experiment was removed from the reactor. Of these data, 82.2% were determined to be Qualified based on NDMAS accuracy testing and data validity assessment. There were 450,557 Failed temperature records due to thermocouple failures, and 138,528 Failed gas flow records due to gas flow cross-talk and leakage problems that occurred in the capsules after cycle 150A. For FPMS data, NDMAS received and processed preliminary release rate and release-to-birth rate ratio (R/B) data for the first three reactor cycles (cycles 149B, 150B, and 151B). This data consists of 45,983 release rate records and 45,235 R/B records for the 12 radionuclides reported. The qualification status of these FPMS data has been set to In Process until receipt of QA-approved data generator reports. All of the above data have been processed and tested using a SAS®-based enterprise application software system, stored in a secure Structured Query Language database, and made available on the NDMAS Web portal (http://ndmas.inl.gov) for both internal and external VHTR project participants.

  4. 21 CFR 26.9 - Equivalence determination.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.9 Equivalence...

  5. 21 CFR 26.6 - Equivalence assessment.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.6 Equivalence...

  6. 21 CFR 26.6 - Equivalence assessment.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.6 Equivalence...

  7. 21 CFR 26.9 - Equivalence determination.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.9 Equivalence...

  8. 21 CFR 26.6 - Equivalence assessment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.6 Equivalence...

  9. 21 CFR 26.9 - Equivalence determination.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS... Specific Sector Provisions for Pharmaceutical Good Manufacturing Practices § 26.9 Equivalence...

  10. TISSUE-Tregs

    PubMed Central

    Panduro, Marisella; Benoist, Christophe; Mathis, Diane

    2016-01-01

    The immune system is responsible for defending an organism against the myriad of microbial invaders it constantly confronts. It has become increasingly clear that the immune system has a second major function: the maintenance of organismal homeostasis. Foxp3+CD4+ regulatory T cells (Tregs) are important contributors to both of these critical activities, defense being the primary purview of Tregs circulating through lymphoid organs, and homeostasis ensured mainly by their counterparts residing in parenchymal tissues. This review focuses on so-called tissue Tregs. We first survey existing information on the phenotype, function, sustaining factors, and human equivalents of the three best-characterized tissue-Treg populations—those operating in visceral adipose tissue, skeletal muscle, and the colonic lamina propria. We then attempt to distill general principles from this body of work—as concerns the provenance, local adaptation, molecular sustenance, and targets of action of tissue Tregs, in particular. PMID:27168246

  11. Equivalency Programmes (EPs) for Promoting Lifelong Learning

    ERIC Educational Resources Information Center

    Haddad, Caroline, Ed.

    2006-01-01

    Equivalency programmes (EPs) refers to alternative education programmes that are equivalent to the formal education system in terms of curriculum and certification, policy support mechanisms, mode of delivery, staff training, and other support activities such as monitoring, evaluation and assessment. The development of EPs is potentially an…

  12. 49 CFR 38.2 - Equivalent facilitation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from...

  13. 49 CFR 38.2 - Equivalent facilitation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from...

  14. 49 CFR 38.2 - Equivalent facilitation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from...

  15. 49 CFR 38.2 - Equivalent facilitation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from...

  16. Mania and Behavioral Equivalents: A Preliminary Study

    ERIC Educational Resources Information Center

    Sturmey, Peter; Laud, Rinita B.; Cooper, Christopher L.; Matson, Johnny L.; Fodstad, Jill C.

    2010-01-01

    Previous research has failed to address the possibility of behavioral equivalents in people with ID and mania. The relationship between a measure of mania and possible behavioral equivalents was assessed in 693 adults, most with severe or profound ID, living in a large residential setting. The mania subscale of the DASH-II proved to be a…

  17. 46 CFR 169.109 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Equivalents. 169.109 Section 169.109 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS General Provisions § 169.109 Equivalents. Substitutes for a fitting, appliance, apparatus, or equipment, may...

  18. 46 CFR 133.09 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Equivalents. When this part requires a particular fitting, material, or lifesaving appliance or arrangement, the Commandant (CG-521) may accept any other fitting, material, or lifesaving appliance or arrangement... evaluations and tests to determine the equivalent effectiveness of the substitute fitting, material,...

  19. 7 CFR 1032.54 - Equivalent price.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 9 2012-01-01 2012-01-01 false Equivalent price. 1032.54 Section 1032.54 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Handling Class Prices § 1032.54 Equivalent price. See § 1000.54. Producer Price Differential...

  20. 7 CFR 1032.54 - Equivalent price.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 9 2014-01-01 2013-01-01 true Equivalent price. 1032.54 Section 1032.54 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Handling Class Prices § 1032.54 Equivalent price. See § 1000.54. Producer Price Differential...

  1. 7 CFR 1032.54 - Equivalent price.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 9 2010-01-01 2009-01-01 true Equivalent price. 1032.54 Section 1032.54 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Handling Class Prices § 1032.54 Equivalent price. See § 1000.54. Producer Price Differential...

  2. 7 CFR 1032.54 - Equivalent price.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 9 2013-01-01 2013-01-01 false Equivalent price. 1032.54 Section 1032.54 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Handling Class Prices § 1032.54 Equivalent price. See § 1000.54. Producer Price Differential...

  3. 7 CFR 1032.54 - Equivalent price.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 9 2011-01-01 2011-01-01 false Equivalent price. 1032.54 Section 1032.54 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Handling Class Prices § 1032.54 Equivalent price. See § 1000.54. Producer Price Differential...

  4. 33 CFR 106.130 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Equivalents. 106.130 Section 106.130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARINE SECURITY: OUTER CONTINENTAL SHELF (OCS) FACILITIES General § 106.130 Equivalents. For any...

  5. 33 CFR 106.130 - Equivalents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Equivalents. 106.130 Section 106.130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARINE SECURITY: OUTER CONTINENTAL SHELF (OCS) FACILITIES General § 106.130 Equivalents. For any...

  6. 33 CFR 106.130 - Equivalents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Equivalents. 106.130 Section 106.130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MARITIME SECURITY MARINE SECURITY: OUTER CONTINENTAL SHELF (OCS) FACILITIES General § 106.130 Equivalents. For any...

  7. 49 CFR 38.2 - Equivalent facilitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from...

  8. 33 CFR 159.19 - Testing equivalency.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Testing equivalency. 159.19 Section 159.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Certification Procedures § 159.19 Testing equivalency. (a) If a...

  9. 33 CFR 159.19 - Testing equivalency.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Testing equivalency. 159.19 Section 159.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Certification Procedures § 159.19 Testing equivalency. (a) If a...

  10. 33 CFR 159.19 - Testing equivalency.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Testing equivalency. 159.19 Section 159.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Certification Procedures § 159.19 Testing equivalency. (a) If a...

  11. 33 CFR 159.19 - Testing equivalency.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Testing equivalency. 159.19 Section 159.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Certification Procedures § 159.19 Testing equivalency. (a) If a...

  12. 33 CFR 159.19 - Testing equivalency.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Testing equivalency. 159.19 Section 159.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Certification Procedures § 159.19 Testing equivalency. (a) If a...

  13. Equivalence in Ventilation and Indoor Air Quality

    SciTech Connect

    Sherman, Max; Walker, Iain; Logue, Jennifer

    2011-08-01

    We ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American Society of Heating, Refrigerating, and Air-Conditioning Enginners [ASHRAE] Standard 62) specify minimum ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation management is often a desirable element of reducing energy consumption or improving IAQ or comfort. Variable ventilation is one innovative strategy. To use variable ventilation in a way that meets standards, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality. This study develops methods to calculate either equivalent ventilation or equivalent IAQ. We demonstrate that equivalent ventilation can be used as the basis for dynamic ventilation control, reducing peak load and infiltration of outdoor contaminants. We also show that equivalent IAQ could allow some contaminants to exceed current standards if other contaminants are more stringently controlled.

  14. Equivalence-Equivalence Responding: Training Conditions Involved in Obtaining a Stable Baseline Performance

    ERIC Educational Resources Information Center

    Garcia, Andres; Bohorquez, Cristobal; Perez, Vicente; Gutierrez, Maria Teresa; Gomez, Jesus; Luciano, Carmen; Wilson, Kelly

    2008-01-01

    Recent research has focused on the variables associated with equivalence-equivalence responding, in which participants match pairs of equivalent or nonequivalent stimuli. One such variable is the presence of response competition from nonarbitrary (physical) relational response options. In the current analysis, the experimenters examined the effect…

  15. Matching Derived Functionally-Same Stimulus Relations: Equivalence-Equivalence and Classical Analogies

    ERIC Educational Resources Information Center

    Carpentier, Franck; Smeets, Paul M.; Barnes-Holmes, Dermot; Stewart, Ian

    2004-01-01

    Previous studies have shown that, after being trained on A-B and A-C matching tasks, subjects match not only functionally-same B and C stimuli (stimulus equivalence), but also BC compounds with same-class elements and BC compounds with different-class elements (equivalence-equivalence). Similar performances are required in classical analogies (a :…

  16. On asymptotically lacunary invariant statistical equivalent set sequences

    NASA Astrophysics Data System (ADS)

    Pancaroglu, Nimet; Nuray, Fatih; Savas, Ekrem

    2013-10-01

    In this paper, we define asymptotically invariant equivalence, strongly asymptotically invariant equivalence, asymptotically invariant statistical equivalence, asymptotically lacunary invariant statistical equivalence, strongly asymptotically lacunary invariant equivalence, asymptotically lacunary invariant equivalence (Wijsman sense) for sequences of sets. Also we investigate some relations between asymptotically lacunary invariant statistical equivalence and asymptotically invariant statistical equivalence for sequences of sets. We introduce some notions and theorems as follows, asymptotically lacunary invariant statistical equivalence, strongly asymptotically lacunary invariant equivalence, asymptotically lacunary invariant equivalence (Wijsman sense) for sequences of sets.

  17. The Assessment of Effective Dose Equivalent Using Personnel Dosimeters

    NASA Astrophysics Data System (ADS)

    Xu, Xie

    From January 1994, U.S. nuclear plants must develop a technically rigorous approach for determining the effective dose equivalent for their work forces. This dissertation explains concepts associated with effective dose equivalent and describes how to assess effective dose equivalent by using conventional personnel dosimetry measurements. A Monte Carlo computer code, MCNP, was used to calculate photon transport through a model of the human body. Published mathematical phantoms of the human adult male and female were used to simulate irradiation from a variety of external radiation sources in order to calculate organ and tissue doses, as well as effective dose equivalent using weighting factors from ICRP Publication 26. The radiation sources considered were broad parallel photon beams incident on the body from 91 different angles and isotropic point sources located at 234 different locations in contact with or near the body. Monoenergetic photons of 0.08, 0.3, and 1.0 MeV were considered for both sources. Personnel dosimeters were simulated on the surface of the body and exposed to with the same sources. From these data, the influence of dosimeter position on dosimeter response was investigated. Different algorithms for assessing effective dose equivalent from personnel dosimeter responses were proposed and evaluated. The results indicate that the current single-badge approach is satisfactory for most common exposure situations encountered in nuclear plants, but additional conversion factors may be used when more accurate results become desirable. For uncommon exposures involving source situated at the back of the body or source located overhead, the current approach of using multi-badges and assigning the highest dose is overly conservative and unnecessarily expensive. For these uncommon exposures, a new algorithm, based on two dosimeters, one on the front of the body and another one on the back of the body, has been shown to yield conservative assessment of

  18. Antireflection design concepts with equivalent layers.

    PubMed

    Schallenberg, Uwe B

    2006-03-01

    Some novel concepts of designing antireflection (AR) coatings with equivalent layers are presented. As an introduction, essential papers concerning thin-film optics and AR designs are cited, and the AR problem and a previously introduced AR-hard design type are discussed. Based on the known matrix formalism, a potential AR region, an equivalent stack index, and an equivalent substrate index are defined to use the theory of stop-band suppression as a starting point for the design of broadband AR coatings. The known multicycle AR design type is identified as a typical solution to the AR problem if the presented approach is used.

  19. Tissue Engineering Research

    DTIC Science & Technology

    2002-01-01

    on Neural Stem Cells ......................................................25 4.1 Scoring System for the Histological Appearance of Full-Thickness...intellectual property. Examples include London’s Imperial College Tissue Engineering Center with its focus on stem cell research and the new Manchester...Moderate Equivalent Allogeneic cells / immunological manipulation Extensive Active in U.S. Modest in EU Little in Japan U.S. Stem cell research Extensive in

  20. On asymptotically generalized statistical equivalent set sequences

    NASA Astrophysics Data System (ADS)

    Savas, Ekrem

    2013-10-01

    In this paper we shall study the asymptotically λ-statistical equivalent (Wijsman sense) of multiple L. In addition to these definition, natural inclusion theorems shall also be presented. This approach has not been considered in any context before.

  1. 46 CFR 114.540 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., calculation, information, or test which provides a level of safety equivalent to that established by specific... provisions of the International Maritime Organization (IMO) “Code of Safety for High Speed Craft” as...

  2. 46 CFR 175.540 - Equivalents.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., appliance, apparatus, equipment, calculation, information, or test, which provides a level of safety... Organization (IMO) “Code of Safety for High Speed Craft” as an equivalent to compliance with...

  3. [Therapeutic equivalence of the new oral anticoagulants].

    PubMed

    Moreno Villar, A; Nacle López, I; Barbero Hernández, M J; Lizan Tudela, L

    2015-10-01

    In an attempt to minimize the economic impact due to the incorporation of innovative drugs, health authorities have promoted and supported the evaluation and market positioning of drugs, as equivalent therapeutic alternatives. This issue has recently gained importance, possibly due to the current economic crisis. The equivalent therapeutic alternatives are justified by the need to compete on price, and by the authorities recommendation to establish therapeutic equivalence, price and financing of medicinal products at the same time. The establishment of the new oral anticoagulants and the equivalent therapeutic alternatives is a problematic issue if it is based on the absence of direct comparisons between different drugs and the questionable methodology used in the current indirect comparisons. Currently, it is difficult to determine when a new oral anticoagulant is more recommendable than others, but efforts are being made in order to propose alternatives for the decision based on patient characteristics.

  4. Distinguishing Provenance Equivalence of Earth Science Data

    NASA Technical Reports Server (NTRS)

    Tilmes, Curt; Yesha, Ye; Halem, M.

    2010-01-01

    Reproducibility of scientific research relies on accurate and precise citation of data and the provenance of that data. Earth science data are often the result of applying complex data transformation and analysis workflows to vast quantities of data. Provenance information of data processing is used for a variety of purposes, including understanding the process and auditing as well as reproducibility. Certain provenance information is essential for producing scientifically equivalent data. Capturing and representing that provenance information and assigning identifiers suitable for precisely distinguishing data granules and datasets is needed for accurate comparisons. This paper discusses scientific equivalence and essential provenance for scientific reproducibility. We use the example of an operational earth science data processing system to illustrate the application of the technique of cascading digital signatures or hash chains to precisely identify sets of granules and as provenance equivalence identifiers to distinguish data made in an an equivalent manner.

  5. REFractions: The Representing Equivalent Fractions Game

    ERIC Educational Resources Information Center

    Tucker, Stephen I.

    2014-01-01

    Stephen Tucker presents a fractions game that addresses a range of fraction concepts including equivalence and computation. The REFractions game also improves students' fluency with representing, comparing and adding fractions.

  6. 46 CFR 125.170 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... required by this subchapter may be accepted by the cognizant OCMI; by the Commanding Officer, Marine Safety... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS GENERAL § 125.170 Equivalents... of safety....

  7. Equivalence relations and the reinforcement contingency.

    PubMed

    Sidman, M

    2000-07-01

    Where do equivalence relations come from? One possible answer is that they arise directly from the reinforcement contingency. That is to say, a reinforcement contingency produces two types of outcome: (a) 2-, 3-, 4-, 5-, or n-term units of analysis that are known, respectively, as operant reinforcement, simple discrimination, conditional discrimination, second-order conditional discrimination, and so on; and (b) equivalence relations that consist of ordered pairs of all positive elements that participate in the contingency. This conception of the origin of equivalence relations leads to a number of new and verifiable ways of conceptualizing equivalence relations and, more generally, the stimulus control of operant behavior. The theory is also capable of experimental disproof.

  8. Dark matter and the equivalence principle

    NASA Technical Reports Server (NTRS)

    Frieman, Joshua A.; Gradwohl, Ben-Ami

    1993-01-01

    A survey is presented of the current understanding of dark matter invoked by astrophysical theory and cosmology. Einstein's equivalence principle asserts that local measurements cannot distinguish a system at rest in a gravitational field from one that is in uniform acceleration in empty space. Recent test-methods for the equivalence principle are presently discussed as bases for testing of dark matter scenarios involving the long-range forces between either baryonic or nonbaryonic dark matter and ordinary matter.

  9. Methods for Equivalence and Noninferiority Testing

    PubMed Central

    Silva, Gisela Tunes da; Logan, Brent R.; Klein, John P.

    2009-01-01

    Classical hypothesis testing focuses on testing whether treatments have differential effects on outcome. However, sometimes clinicians may be more interested in determining whether treatments are equivalent or whether one has noninferior outcomes. We review the hypotheses for these noninferiority and equivalence research questions, consider power and sample size issues, and discuss how to perform such a test for both binary and survival outcomes. The methods are illustrated on 2 recent studies in hematopoietic cell transplantation. PMID:19147090

  10. The endotopism semigroups of an equivalence relation

    SciTech Connect

    Zhuchok, Yu V; Toichkina, E A

    2014-05-31

    In this work we investigate six types of endotopism semigroups for a given equivalence relation. Necessary and sufficient conditions for the existence of all such endotopisms are presented. Conditions for the regularity and coregularity of each of the endotopism semigroups of a given type are established. The notion of the endotype of a binary relation with respect to its endotopisms is introduced and the endotype of an arbitrary equivalence relation is calculated. Bibliography: 26 titles.

  11. Quantum equivalence of dual field theories

    NASA Astrophysics Data System (ADS)

    Fradkin, E. S.; Tseytlin, A. A.

    1985-06-01

    Motivated by the study of ultraviolet properties of different versions of supergravities duality transformations at the quantum level are discussed. Using the background field method it is proven on shell quantum equivalence for several pairs of dual field theories known to be classically equivalent. The examples considered include duality in chiral model, duality of scalars and second rank antisymmetric gauge tensors, vector duality and duality of the Einstein theory with cosmological term and the Eddington-Schrödinger theory.

  12. On the Equivalent Dose for Auger Electron Emitters

    PubMed Central

    Howell, Roger W.; Narra, Venkat R.; Sastry, Kandula S. R.; Rao, Dandamudi V.

    2012-01-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201T1) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET α particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework. PMID:8475256

  13. Absorbed Dose and Dose Equivalent Calculations for Modeling Effective Dose

    NASA Technical Reports Server (NTRS)

    Welton, Andrew; Lee, Kerry

    2010-01-01

    While in orbit, Astronauts are exposed to a much higher dose of ionizing radiation than when on the ground. It is important to model how shielding designs on spacecraft reduce radiation effective dose pre-flight, and determine whether or not a danger to humans is presented. However, in order to calculate effective dose, dose equivalent calculations are needed. Dose equivalent takes into account an absorbed dose of radiation and the biological effectiveness of ionizing radiation. This is important in preventing long-term, stochastic radiation effects in humans spending time in space. Monte carlo simulations run with the particle transport code FLUKA, give absorbed and equivalent dose data for relevant shielding. The shielding geometry used in the dose calculations is a layered slab design, consisting of aluminum, polyethylene, and water. Water is used to simulate the soft tissues that compose the human body. The results obtained will provide information on how the shielding performs with many thicknesses of each material in the slab. This allows them to be directly applicable to modern spacecraft shielding geometries.

  14. The nonequivalence of behavioral and mathematical equivalence.

    PubMed

    Saunders, R R; Green, G

    1992-03-01

    Sidman and his colleagues derived behavioral tests for stimulus equivalence from the axiom in logic and mathematics that defines a relation of equivalence. The analogy has generated abundant research in which match-to-sample methods have been used almost exclusively to study interesting and complex stimulus control phenomena. It has also stimulated considerable discussion regarding interpretation of the analogy and speculation as to its validity and generality. This article reexamines the Sidman stimulus equivalence analogy in the context of a broader consideration of the mathematical axiom than was included in the original presentation of the analogy and some of the data that have accumulated in the interim. We propose that (a) mathematical and behavioral examples of equivalence relations differ substantially, (b) terminology is being used in ways that can lead to erroneous conclusions about the nature of the stimulus control that develops in stimulus equivalence experiments, and (c) complete analyses of equivalence and other types of stimulus-stimulus relations require more than a simple invocation of the analogy. Implications of our analysis for resolving current issues and prompting new research are discussed.

  15. Validation of artificial skin equivalents as in vitro testing systems

    NASA Astrophysics Data System (ADS)

    Schmitt, Robert; Marx, Ulrich; Walles, Heike; Schober, Lena

    2011-03-01

    With the increasing complexity of the chemical composition of pharmaceuticals, cosmetics and everyday substances, the awareness of potential health issues and long term damages for humanoid organs is shifting into focus. Artificial in vitro testing systems play an important role in providing reliable test conditions and replacing precarious animal testing. Especially artificial skin equivalents ASEs are used for a broad spectrum of studies like penetration, irritation and corrosion of substances. One major challenge in tissue engineering is the qualification of each individual ASE as in vitro testing system. Due to biological fluctuations, the stratum corneum hornified layer of some ASEs may not fully develop or other defects might occur. For monitoring these effects we developed an fully automated Optical Coherence Tomography device. Here, we present different methods to characterize and evaluate the quality of the ASEs based on image and data processing of OCT B-scans. By analysing the surface structure, defects, like cuts or tears, are detectable. A further indicator for the quality of the ASE is the morphology of the tissue. This allows to determine if the skin model has reached the final growth state. We found, that OCT is a well suited technology for automatically characterizing artificial skin equivalents and validating the application as testing system.

  16. Acceptance criteria for method equivalency assessments.

    PubMed

    Chatfield, Marion J; Borman, Phil J

    2009-12-15

    Quality by design (ICH-Topic Q8) requires that process control strategy requirements are met and maintained. The challenging task of setting appropriate acceptance criteria for assessment of method equivalence is a critical component of satisfying these requirements. The use of these criteria will support changes made to methods across the product lifecycle. A method equivalence assessment is required when a change is made to a method which may pose a risk to its ability to monitor the quality of the process. Establishing appropriate acceptance criteria are a vital, but not clearly understood, prerequisite to deciding the appropriate design/sample size of the equivalency study. A number of approaches are proposed in the literature for setting acceptance criteria for equivalence which address different purposes. This perspective discusses those purposes and then provides more details on setting acceptance criteria based on patient and producer risk, e.g., tolerance interval approach and the consideration of method or process capability. Applying these to a drug substance assay method for batch release illustrates that, for the equivalence assessment to be meaningful, a clear understanding and appraisal of the control requirements of the method is needed. Rather than a single exact algorithm, the analyst's judgment on a number of aspects is required in deciding the appropriate acceptance criteria.

  17. On SLλ(I)-asymptotically statistical equivalent sequences

    NASA Astrophysics Data System (ADS)

    Gumus, Hafize; Savas, Ekrem

    2012-09-01

    This paper presents the notion of SLλ(I)-asymptotically statistical equivalence which is a natural combination of asymptotic I-equivalence and λ-statistical equivalence. We find its relation to I-asymptotically statistical convergence, strong λI-asymptotically equivalence and strong Cesàro I-asymptotically equivalence.

  18. The New Wind Chill Equivalent Temperature Chart.

    NASA Astrophysics Data System (ADS)

    Osczevski, Randall; Bluestein, Maurice

    2005-10-01

    The formula used in the U.S. and Canada to express the combined effect of wind and low temperature on how cold it feels was changed in November 2001. Many had felt that the old formula for equivalent temperature, derived in the 1960s from Siple and Passel's flawed but quite useful Wind Chill Index, unnecessarily exaggerated the severity of the weather. The new formula is based on a mathematical model of heat flow from the upwind side of a head-sized cylinder moving at walking speed into the wind. The paper details the assumptions that were made in generating the new wind chill charts. It also points out weaknesses in the concept of wind chill equivalent temperature, including its steady-state character and a seemingly paradoxical effect of the internal thermal resistance of the cylinder on comfort and equivalent temperature. Some improvements and alternatives are suggested.

  19. System Equivalent for Real Time Digital Simulator

    NASA Astrophysics Data System (ADS)

    Lin, Xi

    2011-07-01

    The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

  20. Electrophysiological Correlates of Stimulus Equivalence Processes

    PubMed Central

    Haimson, Barry; Wilkinson, Krista M; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J

    2009-01-01

    Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g., wrist, corn). For pairs of both types, event-related cortical potentials were recorded during and immediately after the presentation of the second word. The obtained waveforms differentiated these two types of pairs. For the unrelated pairs, the waveforms were significantly more negative about 400 ms after the second word was presented, thus replicating the “N400” phenomenon of the cognitive neuroscience literature. In addition, there was a strong positive-tending wave form difference post-stimulus presentation (peaked at about 500 ms) that also differentiated the unrelated from related stimulus pairs. In Experiment 2, the procedures were extended to study arbitrary stimulus–stimulus relations established via matching-to-sample training. Participants were experimentally naïve adults. Sample stimuli (Set A) were trigrams, and comparison stimuli (Sets B, C, D, E, and F) were nonrepresentative forms. Behavioral tests evaluated potentially emergent equivalence relations (i.e., BD, DF, CE, etc.). All participants exhibited classes consistent with the arbitrary matching training. They were also exposed also to an event-related potential procedure like that used in Experiment 1. Some received the ERP procedure before equivalence tests and some after. Only those participants who received ERP procedures after equivalence tests exhibited robust N400 differentiation initially. The positivity observed in Experiment 1 was absent for all participants. These results support speculations that equivalence tests may provide contextual support for the formation of equivalence classes including those that emerge gradually during testing

  1. Grammatical equivalents of Palaeolithic tools: a hypothesis.

    PubMed

    Vieira, Antonio B

    2010-09-01

    In this article, language is considered as a behavioural trait evolving by means of natural selection, in co-evolution with the Palaeolithic tool industries. This perspective enables an analysis of the grammatical and syntactic equivalents of the multiple abilities and effects of lithic tools across the successive modes of their development and consider their influence in intra-group communication and the social biology of the hominine species concerned. The hypothesis is that grammatical equivalents inherent to stone tool work guide the evolution of language.

  2. Equivalent Widths in the Spectrum of Sirius

    NASA Astrophysics Data System (ADS)

    Zhao, G.; Qiu, H. M.; Chen, Y. Q.; Li, Z. W.

    2000-02-01

    The equivalent widths of total 546 lines (26 elements are included) in the spectrum of the bright Am star Sirius from 380 to 930 nm are tabulated. The high-resolution, high signal-to-noise ratio spectrum was obtained with the Coudé Echelle Spectrograph attached to the 2.16 m telescope at Beijing Astronomical Observatory (Xinglong, China). Here we also give the results of the equivalent widths comparison between our measurements and those of Strom et al. and Sadakane & Ueta.

  3. 21 CFR 26.6 - Equivalence assessment.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Equivalence assessment. 26.6 Section 26.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  4. 21 CFR 26.9 - Equivalence determination.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Equivalence determination. 26.9 Section 26.9 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  5. CP Violation, Neutral Currents, and Weak Equivalence

    DOE R&D Accomplishments Database

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  6. 46 CFR 154.32 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Compliance may meet an alternate standard if the Commandant (CG-522) finds that the alternate standard provides an equivalent or greater level of protection for the purpose of safety. (b) The Commandant (CG-522... requesting the finding submits a written application to the Commandant (CG-522) that includes— (1) A...

  7. Equivalence of partition properties and determinacy

    PubMed Central

    Kechris, Alexander S.; Woodin, W. Hugh

    1983-01-01

    It is shown that, within L(ℝ), the smallest inner model of set theory containing the reals, the axiom of determinacy is equivalent to the existence of arbitrarily large cardinals below Θ with the strong partition property κ → (κ)κ. PMID:16593299

  8. Pseudo-Equivalent Groups and Linking

    ERIC Educational Resources Information Center

    Haberman, Shelby J.

    2015-01-01

    Adjustment by minimum discriminant information provides an approach to linking test forms in the case of a nonequivalent groups design with no satisfactory common items. This approach employs background information on individual examinees in each administration so that weighted samples of examinees form pseudo-equivalent groups in the sense that…

  9. Electrophysiological Correlates of Stimulus Equivalence Processes

    ERIC Educational Resources Information Center

    Haimson, Barry; Wilkinson, Krista M.; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J.

    2009-01-01

    Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g.,…

  10. The Nature of Dynamic Equivalence in Translating

    ERIC Educational Resources Information Center

    Nida, Eugene A.

    1977-01-01

    A discussion of three types of translation: formal correspondence, cognitive content and emotive response-oriented. The latter two are dynamic-equivalent translations. Their purpose is to enable the receptors to understand the implications of the cognitive content or to make a corresponding emotive response without recourse to the original text.…

  11. HOW TO PASS HIGH SCHOOL EQUIVALENCY EXAMINATION.

    ERIC Educational Resources Information Center

    KLAGSBRUN, FRANCINE, ED.

    ORGANIZED INTO A FIVE-DAY STUDY PLAN, ALLOWING ONE DAY'S STUDY TO EACH PART OF THE EQUIVALENCY EXAMINATION (SPELLING AND GRAMMAR, SOCIAL STUDIES, SCIENCE, LITERATURE, AND MATHEMATICS), THIS BOOK PROVIDES SAMPLE TESTS AND ANSWER SHEETS, A TEST SCORE RECORD AND SELF EVALUATION PROFILE, AND SUPPLEMENTARY TESTS FOR EACH SUBJECT. THE EXAMINEE CAN ORDER…

  12. 21 CFR 26.39 - Equivalence assessment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Equivalence assessment. 26.39 Section 26.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  13. 21 CFR 26.39 - Equivalence assessment.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Equivalence assessment. 26.39 Section 26.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  14. Visual Equivalence and Amodal Completion in Cuttlefish.

    PubMed

    Lin, I-Rong; Chiao, Chuan-Chin

    2017-01-01

    Modern cephalopods are notably the most intelligent invertebrates and this is accompanied by keen vision. Despite extensive studies investigating the visual systems of cephalopods, little is known about their visual perception and object recognition. In the present study, we investigated the visual processing of the cuttlefish Sepia pharaonis, including visual equivalence and amodal completion. Cuttlefish were trained to discriminate images of shrimp and fish using the operant conditioning paradigm. After cuttlefish reached the learning criteria, a series of discrimination tasks were conducted. In the visual equivalence experiment, several transformed versions of the training images, such as images reduced in size, images reduced in contrast, sketches of the images, the contours of the images, and silhouettes of the images, were used. In the amodal completion experiment, partially occluded views of the original images were used. The results showed that cuttlefish were able to treat the training images of reduced size and sketches as the visual equivalence. Cuttlefish were also capable of recognizing partially occluded versions of the training image. Furthermore, individual differences in performance suggest that some cuttlefish may be able to recognize objects when visual information was partly removed. These findings support the hypothesis that the visual perception of cuttlefish involves both visual equivalence and amodal completion. The results from this research also provide insights into the visual processing mechanisms used by cephalopods.

  15. 20 CFR 404.1526 - Medical equivalence.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Medical equivalence. 404.1526 Section 404.1526 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Medical Considerations § 404.1526...

  16. 20 CFR 404.1526 - Medical equivalence.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Medical equivalence. 404.1526 Section 404.1526 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Medical Considerations § 404.1526...

  17. 20 CFR 404.1526 - Medical equivalence.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Medical equivalence. 404.1526 Section 404.1526 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Medical Considerations § 404.1526...

  18. 20 CFR 404.1526 - Medical equivalence.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Medical equivalence. 404.1526 Section 404.1526 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Medical Considerations § 404.1526...

  19. 20 CFR 404.1526 - Medical equivalence.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Medical equivalence. 404.1526 Section 404.1526 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Medical Considerations § 404.1526...

  20. 46 CFR 175.540 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... submitted to the Marine Safety Center via the cognizant OCMI. If necessary, the Marine Safety Center may... submitted to the Marine Safety Center via the cognizant OCMI. (c) The Commandant may approve a novel.... Requests for determination of equivalency must be submitted to Commandant (CG-543) via the cognizant OCMI....

  1. 36 CFR 1192.2 - Equivalent facilitation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Equivalent facilitation. 1192.2 Section 1192.2 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION...

  2. 36 CFR 1192.2 - Equivalent facilitation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Equivalent facilitation. 1192.2 Section 1192.2 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION...

  3. 36 CFR 1192.2 - Equivalent facilitation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Equivalent facilitation. 1192.2 Section 1192.2 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION...

  4. SUPPORT FOR USEPA'S PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    This presentation will discuss recommended and new resources for the USEPA's Pathogen Equivalency Committee including: 1) Committee's creation in 1985 and its purpose 2) Drexel University Professor Chuck Haas' 2001 report (Assessment of the PEC Process) and its findings 3) NAS/NR...

  5. Reading adn Auditory-Visual Equivalences

    ERIC Educational Resources Information Center

    Sidman, Murray

    1971-01-01

    A retarded boy, unable to read orally or with comprehension, was taught to match spoken to printed words and was then capable of reading comprehension (matching printed words to picture) and oral reading (naming printed words aloud), demonstrating that certain learned auditory-visual equivalences are sufficient prerequisites for reading…

  6. 46 CFR 199.09 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CERTAIN INSPECTED VESSELS General § 199.09 Equivalents. When this part requires a particular fitting, material, or lifesaving appliance or arrangement, the Commandant (CG-521) may accept any other fitting... effectiveness of the substitute fitting, material, or lifesaving appliance or arrangement....

  7. Identifiability and Equivalence of GLLIRM Models

    ERIC Educational Resources Information Center

    Revuelta, Javier

    2009-01-01

    The generalized logit-linear item response model (GLLIRM) is a linearly constrained nominal categories model (NCM) that computes the scale and intercept parameters for categories as a weighted sum of basic parameters. This paper addresses the problems of the identifiability of the basic parameters and the equivalence between different GLLIRM…

  8. Equivalence Relations, Contextual Control, and Naming

    ERIC Educational Resources Information Center

    Randell, Tom; Remington, Bob

    2006-01-01

    This paper reports two experiments that investigated the role of verbal behavior in the emergence and generalization of contextually controlled equivalence classes. During both experiments, participants were trained with two different combinations of the same easily nameable, yet formally unrelated, pictorial stimuli. Match-to-sample baselines for…

  9. Visual Equivalence and Amodal Completion in Cuttlefish

    PubMed Central

    Lin, I-Rong; Chiao, Chuan-Chin

    2017-01-01

    Modern cephalopods are notably the most intelligent invertebrates and this is accompanied by keen vision. Despite extensive studies investigating the visual systems of cephalopods, little is known about their visual perception and object recognition. In the present study, we investigated the visual processing of the cuttlefish Sepia pharaonis, including visual equivalence and amodal completion. Cuttlefish were trained to discriminate images of shrimp and fish using the operant conditioning paradigm. After cuttlefish reached the learning criteria, a series of discrimination tasks were conducted. In the visual equivalence experiment, several transformed versions of the training images, such as images reduced in size, images reduced in contrast, sketches of the images, the contours of the images, and silhouettes of the images, were used. In the amodal completion experiment, partially occluded views of the original images were used. The results showed that cuttlefish were able to treat the training images of reduced size and sketches as the visual equivalence. Cuttlefish were also capable of recognizing partially occluded versions of the training image. Furthermore, individual differences in performance suggest that some cuttlefish may be able to recognize objects when visual information was partly removed. These findings support the hypothesis that the visual perception of cuttlefish involves both visual equivalence and amodal completion. The results from this research also provide insights into the visual processing mechanisms used by cephalopods. PMID:28220075

  10. 21 CFR 26.9 - Equivalence determination.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Equivalence determination. 26.9 Section 26.9 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  11. 21 CFR 26.6 - Equivalence assessment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Equivalence assessment. 26.6 Section 26.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  12. Angular Momentum Eigenstates for Equivalent Electrons.

    ERIC Educational Resources Information Center

    Tuttle, E. R.; Calvert, J. B.

    1981-01-01

    Simple and efficient methods for adding angular momenta and for finding angular momentum eigenstates for systems of equivalent electrons are developed. Several different common representations are used in specific examples. The material is suitable for a graduate course in quantum mechanics. (SK)

  13. Are Letter Detection and Proofreading Tasks Equivalent?

    ERIC Educational Resources Information Center

    Saint-Aubin, Jean; Losier, Marie-Claire; Roy, Macha; Lawrence, Mike

    2015-01-01

    When readers search for misspellings in a proofreading task or for a letter in a letter detection task, they are more likely to omit function words than content words. However, with misspelled words, previous findings for the letter detection task were mixed. In two experiments, the authors tested the functional equivalence of both tasks. Results…

  14. 33 CFR 67.01-30 - Equivalents.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Equivalents. 67.01-30 Section 67.01-30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements §...

  15. 33 CFR 67.01-30 - Equivalents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Equivalents. 67.01-30 Section 67.01-30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements §...

  16. 33 CFR 67.01-30 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Equivalents. 67.01-30 Section 67.01-30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements §...

  17. 33 CFR 67.01-30 - Equivalents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Equivalents. 67.01-30 Section 67.01-30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements §...

  18. 33 CFR 67.01-30 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Equivalents. 67.01-30 Section 67.01-30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements §...

  19. 21 CFR 26.39 - Equivalence assessment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Equivalence assessment. 26.39 Section 26.39 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT...

  20. Equivalent weight of humic acid from peat

    USGS Publications Warehouse

    Pommer, A.M.; Breger, I.A.

    1960-01-01

    By means of discontinuous titration, the equivalent weight of humic acid isolated from a peat was found to increase from 144 to 183 between the third and fifty-second day after the humic acid was dissolved. Infra-red studies showed that the material had probably condensed with loss of carbonyl groups. ?? 1960.

  1. 33 CFR 155.120 - Equivalents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Equivalents. 155.120 Section 155.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS General § 155.120...

  2. 33 CFR 155.120 - Equivalents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Equivalents. 155.120 Section 155.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS General § 155.120...

  3. 33 CFR 155.120 - Equivalents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Equivalents. 155.120 Section 155.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS General § 155.120...

  4. 33 CFR 155.120 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Equivalents. 155.120 Section 155.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS General § 155.120...

  5. 33 CFR 155.120 - Equivalents.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Equivalents. 155.120 Section 155.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS General § 155.120...

  6. 46 CFR 170.010 - Equivalents.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., the Commanding Officer (MSC), Attn: Marine Safety Center, U.S. Coast Guard Stop 7410, 4200 Wilson Boulevard Suite 400, Arlington, VA 20598-7410, or the Officer in Charge, Marine Inspection, if the... ALL INSPECTED VESSELS General Provisions § 170.010 Equivalents. Substitutions for fittings,...

  7. 46 CFR 170.010 - Equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., the Commanding Officer, U.S. Coast Guard Marine Safety Center, 2100 2nd St., SW., Stop 7102, Washington, DC 20593-7102, or the Officer in Charge, Marine Inspection, if the substitution provides an... ALL INSPECTED VESSELS General Provisions § 170.010 Equivalents. Substitutions for fittings,...

  8. AN UPDATE ON TECHNOLOGIES SEEKING PFRP EQUIVALENCY

    EPA Science Inventory

    This presentation will: 1) Review the mandate of the Pathogen Equivalency Committee (PEC), 2) Review the PEC's current membership (of 10), 3) Discuss how a typical application is evaluated, 4) Note where information can be found by those interested in applying to the PEC, 5) List...

  9. The equivalent fundamental-mode source

    SciTech Connect

    Spriggs, G.D.; Busch, R.D.; Sakurai, Takeshi; Okajima, Shigeaki

    1997-02-01

    In 1960, Hansen analyzed the problem of assembling fissionable material in the presence of a weak neutron source. Using point kinetics, he defined the weak source condition and analyzed the consequences of delayed initiation during ramp reactivity additions. Although not clearly stated in Hansen`s work, the neutron source strength that appears in the weak source condition corresponds to the equivalent fundamental-mode source. In this work, we describe the concept of an equivalent fundamental-mode source and we derive a deterministic expression for a factor, g*, that converts any arbitrary source distribution to an equivalent fundamental-mode source. We also demonstrate a simplified method for calculating g* in subcritical systems. And finally, we present a new experimental method that can be employed to measure the equivalent fundamental-mode source strength in a multiplying assembly. We demonstrate the method on the zero-power, XIX-1 assembly at the Fast Critical Assembly (FCA) Facility, Japan Atomic Energy Research Institute (JAERI).

  10. Procedures for Determining the Equivalence of Measures.

    ERIC Educational Resources Information Center

    Dunivant, Noel

    Eight different methods are reviewed for determining whether two or more tests are equivalent measures. These methods vary in restrictiveness from the Wilks-Votaw test of compound symmetry (which requires that all means, variances, and covariances are equal), to Joreskog's theory of congeneric tests (which requires only that the tests are measures…

  11. Determination of equivalent weight of amines

    SciTech Connect

    Selig, W.S.

    1987-01-08

    A procedure for the determination of equivalent weight of amines is described. This procedure is based on an acid-base reaction performed in glacial acetic acid. The sum of primary, secondary, and tertiary amines are determined by titration with standard perchloric acid in glacial acetic acid. 1 ref.

  12. Water equivalence of various materials for clinical proton dosimetry by experiment and Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Al-Sulaiti, Leena; Shipley, David; Thomas, Russell; Kacperek, Andrzej; Regan, Patrick; Palmans, Hugo

    2010-07-01

    The accurate conversion of dose to various materials used in clinical proton dosimetry to dose-to-water is based on fluence correction factors, accounting for attenuation of primary protons and production of secondary particles due to non-elastic nuclear interactions. This work aims to investigate the depth dose distribution and the fluence correction with respect to water or graphite at water equivalent depths (WED) in different target materials relevant for dosimetry such as polymethyl methacrylate (PMMA), graphite, A-150, aluminium and copper at 60 and 200 MeV. This was done through a comparison between Monte Carlo simulation using MCNPX 2.5.0, analytical model calculations and experimental measurements at Clatterbridge Centre of Oncology (CCO) in a 60 MeV modulated and un-modulated proton beam. MCNPX simulations indicated small fluence corrections for all materials with respect to graphite and water in 60 and 200 MeV except for aluminium. The analytical calculations showed an increase in the fluence correction factor to a few percent for all materials with respect to water at 200 MeV. The experimental measurements for 60 MeV un-modulated beam indicated a good agreement with MCNPX. For the modulated beam the fluence correction factor was found to be decreasing below unity by up to few percent with depth for aluminium and copper but almost constant and unity for A-150.

  13. A portable dose equivalent meter based on microdosimetry

    NASA Astrophysics Data System (ADS)

    Braby, L. A.

    1985-05-01

    It is generally accepted that the physical basis of the relative biological effectiveness of different radiations is the difference in the spatial distribution of ionization along the charged particle tracks. Thus it is possible to measure physical quantities which may be related to biological damage, and use them to estimate the radiation protection quantity "dose equivalent". A prototype instrument utilizing a spherical proportional counter and a microcomputer to make such measurements has been developed and tested. The detector is filled with gas at low pressure in order to simulate micrometer diameter volumes of tissue. Energy deposition in these small volumes is a stochastic quantity which depends on charged particle stopping power, path length through the site, energy loss straggling, and energy transport by secondary charged particles (delta rays). It has been suggested that this energy deposition distribution be used as a basis for defining radiation quality factor ( overlineQ) [1]. However, to the extent that the energy deposition in the site is proportional to the geometric chord length distribution, energy deposition can also be used to determine the linear energy transfer. The mean quality factor can then be calculated on the basis of the current definition. The prototype instrument uses two amplifiers, with gains of 50 and 1000, processing the pulses from a single detector in order to resolve the wide range of energy deposition events produced by neutron and gamma irradiation. Each amplifier is connected to a specially designed analog to digital converter and a 128 channel multichannel analyzer. A microcomputer controls the system and calculates dose and dose equivalent. Test results for a variety of accelerator produced neutron irradiations show that, from 0.1 to 15 MeV, system accuracy is ±0.5 for overlineQ and ± 15% for dose equivalent.

  14. Representing Identity and Equivalence for Scientific Data

    NASA Astrophysics Data System (ADS)

    Wickett, K. M.; Sacchi, S.; Dubin, D.; Renear, A. H.

    2012-12-01

    Matters of equivalence and identity are central to the stewardship of scientific data. In order to properly prepare for and manage the curation, preservation and sharing of digitally-encoded data, data stewards must be able to characterize and assess the relationships holding between data-carrying digital resources. However, identity-related questions about resources and their information content may not be straightforward to answer: for example, what exactly does it mean to say that two files contain the same data, but in different formats? Information content is frequently distinguished from particular representations, but there is no adequately developed shared understanding of what this really means and how the relationship between content and its representations hold. The Data Concepts group at the Center for Informatics Research in Science and Scholarship (CIRSS), University of Illinois at Urbana Champaign, is developing a logic-based framework of fundamental concepts related to scientific data to support curation and integration. One project goal is to develop precise accounts of information resources carrying the same data. We present two complementary conceptual models for information representation: the Basic Representation Model (BRM) and the Systematic Assertion Model (SAM). We show how these models provide an analytical account of digitally-encoded scientific data and a precise understanding of identity and equivalence. The Basic Representation Model identifies the core entities and relationships involved in representing information carried by digital objects. In BRM, digital objects are symbol structures that express propositional content, and stand in layered encoding relationships. For example, an RDF description may be serialized as either XML or N3, and those expressions in turn may be encoded as either UTF-8 or UTF-16 sequences. Defining this encoding stack reveals distinctions necessary for a precise account of identity and equivalence

  15. Equivalent dose rate by muons to the human body.

    PubMed

    Băcioiu, I

    2011-11-01

    In this paper, the relative sensitivity from different human tissues of the human body, at a ground level, from muon cosmic radiation has been studied. The aim of this paper was to provide information on the equivalent dose rates received from atmospheric muons to human body, at the ground level. The calculated value of the effective dose rate by atmospheric muons plus the radiation levels of the natural annual background radiation dose, at the ground level, in the momentum interval of cosmic ray muon (0.2-120.0 GeV/c) is about 2.106±0.001 mSv/y, which is insignificant in comparison with the values of the doses from the top of the atmosphere.

  16. Scaling Laws for Hydrodynamically Equivalent Implosions

    NASA Astrophysics Data System (ADS)

    Murakami, Masakatsu

    2001-10-01

    The EPOC (equivalent physics of confinement) scenario for the proof of principle of high gain inertial confinement fusion is presented, where the key concept "hydrodynamically equivalent implosions" plays a crucial role. Scaling laws on the target and confinement parameters are derived by applying the Lie group analysis to the PDE (partially differential equations) chain of the hydrodynamic system. It turns out that the conventional scaling law based on adiabatic approximation significantly differs from one which takes such energy transport effect as electron heat conduction into account. Confinement plasma parameters of the hot spot such as the central temperature and the areal mass density at peak compression are obtained with a self-similar solution for spherical implosions.

  17. Equivalent dynamic model of DEMES rotary joint

    NASA Astrophysics Data System (ADS)

    Zhao, Jianwen; Wang, Shu; Xing, Zhiguang; McCoul, David; Niu, Junyang; Huang, Bo; Liu, Liwu; Leng, Jinsong

    2016-07-01

    The dielectric elastomer minimum energy structure (DEMES) can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer (DE), so it is a suitable candidate to make a rotary joint for a soft robot. Dynamic analysis is necessary for some applications, but the dynamic response of DEMESs is difficult to model because of the complicated morphology and viscoelasticity of the DE film. In this paper, a method composed of theoretical analysis and experimental measurement is presented to model the dynamic response of a DEMES rotary joint under an alternating voltage. Based on measurements of equivalent driving force and damping of the DEMES, the model can be derived. Some experiments were carried out to validate the equivalent dynamic model. The maximum angle error between model and experiment is greater than ten degrees, but it is acceptable to predict angular velocity of the DEMES, therefore, it can be applied in feedforward-feedback compound control.

  18. Equivalent Circuit Modeling of Hysteresis Motors

    SciTech Connect

    Nitao, J J; Scharlemann, E T; Kirkendall, B A

    2009-08-31

    We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates, amenable to circuit or digital simulation. 'Hunting' is an oscillatory phenomenon often observed in hysteresis motors. While several works have attempted to model the phenomenon with some partial success, we present a new complete model that predicts hunting from first principles.

  19. Capacitors with low equivalent series resistance

    NASA Technical Reports Server (NTRS)

    Fleig, Patrick Franz (Inventor); Lakeman, Charles D. E. (Inventor); Fuge, Mark (Inventor)

    2011-01-01

    An electric double layer capacitor (EDLC) in a coin or button cell configuration having low equivalent series resistance (ESR). The capacitor comprises mesh or other porous metal that is attached via conducting adhesive to one or both the current collectors. The mesh is embedded into the surface of the adjacent electrode, thereby reducing the interfacial resistance between the electrode and the current collector, thus reducing the ESR of the capacitor.

  20. Quantum mechanics from an equivalence principle

    SciTech Connect

    Faraggi, A.E.; Matone, M.

    1997-05-15

    The authors show that requiring diffeomorphic equivalence for one-dimensional stationary states implies that the reduced action S{sub 0} satisfies the quantum Hamilton-Jacobi equation with the Planck constant playing the role of a covariantizing parameter. The construction shows the existence of a fundamental initial condition which is strictly related to the Moebius symmetry of the Legendre transform and to its involutive character. The universal nature of the initial condition implies the Schroedinger equation in any dimension.

  1. The Otto-engine-equivalent vehicle concept

    NASA Technical Reports Server (NTRS)

    Dowdy, M. W.; Couch, M. D.

    1978-01-01

    A vehicle comparison methodology based on the Otto-Engine Equivalent (OEE) vehicle concept is described. As an illustration of this methodology, the concept is used to make projections of the fuel economy potential of passenger cars using various alternative power systems. Sensitivities of OEE vehicle results to assumptions made in the calculational procedure are discussed. Factors considered include engine torque boundary, rear axle ratio, performance criteria, engine transient response, and transmission shift logic.

  2. Equivalent Multipole Operators for Degenerate Rydberg States

    DTIC Science & Technology

    2006-08-23

    Equivalence of two operators means here that they yield identical matrix elements within a subspace of Hilbert space that corresponds to fixed n. Such...Rydberg atom in time -dependent electric and magnetic fields 6. For example, analytical probabilities have been derived 3–5, without the need for...any perturbative and numerical analysis, for the full array of l→ l transitions in atomic hydrogen Hnl induced by a time -varying weak electric field

  3. Energy conservation economics by investment equivalent

    SciTech Connect

    Larson, R.J.

    1985-08-01

    Investment Equivalents of Energy Savings is a quick and easy technique for companies to assess investment options. Energy conservation proposals must produce an acceptable return before a company will allocate capital. The author describes how the technique operates and how it produces results which allow design engineers, supervisors, and others to choose between alternatives. A hypothetical case provides figures to illustrate how the system develops evaluation criteria and ranks possible solutions. 2 tables.

  4. Einstein's equivalence principle in quantum mechanics revisited

    NASA Astrophysics Data System (ADS)

    Nauenberg, Michael

    2016-11-01

    The gravitational equivalence principle in quantum mechanics is of considerable importance, but it is generally not included in physics textbooks. In this note, we present a precise quantum formulation of this principle and comment on its verification in a neutron diffraction experiment. The solution of the time dependent Schrödinger equation for this problem also gives the wave function for the motion of a charged particle in a homogeneous electric field, which is also usually ignored in textbooks on quantum mechanics.

  5. Semantic relatedness for evaluation of course equivalencies

    NASA Astrophysics Data System (ADS)

    Yang, Beibei

    Semantic relatedness, or its inverse, semantic distance, measures the degree of closeness between two pieces of text determined by their meaning. Related work typically measures semantics based on a sparse knowledge base such as WordNet or Cyc that requires intensive manual efforts to build and maintain. Other work is based on a corpus such as the Brown corpus, or more recently, Wikipedia. This dissertation proposes two approaches to applying semantic relatedness to the problem of suggesting transfer course equivalencies. Two course descriptions are given as input to feed the proposed algorithms, which output a value that can be used to help determine if the courses are equivalent. The first proposed approach uses traditional knowledge sources such as WordNet and corpora for courses from multiple fields of study. The second approach uses Wikipedia, the openly-editable encyclopedia, and it focuses on courses from a technical field such as Computer Science. This work shows that it is promising to adapt semantic relatedness to the education field for matching equivalencies between transfer courses. A semantic relatedness measure using traditional knowledge sources such as WordNet performs relatively well on non-technical courses. However, due to the "knowledge acquisition bottleneck," such a resource is not ideal for technical courses, which use an extensive and growing set of technical terms. To address the problem, this work proposes a Wikipedia-based approach which is later shown to be more correlated to human judgment compared to previous work.

  6. Measurement equivalence in mixed mode surveys.

    PubMed

    Hox, Joop J; De Leeuw, Edith D; Zijlmans, Eva A O

    2015-01-01

    Surveys increasingly use mixed mode data collection (e.g., combining face-to-face and web) because this controls costs and helps to maintain good response rates. However, a combination of different survey modes in one study, be it cross-sectional or longitudinal, can lead to different kinds of measurement errors. For example, respondents in a face-to-face survey or a web survey may interpret the same question differently, and might give a different answer, just because of the way the question is presented. This effect of survey mode on the question-answer process is called measurement mode effect. This study develops methodological and statistical tools to identify the existence and size of mode effects in a mixed mode survey. In addition, it assesses the size and importance of mode effects in measurement instruments using a specific mixed mode panel survey (Netherlands Kinship Panel Study). Most measurement instruments in the NKPS are multi-item scales, therefore confirmatory factor analysis (CFA) will be used as the main analysis tool, using propensity score methods to correct for selection effects. The results show that the NKPS scales by and large have measurement equivalence, but in most cases only partial measurement equivalence. Controlling for respondent differences on demographic variables, and on scale scores from the previous uni-mode measurement occasion, tends to improve measurement equivalence, but not for all scales. The discussion ends with a review of the implications of our results for analyses employing these scales.

  7. TNT equivalency of M10 propellant

    NASA Technical Reports Server (NTRS)

    Mcintyre, F. L.; Price, P.

    1978-01-01

    Peak, side-on blast overpressure and scaled, positive impulse have been measured for M10 single-perforated propellant, web size 0.018 inches, using configurations that simulate the handling of bulk material during processing and shipment. Quantities of 11.34, 22.7, 45.4, and 65.8 kg were tested in orthorhombic shipping containers and fiberboard boxes. High explosive equivalency values for each test series were obtained as a function of scaled distance by comparison to known pressure, arrival time and impulse characteristics for hemispherical TNT surface bursts. The equivalencies were found to depend significantly on scaled distance, with higher values of 150-100 percent (pressure) and 350-125 percent (positive impulse) for the extremes within the range from 1.19 to 3.57 m/cube root of kg. Equivalencies as low as 60-140 percent (pressure) and 30-75 percent (positive impulse) were obtained in the range of 7.14 to 15.8 m/cube root of kg. Within experimental error, both peak pressure and positive impulse scaled as a function of charge weight for all quantities tested in the orthorhombic configuration.

  8. Gingiva Equivalents Secrete Negligible Amounts of Key Chemokines Involved in Langerhans Cell Migration Compared to Skin Equivalents.

    PubMed

    Kosten, Ilona J; Buskermolen, Jeroen K; Spiekstra, Sander W; de Gruijl, Tanja D; Gibbs, Susan

    2015-01-01

    Both oral mucosa and skin have the capacity to maintain immune homeostasis or regulate immune responses upon environmental assault. Whereas much is known about key innate immune events in skin, little is known about oral mucosa. Comparative studies are limited due to the scarce supply of oral mucosa for ex vivo studies. Therefore, we used organotypic tissue equivalents (reconstructed epithelium on fibroblast-populated collagen hydrogel) to study cross talk between cells. Oral mucosa and skin equivalents were compared regarding secretion of cytokines and chemokines involved in LC migration and general inflammation. Basal secretion, representative of homeostasis, and also secretion after stimulation with TNFα, an allergen (cinnamaldehyde), or an irritant (SDS) were assessed. We found that proinflammatory IL-18 and chemokines CCL2, CCL20, and CXCL12, all involved in LC migration, were predominantly secreted by skin as compared to gingiva. Furthermore, CCL27 was predominantly secreted by skin whereas CCL28 was predominantly secreted by gingiva. In contrast, general inflammatory cytokines IL-6 and CXCL8 were secreted similarly by skin and gingiva. These results indicate that the cytokines and chemokines triggering innate immunity and LC migration are different in skin and gingiva. This differential regulation should be figured into novel therapy or vaccination strategies in the context of skin versus mucosa.

  9. Implementation of an analytical model for leakage neutron equivalent dose in a proton radiotherapy planning system.

    PubMed

    Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

    2015-03-11

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects.

  10. Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

    PubMed Central

    Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

    2015-01-01

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects. PMID:25768061

  11. Equivalences between nonuniform exponential dichotomy and admissibility

    NASA Astrophysics Data System (ADS)

    Zhou, Linfeng; Lu, Kening; Zhang, Weinian

    2017-01-01

    Relationship between exponential dichotomies and admissibility of function classes is a significant problem for hyperbolic dynamical systems. It was proved that a nonuniform exponential dichotomy implies several admissible pairs of function classes and conversely some admissible pairs were found to imply a nonuniform exponential dichotomy. In this paper we find an appropriate admissible pair of classes of Lyapunov bounded functions which is equivalent to the existence of nonuniform exponential dichotomy on half-lines R± separately, on both half-lines R± simultaneously, and on the whole line R. Additionally, the maximal admissibility is proved in the case on both half-lines R± simultaneously.

  12. Hysteretic damping in rotordynamics: An equivalent formulation

    NASA Astrophysics Data System (ADS)

    Genta, Giancarlo; Amati, Nicola

    2010-10-01

    The hysteretic damping model cannot be applied to time domain dynamic simulations: this is a well-known feature that has been discussed in the literature since the time when analog computers were widespread. The constant equivalent damping often introduced to overcome this problem is also discussed, and its limitations are stated, in particular those linked with its application in rotordynamics to simulate rotating damping. An alternative model based on the nonviscous damping (NVD) model, but with a limited number of additional degrees of freedom, is proposed, and the relevant equations are derived. Some examples show applications to the rotordynamics field.

  13. Dark matter and the equivalence principle

    NASA Technical Reports Server (NTRS)

    Frieman, Joshua A.; Gradwohl, Ben-Ami

    1991-01-01

    If the dark matter in galaxies and clusters is nonbaryonic, it can interact with additional long-range fields that are invisible to experimental tests of the equivalence principle. The astrophysical and cosmological implications of a long-range force coupled only to the dark matter are discussed and rather tight constraints on its strength are found. If the force is repulsive (attractive), the masses of galaxy groups and clusters (and the mean density of the universe inferred from them) have been systematically underestimated (overestimated). Such an interaction also has unusual implications for the growth of large-scale structure.

  14. Equivalent beam modeling using numerical reduction techniques

    NASA Technical Reports Server (NTRS)

    Chapman, J. M.; Shaw, F. H.

    1987-01-01

    Numerical procedures that can accomplish model reductions for space trusses were developed. Three techniques are presented that can be implemented using current capabilities within NASTRAN. The proposed techniques accomplish their model reductions numerically through use of NASTRAN structural analyses and as such are termed numerical in contrast to the previously developed analytical techniques. Numerical procedures are developed that permit reductions of large truss models containing full modeling detail of the truss and its joints. Three techniques are presented that accomplish these model reductions with various levels of structural accuracy. These numerical techniques are designated as equivalent beam, truss element reduction, and post-assembly reduction methods. These techniques are discussed in detail.

  15. Development and Testing of Living Skin Equivalent.

    DTIC Science & Technology

    1988-05-01

    Model a) The use of Isografts in an inbred strain of rats. In a preliminary series of experiments the potential use of Fischer strain rats has been...tested by preparing a series of isografts made by grafting skin equivalents with cells from female donors to male hosts. On the average, wound...Autograft--rat 4 1 4 3 5 17 Autograft--rabbit 6 3 1 1 11 Isograft --rat 37 13 13 1 64 Allo fib., iso ker--rat 15 12 3 30 Allo fib, iso ker--rab 8 6 14 Iso

  16. Investigating Starburst Galaxy Emission Line Equivalent Widths

    NASA Astrophysics Data System (ADS)

    Meskhidze, Helen; Richardson, Chris T.

    2016-01-01

    Modeling star forming galaxies with spectral synthesis codes allows us to study the gas conditions and excitation mechanisms that are necessary to reproduce high ionization emission lines in both local and high-z galaxies. Our study uses the locally optimally-emitting clouds model to develop an atlas of starburst galaxy emission line equivalent widths. Specifically, we address the following question: What physical conditions are necessary to produce strong high ionization emission lines assuming photoionization via starlight? Here we present the results of our photoionization simulations: an atlas spanning 15 orders of magnitude in ionizing flux and 10 orders of magnitude in hydrogen density that tracks over 150 emission lines ranging from the UV to the near IR. Each simulation grid contains ~1.5x104 photoionization models calculated by supplying a spectral energy distribution, grain content, and chemical abundances. Specifically, we will be discussing the effects on the emission line equivalent widths of varying the metallicity of the cloud, Z = 0.2 Z⊙ to Z = 5.0 Z⊙, and varying the star-formation history, using the instantaneous and continuous evolution tracks and the newly released Starburst99 Geneva rotation tracks.

  17. Validation Of Equivalent Viscous Damping Methodologies

    NASA Astrophysics Data System (ADS)

    Vaquer Araujo, Xavier; Fransen, S. H. J. A.; Germes, S.; Thiry, N.

    2012-07-01

    An important step in the design and verification process of spacecraft structures is the coupled dynamic analysis with the launch vehicle in the low-frequency domain. To obtain accurate predictions of the satellite’s dynamic environment it is essential that the damping of the system is correctly defined and taken into account within the resolution methodologies for the Coupled Loads Analysis (CLA). When working with finite element models, the materials’ damping is characterized by structural damping ratios. In addition, most of the load cases present in the CLA are transient excitations so the resolution of the equations of motion must be done in the time domain. Unfortunately, transient analyses cannot be carried out using structural damping models. Thus, a transformation from a structural to a viscous damping characterization is necessary. Nevertheless, this transformation is not trivial. There exist many methodologies aiming at computing an equivalent viscous damping matrix of the system so it can be used in transient analyses. This paper describes the results obtained in the validation of equivalent viscous damping methodologies used in the European Space Agency. This work permitted to identify the limitations of these methodologies and to come up with an enhanced methodology that predicts more reliable results.

  18. Breaking of Ensemble Equivalence in Networks

    NASA Astrophysics Data System (ADS)

    Squartini, Tiziano; de Mol, Joey; den Hollander, Frank; Garlaschelli, Diego

    2015-12-01

    It is generally believed that, in the thermodynamic limit, the microcanonical description as a function of energy coincides with the canonical description as a function of temperature. However, various examples of systems for which the microcanonical and canonical ensembles are not equivalent have been identified. A complete theory of this intriguing phenomenon is still missing. Here we show that ensemble nonequivalence can manifest itself also in random graphs with topological constraints. We find that, while graphs with a given number of links are ensemble equivalent, graphs with a given degree sequence are not. This result holds irrespective of whether the energy is nonadditive (as in unipartite graphs) or additive (as in bipartite graphs). In contrast with previous expectations, our results show that (1) physically, nonequivalence can be induced by an extensive number of local constraints, and not necessarily by long-range interactions or nonadditivity, (2) mathematically, nonequivalence is determined by a different large-deviation behavior of microcanonical and canonical probabilities for a single microstate, and not necessarily for almost all microstates. The latter criterion, which is entirely local, is not restricted to networks and holds in general.

  19. Equivalent Relaxations of Optimal Power Flow

    SciTech Connect

    Bose, S; Low, SH; Teeraratkul, T; Hassibi, B

    2015-03-01

    Several convex relaxations of the optimal power flow (OPF) problem have recently been developed using both bus injection models and branch flow models. In this paper, we prove relations among three convex relaxations: a semidefinite relaxation that computes a full matrix, a chordal relaxation based on a chordal extension of the network graph, and a second-order cone relaxation that computes the smallest partial matrix. We prove a bijection between the feasible sets of the OPF in the bus injection model and the branch flow model, establishing the equivalence of these two models and their second-order cone relaxations. Our results imply that, for radial networks, all these relaxations are equivalent and one should always solve the second-order cone relaxation. For mesh networks, the semidefinite relaxation and the chordal relaxation are equally tight and both are strictly tighter than the second-order cone relaxation. Therefore, for mesh networks, one should either solve the chordal relaxation or the SOCP relaxation, trading off tightness and the required computational effort. Simulations are used to illustrate these results.

  20. Tissue types (image)

    MedlinePlus

    There are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports other tissues and binds them together (bone, blood, and lymph tissues). ...

  1. Equivalent probability density moments determine equivalent epidemics in an SIRS model with temporary immunity.

    PubMed

    Carr, Thomas W

    2017-02-01

    In an SIRS compartment model for a disease we consider the effect of different probability distributions for remaining immune. We show that to first approximation the first three moments of the corresponding probability densities are sufficient to well describe oscillatory solutions corresponding to recurrent epidemics. Specifically, increasing the fraction who lose immunity, increasing the mean immunity time, and decreasing the heterogeneity of the population all favor the onset of epidemics and increase their severity. We consider six different distributions, some symmetric about their mean and some asymmetric, and show that by tuning their parameters such that they have equivalent moments that they all exhibit equivalent dynamical behavior.

  2. Equivalent magnetization over the World's Ocean

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Choi, Y.; Hamoudi, M.; Erwan, T.; Lesur, V.

    2014-12-01

    As a by-product of our recent work to build a candidate model over the oceans for the World Digital Magnetic Anomaly Map (WDMAM) version 2, we derived global distributions of the equivalent magnetization in oceanic domains. In a first step, we use classic point source forward modeling on a spherical Earth to build a forward model of the marine magnetic anomalies at sea-surface. We estimate magnetization vectors using the age map of the ocean floor, the relative plate motions, the apparent polar wander path for Africa, and a geomagnetic reversal time scale. As magnetized source geometry, we assume 1 km-thick layer bearing a 10 A/m magnetization following the topography of the oceanic basement as defined by the bathymetry and sedimentary thickness. Adding a present-day geomagnetic field model allows the computation of our initial magnetic anomaly model. In a second step, we adjust this model to the existing marine magnetic anomaly data, in order to make it consistent with these data. To do so, we extract synthetic magnetic along the ship tracks for which real data are available and we compare quantitatively the measured and computed anomalies on 100, 200 or 400 km-long sliding windows (depending the spreading rate). Among the possible comparison criteria, we discard the maximal range - too dependent on local values - and the correlation and coherency - the geographical adjustment between model and data being not accurate enough - to favor the standard deviation around the mean value. The ratio between the standard deviations of data and model on each sliding window represent an estimate of the magnetization ratio causing the anomalies, which we interpolate to adjust the initial magnetic anomaly model to the data and therefore compute a final model to be included in our WDMAM candidate over the oceanic regions lacking data. The above ratio, after division by the magnetization of 10 A/m used in the model, represents an estimate of the equivalent magnetization under the

  3. Equivalence between spin Hamiltonians and boson sampling

    NASA Astrophysics Data System (ADS)

    Peropadre, Borja; Aspuru-Guzik, Alán; García-Ripoll, Juan José

    2017-03-01

    Aaronson and Arkhipov showed that predicting or reproducing the measurement statistics of a general linear optics circuit with a single Fock-state input is a classically hard problem. Here we show that this problem, known as boson sampling, is as hard as simulating the short time evolution of a large but simple spin model with long-range X Y interactions. The conditions for this equivalence are the same for efficient boson sampling, namely, having a small number of photons (excitations) as compared to the number of modes (spins). This mapping allows efficient implementations of boson sampling in small quantum computers and simulators and sheds light on the complexity of time evolution with critical spin models.

  4. Phenomenological approaches of inflation and their equivalence

    NASA Astrophysics Data System (ADS)

    Boubekeur, Lotfi; Giusarma, Elena; Mena, Olga; Ramírez, Héctor

    2015-04-01

    In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equivalent from the observational viewpoint, as they single out the same areas in the parameter space, and agree with the inflationary attractors where successful inflation occurs. Rephrased in terms of the familiar picture of a slowly rolling, canonically normalized scalar field, the resulting inflaton excursions in these two approaches are almost identical. Furthermore, once the Galactic dust polarization data from Planck are included in the numerical fits, inflaton excursions can safely take sub-Planckian values.

  5. Equivalent damage validation by variable cluster analysis

    NASA Astrophysics Data System (ADS)

    Drago, Carlo; Ferlito, Rachele; Zucconi, Maria

    2016-06-01

    The main aim of this work is to perform a clustering analysis on the damage relieved in the old center of L'Aquila after the earthquake occurred on April 6, 2009 and to validate an Indicator of Equivalent Damage ED that summarizes the information reported on the AeDES card regarding the level of damage and their extension on the surface of the buildings. In particular we used a sample of 13442 masonry buildings located in an area characterized by a Macroseismic Intensity equal to 8 [1]. The aim is to ensure the coherence between the clusters and its hierarchy identified in the data of damage detected and in the data of the ED elaborated.

  6. Snow water equivalent determination by microwave radiometry

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Foster, J. L.; Hall, D. K.; Rango, A.; Hartline, B. K.

    1981-01-01

    One of the most important parameters for accurate snowmelt runoff prediction is snow water equivalent (SWE) which is contentionally monitored using observations made at widely scattered points in or around specific watersheds. Remote sensors which provide data with better spatial and temporal coverage can be used to improve the SWE estimates. Microwave radiation, which can penetrate through a snowpack, may be used to infer the SWE. Calculations made from a microscopic scattering model were used to simulate the effect of varying SWE on the microwave brightness temperature. Data obtained from truck mounted, airborne and spaceborne systems from various test sites were studied. The simulated SWE compares favorable with the measured SWE. In addition, whether the underlying soil is frozen or thawed can be discriminated successfully on the basis of the polarization of the microwave radiation.

  7. Expressivism, Relativism, and the Analytic Equivalence Test.

    PubMed

    Frápolli, Maria J; Villanueva, Neftalí

    2015-01-01

    The purpose of this paper is to show that, pace (Field, 2009), MacFarlane's assessment relativism and expressivism should be sharply distinguished. We do so by arguing that relativism and expressivism exemplify two very different approaches to context-dependence. Relativism, on the one hand, shares with other contemporary approaches a bottom-up, building block, model, while expressivism is part of a different tradition, one that might include Lewis' epistemic contextualism and Frege's content individuation, with which it shares an organic model to deal with context-dependence. The building-block model and the organic model, and thus relativism and expressivism, are set apart with the aid of a particular test: only the building-block model is compatible with the idea that there might be analytically equivalent, and yet different, propositions.

  8. Expressivism, Relativism, and the Analytic Equivalence Test

    PubMed Central

    Frápolli, Maria J.; Villanueva, Neftalí

    2015-01-01

    The purpose of this paper is to show that, pace (Field, 2009), MacFarlane’s assessment relativism and expressivism should be sharply distinguished. We do so by arguing that relativism and expressivism exemplify two very different approaches to context-dependence. Relativism, on the one hand, shares with other contemporary approaches a bottom–up, building block, model, while expressivism is part of a different tradition, one that might include Lewis’ epistemic contextualism and Frege’s content individuation, with which it shares an organic model to deal with context-dependence. The building-block model and the organic model, and thus relativism and expressivism, are set apart with the aid of a particular test: only the building-block model is compatible with the idea that there might be analytically equivalent, and yet different, propositions. PMID:26635690

  9. Snow water equivalent mapping in Norway

    NASA Astrophysics Data System (ADS)

    Tveito, O. E.; Udnæs, H.-C.; Engeset, R.; Førland, E. J.; Isaksen, K.; Mengistu, Z.

    2003-04-01

    In high latitude area snow covers the ground large parts of the year. Information about the water volume as snow is of major importance in many respects. Flood forecasters at NVE need it in order to assess possible flood risks. Hydropower producers need it to plan the most efficient production of the water in their reservoirs, traders to estimate the potential energy available for the market. Meteorologists on their side use the information as boundary conditions in weather forecasting models. The Norwegian meteorological institute has provided snow accumulation maps for Norway for more than 50 years. These maps are now produced twice a month in the winter season. They show the accumulated precipitation in the winter season from the day the permanent snow cover is established. They do however not take melting into account, and do therefore not give a good description of the actual snow amounts during and after periods with snowmelt. Due to an increased need for a direct measure of water volumes as snow cover, met.no and NVE initialized a joint project in order to establish maps of the actual snow cover expressed in water equivalents. The project utilizes recent developments in the use of GIS in spatial modeling. Daily precipitation and temperature are distributed in space by using objective spatial interpolation methods. The interpolation considers topographical and other geographical parameters as well as weather type information. A degree-day model is used at each modeling point to calculate snow-accumulation and snowmelt. The maps represent a spatial scale of 1x1 km2. The modeled snow reservoir is validated by snow pillow values as well traditional snow depth observations. Preliminary results show that the new snow modeling approach reproduces the snow water equivalent well. The spatial approach also opens for a wide use in the terms of areal analysis.

  10. Equivalence principle implications of modified gravity models

    SciTech Connect

    Hui, Lam; Nicolis, Alberto; Stubbs, Christopher W.

    2009-11-15

    Theories that attempt to explain the observed cosmic acceleration by modifying general relativity all introduce a new scalar degree of freedom that is active on large scales, but is screened on small scales to match experiments. We demonstrate that if such screening occurs via the chameleon mechanism, such as in f(R) theory, it is possible to have order unity violation of the equivalence principle, despite the absence of explicit violation in the microscopic action. Namely, extended objects such as galaxies or constituents thereof do not all fall at the same rate. The chameleon mechanism can screen the scalar charge for large objects but not for small ones (large/small is defined by the depth of the gravitational potential and is controlled by the scalar coupling). This leads to order one fluctuations in the ratio of the inertial mass to gravitational mass. We provide derivations in both Einstein and Jordan frames. In Jordan frame, it is no longer true that all objects move on geodesics; only unscreened ones, such as test particles, do. In contrast, if the scalar screening occurs via strong coupling, such as in the Dvali-Gabadadze-Porrati braneworld model, equivalence principle violation occurs at a much reduced level. We propose several observational tests of the chameleon mechanism: 1. small galaxies should accelerate faster than large galaxies, even in environments where dynamical friction is negligible; 2. voids defined by small galaxies would appear larger compared to standard expectations; 3. stars and diffuse gas in small galaxies should have different velocities, even if they are on the same orbits; 4. lensing and dynamical mass estimates should agree for large galaxies but disagree for small ones. We discuss possible pitfalls in some of these tests. The cleanest is the third one where the mass estimate from HI rotational velocity could exceed that from stars by 30% or more. To avoid blanket screening of all objects, the most promising place to look is in

  11. 40 CFR 61.66 - Equivalent equipment and procedures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Chloride § 61.66 Equivalent equipment and procedures. Upon written application from an owner or operator... satisfaction to be equivalent in terms of reducing vinyl chloride emissions to the atmosphere to...

  12. Elementary equivalence of Chevalley groups over local rings

    SciTech Connect

    Bunina, Elena I

    2010-05-11

    It is proved that (elementary) Chevalley groups over local rings with invertible 2 are elementarily equivalent if and only if their types and weight lattices coincide and the initial rings are elementarily equivalent. Bibliography: 25 titles.

  13. FROM CONCEPT TO EQUIVALENCY: THE 503 REGULATIONS AND THE PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    Since its creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing innovative and alternative sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether t...

  14. FROM CONCEPT TO EQUIVALENCY: THE 503 REGULATIONS AND THE PATHOGEN EQUIVALENCY COMMITTEE (PAPER)

    EPA Science Inventory

    Since its creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing innovative and alternative sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether t...

  15. Optimizing Equivalence-Based Instruction: Effects of Training Protocols on Equivalence Class Formation

    ERIC Educational Resources Information Center

    Fienup, Daniel M.; Wright, Nicole A.; Fields, Lanny

    2015-01-01

    Two experiments evaluated the effects of the simple-to-complex and simultaneous training protocols on the formation of academically relevant equivalence classes. The simple-to-complex protocol intersperses derived relations probes with training baseline relations. The simultaneous protocol conducts all training trials and test trials in separate…

  16. 78 FR 67360 - Ambient Air Monitoring Reference and Equivalent Methods: Designation of Five New Equivalent Methods

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ... equivalent methods are identified as follows: EQPM-1013-207, ``Thermo Scientific TEOM 1405-DF Dichotomous... external enclosures, and operated in accordance with the Thermo Scientific TEOM 1405-DF Dichotomous Ambient..., ``Thermo Scientific TEOM 1405-DF Dichotomous Ambient Particular Monitor with FDMS ,'' configured for...

  17. 77 FR 60985 - Ambient Air Monitoring Reference and Equivalent Methods: Designation of Three New Equivalent Methods

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-05

    ... for Air Pollution Measurement Systems, Volume I,'' EPA/600/R-94/038a and ``Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Quality Monitoring Program'' EPA-454/B... AGENCY Ambient Air Monitoring Reference and Equivalent Methods: Designation of Three New...

  18. Calculation of Dose, Dose Equivalent, and Relative Biological Effectiveness for High Charge and Energy Ion Beams

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Reginatto, M.; Hajnal, F.; Chun, S. Y.

    1995-01-01

    The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H1OT1/2 cell survival and neoplastic transformation as a function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical applications.

  19. Calculation of dose, dose equivalent, and relative biological effectiveness for high charge and energy ion beams

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Chun, S. Y.; Reginatto, M.; Hajnal, F.

    1995-01-01

    The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H10T1/2 cell survival and neo-plastic transformation as function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical application.

  20. Considerations on Estimating Upper Bounds of Neutron Doses Equivalents to Military Participants at Atmospheric Nuclear Tests

    DTIC Science & Technology

    2007-04-01

    Tissue kerma for monoenergetic neutrons of energy up to 14 MeV and contributions from different interactions that produce charged ionizing particles...fluence for each energy group obtained from calculations for monoenergetic neutrons similar to calculations in Figure 2-I, and the energy dependence of the...Considerations on Estimating Upper Bounds of Neutron Dose Equivalents to Military Partici pants at Atmospheric Nuclear Tests Approved for public release

  1. New equivalent-electrical circuit model and a practical measurement method for human body impedance.

    PubMed

    Chinen, Koyu; Kinjo, Ichiko; Zamami, Aki; Irei, Kotoyo; Nagayama, Kanako

    2015-01-01

    Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

  2. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2012-01-01 2012-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  3. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2011-01-01 2011-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  4. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2010-01-01 2010-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  5. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2014-01-01 2014-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  6. 7 CFR 987.105 - Whole equivalent of pitted dates.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Whole equivalent of pitted dates. For the purposes of this part, the whole date equivalent weight of pitted dates shall be determined by dividing the weight of the pitted dates by 0.83. Identification and... 7 Agriculture 8 2013-01-01 2013-01-01 false Whole equivalent of pitted dates. 987.105 Section...

  7. 49 CFR 538.8 - Gallon Equivalents for Gaseous Fuels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.8 Gallon Equivalents for Gaseous Fuels. The gallon equivalent of gaseous fuels, for purposes... 49 Transportation 6 2010-10-01 2010-10-01 false Gallon Equivalents for Gaseous Fuels....

  8. 49 CFR 538.8 - Gallon Equivalents for Gaseous Fuels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.8 Gallon Equivalents for Gaseous Fuels. The gallon equivalent of gaseous fuels, for purposes... 49 Transportation 6 2011-10-01 2011-10-01 false Gallon Equivalents for Gaseous Fuels....

  9. 49 CFR 538.8 - Gallon Equivalents for Gaseous Fuels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.8 Gallon Equivalents for Gaseous Fuels. The gallon equivalent of gaseous fuels, for purposes... 49 Transportation 6 2013-10-01 2013-10-01 false Gallon Equivalents for Gaseous Fuels....

  10. 49 CFR 538.8 - Gallon Equivalents for Gaseous Fuels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.8 Gallon Equivalents for Gaseous Fuels. The gallon equivalent of gaseous fuels, for purposes... 49 Transportation 6 2014-10-01 2014-10-01 false Gallon Equivalents for Gaseous Fuels....

  11. 49 CFR 538.8 - Gallon Equivalents for Gaseous Fuels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.8 Gallon Equivalents for Gaseous Fuels. The gallon equivalent of gaseous fuels, for purposes... 49 Transportation 6 2012-10-01 2012-10-01 false Gallon Equivalents for Gaseous Fuels....

  12. 46 CFR Appendix A to Part 154 - Equivalent Stress

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Equivalent Stress A Appendix A to Part 154 Shipping...—Equivalent Stress I. Equivalent stress (σ c) is calculated by the following formula or another formula... normal stress in “x” direction. σy=total normal stress in “y” direction. τxy=total shear stress in...

  13. 46 CFR Appendix A to Part 154 - Equivalent Stress

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Equivalent Stress A Appendix A to Part 154 Shipping...—Equivalent Stress I. Equivalent stress (σ c) is calculated by the following formula or another formula... normal stress in “x” direction. σy=total normal stress in “y” direction. τxy=total shear stress in...

  14. 46 CFR Appendix A to Part 154 - Equivalent Stress

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Equivalent Stress A Appendix A to Part 154 Shipping...—Equivalent Stress I. Equivalent stress (σ c) is calculated by the following formula or another formula... normal stress in “x” direction. σy=total normal stress in “y” direction. τxy=total shear stress in...

  15. Tests of Equivalence for One-Way Independent Groups Designs

    ERIC Educational Resources Information Center

    Cribbie, Robert A.; Arpin-Cribbie, Chantal A.; Gruman, Jamie A.

    2009-01-01

    Researchers in education are often interested in determining whether independent groups are equivalent on a specific outcome. Equivalence tests for 2 independent populations have been widely discussed, whereas testing for equivalence with more than 2 independent groups has received little attention. The authors discuss alternatives for testing the…

  16. Reasons for the Decalage between Identity Conservation and Equivalence Conservation.

    ERIC Educational Resources Information Center

    Gold, Ron

    1983-01-01

    Two experiments investigated which of two factors is responsible for decalage between Piaget's equivalence and identity conservation tasks. Performance of 78 primary school students between 57 and 79 months of age was compared on equivalence and identity tasks and a third task, equivalence I, which retains transitivity requirement of Piaget's task…

  17. Equivalent Circuits For AC-Impedance Analysis Of Corrosion

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Report presents investigation of equivalent circuits for ac-impedance analysis of corrosion. Impedance between specimen and electrolyte measured as function of frequency. Data used to characterize corrosion electrochemical system in terms of equivalent circuit. Eleven resistor/capacitor equivalent-circuit models were analyzed.

  18. Tests of the weak equivalence principle

    NASA Astrophysics Data System (ADS)

    Speake, C. C.; Will, C. M.

    2012-09-01

    The Einstein equivalence principle is the foundation for general relativity and all metric theories of gravity. Of its three tenets—the equality of acceleration of test bodies, or weak equivalence principle; the validity of Lorentz invariance in local freely falling frames; and the position invariance of local physical laws—the weak equivalence principle has played the most important role historically, and continues to be a focus of intense theoretical and experimental investigation. From the probably apocryphal 16th century demonstrations by Galileo at Pisa's leaning tower to the sensitive torsion-balance measurements of today (both pictured on the cover of this issue), this principle, dubbed WEP, has been crucial to the development of gravitation theory. The universality of the rate of acceleration of all types of matter in a gravitational field can be taken as evidence that gravitation is fundamentally determined by the geometry, or metric, of spacetime. Newton began his magnum opus 'The Principia' with a discussion of WEP and his experiments to verify it, while Einstein took WEP for granted in his construction of general relativity, never once referring to the epochal experiments by Baron Eötvös. The classic 1964 experiment of Roll, Krotkov and Dicke ushered in the modern era of high-precision tests, and the search for a 'fifth force' during the late 1980s (instigated, ironically, by purported anomalies in Eötvös's old data) caused the enterprise to pivot from pure tests of the foundation of GR to searches for new physics beyond the standard model of the non-gravitational interactions. Today, the next generation of experimental tests of WEP are being prepared for launch or are being developed, with the goal of reaching unprecedented levels of sensitivity, in search of signatures of interactions inspired by string theory, extra dimensions and other concepts from the world of high-energy physics. At the same time observations continue using lunar laser

  19. Tissue repair

    PubMed Central

    2010-01-01

    As living beings that encounter every kind of traumatic event from paper cut to myocardial infarction, we must possess ways to heal damaged tissues. While some animals are able to regrow complete body parts following injury (such as the earthworm who grows a new head following bisection), humans are sadly incapable of such feats. Our means of recovery following tissue damage consists largely of repair rather than pure regeneration. Thousands of times in our lives, a meticulously scripted but unseen wound healing drama plays, with cells serving as actors, extracellular matrix as the setting and growth factors as the means of communication. This article briefly reviews the cells involved in tissue repair, their signaling and proliferation mechanisms and the function of the extracellular matrix, then presents the actors and script for the three acts of the tissue repair drama. PMID:21220961

  20. Class 1 Integron-Borne, Multiple-Antibiotic Resistance Encoded by a 150-Kilobase Conjugative Plasmid in Epidemic Vibrio cholerae O1 Strains Isolated in Guinea-Bissau

    PubMed Central

    Dalsgaard, Anders; Forslund, Anita; Petersen, Andreas; Brown, Derek J.; Dias, Francisco; Monteiro, Serifo; Mølbak, Kåre; Aaby, Peter; Rodrigues, Amabelia; Sandström, Anita

    2000-01-01

    In the 1996–1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality rate from 1.0% before the emergence of the multiple-drug-resistant strain to 5.3% after the emergence of the strain. Our study shows that the strain contained a 150-kb conjugative multiple-antibiotic resistance plasmid with class 1 integron-borne gene cassettes encoding resistance to trimethoprim (dhfrXII) and aminoglycosides [ant(3")-1a]). The finding of transferable resistance to almost all of the antibiotics commonly used to treat cholera is of great public health concern. Studies should be carried out to determine to what extent the strain or its resistance genes have been spread to other areas where cholera is endemic. PMID:11015401

  1. Tissue Issues

    ERIC Educational Resources Information Center

    Metz, James

    2016-01-01

    Every day, 27,000 trees are used to make bathroom tissue. Americans use an average of 23.6 rolls per person per year, and more than 7 billion rolls of toilet paper are sold yearly in the United States alone. Perhaps the amount of bathroom tissue used can be reduced by changing the dimensions of the paper or the core. This brief article presents…

  2. Biomonitoring Equivalents for interpretation of urinary fluoride.

    PubMed

    Aylward, L L; Hays, S M; Vezina, A; Deveau, M; St-Amand, A; Nong, A

    2015-06-01

    Exposure to fluoride is widespread due to its natural occurrence in the environment and addition to drinking water and dental products for the prevention of dental caries. The potential health risks of excess fluoride exposure include aesthetically unacceptable dental fluorosis (tooth mottling) and increased skeletal fragility. Numerous organizations have conducted risk assessments and set guidance values to represent maximum recommended exposure levels as well as recommended adequate intake levels based on potential public health benefits of fluoride exposure. Biomonitoring Equivalents (BEs) are estimates of the average biomarker concentrations corresponding to such exposure guidance values. The literature on daily urinary fluoride excretion rates as a function of daily fluoride exposure was reviewed and BE values corresponding to the available US and Canadian exposure guidance values were derived for fluoride in urine. The derived BE values range from 1.1 to 2.1mg/L (1.2-2.5μg/g creatinine). Concentrations of fluoride in single urinary spot samples from individuals, even under exposure conditions consistent with the exposure guidance values, may vary from the predicted average concentrations by several-fold due to within- and across-individual variation in urinary flow and creatinine excretion rates and due to the rapid elimination kinetics of fluoride. Thus, the BE values are most appropriately applied to screen population central tendency estimates for biomarker concentrations rather than interpretation of individual spot sample concentrations.

  3. Validation of equivalent viscous damping methodologies

    NASA Astrophysics Data System (ADS)

    Vaquer Araujo, Xavier; Fransen, Sebastiaan H. J. A.; Germès, Sylvain; Thiry, Nicolas

    2013-06-01

    An important step in the design and verification process of spacecraft structures is the coupled dynamic analysis with the launch vehicle in the low-frequency domain. To obtain accurate predictions of the satellite's dynamic environment, it is essential that the damping of the system is correctly defined and taken into account within the resolution methodologies for the coupled loads analysis (CLA). When working with finite element models, the materials' damping is characterized by structural damping ratios. In addition, most of the load cases present in the CLA are transient excitations, and so the resolution of the equations of motion must be done in the time domain. Unfortunately, in the CLA, transient analyses cannot be carried out using structural damping models. Thus, a transformation from a structural to a viscous damping characterization is necessary in this case. Nevertheless, this transformation is not trivial. There exist many methodologies for computing an equivalent viscous damping (EqVD) matrix of the system which can be used in transient analyses. This paper describes the results obtained from the validation of EqVD methodologies used in the European Space Agency. This work identifies the limitations of these methodologies and comes up with an enhanced methodology that predicts more reliable results.

  4. Equivalence principle and the baryon acoustic peak

    NASA Astrophysics Data System (ADS)

    Baldauf, Tobias; Mirbabayi, Mehrdad; Simonović, Marko; Zaldarriaga, Matias

    2015-08-01

    We study the dominant effect of a long wavelength density perturbation δ (λL) on short distance physics. In the nonrelativistic limit, the result is a uniform acceleration, fixed by the equivalence principle, and typically has no effect on statistical averages due to translational invariance. This same reasoning has been formalized to obtain a "consistency condition" on the cosmological correlation functions. In the presence of a feature, such as the acoustic peak at ℓBAO, this naive expectation breaks down for λL<ℓBAO. We calculate a universal piece of the three-point correlation function in this regime. The same effect is shown to underlie the spread of the acoustic peak, and is calculable to all orders in the long modes. This can be used to improve the result of perturbative calculations—a technique known as "infra-red resummation"—and is explicitly applied to the one-loop calculation of the power spectrum. Finally, the success of baryon acoustic oscillation reconstruction schemes is argued to be another empirical evidence for the validity of the results.

  5. Challenging a culture of racial equivalence.

    PubMed

    Song, Miri

    2014-03-01

    We live at a time when our understandings and conceptualizations of 'racism' are often highly imprecise, broad, and used to describe a wide range of racialized phenomena. In this article, I raise some important questions about how the term racism is used and understood in contemporary British society by drawing on some recent cases of alleged racism in football and politics, many of which have been played out via new media technologies. A broader understanding of racism, through the use of the term 'racialization', has been helpful in articulating a more nuanced and complex understanding of racial incidents, especially of people's (often ambivalent) beliefs and behaviours. However, the growing emphasis upon 'racialization' has led to a conceptualization of racism which increasingly involves multiple perpetrators, victims, and practices without enough consideration of how and why particular interactions and practices constitute racism as such. The trend toward a growing culture of racial equivalence is worrying, as it denudes the idea of racism of its historical basis, severity and power. These frequent and commonplace assertions of racism in the public sphere paradoxically end up trivializing and homogenizing quite different forms of racialized interactions. I conclude that we need to retain the term 'racism', but we need to differentiate more clearly between 'racism' (as an historical and structured system of domination) from the broader notion of 'racialization'.

  6. A restricted proof that the weak equivalence principle implies the Einstein equivalence principle

    NASA Technical Reports Server (NTRS)

    Lightman, A. P.; Lee, D. L.

    1973-01-01

    Schiff has conjectured that the weak equivalence principle (WEP) implies the Einstein equivalence principle (EEP). A proof is presented of Schiff's conjecture, restricted to: (1) test bodies made of electromagnetically interacting point particles, that fall from rest in a static, spherically symmetric gravitational field; (2) theories of gravity within a certain broad class - a class that includes almost all complete relativistic theories that have been found in the literature, but with each theory truncated to contain only point particles plus electromagnetic and gravitational fields. The proof shows that every nonmentric theory in the class (every theory that violates EEP) must violate WEP. A formula is derived for the magnitude of the violation. It is shown that WEP is a powerful theoretical and experimental tool for constraining the manner in which gravity couples to electromagnetism in gravitation theories.

  7. Effective dose equivalent on the ninth Shuttle--Mir mission (STS-91)

    NASA Technical Reports Server (NTRS)

    Yasuda, H.; Badhwar, G. D.; Komiyama, T.; Fujitaka, K.

    2000-01-01

    Organ and tissue doses and effective dose equivalent were measured using a life-size human phantom on the ninth Shuttle-Mir Mission (STS-91, June 1998), a 9.8-day spaceflight at low-Earth orbit (about 400 km in altitude and 51.65 degrees in inclination). The doses were measured at 59 positions using a combination of thermoluminescent dosimeters of Mg(2)SiO(4):Tb (TDMS) and plastic nuclear track detectors (PNTD). In correcting the change in efficiency of the TDMS, it was assumed that reduction of efficiency is attributed predominantly to HZE particles with energy greater than 100 MeV nucleon(-1). A conservative calibration curve was chosen for determining LET from the PNTD track-formation sensitivities. The organ and tissue absorbed doses during the mission ranged from 1.7 to 2.7 mGy and varied by a factor of 1.6. The dose equivalent ranged from 3.4 to 5.2 mSv and varied by a factor of 1.5 on the basis of the dependence of Q on LET in the 1990 recommendations of the ICRP. The effective quality factor (Q(e)) varied from 1.7 to 2.4. The dose equivalents for several radiation-sensitive organs, such as the stomach, lung, gonad and breast, were not significantly different from the skin dose equivalent (H(skin)). The effective dose equivalent was evaluated as 4.1 mSv, which was about 90% of the H(skin).

  8. Kinetic simulation of hydrodynamic equivalent capsule implosions

    NASA Astrophysics Data System (ADS)

    Kwan, Thomas; Le, Ari; Schmitt, Mark; Herrmann, Hans

    2016-10-01

    We have carried out simulations of direct-drive hydrodynamic equivalent capsule implosion experiments conducted on Omega laser facility at the Laboratory of Laser Energetics of the University of Rochester. The capsules had a glass shell (SiO2) 4.87 μm with an inner diameter of 1086 μm. One was filled with deuterium (D) and tritium (T) at 6.635 and 2.475 atmospheric pressure respectively. The other capsule with D, T, and He-3 at 2.475, 2.475, and 5.55 atmospheric pressure respectively. The capsules were imploded with 60 laser beams with a square pulse length of 0.6ns of total energy of 15.6 kJ. One-dimensional radiation hydrodynamic calculations with HYDRA and kinetic particle/hybrid simulations with LSP are carried out for the post-shot analysis. HYDRA outputs at 0.6ns are linked to LSP, in which the electrons are treated as a fluid while all the ion dynamics is simulated by the standard particle-in-cell technique. Additionally, simulations with the new photon package in LSP are initiated at the beginning of the implosion to include the implosion phase of the capsule. The simulation results of density, temperature, and velocity profiles of the electrons, D, T, He-3, and SiO2species are compared with HYDRA. Detail comparisons among the kinetic simulations, rad-hydro simulations, and experimental results of neutron yield, yield ratio, fusion burn histories, and shell convergence will be presented to assess plasma kinetic effects. Work performed under the auspices of the US DOE by the Los Alamos National Laboratory under Contract No. W7405-ENG-36.

  9. Principle of Spacetime and Black Hole Equivalence

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2016-06-01

    Modelling the universe without relying on a set of hypothetical entities (HEs) to explain observations and overcome problems and difficulties is essential to developing a physical cosmology. The well-known big bang cosmology, widely accepted as the standard model, stands on two fundamentals, which are Einstein’s general relativity (GR) that describes the effect of matter on spacetime and the cosmological principle (CP) of spacetime isotropy and homogeneity. The field equation of GR along with the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric of spacetime derived from CP generates the Friedmann equation (FE) that governs the development and dynamics of the universe. The big bang theory has made impressive successes in explaining the universe, but still has problems and solutions of them rely on an increasing number of HEs such as inflation, dark matter, dark energy, and so on. Recently, the author has developed a new cosmological model called black hole universe, which, instead of making many those hypotheses, only includes a new single postulate (or a new principle) to the cosmology - Principle of Spacetime and Black Hole Equivalence (SBHEP) - to explain all the existing observations of the universe and overcome all the existing problems in conventional cosmologies. This study thoroughly demonstrates how this newly developed black hole universe model, which therefore stands on the three fundamentals (GR, CP, and SBHEP), can fully explain the universe as well as easily conquer the difficulties according to the well-developed physics, thus, neither needing any other hypotheses nor existing any unsolved difficulties. This work was supported by NSF/REU (Grant #: PHY-1263253) at Alabama A & M University.

  10. Tissue Classification

    SciTech Connect

    Robinson, David Gerald

    2015-01-01

    The project began as a e ort to support InLight and Lumidigm. With the sale of the companies to a non-New Mexico entity, the project then focused on supporting a new company Medici Technologies. The Small Business (SB) is attempting to quantify glucose in tissue using a series of short interferometer scans of the nger. Each scan is produced from a novel presentation of the nger to the device. The intent of the project is to identify and, if possible, implement improved methods for classi cation, feature selection, and training to improve the performance of predictive algorithms used for tissue classi cation.

  11. An equivalent viscoelastic model for rock mass with parallel joints

    NASA Astrophysics Data System (ADS)

    Li, Jianchun; Ma, Guowei; Zhao, Jian

    2010-03-01

    An equivalent viscoelastic medium model is proposed for rock mass with parallel joints. A concept of "virtual wave source (VWS)" is proposed to take into account the wave reflections between the joints. The equivalent model can be effectively applied to analyze longitudinal wave propagation through discontinuous media with parallel joints. Parameters in the equivalent viscoelastic model are derived analytically based on longitudinal wave propagation across a single rock joint. The proposed model is then verified by applying identical incident waves to the discontinuous and equivalent viscoelastic media at one end to compare the output waves at the other end. When the wavelength of the incident wave is sufficiently long compared to the joint spacing, the effect of the VWS on wave propagation in rock mass is prominent. The results from the equivalent viscoelastic medium model are very similar to those determined from the displacement discontinuity method. Frequency dependence and joint spacing effect on the equivalent viscoelastic model and the VWS method are discussed.

  12. Estimating Equivalency of Explosives Through A Thermochemical Approach

    SciTech Connect

    Maienschein, J L

    2002-07-08

    The Cheetah thermochemical computer code provides an accurate method for estimating the TNT equivalency of any explosive, evaluated either with respect to peak pressure or the quasi-static pressure at long time in a confined volume. Cheetah calculates the detonation energy and heat of combustion for virtually any explosive (pure or formulation). Comparing the detonation energy for an explosive with that of TNT allows estimation of the TNT equivalency with respect to peak pressure, while comparison of the heat of combustion allows estimation of TNT equivalency with respect to quasi-static pressure. We discuss the methodology, present results for many explosives, and show comparisons with equivalency data from other sources.

  13. A first vascularized skin equivalent for as an alternative to animal experimentation.

    PubMed

    Groeber, Florian; Engelhardt, Lisa; Lange, Julia; Kurdyn, Szymon; Schmid, Freia F; Rücker, Christoph; Mielke, Stephan; Walles, Heike; Hansmann, Jan

    2016-01-01

    Tissue-engineered skin equivalents mimic key aspects of the human skin, and can thus be employed as wound coverage for large skin defects or as in vitro test systems as an alternative to animal models. However, current skin equivalents lack a functional vasculature limiting clinical and research applications. This study demonstrates the generation of a vascularized skin equivalent with a perfused vascular network by combining a biological vascularized scaffold (BioVaSc) based on a decellularized segment of a porcine jejunum and a tailored bioreactor system. Briefly, the BioVaSc was seeded with human fibroblasts, keratinocytes, and human microvascular endothelial cells. After 14 days at the air-liquid interface, hematoxylin & eosin and immunohistological staining revealed a specific histological architecture representative of the human dermis and epidermis including a papillary-like architecture at the dermal-epidermal-junction. The formation of the skin barrier was measured non-destructively using impedance spectroscopy. Additionally, endothelial cells lined the walls of the formed vessels that could be perfused with a physiological volume flow. Due to the presence of a complex in-vivo-like vasculature, the here shown skin equivalent has the potential for skin grafting and represents a sophisticated in vitro model for dermatological research.

  14. Construction of a Corneal Stromal Equivalent with SMILE-Derived Lenticules and Fibrin Glue

    PubMed Central

    Yin, Houfa; Qiu, Peijin; Wu, Fang; Zhang, Wei; Teng, Wenqi; Qin, Zhenwei; Li, Chao; Zhou, Jiaojie; Fang, Zhi; Tang, Qiaomei; Fu, Qiuli; Ma, Jian; Yang, Yabo

    2016-01-01

    The scarcity of corneal tissue to treat deep corneal defects and corneal perforations remains a challenge. Currently, small incision lenticule extraction (SMILE)-derived lenticules appear to be a promising alternative for the treatment of these conditions. However, the thickness and toughness of a single piece of lenticule are limited. To overcome these limitations, we constructed a corneal stromal equivalent with SMILE-derived lenticules and fibrin glue. In vitro cell culture revealed that the corneal stromal equivalent could provide a suitable scaffold for the survival and proliferation of corneal epithelial cells, which formed a continuous pluristratified epithelium with the expression of characteristic markers. Finally, anterior lamellar keratoplasty in rabbits demonstrated that the corneal stromal equivalent with decellularized lenticules and fibrin glue could repair the anterior region of the stroma, leading to re-epithelialization and recovery of both transparency and ultrastructural organization. Corneal neovascularization, graft degradation, and corneal rejection were not observed within 3 months. Taken together, the corneal stromal equivalent with SMILE-derived lenticules and fibrin glue appears to be a safe and effective alternative for the repair of damage to the anterior cornea, which may provide new avenues in the treatment of deep corneal defects or corneal perforations. PMID:27651001

  15. Equivalent Sensor Radiance Generation and Remote Sensing from Model Parameters. Part 1; Equivalent Sensor Radiance Formulation

    NASA Technical Reports Server (NTRS)

    Wind, Galina; DaSilva, Arlindo M.; Norris, Peter M.; Platnick, Steven E.

    2013-01-01

    In this paper we describe a general procedure for calculating equivalent sensor radiances from variables output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint the algorithm takes explicit account of the model subgrid variability, in particular its description of the probably density function of total water (vapor and cloud condensate.) The equivalent sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies. We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products.) We focus on clouds and cloud/aerosol interactions, because they are very important to model development and improvement.

  16. Immunolocalization of a 110 kD molecule and a 150 kD molecule in rat incisor and mandibular bone.

    PubMed

    Chardin, H; Septier, D; Goldberg, M

    1991-03-01

    In the present study, antibodies against rat dental proteoglycans were used to characterize and localize the proteoglycans in rat incisor and mandibular tissues. Polyclonal rabbit antibodies were raised against a CPC-precipitated fraction of a sulfated dental extract. In unpurified dental extract these antibodies recognized two molecules of 110 kD and 150 kD. The 150 kD molecule was susceptible to chondroitinase ABC digestion but the 110 kD molecule resisted this enzymatic degradation. Immunocytochemically these two molecules were seen to be located in the pulp, the enamel organ and the mandibular bone. In each tissue only the periphery of the cells was stained and not the intracellular compartment. In the mineralized area of bone, dentin and forming enamel no staining was seen. These results indicate common epitopes in the proteoglycans from pulp, predentin, enamel organ and bone. Some differences were found in the nature of tooth and bone proteoglycans.

  17. Assessment of the effective dose equivalent for external photon radiation

    SciTech Connect

    Reece, W.D.; Poston, J.W.; Xu, X.G. )

    1993-02-01

    Beginning in January 1994, US nuclear power plants must change the way that they determine the radiation exposure to their workforce. At that time, revisions to Title 10 Part 20 of the Code of Federal Regulations will be in force requiring licensees to evaluate worker radiation exposure using a risk-based methodology termed the effective dose equivalent.'' A research project was undertaken to improve upon the conservative method presently used for assessing effective dose equivalent. In this project effective dose equivalent was calculated using a mathematical model of the human body, and tracking photon interactions for a wide variety of radiation source geometries using Monte Carlo computer code simulations. Algorithms were then developed to relate measurements of the photon flux on the surface of the body (as measured by dosimeters) to effective dose equivalent. This report (Volume I of a two-part study) describes: the concept of effective dose equivalent, the evolution of the concept and its incorporation into regulations, the variations in human organ susceptibility to radiation, the mathematical modeling and calculational techniques used, the results of effective dose equivalent calculations for a broad range of photon energiesand radiation source geometries. The study determined that for beam radiation sources the highest effective dose equivalent occurs for beams striking the front of the torso. Beams striking the rear of the torsoproduce the next highest effective dose equivalent, with effective dose equivalent falling significantly as one departs from these two orientations. For point sources, the highest effective dose equivalent occurs when the sources are in contact with the body on the front of the torso. For females the highest effective dose equivalent occurs when the source is on the sternum, for males when it is on the gonads.

  18. Pumpless microfluidic platform for drug testing on human skin equivalents

    PubMed Central

    Abaci, Hasan Erbil; Gledhill, Karl; Guo, Zongyou; Christiano, Angela M.; Shuler, Michael L.

    2014-01-01

    Advances in bio-mimetic in vitro human skin models increase the efficiency of drug screening studies. In this study, we designed and developed a microfluidic platform that allows for long-term maintenance of full thickness human skin equivalents (HSE) which are comprised of both the epidermal and dermal compartments. The design is based on the physiologically relevant blood residence times in human skin tissue and allows for the establishment of an air-epidermal interface which is crucial for maturation and terminal differentiation of HSEs. The small scale of the design reduces the amount of culture medium and the number of cells required by 36 fold compared to conventional transwell cultures. Our HSE-on-a-chip platform has the capability to recirculate the medium at desired flow rates without the need for pump or external tube connections. We demonstrate that the platform can be used to maintain HSEs for three weeks with proliferating keratinocytes similar to conventional HSE cultures. Immunohistochemistry analyses show that the differentiation and localization of keratinocytes was successfully achieved, establishing all sub-layers of the epidermis after one week. Basal keratinocytes located at the epidermal-dermal interface remain in a proliferative state for three weeks. We use a transdermal transport model to show that the skin barrier function is maintained for three weeks. We also validate the capability of the HSE-on-a-chip platform to be used for drug testing purposes by examining the toxic effects of doxorubucin on skin cells and structure. Overall, the HSE-on-a-chip is a user-friendly and cost-effective in vitro platform for drug testing of candidate molecules for skin disorders. PMID:25490891

  19. Pumpless microfluidic platform for drug testing on human skin equivalents.

    PubMed

    Abaci, Hasan Erbil; Gledhill, Karl; Guo, Zongyou; Christiano, Angela M; Shuler, Michael L

    2015-02-07

    Advances in bio-mimetic in vitro human skin models increase the efficiency of drug screening studies. In this study, we designed and developed a microfluidic platform that allows for long-term maintenance of full thickness human skin equivalents (HSE) which are comprised of both the epidermal and dermal compartments. The design is based on the physiologically relevant blood residence times in human skin tissue and allows for the establishment of an air-epidermal interface which is crucial for maturation and terminal differentiation of HSEs. The small scale of the design reduces the amount of culture medium and the number of cells required by 36 fold compared to conventional transwell cultures. Our HSE-on-a-chip platform has the capability to recirculate the medium at desired flow rates without the need for pump or external tube connections. We demonstrate that the platform can be used to maintain HSEs for three weeks with proliferating keratinocytes similar to conventional HSE cultures. Immunohistochemistry analyses show that the differentiation and localization of keratinocytes was successfully achieved, establishing all sub-layers of the epidermis after one week. Basal keratinocytes located at the epidermal-dermal interface remain in a proliferative state for three weeks. We use a transdermal transport model to show that the skin barrier function is maintained for three weeks. We also validate the capability of the HSE-on-a-chip platform to be used for drug testing purposes by examining the toxic effects of doxorubucin on skin cells and structure. Overall, the HSE-on-a-chip is a user-friendly and cost-effective in vitro platform for drug testing of candidate molecules for skin disorders.

  20. Deuterons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2011-01-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ((2)H(+)) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by <3%. The greatest difference, 47%, occurred at 30 MeV.

  1. Chip-based liver equivalents for toxicity testing--organotypicalness versus cost-efficient high throughput.

    PubMed

    Materne, Eva-Maria; Tonevitsky, Alexander G; Marx, Uwe

    2013-09-21

    Drug-induced liver toxicity dominates the reasons for pharmaceutical product ban, withdrawal or non-approval since the thalidomide disaster in the late-1950s. Hopes to finally solve the liver toxicity test dilemma have recently risen to a historic level based on the latest progress in human microfluidic tissue culture devices. Chip-based human liver equivalents are envisaged to identify liver toxic agents regularly undiscovered by current test procedures at industrial throughput. In this review, we focus on advanced microfluidic microscale liver equivalents, appraising them against the level of architectural and, consequently, functional identity with their human counterpart in vivo. We emphasise the inherent relationship between human liver architecture and its drug-induced injury. Furthermore, we plot the current socio-economic drug development environment against the possible value such systems may add. Finally, we try to sketch a forecast for translational innovations in the field.

  2. Equivalent sphere approximations for skin, eye, and blood-forming organs

    SciTech Connect

    Maxson, W.L.; Townsend, L.W.; Bier, S.G.

    1996-12-31

    Throughout the manned spaceflight program, protecting astronauts from space radiation has been the subject of intense study. For interplanetary crews, two main sources of radiation hazards are solar particle events (SPEs) and galactic cosmic rays. For nearly three decades, crew doses and related shielding requirements have been assessed using the assumption that body organ exposures are well approximated by exposures at the center of tissue-equivalent spheres. For the skin and for blood-forming organs (BFOs), these spheres have radii of 0 and 5 cm, respectively. Recent studies indicate that significant overestimation of organ doses occurs if these models are used instead of realistic human geometry models. The use of the latter, however, requires much longer computational times. In this work, the authors propose preliminary revisions to these equivalent sphere approximations that yield more realistic dose estimates.

  3. 30 CFR 71.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Approved sampling devices; equivalent... OF UNDERGROUND COAL MINES Sampling Procedures § 71.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  4. 30 CFR 90.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Approved sampling devices; equivalent... DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  5. 30 CFR 70.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Approved sampling devices; equivalent... § 70.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in milligrams collected on the filter of an...

  6. 30 CFR 90.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Approved sampling devices; equivalent... DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  7. 30 CFR 70.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Approved sampling devices; equivalent... § 70.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in milligrams collected on the filter of an...

  8. 30 CFR 70.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Approved sampling devices; equivalent... § 70.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in milligrams collected on the filter of an...

  9. 30 CFR 90.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved sampling devices; equivalent... DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  10. 30 CFR 90.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Approved sampling devices; equivalent... DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  11. 30 CFR 71.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved sampling devices; equivalent... OF UNDERGROUND COAL MINES Sampling Procedures § 71.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  12. 30 CFR 71.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Approved sampling devices; equivalent... OF UNDERGROUND COAL MINES Sampling Procedures § 71.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  13. 30 CFR 70.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved sampling devices; equivalent... § 70.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in milligrams collected on the filter of an...

  14. 30 CFR 71.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Approved sampling devices; equivalent... OF UNDERGROUND COAL MINES Sampling Procedures § 71.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust...

  15. 40 CFR 133.105 - Treatment equivalent to secondary treatment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 23 2012-07-01 2012-07-01 false Treatment equivalent to secondary treatment. 133.105 Section 133.105 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS SECONDARY TREATMENT REGULATION § 133.105 Treatment equivalent to secondary...

  16. 30 CFR 70.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... concentrations. 70.206 Section 70.206 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... § 70.206 Approved sampling devices; equivalent concentrations. The concentration of respirable dust... concentration to an equivalent concentration as measured with an MRE instrument. To convert a concentration...

  17. 40 CFR 61.66 - Equivalent equipment and procedures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... satisfaction to be equivalent in terms of reducing vinyl chloride emissions to the atmosphere to those... (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Vinyl Chloride § 61.66 Equivalent equipment and procedures. Upon written application from an owner or...

  18. Stimulus Equivalence, Generalization, and Contextual Stimulus Control in Verbal Classes

    ERIC Educational Resources Information Center

    Sigurdardottir, Zuilma Gabriela; Mackay, Harry A.; Green, Gina

    2012-01-01

    Stimulus generalization and contextual control affect the development of equivalence classes. Experiment 1 demonstrated primary stimulus generalization from the members of trained equivalence classes. Adults were taught to match six spoken Icelandic nouns and corresponding printed words and pictures to one another in computerized three-choice…

  19. 49 CFR 37.105 - Equivalent service standard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Equivalent service standard. 37.105 Section 37.105 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Acquisition of Accessible Vehicles by Private Entities § 37.105 Equivalent service...

  20. 40 CFR 133.105 - Treatment equivalent to secondary treatment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Treatment equivalent to secondary treatment. 133.105 Section 133.105 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS SECONDARY TREATMENT REGULATION § 133.105 Treatment equivalent to secondary...

  1. Mechanical Equivalent of Heat--Software for a Thermistor

    ERIC Educational Resources Information Center

    Boleman, Michael

    2008-01-01

    The Mechanical Equivalent of Heat Apparatus from PASCO scientific provides the means for doing a simple experiment to determine the mechanical equivalent of heat, "J." A necessary step of this experiment is to determine the temperature of an aluminum cylinder. By measuring the resistance of a thermistor embedded in the cylinder, one is able to…

  2. Assessment Battery for Communication: Development of Two Equivalent Forms

    ERIC Educational Resources Information Center

    Bosco, Francesca M.; Angeleri, Romina; Zuffranieri, Marco; Bara, Bruno G.; Sacco, Katiuscia

    2012-01-01

    The aim of this paper was to develop and test two equivalent forms of the Assessment Battery for Communication (ABaCo), a tool for evaluating pragmatic abilities in patients with neuropsychological and psychiatric disorders. The equivalent forms were created using the data from a sample of 390 children, then tested in a sample of 30 patients with…

  3. Equivalence Class Formation: A Method for Teaching Statistical Interactions

    ERIC Educational Resources Information Center

    Fields, Lanny; Travis, Robert; Roy, Deborah; Yadlovker, Eytan; de Aguiar-Rocha, Liliane; Sturmey, Peter

    2009-01-01

    Many students struggle with statistical concepts such as interaction. In an experimental group, participants took a paper-and-pencil test and then were given training to establish equivalent classes containing four different statistical interactions. All participants formed the equivalence classes and showed maintenance when probes contained novel…

  4. 33 CFR 140.15 - Equivalents and approved equipment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Equivalents and approved equipment. 140.15 Section 140.15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES GENERAL General § 140.15 Equivalents and...

  5. 49 CFR 37.105 - Equivalent service standard.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Equivalent service standard. 37.105 Section 37.105 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Acquisition of Accessible Vehicles by Private Entities § 37.105 Equivalent service...

  6. 43 CFR 426.11 - Class 1 equivalency.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Equivalency determinations can be made only on a district-wide basis. (c) Definition of Class 1 land. Class 1... measured in terms of net income per acre (reflecting both productivity and costs of production). The... farm income will be the measure of productivity to establish equivalency factors reflecting the...

  7. Assessing Measurement Equivalence in Ordered-Categorical Data

    ERIC Educational Resources Information Center

    Elosua, Paula

    2011-01-01

    Assessing measurement equivalence in the framework of the common factor linear models (CFL) is known as factorial invariance. This methodology is used to evaluate the equivalence among the parameters of a measurement model among different groups. However, when dichotomous, Likert, or ordered responses are used, one of the assumptions of the CFL is…

  8. Neutron detector simultaneously measures fluence and dose equivalent

    NASA Technical Reports Server (NTRS)

    Dvorak, R. F.; Dyer, N. C.

    1967-01-01

    Neutron detector acts as both an area monitoring instrument and a criticality dosimeter by simultaneously measuring dose equivalent and fluence. The fluence is determined by activation of six foils one inch below the surface of the moderator. Dose equivalent is determined from activation of three interlocked foils at the center of the moderator.

  9. Nodal Structure and the Partitioning of Equivalence Classes

    ERIC Educational Resources Information Center

    Fields, Lanny; Watanabe-Rose, Mari

    2008-01-01

    By definition, all of the stimuli in an equivalence class have to be functionally interchangeable with each other. The present experiment, however, demonstrated that this was not the case when using post-class-formation dual-option response transfer tests. With college students, two 4-node 6-member equivalence classes with nodal structures of…

  10. Teaching Statistical Variability with Equivalence-Based Instruction

    ERIC Educational Resources Information Center

    Albright, Leif; Reeve, Kenneth F.; Reeve, Sharon A.; Kisamore, April N.

    2015-01-01

    In the present study, equivalence-based instruction was used to teach 2 4-member classes representing high and low statistical variability to 10 college students. Computerized equivalence-based instruction with multiple-exemplar training was used to teach the classes. A pretest-training-posttest design evaluated performances on both computer-based…

  11. Quantifying the Combined Effect of Radiation Therapy and Hyperthermia in Terms of Equivalent Dose Distributions

    SciTech Connect

    Kok, H. Petra; Crezee, Johannes; Franken, Nicolaas A.P.; Barendsen, Gerrit W.

    2014-03-01

    Purpose: To develop a method to quantify the therapeutic effect of radiosensitization by hyperthermia; to this end, a numerical method was proposed to convert radiation therapy dose distributions with hyperthermia to equivalent dose distributions without hyperthermia. Methods and Materials: Clinical intensity modulated radiation therapy plans were created for 15 prostate cancer cases. To simulate a clinically relevant heterogeneous temperature distribution, hyperthermia treatment planning was performed for heating with the AMC-8 system. The temperature-dependent parameters α (Gy{sup −1}) and β (Gy{sup −2}) of the linear–quadratic model for prostate cancer were estimated from the literature. No thermal enhancement was assumed for normal tissue. The intensity modulated radiation therapy plans and temperature distributions were exported to our in-house-developed radiation therapy treatment planning system, APlan, and equivalent dose distributions without hyperthermia were calculated voxel by voxel using the linear–quadratic model. Results: The planned average tumor temperatures T90, T50, and T10 in the planning target volume were 40.5°C, 41.6°C, and 42.4°C, respectively. The planned minimum, mean, and maximum radiation therapy doses were 62.9 Gy, 76.0 Gy, and 81.0 Gy, respectively. Adding hyperthermia yielded an equivalent dose distribution with an extended 95% isodose level. The equivalent minimum, mean, and maximum doses reflecting the radiosensitization by hyperthermia were 70.3 Gy, 86.3 Gy, and 93.6 Gy, respectively, for a linear increase of α with temperature. This can be considered similar to a dose escalation with a substantial increase in tumor control probability for high-risk prostate carcinoma. Conclusion: A model to quantify the effect of combined radiation therapy and hyperthermia in terms of equivalent dose distributions was presented. This model is particularly instructive to estimate the potential effects of interaction from different

  12. Novel three-dimensional autologous tissue-engineered vaginal tissues using the self-assembly technique.

    PubMed

    Orabi, Hazem; Saba, Ingrid; Rousseau, Alexandre; Bolduc, Stéphane

    2017-02-01

    Many diseases necessitate the substitution of vaginal tissues. Current replacement therapies are associated with many complications. In this study, we aimed to create bioengineered neovaginas with the self-assembly technique using autologous vaginal epithelial (VE) and vaginal stromal (VS) cells without the use of exogenous materials and to document the survival and incorporation of these grafts into the tissues of nude female mice. Epithelial and stromal cells were isolated from vaginal biopsies. Stromal cells were driven to form collagen sheets, 3 of which were superimposed to form vaginal stromas. VE cells were seeded on top of these stromas and allowed to mature in an air-liquid interface. The vaginal equivalents were implanted subcutaneously in female nude mice, which were sacrificed after 1 and 2 weeks after surgery. The in vitro and animal-retrieved equivalents were assessed using histologic, functional, and mechanical evaluations. Vaginal equivalents could be handled easily. VE cells formed a well-differentiated epithelial layer with a continuous basement membrane. The equivalent matrix was composed of collagen I and III and elastin. The epithelium, basement membrane, and stroma were comparable to those of native vaginal tissues. The implanted equivalents formed mature vaginal epithelium and matrix that were integrated into the mice tissues. Using the self-assembly technique, in vitro vaginal tissues were created with many functional and biological similarities to native vagina without any foreign material. They formed functional vaginal tissues after in vivo animal implantation. It is appropriate for vaginal substitution and disease modeling for infectious studies, vaginal applicants, and drug testing.

  13. Tissue engineering in urothelium regeneration.

    PubMed

    Vaegler, Martin; Maurer, Sabine; Toomey, Patricia; Amend, Bastian; Sievert, Karl-Dietrich

    2015-03-01

    The development of therapeutic treatments to regenerate urothelium, manufacture tissue equivalents or neourethras for in-vivo application is a significant challenge in the field of tissue engineering. Many studies have focused on urethral defects that, in most cases, inadequately address current therapies. This article reviews the primary tissue engineering strategies aimed at the clinical requirements for urothelium regeneration while concentrating on promising investigations in the use of grafts, cellular preparations, as well as seeded or unseeded natural and synthetic materials. Despite significant progress being made in the development of scaffolds and matrices, buccal mucosa transplants have not been replaced. Recently, graft tissues appear to have an advantage over the use of matrices. These therapies depend on cell isolation and propagation in vitro that require, not only substantial laboratory resources, but also subsequent surgical implant procedures. The choice of the correct cell source is crucial when determining an in-vivo application because of the risks of tissue changes and abnormalities that may result in donor site morbidity. Addressing an appropriately-designed animal model and relevant regulatory issues is of fundamental importance for the principal investigators when a therapy using cellular components has been developed for clinical use.

  14. Tissue irradiator

    DOEpatents

    Hungate, F.P.; Riemath, W.F.; Bunnell, L.R.

    1975-12-16

    A tissue irradiator is provided for the in-vivo irradiation of body tissue. The irradiator comprises a radiation source material contained and completely encapsulated within vitreous carbon. An embodiment for use as an in- vivo blood irradiator comprises a cylindrical body having an axial bore therethrough. A radioisotope is contained within a first portion of vitreous carbon cylindrically surrounding the axial bore, and a containment portion of vitreous carbon surrounds the radioisotope containing portion, the two portions of vitreous carbon being integrally formed as a single unit. Connecting means are provided at each end of the cylindrical body to permit connections to blood- carrying vessels and to provide for passage of blood through the bore. In a preferred embodiment, the radioisotope is thulium-170 which is present in the irradiator in the form of thulium oxide. A method of producing the preferred blood irradiator is also provided, whereby nonradioactive thulium-169 is dispersed within a polyfurfuryl alcohol resin which is carbonized and fired to form the integral vitreous carbon body and the device is activated by neutron bombardment of the thulium-169 to produce the beta-emitting thulium-170.

  15. Investigating the protective properties of milk phospholipids against ultraviolet light exposure in a skin equivalent model

    NASA Astrophysics Data System (ADS)

    Russell, Ashley; Laubscher, Andrea; Jimenez-Flores, Rafael; Laiho, Lily H.

    2010-02-01

    Current research on bioactive molecules in milk has documented health advantages of bovine milk and its components. Milk Phospholipids, selected for this study, represent molecules with great potential benefit in human health and nutrition. In this study we used confocal reflectance and multiphoton microscopy to monitor changes in skin morphology upon skin exposure to ultraviolet light and evaluate the potential of milk phospholipids in preventing photodamage to skin equivalent models. The results suggest that milk phospholipids act upon skin cells in a protective manner against the effect of ultraviolet (UV) radiation. Similar results were obtained from MTT tissue viability assay and histology.

  16. Equivalence of four Monte Carlo methods for photon migration in turbid media.

    PubMed

    Sassaroli, Angelo; Martelli, Fabrizio

    2012-10-01

    In the field of photon migration in turbid media, different Monte Carlo methods are usually employed to solve the radiative transfer equation. We consider four different Monte Carlo methods, widely used in the field of tissue optics, that are based on four different ways to build photons' trajectories. We provide both theoretical arguments and numerical results showing the statistical equivalence of the four methods. In the numerical results we compare the temporal point spread functions calculated by the four methods for a wide range of the optical properties in the slab and semi-infinite medium geometry. The convergence of the methods is also briefly discussed.

  17. Singularity theory of fitness functions under dimorphism equivalence.

    PubMed

    Wang, Xiaohui; Golubitsky, Martin

    2016-09-01

    We apply singularity theory to classify monomorphic singular points as they occur in adaptive dynamics. Our approach is based on a new equivalence relation called dimorphism equivalence, which is the largest equivalence relation on strategy functions that preserves ESS singularities, CvSS singularities, and dimorphisms. Specifically, we classify singularities up to topological codimension two and compute their normal forms and universal unfoldings. These calculations lead to the classification of local mutual invasibility plots that can be seen generically in systems with two parameters.

  18. Weight propagation and equivalent horsepower for alternate-engined cars

    NASA Technical Reports Server (NTRS)

    Klose, G. J.; Kurtz, D. W.

    1978-01-01

    In order to evaluate properly the consequences of replacing conventional Otto-cycle engines with alternate power systems, comparisons must be carried out at the vehicle level with functionally equivalent cars. This paper presents the development and application of a procedure for establishing equivalent vehicles. A systematic weight propagation methodology, based on detailed weight breakdowns and influence factors, yields the vehicle weight impacts due to changes in engine weight and power. Performance-matching criteria, utilizing a vehicle simulation program, are then employed to establish Otto-engine-equivalent vehicles, whose characteristics can form the basis for alternative engine evaluations.

  19. Multivariate equivalence tests for use in pharmaceutical development.

    PubMed

    Hoffelder, Thomas; Gössl, Rüdiger; Wellek, Stefan

    2015-01-01

    Statistical equivalence analyses are well-established parts of many studies in the biomedical sciences. Also in pharmaceutical development and manufacturing equivalence testing methods are required in order to statistically establish similarities between machines, process components, or complete processes. This article presents a choice of multivariate equivalence testing procedures for normally distributed data as generalizations of existing univariate methods. In all derived methods, variability is interpreted as nuisance parameter. The use of the proposed methods in pharmaceutical development is demonstrated with a comparative analysis of dissolution profiles.

  20. Thévenin equivalence in disorderless quantum networks

    SciTech Connect

    Cain, C. A.; Wu, C. H.

    2015-01-14

    We outline the procedure of extending the Thévenin equivalence principle for classical electric circuits to reducing Aharonov-Bohm-based quantum networks into equivalent models. With examples, we show from first principles how the requirements are related to the electron band structure's Fermi level and the lattice spacing of the network. Quantum networks of varying degrees of coupling strength from four basic classifications of single and double entangled loops sharing symmetry and highly correlated band structures are used to demonstrate the concept. We show the limitations of how the principle may be applied. Several classes of examples are given and their equivalent forms are shown.

  1. An improved equivalent circuit model of radial mode piezoelectric transformer.

    PubMed

    Huang, Yihua; Huang, Wei

    2011-05-01

    In this paper, both the equivalent circuit models of the radial mode and the coupled thickness vibration mode of the radial mode piezoelectric transformer are deduced, and then with the Y-parameter matrix method and the dual-port network theory, an improved equivalent circuit model for the multilayer radial mode piezoelectric transformer is established. A radial mode transformer sample is tested to verify the equivalent circuit model. The experimental results show that the model proposed in this paper is more precise than the typical model.

  2. Photochemical tissue bonding

    DOEpatents

    Redmond, Robert W [Brookline, MA; Kochevar, Irene E [Charlestown, MA

    2012-01-10

    Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

  3. Dosimetric verification of the anisotropic analytical algorithm in lung equivalent heterogeneities with and without bone equivalent heterogeneities

    SciTech Connect

    Ono, Kaoru; Endo, Satoru; Tanaka, Kenichi; Hoshi, Masaharu; Hirokawa, Yutaka

    2010-08-15

    Purpose: In this study, the authors evaluated the accuracy of dose calculations performed by the convolution/superposition based anisotropic analytical algorithm (AAA) in lung equivalent heterogeneities with and without bone equivalent heterogeneities. Methods: Calculations of PDDs using the AAA and Monte Carlo simulations (MCNP4C) were compared to ionization chamber measurements with a heterogeneous phantom consisting of lung equivalent and bone equivalent materials. Both 6 and 10 MV photon beams of 4x4 and 10x10 cm{sup 2} field sizes were used for the simulations. Furthermore, changes of energy spectrum with depth for the heterogeneous phantom using MCNP were calculated. Results: The ionization chamber measurements and MCNP calculations in a lung equivalent phantom were in good agreement, having an average deviation of only 0.64{+-}0.45%. For both 6 and 10 MV beams, the average deviation was less than 2% for the 4x4 and 10x10 cm{sup 2} fields in the water-lung equivalent phantom and the 4x4 cm{sup 2} field in the water-lung-bone equivalent phantom. Maximum deviations for the 10x10 cm{sup 2} field in the lung equivalent phantom before and after the bone slab were 5.0% and 4.1%, respectively. The Monte Carlo simulation demonstrated an increase of the low-energy photon component in these regions, more for the 10x10 cm{sup 2} field compared to the 4x4 cm{sup 2} field. Conclusions: The low-energy photon by Monte Carlo simulation component increases sharply in larger fields when there is a significant presence of bone equivalent heterogeneities. This leads to great changes in the build-up and build-down at the interfaces of different density materials. The AAA calculation modeling of the effect is not deemed to be sufficiently accurate.

  4. 33 CFR 101.130 - Equivalent security measures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... equivalent security measure that has been approved by the Commandant (CG-54) as meeting or exceeding the effectiveness of the required measure. The Commandant (CG-54) may require that the owner or operator...

  5. 33 CFR 101.130 - Equivalent security measures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... equivalent security measure that has been approved by the Commandant (CG-54) as meeting or exceeding the effectiveness of the required measure. The Commandant (CG-54) may require that the owner or operator...

  6. On the possibility of radiation equivalent waste disposal

    SciTech Connect

    Adamov, E.O.; Orlov, V.V.; Tocheny, L.V.

    1993-12-31

    The method of radiation equivalent waste disposal due to their long-term controlled cooling, actinides recycle, and burning up and a variety of other measures can be considered for large scale future nuclear power.

  7. Lipschitz equivalence of self-similar sets with touching structures

    NASA Astrophysics Data System (ADS)

    Ruan, Huo-Jun; Wang, Yang; Xi, Li-Feng

    2014-06-01

    Lipschitz equivalence of self-similar sets is an important area in the study of fractal geometry. It is known that two dust-like self-similar sets with the same contraction ratios are always Lipschitz equivalent. However, when self-similar sets have touching structures the problem of Lipschitz equivalence becomes much more challenging and intriguing at the same time. So far, all the known results only cover self-similar sets in {R} with no more than three branches. In this study we establish results for the Lipschitz equivalence of self-similar sets with touching structures in {R} with arbitrarily many branches. Key to our study is the introduction of a geometric condition for self-similar sets called substitutable.

  8. Condition for equivalence of q-deformed and anharmonic oscillators

    NASA Technical Reports Server (NTRS)

    Artoni, M.; Zang, Jun; Birman, Joseph L.

    1993-01-01

    The equivalence between the q-deformed harmonic oscillator and a specific anharmonic oscillator model, by which some new insight into the problem of the physical meaning of the parameter q can be attained, are discussed.

  9. Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds

    NASA Astrophysics Data System (ADS)

    Wang, Haining; Dai, Xi-Jie; Li, Chao-Jun

    2016-12-01

    Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.

  10. Lack of pharmacokinetic interaction as an equivalence problem.

    PubMed

    Steinijans, V W; Hartmann, M; Huber, R; Radtke, H W

    1991-08-01

    The demonstration that concomitant administration of drug B does not affect the pharmacokinetics of drug A can be adequately handled as an equivalence problem. Administration of drug A alone serves as reference and simultaneous administration of drugs A and B as test situation. The range of clinically acceptable variation in the pharmacokinetic characteristics of drug A defines the equivalence range. This will usually correspond to the bioequivalence range accepted for the comparison of different formulations of drug A. Equivalence, i.e. lack of pharmacokinetic interaction, is concluded if the 90%-confidence interval for the ratio (difference) of the expected medians for test and reference is entirely within the equivalence range. This decision procedure ensures that the consumer risk of incorrectly concluding "lack of interaction" is limited to 5%. Moreover, the producer risk of incorrectly concluding "interaction" can be controlled by appropriate sample sizes.

  11. Improved Equivalent Linearization Implementations Using Nonlinear Stiffness Evaluation

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Muravyov, Alexander A.

    2001-01-01

    This report documents two new implementations of equivalent linearization for solving geometrically nonlinear random vibration problems of complicated structures. The implementations are given the acronym ELSTEP, for "Equivalent Linearization using a STiffness Evaluation Procedure." Both implementations of ELSTEP are fundamentally the same in that they use a novel nonlinear stiffness evaluation procedure to numerically compute otherwise inaccessible nonlinear stiffness terms from commercial finite element programs. The commercial finite element program MSC/NASTRAN (NASTRAN) was chosen as the core of ELSTEP. The FORTRAN implementation calculates the nonlinear stiffness terms and performs the equivalent linearization analysis outside of NASTRAN. The Direct Matrix Abstraction Program (DMAP) implementation performs these operations within NASTRAN. Both provide nearly identical results. Within each implementation, two error minimization approaches for the equivalent linearization procedure are available - force and strain energy error minimization. Sample results for a simply supported rectangular plate are included to illustrate the analysis procedure.

  12. Establishment of an equivalence acceptance criterion for accelerated stability studies.

    PubMed

    Burdick, Richard K; Sidor, Leslie

    2013-01-01

    In this article, the use of statistical equivalence testing for providing evidence of process comparability in an accelerated stability study is advocated over the use of a test of differences. The objective of such a study is to demonstrate comparability by showing that the stability profiles under nonrecommended storage conditions of two processes are equivalent. Because it is difficult at accelerated conditions to find a direct link to product specifications, and hence product safety and efficacy, an equivalence acceptance criterion is proposed that is based on the statistical concept of effect size. As with all statistical tests of equivalence, it is important to collect input from appropriate subject-matter experts when defining the acceptance criterion.

  13. Effect of primary-zone equivalence ratio on pollutant formation

    NASA Technical Reports Server (NTRS)

    Claus, R. W.

    1979-01-01

    Test were conducted to determine the effect of primary-zone equivalence ratio on the formation of smoke and other gaseous pollutants in an experimental can combustor. Several fuel injection techniques were examined at primary-zone equivalence ratios from 0.8 to 2.0. The main emphasis was on reducing fuel-rich-combustion smoke levels. Two of the four fuel injection configurations studied produced smoke levels below a smoke number of 20 at a primary-zone equivalence ratio of about 1.7. As the fuel mixing and atomization were recorded at primary-zone equivalence ratios as high as 2.0. The gaseous emissions of unburned hydrocarbons, carbon monoxide, and oxides of nitrogen were quite sensitive to the fuel injection configuration as well as to the primary-zone equilvalence ratio.

  14. Calorimetric measurement and modelling of the equivalent series of capacitors

    NASA Astrophysics Data System (ADS)

    Seguin, B.; Gosse, J. P.; Ferrieux, J. P.

    1999-12-01

    The equivalent series resistance of polypropylene capacitors has been determined under rated voltage, in the range 1 kHz 1 MHz, between 220 K and 370 K by a calorimetric technique. The original feature of this determination of capacitor losses lies in the use of the isothermal calorimetry and in the measurement of an electrical power and not of a temperature increase. The frequency dependence of the equivalent series resistance, at various temperatures, enables to separate the losses in the conducting material from those in the dielectric and to get their respective variations as a function of frequency and temperature. These variations of the equivalent series resistance with frequency at a given temperature have been reproduced by using an equivalent circuit composed of resistors, inductors and capacitors. This model has been verified for non-sinusoidal waveforms such as those met with in a filtering circuit and is used to evaluate by simulation the losses of the capacitor.

  15. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation

    SciTech Connect

    Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E. )

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  16. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation.

    PubMed

    Sondhaus, C A; Bond, V P; Feinendegen, L E

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  17. Can the Equivalent Sphere Model Approximate Organ Doses in Space?

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei

    2007-01-01

    For space radiation protection it is often useful to calculate dose or dose,equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to. simulate the BFO dose. However, many previous studies have concluded that a 5cm sphere gives very different dose values from the exact BFO values. One study [1] . concludes that a 9 cm sphere is a reasonable approximation for BFO'doses in solar particle event environments. In this study we use a deterministic radiation transport [2] to investigate the reason behind these observations and to extend earlier studies. We take different space radiation environments, including seven galactic cosmic ray environments and six large solar particle events, and calculate the dose and dose equivalent in the skin, eyes and BFO using their thickness distribution functions from the CAM (Computerized Anatomical Man) model [3] The organ doses have been evaluated with a water or aluminum shielding of an areal density from 0 to 20 g/sq cm. We then compare with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we address why the equivalent sphere model is not a good approximation in some cases. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin. For galactic cosmic rays environments, the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of the eye or the skin, but is unacceptable for the dose of the eye or the skin. The ranges of the radius parameters are also being investigated, and the BFO radius parameters are found to be significantly, larger than 5 cm in all cases, consistent with the conclusion of

  18. Cohomology of groups and splendid equivalences of derived categories

    NASA Astrophysics Data System (ADS)

    Zimmermann, Alexander

    2001-11-01

    In an earlier paper we studied the impact of equivalences between derived categories of group rings on their cohomology rings. Especially the group of auto-equivalences TrPic(RG) of the derived category of a group ring RG as introduced by Raphaël Rouquier and the author defines an action on the cohomology ring of this group. We study this action with respect to the restriction map, transfer, conjugation and the local structure of the group G.

  19. Equivalent equations of motion for gravity and entropy

    NASA Astrophysics Data System (ADS)

    Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Mosk, Benjamin; Sully, James

    2017-02-01

    We demonstrate an equivalence between the wave equation obeyed by the entanglement entropy of CFT subregions and the linearized bulk Einstein equation in Anti-de Sitter space. In doing so, we make use of the formalism of kinematic space [1] and fields on this space, introduced in [2]. We show that the gravitational dynamics are equivalent to a gauge invariant wave-equation on kinematic space and that this equation arises in natural correspondence to the conformal Casimir equation in the CFT.

  20. Neutral theory and the evolution of ecological equivalence.

    PubMed

    Hubbell, Stephen P

    2006-06-01

    Since the publication of the unified neutral theory in 2001, there has been much discussion of the theory, pro and con. The hypothesis of ecological equivalence is the fundamental yet controversial idea behind neutral theory. Assuming trophically similar species are demographically alike (symmetric) on a per capita basis is only an approximation, but it is equivalent to asking: How many of the patterns of ecological communities are the result of species similarities, rather than of species differences? The strategy behind neutral theory is to see how far one can get with the simplification of assuming ecological equivalence before introducing more complexity. In another paper, I review the empirical evidence that led me to hypothesize ecological equivalence among many of the tree species in the species-rich tropical forest on Barro Colorado Island (BCI). In this paper, I develop a simple model for the evolution of ecological equivalence or niche convergence, using as an example evolution of the suite of life history traits characteristic of shade tolerant tropical tree species. Although the model is simple, the conclusions from it seem likely to be robust. I conclude that ecological equivalence for resource use are likely to evolve easily and often, especially in species-rich communities that are dispersal and recruitment limited. In the case of the BCI forest, tree species are strongly dispersal- and recruitment-limited, not only because of restricted seed dispersal, but also because of low recruitment success due to heavy losses of the seedling stages to predators and pathogens and other abiotic stresses such as drought. These factors and the high species richness of the community strongly reduce the potential for competitive exclusion of functionally equivalent or nearly equivalent species.

  1. The equivalence between dislocation pile-ups and cracks

    NASA Technical Reports Server (NTRS)

    Liu, H. W.; Gao, Q.

    1990-01-01

    Cracks and dislocation pile-ups are equivalent to each other. In this paper, the physical equivalence between cracks and pile-ups is delineated, and the relationshps between crack-extension force, force on the leading dislocation, stress-intensity factor, and dislocation density are reviewed and summarized. These relations make it possible to extend quantitatively the recent advances in the concepts and practices of fracture mechanics to the studies of microfractures and microplastic deformations.

  2. Equivalence Between Approximate Dynamic Inversion and Proportional-Integral Control

    DTIC Science & Technology

    2008-09-29

    systems that renders the closed-loop error dynamics independent of the reference model dynamics. The equivalent PI controller will be derived and both of...integral control, PI control . I. INTRODUCTION DYNAMIC inversion (DI) or feedback linearization isa popular control design method that is well suited for...Proportional-Integral (PI) model reference controller realiza- tion. The key characteristic of the equivalent PI controller is that it is largely independent

  3. Solar particle event organ doses and dose equivalents for interplanetary crews: variations due to body size

    NASA Technical Reports Server (NTRS)

    Zapp, E. N.; Townsend, L. W.; Cucinotta, F. A.

    2002-01-01

    Proper assessments of spacecraft shielding requirements and concomitant estimates of risk to critical body organs of spacecraft crews from energetic space radiation require accurate, quantitative methods of characterizing the compositional changes in these radiation fields as they pass through the spacecraft and overlying tissue. When estimating astronaut radiation organ doses and dose equivalents it is customary to use the Computerized Anatomical Man (CAM) model of human geometry to account for body self-shielding. Usually, the distribution for the 50th percentile man (175 cm height; 70 kg mass) is used. Most male members of the U.S. astronaut corps are taller and nearly all have heights that deviate from the 175 cm mean. In this work, estimates of critical organ doses and dose equivalents for interplanetary crews exposed to an event similar to the October 1989 solar particle event are presented for male body sizes that vary from the 5th to the 95th percentiles. Overall the results suggest that calculations of organ dose and dose equivalent may vary by as much as approximately 15% as body size is varied from the 5th to the 95th percentile in the population used to derive the CAM model data. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

  4. Melanin Transfer in Human 3D Skin Equivalents Generated Exclusively from Induced Pluripotent Stem Cells

    PubMed Central

    Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A.; Itoh, Munenari; Christiano, Angela M.

    2015-01-01

    The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes. PMID:26308443

  5. Evaluation of lead equivalence of patient and hardware materials in medical diagnostic x-ray shielding.

    PubMed

    Okunade, Akintunde Akangbe

    2005-02-01

    In the estimation of additional shielding requirements for primary beam apart from that provided by patient and hardware in the x-ray beam, there is the need to distinguish between attenuation and hardening properties of materials in comparison. In this work, numerical comparison of attenuation and hardening properties of phantom (Lucite, soft tissue, water) and hardware (aluminum and steel) materials with those of lead have been carried out. Results presented show that the shielding affordable by lead attenuation equivalent thicknesses (LAE) and lead hardening equivalent thicknesses (LHE) is not strictly equivalent to that affordable by thicknesses of substitutes (phantom materials, aluminum and steel) when there are differences in attenuation and hardening properties. Even though beams through LAE that are not "exact" have equal exposure values, the half value layers are higher than those through thicknesses of lead substitutes. Example calculations show that the use of lead thickness (LAE) that are not "exact" to account for the shielding afforded by the thickness of the patient (water phantom) produces lesser reduction of the primary radiation level in the area indicated for shielding. The "exact" LAE that will reduce the primary radiation level equally as the patient and radiographic table may be higher by close to 20% or more of that which is not "exact."

  6. [Generalization of money-handling though training in equivalence relationships].

    PubMed

    Vives-Montero, Carmen; Valero-Aguayo, Luis; Ascanio, Lourdes

    2011-02-01

    This research used a matching-to-sample procedure and equivalence learning process with language and verbal tasks. In the study, an application of the equivalence relationship of money was used with several kinds of euro coins presented. The sample consisted of 16 children (8 in the experimental group and 8 in the control group) aged 5 years. The prerequisite behaviors, the identification of coins and the practical use of different euro coins, were assessed in the pre and post phases for both groups. The children in the experimental group performed an equivalence task using the matching-to-sample procedure. This consisted of a stimulus sample and four matching stimuli, using a series of euro coins with equivalent value in each set. The children in the control group did not undergo this training process. The results showed a large variability in the children's data of the equivalence tests. The experimental group showed the greatest pre and post changes in the statistically significant data. They also showed a greater generalization in the identification of money and in the use of euro coins than the control group. The implications for educational training and the characteristics of the procedure used here for coin equivalence are discussed.

  7. The transfer of Cfunc contextual control through equivalence relations.

    PubMed

    Perez, William F; Fidalgo, Adriana P; Kovac, Roberta; Nico, Yara C

    2015-05-01

    Derived relational responding is affected by contextual stimuli (Cfunc) that select specific stimulus functions. The present study investigated the transfer of Cfunc contextual control through equivalence relations by evaluating both (a) the maintenance of Cfunc contextual control after the expansion of a relational network, and (b) the establishment of novel contextual stimuli by the transfer of Cfunc contextual control through equivalence relations. Initially, equivalence relations were established and contingencies were arranged so that colors functioned as Cfunc stimuli controlling participants' key-pressing responses in the presence of any stimulus from a three-member equivalence network. To investigate the first research question, the three-member equivalence relations were expanded to five members and the novel members were presented with the Cfunc stimuli in the key-pressing task. To address the second goal of this study, the colors (Cfunc) were established as equivalent to certain line patterns. The transfer of contextual cue function (Cfunc) was tested replacing the colored backgrounds with line patterns in the key-pressing task. Results suggest that the Cfunc contextual control was transferred to novel stimuli that were added to the relational network. In addition, the line patterns indirectly acquired the contextual cue function (Cfunc) initially established for the colored backgrounds. The conceptual and applied implications of Cfunc contextual control are discussed.

  8. Solving complex-valued linear systems via equivalent real formulations

    SciTech Connect

    DAY,DAVID M.; HEROUX,MICHAEL A.

    2000-05-22

    Most algorithms used in preconditioned iterative methods are generally applicable to complex valued linear systems, with real valued linear systems simply being a special case. However, most iterative solver packages available today focus exclusively on real valued systems, or deal with complex valued systems as an afterthought. One obvious approach to addressing this problem is to recast the complex problem into one of a several equivalent real forms and then use a real valued solver to solve the related system. However, well-known theoretical results showing unfavorable spectral properties for the equivalent real forms have diminished enthusiasm for this approach. At the same time, experience has shown that there are situations where using an equivalent real form can be very effective. In this paper, the authors explore this approach, giving both theoretical and experimental evidence that an equivalent real form can be useful for a number of practical situations. Furthermore, they show that by making good use of some of the advance features of modem solver packages, they can easily generate equivalent real form preconditioners that are computationally efficient and mathematically identical to their complex counterparts. Using their techniques, they are able to solve very ill-conditioned complex valued linear systems for a variety of large scale applications. However, more importantly, they shed more light on the effectiveness of equivalent real forms and more clearly delineate how and when they should be used.

  9. Diminished acquired equivalence yet good discrimination performance in older participants.

    PubMed

    Robinson, Jasper; Owens, Emma

    2013-01-01

    We asked younger and older human participants to perform computer-based configural discriminations that were designed to detect acquired equivalence. Both groups solved the discriminations but only the younger participants demonstrated acquired equivalence. The discriminations involved learning the preferences ["like" (+) or "dislike" (-)] for sports [e.g., tennis (t) and hockey (h)] of four fictitious people [e.g., Alice (A), Beth (B), Charlotte (C), and Dorothy (D)]. In one experiment, the discrimination had the form: At+, Bt-, Ct+, Dt-, Ah-, Bh+, Ch-, Dh+. Notice that, e.g., Alice and Charlotte are "equivalent" in liking tennis but disliking hockey. Acquired equivalence was assessed in ancillary components of the discrimination (e.g., by looking at the subsequent rate of "whole" versus "partial" reversal learning). Acquired equivalence is anticipated by a network whose hidden units are shared when inputs (e.g., A and C) signal the same outcome (e.g., +) when accompanied by the same input (t). One interpretation of these results is that there are age-related differences in the mechanisms of configural acquired equivalence.

  10. Tissue Photolithography

    NASA Technical Reports Server (NTRS)

    Wade, Lawrence A.; Kartalov, Emil; Shibata, Darryl; Taylor, Clive

    2011-01-01

    Tissue lithography will enable physicians and researchers to obtain macromolecules with high purity (greater than 90 percent) from desired cells in conventionally processed, clinical tissues by simply annotating the desired cells on a computer screen. After identifying the desired cells, a suitable lithography mask will be generated to protect the contents of the desired cells while allowing destruction of all undesired cells by irradiation with ultraviolet light. The DNA from the protected cells can be used in a number of downstream applications including DNA sequencing. The purity (i.e., macromolecules isolated form specific cell types) of such specimens will greatly enhance the value and information of downstream applications. In this method, the specific cells are isolated on a microscope slide using photolithography, which will be faster, more specific, and less expensive than current methods. It relies on the fact that many biological molecules such as DNA are photosensitive and can be destroyed by ultraviolet irradiation. Therefore, it is possible to protect the contents of desired cells, yet destroy undesired cells. This approach leverages the technologies of the microelectronics industry, which can make features smaller than 1 micrometer with photolithography. A variety of ways has been created to achieve identification of the desired cell, and also to designate the other cells for destruction. This can be accomplished through chrome masks, direct laser writing, and also active masking using dynamic arrays. Image recognition is envisioned as one method for identifying cell nuclei and cell membranes. The pathologist can identify the cells of interest using a microscopic computerized image of the slide, and appropriate custom software. In one of the approaches described in this work, the software converts the selection into a digital mask that can be fed into a direct laser writer, e.g. the Heidelberg DWL66. Such a machine uses a metalized glass plate (with

  11. The materials used in bone tissue engineering

    SciTech Connect

    Tereshchenko, V. P. Kirilova, I. A.; Sadovoy, M. A.; Larionov, P. M.

    2015-11-17

    Bone tissue engineering looking for an alternative solution to the problem of skeletal injuries. The method is based on the creation of tissue engineered bone tissue equivalent with stem cells, osteogenic factors, and scaffolds - the carriers of these cells. For production of tissue engineered bone equivalent is advisable to create scaffolds similar in composition to natural extracellular matrix of the bone. This will provide optimal conditions for the cells, and produce favorable physico-mechanical properties of the final construction. This review article gives an analysis of the most promising materials for the manufacture of cell scaffolds. Biodegradable synthetic polymers are the basis for the scaffold, but it alone cannot provide adequate physical and mechanical properties of the construction, and favorable conditions for the cells. Addition of natural polymers improves the strength characteristics and bioactivity of constructions. Of the inorganic compounds, to create cell scaffolds the most widely used calcium phosphates, which give the structure adequate stiffness and significantly increase its osteoinductive capacity. Signaling molecules do not affect the physico-mechanical properties of the scaffold, but beneficial effect is on the processes of adhesion, proliferation and differentiation of cells. Biodegradation of the materials will help to fulfill the main task of bone tissue engineering - the ability to replace synthetic construct by natural tissues that will restore the original anatomical integrity of the bone.

  12. The materials used in bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Tereshchenko, V. P.; Kirilova, I. A.; Sadovoy, M. A.; Larionov, P. M.

    2015-11-01

    Bone tissue engineering looking for an alternative solution to the problem of skeletal injuries. The method is based on the creation of tissue engineered bone tissue equivalent with stem cells, osteogenic factors, and scaffolds - the carriers of these cells. For production of tissue engineered bone equivalent is advisable to create scaffolds similar in composition to natural extracellular matrix of the bone. This will provide optimal conditions for the cells, and produce favorable physico-mechanical properties of the final construction. This review article gives an analysis of the most promising materials for the manufacture of cell scaffolds. Biodegradable synthetic polymers are the basis for the scaffold, but it alone cannot provide adequate physical and mechanical properties of the construction, and favorable conditions for the cells. Addition of natural polymers improves the strength characteristics and bioactivity of constructions. Of the inorganic compounds, to create cell scaffolds the most widely used calcium phosphates, which give the structure adequate stiffness and significantly increase its osteoinductive capacity. Signaling molecules do not affect the physico-mechanical properties of the scaffold, but beneficial effect is on the processes of adhesion, proliferation and differentiation of cells. Biodegradation of the materials will help to fulfill the main task of bone tissue engineering - the ability to replace synthetic construct by natural tissues that will restore the original anatomical integrity of the bone.

  13. In vivo tissue engineering of musculoskeletal tissues.

    PubMed

    McCullen, Seth D; Chow, Andre G Y; Stevens, Molly M

    2011-10-01

    Tissue engineering of musculoskeletal tissues often involves the in vitro manipulation and culture of progenitor cells, growth factors and biomaterial scaffolds. Though in vitro tissue engineering has greatly increased our understanding of cellular behavior and cell-material interactions, this methodology is often unable to recreate tissue with the hierarchical organization and vascularization found within native tissues. Accordingly, investigators have focused on alternative in vivo tissue engineering strategies, whereby the traditional triad (cells, growth factors, scaffolds) or a combination thereof are directly implanted at the damaged tissue site or within ectopic sites capable of supporting neo-tissue formation. In vivo tissue engineering may offer a preferential route for regeneration of musculoskeletal and other tissues with distinct advantages over in vitro methods based on the specific location of endogenous cultivation, recruitment of autologous cells, and patient-specific regenerated tissues.

  14. Ex Vivo Produced Oral Mucosa Equivalent by Using the Direct Explant Cell Culture Technique

    PubMed Central

    Bayar, Gürkan Raşit; Aydıntuğ, Yavuz Sinan; Günhan, Ömer; Öztürk, Kamile; Gülses, Aydın

    2012-01-01

    Objective: The aim of this study is the histological and immunohistochemical evaluation of ex vivo produced oral mucosal equivalents using keratinocytes cultured by direct explant technique. Material and Methods: Oral mucosa tissue samples were obtained from the keratinized gingival tissues of 14 healthy human subjects. Human oral mucosa keratinocytes from an oral mucosa biopsy specimen were dissociated by the explant technique. Once a sufficient population of keratinocytes was reached, they were seeded onto the type IV collagen coated “AlloDerm” and taken for histological and immunohistochemical examinations at 11 days postseeding of the keratinocytes on the cadaveric human dermal matrix. Results: Histopathologically and immunohistochemically, 12 out of 14 successful ex vivo produced oral mucosa equivalents (EVPOME) that consisted of a stratified epidermis on a dermal matrix have been developed with keratinocytes cultured by the explant technique. Conclusion: The technical handling involved in the direct explant method at the beginning of the process has fewer steps than the enzymatic method and use of the direct explant technique protocol for culturing of human oral mucosa keratinocyte may be more adequate for EVPOME production. PMID:25207018

  15. Tritons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ((3)H(+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV.

  16. Helions at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions ((3)He(2+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV.

  17. Integration of Mature Adipocytes to Build-Up a Functional Three-Layered Full-Skin Equivalent

    PubMed Central

    Huber, Birgit; Link, Antonia; Linke, Kirstin; Gehrke, Sandra A.; Winnefeld, Marc

    2016-01-01

    Large, deep full-thickness skin wounds from high-graded burns or trauma are not able to reepithelialize sufficiently, resulting in scar formation, mobility limitations, and cosmetic deformities. In this study, in vitro-constructed tissue replacements are needed. Furthermore, such full-skin equivalents would be helpful as in vivo-like test systems for toxicity, cosmetic, and pharmaceutical testing. Up to date, no skin equivalent is available containing the underlying subcutaneous fatty tissue. In this study, we composed a full-skin equivalent and evaluated three different media for the coculture of mature adipocytes, fibroblasts, and keratinocytes. Therefore, adipocyte medium was supplemented with ascorbyl-2-phosphate and calcium chloride, which are important for successful epidermal stratification (Air medium). This medium was further supplemented with two commercially available factor combinations often used for the in vitro culture of keratinocytes (Air-HKGS and Air-KGM medium). We showed that in all media, keratinocytes differentiated successfully to build a stratified epidermal layer and expressed cytokeratin 10 and 14. Perilipin A-positive adipocytes could be found in all tissue models for up to 14 days, whereas adipocytes in the Air-HKGS and Air-KGM medium seemed to be smaller. Adipocytes in all tissue models were able to release adipocyte-specific factors, whereas the supplementation of keratinocyte-specific factors had a slightly negative effect on adipocyte functionality. The permeability of the epidermis of all models was comparable since they were able to withstand a deep penetration of cytotoxic Triton X in the same manner. Taken together, we were able to compose functional three-layered full-skin equivalents by using the Air medium. PMID:27334067

  18. Evaluating ecological equivalence of created marshes: comparing structural indicators with stable isotope indicators of blue crab trophic support

    USGS Publications Warehouse

    Llewellyn, Chris; LaPeyre, Megan K.

    2010-01-01

    This study sought to examine ecological equivalence of created marshes of different ages using traditional structural measures of equivalence, and tested a relatively novel approach using stable isotopes as a measure of functional equivalence. We compared soil properties, vegetation, nekton communities, and δ13C and δ15N isotope values of blue crab muscle and hepatopancreas tissue and primary producers at created (5-24 years old) and paired reference marshes in SW Louisiana. Paired contrasts indicated that created and reference marshes supported equivalent plant and nekton communities, but differed in soil characteristics. Stable isotope indicators examining blue crab food web support found that the older marshes (8 years+) were characterized by comparable trophic diversity and breadth compared to their reference marshes. Interpretation of results for the youngest site was confounded by the fact that the paired reference, which represented the desired end goal of restoration, contained a greater diversity of basal resources. Stable isotope techniques may give coastal managers an additional tool to assess functional equivalency of created marshes, as measured by trophic support, but may be limited to comparisons of marshes with similar vegetative communities and basal resources, or require the development of robust standardization techniques.

  19. Validity of the Aluminum Equivalent Approximation in Space Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Badavi, Francis F.; Adams, Daniel O.; Wilson, John W.

    2009-01-01

    The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space operations of the 21 st century which will include long stays onboard the International Space Station (ISS) and perhaps the moon. This is especially true for a risk based protection system, as appears imminent for deep space exploration where the long-term effects of Galactic Cosmic Ray (GCR) exposure is of primary concern. The present analysis demonstrates that sufficiently large errors in the interior particle environment of a spacecraft result from the use of the aluminum equivalent approximation, and such approximations should be avoided in future astronaut risk estimates. In this study, the aluminum equivalent approximation is evaluated as a means for estimating the particle environment within a spacecraft structure induced by the GCR radiation field. For comparison, the two extremes of the GCR environment, the 1977 solar minimum and the 2001 solar maximum, are considered. These environments are coupled to the Langley Research Center (LaRC) deterministic ionized particle transport code High charge (Z) and Energy TRaNsport (HZETRN), which propagates the GCR spectra for elements with charges (Z) in the range I <= Z <= 28 (H -- Ni) and secondary neutrons through selected target materials. The coupling of the GCR extremes to HZETRN allows for the examination of the induced environment within the interior' of an idealized spacecraft

  20. Intraverbal naming and equivalence class formation in children.

    PubMed

    Carp, Charlotte L; Petursdottir, Anna Ingeborg

    2015-11-01

    Six typically developing children between 5 and 7 years of age underwent match-to-sample training to establish three-member equivalence classes after first acquiring a unique name for each stimulus. Horne and Lowe's (1996) naming hypothesis predicts that under those circumstances, match-to-sample training contingencies may establish intraverbal relations between the unique names, which in turn guide correct responses on a subsequent test for stimulus equivalence. Following training of baseline relations (AB and AC), participants received an equivalence test followed by an intraverbal test. Performance on the two tests co-varied, such that three participants passed both tests, and three participants failed repeated administrations of both tests, including a modified version of the equivalence test designed to promote intraverbal responding. The participants who failed the equivalence test, however, did so primarily due to poor performance in transitivity trials, but performed accurately in symmetry trials. After training of a third relation (BC), all three participants performed accurately in a symmetry test for the remaining untrained relations (BA, CA, and CB); two of them in the absence of relevant intraverbal repertoires.

  1. Inertia and Double Bending of Light from Equivalence

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L., Jr.

    2010-01-01

    Careful examination of light paths in an accelerated reference frame, with use of Special Relativity, can account fully for the observed bending of light in a gravitational field, not just half of it as reported in 1911. This analysis also leads to a Machian formulation of inertia similar to the one proposed by Einstein in 1912 and later derived from gravitational field equations in Minkowsky Space by Sciama in 1953. There is a clear inference from equivalence that there is some type of inertial mass increase in a gravitational field. It is the purpose of the current paper to suggest that equivalence provides a more complete picture of gravitational effects than previously thought, correctly predicting full light bending, and that since the theory of inertia is derivable from equivalence, any theory based on equivalence must take account of it. Einstein himself clearly was not satisfied with the status of inertia in GRT, as our quotes have shown. Many have tried to account for inertia and met with less than success, for example Davidson s integration of Sciama s inertia into GRT but only for a steady state cosmology [10], and the Machian gravity theory of Brans and Dicke [11]. Yet Mach s idea hasn t gone away, and now it seems that it cannot go away without also disposing of equivalence.

  2. Equivalent-Continuum Modeling With Application to Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Odegard, Gregory M.; Gates, Thomas S.; Nicholson, Lee M.; Wise, Kristopher E.

    2002-01-01

    A method has been proposed for developing structure-property relationships of nano-structured materials. This method serves as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the vibrational potential energy of a nano-structured material with the strain energy of representative truss and continuum models. As important examples with direct application to the development and characterization of single-walled carbon nanotubes and the design of nanotube-based devices, the modeling technique has been applied to determine the effective-continuum geometry and bending rigidity of a graphene sheet. A representative volume element of the chemical structure of graphene has been substituted with equivalent-truss and equivalent continuum models. As a result, an effective thickness of the continuum model has been determined. This effective thickness has been shown to be significantly larger than the interatomic spacing of graphite. The effective thickness has been shown to be significantly larger than the inter-planar spacing of graphite. The effective bending rigidity of the equivalent-continuum model of a graphene sheet was determined by equating the vibrational potential energy of the molecular model of a graphene sheet subjected to cylindrical bending with the strain energy of an equivalent continuum plate subjected to cylindrical bending.

  3. The equivalent depth of burst for impact cratering

    NASA Technical Reports Server (NTRS)

    Holsapple, K. A.

    1980-01-01

    The concept of modeling an impact cratering event with an explosive event with the explosive buried at some equivalent depth of burst (d.o.b.) is discussed. Various and different ways to define this equivalent d.o.b. are identified. Recent experimental results for a dense quartz sand are used to determine the equivalent d.o.b. for various conditions of charge type, event size, and impact conditions. The results show a decrease in equivalent d.o.b. with increasing energy for fixed impact velocity and a decrease in equivalent d.o.b. with increasing velocity for fixed energy. The values for an iron projectile are on the order of 2-3 projectile radii for energy equal to one ton of TNT, decreasing to about 1.5 radii at a megaton of TNT. The dependence on projectile and target mass density matches that included in common jet-penetration formulas for projectile densities greater than target densities and for the higher energies.

  4. Sequential time interleaved random equivalent sampling for repetitive signal

    NASA Astrophysics Data System (ADS)

    Zhao, Yijiu; Liu, Jingjing

    2016-12-01

    Compressed sensing (CS) based sampling techniques exhibit many advantages over other existing approaches for sparse signal spectrum sensing; they are also incorporated into non-uniform sampling signal reconstruction to improve the efficiency, such as random equivalent sampling (RES). However, in CS based RES, only one sample of each acquisition is considered in the signal reconstruction stage, and it will result in more acquisition runs and longer sampling time. In this paper, a sampling sequence is taken in each RES acquisition run, and the corresponding block measurement matrix is constructed using a Whittaker-Shannon interpolation formula. All the block matrices are combined into an equivalent measurement matrix with respect to all sampling sequences. We implemented the proposed approach with a multi-cores analog-to-digital converter (ADC), whose ADC cores are time interleaved. A prototype realization of this proposed CS based sequential random equivalent sampling method has been developed. It is able to capture an analog waveform at an equivalent sampling rate of 40 GHz while sampled at 1 GHz physically. Experiments indicate that, for a sparse signal, the proposed CS based sequential random equivalent sampling exhibits high efficiency.

  5. Testing the principle of equivalence by solar neutrinos

    SciTech Connect

    Minakata, Hisakazu |; Nunokawa, Hiroshi |

    1994-04-01

    We discuss the possibility of testing the principle of equivalence with solar neutrinos. If there exists a violation of the equivalence principle quarks and leptons with different flavors may not universally couple with gravity. The method we discuss employs a quantum mechanical phenomenon of neutrino oscillation to probe into the non-university of the gravitational couplings of neutrinos. We develop an appropriate formalism to deal with neutrino propagation under the weak gravitational fields of the sun in the presence of the flavor mixing. We point out that solar neutrino observation by the next generation water Cherenkov detectors can improve the existing bound on violation of the equivalence principle by 3-4 orders of magnitude if the nonadiabatic Mikheyev-Smirnov-Wolfenstein mechanism is the solution to the solar neutrino problem.

  6. Inverse grading and hydraulic equivalence in grain-flow deposits

    USGS Publications Warehouse

    Sallenger, A. H.

    1979-01-01

    Inversely graded grain-flow deposits are characterized by a hydraulic equivalence that differs from that based on settling velocities or entrainment. Dispersive equivalence, derived from the dispersive pressure hypothesis on how inverse grading develops, was found to agree reasonably well with observed relationships between grain sizes and densities in grain-flow deposits. Furthermore, observed relationships in deposits formed in subaerial and subaqueous environments were found to be independent of fluid density as is required by dispersive equivalence. The results suggest that dispersive pressure controls the development of the inverse grading common to beach foreshore laminations, slip-face foreset strata, the basal parts of some coarse-grained turbidites, and other diverse deposits.

  7. Wave propagation in equivalent continuums representing truss lattice materials

    SciTech Connect

    Messner, Mark C.; Barham, Matthew I.; Kumar, Mukul; Barton, Nathan R.

    2015-07-29

    Stiffness scales linearly with density in stretch-dominated lattice meta-materials offering the possibility of very light yet very stiff structures. Current additive manufacturing techniques can assemble structures consisting of these lattice materials, but the design of such structures will require accurate, efficient simulation techniques. Equivalent continuum models have several advantages over discrete truss models of stretch dominated lattices, including computational efficiency and ease of model construction. However, the development an equivalent model suitable for representing the dynamic response of a periodic truss is complicated by microinertial effects. This paper derives a dynamic equivalent continuum model for periodic truss structures and verifies it against detailed finite element simulations. The model must incorporate microinertial effects to accurately reproduce long-wavelength characteristics of the response such as anisotropic elastic soundspeeds. The formulation presented here also improves upon previous work by preserving equilibrium at truss joints for affine lattice deformation and by improving numerical stability by eliminating vertices in the effective yield surface.

  8. Equivalent mechanical model for liquid sloshing during draining

    NASA Astrophysics Data System (ADS)

    Li, Qing; Ma, Xingrui; Wang, Tianshu

    2011-01-01

    For a spacecraft draining liquid fuel during a continuous thruster maneuver, a brief equivalent method is proposed to model the time-varying properties of liquid sloshing for dynamics and control design. The sloshing liquid during draining is equivalent to a set of mechanical model with variable parameters. The model parameters for sample filling ratios are determined by an efficient finite element method according to equivalent principles, while the parameters for other filling ratios are obtained by piecewise linear interpolation. Using the proposed model, forces and torques acted on a Cassini shaped tank by the inside liquid during draining are investigated undergoing several typical motions. Verifications and comparative studies are done with Computational Fluid Dynamics simulations, which confirm the accuracy of the brief model while the sloshing amplitude is small and the flow rate is low.

  9. The origins and use of the equivalent temperature concept

    NASA Astrophysics Data System (ADS)

    Eason, E. D.; Hall, G.; Heys, G. B.; Knott, J. F.; Marsden, B. J.; Preston, S. D.; Swan, T.

    2008-10-01

    In some graphite research fields, it is accepted practice to apply an equivalent temperature correction when using graphite data from facilities with differing fast neutron fluxes. The origins of the equivalent temperature hypothesis are described, including the data and theory originally used to justify the approach, and some reservations that have been expressed by various authors are discussed. Relevant findings of recent statistically based work on Gilsocarbon materials irradiated in test reactors at differing flux are presented. The data originally used for justifying the approach and the more recent data analyses both suggest that the use of equivalent temperatures may be justified at low temperatures but not at temperatures above about 300-350 °C. Unfortunately the quantity and quality of the data does not allow for a more exact temperature to be defined.

  10. Asymptotically Jλ -statistical equivalent sequences of weight g

    NASA Astrophysics Data System (ADS)

    Savaş, Ekrem

    2016-08-01

    This paper presents the following definition which is a natural combination of the definition for asymptotically equivalent of weight g, J -statistically limit, and λ - statistical convergence, where g :ℕ →[0 , ∞ ) is a function satisfying g (n) → ∞ and g(n) ↛ 0. The two nonnegative sequences x = (xk) and y = (yk) are said to be asymptotically Jg -statistical equivalent of weight g to multiple L provided that for every ɛ > 0, and δ > 0, {n ∈ℕ : 1/g (λn) |{k ∈In:|x/k yk -L | ≥ɛ }| ≥δ }∈J , (denoted by x ˜SλL(I) g y ) and simply asymptotically Jg -statistical equivalent of weight g if L = 1. In addition, we shall also present some inclusion theorems.

  11. Dynamic equivalences in the hard-sphere dynamic universality class.

    PubMed

    López-Flores, Leticia; Ruíz-Estrada, Honorina; Chávez-Páez, Martín; Medina-Noyola, Magdaleno

    2013-10-01

    We perform systematic simulation experiments on model systems with soft-sphere repulsive interactions to test the predicted dynamic equivalence between soft-sphere liquids with similar static structure. For this we compare the simulated dynamics (mean squared displacement, intermediate scattering function, α-relaxation time, etc.) of different soft-sphere systems, between them and with the hard-sphere liquid. We then show that the referred dynamic equivalence does not depend on the (Newtonian or Brownian) nature of the microscopic laws of motion of the constituent particles, and hence, applies independently to colloidal and to atomic simple liquids. Finally, we verify another more recently proposed dynamic equivalence, this time between the long-time dynamics of an atomic liquid and its corresponding Brownian fluid (i.e., the Brownian system with the same interaction potential).

  12. Methods for proving the equivalency of detonator performance

    SciTech Connect

    Munger, Alan C; Akinci, Adrian A; Thomas, Keith A; Clarke, Steve A; Martin, Eric S; Murphy, Michael J

    2009-01-01

    One of the challenges facing engineers is developing newer, safer detonators that are equivalent to devices currently in use. There is no clear consensus on an exact method for drawing equivalence of detonators. This paper summarizes our current efforts to develop diagnostics addressing various aspects of detonator design to better quantify and prove equivalency. We consider various optical techniques to quantify the output pressure and output wave shape. The development of a unique interpretation of streak camera breakouts, known as the apparent center of initiation, will be discussed as a metric for detonation wave shape. Specific examples apply these techniques to the comparison of a new laser-driven detonator with an existing exploding bridgewire (EBW) detonator. Successes and short-comings of the techniques will be discussed.

  13. Topological equivalence between the Fibonacci quasicrystal and the Harper model.

    PubMed

    Kraus, Yaacov E; Zilberberg, Oded

    2012-09-14

    One-dimensional quasiperiodic systems, such as the Harper model and the Fibonacci quasicrystal, have long been the focus of extensive theoretical and experimental research. Recently, the Harper model was found to be topologically nontrivial. Here, we derive a general model that embodies a continuous deformation between these seemingly unrelated models. We show that this deformation does not close any bulk gaps, and thus prove that these models are in fact topologically equivalent. Remarkably, they are equivalent regardless of whether the quasiperiodicity appears as an on-site or hopping modulation. This proves that these different models share the same boundary phenomena and explains past measurements. We generalize this equivalence to any Fibonacci-like quasicrystal, i.e., a cut and project in any irrational angle.

  14. Basic neuron model electrical equivalent circuit: an undergraduate laboratory exercise.

    PubMed

    Dabrowski, Katie M; Castaño, Diego J; Tartar, Jaime L

    2013-01-01

    We developed a hands-on laboratory exercise for undergraduate students in which they can build and manipulate a neuron equivalent circuit. This exercise uses electrical circuit components that resemble neuron components and are easy to construct. We describe the methods for creating the equivalent circuit and how to observe different neuron properties through altering the structure of the equivalent circuit. We explain how this hands-on laboratory activity allows for the better understanding of this fundamental neuroscience concept. At the conclusion of this laboratory exercise, undergraduate students will be able to apply the principles of Ohm's law, cable theory with regards to neurons, and understand the functions of resistance and capacitance in a neuron.

  15. Improved equivalent circuits for acoustic plate wave devices.

    PubMed

    Zaitsev, B D; Kuznetsova, I E; Joshi, S G

    2002-05-01

    This paper presents improved equivalent circuits for the analysis and design of acoustic plate wave devices. The method uses a mixed equivalent circuit for the interdigital transducer consisting of both active and passive sections placed on the surface of a piezoelectric plate. The values of the various circuit elements are obtained by carrying out a best fit between theoretical and experimental frequency dependence of the real and imaginary parts of transducer input impedance. Knowledge of the equivalent circuit parameters allows one to optimize design of the devices. The method has been successfully employed for the design of one-port shear-horizontal wave resonators on Y-X lithium niobate plates. The proposed method can also be utilized for determining acoustic wave velocity with high accuracy.

  16. Other Questions with Respect to the Weak Equivalence Principle

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2017-01-01

    A disc rotating at high speed will exert out-of-plane forces resembling an accelerating field. Is the principle of equivalence also applicable for this process? Will someone inside an elevator in free-fall and rotating around its vertical centre, feel a gravitational force? Or will he feel a gravitational force larger than what equivalence principle requires? Does the equivalence principle remain applicable here? An airplane flies at an altitude of 1 km. The co-pilot drops an elevator-room without a passenger inside it. After one second has elapsed, the co-pilot drops four grenades in the direction of the freely-falling elevator's path. The question: Will the grenades reach the elevator before it reaches the ground? If no, why? If yes, which grenade? How will the air resistance influence the outcome?

  17. Motor equivalence during multi-finger accurate force production

    PubMed Central

    Mattos, Daniela; Schöner, Gregor; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2014-01-01

    We explored stability of multi-finger cyclical accurate force production action by analysis of responses to small perturbations applied to one of the fingers and inter-cycle analysis of variance. Healthy subjects performed two versions of the cyclical task, with and without an explicit target. The “inverse piano” apparatus was used to lift/lower a finger by 1 cm over 0.5 s; the subjects were always instructed to perform the task as accurate as they could at all times. Deviations in the spaces of finger forces and modes (hypothetical commands to individual fingers) were quantified in directions that did not change total force (motor equivalent) and in directions that changed the total force (non-motor equivalent). Motor equivalent deviations started immediately with the perturbation and increased progressively with time. After a sequence of lifting-lowering perturbations leading to the initial conditions, motor equivalent deviations were dominating. These phenomena were less pronounced for analysis performed with respect to the total moment of force with respect to an axis parallel to the forearm/hand. Analysis of inter-cycle variance showed consistently higher variance in a subspace that did not change the total force as compared to the variance that affected total force. We interpret the results as reflections of task-specific stability of the redundant multi-finger system. Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbation involve large changes of neural commands that do not affect salient performance variables, even during actions with the purpose to correct those salient variables. Consistency of the analyses of motor equivalence and variance analysis provides additional support for the idea of task-specific stability ensured at a neural level. PMID:25344311

  18. Technical note: Equivalent genomic models with a residual polygenic effect.

    PubMed

    Liu, Z; Goddard, M E; Hayes, B J; Reinhardt, F; Reents, R

    2016-03-01

    Routine genomic evaluations in animal breeding are usually based on either a BLUP with genomic relationship matrix (GBLUP) or single nucleotide polymorphism (SNP) BLUP model. For a multi-step genomic evaluation, these 2 alternative genomic models were proven to give equivalent predictions for genomic reference animals. The model equivalence was verified also for young genotyped animals without phenotypes. Due to incomplete linkage disequilibrium of SNP markers to genes or causal mutations responsible for genetic inheritance of quantitative traits, SNP markers cannot explain all the genetic variance. A residual polygenic effect is normally fitted in the genomic model to account for the incomplete linkage disequilibrium. In this study, we start by showing the proof that the multi-step GBLUP and SNP BLUP models are equivalent for the reference animals, when they have a residual polygenic effect included. Second, the equivalence of both multi-step genomic models with a residual polygenic effect was also verified for young genotyped animals without phenotypes. Additionally, we derived formulas to convert genomic estimated breeding values of the GBLUP model to its components, direct genomic values and residual polygenic effect. Third, we made a proof that the equivalence of these 2 genomic models with a residual polygenic effect holds also for single-step genomic evaluation. Both the single-step GBLUP and SNP BLUP models lead to equal prediction for genotyped animals with phenotypes (e.g., reference animals), as well as for (young) genotyped animals without phenotypes. Finally, these 2 single-step genomic models with a residual polygenic effect were proven to be equivalent for estimation of SNP effects, too.

  19. Offsetting Ongoing Methane Emissions --- An Alternative to Emission Equivalence Metrics

    NASA Astrophysics Data System (ADS)

    Clisby, N.; Enting, I. G.; Lauder, A.; Carter, J.; Cowie, A.; Henry, B.; Raupach, M. R.

    2012-12-01

    The Global Warming Potential (GWP) has been widely adopted as a metric for comparing the climate impact of different greenhouse gases. As has been frequently noted, there are many problems with using GWPs to define emission equivalence in spite of the use of GWPs for this purpose in contexts such as the Kyoto Protocol. We propose that for methane, rather than define emission equivalence, the appropriate comparison is between ongoing emissions of 0.9 to 1.0 kg of CH4 per year and one-off emissions of 1 tonne of carbon. This approach represents an approximate solution to the inverse problem of defining a forcing equivalent index (FEI) that gives exact equivalence of radiative forcing over a range of timescales. In our approach, if ongoing methane emissions are offset by a one-off carbon removal that is built up with 40-year e-folding time, then the result is close to radiatively neutral over periods from years to centuries. In contrast, the GWP provides radiative equivalence (in integrated terms) only at a single time, with large discrepancies at other times. Our approach also follows from consideration of greenhouse gas stabilisation, since stabilising atmospheric CO2 requires an approximate cap on total emissions, while stabilising methane requires stabilisation of ongoing emissions. Our quantitative treatment recognises that, on time scales of centuries, removal of 1 tonne of carbon only lowers the atmospheric carbon content by 0.3 to 0.35 tonnes. We discuss the implications for rangeland grazing systems. In the absence of effective mitigation techniques for methane from rangeland systems, this approach may provide an attractive offset mechanism in spite of requiring that woody vegetation be established and maintained over about 15% of the landscape, or an equivalent amount of carbon storage in soil.

  20. Equilibrium polymerization on the equivalent-neighbor lattice

    NASA Technical Reports Server (NTRS)

    Kaufman, Miron

    1989-01-01

    The equilibrium polymerization problem is solved exactly on the equivalent-neighbor lattice. The Flory-Huggins (Flory, 1986) entropy of mixing is exact for this lattice. The discrete version of the n-vector model is verified when n approaches 0 is equivalent to the equal reactivity polymerization process in the whole parameter space, including the polymerized phase. The polymerization processes for polymers satisfying the Schulz (1939) distribution exhibit nonuniversal critical behavior. A close analogy is found between the polymerization problem of index the Schulz r and the Bose-Einstein ideal gas in d = -2r dimensions, with the critical polymerization corresponding to the Bose-Einstein condensation.

  1. In vitro assessment of equivalence of occupational health risk: welders.

    PubMed Central

    Stern, R M

    1983-01-01

    The possibility of using in vitro testing to determine the equivalence of risk for various occupational groups is discussed. In the absence of epidemiological evidence or relevant animal in vivo bioassays on which to determine the health effects of specific occupational exposures, it is proposed to use similarities in the in vitro response to substances with known (or strongly suspected) and unknown risk to demonstrate their risk equivalence. Identification and evaluation of a high risk "hot spot" due to exposure to Cr(VI) for stainless steel welders is discussed in terms of recent developments in collection, analysis and bioassay of welding fumes. PMID:6641655

  2. Equivalent Latitude Computation Using Regions of Interest (ROI)

    PubMed Central

    Añel, Juan A.; Allen, Douglas R.; Sáenz, Guadalupe; Gimeno, Luis; de la Torre, Laura

    2013-01-01

    This paper introduces a novel algorithm to compute equivalent latitude by applying regions of interest (ROI). The technique is illustrated using code written in Interactive Data Language (IDL). The ROI method is compared with the “piecewise-constant” method, the approach commonly used in atmospheric sciences, using global fields of atmospheric potential vorticity. The ROI method is considerably more accurate and computationally faster than the piecewise-constant method, and it also works well with irregular grids. Both the ROI and piecewise-constant IDL codes for equivalent latitude are included as a useful reference for the research community. PMID:24086267

  3. Probing students' ideas of the principle of equivalence

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Atanu; Kumar, Arvind

    2011-01-01

    The principle of equivalence was the first vital clue to Einstein in his extension of special relativity to general relativity, the modern theory of gravitation. In this paper we investigate in some detail students' understanding of this principle in a variety of contexts, when they are undergoing an introductory course on general relativity. The tool of assessment is a diagnostic questionnaire administered to a group of 30 senior undergraduates going through the course. The analysis of responses reveals a number of significant conceptual vulnerabilities in several aspects of the topic. The most important among these is related to the notion of an inertial frame that follows naturally from the principle of equivalence.

  4. Electric circuit networks equivalent to chaotic quantum billiards

    SciTech Connect

    Bulgakov, Evgeny N.; Maksimov, Dmitrii N.; Sadreev, Almas F.

    2005-04-01

    We consider two electric RLC resonance networks that are equivalent to quantum billiards. In a network of inductors grounded by capacitors, the eigenvalues of the quantum billiard correspond to the squared resonant frequencies. In a network of capacitors grounded by inductors, the eigenvalues of the billiard are given by the inverse of the squared resonant frequencies. In both cases, the local voltages play the role of the wave function of the quantum billiard. However, unlike for quantum billiards, there is a heat power because of the resistance of the inductors. In the equivalent chaotic billiards, we derive a distribution of the heat power which describes well the numerical statistics.

  5. 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in extracts of Baltic white-tailed sea eagles

    SciTech Connect

    Koistinen, J.; Giesy, J.P.; Koivusaari, J.; Nuuja, I.; Vuorinen, P.J.; Paasivirta, J.

    1997-07-01

    Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin-(TCDD) equivalents were measured in extracts of Baltic white-tailed sea eagle tissues. Extracts of salmon, ringed seal, and grey seal were analyzed as other predatory species of the same area. Concentrations in eagle and seal tissues were greater than those in salmon. Concentrations of TCDD equivalents (TCDD-EQs) determined by the H4IIE bioassay were compared with toxic equivalents (TEQs) derived from instrumental chemical analyses in fractions containing polychlorinated dibenzo-P-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) or coplanar polychlorinated biphenyls (PCBs). Toxic equivalents were calculated by use of an additive model in which the product of the concentrations of instrumentally measured individual congeners were multiplied by their TCDD equivalency factors and were summed to give a total concentration of TEQs. The TCDD-EQs were compared with TEQs to develop a mass balance to determine whether all the TCDD-like activity was accounted for. The TEQs determined by chemical analyses for coplanar PCBs was 770 pg/g fw, and that of PCDD/PCDFs was 270 pg/g fw in this eagle. Thus, concentrations of TCDD-EQs were approx. 20% greater than those of TEQs. The true difference in activities is probably greater because of lower recoveries and infra-additivities among congeners in the bioassay. This indicates that there are compounds present in the extracts that can contribute to the total concentrations of TCDD-EQs in white-tailed sea eagle eggs to the no-observable-adverse-effect concentration, ranged from 7.3 to 141. This indicates that current concentrations of TCDD-EQs in these eggs are likely causing adverse effects in the Baltic populations of white-tailed sea eagles. This study indicated that the H4IIE bioassay is useful for monitoring the presence and biological activity of TCDD-like compounds in environmental samples like white-tailed sea eagles.

  6. 21 CFR 26.15 - Monitoring continued equivalence.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Monitoring continued equivalence. 26.15 Section 26.15 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY...

  7. The Equivalence of Precession Phenomena in Metric Theories of Gravity

    NASA Technical Reports Server (NTRS)

    Krisher, Timothy P.

    1996-01-01

    The requirement of general covariance imparts to metric theories of gravity, such as general relativity, important structural features. A precise mathematical form results, ensuring that computation of observable physical effects in the theory gives the same answers independently of the chosen system of coordinates. This coordinate independence property, in turn, can lead to an equivalence of apparently different physical effects.

  8. Transfer of Aversive Respondent Elicitation in Accordance with Equivalence Relations

    ERIC Educational Resources Information Center

    Valverde, Miguel Rodriguez; Luciano, Carmen; Barnes-Holmes, Dermot

    2009-01-01

    The present study investigates the transfer of aversively conditioned respondent elicitation through equivalence classes, using skin conductance as the measure of conditioning. The first experiment is an attempt to replicate Experiment 1 in Dougher, Augustson, Markham, Greenway, and Wulfert (1994), with different temporal parameters in the…

  9. Equivalent Skin Analysis of Wing Structures Using Neural Networks

    NASA Technical Reports Server (NTRS)

    Liu, Youhua; Kapania, Rakesh K.

    2000-01-01

    An efficient method of modeling trapezoidal built-up wing structures is developed by coupling. in an indirect way, an Equivalent Plate Analysis (EPA) with Neural Networks (NN). Being assumed to behave like a Mindlin-plate, the wing is solved using the Ritz method with Legendre polynomials employed as the trial functions. This analysis method can be made more efficient by avoiding most of the computational effort spent on calculating contributions to the stiffness and mass matrices from each spar and rib. This is accomplished by replacing the wing inner-structure with an "equivalent" material that combines to the skin and whose properties are simulated by neural networks. The constitutive matrix, which relates the stress vector to the strain vector, and the density of the equivalent material are obtained by enforcing mass and stiffness matrix equities with rec,ard to the EPA in a least-square sense. Neural networks for the material properties are trained in terms of the design variables of the wing structure. Examples show that the present method, which can be called an Equivalent Skin Analysis (ESA) of the wing structure, is more efficient than the EPA and still fairly good results can be obtained. The present ESA is very promising to be used at the early stages of wing structure design.

  10. 21 CFR 26.45 - Monitoring continued equivalence.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Monitoring continued equivalence. 26.45 Section 26.45 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY...

  11. 21 CFR 26.45 - Monitoring continued equivalence.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Monitoring continued equivalence. 26.45 Section 26.45 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY...

  12. 21 CFR 26.45 - Monitoring continued equivalence.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Monitoring continued equivalence. 26.45 Section 26.45 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY...

  13. 21 CFR 26.45 - Monitoring continued equivalence.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Monitoring continued equivalence. 26.45 Section 26.45 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY...

  14. Maintaining Equivalent Cut Scores for Small Sample Test Forms

    ERIC Educational Resources Information Center

    Dwyer, Andrew C.

    2016-01-01

    This study examines the effectiveness of three approaches for maintaining equivalent performance standards across test forms with small samples: (1) common-item equating, (2) resetting the standard, and (3) rescaling the standard. Rescaling the standard (i.e., applying common-item equating methodology to standard setting ratings to account for…

  15. An Analysis of the Myth of Cultural Equivalence

    ERIC Educational Resources Information Center

    Lange, John

    2010-01-01

    In this article, the author offers a "Pierce-ing," rational dissection of the notion of cultural equivalence that exposes the hypocrisy of its purveyors. He tackles three major argument lines--the Probabilities Argument, the Internal-Division Argument, and the Change Argument--and proves that it is simply very improbable that culture, in any…

  16. 30 CFR 71.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... concentrations. 71.206 Section 71.206 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in... passing through the filter and then converting that concentration to an equivalent concentration...

  17. 30 CFR 90.206 - Approved sampling devices; equivalent concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... concentrations. 90.206 Section 90.206 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... concentrations. The concentration of respirable dust shall be determined by dividing the weight of dust in... passing through the filter and then converting that concentration to an equivalent concentration...

  18. 29 CFR 4.170 - Furnishing fringe benefits or equivalents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... required under the determination in order to satisfy his fringe benefit obligations under the Act, and must... fringe benefit obligations which may be required by an applicable fringe benefit determination, such as... 29 Labor 1 2010-07-01 2010-07-01 true Furnishing fringe benefits or equivalents. 4.170 Section...

  19. One-to-One Play Promotes Numerical Equivalence Concepts

    ERIC Educational Resources Information Center

    Mix, Kelly S.; Moore, Julie A.; Holcomb, Erin

    2011-01-01

    Young children spontaneously engage in a variety of one-to-one correspondence activities during play. The present study tested whether one of these activities--pairing objects with containers--supported the development of numerical equivalence judgments. Three-year-olds were given sets of toys to take home. In one condition, the toys were…

  20. Apparatus for Teaching Physics. Mechanical Equivalent of Heat.

    ERIC Educational Resources Information Center

    Inscho, F. Paul

    1992-01-01

    Suggests an apparatus to improve the measurement of the mechanical equivalent of heat. Describes the materials needed to construct the apparatus; the methodology of an experiment to measure the heat gained by lead shot falling through a distance of 100 meters; and the calculations made to register that gain. (MDH)