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Sample records for efficient stereological estimation

  1. Abdominal fat volume estimation by stereology on CT: a comparison with manual planimetry.

    Science.gov (United States)

    Manios, G E; Mazonakis, M; Voulgaris, C; Karantanas, A; Damilakis, J

    2016-03-01

    To deploy and evaluate a stereological point-counting technique on abdominal CT for the estimation of visceral (VAF) and subcutaneous abdominal fat (SAF) volumes. Stereological volume estimations based on point counting and systematic sampling were performed on images from 14 consecutive patients who had undergone abdominal CT. For the optimization of the method, five sampling intensities in combination with 100 and 200 points were tested. The optimum stereological measurements were compared with VAF and SAF volumes derived by the standard technique of manual planimetry on the same scans. Optimization analysis showed that the selection of 200 points along with the sampling intensity 1/8 provided efficient volume estimations in less than 4 min for VAF and SAF together. The optimized stereology showed strong correlation with planimetry (VAF: r = 0.98; SAF: r = 0.98). No statistical differences were found between the two methods (VAF: P = 0.81; SAF: P = 0.83). The 95% limits of agreement were also acceptable (VAF: -16.5%, 16.1%; SAF: -10.8%, 10.7%) and the repeatability of stereology was good (VAF: CV = 4.5%, SAF: CV = 3.2%). Stereology may be successfully applied to CT images for the efficient estimation of abdominal fat volume and may constitute a good alternative to the conventional planimetric technique. Abdominal obesity is associated with increased risk of disease and mortality. Stereology may quantify visceral and subcutaneous abdominal fat accurately and consistently. The application of stereology to estimating abdominal volume fat reduces processing time. Stereology is an efficient alternative method for estimating abdominal fat volume.

  2. Improving efficiency in stereology

    DEFF Research Database (Denmark)

    Keller, Kresten Krarup; Andersen, Ina Trolle; Andersen, Johnnie Bremholm

    2013-01-01

    of the study was to investigate the time efficiency of the proportionator and the autodisector on virtual slides compared with traditional methods in a practical application, namely the estimation of osteoclast numbers in paws from mice with experimental arthritis and control mice. Tissue slides were scanned......, a proportionator sampling and a systematic, uniform random sampling were simulated. We found that the proportionator was 50% to 90% more time efficient than systematic, uniform random sampling. The time efficiency of the autodisector on virtual slides was 60% to 100% better than the disector on tissue slides. We...... conclude that both the proportionator and the autodisector on virtual slides may improve efficiency of cell counting in stereology....

  3. Abdominal fat volume estimation by stereology on CT: a comparison with manual planimetry

    Energy Technology Data Exchange (ETDEWEB)

    Manios, G.E.; Mazonakis, M.; Damilakis, J. [University of Crete, Department of Medical Physics, Faculty of Medicine, Heraklion, Crete (Greece); Voulgaris, C.; Karantanas, A. [University of Crete, Department of Radiology, Faculty of Medicine, Heraklion, Crete (Greece)

    2016-03-15

    To deploy and evaluate a stereological point-counting technique on abdominal CT for the estimation of visceral (VAF) and subcutaneous abdominal fat (SAF) volumes. Stereological volume estimations based on point counting and systematic sampling were performed on images from 14 consecutive patients who had undergone abdominal CT. For the optimization of the method, five sampling intensities in combination with 100 and 200 points were tested. The optimum stereological measurements were compared with VAF and SAF volumes derived by the standard technique of manual planimetry on the same scans. Optimization analysis showed that the selection of 200 points along with the sampling intensity 1/8 provided efficient volume estimations in less than 4 min for VAF and SAF together. The optimized stereology showed strong correlation with planimetry (VAF: r = 0.98; SAF: r = 0.98). No statistical differences were found between the two methods (VAF: P = 0.81; SAF: P = 0.83). The 95 % limits of agreement were also acceptable (VAF: -16.5 %, 16.1 %; SAF: -10.8 %, 10.7 %) and the repeatability of stereology was good (VAF: CV = 4.5 %, SAF: CV = 3.2 %). Stereology may be successfully applied to CT images for the efficient estimation of abdominal fat volume and may constitute a good alternative to the conventional planimetric technique. (orig.)

  4. Digital stereology in neuropathology

    DEFF Research Database (Denmark)

    Kristiansen, Sarah Line Brøgger; Nyengaard, Jens Randel

    2012-01-01

    will therefore present the relevant stereological estimators for obtaining reliable quantitative structural data from brains and peripheral nerves when using digital light microscopy. It is discussed how to obtain brain and nerve fibre samples to fulfil the requirements for the estimators. A presentation......-dimensional structural knowledge. Accordingly, stereology is a science based on statistical sampling principles and geometric measures. The application of stereology to neuropathological studies allows the researcher to efficiently obtain a precise estimate of various structural quantities. This neuropathological review...

  5. Efficient stereological approaches for the volumetry of a normal or enlarged spleen from MDCT images

    Energy Technology Data Exchange (ETDEWEB)

    Mazonakis, Michalis; Stratakis, John; Damilakis, John [University of Crete, Department of Medical Physics, Faculty of Medicine, P.O. Box 2208, Iraklion, Crete (Greece)

    2015-06-01

    To introduce efficient stereological approaches for estimating the volume of a normal or enlarged spleen from MDCT. All study participants underwent an abdominal MDCT. The first group included 20 consecutive patients with splenomegaly and the second group consisted of 20 subjects with a normal spleen. Splenic volume estimations were performed using the stereological point counting method. Stereological assessments were optimized using the systematic slice sampling procedure. Planimetric measurements based on manual tracing of splenic boundaries on each slice were taken as reference values. Stereological analysis using five to eight systematically sampled slices provided enlarged splenic volume estimations with a mean precision of 4.9 ± 1.0 % in a mean time of 2.3 ± 0.4 min. A similar measurement duration and error was observed for normal splenic volume assessment using four to seven systematically selected slices. These stereological approaches slightly but insignificantly overestimated the volume of a normal and enlarged spleen compared to planimetry (P > 0.05) with a mean difference of -1.3 ± 4.3 % and -2.7 ± 5.2 %, respectively. The two methods were highly correlated (r ≥ 0.96). The variability of repeated stereological estimations was below 3.8 %. The proposed stereological approaches enable the rapid, reproducible, and accurate splenic volume estimation from MDCT data in patients with or without splenomegaly. (orig.)

  6. Estimation of absolute microglial cell numbers in mouse fascia dentata using unbiased and efficient stereological cell counting principles

    DEFF Research Database (Denmark)

    Wirenfeldt, Martin; Dalmau, Ishar; Finsen, Bente

    2003-01-01

    Stereology offers a set of unbiased principles to obtain precise estimates of total cell numbers in a defined region. In terms of microglia, which in the traumatized and diseased CNS is an extremely dynamic cell population, the strength of stereology is that the resultant estimate is unaffected...... of microglia, although with this thickness, the intensity of the staining is too high to distinguish single cells. Lectin histochemistry does not visualize microglia throughout the section and, accordingly, is not suited for the optical fractionator. The mean total number of Mac-1+ microglial cells...... in the unilateral dentate gyrus of the normal young adult male C57BL/6 mouse was estimated to be 12,300 (coefficient of variation (CV)=0.13) with a mean coefficient of error (CE) of 0.06. The perspective of estimating microglial cell numbers using stereology is to establish a solid basis for studying the dynamics...

  7. Stereological estimation of surface area from digital images

    DEFF Research Database (Denmark)

    Ziegel, Johanna; Kiderlen, Markus

    2010-01-01

    A sampling design of local stereology is combined with a method from digital stereology to yield a novel estimator of surface area based on counts of configurations observed in a digitization of an isotropic 2- dimensional slice with thickness s. As a tool, a result of the second author and J....... Rataj on infinitesimal increase of volumes of morphological transforms is refined and used. The proposed surface area estimator is asymptotically unbiased in the case of sets contained in the ball centred at the origin with radius s and in the case of balls centred at the origin with unknown radius...

  8. Stereological estimation of nuclear volume in benign and atypical meningiomas

    DEFF Research Database (Denmark)

    Madsen, C; Schrøder, H D

    1993-01-01

    A stereological estimation of nuclear volume in benign and atypical meningiomas was made. The aim was to investigate whether this method could discriminate between these two meningeal neoplasms. The difference was significant and it was moreover seen that there was no overlap between the two groups....... The results demonstrate that atypical meningiomas can be distinguished from benign meningiomas by an objective stereological estimation of nuclear volume....

  9. Sampling for stereology in lungs

    Directory of Open Access Journals (Sweden)

    J. R. Nyengaard

    2006-12-01

    of view, and noise due to random positioning of the probes. This can be decreased by increasing the number of units from the element causing the most variance. Overall, stereology provides lung scientists with efficient tools for estimating structural components correctly.

  10. The proportionator: unbiased stereological estimation using biased automatic image analysis and non-uniform probability proportional to size sampling

    DEFF Research Database (Denmark)

    Gardi, Jonathan Eyal; Nyengaard, Jens Randel; Gundersen, Hans Jørgen Gottlieb

    2008-01-01

    examined, which in turn leads to any of the known stereological estimates, including size distributions and spatial distributions. The unbiasedness is not a function of the assumed relation between the weight and the structure, which is in practice always a biased relation from a stereological (integral......, the desired number of fields are sampled automatically with probability proportional to the weight and presented to the expert observer. Using any known stereological probe and estimator, the correct count in these fields leads to a simple, unbiased estimate of the total amount of structure in the sections...... geometric) point of view. The efficiency of the proportionator depends, however, directly on this relation to be positive. The sampling and estimation procedure is simulated in sections with characteristics and various kinds of noises in possibly realistic ranges. In all cases examined, the proportionator...

  11. STEREOLOGICAL ESTIMATION OF SURFACE AREA FROM DIGITAL IMAGES

    Directory of Open Access Journals (Sweden)

    Johanna Ziegel

    2011-05-01

    Full Text Available A sampling design of local stereology is combined with a method from digital stereology to yield a novel estimator of surface area based on counts of configurations observed in a digitization of an isotropic 2- dimensional slice with thickness s. As a tool, a result of the second author and J. Rataj on infinitesimal increase of volumes of morphological transforms is refined and used. The proposed surface area estimator is asymptotically unbiased in the case of sets contained in the ball centred at the origin with radius s and in the case of balls centred at the origin with unknown radius. For general shapes bounds for the asymptotic expected relative worst case error are given. A simulation example is discussed for surface area estimation based on 2×2×2-configurations.

  12. The efficiency of systematic sampling in stereology-reconsidered

    DEFF Research Database (Denmark)

    Gundersen, Hans Jørgen Gottlieb; Jensen, Eva B. Vedel; Kieu, K

    1999-01-01

    In the present paper, we summarize and further develop recent research in the estimation of the variance of stereological estimators based on systematic sampling. In particular, it is emphasized that the relevant estimation procedure depends on the sampling density. The validity of the variance...... estimation is examined in a collection of data sets, obtained by systematic sampling. Practical recommendations are also provided in a separate section....

  13. Stereological estimation of nuclear mean volume in invasive meningiomas

    DEFF Research Database (Denmark)

    Madsen, C; Schrøder, H D

    1996-01-01

    A stereological estimation of nuclear mean volume in bone and brain invasive meningiomas was made. For comparison the nuclear mean volume of benign meningiomas was estimated. The aim was to investigate whether this method could discriminate between these groups. We found that the nuclear mean...... volume in the bone and brain invasive meningiomas was larger than in the benign tumors. The difference was significant and moreover it was seen that there was no overlap between the two groups. In the bone invasive meningiomas the nuclear mean volume appeared to be larger inside than outside the bone....... No significant difference in nuclear mean volume was found between brain and bone invasive meningiomas. The results demonstrate that invasive meningiomas differ from benign meningiomas by an objective stereological estimation of nuclear mean volume (p

  14. An unbiased stereological method for efficiently quantifying the innervation of the heart and other organs based on total length estimations

    DEFF Research Database (Denmark)

    Mühlfeld, Christian; Papadakis, Tamara; Krasteva, Gabriela

    2010-01-01

    Quantitative information about the innervation is essential to analyze the structure-function relationships of organs. So far, there has been no unbiased stereological tool for this purpose. This study presents a new unbiased and efficient method to quantify the total length of axons in a given...... reference volume, illustrated on the left ventricle of the mouse heart. The method is based on the following steps: 1) estimation of the reference volume; 2) randomization of location and orientation using appropriate sampling techniques; 3) counting of nerve fiber profiles hit by a defined test area within...

  15. Nondestructive, stereological estimation of canopy surface area

    DEFF Research Database (Denmark)

    Wulfsohn, Dvora-Laio; Sciortino, Marco; Aaslyng, Jesper M.

    2010-01-01

    We describe a stereological procedure to estimate the total leaf surface area of a plant canopy in vivo, and address the problem of how to predict the variance of the corresponding estimator. The procedure involves three nested systematic uniform random sampling stages: (i) selection of plants from...... a canopy using the smooth fractionator, (ii) sampling of leaves from the selected plants using the fractionator, and (iii) area estimation of the sampled leaves using point counting. We apply this procedure to estimate the total area of a chrysanthemum (Chrysanthemum morifolium L.) canopy and evaluate both...... the time required and the precision of the estimator. Furthermore, we compare the precision of point counting for three different grid intensities with that of several standard leaf area measurement techniques. Results showed that the precision of the plant leaf area estimator based on point counting...

  16. Stereological estimation of nuclear volume in benign and atypical meningiomas

    DEFF Research Database (Denmark)

    Madsen, C; Schrøder, H D

    1993-01-01

    A stereological estimation of nuclear volume in benign and atypical meningiomas was made. The aim was to investigate whether this method could discriminate between these two meningeal neoplasms. The difference was significant and it was moreover seen that there was no overlap between the two groups...

  17. Stereological analysis of spatial structures

    DEFF Research Database (Denmark)

    Hansen, Linda Vadgård

    The thesis deals with stereological analysis of spatial structures. One area of focus has been to improve the precision of well-known stereological estimators by including information that is available via automatic image analysis. Furthermore, the thesis presents a stochastic model for star......-shaped three-dimensional objects using the radial function. It appears that the model is highly fleksiblel in the sense that it can be used to describe an object with arbitrary irregular surface. Results on the distribution of well-known local stereological volume estimators are provided....

  18. A simple and efficient alternative to implementing systematic random sampling in stereological designs without a motorized microscope stage.

    Science.gov (United States)

    Melvin, Neal R; Poda, Daniel; Sutherland, Robert J

    2007-10-01

    When properly applied, stereology is a very robust and efficient method to quantify a variety of parameters from biological material. A common sampling strategy in stereology is systematic random sampling, which involves choosing a random sampling [corrected] start point outside the structure of interest, and sampling relevant objects at [corrected] sites that are placed at pre-determined, equidistant intervals. This has proven to be a very efficient sampling strategy, and is used widely in stereological designs. At the microscopic level, this is most often achieved through the use of a motorized stage that facilitates the systematic random stepping across the structure of interest. Here, we report a simple, precise and cost-effective software-based alternative to accomplishing systematic random sampling under the microscope. We believe that this approach will facilitate the use of stereological designs that employ systematic random sampling in laboratories that lack the resources to acquire costly, fully automated systems.

  19. A note on stereological estimation of the volume-weighted second moment of particle volume

    DEFF Research Database (Denmark)

    Jensen, E B; Sørensen, Flemming Brandt

    1991-01-01

    It is shown that for a variety of biological particle shapes, the volume-weighted second moment of particle volume can be estimated stereologically using only the areas of particle transects, which can be estimated manually by point-counting....

  20. Application of stereology to dermatological research

    DEFF Research Database (Denmark)

    Kamp, Søren; Jemec, Gregor Borut Ernst; Kemp, Kåre

    2009-01-01

    Stereology is a set of mathematical and statistical tools to estimate three-dimensional (3-D) characteristics of objects from regular two-dimensional (2-D) sections. In medicine and biology, it can be used to estimate features such as cell volume, cell membrane surface area, total length of blood...... vessels per volume tissue and total number of cells. The unbiased quantification of these 3-D features allows for a better understanding of morphology in vivo compared with 2-D methods. This review provides an introduction to the field of stereology with specific emphasis on the application of stereology...

  1. THE APPLICATION OF STEREOLOGY METHOD FOR ESTIMATING THE NUMBER OF 3D BaTiO3 – CERAMIC GRAINS CONTACT SURFACES

    Directory of Open Access Journals (Sweden)

    Vojislav V Mitić

    2011-05-01

    Full Text Available Methods of stereological study are of great importance for structural research of electronic ceramic materials including BaTiO3-ceramic materials. The broad application of ceramics, based on barium-titanate, in advanced electronics nowadays demands a constant research of its structure, that through the correlation structureproperties, a fundamental in the basic materials properties prognosis triad (technology-structure-properties, leads to further prognosis and properties design of these ceramics. Microstructure properties of BaTiO3- ceramic material, expressed in grains' boundary contact, are of basic importance for electric properties of this material, particularly the capacity. In this paper, a significant step towards establishing control under capacitive properties of BaTiO3-ceramics is being done by estimating the number of grains contact surfaces. Defining an efficient stereology method for estimating the number of BaTiO3-ceramic grains contact surfaces, we have started from a mathematical model of mutual grains distribution in the prescribed volume of BaTiO3-ceramic sample. Since the real microstructure morphology of BaTiO3-ceramics is in some way disordered, spherical shaped grains, using computer-modelling methods, are approximated by polyhedra with a great number of small convex polygons. By dividing the volume of BaTiO3-ceramic sample with the definite number of parallel planes, according to a given pace, into the intersection plane a certain number of grains contact surfaces are identified. According to quantitative estimation of 2D stereological parameters the modelled 3D internal microstructure is obtained. Experiments were made by using the scanning electronic microscopy (SEM method with the ceramic samples prepared under pressing pressures up to 150 MPa and sintering temperature up to 1370°C while the obtained microphotographs were used as a base of confirming the validity of presented stereology method. This paper, by applying

  2. DNA-index and stereological estimation of nuclear volume in primary and metastatic malignant melanomas

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Kristensen, I B; Grymer, F

    1990-01-01

    The aim of this study was to investigate the relationship between physical nuclear volume and ploidy level in malignant melanomas, and to analyse the heterogeneity of these two parameters among primary and corresponding secondary tumours. Unbiased stereological estimates of nuclear volume can...

  3. Intralesional and metastatic heterogeneity in malignant melanomas demonstrated by stereologic estimates of nuclear volume

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Erlandsen, M

    1990-01-01

    Regional variability of nuclear 3-dimensional size can be estimated objectively using point-sampled intercepts obtained from different, defined zones within individual neoplasms. In the present study, stereologic estimates of the volume-weighted mean nuclear volume, nuclear vv, within peripheral...... melanomas showed large interindividual variation. This finding emphasizes that unbiased estimates of nuclear vv are robust to regional heterogeneity of nuclear volume and thus suitable for purposes of objective, quantitative malignancy grading of melanomas....

  4. Assessment of left ventricular function and mass by MR imaging: a stereological study based on the systematic slice sampling procedure.

    Science.gov (United States)

    Mazonakis, Michalis; Sahin, Bunyamin; Pagonidis, Konstantin; Damilakis, John

    2011-06-01

    The aim of this study was to combine the stereological technique with magnetic resonance (MR) imaging data for the volumetric and functional analysis of the left ventricle (LV). Cardiac MR examinations were performed in 13 consecutive subjects with known or suspected coronary artery disease. The end-diastolic volume (EDV), end-systolic volume, ejection fraction (EF), and mass were estimated by stereology using the entire slice set depicting LV and systematic sampling intensities of 1/2 and 1/3 that provided samples with every second and third slice, respectively. The repeatability of stereology was evaluated. Stereological assessments were compared with the reference values derived by manually tracing the endocardial and epicardial contours on MR images. Stereological EDV and EF estimations obtained by the 1/3 systematic sampling scheme were significantly different from those by manual delineation (P sampling intensity of 1/2 (P > .05). For these stereological approaches, a high correlation (r(2) = 0.80-0.93) and clinically acceptable limits of agreement were found with the reference method. Stereological estimations obtained by both sample sizes presented comparable coefficient of variation values of 2.9-5.8%. The mean time for stereological measurements on the entire slice set was 3.4 ± 0.6 minutes and it was reduced to 2.5 ± 0.5 minutes with the 1/2 systematic sampling scheme. Stereological analysis on systematic samples of MR slices generated by the 1/2 sampling intensity provided efficient and quick assessment of LV volumes, function, and mass. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  5. Some new, simple and efficient stereological methods and their use in pathological research and diagnosis

    DEFF Research Database (Denmark)

    Gundersen, H J; Bendtsen, T F; Korbo, L

    1988-01-01

    Stereology is a set of simple and efficient methods for quantitation of three-dimensional microscopic structures which is specifically tuned to provide reliable data from sections. Within the last few years, a number of new methods has been developed which are of special interest to pathologists...... are invariably simple and easy....

  6. Application of stereological methods to estimate post-mortem brain surface area using 3T MRI

    DEFF Research Database (Denmark)

    Furlong, Carolyn; García-Fiñana, Marta; Puddephat, Michael

    2013-01-01

    The Cavalieri and Vertical Sections methods of design based stereology were applied in combination with 3 tesla (i.e. 3T) Magnetic Resonance Imaging (MRI) to estimate cortical and subcortical volume, area of the pial surface, area of the grey-white matter boundary, and thickness of the cerebral...

  7. Computer-assisted stereology and automated image analysis for quantification of tumor infiltrating lymphocytes in colon cancer.

    Science.gov (United States)

    Eriksen, Ann C; Andersen, Johnnie B; Kristensson, Martin; dePont Christensen, René; Hansen, Torben F; Kjær-Frifeldt, Sanne; Sørensen, Flemming B

    2017-08-29

    Precise prognostic and predictive variables allowing improved post-operative treatment stratification are missing in patients treated for stage II colon cancer (CC). Investigation of tumor infiltrating lymphocytes (TILs) may be rewarding, but the lack of a standardized analytic technique is a major concern. Manual stereological counting is considered the gold standard, but digital pathology with image analysis is preferred due to time efficiency. The purpose of this study was to compare manual stereological estimates of TILs with automatic counts obtained by image analysis, and at the same time investigate the heterogeneity of TILs. From 43 patients treated for stage II CC in 2002 three paraffin embedded, tumor containing tissue blocks were selected one of them representing the deepest invasive tumor front. Serial sections from each of the 129 blocks were immunohistochemically stained for CD3 and CD8, and the slides were scanned. Stereological estimates of the numerical density and area fraction of TILs were obtained using the computer-assisted newCAST stereology system. For the image analysis approach an app-based algorithm was developed using Visiopharm Integrator System software. For both methods the tumor areas of interest (invasive front and central area) were manually delineated by the observer. Based on all sections, the Spearman's correlation coefficients for density estimates varied from 0.9457 to 0.9638 (p heterogeneity, intra-class correlation coefficients (ICC) for CD3+ TILs varied from 0.615 to 0.746 in the central area, and from 0.686 to 0.746 in the invasive area. ICC for CD8+ TILs varied from 0.724 to 0.775 in the central area, and from 0.746 to 0.765 in the invasive area. Exact objective and time efficient estimates of numerical densities and area fractions of CD3+ and CD8+ TILs in stage II colon cancer can be obtained by image analysis and are highly correlated to the corresponding estimates obtained by the gold standard based on stereology

  8. Newsletter '76 in stereology

    International Nuclear Information System (INIS)

    Ondracek, G.

    1976-08-01

    The present newsletter on stereology deals with a brief outlook about stereological problems to be solved in the future, compares definitions in pattern recognition and stereology and exposes the main notions of mathematical morphology used in quantitative metallography. This includes the description of the main stereological equations relating the parameters describing the dimensional features to the parameters measured in plane sections as well as a special type of equation for practical uses by which the average fiber length in composite materials can be determined. In this context the methods of particle shape descriptions have been summarized and reviewed and an example is given, how particle size and shape distributions can be measured statistically by automatic feature analysis of morphometric sections. - The introduction of stereological microstructural parameters into microstructure - property equations opens the way to calculate the materials properties by a stereological microstructure analysis and extends the possibilities of the common microstructural quality control. This is demonstrated for WC-Co hard metals. (orig./GSC) [de

  9. Stereological estimates of nuclear volume in squamous cell carcinoma of the uterine cervix and its precursors

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bichel, P; Jakobsen, A

    1991-01-01

    Using modern stereology, this study was carried out to obtain base-line data concerning three-dimensional, mean nuclear size in precancerous and invasive lesions of the uterine cervix. Unbiased estimates of the volume-weighted mean nuclear volume (nuclear vv) were obtained by point-sampling of nu......Using modern stereology, this study was carried out to obtain base-line data concerning three-dimensional, mean nuclear size in precancerous and invasive lesions of the uterine cervix. Unbiased estimates of the volume-weighted mean nuclear volume (nuclear vv) were obtained by point......-sampling of nuclear intercepts in 51 pre-treatment biopsies from patients with invasive squamous cell carcinomas (SCC). Vertical sections from 27 specimens with cervical intraepithelial neoplasia (CIN) grades I through III were also investigated, along with 10 CIN III associated with microinvasion (CIN III + M......). On average, nuclear vv was larger in SCC than in CIN III and CIN III + M together (2 P = 8.9 . 10(-5). A conspicuous overlap of nuclear vv existed between all investigated lesional groups. The reproducibility of estimates of nuclear vv in biopsies with SCC was acceptable (r = 0.85 and r = 0.84 in intra...

  10. Stereological estimation of the mean and variance of nuclear volume from vertical sections

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt

    1991-01-01

    The application of assumption-free, unbiased stereological techniques for estimation of the volume-weighted mean nuclear volume, nuclear vv, from vertical sections of benign and malignant nuclear aggregates in melanocytic skin tumours is described. Combining sampling of nuclei with uniform...... probability in a physical disector and Cavalieri's direct estimator of volume, the unbiased, number-weighted mean nuclear volume, nuclear vN, of the same benign and malignant nuclear populations is also estimated. Having obtained estimates of nuclear volume in both the volume- and number distribution...... to the larger malignant nuclei. Finally, the variance in the volume distribution of nuclear volume is estimated by shape-independent estimates of the volume-weighted second moment of the nuclear volume, vv2, using both a manual and a computer-assisted approach. The working procedure for the description of 3-D...

  11. Stereological estimation of the mean and variance of nuclear volume from vertical sections

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt

    1991-01-01

    The application of assumption-free, unbiased stereological techniques for estimation of the volume-weighted mean nuclear volume, nuclear vv, from vertical sections of benign and malignant nuclear aggregates in melanocytic skin tumours is described. Combining sampling of nuclei with uniform...... probability in a physical disector and Cavalieri's direct estimator of volume, the unbiased, number-weighted mean nuclear volume, nuclear vN, of the same benign and malignant nuclear populations is also estimated. Having obtained estimates of nuclear volume in both the volume- and number distribution...... of volume, a detailed investigation of nuclear size variability is possible. Benign and malignant nuclear populations show approximately the same relative variability with regard to nuclear volume, and the presented data are compatible with a simple size transformation from the smaller benign nuclei...

  12. Estimation of fetal volume by magnetic resonance imaging and stereology.

    Science.gov (United States)

    Roberts, N; Garden, A S; Cruz-Orive, L M; Whitehouse, G H; Edwards, R H

    1994-11-01

    The current methods to monitor fetal growth in utero are based on ultrasound image measurements which, lacking a proper sampling methodology, may be biased to unknown degrees. The Cavalieri method of stereology guarantees the accurate estimation of the volume of an arbitrary object from a few systematic sections. Non-invasive scanning methods, and magnetic resonance imaging (MRI) in particular, are valuable tools to provide the necessary sections, and therefore offer interesting possibilities for unbiased quantification. This paper describes how to estimate fetal volume in utero with a coefficient of error of less than 5% in less than 5 min, from three or four properly sampled MRI scans. MRI was chosen because it does not use ionizing radiations on the one hand, and it offers a good image quality on the other. The impact of potential sources of bias such as fetal motion, chemical shift and partial voluming artefacts is discussed. The methods are illustrated on four subjects monitored between weeks 28 and 40 of gestation.

  13. STEREOLOGICAL ANALYSIS OF SHAPE

    Directory of Open Access Journals (Sweden)

    Asger Hobolth

    2011-05-01

    Full Text Available This paper concerns the problem of making stereological inference about the shape variability in a population of spatial particles. Under rotational invariance the shape variability can be estimated from central planar sections through the particles. A simple, but flexible, parametric model for rotation invariant spatial particles is suggested. It is shown how the parameters of the model can be estimated from observations on central sections. The corresponding model for planar particles is also discussed in some detail.

  14. Intralesional and metastatic heterogeneity in malignant melanomas demonstrated by stereologic estimates of nuclear volume

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Erlandsen, M

    1990-01-01

    Regional variability of nuclear 3-dimensional size can be estimated objectively using point-sampled intercepts obtained from different, defined zones within individual neoplasms. In the present study, stereologic estimates of the volume-weighted mean nuclear volume, nuclear vv, within peripheral...... on average larger in the peripheral zones of primary melanomas, than nuclear vv in central zones (2p = 6.7 x 10(-4), whereas no zonal differences were demonstrated in metastatic lesions (2p = 0.21). A marked intraindividual variation was demonstrated between primary and corresponding secondary melanomas (2p...... melanomas showed large interindividual variation. This finding emphasizes that unbiased estimates of nuclear vv are robust to regional heterogeneity of nuclear volume and thus suitable for purposes of objective, quantitative malignancy grading of melanomas....

  15. A novel approach to non-biased systematic random sampling: a stereologic estimate of Purkinje cells in the human cerebellum.

    Science.gov (United States)

    Agashiwala, Rajiv M; Louis, Elan D; Hof, Patrick R; Perl, Daniel P

    2008-10-21

    Non-biased systematic sampling using the principles of stereology provides accurate quantitative estimates of objects within neuroanatomic structures. However, the basic principles of stereology are not optimally suited for counting objects that selectively exist within a limited but complex and convoluted portion of the sample, such as occurs when counting cerebellar Purkinje cells. In an effort to quantify Purkinje cells in association with certain neurodegenerative disorders, we developed a new method for stereologic sampling of the cerebellar cortex, involving calculating the volume of the cerebellar tissues, identifying and isolating the Purkinje cell layer and using this information to extrapolate non-biased systematic sampling data to estimate the total number of Purkinje cells in the tissues. Using this approach, we counted Purkinje cells in the right cerebella of four human male control specimens, aged 41, 67, 70 and 84 years, and estimated the total Purkinje cell number for the four entire cerebella to be 27.03, 19.74, 20.44 and 22.03 million cells, respectively. The precision of the method is seen when comparing the density of the cells within the tissue: 266,274, 173,166, 167,603 and 183,575 cells/cm3, respectively. Prior literature documents Purkinje cell counts ranging from 14.8 to 30.5 million cells. These data demonstrate the accuracy of our approach. Our novel approach, which offers an improvement over previous methodologies, is of value for quantitative work of this nature. This approach could be applied to morphometric studies of other similarly complex tissues as well.

  16. Blood capillary length estimation from three-dimensional microscopic data by image analysis and stereology.

    Science.gov (United States)

    Kubínová, Lucie; Mao, Xiao Wen; Janáček, Jiří

    2013-08-01

    Studies of the capillary bed characterized by its length or length density are relevant in many biomedical studies. A reliable assessment of capillary length from two-dimensional (2D), thin histological sections is a rather difficult task as it requires physical cutting of such sections in randomized directions. This is often technically demanding, inefficient, or outright impossible. However, if 3D image data of the microscopic structure under investigation are available, methods of length estimation that do not require randomized physical cutting of sections may be applied. Two different rat brain regions were optically sliced by confocal microscopy and resulting 3D images processed by three types of capillary length estimation methods: (1) stereological methods based on a computer generation of isotropic uniform random virtual test probes in 3D, either in the form of spatial grids of virtual "slicer" planes or spherical probes; (2) automatic method employing a digital version of the Crofton relations using the Euler characteristic of planar sections of the binary image; and (3) interactive "tracer" method for length measurement based on a manual delineation in 3D of the axes of capillary segments. The presented methods were compared in terms of their practical applicability, efficiency, and precision.

  17. Newsletter '77 in stereology

    International Nuclear Information System (INIS)

    Ondracek, G.

    1977-12-01

    There are three groups of contributions forming the present Newsletter in Stereology which are such of theoretical type, stereological activities in bio-sciences and quatitative image analysis in materials science. The report is introduced by two papers treating theoretical problems as the definition of particle size based on the total curvature and the definition of pattern recognition categories. It than follows a summarizing description and comparison of alternative techniques used to measure and conclude stereological parameters in bio-sciences. The discussion includes the sample preparation, semi- and complete automatic measuring procedures as well as the computation of primary data. The biological part ends by considering the use of those quantitative microscopical methods to investigate and classify foreign compounds inside the human liver stereologically. The materials science part reports about tests made on steel specimens to evaluate the accuracy of automatic microstructural analyses and about the use of image 'erosion' and 'dilatation' to measure microstructural parameters automatically. The last subject is part of a serie on morphology in quantitative metallography started in the previous Newsletter '76. The last paper on materials sciences considers the use of stereology and microstructural analysis in respect to a quality control, choosing WC-Co hardmetals as an example, where stereologically defined microstructural parameters do not serve only to describe microstructures quantitatively but also provide a usefull tool to determine properties indirectly. (orig.) [de

  18. Stereological estimates of nuclear volume in the prognostic evaluation of primary flat carcinoma in situ of the urinary bladder

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Jacobsen, F

    1991-01-01

    Primary, flat carcinoma in situ of the urinary bladder is rare and its behaviour is unpredictable. The aim of this retrospective study was to obtain base-line data and investigate the prognostic value of unbiased, stereological estimates of the volume-weighted mean nuclear volume, nuclear vv, in ...

  19. Confocal stereology: an efficient tool for measurement of microscopic structures

    Czech Academy of Sciences Publication Activity Database

    Kubínová, Lucie; Janáček, Jiří

    2015-01-01

    Roč. 360, č. 1 (2015), s. 13-28 ISSN 0302-766X R&D Projects: GA MŠk(CZ) LH13028 Institutional support: RVO:67985823 Keywords : 3-D images * confocal microscopy * geometrical characteristics * spatial probes * stereology Subject RIV: EA - Cell Biology Impact factor: 2.948, year: 2015

  20. Unbiased stereological estimation of d-dimensional volume in Rn from an isotropic random slice through a fixed point

    DEFF Research Database (Denmark)

    Jensen, Eva B. Vedel; Kiêu, K

    1994-01-01

    Unbiased stereological estimators of d-dimensional volume in R(n) are derived, based on information from an isotropic random r-slice through a specified point. The content of the slice can be subsampled by means of a spatial grid. The estimators depend only on spatial distances. As a fundamental ...... lemma, an explicit formula for the probability that an isotropic random r-slice in R(n) through 0 hits a fixed point in R(n) is given....

  1. Design-based stereological estimation of the total number of cardiac myocytes in histological sections

    DEFF Research Database (Denmark)

    Brüel, Annemarie; Nyengaard, Jens Randel

    2005-01-01

    in LM sections using design-based stereology. MATERIALS AND METHODS: From formalin-fixed left rat ventricles (LV) isotropic uniformly random sections were cut. The total number of myocyte nuclei per LV was estimated using the optical disector. Two-microm-thick serial paraffin sections were stained......BACKGROUND: Counting the total number of cardiac myocytes has not previously been possible in ordinary histological sections using light microscopy (LM) due to difficulties in defining the myocyte borders properly. AIM: To describe a method by which the total number of cardiac myocytes is estimated...... with antibodies against cadherin and type IV collagen to visualise the intercalated discs and the myocyte membranes, respectively. Using the physical disector in "local vertical windows" of the serial sections, the average number of nuclei per myocyte was estimated.RESULTS: The total number of myocyte nuclei...

  2. Stereological estimation of nuclear volume in benign and malignant melanocytic lesions of the skin. Inter- and intraobserver variability of malignancy grading

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Ottosen, P D

    1991-01-01

    The volume-weighted, mean nuclear volume (nuclear vv) may be estimated without any assumptions regarding nuclear shape using modern stereological techniques. As a part of an investigation concerning the prospects of nuclear vv for classification and malignancy grading of cutaneous melanocytic tum...

  3. EARLY HISTORY OF GEOMETRIC PROBABILITY AND STEREOLOGY

    Directory of Open Access Journals (Sweden)

    Magdalena Hykšová

    2012-03-01

    Full Text Available The paper provides an account of the history of geometric probability and stereology from the time of Newton to the early 20th century. It depicts the development of two parallel ways: on one hand, the theory of geometric probability was formed with minor attention paid to other applications than those concerning spatial chance games. On the other hand, practical rules of the estimation of area or volume fraction and other characteristics, easily deducible from geometric probability theory, were proposed without the knowledge of this branch. A special attention is paid to the paper of J.-É. Barbier published in 1860, which contained the fundamental stereological formulas, but remained almost unnoticed both by mathematicians and practicians.

  4. Unbiased stereologic techniques for practical use in diagnostic histopathology

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt

    1995-01-01

    Grading of malignancy by the examination of morphologic and cytologic details in histologic sections from malignant neoplasms is based exclusively on qualitative features, associated with significant subjectivity, and thus rather poor reproducibility. The traditional way of malignancy grading may...... by introducing quantitative techniques in the histopathologic discipline of malignancy grading. Unbiased stereologic methods, especially based on measurements of nuclear three-dimensional mean size, have during the last decade proved their value in this regard. In this survey, the methods are reviewed regarding...... the basic technique involved, sampling, efficiency, and reproducibility. Various types of cancers, where stereologic grading of malignancy has been used, are reviewed and discussed with regard to the development of a new objective and reproducible basis for carrying out prognosis-related malignancy grading...

  5. Cerebral atrophy in AIDS: a stereological study

    DEFF Research Database (Denmark)

    Oster, S; Christoffersen, P; Gundersen, H J

    1993-01-01

    Stereological estimates of mean volumes, surface areas, and cortical thicknesses were obtained on formalin-fixed brains from 19 men with AIDS and 19 controls. Volumes of neocortex, white matter, central brain nuclei, ventricles and archicortex were estimated using point counting and Cavalieri......'s unbiased principle for volume estimation. In AIDS, the mean volume of neocortex was reduced by 11%, and that of the central brain nuclei by 18%. Mean ventricular volume was increased by 55%. Mean neocortical thickness was reduced by 12%. The mean volume of white matter was reduced by 13%. The findings in 6...

  6. Comparison of quantitative estimation of intracerebral hemorrhage and infarct volumes after thromboembolism in an embolic stroke model

    DEFF Research Database (Denmark)

    Eriksen, Nina; Rasmussen, Rune Skovgaard; Overgaard, Karsten

    2014-01-01

    . Group 1 was treated with saline, and group 2 was treated with 20 mg/kg recombinant tissue plasminogen activator to promote intracerebral hemorrhages. Stereology, semiautomated computer estimation, and manual erythrocyte counting were used to test the precision and efficiency of determining the size...... measurements, the stereological method was the most efficient and advantageous. CONCLUSIONS: We found that stereology was the superior method for quantification of hemorrhagic volume, especially for rodent petechial bleeding, which is otherwise difficult to measure. Our results suggest the possibility...

  7. AUTOMATIC ESTIMATION OF SIZE PARAMETERS USING VERIFIED COMPUTERIZED STEREOANALYSIS

    Directory of Open Access Journals (Sweden)

    Peter R Mouton

    2011-05-01

    Full Text Available State-of-the-art computerized stereology systems combine high-resolution video microscopy and hardwaresoftware integration with stereological methods to assist users in quantifying multidimensional parameters of importance to biomedical research, including volume, surface area, length, number, their variation and spatial distribution. The requirement for constant interactions between a trained, non-expert user and the targeted features of interest currently limits the throughput efficiency of these systems. To address this issue we developed a novel approach for automatic stereological analysis of 2-D images, Verified Computerized Stereoanalysis (VCS. The VCS approach minimizes the need for user interactions with high contrast [high signal-to-noise ratio (S:N] biological objects of interest. Performance testing of the VCS approach confirmed dramatic increases in the efficiency of total object volume (size estimation, without a loss of accuracy or precision compared to conventional computerized stereology. The broad application of high efficiency VCS to high-contrast biological objects on tissue sections could reduce labor costs, enhance hypothesis testing, and accelerate the progress of biomedical research focused on improvements in health and the management of disease.

  8. A review of state-of-the-art stereology for better quantitative 3D morphology in cardiac research.

    Science.gov (United States)

    Mühlfeld, Christian; Nyengaard, Jens Randel; Mayhew, Terry M

    2010-01-01

    The aim of stereological methods in biomedical research is to obtain quantitative information about three-dimensional (3D) features of tissues, cells, or organelles from two-dimensional physical or optical sections. With immunogold labeling, stereology can even be used for the quantitative analysis of the distribution of molecules within tissues and cells. Nowadays, a large number of design-based stereological methods offer an efficient quantitative approach to intriguing questions in cardiac research, such as "Is there a significant loss of cardiomyocytes during progression from ventricular hypertrophy to heart failure?" or "Does a specific treatment reduce the degree of fibrosis in the heart?" Nevertheless, the use of stereological methods in cardiac research is rare. The present review article demonstrates how some of the potential pitfalls in quantitative microscopy may be avoided. To this end, we outline the concepts of design-based stereology and illustrate their practical applications to a wide range of biological questions in cardiac research. We hope that the present article will stimulate researchers in cardiac research to incorporate design-based stereology into their study designs, thus promoting an unbiased quantitative 3D microscopy.

  9. Systematic versus random sampling in stereological studies.

    Science.gov (United States)

    West, Mark J

    2012-12-01

    The sampling that takes place at all levels of an experimental design must be random if the estimate is to be unbiased in a statistical sense. There are two fundamental ways by which one can make a random sample of the sections and positions to be probed on the sections. Using a card-sampling analogy, one can pick any card at all out of a deck of cards. This is referred to as independent random sampling because the sampling of any one card is made without reference to the position of the other cards. The other approach to obtaining a random sample would be to pick a card within a set number of cards and others at equal intervals within the deck. Systematic sampling along one axis of many biological structures is more efficient than random sampling, because most biological structures are not randomly organized. This article discusses the merits of systematic versus random sampling in stereological studies.

  10. Digital immunohistochemistry wizard: image analysis-assisted stereology tool to produce reference data set for calibration and quality control.

    Science.gov (United States)

    Plancoulaine, Benoît; Laurinaviciene, Aida; Meskauskas, Raimundas; Baltrusaityte, Indra; Besusparis, Justinas; Herlin, Paulette; Laurinavicius, Arvydas

    2014-01-01

    Digital image analysis (DIA) enables better reproducibility of immunohistochemistry (IHC) studies. Nevertheless, accuracy of the DIA methods needs to be ensured, demanding production of reference data sets. We have reported on methodology to calibrate DIA for Ki67 IHC in breast cancer tissue based on reference data obtained by stereology grid count. To produce the reference data more efficiently, we propose digital IHC wizard generating initial cell marks to be verified by experts. Digital images of proliferation marker Ki67 IHC from 158 patients (one tissue microarray spot per patient) with an invasive ductal carcinoma of the breast were used. Manual data (mD) were obtained by marking Ki67-positive and negative tumour cells, using a stereological method for 2D object enumeration. DIA was used as an initial step in stereology grid count to generate the digital data (dD) marks by Aperio Genie and Nuclear algorithms. The dD were collected into XML files from the DIA markup images and overlaid on the original spots along with the stereology grid. The expert correction of the dD marks resulted in corrected data (cD). The percentages of Ki67 positive tumour cells per spot in the mD, dD, and cD sets were compared by single linear regression analysis. Efficiency of cD production was estimated based on manual editing effort. The percentage of Ki67-positive tumor cells was in very good agreement in the mD, dD, and cD sets: regression of cD from dD (R2=0.92) reflects the impact of the expert editing the dD as well as accuracy of the DIA used; regression of the cD from the mD (R2=0.94) represents the consistency of the DIA-assisted ground truth (cD) with the manual procedure. Nevertheless, the accuracy of detection of individual tumour cells was much lower: in average, 18 and 219 marks per spot were edited due to the Genie and Nuclear algorithm errors, respectively. The DIA-assisted cD production in our experiment saved approximately 2/3 of manual marking. Digital IHC wizard

  11. [Simulation and data analysis of stereological modeling based on virtual slices].

    Science.gov (United States)

    Wang, Hao; Shen, Hong; Bai, Xiao-yan

    2008-05-01

    To establish a computer-assisted stereological model for simulating the process of slice section and evaluate the relationship between section surface and estimated three-dimensional structure. The model was designed by mathematic method as a win32 software based on the MFC using Microsoft visual studio as IDE for simulating the infinite process of sections and analysis of the data derived from the model. The linearity of the fitting of the model was evaluated by comparison with the traditional formula. The win32 software based on this algorithm allowed random sectioning of the particles distributed randomly in an ideal virtual cube. The stereological parameters showed very high throughput (>94.5% and 92%) in homogeneity and independence tests. The data of density, shape and size of the section were tested to conform to normal distribution. The output of the model and that from the image analysis system showed statistical correlation and consistency. The algorithm we described can be used for evaluating the stereologic parameters of the structure of tissue slices.

  12. DNA level and stereologic estimates of nuclear volume in squamous cell carcinomas of the uterine cervix. A comparative study with analysis of prognostic impact

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bichel, P; Jakobsen, A

    1992-01-01

    Grading of malignancy in squamous cell carcinomas of the uterine cervix is based on qualitative, morphologic examination and suffers from poor reproducibility. Using modern stereology, unbiased estimates of the three-dimensional, volume-weighted mean nuclear volume (nuclear vv), were obtained...... in pretreatment biopsies from 51 patients treated for cervical cancer in clinical Stages I through III (mean age of 56 years, follow-up period greater than 5 years). In addition, conventional, two-dimensional morphometric estimates of nuclear and mitotic features were obtained. DNA indices (DI) were estimated...

  13. DNA level and stereologic estimates of nuclear volume in squamous cell carcinomas of the uterine cervix. A comparative study with analysis of prognostic impact

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bichel, P; Jakobsen, A

    1992-01-01

    Grading of malignancy in squamous cell carcinomas of the uterine cervix is based on qualitative, morphologic examination and suffers from poor reproducibility. Using modern stereology, unbiased estimates of the three-dimensional, volume-weighted mean nuclear volume (nuclear vv), were obtained...... in pretreatment biopsies from 51 patients treated for cervical cancer in clinical Stages I through III (mean age of 56 years, follow-up period greater than 5 years). In addition, conventional, two-dimensional morphometric estimates of nuclear and mitotic features were obtained. DNA indices (DI) were estimated...... carcinoma of the uterine cervix....

  14. Automatic sampling for unbiased and efficient stereological estimation using the proportionator in biological studies

    DEFF Research Database (Denmark)

    Gardi, Jonathan Eyal; Nyengaard, Jens Randel; Gundersen, Hans Jørgen Gottlieb

    2008-01-01

    Quantification of tissue properties is improved using the general proportionator sampling and estimation procedure: automatic image analysis and non-uniform sampling with probability proportional to size (PPS). The complete region of interest is partitioned into fields of view, and every field...... of view is given a weight (the size) proportional to the total amount of requested image analysis features in it. The fields of view sampled with known probabilities proportional to individual weight are the only ones seen by the observer who provides the correct count. Even though the image analysis...... cerebellum, total number of orexin positive neurons in transgenic mice brain, and estimating the absolute area and the areal fraction of β islet cells in dog pancreas.  The proportionator was at least eight times more efficient (precision and time combined) than traditional computer controlled sampling....

  15. Stereological estimation of nuclear volume and other quantitative histopathological parameters in the prognostic evaluation of supraglottic laryngeal squamous cell carcinoma

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bennedbaek, O; Pilgaard, J

    1989-01-01

    The aim of this study was to investigate various approaches to the grading of malignancy in pre-treatment biopsies from patients with supraglottic laryngeal squamous cell carcinoma. The prospects of objective malignancy grading based on stereological estimation of the volume-weighted mean nuclear...... volume, nuclear Vv, and nuclear volume fraction, Vv(nuc/tis), along with morphometrical 2-dimensional estimation of nuclear density index, NI, and mitotic activity index, MI, were investigated and compared with the current morphological, multifactorial grading system. The reproducibility among two...... observers of the latter was poor in the material which consisted of 35 biopsy specimens. Unbiased estimates of nuclear Vv were on the average 385 microns3 (CV = 0.44), with more than 90% of the associated variance attributable to differences in nuclear Vv among individual lesions. Nuclear Vv was positively...

  16. Current automated 3D cell detection methods are not a suitable replacement for manual stereologic cell counting

    Directory of Open Access Journals (Sweden)

    Christoph eSchmitz

    2014-05-01

    Full Text Available Stereologic cell counting has had a major impact on the field of neuroscience. A major bottleneck in stereologic cell counting is that the user must manually decide whether or not each cell is counted according to three-dimensional (3D stereologic counting rules by visual inspection within hundreds of microscopic fields-of-view per investigated brain or brain region. Reliance on visual inspection forces stereologic cell counting to be very labor-intensive and time-consuming, and is the main reason why biased, non-stereologic two-dimensional (2D cell counting approaches have remained in widespread use. We present an evaluation of the performance of modern automated cell detection and segmentation algorithms as a potential alternative to the manual approach in stereologic cell counting. The image data used in this study were 3D microscopic images of thick brain tissue sections prepared with a variety of commonly used nuclear and cytoplasmic stains. The evaluation compared the numbers and locations of cells identified unambiguously and counted exhaustively by an expert observer with those found by three automated 3D cell detection algorithms: nuclei segmentation from the FARSIGHT toolkit, nuclei segmentation by 3D multiple level set methods, and the 3D object counter plug-in for ImageJ. Of these methods, FARSIGHT performed best, with true-positive detection rates between 38–99% and false-positive rates from 3.6–82%. The results demonstrate that the current automated methods suffer from lower detection rates and higher false-positive rates than are acceptable for obtaining valid estimates of cell numbers. Thus, at present, stereologic cell counting with manual decision for object inclusion according to unbiased stereologic counting rules remains the only adequate method for unbiased cell quantification in histologic tissue sections.

  17. Stereological estimation of surface area and barrier thickness of fish gills in vertical sections.

    Science.gov (United States)

    Da Costa, Oscar T F; Pedretti, Ana Carolina E; Schmitz, Anke; Perry, Steven F; Fernandes, Marisa N

    2007-01-01

    Previous morphometric methods for estimation of the volume of components, surface area and thickness of the diffusion barrier in fish gills have taken advantage of the highly ordered structure of these organs for sampling and surface area estimations, whereas the thickness of the diffusion barrier has been measured orthogonally on perpendicularly sectioned material at subjectively selected sites. Although intuitively logical, these procedures do not have a demonstrated mathematical basis, do not involve random sampling and measurement techniques, and are not applicable to the gills of all fish. The present stereological methods apply the principles of surface area estimation in vertical uniform random sections to the gills of the Brazilian teleost Arapaima gigas. The tissue was taken from the entire gill apparatus of the right-hand or left-hand side (selected at random) of the fish by systematic random sampling and embedded in glycol methacrylate for light microscopy. Arches from the other side were embedded in Epoxy resin. Reference volume was estimated by the Cavalieri method in the same vertical sections that were used for surface density and volume density measurements. The harmonic mean barrier thickness of the water-blood diffusion barrier was calculated from measurements taken along randomly selected orientation lines that were sine-weighted relative to the vertical axis. The values thus obtained for the anatomical diffusion factor (surface area divided by barrier thickness) compare favourably with those obtained for other sluggish fish using existing methods.

  18. Practical Stereology Applications for the Pathologist.

    Science.gov (United States)

    Brown, Danielle L

    2017-05-01

    Qualitative histopathology is the gold standard for routine examination of morphological tissue changes in the regulatory or academic environment. The human eye is exceptional for pattern recognition but often cannot detect small changes in quantity. In cases where detection of subtle quantitative changes is critical, more sensitive methods are required. Two-dimensional histomorphometry can provide additional quantitative information and is quite useful in many cases. However, the provided data may not be referent to the entire tissue and, as such, it makes several assumptions, which are sources of bias. In contrast, stereology is design based rather than assumption based and uses stringent sampling methods to obtain accurate and precise 3-dimensional information using geometrical and statistical principles. Recent advances in technology have made stereology more approachable and practical for the pathologist in both regulatory and academic environments. This review introduces pathologists to the basic principles of stereology and walks the reader through some real-world examples for the application of these principles in the workplace.

  19. Introduction into integral geometry and stereology

    DEFF Research Database (Denmark)

    Kiderlen, Markus

    Statistics and Random Fields and is a self-containing introduction into integral geometry and its applications in stereology. The most important integral geometric tools for stereological applications are kinematic formulas and results of Blaschke-Petkantschin type. Therefore, Crofton's formula......This text is the extended version of two talks held at the Summer Academy Stochastic Geometry, Spatial Statistics and Random Fields in the Soellerhaus, Germany, in September 2009. It forms (with slight modifications) a chapter of the Springer lecture notes Lectures on Stochastic Geometry, Spatial...

  20. Stereological estimation of nuclear volume and other quantitative histopathological parameters in the prognostic evaluation of supraglottic laryngeal squamous cell carcinoma

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bennedbaek, O; Pilgaard, J

    1989-01-01

    The aim of this study was to investigate various approaches to the grading of malignancy in pre-treatment biopsies from patients with supraglottic laryngeal squamous cell carcinoma. The prospects of objective malignancy grading based on stereological estimation of the volume-weighted mean nuclear...... observers of the latter was poor in the material which consisted of 35 biopsy specimens. Unbiased estimates of nuclear Vv were on the average 385 microns3 (CV = 0.44), with more than 90% of the associated variance attributable to differences in nuclear Vv among individual lesions. Nuclear Vv was positively....... None of the investigated categorical and quantitative parameters (cutoff points = means) reached the level of significance with respect to prognostic value. However, nuclear Vv showed the best information concerning survival (2p = 0.08), and this estimator offers optimal features for objective...

  1. PROBES, POPULATIONS, SAMPLES, MEASUREMENTS AND RELATIONS IN STEREOLOGY

    Directory of Open Access Journals (Sweden)

    Robert T Dehoff

    2011-05-01

    Full Text Available This summary paper provides an overview of the content of stereology. The typical problem at hand centers around some three dimensional object that has an internal structure that determines its function, performance, or response. To understand and quantify the geometry of that structure it is necessary to probe it with geometric entities: points, lines, planes volumes, etc. Meaningful results are obtained only if the set of probes chosen for use in the assessment is drawn uniformly from the population of such probes for the structure as a whole. This requires an understanding of the population of each kind of probe. Interaction of the probes with the structure produce geometric events which are the focus of stereological measurements. In almost all applications the measurement that is made is a simple count of the number of these events. Rigorous application of these requirements for sample design produce unbiased estimates of geometric properties of features in the structure no matter how complex are the features or what their arrangement in space. It is this assumption-free characteristic of the methodology that makes it a powerful tool for characterizing the internal structure of three dimensional objects.

  2. Practical application of stereological methods in experimental kidney animal models.

    Science.gov (United States)

    Fernández García, María Teresa; Núñez Martínez, Paula; García de la Fuente, Vanessa; Sánchez Pitiot, Marta; Muñiz Salgueiro, María Del Carmen; Perillán Méndez, Carmen; Argüelles Luis, Juan; Astudillo González, Aurora

    The kidneys are vital organs responsible for excretion, fluid and electrolyte balance and hormone production. The nephrons are the kidney's functional and structural units. The number, size and distribution of the nephron components contain relevant information on renal function. Stereology is a branch of morphometry that applies mathematical principles to obtain three-dimensional information from serial, parallel and equidistant two-dimensional microscopic sections. Because of the complexity of stereological studies and the lack of scientific literature on the subject, the aim of this paper is to clearly explain, through animal models, the basic concepts of stereology and how to calculate the main kidney stereological parameters that can be applied in future experimental studies. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  3. Evaluation of FITC-induced atopic dermatitis-like disease in NC/Nga mice and BALB/c mice using computer-assisted stereological toolbox, a computer-aided morphometric system

    DEFF Research Database (Denmark)

    Hvid, Malene; Jensen, Helene Kofoed; Deleuran, Bent

    2009-01-01

    Stereological Toolbox as a stereological method, the mice were sensitized to FITC and the histological efficiency of disease induction with regard to inflammation and CD4+ and CD8+ lymphocytes, in addition to mast cells, was evaluated. The method was validated by comparison to a conventional semiquantitative...

  4. Blood Capillary Length Estimation from Three-Dimensional Microscopic Data by Image Analysis and Stereology

    Czech Academy of Sciences Publication Activity Database

    Kubínová, Lucie; Mao, X. W.; Janáček, Jiří

    2013-01-01

    Roč. 19, č. 4 (2013), s. 898-906 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) ME09010; GA MŠk(CZ) LH13028; GA ČR(CZ) GAP108/11/0794 Institutional research plan: CEZ:AV0Z5011922 Institutional support: RVO:67985823 Keywords : capillaries * confocal microscopy * image analysis * length * rat brain * stereology Subject RIV: EA - Cell Biology Impact factor: 1.757, year: 2013

  5. Stereology as a tool to assess reproduction strategy and fecundity of teleost fishes

    DEFF Research Database (Denmark)

    Bucholtz, Rikke Hagstrøm

    methods to assess fecundity and reproductive strategies. The strength of the stereological method being that, in combination with conventional histological analysis, quantification of all oocyte categories is possible, as well as registration of qualitative characteristics relating to spawning history...... of oocyte dynamics in fish and were successfully implemented in herring ovaries for quantification of both oocyte numbers and sizes as well as total volume fraction of atretic oocytes, introducing a negligible error to the total variance of estimates. The histological nature of the stereological methods...... facilitated a ready validation of maturity data, distinguishing first time spawners from repeat spawners, as well as a ready recognition of ongoing oocyte recruitment in early maturity stages, early stage atresia, POFs and residual eggs. Analyzing a sample of females all collected during a short time frame...

  6. STEREOLOGY FROM ONE OF ALL THE POSSIBLE ANGLES

    Directory of Open Access Journals (Sweden)

    Leszek Wojnar

    2011-05-01

    Full Text Available Relation between image analysis and stereology is discussed in terms of different fields of applications, especially materials science, biology and medicine. Some long-term tendencies observed as well as possible future trends are discussed. The need of a wider use of image analysis techniques including ma1hematical morphology in any field of science is demons1rated. Simultaneously, the significance of stereological background in automatic quantification of1he investigated structures is confirmed.

  7. Brain Volume Estimation Enhancement by Morphological Image Processing Tools

    Directory of Open Access Journals (Sweden)

    Zeinali R.

    2017-12-01

    Full Text Available Background: Volume estimation of brain is important for many neurological applications. It is necessary in measuring brain growth and changes in brain in normal/ abnormal patients. Thus, accurate brain volume measurement is very important. Magnetic resonance imaging (MRI is the method of choice for volume quantification due to excellent levels of image resolution and between-tissue contrast. Stereology method is a good method for estimating volume but it requires to segment enough MRI slices and have a good resolution. In this study, it is desired to enhance stereology method for volume estimation of brain using less MRI slices with less resolution. Methods: In this study, a program for calculating volume using stereology method has been introduced. After morphologic method, dilation was applied and the stereology method enhanced. For the evaluation of this method, we used T1-wighted MR images from digital phantom in BrainWeb which had ground truth. Results: The volume of 20 normal brain extracted from BrainWeb, was calculated. The volumes of white matter, gray matter and cerebrospinal fluid with given dimension were estimated correctly. Volume calculation from Stereology method in different cases was made. In three cases, Root Mean Square Error (RMSE was measured. Case I with T=5, d=5, Case II with T=10, D=10 and Case III with T=20, d=20 (T=slice thickness, d=resolution as stereology parameters. By comparing these results of two methods, it is obvious that RMSE values for our proposed method are smaller than Stereology method. Conclusion: Using morphological operation, dilation allows to enhance the estimation volume method, Stereology. In the case with less MRI slices and less test points, this method works much better compared to Stereology method.

  8. Stereological estimates of nuclear volume in normal germ cells and carcinoma in situ of the human testis

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Müller, J

    1990-01-01

    Carcinoma in situ of the testis may appear many years prior to the development of an invasive tumour. Using point-sampled intercepts, base-line data concerning unbiased stereological estimates of the volume-weighted mean nuclear volume (nuclear vV) were obtained in 50 retrospective serial...... testicular biopsies from 10 patients with carcinoma in situ. All but two patients eventually developed an invasive growth. Testicular biopsies from 10 normal adult individuals and five prepubertal boys were included as controls. Nuclear vV in testicular carcinoma in situ was significantly larger than...... that of morphologically normal spermatogonia (2P = 1.0 x 10(-19)), with only minor overlap. Normal spermatogonia from controls had, on average, smaller nuclear vV than morphologically normal spermatogonia in biopsies with ipsi- or contra-lateral carcinoma in situ (2P = 5.2 x 10(-3)). No difference in nuclear vV was found...

  9. Using the Optical Fractionator to Estimate Total Cell Numbers in the Normal and Abnormal Developing Human Forebrain

    DEFF Research Database (Denmark)

    Larsen, Karen B

    2017-01-01

    abnormal development. Furthermore, many studies of brain cell numbers have employed biased counting methods, whereas innovations in stereology during the past 20-30 years enable reliable and efficient estimates of cell numbers. However, estimates of cell volumes and densities in fetal brain samples...

  10. STEREOLOGICAL ESTIMATION OF ITO CELLS FROM RAT LIVER USING THE OPTICAL FRACTIONATOR - A PRELIMINARY REPORT

    Directory of Open Access Journals (Sweden)

    Ricardo Marcos

    2011-05-01

    Full Text Available In the last two decades, much light has been shed on hepatic fibrosis, and the activation / proliferation of Ito cells (IC emerged to play a central role. Therefore, it is essential to have solid quantitative data in nonpathological statuses; yet, this data is scarce and confined to "number per area" or semiquantitative information. Moreover, the supposed heterogeneous distribution of IC in the hepatic lobule was never analysed with design-based (unbiased stereology. In the present study, the total number (N of IC in rat liver was estimated for the first time, by combining immunocytochemistry with the optical fractionator. Quantification was extended to the hepatocytes, to disclose the IC index, an often-used ratio in hepatology. Systematic uniform random liver sections were obtained from male Wistar rats (n = 3, and immunostained against glial fibrillary acidic protein (GFAP, a known specific marker for hepatic IC. For the first time, these were marked against GFAP in thick (30 μm paraffin sections. The estimated N of IC was 224E06; with a coefficient of error of 0.04 or 0.06, depending on the particular equation used (based on the so-called "quadratic approximation". The IC index was 91 IC/1000 hepatocytes. Concerning the lobular heterogeneity, it was proved the liver harbours a larger total number of periportal IC and hepatocytes.

  11. DNA level and stereologic estimates of nuclear volume in squamous cell carcinomas of the uterine cervix. A comparative study with analysis of prognostic impact

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Bichel, P; Jakobsen, A

    1992-01-01

    Grading of malignancy in squamous cell carcinomas of the uterine cervix is based on qualitative, morphologic examination and suffers from poor reproducibility. Using modern stereology, unbiased estimates of the three-dimensional, volume-weighted mean nuclear volume (nuclear vv), were obtained...... in pretreatment biopsies from 51 patients treated for cervical cancer in clinical Stages I through III (mean age of 56 years, follow-up period greater than 5 years). In addition, conventional, two-dimensional morphometric estimates of nuclear and mitotic features were obtained. DNA indices (DI) were estimated...... of nuclear vv were only of marginal prognostic significance (2P = 0.07). However, Cox multivariate regression analysis showed independent prognostic value of patient age and nuclear vv along with clinical stage and DI. All other investigated variables were rejected from the model. A prognostic index...

  12. Stereological analysis of nuclear volume in recurrent meningiomas

    DEFF Research Database (Denmark)

    Madsen, C; Schrøder, H D

    1994-01-01

    A stereological estimation of nuclear volume in recurrent and non-recurrent meningiomas was made. The aim was to investigate whether this method could discriminate between these two groups. We found that the mean nuclear volumes in recurrent meningiomas were all larger at debut than in any...... of the control tumors. The mean nuclear volume of the individual recurrent tumors appeared to change with time, showing a tendency to diminish. A relationship between large nuclear volume at presentation and number of or time interval between recurrences was not found. We conclude that measurement of mean...... nuclear volume in meningiomas might help identify a group at risk of recurrence....

  13. A handheld support system to facilitate stereological measurements and mapping of branching structures

    DEFF Research Database (Denmark)

    Gardi, J.E.; Wulfsohn, Dvora-Laiô; Nyengaard, J.R.

    2007-01-01

    specifications, software and Graphical User Interface (GUI) development, functionality and application of the handheld system using four examples: (1) sampling monkey lung bronchioles for estimation of diameter and wall thickness (2) sampling rat kidney for estimating number of arteries and arterioles......‘BranchSampler' is a system for computer-assisted manual stereology written for handheld devices running Windows CE. The system has been designed specifically to streamline data collection and optimize sampling of tree-like branching structures, with particular aims of reducing user errors, saving...

  14. Stereological estimate of the total number of neurons in spinal segment D9 of the red-eared turtle

    DEFF Research Database (Denmark)

    Walløe, Solveig; Nissen, Ulla Vig; Berg, Rune W

    2011-01-01

    The red-eared turtle is an important animal model for investigating the neural activity in the spinal circuit that generates motor behavior. However, basic anatomical features, including the number of neurons in the spinal segments involved, are unknown. In the present study, we estimate the total...... number of neurons in segment D9 of the spinal cord in the red-eared turtle (Trachemys scripta elegans) using stereological cell counting methods. In transverse spinal cord sections stained with modified Giemsa, motoneurons (MNs), interneurons (INs), and non-neuronal cells were distinguished according...... to location and morphology. Each cell type was then counted separately using an optical disector with the cell nucleus as counting item. The number of cells in segment D9 was as follows (mean ± SE): MNs, 2049 ± 74; INs, 16,135 ± 316; non-neuronal cells, 47,504 ± 478 (n = 6). These results provide the first...

  15. Stereological, functional and molecular studies of development and disease : a collection of published works 1981 to 2013

    OpenAIRE

    Bertram, John F.

    2016-01-01

    The unifying theme throughout this Doctorate of Science thesis is the development, refinement and utilisation of stereological techniques to study tissue structures in development, and in adult health and disease. Stereology is the discipline based on geometric probability theory that enables us to quantify structures in three-dimensional space. Stereological techniques are often applied in material science as well as biomedical science. When applied to histology and pathology, stereology can...

  16. Changes in total cell numbers of the basal ganglia in patients with multiple system atrophy - A stereological study

    DEFF Research Database (Denmark)

    Salvesen, Lisette; Ullerup, Birgitte H; Sunay, Fatma B

    2014-01-01

    Total numbers of neurons, oligodendrocytes, astrocytes, and microglia in the basal ganglia and red nucleus were estimated in brains from 11 patients with multiple system atrophy (MSA) and 11 age- and gender-matched control subjects with unbiased stereological methods. Compared to the control...

  17. Assessing the Effects of Fibrosis on Lung Function by Light Microscopy-Coupled Stereology

    DEFF Research Database (Denmark)

    Pilecki, Bartosz; Sørensen, Grith Lykke

    2017-01-01

    Pulmonary diseases such as fibrosis are characterized by structural abnormalities that lead to impairment of proper lung function. Stereological analysis of serial tissue sections allows detection and quantitation of subtle changes in lung architecture. Here, we describe a stereology-based method...

  18. Quantitative analysis of the renal aging in rats. Stereological study

    OpenAIRE

    Melchioretto, Eduardo Felippe; Zeni, Marcelo; Veronez, Djanira Aparecida da Luz; Martins Filho, Eduardo Lopes; Fraga, Rogério de

    2016-01-01

    ABSTRACT PURPOSE: To evaluate the renal function and the renal histological alterations through the stereology and morphometrics in rats submitted to the natural process of aging. METHODS: Seventy two Wistar rats, divided in six groups. Each group was sacrificed in a different age: 3, 6, 9, 12, 18 and 24 months. It was performed right nephrectomy, stereological and morphometric analysis of the renal tissue (renal volume and weight, density of volume (Vv[glom]) and numerical density (Nv[glo...

  19. STEREOLOGICAL ANALYSIS OF THE COCHLEAR NUCLEI OF MONKEY (MACACA FASCICULARIS AFTER DEAFFERENTATION

    Directory of Open Access Journals (Sweden)

    Ana M Insausti

    2011-05-01

    Full Text Available The cochlear nuclei (CN in the brainstem receive the input signals from the inner ear through the cochlear nerve, and transmit these signals to higher auditory centres. A variety of lesions of the cochlear nerve cause deafness. As reported in the literature, artificial removal of auditive input, or 'deafferentation', induces structural alterations in the CN. The purpose of this study was to estimate a number of relevant stereological parameters of the CN in control and deafferented Macaca fascicularis monkeys.

  20. Stereological estimates of nuclear volume and other quantitative variables in supratentorial brain tumors. Practical technique and use in prognostic evaluation

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Braendgaard, H; Chistiansen, A O

    1991-01-01

    The use of morphometry and modern stereology in malignancy grading of brain tumors is only poorly investigated. The aim of this study was to present these quantitative methods. A retrospective feasibility study of 46 patients with supratentorial brain tumors was carried out to demonstrate...... the practical technique. The continuous variables were correlated with the subjective, qualitative WHO classification of brain tumors, and the prognostic value of the parameters was assessed. Well differentiated astrocytomas (n = 14) had smaller estimates of the volume-weighted mean nuclear volume and mean...... nuclear profile area, than those of anaplastic astrocytomas (n = 13) (2p = 3.1.10(-3) and 2p = 4.8.10(-3), respectively). No differences were seen between the latter type of tumor and glioblastomas (n = 19). The nuclear index was of the same magnitude in all three tumor types, whereas the mitotic index...

  1. Variance estimation for generalized Cavalieri estimators

    OpenAIRE

    Johanna Ziegel; Eva B. Vedel Jensen; Karl-Anton Dorph-Petersen

    2011-01-01

    The precision of stereological estimators based on systematic sampling is of great practical importance. This paper presents methods of data-based variance estimation for generalized Cavalieri estimators where errors in sampling positions may occur. Variance estimators are derived under perturbed systematic sampling, systematic sampling with cumulative errors and systematic sampling with random dropouts. Copyright 2011, Oxford University Press.

  2. ON ESTIMATION AND HYPOTHESIS TESTING OF THE GRAIN SIZE DISTRIBUTION BY THE SALTYKOV METHOD

    Directory of Open Access Journals (Sweden)

    Yuri Gulbin

    2011-05-01

    Full Text Available The paper considers the problem of validity of unfolding the grain size distribution with the back-substitution method. Due to the ill-conditioned nature of unfolding matrices, it is necessary to evaluate the accuracy and precision of parameter estimation and to verify the possibility of expected grain size distribution testing on the basis of intersection size histogram data. In order to review these questions, the computer modeling was used to compare size distributions obtained stereologically with those possessed by three-dimensional model aggregates of grains with a specified shape and random size. Results of simulations are reported and ways of improving the conventional stereological techniques are suggested. It is shown that new improvements in estimating and testing procedures enable grain size distributions to be unfolded more efficiently.

  3. Practicable methods for histological section thickness measurement in quantitative stereological analyses.

    Science.gov (United States)

    Matenaers, Cyrill; Popper, Bastian; Rieger, Alexandra; Wanke, Rüdiger; Blutke, Andreas

    2018-01-01

    of SR to efficiently provide accurate section thickness measurements as a prerequisite for reliable estimates of dependent quantitative stereological parameters.

  4. PLASTICITY OF SKELETAL MUSCLE STUDIED BY STEREOLOGY

    Directory of Open Access Journals (Sweden)

    Ida Eržen

    2011-05-01

    Full Text Available The present contribution provides an overview of stereological methods applied in the skeletal muscle research at the Institute of Anatomy of the Medical Faculty in Ljubljana. Interested in skeletal muscle plasticity we studied three different topics: (i expression of myosin heavy chain isoforms in slow and fast muscles under experimental conditions, (ii frequency of satellite cells in young and old human and rat muscles and (iii capillary supply of rat fast and slow muscles. We analysed the expression of myosin heavy chain isoforms within slow rat soleus and fast extensor digitorum longus muscles after (i homotopic and heterotopic transplantation of both muscles, (ii low frequency electrical stimulation of the fast muscle and (iii transposition of the fast nerve to the slow muscle. The models applied were able to turn the fast muscle into a completely slow muscle, but not vice versa. One of the indicators for the regenerative potential of skeletal muscles is its satellite cell pool. The estimated parameters, number of satellite cells per unit fibre length, corrected to the reference sarcomere length (Nsc/Lfib and number of satellite cells per number of nuclei (myonuclei and satellite cell nuclei (Nsc/Nnucl indicated that the frequency of M-cadherin stained satellite cells declines in healthy old human and rat muscles compared to young muscles. To access differences in capillary densities among slow and fast muscles and slow and fast muscle fibres, we have introduced Slicer and Fakir methods, and tested them on predominantly slow and fast rat muscles. Discussing three different topics that require different approach, the present paper reflects the three decades of the development of stereological methods: 2D analysis by simple point counting in the 70's, the disector in the 80's and virtual spatial probes in the 90's. In all methods the interactive computer assisted approach was utilised.

  5. Unbiased Stereologic Estimation of the Spatial Distribution of Paget’s Disease in the Human Temporal Bone

    DEFF Research Database (Denmark)

    Bloch, Sune Land; Sørensen, Mads Sølvsten

    2014-01-01

    remodeling around the inner ear space and to compare it with that of otosclerosis in a contemporary context of temporal bone dynamics. MATERIALS AND METHODS: From the temporal bone collection of Massachusetts Eye and Ear Infirmary, 15 of 29 temporal bones with Paget's disease were selected to obtain...... an independent sample. All volume distributions were obtained along the normal axis of capsular bone remodeling activity by the use of vector-based stereology. RESULTS: Pagetic bone remodeling was distributed centrifugally around the inner ear space at the individual and the general level. This pattern...

  6. Comparison of automated brain volumetry methods with stereology in children aged 2 to 3 years

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Kristina N. [University Children' s Hospital of Zurich, Center for MR Research, Zurich (Switzerland); University Children' s Hospital, Pediatric Cardiology, Zurich (Switzerland); Latal, Beatrice [University Children' s Hospital, Child Development Center, Zurich (Switzerland); University Children' s Hospital, Children' s Research Center, Zurich (Switzerland); Knirsch, Walter [University Children' s Hospital, Pediatric Cardiology, Zurich (Switzerland); University Children' s Hospital, Children' s Research Center, Zurich (Switzerland); Scheer, Ianina [University Children' s Hospital, Department for Diagnostic Neuroradiology, Zurich (Switzerland); Rhein, Michael von [University Children' s Hospital, Child Development Center, Zurich (Switzerland); Reich, Bettina; Bauer, Juergen; Gummel, Kerstin [Justus-Liebig University, Pediatric Heart Center, University Hospital Giessen, Giessen (Germany); Roberts, Neil [University of Edinburgh, Clinical Research and Imaging Centre (CRIC), The Queens Medical Research Institute (QMRI), Edinburgh (United Kingdom); O' Gorman Tuura, Ruth [University Children' s Hospital of Zurich, Center for MR Research, Zurich (Switzerland); University Children' s Hospital, Children' s Research Center, Zurich (Switzerland)

    2016-09-15

    The accurate and precise measurement of brain volumes in young children is important for early identification of children with reduced brain volumes and an increased risk for neurodevelopmental impairment. Brain volumes can be measured from cerebral MRI (cMRI), but most neuroimaging tools used for cerebral segmentation and volumetry were developed for use in adults and have not been validated in infants or young children. Here, we investigate the feasibility and accuracy of three automated software methods (i.e., SPM, FSL, and FreeSurfer) for brain volumetry in young children and compare the measures with corresponding volumes obtained using the Cavalieri method of modern design stereology. Cerebral MRI data were collected from 21 children with a complex congenital heart disease (CHD) before Fontan procedure, at a median age of 27 months (range 20.9-42.4 months). Data were segmented with SPM, FSL, and FreeSurfer, and total intracranial volume (ICV) and total brain volume (TBV) were compared with corresponding measures obtained using the Cavalieri method. Agreement between the estimated brain volumes (ICV and TBV) relative to the gold standard stereological volumes was strongest for FreeSurfer (p < 0.001) and moderate for SPM segment (ICV p = 0.05; TBV p = 0.006). No significant association was evident between ICV and TBV obtained using SPM NewSegment and FSL FAST and the corresponding stereological volumes. FreeSurfer provides an accurate method for measuring brain volumes in young children, even in the presence of structural brain abnormalities. (orig.)

  7. Comparison of automated brain volumetry methods with stereology in children aged 2 to 3 years

    International Nuclear Information System (INIS)

    Mayer, Kristina N.; Latal, Beatrice; Knirsch, Walter; Scheer, Ianina; Rhein, Michael von; Reich, Bettina; Bauer, Juergen; Gummel, Kerstin; Roberts, Neil; O'Gorman Tuura, Ruth

    2016-01-01

    The accurate and precise measurement of brain volumes in young children is important for early identification of children with reduced brain volumes and an increased risk for neurodevelopmental impairment. Brain volumes can be measured from cerebral MRI (cMRI), but most neuroimaging tools used for cerebral segmentation and volumetry were developed for use in adults and have not been validated in infants or young children. Here, we investigate the feasibility and accuracy of three automated software methods (i.e., SPM, FSL, and FreeSurfer) for brain volumetry in young children and compare the measures with corresponding volumes obtained using the Cavalieri method of modern design stereology. Cerebral MRI data were collected from 21 children with a complex congenital heart disease (CHD) before Fontan procedure, at a median age of 27 months (range 20.9-42.4 months). Data were segmented with SPM, FSL, and FreeSurfer, and total intracranial volume (ICV) and total brain volume (TBV) were compared with corresponding measures obtained using the Cavalieri method. Agreement between the estimated brain volumes (ICV and TBV) relative to the gold standard stereological volumes was strongest for FreeSurfer (p < 0.001) and moderate for SPM segment (ICV p = 0.05; TBV p = 0.006). No significant association was evident between ICV and TBV obtained using SPM NewSegment and FSL FAST and the corresponding stereological volumes. FreeSurfer provides an accurate method for measuring brain volumes in young children, even in the presence of structural brain abnormalities. (orig.)

  8. Stereological quantification of mast cells in human synovium

    DEFF Research Database (Denmark)

    Damsgaard, T E; Sørensen, Flemming Brandt; Herlin, T

    1999-01-01

    Mast cells participate in both the acute allergic reaction as well as in chronic inflammatory diseases. Earlier studies have revealed divergent results regarding the quantification of mast cells in the human synovium. The aim of the present study was therefore to quantify these cells in the human...... synovium, using stereological techniques. Different methods of staining and quantification have previously been used for mast cell quantification in human synovium. Stereological techniques provide precise and unbiased information on the number of cell profiles in two-dimensional tissue sections of......, in this case, human synovium. In 10 patients suffering from osteoarthritis a median of 3.6 mast cells/mm2 synovial membrane was found. The total number of cells (synoviocytes, fibroblasts, lymphocytes, leukocytes) present was 395.9 cells/mm2 (median). The mast cells constituted 0.8% of all the cell profiles...

  9. Unbiased stereologic techniques for practical use in diagnostic histopathology

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt

    1995-01-01

    by introducing quantitative techniques in the histopathologic discipline of malignancy grading. Unbiased stereologic methods, especially based on measurements of nuclear three-dimensional mean size, have during the last decade proved their value in this regard. In this survey, the methods are reviewed regarding......Grading of malignancy by the examination of morphologic and cytologic details in histologic sections from malignant neoplasms is based exclusively on qualitative features, associated with significant subjectivity, and thus rather poor reproducibility. The traditional way of malignancy grading may...... of solid tumors. This new, unbiased attitude to malignancy grading is associated with excellent virtues, which ultimately may help the clinician in the choice of optimal treatment of the individual patient suffering from cancer. Stereologic methods are not solely applicable to the field of malignancy...

  10. Stereology of human myometrium in pregnancy: influence of maternal body mass index and age.

    LENUS (Irish Health Repository)

    Sweeney, Eva M

    2013-04-01

    Knowledge of the stereology of human myometrium in pregnancy is limited. Uterine contractile performance may be altered in association with maternal obesity and advanced maternal age. The aim of this study was to investigate the stereology of human myometrium in pregnancy, and to evaluate a potential influence of maternal body mass index (BMI) and age.

  11. Prediction of prognosis in patients with epidural hematoma by a new stereological method

    International Nuclear Information System (INIS)

    Kalkan, E.; Cander, B.; Gul, M.; Girisgin, S.; Karabagli, H.; Sahin, B.

    2007-01-01

    Epidural hematoma (EH) is a serious clinical event observed in 2% of head trauma patients. Studies regarding the effects of epidural hematoma volume (EHV) on prognosis are not sufficient. In this study, we applied the volume fraction approach of the stereological method to estimate the hematoma to brain volume fraction (HBVF), and investigated the relation between the HBVF and prognosis. Fifty-nine EH patients (46 male and 13 female subjects, with average age of 21 years) admitted to the emergency clinic were included. The HBVF was estimated on the printed films of cranial computed tomography scans. For this purpose, common point counting grids were superimposed over the scan frames. According to the clinical results, patients were divided into three groups as complete recovery (43), disability (8) and exitus (8). The HBVF was compared with the clinical results. HBVF was determined as 4.6% in the patients with recovery, 8.1% in disability, and 7.6% in exitus patients. The HBVF values were lowest in recovery patients, and the difference between the recovery and the other two groups was statistically significant (p=0.007). However, there was no statistically significant difference in HBVF between disability and exitus patients (p>0.05). In conclusion, the HBVF can be an important tool to determine prognosis, and it can be measured using the volume fraction approach of stereological methods as developed in the present study. (author)

  12. Histological versus stereological methods applied at spermatogonia during normal human development

    DEFF Research Database (Denmark)

    Cortes, D

    1990-01-01

    The number of spermatogonia per tubular transverse section (S/T), and the percentage of seminiferous tubulus containing spermatogonia (the fertility index (FI] were measured in 40 pairs of normal autopsy testes aged 28 weeks of gestation-40 years. S/T and FI showed similar changes during the whole...... period, and were minimal between 1 and 4 years. The number of spermatogonia per testis (S/testis) and the number of spermatogonia per cm3 testis tissue (S/cm3) were estimated by stereological methods in the same testes. S/T and FI respectively were significantly correlated both to S/testis and S/cm3. So...

  13. Stereology application in the investigation of physical and mechanical properties of porous materials

    International Nuclear Information System (INIS)

    Cytermann, Richard.

    1979-04-01

    The sintering of carbonyl nickel powders has been studied through stereology (quantitative microscopy) associated with different physical and mechanical measurements. This study demonstrated that a set of stereological parameters, such as porosity, grain size, mean pore volume ..., was necessary to characterize porous parts with the same porosity obtained through different ways. On the one hand, stereology permitted to elucidate powder shape and speed of pressure rising influence on the compacting process. On the other hand, the study of physical and mechanical properties related to their microstructure led to distinguish: properties such as elasticity modulus independant of compacting pressure, sintering temperature and powder shape. Their evolution has been characterized through contiguity coefficient; properties such as tensile strength dependant of sintering parameters. Their characterization required the simultaneous measurement of porosity mean pore volume, shape factor and grain size [fr

  14. Quantitative analysis of the renal aging in rats. Stereological study.

    Science.gov (United States)

    Melchioretto, Eduardo Felippe; Zeni, Marcelo; Veronez, Djanira Aparecida da Luz; Martins, Eduardo Lopes; Fraga, Rogério de

    2016-05-01

    To evaluate the renal function and the renal histological alterations through the stereology and morphometrics in rats submitted to the natural process of aging. Seventy two Wistar rats, divided in six groups. Each group was sacrificed in a different age: 3, 6, 9, 12, 18 and 24 months. It was performed right nephrectomy, stereological and morphometric analysis of the renal tissue (renal volume and weight, density of volume (Vv[glom]) and numerical density (Nv[glom]) of the renal glomeruli and average glomerular volume (Vol[glom])) and also it was evaluated the renal function for the dosage of serum creatinine and urea. There was significant decrease of the renal function in the oldest rats. The renal volume presented gradual increase during the development of the rats with the biggest values registered in the group of animals at 12 months of age and significant progressive decrease in older animals. Vv[glom] presented statistically significant gradual reduction between the groups and the Nv[glom] also decreased significantly. The renal function proved to be inferior in senile rats when compared to the young rats. The morphometric and stereological analysis evidenced renal atrophy, gradual reduction of the volume density and numerical density of the renal glomeruli associated to the aging process.

  15. Light scattering in porous materials: Geometrical optics and stereological approach

    International Nuclear Information System (INIS)

    Malinka, Aleksey V.

    2014-01-01

    Porous material has been considered from the point of view of stereology (geometrical statistics), as a two-phase random mixture of solid material and air. Considered are the materials having the refractive index with the real part that differs notably from unit and the imaginary part much less than unit. Light scattering in such materials has been described using geometrical optics. These two – the geometrical optics laws and the stereological approach – allow one to obtain the inherent optical properties of such a porous material, which are basic in the radiative transfer theory: the photon survival probability, the scattering phase function, and the polarization properties (Mueller matrix). In this work these characteristics are expressed through the refractive index of the material and the random chord length distribution. The obtained results are compared with the traditional approach, modeling the porous material as a pack of particles of different shapes. - Highlights: • Porous material has been considered from the point of view of stereology. • Properties of a two-phase random mixture of solid material and air are considered. • Light scattering in such materials has been described using geometrical optics. • The inherent optical properties of such a porous material have been obtained

  16. Stereological estimation of ovarian volume and number of follicles in low dose of Vitex agnus castus treated mice

    OpenAIRE

    HAMIDIAN, Gholamreza; YAHYAVI, Fariba

    2014-01-01

    Vitex agnus castus (VAC) has been proven to have a wide range of biological activities. It is commonly used in the treatment of menstrual disorders resulting from corpus luteum deficiency, including premenstrual symptoms and spasmodic dysmenorrheal, for certain menopausal conditions, and for insufficient lactation. The aim of this study was to investigate the effects of low dose of VAC essential oil on ovarian volume and oocyte number in mice by stereological technique. In this study 10 young...

  17. Morphometric changes in the spinal cord during prenatal life: a stereological study in sheep.

    Science.gov (United States)

    Sadeghinezhad, Javad; Zadsar, Narges; Hasanzadeh, Beal

    2018-03-01

    This study describes the volumetric changes in the spinal cord during prenatal life in sheep using quantitative stereological methods. Twenty healthy sheep fetuses were included in the present study, divided into four groups representing 9-11, 12-14, 15-17, and 18-20 weeks of gestation. In each group, the spinal cord was dissected out and sampled according to the unbiased systematic random sampling method then used for stereological estimations. The total volume of spinal cord, volume of gray matter (GM), volume of white matter (WM), ratio of GM volume to WM volume, and volume of central canal (CC) were estimated in the whole spinal cord and its various regions using Cavalieri's principle. The total volume of the spinal cord increased 8 times from week 9 to week 20. The cervical region showed the greatest (9.7 times) and the sacral region the least (6.3 times) volumetric change. The CC volume of the whole spinal cord increased 5.8 times from week 9 to week 20. The cervical region developed faster (8.2 times) and the thoracic region slower (4.4 times) than the total spinal cord. During development, the volume ratio of GM to WM decreased from lower toward upper regions. The greatest volume changes occurred mostly in weeks 9-11 and 12-14. The cervical region showed the greatest volume changes in comparison with other regions of the spinal cord.

  18. Assessment of in vivo MR imaging compared to physical sections in vitro-A quantitative study of brain volumes using stereology

    DEFF Research Database (Denmark)

    Jelsing, Jacob; Rostrup, Egill; Markenroth, Karin

    2005-01-01

    The object of the present study was to compare stereological estimates of brain volumes obtained in vivo by magnetic resonance imaging (MRI) to corresponding volumes from physical sections in vitro. Brains of ten domestic pigs were imaged using a 3-T scanner. The volumes of different brain....... However, although intraobserver difference of MRI estimates was acceptable, the interobserver difference was not. A statistical highly significant difference of 11-41% was observed between observers for volume estimates of all compartments considered. The study demonstrates that quantitative MRI...

  19. Using biased image analysis for improving unbiased stereological number estimation - a pilot simulation study of the smooth fractionator

    DEFF Research Database (Denmark)

    Gardi, Jonathan Eyal; Nyengaard, Jens Randel; Gundersen, Hans Jørgen Gottlieb

    2006-01-01

    uniformly random sampling design and the ordinary simple random sampling design. The smooth protocol is performed using biased information from crude (but fully automatic) image analysis of the fields of view. The different design paradigms are compared using simulation in three different cell distributions......The smooth fractionator was introduced in 2002. The combination of a smoothing protocol with a computer-aided stereology tool provides better precision and a lighter workload. This study uses simulation to compare fractionator sampling based on the smooth design, the commonly used systematic...

  20. Confocal stereology and image analysis: methods for estimating geometrical characteristics of cells and tissues from three-dimensional confocal images

    Czech Academy of Sciences Publication Activity Database

    Kubínová, Lucie; Janáček, Jiří; Karen, Petr; Radochová, Barbora; Difato, Francesco; Krekule, Ivan

    2004-01-01

    Roč. 53, Suppl.1 (2004), s. S47-S55 ISSN 0862-8408 R&D Projects: GA ČR GA304/01/0257; GA ČR GA310/02/1470; GA AV ČR KJB6011309; GA AV ČR KJB5039302 Grant - others:SI - CZ(CZ) KONTAKT 001/2001 Institutional research plan: CEZ:AV0Z5011922 Keywords : confocal microscopy * image analysis * stereology Subject RIV: EA - Cell Biology Impact factor: 1.140, year: 2004

  1. Stereological Cell Morphometry In Right Atrium Myocardium Of Primates

    Science.gov (United States)

    Mandarim-De-Lacerda, Carlos A...; Hureau, Jacques

    1986-07-01

    The mechanism by which the cardiac impulse is propagated in normal hearts from its origin in the sinus node to the atrio-ventricular node has not been agreed on fully. We studied the "internodal posterior tract" through the crista terminalis by light microscopy and stereological morphometry. The hearts of 12 Papio cynocephalus were perfused , after sacrifice,with phosphate-buffered formol saline. The regions of the crista terminalis (CT), interatrial septum (IAS), atrioventricular bundle (AVB) and interventricular septum (IVS) were cut off and embedded in paraplast and sectioned (10 4m). The multipurpose test system M 42 was superimposed over the photomicrographs (1,890 points test, ESR = 2%) to the stereological computing. The quantitative results show that the cells from CT were more closely relationed with IAS cells than others cells (IVS and AVB cells). This results are not a morphological evidence to establish the specificity of the "internodal posterior tract". The cellular arrangement and anatomical variation in CT myocardium is very important.

  2. First and second order stereology of hyaline cartilage: Application on mice femoral cartilage.

    Science.gov (United States)

    Noorafshan, Ali; Niazi, Behnam; Mohamadpour, Masoomeh; Hoseini, Leila; Hoseini, Najmeh; Owji, Ali Akbar; Rafati, Ali; Sadeghi, Yasaman; Karbalay-Doust, Saied

    2016-11-01

    Stereological techniques could be considered in research on cartilage to obtain quantitative data. The present study aimed to explain application of the first- and second-order stereological methods on articular cartilage of mice and the methods applied on the mice exposed to cadmium (Cd). The distal femoral articular cartilage of BALB/c mice (control and Cd-treated) was removed. Then, volume and surface area of the cartilage and number of chondrocytes were estimated using Cavalieri and optical dissector techniques on isotropic uniform random sections. Pair-correlation function [g(r)] and cross-correlation function were calculated to express the spatial arrangement of chondrocytes-chondrocytes and chondrocytes-matrix (chondrocyte clustering/dispersing), respectively. The mean±standard deviation of the cartilage volume, surface area, and thickness were 1.4±0.1mm 3 , 26.2±5.4mm 2 , and 52.8±6.7μm, respectively. Besides, the mean number of chondrocytes was 680±200 (×10 3 ). The cartilage volume, cartilage surface area, and number of chondrocytes were respectively reduced by 25%, 27%, and 27% in the Cd-treated mice in comparison to the control animals (pcartilage components carried potential advantages for investigating the cartilage in different joint conditions. Chondrocyte clustering/dispersing and cellularity can be evaluated in cartilage assessment in normal or abnormal situations. Copyright © 2016 Elsevier GmbH. All rights reserved.

  3. Stereological brain volume changes in post-weaned socially isolated rats

    DEFF Research Database (Denmark)

    Fabricius, Katrine; Helboe, Lone; Steiniger-Brach, Björn

    2010-01-01

    Lister Hooded rats isolated from postnatal day 25 for 15 weeks. We observed the expected gender differences in total brain volume with males having larger brains than females. Further, we found that isolated males had significantly smaller brains than group-housed controls and larger lateral ventricles...... have evaluated the neuroanatomical changes in this animal model in comparison to changes seen in schizophrenia. In this study, we applied stereological volume estimates to evaluate the total brain, the ventricular system, and the pyramidal and granular cell layers of the hippocampus in male and female...... than controls. However, this was not seen in female rats. Isolated males had a significant smaller hippocampus, dentate gyrus and CA2/3 where isolated females had a significant smaller CA1 compared to controls. Thus, our results indicate that long-term isolation of male rats leads to neuroanatomical...

  4. UTILIZATION OF STEREOLOGY FOR QUANTITATIVE ANALYSIS OF PLASTIC DEFORMATION OF FORMING PIECES

    Directory of Open Access Journals (Sweden)

    Maroš Martinkovič

    2012-01-01

    Full Text Available Mechanical working leads to final properties of forming pieces, which are affected by conditions of production technology. Utilization of stereology leads to the detail analysis of three-dimensional plastic deformed material structure by different forming technologies, e.g. forging, extruding, upsetting, metal spinning, drawing etc. The microstructure of cold drawing wires was analyzed. Grain boundaries orientation was measured on the parallel section of wire with a different degree of deformation and direct axis plastic deformation was evaluated in bulk formed part. The strain of probes on their sections was obtained using stereology by measurement of degree of grain boundary orientation which was converted to deformation using model of conversion of grain boundary orientation degree to deformation.

  5. The Optical Fractionator Technique to Estimate Cell Numbers in a Rat Model of Electroconvulsive Therapy

    DEFF Research Database (Denmark)

    Olesen, Mikkel Vestergaard; Needham, Esther Kjær; Pakkenberg, Bente

    2017-01-01

    are too high to count manually, and stereology is now the technique of choice whenever estimates of three-dimensional quantities need to be extracted from measurements on two-dimensional sections. All stereological methods are in principle unbiased; however, they rely on proper knowledge about...

  6. CONDITIONS FOR EXACT CAVALIERI ESTIMATION

    Directory of Open Access Journals (Sweden)

    Mónica Tinajero-Bravo

    2014-03-01

    Full Text Available Exact Cavalieri estimation amounts to zero variance estimation of an integral with systematic observations along a sampling axis. A sufficient condition is given, both in the continuous and the discrete cases, for exact Cavalieri sampling. The conclusions suggest improvements on the current stereological application of fractionator-type sampling.

  7. STEREOLOGICAL QUANTITATION OF LEYDIG AND SERTOLI CELLS IN THE TESTIS FROM YOUNG AND OLD MEN

    Directory of Open Access Journals (Sweden)

    Peter M Petersen

    2011-05-01

    Full Text Available One of the newer stereological methods, the optical fractionator, was applied to the study of the effects of ageing on the human testis. The estimated total number of Sertoli and Leydig cells per testis in men younger than 30 years were 430×106 (CV = SD/mean = 0.35 and 117×106 (CV = 0.53, respectively, while in men older than 50 years the estimated total Sertoli cell number was 266×106 (CV = 0.46 and the mean Leydig cell number 83×106 (CV = 0.53. The difference between the number of Sertoli cells in men younger than 30 years compared with men older than 50 years was close to statistical significance (p = 0.052 while no differences was found in total Leydig cell number (p = 0.22.

  8. Autogenous bone graft and ePTFE membrane in the treatment of peri-implantitis. II. Stereologic and histologic observations in cynomolgus monkeys

    DEFF Research Database (Denmark)

    Schou, Søren; Holmstrup, Palle; Skovgaard, Lene Theil

    2003-01-01

    autogenous bone graft; guided bone regeneration; histology; membrane; non-human primates; oral implants; osseointegration; pathalogy; peri-implantitis; stereology; treatment......autogenous bone graft; guided bone regeneration; histology; membrane; non-human primates; oral implants; osseointegration; pathalogy; peri-implantitis; stereology; treatment...

  9. Stereological study of postnatal development in the mouse utricular macula

    DEFF Research Database (Denmark)

    Kirkegaard, Mette; Nyengaard, Jens Randel

    2005-01-01

    This study describes the morphometric changes taking place in the utricular macula of mice with ages in geometric progression from 1 to 512 days after birth. By using design-based stereological methods, the total volume and surface area of the sensory epithelium as well the total number of the ha...

  10. A new fractionator principle with varying sampling fractions: exemplified by estimation of synapse number using electron microscopy

    DEFF Research Database (Denmark)

    Witgen, Brent Marvin; Grady, M. Sean; Nyengaard, Jens Randel

    2006-01-01

    The quantification of ultrastructure has been permanently improved by the application of new stereological principles. Both precision and efficiency have been enhanced. Here we report for the first time a fractionator method that can be applied at the electron microscopy level. This new design...... the total object number using section sampling fractions based on the average thickness of sections of variable thicknesses. As an alternative, this approach estimates the correct particle section sampling probability based on an estimator of the Horvitz-Thompson type, resulting in a theoretically more...

  11. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Directory of Open Access Journals (Sweden)

    María García-Amado

    Full Text Available Cell number alterations in the amygdaloid complex (AC might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL, corticomedial and central groups, 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3 and mean cell numbers (x10(6 were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  12. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Science.gov (United States)

    García-Amado, María; Prensa, Lucía

    2012-01-01

    Cell number alterations in the amygdaloid complex (AC) might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL), corticomedial and central groups), 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3) and mean cell numbers (x10(6)) were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  13. Flexible and efficient estimating equations for variogram estimation

    KAUST Repository

    Sun, Ying; Chang, Xiaohui; Guan, Yongtao

    2018-01-01

    Variogram estimation plays a vastly important role in spatial modeling. Different methods for variogram estimation can be largely classified into least squares methods and likelihood based methods. A general framework to estimate the variogram through a set of estimating equations is proposed. This approach serves as an alternative approach to likelihood based methods and includes commonly used least squares approaches as its special cases. The proposed method is highly efficient as a low dimensional representation of the weight matrix is employed. The statistical efficiency of various estimators is explored and the lag effect is examined. An application to a hydrology dataset is also presented.

  14. Flexible and efficient estimating equations for variogram estimation

    KAUST Repository

    Sun, Ying

    2018-01-11

    Variogram estimation plays a vastly important role in spatial modeling. Different methods for variogram estimation can be largely classified into least squares methods and likelihood based methods. A general framework to estimate the variogram through a set of estimating equations is proposed. This approach serves as an alternative approach to likelihood based methods and includes commonly used least squares approaches as its special cases. The proposed method is highly efficient as a low dimensional representation of the weight matrix is employed. The statistical efficiency of various estimators is explored and the lag effect is examined. An application to a hydrology dataset is also presented.

  15. Quantifying Golgi structure using EM: combining volume-SEM and stereology for higher throughput.

    Science.gov (United States)

    Ferguson, Sophie; Steyer, Anna M; Mayhew, Terry M; Schwab, Yannick; Lucocq, John Milton

    2017-06-01

    Investigating organelles such as the Golgi complex depends increasingly on high-throughput quantitative morphological analyses from multiple experimental or genetic conditions. Light microscopy (LM) has been an effective tool for screening but fails to reveal fine details of Golgi structures such as vesicles, tubules and cisternae. Electron microscopy (EM) has sufficient resolution but traditional transmission EM (TEM) methods are slow and inefficient. Newer volume scanning EM (volume-SEM) methods now have the potential to speed up 3D analysis by automated sectioning and imaging. However, they produce large arrays of sections and/or images, which require labour-intensive 3D reconstruction for quantitation on limited cell numbers. Here, we show that the information storage, digital waste and workload involved in using volume-SEM can be reduced substantially using sampling-based stereology. Using the Golgi as an example, we describe how Golgi populations can be sensed quantitatively using single random slices and how accurate quantitative structural data on Golgi organelles of individual cells can be obtained using only 5-10 sections/images taken from a volume-SEM series (thereby sensing population parameters and cell-cell variability). The approach will be useful in techniques such as correlative LM and EM (CLEM) where small samples of cells are treated and where there may be variable responses. For Golgi study, we outline a series of stereological estimators that are suited to these analyses and suggest workflows, which have the potential to enhance the speed and relevance of data acquisition in volume-SEM.

  16. A comparison of porosity analysis using 2D stereology estimates and 3D serial sectioning for additively manufactured Ti 6Al 2Sn 4Zr 2Mo alloy

    International Nuclear Information System (INIS)

    Ganti, Satya R.; Velez, Michael A.; Geier, Brian A.; Hayes, Brian J.; Turner, Bryan J.; Jenkins, Elizabeth J.

    2017-01-01

    Porosity is a typical defect in additively manufactured (AM) parts. Such defects limit the properties and performance of AM parts, and therefore need to be characterized accurately. Current methods for characterization of defects and microstructure rely on classical stereological methods that extrapolate information from two dimensional images. The automation of serial sectioning provides an opportunity to precisely and accurately quantify porosity in three dimensions in materials. In this work, we analyzed the porosity of an additively manufactured Ti 6Al 2Sn 4Zr 2Mo sample using Robo-Met.3D "r"e"g"i"s"t"e"r"e"d, an automated serial sectioning system. Image processing for three dimensional reconstruction of the serial-sectioned two dimensional images was performed using open source image analysis software (Fiji/ImageJ, Dream.3D, Paraview). The results from this 3D serial sectioning analysis were then compared to classical 2D stereological methods (Saltykov stereological theory). We found that for this dataset, the classical 2D methods underestimated the porosity size and distributions of the larger pores; a critical attribute to fatigue behavior of the AM part. The results suggest that acquiring experimental data with equipment such as Robo-Met.3D "r"e"g"i"s"t"e"r"e"d to measure the number and size of particles such as pores in a volume irrespective of knowing their shape is a better choice.

  17. Novel efficient methods for measuring mesophyll anatomical characteristics from fresh thick sections using stereology and confocal microscopy: application on acid rain-treated Norway spruce needles

    Czech Academy of Sciences Publication Activity Database

    Albrechtová, Jana; Janáček, Jiří; Lhotáková, Zuzana; Radochová, Barbora; Kubínová, Lucie

    2007-01-01

    Roč. 58, č. 6 (2007), s. 1451-1461 ISSN 0022-0957 R&D Projects: GA AV ČR IAA5011810; GA AV ČR(CZ) IAA600110507; GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z60050516 Keywords : mesophyll * stereology * confocal microscopy Subject RIV: EA - Cell Biology Impact factor: 3.917, year: 2007

  18. Unbiased stereological methods used for the quantitative evaluation of guided bone regeneration

    DEFF Research Database (Denmark)

    Aaboe, Else Merete; Pinholt, E M; Schou, S

    1998-01-01

    The present study describes the use of unbiased stereological methods for the quantitative evaluation of the amount of regenerated bone. Using the principle of guided bone regeneration the amount of regenerated bone after placement of degradable or non-degradable membranes covering defects...

  19. Stereological quantification of lymphocytes in skin biopsies from atopic dermatitis patients

    DEFF Research Database (Denmark)

    Ellingsen, A R; Sørensen, F B; Larsen, Jytte Overgaard

    2001-01-01

    with active eczema in 8 adults with AD and from clinically normal skin from 4 of the patients. Five persons without allergy or skin disease served as controls. The mean number of lymphocytes in 4-mm skin biopsies was 469,000 and 124,000 in active eczema and in clinically normal skin, respectively. Compared......Atopic dermatitis (AD) is histologically characterized by lymphocytic infiltration of the skin and quantitative assessment is required. This study introduces stereological techniques to quantify the number of lymphocytes in skin biopsies. Four-millimetre punch biopsies were taken from skin...... with controls, the number of lymphocytes in biopsies increased by a factor of 6.8 in active eczema and a factor of 1.8 in clinically normal skin. If 20% of skin is affected by eczema the total number of lymphocytes located in the affected skin can be estimated to 1.27 x 10(10). A patient with clinically...

  20. The total number of Leydig and Sertoli cells in the testes of men across various age groups - a stereological study

    DEFF Research Database (Denmark)

    Petersen, Peter M; Seierøe, Karina; Pakkenberg, Bente

    2015-01-01

    is particularly sensitive to methodological problems. Therefore, using the optical fractionator technique and a sampling design specifically optimized for human testes, we estimated the total number of Sertoli and Leydig cells in the testes from 26 post mortem male subjects ranging in age from 16 to 80 years...... of Sertoli cells with age; no such decline was found for Leydig cells. Quantitative stereological analysis of post mortem tissue may help understand the influence of age or disease on the number of human testicular cells....

  1. Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods

    Science.gov (United States)

    Mao, Xiao W.; Archambeau, John O.; Kubinova, Lucie; Boyle, Soames; Petersen, Georgia; Grove, Roger; Nelson, G. A. (Principal Investigator)

    2003-01-01

    This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (Ppopulations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.

  2. Surface tensor estimation from linear sections

    DEFF Research Database (Denmark)

    Kousholt, Astrid; Kiderlen, Markus; Hug, Daniel

    From Crofton's formula for Minkowski tensors we derive stereological estimators of translation invariant surface tensors of convex bodies in the n-dimensional Euclidean space. The estimators are based on one-dimensional linear sections. In a design based setting we suggest three types of estimators....... These are based on isotropic uniform random lines, vertical sections, and non-isotropic random lines, respectively. Further, we derive estimators of the specific surface tensors associated with a stationary process of convex particles in the model based setting....

  3. Surface tensor estimation from linear sections

    DEFF Research Database (Denmark)

    Kousholt, Astrid; Kiderlen, Markus; Hug, Daniel

    2015-01-01

    From Crofton’s formula for Minkowski tensors we derive stereological estimators of translation invariant surface tensors of convex bodies in the n-dimensional Euclidean space. The estimators are based on one-dimensional linear sections. In a design based setting we suggest three types of estimators....... These are based on isotropic uniform random lines, vertical sections, and non-isotropic random lines, respectively. Further, we derive estimators of the specific surface tensors associated with a stationary process of convex particles in the model based setting....

  4. The changes of stage distribution of seminiferous epithelium cycle and its correlations with Leydig cell stereological parameters in aging men.

    Science.gov (United States)

    Huang, Rui; Zhu, Wei-Jie; Li, Jing; Gu, Yi-Qun

    2014-12-01

    To evaluate the changes of stage distribution of seminiferous epithelium cycle and its correlations with Leydig cell stereological parameters in aging men. Point counting method was used to analyze the stereological parameters of Leydig cells. The stage number of seminiferous epithelium cycle was calculated in the same testicular tissue samples which were used for Leydig cell stereological analysis. The aging group had shown more severe pathological changes as well as higher pathologic scores than the young group. Compared with the control group, the volume density (VV) and surface density (NA) of Leydig cells in the aging group were increased significantly. The stage number of seminiferous epithelium cycle in the aging group was decreased coincidently compared to the young group. Leydig cell Vv in the young group has a positive relationship with stages I, II, III, V and VI of seminiferous epithelium cycle, and Leydig cell NA and numerical density (NV) were positively related to stage IV. However, only the correlation between NV and stage II was found in the aging group. The stage number of seminiferous epithelium cycle was decreased in aging testes. Changes in the stage distribution in aging testes were related to the Leydig cell stereological parameters which presented as a sign of morphological changes. Copyright © 2014 Elsevier GmbH. All rights reserved.

  5. MRI volumetry of prefrontal cortex

    Science.gov (United States)

    Sheline, Yvette I.; Black, Kevin J.; Lin, Daniel Y.; Pimmel, Joseph; Wang, Po; Haller, John W.; Csernansky, John G.; Gado, Mokhtar; Walkup, Ronald K.; Brunsden, Barry S.; Vannier, Michael W.

    1995-05-01

    Prefrontal cortex volumetry by brain magnetic resonance (MR) is required to estimate changes postulated to occur in certain psychiatric and neurologic disorders. A semiautomated method with quantitative characterization of its performance is sought to reliably distinguish small prefrontal cortex volume changes within individuals and between groups. Stereological methods were tested by a blinded comparison of measurements applied to 3D MR scans obtained using an MPRAGE protocol. Fixed grid stereologic methods were used to estimate prefrontal cortex volumes on a graphic workstation, after the images are scaled from 16 to 8 bits using a histogram method. In addition images were resliced into coronal sections perpendicular to the bicommissural plane. Prefrontal cortex volumes were defined as all sections of the frontal lobe anterior to the anterior commissure. Ventricular volumes were excluded. Stereological measurement yielded high repeatability and precision, and was time efficient for the raters. The coefficient of error was volumetry by stereology can yield accurate and repeatable measurements. Small frontal lobe volume reductions in patients with brain disorders such as depression and schizophrenia can be efficiently assessed using this method.

  6. Unbiased estimation of the eyeball volume using the Cavalieri principle on computed tomography images.

    Science.gov (United States)

    Acer, Niyazi; Sahin, Bunyamin; Ucar, Tolga; Usanmaz, Mustafa

    2009-01-01

    The size of the eyeball has been the subject of a few studies. None of them used stereological methods to estimate the volume. In the current study, we estimated the volume of eyeball in normal men and women using the stereological methods. Eyeball volume (EV) was estimated using the Cavalieri principle as a combination of point-counting and planimetry techniques. We used computed tomography scans taken from 36 participants (15 men and 21 women) to estimate the EV. The mean (SD) EV values obtained by planimetry method were 7.49 (0.79) and 7.06 (0.85) cm in men and women, respectively. By using point-counting method, the mean (SD) values were 7.48 (0.85) and 7.21 (0.84) cm in men and women, respectively. There was no statistically significant difference between the findings from the 2 methods (P > 0.05). A weak correlation was found between the axial length of eyeball and the EV estimated by point counting and planimetry (P eyeball.

  7. No correlation between ultrasound placental grading at 31-34 weeks of gestation and a surrogate estimate of organ function at term obtained by stereological analysis.

    Science.gov (United States)

    Yin, T T; Loughna, P; Ong, S S; Padfield, J; Mayhew, T M

    2009-08-01

    We test the experimental hypothesis that early changes in the ultrasound appearance of the placenta reflect poor or reduced placental function. The sonographic (Grannum) grade of placental maturity was compared to placental function as expressed by the morphometric oxygen diffusive conductance of the villous membrane. Ultrasonography was used to assess the Grannum grade of 32 placentas at 31-34 weeks of gestation. Indications for the scans included a history of previous fetal abnormalities, previous fetal growth problems or suspicion of IUGR. Placentas were classified from grade 0 (most immature) to grade III (most mature). We did not exclude smokers or complicated pregnancies as we aimed to correlate the early appearance of mature placentas with placental function. After delivery, microscopical fields on formalin-fixed, trichrome-stained histological sections of each placenta were obtained by multistage systematic uniform random sampling. Using design-based stereological methods, the exchange surface areas of peripheral (terminal and intermediate) villi and their fetal capillaries and the arithmetic and harmonic mean thicknesses of the villous membrane (maternal surface of villous trophoblast to adluminal surface of vascular endothelium) were estimated. An index of the variability in thickness of this membrane, and an estimate of its oxygen diffusive conductance, were derived secondarily as were estimates of the mean diameters and total lengths of villi and fetal capillaries. Group comparisons were drawn using analysis of variance. We found no significant differences in placental volume or composition or in the dimensions or diffusive conductances of the villous membrane. Subsequent exclusion of smokers did not alter these main findings. Grannum grades at 31-34 weeks of gestation appear not to provide reliable predictors of the functional capacity of the term placenta as expressed by the surrogate measure, morphometric diffusive conductance.

  8. Hippocampal MR volumetry

    Science.gov (United States)

    Haller, John W.; Botteron, K.; Brunsden, Barry S.; Sheline, Yvette I.; Walkup, Ronald K.; Black, Kevin J.; Gado, Mokhtar; Vannier, Michael W.

    1994-09-01

    Goal: To estimate hippocampal volumes from in vivo 3D magnetic resonance (MR) brain images and determine inter-rater and intra- rater repeatability. Objective: The precision and repeatability of hippocampal volume estimates using stereologic measurement methods is sought. Design: Five normal control and five schizophrenic subjects were MR scanned using a MPRAGE protocol. Fixed grid stereologic methods were used to estimate hippocampal volumes on a graphics workstation. The images were preprocessed using histogram analysis to standardize 3D MR image scaling from 16 to 8 bits and image volumes were interpolated to 0.5 mm3 isotropic voxels. The following variables were constant for the repeated stereologic measures: grid size, inter-slice distance (1.5 mm), voxel dimensions (0.5 mm3), number of hippocampi measured (10), total number of measurements per rater (40), and number of raters (5). Two grid sizes were tested to determine the coefficient of error associated with the number of sampled 'hits' (approximately 140 and 280) on the hippocampus. Starting slice and grid position were randomly varied to assure unbiased volume estimates. Raters were blind to subject identity, diagnosis, and side of the brain from which the image volumes were extracted and the order of subject presentation was randomized for each of the raters. Inter- and intra-rater intraclass correlation coefficients (ICC) were determined. Results: The data indicate excellent repeatability of fixed grid stereologic hippocampal volume measures when using an inter-slice distance of 1.5 mm and a 6.25 mm2 grid (inter-rater ICCs equals 0.86 - 0.97, intra- rater ICCs equals 0.85 - 0.97). One major advantage of the current study was the use of 3D MR data which significantly improved visualization of hippocampal boundaries by providing the ability to access simultaneous orthogonal views while counting stereological marks within the hippocampus. Conclusion: Stereological estimates of 3D volumes from 2D MR

  9. Stereologic estimation of nucleolar volume in ocular melanoma

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Gamel, J W; McCurdy, J

    1993-01-01

    The aim of this study was to investigate the relationships between one-, two-, and three-dimensional histomorphometric estimators of nucleolar size in ordinary histologic sections of uveal melanomas from 144 patients. In addition, the prognostic value of the various size parameters was studied. T...

  10. Application of the Physical Disector Principle for Quantification of Dopaminergic Neuronal Loss in a Rat 6-Hydroxydopamine Nigral Lesion Model of Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Katrine Fabricius

    2017-12-01

    Full Text Available Stereological analysis is the optimal tool for quantitative assessment of brain morphological and cellular changes induced by neurotoxic lesions or treatment interventions. Stereological methods based on random sampling techniques yield unbiased estimates of particle counts within a defined volume, thereby providing a true quantitative estimate of the target cell population. Neurodegenerative diseases involve loss of specific neuron types, such as the midbrain tyrosine hydroxylase-positive dopamine neurons in Parkinson's disease and in animal models of nigrostriatal degeneration. Therefore, we applied an established automated physical disector principle in a fractionator design for efficient stereological quantitative analysis of tyrosine hydroxylase (TH-positive dopamine neurons in the substantia nigra pars compacta of hemiparkinsonian rats with unilateral 6-hydroxydopamine (6-OHDA lesions. We obtained reliable estimates of dopamine neuron numbers, and established the relationship between behavioral asymmetry and dopamine neuron loss on the lesioned side. In conclusion, the automated physical disector principle provided a useful and efficient tool for unbiased estimation of TH-positive neurons in rat midbrain, and should prove valuable for investigating neuroprotective strategies in 6-OHDA model of parkinsonism, while generalizing to other immunohistochemically-defined cell populations.

  11. Efficiently adapting graphical models for selectivity estimation

    DEFF Research Database (Denmark)

    Tzoumas, Kostas; Deshpande, Amol; Jensen, Christian S.

    2013-01-01

    cardinality estimation without making the independence assumption. By carefully using concepts from the field of graphical models, we are able to factor the joint probability distribution over all the attributes in the database into small, usually two-dimensional distributions, without a significant loss...... in estimation accuracy. We show how to efficiently construct such a graphical model from the database using only two-way join queries, and we show how to perform selectivity estimation in a highly efficient manner. We integrate our algorithms into the PostgreSQL DBMS. Experimental results indicate...

  12. No postnatal doubling of number of neurons in human Broca's areas (Brodmann areas 44 and 45)? A stereological study.

    Science.gov (United States)

    Uylings, H B M; Malofeeva, L I; Bogolepova, I N; Jacobsen, A M; Amunts, K; Zilles, K

    2005-01-01

    In this study we explored whether a postnatal doubling of the total number of neurons occurs in the human Brodmann areas 44 and 45 (Broca's area). We describe the most recent error prediction formulae and their application for the modern stereological estimators for volume and number of neurons. We estimated the number of neurons in 3D optical disector probes systematically random sampled throughout the entire Brodmann areas (BA) 44 and 45 in developing and young adult cases. In the relatively small number of male and female cases studied no substantial postnatal increase in total number of neurons occurred in areas 44 and 45; the volume of these areas reached adult values around 7 years. In addition, we did find indications that a shift from a right-over-left to a left-over-right asymmetry may occur in the volume of BA 45 during postnatal development. No major asymmetry in total number of neurons in BA 44 and 45 was detected.

  13. Three-dimensional stereology as a tool for evaluating bladder outlet obstruction

    DEFF Research Database (Denmark)

    Wijk, J. Van der; Wijk, J. Van der; Horn, T.

    2008-01-01

    -cup biopsy, taken during cystoscopy, was stereologically evaluated to determine the smooth muscle cell volume and the fractions of collagen and smooth muscle using light and electron microscopy. Results. The collagen fraction was higher in patients than in controls (probably because the patients were older...... tract symptoms (LUTS) suggestive of BOO and five controls (mean age 48.6 years; range 43-53 years) without LUTS were studied. All participants underwent a full examination, including determination of the International Prostate Symptom Score, laboratory analysis and a urodynamic evaluation. A cold...

  14. Introducing Stereology as a Tool to Assess the Severity of Psoriasis

    DEFF Research Database (Denmark)

    Kamp, Søren; Stenderup, Karin; Rosada, Cecilia

    2008-01-01

    to histological specimens in order to obtain three-dimensional properties from two-dimensional tissue samples. The psoriasis xenograft model used in this trial is accepted as a leading animal model for psoriasis. Psoriatic skin from psoriatic patients was grafted onto severe combined immunodeficient (SCID) mice......  The purpose of this study was to introduce stereology as a novel tool in assessing the severity of psoriasis. Psoriasis is a well described chronic inflammatory skin disease affecting approximately 2% of the Caucasian population.   The severity of psoriasis has been assessed by a multitude...

  15. Efficient, Differentially Private Point Estimators

    OpenAIRE

    Smith, Adam

    2008-01-01

    Differential privacy is a recent notion of privacy for statistical databases that provides rigorous, meaningful confidentiality guarantees, even in the presence of an attacker with access to arbitrary side information. We show that for a large class of parametric probability models, one can construct a differentially private estimator whose distribution converges to that of the maximum likelihood estimator. In particular, it is efficient and asymptotically unbiased. This result provides (furt...

  16. MILITARY MISSION COMBAT EFFICIENCY ESTIMATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Ighoyota B. AJENAGHUGHRURE

    2017-04-01

    Full Text Available Military infantry recruits, although trained, lacks experience in real-time combat operations, despite the combat simulations training. Therefore, the choice of including them in military operations is a thorough and careful process. This has left top military commanders with the tough task of deciding, the best blend of inexperienced and experienced infantry soldiers, for any military operation, based on available information on enemy strength and capability. This research project delves into the design of a mission combat efficiency estimator (MCEE. It is a decision support system that aids top military commanders in estimating the best combination of soldiers suitable for different military operations, based on available information on enemy’s combat experience. Hence, its advantages consist of reducing casualties and other risks that compromises the entire operation overall success, and also boosting the morals of soldiers in an operation, with such information as an estimation of combat efficiency of their enemies. The system was developed using Microsoft Asp.Net and Sql server backend. A case study test conducted with the MECEE system, reveals clearly that the MECEE system is an efficient tool for military mission planning in terms of team selection. Hence, when the MECEE system is fully deployed it will aid military commanders in the task of decision making on team members’ combination for any given operation based on enemy personnel information that is well known beforehand. Further work on the MECEE will be undertaken to explore fire power types and impact in mission combat efficiency estimation.

  17. Classification of tubulo-papillary renal cortical tumours using estimates of nuclear volume

    DEFF Research Database (Denmark)

    Brooks, B; Sørensen, Flemming Brandt; Olsen, S

    1993-01-01

    The classification of renal cortical tumours is problematic, with no clear division of benign from malignant tumours. Unbiased stereological estimates of volume-weighted nuclear volume (nuclear vv) were obtained by point sampling of nuclear intercepts in a retrospective study of 36 variably sized...

  18. Efficient estimation of semiparametric copula models for bivariate survival data

    KAUST Repository

    Cheng, Guang

    2014-01-01

    A semiparametric copula model for bivariate survival data is characterized by a parametric copula model of dependence and nonparametric models of two marginal survival functions. Efficient estimation for the semiparametric copula model has been recently studied for the complete data case. When the survival data are censored, semiparametric efficient estimation has only been considered for some specific copula models such as the Gaussian copulas. In this paper, we obtain the semiparametric efficiency bound and efficient estimation for general semiparametric copula models for possibly censored data. We construct an approximate maximum likelihood estimator by approximating the log baseline hazard functions with spline functions. We show that our estimates of the copula dependence parameter and the survival functions are asymptotically normal and efficient. Simple consistent covariance estimators are also provided. Numerical results are used to illustrate the finite sample performance of the proposed estimators. © 2013 Elsevier Inc.

  19. Stereology, an unbiased methodological approach to study plant anatomy and cytology: Past, present and future

    Czech Academy of Sciences Publication Activity Database

    Kubínová, Lucie; Radochová, Barbora; Lhotáková, Z.; Kubínová, Z.; Albrechtová, J.

    2017-01-01

    Roč. 36, č. 3 (2017), s. 187-205 ISSN 1580-3139 R&D Projects: GA MŠk(CZ) LM2015062 Institutional support: RVO:67985823 Keywords : chloroplast * confocal microscopy * leaf anatomy * mesophyll * stereological methods * systematic uniform random sampling Subject RIV: FS - Medical Facilities ; Equipment OBOR OECD: Medical laboratory technology (including laboratory samples analysis Impact factor: 1.135, year: 2016

  20. Stereological quantification of tumor volume, mean nuclear volume and total number of melanoma cells correlated with morbidity and mortality

    DEFF Research Database (Denmark)

    Bønnelykke-Behrndtz, Marie Louise; Sørensen, Flemming Brandt; Damsgaard, Tine Engberg

    2008-01-01

    potential indicators of prognosis. Sixty patients who underwent surgery at the Department of Plastic Surgery, Aarhus University Hospital, from 1991 to 1994 were included in the study. Total tumor volume was estimated by the Cavalieri technique, total number of tumor cells by the optical dissector principle...... showed a significant impact on both disease-free survival (p=0.001) and mortality (p=0.009). In conclusion, tumor volume and total number of cancer cells were highly reproducible but did not add additional, independent prognostic information regarding the study population.......Stereological quantification of tumor volume, total number of tumor cells and mean nuclear volume provides unbiased data, regardless of the three-dimensional shape of the melanocytic lesion. The aim of the present study was to investigate whether these variables are reproducible and may represent...

  1. Sensitivity of Technical Efficiency Estimates to Estimation Methods: An Empirical Comparison of Parametric and Non-Parametric Approaches

    OpenAIRE

    de-Graft Acquah, Henry

    2014-01-01

    This paper highlights the sensitivity of technical efficiency estimates to estimation approaches using empirical data. Firm specific technical efficiency and mean technical efficiency are estimated using the non parametric Data Envelope Analysis (DEA) and the parametric Corrected Ordinary Least Squares (COLS) and Stochastic Frontier Analysis (SFA) approaches. Mean technical efficiency is found to be sensitive to the choice of estimation technique. Analysis of variance and Tukey’s test sugge...

  2. On semiautomatic estimation of surface area

    DEFF Research Database (Denmark)

    Dvorak, J.; Jensen, Eva B. Vedel

    2013-01-01

    and the surfactor. For ellipsoidal particles, it is shown that the flower estimator is equal to the pivotal estimator based on support function measurements along four perpendicular rays. This result makes the pivotal estimator a powerful approximation to the flower estimator. In a simulation study of prolate....... If the segmentation is correct the estimate is computed automatically, otherwise the expert performs the necessary measurements manually. In case of convex particles we suggest to base the semiautomatic estimation on the so-called flower estimator, a new local stereological estimator of particle surface area....... For convex particles, the estimator is equal to four times the area of the support set (flower set) of the particle transect. We study the statistical properties of the flower estimator and compare its performance to that of two discretizations of the flower estimator, namely the pivotal estimator...

  3. A Stereological Method for the Quantitative Evaluation of Cartilage Repair Tissue

    Science.gov (United States)

    Nyengaard, Jens Randel; Lind, Martin; Spector, Myron

    2015-01-01

    Objective To implement stereological principles to develop an easy applicable algorithm for unbiased and quantitative evaluation of cartilage repair. Design Design-unbiased sampling was performed by systematically sectioning the defect perpendicular to the joint surface in parallel planes providing 7 to 10 hematoxylin–eosin stained histological sections. Counting windows were systematically selected and converted into image files (40-50 per defect). The quantification was performed by two-step point counting: (1) calculation of defect volume and (2) quantitative analysis of tissue composition. Step 2 was performed by assigning each point to one of the following categories based on validated and easy distinguishable morphological characteristics: (1) hyaline cartilage (rounded cells in lacunae in hyaline matrix), (2) fibrocartilage (rounded cells in lacunae in fibrous matrix), (3) fibrous tissue (elongated cells in fibrous tissue), (4) bone, (5) scaffold material, and (6) others. The ability to discriminate between the tissue types was determined using conventional or polarized light microscopy, and the interobserver variability was evaluated. Results We describe the application of the stereological method. In the example, we assessed the defect repair tissue volume to be 4.4 mm3 (CE = 0.01). The tissue fractions were subsequently evaluated. Polarized light illumination of the slides improved discrimination between hyaline cartilage and fibrocartilage and increased the interobserver agreement compared with conventional transmitted light. Conclusion We have applied a design-unbiased method for quantitative evaluation of cartilage repair, and we propose this algorithm as a natural supplement to existing descriptive semiquantitative scoring systems. We also propose that polarized light is effective for discrimination between hyaline cartilage and fibrocartilage. PMID:26069715

  4. An efficient quantum algorithm for spectral estimation

    Science.gov (United States)

    Steffens, Adrian; Rebentrost, Patrick; Marvian, Iman; Eisert, Jens; Lloyd, Seth

    2017-03-01

    We develop an efficient quantum implementation of an important signal processing algorithm for line spectral estimation: the matrix pencil method, which determines the frequencies and damping factors of signals consisting of finite sums of exponentially damped sinusoids. Our algorithm provides a quantum speedup in a natural regime where the sampling rate is much higher than the number of sinusoid components. Along the way, we develop techniques that are expected to be useful for other quantum algorithms as well—consecutive phase estimations to efficiently make products of asymmetric low rank matrices classically accessible and an alternative method to efficiently exponentiate non-Hermitian matrices. Our algorithm features an efficient quantum-classical division of labor: the time-critical steps are implemented in quantum superposition, while an interjacent step, requiring much fewer parameters, can operate classically. We show that frequencies and damping factors can be obtained in time logarithmic in the number of sampling points, exponentially faster than known classical algorithms.

  5. Design-based estimation of neuronal number and individual neuronal volume in the rat hippocampus

    DEFF Research Database (Denmark)

    Hosseini-Sharifabad, Mohammad; Nyengaard, Jens Randel

    2007-01-01

    Tools recently developed in stereology were employed for unbiased estimation of the neuronal number and volume in three major subdivisions of rat hippocampus (dentate granular, CA1 and CA3 pyramidal layers). The optical fractionator is used extensively in quantitative studies of the hippocampus; ...

  6. Efficient Frontier - Comparing Different Volatility Estimators

    OpenAIRE

    Tea Poklepović; Zdravka Aljinović; Mario Matković

    2015-01-01

    Modern Portfolio Theory (MPT) according to Markowitz states that investors form mean-variance efficient portfolios which maximizes their utility. Markowitz proposed the standard deviation as a simple measure for portfolio risk and the lower semi-variance as the only risk measure of interest to rational investors. This paper uses a third volatility estimator based on intraday data and compares three efficient frontiers on the Croatian Stock Market. The results show that ra...

  7. Effect of praziquantel administration on hepatic stereology of mice infected with Schistosoma mansoni and fed a low-protein diet

    Directory of Open Access Journals (Sweden)

    L.A. Barros

    2009-09-01

    Full Text Available A study was undertaken to investigate the effect of administering praziquantel (PZQ, focusing on the liver stereological findings of malnourished mice infected with Schistosoma mansoni. Thirty female Swiss Webster mice (age: 21 days; weight: 8-14 g were fed either a low-protein diet (8% or standard chow (22% protein for 15 days. Five mice in each group were infected with 50 cercariae each of the BH strain (Brazil. PZQ therapy (80 mg/kg body weight, per day was started on the 50th day of infection and consisted of daily administration for 5 days. Volume density (hepatocytes, sinusoids and hepatic fibrosis was determined by stereology using a light microscope. Body weight gain and total serum albumin levels were always lower in undernourished mice. Our stereological study demonstrated that treatment increased both volume density of hepatocytes in mice fed standard chow (47.56%, treated group and 12.06%, control and low-protein chow (30.98%, treated group and 21.44%, control, and hepatic sinusoids [standard chow (12.52%, treated group and 9.06%, control, low-protein chow (14.42%, treated group and 8.46%, control], while hepatic fibrosis was reduced [standard chow (39.92%, treated group and 78.88%, control and low-protein chow (54.60%, treated group and 70.10%, control]. On the other hand, mice fed low-protein chow decreased density volume of hepatocytes and hepatic fibrosis. In conclusion, our findings indicate that treatment with PZQ ameliorates hepatic schistosomiasis pathology even in mice fed a low-protein diet.

  8. Stereologic, histopathologic, flow cytometric, and clinical parameters in the prognostic evaluation of 74 patients with intraoral squamous cell carcinomas

    DEFF Research Database (Denmark)

    Bundgaard, T; Sørensen, Flemming Brandt; Gaihede, M

    1992-01-01

    BACKGROUND AND METHODS: A consecutive series of all 78 incident cases of intraoral squamous cell carcinoma occurring during a 2-year period in a population of 1.4 million inhabitants were evaluated by histologic score (the modified classification of Jacobsson et al.), flow cytometry, stereology, ...

  9. Efficient multidimensional regularization for Volterra series estimation

    Science.gov (United States)

    Birpoutsoukis, Georgios; Csurcsia, Péter Zoltán; Schoukens, Johan

    2018-05-01

    This paper presents an efficient nonparametric time domain nonlinear system identification method. It is shown how truncated Volterra series models can be efficiently estimated without the need of long, transient-free measurements. The method is a novel extension of the regularization methods that have been developed for impulse response estimates of linear time invariant systems. To avoid the excessive memory needs in case of long measurements or large number of estimated parameters, a practical gradient-based estimation method is also provided, leading to the same numerical results as the proposed Volterra estimation method. Moreover, the transient effects in the simulated output are removed by a special regularization method based on the novel ideas of transient removal for Linear Time-Varying (LTV) systems. Combining the proposed methodologies, the nonparametric Volterra models of the cascaded water tanks benchmark are presented in this paper. The results for different scenarios varying from a simple Finite Impulse Response (FIR) model to a 3rd degree Volterra series with and without transient removal are compared and studied. It is clear that the obtained models capture the system dynamics when tested on a validation dataset, and their performance is comparable with the white-box (physical) models.

  10. A Computationally Efficient Method for Polyphonic Pitch Estimation

    Directory of Open Access Journals (Sweden)

    Ruohua Zhou

    2009-01-01

    Full Text Available This paper presents a computationally efficient method for polyphonic pitch estimation. The method employs the Fast Resonator Time-Frequency Image (RTFI as the basic time-frequency analysis tool. The approach is composed of two main stages. First, a preliminary pitch estimation is obtained by means of a simple peak-picking procedure in the pitch energy spectrum. Such spectrum is calculated from the original RTFI energy spectrum according to harmonic grouping principles. Then the incorrect estimations are removed according to spectral irregularity and knowledge of the harmonic structures of the music notes played on commonly used music instruments. The new approach is compared with a variety of other frame-based polyphonic pitch estimation methods, and results demonstrate the high performance and computational efficiency of the approach.

  11. Global CO2 efficiency: Country-wise estimates using a stochastic cost frontier

    International Nuclear Information System (INIS)

    Herrala, Risto; Goel, Rajeev K.

    2012-01-01

    This paper examines global carbon dioxide (CO 2 ) efficiency by employing a stochastic cost frontier analysis of about 170 countries in 1997 and 2007. The main contribution lies in providing a new approach to environmental efficiency estimation, in which the efficiency estimates quantify the distance from the policy objective of minimum emissions. We are able to examine a very large pool of nations and provide country-wise efficiency estimates. We estimate three econometric models, corresponding with alternative interpretations of the Cancun vision (Conference of the Parties 2011). The models reveal progress in global environmental efficiency during a preceding decade. The estimates indicate vast differences in efficiency levels, and efficiency changes across countries. The highest efficiency levels are observed in Africa and Europe, while the lowest are clustered around China. The largest efficiency gains were observed in central and eastern Europe. CO 2 efficiency also improved in the US and China, the two largest emitters, but their ranking in terms of CO 2 efficiency deteriorated. Policy implications are discussed. - Highlights: ► We estimate global environmental efficiency in line with the Cancun vision, using a stochastic cost frontier. ► The study covers 170 countries during a 10 year period, ending in 2007. ► The biggest improvements occurred in Europe, and efficiency falls in South America. ► The efficiency ranking of US and China, the largest emitters, deteriorated. ► In 2007, highest efficiency was observed in Africa and Europe, and the lowest around China.

  12. Effect of hindlimb unloading on stereological parameters of the motor cortex and hippocampus in male rats.

    Science.gov (United States)

    Salehi, Mohammad Saied; Mirzaii-Dizgah, Iraj; Vasaghi-Gharamaleki, Behnoosh; Zamiri, Mohammad Javad

    2016-11-09

    Hindlimb unloading (HU) can cause motion and cognition dysfunction, although its cellular and molecular mechanisms are not well understood. The aim of the present study was to determine the stereological parameters of the brain areas involved in motion (motor cortex) and spatial learning - memory (hippocampus) under an HU condition. Sixteen adult male rats, kept under a 12 : 12 h light-dark cycle, were divided into two groups of freely moving (n=8) and HU (n=8) rats. The volume of motor cortex and hippocampus, the numerical cell density of neurons in layers I, II-III, V, and VI of the motor cortex, the entire motor cortex as well as the primary motor cortex, and the numerical density of the CA1, CA3, and dentate gyrus subregions of the hippocampus were estimated. No significant differences were observed in the evaluated parameters. Our results thus indicated that motor cortical and hippocampal atrophy and cell loss may not necessarily be involved in the motion and spatial learning memory impairment in the rat.

  13. An efficient estimator for Gibbs random fields

    Czech Academy of Sciences Publication Activity Database

    Janžura, Martin

    2014-01-01

    Roč. 50, č. 6 (2014), s. 883-895 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GBP402/12/G097 Institutional support: RVO:67985556 Keywords : Gibbs random field * efficient estimator * empirical estimator Subject RIV: BA - General Mathematics Impact factor: 0.541, year: 2014 http://library.utia.cas.cz/separaty/2015/SI/janzura-0441325.pdf

  14. Microstructure characterization via stereological relations — A shortcut for beginners

    Energy Technology Data Exchange (ETDEWEB)

    Pabst, Willi, E-mail: pabstw@vscht.cz; Gregorová, Eva; Uhlířová, Tereza

    2015-07-15

    Stereological relations that can be routinely applied for the quantitative characterization of microstructures of heterogeneous single- and two-phase materials via global microstructural descriptors are reviewed. It is shown that in the case of dense, single-phase polycrystalline materials (e.g., transparent yttrium aluminum garnet ceramics) two quantities have to be determined, the interface density (or, equivalently, the mean chord length of the grains) and the mean curvature integral density (or, equivalently, the Jeffries grain size), while for two-phase materials (e.g., highly porous, cellular alumina ceramics), one additional quantity, the volume fraction (porosity), is required. The Delesse–Rosiwal law is recalled and size measures are discussed. It is shown that the Jeffries grain size is based on the triple junction line length density, while the mean chord length of grains is based on the interface density (grain boundary area density). In contrast to widespread belief, however, these two size measures are not alternative, but independent (and thus complementary), measures of grain size. Concomitant with this fact, a clear distinction between linear and planar grain size numbers is proposed. Finally, based on our concept of phase-specific quantities, it is shown that under certain conditions it is possible to define a Jeffries size also for two-phase materials and that the ratio of the mean chord length and the Jeffries size has to be considered as an invariant number for a certain type of microstructure, i.e., a characteristic value that is independent of the absolute size of the microstructural features (e.g., grains, inclusions or pores). - Highlights: • Stereology-based image analysis is reviewed, including error considerations. • Recipes are provided for measuring global metric microstructural descriptors. • Size measures are based on interface density and mean curvature integral density. • Phase-specific quantities and a generalized

  15. Estimates of nuclear volume in plaque and tumor-stage mycosis fungoides. A new prognostic indicator

    DEFF Research Database (Denmark)

    Brooks, B; Sørensen, Flemming Brandt; Thestrup-Pedersen, K

    1994-01-01

    It is well documented that mycosis fungoides (MF), a cutaneous T-cell lymphoma, has a variable clinical course. Unbiased stereological estimates of three-dimensional volume-weighted mean nuclear size (nucl vV) of mycosis cells were obtained in a retrospective study of 18 patients with a total of ...

  16. Effect of Sodium Cyclamate on the Rat Fetal Exocrine Pancreas: a Karyometric and Stereological Study

    OpenAIRE

    MARTINS, Alex Tadeu; SANTOS, Fabiano de Sant`Ana dos; SCANNAVINO, Fabio Luiz Ferreira; PIRES, Juliana Rico; ZUZA, Elizangela Partata; PADOVANI JUNIOR, Joao Armando; AZOUBEL, Reinaldo; MATEO, Miguel Angel Sala Di; LOPES, Ruberval Armando

    2010-01-01

    The cyclamate, a sweetner substance derived from N-cyclo-hexyl-sulfamic acid, is largely utilized as a non-caloric artificial edulcorant in foods and beverages as well as in the pharmaceutical industry. The objective of this study was to evaluate karyometric and stereological alterations in the rat fetal pancreas resulting from the intraperitoneal administration of sodium cyclamate. The exocrine pancreas of ten fetuses of rats were evaluated, five treated and five controls chosen at random, i...

  17. Tensor-based morphometry and stereology reveal brain pathology in the complexin1 knockout mouse.

    Science.gov (United States)

    Kielar, Catherine; Sawiak, Stephen J; Navarro Negredo, Paloma; Tse, Desmond H Y; Morton, A Jennifer

    2012-01-01

    Complexins (Cplxs) are small, soluble, regulatory proteins that bind reversibly to the SNARE complex and modulate synaptic vesicle release. Cplx1 knockout mice (Cplx1(-/-)) have the earliest known onset of ataxia seen in a mouse model, although hitherto no histopathology has been described in these mice. Nevertheless, the profound neurological phenotype displayed by Cplx1(-/-) mutants suggests that significant functional abnormalities must be present in these animals. In this study, MRI was used to automatically detect regions where structural differences were not obvious when using a traditional histological approach. Tensor-based morphometry of Cplx1(-/-) mouse brains showed selective volume loss from the thalamus and cerebellum. Stereological analysis of Cplx1(-/-) and Cplx1(+/+) mice brain slices confirmed the volume loss in the thalamus as well as loss in some lobules of the cerebellum. Finally, stereology was used to show that there was loss of cerebellar granule cells in Cplx1(-/-) mice when compared to Cplx1(+/+) animals. Our study is the first to describe pathological changes in Cplx1(-/-) mouse brain. We suggest that the ataxia in Cplx1(-/-) mice is likely to be due to pathological changes in both cerebellum and thalamus. Reduced levels of Cplx proteins have been reported in brains of patients with neurodegenerative diseases. Therefore, understanding the effects of Cplx depletion in brains from Cplx1(-/-) mice may also shed light on the mechanisms underlying pathophysiology in disorders in which loss of Cplx1 occurs.

  18. Tensor-based morphometry and stereology reveal brain pathology in the complexin1 knockout mouse.

    Directory of Open Access Journals (Sweden)

    Catherine Kielar

    Full Text Available Complexins (Cplxs are small, soluble, regulatory proteins that bind reversibly to the SNARE complex and modulate synaptic vesicle release. Cplx1 knockout mice (Cplx1(-/- have the earliest known onset of ataxia seen in a mouse model, although hitherto no histopathology has been described in these mice. Nevertheless, the profound neurological phenotype displayed by Cplx1(-/- mutants suggests that significant functional abnormalities must be present in these animals. In this study, MRI was used to automatically detect regions where structural differences were not obvious when using a traditional histological approach. Tensor-based morphometry of Cplx1(-/- mouse brains showed selective volume loss from the thalamus and cerebellum. Stereological analysis of Cplx1(-/- and Cplx1(+/+ mice brain slices confirmed the volume loss in the thalamus as well as loss in some lobules of the cerebellum. Finally, stereology was used to show that there was loss of cerebellar granule cells in Cplx1(-/- mice when compared to Cplx1(+/+ animals. Our study is the first to describe pathological changes in Cplx1(-/- mouse brain. We suggest that the ataxia in Cplx1(-/- mice is likely to be due to pathological changes in both cerebellum and thalamus. Reduced levels of Cplx proteins have been reported in brains of patients with neurodegenerative diseases. Therefore, understanding the effects of Cplx depletion in brains from Cplx1(-/- mice may also shed light on the mechanisms underlying pathophysiology in disorders in which loss of Cplx1 occurs.

  19. PFP total operating efficiency calculation and basis of estimate

    International Nuclear Information System (INIS)

    SINCLAIR, J.C.

    1999-01-01

    The purpose of the Plutonium Finishing Plant (PFP) Total Operating Efficiency Calculation and Basis of Estimate document is to provide the calculated value and basis of estimate for the Total Operating Efficiency (TOE) for the material stabilization operations to be conducted in 234-52 Building. This information will be used to support both the planning and execution of the Plutonium Finishing Plant (PFP) Stabilization and Deactivation Project's (hereafter called the Project) resource-loaded, integrated schedule

  20. Stereology of the thyroid gland in Indo-Pacific bottlenose dolphin (Tursiops aduncus in comparison with human (Homo sapiens: quantitative and functional implications.

    Directory of Open Access Journals (Sweden)

    Brian Chin Wing Kot

    Full Text Available The mammalian thyroid gland maintains basal metabolism in tissues for optimal function. Determining thyroid volume is important in assessing growth and involution. Volume estimation is also important in stereological studies. Direct measurements of colloid volume and nuclear-to-cytoplasmic ratio of the follicular cells may provide important information about thyroid gland function such as hormone storage and secretion, which helps understand the changes at morphological and functional levels. The present study determined the colloid volume using simple stereological principle and the nuclear-to-cytoplasmic ratio of 4 Indo-Pacific bottlenose dolphins and 2 human thyroid glands. In both dolphin and human thyroid glands, the size of the follicles tended to be quite variable. The distribution of large and small follicles within the thyroid gland was also found to be random in both the dolphin and human thyroid gland; however, the size of follicles appeared to decrease as a function of increasing age in the dolphin thyroid gland. The mean colloid volume of the dolphin thyroid gland and human thyroid gland was 1.22×10(5 µm(3 and 7.02×10(5 µm(3 respectively. The dolphin and human subjects had a significant difference in the mean colloid volume. The mean N/C ratio of the dolphin thyroid follicular epithelia and human follicular epithelia was 0.50 and 0.64 respectively. The dolphin and human subjects had a significant difference in the mean N/C ratio. This information contributes to understanding dolphin thyroid physiology and its structural adaptations to meet the physical demands of the aquatic environment, and aids with ultrasonography and corrective therapy in live subjects.

  1. Stereological observations of platelet-reinforced mullite- and zirconia-matrix composites

    International Nuclear Information System (INIS)

    Cherian, I.K.; Kriven, W.M.; Lehigh, M.D.; Nettleship, I.

    1996-01-01

    Recently, the effect of solid inclusions on the sintering of ceramic powders has been explained in terms of a back-stress that opposes densification. Several analyses have been proposed to describe this problem. However, little quantitative information exists concerning the effect of reinforcement on microstructural evolution. This study compares the microstructural development of zirconia and mullite matrices in the presence of alumina platelets. The effect of platelet loading on density is similar for both composites. Quantitative stereological examinations reveal that the average grain size and pore size are finer for the zirconia-matrix composite. The platelet loading does not have any noticeable effect on the average grain size of the matrix in either composite. However, the average pore size increases as the volume fraction of platelets increases for both materials. Contiguity measurements have detected some aggregation of platelets in the zirconia-matrix composite

  2. Piecewise Loglinear Estimation of Efficient Production Surfaces

    OpenAIRE

    Rajiv D. Banker; Ajay Maindiratta

    1986-01-01

    Linear programming formulations for piecewise loglinear estimation of efficient production surfaces are derived from a set of basic properties postulated for the underlying production possibility sets. Unlike the piecewise linear model of Banker, Charnes, and Cooper (Banker R. D., A. Charnes, W. W. Cooper. 1984. Models for the estimation of technical and scale inefficiencies in data envelopment analysis. Management Sci. 30 (September) 1078--1092.), this approach permits the identification of ...

  3. Effects of melatonin on diclofenac sodium treated rat kidney: a stereological and histopathological study.

    Science.gov (United States)

    Khoshvakhti, Habib; Yurt, K Kübra; Altunkaynak, B Zuhal; Türkmen, Aysın P; Elibol, Ebru; Aydın, Işınsu; Kıvrak, Elfide G; Önger, M Emin; Kaplan, Süleyman

    2015-01-01

    In this study, we aimed to investigate the effect of diclofenac sodium (DS) and melatonin (MEL) on kidney of the prenatally administered rats. Pregnant rats were divided into the control, physiological saline, DS, and DS + MEL groups. All injections were given beginning from the 5th day after mating to the 15th day of the pregnancy. Physical dissector and Cavalieri principle were used to estimate the numerical density and total number of glomeruli and the volumetric parameters of kidney, respectively. Our stereological results indicated that DS application during the pregnancy lead to decrease in the mean volume, numerical density, and total number of the glomeruli (p  0.05). Light microscopic investigation showed congestion in blood vessels and shrinkage of the Bowman's space in the DS group. Moreover, there was degeneration in nephrons including glomerulosclerosis and tubular defects, and an increase in the connective tissue in the kidneys of the DS-treated group. However, usage of the MEL with the DS caused preventing of these pathological alterations in the kidney. We suggested that DS might lead to adverse effects in the kidneys of the rats that are prenatally subjected to this drug. Fortunately, these adverse effects can be prevented by the melatonin supplementation.

  4. Estimating Production Technical Efficiency of Irvingia Seed (Ogbono ...

    African Journals Online (AJOL)

    This study estimated the production technical efficiency of irvingia seed (Ogbono) farmers in Nsukka agricultural zone in Enugu State, Nigeria. This is against the backdrop of the importance of efficiency as a factor of productivity in a growing economy like Nigeria where resources are scarce and opportunities for new ...

  5. Stereological comparison of oocyte recruitment and batch fecundity estimates from paraffin and resin sections using spawning albacore (Thunnus alalunga) ovaries as a case study

    Science.gov (United States)

    Saber, Sámar; Macías, David; Ortiz de Urbina, Josetxu; Kjesbu, Olav Sigurd

    2015-01-01

    Traditional histological protocols in marine fish reproductive laboratories using paraffin as the embedding medium are now increasingly being replaced with protocols using resin instead. These procedures entail different degrees of tissue shrinkage complicating direct comparisons of measurement results across laboratories or articles. In this work we selected ovaries of spawning Mediterranean albacore (Thunnus alalunga) as the subject of our study to address the issue of structural changes, by contrasting values on oocyte recruitment and final batch fecundity given from the same tissue samples in both paraffin and resin. A modern stereological method, the oocyte packing density (OPD) theory, was used supported by initial studies on ovarian tissue sampling and measurement design. Examples of differences in the volume fraction of oocyte stages, free space and connective tissue were found between the embedding media. Mean oocyte diameters were smaller in paraffin than in resin with differences ranging between 0.5% in primary growth and 24.3% in hydration (HYD) stage oocytes. Fresh oocyte measurements showed that oocytes shrank as a consequence of the embedding process, reaching the maximal degree of shrinkage for oocytes in the HYD stage (45.8% in paraffin and 26.5% in resin). In order to assess the effect of oocyte shrinkage on the OPD result, and thereby on relative batch fecundity (Fr), oocyte diameters corrected and uncorrected for shrinkage, were used for estimations. Statistical significant differences were found (P based on either oocytes in the germinal vesicle migration stage or HYD stage. As a valuable adjunct, the present use of the OPD theory made it possible to document that the oocyte recruitment of spawning ovaries of Mediterranean albacore followed the typical pattern of an asynchronous oocyte development and indeterminate fecundity.

  6. Extrapolated HPGe efficiency estimates based on a single calibration measurement

    International Nuclear Information System (INIS)

    Winn, W.G.

    1994-01-01

    Gamma spectroscopists often must analyze samples with geometries for which their detectors are not calibrated. The effort to experimentally recalibrate a detector for a new geometry can be quite time consuming, causing delay in reporting useful results. Such concerns have motivated development of a method for extrapolating HPGe efficiency estimates from an existing single measured efficiency. Overall, the method provides useful preliminary results for analyses that do not require exceptional accuracy, while reliably bracketing the credible range. The estimated efficiency element-of for a uniform sample in a geometry with volume V is extrapolated from the measured element-of 0 of the base sample of volume V 0 . Assuming all samples are centered atop the detector for maximum efficiency, element-of decreases monotonically as V increases about V 0 , and vice versa. Extrapolation of high and low efficiency estimates element-of h and element-of L provides an average estimate of element-of = 1/2 [element-of h + element-of L ] ± 1/2 [element-of h - element-of L ] (general) where an uncertainty D element-of = 1/2 (element-of h - element-of L ] brackets limits for a maximum possible error. The element-of h and element-of L both diverge from element-of 0 as V deviates from V 0 , causing D element-of to increase accordingly. The above concepts guided development of both conservative and refined estimates for element-of

  7. Total numbers of neurons and glial cells in cortex and basal ganglia of aged brains with Down syndrome--a stereological study.

    Science.gov (United States)

    Karlsen, Anna Schou; Pakkenberg, Bente

    2011-11-01

    The total numbers of neurons and glial cells in the neocortex and basal ganglia in adults with Down syndrome (DS) were estimated with design-based stereological methods, providing quantitative data on brains affected by delayed development and accelerated aging. Cell numbers, volume of regions, and densities of neurons and glial cell subtypes were estimated in brains from 4 female DS subjects (mean age 66 years) and 6 female controls (mean age 70 years). The DS subjects were estimated to have about 40% fewer neocortical neurons in total (11.1 × 10(9) vs. 17.8 × 10(9), 2p ≤ 0.001) and almost 30% fewer neocortical glial cells with no overlap to controls (12.8 × 10(9) vs. 18.2 × 10(9), 2p = 0.004). In contrast, the total number of neurons in the basal ganglia was the same in the 2 groups, whereas the number of oligodendrocytes in the basal ganglia was reduced by almost 50% in DS (405 × 10(6) vs. 816 × 10(6), 2p = 0.01). We conclude that trisomy 21 affects cortical structures more than central gray matter emphasizing the differential impairment of brain development. Despite concomitant Alzheimer-like pathology, the neurodegenerative outcome in a DS brain deviates from common Alzheimer disease.

  8. Stereological Methods for Estimation of Total Number of Particles in ...

    African Journals Online (AJOL)

    In certain organs, like the brain, it is important to count the number of neurons associated with a particular function or region. The count gives an estimate of the electronic units available for a specific task or are endowed with a quantum of electrical energy. Similar studies can be extended in organs like the kidney, glands ...

  9. Stoichiometric estimates of the biochemical conversion efficiencies in tsetse metabolism

    Directory of Open Access Journals (Sweden)

    Custer Adrian V

    2005-08-01

    Full Text Available Abstract Background The time varying flows of biomass and energy in tsetse (Glossina can be examined through the construction of a dynamic mass-energy budget specific to these flies but such a budget depends on efficiencies of metabolic conversion which are unknown. These efficiencies of conversion determine the overall yields when food or storage tissue is converted into body tissue or into metabolic energy. A biochemical approach to the estimation of these efficiencies uses stoichiometry and a simplified description of tsetse metabolism to derive estimates of the yields, for a given amount of each substrate, of conversion product, by-products, and exchanged gases. This biochemical approach improves on estimates obtained through calorimetry because the stoichiometric calculations explicitly include the inefficiencies and costs of the reactions of conversion. However, the biochemical approach still overestimates the actual conversion efficiency because the approach ignores all the biological inefficiencies and costs such as the inefficiencies of leaky membranes and the costs of molecular transport, enzyme production, and cell growth. Results This paper presents estimates of the net amounts of ATP, fat, or protein obtained by tsetse from a starting milligram of blood, and provides estimates of the net amounts of ATP formed from the catabolism of a milligram of fat along two separate pathways, one used for resting metabolism and one for flight. These estimates are derived from stoichiometric calculations constructed based on a detailed quantification of the composition of food and body tissue and on a description of the major metabolic pathways in tsetse simplified to single reaction sequences between substrates and products. The estimates include the expected amounts of uric acid formed, oxygen required, and carbon dioxide released during each conversion. The calculated estimates of uric acid egestion and of oxygen use compare favorably to

  10. Efficient Methods of Estimating Switchgrass Biomass Supplies

    Science.gov (United States)

    Switchgrass (Panicum virgatum L.) is being developed as a biofuel feedstock for the United States. Efficient and accurate methods to estimate switchgrass biomass feedstock supply within a production area will be required by biorefineries. Our main objective was to determine the effectiveness of in...

  11. Efficient estimation for ergodic diffusions sampled at high frequency

    DEFF Research Database (Denmark)

    Sørensen, Michael

    A general theory of efficient estimation for ergodic diffusions sampled at high fre- quency is presented. High frequency sampling is now possible in many applications, in particular in finance. The theory is formulated in term of approximate martingale estimating functions and covers a large class...

  12. Estimation of farm level technical efficiency and its determinants ...

    African Journals Online (AJOL)

    With the difficulties encountered by the farmers in adopting improved technologies, increasing resource use efficiency has become a very significant factor in increasing productivity. Therefore, this study was designed to estimate the farm level technical efficiency and its determinants among male and female sweet potato ...

  13. Semiparametric Gaussian copula models : Geometry and efficient rank-based estimation

    NARCIS (Netherlands)

    Segers, J.; van den Akker, R.; Werker, B.J.M.

    2014-01-01

    We propose, for multivariate Gaussian copula models with unknown margins and structured correlation matrices, a rank-based, semiparametrically efficient estimator for the Euclidean copula parameter. This estimator is defined as a one-step update of a rank-based pilot estimator in the direction of

  14. Three-dimensional stereology as a tool for evaluating bladder outlet obstruction

    DEFF Research Database (Denmark)

    Van Der Wijk, Jasper; Van Der Wijk, Jan; Horn, Thomas

    2008-01-01

    Objective. In a pilot study we evaluated whether implementation of a novel 3D stereologic technique can prove that bladder outlet obstruction (BOO) is associated with morphologic changes in the bladder wall. Material and methods. Ten males (mean age 69.7 years; range 58-84 years) with lower urinary...... tract symptoms (LUTS) suggestive of BOO and five controls (mean age 48.6 years; range 43-53 years) without LUTS were studied. All participants underwent a full examination, including determination of the International Prostate Symptom Score, laboratory analysis and a urodynamic evaluation. A cold....... Conclusions. This pilot study shows that, even with the implementation of subtle morphometric techniques, there seems to be no relationship between the severity of BOO and bladder wall morphology. It is possible that interstitial collagen in the bladder wall increases with age. It seems that bladder wall...

  15. Efficient channel estimation in massive MIMO systems - a distributed approach

    KAUST Repository

    Al-Naffouri, Tareq Y.

    2016-01-01

    We present two efficient algorithms for distributed estimation of channels in massive MIMO systems. The two cases of 1) generic, and 2) sparse channels is considered. The algorithms estimate the impulse response for each channel observed

  16. Stereological measures of trabecular bone structure: comparison of 3D micro computed tomography with 2D histological sections in human proximal tibial bone biopsies

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Laib, A.; Koller, B.

    2005-01-01

    Stereology applied on histological sections is the 'gold standard' for obtaining quantitative information on cancellous bone structure. Recent advances in micro computed tomography (microCT) have made it possible to acquire three-dimensional (3D) data non-destructively. However, before the 3D...... methods can be used as a substitute for the current 'gold standard' they have to be verified against the existing standard. The aim of this study was to compare bone structural measures obtained from 3D microCT data sets with those obtained by stereology performed on conventional histological sections...... tibial metaphysis. The biopsies were embedded in methylmetacrylate before microCT scanning in a Scanco microCT 40 scanner at a resolution of 20 x 20 x 20 microm3, and the 3D data sets were analysed with a computer program. After microCT scanning, 16 sections were cut from the central 2 mm of each biopsy...

  17. An empirical analysis of the precision of estimating the numbers of neurons and glia in human neocortex using a fractionator-design with sub-sampling

    DEFF Research Database (Denmark)

    Lyck, L.; Santamaria, I.D.; Pakkenberg, B.

    2009-01-01

    Improving histomorphometric analysis of the human neocortex by combining stereological cell counting with immunchistochemical visualisation of specific neuronal and glial cell populations is a methodological challenge. To enable standardized immunohistochemical staining, the amount of brain tissue...... to be stained and analysed by cell counting was efficiently reduced using a fractionator protocol involving several steps of sub-sampling. Since no mathematical or statistical tools exist to predict the variance originating from repeated sampling in complex structures like the human neocortex, the variance....... The results showed that it was possible, but not straight forward, to combine immunohistochemistry and the optical fractionator for estimation of specific subpopulations of brain cells in human neocortex. (C) 2009 Elsevier B.V. All rights reserved Udgivelsesdato: 2009/9/15...

  18. Alternative Approaches to Technical Efficiency Estimation in the Stochastic Frontier Model

    OpenAIRE

    Acquah, H. de-Graft; Onumah, E. E.

    2014-01-01

    Estimating the stochastic frontier model and calculating technical efficiency of decision making units are of great importance in applied production economic works. This paper estimates technical efficiency from the stochastic frontier model using Jondrow, and Battese and Coelli approaches. In order to compare alternative methods, simulated data with sample sizes of 60 and 200 are generated from stochastic frontier model commonly applied to agricultural firms. Simulated data is employed to co...

  19. AN ESTIMATION OF TECHNICAL EFFICIENCY OF GARLIC PRODUCTION IN KHYBER PAKHTUNKHWA PAKISTAN

    Directory of Open Access Journals (Sweden)

    Nabeel Hussain

    2014-04-01

    Full Text Available This study was conducted to estimate the technical efficiency of farmers in garlic production in Khyber Pakhtunkhwa province, Pakistan. Data was randomly collected from 110 farmers using multistage sampling technique. Maximum likelihood estimation technique was used to estimate Cob-Douglas frontier production function. The analysis revealed that the estimated mean technical efficiency was 77 percent indicating that total output can be further increased with efficient use of resources and technology. The estimated gamma value was found to be 0.93 which shows 93% variation in garlic output due to inefficiency factors. The analysis further revealed that seed rate, tractor hours, fertilizer, FYM and weedicides were positive and statistically significant production factors. The results also show that age and education were statistically significant inefficiency factors, age having positive and education having negative relationship with the output of garlic. This study suggests that in order to increase the production of garlic by taking advantage of their high efficiency level, the government should invest in the research and development aspects for introducing good quality seeds to increase garlic productivity and should organize training programs to educate farmers about garlic production.

  20. Highly Efficient Estimators of Multivariate Location with High Breakdown Point

    NARCIS (Netherlands)

    Lopuhaa, H.P.

    1991-01-01

    We propose an affine equivariant estimator of multivariate location that combines a high breakdown point and a bounded influence function with high asymptotic efficiency. This proposal is basically a location $M$-estimator based on the observations obtained after scaling with an affine equivariant

  1. An organic group contribution approach to radiative efficiency estimation of organic working fluid

    International Nuclear Information System (INIS)

    Zhang, Xinxin; Kobayashi, Noriyuki; He, Maogang; Wang, Jingfu

    2016-01-01

    Highlights: • We use group contribution method to estimate radiative efficiency. • CFC, HCFC, HFC, HFE, and PFC were estimated using this method. • In most cases, the estimation value has a good precision. • The method is reliable for the estimation of molecule with a symmetric structure. • This estimation method can offer good reference for working fluid development. - Abstract: The ratification of the Montreal Protocol in 1987 and the Kyoto Protocol in 1997 mark an environment protection era of the development of organic working fluid. Ozone depletion potential (ODP) and global warming potential (GWP) are two most important indices for the quantitative comparison of organic working fluid. Nowadays, more and more attention has been paid to GWP. The calculation of GWP is an extremely complicated process which involves interactions between surface and atmosphere such as atmospheric radiative transfer and atmospheric chemical reactions. GWP of a substance is related to its atmospheric abundance and is a variable in itself. However, radiative efficiency is an intermediate parameter for GWP calculation and it is a constant value used to describe inherent property of a substance. In this paper, the group contribution method was adopted to estimate the radiative efficiency of the organic substance which contains more than one carbon atom. In most cases, the estimation value and the standard value are in a good agreement. The biggest estimation error occurs in the estimation of the radiative efficiency of fluorinated ethers due to its plenty of structure groups and its complicated structure compared with hydrocarbon. This estimation method can be used to predict the radiative efficiency of newly developed organic working fluids.

  2. KDE-Track: An Efficient Dynamic Density Estimator for Data Streams

    KAUST Repository

    Qahtan, Abdulhakim Ali Ali; Wang, Suojin; Zhang, Xiangliang

    2016-01-01

    Recent developments in sensors, global positioning system devices and smart phones have increased the availability of spatiotemporal data streams. Developing models for mining such streams is challenged by the huge amount of data that cannot be stored in the memory, the high arrival speed and the dynamic changes in the data distribution. Density estimation is an important technique in stream mining for a wide variety of applications. The construction of kernel density estimators is well studied and documented. However, existing techniques are either expensive or inaccurate and unable to capture the changes in the data distribution. In this paper, we present a method called KDE-Track to estimate the density of spatiotemporal data streams. KDE-Track can efficiently estimate the density function with linear time complexity using interpolation on a kernel model, which is incrementally updated upon the arrival of new samples from the stream. We also propose an accurate and efficient method for selecting the bandwidth value for the kernel density estimator, which increases its accuracy significantly. Both theoretical analysis and experimental validation show that KDE-Track outperforms a set of baseline methods on the estimation accuracy and computing time of complex density structures in data streams.

  3. KDE-Track: An Efficient Dynamic Density Estimator for Data Streams

    KAUST Repository

    Qahtan, Abdulhakim Ali Ali

    2016-11-08

    Recent developments in sensors, global positioning system devices and smart phones have increased the availability of spatiotemporal data streams. Developing models for mining such streams is challenged by the huge amount of data that cannot be stored in the memory, the high arrival speed and the dynamic changes in the data distribution. Density estimation is an important technique in stream mining for a wide variety of applications. The construction of kernel density estimators is well studied and documented. However, existing techniques are either expensive or inaccurate and unable to capture the changes in the data distribution. In this paper, we present a method called KDE-Track to estimate the density of spatiotemporal data streams. KDE-Track can efficiently estimate the density function with linear time complexity using interpolation on a kernel model, which is incrementally updated upon the arrival of new samples from the stream. We also propose an accurate and efficient method for selecting the bandwidth value for the kernel density estimator, which increases its accuracy significantly. Both theoretical analysis and experimental validation show that KDE-Track outperforms a set of baseline methods on the estimation accuracy and computing time of complex density structures in data streams.

  4. Phytoremediation: realistic estimation of modern efficiency and future possibility

    International Nuclear Information System (INIS)

    Kravets, A.; Pavlenko, Y.; Kusmenko, L.; Ermak, M.

    1996-01-01

    Kinetic peculiarities of the radionuclides migration in the system 'soil-plant' of the Chernobyl region have been investigated by means of numerical modelling. Quantitative estimation of half-time of natural cleaning of soil has been realised. Potential possibility and efficiency of the modem phytoremediation technology has been estimated. Outlines of the general demands and future possibility of biotechnology of the phytoremediation creation have been formulated. (author)

  5. Phytoremediation: realistic estimation of modern efficiency and future possibility

    Energy Technology Data Exchange (ETDEWEB)

    Kravets, A; Pavlenko, Y [Institute of Cell Biology and Genetic Engineering NAS, Kiev (Ukraine); Kusmenko, L; Ermak, M [Institute of Plant Physiology and Genetic NAS, Vasilkovsky, Kiev (Ukraine)

    1996-11-01

    Kinetic peculiarities of the radionuclides migration in the system 'soil-plant' of the Chernobyl region have been investigated by means of numerical modelling. Quantitative estimation of half-time of natural cleaning of soil has been realised. Potential possibility and efficiency of the modem phytoremediation technologyhas been estimated. Outlines of the general demands and future possibility of biotechnology of the phytoremediation creation have been formulated. (author)

  6. Engineering estimates versus impact evaluation of energy efficiency projects: Regression discontinuity evidence from a case study

    International Nuclear Information System (INIS)

    Lang, Corey; Siler, Matthew

    2013-01-01

    Energy efficiency upgrades have been gaining widespread attention across global channels as a cost-effective approach to addressing energy challenges. The cost-effectiveness of these projects is generally predicted using engineering estimates pre-implementation, often with little ex post analysis of project success. In this paper, for a suite of energy efficiency projects, we directly compare ex ante engineering estimates of energy savings to ex post econometric estimates that use 15-min interval, building-level energy consumption data. In contrast to most prior literature, our econometric results confirm the engineering estimates, even suggesting the engineering estimates were too modest. Further, we find heterogeneous efficiency impacts by time of day, suggesting select efficiency projects can be useful in reducing peak load. - Highlights: • Regression discontinuity used to estimate energy savings from efficiency projects. • Ex post econometric estimates validate ex ante engineering estimates of energy savings. • Select efficiency projects shown to reduce peak load

  7. Robust and efficient parameter estimation in dynamic models of biological systems.

    Science.gov (United States)

    Gábor, Attila; Banga, Julio R

    2015-10-29

    Dynamic modelling provides a systematic framework to understand function in biological systems. Parameter estimation in nonlinear dynamic models remains a very challenging inverse problem due to its nonconvexity and ill-conditioning. Associated issues like overfitting and local solutions are usually not properly addressed in the systems biology literature despite their importance. Here we present a method for robust and efficient parameter estimation which uses two main strategies to surmount the aforementioned difficulties: (i) efficient global optimization to deal with nonconvexity, and (ii) proper regularization methods to handle ill-conditioning. In the case of regularization, we present a detailed critical comparison of methods and guidelines for properly tuning them. Further, we show how regularized estimations ensure the best trade-offs between bias and variance, reducing overfitting, and allowing the incorporation of prior knowledge in a systematic way. We illustrate the performance of the presented method with seven case studies of different nature and increasing complexity, considering several scenarios of data availability, measurement noise and prior knowledge. We show how our method ensures improved estimations with faster and more stable convergence. We also show how the calibrated models are more generalizable. Finally, we give a set of simple guidelines to apply this strategy to a wide variety of calibration problems. Here we provide a parameter estimation strategy which combines efficient global optimization with a regularization scheme. This method is able to calibrate dynamic models in an efficient and robust way, effectively fighting overfitting and allowing the incorporation of prior information.

  8. Efficient estimation for high similarities using odd sketches

    DEFF Research Database (Denmark)

    Mitzenmacher, Michael; Pagh, Rasmus; Pham, Ninh Dang

    2014-01-01

    . This means that Odd Sketches provide a highly space-efficient estimator for sets of high similarity, which is relevant in applications such as web duplicate detection, collaborative filtering, and association rule learning. The method extends to weighted Jaccard similarity, relevant e.g. for TF-IDF vector...... and web duplicate detection tasks....

  9. Effects of bisphenol A treatment during pregnancy on kidney development in mice: a stereological and histopathological study.

    Science.gov (United States)

    Nuñez, P; Fernandez, T; García-Arévalo, M; Alonso-Magdalena, P; Nadal, A; Perillan, C; Arguelles, J

    2018-04-01

    Bisphenol A (BPA) is a chemical found in plastics that resembles oestrogen in organisms. Developmental exposure to endocrine-disrupting chemicals, such as BPA, increases the susceptibility to type 2 diabetes (T2DM) and cardiovascular diseases. Animal studies have reported a nephron deficit in offspring exposed to maternal diabetes. The aim of this study was to investigate the prenatal BPA exposure effects on nephrogenesis in a mouse model that was predisposed to T2DM. This study quantitatively evaluated the renal structural changes using stereology and histomorphometry methods. The OF1 pregnant mice were treated with a vehicle or BPA (10 or 100 μg/kg/day) during days 9-16 of gestation (early nephrogenesis). The 30-day-old offspring were sacrificed, and tissue samples were collected and prepared for histopathological and stereology studies. Glomerular abnormalities and reduced glomerular formation were observed in the BPA offspring. The kidneys of the BPA10 and BPA100 female offspring had a significantly lower glomerular number and density than those of the CONTROL female offspring. The glomerular histomorphometry revealed a significant difference between the female and male CONTROL offspring for the analysed glomerular parameters that disappeared in the BPA10 and BPA100 offspring. In addition, the kidney histopathological examination showed typical male cuboidal epithelial cells of the Bowman capsule in the female BPA offspring. Exposure to environmentally relevant doses of BPA during embryonic development altered nephrogenesis. These structural changes could be associated with an increased risk of developing cardiometabolic diseases later in life.

  10. A comparison of porosity analysis using 2D stereology estimates and 3D serial sectioning for additively manufactured Ti 6Al 2Sn 4Zr 2Mo alloy; Vergleich der Porositaetsanalyse einer Ti 6Al 2Sn 4Zr 2Mo-Legierung aus additiver Fertigung mittels stereologischer Schaetzungen (2D) und mit Serienschnitten (3D)

    Energy Technology Data Exchange (ETDEWEB)

    Ganti, Satya R.; Velez, Michael A.; Geier, Brian A.; Hayes, Brian J.; Turner, Bryan J.; Jenkins, Elizabeth J. [UES Inc., Dayton, OH (United States)

    2017-02-15

    Porosity is a typical defect in additively manufactured (AM) parts. Such defects limit the properties and performance of AM parts, and therefore need to be characterized accurately. Current methods for characterization of defects and microstructure rely on classical stereological methods that extrapolate information from two dimensional images. The automation of serial sectioning provides an opportunity to precisely and accurately quantify porosity in three dimensions in materials. In this work, we analyzed the porosity of an additively manufactured Ti 6Al 2Sn 4Zr 2Mo sample using Robo-Met.3D {sup registered}, an automated serial sectioning system. Image processing for three dimensional reconstruction of the serial-sectioned two dimensional images was performed using open source image analysis software (Fiji/ImageJ, Dream.3D, Paraview). The results from this 3D serial sectioning analysis were then compared to classical 2D stereological methods (Saltykov stereological theory). We found that for this dataset, the classical 2D methods underestimated the porosity size and distributions of the larger pores; a critical attribute to fatigue behavior of the AM part. The results suggest that acquiring experimental data with equipment such as Robo-Met.3D {sup registered} to measure the number and size of particles such as pores in a volume irrespective of knowing their shape is a better choice.

  11. Operator Bias in the Estimation of Arc Efficiency in Gas Tungsten Arc Welding

    Directory of Open Access Journals (Sweden)

    Fredrik Sikström

    2015-03-01

    Full Text Available In this paper the operator bias in the measurement process of arc efficiency in stationary direct current electrode negative gas tungsten arc welding is discussed. An experimental study involving 15 operators (enough to reach statistical significance has been carried out with the purpose to estimate the arc efficiency from a specific procedure for calorimetric experiments. The measurement procedure consists of three manual operations which introduces operator bias in the measurement process. An additional relevant experiment highlights the consequences of estimating the arc voltage by measuring the potential between the terminals of the welding power source instead of measuring the potential between the electrode contact tube and the workpiece. The result of the study is a statistical evaluation of the operator bias influence on the estimate, showing that operator bias is negligible in the estimate considered here. On the contrary the consequences of neglecting welding leads voltage drop results in a significant under estimation of the arc efficiency.

  12. Efficient semiparametric estimation in generalized partially linear additive models for longitudinal/clustered data

    KAUST Repository

    Cheng, Guang

    2014-02-01

    We consider efficient estimation of the Euclidean parameters in a generalized partially linear additive models for longitudinal/clustered data when multiple covariates need to be modeled nonparametrically, and propose an estimation procedure based on a spline approximation of the nonparametric part of the model and the generalized estimating equations (GEE). Although the model in consideration is natural and useful in many practical applications, the literature on this model is very limited because of challenges in dealing with dependent data for nonparametric additive models. We show that the proposed estimators are consistent and asymptotically normal even if the covariance structure is misspecified. An explicit consistent estimate of the asymptotic variance is also provided. Moreover, we derive the semiparametric efficiency score and information bound under general moment conditions. By showing that our estimators achieve the semiparametric information bound, we effectively establish their efficiency in a stronger sense than what is typically considered for GEE. The derivation of our asymptotic results relies heavily on the empirical processes tools that we develop for the longitudinal/clustered data. Numerical results are used to illustrate the finite sample performance of the proposed estimators. © 2014 ISI/BS.

  13. Ultrastructural and stereological analysis of trypanosomatidis of the genus Endotrypanum

    Directory of Open Access Journals (Sweden)

    Maurílio J. Soares

    1991-06-01

    Full Text Available Culture forms of four strains of Endotrypanum (E. schaudinni and E. monterogeii were processed for transmission electron microscopy and analyzed at the ultrastructural level. Quantitative data about some cytoplasmic organelles were obeined by stereology. All culture forms were promastigotes. In their cytoplasm four different organelles could be found: lipid inclusions (0,2-0,4 µm in diameter, mebrane-bounded vacuoles (0.10-0,28 µm in diameter, glycosomes (0,2-0,3 µm in diameter, and the mitochondrion. The kenetoplast appears as a thin band, except for the strain IM201, which possesses a broader structure, and possibly is not a member of this genus. Clusters of virus-like particles were seen in the cytoplasm of the strain LV88. The data obtained show that all strains have the typical morphological feature of the trypanosomatids. Only strain IM201 could be differentiated from the others, due to its larger kenetoplast-DNA network and its large mitochondrial and glycosomal relative volume. The morphometrical data did not allow the differentiation between E. schaudinni (strains IM217 and M6226 and E. monterogeii (strain LV88.

  14. Statistically and Computationally Efficient Estimating Equations for Large Spatial Datasets

    KAUST Repository

    Sun, Ying; Stein, Michael L.

    2014-01-01

    For Gaussian process models, likelihood based methods are often difficult to use with large irregularly spaced spatial datasets, because exact calculations of the likelihood for n observations require O(n3) operations and O(n2) memory. Various approximation methods have been developed to address the computational difficulties. In this paper, we propose new unbiased estimating equations based on score equation approximations that are both computationally and statistically efficient. We replace the inverse covariance matrix that appears in the score equations by a sparse matrix to approximate the quadratic forms, then set the resulting quadratic forms equal to their expected values to obtain unbiased estimating equations. The sparse matrix is constructed by a sparse inverse Cholesky approach to approximate the inverse covariance matrix. The statistical efficiency of the resulting unbiased estimating equations are evaluated both in theory and by numerical studies. Our methods are applied to nearly 90,000 satellite-based measurements of water vapor levels over a region in the Southeast Pacific Ocean.

  15. Statistically and Computationally Efficient Estimating Equations for Large Spatial Datasets

    KAUST Repository

    Sun, Ying

    2014-11-07

    For Gaussian process models, likelihood based methods are often difficult to use with large irregularly spaced spatial datasets, because exact calculations of the likelihood for n observations require O(n3) operations and O(n2) memory. Various approximation methods have been developed to address the computational difficulties. In this paper, we propose new unbiased estimating equations based on score equation approximations that are both computationally and statistically efficient. We replace the inverse covariance matrix that appears in the score equations by a sparse matrix to approximate the quadratic forms, then set the resulting quadratic forms equal to their expected values to obtain unbiased estimating equations. The sparse matrix is constructed by a sparse inverse Cholesky approach to approximate the inverse covariance matrix. The statistical efficiency of the resulting unbiased estimating equations are evaluated both in theory and by numerical studies. Our methods are applied to nearly 90,000 satellite-based measurements of water vapor levels over a region in the Southeast Pacific Ocean.

  16. Estimating the NIH efficient frontier.

    Science.gov (United States)

    Bisias, Dimitrios; Lo, Andrew W; Watkins, James F

    2012-01-01

    The National Institutes of Health (NIH) is among the world's largest investors in biomedical research, with a mandate to: "…lengthen life, and reduce the burdens of illness and disability." Its funding decisions have been criticized as insufficiently focused on disease burden. We hypothesize that modern portfolio theory can create a closer link between basic research and outcome, and offer insight into basic-science related improvements in public health. We propose portfolio theory as a systematic framework for making biomedical funding allocation decisions-one that is directly tied to the risk/reward trade-off of burden-of-disease outcomes. Using data from 1965 to 2007, we provide estimates of the NIH "efficient frontier", the set of funding allocations across 7 groups of disease-oriented NIH institutes that yield the greatest expected return on investment for a given level of risk, where return on investment is measured by subsequent impact on U.S. years of life lost (YLL). The results suggest that NIH may be actively managing its research risk, given that the volatility of its current allocation is 17% less than that of an equal-allocation portfolio with similar expected returns. The estimated efficient frontier suggests that further improvements in expected return (89% to 119% vs. current) or reduction in risk (22% to 35% vs. current) are available holding risk or expected return, respectively, constant, and that 28% to 89% greater decrease in average years-of-life-lost per unit risk may be achievable. However, these results also reflect the imprecision of YLL as a measure of disease burden, the noisy statistical link between basic research and YLL, and other known limitations of portfolio theory itself. Our analysis is intended to serve as a proof-of-concept and starting point for applying quantitative methods to allocating biomedical research funding that are objective, systematic, transparent, repeatable, and expressly designed to reduce the burden of

  17. The efficiency of different estimation methods of hydro-physical limits

    Directory of Open Access Journals (Sweden)

    Emma María Martínez

    2012-12-01

    Full Text Available The soil water available to crops is defined by specific values of water potential limits. Underlying the estimation of hydro-physical limits, identified as permanent wilting point (PWP and field capacity (FC, is the selection of a suitable method based on a multi-criteria analysis that is not always clear and defined. In this kind of analysis, the time required for measurements must be taken into consideration as well as other external measurement factors, e.g., the reliability and suitability of the study area, measurement uncertainty, cost, effort and labour invested. In this paper, the efficiency of different methods for determining hydro-physical limits is evaluated by using indices that allow for the calculation of efficiency in terms of effort and cost. The analysis evaluates both direct determination methods (pressure plate - PP and water activity meter - WAM and indirect estimation methods (pedotransfer functions - PTFs. The PTFs must be validated for the area of interest before use, but the time and cost associated with this validation are not included in the cost of analysis. Compared to the other methods, the combined use of PP and WAM to determine hydro-physical limits differs significantly in time and cost required and quality of information. For direct methods, increasing sample size significantly reduces cost and time. This paper assesses the effectiveness of combining a general analysis based on efficiency indices and more specific analyses based on the different influencing factors, which were considered separately so as not to mask potential benefits or drawbacks that are not evidenced in efficiency estimation.

  18. Shrinkage Estimators for Robust and Efficient Inference in Haplotype-Based Case-Control Studies

    KAUST Repository

    Chen, Yi-Hau; Chatterjee, Nilanjan; Carroll, Raymond J.

    2009-01-01

    Case-control association studies often aim to investigate the role of genes and gene-environment interactions in terms of the underlying haplotypes (i.e., the combinations of alleles at multiple genetic loci along chromosomal regions). The goal of this article is to develop robust but efficient approaches to the estimation of disease odds-ratio parameters associated with haplotypes and haplotype-environment interactions. We consider "shrinkage" estimation techniques that can adaptively relax the model assumptions of Hardy-Weinberg-Equilibrium and gene-environment independence required by recently proposed efficient "retrospective" methods. Our proposal involves first development of a novel retrospective approach to the analysis of case-control data, one that is robust to the nature of the gene-environment distribution in the underlying population. Next, it involves shrinkage of the robust retrospective estimator toward a more precise, but model-dependent, retrospective estimator using novel empirical Bayes and penalized regression techniques. Methods for variance estimation are proposed based on asymptotic theories. Simulations and two data examples illustrate both the robustness and efficiency of the proposed methods.

  19. Shrinkage Estimators for Robust and Efficient Inference in Haplotype-Based Case-Control Studies

    KAUST Repository

    Chen, Yi-Hau

    2009-03-01

    Case-control association studies often aim to investigate the role of genes and gene-environment interactions in terms of the underlying haplotypes (i.e., the combinations of alleles at multiple genetic loci along chromosomal regions). The goal of this article is to develop robust but efficient approaches to the estimation of disease odds-ratio parameters associated with haplotypes and haplotype-environment interactions. We consider "shrinkage" estimation techniques that can adaptively relax the model assumptions of Hardy-Weinberg-Equilibrium and gene-environment independence required by recently proposed efficient "retrospective" methods. Our proposal involves first development of a novel retrospective approach to the analysis of case-control data, one that is robust to the nature of the gene-environment distribution in the underlying population. Next, it involves shrinkage of the robust retrospective estimator toward a more precise, but model-dependent, retrospective estimator using novel empirical Bayes and penalized regression techniques. Methods for variance estimation are proposed based on asymptotic theories. Simulations and two data examples illustrate both the robustness and efficiency of the proposed methods.

  20. Stereological quantification of immune-competent cells in baseline biopsy specimens from achilles tendons

    DEFF Research Database (Denmark)

    Kragsnaes, Maja Skov; Fredberg, Ulrich; Stribolt, Katrine

    2014-01-01

    BACKGROUND: Limited data exist on the presence and function of immune-competent cells in chronic tendinopathic tendons and their potential role in inflammation and tissue healing as well as in predicting long-term outcome. PURPOSE: To quantify subtypes of immune-competent cells in biopsy specimens...... immunohistochemically by quantifying the presence of macrophages (CD68-PGM1(+), CD68-KP1(+)), hemosiderophages (Perls blue), T lymphocytes (CD2(+), CD3(+), CD4(+), CD7(+), CD8(+)), B lymphocytes (CD20(+)), natural killer cells (CD56(+)), mast cells (NaSDCl(+)), Schwann cells (S100(+)), and endothelial cells (CD34......(+)) using a stereological technique. A follow-up examination was conducted more than 4 years (range, 4-9 years) after the biopsy procedure to evaluate the long-term presence of Achilles tendon symptoms. RESULTS: Macrophages, T lymphocytes, mast cells, and natural killer cells were observed in the majority...

  1. Efficient estimation of diffusion during dendritic solidification

    Science.gov (United States)

    Yeum, K. S.; Poirier, D. R.; Laxmanan, V.

    1989-01-01

    A very efficient finite difference method has been developed to estimate the solute redistribution during solidification with diffusion in the solid. This method is validated by comparing the computed results with the results of an analytical solution derived by Kobayashi (1988) for the assumptions of a constant diffusion coefficient, a constant equilibrium partition ratio, and a parabolic rate of the advancement of the solid/liquid interface. The flexibility of the method is demonstrated by applying it to the dendritic solidification of a Pb-15 wt pct Sn alloy, for which the equilibrium partition ratio and diffusion coefficient vary substantially during solidification. The fraction eutectic at the end of solidification is also obtained by estimating the fraction solid, in greater resolution, where the concentration of solute in the interdendritic liquid reaches the eutectic composition of the alloy.

  2. Efficient channel estimation in massive MIMO systems - a distributed approach

    KAUST Repository

    Al-Naffouri, Tareq Y.

    2016-01-21

    We present two efficient algorithms for distributed estimation of channels in massive MIMO systems. The two cases of 1) generic, and 2) sparse channels is considered. The algorithms estimate the impulse response for each channel observed by the antennas at the receiver (base station) in a coordinated manner by sharing minimal information among neighboring antennas. Simulations demonstrate the superior performance of the proposed methods as compared to other methods.

  3. Computationally Efficient and Noise Robust DOA and Pitch Estimation

    DEFF Research Database (Denmark)

    Karimian-Azari, Sam; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2016-01-01

    Many natural signals, such as voiced speech and some musical instruments, are approximately periodic over short intervals. These signals are often described in mathematics by the sum of sinusoids (harmonics) with frequencies that are proportional to the fundamental frequency, or pitch. In sensor...... a joint DOA and pitch estimator. In white Gaussian noise, we derive even more computationally efficient solutions which are designed using the narrowband power spectrum of the harmonics. Numerical results reveal the performance of the estimators in colored noise compared with the Cram\\'{e}r-Rao lower...

  4. Stereologic, histopathologic, flow cytometric, and clinical parameters in the prognostic evaluation of 74 patients with intraoral squamous cell carcinomas

    DEFF Research Database (Denmark)

    Bundgaard, T; Sørensen, Flemming Brandt; Gaihede, M

    1992-01-01

    , tumor size, and the TNM classification. RESULTS: The investigation showed a significant difference between the volume-weighted mean nuclear volume (nuclear vv) of oral leukoplakia (n = 29) and oral squamous cell carcinomas (P = 0.001). The value of the parameters as prognostic indicators of survival......BACKGROUND AND METHODS: A consecutive series of all 78 incident cases of intraoral squamous cell carcinoma occurring during a 2-year period in a population of 1.4 million inhabitants were evaluated by histologic score (the modified classification of Jacobsson et al.), flow cytometry, stereology...

  5. Effect of Urtica dioica on morphometric indices of kidney in streptozotocin diabetic rats--a stereological study.

    Science.gov (United States)

    Golalipour, Mohammad Jafar; Gharravi, Anneh Mohammad; Ghafari, Sorya; Afshar, Mohammad

    2007-11-01

    The aim of the present study was to investigate the effect of Urtica dioica on Morphometric indices of kidney in diabetic rats. Thirty male adult albino wistar rats of 125-175 g divided into control, diabetic and Urtica dioica treatment groups. In treatment Group, diabetic rats received 100 mg kg(-1) daily hydroalcoholic extract of U. dioica intraperitoneally for 4 weeks. After the animals had been sacrified, the kidneys were removed and fixed by formaldehyde, cut horizontally into 1 mm slices and processed, Stained with H and E. Stereological study performed using light microscope and the image projected on a table of olysa software. Cavalieri principle was used to estimate the volume of cortex, medulla and whole kidney. All the grouped data statistically evaluated using Student's t-test, expressed as the Mean +/- SE. Ration of kidney weight/body weight in diabetes (0.51) and diabetes-extract group (0.67) were higher then control group (0.42). Ratio of kidney volume/body weight in diabetes (350) and diabetes-extract group (348) were higher then control group (323). Volume Ratio of cortex/medulla in diabetes-extract group (1.65) was higher then control (1.34) and diabetes group (1.33). Glomerular area and diameter and proximal tubule diameter in diabetes-Extract group was higher than control and diabetes groups. This study revealed that Urtica dioica has no effect on renal morphometric indices in induced diabetic rats.

  6. x-y-recording in transmission electron microscopy. A versatile and inexpensive interface to personal computers with application to stereology.

    Science.gov (United States)

    Rickmann, M; Siklós, L; Joó, F; Wolff, J R

    1990-09-01

    An interface for IBM XT/AT-compatible computers is described which has been designed to read the actual specimen stage position of electron microscopes. The complete system consists of (i) optical incremental encoders attached to the x- and y-stage drivers of the microscope, (ii) two keypads for operator input, (iii) an interface card fitted to the bus of the personal computer, (iv) a standard configuration IBM XT (or compatible) personal computer optionally equipped with a (v) HP Graphic Language controllable colour plotter. The small size of the encoders and their connection to the stage drivers by simple ribbed belts allows an easy adaptation of the system to most electron microscopes. Operation of the interface card itself is supported by any high-level language available for personal computers. By the modular concept of these languages, the system can be customized to various applications, and no computer expertise is needed for actual operation. The present configuration offers an inexpensive attachment, which covers a wide range of applications from a simple notebook to high-resolution (200-nm) mapping of tissue. Since section coordinates can be processed in real-time, stereological estimations can be derived directly "on microscope". This is exemplified by an application in which particle numbers were determined by the disector method.

  7. Immunocytochemical and stereological analysis of GABA(B) receptor subunit expression in the rat vestibular nucleus following unilateral vestibular deafferentation.

    Science.gov (United States)

    Zhang, Rong; Ashton, John; Horii, Arata; Darlington, Cynthia L; Smith, Paul F

    2005-03-10

    The process of behavioral recovery that occurs following damage to one vestibular labyrinth, vestibular compensation, has been attributed in part to a down-regulation of GABA(B) receptors in the vestibular nucleus complex (VNC) ipsilateral to the lesion, which could potentially reduce commissural inhibition from the contralateral VNC. In this study, we tested the possibility that this occurs through a decrease in the expression of either the GABA(B1) or GABA(B2) subunits of the GABA(B) receptor. We used Western blotting to quantify the expression of these subunits in the VNC at 10 h and 50 h following unilateral vestibular deafferentation (UVD) or sham surgery in rats. We then used immunocytochemistry and stereological counting methods to estimate the number of neurons expressing these subunits in the MVN at 10 h and 2 weeks following UVD or sham surgery. Compared to sham controls, we found no significant changes in either the expression of the two GABA(B) receptor subunits in the VNC or in the number of MVN neurons expressing these GABA(B) receptor subunits post-UVD. These results suggest that GABA(B) receptor expression does not change substantially in the VNC during the process of vestibular compensation.

  8. Estimating the NIH efficient frontier.

    Directory of Open Access Journals (Sweden)

    Dimitrios Bisias

    Full Text Available BACKGROUND: The National Institutes of Health (NIH is among the world's largest investors in biomedical research, with a mandate to: "…lengthen life, and reduce the burdens of illness and disability." Its funding decisions have been criticized as insufficiently focused on disease burden. We hypothesize that modern portfolio theory can create a closer link between basic research and outcome, and offer insight into basic-science related improvements in public health. We propose portfolio theory as a systematic framework for making biomedical funding allocation decisions-one that is directly tied to the risk/reward trade-off of burden-of-disease outcomes. METHODS AND FINDINGS: Using data from 1965 to 2007, we provide estimates of the NIH "efficient frontier", the set of funding allocations across 7 groups of disease-oriented NIH institutes that yield the greatest expected return on investment for a given level of risk, where return on investment is measured by subsequent impact on U.S. years of life lost (YLL. The results suggest that NIH may be actively managing its research risk, given that the volatility of its current allocation is 17% less than that of an equal-allocation portfolio with similar expected returns. The estimated efficient frontier suggests that further improvements in expected return (89% to 119% vs. current or reduction in risk (22% to 35% vs. current are available holding risk or expected return, respectively, constant, and that 28% to 89% greater decrease in average years-of-life-lost per unit risk may be achievable. However, these results also reflect the imprecision of YLL as a measure of disease burden, the noisy statistical link between basic research and YLL, and other known limitations of portfolio theory itself. CONCLUSIONS: Our analysis is intended to serve as a proof-of-concept and starting point for applying quantitative methods to allocating biomedical research funding that are objective, systematic, transparent

  9. Estimating the NIH Efficient Frontier

    Science.gov (United States)

    2012-01-01

    Background The National Institutes of Health (NIH) is among the world’s largest investors in biomedical research, with a mandate to: “…lengthen life, and reduce the burdens of illness and disability.” Its funding decisions have been criticized as insufficiently focused on disease burden. We hypothesize that modern portfolio theory can create a closer link between basic research and outcome, and offer insight into basic-science related improvements in public health. We propose portfolio theory as a systematic framework for making biomedical funding allocation decisions–one that is directly tied to the risk/reward trade-off of burden-of-disease outcomes. Methods and Findings Using data from 1965 to 2007, we provide estimates of the NIH “efficient frontier”, the set of funding allocations across 7 groups of disease-oriented NIH institutes that yield the greatest expected return on investment for a given level of risk, where return on investment is measured by subsequent impact on U.S. years of life lost (YLL). The results suggest that NIH may be actively managing its research risk, given that the volatility of its current allocation is 17% less than that of an equal-allocation portfolio with similar expected returns. The estimated efficient frontier suggests that further improvements in expected return (89% to 119% vs. current) or reduction in risk (22% to 35% vs. current) are available holding risk or expected return, respectively, constant, and that 28% to 89% greater decrease in average years-of-life-lost per unit risk may be achievable. However, these results also reflect the imprecision of YLL as a measure of disease burden, the noisy statistical link between basic research and YLL, and other known limitations of portfolio theory itself. Conclusions Our analysis is intended to serve as a proof-of-concept and starting point for applying quantitative methods to allocating biomedical research funding that are objective, systematic, transparent

  10. Environmental efficiency with multiple environmentally detrimental variables : estimated with SFA and DEA

    NARCIS (Netherlands)

    Reinhard, S.; Lovell, C.A.K.; Thijssen, G.J.

    2000-01-01

    The objective of this paper is to estimate comprehensive environmental efficiency measures for Dutch dairy farms. The environmental efficiency scores are based on the nitrogen surplus, phosphate surplus and the total (direct and indirect) energy use of an unbalanced panel of dairy farms. We define

  11. LocExpress: a web server for efficiently estimating expression of novel transcripts.

    Science.gov (United States)

    Hou, Mei; Tian, Feng; Jiang, Shuai; Kong, Lei; Yang, Dechang; Gao, Ge

    2016-12-22

    The temporal and spatial-specific expression pattern of a transcript in multiple tissues and cell types can indicate key clues about its function. While several gene atlas available online as pre-computed databases for known gene models, it's still challenging to get expression profile for previously uncharacterized (i.e. novel) transcripts efficiently. Here we developed LocExpress, a web server for efficiently estimating expression of novel transcripts across multiple tissues and cell types in human (20 normal tissues/cells types and 14 cell lines) as well as in mouse (24 normal tissues/cell types and nine cell lines). As a wrapper to RNA-Seq quantification algorithm, LocExpress efficiently reduces the time cost by making abundance estimation calls increasingly within the minimum spanning bundle region of input transcripts. For a given novel gene model, such local context-oriented strategy allows LocExpress to estimate its FPKMs in hundreds of samples within minutes on a standard Linux box, making an online web server possible. To the best of our knowledge, LocExpress is the only web server to provide nearly real-time expression estimation for novel transcripts in common tissues and cell types. The server is publicly available at http://loc-express.cbi.pku.edu.cn .

  12. Efficient semiparametric estimation in generalized partially linear additive models for longitudinal/clustered data

    KAUST Repository

    Cheng, Guang; Zhou, Lan; Huang, Jianhua Z.

    2014-01-01

    We consider efficient estimation of the Euclidean parameters in a generalized partially linear additive models for longitudinal/clustered data when multiple covariates need to be modeled nonparametrically, and propose an estimation procedure based

  13. Stereological estimation of nuclear volume in benign melanocytic lesions and cutaneous malignant melanomas

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt

    1989-01-01

    a favorable prognosis. No significant differences in vV could be demonstrated among different noninvasive tumor types. Two-dimensional estimates only distinguished benign from malignant tumors with considerable overlap and with significantly varying influence from other factors among different benign lesional...

  14. Public-Private Investment Partnerships: Efficiency Estimation Methods

    Directory of Open Access Journals (Sweden)

    Aleksandr Valeryevich Trynov

    2016-06-01

    Full Text Available The article focuses on assessing the effectiveness of investment projects implemented on the principles of public-private partnership (PPP. This article puts forward the hypothesis that the inclusion of multiplicative economic effects will increase the attractiveness of public-private partnership projects, which in turn will contribute to the more efficient use of budgetary resources. The author proposed a methodological approach and methods of evaluating the economic efficiency of PPP projects. The author’s technique is based upon the synthesis of approaches to evaluation of the project implemented in the private and public sector and in contrast to the existing methods allows taking into account the indirect (multiplicative effect arising during the implementation of project. In the article, to estimate the multiplier effect, the model of regional economy — social accounting matrix (SAM was developed. The matrix is based on the data of the Sverdlovsk region for 2013. In the article, the genesis of the balance models of economic systems is presented. The evolution of balance models in the Russian (Soviet and foreign sources from their emergence up to now are observed. It is shown that SAM is widely used in the world for a wide range of applications, primarily to assess the impact on the regional economy of various exogenous factors. In order to clarify the estimates of multiplicative effects, the disaggregation of the account of the “industry” of the matrix of social accounts was carried out in accordance with the All-Russian Classifier of Types of Economic Activities (OKVED. This step allows to consider the particular characteristics of the industry of the estimated investment project. The method was tested on the example of evaluating the effectiveness of the construction of a toll road in the Sverdlovsk region. It is proved that due to the multiplier effect, the more capital-intensive version of the project may be more beneficial in

  15. Stereological estimation of total cell numbers in the human cerebral and cerebellar cortex

    DEFF Research Database (Denmark)

    Walløe, Solveig; Pakkenberg, Bente; Fabricius, Katrine

    2014-01-01

    estimates and were often very time-consuming. Within the last 20-30 years, it has become possible to rely on more advanced and unbiased methods. These methods have provided us with information about fetal brain development, differences in cell numbers between men and women, the effect of age on selected...

  16. Use of flow cytometry for high-throughput cell population estimates in fixed brain tissue

    Directory of Open Access Journals (Sweden)

    Nicole A Young

    2012-07-01

    Full Text Available The numbers and types of cells in an area of cortex define its function. Therefore it is essential to characterize the numbers and distributions of total cells in areas of the cortex, as well as to identify numbers of subclasses of neurons and glial cells. To date, the large size of the primate brain and the lack of innovation in cell counting methods have been a roadblock to obtaining high-resolution maps of cell and neuron density across the cortex in humans and non-human primates. Stereological counting methods and the isotropic fractionator are valuable tools for estimating cell numbers, but are better suited to smaller, well-defined brain structures or to cortex as a whole. In the present study, we have extended our flow-cytometry based counting method, the flow fractionator (Collins et al., 2010a, to include high-throughput total cell population estimates in homogenized cortical samples. We demonstrate that our method produces consistent, accurate and repeatable cell estimates quickly. The estimates we report are in excellent agreement with estimates for the same samples obtained using a Neubauer chamber and a fluorescence microscope. We show that our flow cytometry-based method for total cell estimation in homogenized brain tissue is more efficient and more precise than manual counting methods. The addition of automated nuclei counting to our flow fractionator method allows for a fully automated, rapid characterization of total cells and neuronal and non-neuronal populations in human and non-human primate brains, providing valuable data to further our understanding of the functional organization of normal, aging and diseased brains.

  17. Unbiased estimation of human body composition by the Cavalieri method using magnetic resonance imaging

    International Nuclear Information System (INIS)

    Roberts, N.; Reid, N.M.K.; Brodie, D.A.; Bourne, M.; Edwards, R.H.T.; Cruz-Orive, L.M.

    1993-01-01

    The classical methods for estimating the volume of human body compartments in vivo (e.g. skin-fold thickness for fat, radioisotope counting for different compartments, etc.) are generally indirect and rely on essentially empirical relationships - hence they are biased to unknown degrees. The advent of modern non-invasive scanning techniques, such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) is now widening the scope of volume quantification, especially in combination with stereological methods. Apart from its superior soft tissue contrast, MRI enjoys the distinct advantage of not using ionizing radiations. By a proper landmarking and control of the scanner couch, an adult male volunteer was scanned exhaustively into parallel systematic MR ''sections''. Four compartments were defined, namely bone, muscle, organs and fat (which included the skin), and their corresponding volumes were easily and efficiently estimated by the Cavalieri method: the total section area of a compartment times the section interval estimates the volume of the compartment without bias. Formulae and nomograms are given to predict the errors and to optimize the design. To estimate an individual's muscle volume with a 5% coefficient of error, 10 sections and less than 10 min point counting (to estimate the relevant section areas) are required. Bone and fat require about twice as much work. To estimate the mean muscle volume of a population with the same error contribution, from a random sample of six subjects, the workload per subject can be divided by √ 6, namely 4 min per subject. For a given number of sections planimetry would be as accurate but far more time consuming than point counting. (author)

  18. Efficient and robust estimation for longitudinal mixed models for binary data

    DEFF Research Database (Denmark)

    Holst, René

    2009-01-01

    This paper proposes a longitudinal mixed model for binary data. The model extends the classical Poisson trick, in which a binomial regression is fitted by switching to a Poisson framework. A recent estimating equations method for generalized linear longitudinal mixed models, called GEEP, is used...... as a vehicle for fitting the conditional Poisson regressions, given a latent process of serial correlated Tweedie variables. The regression parameters are estimated using a quasi-score method, whereas the dispersion and correlation parameters are estimated by use of bias-corrected Pearson-type estimating...... equations, using second moments only. Random effects are predicted by BLUPs. The method provides a computationally efficient and robust approach to the estimation of longitudinal clustered binary data and accommodates linear and non-linear models. A simulation study is used for validation and finally...

  19. Proliferation of Sertoli cells during development of the human testis assessed by stereological methods

    DEFF Research Database (Denmark)

    Cortes, D; Müller, J; Skakkebaek, N E

    1987-01-01

    Sertoli cells were studied using stereological methods in testes obtained from five children who were stillborn, and 31 individuals between 3 months and 40 years of age, who had suffered from sudden, unexpected death. The mean nuclear volume of the Sertoli cells, the numerical density of Sertoli...... cells, and the total number of Sertoli cells per individual were determined by point- and profile-counting of 0.5 micron sections. The nuclear volume of Sertoli cells increased from a median of 120 microns3 (range 53-130) during the period of 3 months to 10 years to 210 microns3 (170-260) in adults...... (greater than 25 years). The numerical density of Sertoli cells decreased from a median of 1200 X 10(6)/cm3 (870-1400) during childhood (3 months to 10 years) to 140 X 10(6)/cm3 (110-260) in adults (greater than 25 years). The total number of Sertoli cells per individual increased significantly from...

  20. The relative efficiency of three methods of estimating herbage mass ...

    African Journals Online (AJOL)

    The methods involved were randomly placed circular quadrats; randomly placed narrow strips; and disc meter sampling. Disc meter and quadrat sampling appear to be more efficient than strip sampling. In a subsequent small plot grazing trial the estimates of herbage mass, using the disc meter, had a consistent precision ...

  1. FIRST USE OF STEREOLOGY TO QUANTIFY THE SURVIVAL OF FAT AUTOGRAFTS

    Directory of Open Access Journals (Sweden)

    Eduardo Serna Cuéllar

    2011-05-01

    Full Text Available It is not usual to perform quantitative analyses on surgical materials. Rather, they are evaluated clinically, through qualitative methods, and if quantitation is done, it is on a 2-dimensional basis. In this study, the long-term survival of fat autografts (FAG in 40 subjects with facial soft tissue defects is quantified. An adipose tissue preparation from the abdomen obtained through liposuction and centrifugation is injected subcutaneously. Approximately 14 months later, the treated area is biopsied. Extensive computer-based histological analyses were performed using the stereological method in order to directly obtain three parameters: volume fraction of adipocytes in the fat tissue (VV, density (number per volume of adipocytes in the fat tissue (NV, and the mean cell volume of adipocytes (VA in each tissue sample. A set of equations based on these three quantitative parameters is produced for evaluation of the volumetric survival fraction (VSF of FAG. The presented data evidenced a 66% survival fraction at the 14-month follow-up. In routine practice, it would be sufficient to perform this volumetric analysis on the injected and biopsied fat samples to know what fraction of the FAG has survived. This is an objective method for quantifying FAG survival and will allow a standardized comparison between different research series and authors.

  2. The role of efficiency estimates in regulatory price reviews: Ofgem's approach to benchmarking electricity networks

    International Nuclear Information System (INIS)

    Pollitt, Michael

    2005-01-01

    Electricity regulators around the world make use of efficiency analysis (or benchmarking) to produce estimates of the likely amount of cost reduction which regulated electric utilities can achieve. This short paper examines the use of such efficiency estimates by the UK electricity regulator (Ofgem) within electricity distribution and transmission price reviews. It highlights the place of efficiency analysis within the calculation of X factors. We suggest a number of problems with the current approach and make suggestions for the future development of X factor setting. (author)

  3. Stereological study of the effect of ginger's alcoholic extract on the testis in busulfan-induced infertility in rats

    Directory of Open Access Journals (Sweden)

    Hossein Bordbar

    2013-06-01

    Full Text Available Background: In traditional medicine zingiber officinale used to regulate female menstural cycle and treat male infertility. Recent studies have suggested the possible role of ginger extract in improving the testicular damage of busulfan. Objective: The aim of this study was to evaluate the effects of zingiber officinale on the sperm parameters, testosterone level and the volume of the testes and seminiferous tubules by stereological methods. Materials and Methods: Fifty rats were divided into four groups. All the rats were given a single intraperitoneally injection of 5mg/kg busulfan solution. The first group was kept as busulfan control, while the other groups were orally administrated ginger extract in graded doses of 50, 100 and 150mg/kg b.wt, for 48 consecutive days. At the end, all animals were anesthetized and their testes and vas deference were removed, fixed, embedded, and stained. The volume of testes and seminiferous tubules were estimated by cavalieri methods. Results: The result showed, that zingiber officinale increased the volumes of seminiferous tubule in 100mg/kg treated group compared to control group. Sperm count (706×105 and 682×105 and the level of testosterone (50.90 ng/mL and 54.10 ng/mL enhanced in 100 mg/kg and 150 mg/kg treated groups compared to control group (p=0.00. Conclusion: It seems that zingiber officinale stimulate male reproductive system in induce busulfan infertility

  4. A harmonized calculation model for transforming EU bottom-up energy efficiency indicators into empirical estimates of policy impacts

    International Nuclear Information System (INIS)

    Horowitz, Marvin J.; Bertoldi, Paolo

    2015-01-01

    This study is an impact analysis of European Union (EU) energy efficiency policy that employs both top-down energy consumption data and bottom-up energy efficiency statistics or indicators. As such, it may be considered a contribution to the effort called for in the EU's 2006 Energy Services Directive (ESD) to develop a harmonized calculation model. Although this study does not estimate the realized savings from individual policy measures, it does provide estimates of realized energy savings for energy efficiency policy measures in aggregate. Using fixed effects panel models, the annual cumulative savings in 2011 of combined household and manufacturing sector electricity and natural gas usage attributed to EU energy efficiency policies since 2000 is estimated to be 1136 PJ; the savings attributed to energy efficiency policies since 2006 is estimated to be 807 PJ, or the equivalent of 5.6% of 2011 EU energy consumption. As well as its contribution to energy efficiency policy analysis, this study adds to the development of methods that can improve the quality of information provided by standardized energy efficiency and sustainable resource indexes. - Highlights: • Impact analysis of European Union energy efficiency policy. • Harmonization of top-down energy consumption and bottom-up energy efficiency indicators. • Fixed effects models for Member States for household and manufacturing sectors and combined electricity and natural gas usage. • EU energy efficiency policies since 2000 are estimated to have saved 1136 Petajoules. • Energy savings attributed to energy efficiency policies since 2006 are 5.6 percent of 2011 combined electricity and natural gas usage.

  5. ESTIMATION OF EFFICIENCY PARTNERSHIP LARGE AND SMALL BUSINESS

    Directory of Open Access Journals (Sweden)

    Олег Васильевич Чабанюк

    2014-05-01

    Full Text Available In this  article, based on the definition of key factors and its components, developed an algorithm consistent, logically connected stages of the transition from the traditional enterprise to enterprise innovation typebased becoming intrapreneurship. Аnalysis of economic efficiency of innovative business idea is: based on the determination of experts the importance of the model parameters ensure the effectiveness of intrapreneurship by using methods of kvalimetricheskogo modeling expert estimates score calculated "efficiency intrapreneurship". On the author's projected optimum level indicator should exceed 0.5, but it should be noted that the achievement of this level is possible with the 2 - 3rd year of existence intraprenerskoy structure. The proposed method was tested in practice and can be used for the formation of intrapreneurship in large and medium-sized enterprises as one of the methods of implementation of the innovation activities of small businesses.DOI: http://dx.doi.org/10.12731/2218-7405-2013-10-50

  6. Efficient Smoothed Concomitant Lasso Estimation for High Dimensional Regression

    Science.gov (United States)

    Ndiaye, Eugene; Fercoq, Olivier; Gramfort, Alexandre; Leclère, Vincent; Salmon, Joseph

    2017-10-01

    In high dimensional settings, sparse structures are crucial for efficiency, both in term of memory, computation and performance. It is customary to consider ℓ 1 penalty to enforce sparsity in such scenarios. Sparsity enforcing methods, the Lasso being a canonical example, are popular candidates to address high dimension. For efficiency, they rely on tuning a parameter trading data fitting versus sparsity. For the Lasso theory to hold this tuning parameter should be proportional to the noise level, yet the latter is often unknown in practice. A possible remedy is to jointly optimize over the regression parameter as well as over the noise level. This has been considered under several names in the literature: Scaled-Lasso, Square-root Lasso, Concomitant Lasso estimation for instance, and could be of interest for uncertainty quantification. In this work, after illustrating numerical difficulties for the Concomitant Lasso formulation, we propose a modification we coined Smoothed Concomitant Lasso, aimed at increasing numerical stability. We propose an efficient and accurate solver leading to a computational cost no more expensive than the one for the Lasso. We leverage on standard ingredients behind the success of fast Lasso solvers: a coordinate descent algorithm, combined with safe screening rules to achieve speed efficiency, by eliminating early irrelevant features.

  7. Commercial Discount Rate Estimation for Efficiency Standards Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, K. Sydny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-04-13

    Underlying each of the Department of Energy's (DOE's) federal appliance and equipment standards are a set of complex analyses of the projected costs and benefits of regulation. Any new or amended standard must be designed to achieve significant additional energy conservation, provided that it is technologically feasible and economically justified (42 U.S.C. 6295(o)(2)(A)). A proposed standard is considered economically justified when its benefits exceed its burdens, as represented by the projected net present value of costs and benefits. DOE performs multiple analyses to evaluate the balance of costs and benefits of commercial appliance and equipment e efficiency standards, at the national and individual building or business level, each framed to capture different nuances of the complex impact of standards on the commercial end user population. The Life-Cycle Cost (LCC) analysis models the combined impact of appliance first cost and operating cost changes on a representative commercial building sample in order to identify the fraction of customers achieving LCC savings or incurring net cost at the considered efficiency levels.1 Thus, the choice of commercial discount rate value(s) used to calculate the present value of energy cost savings within the Life-Cycle Cost model implicitly plays a key role in estimating the economic impact of potential standard levels.2 This report is intended to provide a more in-depth discussion of the commercial discount rate estimation process than can be readily included in standard rulemaking Technical Support Documents (TSDs).

  8. RATIO ESTIMATORS FOR THE CO-EFFICIENT OF VARIATION IN A FINITE POPULATION

    Directory of Open Access Journals (Sweden)

    Archana V

    2011-04-01

    Full Text Available The Co-efficient of variation (C.V is a relative measure of dispersion and is free from unit of measurement. Hence it is widely used by the scientists in the disciplines of agriculture, biology, economics and environmental science. Although a lot of work has been reported in the past for the estimation of population C.V in infinite population models, they are not directly applicable for the finite populations. In this paper we have proposed six new estimators of the population C.V in finite population using ratio and product type estimators. The bias and mean square error of these estimators are derived for the simple random sampling design. The performance of the estimators is compared using a real life dataset. The ratio estimator using the information on the population C.V of the auxiliary variable emerges as the best estimator

  9. Efficient AM Algorithms for Stochastic ML Estimation of DOA

    Directory of Open Access Journals (Sweden)

    Haihua Chen

    2016-01-01

    Full Text Available The estimation of direction-of-arrival (DOA of signals is a basic and important problem in sensor array signal processing. To solve this problem, many algorithms have been proposed, among which the Stochastic Maximum Likelihood (SML is one of the most concerned algorithms because of its high accuracy of DOA. However, the estimation of SML generally involves the multidimensional nonlinear optimization problem. As a result, its computational complexity is rather high. This paper addresses the issue of reducing computational complexity of SML estimation of DOA based on the Alternating Minimization (AM algorithm. We have the following two contributions. First using transformation of matrix and properties of spatial projection, we propose an efficient AM (EAM algorithm by dividing the SML criterion into two components. One depends on a single variable parameter while the other does not. Second when the array is a uniform linear array, we get the irreducible form of the EAM criterion (IAM using polynomial forms. Simulation results show that both EAM and IAM can reduce the computational complexity of SML estimation greatly, while IAM is the best. Another advantage of IAM is that this algorithm can avoid the numerical instability problem which may happen in AM and EAM algorithms when more than one parameter converges to an identical value.

  10. A possible approach to estimating the operational efficiency of multiprocessor systems

    International Nuclear Information System (INIS)

    Kuznetsov, N.Y.; Gorlach, S.P.; Sumskaya, A.A.

    1984-01-01

    This article presents a mathematical model that constructs the upper and lower estimates evaluating the efficiency of solution of a large class of problems using a multiprocessor system with a specific architecture. Efficiency depends on a system's architecture (e.g., the number of processors, memory volume, the number of communication links, commutation speed) and the types of problems it is intended to solve. The behavior of the model is considered in a stationary mode. The model is used to evaluate the efficiency of a particular algorithm implemented in a multiprocessor system. It is concluded that the model is flexible and enables the investigation of a broad class of problems in computational mathematics, including linear algebra and boundary-value problems of mathematical physics

  11. Design-based stereological analysis of the lung parenchymal architecture and alveolar type II cells in surfactant protein A and D double deficient mice

    DEFF Research Database (Denmark)

    Jung, A; Allen, L; Nyengaard, Jens Randel

    2005-01-01

    Alveolar epithelial type II cells synthesize and secrete surfactant. The surfactant-associated proteins A and D (SP-A and SP-D), members of the collectin protein family, participate in pulmonary immune defense, modulation of inflammation, and surfactant metabolism. Both proteins are known to have......, but the mean volume of a single lamellar body remains constant. These results demonstrate that chronic deficiency of SP-A and SP-D in mice leads to parenchymal remodeling, type II cell hyperplasia and hypertrophy, and disturbed intracellular surfactant metabolism. The design-based stereological approach...

  12. Stereological estimation of total cell numbers in the young human utricular macula

    DEFF Research Database (Denmark)

    Severinsen, Stig Avall; Sørensen, Mads Sølvsten; Kirkegaard, Mette

    2010-01-01

    Abstract Conclusion: There is no change in the total cell population and hair cell:supporting cell ratio in the human utricular macula from gestational week 16 and onwards, whereas the lower hair cell:supporting cell ratio and lower total number of cells in the youngest specimens indicate...... that the utricle is still differentiating and adding new cells at the 10th to 12th gestational week. Objectives: Archival temporal bones were investigated to quantify cell numbers in the utricular macula in fetuses and children. Methods: The age of the subjects ranged from gestational week 10 to 15 years....... The optical fractionator was used to estimate the total number of cells in the utricular macula. Results: The total cell number was found to be 143 000 in subjects older than gestational week 16. The number of hair cells and supporting cells did not change between the 16th gestational week and 15 years...

  13. Mast cells and atopic dermatitis. Stereological quantification of mast cells in atopic dermatitis and normal human skin

    DEFF Research Database (Denmark)

    Damsgaard, T E; Olesen, A B; Sørensen, Flemming Brandt

    1997-01-01

    Stereological quantification of mast cell numbers was applied to sections of punch biopsies from lesional and nonlesional skin of atopic dermatitis patients and skin of healthy volunteers. We also investigated whether the method of staining and/or the fixative influenced the results...... of the determination of the mast cell profile numbers. The punch biopsies were taken from the same four locations in both atopic dermatitis patients and normal individuals. The locations were the scalp, neck and flexure of the elbow (lesional skin), and nates (nonlesional skin). Clinical scoring was carried out...... yielded the following results: (1) in atopic dermatitis lesional skin an increased number of mast cell profiles was found as compared with nonlesional skin, (2) comparing atopic dermatitis skin with normal skin, a significantly increased number of mast cell profiles per millimetre squared was found...

  14. Mast cells and atopic dermatitis. Stereological quantification of mast cells in atopic dermatitis and normal human skin

    DEFF Research Database (Denmark)

    Damsgaard, T E; Olesen, A B; Sørensen, Flemming Brandt

    1997-01-01

    Stereological quantification of mast cell numbers was applied to sections of punch biopsies from lesional and nonlesional skin of atopic dermatitis patients and skin of healthy volunteers. We also investigated whether the method of staining and/or the fixative influenced the results...... of the determination of the mast cell profile numbers. The punch biopsies were taken from the same four locations in both atopic dermatitis patients and normal individuals. The locations were the scalp, neck and flexure of the elbow (lesional skin), and nates (nonlesional skin). Clinical scoring was carried out...... at the site of each biopsy. After fixation and plastic embedding, the biopsies were cut into 2 microns serial sections. Ten sections, 30 microns apart, from each biopsy were examined and stained alternately with either toluidine blue or Giemsa stain and mast cell profile numbers were determined. The study...

  15. A virtually blind spectrum efficient channel estimation technique for mimo-ofdm system

    International Nuclear Information System (INIS)

    Ullah, M.O.

    2015-01-01

    Multiple-Input Multiple-Output antennas in conjunction with Orthogonal Frequency-Division Multiplexing is a dominant air interface for 4G and 5G cellular communication systems. Additionally, MIMO- OFDM based air interface is the foundation for latest wireless Local Area Networks, wireless Personal Area Networks, and digital multimedia broadcasting. Whether it is a single antenna or a multi-antenna OFDM system, accurate channel estimation is required for coherent reception. Training-based channel estimation methods require multiple pilot symbols and therefore waste a significant portion of channel bandwidth. This paper describes a virtually blind spectrum efficient channel estimation scheme for MIMO-OFDM systems which operates well below the Nyquist criterion. (author)

  16. Applied tensor stereology

    DEFF Research Database (Denmark)

    Ziegel, Johanna; Nyengaard, Jens Randel; Jensen, Eva B. Vedel

    In the present paper, statistical procedures for estimating shape and orientation of arbitrary three-dimensional particles are developed. The focus of this work is on the case where the particles cannot be observed directly, but only via sections. Volume tensors are used for describing particle s...

  17. Estimation of energy efficiency of residential buildings

    Directory of Open Access Journals (Sweden)

    Glushkov Sergey

    2017-01-01

    Full Text Available Increasing energy performance of the residential buildings by means of reducing heat consumption on the heating and ventilation is the last segment in the system of energy resources saving. The first segments in the energy saving process are heat producing and transportation over the main lines and outside distribution networks. In the period from 2006 to 2013. by means of the heat-supply schemes optimization and modernization of the heating systems. using expensive (200–300 $US per 1 m though hugely effective preliminary coated pipes. the economy reached 2.7 mln tons of fuel equivalent. Considering the multi-stage and multifactorial nature (electricity. heat and water supply of the residential sector energy saving. the reasonable estimate of the efficiency of the saving of residential buildings energy should be performed in tons of fuel equivalent per unit of time.

  18. Energy efficiency estimation of a steam powered LNG tanker using normal operating data

    Directory of Open Access Journals (Sweden)

    Sinha Rajendra Prasad

    2016-01-01

    Full Text Available A ship’s energy efficiency performance is generally estimated by conducting special sea trials of few hours under very controlled environmental conditions of calm sea, standard draft and optimum trim. This indicator is then used as the benchmark for future reference of the ship’s Energy Efficiency Performance (EEP. In practice, however, for greater part of operating life the ship operates in conditions which are far removed from original sea trial conditions and therefore comparing energy performance with benchmark performance indicator is not truly valid. In such situations a higher fuel consumption reading from the ship fuel meter may not be a true indicator of poor machinery performance or dirty underwater hull. Most likely, the reasons for higher fuel consumption may lie in factors other than the condition of hull and machinery, such as head wind, current, low load operations or incorrect trim [1]. Thus a better and more accurate approach to determine energy efficiency of the ship attributable only to main machinery and underwater hull condition will be to filter out the influence of all spurious and non-standard operating conditions from the ship’s fuel consumption [2]. The author in this paper identifies parameters of a suitable filter to be used on the daily report data of a typical LNG tanker of 33000 kW shaft power to remove effects of spurious and non-standard ship operations on its fuel consumption. The filtered daily report data has been then used to estimate actual fuel efficiency of the ship and compared with the sea trials benchmark performance. Results obtained using data filter show closer agreement with the benchmark EEP than obtained from the monthly mini trials . The data filtering method proposed in this paper has the advantage of using the actual operational data of the ship and thus saving cost of conducting special sea trials to estimate ship EEP. The agreement between estimated results and special sea trials EEP is

  19. Estimating shadow prices and efficiency analysis of productive inputs and pesticide use of vegetable production

    NARCIS (Netherlands)

    Singbo, Alphonse G.; Lansink, Alfons Oude; Emvalomatis, Grigorios

    2015-01-01

    This paper analyzes technical efficiency and the value of the marginal product of productive inputs vis-a-vis pesticide use to measure allocative efficiency of pesticide use along productive inputs. We employ the data envelopment analysis framework and marginal cost techniques to estimate

  20. The Effects of Acoustic White Noise on the Rat Central Auditory System During the Fetal and Critical Neonatal Periods: A Stereological Study.

    Science.gov (United States)

    Salehi, Mohammad Saied; Namavar, Mohammad Reza; Tamadon, Amin; Bahmani, Raziyeh; Jafarzadeh Shirazi, Mohammad Reza; Khazali, Homayoun; Dargahi, Leila; Pandamooz, Sareh; Mohammad-Rezazadeh, Farzad; Rashidi, Fatemeh Sadat

    2017-01-01

    To evaluate the effects of long-term, moderate level noise exposure during crucial periods of rat infants on stereological parameters of medial geniculate body (MGB) and auditory cortex. Twenty-four male offspring of 12 pregnant rats were divided into four groups: fetal-to-critical period group, which were exposed to noise from the last 10 days of fetal life till postnatal day (PND) 29; fetal period group that exposed to noise during the last 10 days of fetal life; critical period group, exposed to noise from PND 15 till PND 29, and control group. White noise at 90 dB for 2 h per day was used. Variance for variables was performed using Proc GLM followed by mean comparison by Duncan's multiple range test. Numerical density of neurons in MGB of fetal-to-critical period group was lower than control group. Similar results were seen in numerical density of neurons in layers IV and VI of auditory cortex. Furthermore, no significant difference was observed in the volume of auditory cortex among groups, and only MGB volume in fetal-to-critical period group was higher than other groups. Estimated total number of neurons in MGB was not significantly different among groups. It seems necessary to prevent long-term moderate level noise exposure during fetal-to-critical neonatal period.

  1. Efficient optimal joint channel estimation and data detection for massive MIMO systems

    KAUST Repository

    Alshamary, Haider Ali Jasim

    2016-08-15

    In this paper, we propose an efficient optimal joint channel estimation and data detection algorithm for massive MIMO wireless systems. Our algorithm is optimal in terms of the generalized likelihood ratio test (GLRT). For massive MIMO systems, we show that the expected complexity of our algorithm grows polynomially in the channel coherence time. Simulation results demonstrate significant performance gains of our algorithm compared with suboptimal non-coherent detection algorithms. To the best of our knowledge, this is the first algorithm which efficiently achieves GLRT-optimal non-coherent detections for massive MIMO systems with general constellations.

  2. Program Potential: Estimates of Federal Energy Cost Savings from Energy Efficient Procurement

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Margaret [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fujita, K. Sydny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-09-17

    In 2011, energy used by federal buildings cost approximately $7 billion. Reducing federal energy use could help address several important national policy goals, including: (1) increased energy security; (2) lowered emissions of greenhouse gases and other air pollutants; (3) increased return on taxpayer dollars; and (4) increased private sector innovation in energy efficient technologies. This report estimates the impact of efficient product procurement on reducing the amount of wasted energy (and, therefore, wasted money) associated with federal buildings, as well as on reducing the needless greenhouse gas emissions associated with these buildings.

  3. Classification of tubulo-papillary renal cortical tumours using estimates of nuclear volume

    DEFF Research Database (Denmark)

    Brooks, B; Sørensen, Flemming Brandt; Olsen, S

    1993-01-01

    The classification of renal cortical tumours is problematic, with no clear division of benign from malignant tumours. Unbiased stereological estimates of volume-weighted nuclear volume (nuclear vv) were obtained by point sampling of nuclear intercepts in a retrospective study of 36 variably sized...... = 241 microns 3) and 15 tumours classified as renal cell carcinomas with diameters > 3 cm, or aggressive histological pattern (average nuclear vv = 229 microns 3) (2p = 0.68). In this subtype of renal cortical tumours, estimates of nuclear vv do not support the historical convention of using a 3 cm...... tumour diameter as the dividing line between adenomas and carcinomas, but support the theory of a single group of tumours. As most of the truly incidental renal cortical tumours are less than 1 cm in diameter, this limit could be considered. Such small benign cortical nodules have never been reported...

  4. Efficient estimation of dynamic density functions with an application to outlier detection

    KAUST Repository

    Qahtan, Abdulhakim Ali Ali; Zhang, Xiangliang; Wang, Suojin

    2012-01-01

    In this paper, we propose a new method to estimate the dynamic density over data streams, named KDE-Track as it is based on a conventional and widely used Kernel Density Estimation (KDE) method. KDE-Track can efficiently estimate the density with linear complexity by using interpolation on a kernel model, which is incrementally updated upon the arrival of streaming data. Both theoretical analysis and experimental validation show that KDE-Track outperforms traditional KDE and a baseline method Cluster-Kernels on estimation accuracy of the complex density structures in data streams, computing time and memory usage. KDE-Track is also demonstrated on timely catching the dynamic density of synthetic and real-world data. In addition, KDE-Track is used to accurately detect outliers in sensor data and compared with two existing methods developed for detecting outliers and cleaning sensor data. © 2012 ACM.

  5. A characteristic ventricular shape in myelomeningocele-associated hydrocephalus? A CT stereology study

    International Nuclear Information System (INIS)

    Roost, D. van; Solymosi, L.; Funke, K.

    1995-01-01

    We measured the volume of the supratentorial ventricles in 39 consecutive children with myelomeningocele (MMC) and associated hydrocephalus, using a stereological method based on the Cavalieri theorem of systematic sampling. We distinguished the following groups: newborns before and after cerebrospinal fluid shunting (14), a somewhat larger group of newborns with an untreated MMC-associated hydrocephalus (25) and a group of shunted children at a mean age of 1.5 years (28). We paid special attention to the shape of the lateral ventricles, looking separately at the anterior and posterior halves. The measurements were compared with a healthy control group (10) and with children with hydrocephalus unrelated to MMC (15). The average volume ratio of the posterior to the anterior half of the lateral ventricles was 1.05 ± 0.39 in non-hydrocephalic children, 1.11 ± 0.55 in untreated hydrocephalic children without MMC, and 2.15 ± 0.65 in MMC-associated hydrocephalus prior to shunting. These ratios did not change significantly after shunting. This confirms our impression that MMC-associated hydrocephalus shows a characteristic shape, with a disproportionate enlargement of the posterior part of the lateral ventricles, in clear contrast to the normal-width frontal horns. This shape is reminiscent of the fetal ventricular shape. It reveals disturbance of brain development in children with MMC, which goes beyond the classic description of the Chiari malformation. (orig.)

  6. Efficient Estimation of Non-Linear Dynamic Panel Data Models with Application to Smooth Transition Models

    DEFF Research Database (Denmark)

    Gørgens, Tue; Skeels, Christopher L.; Wurtz, Allan

    This paper explores estimation of a class of non-linear dynamic panel data models with additive unobserved individual-specific effects. The models are specified by moment restrictions. The class includes the panel data AR(p) model and panel smooth transition models. We derive an efficient set...... of moment restrictions for estimation and apply the results to estimation of panel smooth transition models with fixed effects, where the transition may be determined endogenously. The performance of the GMM estimator, both in terms of estimation precision and forecasting performance, is examined in a Monte...

  7. Efficient Implementation of a Symbol Timing Estimator for Broadband PLC.

    Science.gov (United States)

    Nombela, Francisco; García, Enrique; Mateos, Raúl; Hernández, Álvaro

    2015-08-21

    Broadband Power Line Communications (PLC) have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA.

  8. Efficient Implementation of a Symbol Timing Estimator for Broadband PLC

    Directory of Open Access Journals (Sweden)

    Francisco Nombela

    2015-08-01

    Full Text Available Broadband Power Line Communications (PLC have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA.

  9. An empirical analysis of the precision of estimating the numbers of neurons and glia in human neocortex using a fractionator-design with sub-sampling

    DEFF Research Database (Denmark)

    Lyck, L.; Santamaria, I.D.; Pakkenberg, B.

    2009-01-01

    Improving histomorphometric analysis of the human neocortex by combining stereological cell counting with immunchistochemical visualisation of specific neuronal and glial cell populations is a methodological challenge. To enable standardized immunohistochemical staining, the amount of brain tissue...... at each level of sampling was determined empirically. The methodology was tested in three brains analysing the contribution of the multi-step sampling procedure to the precision on the estimated total numbers of immunohistochemically defined NeuN expressing (NeuN(+)) neurons and CD45(+) microglia...

  10. Efficiency Optimization Control of IPM Synchronous Motor Drives with Online Parameter Estimation

    Directory of Open Access Journals (Sweden)

    Sadegh Vaez-Zadeh

    2011-04-01

    Full Text Available This paper describes an efficiency optimization control method for high performance interior permanent magnet synchronous motor drives with online estimation of motor parameters. The control system is based on an input-output feedback linearization method which provides high performance control and simultaneously ensures the minimization of the motor losses. The controllable electrical loss can be minimized by the optimal control of the armature current vector. It is shown that parameter variations except at near the nominal conditions have undesirable effect on the controller performance. Therefore, a parameter estimation method based on the second method of Lyapunov is presented which guarantees the stability and convergence of the estimation. The extensive simulation results show the feasibility of the proposed controller and observer and their desirable performances.

  11. FASTSim: A Model to Estimate Vehicle Efficiency, Cost and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Brooker, A.; Gonder, J.; Wang, L.; Wood, E.; Lopp, S.; Ramroth, L.

    2015-05-04

    The Future Automotive Systems Technology Simulator (FASTSim) is a high-level advanced vehicle powertrain systems analysis tool supported by the U.S. Department of Energy’s Vehicle Technologies Office. FASTSim provides a quick and simple approach to compare powertrains and estimate the impact of technology improvements on light- and heavy-duty vehicle efficiency, performance, cost, and battery batches of real-world drive cycles. FASTSim’s calculation framework and balance among detail, accuracy, and speed enable it to simulate thousands of driven miles in minutes. The key components and vehicle outputs have been validated by comparing the model outputs to test data for many different vehicles to provide confidence in the results. A graphical user interface makes FASTSim easy and efficient to use. FASTSim is freely available for download from the National Renewable Energy Laboratory’s website (see www.nrel.gov/fastsim).

  12. Estimating returns to scale and scale efficiency for energy consuming appliances

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Helcio [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Efficiency Standards Group; Okwelum, Edson O. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Efficiency Standards Group

    2018-01-18

    Energy consuming appliances accounted for over 40% of the energy use and $17 billion in sales in the U.S. in 2014. Whether such amounts of money and energy were optimally combined to produce household energy services is not straightforwardly determined. The efficient allocation of capital and energy to provide an energy service has been previously approached, and solved with Data Envelopment Analysis (DEA) under constant returns to scale. That approach, however, lacks the scale dimension of the problem and may restrict the economic efficient models of an appliance available in the market when constant returns to scale does not hold. We expand on that approach to estimate returns to scale for energy using appliances. We further calculate DEA scale efficiency scores for the technically efficient models that comprise the economic efficient frontier of the energy service delivered, under different assumptions of returns to scale. We then apply this approach to evaluate dishwashers available in the market in the U.S. Our results show that (a) for the case of dishwashers scale matters, and (b) the dishwashing energy service is delivered under non-decreasing returns to scale. The results further demonstrate that this method contributes to increase consumers’ choice of appliances.

  13. Estimation of absorbed photosynthetically active radiation and vegetation net production efficiency using satellite data

    International Nuclear Information System (INIS)

    Hanan, N.P.; Prince, S.D.; Begue, A.

    1995-01-01

    The amount of photosynthetically active radiation (PAR) absorbed by green vegetation is an important determinant of photosynthesis and growth. Methods for the estimation of fractional absorption of PAR (iff PAR ) for areas greater than 1 km 2 using satellite data are discussed, and are applied to sites in the Sahel that have a sparse herb layer and tree cover of less than 5%. Using harvest measurements of seasonal net production, net production efficiencies are calculated. Variation in estimates of seasonal PAR absorption (APAR) caused by the atmospheric correction method and relationship between surface reflectances and iff PAR is considered. The use of maximum value composites of satellite NDVI to reduce the effect of the atmosphere is shown to produce inaccurate APAR estimates. In this data set, however, atmospheric correction using average optical depths was found to give good approximations of the fully corrected data. A simulation of canopy radiative transfer using the SAIL model was used to derive a relationship between canopy NDVI and iff PAR . Seasonal APAR estimates assuming a 1:1 relationship between iff PAR and NDVI overestimated the SAIL modeled results by up to 260%. The use of a modified 1:1 relationship, where iff PAR was assumed to be linearly related to NDVI scaled between minimum (soil) and maximum (infinite canopy) values, underestimated the SAIL modeled results by up to 35%. Estimated net production efficiencies (ϵ n , dry matter per unit APAR) fell in the range 0.12–1.61 g MJ −1 for above ground production, and in the range 0.16–1.88 g MJ −1 for total production. Sites with lower rainfall had reduced efficiencies, probably caused by physiological constraints on photosynthesis during dry conditions. (author)

  14. Statistical estimate of mercury removal efficiencies for air pollution control devices of municipal solid waste incinerators.

    Science.gov (United States)

    Takahashi, Fumitake; Kida, Akiko; Shimaoka, Takayuki

    2010-10-15

    Although representative removal efficiencies of gaseous mercury for air pollution control devices (APCDs) are important to prepare more reliable atmospheric emission inventories of mercury, they have been still uncertain because they depend sensitively on many factors like the type of APCDs, gas temperature, and mercury speciation. In this study, representative removal efficiencies of gaseous mercury for several types of APCDs of municipal solid waste incineration (MSWI) were offered using a statistical method. 534 data of mercury removal efficiencies for APCDs used in MSWI were collected. APCDs were categorized as fixed-bed absorber (FA), wet scrubber (WS), electrostatic precipitator (ESP), and fabric filter (FF), and their hybrid systems. Data series of all APCD types had Gaussian log-normality. The average removal efficiency with a 95% confidence interval for each APCD was estimated. The FA, WS, and FF with carbon and/or dry sorbent injection systems had 75% to 82% average removal efficiencies. On the other hand, the ESP with/without dry sorbent injection had lower removal efficiencies of up to 22%. The type of dry sorbent injection in the FF system, dry or semi-dry, did not make more than 1% difference to the removal efficiency. The injection of activated carbon and carbon-containing fly ash in the FF system made less than 3% difference. Estimation errors of removal efficiency were especially high for the ESP. The national average of removal efficiency of APCDs in Japanese MSWI plants was estimated on the basis of incineration capacity. Owing to the replacement of old APCDs for dioxin control, the national average removal efficiency increased from 34.5% in 1991 to 92.5% in 2003. This resulted in an additional reduction of about 0.86Mg emission in 2003. Further study using the methodology in this study to other important emission sources like coal-fired power plants will contribute to better emission inventories. Copyright © 2010 Elsevier B.V. All rights

  15. Efficient Spectral Power Estimation on an Arbitrary Frequency Scale

    Directory of Open Access Journals (Sweden)

    F. Zaplata

    2015-04-01

    Full Text Available The Fast Fourier Transform is a very efficient algorithm for the Fourier spectrum estimation, but has the limitation of a linear frequency scale spectrum, which may not be suitable for every system. For example, audio and speech analysis needs a logarithmic frequency scale due to the characteristic of a human’s ear. The Fast Fourier Transform algorithms are not able to efficiently give the desired results and modified techniques have to be used in this case. In the following text a simple technique using the Goertzel algorithm allowing the evaluation of the power spectra on an arbitrary frequency scale will be introduced. Due to its simplicity the algorithm suffers from imperfections which will be discussed and partially solved in this paper. The implementation into real systems and the impact of quantization errors appeared to be critical and have to be dealt with in special cases. The simple method dealing with the quantization error will also be introduced. Finally, the proposed method will be compared to other methods based on its computational demands and its potential speed.

  16. Efficient Semiparametric Marginal Estimation for the Partially Linear Additive Model for Longitudinal/Clustered Data

    KAUST Repository

    Carroll, Raymond; Maity, Arnab; Mammen, Enno; Yu, Kyusang

    2009-01-01

    We consider the efficient estimation of a regression parameter in a partially linear additive nonparametric regression model from repeated measures data when the covariates are multivariate. To date, while there is some literature in the scalar covariate case, the problem has not been addressed in the multivariate additive model case. Ours represents a first contribution in this direction. As part of this work, we first describe the behavior of nonparametric estimators for additive models with repeated measures when the underlying model is not additive. These results are critical when one considers variants of the basic additive model. We apply them to the partially linear additive repeated-measures model, deriving an explicit consistent estimator of the parametric component; if the errors are in addition Gaussian, the estimator is semiparametric efficient. We also apply our basic methods to a unique testing problem that arises in genetic epidemiology; in combination with a projection argument we develop an efficient and easily computed testing scheme. Simulations and an empirical example from nutritional epidemiology illustrate our methods.

  17. Efficient Semiparametric Marginal Estimation for the Partially Linear Additive Model for Longitudinal/Clustered Data

    KAUST Repository

    Carroll, Raymond

    2009-04-23

    We consider the efficient estimation of a regression parameter in a partially linear additive nonparametric regression model from repeated measures data when the covariates are multivariate. To date, while there is some literature in the scalar covariate case, the problem has not been addressed in the multivariate additive model case. Ours represents a first contribution in this direction. As part of this work, we first describe the behavior of nonparametric estimators for additive models with repeated measures when the underlying model is not additive. These results are critical when one considers variants of the basic additive model. We apply them to the partially linear additive repeated-measures model, deriving an explicit consistent estimator of the parametric component; if the errors are in addition Gaussian, the estimator is semiparametric efficient. We also apply our basic methods to a unique testing problem that arises in genetic epidemiology; in combination with a projection argument we develop an efficient and easily computed testing scheme. Simulations and an empirical example from nutritional epidemiology illustrate our methods.

  18. Is length an appropriate estimator to characterize pulmonary alveolar capillaries? A critical evaluation in the human lung

    DEFF Research Database (Denmark)

    Mühlfeld, Christian; Weibel, Ewald R.; Hahn, Ute

    2010-01-01

    Stereological estimations of total capillary length have been used to characterize changes in the alveolar capillary network (ACN) during developmental processes or pathophysiological conditions. Here, we analyzed whether length estimations are appropriate to describe the 3D nature of the ACN. Semi...... resulted in a mean of 2,746 km (SD: 722 km). Because of the geometry of the ACN both approaches carry an unpredictable bias. The bias incurred by the design-based approach is proportional to the ratio between radius and length of the capillary segments in the ACN, the number of branching points...... and the winding of the capillaries. The model-based approach is biased because of the real noncylindrical shape of capillaries and the network structure. In conclusion, the estimation of the total length of capillaries in the ACN cannot be recommended as the geometry of the ACN does not fulfill the requirements...

  19. Analytical estimates and proof of the scale-free character of efficiency and improvement in Barabasi-Albert trees

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Bermejo, B. [Departamento de Fisica, Universidad Rey Juan Carlos, Escuela Superior de Ciencias Experimentales y Tecnologia, Edificio Departamental II, Calle Tulipan S/N, 28933-Mostoles-Madrid (Spain)], E-mail: benito.hernandez@urjc.es; Marco-Blanco, J. [Departamento de Fisica, Universidad Rey Juan Carlos, Escuela Superior de Ciencias Experimentales y Tecnologia, Edificio Departamental II, Calle Tulipan S/N, 28933-Mostoles-Madrid (Spain); Romance, M. [Departamento de Matematica Aplicada, Universidad Rey Juan Carlos, Escuela Superior de Ciencias Experimentales y Tecnologia, Edificio Departamental II, Calle Tulipan S/N, 28933-Mostoles-Madrid (Spain)

    2009-02-23

    Estimates for the efficiency of a tree are derived, leading to new analytical expressions for Barabasi-Albert trees efficiency. These expressions are used to investigate the dynamic behaviour of such networks. It is proved that the preferential attachment leads to an asymptotic conservation of efficiency as the Barabasi-Albert trees grow.

  20. Analytical estimates and proof of the scale-free character of efficiency and improvement in Barabasi-Albert trees

    International Nuclear Information System (INIS)

    Hernandez-Bermejo, B.; Marco-Blanco, J.; Romance, M.

    2009-01-01

    Estimates for the efficiency of a tree are derived, leading to new analytical expressions for Barabasi-Albert trees efficiency. These expressions are used to investigate the dynamic behaviour of such networks. It is proved that the preferential attachment leads to an asymptotic conservation of efficiency as the Barabasi-Albert trees grow

  1. Impact of energy policy instruments on the estimated level of underlying energy efficiency in the EU residential sector

    International Nuclear Information System (INIS)

    Filippini, Massimo; Hunt, Lester C.; Zorić, Jelena

    2014-01-01

    The promotion of energy efficiency is seen as one of the top priorities of EU energy policy (EC, 2010). In order to design and implement effective energy policy instruments, it is necessary to have information on energy demand price and income elasticities in addition to sound indicators of energy efficiency. This research combines the approaches taken in energy demand modelling and frontier analysis in order to econometrically estimate the level of energy efficiency for the residential sector in the EU-27 member states for the period 1996 to 2009. The estimates for the energy efficiency confirm that the EU residential sector indeed holds a relatively high potential for energy savings from reduced inefficiency. Therefore, despite the common objective to decrease ‘wasteful’ energy consumption, considerable variation in energy efficiency between the EU member states is established. Furthermore, an attempt is made to evaluate the impact of energy-efficiency measures undertaken in the EU residential sector by introducing an additional set of variables into the model and the results suggest that financial incentives and energy performance standards play an important role in promoting energy efficiency improvements, whereas informative measures do not have a significant impact. - Highlights: • The level of energy efficiency of the EU residential sector is estimated. • Considerable potential for energy savings from reduced inefficiency is established. • The impact of introduced energy-efficiency policy measures is also evaluated. • Financial incentives are found to promote energy efficiency improvements. • Energy performance standards also play an important role

  2. Energy-efficient power allocation of two-hop cooperative systems with imperfect channel estimation

    KAUST Repository

    Amin, Osama

    2015-06-08

    Recently, much attention has been paid to the green design of wireless communication systems using energy efficiency (EE) metrics that should capture all energy consumption sources to deliver the required data. In this paper, we formulate an accurate EE metric for cooperative two-hop systems that use the amplify-and-forward relaying scheme. Different from the existing research that assumes the availability of perfect channel state information (CSI) at the communication cooperative nodes, we assume a practical scenario, where training pilots are used to estimate the channels. The estimated CSI can be used to adapt the available resources of the proposed system in order to maximize the EE. Two estimation strategies are assumed namely disintegrated channel estimation, which assumes the availability of channel estimator at the relay, and cascaded channel estimation, where the relay is not equipped with channel estimator and only forwards the received pilot(s) in order to let the destination estimate the cooperative link. The channel estimation cost is reflected on the EE metric by including the estimation error in the signal-to-noise term and considering the energy consumption during the estimation phase. Based on the formulated EE metric, we propose an energy-aware power allocation algorithm to maximize the EE of the cooperative system with channel estimation. Furthermore, we study the impact of the estimation parameters on the optimized EE performance via simulation examples.

  3. STEREOLOGICAL STUDIES ON FETAL VASCULAR DEVELOPMENT IN HUMAN PLACENTAL VILLI

    Directory of Open Access Journals (Sweden)

    Terry M Mayhew

    2011-05-01

    Full Text Available In human pregnancy, fetal well-being depends on the development of placental villi and the creation and maintenance of fetal microvessels within them. The aim of this study was to define stereological measures of the growth, capillarization and maturation of villi and of fetoplacental angiogenesis and capillary remodelling. Placentas were collected at 12-41 weeks of gestation and assigned to six age groups spanning equal age ranges. Tissue samples were randomised for position and orientation. Overall growth of peripheral (intermediate and terminal villi and their capillaries was evaluated using total volumes, surface areas and lengths. Measures of villous capillarization comprised capillary volume, surface and length densities and capillary:villus surface and length ratios. Size and shape remodelling of villi and capillaries was assessed using mean cross-sectional areas, perimeters and shape coefficients (perimeter2/area. Group comparisons were drawn by analysis of variance. Villous and capillary volumes, surfaces and lengths increased significantly throughout gestation. Villous maturation involved phasic (capillary:villus surface and length ratios or progressive (volume, surface and length densities increases in indices of villous capillarization. It also involved isomorphic thinning (cross-sectional areas and perimeters declined but shape coefficients did not alter. In contrast, growth of capillaries did not involve changes in luminal areas or perimeters. The results show that villous growth and fetal angiogenesis involve increases in overall length rather than calibre and that villous differentiation involves increased capillarization. Although they do not distinguish between increases in the lengths versus numbers of capillary segments, other studies have shown that capillaries switch from branching to non-branching angiogenesis during gestation. Combined with maintenance of capillary calibres, these processes will contribute to the reduced

  4. FIBRIN-TYPE FIBRINOID IN HUMAN PLACENTA: A STEREOLOGICAL ANALYSIS OF ITS ASSOCIATION WITH INTERVILLOUS VOLUME AND VILLOUS SURFACE AREA

    Directory of Open Access Journals (Sweden)

    Terry M Mayhew

    2011-05-01

    Full Text Available Stereological methods were used to examine fibrin-type fibrinoid deposition in the intervillous spaces of human placentas collected during gestation (12-41 weeks and from term pregnancies at low (400 m and high (3.6 km altitude. The main aim was to test predictions about the relationships between fibrinoid deposits and either the volume of intervillous space or the surface area of (intermediate + terminal villi. Fields of view on Masson trichrome-stained paraffin sections were selected as part of a systematic sampling design which randomised section location and orientation. Relative and absolute volumes were estimated by test point counting and surfaces by intersection counting. Apparent differences were tested by analyses of variance and relationships by correlation and regression analysis. Fibrinoid volume increased during gestation and correlated positively with intervillous volume and villous surface area. However, relative to intervillous volume, the main increase in fibrinoid occurred towards term (36-41 weeks. At high altitude, placentas contained more intervillous space but less fibrinoid. At both altitudes, there were significant correlations between fibrinoid volume and villous surface area. In all cases, changes in fibrinoid volume were commensurate with changes in villous surface area. Whilst findings lend support to the notion that fibrinoid deposition during normal gestation is influenced by the quality of vascular perfusion, they also emphasise that the extent of the villous surface is a more generally important factor. The villous surface may influence the steady state between coagulation and fibrinolysis since some pro-coagulatory events operate at the trophoblastic epithelium. They occur notably at sites of trophoblast de-epithelialisation and these arise following trauma or during the extrusion phase of normal epithelial turnover.

  5. Crataegus Monogyna Aqueous Extract Ameliorates Cyclophosphamide-Induced Toxicity in Rat Testis: Stereological Evidences

    Directory of Open Access Journals (Sweden)

    Hassan Malekinejad

    2012-01-01

    Full Text Available Cyclophosphamide (CP is extensively used as an antineoplastic agent for the treatment of various cancers, as well as an immunosuppressive agent. However, despite its wide spectrum of clinical uses, CP is known to cause several adverse effects including reproductive toxicity. Crataegus monogyna is one of the oldest pharmaceutical plants that have been shown to be cytoprotective by scavenging free radicals. The present study was conducted to assess whether Crataegus monogyna fruits aqueous extract with anti-oxidant properties, could serve as a protective agent against reproductive toxicity during CP treatment in a rat model. Male Wistar rats were categorized into four groups. Two groups of rats were administered CP at a dose of 5 mg in 5 ml saline/kg/day for 28 days by oral gavages. One of these groups received Crataegus monogyna aqueous extract at a dose of 20 mg/kg/day orally four hours after cyclophosphamide administration. A vehicle treated control group and a Crataegus monogyna control group were also included. The CP-treated group showed significant decreases in the body, testes and epididymides weights as well as many histological alterations. Stereological parameters and spermatogenic activities (Sertoli cell, repopulation and miotic indices were also significantly decreased by CP treatment. Notably, Crataegus coadministration caused a partial recovery in above-mentined parameters. These findings indicate that Crataegus monogyna may be partially protective against CP-induced testicular toxicity.

  6. Towards physiologically meaningful water-use efficiency estimates from eddy covariance data.

    Science.gov (United States)

    Knauer, Jürgen; Zaehle, Sönke; Medlyn, Belinda E; Reichstein, Markus; Williams, Christopher A; Migliavacca, Mirco; De Kauwe, Martin G; Werner, Christiane; Keitel, Claudia; Kolari, Pasi; Limousin, Jean-Marc; Linderson, Maj-Lena

    2018-02-01

    Intrinsic water-use efficiency (iWUE) characterizes the physiological control on the simultaneous exchange of water and carbon dioxide in terrestrial ecosystems. Knowledge of iWUE is commonly gained from leaf-level gas exchange measurements, which are inevitably restricted in their spatial and temporal coverage. Flux measurements based on the eddy covariance (EC) technique can overcome these limitations, as they provide continuous and long-term records of carbon and water fluxes at the ecosystem scale. However, vegetation gas exchange parameters derived from EC data are subject to scale-dependent and method-specific uncertainties that compromise their ecophysiological interpretation as well as their comparability among ecosystems and across spatial scales. Here, we use estimates of canopy conductance and gross primary productivity (GPP) derived from EC data to calculate a measure of iWUE (G 1 , "stomatal slope") at the ecosystem level at six sites comprising tropical, Mediterranean, temperate, and boreal forests. We assess the following six mechanisms potentially causing discrepancies between leaf and ecosystem-level estimates of G 1 : (i) non-transpirational water fluxes; (ii) aerodynamic conductance; (iii) meteorological deviations between measurement height and canopy surface; (iv) energy balance non-closure; (v) uncertainties in net ecosystem exchange partitioning; and (vi) physiological within-canopy gradients. Our results demonstrate that an unclosed energy balance caused the largest uncertainties, in particular if it was associated with erroneous latent heat flux estimates. The effect of aerodynamic conductance on G 1 was sufficiently captured with a simple representation. G 1 was found to be less sensitive to meteorological deviations between canopy surface and measurement height and, given that data are appropriately filtered, to non-transpirational water fluxes. Uncertainties in the derived GPP and physiological within-canopy gradients and their

  7. Estimate of Technical Potential for Minimum Efficiency Performance Standards in 13 Major World Economies

    Energy Technology Data Exchange (ETDEWEB)

    Letschert, Virginie [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Desroches, Louis-Benoit [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ke, Jing [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); McNeil, Michael [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-07-01

    As part of the ongoing effort to estimate the foreseeable impacts of aggressive minimum efficiency performance standards (MEPS) programs in the world’s major economies, Lawrence Berkeley National Laboratory (LBNL) has developed a scenario to analyze the technical potential of MEPS in 13 major economies around the world1 . The “best available technology” (BAT) scenario seeks to determine the maximum potential savings that would result from diffusion of the most efficient available technologies in these major economies.

  8. Efficient estimation of feedback effects with application to climate models

    International Nuclear Information System (INIS)

    Cacugi, D.G.; Hall, M.C.G.

    1984-01-01

    This work presents an efficient method for calculating the sensitivity of a mathematical model's result to feedback. Feedback is defined in terms of an operator acting on the model's dependent variables. The sensitivity to feedback is defined as a functional derivative, and a method is presented to evaluate this derivative using adjoint functions. Typically, this method allows the individual effect of many different feedbacks to be estimated with a total additional computing time comparable to only one recalculation. The effects on a CO 2 -doubling experiment of actually incorporating surface albedo and water vapor feedbacks in radiative-convective model are compared with sensivities calculated using adjoint functions. These sensitivities predict the actual effects of feedback with at least the correct sign and order of magnitude. It is anticipated that this method of estimation the effect of feedback will be useful for more complex models where extensive recalculations for each of a variety of different feedbacks is impractical

  9. Efficient estimators for likelihood ratio sensitivity indices of complex stochastic dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Arampatzis, Georgios; Katsoulakis, Markos A.; Rey-Bellet, Luc [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003 (United States)

    2016-03-14

    We demonstrate that centered likelihood ratio estimators for the sensitivity indices of complex stochastic dynamics are highly efficient with low, constant in time variance and consequently they are suitable for sensitivity analysis in long-time and steady-state regimes. These estimators rely on a new covariance formulation of the likelihood ratio that includes as a submatrix a Fisher information matrix for stochastic dynamics and can also be used for fast screening of insensitive parameters and parameter combinations. The proposed methods are applicable to broad classes of stochastic dynamics such as chemical reaction networks, Langevin-type equations and stochastic models in finance, including systems with a high dimensional parameter space and/or disparate decorrelation times between different observables. Furthermore, they are simple to implement as a standard observable in any existing simulation algorithm without additional modifications.

  10. Long live the liver: immunohistochemical and stereological study of hepatocytes, liver sinusoidal endothelial cells, Kupffer cells and hepatic stellate cells of male and female rats throughout ageing.

    Science.gov (United States)

    Marcos, Ricardo; Correia-Gomes, Carla

    2016-12-01

    Male/female differences in enzyme activity and gene expression in the liver are known to be attenuated with ageing. Nevertheless, the effect of ageing on liver structure and quantitative cell morphology remains unknown. Male and female Wistar rats aged 2, 6, 12 and 18 months were examined by means of stereological techniques and immunohistochemical tagging of hepatocytes (HEP), liver sinusoidal endothelial cells (LSEC), Kupffer cells (KC) and hepatic stellate cells (HSC) in order to assess the total number and number per gram of these cells throughout life. The mean cell volume of HEP and HSC, the lobular position and the collagen content of the liver were also evaluated with stereological techniques. The number per gram of HSC was similar for both genders and was maintained throughout ageing. The mean volume of HSC was also conserved but differences in the cell body and lobular location were observed. Statistically significant gender differences in HEP were noted in young rats (females had smaller and more binucleated HEP) but were attenuated with ageing. The same occurred for KC and LSEC, since the higher number per gram in young females disappeared in older animals. Liver collagen increased with ageing but only in males. Thus, the numbers of these four cell types are related throughout ageing, with well-defined cell ratios. The shape and lobular position of HSC change with ageing in both males and females. Gender dimorphism in HEP, KC and LSEC of young rat liver disappears with ageing.

  11. Efficiency of the estimators of multivariate distribution parameters from the one-dimensional observed frequencies

    International Nuclear Information System (INIS)

    Chernov, N.I.; Kurbatov, V.S.; Ososkov, G.A.

    1988-01-01

    Parameter estimation for multivariate probability distributions is studied in experiments where data are presented as one-dimensional hystograms. For this model a statistics defined as a quadratic form of the observed frequencies which has a limitig x 2 -distribution is proposed. The efficiency of the estimator minimizing the value of that statistics is proved whithin the class of all unibased estimates obtained via minimization of quadratic forms of observed frequencies. The elaborated method was applied to the physical problem of analysis of the secondary pion energy distribution in the isobar model of pion-nucleon interactions with the production of an additional pion. The numerical experiments showed that the accuracy of estimation is twice as much if comparing the conventional methods

  12. Estimation efficiency of usage satellite derived and modelled biophysical products for yield forecasting

    Science.gov (United States)

    Kolotii, Andrii; Kussul, Nataliia; Skakun, Sergii; Shelestov, Andrii; Ostapenko, Vadim; Oliinyk, Tamara

    2015-04-01

    Efficient and timely crop monitoring and yield forecasting are important tasks for ensuring of stability and sustainable economic development [1]. As winter crops pay prominent role in agriculture of Ukraine - the main focus of this study is concentrated on winter wheat. In our previous research [2, 3] it was shown that usage of biophysical parameters of crops such as FAPAR (derived from Geoland-2 portal as for SPOT Vegetation data) is far more efficient for crop yield forecasting to NDVI derived from MODIS data - for available data. In our current work efficiency of usage such biophysical parameters as LAI, FAPAR, FCOVER (derived from SPOT Vegetation and PROBA-V data at resolution of 1 km and simulated within WOFOST model) and NDVI product (derived from MODIS) for winter wheat monitoring and yield forecasting is estimated. As the part of crop monitoring workflow (vegetation anomaly detection, vegetation indexes and products analysis) and yield forecasting SPIRITS tool developed by JRC is used. Statistics extraction is done for landcover maps created in SRI within FP-7 SIGMA project. Efficiency of usage satellite based and modelled with WOFOST model biophysical products is estimated. [1] N. Kussul, S. Skakun, A. Shelestov, O. Kussul, "Sensor Web approach to Flood Monitoring and Risk Assessment", in: IGARSS 2013, 21-26 July 2013, Melbourne, Australia, pp. 815-818. [2] F. Kogan, N. Kussul, T. Adamenko, S. Skakun, O. Kravchenko, O. Kryvobok, A. Shelestov, A. Kolotii, O. Kussul, and A. Lavrenyuk, "Winter wheat yield forecasting in Ukraine based on Earth observation, meteorological data and biophysical models," International Journal of Applied Earth Observation and Geoinformation, vol. 23, pp. 192-203, 2013. [3] Kussul O., Kussul N., Skakun S., Kravchenko O., Shelestov A., Kolotii A, "Assessment of relative efficiency of using MODIS data to winter wheat yield forecasting in Ukraine", in: IGARSS 2013, 21-26 July 2013, Melbourne, Australia, pp. 3235 - 3238.

  13. Experimental study on source efficiencies for estimating surface contamination level

    International Nuclear Information System (INIS)

    Ichiji, Takeshi; Ogino, Haruyuki

    2008-01-01

    Source efficiency was measured experimentally for various materials, such as metals, nonmetals, flooring materials, sheet materials and other materials, contaminated by alpha and beta emitter radioactive nuclides. Five nuclides, 147 Pm, 60 Co, 137 Cs, 204 Tl and 90 Sr- 90 Y, were used as the beta emitters, and one nuclide 241 Am was used as the alpha emitter. The test samples were prepared by placing drops of the radioactive standardized solutions uniformly on the various materials using an automatic quantitative dispenser system from Musashi Engineering, Inc. After placing drops of the radioactive standardized solutions, the test materials were allowed to dry for more than 12 hours in a draft chamber with a hood. The radioactivity of each test material was about 30 Bq. Beta rays or alpha rays from the test materials were measured with a 2-pi gas flow proportional counter from Aloka Co., Ltd. The source efficiencies of the metals, nonmetals and sheet materials were higher than 0.5 in the case of contamination by the 137 Cs, 204 Tl and 90 Sr- 90 Y radioactive standardized solutions, higher than 0.4 in the case of contamination by the 60 Co radioactive standardized solution, and higher than 0.25 in the case of contamination by the alpha emitter the 241 Am radioactive standardized solution. These values were higher than those given in Japanese Industrial Standards (JIS) documents. In contrast, the source efficiencies of some permeable materials were lower than those given in JIS documents, because source efficiency varies depending on whether the materials or radioactive sources are wet or dry. This study provides basic data on source efficiency, which is useful for estimating the surface contamination level of materials. (author)

  14. Stereological Investigation of the Effects of Treadmill Running Exercise on the Hippocampal Neurons in Middle-Aged APP/PS1 Transgenic Mice.

    Science.gov (United States)

    Chao, Fenglei; Jiang, Lin; Zhang, Yi; Zhou, Chunni; Zhang, Lei; Tang, Jing; Liang, Xin; Qi, Yingqiang; Zhu, Yanqing; Ma, Jing; Tang, Yong

    2018-01-01

    The risk of cognitive decline during Alzheimer's disease (AD) can be reduced if physical activity is maintained; however, the specific neural events underlying this beneficial effect are still uncertain. To quantitatively investigate the neural events underlying the effect of running exercise on middle-aged AD subjects, 12-month-old male APP/PS1 mice were randomly assigned to a control group or running group, and age-matched non-transgenic littermates were used as a wild-type group. AD running group mice were subjected to a treadmill running protocol (regular and moderate intensity) for four months. Spatial learning and memory abilities were assessed using the Morris water maze. Hippocampal amyloid plaques were observed using Thioflavin S staining and immunohistochemistry. Hippocampal volume, number of neurons, and number of newborn cells (BrdU+ cells) in the hippocampus were estimated using stereological techniques, and newborn neurons were observed using double-labelling immunofluorescence. Marked neuronal loss in both the CA1 field and dentate gyrus (DG) and deficits in both the neurogenesis and survival of new neurons in the DG of middle-aged APP/PS1 mice were observed. Running exercise could improve the spatial learning and memory abilities, reduce amyloid plaques in the hippocampi, delay neuronal loss, induce neurogenesis, and promote the survival of newborn neurons in the DG of middle-aged APP/PS1 mice. Exercise-induced protection of neurons and adult neurogenesis within the DG might be part of the important structural basis of the improved spatial learning and memory abilities observed in AD mice.

  15. A novel method for coil efficiency estimation: Validation with a 13C birdcage

    DEFF Research Database (Denmark)

    Giovannetti, Giulio; Frijia, Francesca; Hartwig, Valentina

    2012-01-01

    Coil efficiency, defined as the B1 magnetic field induced at a given point on the square root of supplied power P, is an important parameter that characterizes both the transmit and receive performance of the radiofrequency (RF) coil. Maximizing coil efficiency will maximize also the signal......-to-noise ratio. In this work, we propose a novel method for RF coil efficiency estimation based on the use of a perturbing loop. The proposed method consists of loading the coil with a known resistor by inductive coupling and measuring the quality factor with and without the load. We tested the method...... by measuring the efficiency of a 13C birdcage coil tuned at 32.13 MHz and verified its accuracy by comparing the results with the nuclear magnetic resonance nutation experiment. The method allows coil performance characterization in a short time and with great accuracy, and it can be used both on the bench...

  16. Estimating the Efficiency and Impacts of Petroleum Product Pricing Reforms in China

    Directory of Open Access Journals (Sweden)

    Chuxiong Deng

    2018-04-01

    Full Text Available The efficiency and effects analysis of a new pricing mechanism would have significant policy implications for the further design of a pricing mechanism in an emerging market. Unlike most of the existing literature, which focuses on the impacts to the macro-economy, this paper firstly uses an econometrics model to discuss the efficiency of the new pricing mechanism, and then establishes an augmented Phillips curve to estimate the impact of pricing reform on inflation in China. The results show that: (1 the new pricing mechanism would strengthen the linkage between Chinese oil prices and international oil prices; (2 oil price adjustments are still inadequate in China. (3 The lag in inflation is the most important factor that affects inflation, while the impact of the Chinese government’s price adjustments on inflation is limited and insignificant. In order to improve the efficiency of the petroleum products pricing mechanism and shorten lags, government should shorten the adjustment period and diminish the fluctuation threshold.

  17. ESTIMATION OF THE NUMBER OF NEURONS IN THE HIPPOCAMPUS OF RATS WITH PENICILLIN INDUCED EPILEPSY

    Directory of Open Access Journals (Sweden)

    Ilgaz Akdogan

    2011-05-01

    Full Text Available Epilepsy is a neurological disease arising from strong and uncontrollable electrical firings of a group of neurons in the central nervous system. Experimental epileptic models have been developed to assess the physiopathology of epileptic seizures. This study was undertaken to estimate the number of neurons in the rat hippocampus with penicillin induced epilepsy, using a stereological method, "the optical fractionator". In the experimental group, 500 IU penicillin-G was injected intra-cortically, and in the control group, the same volume of saline was administered. A week later, the animals were decapitated and their brains were removed by craniatomy. Frozen brains were cut with a thickness of 150 ěm in a cryostat. Sections were collected by systematic random sampling and stained with hematoxylen-eosin. Microscopic images of pyramidal cell layers from hippocampus CA1, CA2 and CA3 subfields were then transferred to a monitor, using a 100x objective (N.A. = 1.25. Using the optical disector method, the neurons were counted in the frames and determined with a fractionator sampling scheme. The total pyramidal neuron number was then estimated using the optical fractionator method. The total pyramidal neuron number was found to be statistically lower in the experimental group (mean = 142,888 ± 11,745 than in the control group (mean = 177,953 ± 10,907 (p < 0.05. The results suggest that a decrease in the hippocampal neuronal number in a penicillin model of epilepsy can be determined objectively and efficiently using the optical fractionator method.

  18. Validation by theoretical approach to the experimental estimation of efficiency for gamma spectrometry of gas in 100 ml standard flask

    International Nuclear Information System (INIS)

    Mohan, V.; Chudalayandi, K.; Sundaram, M.; Krishnamony, S.

    1996-01-01

    Estimation of gaseous activity forms an important component of air monitoring at Madras Atomic Power Station (MAPS). The gases of importance are argon 41 an air activation product and fission product noble gas xenon 133. For estimating the concentration, the experimental method is used in which a grab sample is collected in a 100 ml volumetric standard flask. The activity of gas is then computed by gamma spectrometry using a predetermined efficiency estimated experimentally. An attempt is made using theoretical approach to validate the experimental method of efficiency estimation. Two analytical models named relative flux model and absolute activity model were developed independently of each other. Attention is focussed on the efficiencies for 41 Ar and 133 Xe. Results show that the present method of sampling and analysis using 100 ml volumetric flask is adequate and acceptable. (author). 5 refs., 2 tabs

  19. SU-E-I-65: Estimation of Tagging Efficiency in Pseudo-Continuous Arterial Spin Labeling (pCASL) MRI

    Energy Technology Data Exchange (ETDEWEB)

    Jen, M [Chang Gung University, Taoyuan City, Taiwan (China); Yan, F; Tseng, Y; Chen, C [Taipei Medical University - Shuang Ho Hospital, Ministry of Health and Welf, New Taipei City, Taiwan (China); Lin, C [GE Healthcare, Taiwan (China); GE Healthcare China, Beijing (China); Liu, H [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: pCASL was recommended as a potent approach for absolute cerebral blood flow (CBF) quantification in clinical practice. However, uncertainties of tagging efficiency in pCASL remain an issue. This study aimed to estimate tagging efficiency by using short quantitative pulsed ASL scan (FAIR-QUIPSSII) and compare resultant CBF values with those calibrated by using 2D Phase Contrast (PC) MRI. Methods: Fourteen normal volunteers participated in this study. All images, including whole brain (WB) pCASL, WB FAIR-QUIPSSII and single-slice 2D PC, were collected on a 3T clinical MRI scanner with a 8-channel head coil. DeltaM map was calculated by averaging the subtraction of tag/control pairs in pCASL and FAIR-QUIPSSII images and used for CBF calculation. Tagging efficiency was then calculated by the ratio of mean gray matter CBF obtained from pCASL and FAIR-QUIPSSII. For comparison, tagging efficiency was also estimated with 2D PC, a previously established method, by contrast WB CBF in pCASL and 2D PC. Feasibility of estimation from a short FAIR-QUIPSSII scan was evaluated by number of averages required for obtaining a stable deltaM value. Setting deltaM calculated by maximum number of averaging (50 pairs) as reference, stable results were defined within ±10% variation. Results: Tagging efficiencies obtained by 2D PC MRI (0.732±0.092) were significantly lower than which obtained by FAIRQUIPPSSII (0.846±0.097) (P<0.05). Feasibility results revealed that four pairs of images in FAIR-QUIPPSSII scan were sufficient to obtain a robust calibration of less than 10% differences from using 50 pairs. Conclusion: This study found that reliable estimation of tagging efficiency could be obtained by a few pairs of FAIR-QUIPSSII images, which suggested that calibration scan in a short duration (within 30s) was feasible. Considering recent reports concerning variability of PC MRI-based calibration, this study proposed an effective alternative for CBF quantification with pCASL.

  20. Estimation of Maize photosynthesis Efficiency Under Deficit Irrigation and Mulch

    International Nuclear Information System (INIS)

    Al-Hadithi, S.

    2004-01-01

    This research aims at estimating maize photosynthesis efficiency under deficit irrigation and soil mulching. A split-split plot design experiment was conducted with three replicates during the fall season 2000 and spring season 2001 at the experimental Station of Soil Dept./ Iraq Atomic Energy Commission. The main plots were assigned to full and deficit irrigation treatments: (C) control. The deficit irrigation treatment included the omission of one irrigation at establishment (S1, 15 days), vegetation (S2, 35 days), flowering (S3, 40 days) and yield formation (S4, 30 days) stages. The sub-plots were allocated for the two varieties, Synthetic 5012 (V1) and Haybrid 2052 (V2). The sub-sub-plots were assigned to mulch (M1) with wheat straw and no mulch (M0). Results showed that the deficit irrigation did not affect photosynthesis efficiency in both seasons, which ranged between 1.90 to 2.15% in fall season and between 1.18 and 1.45% in spring season. The hybrid variety was superior 9.39 and 9.15% over synthetic variety in fall and spring seasons, respectively. Deficit irrigation, varieties and mulch had no significant effects on harvest index in both seasons. This indicates that the two varieties were stable in their partitioning efficiency of nutrient matter between plant organ and grains under the condition of this experiment. (Author) 21 refs., 3 figs., 6 tabs

  1. Long lasting structural changes in primary motor cortex after motor skill learning: a behavioural and stereological study

    Directory of Open Access Journals (Sweden)

    PAOLA MORALES

    2008-12-01

    Full Text Available Many motor skills, once acquired, are stored over a long time period, probably sustained by permanent neuronal changes. Thus, in this paper we have investigated with quantitative stereology the generation and persistence of neuronal density changes in primary motor cortex (MI following motor skill learning (skilled reaching task. Rats were trained a lateralised reaching task during an "early" (22-31 days oíd or "late" (362-371 days oíd postnatal period. The trained and corresponding control rats were sacrificed at day 372, immediately after the behavioural testing. The "early" trained group preserved the learned skilled reaching task when tested at day 372, without requiring any additional training. The "late" trained group showed a similar capacity to that of the "early" trained group for learning the skilled reaching task. All trained animáis ("early" and "late" trained groups showed a significant Ínter hemispheric decrease of neuronal density in the corresponding motor forelimb representation área of MI (cortical layers II-III

  2. Fourier Spot Volatility Estimator: Asymptotic Normality and Efficiency with Liquid and Illiquid High-Frequency Data

    Science.gov (United States)

    2015-01-01

    The recent availability of high frequency data has permitted more efficient ways of computing volatility. However, estimation of volatility from asset price observations is challenging because observed high frequency data are generally affected by noise-microstructure effects. We address this issue by using the Fourier estimator of instantaneous volatility introduced in Malliavin and Mancino 2002. We prove a central limit theorem for this estimator with optimal rate and asymptotic variance. An extensive simulation study shows the accuracy of the spot volatility estimates obtained using the Fourier estimator and its robustness even in the presence of different microstructure noise specifications. An empirical analysis on high frequency data (U.S. S&P500 and FIB 30 indices) illustrates how the Fourier spot volatility estimates can be successfully used to study intraday variations of volatility and to predict intraday Value at Risk. PMID:26421617

  3. SEBAL Model Using to Estimate Irrigation Water Efficiency & Water Requirement of Alfalfa Crop

    Science.gov (United States)

    Zeyliger, Anatoly; Ermolaeva, Olga

    2013-04-01

    The sustainability of irrigation is a complex and comprehensive undertaking, requiring an attention to much more than hydraulics, chemistry, and agronomy. A special combination of human, environmental, and economic factors exists in each irrigated region and must be recognized and evaluated. A way to evaluate the efficiency of irrigation water use for crop production is to consider the so-called crop-water production functions, which express the relation between the yield of a crop and the quantity of water applied to it or consumed by it. The term has been used in a somewhat ambiguous way. Some authors have defined the Crop-Water Production Functions between yield and the total amount of water applied, whereas others have defined it as a relation between yield and seasonal evapotranspiration (ET). In case of high efficiency of irrigation water use the volume of water applied is less than the potential evapotranspiration (PET), then - assuming no significant change of soil moisture storage from beginning of the growing season to its end-the volume of water may be roughly equal to ET. In other case of low efficiency of irrigation water use the volume of water applied exceeds PET, then the excess of volume of water applied over PET must go to either augmenting soil moisture storage (end-of-season moisture being greater than start-of-season soil moisture) or to runoff or/and deep percolation beyond the root zone. In presented contribution some results of a case study of estimation of biomass and leaf area index (LAI) for irrigated alfalfa by SEBAL algorithm will be discussed. The field study was conducted with aim to compare ground biomass of alfalfa at some irrigated fields (provided by agricultural farm) at Saratov and Volgograd Regions of Russia. The study was conducted during vegetation period of 2012 from April till September. All the operations from importing the data to calculation of the output data were carried by eLEAF company and uploaded in Fieldlook web

  4. Development of a computationally efficient algorithm for attitude estimation of a remote sensing satellite

    Science.gov (United States)

    Labibian, Amir; Bahrami, Amir Hossein; Haghshenas, Javad

    2017-09-01

    This paper presents a computationally efficient algorithm for attitude estimation of remote a sensing satellite. In this study, gyro, magnetometer, sun sensor and star tracker are used in Extended Kalman Filter (EKF) structure for the purpose of Attitude Determination (AD). However, utilizing all of the measurement data simultaneously in EKF structure increases computational burden. Specifically, assuming n observation vectors, an inverse of a 3n×3n matrix is required for gain calculation. In order to solve this problem, an efficient version of EKF, namely Murrell's version, is employed. This method utilizes measurements separately at each sampling time for gain computation. Therefore, an inverse of a 3n×3n matrix is replaced by an inverse of a 3×3 matrix for each measurement vector. Moreover, gyro drifts during the time can reduce the pointing accuracy. Therefore, a calibration algorithm is utilized for estimation of the main gyro parameters.

  5. An applicable method for efficiency estimation of operating tray distillation columns and its comparison with the methods utilized in HYSYS and Aspen Plus

    Science.gov (United States)

    Sadeghifar, Hamidreza

    2015-10-01

    Developing general methods that rely on column data for the efficiency estimation of operating (existing) distillation columns has been overlooked in the literature. Most of the available methods are based on empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods may not be sufficiently accurate when applied to industrial columns. In this paper, an applicable and accurate method was developed for the efficiency estimation of distillation columns filled with trays. This method can calculate efficiency as well as mass and heat transfer coefficients without using any empirical mass transfer or hydraulic correlations and without the need to estimate operational or hydraulic parameters of the column. E.g., the method does not need to estimate tray interfacial area, which can be its most important advantage over all the available methods. The method can be used for the efficiency prediction of any trays in distillation columns. For the efficiency calculation, the method employs the column data and uses the true rates of the mass and heat transfers occurring inside the operating column. It is highly emphasized that estimating efficiency of an operating column has to be distinguished from that of a column being designed.

  6. Estimating the cost of saving electricity through U.S. utility customer-funded energy efficiency programs

    International Nuclear Information System (INIS)

    Hoffman, Ian M.; Goldman, Charles A.; Rybka, Gregory; Leventis, Greg; Schwartz, Lisa; Sanstad, Alan H.; Schiller, Steven

    2017-01-01

    The program administrator and total cost of saved energy allow comparison of the cost of efficiency across utilities, states, and program types, and can identify potential performance improvements. Comparing program administrator cost with the total cost of saved energy can indicate the degree to which programs leverage investment by participants. Based on reported total costs and savings information for U.S. utility efficiency programs from 2009 to 2013, we estimate the savings-weighted average total cost of saved electricity across 20 states at $0.046 per kilowatt-hour (kW h), comparing favorably with energy supply costs and retail rates. Programs targeted on the residential market averaged $0.030 per kW h compared to $0.053 per kW h for non-residential programs. Lighting programs, with an average total cost of $0.018 per kW h, drove lower savings costs in the residential market. We provide estimates for the most common program types and find that program administrators and participants on average are splitting the costs of efficiency in half. More consistent, standardized and complete reporting on efficiency programs is needed. Differing definitions and quantification of costs, savings and savings lifetimes pose challenges for comparing program results. Reducing these uncertainties could increase confidence in efficiency as a resource among planners and policymakers. - Highlights: • The cost of saved energy allows comparisons among energy resource investments. • Findings from the most expansive collection yet of total energy efficiency program costs. • The weighted average total cost of saved electricity was $0.046 for 20 states in 2009–2013. • Averages in the residential and non-residential sectors were $0.030 and $0.053 per kW h, respectively. • Results strongly indicate need for more consistent, reliable and complete reporting on efficiency programs.

  7. Estimation of hospital efficiency--do different definitions and casemix measures for hospital output affect the results?

    Science.gov (United States)

    Vitikainen, Kirsi; Street, Andrew; Linna, Miika

    2009-02-01

    Hospital efficiency has been the subject of numerous health economics studies, but there is little evidence on how the chosen output and casemix measures affect the efficiency results. The aim of this study is to examine the robustness of efficiency results due to these factors. Comparison is made between activities and episode output measures, and two different output grouping systems (Classic and FullDRG). Non-parametric data envelopment analysis is used as an analysis technique. The data consist of all public acute care hospitals in Finland in 2005 (n=40). Efficiency estimates were not found to be highly sensitive to the choice between episode and activity descriptions of output, but more so to the choice of DRG grouping system. Estimates are most sensitive to scale assumptions, with evidence of decreasing returns to scale in larger hospitals. Episode measures are generally to be preferred to activity measures because these better capture the patient pathway, while FullDRGs are preferred to Classic DRGs particularly because of the better description of outpatient output in the former grouping system. Attention should be paid to reducing the extent of scale inefficiency in Finland.

  8. Efficient bootstrap estimates for tail statistics

    Science.gov (United States)

    Breivik, Øyvind; Aarnes, Ole Johan

    2017-03-01

    Bootstrap resamples can be used to investigate the tail of empirical distributions as well as return value estimates from the extremal behaviour of the sample. Specifically, the confidence intervals on return value estimates or bounds on in-sample tail statistics can be obtained using bootstrap techniques. However, non-parametric bootstrapping from the entire sample is expensive. It is shown here that it suffices to bootstrap from a small subset consisting of the highest entries in the sequence to make estimates that are essentially identical to bootstraps from the entire sample. Similarly, bootstrap estimates of confidence intervals of threshold return estimates are found to be well approximated by using a subset consisting of the highest entries. This has practical consequences in fields such as meteorology, oceanography and hydrology where return values are calculated from very large gridded model integrations spanning decades at high temporal resolution or from large ensembles of independent and identically distributed model fields. In such cases the computational savings are substantial.

  9. Semiparametric efficient and robust estimation of an unknown symmetric population under arbitrary sample selection bias

    KAUST Repository

    Ma, Yanyuan

    2013-09-01

    We propose semiparametric methods to estimate the center and shape of a symmetric population when a representative sample of the population is unavailable due to selection bias. We allow an arbitrary sample selection mechanism determined by the data collection procedure, and we do not impose any parametric form on the population distribution. Under this general framework, we construct a family of consistent estimators of the center that is robust to population model misspecification, and we identify the efficient member that reaches the minimum possible estimation variance. The asymptotic properties and finite sample performance of the estimation and inference procedures are illustrated through theoretical analysis and simulations. A data example is also provided to illustrate the usefulness of the methods in practice. © 2013 American Statistical Association.

  10. Pathophysiological Alterations In The Basolateral Amygdala And Neurodegeneration Of Limbic Structures During Epileptogenesis Induced By Status Epilepticus

    Science.gov (United States)

    2009-02-05

    22 CHAPTER 2 TABLE 1 Stereological estimation of total Nissl - stained and GAD67-positive neurons in the BLA of sham control rats and KA-SE rats... Nissl - stained sections……………….... FIGURE 2 Counting site for stereological quantification of Nissl - stained neurons...FIGURE 3 Counting grid superimposed over tracing of BLA………………... 142 143 144 xii FIGURE 4 Disector height and guard zones in Nissl - stained

  11. A simple method for estimating the length density of convoluted tubular systems.

    Science.gov (United States)

    Ferraz de Carvalho, Cláudio A; de Campos Boldrini, Silvia; Nishimaru, Flávio; Liberti, Edson A

    2008-10-01

    We present a new method for estimating the length density (Lv) of convoluted tubular structures exhibiting an isotropic distribution. Although the traditional equation Lv=2Q/A is used, the parameter Q is obtained by considering the collective perimeters of tubular sections. This measurement is converted to a standard model of the structure, assuming that all cross-sections are approximately circular and have an average perimeter similar to that of actual circular cross-sections observed in the same material. The accuracy of this method was tested in eight experiments using hollow macaroni bent into helical shapes. After measuring the length of the macaroni segments, they were boiled and randomly packed into cylindrical volumes along with an aqueous suspension of gelatin and India ink. The solidified blocks were cut into slices 1.0 cm thick and 33.2 cm2 in area (A). The total perimeter of the macaroni cross-sections so revealed was stereologically estimated using a test system of straight parallel lines. Given Lv and the reference volume, the total length of macaroni in each section could be estimated. Additional corrections were made for the changes induced by boiling, and the off-axis position of the thread used to measure length. No statistical difference was observed between the corrected estimated values and the actual lengths. This technique is useful for estimating the length of capillaries, renal tubules, and seminiferous tubules.

  12. Estimation of Gasoline Price Elasticities of Demand for Automobile Fuel Efficiency in Korea: A Hedonic Approach

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Tae [Sungkyunkwan University, Seoul (Korea); Lee, Myunghun [Keimyung University, Taegu (Korea)

    2001-03-01

    This paper estimates the gasoline price elasticities of demand for automobile fuel efficiency in Korea to examine indirectly whether the government policy of raising fuel prices is effective in inducing less consumption of fuel, relying on a hedonic technique developed by Atkinson and Halvorsen (1984). One of the advantages of this technique is that the data for a single year, without involving variation in the price of gasoline, is sufficient in implementing this study. Moreover, this technique enables us to circumvent the multicollinearity problem, which had reduced reliability of the results in previous hedonic studies. The estimated elasticities of demand for fuel efficiency with respect to the price of gasoline, on average, is 0.42. (author). 30 refs., 3 tabs.

  13. Spatially Explicit Estimation of Optimal Light Use Efficiency for Improved Satellite Data Driven Ecosystem Productivity Modeling

    Science.gov (United States)

    Madani, N.; Kimball, J. S.; Running, S. W.

    2014-12-01

    Remote sensing based light use efficiency (LUE) models, including the MODIS (MODerate resolution Imaging Spectroradiometer) MOD17 algorithm are commonly used for regional estimation and monitoring of vegetation gross primary production (GPP) and photosynthetic carbon (CO2) uptake. A common model assumption is that plants in a biome matrix operate at their photosynthetic capacity under optimal climatic conditions. A prescribed biome maximum light use efficiency parameter defines the maximum photosynthetic carbon conversion rate under prevailing climate conditions and is a large source of model uncertainty. Here, we used tower (FLUXNET) eddy covariance measurement based carbon flux data for estimating optimal LUE (LUEopt) over a North American domain. LUEopt was first estimated using tower observed daily carbon fluxes, meteorology and satellite (MODIS) observed fraction of photosynthetically active radiation (FPAR). LUEopt was then spatially interpolated over the domain using empirical models derived from independent geospatial data including global plant traits, surface soil moisture, terrain aspect, land cover type and percent tree cover. The derived LUEopt maps were then used as primary inputs to the MOD17 LUE algorithm for regional GPP estimation; these results were evaluated against tower observations and alternate MOD17 GPP estimates determined using Biome-specific LUEopt constants. Estimated LUEopt shows large spatial variability within and among different land cover classes indicated from a sparse North American tower network. Leaf nitrogen content and soil moisture are two important factors explaining LUEopt spatial variability. GPP estimated from spatially explicit LUEopt inputs shows significantly improved model accuracy against independent tower observations (R2 = 0.76; Mean RMSE plant trait information can explain spatial heterogeneity in LUEopt, leading to improved GPP estimates from satellite based LUE models.

  14. Degeneration and regeneration of motor and sensory nerves: a stereological study of crush lesions in rat facial and mental nerves

    DEFF Research Database (Denmark)

    Barghash, Ziad; Larsen, Jytte Overgaard; Al-Bishri, Awad

    2013-01-01

    The aim of this study was to evaluate the degeneration and regeneration of a sensory nerve and a motor nerve at the histological level after a crush injury. Twenty-five female Wistar rats had their mental nerve and the buccal branch of their facial nerve compressed unilaterally against a glass rod...... for 30 s. Specimens of the compressed nerves and the corresponding control nerves were dissected at 3, 7, and 19 days after surgery. Nerve cross-sections were stained with osmium tetroxide and toluidine blue and analysed using two-dimensional stereology. We found differences between the two nerves both...... in the normal anatomy and in the regenerative pattern. The mental nerve had a larger cross-sectional area including all tissue components. The mental nerve had a larger volume fraction of myelinated axons and a correspondingly smaller volume fraction of endoneurium. No differences were observed...

  15. Estimation on separation efficiency of aluminum from base-cap of spent fluorescent lamp in hammer crusher unit.

    Science.gov (United States)

    Rhee, Seung-Whee

    2017-09-01

    In order to separate aluminum from the base-cap of spent fluorescent lamp (SFL), the separation efficiency of hammer crusher unit is estimated by introducing a binary separation theory. The base-cap of SFL is composed by glass fragment, binder, ferrous metal, copper and aluminum. The hammer crusher unit to recover aluminum from the base-cap consists of 3stages of hammer crusher, magnetic separator and vibrating screen. The optimal conditions of rotating speed and operating time in the hammer crusher unit are decided at each stage. At the optimal conditions, the aluminum yield and the separation efficiency of hammer crusher unit are estimated by applying a sequential binary separation theory at each stage. And the separation efficiency between hammer crusher unit and roll crush system is compared to show the performance of aluminum recovery from the base-cap of SFL. Since the separation efficiency can be increased to 99% at stage 3, from the experimental results, it is found that aluminum from the base-cap can be sufficiently recovered by the hammer crusher unit. Copyright © 2017. Published by Elsevier Ltd.

  16. Technical Note: On the efficiency of variance reduction techniques for Monte Carlo estimates of imaging noise.

    Science.gov (United States)

    Sharma, Diksha; Sempau, Josep; Badano, Aldo

    2018-02-01

    Monte Carlo simulations require large number of histories to obtain reliable estimates of the quantity of interest and its associated statistical uncertainty. Numerous variance reduction techniques (VRTs) have been employed to increase computational efficiency by reducing the statistical uncertainty. We investigate the effect of two VRTs for optical transport methods on accuracy and computing time for the estimation of variance (noise) in x-ray imaging detectors. We describe two VRTs. In the first, we preferentially alter the direction of the optical photons to increase detection probability. In the second, we follow only a fraction of the total optical photons generated. In both techniques, the statistical weight of photons is altered to maintain the signal mean. We use fastdetect2, an open-source, freely available optical transport routine from the hybridmantis package. We simulate VRTs for a variety of detector models and energy sources. The imaging data from the VRT simulations are then compared to the analog case (no VRT) using pulse height spectra, Swank factor, and the variance of the Swank estimate. We analyze the effect of VRTs on the statistical uncertainty associated with Swank factors. VRTs increased the relative efficiency by as much as a factor of 9. We demonstrate that we can achieve the same variance of the Swank factor with less computing time. With this approach, the simulations can be stopped when the variance of the variance estimates reaches the desired level of uncertainty. We implemented analytic estimates of the variance of Swank factor and demonstrated the effect of VRTs on image quality calculations. Our findings indicate that the Swank factor is dominated by the x-ray interaction profile as compared to the additional uncertainty introduced in the optical transport by the use of VRTs. For simulation experiments that aim at reducing the uncertainty in the Swank factor estimate, any of the proposed VRT can be used for increasing the relative

  17. Avoided cost estimation and post-reform funding allocation for California's energy efficiency programs

    International Nuclear Information System (INIS)

    Baskette, C.; Horii, B.; Price, S.; Kollman, E.

    2006-01-01

    This paper summarizes the first comprehensive estimation of California's electricity avoided costs since the state reformed its electricity market. It describes avoided cost estimates that vary by time and location, thus facilitating targeted design, funding, and marketing of demand-side management (DSM) and energy efficiency (EE) programs that could not have occurred under the previous methodology of system average cost estimation. The approach, data, and results reflect two important market structure changes: (a) wholesale spot and forward markets now supply electricity commodities to load serving entities; and (b) the evolution of an emissions market that internalizes and prices some of the externalities of electricity generation. The paper also introduces the multiplier effect of a price reduction due to DSM/EE implementation on electricity bills of all consumers. It affirms that area- and time-specific avoided cost estimates can improve the allocation of the state's public funding for DSM/EE programs, a finding that could benefit other parts of North America (e.g. Ontario and New York), which have undergone electricity deregulation. (author)

  18. An efficient algebraic approach to observability analysis in state estimation

    Energy Technology Data Exchange (ETDEWEB)

    Pruneda, R.E.; Solares, C.; Conejo, A.J. [University of Castilla-La Mancha, 13071 Ciudad Real (Spain); Castillo, E. [University of Cantabria, 39005 Santander (Spain)

    2010-03-15

    An efficient and compact algebraic approach to state estimation observability is proposed. It is based on transferring rows to columns and vice versa in the Jacobian measurement matrix. The proposed methodology provides a unified approach to observability checking, critical measurement identification, determination of observable islands, and selection of pseudo-measurements to restore observability. Additionally, the observability information obtained from a given set of measurements can provide directly the observability obtained from any subset of measurements of the given set. Several examples are used to illustrate the capabilities of the proposed methodology, and results from a large case study are presented to demonstrate the appropriate computational behavior of the proposed algorithms. Finally, some conclusions are drawn. (author)

  19. Estimating the energy and exergy utilization efficiencies for the residential-commercial sector: an application

    International Nuclear Information System (INIS)

    Utlu, Zafer; Hepbasli, Arif

    2006-01-01

    The main objectives in carrying out the present study are twofold, namely to estimate the energy and exergy utilization efficiencies for the residential-commercial sector and to compare those of various countries with each other. In this regard, Turkey is given as an illustrative example with its latest figures in 2002 since the data related to the following years are still being processed. Total energy and exergy inputs in this year are calculated to be 3257.20 and 3212.42 PJ, respectively. Annual fuel consumptions in space heating, water heating and cooking activities as well as electrical energy uses by appliances are also determined. The energy and exergy utilization efficiency values for the Turkish residential-commercial sector are obtained to be 55.58% and 9.33%, respectively. Besides this, Turkey's overall energy and exergy utilization efficiencies are found to be 46.02% and 24.99%, respectively. The present study clearly indicates the necessity of the planned studies toward increasing exergy utilization efficiencies in the sector studied

  20. Estimation of technical efficiency and it's determinants in the hybrid maize production in district chiniot: a cobb douglas model approach

    International Nuclear Information System (INIS)

    Naqvi, S.A.A.; Ashfaq, M.

    2014-01-01

    High yielding crop like maize is very important for countries like Pakistan, which is third cereal crop after wheat and rice. Maize accounts for 4.8 percent of the total cropped area and 4.82 percent of the value of agricultural production. It is grown all over the country but major areas are Sahiwal, Okara and Faisalabad. Chiniot is one of the distinct agroecological domains of central Punjab for the maize cultivation, that's why this district was selected for the study and the technical efficiency of hybrid maize farmers was estimated. The primary data of 120 farmers, 40 farmers from each of the three tehsils of Chiniot were collected in the year 2011. Causes of low yields for various farmers than the others, while using the same input bundle were estimated. The managerial factors causing the inefficiency of production were also measured. The average technical efficiency was estimated to be 91 percent, while it was found to be 94.8, 92.7 and 90.8 for large, medium and small farmers, respectively. Stochastic frontier production model was used to measure technical efficiency. Statistical software Frontier 4.1 was used to analyse the data to generate inferences because the estimates of efficiency were produced as a direct output from package. It was concluded that the efficiency can be enhanced by covering the inefficiency from the environmental variables, farmers personal characteristics and farming conditions. (author)

  1. Computationally Efficient 2D DOA Estimation for L-Shaped Array with Unknown Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Yang-Yang Dong

    2018-01-01

    Full Text Available Although L-shaped array can provide good angle estimation performance and is easy to implement, its two-dimensional (2D direction-of-arrival (DOA performance degrades greatly in the presence of mutual coupling. To deal with the mutual coupling effect, a novel 2D DOA estimation method for L-shaped array with low computational complexity is developed in this paper. First, we generalize the conventional mutual coupling model for L-shaped array and compensate the mutual coupling blindly via sacrificing a few sensors as auxiliary elements. Then we apply the propagator method twice to mitigate the effect of strong source signal correlation effect. Finally, the estimations of azimuth and elevation angles are achieved simultaneously without pair matching via the complex eigenvalue technique. Compared with the existing methods, the proposed method is computationally efficient without spectrum search or polynomial rooting and also has fine angle estimation performance for highly correlated source signals. Theoretical analysis and simulation results have demonstrated the effectiveness of the proposed method.

  2. ESTIMATION OF EFFICIENCY OF OPERATING SYSTEM OF TAX PLANNING IN THE COMMERCIAL ORGANIZATIONS

    Directory of Open Access Journals (Sweden)

    Evgeniy A. Samsonov

    2014-01-01

    Full Text Available Present clause is devoted to scientific judgement and estimations of efficiency of stimulating mechanisms (tools of application of system of tax planning in the commercial organizations which allow to estimate разнонаправленное influence of taxes on final financial result of the organization, and also to predict change of business activity of the organization depending on tax loading. The big attention is given to complicated questions of features of management by the taxation and the order of reflection in the tax account of the facts of the economic activities arising between the state, on the one hand, and managing subjects - the commercial organizations - with another.

  3. Fast and Statistically Efficient Fundamental Frequency Estimation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom

    2016-01-01

    Fundamental frequency estimation is a very important task in many applications involving periodic signals. For computational reasons, fast autocorrelation-based estimation methods are often used despite parametric estimation methods having superior estimation accuracy. However, these parametric...... a recursive solver. Via benchmarks, we demonstrate that the computation time is reduced by approximately two orders of magnitude. The proposed fast algorithm is available for download online....

  4. The estimation of energy efficiency for hybrid refrigeration system

    International Nuclear Information System (INIS)

    Gazda, Wiesław; Kozioł, Joachim

    2013-01-01

    Highlights: ► We present the experimental setup and the model of the hybrid cooling system. ► We examine impact of the operating parameters of the hybrid cooling system on the energy efficiency indicators. ► A comparison of the final and the primary energy use for a combination of the cooling systems is carried out. ► We explain the relationship between the COP and PER values for the analysed cooling systems. -- Abstract: The concept of the air blast-cryogenic freezing method (ABCF) is based on an innovative hybrid refrigeration system with one common cooling space. The hybrid cooling system consists of a vapor compression refrigeration system and a cryogenic refrigeration system. The prototype experimental setup for this method on the laboratory scale is discussed. The application of the results of experimental investigations and the theoretical–empirical model makes it possible to calculate the cooling capacity as well as the final and primary energy use in the hybrid system. The energetic analysis has been carried out for the operating modes of the refrigerating systems for the required temperatures inside the cooling chamber of −5 °C, −10 °C and −15 °C. For the estimation of the energy efficiency the coefficient of performance COP and the primary energy ratio PER for the hybrid refrigeration system are proposed. A comparison of these coefficients for the vapor compression refrigeration and the cryogenic refrigeration system has also been presented.

  5. The optical rotator

    DEFF Research Database (Denmark)

    Tandrup, T; Gundersen, Hans Jørgen Gottlieb; Jensen, Eva B. Vedel

    1997-01-01

    further discuss the methods derived from this principle and present two new local volume estimators. The optical rotator benefits from information obtained in all three dimensions in thick sections but avoids over-/ underprojection problems at the extremes of the cell. Using computer-assisted microscopes......The optical rotator is an unbiased, local stereological principle for estimation of cell volume and cell surface area in thick, transparent slabs, The underlying principle was first described in 1993 by Kieu Jensen (T. Microsc. 170, 45-51) who also derived an estimator of length, In this study we...... the extra measurements demand minimal extra effort and make this estimator even more efficient when it comes to estimation of individual cell size than many of the previous local estimators, We demonstrate the principle of the optical rotator in an example (the cells in the dorsal root ganglion of the rat...

  6. Efficient Bayesian Compressed Sensing-based Channel Estimation Techniques for Massive MIMO-OFDM Systems

    OpenAIRE

    Al-Salihi, Hayder Qahtan Kshash; Nakhai, Mohammad Reza

    2017-01-01

    Efficient and highly accurate channel state information (CSI) at the base station (BS) is essential to achieve the potential benefits of massive multiple input multiple output (MIMO) systems. However, the achievable accuracy that is attainable is limited in practice due to the problem of pilot contamination. It has recently been shown that compressed sensing (CS) techniques can address the pilot contamination problem. However, CS-based channel estimation requires prior knowledge of channel sp...

  7. Estimation of combustion flue gas acid dew point during heat recovery and efficiency gain

    Energy Technology Data Exchange (ETDEWEB)

    Bahadori, A. [Curtin University of Technology, Perth, WA (Australia)

    2011-06-15

    When cooling combustion flue gas for heat recovery and efficiency gain, the temperature must not be allowed to drop below the sulfur trioxide dew point. Below the SO{sub 3} dew point, very corrosive sulfuric acid forms and leads to operational hazards on metal surfaces. In the present work, simple-to-use predictive tool, which is easier than existing approaches, less complicated with fewer computations is formulated to arrive at an appropriate estimation of acid dew point during combustion flue gas cooling which depends on fuel type, sulfur content in fuel, and excess air levels. The resulting information can then be applied to estimate the acid dew point, for sulfur in various fuels up to 0.10 volume fraction in gas (0.10 mass fraction in liquid), excess air fractions up to 0.25, and elemental concentrations of carbon up to 3. The proposed predictive tool shows a very good agreement with the reported data wherein the average absolute deviation percent was found to be around 3.18%. This approach can be of immense practical value for engineers and scientists for a quick estimation of acid dew point during combustion flue gas cooling for heat recovery and efficiency gain for wide range of operating conditions without the necessity of any pilot plant setup and tedious experimental trials. In particular, process and combustion engineers would find the tool to be user friendly involving transparent calculations with no complex expressions for their applications.

  8. Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle

    Directory of Open Access Journals (Sweden)

    Junpeng Shi

    2017-02-01

    Full Text Available In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS method for two-dimensional direction of arrival (2D DOA estimation with uniform rectangular arrays (URAs in a low-grazing angle (LGA condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions.

  9. Efficient Bayesian estimates for discrimination among topologically different systems biology models.

    Science.gov (United States)

    Hagen, David R; Tidor, Bruce

    2015-02-01

    A major effort in systems biology is the development of mathematical models that describe complex biological systems at multiple scales and levels of abstraction. Determining the topology-the set of interactions-of a biological system from observations of the system's behavior is an important and difficult problem. Here we present and demonstrate new methodology for efficiently computing the probability distribution over a set of topologies based on consistency with existing measurements. Key features of the new approach include derivation in a Bayesian framework, incorporation of prior probability distributions of topologies and parameters, and use of an analytically integrable linearization based on the Fisher information matrix that is responsible for large gains in efficiency. The new method was demonstrated on a collection of four biological topologies representing a kinase and phosphatase that operate in opposition to each other with either processive or distributive kinetics, giving 8-12 parameters for each topology. The linearization produced an approximate result very rapidly (CPU minutes) that was highly accurate on its own, as compared to a Monte Carlo method guaranteed to converge to the correct answer but at greater cost (CPU weeks). The Monte Carlo method developed and applied here used the linearization method as a starting point and importance sampling to approach the Bayesian answer in acceptable time. Other inexpensive methods to estimate probabilities produced poor approximations for this system, with likelihood estimation showing its well-known bias toward topologies with more parameters and the Akaike and Schwarz Information Criteria showing a strong bias toward topologies with fewer parameters. These results suggest that this linear approximation may be an effective compromise, providing an answer whose accuracy is near the true Bayesian answer, but at a cost near the common heuristics.

  10. Stereological estimates of nuclear volume in thin malignant melanomas

    DEFF Research Database (Denmark)

    Björnhagen, V; Månsson-Brahme, E; Lindholm, J

    1998-01-01

    melanomas were individually compared with 33 thin non-metastasizing melanomas after individual matching of cases with one or two randomly chosen controls for site of primary tumour, tumour thickness, level of invasion, tumour regression and follow-up. Conditional logistic regression analysis showed...

  11. OPTIMIZATION OF THE CRITERION FOR ESTIMATING THE TECHNOLOGY EFFICIENCY OF PACKING-CASE-PIECE LOADS DELIVERY

    OpenAIRE

    O. Severyn; O. Shulika

    2017-01-01

    The results of optimization of gravimetric coefficients for indexes included in the integral criterion of estimation of the efficiency of transport-technological charts of cargo delivery are resulted. The values of gravimetric coefficients are determined on the basis of two methods of experimental researches: questioning of respondents among the specialists of motor transport production and imitation design.

  12. Simple, efficient estimators of treatment effects in randomized trials using generalized linear models to leverage baseline variables.

    Science.gov (United States)

    Rosenblum, Michael; van der Laan, Mark J

    2010-04-01

    Models, such as logistic regression and Poisson regression models, are often used to estimate treatment effects in randomized trials. These models leverage information in variables collected before randomization, in order to obtain more precise estimates of treatment effects. However, there is the danger that model misspecification will lead to bias. We show that certain easy to compute, model-based estimators are asymptotically unbiased even when the working model used is arbitrarily misspecified. Furthermore, these estimators are locally efficient. As a special case of our main result, we consider a simple Poisson working model containing only main terms; in this case, we prove the maximum likelihood estimate of the coefficient corresponding to the treatment variable is an asymptotically unbiased estimator of the marginal log rate ratio, even when the working model is arbitrarily misspecified. This is the log-linear analog of ANCOVA for linear models. Our results demonstrate one application of targeted maximum likelihood estimation.

  13. Simple, Efficient Estimators of Treatment Effects in Randomized Trials Using Generalized Linear Models to Leverage Baseline Variables

    Science.gov (United States)

    Rosenblum, Michael; van der Laan, Mark J.

    2010-01-01

    Models, such as logistic regression and Poisson regression models, are often used to estimate treatment effects in randomized trials. These models leverage information in variables collected before randomization, in order to obtain more precise estimates of treatment effects. However, there is the danger that model misspecification will lead to bias. We show that certain easy to compute, model-based estimators are asymptotically unbiased even when the working model used is arbitrarily misspecified. Furthermore, these estimators are locally efficient. As a special case of our main result, we consider a simple Poisson working model containing only main terms; in this case, we prove the maximum likelihood estimate of the coefficient corresponding to the treatment variable is an asymptotically unbiased estimator of the marginal log rate ratio, even when the working model is arbitrarily misspecified. This is the log-linear analog of ANCOVA for linear models. Our results demonstrate one application of targeted maximum likelihood estimation. PMID:20628636

  14. Scaling gross ecosystem production at Harvard Forest with remote sensing: a comparison of estimates from a constrained quantum-use efficiency model and eddy correlation

    International Nuclear Information System (INIS)

    Waring, R.H.; Law, B.E.; Goulden, M.L.; Bassow, S.L.; McCreight, R.W.; Wofsy, S.C.; Bazzaz, F.A.

    1995-01-01

    Two independent methods of estimating gross ecosystem production (GEP) were compared over a period of 2 years at monthly integrals for a mixed forest of conifers and deciduous hardwoods at Harvard Forest in central Massachusetts. Continuous eddy flux measurements of net ecosystem exchange (NEE) provided one estimate of GEP by taking day to night temperature differences into account to estimate autotrophic and heterotrophic respiration. GEP was also estimated with a quantum efficiency model based on measurements of maximum quantum efficiency (Qmax), seasonal variation in canopy phenology and chlorophyll content, incident PAR, and the constraints of freezing temperatures and vapour pressure deficits on stomatal conductance. Quantum efficiency model estimates of GEP and those derived from eddy flux measurements compared well at monthly integrals over two consecutive years (R 2 = 0–98). Remotely sensed data were acquired seasonally with an ultralight aircraft to provide a means of scaling the leaf area and leaf pigmentation changes that affected the light absorption of photosynthetically active radiation to larger areas. A linear correlation between chlorophyll concentrations in the upper canopy leaves of four hardwood species and their quantum efficiencies (R 2 = 0–99) suggested that seasonal changes in quantum efficiency for the entire canopy can be quantified with remotely sensed indices of chlorophyll. Analysis of video data collected from the ultralight aircraft indicated that the fraction of conifer cover varied from < 7% near the instrument tower to about 25% for a larger sized area. At 25% conifer cover, the quantum efficiency model predicted an increase in the estimate of annual GEP of < 5% because unfavourable environmental conditions limited conifer photosynthesis in much of the non-growing season when hardwoods lacked leaves

  15. Statistically Efficient Methods for Pitch and DOA Estimation

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2013-01-01

    , it was recently considered to estimate the DOA and pitch jointly. In this paper, we propose two novel methods for DOA and pitch estimation. They both yield maximum-likelihood estimates in white Gaussian noise scenar- ios, where the SNR may be different across channels, as opposed to state-of-the-art methods......Traditionally, direction-of-arrival (DOA) and pitch estimation of multichannel, periodic sources have been considered as two separate problems. Separate estimation may render the task of resolving sources with similar DOA or pitch impossible, and it may decrease the estimation accuracy. Therefore...

  16. Efficient Estimating Functions for Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Jakobsen, Nina Munkholt

    The overall topic of this thesis is approximate martingale estimating function-based estimationfor solutions of stochastic differential equations, sampled at high frequency. Focuslies on the asymptotic properties of the estimators. The first part of the thesis deals with diffusions observed over...... a fixed time interval. Rate optimal and effcient estimators areobtained for a one-dimensional diffusion parameter. Stable convergence in distribution isused to achieve a practically applicable Gaussian limit distribution for suitably normalisedestimators. In a simulation example, the limit distributions...... multidimensional parameter. Conditions for rate optimality and effciency of estimatorsof drift-jump and diffusion parameters are given in some special cases. Theseconditions are found to extend the pre-existing conditions applicable to continuous diffusions,and impose much stronger requirements on the estimating...

  17. Efficient estimation of an additive quantile regression model

    NARCIS (Netherlands)

    Cheng, Y.; de Gooijer, J.G.; Zerom, D.

    2011-01-01

    In this paper, two non-parametric estimators are proposed for estimating the components of an additive quantile regression model. The first estimator is a computationally convenient approach which can be viewed as a more viable alternative to existing kernel-based approaches. The second estimator

  18. Effect of LET on the efficiency of dose re-estimation in LiF using uv photo-transfer

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, J A; Baker, D M; Marshall, M; Budd, T [UKAEA Atomic Energy Research Establishment, Harwell. Environmental and Medical Sciences Div.

    1980-09-01

    Glow curves from TLD600 and TLD700 extruded rods exposed to ..gamma..-, X- and neutron radiations have been compared before and after uv photo-transfer. Re-estimation efficiency increases with LET by an amount which varies from batch to batch.

  19. An Efficient Acoustic Density Estimation Method with Human Detectors Applied to Gibbons in Cambodia.

    Directory of Open Access Journals (Sweden)

    Darren Kidney

    Full Text Available Some animal species are hard to see but easy to hear. Standard visual methods for estimating population density for such species are often ineffective or inefficient, but methods based on passive acoustics show more promise. We develop spatially explicit capture-recapture (SECR methods for territorial vocalising species, in which humans act as an acoustic detector array. We use SECR and estimated bearing data from a single-occasion acoustic survey of a gibbon population in northeastern Cambodia to estimate the density of calling groups. The properties of the estimator are assessed using a simulation study, in which a variety of survey designs are also investigated. We then present a new form of the SECR likelihood for multi-occasion data which accounts for the stochastic availability of animals. In the context of gibbon surveys this allows model-based estimation of the proportion of groups that produce territorial vocalisations on a given day, thereby enabling the density of groups, instead of the density of calling groups, to be estimated. We illustrate the performance of this new estimator by simulation. We show that it is possible to estimate density reliably from human acoustic detections of visually cryptic species using SECR methods. For gibbon surveys we also show that incorporating observers' estimates of bearings to detected groups substantially improves estimator performance. Using the new form of the SECR likelihood we demonstrate that estimates of availability, in addition to population density and detection function parameters, can be obtained from multi-occasion data, and that the detection function parameters are not confounded with the availability parameter. This acoustic SECR method provides a means of obtaining reliable density estimates for territorial vocalising species. It is also efficient in terms of data requirements since since it only requires routine survey data. We anticipate that the low-tech field requirements will

  20. Accounting for the decrease of photosystem photochemical efficiency with increasing irradiance to estimate quantum yield of leaf photosynthesis.

    Science.gov (United States)

    Yin, Xinyou; Belay, Daniel W; van der Putten, Peter E L; Struik, Paul C

    2014-12-01

    Maximum quantum yield for leaf CO2 assimilation under limiting light conditions (Φ CO2LL) is commonly estimated as the slope of the linear regression of net photosynthetic rate against absorbed irradiance over a range of low-irradiance conditions. Methodological errors associated with this estimation have often been attributed either to light absorptance by non-photosynthetic pigments or to some data points being beyond the linear range of the irradiance response, both causing an underestimation of Φ CO2LL. We demonstrate here that a decrease in photosystem (PS) photochemical efficiency with increasing irradiance, even at very low levels, is another source of error that causes a systematic underestimation of Φ CO2LL. A model method accounting for this error was developed, and was used to estimate Φ CO2LL from simultaneous measurements of gas exchange and chlorophyll fluorescence on leaves using various combinations of species, CO2, O2, or leaf temperature levels. The conventional linear regression method under-estimated Φ CO2LL by ca. 10-15%. Differences in the estimated Φ CO2LL among measurement conditions were generally accounted for by different levels of photorespiration as described by the Farquhar-von Caemmerer-Berry model. However, our data revealed that the temperature dependence of PSII photochemical efficiency under low light was an additional factor that should be accounted for in the model.

  1. Efficient 3D movement-based kernel density estimator and application to wildlife ecology

    Science.gov (United States)

    Tracey-PR, Jeff; Sheppard, James K.; Lockwood, Glenn K.; Chourasia, Amit; Tatineni, Mahidhar; Fisher, Robert N.; Sinkovits, Robert S.

    2014-01-01

    We describe an efficient implementation of a 3D movement-based kernel density estimator for determining animal space use from discrete GPS measurements. This new method provides more accurate results, particularly for species that make large excursions in the vertical dimension. The downside of this approach is that it is much more computationally expensive than simpler, lower-dimensional models. Through a combination of code restructuring, parallelization and performance optimization, we were able to reduce the time to solution by up to a factor of 1000x, thereby greatly improving the applicability of the method.

  2. Efficient Estimating Functions for Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Jakobsen, Nina Munkholt

    The overall topic of this thesis is approximate martingale estimating function-based estimationfor solutions of stochastic differential equations, sampled at high frequency. Focuslies on the asymptotic properties of the estimators. The first part of the thesis deals with diffusions observed over...

  3. Estimating the changes in the distribution of energy efficiency in the U.S. automobile assembly industry

    International Nuclear Information System (INIS)

    Boyd, Gale A.

    2014-01-01

    This paper describes the EPA's voluntary ENERGY STAR program and the results of the automobile manufacturing industry's efforts to advance energy management as measured by the updated ENERGY STAR Energy Performance Indicator (EPI). A stochastic single-factor input frontier estimation using the gamma error distribution is applied to separately estimate the distribution of the electricity and fossil fuel efficiency of assembly plants using data from 2003 to 2005 and then compared to model results from a prior analysis conducted for the 1997–2000 time period. This comparison provides an assessment of how the industry has changed over time. The frontier analysis shows a modest improvement (reduction) in “best practice” for electricity use and a larger one for fossil fuels. This is accompanied by a large reduction in the variance of fossil fuel efficiency distribution. The results provide evidence of a shift in the frontier, in addition to some “catching up” of poor performing plants over time. - Highlights: • A non-public dataset of U.S. auto manufacturing plants is compiled. • A stochastic frontier with a gamma distribution is applied to plant level data. • Electricity and fuel use are modeled separately. • Comparison to prior analysis reveals a shift in the frontier and “catching up”. • Results are used by ENERGY STAR to award energy efficiency plant certifications

  4. FAST LABEL: Easy and efficient solution of joint multi-label and estimation problems

    KAUST Repository

    Sundaramoorthi, Ganesh

    2014-06-01

    We derive an easy-to-implement and efficient algorithm for solving multi-label image partitioning problems in the form of the problem addressed by Region Competition. These problems jointly determine a parameter for each of the regions in the partition. Given an estimate of the parameters, a fast approximate solution to the multi-label sub-problem is derived by a global update that uses smoothing and thresholding. The method is empirically validated to be robust to fine details of the image that plague local solutions. Further, in comparison to global methods for the multi-label problem, the method is more efficient and it is easy for a non-specialist to implement. We give sample Matlab code for the multi-label Chan-Vese problem in this paper! Experimental comparison to the state-of-the-art in multi-label solutions to Region Competition shows that our method achieves equal or better accuracy, with the main advantage being speed and ease of implementation.

  5. Energy-Efficient Channel Estimation in MIMO Systems

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The emergence of MIMO communications systems as practical high-data-rate wireless communications systems has created several technical challenges to be met. On the one hand, there is potential for enhancing system performance in terms of capacity and diversity. On the other hand, the presence of multiple transceivers at both ends has created additional cost in terms of hardware and energy consumption. For coherent detection as well as to do optimization such as water filling and beamforming, it is essential that the MIMO channel is known. However, due to the presence of multiple transceivers at both the transmitter and receiver, the channel estimation problem is more complicated and costly compared to a SISO system. Several solutions have been proposed to minimize the computational cost, and hence the energy spent in channel estimation of MIMO systems. We present a novel method of minimizing the overall energy consumption. Unlike existing methods, we consider the energy spent during the channel estimation phase which includes transmission of training symbols, storage of those symbols at the receiver, and also channel estimation at the receiver. We develop a model that is independent of the hardware or software used for channel estimation, and use a divide-and-conquer strategy to minimize the overall energy consumption.

  6. ON THE PRECISION OF THE NUCLEATOR

    Directory of Open Access Journals (Sweden)

    Javier González-Villa

    2017-06-01

    Full Text Available The nucleator is a design unbiased method of local stereology for estimating the volume of a bounded object. The only information required lies in the intersection of the object with an isotropic random ray emanating from a fixed point (called the pivotal point associated with the object. For instance, the volume of a neuron can be estimated from a random ray emanating from its nucleolus. The nucleator is extensively used in biosciences because it is efficient and easy to apply. The estimator variance can be reduced by increasing the number of rays. In an earlier paper a systematic sampling design was proposed, and theoretical variance predictors were derived, for the corresponding volume estimator. Being the only variance predictors hitherto available for the nucleator, our basic goal was to check their statistical performance by means of Monte Carlo resampling on computer reconstructions of real objects. As a plus, the empirical distribution of the volume estimator revealed statistical properties of practical relevance.

  7. A note on the estimation of the Pareto efficient set for multiobjective matrix permutation problems.

    Science.gov (United States)

    Brusco, Michael J; Steinley, Douglas

    2012-02-01

    There are a number of important problems in quantitative psychology that require the identification of a permutation of the n rows and columns of an n × n proximity matrix. These problems encompass applications such as unidimensional scaling, paired-comparison ranking, and anti-Robinson forms. The importance of simultaneously incorporating multiple objective criteria in matrix permutation applications is well recognized in the literature; however, to date, there has been a reliance on weighted-sum approaches that transform the multiobjective problem into a single-objective optimization problem. Although exact solutions to these single-objective problems produce supported Pareto efficient solutions to the multiobjective problem, many interesting unsupported Pareto efficient solutions may be missed. We illustrate the limitation of the weighted-sum approach with an example from the psychological literature and devise an effective heuristic algorithm for estimating both the supported and unsupported solutions of the Pareto efficient set. © 2011 The British Psychological Society.

  8. Efficient Monte Carlo Estimation of the Expected Value of Sample Information Using Moment Matching.

    Science.gov (United States)

    Heath, Anna; Manolopoulou, Ioanna; Baio, Gianluca

    2018-02-01

    The Expected Value of Sample Information (EVSI) is used to calculate the economic value of a new research strategy. Although this value would be important to both researchers and funders, there are very few practical applications of the EVSI. This is due to computational difficulties associated with calculating the EVSI in practical health economic models using nested simulations. We present an approximation method for the EVSI that is framed in a Bayesian setting and is based on estimating the distribution of the posterior mean of the incremental net benefit across all possible future samples, known as the distribution of the preposterior mean. Specifically, this distribution is estimated using moment matching coupled with simulations that are available for probabilistic sensitivity analysis, which is typically mandatory in health economic evaluations. This novel approximation method is applied to a health economic model that has previously been used to assess the performance of other EVSI estimators and accurately estimates the EVSI. The computational time for this method is competitive with other methods. We have developed a new calculation method for the EVSI which is computationally efficient and accurate. This novel method relies on some additional simulation so can be expensive in models with a large computational cost.

  9. Oracle Efficient Estimation and Forecasting with the Adaptive LASSO and the Adaptive Group LASSO in Vector Autoregressions

    DEFF Research Database (Denmark)

    Kock, Anders Bredahl; Callot, Laurent

    We show that the adaptive Lasso (aLasso) and the adaptive group Lasso (agLasso) are oracle efficient in stationary vector autoregressions where the number of parameters per equation is smaller than the number of observations. In particular, this means that the parameters are estimated consistently...

  10. Estimating Origin-Destination Matrices Using AN Efficient Moth Flame-Based Spatial Clustering Approach

    Science.gov (United States)

    Heidari, A. A.; Moayedi, A.; Abbaspour, R. Ali

    2017-09-01

    Automated fare collection (AFC) systems are regarded as valuable resources for public transport planners. In this paper, the AFC data are utilized to analysis and extract mobility patterns in a public transportation system. For this purpose, the smart card data are inserted into a proposed metaheuristic-based aggregation model and then converted to O-D matrix between stops, since the size of O-D matrices makes it difficult to reproduce the measured passenger flows precisely. The proposed strategy is applied to a case study from Haaglanden, Netherlands. In this research, moth-flame optimizer (MFO) is utilized and evaluated for the first time as a new metaheuristic algorithm (MA) in estimating transit origin-destination matrices. The MFO is a novel, efficient swarm-based MA inspired from the celestial navigation of moth insects in nature. To investigate the capabilities of the proposed MFO-based approach, it is compared to methods that utilize the K-means algorithm, gray wolf optimization algorithm (GWO) and genetic algorithm (GA). The sum of the intra-cluster distances and computational time of operations are considered as the evaluation criteria to assess the efficacy of the optimizers. The optimality of solutions of different algorithms is measured in detail. The traveler's behavior is analyzed to achieve to a smooth and optimized transport system. The results reveal that the proposed MFO-based aggregation strategy can outperform other evaluated approaches in terms of convergence tendency and optimality of the results. The results show that it can be utilized as an efficient approach to estimating the transit O-D matrices.

  11. ESTIMATING ORIGIN-DESTINATION MATRICES USING AN EFFICIENT MOTH FLAME-BASED SPATIAL CLUSTERING APPROACH

    Directory of Open Access Journals (Sweden)

    A. A. Heidari

    2017-09-01

    Full Text Available Automated fare collection (AFC systems are regarded as valuable resources for public transport planners. In this paper, the AFC data are utilized to analysis and extract mobility patterns in a public transportation system. For this purpose, the smart card data are inserted into a proposed metaheuristic-based aggregation model and then converted to O-D matrix between stops, since the size of O-D matrices makes it difficult to reproduce the measured passenger flows precisely. The proposed strategy is applied to a case study from Haaglanden, Netherlands. In this research, moth-flame optimizer (MFO is utilized and evaluated for the first time as a new metaheuristic algorithm (MA in estimating transit origin-destination matrices. The MFO is a novel, efficient swarm-based MA inspired from the celestial navigation of moth insects in nature. To investigate the capabilities of the proposed MFO-based approach, it is compared to methods that utilize the K-means algorithm, gray wolf optimization algorithm (GWO and genetic algorithm (GA. The sum of the intra-cluster distances and computational time of operations are considered as the evaluation criteria to assess the efficacy of the optimizers. The optimality of solutions of different algorithms is measured in detail. The traveler's behavior is analyzed to achieve to a smooth and optimized transport system. The results reveal that the proposed MFO-based aggregation strategy can outperform other evaluated approaches in terms of convergence tendency and optimality of the results. The results show that it can be utilized as an efficient approach to estimating the transit O-D matrices.

  12. Efficient dense blur map estimation for automatic 2D-to-3D conversion

    Science.gov (United States)

    Vosters, L. P. J.; de Haan, G.

    2012-03-01

    Focus is an important depth cue for 2D-to-3D conversion of low depth-of-field images and video. However, focus can be only reliably estimated on edges. Therefore, Bea et al. [1] first proposed an optimization based approach to propagate focus to non-edge image portions, for single image focus editing. While their approach produces accurate dense blur maps, the computational complexity and memory requirements for solving the resulting sparse linear system with standard multigrid or (multilevel) preconditioning techniques, are infeasible within the stringent requirements of the consumer electronics and broadcast industry. In this paper we propose fast, efficient, low latency, line scanning based focus propagation, which mitigates the need for complex multigrid or (multilevel) preconditioning techniques. In addition we propose facial blur compensation to compensate for false shading edges that cause incorrect blur estimates in people's faces. In general shading leads to incorrect focus estimates, which may lead to unnatural 3D and visual discomfort. Since visual attention mostly tends to faces, our solution solves the most distracting errors. A subjective assessment by paired comparison on a set of challenging low-depth-of-field images shows that the proposed approach achieves equal 3D image quality as optimization based approaches, and that facial blur compensation results in a significant improvement.

  13. An Investigation of the High Efficiency Estimation Approach of the Large-Scale Scattered Point Cloud Normal Vector

    Directory of Open Access Journals (Sweden)

    Xianglin Meng

    2018-03-01

    Full Text Available The normal vector estimation of the large-scale scattered point cloud (LSSPC plays an important role in point-based shape editing. However, the normal vector estimation for LSSPC cannot meet the great challenge of the sharp increase of the point cloud that is mainly attributed to its low computational efficiency. In this paper, a novel, fast method-based on bi-linear interpolation is reported on the normal vector estimation for LSSPC. We divide the point sets into many small cubes to speed up the local point search and construct interpolation nodes on the isosurface expressed by the point cloud. On the premise of calculating the normal vectors of these interpolated nodes, a normal vector bi-linear interpolation of the points in the cube is realized. The proposed approach has the merits of accurate, simple, and high efficiency, because the algorithm only needs to search neighbor and calculates normal vectors for interpolation nodes that are usually far less than the point cloud. The experimental results of several real and simulated point sets show that our method is over three times faster than the Elliptic Gabriel Graph-based method, and the average deviation is less than 0.01 mm.

  14. Efficient estimation of an additive quantile regression model

    NARCIS (Netherlands)

    Cheng, Y.; de Gooijer, J.G.; Zerom, D.

    2009-01-01

    In this paper two kernel-based nonparametric estimators are proposed for estimating the components of an additive quantile regression model. The first estimator is a computationally convenient approach which can be viewed as a viable alternative to the method of De Gooijer and Zerom (2003). By

  15. Efficient estimation of an additive quantile regression model

    NARCIS (Netherlands)

    Cheng, Y.; de Gooijer, J.G.; Zerom, D.

    2010-01-01

    In this paper two kernel-based nonparametric estimators are proposed for estimating the components of an additive quantile regression model. The first estimator is a computationally convenient approach which can be viewed as a viable alternative to the method of De Gooijer and Zerom (2003). By

  16. Ultrasound elastography: efficient estimation of tissue displacement using an affine transformation model

    Science.gov (United States)

    Hashemi, Hoda Sadat; Boily, Mathieu; Martineau, Paul A.; Rivaz, Hassan

    2017-03-01

    Ultrasound elastography entails imaging mechanical properties of tissue and is therefore of significant clinical importance. In elastography, two frames of radio-frequency (RF) ultrasound data that are obtained while the tissue is undergoing deformation, and the time-delay estimate (TDE) between the two frames is used to infer mechanical properties of tissue. TDE is a critical step in elastography, and is challenging due to noise and signal decorrelation. This paper presents a novel and robust technique TDE using all samples of RF data simultaneously. We assume tissue deformation can be approximated by an affine transformation, and hence call our method ATME (Affine Transformation Model Elastography). The affine transformation model is utilized to obtain initial estimates of axial and lateral displacement fields. The affine transformation only has six degrees of freedom (DOF), and as such, can be efficiently estimated. A nonlinear cost function that incorporates similarity of RF data intensity and prior information of displacement continuity is formulated to fine-tune the initial affine deformation field. Optimization of this function involves searching for TDE of all samples of the RF data. The optimization problem is converted to a sparse linear system of equations, which can be solved in real-time. Results on simulation are presented for validation. We further collect RF data from in-vivo patellar tendon and medial collateral ligament (MCL), and show that ATME can be used to accurately track tissue displacement.

  17. The Cellular Composition and Glia-Neuron Ratio in the Spinal Cord of a Human and a Nonhuman Primate: Comparison With Other Species and Brain Regions.

    Science.gov (United States)

    Bahney, Jami; von Bartheld, Christopher S

    2018-04-01

    The cellular composition of brains shows largely conserved, gradual evolutionary trends between species. In the primate spinal cord, however, the glia-neuron ratio was reported to be greatly increased over that in the rodent spinal cord. Here, we re-examined the cellular composition of the spinal cord of one human and one nonhuman primate species by employing two different counting methods, the isotropic fractionator and stereology. We also determined whether segmental differences in cellular composition, possibly reflecting increased fine motor control of the upper extremities, may explain a sharply increased glia-neuron ratio in primates. In the cynomolgus monkey spinal cord, the isotropic fractionator and stereology yielded 206-275 million cells, of which 13.3-25.1% were neurons (28-69 million). Stereological estimates yielded 21.1% endothelial cells and 65.5% glial cells (glia-neuron ratio of 4.9-5.6). In human spinal cords, the isotropic fractionator and stereology generated estimates of 1.5-1.7 billion cells and 197-222 million neurons (13.4% neurons, 12.2% endothelial cells, 74.8% glial cells), and a glia-neuron ratio of 5.6-7.1, with estimates of neuron numbers in the human spinal cord based on morphological criteria. The non-neuronal to neuron ratios in human and cynomolgus monkey spinal cords were 6.5 and 3.2, respectively, suggesting that previous reports overestimated this ratio. We did not find significant segmental differences in the cellular composition between cervical, thoracic and lumbar levels. When compared with brain regions, the spinal cord showed gradual increases of the glia-neuron ratio with increasing brain mass, similar to the cerebral cortex and the brainstem. Anat Rec, 301:697-710, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  18. Estimation of Radiative Efficiency of Chemicals with Potentially Significant Global Warming Potential.

    Science.gov (United States)

    Betowski, Don; Bevington, Charles; Allison, Thomas C

    2016-01-19

    Halogenated chemical substances are used in a broad array of applications, and new chemical substances are continually being developed and introduced into commerce. While recent research has considerably increased our understanding of the global warming potentials (GWPs) of multiple individual chemical substances, this research inevitably lags behind the development of new chemical substances. There are currently over 200 substances known to have high GWP. Evaluation of schemes to estimate radiative efficiency (RE) based on computational chemistry are useful where no measured IR spectrum is available. This study assesses the reliability of values of RE calculated using computational chemistry techniques for 235 chemical substances against the best available values. Computed vibrational frequency data is used to estimate RE values using several Pinnock-type models, and reasonable agreement with reported values is found. Significant improvement is obtained through scaling of both vibrational frequencies and intensities. The effect of varying the computational method and basis set used to calculate the frequency data is discussed. It is found that the vibrational intensities have a strong dependence on basis set and are largely responsible for differences in computed RE values.

  19. Efficient Estimation of Dynamic Density Functions with Applications in Streaming Data

    KAUST Repository

    Qahtan, Abdulhakim

    2016-05-11

    Recent advances in computing technology allow for collecting vast amount of data that arrive continuously in the form of streams. Mining data streams is challenged by the speed and volume of the arriving data. Furthermore, the underlying distribution of the data changes over the time in unpredicted scenarios. To reduce the computational cost, data streams are often studied in forms of condensed representation, e.g., Probability Density Function (PDF). This thesis aims at developing an online density estimator that builds a model called KDE-Track for characterizing the dynamic density of the data streams. KDE-Track estimates the PDF of the stream at a set of resampling points and uses interpolation to estimate the density at any given point. To reduce the interpolation error and computational complexity, we introduce adaptive resampling where more/less resampling points are used in high/low curved regions of the PDF. The PDF values at the resampling points are updated online to provide up-to-date model of the data stream. Comparing with other existing online density estimators, KDE-Track is often more accurate (as reflected by smaller error values) and more computationally efficient (as reflected by shorter running time). The anytime available PDF estimated by KDE-Track can be applied for visualizing the dynamic density of data streams, outlier detection and change detection in data streams. In this thesis work, the first application is to visualize the taxi traffic volume in New York city. Utilizing KDE-Track allows for visualizing and monitoring the traffic flow on real time without extra overhead and provides insight analysis of the pick up demand that can be utilized by service providers to improve service availability. The second application is to detect outliers in data streams from sensor networks based on the estimated PDF. The method detects outliers accurately and outperforms baseline methods designed for detecting and cleaning outliers in sensor data. The

  20. Improving Global Gross Primary Productivity Estimates by Computing Optimum Light Use Efficiencies Using Flux Tower Data

    Science.gov (United States)

    Madani, Nima; Kimball, John S.; Running, Steven W.

    2017-11-01

    In the light use efficiency (LUE) approach of estimating the gross primary productivity (GPP), plant productivity is linearly related to absorbed photosynthetically active radiation assuming that plants absorb and convert solar energy into biomass within a maximum LUE (LUEmax) rate, which is assumed to vary conservatively within a given biome type. However, it has been shown that photosynthetic efficiency can vary within biomes. In this study, we used 149 global CO2 flux towers to derive the optimum LUE (LUEopt) under prevailing climate conditions for each tower location, stratified according to model training and test sites. Unlike LUEmax, LUEopt varies according to heterogeneous landscape characteristics and species traits. The LUEopt data showed large spatial variability within and between biome types, so that a simple biome classification explained only 29% of LUEopt variability over 95 global tower training sites. The use of explanatory variables in a mixed effect regression model explained 62.2% of the spatial variability in tower LUEopt data. The resulting regression model was used for global extrapolation of the LUEopt data and GPP estimation. The GPP estimated using the new LUEopt map showed significant improvement relative to global tower data, including a 15% R2 increase and 34% root-mean-square error reduction relative to baseline GPP calculations derived from biome-specific LUEmax constants. The new global LUEopt map is expected to improve the performance of LUE-based GPP algorithms for better assessment and monitoring of global terrestrial productivity and carbon dynamics.

  1. An efficient modularized sample-based method to estimate the first-order Sobol' index

    International Nuclear Information System (INIS)

    Li, Chenzhao; Mahadevan, Sankaran

    2016-01-01

    Sobol' index is a prominent methodology in global sensitivity analysis. This paper aims to directly estimate the Sobol' index based only on available input–output samples, even if the underlying model is unavailable. For this purpose, a new method to calculate the first-order Sobol' index is proposed. The innovation is that the conditional variance and mean in the formula of the first-order index are calculated at an unknown but existing location of model inputs, instead of an explicit user-defined location. The proposed method is modularized in two aspects: 1) index calculations for different model inputs are separate and use the same set of samples; and 2) model input sampling, model evaluation, and index calculation are separate. Due to this modularization, the proposed method is capable to compute the first-order index if only input–output samples are available but the underlying model is unavailable, and its computational cost is not proportional to the dimension of the model inputs. In addition, the proposed method can also estimate the first-order index with correlated model inputs. Considering that the first-order index is a desired metric to rank model inputs but current methods can only handle independent model inputs, the proposed method contributes to fill this gap. - Highlights: • An efficient method to estimate the first-order Sobol' index. • Estimate the index from input–output samples directly. • Computational cost is not proportional to the number of model inputs. • Handle both uncorrelated and correlated model inputs.

  2. Relative efficiency of unequal versus equal cluster sizes in cluster randomized trials using generalized estimating equation models.

    Science.gov (United States)

    Liu, Jingxia; Colditz, Graham A

    2018-05-01

    There is growing interest in conducting cluster randomized trials (CRTs). For simplicity in sample size calculation, the cluster sizes are assumed to be identical across all clusters. However, equal cluster sizes are not guaranteed in practice. Therefore, the relative efficiency (RE) of unequal versus equal cluster sizes has been investigated when testing the treatment effect. One of the most important approaches to analyze a set of correlated data is the generalized estimating equation (GEE) proposed by Liang and Zeger, in which the "working correlation structure" is introduced and the association pattern depends on a vector of association parameters denoted by ρ. In this paper, we utilize GEE models to test the treatment effect in a two-group comparison for continuous, binary, or count data in CRTs. The variances of the estimator of the treatment effect are derived for the different types of outcome. RE is defined as the ratio of variance of the estimator of the treatment effect for equal to unequal cluster sizes. We discuss a commonly used structure in CRTs-exchangeable, and derive the simpler formula of RE with continuous, binary, and count outcomes. Finally, REs are investigated for several scenarios of cluster size distributions through simulation studies. We propose an adjusted sample size due to efficiency loss. Additionally, we also propose an optimal sample size estimation based on the GEE models under a fixed budget for known and unknown association parameter (ρ) in the working correlation structure within the cluster. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fast glomerular quantification of whole ex vivo mouse kidneys using Magnetic Resonance Imaging at 9.4 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Chacon-Caldera, Jorge; Kraemer, Philipp; Schad, Lothar R. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Geraci, Stefania; Gretz, Norbert [Heidelberg Univ., Mannheim (Germany). Medical Research Centre; Cullen-McEwen, Luise; Bertram, John F. [Monash Univ., Melbourne, VIC (Australia). Development and Stem Cells Program and Dept. of Anatomy and Developmental Biology

    2016-05-01

    A method to measure total glomerular number (N{sub glom}) in whole mouse kidneys using MRI is presented. The method relies on efficient acquisition times. A 9.4 T preclinical MRI system with a surface cryogenic coil and a 3D gradient echo sequence were used to image nine whole ex vivo BALB/c mouse kidneys labelled with cationized-ferritin (CF). A novel method to segment the glomeruli was developed. The quantification of glomeruli was achieved by identifying and fitting the probability distribution of glomeruli thus reducing variations due to noise. For validation, N{sub glom} of the same kidneys were also obtained using the gold standard: design-based stereology. Excellent agreement was found between the MRI and stereological measurements of N{sub glom}, with values differing by less than 4%: (mean ± SD) MRI = 15 606 ± 1 178; stereology = 16 273 ± 1 523. Using a robust segmentation method and a reliable quantification method, it was possible to acquire N{sub glom} with a scanning time of 33 minutes and 20 seconds. This was more than 8 times faster than previously presented MRI-based methods. Thus, an efficient approach to measure N{sub glom} ex vivo in health and disease is provided.

  4. The Estimation Of The Regions’ Efficiency Of The Russian Federation Including The Intellectual Capital, The Characteristics Of Readiness For Innovation, Level Of Well-Being, And Quality Of Life

    Directory of Open Access Journals (Sweden)

    Valeriy Leonidovich Makarov

    2014-12-01

    Full Text Available On the basis of the authors’ methodology, the models of productive potential of the Russian Federation regions, including estimations of intellectual capital, were constructed. It is shown that characteristics of well-being level and quality of life make a significant impact on the regional production’s efficiency. The characteristics of regions’ readiness to innovate are identified, it is possible to name it as a factor of production’s efficiency. It is shown that the inclusion of different factors of efficiency in the production potential model can significantly increase the differentiation of technical efficiency estimates, besides these estimates and their grades depend on a set of efficiency’s factors. On the basis of a comparison of real GRP and boundary GRP ratings, it is identified locally effective regions with a relatively high estimation of efficiency among regions with similar amounts of GRP and locally ineffective regions. It is calculated marginal effects of influence of the efficiency’s factors on the result of industrial activity in the region. It seems constructively to use these estimates while analyzing the prospects for regions’ development, which is based on the possibility of targeting impact on controllable efficiency’s factors. The article is also offered the option of methodology of the public policy efficiency estimation on the knowledge economy formation — an agent-based model for Russia, which is learning the “knowledge economy” sector and considering their relationship with the rest of the macroeconomic system.

  5. Electroconvulsive Stimulation, but not Chronic Restraint Stress, Causes Structural Alterations in Adult Rat Hippocampus

    DEFF Research Database (Denmark)

    Olesen, Mikkel V.; Wörtwein, Gitta; Pakkenberg, Bente

    2015-01-01

    The neurobiological mechanisms underlying depression are not fully understood. Only a few previous studies have used validated stereological methods to test how stress and animal paradigms of depression affect adult hippocampal neurogenesis and whether antidepressant therapy can counteract possible...... changes in an animal model. Thus, in this study we applied methods that are state of the art in regard to stereological cell counting methods. Using a validated rat model of depression in combination with a clinically relevant schedule of electroconvulsive stimulation, we estimated the total number...... of newly formed neurons in the hippocampal subgranular zone. Also estimated were the total number of neurons and the volume of the granule cell layer in adult rats subjected to chronic restraint stress and electroconvulsive stimulation either alone or in combination. We found that chronic restraint stress...

  6. Efficient Estimation of Extreme Non-linear Roll Motions using the First-order Reliability Method (FORM)

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2007-01-01

    In on-board decision support systems efficient procedures are needed for real-time estimation of the maximum ship responses to be expected within the next few hours, given on-line information on the sea state and user defined ranges of possible headings and speeds. For linear responses standard...... frequency domain methods can be applied. To non-linear responses like the roll motion, standard methods like direct time domain simulations are not feasible due to the required computational time. However, the statistical distribution of non-linear ship responses can be estimated very accurately using...... the first-order reliability method (FORM), well-known from structural reliability problems. To illustrate the proposed procedure, the roll motion is modelled by a simplified non-linear procedure taking into account non-linear hydrodynamic damping, time-varying restoring and wave excitation moments...

  7. Development of electrical efficiency measurement techniques for 10 kW-class SOFC system: Part II. Uncertainty estimation

    International Nuclear Information System (INIS)

    Tanaka, Yohei; Momma, Akihiko; Kato, Ken; Negishi, Akira; Takano, Kiyonami; Nozaki, Ken; Kato, Tohru

    2009-01-01

    Uncertainty of electrical efficiency measurement was investigated for a 10 kW-class SOFC system using town gas. Uncertainty of heating value measured by the gas chromatography method on a mole base was estimated as ±0.12% at 95% level of confidence. Micro-gas chromatography with/without CH 4 quantification may be able to reduce uncertainty of measurement. Calibration and uncertainty estimation methods are proposed for flow-rate measurement of town gas with thermal mass-flow meters or controllers. By adequate calibrations for flowmeters, flow rate of town gas or natural gas at 35 standard litters per minute can be measured within relative uncertainty ±1.0% at 95 % level of confidence. Uncertainty of power measurement can be as low as ±0.14% when a precise wattmeter is used and calibrated properly. It is clarified that electrical efficiency for non-pressurized 10 kW-class SOFC systems can be measured within ±1.0% relative uncertainty at 95% level of confidence with the developed techniques when the SOFC systems are operated relatively stably

  8. Efficient collaborative sparse channel estimation in massive MIMO

    KAUST Repository

    Masood, Mudassir

    2015-08-12

    We propose a method for estimation of sparse frequency selective channels within MIMO-OFDM systems. These channels are independently sparse and share a common support. The method estimates the impulse response for each channel observed by the antennas at the receiver. Estimation is performed in a coordinated manner by sharing minimal information among neighboring antennas to achieve results better than many contemporary methods. Simulations demonstrate the superior performance of the proposed method.

  9. Efficient collaborative sparse channel estimation in massive MIMO

    KAUST Repository

    Masood, Mudassir; Afify, Laila H.; Al-Naffouri, Tareq Y.

    2015-01-01

    We propose a method for estimation of sparse frequency selective channels within MIMO-OFDM systems. These channels are independently sparse and share a common support. The method estimates the impulse response for each channel observed by the antennas at the receiver. Estimation is performed in a coordinated manner by sharing minimal information among neighboring antennas to achieve results better than many contemporary methods. Simulations demonstrate the superior performance of the proposed method.

  10. Econometric estimation of investment utilization, adjustment costs, and technical efficiency in Danish pig farms using hyperbolic distance functions

    DEFF Research Database (Denmark)

    Henningsen, Arne; Fabricius, Ole; Olsen, Jakob Vesterlund

    2014-01-01

    Based on a theoretical microeconomic model, we econometrically estimate investment utilization, adjustment costs, and technical efficiency in Danish pig farms based on a large unbalanced panel dataset. As our theoretical model indicates that adjustment costs are caused both by increased inputs...... of investment activities by the maximum likelihood method so that we can estimate the adjustment costs that occur in the year of the investment and the three following years. Our results show that investments are associated with significant adjustment costs, especially in the year in which the investment...

  11. Towards the Estimation of an Efficient Benchmark Portfolio: The Case of Croatian Emerging Market

    Directory of Open Access Journals (Sweden)

    Dolinar Denis

    2017-04-01

    Full Text Available The fact that cap-weighted indices provide an inefficient risk-return trade-off is well known today. Various research approaches evolved suggesting alternative to cap-weighting in an effort to come up with a more efficient market index benchmark. In this paper we aim to use such an approach and focus on the Croatian capital market. We apply statistical shrinkage method suggested by Ledoit and Wolf (2004 to estimate the covariance matrix and follow the work of Amenc et al. (2011 to obtain estimates of expected returns that rely on risk-return trade-off. Empirical findings for the proposed portfolio optimization include out-of-sample and robustness testing. This way we compare the performance of the capital-weighted benchmark to the alternative and ensure that consistency is achieved in different volatility environments. Research findings do not seem to support relevant research results for the developed markets but rather complement earlier research (Zoričić et al., 2014.

  12. DECIPHERING THE FINEST IMPRINT OF GLACIAL EROSION: OBJECTIVE ANALYSIS OF STRIAE PATTERNS ON BEDROCK

    Directory of Open Access Journals (Sweden)

    Piet Stroeven

    2011-05-01

    Full Text Available The aim of this study is to compare the efficiency of different mathematical and statistical geometrical methods applied to characterise the orientation distribution of striae on bedrock for deciphering the finest imprint of glacial erosion. The involved methods include automatic image analysis techniques of Fast Fourier Transform (FFT, and the experimental investigations by means of Saltikov's directed secants analysis (rose of intersection densities, applied to digital and analogue images of the striae pattern, respectively. In addition, the experimental data were compared with the modelling results made on the basis of Underwood's concept of linear systems in a plane. The experimental and modelling approaches in the framework of stereology yield consistent results. These results reveal that stereological methods allow a reliable and efficient delineation of different families of glacial striae from a complex record imprinted in bedrock.

  13. Effects of hypertension and ovariectomy on rat hepatocytes. Are amlodipine and lacidipine protective? (A stereological and histological study).

    Science.gov (United States)

    Dursun, Hakan; Albayrak, Fatih; Uyanik, Abdullah; Keleş, Nuri Osman; Beyzagül, Polat; Bayram, Ednan; Halici, Zekai; Altunkaynak, Zuhal Berrin; Süleyman, Halis; Okçu, Nihat; Ünal, Bünyamin

    2010-12-01

    Calcium channel blockers are increasingly used for the treatment of hypertension. Menopause and hypertension are both important risk factors for liver damage and several other circulatory abnormalities. The aim of this study was to determine the effects of amlodipine and lacidipine in an ovariectomy-induced postmenopausal period model and a deoxycorticosterone acetate-salt-induced hypertensive model in rats. In this study, animals were divided into six groups as follows: control (Group 1), hypertension (Group 2), ovariectomy (Group 3), ovariectomy and hypertension (Group 4), ovariectomy, hypertension and amlodipine-treated (Group 5), and ovariectomy, hypertension and lacidipine-treated (Group 6). At the end of the experiment, the livers were removed and tissue samples were histologically and stereologically examined. The numerical densities of the hepatocytes according to group were 0.000422, 0.00329, 0.000272, 0.00259, 0.00374 and 0.000346 μm3, respectively. Significant differences were found between values of all groups (phypertension in Groups 5 and 6. Our experimental results show that both hypertension and the postmenopausal period have negative effects on the number of hepatocytes and histological structure of the liver. Both amlodipine and lacidipine appear to ameliorate the hypertension and/or postmenopausal period-related decrease in hepatocyte number. We thus suggest that lacidipine and particularly amlodipine have important protective and recovering effects on the liver.

  14. Investigating time-efficiency of forward masking paradigms for estimating basilar membrane input-output characteristics

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Jepsen, Morten Løve; Dau, Torsten

    2017-01-01

    -output (I/O) function have been proposed. However, such measures are very time consuming. The present study investigated possible modifications of the temporal masking curve (TMC) paradigm to improve time and measurement efficiency. In experiment 1, estimates of knee point (KP) and compression ratio (CR......”, was tested. In contrast to the standard TMC paradigm, the maker level was kept fixed and the “gap threshold” was obtained, such that the masker just masks a low-level (12 dB sensation level) signal. It is argued that this modification allows for better control of the tested stimulus level range, which...

  15. Estimation of the number of angiotensin II AT1 receptors in rat kidney afferent and efferent arterioles

    DEFF Research Database (Denmark)

    Razga, Zsolt; Nyengaard, Jens Randel

    2007-01-01

    of angiotensin II AT1 receptors along the length of the arterioles and per arteriole, we combined immunoelectron microscopy with stereology. RESULTS: The number of AT1 receptor molecules was significantly lower in the renin-positive smooth muscle cells (SMCs) than in the renin-negative SMCs of the afferent...

  16. Metamodel for Efficient Estimation of Capacity-Fade Uncertainty in Li-Ion Batteries for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Jaewook Lee

    2015-06-01

    Full Text Available This paper presents an efficient method for estimating capacity-fade uncertainty in lithium-ion batteries (LIBs in order to integrate them into the battery-management system (BMS of electric vehicles, which requires simple and inexpensive computation for successful application. The study uses the pseudo-two-dimensional (P2D electrochemical model, which simulates the battery state by solving a system of coupled nonlinear partial differential equations (PDEs. The model parameters that are responsible for electrode degradation are identified and estimated, based on battery data obtained from the charge cycles. The Bayesian approach, with parameters estimated by probability distributions, is employed to account for uncertainties arising in the model and battery data. The Markov Chain Monte Carlo (MCMC technique is used to draw samples from the distributions. The complex computations that solve a PDE system for each sample are avoided by employing a polynomial-based metamodel. As a result, the computational cost is reduced from 5.5 h to a few seconds, enabling the integration of the method into the vehicle BMS. Using this approach, the conservative bound of capacity fade can be determined for the vehicle in service, which represents the safety margin reflecting the uncertainty.

  17. A simple and efficient algorithm to estimate daily global solar radiation from geostationary satellite data

    International Nuclear Information System (INIS)

    Lu, Ning; Qin, Jun; Yang, Kun; Sun, Jiulin

    2011-01-01

    Surface global solar radiation (GSR) is the primary renewable energy in nature. Geostationary satellite data are used to map GSR in many inversion algorithms in which ground GSR measurements merely serve to validate the satellite retrievals. In this study, a simple algorithm with artificial neural network (ANN) modeling is proposed to explore the non-linear physical relationship between ground daily GSR measurements and Multi-functional Transport Satellite (MTSAT) all-channel observations in an effort to fully exploit information contained in both data sets. Singular value decomposition is implemented to extract the principal signals from satellite data and a novel method is applied to enhance ANN performance at high altitude. A three-layer feed-forward ANN model is trained with one year of daily GSR measurements at ten ground sites. This trained ANN is then used to map continuous daily GSR for two years, and its performance is validated at all 83 ground sites in China. The evaluation result demonstrates that this algorithm can quickly and efficiently build the ANN model that estimates daily GSR from geostationary satellite data with good accuracy in both space and time. -- Highlights: → A simple and efficient algorithm to estimate GSR from geostationary satellite data. → ANN model fully exploits both the information from satellite and ground measurements. → Good performance of the ANN model is comparable to that of the classical models. → Surface elevation and infrared information enhance GSR inversion.

  18. Efficiency and abatement costs of energy-related CO2 emissions in China: A slacks-based efficiency measure

    International Nuclear Information System (INIS)

    Choi, Yongrok; Zhang, Ning; Zhou, P.

    2012-01-01

    Highlights: ► We employ a slacks-based DEA model to estimate the energy efficiency and shadow prices of CO 2 emissions in China. ► The empirical study shows that China was not performing CO 2 -efficiently. ► The average of estimated shadow prices of CO 2 emissions is about $7.2. -- Abstract: This paper uses nonparametric efficiency analysis technique to estimate the energy efficiency, potential emission reductions and marginal abatement costs of energy-related CO 2 emissions in China. We employ a non-radial slacks-based data envelopment analysis (DEA) model for estimating the potential reductions and efficiency of CO 2 emissions for China. The dual model of the slacks-based DEA model is then used to estimate the marginal abatement costs of CO 2 emissions. An empirical study based on China’s panel data (2001–2010) is carried out and some policy implications are also discussed.

  19. An estimate of the second law thermodynamic efficiency of the various units comprising an Environmental Control and Life Support System (ECLSS)

    Science.gov (United States)

    Chatterjee, Sharmista; Seagrave, Richard C.

    1993-01-01

    The objective of this paper is to present an estimate of the second law thermodynamic efficiency of the various units comprising an Environmental Control and Life Support System (ECLSS). The technique adopted here is based on an evaluation of the 'lost work' within each functional unit of the subsystem. Pertinent information for our analysis is obtained from a user interactive integrated model of an ECLSS. The model was developed using ASPEN. A potential benefit of this analysis is the identification of subsystems with high entropy generation as the most likely candidates for engineering improvements. This work has been motivated by the fact that the design objective for a long term mission should be the evaluation of existing ECLSS technologies not only the basis of the quantity of work needed for or obtained from each subsystem but also on the quality of work. In a previous study Brandhorst showed that the power consumption for partially closed and completely closed regenerable life support systems was estimated as 3.5 kw/individual and 10-12 kw/individual respectively. With the increasing cost and scarcity of energy resources, our attention is drawn to evaluate the existing ECLSS technologies on the basis of their energy efficiency. In general the first law efficiency of a system is usually greater than 50 percent. From literature, the second law efficiency is usually about 10 percent. The estimation of second law efficiency of the system indicates the percentage of energy degraded as irreversibilities within the process. This estimate offers more room for improvement in the design of equipment. From another perspective, our objective is to keep the total entropy production of a life support system as low as possible and still ensure a positive entropy gradient between the system and the surroundings. The reason for doing so is as the entropy production of the system increases, the entropy gradient between the system and the surroundings decreases, and the

  20. Estimation of the potential efficiency of a multijunction solar cell at a limit balance of photogenerated currents

    Energy Technology Data Exchange (ETDEWEB)

    Mintairov, M. A., E-mail: mamint@mail.ioffe.ru; Evstropov, V. V.; Mintairov, S. A.; Shvarts, M. Z.; Timoshina, N. Kh.; Kalyuzhnyy, N. A. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2015-05-15

    A method is proposed for estimating the potential efficiency which can be achieved in an initially unbalanced multijunction solar cell by the mutual convergence of photogenerated currents: to extract this current from a relatively narrow band-gap cell and to add it to a relatively wide-gap cell. It is already known that the properties facilitating relative convergence are inherent to such objects as bound excitons, quantum dots, donor-acceptor pairs, and others located in relatively wide-gap cells. In fact, the proposed method is reduced to the problem of obtaining such a required light current-voltage (I–V) characteristic which corresponds to the equality of all photogenerated short-circuit currents. Two methods for obtaining the required light I–V characteristic are used. The first one is selection of the spectral composition of the radiation incident on the multijunction solar cell from an illuminator. The second method is a double shift of the dark I–V characteristic: a current shift J{sub g} (common set photogenerated current) and a voltage shift (−J{sub g}R{sub s}), where R{sub s} is the series resistance. For the light and dark I–V characteristics, a general analytical expression is derived, which considers the effect of so-called luminescence coupling in multijunction solar cells. The experimental I–V characteristics are compared with the calculated ones for a three-junction InGaP/GaAs/Ge solar cell with R{sub s} = 0.019 Ω cm{sup 2} and a maximum factual efficiency of 36.9%. Its maximum potential efficiency is estimated as 41.2%.

  1. ON THE VOLUME FROM PLANAR SECTIONS THROUGH A CURVE

    Directory of Open Access Journals (Sweden)

    Ximo Gual-Arnau

    2011-05-01

    Full Text Available We derive a formula to obtain the volume of a compact domain from planar sections through a curve. From this formula we propose a stereological estimator for the volume which generalizes some known unbiased estimators which use a systematic sampling scheme. Moreover we formulate a Cavalieri's principle for compact domains is spaces of constant curvature λ.

  2. Stereological Study on the Positive Effect of Running Exercise on the Capillaries in the Hippocampus in a Depression Model

    Directory of Open Access Journals (Sweden)

    Linmu Chen

    2017-11-01

    Full Text Available Running exercise is an effective method to improve depressive symptoms when combined with drugs. However, the underlying mechanisms are not fully clear. Cerebral blood flow perfusion in depressed patients is significantly lower in the hippocampus. Physical activity can achieve cerebrovascular benefits. The purpose of this study was to evaluate the impacts of running exercise on capillaries in the hippocampal CA1 and dentate gyrus (DG regions. The chronic unpredictable stress (CUS depression model was used in this study. CUS rats were given 4 weeks of running exercise from the fifth week to the eighth week (20 min every day from Monday to Friday each week. The sucrose consumption test was used to measure anhedonia. Furthermore, stereological methods were used to investigate the capillary changes among the control group, CUS/Standard group and CUS/Running group. Sucrose consumption significantly increased in the CUS/Running group. Running exercise has positive effects on the capillaries parameters in the hippocampal CA1 and DG regions, such as the total volume, total length and total surface area. These results demonstrated that capillaries are protected by running exercise in the hippocampal CA1 and DG might be one of the structural bases for the exercise-induced treatment of depression-like behavior. These results suggest that drugs and behavior influence capillaries and may be considered as a new means for depression treatment in the future.

  3. The rat orbital and agranular insular prefrontal cortical areas: a cytoarchitectonic and chemoarchitectonic study

    NARCIS (Netherlands)

    van de Werd, H.J.J.M.; Uylings, H.B.M.

    2008-01-01

    Cytoarchitectonic characterization of borders is necessary for stereological studies (e.g., total cell number estimation), in which particular cortical areas have to be defined. In this study, cytoarchitectonic characteristics are described and illustrated for the rat ventral or orbital frontal

  4. Estimating statistical uncertainty of Monte Carlo efficiency-gain in the context of a correlated sampling Monte Carlo code for brachytherapy treatment planning with non-normal dose distribution.

    Science.gov (United States)

    Mukhopadhyay, Nitai D; Sampson, Andrew J; Deniz, Daniel; Alm Carlsson, Gudrun; Williamson, Jeffrey; Malusek, Alexandr

    2012-01-01

    Correlated sampling Monte Carlo methods can shorten computing times in brachytherapy treatment planning. Monte Carlo efficiency is typically estimated via efficiency gain, defined as the reduction in computing time by correlated sampling relative to conventional Monte Carlo methods when equal statistical uncertainties have been achieved. The determination of the efficiency gain uncertainty arising from random effects, however, is not a straightforward task specially when the error distribution is non-normal. The purpose of this study is to evaluate the applicability of the F distribution and standardized uncertainty propagation methods (widely used in metrology to estimate uncertainty of physical measurements) for predicting confidence intervals about efficiency gain estimates derived from single Monte Carlo runs using fixed-collision correlated sampling in a simplified brachytherapy geometry. A bootstrap based algorithm was used to simulate the probability distribution of the efficiency gain estimates and the shortest 95% confidence interval was estimated from this distribution. It was found that the corresponding relative uncertainty was as large as 37% for this particular problem. The uncertainty propagation framework predicted confidence intervals reasonably well; however its main disadvantage was that uncertainties of input quantities had to be calculated in a separate run via a Monte Carlo method. The F distribution noticeably underestimated the confidence interval. These discrepancies were influenced by several photons with large statistical weights which made extremely large contributions to the scored absorbed dose difference. The mechanism of acquiring high statistical weights in the fixed-collision correlated sampling method was explained and a mitigation strategy was proposed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Estimating and understanding the efficiency of nanoparticles in enhancing the conductivity of carbon nanotube/polymer composites

    KAUST Repository

    Mora Cordova, Angel

    2018-05-22

    Carbon nanotubes (CNTs) have been widely used to improve the electrical conductivity of polymers. However, not all CNTs actively participate in the conduction of electricity since they have to be close to each other to form a conductive network. The amount of active CNTs is rarely discussed as it is not captured by percolation theory. However, this amount is a very important information that could be used in a definition of loading efficiency for CNTs (and, in general, for any nanofiller). Thus, we develop a computational tool to quantify the amount of CNTs that actively participates in the conductive network. We then use this quantity to propose a definition of loading efficiency. We compare our results with an expression presented in the literature for the fraction of percolated CNTs (although not presented as a definition of efficiency). We found that this expression underestimates the fraction of percolated CNTs. We thus propose an improved estimation. We also study how efficiency changes with CNT loading and the CNT aspect ratio. We use this concept to study the size of the representative volume element (RVE) for polymers loaded with CNTs, which has received little attention in the past. Here, we find the size of RVE based on both loading efficiency and electrical conductivity such that the scales of “morphological” and “functional” RVEs can be compared. Additionally, we study the relations between particle and network properties (such as efficiency, CNT conductivity and junction resistance) and the conductivity of CNT/polymer composites. We present a series of recommendations to improve the conductivity of a composite based on our simulation results.

  6. Estimating and understanding the efficiency of nanoparticles in enhancing the conductivity of carbon nanotube/polymer composites

    KAUST Repository

    Mora Cordova, Angel; Han, Fei; Lubineau, Gilles

    2018-01-01

    Carbon nanotubes (CNTs) have been widely used to improve the electrical conductivity of polymers. However, not all CNTs actively participate in the conduction of electricity since they have to be close to each other to form a conductive network. The amount of active CNTs is rarely discussed as it is not captured by percolation theory. However, this amount is a very important information that could be used in a definition of loading efficiency for CNTs (and, in general, for any nanofiller). Thus, we develop a computational tool to quantify the amount of CNTs that actively participates in the conductive network. We then use this quantity to propose a definition of loading efficiency. We compare our results with an expression presented in the literature for the fraction of percolated CNTs (although not presented as a definition of efficiency). We found that this expression underestimates the fraction of percolated CNTs. We thus propose an improved estimation. We also study how efficiency changes with CNT loading and the CNT aspect ratio. We use this concept to study the size of the representative volume element (RVE) for polymers loaded with CNTs, which has received little attention in the past. Here, we find the size of RVE based on both loading efficiency and electrical conductivity such that the scales of “morphological” and “functional” RVEs can be compared. Additionally, we study the relations between particle and network properties (such as efficiency, CNT conductivity and junction resistance) and the conductivity of CNT/polymer composites. We present a series of recommendations to improve the conductivity of a composite based on our simulation results.

  7. Drainage estimation to aquifer and water use irrigation efficiency in semi-arid zone for a long period of time

    Science.gov (United States)

    Jiménez-Martínez, J.; Molinero-Huguet, J.; Candela, L.

    2009-04-01

    Water requirements for different crop types according to soil type and climate conditions play not only an important role in agricultural efficiency production, though also for water resources management and control of pollutants in drainage water. The key issue to attain these objectives is the irrigation efficiency. Application of computer codes for irrigation simulation constitutes a fast and inexpensive approach to study optimal agricultural management practices. To simulate daily water balance in the soil, vadose zone and aquifer the VisualBALAN V. 2.0 code was applied to an experimental area under irrigation characterized by its aridity. The test was carried out in three experimental plots for annual row crops (lettuce and melon), perennial vegetables (artichoke), and fruit trees (citrus) under common agricultural practices in open air for October 1999-September 2008. Drip irrigation was applied to crops production due to the scarcity of water resources and the need for water conservation. Water level change was monitored in the top unconfined aquifer for each experimental plot. Results of water balance modelling show a good agreement between observed and estimated water level values. For the study period, mean drainage obtained values were 343 mm, 261 mm and 205 mm for lettuce and melon, artichoke and citrus respectively. Assessment of water use efficiency was based on the IE indicator proposed by the ASCE Task Committee. For the modelled period, water use efficiency was estimated as 73, 71 and 78 % of the applied dose (irrigation + precipitation) for lettuce and melon, artichoke and citrus, respectively.

  8. An estimation of the energy and exergy efficiencies for the energy resources consumption in the transportation sector in Malaysia

    International Nuclear Information System (INIS)

    Saidur, R.; Sattar, M.A.; Masjuki, H.H.; Ahmed, S.; Hashim, U.

    2007-01-01

    The purpose of this work is to apply the useful energy and exergy analysis models for different modes of transport in Malaysia and to compare the result with a few countries. In this paper, energy and exergy efficiencies of the various sub-sectors are presented by considering the energy and exergy flows from 1995 to 2003. Respective flow diagrams to find the overall energy and exergy efficiencies of Malaysian transportation sector are also presented. The estimated overall energy efficiency ranges from 22.74% (1999) to 22.98% (1998) with a mean of 22.82+/-0.06% and that of overall exergy efficiency ranges from 22.44% (2000) to 22.82% (1998) with a mean of 22.55+/-0.12%. The results are compared with respect to present energy and exergy efficiencies in each sub-sector. The transportation sector used about 40% of the total energy consumed in 2002. Therefore, it is important to identify the energy and exergy flows and the pertinent losses. The road sub-sector has appeared to be the most efficient one compared to the air and marine sub-sectors. Also found that the energy and exergy efficiencies of Malaysian transportation sector are lower than that of Turkey but higher than Norway

  9. Neuronal precursor cell proliferation in the hippocampus after transient cerebral ischemia: a comparative study of two rat strains using stereological tools.

    Science.gov (United States)

    Kelsen, Jesper; Larsen, Marianne H; Sørensen, Jens Christian; Møller, Arne; Frøkiaer, Jørgen; Nielsen, Søren; Nyengaard, Jens R; Mikkelsen, Jens D; Rønn, Lars Christian B

    2010-04-06

    We are currently investigating microglial activation and neuronal precursor cell (NPC) proliferation after transient middle cerebral artery occlusion (tMCAo) in rats. This study aimed: (1) to investigate differences in hippocampal NPC proliferation in outbred male spontaneously hypertensive rats (SHRs) and Sprague-Dawley rats (SDs) one week after tMCAo; (2) to present the practical use of the optical fractionator and 2D nucleator in stereological brain tissue analyses; and (3) to report our experiences with an intraluminal tMCAo model where the occluding filament is advanced 22 mm beyond the carotid bifurcation and the common carotid artery is clamped during tMCAo. Twenty-three SDs and twenty SHRs were randomized into four groups subjected to 90 minutes tMCAo or sham. BrdU (50 mg/kg) was administered intraperitoneally twice daily on Day 4 to 7 after surgery. On Day 8 all animals were euthanized. NeuN-stained tissue sections were used for brain and infarct volume estimation with the 2D nucleator and Cavalieri principle. Brains were studied for the presence of activated microglia (ED-1) and hippocampal BrdU incorporation using the optical fractionator. We found no significant difference or increase in post-ischemic NPC proliferation between the two strains. However, the response to remote ischemia may differ between SDs and SHRs. In three animals increased post-stroke NPC proliferation was associated with hippocampal ischemic injury. The mean infarct volume was 89.2 +/- 76.1 mm3 in SHRs and 16.9 +/- 22.7 mm3 in SDs (p < 0.005). Eight out of eleven SHRs had ischemic neocortical damage in contrast to only one out of 12 SDs. We observed involvement of the anterior choroidal and hypothalamic arteries in several animals from both strains and the anterior cerebral artery in two SHRs. We found no evidence of an early hippocampal NPC proliferation one week after tMCAo in both strains. Infarction within the anterior choroidal artery could induce hippocampal ischemia and

  10. Estimation of gas turbine blades cooling efficiency

    NARCIS (Netherlands)

    Moskalenko, A.B.; Kozhevnikov, A.

    2016-01-01

    This paper outlines the results of the evaluation of the most thermally stressed gas turbine elements, first stage power turbine blades, cooling efficiency. The calculations were implemented using a numerical simulation based on the Finite Element Method. The volume average temperature of the blade

  11. Particle sizes from sectional data

    DEFF Research Database (Denmark)

    Pawlas, Zbynek; Nyengaard, Jens Randel; Jensen, Eva Bjørn Vedel

    2009-01-01

    We propose a new statistical method for obtaining information about particle size distributions from sectional data without specific assumptions about particle shape. The method utilizes recent advances in local stereology. We show how to estimate separately from sectional data the variance due t...

  12. The Use of 32P and 15N to Estimate Fertilizer Efficiency in Oil Palm

    International Nuclear Information System (INIS)

    Sisworo, Elsje L; Sisworo, Widjang H; Havid-Rasjid; Haryanto; Syamsul-Rizal; Poeloengan, Z; Kusnu-Martoyo

    2004-01-01

    Oil palm has become an important commodity for Indonesia reaching an area of 2.6 million ha at the end of 1998. It is mostly cultivated in highly weathered acid soil usually Ultisols and Oxisols which are known for their low fertility, concerning the major nutrients like N and P. This study most conducted to search for the most active root-zone of oil palm and applied urea fertilizer at such soils to obtain high N-efficiency. Carrier free KH 2 32 PO 4 solution was used to determine the active root-zone of oil palm by applying 32 P around the plant in twenty holes. After the most active root-zone have been determined, urea in one, two and three splits were respectively applied at this zone. To estimate N-fertilizer efficiency of urea labelled 15 N Ammonium Sulphate was used by adding them at the same amount of 16 g 15 N plan -1 . This study showed that the most active root-zone was found at a 1.5 m distance from the plant-stem and at 5 cm soil depth. For urea the highest N-efficiency was obtained from applying it at two splits. The use of 32 P was able to distinguish several root zones: 1.5 m - 2.5 m from the plant-stem at a 5 cm and 15 cm soil depth. Urea placed at the most active root-zone, which was at a 1.5 m distance from the plant-stem and at a 5 cm depth in one, two, and three splits respectively showed difference N-efficiency. The highest N-efficiency of urea was obtained when applying it in two splits at the most active root-zone. (author)

  13. ERROR BOUNDS FOR SURFACE AREA ESTIMATORS BASED ON CROFTON’S FORMULA

    Directory of Open Access Journals (Sweden)

    Markus Kiderlen

    2011-05-01

    Full Text Available According to Crofton's formula, the surface area S(A of a sufficiently regular compact set A in Rd is proportional to the mean of all total projections pA (u on a linear hyperplane with normal u, uniformly averaged over all unit vectors u. In applications, pA (u is only measured in k directions and the mean is approximated by a finite weighted sum bS(A of the total projections in these directions. The choice of the weights depends on the selected quadrature rule. We define an associated zonotope Z (depending only on the projection directions and the quadrature rule, and show that the relative error bS (A/S (A is bounded from below by the inradius of Z and from above by the circumradius of Z. Applying a strengthened isoperimetric inequality due to Bonnesen, we show that the rectangular quadrature rule does not give the best possible error bounds for d =2. In addition, we derive asymptotic behavior of the error (with increasing k in the planar case. The paper concludes with applications to surface area estimation in design-based digital stereology where we show that the weights due to Bonnesen's inequality are better than the usual weights based on the rectangular rule and almost optimal in the sense that the relative error of the surface area estimator is very close to the minimal error.

  14. Spectral and Energy Efficient Low-Overhead Uplink and Downlink Channel Estimation for 5G Massive MIMO Systems

    Directory of Open Access Journals (Sweden)

    Imran Khan

    2018-01-01

    Full Text Available Uplink and Downlink channel estimation in massive Multiple Input Multiple Output (MIMO systems is an intricate issue because of the increasing channel matrix dimensions. The channel feedback overhead using traditional codebook schemes is very large, which consumes more bandwidth and decreases the overall system efficiency. The purpose of this paper is to decrease the channel estimation overhead by taking the advantage of sparse attributes and also to optimize the Energy Efficiency (EE of the system. To cope with this issue, we propose a novel approach by using Compressed-Sensing (CS, Block Iterative-Support-Detection (Block-ISD, Angle-of-Departure (AoD and Structured Compressive Sampling Matching Pursuit (S-CoSaMP algorithms to reduce the channel estimation overhead and compare them with the traditional algorithms. The CS uses temporal-correlation of time-varying channels to produce Differential-Channel Impulse Response (DCIR among two CIRs that are adjacent in time-slots. DCIR has greater sparsity than the conventional CIRs as it can be easily compressed. The Block-ISD uses spatial-correlation of the channels to obtain the block-sparsity which results in lower pilot-overhead. AoD quantizes the channels whose path-AoDs variation is slower than path-gains and such information is utilized for reducing the overhead. S-CoSaMP deploys structured-sparsity to obtain reliable Channel-State-Information (CSI. MATLAB simulation results show that the proposed CS based algorithms reduce the feedback and pilot-overhead by a significant percentage and also improve the system capacity as compared with the traditional algorithms. Moreover, the EE level increases with increasing Base Station (BS density, UE density and lowering hardware impairments level.

  15. Estimate of Cost-Effective Potential for Minimum Efficiency Performance Standards in 13 Major World Economies Energy Savings, Environmental and Financial Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Letschert, Virginie E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bojda, Nicholas [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ke, Jing [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); McNeil, Michael A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-07-01

    This study analyzes the financial impacts on consumers of minimum efficiency performance standards (MEPS) for appliances that could be implemented in 13 major economies around the world. We use the Bottom-Up Energy Analysis System (BUENAS), developed at Lawrence Berkeley National Laboratory (LBNL), to analyze various appliance efficiency target levels to estimate the net present value (NPV) of policies designed to provide maximum energy savings while not penalizing consumers financially. These policies constitute what we call the “cost-effective potential” (CEP) scenario. The CEP scenario is designed to answer the question: How high can we raise the efficiency bar in mandatory programs while still saving consumers money?

  16. Gaussian Quadrature is an efficient method for the back-transformation in estimating the usual intake distribution when assessing dietary exposure.

    Science.gov (United States)

    Dekkers, A L M; Slob, W

    2012-10-01

    In dietary exposure assessment, statistical methods exist for estimating the usual intake distribution from daily intake data. These methods transform the dietary intake data to normal observations, eliminate the within-person variance, and then back-transform the data to the original scale. We propose Gaussian Quadrature (GQ), a numerical integration method, as an efficient way of back-transformation. We compare GQ with six published methods. One method uses a log-transformation, while the other methods, including GQ, use a Box-Cox transformation. This study shows that, for various parameter choices, the methods with a Box-Cox transformation estimate the theoretical usual intake distributions quite well, although one method, a Taylor approximation, is less accurate. Two applications--on folate intake and fruit consumption--confirmed these results. In one extreme case, some methods, including GQ, could not be applied for low percentiles. We solved this problem by modifying GQ. One method is based on the assumption that the daily intakes are log-normally distributed. Even if this condition is not fulfilled, the log-transformation performs well as long as the within-individual variance is small compared to the mean. We conclude that the modified GQ is an efficient, fast and accurate method for estimating the usual intake distribution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Estimating causal effects with a non-paranormal method for the design of efficient intervention experiments.

    Science.gov (United States)

    Teramoto, Reiji; Saito, Chiaki; Funahashi, Shin-ichi

    2014-06-30

    Knockdown or overexpression of genes is widely used to identify genes that play important roles in many aspects of cellular functions and phenotypes. Because next-generation sequencing generates high-throughput data that allow us to detect genes, it is important to identify genes that drive functional and phenotypic changes of cells. However, conventional methods rely heavily on the assumption of normality and they often give incorrect results when the assumption is not true. To relax the Gaussian assumption in causal inference, we introduce the non-paranormal method to test conditional independence in the PC-algorithm. Then, we present the non-paranormal intervention-calculus when the directed acyclic graph (DAG) is absent (NPN-IDA), which incorporates the cumulative nature of effects through a cascaded pathway via causal inference for ranking causal genes against a phenotype with the non-paranormal method for estimating DAGs. We demonstrate that causal inference with the non-paranormal method significantly improves the performance in estimating DAGs on synthetic data in comparison with the original PC-algorithm. Moreover, we show that NPN-IDA outperforms the conventional methods in exploring regulators of the flowering time in Arabidopsis thaliana and regulators that control the browning of white adipocytes in mice. Our results show that performance improvement in estimating DAGs contributes to an accurate estimation of causal effects. Although the simplest alternative procedure was used, our proposed method enables us to design efficient intervention experiments and can be applied to a wide range of research purposes, including drug discovery, because of its generality.

  18. Degeneration and regeneration of motor and sensory nerves: a stereological study of crush lesions in rat facial and mental nerves.

    Science.gov (United States)

    Barghash, Z; Larsen, J O; Al-Bishri, A; Kahnberg, K-E

    2013-12-01

    The aim of this study was to evaluate the degeneration and regeneration of a sensory nerve and a motor nerve at the histological level after a crush injury. Twenty-five female Wistar rats had their mental nerve and the buccal branch of their facial nerve compressed unilaterally against a glass rod for 30s. Specimens of the compressed nerves and the corresponding control nerves were dissected at 3, 7, and 19 days after surgery. Nerve cross-sections were stained with osmium tetroxide and toluidine blue and analysed using two-dimensional stereology. We found differences between the two nerves both in the normal anatomy and in the regenerative pattern. The mental nerve had a larger cross-sectional area including all tissue components. The mental nerve had a larger volume fraction of myelinated axons and a correspondingly smaller volume fraction of endoneurium. No differences were observed in the degenerative pattern; however, at day 19 the buccal branch had regenerated to the normal number of axons, whereas the mental nerve had only regained 50% of the normal number of axons. We conclude that the regenerative process is faster and/or more complete in the facial nerve (motor function) than it is in the mental nerve (somatosensory function). Copyright © 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  19. Non-invasive estimation of myocardial efficiency using positron emission tomography and carbon-11 acetate - comparison between the normal and failing human heart

    International Nuclear Information System (INIS)

    Bengel, F.M.; Nekolla, S.; Schwaiger, M.; Ungerer, M.

    2000-01-01

    We studied ten patients with idiopathic dilated cardiomyopathy (DCM) and 11 healthy normals by dynamic PET with 11 C-acetate and either tomographic radionuclide ventriculography or cine magnetic resonance imaging. A ''stroke work index'' (SWI) was calculated by: SWI = systolic blood pressure x stroke volume/body surface area. To estimate myocardial efficiency, a ''work-metabolic index'' (WMI) was then obtained as follows: WMI = SWI x heart rate/k(mono), where k(mono) is the washout constant for 11 C-acetate derived from mono-exponential fitting. In DCM patients, left ventricular ejection fraction was 19%±10% and end-diastolic volume was 92±28 ml/m 2 (vs 64%±7% and 55±8 ml/m 2 in normals, P 2 ; P 6 mmHg x ml/m 2 ; P<0.001) were lower in DCM patients, too. Overall, the WMI correlated positively with ejection parameters (r=0.73, P<0.001 for ejection fraction; r=0.93, P<0.001 for stroke volume), and inversely with systemic vascular resistance (r=-0.77; P<0.001). There was a weak positive correlation between WMI and end-diastolic volume in normals (r=0.45; P=0.17), while in DCM patients, a non-significant negative correlation coefficient (r=-0.21; P=0.57) was obtained. In conclusion non-invasive estimates of oxygen consumption and efficiency in the failing heart were reduced compared with those in normals. Estimates of efficiency increased with increasing contractile performance, and decreased with increasing ventricular afterload. In contrast to normals, the failing heart was not able to respond with an increase in efficiency to increasing ventricular volume.(orig./MG) (orig.)

  20. Proliferation of germ cells and somatic cells in first trimester human embryonic gonads as indicated by S and S+G2+M phase fractions

    DEFF Research Database (Denmark)

    Sørensen, Kristina Pilekær; Lutterodt, Melissa Catherine R; Mamsen, Linn S

    2011-01-01

    The number of germ cells and somatic cells in human embryonic and foetal gonads has previously been estimated by stereological methods, which are time- and labour-consuming with little information concerning cell proliferation. Here, we studied whether flow cytometry could be applied as an easier...

  1. Total regional and global number of synapses in the human brain neocortex

    NARCIS (Netherlands)

    Tang, Y.; Nyengaard, J.R.; Groot, D.M.G. de; Jorgen, H.; Gundersen, G.

    2001-01-01

    An estimator of the total number of synapses in neocortex of human autopsy brains based on unbiased stereological principles is described. Each randomly chosen cerebral hemisphere was stratified into the four major neocortical regions. Uniform sampling with a varying sampling fraction in each region

  2. Influence of Plot Size on Efficiency of Biomass Estimates in Inventories of Dry Tropical Forests Assisted by Photogrammetric Data from an Unmanned Aircraft System

    Directory of Open Access Journals (Sweden)

    Daud Jones Kachamba

    2017-06-01

    Full Text Available Applications of unmanned aircraft systems (UASs to assist in forest inventories have provided promising results in biomass estimation for different forest types. Recent studies demonstrating use of different types of remotely sensed data to assist in biomass estimation have shown that accuracy and precision of estimates are influenced by the size of field sample plots used to obtain reference values for biomass. The objective of this case study was to assess the influence of sample plot size on efficiency of UAS-assisted biomass estimates in the dry tropical miombo woodlands of Malawi. The results of a design-based field sample inventory assisted by three-dimensional point clouds obtained from aerial imagery acquired with a UAS showed that the root mean square errors as well as the standard error estimates of mean biomass decreased as sample plot sizes increased. Furthermore, relative efficiency values over different sample plot sizes were above 1.0 in a design-based and model-assisted inferential framework, indicating that UAS-assisted inventories were more efficient than purely field-based inventories. The results on relative costs for UAS-assisted and pure field-based sample plot inventories revealed that there is a trade-off between inventory costs and required precision. For example, in our study if a standard error of less than approximately 3 Mg ha−1 was targeted, then a UAS-assisted forest inventory should be applied to ensure more cost effective and precise estimates. Future studies should therefore focus on finding optimum plot sizes for particular applications, like for example in projects under the Reducing Emissions from Deforestation and Forest Degradation, plus forest conservation, sustainable management of forest and enhancement of carbon stocks (REDD+ mechanism with different geographical scales.

  3. Efficient and robust pupil size and blink estimation from near-field video sequences for human-machine interaction.

    Science.gov (United States)

    Chen, Siyuan; Epps, Julien

    2014-12-01

    Monitoring pupil and blink dynamics has applications in cognitive load measurement during human-machine interaction. However, accurate, efficient, and robust pupil size and blink estimation pose significant challenges to the efficacy of real-time applications due to the variability of eye images, hence to date, require manual intervention for fine tuning of parameters. In this paper, a novel self-tuning threshold method, which is applicable to any infrared-illuminated eye images without a tuning parameter, is proposed for segmenting the pupil from the background images recorded by a low cost webcam placed near the eye. A convex hull and a dual-ellipse fitting method are also proposed to select pupil boundary points and to detect the eyelid occlusion state. Experimental results on a realistic video dataset show that the measurement accuracy using the proposed methods is higher than that of widely used manually tuned parameter methods or fixed parameter methods. Importantly, it demonstrates convenience and robustness for an accurate and fast estimate of eye activity in the presence of variations due to different users, task types, load, and environments. Cognitive load measurement in human-machine interaction can benefit from this computationally efficient implementation without requiring a threshold calibration beforehand. Thus, one can envisage a mini IR camera embedded in a lightweight glasses frame, like Google Glass, for convenient applications of real-time adaptive aiding and task management in the future.

  4. On efficiency of some ratio estimators in double sampling design ...

    African Journals Online (AJOL)

    In this paper, three sampling ratio estimators in double sampling design were proposed with the intention of finding an alternative double sampling design estimator to the conventional ratio estimator in double sampling design discussed by Cochran (1997), Okafor (2002) , Raj (1972) and Raj and Chandhok (1999).

  5. Energy efficiency in Swedish industry

    International Nuclear Information System (INIS)

    Zhang, Shanshan; Lundgren, Tommy; Zhou, Wenchao

    2016-01-01

    This paper assesses energy efficiency in Swedish industry. Using unique firm-level panel data covering the years 2001–2008, the efficiency estimates are obtained for firms in 14 industrial sectors by using data envelopment analysis (DEA). The analysis accounts for multi-output technologies where undesirable outputs are produced alongside with the desirable output. The results show that there was potential to improve energy efficiency in all the sectors and relatively large energy inefficiencies existed in small energy-use industries in the sample period. Also, we assess how the EU ETS, the carbon dioxide (CO_2) tax and the energy tax affect energy efficiency by conducting a second-stage regression analysis. To obtain consistent estimates for the regression model, we apply a modified, input-oriented version of the double bootstrap procedure of Simar and Wilson (2007). The results of the regression analysis reveal that the EU ETS and the CO_2 tax did not have significant influences on energy efficiency in the sample period. However, the energy tax had a positive relation with the energy efficiency. - Highlights: • We use DEA to estimate firm-level energy efficiency in Swedish industry. • We examine impacts of climate and energy policies on energy efficiency. • The analyzed policies are Swedish carbon and energy taxes and the EU ETS. • Carbon tax and EU ETS did not have significant influences on energy efficiency. • The energy tax had a positive relation with energy efficiency.

  6. An Efficient and Reliable Statistical Method for Estimating Functional Connectivity in Large Scale Brain Networks Using Partial Correlation.

    Science.gov (United States)

    Wang, Yikai; Kang, Jian; Kemmer, Phebe B; Guo, Ying

    2016-01-01

    Currently, network-oriented analysis of fMRI data has become an important tool for understanding brain organization and brain networks. Among the range of network modeling methods, partial correlation has shown great promises in accurately detecting true brain network connections. However, the application of partial correlation in investigating brain connectivity, especially in large-scale brain networks, has been limited so far due to the technical challenges in its estimation. In this paper, we propose an efficient and reliable statistical method for estimating partial correlation in large-scale brain network modeling. Our method derives partial correlation based on the precision matrix estimated via Constrained L1-minimization Approach (CLIME), which is a recently developed statistical method that is more efficient and demonstrates better performance than the existing methods. To help select an appropriate tuning parameter for sparsity control in the network estimation, we propose a new Dens-based selection method that provides a more informative and flexible tool to allow the users to select the tuning parameter based on the desired sparsity level. Another appealing feature of the Dens-based method is that it is much faster than the existing methods, which provides an important advantage in neuroimaging applications. Simulation studies show that the Dens-based method demonstrates comparable or better performance with respect to the existing methods in network estimation. We applied the proposed partial correlation method to investigate resting state functional connectivity using rs-fMRI data from the Philadelphia Neurodevelopmental Cohort (PNC) study. Our results show that partial correlation analysis removed considerable between-module marginal connections identified by full correlation analysis, suggesting these connections were likely caused by global effects or common connection to other nodes. Based on partial correlation, we find that the most significant

  7. An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone-Beam CT

    Directory of Open Access Journals (Sweden)

    Lei Zhu

    2008-01-01

    Full Text Available Reconstruction algorithms for circular cone-beam (CB scans have been extensively studied in the literature. Since insufficient data are measured, an exact reconstruction is impossible for such a geometry. If the reconstruction algorithm assumes zeros for the missing data, such as the standard FDK algorithm, a major type of resulting CB artifacts is the intensity drop along the axial direction. Many algorithms have been proposed to improve image quality when faced with this problem of data missing; however, development of an effective and computationally efficient algorithm remains a major challenge. In this work, we propose a novel method for estimating the unmeasured data and reducing the intensity drop artifacts. Each CB projection is analyzed in the Radon space via Grangeat's first derivative. Assuming the CB projection is taken from a parallel beam geometry, we extract those data that reside in the unmeasured region of the Radon space. These data are then used as in a parallel beam geometry to calculate a correction term, which is added together with Hu’s correction term to the FDK result to form a final reconstruction. More approximations are then made on the calculation of the additional term, and the final formula is implemented very efficiently. The algorithm performance is evaluated using computer simulations on analytical phantoms. The reconstruction comparison with results using other existing algorithms shows that the proposed algorithm achieves a superior performance on the reduction of axial intensity drop artifacts with a high computation efficiency.

  8. Efficiency in the Worst Production Situation Using Data Envelopment Analysis

    Directory of Open Access Journals (Sweden)

    Md. Kamrul Hossain

    2013-01-01

    Full Text Available Data envelopment analysis (DEA measures relative efficiency among the decision making units (DMU without considering noise in data. The least efficient DMU indicates that it is in the worst situation. In this paper, we measure efficiency of individual DMU whenever it losses the maximum output, and the efficiency of other DMUs is measured in the observed situation. This efficiency is the minimum efficiency of a DMU. The concept of stochastic data envelopment analysis (SDEA is a DEA method which considers the noise in data which is proposed in this study. Using bounded Pareto distribution, we estimate the DEA efficiency from efficiency interval. Small value of shape parameter can estimate the efficiency more accurately using the Pareto distribution. Rank correlations were estimated between observed efficiencies and minimum efficiency as well as between observed and estimated efficiency. The correlations are indicating the effectiveness of this SDEA model.

  9. Increased Statistical Efficiency in a Lognormal Mean Model

    Directory of Open Access Journals (Sweden)

    Grant H. Skrepnek

    2014-01-01

    Full Text Available Within the context of clinical and other scientific research, a substantial need exists for an accurate determination of the point estimate in a lognormal mean model, given that highly skewed data are often present. As such, logarithmic transformations are often advocated to achieve the assumptions of parametric statistical inference. Despite this, existing approaches that utilize only a sample’s mean and variance may not necessarily yield the most efficient estimator. The current investigation developed and tested an improved efficient point estimator for a lognormal mean by capturing more complete information via the sample’s coefficient of variation. Results of an empirical simulation study across varying sample sizes and population standard deviations indicated relative improvements in efficiency of up to 129.47 percent compared to the usual maximum likelihood estimator and up to 21.33 absolute percentage points above the efficient estimator presented by Shen and colleagues (2006. The relative efficiency of the proposed estimator increased particularly as a function of decreasing sample size and increasing population standard deviation.

  10. Angiogenesis in breast cancer: a comparative study of the observer variability of methods for determining microvessel density

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Rose, C

    1998-01-01

    included Chalkley counting, estimation of intratumoral microvessel density (MVD) by one hot-spot, MVD by the mean value of three hot-spots, and the highest value of MVD in three hot-spots. In addition, we applied stereology in the quantification of angiogenesis in the whole tumor section by random...

  11. Quantitative relationships in delphinid neocortex

    DEFF Research Database (Denmark)

    Mortensen, Heidi S.; Pakkenberg, Bente; Dam, Maria

    2014-01-01

    total number of brain cells in cetaceans, and even fewer have used unbiased counting methods. In this study, using stereological methods, we estimated the total number of cells in the neocortex of the long-finned pilot whale (Globicephala melas) brain. For the first time, we show that a species...

  12. Combining counts and incidence data: an efficient approach for estimating the log-normal species abundance distribution and diversity indices.

    Science.gov (United States)

    Bellier, Edwige; Grøtan, Vidar; Engen, Steinar; Schartau, Ann Kristin; Diserud, Ola H; Finstad, Anders G

    2012-10-01

    Obtaining accurate estimates of diversity indices is difficult because the number of species encountered in a sample increases with sampling intensity. We introduce a novel method that requires that the presence of species in a sample to be assessed while the counts of the number of individuals per species are only required for just a small part of the sample. To account for species included as incidence data in the species abundance distribution, we modify the likelihood function of the classical Poisson log-normal distribution. Using simulated community assemblages, we contrast diversity estimates based on a community sample, a subsample randomly extracted from the community sample, and a mixture sample where incidence data are added to a subsample. We show that the mixture sampling approach provides more accurate estimates than the subsample and at little extra cost. Diversity indices estimated from a freshwater zooplankton community sampled using the mixture approach show the same pattern of results as the simulation study. Our method efficiently increases the accuracy of diversity estimates and comprehension of the left tail of the species abundance distribution. We show how to choose the scale of sample size needed for a compromise between information gained, accuracy of the estimates and cost expended when assessing biological diversity. The sample size estimates are obtained from key community characteristics, such as the expected number of species in the community, the expected number of individuals in a sample and the evenness of the community.

  13. SCoPE: an efficient method of Cosmological Parameter Estimation

    International Nuclear Information System (INIS)

    Das, Santanu; Souradeep, Tarun

    2014-01-01

    Markov Chain Monte Carlo (MCMC) sampler is widely used for cosmological parameter estimation from CMB and other data. However, due to the intrinsic serial nature of the MCMC sampler, convergence is often very slow. Here we present a fast and independently written Monte Carlo method for cosmological parameter estimation named as Slick Cosmological Parameter Estimator (SCoPE), that employs delayed rejection to increase the acceptance rate of a chain, and pre-fetching that helps an individual chain to run on parallel CPUs. An inter-chain covariance update is also incorporated to prevent clustering of the chains allowing faster and better mixing of the chains. We use an adaptive method for covariance calculation to calculate and update the covariance automatically as the chains progress. Our analysis shows that the acceptance probability of each step in SCoPE is more than 95% and the convergence of the chains are faster. Using SCoPE, we carry out some cosmological parameter estimations with different cosmological models using WMAP-9 and Planck results. One of the current research interests in cosmology is quantifying the nature of dark energy. We analyze the cosmological parameters from two illustrative commonly used parameterisations of dark energy models. We also asses primordial helium fraction in the universe can be constrained by the present CMB data from WMAP-9 and Planck. The results from our MCMC analysis on the one hand helps us to understand the workability of the SCoPE better, on the other hand it provides a completely independent estimation of cosmological parameters from WMAP-9 and Planck data

  14. Efficient estimates of cochlear hearing loss parameters in individual listeners

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Jepsen, Morten Løve; Dau, Torsten

    2013-01-01

    It has been suggested that the level corresponding to the knee-point of the basilar membrane (BM) input/output (I/O) function can be used to estimate the amount of inner- and outer hair-cell loss (IHL, OHL) in listeners with a moderate cochlear hearing impairment Plack et al. (2004). According...... to Jepsen and Dau (2011) IHL + OHL = HLT [dB], where HLT stands for total hearing loss. Hence having estimates of the total hearing loss and OHC loss, one can estimate the IHL. In the present study, results from forward masking experiments based on temporal masking curves (TMC; Nelson et al., 2001...... estimates of the knee-point level. Further, it is explored whether it is possible to estimate the compression ratio using only on-frequency TMCs. 10 normal-hearing and 10 hearing-impaired listeners (with mild-to-moderate sensorineural hearing loss) were tested at 1, 2 and 4 kHz. The results showed...

  15. Review of Evaluation, Measurement and Verification Approaches Used to Estimate the Load Impacts and Effectiveness of Energy Efficiency Programs

    Energy Technology Data Exchange (ETDEWEB)

    Messenger, Mike; Bharvirkar, Ranjit; Golemboski, Bill; Goldman, Charles A.; Schiller, Steven R.

    2010-04-14

    Public and private funding for end-use energy efficiency actions is expected to increase significantly in the United States over the next decade. For example, Barbose et al (2009) estimate that spending on ratepayer-funded energy efficiency programs in the U.S. could increase from $3.1 billion in 2008 to $7.5 and 12.4 billion by 2020 under their medium and high scenarios. This increase in spending could yield annual electric energy savings ranging from 0.58% - 0.93% of total U.S. retail sales in 2020, up from 0.34% of retail sales in 2008. Interest in and support for energy efficiency has broadened among national and state policymakers. Prominent examples include {approx}$18 billion in new funding for energy efficiency programs (e.g., State Energy Program, Weatherization, and Energy Efficiency and Conservation Block Grants) in the 2009 American Recovery and Reinvestment Act (ARRA). Increased funding for energy efficiency should result in more benefits as well as more scrutiny of these results. As energy efficiency becomes a more prominent component of the U.S. national energy strategy and policies, assessing the effectiveness and energy saving impacts of energy efficiency programs is likely to become increasingly important for policymakers and private and public funders of efficiency actions. Thus, it is critical that evaluation, measurement, and verification (EM&V) is carried out effectively and efficiently, which implies that: (1) Effective program evaluation, measurement, and verification (EM&V) methodologies and tools are available to key stakeholders (e.g., regulatory agencies, program administrators, consumers, and evaluation consultants); and (2) Capacity (people and infrastructure resources) is available to conduct EM&V activities and report results in ways that support program improvement and provide data that reliably compares achieved results against goals and similar programs in other jurisdictions (benchmarking). The National Action Plan for Energy

  16. A Modularized Efficient Framework for Non-Markov Time Series Estimation

    Science.gov (United States)

    Schamberg, Gabriel; Ba, Demba; Coleman, Todd P.

    2018-06-01

    We present a compartmentalized approach to finding the maximum a-posteriori (MAP) estimate of a latent time series that obeys a dynamic stochastic model and is observed through noisy measurements. We specifically consider modern signal processing problems with non-Markov signal dynamics (e.g. group sparsity) and/or non-Gaussian measurement models (e.g. point process observation models used in neuroscience). Through the use of auxiliary variables in the MAP estimation problem, we show that a consensus formulation of the alternating direction method of multipliers (ADMM) enables iteratively computing separate estimates based on the likelihood and prior and subsequently "averaging" them in an appropriate sense using a Kalman smoother. As such, this can be applied to a broad class of problem settings and only requires modular adjustments when interchanging various aspects of the statistical model. Under broad log-concavity assumptions, we show that the separate estimation problems are convex optimization problems and that the iterative algorithm converges to the MAP estimate. As such, this framework can capture non-Markov latent time series models and non-Gaussian measurement models. We provide example applications involving (i) group-sparsity priors, within the context of electrophysiologic specrotemporal estimation, and (ii) non-Gaussian measurement models, within the context of dynamic analyses of learning with neural spiking and behavioral observations.

  17. Thermodynamic framework for estimating the efficiencies of alkaline batteries

    Energy Technology Data Exchange (ETDEWEB)

    Pound, B G; Singh, R P; MacDonald, D D

    1986-06-01

    A thermodynamic framework has been developed to evaluate the efficiencies of alkaline battery systems for electrolyte (MOH) concentrations from 1 to 8 mol kg/sup -1/ and over the temperature range -10 to 120/sup 0/C. An analysis of the thermodynamic properties of concentrated LiOH, NaOH, and KOH solutions was carried out to provide data for the activity of water, the activity coefficient of the hydroxide ion, and the pH of the electrolyte. Potential-pH relations were then derived for various equilibrium phenomena for the metals Li, Al, Fe, Ni, and Zn in aqueous solutions and, using the data for the alkali metal hydroxides, equilibrium potentials were computed as a function of composition and temperature. These data were then used to calculate reversible cell voltages for a number of battery systems, assuming a knowledge of the cell reactions. Finally, some of the calculated cell voltages were compared with observed cell voltages to compute voltage efficiencies for various alkaline batteries. The voltage efficiencies of H/sub 2//Ni, Fe/Ni, and Zn/Ni test cells were found to be between 90 and 100%, implying that, at least at open circuit, there is little, if any, contribution from parasitic redox couples to the cell potentials for these systems. The efficiency of an Fe/air test cell was relatively low (72%). This is probably due to the less-than-theoretical voltage of the air electrode.

  18. A Production Efficiency Model-Based Method for Satellite Estimates of Corn and Soybean Yields in the Midwestern US

    Directory of Open Access Journals (Sweden)

    Andrew E. Suyker

    2013-11-01

    Full Text Available Remote sensing techniques that provide synoptic and repetitive observations over large geographic areas have become increasingly important in studying the role of agriculture in global carbon cycles. However, it is still challenging to model crop yields based on remotely sensed data due to the variation in radiation use efficiency (RUE across crop types and the effects of spatial heterogeneity. In this paper, we propose a production efficiency model-based method to estimate corn and soybean yields with MODerate Resolution Imaging Spectroradiometer (MODIS data by explicitly handling the following two issues: (1 field-measured RUE values for corn and soybean are applied to relatively pure pixels instead of the biome-wide RUE value prescribed in the MODIS vegetation productivity product (MOD17; and (2 contributions to productivity from vegetation other than crops in mixed pixels are deducted at the level of MODIS resolution. Our estimated yields statistically correlate with the national survey data for rainfed counties in the Midwestern US with low errors for both corn (R2 = 0.77; RMSE = 0.89 MT/ha and soybeans (R2 = 0.66; RMSE = 0.38 MT/ha. Because the proposed algorithm does not require any retrospective analysis that constructs empirical relationships between the reported yields and remotely sensed data, it could monitor crop yields over large areas.

  19. Stereological study on the effect of vitamin C in preventing the adverse effects of bisphenol A on rat ovary

    Directory of Open Access Journals (Sweden)

    Malek Soleimani Mehranjani

    2016-06-01

    Full Text Available Background: Bisphenol A (BPA, an environmental pollutant, can generate free radicals which damages the reproductive system. Vitamin C is an antioxidant which may prevent the adverse effects of free radicals. Objective: The aim was to investigate the effect of vitamin C on the ovary tissue in rats treated with BPA. Materials and Methods: In this experimental study, 24 female Wistar rats (200±20 gr were randomly divided into 4 groups (n=6: control, BPA (60 μg/Kg/day, vitamin C (150 mg/Kg/day and BPA + vitamin C and orally treated for 20 days. The left ovaries were taken out, fixed for tissue processing and studied using stereological methods. Data were analyzed with SPSS using one-way ANOVA, and the means were considered significantly different at (p<0.05. Results: The total volume of ovary and cortex (p<0.01, medulla (p<0.05, the volume of corpus luteum (p<0.001 and the mean number of antral follicles (p<0.001 significantly reduced in BPA group compared with control, while the number of atretic follicles increased (p<0.05. The volume of oocyte (p<0.01 and its nucleus (p<0.001 in the antral follicles and the thickness of zona pellucida (ZP in the secondary (p<0.05 and antral (p<0.001 follicles significantly decreased in BPA group compared with controls. The above parameters in the BPA + vitamin C group were compensated to control level. Conclusion: Vitamin C can be used as a potential antioxidant in the case of BPA toxication

  20. Efficiency in Microfinance Cooperatives

    Directory of Open Access Journals (Sweden)

    HARTARSKA, Valentina

    2012-12-01

    Full Text Available In recognition of cooperatives’ contribution to the socio-economic well-being of their participants, the United Nations has declared 2012 as the International Year of Cooperatives. Microfinance cooperatives make a large part of the microfinance industry. We study efficiency of microfinance cooperatives and provide estimates of the optimal size of such organizations. We employ the classical efficiency analysis consisting of estimating a system of equations and identify the optimal size of microfinance cooperatives in terms of their number of clients (outreach efficiency, as well as dollar value of lending and deposits (sustainability. We find that microfinance cooperatives have increasing returns to scale which means that the vast majority can lower cost if they become larger. We calculate that the optimal size is around $100 million in lending and half of that in deposits. We find less robust estimates in terms of reaching many clients with a range from 40,000 to 180,000 borrowers.

  1. Efficiency profile method to study the hit efficiency of drift chambers

    International Nuclear Information System (INIS)

    Abyzov, A.; Bel'kov, A.; Lanev, A.; Spiridonov, A.; Walter, M.; Hulsbergen, W.

    2002-01-01

    A method based on the usage of efficiency profile is proposed to estimate the hit efficiency of drift chambers with a large number of channels. The performance of the method under real conditions of the detector operation has been tested analysing the experimental data from the HERA-B drift chambers

  2. An Integrated Approach for Estimating the Energy Efficiency of Seventeen Countries

    Directory of Open Access Journals (Sweden)

    Chia-Nan Wang

    2017-10-01

    Full Text Available Increased energy efficiency is one of the most effective ways to achieve climate change mitigation. This study aims to evaluate the energy efficiency of seventeen countries. The evaluation is based on an integrated method that combines the super slack-based (super SBM model and the Malmquist productivity index (MPI to investigate the energy efficiency of seventeen countries during the period of 2010–2015. The results in this study are that the United States, Columbia, Japan, China, and Saudi Arabia perform the best in energy efficiency, whereas Brazil, Russia, Indonesia, and India perform the worst during the entire sample period. The energy efficiency of these countries arrived mainly from technological improvement. The study provides suggestions for the seventeen countries’ government to control the energy consumption and contribute to environmental protection.

  3. Chapter 12: Survey Design and Implementation for Estimating Gross Savings Cross-Cutting Protocol. The Uniform Methods Project: Methods for Determining Energy Efficiency Savings for Specific Measures

    Energy Technology Data Exchange (ETDEWEB)

    Kurnik, Charles W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Baumgartner, Robert [Tetra Tech, Madison, WI (United States)

    2017-10-05

    This chapter presents an overview of best practices for designing and executing survey research to estimate gross energy savings in energy efficiency evaluations. A detailed description of the specific techniques and strategies for designing questions, implementing a survey, and analyzing and reporting the survey procedures and results is beyond the scope of this chapter. So for each topic covered below, readers are encouraged to consult articles and books cited in References, as well as other sources that cover the specific topics in greater depth. This chapter focuses on the use of survey methods to collect data for estimating gross savings from energy efficiency programs.

  4. The efficiency of modified jackknife and ridge type regression estimators: a comparison

    Directory of Open Access Journals (Sweden)

    Sharad Damodar Gore

    2008-09-01

    Full Text Available A common problem in multiple regression models is multicollinearity, which produces undesirable effects on the least squares estimator. To circumvent this problem, two well known estimation procedures are often suggested in the literature. They are Generalized Ridge Regression (GRR estimation suggested by Hoerl and Kennard iteb8 and the Jackknifed Ridge Regression (JRR estimation suggested by Singh et al. iteb13. The GRR estimation leads to a reduction in the sampling variance, whereas, JRR leads to a reduction in the bias. In this paper, we propose a new estimator namely, Modified Jackknife Ridge Regression Estimator (MJR. It is based on the criterion that combines the ideas underlying both the GRR and JRR estimators. We have investigated standard properties of this new estimator. From a simulation study, we find that the new estimator often outperforms the LASSO, and it is superior to both GRR and JRR estimators, using the mean squared error criterion. The conditions under which the MJR estimator is better than the other two competing estimators have been investigated.

  5. Impact of reduced marker set estimation of genomic relationship matrices on genomic selection for feed efficiency in Angus cattle

    Directory of Open Access Journals (Sweden)

    Northcutt Sally L

    2010-04-01

    Full Text Available Abstract Background Molecular estimates of breeding value are expected to increase selection response due to improvements in the accuracy of selection and a reduction in generation interval, particularly for traits that are difficult or expensive to record or are measured late in life. Several statistical methods for incorporating molecular data into breeding value estimation have been proposed, however, most studies have utilized simulated data in which the generated linkage disequilibrium may not represent the targeted livestock population. A genomic relationship matrix was developed for 698 Angus steers and 1,707 Angus sires using 41,028 single nucleotide polymorphisms and breeding values were estimated using feed efficiency phenotypes (average daily feed intake, residual feed intake, and average daily gain recorded on the steers. The number of SNPs needed to accurately estimate a genomic relationship matrix was evaluated in this population. Results Results were compared to estimates produced from pedigree-based mixed model analysis of 862 Angus steers with 34,864 identified paternal relatives but no female ancestors. Estimates of additive genetic variance and breeding value accuracies were similar for AFI and RFI using the numerator and genomic relationship matrices despite fewer animals in the genomic analysis. Bootstrap analyses indicated that 2,500-10,000 markers are required for robust estimation of genomic relationship matrices in cattle. Conclusions This research shows that breeding values and their accuracies may be estimated for commercially important sires for traits recorded in experimental populations without the need for pedigree data to establish identity by descent between members of the commercial and experimental populations when at least 2,500 SNPs are available for the generation of a genomic relationship matrix.

  6. Robust estimation and hypothesis testing

    CERN Document Server

    Tiku, Moti L

    2004-01-01

    In statistical theory and practice, a certain distribution is usually assumed and then optimal solutions sought. Since deviations from an assumed distribution are very common, one cannot feel comfortable with assuming a particular distribution and believing it to be exactly correct. That brings the robustness issue in focus. In this book, we have given statistical procedures which are robust to plausible deviations from an assumed mode. The method of modified maximum likelihood estimation is used in formulating these procedures. The modified maximum likelihood estimators are explicit functions of sample observations and are easy to compute. They are asymptotically fully efficient and are as efficient as the maximum likelihood estimators for small sample sizes. The maximum likelihood estimators have computational problems and are, therefore, elusive. A broad range of topics are covered in this book. Solutions are given which are easy to implement and are efficient. The solutions are also robust to data anomali...

  7. Histogram Estimators of Bivariate Densities

    National Research Council Canada - National Science Library

    Husemann, Joyce A

    1986-01-01

    One-dimensional fixed-interval histogram estimators of univariate probability density functions are less efficient than the analogous variable-interval estimators which are constructed from intervals...

  8. HOW MANY LOBSTERS ARE IN THE SEA?

    Directory of Open Access Journals (Sweden)

    Ernest Enns

    2011-05-01

    Full Text Available A lobster fishery must have a reasonable estimate of the number of lobsters within the fishery in order to regulate the annual harvest. Stereological sampling procedures are used to estimate the number of lobsters in a defined region of the sea. From a given point in the fishery, a selective sample in a random direction to the boundary of the fishery is taken. This is repeated to generate a systematic sample from which the total population is estimated.

  9. Efficiency model of Russian banks

    OpenAIRE

    Pavlyuk, Dmitry

    2006-01-01

    The article deals with problems related to the stochastic frontier model of bank efficiency measurement. The model is used to study the efficiency of the banking sector of The Russian Federation. It is based on the stochastic approach both to the efficiency frontier location and to individual bank efficiency values. The model allows estimating bank efficiency values, finding relations with different macro- and microeconomic factors and testing some economic hypotheses.

  10. Multi-directional program efficiency

    DEFF Research Database (Denmark)

    Asmild, Mette; Balezentis, Tomas; Hougaard, Jens Leth

    2016-01-01

    The present paper analyses both managerial and program efficiencies of Lithuanian family farms, in the tradition of Charnes et al. (Manag Sci 27(6):668–697, 1981) but with the important difference that multi-directional efficiency analysis rather than the traditional data envelopment analysis...... approach is used to estimate efficiency. This enables a consideration of input-specific efficiencies. The study shows clear differences between the efficiency scores on the different inputs as well as between the farm types of crop, livestock and mixed farms respectively. We furthermore find that crop...... farms have the highest program efficiency, but the lowest managerial efficiency and that the mixed farms have the lowest program efficiency (yet not the highest managerial efficiency)....

  11. Dose-response curve estimation: a semiparametric mixture approach.

    Science.gov (United States)

    Yuan, Ying; Yin, Guosheng

    2011-12-01

    In the estimation of a dose-response curve, parametric models are straightforward and efficient but subject to model misspecifications; nonparametric methods are robust but less efficient. As a compromise, we propose a semiparametric approach that combines the advantages of parametric and nonparametric curve estimates. In a mixture form, our estimator takes a weighted average of the parametric and nonparametric curve estimates, in which a higher weight is assigned to the estimate with a better model fit. When the parametric model assumption holds, the semiparametric curve estimate converges to the parametric estimate and thus achieves high efficiency; when the parametric model is misspecified, the semiparametric estimate converges to the nonparametric estimate and remains consistent. We also consider an adaptive weighting scheme to allow the weight to vary according to the local fit of the models. We conduct extensive simulation studies to investigate the performance of the proposed methods and illustrate them with two real examples. © 2011, The International Biometric Society.

  12. 高效超分辨波达方向估计算法综述%Overview of efficient algorithms for super-resolution DOA estimates

    Institute of Scientific and Technical Information of China (English)

    闫锋刚; 沈毅; 刘帅; 金铭; 乔晓林

    2015-01-01

    Computationally efficient methods for super-resolution direction of arrival (DOA)estimation aim to reduce the complexity of conventional techniques,to economize on the costs of systems and to enhance the ro-bustness of DOA estimators against array geometries and other environmental restrictions,which has been an important topic in the field.According to the theory and elements of the multiple signal classification (MUSIC) algorithm and the primary derivations from MUSIC,state-of-the-art efficient super-resolution DOA estimators are classified into five different types.These five types of approaches reduce the complexity by real-valued com-putation,beam-space transformation,fast subspace estimation,rapid spectral search,and no spectral search, respectively.With such a classification,comprehensive overviews of each kind of efficient methods are given and numerical comparisons among these estimators are also conducted to illustrate their advantages.Future develop-ment trends of efficient algorithms for super-resolution DOA estimates are finally predicted with basic require-ments of real-world applications.%高效超分辨波达方向估计算法致力于降低超分辨算法的计算量、节约系统的实现成本、弱化算法对于阵列结构的依赖性,是推进超分辨理论工程化的一个重要研究课题。从多重信号分类(multiple signal classifi-cation,MUSIC)算法的原理和构成要素入手,以基于 MUSIC 派生高效超分辨算法的目的和方法为标准,将现存高效超分辨算法划分为实值运算、波束域变换、快速子空间估计、快速峰值搜索和免峰值搜索5大类。在此基础上,全面回顾总结了各类高效算法的发展历程和最新进展,对比分析了它们的主要优缺点。最后,结合空间谱估计实际工程化的应用需求,指出了高效超分辨算法的未来发展趋势。

  13. PRESIDENT’S ADDRESS

    Directory of Open Access Journals (Sweden)

    Lucie Kubínová

    2016-03-01

    Full Text Available Dear colleagues, Let me wish you and our Image Analysis & Stereology Journal all the best in 2016. It is great honour for me to be in charge of the International Society for Stereology (ISS. I would like to thank Eric Pirard for all his tremendous work and effort he has put into ISS activities in past years, together with all members of the ISS Board. I am glad Eric is willing to help me with ISS as „Immediate Past President“. I also rely on close collaboration with Ida Eržen and Marko Kreft, the Editors-in-Chief of Image Analysis & Stereology (IAS, IAS Editorial Board and future ISS Board. I appreciate long-term cooperation between the Image Analysis & Stereology Journal and the International Society for Stereology and I am looking forward to broaden our relationships in the future. As a President of ISS I plan to evoke new activities which would help to make ISS vivid and useful to scientific community. We are planning new courses on stereology, image analysis and related topics run in cooperation with ISS with reduced fee for ISS members, competion for the best PhD thesis using stereology and/or image analysis, ISS history mapping, etc. I welcome your further suggestions and comments. I would like to cordially invite you to become members of the International Society for Stereology (http://stereologysociety.org/membership.html and to take part in new activities organized by ISS, such as:Special Session „3D Image Analysis and Stereology in Fluorescence Microscopy“ at ISBI 2016 (in Prague, see http://biomedicalimaging.org/2016/?page_id=768.Round table discussion on „Stereology and 3D image analysis in microscopy“ to be held at the 16th European Microscopy Congress in Lyon (EMC 2016, see http://www.emc2016.fr/en/scientific-programme/special/stereology.It is my intention to involve young people and fresh ideas in the activities of ISS and in further improvement of IAS. Please contact me at lucie

  14. A new approach to estimate the geometrical factors, solid angle approximation, geometrical efficiency and their use in basic interaction cross section measurements

    CERN Document Server

    Rao, D V; Brunetti, A; Gigante, G E; Takeda, T; Itai, Y; Akatsuka, T

    2002-01-01

    A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic K alpha radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work. (authors)

  15. A new approach to estimate the geometrical factors, solid angle approximation, geometrical efficiency and their use in basic interaction cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rao, D.V.; Cesareo, R.; Brunetti, A. [Sassari University, Istituto di Matematica e Fisica (Italy); Gigante, G.E. [Roma Universita, Dipt. di Fisica (Italy); Takeda, T.; Itai, Y. [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Akatsuka, T. [Yamagata Univ., Yonezawa (Japan). Faculty of Engineering

    2002-10-01

    A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic K{alpha} radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work. (authors)

  16. A new approach to estimate the geometrical factors, solid angle approximation, geometrical efficiency and their use in basic interaction cross section measurements

    Science.gov (United States)

    Rao, D. V.; Cesareo, R.; Brunetti, A.; Gigante, G. E.; Takeda, T.; Itai, Y.; Akatsuka, T.

    2002-10-01

    A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic Kα radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work.

  17. Efficient Topology Estimation for Large Scale Optical Mapping

    CERN Document Server

    Elibol, Armagan; Garcia, Rafael

    2013-01-01

    Large scale optical mapping methods are in great demand among scientists who study different aspects of the seabed, and have been fostered by impressive advances in the capabilities of underwater robots in gathering optical data from the seafloor. Cost and weight constraints mean that low-cost ROVs usually have a very limited number of sensors. When a low-cost robot carries out a seafloor survey using a down-looking camera, it usually follows a predefined trajectory that provides several non time-consecutive overlapping image pairs. Finding these pairs (a process known as topology estimation) is indispensable to obtaining globally consistent mosaics and accurate trajectory estimates, which are necessary for a global view of the surveyed area, especially when optical sensors are the only data source. This book contributes to the state-of-art in large area image mosaicing methods for underwater surveys using low-cost vehicles equipped with a very limited sensor suite. The main focus has been on global alignment...

  18. The efficiency of parameter estimation of latent path analysis using summated rating scale (SRS) and method of successive interval (MSI) for transformation of score to scale

    Science.gov (United States)

    Solimun, Fernandes, Adji Achmad Rinaldo; Arisoesilaningsih, Endang

    2017-12-01

    Research in various fields generally investigates systems and involves latent variables. One method to analyze the model representing the system is path analysis. The data of latent variables measured using questionnaires by applying attitude scale model yields data in the form of score, before analyzed should be transformation so that it becomes data of scale. Path coefficient, is parameter estimator, calculated from scale data using method of successive interval (MSI) and summated rating scale (SRS). In this research will be identifying which data transformation method is better. Path coefficients have smaller varieties are said to be more efficient. The transformation method that produces scaled data and used in path analysis capable of producing path coefficients (parameter estimators) with smaller varieties is said to be better. The result of analysis using real data shows that on the influence of Attitude variable to Intention Entrepreneurship, has relative efficiency (ER) = 1, where it shows that the result of analysis using data transformation of MSI and SRS as efficient. On the other hand, for simulation data, at high correlation between items (0.7-0.9), MSI method is more efficient 1.3 times better than SRS method.

  19. 16 CFR 305.5 - Determinations of estimated annual energy consumption, estimated annual operating cost, and...

    Science.gov (United States)

    2010-01-01

    ... consumption, estimated annual operating cost, and energy efficiency rating, and of water use rate. 305.5... RULE CONCERNING DISCLOSURES REGARDING ENERGY CONSUMPTION AND WATER USE OF CERTAIN HOME APPLIANCES AND... § 305.5 Determinations of estimated annual energy consumption, estimated annual operating cost, and...

  20. Efficiencies of Internet-based digital and paper-based scientific surveys and the estimated costs and time for different-sized cohorts.

    Directory of Open Access Journals (Sweden)

    Constantin E Uhlig

    Full Text Available To evaluate the relative efficiencies of five Internet-based digital and three paper-based scientific surveys and to estimate the costs for different-sized cohorts.Invitations to participate in a survey were distributed via e-mail to employees of two university hospitals (E1 and E2 and to members of a medical association (E3, as a link placed in a special text on the municipal homepage regularly read by the administrative employees of two cities (H1 and H2, and paper-based to workers at an automobile enterprise (P1 and college (P2 and senior (P3 students. The main parameters analyzed included the numbers of invited and actual participants, and the time and cost to complete the survey. Statistical analysis was descriptive, except for the Kruskal-Wallis-H-test, which was used to compare the three recruitment methods. Cost efficiencies were compared and extrapolated to different-sized cohorts.The ratios of completely answered questionnaires to distributed questionnaires were between 81.5% (E1 and 97.4% (P2. Between 6.4% (P1 and 57.0% (P2 of the invited participants completely answered the questionnaires. The costs per completely answered questionnaire were $0.57-$1.41 (E1-3, $1.70 and $0.80 for H1 and H2, respectively, and $3.36-$4.21 (P1-3. Based on our results, electronic surveys with 10, 20, 30, or 42 questions would be estimated to be most cost (and time efficient if more than 101.6-225.9 (128.2-391.7, 139.8-229.2 (93.8-193.6, 165.8-230.6 (68.7-115.7, or 188.2-231.5 (44.4-72.7 participants were required, respectively.The study efficiency depended on the technical modalities of the survey methods and engagement of the participants. Depending on our study design, our results suggest that in similar projects that will certainly have more than two to three hundred required participants, the most efficient way of conducting a questionnaire-based survey is likely via the Internet with a digital questionnaire, specifically via a centralized e-mail.

  1. Relationship between competition and efficiency in the Czech banking industry

    Directory of Open Access Journals (Sweden)

    Iveta Řepková

    2013-01-01

    Full Text Available The aim of the paper is to estimate the relationship between competition and efficiency in the Czech banking industry in the period 2001–2010. The theoretical definition and literature review of the relationship between banking competition and efficiency is included. Lerner index and Data Envelopment Analysis were used to estimate the degree of competition and efficiency in the Czech banking sector. The market structure of the Czech banking industry was estimated as a monopolistic competition and it was found a slight increase in the competition in the banking sector. The efficiency of the Czech banks increased in the analysed period. Using a Johansen cointegration test, the paper contributes to the empirical literature, testing not only the causality running from competition to efficiency, but also the reverse effect running from efficiency to competition. The positive relationship between competition and efficiency was estimated in the Czech banking sector. These findings are in line with the Quiet Life Hypothesis and the suggestions that the increase of the competition will contribute to efficiency.

  2. Generalized Centroid Estimators in Bioinformatics

    Science.gov (United States)

    Hamada, Michiaki; Kiryu, Hisanori; Iwasaki, Wataru; Asai, Kiyoshi

    2011-01-01

    In a number of estimation problems in bioinformatics, accuracy measures of the target problem are usually given, and it is important to design estimators that are suitable to those accuracy measures. However, there is often a discrepancy between an employed estimator and a given accuracy measure of the problem. In this study, we introduce a general class of efficient estimators for estimation problems on high-dimensional binary spaces, which represent many fundamental problems in bioinformatics. Theoretical analysis reveals that the proposed estimators generally fit with commonly-used accuracy measures (e.g. sensitivity, PPV, MCC and F-score) as well as it can be computed efficiently in many cases, and cover a wide range of problems in bioinformatics from the viewpoint of the principle of maximum expected accuracy (MEA). It is also shown that some important algorithms in bioinformatics can be interpreted in a unified manner. Not only the concept presented in this paper gives a useful framework to design MEA-based estimators but also it is highly extendable and sheds new light on many problems in bioinformatics. PMID:21365017

  3. Efficient Maximum Likelihood Estimation for Pedigree Data with the Sum-Product Algorithm.

    Science.gov (United States)

    Engelhardt, Alexander; Rieger, Anna; Tresch, Achim; Mansmann, Ulrich

    2016-01-01

    We analyze data sets consisting of pedigrees with age at onset of colorectal cancer (CRC) as phenotype. The occurrence of familial clusters of CRC suggests the existence of a latent, inheritable risk factor. We aimed to compute the probability of a family possessing this risk factor as well as the hazard rate increase for these risk factor carriers. Due to the inheritability of this risk factor, the estimation necessitates a costly marginalization of the likelihood. We propose an improved EM algorithm by applying factor graphs and the sum-product algorithm in the E-step. This reduces the computational complexity from exponential to linear in the number of family members. Our algorithm is as precise as a direct likelihood maximization in a simulation study and a real family study on CRC risk. For 250 simulated families of size 19 and 21, the runtime of our algorithm is faster by a factor of 4 and 29, respectively. On the largest family (23 members) in the real data, our algorithm is 6 times faster. We introduce a flexible and runtime-efficient tool for statistical inference in biomedical event data with latent variables that opens the door for advanced analyses of pedigree data. © 2017 S. Karger AG, Basel.

  4. On the Optimality of Multivariate S-Estimators

    NARCIS (Netherlands)

    Croux, C.; Dehon, C.; Yadine, A.

    2010-01-01

    In this paper we maximize the efficiency of a multivariate S-estimator under a constraint on the breakdown point. In the linear regression model, it is known that the highest possible efficiency of a maximum breakdown S-estimator is bounded above by 33% for Gaussian errors. We prove the surprising

  5. Radiation risk estimation based on measurement error models

    CERN Document Server

    Masiuk, Sergii; Shklyar, Sergiy; Chepurny, Mykola; Likhtarov, Illya

    2017-01-01

    This monograph discusses statistics and risk estimates applied to radiation damage under the presence of measurement errors. The first part covers nonlinear measurement error models, with a particular emphasis on efficiency of regression parameter estimators. In the second part, risk estimation in models with measurement errors is considered. Efficiency of the methods presented is verified using data from radio-epidemiological studies.

  6. Economics of appliance efficiency

    International Nuclear Information System (INIS)

    Tiedemann, K.H.

    2009-01-01

    Several significant developments occurred in 2001 that affect the impact of market transformation programs. This paper presented and applied an econometric approach to the identification and estimation of market models for refrigerators, clothes washers, dishwashers and room air conditioners. The purpose of the paper was to understand the impact of energy conservation policy developments on sales of energy efficient appliances. The paper discussed the approach with particular reference to building a database of sales and drivers of sales using publicly available information; estimation of the determinants of sales using econometric models; and estimation of the individual impacts of prices, gross domestic product (GDP) and energy conservation policies on sales using regression results. Market and policy developments were also presented, such as change a light, save the world promotion; the California energy crisis; and the Pacific Northwest drought induced hydro power shortage. It was concluded that an increase in GDP increased the sales of both more efficient and less efficient refrigerators, clothes washers, dishwashers, and room air conditioners. An increase in electricity price increased sales of Energy Star refrigerators, clothes washers, dishwashers, and room air conditioners. 4 refs., 8 tabs.

  7. Implant surface preparation in the surgical treatment of experimental peri-implantitis with autogenous bone graft and ePTFE membrane in cynomolgus monkeys

    DEFF Research Database (Denmark)

    Schou, Søren; Holmstrup, Palle; Jørgensen, Torben

    2003-01-01

    peri-implantitis; treatment; implant surface preparation; nonhuman primates; histology; stereology......peri-implantitis; treatment; implant surface preparation; nonhuman primates; histology; stereology...

  8. Typology of efficiency of functioning of enterprise

    Directory of Open Access Journals (Sweden)

    I.I. Svitlyshyn

    2015-03-01

    Full Text Available Measuring and estimation of the efficiency of functioning of enterprises of agrarian sector traditionally performed by applying only some of its types, which focuses mainly on operating activity. Investment and financial activity, as inalienable constituent of economic process of enterprise, remain regardless thus. In addition, in scientific literature and practical activity to research of efficiency focuses on the stages «production-exchange». The stages of «distribution» and «consumption» at the level of enterprise are not examined. This distorts the results of measuring and estimation of efficiency and makes uneffective proposals for its growth. Coming from what, approach is worked out to determination and systematization of basic types of efficiency of functioning of enterprises of agrarian sector. Approach is based on the offered model, that system represents all stages and types of economic activity of the enterprise. The basic lines of efficiency are interpreted on every stage and in the cut of types of economic activity of enterprise. It allows to provide a complexity and system during its measuring and estimation.

  9. Sparse DOA estimation with polynomial rooting

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Fernandez Grande, Efren

    2015-01-01

    Direction-of-arrival (DOA) estimation involves the localization of a few sources from a limited number of observations on an array of sensors. Thus, DOA estimation can be formulated as a sparse signal reconstruction problem and solved efficiently with compressive sensing (CS) to achieve highresol......Direction-of-arrival (DOA) estimation involves the localization of a few sources from a limited number of observations on an array of sensors. Thus, DOA estimation can be formulated as a sparse signal reconstruction problem and solved efficiently with compressive sensing (CS) to achieve...... highresolution imaging. Utilizing the dual optimal variables of the CS optimization problem, it is shown with Monte Carlo simulations that the DOAs are accurately reconstructed through polynomial rooting (Root-CS). Polynomial rooting is known to improve the resolution in several other DOA estimation methods...

  10. Relative Pose Estimation Algorithm with Gyroscope Sensor

    Directory of Open Access Journals (Sweden)

    Shanshan Wei

    2016-01-01

    Full Text Available This paper proposes a novel vision and inertial fusion algorithm S2fM (Simplified Structure from Motion for camera relative pose estimation. Different from current existing algorithms, our algorithm estimates rotation parameter and translation parameter separately. S2fM employs gyroscopes to estimate camera rotation parameter, which is later fused with the image data to estimate camera translation parameter. Our contributions are in two aspects. (1 Under the circumstance that no inertial sensor can estimate accurately enough translation parameter, we propose a translation estimation algorithm by fusing gyroscope sensor and image data. (2 Our S2fM algorithm is efficient and suitable for smart devices. Experimental results validate efficiency of the proposed S2fM algorithm.

  11. Feed Forward Artificial Neural Network Model to Estimate the TPH Removal Efficiency in Soil Washing Process

    Directory of Open Access Journals (Sweden)

    Hossein Jafari Mansoorian

    2017-01-01

    Full Text Available Background & Aims of the Study: A feed forward artificial neural network (FFANN was developed to predict the efficiency of total petroleum hydrocarbon (TPH removal from a contaminated soil, using soil washing process with Tween 80. The main objective of this study was to assess the performance of developed FFANN model for the estimation of   TPH removal. Materials and Methods: Several independent repressors including pH, shaking speed, surfactant concentration and contact time were used to describe the removal of TPH as a dependent variable in a FFANN model. 85% of data set observations were used for training the model and remaining 15% were used for model testing, approximately. The performance of the model was compared with linear regression and assessed, using Root of Mean Square Error (RMSE as goodness-of-fit measure Results: For the prediction of TPH removal efficiency, a FANN model with a three-hidden-layer structure of 4-3-1 and a learning rate of 0.01 showed the best predictive results. The RMSE and R2 for the training and testing steps of the model were obtained to be 2.596, 0.966, 10.70 and 0.78, respectively. Conclusion: For about 80% of the TPH removal efficiency can be described by the assessed regressors the developed model. Thus, focusing on the optimization of soil washing process regarding to shaking speed, contact time, surfactant concentration and pH can improve the TPH removal performance from polluted soils. The results of this study could be the basis for the application of FANN for the assessment of soil washing process and the control of petroleum hydrocarbon emission into the environments.

  12. Agent-based Security and Efficiency Estimation in Airport Terminals

    NARCIS (Netherlands)

    Janssen, S.A.M.

    We investigate the use of an Agent-based framework to identify and quantify the relationship between security and efficiency within airport terminals. In this framework, we define a novel Security Risk Assessment methodology that explicitly models attacker and defender behavior in a security

  13. Plant Friendly Input Design for Parameter Estimation in an Inertial System with Respect to D-Efficiency Constraints

    Directory of Open Access Journals (Sweden)

    Wiktor Jakowluk

    2014-11-01

    Full Text Available System identification, in practice, is carried out by perturbing processes or plants under operation. That is why in many industrial applications a plant-friendly input signal would be preferred for system identification. The goal of the study is to design the optimal input signal which is then employed in the identification experiment and to examine the relationships between the index of friendliness of this input signal and the accuracy of parameter estimation when the measured output signal is significantly affected by noise. In this case, the objective function was formulated through maximisation of the Fisher information matrix determinant (D-optimality expressed in conventional Bolza form. As setting such conditions of the identification experiment we can only talk about the D-suboptimality, we quantify the plant trajectories using the D-efficiency measure. An additional constraint, imposed on D-efficiency of the solution, should allow one to attain the most adequate information content  from the plant which operating point is perturbed in the least invasive (most friendly way. A simple numerical example, which clearly demonstrates the idea presented in the paper, is included and discussed.

  14. On the Use of Student Data in Efficiency Analysis--Technical Efficiency in Swedish Upper Secondary School

    Science.gov (United States)

    Waldo, Staffan

    2007-01-01

    While individual data form the base for much empirical analysis in education, this is not the case for analysis of technical efficiency. In this paper, efficiency is estimated using individual data which is then aggregated to larger groups of students. Using an individual approach to technical efficiency makes it possible to carry out studies on a…

  15. An improved routine for the fast estimate of ion cyclotron heating efficiency in tokamak plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1992-02-01

    The subroutine ICEVAL for the rapid simulation of Ion Cyclotron Heating in tokamak plasmas is based on analytic estimates of the wave behaviour near resonances, and on drastic but reasonable simplifications of the real geometry. The subroutine has been rewritten to improve the model and to facilitate its use as input in transport codes. In the new version the influence of quasilinear minority heating on the damping efficiency is taken into account using the well-known Stix analytic approximation. Among other improvements are: a) the possibility of considering plasmas with more than two ion species; b) inclusion of Landau, Transit Time and collisional damping on the electrons non localised at resonances; c) better models for the antenna spectrum and for the construction of the power deposition profiles. The results of ICEVAL are compared in detail with those of the full-wave code FELICE for the case of Hydrogen minority heating in a Deuterium plasma; except for details which depend on the excitation of global eigenmodes, agreement is excellent. ICEVAL is also used to investigate the enhancement of the absorption efficiency due to quasilinear heating of the minority ions. The effect is a strongly non-linear function of the available power, and decreases rapidly with increasing concentration. For parameters typical of Asdex Upgrade plasmas, about 4 MW are required to produce a significant increase of the single-pass absorption at concentrations between 10 and 20%. (orig.)

  16. Efficient scatter distribution estimation and correction in CBCT using concurrent Monte Carlo fitting

    Energy Technology Data Exchange (ETDEWEB)

    Bootsma, G. J., E-mail: Gregory.Bootsma@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada); Verhaegen, F. [Department of Radiation Oncology - MAASTRO, GROW—School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Medical Physics Unit, Department of Oncology, McGill University, Montreal, Quebec H3G 1A4 (Canada); Jaffray, D. A. [Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada)

    2015-01-15

    suitable GOF metric with strong correlation with the actual error of the scatter fit, S{sub F}. Fitting the scatter distribution to a limited sum of sine and cosine functions using a low-pass filtered fast Fourier transform provided a computationally efficient and accurate fit. The CMCF algorithm reduces the number of photon histories required by over four orders of magnitude. The simulated experiments showed that using a compensator reduced the computational time by a factor between 1.5 and 1.75. The scatter estimates for the simulated and measured data were computed between 35–93 s and 114–122 s, respectively, using 16 Intel Xeon cores (3.0 GHz). The CMCF scatter correction improved the contrast-to-noise ratio by 10%–50% and reduced the reconstruction error to under 3% for the simulated phantoms. Conclusions: The novel CMCF algorithm significantly reduces the computation time required to estimate the scatter distribution by reducing the statistical noise in the MC scatter estimate and limiting the number of projection angles that must be simulated. Using the scatter estimate provided by the CMCF algorithm to correct both simulated and real projection data showed improved reconstruction image quality.

  17. Optimizing Sampling Efficiency for Biomass Estimation Across NEON Domains

    Science.gov (United States)

    Abercrombie, H. H.; Meier, C. L.; Spencer, J. J.

    2013-12-01

    Over the course of 30 years, the National Ecological Observatory Network (NEON) will measure plant biomass and productivity across the U.S. to enable an understanding of terrestrial carbon cycle responses to ecosystem change drivers. Over the next several years, prior to operational sampling at a site, NEON will complete construction and characterization phases during which a limited amount of sampling will be done at each site to inform sampling designs, and guide standardization of data collection across all sites. Sampling biomass in 60+ sites distributed among 20 different eco-climatic domains poses major logistical and budgetary challenges. Traditional biomass sampling methods such as clip harvesting and direct measurements of Leaf Area Index (LAI) involve collecting and processing plant samples, and are time and labor intensive. Possible alternatives include using indirect sampling methods for estimating LAI such as digital hemispherical photography (DHP) or using a LI-COR 2200 Plant Canopy Analyzer. These LAI estimations can then be used as a proxy for biomass. The biomass estimates calculated can then inform the clip harvest sampling design during NEON operations, optimizing both sample size and number so that standardized uncertainty limits can be achieved with a minimum amount of sampling effort. In 2011, LAI and clip harvest data were collected from co-located sampling points at the Central Plains Experimental Range located in northern Colorado, a short grass steppe ecosystem that is the NEON Domain 10 core site. LAI was measured with a LI-COR 2200 Plant Canopy Analyzer. The layout of the sampling design included four, 300 meter transects, with clip harvests plots spaced every 50m, and LAI sub-transects spaced every 10m. LAI was measured at four points along 6m sub-transects running perpendicular to the 300m transect. Clip harvest plots were co-located 4m from corresponding LAI transects, and had dimensions of 0.1m by 2m. We conducted regression analyses

  18. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  19. Estimating the potential for electricity savings in households

    International Nuclear Information System (INIS)

    Boogen, Nina

    2017-01-01

    Improving efficiency in the use of energy is an important goal for many nations since end-use energy efficiency can help to reduce CO_2 emissions. Furthermore, since the residential sector in industrialised countries requires around one third of the end-use electricity, it is important for policy makers to estimate the scope for electricity saving in households to reduce electricity consumption by using appropriate steering mechanisms. We estimate the level of technical efficiency in the use of electricity using data from a Swiss household survey. We find an average inefficiency in electricity use by Swiss households of around 20 to 25%. Bottom-up economic-engineering models estimate the potential in Switzerland to be around 15%. In this paper we use a sub-vector input distance frontier function based on economic foundations. Our estimates lie at the upper end of the electricity saving potential estimated by the afore-mentioned economic-engineering approach. - Highlights: • We estimate the level of efficiency in the use of electricity by Swiss households. • We apply a non-radial input distance function and stochastic frontier methods. • We use data from two waves of a Swiss household survey conducted in 2005 and 2011. • We find an inefficiency in the use of electricity of around 20–25%.

  20. Studying the Efficiency of Industrial Dairy Farms of Saqqez and Divandarreh Cities: Using Super-Efficiency Approach

    Directory of Open Access Journals (Sweden)

    S.J. Mohammadi

    2016-03-01

    Full Text Available Introduction: In the developed world, particularly in developing countries, livestock is the most important agricultural sub-sector.Livestock of primary and secondary industries has an especial place in the national economybecause of their greatvalue of products, creating job opportunities, providing health products for consumers, increasing export income of the economy throughaccessing global markets of livestock products and finally their undeniable role in acquiring food security.The demand for milk in Iran increased due to an increase in population and the amount of milk production was also increased. The great share of increased produced milk goes to the industrial dairy farms. One of the major methods to increase the amount of milk production continually is to make its production efficient and improve economic conditions. The current study attempts to determine the efficiency and ranking of industrial dairy farms in Saqqez and Divandarreh cities using super-efficiency model. Materials and Methods: The statistical populations of the study are all active industrial dairy farms of Saqqez and Divandarreh cities which are about 19 farms. The required data for calculating the efficiency were gathered by surveying and completing questionnaires for the year 2013. In this study first, for each farm Data Envelopment Analysis (DEA method and GAMS software package were used to estimate super efficiency. Super efficiency is a form of modified DEA model in which each farm can get an efficiency greater than one. Then in order to make sure about being unbiased the obtained super-efficiency scores, the modified model of Banker and Gifford, was re-estimated and the conventional efficiency scores of farms were compared by normalizing and removing some of the scores of outlier farm based on pre-selected screens. The model has suggested conditions for which some of the estimates for dairy farms might have been contaminated with error.As a t result, it has been

  1. Efficient Levenberg-Marquardt minimization of the maximum likelihood estimator for Poisson deviates

    International Nuclear Information System (INIS)

    Laurence, T.; Chromy, B.

    2010-01-01

    Histograms of counted events are Poisson distributed, but are typically fitted without justification using nonlinear least squares fitting. The more appropriate maximum likelihood estimator (MLE) for Poisson distributed data is seldom used. We extend the use of the Levenberg-Marquardt algorithm commonly used for nonlinear least squares minimization for use with the MLE for Poisson distributed data. In so doing, we remove any excuse for not using this more appropriate MLE. We demonstrate the use of the algorithm and the superior performance of the MLE using simulations and experiments in the context of fluorescence lifetime imaging. Scientists commonly form histograms of counted events from their data, and extract parameters by fitting to a specified model. Assuming that the probability of occurrence for each bin is small, event counts in the histogram bins will be distributed according to the Poisson distribution. We develop here an efficient algorithm for fitting event counting histograms using the maximum likelihood estimator (MLE) for Poisson distributed data, rather than the non-linear least squares measure. This algorithm is a simple extension of the common Levenberg-Marquardt (L-M) algorithm, is simple to implement, quick and robust. Fitting using a least squares measure is most common, but it is the maximum likelihood estimator only for Gaussian-distributed data. Non-linear least squares methods may be applied to event counting histograms in cases where the number of events is very large, so that the Poisson distribution is well approximated by a Gaussian. However, it is not easy to satisfy this criterion in practice - which requires a large number of events. It has been well-known for years that least squares procedures lead to biased results when applied to Poisson-distributed data; a recent paper providing extensive characterization of these biases in exponential fitting is given. The more appropriate measure based on the maximum likelihood estimator (MLE

  2. A laboratory method to estimate the efficiency of plant extract to neutralize soil acidity

    Directory of Open Access Journals (Sweden)

    Marcelo E. Cassiolato

    2002-06-01

    Full Text Available Water-soluble plant organic compounds have been proposed to be efficient in alleviating soil acidity. Laboratory methods were evaluated to estimate the efficiency of plant extracts to neutralize soil acidity. Plant samples were dried at 65ºC for 48 h and ground to pass 1 mm sieve. Plant extraction procedure was: transfer 3.0 g of plant sample to a becker, add 150 ml of deionized water, shake for 8 h at 175 rpm and filter. Three laboratory methods were evaluated: sigma (Ca+Mg+K of the plant extracts; electrical conductivity of the plant extracts and titration of plant extracts with NaOH solution between pH 3 to 7. These methods were compared with the effect of the plant extracts on acid soil chemistry. All laboratory methods were related with soil reaction. Increasing sigma (Ca+Mg+K, electrical conductivity and the volume of NaOH solution spent to neutralize H+ ion of the plant extracts were correlated with the effect of plant extract on increasing soil pH and exchangeable Ca and decreasing exchangeable Al. It is proposed the electrical conductivity method for estimating the efficiency of plant extract to neutralize soil acidity because it is easily adapted for routine analysis and uses simple instrumentations and materials.Tem sido proposto que os compostos orgânicos de plantas solúveis em água são eficientes na amenização da acidez do solo. Foram avaliados métodos de laboratório para estimar a eficiência dos extratos de plantas na neutralização da acidez do solo. Os materiais de plantas foram secos a 65º C por 48 horas, moídos e passados em peneira de 1mm. Utilizou-se o seguinte procedimento para obtenção do extrato de plantas: transferir 3.0 g da amostra de planta para um becker, adicionar 150 ml de água deionizada, agitar por 8h a 175 rpm e filtrar. Avaliaram-se três métodos de laboratório: sigma (Ca + Mg + K do extrato de planta, condutividade elétrica (CE do extrato de planta e titulação do extrato de planta com solu

  3. Online wave estimation using vessel motion measurements

    DEFF Research Database (Denmark)

    H. Brodtkorb, Astrid; Nielsen, Ulrik D.; J. Sørensen, Asgeir

    2018-01-01

    parameters and motion transfer functions are required as input. Apart from this the method is signal-based, with no assumptions on the wave spectrum shape, and as a result it is computationally efficient. The algorithm is implemented in a dynamic positioning (DP)control system, and tested through simulations......In this paper, a computationally efficient online sea state estimation algorithm isproposed for estimation of the on site sea state. The algorithm finds the wave spectrum estimate from motion measurements in heave, roll and pitch by iteratively solving a set of linear equations. The main vessel...

  4. Proliferation assessment in breast carcinomas using digital image analysis based on virtual Ki67/cytokeratin double staining.

    Science.gov (United States)

    Røge, Rasmus; Riber-Hansen, Rikke; Nielsen, Søren; Vyberg, Mogens

    2016-07-01

    Manual estimation of Ki67 Proliferation Index (PI) in breast carcinoma classification is labor intensive and prone to intra- and interobserver variation. Standard Digital Image Analysis (DIA) has limitations due to issues with tumor cell identification. Recently, a computer algorithm, DIA based on Virtual Double Staining (VDS), segmenting Ki67-positive and -negative tumor cells using digitally fused parallel cytokeratin (CK) and Ki67-stained slides has been introduced. In this study, we compare VDS with manual stereological counting of Ki67-positive and -negative cells and examine the impact of the physical distance of the parallel slides on the alignment of slides. TMAs, containing 140 cores of consecutively obtained breast carcinomas, were stained for CK and Ki67 using optimized staining protocols. By means of stereological principles, Ki67-positive and -negative cell profiles were counted in sampled areas and used for the estimation of PIs of the whole tissue core. The VDS principle was applied to both the same sampled areas and the whole tissue core. Additionally, five neighboring slides were stained for CK in order to examine the alignment algorithm. Correlation between manual counting and VDS in both sampled areas and whole core was almost perfect (correlation coefficients above 0.97). Bland-Altman plots did not reveal any skewness in any data ranges. There was a good agreement in alignment (>85 %) in neighboring slides, whereas agreement decreased in non-neighboring slides. VDS gave similar results compared with manual counting using stereological principles. Introduction of this method in clinical and research practice may improve accuracy and reproducibility of Ki67 PI.

  5. Early behavioral changes and quantitative analysis of neuropathological features in murine prion disease

    Science.gov (United States)

    Borner, Roseane; Bento-Torres, João; Souza, Diego RV; Sadala, Danyelle B; Trevia, Nonata; Farias, José Augusto; Lins, Nara; Passos, Aline; Quintairos, Amanda; Diniz, José Antônio; Perry, Victor Hugh; Vasconcelos, Pedro Fernando; Cunningham, Colm

    2011-01-01

    Behavioral and neuropathological changes have been widely investigated in murine prion disease but stereological based unbiased estimates of key neuropathological features have not been carried out. After injections of ME7 infected (ME7) or normal brain homogenates (NBH) into dorsal CA1 of albino Swiss mice and C57BL6, we assessed behavioral changes on hippocampal-dependent tasks. We also estimated by optical fractionator at 15 and 18 weeks post-injections (w.p.i.) the total number of neurons, reactive astrocytes, activated microglia and perineuronal nets (PN) in the polymorphic layer of dentate gyrus (PolDG), CA1 and septum in albino Swiss mice. On average, early behavioral changes in albino Swiss mice start four weeks later than in C57BL6. Cluster and discriminant analysis of behavioral data in albino Swiss mice revealed that four of nine subjects start to change their behavior at 12 w.p.i. and reach terminal stage at 22 w.p.i and the remaining subjects start at 22 w.p.i. and reach terminal stage at 26 w.p.i. Biotinylated dextran-amine BDA-tracer experiments in mossy fiber pathway confirmed axonal degeneration and stereological data showed that early astrocytosis, microgliosis and reduction in the perineuronal nets are independent of a change in the number of neuronal cell bodies. Statistical analysis revealed that the septal region had greater levels of neuroinflammation and extracellular matrix damage than CA1. This stereological and multivariate analysis at early stages of disease in an outbred model of prion disease provided new insights connecting behavioral changes and neuroinflammation and seems to be important to understand the mechanisms of prion disease progression. PMID:21862877

  6. High-Level Design Space and Flexibility Exploration for Adaptive, Energy-Efficient WCDMA Channel Estimation Architectures

    Directory of Open Access Journals (Sweden)

    Zoltán Endre Rákossy

    2012-01-01

    Full Text Available Due to the fast changing wireless communication standards coupled with strict performance constraints, the demand for flexible yet high-performance architectures is increasing. To tackle the flexibility requirement, software-defined radio (SDR is emerging as an obvious solution, where the underlying hardware implementation is tuned via software layers to the varied standards depending on power-performance and quality requirements leading to adaptable, cognitive radio. In this paper, we conduct a case study for representatives of two complexity classes of WCDMA channel estimation algorithms and explore the effect of flexibility on energy efficiency using different implementation options. Furthermore, we propose new design guidelines for both highly specialized architectures and highly flexible architectures using high-level synthesis, to enable the required performance and flexibility to support multiple applications. Our experiments with various design points show that the resulting architectures meet the performance constraints of WCDMA and a wide range of options are offered for tuning such architectures depending on power/performance/area constraints of SDR.

  7. Validation of an efficient visual method for estimating leaf area index ...

    African Journals Online (AJOL)

    This study aimed to evaluate the accuracy and applicability of a visual method for estimating LAI in clonal Eucalyptus grandis × E. urophylla plantations and to compare it with hemispherical photography, ceptometer and LAI-2000® estimates. Destructive sampling for direct determination of the actual LAI was performed in ...

  8. 11 YEARS OF BIOSTEREOLOGY IN CHINA

    Directory of Open Access Journals (Sweden)

    Hong Shen

    2011-05-01

    Full Text Available Biostereology in China is very active. Here is a brief summary: Organization: The organization of biostereology in China was founded in Nov. 1988. Its name is Chinese Society of Biomedical Stereology (CSBS, and is affiliated to the Chinese Society for Stereology (CSS. The first joint president of CSS/BMC was Prof. Peixuan Tang, the second and now the third, is Prof. Dewen Wang. There are 556 registered members. Academic Congresses: Sessions of the National Biostereological Congress were convened in 1990, 1992, 1996 and 2000. Publications: Four works were written and published in China. One is "Quantitative Histology" (Luji Shi, 1964, another is "Stereological Morphometry For Cell Morphology" (Fusheng Zheng, 1990, the third one is "Practical Biostereological Techniques" (Hong Shen and Yingzhong Shen, 1991 and the fourth one is "Quantitative Cytology and Cytochemistry Techniques" (Genxing Xu, 1994. A Chinese Journal of Stereology and Image Analysis has been published since 1996. Courses: More than ten national training courses on biostereology were held. In some medical universities or colleges, a biostereology course has been set up. Theoretical studies: Some new concepts, parameters and methods for stereology and morphometry were put forward, such as: regular form factor, volume concavity, surface concavity, area concavity, boundary concavity, curve profile area density, positive university for immunohistochemistry stain etc. Application: Stereological methods have been widely applied in biomedical studies. The applied field covered most of the morphological domain of biology. The main applications of biostereology are quantitative pathological diagnosis and prognosis of tumor cells and histostructures. Most studies utilize classical stereological methods. New stereological methods should be popularized and applied in the future. Image Analysis System: Image analysis systems are widely used in biostereological studies. About ten kinds of image

  9. Estimation of Total Glomerular Number Using an Integrated Disector Method in Embryonic and Postnatal Kidneys

    Directory of Open Access Journals (Sweden)

    Michel G Arsenault

    2014-06-01

    Full Text Available Congenital Anomalies of the Kidney and Urinary Tract (CAKUT are a polymorphic group of clinical disorders comprising the major cause of renal failure in children. Included within CAKUT is a wide spectrum of developmental malformations ranging from renal agenesis, renal hypoplasia and renal dysplasia (maldifferentiation of renal tissue, each characterized by varying deficits in nephron number. First presented in the Brenner Hypothesis, low congenital nephron endowment is becoming recognized as an antecedent cause of adult-onset hypertension, a leading cause of coronary heart disease, stroke, and renal failure in North America. Genetic mouse models of impaired nephrogenesis and nephron endowment provide a critical framework for understanding the origins of human kidney disease. Current methods to quantitate nephron number include (i acid maceration (ii estimation of nephron number from a small number of tissue sections (iii imaging modalities such as MRI and (iv the gold standard physical disector/fractionator method. Despite its accuracy, the physical disector/fractionator method is rarely employed because it is labour-intensive, time-consuming and costly to perform. Consequently, less rigourous methods of nephron estimation are routinely employed by many laboratories. Here we present an updated, digitized version of the physical disector/fractionator method using free open source Fiji software, which we have termed the integrated disector method. This updated version of the gold standard modality accurately, rapidly and cost-effectively quantitates nephron number in embryonic and post-natal mouse kidneys, and can be easily adapted for stereological measurements in other organ systems.

  10. Estimating Function Approaches for Spatial Point Processes

    Science.gov (United States)

    Deng, Chong

    Spatial point pattern data consist of locations of events that are often of interest in biological and ecological studies. Such data are commonly viewed as a realization from a stochastic process called spatial point process. To fit a parametric spatial point process model to such data, likelihood-based methods have been widely studied. However, while maximum likelihood estimation is often too computationally intensive for Cox and cluster processes, pairwise likelihood methods such as composite likelihood, Palm likelihood usually suffer from the loss of information due to the ignorance of correlation among pairs. For many types of correlated data other than spatial point processes, when likelihood-based approaches are not desirable, estimating functions have been widely used for model fitting. In this dissertation, we explore the estimating function approaches for fitting spatial point process models. These approaches, which are based on the asymptotic optimal estimating function theories, can be used to incorporate the correlation among data and yield more efficient estimators. We conducted a series of studies to demonstrate that these estmating function approaches are good alternatives to balance the trade-off between computation complexity and estimating efficiency. First, we propose a new estimating procedure that improves the efficiency of pairwise composite likelihood method in estimating clustering parameters. Our approach combines estimating functions derived from pairwise composite likeli-hood estimation and estimating functions that account for correlations among the pairwise contributions. Our method can be used to fit a variety of parametric spatial point process models and can yield more efficient estimators for the clustering parameters than pairwise composite likelihood estimation. We demonstrate its efficacy through a simulation study and an application to the longleaf pine data. Second, we further explore the quasi-likelihood approach on fitting

  11. Regional and global exergy and energy efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Nakicenovic, N; Kurz, R [International Inst. for Applied Systems Analysis, Laxenburg (Austria). Environmentally Compatible Energy Strategies (Ecuador) Project; Gilli, P V [Graz Univ. of Technology (Austria)

    1996-03-01

    We present estimates of global energy efficiency by applying second-law (exergy) analysis to regional and global energy balances. We use a uniform analysis of national and regional energy balances and aggregate these balances first for three main economic regions and subsequently into world totals. The procedure involves assessment of energy and exergy efficiencies at each step of energy conversion, from primary exergy to final and useful exergy. Ideally, the analysis should be extended to include actual delivered energy services; unfortunately, data are scarce and only rough estimates can be given for this last stage of energy conversion. The overall result is that the current global primary to useful exergy efficiency is about one-tenth of the theoretical maximum and the service efficiency is even lower. (Author)

  12. Doubly Robust Estimation of Optimal Dynamic Treatment Regimes

    DEFF Research Database (Denmark)

    Barrett, Jessica K; Henderson, Robin; Rosthøj, Susanne

    2014-01-01

    We compare methods for estimating optimal dynamic decision rules from observational data, with particular focus on estimating the regret functions defined by Murphy (in J. R. Stat. Soc., Ser. B, Stat. Methodol. 65:331-355, 2003). We formulate a doubly robust version of the regret-regression appro......We compare methods for estimating optimal dynamic decision rules from observational data, with particular focus on estimating the regret functions defined by Murphy (in J. R. Stat. Soc., Ser. B, Stat. Methodol. 65:331-355, 2003). We formulate a doubly robust version of the regret......-regression approach of Almirall et al. (in Biometrics 66:131-139, 2010) and Henderson et al. (in Biometrics 66:1192-1201, 2010) and demonstrate that it is equivalent to a reduced form of Robins' efficient g-estimation procedure (Robins, in Proceedings of the Second Symposium on Biostatistics. Springer, New York, pp....... 189-326, 2004). Simulation studies suggest that while the regret-regression approach is most efficient when there is no model misspecification, in the presence of misspecification the efficient g-estimation procedure is more robust. The g-estimation method can be difficult to apply in complex...

  13. Measuring economy-wide energy efficiency performance: A parametric frontier approach

    International Nuclear Information System (INIS)

    Zhou, P.; Ang, B.W.; Zhou, D.Q.

    2012-01-01

    This paper proposes a parametric frontier approach to estimating economy-wide energy efficiency performance from a production efficiency point of view. It uses the Shephard energy distance function to define an energy efficiency index and adopts the stochastic frontier analysis technique to estimate the index. A case study of measuring the economy-wide energy efficiency performance of a sample of OECD countries using the proposed approach is presented. It is found that the proposed parametric frontier approach has higher discriminating power in energy efficiency performance measurement compared to its nonparametric frontier counterparts.

  14. Efficiency in the Community College Sector: Stochastic Frontier Analysis

    Science.gov (United States)

    Agasisti, Tommaso; Belfield, Clive

    2017-01-01

    This paper estimates technical efficiency scores across the community college sector in the United States. Using stochastic frontier analysis and data from the Integrated Postsecondary Education Data System for 2003-2010, we estimate efficiency scores for 950 community colleges and perform a series of sensitivity tests to check for robustness. We…

  15. The Efficiency of OLS Estimators of Structural Parameters in a Simple Linear Regression Model in the Calibration of the Averages Scheme

    Directory of Open Access Journals (Sweden)

    Kowal Robert

    2016-12-01

    Full Text Available A simple linear regression model is one of the pillars of classic econometrics. Multiple areas of research function within its scope. One of the many fundamental questions in the model concerns proving the efficiency of the most commonly used OLS estimators and examining their properties. In the literature of the subject one can find taking back to this scope and certain solutions in that regard. Methodically, they are borrowed from the multiple regression model or also from a boundary partial model. Not everything, however, is here complete and consistent. In the paper a completely new scheme is proposed, based on the implementation of the Cauchy-Schwarz inequality in the arrangement of the constraint aggregated from calibrated appropriately secondary constraints of unbiasedness which in a result of choice the appropriate calibrator for each variable directly leads to showing this property. A separate range-is a matter of choice of such a calibrator. These deliberations, on account of the volume and kinds of the calibration, were divided into a few parts. In the one the efficiency of OLS estimators is proven in a mixed scheme of the calibration by averages, that is preliminary, and in the most basic frames of the proposed methodology. In these frames the future outlines and general premises constituting the base of more distant generalizations are being created.

  16. Methodical Approach to Estimation of Energy Efficiency Parameters of the Economy Under the Structural Changes in the Fuel And Energy Balance (on the Example of Baikal Region

    Directory of Open Access Journals (Sweden)

    Boris Grigorievich Saneev

    2013-12-01

    Full Text Available The authors consider a methodical approach which allows estimating energy efficiency parameters of the region’s economy using a fuel and energy balance (FEB. This approach was tested on the specific case of Baikal region. During the testing process the authors have developed ex ante and ex post FEBs and estimated energy efficiency parameters such as energy-, electro- and heat capacity of GRP, coefficients of useful utilization of fuel and energy resources and a monetary version of FEB. Forecast estimations are based on assumptions and limitations of technologically-intensive development scenario of the region. Authors show that the main factor of structural changes in the fuel and energy balance will be the large-scale development of hydrocarbon resources in Baikal region. It will cause structural changes in the composition of both the debit and credit of FEB (namely the structure of export and final consumption of fuel and energy resources. Authors assume that the forecast structural changes of the region’s FEB will significantly improve energy efficiency parameters of the economy: energy capacity of GRP will decrease by 1,5 times in 2010– 2030, electro and heat capacity – 1,9 times; coefficients of useful utilization of fuel and energy resources will increase by 3–5 p.p. This will save about 20 million tons of fuel equivalent (about 210 billion rubles in 2011 the prices until 2030

  17. The exogenous factors affecting the cost efficiency of power generation

    International Nuclear Information System (INIS)

    Chang, D.-S.; Chen, Y.-T.; Chen, W.-D.

    2009-01-01

    This paper employs a stochastic frontier analysis (SFA) to examine cost efficiency and scale economies in Taiwan Power Company (TPC) by using the panel data covering the period of 1995-2006. In most previous studies, the efficiency estimated by the Panel Data without testing the endogeneity may bring about a biased estimator resulting from the correlation between input and individual effect. A Hausman test is conducted in this paper to examine the endogeneity of input variables and thus an appropriate model is selected based on the test result. This study finds that the power generation executes an increasing return to scale across all the power plants based on the pooled data. We also use installed capacity, service years of the power plant, and type of fuel as explanatory variable for accounting for the estimated cost efficiency of each plant by a logistic regression model to examine the factor affecting the individual efficiency estimates. The results demonstrate that the variable of installed capacity keeps a positive relationship with cost efficiency while the factor of working years has a negative relationship.

  18. Energy-efficient cooking methods

    Energy Technology Data Exchange (ETDEWEB)

    De, Dilip K. [Department of Physics, University of Jos, P.M.B. 2084, Jos, Plateau State (Nigeria); Muwa Shawhatsu, N. [Department of Physics, Federal University of Technology, Yola, P.M.B. 2076, Yola, Adamawa State (Nigeria); De, N.N. [Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX 76019 (United States); Ikechukwu Ajaeroh, M. [Department of Physics, University of Abuja, Abuja (Nigeria)

    2013-02-15

    Energy-efficient new cooking techniques have been developed in this research. Using a stove with 649{+-}20 W of power, the minimum heat, specific heat of transformation, and on-stove time required to completely cook 1 kg of dry beans (with water and other ingredients) and 1 kg of raw potato are found to be: 710 {+-}kJ, 613 {+-}kJ, and 1,144{+-}10 s, respectively, for beans and 287{+-}12 kJ, 200{+-}9 kJ, and 466{+-}10 s for Irish potato. Extensive researches show that these figures are, to date, the lowest amount of heat ever used to cook beans and potato and less than half the energy used in conventional cooking with a pressure cooker. The efficiency of the stove was estimated to be 52.5{+-}2 %. Discussion is made to further improve the efficiency in cooking with normal stove and solar cooker and to save food nutrients further. Our method of cooking when applied globally is expected to contribute to the clean development management (CDM) potential. The approximate values of the minimum and maximum CDM potentials are estimated to be 7.5 x 10{sup 11} and 2.2 x 10{sup 13} kg of carbon credit annually. The precise estimation CDM potential of our cooking method will be reported later.

  19. A hydrogen production experiment by the thermo-chemical and electrolytic hybrid hydrogen production in lower temperature range. System viability and preliminary thermal efficiency estimation

    International Nuclear Information System (INIS)

    Takai, Toshihide; Nakagiri, Toshio; Inagaki, Yoshiyuki

    2008-10-01

    A new experimental apparatus by the thermo-chemical and electrolytic Hybrid-Hydrogen production in Lower Temperature range (HHLT) was developed and hydrogen production experiment was performed to confirm the system operability. Hydrogen production efficiency was estimated and technical problems were clarified through the experimental results. Stable operation of the SO 3 electrolysis cell and the sulfur dioxide solution electrolysis cell were confirmed during experimental operation and any damage which would be affected solid operation was not detected under post operation inspection. To improve hydrogen production efficiency, it was found that the reduction of sulfuric acid circulation and the decrease in the cell voltage were key issues. (author)

  20. Application of computer simulation in the stereology of materials

    Czech Academy of Sciences Publication Activity Database

    Saxl, Ivan; Ponížil, P.; Löflerová, M.

    2009-01-01

    Roč. 4, č. 2 (2009), s. 231-249 ISSN 1741-8410 R&D Projects: GA ČR GA201/06/0302 Grant - others:GA ČR(CZ) GA106/05/0550 Institutional research plan: CEZ:AV0Z10190503 Keywords : 3D computer simulation * fibre anisotropy * fracture surface * grain size estimation * random tessellation * rough surface analysis * fibre processes Subject RIV: BA - General Mathematics

  1. Distributed fusion estimation for sensor networks with communication constraints

    CERN Document Server

    Zhang, Wen-An; Song, Haiyu; Yu, Li

    2016-01-01

    This book systematically presents energy-efficient robust fusion estimation methods to achieve thorough and comprehensive results in the context of network-based fusion estimation. It summarizes recent findings on fusion estimation with communication constraints; several novel energy-efficient and robust design methods for dealing with energy constraints and network-induced uncertainties are presented, such as delays, packet losses, and asynchronous information... All the results are presented as algorithms, which are convenient for practical applications.

  2. Coordination of Energy Efficiency and Demand Response

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Charles; Reid, Michael; Levy, Roger; Silverstein, Alison

    2010-01-29

    This paper reviews the relationship between energy efficiency and demand response and discusses approaches and barriers to coordinating energy efficiency and demand response. The paper is intended to support the 10 implementation goals of the National Action Plan for Energy Efficiency's Vision to achieve all cost-effective energy efficiency by 2025. Improving energy efficiency in our homes, businesses, schools, governments, and industries - which consume more than 70 percent of the nation's natural gas and electricity - is one of the most constructive, cost-effective ways to address the challenges of high energy prices, energy security and independence, air pollution, and global climate change. While energy efficiency is an increasingly prominent component of efforts to supply affordable, reliable, secure, and clean electric power, demand response is becoming a valuable tool in utility and regional resource plans. The Federal Energy Regulatory Commission (FERC) estimated the contribution from existing U.S. demand response resources at about 41,000 megawatts (MW), about 5.8 percent of 2008 summer peak demand (FERC, 2008). Moreover, FERC recently estimated nationwide achievable demand response potential at 138,000 MW (14 percent of peak demand) by 2019 (FERC, 2009).2 A recent Electric Power Research Institute study estimates that 'the combination of demand response and energy efficiency programs has the potential to reduce non-coincident summer peak demand by 157 GW' by 2030, or 14-20 percent below projected levels (EPRI, 2009a). This paper supports the Action Plan's effort to coordinate energy efficiency and demand response programs to maximize value to customers. For information on the full suite of policy and programmatic options for removing barriers to energy efficiency, see the Vision for 2025 and the various other Action Plan papers and guides available at www.epa.gov/eeactionplan.

  3. Oil pipeline energy consumption and efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Hooker, J.N.

    1981-01-01

    This report describes an investigation of energy consumption and efficiency of oil pipelines in the US in 1978. It is based on a simulation of the actual movement of oil on a very detailed representation of the pipeline network, and it uses engineering equations to calculate the energy that pipeline pumps must have exerted on the oil to move it in this manner. The efficiencies of pumps and drivers are estimated so as to arrive at the amount of energy consumed at pumping stations. The throughput in each pipeline segment is estimated by distributing each pipeline company's reported oil movements over its segments in proportions predicted by regression equations that show typical throughput and throughput capacity as functions of pipe diameter. The form of the equations is justified by a generalized cost-engineering study of pipelining, and their parameters are estimated using new techniques developed for the purpose. A simplified model of flow scheduling is chosen on the basis of actual energy use data obtained from a few companies. The study yields energy consumption and intensiveness estimates for crude oil trunk lines, crude oil gathering lines and oil products lines, for the nation as well as by state and by pipe diameter. It characterizes the efficiency of typical pipelines of various diameters operating at capacity. Ancillary results include estimates of oil movements by state and by diameter and approximate pipeline capacity utilization nationwide.

  4. Efficiency of Finish power transmission network companies

    International Nuclear Information System (INIS)

    Anon.

    2001-01-01

    The Finnish Energy Market Authority has investigated the efficiency of power transmissions network companies. The results show that the intensification potential of the branch is 402 million FIM, corresponding to about 15% of the total costs of the branch and 7.3 % of the turnout. Energy Market Authority supervises the reasonableness of the power transmission prices, and it will use the results of the research in supervision. The research was carried out by the Quantitative Methods Research Group of Helsinki School of Economics. The main objective of the research was to create an efficiency estimation method for electric power distribution network business used for Finnish conditions. Data of the year 1998 was used as basic material in the research. Twenty-one of the 102 power distribution network operators was estimated to be totally efficient. Highest possible efficiency rate was 100, and the average of the efficiency rates of all the operators was 76.9, the minimum being 42.6

  5. Sampling strategies for efficient estimation of tree foliage biomass

    Science.gov (United States)

    Hailemariam Temesgen; Vicente Monleon; Aaron Weiskittel; Duncan Wilson

    2011-01-01

    Conifer crowns can be highly variable both within and between trees, particularly with respect to foliage biomass and leaf area. A variety of sampling schemes have been used to estimate biomass and leaf area at the individual tree and stand scales. Rarely has the effectiveness of these sampling schemes been compared across stands or even across species. In addition,...

  6. Optimizing lengths of confidence intervals: fourth-order efficiency in location models

    NARCIS (Netherlands)

    Klaassen, C.; Venetiaan, S.

    2010-01-01

    Under regularity conditions the maximum likelihood estimator of the location parameter in a location model is asymptotically efficient among translation equivariant estimators. Additional regularity conditions warrant third- and even fourth-order efficiency, in the sense that no translation

  7. Sequential bayes estimation algorithm with cubic splines on uniform meshes

    International Nuclear Information System (INIS)

    Hossfeld, F.; Mika, K.; Plesser-Walk, E.

    1975-11-01

    After outlining the principles of some recent developments in parameter estimation, a sequential numerical algorithm for generalized curve-fitting applications is presented combining results from statistical estimation concepts and spline analysis. Due to its recursive nature, the algorithm can be used most efficiently in online experimentation. Using computer-sumulated and experimental data, the efficiency and the flexibility of this sequential estimation procedure is extensively demonstrated. (orig.) [de

  8. Valid and efficient manual estimates of intracranial volume from magnetic resonance images

    International Nuclear Information System (INIS)

    Klasson, Niklas; Olsson, Erik; Rudemo, Mats; Eckerström, Carl; Malmgren, Helge; Wallin, Anders

    2015-01-01

    Manual segmentations of the whole intracranial vault in high-resolution magnetic resonance images are often regarded as very time-consuming. Therefore it is common to only segment a few linearly spaced intracranial areas to estimate the whole volume. The purpose of the present study was to evaluate how the validity of intracranial volume estimates is affected by the chosen interpolation method, orientation of the intracranial areas and the linear spacing between them. Intracranial volumes were manually segmented on 62 participants from the Gothenburg MCI study using 1.5 T, T 1 -weighted magnetic resonance images. Estimates of the intracranial volumes were then derived using subsamples of linearly spaced coronal, sagittal or transversal intracranial areas from the same volumes. The subsamples of intracranial areas were interpolated into volume estimates by three different interpolation methods. The linear spacing between the intracranial areas ranged from 2 to 50 mm and the validity of the estimates was determined by comparison with the entire intracranial volumes. A progressive decrease in intra-class correlation and an increase in percentage error could be seen with increased linear spacing between intracranial areas. With small linear spacing (≤15 mm), orientation of the intracranial areas and interpolation method had negligible effects on the validity. With larger linear spacing, the best validity was achieved using cubic spline interpolation with either coronal or sagittal intracranial areas. Even at a linear spacing of 50 mm, cubic spline interpolation on either coronal or sagittal intracranial areas had a mean absolute agreement intra-class correlation with the entire intracranial volumes above 0.97. Cubic spline interpolation in combination with linearly spaced sagittal or coronal intracranial areas overall resulted in the most valid and robust estimates of intracranial volume. Using this method, valid ICV estimates could be obtained in less than five

  9. Assessment of the achieved savings from induction motors energy efficiency labeling in Brazil

    International Nuclear Information System (INIS)

    Bortoni, E.C.; Nogueira, L.A.H.; Cardoso, R.B.; Haddad, J.; Souza, E.P.; Dias, M.V.X.; Yamachita, R.A.

    2013-01-01

    Highlights: • We have modeled the influence of the increase of efficiency of motors. • The amount of saved energy is estimated. • The work deals with the “measurement” of a non-consumed energy. • The influence of the motor useful life is taken into account. • The influence of efficiency decrease along the motor life is also taken into account. - Abstract: Since 1995 Brazil has been applying its labeling program to increase the efficiency of application of many household appliances and equipment. From 2003 on inductions motors have also been receiving the PROCEL prize, which helped push motors efficiency over than those limits established by the labeling program. Therefore, this work presents the development of a model to estimate the amount of savings obtained with the usage of the PROCEL endorsement labels in standard and in energy efficient motors. The estimated peak demand reduction is also inferred. The developed model makes the usage of sales information and of a discard function to estimate the Brazilian motor stock. Approaches such as the use of efficiency loading and efficiency aging factors are employed to estimate motors consumption

  10.  Higher Order Improvements for Approximate Estimators

    DEFF Research Database (Denmark)

    Kristensen, Dennis; Salanié, Bernard

    Many modern estimation methods in econometrics approximate an objective function, through simulation or discretization for instance. The resulting "approximate" estimator is often biased; and it always incurs an efficiency loss. We here propose three methods to improve the properties of such appr......Many modern estimation methods in econometrics approximate an objective function, through simulation or discretization for instance. The resulting "approximate" estimator is often biased; and it always incurs an efficiency loss. We here propose three methods to improve the properties...... of such approximate estimators at a low computational cost. The first two methods correct the objective function so as to remove the leading term of the bias due to the approximation. One variant provides an analytical bias adjustment, but it only works for estimators based on stochastic approximators......, such as simulation-based estimators. Our second bias correction is based on ideas from the resampling literature; it eliminates the leading bias term for non-stochastic as well as stochastic approximators. Finally, we propose an iterative procedure where we use Newton-Raphson (NR) iterations based on a much finer...

  11. Estimation of Economic Efficiency of Regional Touristic Complex

    Directory of Open Access Journals (Sweden)

    Kurchenkov Vladimir Viktorovich

    2015-09-01

    Full Text Available The article describes the features of the development of the regional touristic complex in modern conditions and determines the direction of realizing the potential of the regional market of tourist services. The authors reveal the multiplicative interrelation for analyzing the interaction of the primary and secondary sectors of the regional market of tourist services. The key indicators of efficiency are outlined, the extent of their relevance for assessing the potential of international tourism in the region is revealed. The authors calculate the relative indicators reflecting the dynamics of incomes from inbound, outbound and domestic tourism in relation to the total income from tourism activities in the region during the reporting period, usually for one calendar year. On the basis of these parameters, the classification of the regions of the Southern Federal District in terms of tourist attraction is carried out. The authors determine the reasons of the low tourist attractiveness of the Volgograd region in comparison with other regions of the Southern Federal District. It is substantiated that the potential of expanding tourism activity is not fully realized today in the Volgograd region. The technique of analysis and evaluation of the effectiveness of regional touristic complex on the basis of cluster approach is suggested. For analyzing the effectiveness of regional tourism cluster the authors propose to use indicators that reflect the overall performance of the regional tourism cluster, characterizing the impact of cluster development of the area, or the regional market, as well as evaluating the performance of each of the companies cooperating in the framework of the cluster. The article contains recommendations to the regional authorities on improving the efficiency of regional touristic complex in the short- and long-term prospects.

  12. What is the most efficient respiratory organ for the loricariid air-breathing fish Pterygoplichthys anisitsi, gills or stomach? A quantitative morphological study.

    Science.gov (United States)

    da Cruz, André Luis; Fernandes, Marisa Narciso

    2016-12-01

    The purpose of the present study was to evaluate the morphometric respiratory potential of gills compared to the stomach in obtaining oxygen for aerobic metabolism in Pterygoplichthys anisitsi, a facultative air-breathing fish. The measurements were done using stereological methods. The gills showed greater total volume, volume-to-body mass ratio, potential surface area, and surface-to-volume ratio than the stomach. The water-blood diffusion barrier of the gills is thicker than the air-blood diffusion barrier of the stomach. Taken together, the surface area, the surface-to-volume ratio and the diffusion distance for O 2 transfer from the respiratory medium to blood yield a greater diffusing capacity for gills than for the stomach, suggesting greater importance of aquatic respiration in this species. On the other hand, water breathing is energetically more expensive than breathing air. Under severe hypoxic conditions, O 2 uptake by the stomach is more efficient than by the gills, although the stomach has a much lower diffusing capacity. Thus, P. anisitsi uses gills under normoxic conditions but the stomach may also support aerobic metabolism depending on environmental conditions. Copyright © 2016 Elsevier GmbH. All rights reserved.

  13. A bias correction for covariance estimators to improve inference with generalized estimating equations that use an unstructured correlation matrix.

    Science.gov (United States)

    Westgate, Philip M

    2013-07-20

    Generalized estimating equations (GEEs) are routinely used for the marginal analysis of correlated data. The efficiency of GEE depends on how closely the working covariance structure resembles the true structure, and therefore accurate modeling of the working correlation of the data is important. A popular approach is the use of an unstructured working correlation matrix, as it is not as restrictive as simpler structures such as exchangeable and AR-1 and thus can theoretically improve efficiency. However, because of the potential for having to estimate a large number of correlation parameters, variances of regression parameter estimates can be larger than theoretically expected when utilizing the unstructured working correlation matrix. Therefore, standard error estimates can be negatively biased. To account for this additional finite-sample variability, we derive a bias correction that can be applied to typical estimators of the covariance matrix of parameter estimates. Via simulation and in application to a longitudinal study, we show that our proposed correction improves standard error estimation and statistical inference. Copyright © 2012 John Wiley & Sons, Ltd.

  14. Motor-operated gearbox efficiency

    International Nuclear Information System (INIS)

    DeWall, K.G.; Watkins, J.C.; Bramwell, D.; Weidenhamer, G.H.

    1996-01-01

    Researchers at the Idaho National Engineering Laboratory recently conducted tests investigating the operating efficiency of the power train (gearbox) in motor-operators typically used in nuclear power plants to power motor-operated valves. Actual efficiency ratios were determined from in-line measurements of electric motor torque (input to the operator gearbox) and valve stem torque (output from the gearbox) while the operators were subjected to gradually increasing loads until the electric motor stalled. The testing included parametric studies under reduced voltage and elevated temperature conditions. As part of the analysis of the results, the authors compared efficiency values determined from testing to the values published by the operator manufacturer and typically used by the industry in calculations for estimating motor-operator capabilities. The operators they tested under load ran at efficiencies lower than the running efficiency (typically 50%) published by the operator manufacturer

  15. Motor-operated gearbox efficiency

    Energy Technology Data Exchange (ETDEWEB)

    DeWall, K.G.; Watkins, J.C.; Bramwell, D. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Weidenhamer, G.H.

    1996-12-01

    Researchers at the Idaho National Engineering Laboratory recently conducted tests investigating the operating efficiency of the power train (gearbox) in motor-operators typically used in nuclear power plants to power motor-operated valves. Actual efficiency ratios were determined from in-line measurements of electric motor torque (input to the operator gearbox) and valve stem torque (output from the gearbox) while the operators were subjected to gradually increasing loads until the electric motor stalled. The testing included parametric studies under reduced voltage and elevated temperature conditions. As part of the analysis of the results, the authors compared efficiency values determined from testing to the values published by the operator manufacturer and typically used by the industry in calculations for estimating motor-operator capabilities. The operators they tested under load ran at efficiencies lower than the running efficiency (typically 50%) published by the operator manufacturer.

  16. Motor-operator gearbox efficiency

    International Nuclear Information System (INIS)

    DeWall, K.G.; Watkins, J.C.; Bramwell, D.

    1996-01-01

    Researchers at the Idaho National Engineering Laboratory recently conducted tests investigating the operating efficiency of the power train (gearbox) in motor-operators typically used in nuclear power plants to power motor-operated valves. Actual efficiency ratios were determined from in-line measurements of electric motor torque (input to the operator gearbox) and valve stem torque (output from the gearbox) while the operators were subjected to gradually increasing loads until the electric motor stalled. The testing included parametric studies under reduced voltage and elevated temperature conditions. As part of the analysis of the results, we compared efficiency values determined from testing to the values published by the operator manufacturer and typically used by the industry in calculations for estimating motor-operator capabilities. The operators we tested under load ran at efficiencies lower than the running efficiency (typically 50%) published by the operator manufacturer

  17. Efficient Bayesian parameter estimation with implicit sampling and surrogate modeling for a vadose zone hydrological problem

    Science.gov (United States)

    Liu, Y.; Pau, G. S. H.; Finsterle, S.

    2015-12-01

    Parameter inversion involves inferring the model parameter values based on sparse observations of some observables. To infer the posterior probability distributions of the parameters, Markov chain Monte Carlo (MCMC) methods are typically used. However, the large number of forward simulations needed and limited computational resources limit the complexity of the hydrological model we can use in these methods. In view of this, we studied the implicit sampling (IS) method, an efficient importance sampling technique that generates samples in the high-probability region of the posterior distribution and thus reduces the number of forward simulations that we need to run. For a pilot-point inversion of a heterogeneous permeability field based on a synthetic ponded infiltration experiment simu­lated with TOUGH2 (a subsurface modeling code), we showed that IS with linear map provides an accurate Bayesian description of the parameterized permeability field at the pilot points with just approximately 500 forward simulations. We further studied the use of surrogate models to improve the computational efficiency of parameter inversion. We implemented two reduced-order models (ROMs) for the TOUGH2 forward model. One is based on polynomial chaos expansion (PCE), of which the coefficients are obtained using the sparse Bayesian learning technique to mitigate the "curse of dimensionality" of the PCE terms. The other model is Gaussian process regression (GPR) for which different covariance, likelihood and inference models are considered. Preliminary results indicate that ROMs constructed based on the prior parameter space perform poorly. It is thus impractical to replace this hydrological model by a ROM directly in a MCMC method. However, the IS method can work with a ROM constructed for parameters in the close vicinity of the maximum a posteriori probability (MAP) estimate. We will discuss the accuracy and computational efficiency of using ROMs in the implicit sampling procedure

  18. A logistic regression estimating function for spatial Gibbs point processes

    DEFF Research Database (Denmark)

    Baddeley, Adrian; Coeurjolly, Jean-François; Rubak, Ege

    We propose a computationally efficient logistic regression estimating function for spatial Gibbs point processes. The sample points for the logistic regression consist of the observed point pattern together with a random pattern of dummy points. The estimating function is closely related to the p......We propose a computationally efficient logistic regression estimating function for spatial Gibbs point processes. The sample points for the logistic regression consist of the observed point pattern together with a random pattern of dummy points. The estimating function is closely related...

  19. EPA’s Travel Efficiency Method (TEAM) AMPO Presentation

    Science.gov (United States)

    Presentation describes EPA’s Travel Efficiency Assessment Method (TEAM) assessing potential travel efficiency strategies for reducing travel activity and emissions, includes reduction estimates in Vehicle Miles Traveled in four different geographic areas.

  20. An adaptive hybrid EnKF-OI scheme for efficient state-parameter estimation of reactive contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad; Valstar, Johan R.; Hoteit, Ibrahim

    2014-01-01

    Reactive contaminant transport models are used by hydrologists to simulate and study the migration and fate of industrial waste in subsurface aquifers. Accurate transport modeling of such waste requires clear understanding of the system's parameters, such as sorption and biodegradation. In this study, we present an efficient sequential data assimilation scheme that computes accurate estimates of aquifer contamination and spatially variable sorption coefficients. This assimilation scheme is based on a hybrid formulation of the ensemble Kalman filter (EnKF) and optimal interpolation (OI) in which solute concentration measurements are assimilated via a recursive dual estimation of sorption coefficients and contaminant state variables. This hybrid EnKF-OI scheme is used to mitigate background covariance limitations due to ensemble under-sampling and neglected model errors. Numerical experiments are conducted with a two-dimensional synthetic aquifer in which cobalt-60, a radioactive contaminant, is leached in a saturated heterogeneous clayey sandstone zone. Assimilation experiments are investigated under different settings and sources of model and observational errors. Simulation results demonstrate that the proposed hybrid EnKF-OI scheme successfully recovers both the contaminant and the sorption rate and reduces their uncertainties. Sensitivity analyses also suggest that the adaptive hybrid scheme remains effective with small ensembles, allowing to reduce the ensemble size by up to 80% with respect to the standard EnKF scheme. © 2014 Elsevier Ltd.

  1. An adaptive hybrid EnKF-OI scheme for efficient state-parameter estimation of reactive contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad

    2014-09-01

    Reactive contaminant transport models are used by hydrologists to simulate and study the migration and fate of industrial waste in subsurface aquifers. Accurate transport modeling of such waste requires clear understanding of the system\\'s parameters, such as sorption and biodegradation. In this study, we present an efficient sequential data assimilation scheme that computes accurate estimates of aquifer contamination and spatially variable sorption coefficients. This assimilation scheme is based on a hybrid formulation of the ensemble Kalman filter (EnKF) and optimal interpolation (OI) in which solute concentration measurements are assimilated via a recursive dual estimation of sorption coefficients and contaminant state variables. This hybrid EnKF-OI scheme is used to mitigate background covariance limitations due to ensemble under-sampling and neglected model errors. Numerical experiments are conducted with a two-dimensional synthetic aquifer in which cobalt-60, a radioactive contaminant, is leached in a saturated heterogeneous clayey sandstone zone. Assimilation experiments are investigated under different settings and sources of model and observational errors. Simulation results demonstrate that the proposed hybrid EnKF-OI scheme successfully recovers both the contaminant and the sorption rate and reduces their uncertainties. Sensitivity analyses also suggest that the adaptive hybrid scheme remains effective with small ensembles, allowing to reduce the ensemble size by up to 80% with respect to the standard EnKF scheme. © 2014 Elsevier Ltd.

  2. Quantitative Measurements in the Human Hippocampus and Related Areas: Correspondence between Ex-Vivo MRI and Histological Preparations.

    Directory of Open Access Journals (Sweden)

    José Carlos Delgado-González

    Full Text Available The decrease of volume estimates in different structures of the medial temporal lobe related to memory correlate with the decline of cognitive functions in neurodegenerative diseases. This study presents data on the association between MRI quantitative parameters of medial temporal lobe structures and their quantitative estimate in microscopic examination. Twelve control cases had ex-vivo MRI, and thereafter, the temporal lobe of both hemispheres was sectioned from the pole as far as the level of the splenium of the corpus callosum. Nissl stain was used to establish anatomical boundaries between structures in the medial temporal lobe. The study included morphometrical and stereological estimates of the amygdaloid complex, hippocampus, and temporal horn of the lateral ventricle, as well as different regions of grey and white matter in the temporal lobe. Data showed a close association between morphometric MRI images values and those based on the histological determination of boundaries. Only values in perimeter and circularity of the piamater were different. This correspondence is also revealed by the stereological study, although irregular compartments resulted in a lesser agreement. Neither age ( 65 yr nor hemisphere had any effect. Our results indicate that ex-vivo MRI is highly associated with quantitative information gathered by histological examination, and these data could be used as structural MRI biomarker in neurodegenerative diseases.

  3. Energy Efficiency - Spectral Efficiency Trade-off: A Multiobjective Optimization Approach

    KAUST Repository

    Amin, Osama

    2015-04-23

    In this paper, we consider the resource allocation problem for energy efficiency (EE) - spectral efficiency (SE) trade-off. Unlike traditional research that uses the EE as an objective function and imposes constraints either on the SE or achievable rate, we propound a multiobjective optimization approach that can flexibly switch between the EE and SE functions or change the priority level of each function using a trade-off parameter. Our dynamic approach is more tractable than the conventional approaches and more convenient to realistic communication applications and scenarios. We prove that the multiobjective optimization of the EE and SE is equivalent to a simple problem that maximizes the achievable rate/SE and minimizes the total power consumption. Then we apply the generalized framework of the resource allocation for the EE-SE trade-off to optimally allocate the subcarriers’ power for orthogonal frequency division multiplexing (OFDM) with imperfect channel estimation. Finally, we use numerical results to discuss the choice of the trade-off parameter and study the effect of the estimation error, transmission power budget and channel-to-noise ratio on the multiobjective optimization.

  4. Energy Efficiency - Spectral Efficiency Trade-off: A Multiobjective Optimization Approach

    KAUST Repository

    Amin, Osama; Bedeer, Ebrahim; Ahmed, Mohamed; Dobre, Octavia

    2015-01-01

    In this paper, we consider the resource allocation problem for energy efficiency (EE) - spectral efficiency (SE) trade-off. Unlike traditional research that uses the EE as an objective function and imposes constraints either on the SE or achievable rate, we propound a multiobjective optimization approach that can flexibly switch between the EE and SE functions or change the priority level of each function using a trade-off parameter. Our dynamic approach is more tractable than the conventional approaches and more convenient to realistic communication applications and scenarios. We prove that the multiobjective optimization of the EE and SE is equivalent to a simple problem that maximizes the achievable rate/SE and minimizes the total power consumption. Then we apply the generalized framework of the resource allocation for the EE-SE trade-off to optimally allocate the subcarriers’ power for orthogonal frequency division multiplexing (OFDM) with imperfect channel estimation. Finally, we use numerical results to discuss the choice of the trade-off parameter and study the effect of the estimation error, transmission power budget and channel-to-noise ratio on the multiobjective optimization.

  5. Efficiency gains, bounds, and risk in finance

    NARCIS (Netherlands)

    Sarisoy, Cisil

    2015-01-01

    This thesis consists of three chapters. The first chapter analyzes efficiency gains in the estimation of expected returns based on asset pricing models and examines the economic implications of such gains in portfolio allocation exercises. The second chapter provides nonparametric efficiency bounds

  6. Estimation of population mean under systematic sampling

    Science.gov (United States)

    Noor-ul-amin, Muhammad; Javaid, Amjad

    2017-11-01

    In this study we propose a generalized ratio estimator under non-response for systematic random sampling. We also generate a class of estimators through special cases of generalized estimator using different combinations of coefficients of correlation, kurtosis and variation. The mean square errors and mathematical conditions are also derived to prove the efficiency of proposed estimators. Numerical illustration is included using three populations to support the results.

  7. Risk estimation using probability machines

    Science.gov (United States)

    2014-01-01

    Background Logistic regression has been the de facto, and often the only, model used in the description and analysis of relationships between a binary outcome and observed features. It is widely used to obtain the conditional probabilities of the outcome given predictors, as well as predictor effect size estimates using conditional odds ratios. Results We show how statistical learning machines for binary outcomes, provably consistent for the nonparametric regression problem, can be used to provide both consistent conditional probability estimation and conditional effect size estimates. Effect size estimates from learning machines leverage our understanding of counterfactual arguments central to the interpretation of such estimates. We show that, if the data generating model is logistic, we can recover accurate probability predictions and effect size estimates with nearly the same efficiency as a correct logistic model, both for main effects and interactions. We also propose a method using learning machines to scan for possible interaction effects quickly and efficiently. Simulations using random forest probability machines are presented. Conclusions The models we propose make no assumptions about the data structure, and capture the patterns in the data by just specifying the predictors involved and not any particular model structure. So they do not run the same risks of model mis-specification and the resultant estimation biases as a logistic model. This methodology, which we call a “risk machine”, will share properties from the statistical machine that it is derived from. PMID:24581306

  8. The efficiency of aerodynamic force production in Drosophila.

    Science.gov (United States)

    Lehmann, F O

    2001-12-01

    Total efficiency of aerodynamic force production in insect flight depends on both the efficiency with which flight muscles turn metabolic energy into muscle mechanical power and the efficiency with which this power is converted into aerodynamic flight force by the flapping wings. Total efficiency has been estimated in tethered flying fruit flies Drosophila by modulating their power expenditures in a virtual reality flight simulator while simultaneously measuring stroke kinematics, locomotor performance and metabolic costs. During flight, muscle efficiency increases with increasing flight force production, whereas aerodynamic efficiency of lift production decreases with increasing forces. As a consequence of these opposite trends, total flight efficiency in Drosophila remains approximately constant within the kinematic working range of the flight motor. Total efficiency is broadly independent of different profile power estimates and typically amounts to 2-3%. The animal achieves maximum total efficiency near hovering flight conditions, when the beating wings produce flight forces that are equal to the body weight of the insect. It remains uncertain whether this small advantage in total efficiency during hovering flight was shaped by evolutionary factors or results from functional constraints on both the production of mechanical power by the indirect flight muscles and the unsteady aerodynamic mechanisms in flapping flight.

  9. The Dimensions of the Orbital Cavity Based on High-Resolution Computed Tomography of Human Cadavers

    DEFF Research Database (Denmark)

    Felding, Ulrik Ascanius; Bloch, Sune Land; Buchwald, Christian von

    2016-01-01

    for surface area. To authors' knowledge, this study is the first to have measured the entire surface area of the orbital cavity.The volume and surface area of the orbital cavity were estimated in computed tomography scans of 11 human cadavers using unbiased stereological sampling techniques. The mean (± SD......) total volume and total surface area of the orbital cavities was 24.27 ± 3.88 cm and 32.47 ± 2.96 cm, respectively. There was no significant difference in volume (P = 0.315) or surface area (P = 0.566) between the 2 orbital cavities.The stereological technique proved to be a robust and unbiased method...... that may be used as a gold standard for comparison with automated computer software. Future imaging studies in blow-out fracture patients may be based on individual and relative calculation involving both herniated volume and fractured surface area in relation to the total volume and surface area...

  10. Efficiency of clinical and combined diagnosis of breast cancer

    International Nuclear Information System (INIS)

    Solov'ev, I.E.

    1986-01-01

    Problems on clinical, instrumental, laboratory diagnosis of mammary glands cancer are described. Efficiency of clinical examination, mammography, cytological examination, ultrasonic, radioisotopic diagnosis, some biochemical tests are estimated. The conclusion concerning advisability of complex diagnosis of mammary glands cancer especially its early forms is made. Perspectivity of application of polyamine test in diagnosis of primary cancer of the mammary gland is mark to estimate efficiency of its treatment

  11. A Quantitative Technique for Beginning Microscopists.

    Science.gov (United States)

    Sundberg, Marshall D.

    1984-01-01

    Stereology is the study of three-dimensional objects through the interpretation of two-dimensional images. Stereological techniques used in introductory botany to quantitatively examine changes in leaf anatomy in response to different environments are discussed. (JN)

  12. Modeling and energy efficiency optimization of belt conveyors

    International Nuclear Information System (INIS)

    Zhang, Shirong; Xia, Xiaohua

    2011-01-01

    Highlights: → We take optimization approach to improve operation efficiency of belt conveyors. → An analytical energy model, originating from ISO 5048, is proposed. → Then an off-line and an on-line parameter estimation schemes are investigated. → In a case study, six optimization problems are formulated with solutions in simulation. - Abstract: The improvement of the energy efficiency of belt conveyor systems can be achieved at equipment and operation levels. Specifically, variable speed control, an equipment level intervention, is recommended to improve operation efficiency of belt conveyors. However, the current implementations mostly focus on lower level control loops without operational considerations at the system level. This paper intends to take a model based optimization approach to improve the efficiency of belt conveyors at the operational level. An analytical energy model, originating from ISO 5048, is firstly proposed, which lumps all the parameters into four coefficients. Subsequently, both an off-line and an on-line parameter estimation schemes are applied to identify the new energy model, respectively. Simulation results are presented for the estimates of the four coefficients. Finally, optimization is done to achieve the best operation efficiency of belt conveyors under various constraints. Six optimization problems of a typical belt conveyor system are formulated, respectively, with solutions in simulation for a case study.

  13. Poisson sampling - The adjusted and unadjusted estimator revisited

    Science.gov (United States)

    Michael S. Williams; Hans T. Schreuder; Gerardo H. Terrazas

    1998-01-01

    The prevailing assumption, that for Poisson sampling the adjusted estimator "Y-hat a" is always substantially more efficient than the unadjusted estimator "Y-hat u" , is shown to be incorrect. Some well known theoretical results are applicable since "Y-hat a" is a ratio-of-means estimator and "Y-hat u" a simple unbiased estimator...

  14. Estimating the energy use of high definition games consoles

    International Nuclear Information System (INIS)

    Webb, A.; Mayers, K.; France, C.; Koomey, J.

    2013-01-01

    As the energy use of games consoles has risen, due to increased ownership and use and improved performance and functionality, various governments have shown an interest in ways to improve their energy efficiency. Estimates of console energy use vary widely between 32 and 500 kWh/year. Most such estimates are unreliable as they are based on incorrect assumptions and unrepresentative data. To address the shortcomings of existing estimates of console energy use, this study collates, normalises and analyses available data for power consumption and usage. The results show that the average energy use of high definition games consoles (sold between 2005 and 2011 inclusive) can be estimated at 102 kWh/year, and 64 kWh/year for new console models on sale in early 2012. The calculations herein provide representative estimates of console energy use during this period, including a breakdown of the relative contribution of different usage modes. These results could be used as a baseline to evaluate the potential energy savings from efficiency improvements in games consoles, and also to assess the potential effectiveness of any proposed energy efficiency standards. Use of accurate data will help ensure the implementation of the most effective efficiency policies and standards. - Highlights: • Estimates of games console energy use vary significantly. • New energy use estimates calculated for high definition games consoles. • Consoles currently on sale use 37% less energy than earlier models. • Gaming accounts for over 50% of console energy use. • Further research regarding console usage is needed, particularly inactive time

  15. On Estimating Quantiles Using Auxiliary Information

    Directory of Open Access Journals (Sweden)

    Berger Yves G.

    2015-03-01

    Full Text Available We propose a transformation-based approach for estimating quantiles using auxiliary information. The proposed estimators can be easily implemented using a regression estimator. We show that the proposed estimators are consistent and asymptotically unbiased. The main advantage of the proposed estimators is their simplicity. Despite the fact the proposed estimators are not necessarily more efficient than their competitors, they offer a good compromise between accuracy and simplicity. They can be used under single and multistage sampling designs with unequal selection probabilities. A simulation study supports our finding and shows that the proposed estimators are robust and of an acceptable accuracy compared to alternative estimators, which can be more computationally intensive.

  16. Male pre- and post-pubertal castration effect on live weight, components of empty body weight, estimated nitrogen excretion and efficiency in Piemontese hypertrofic cattle

    Directory of Open Access Journals (Sweden)

    Davide Biagini

    2011-04-01

    Full Text Available To evaluate the effect of sexual neutering and age of castration on empty body weight (EBW components and estimated nitrogen excretion and efficiency, a trial was carried out on 3 groups of double-muscled Piemontese calves: early castrated (EC, 5th month of age, late castrated (LC, 12th month of age and intact males (IM, control group. Animals were fed at the same energy and protein level and slaughtered at 18th month of age. Live and slaughtering performances and EBW components were recorded, whereas N excretion was calculated by difference between diet and weight gain N content. In live and slaughtering performances, IM showed higher final, carcass and total meat weight than EC and LC (P<0.01. In EBW components, IM showed higher blood and head weight than EC and LC (P<0.01 and 0.05 respectively, and differences were found between EC and LC for head weights (P<0.01. IM showed higher body crude protein (BCP than EC and LC (P<0.01 and 0.05 respectively, but BCP/EBW ratio was higher only in IM than EC (P<0.05. Estimated N daily gain was higher in IM than EC and LC (P<0.01. Only LC showed higher excretion than IM (P<0.05, and N efficiency was higher in IM than EC and LC (P<0.05 and 0.01 respectively. In conclusion, for the Piemontese hypertrophied cattle castration significantly increases N excretion (+7% and reduces N efficiency (-15%, leading to a lower level of sustainability.

  17. Estimation of greenhouse gas (GHG) emission and energy use efficiency (EUE) analysis in rainfed canola production (case study: Golestan province, Iran)

    International Nuclear Information System (INIS)

    Kazemi, Hossein; Bourkheili, Saeid Hassanpour; Kamkar, Behnam; Soltani, Afshin; Gharanjic, Kambiz; Nazari, Noor Mohammad

    2016-01-01

    Increasing the use of energy inputs in agricultural section has been led to numerous environmental concerns such as greenhouse gas (GHG) emissions, high consumption of non-renewable resources, loss of biodiversity and environment pollutions. The study was aimed to analyze the energy use efficiency (EUE) and estimation of GHG emissions from rainfed–based canola production systems (RCPSs) in Iran. In this study, data were collected from 35 farms in Golestan province (northeast of Iran) by a face to face questionnaire performed and statistical yearbooks of 2014. The amount of GHG emissions (per hectare) from inputs used in RCPSs was calculated using CO 2 emissions coefficient of agricultural inputs. Results showed that the EUE and net energy (NE) were as 3.44 and 35,537.81 MJ ha −1 , respectively. The value of these indices for the study area indicated that surveyed fields are approximately efficient in the use of energy for canola production. The highest share of energy consumption belonged to nitrogen fertilizer (42.09%) followed by diesel fuel (39.81%). In production of rainfed canola, GHG emission was estimated as 1009.91 kg CO 2 equivalent per hectare. Based on the results, nitrogen fertilizer (44.15%), diesel fuel (30.16%) and machinery (14.49%) for field operations had the highest share of GHG emission. The total consumed energy by inputs could be classified as direct energy (40.09%), and indirect energy (59.91%) or renewable energy (2.02%) and nonrenewable energy (97.98%). These results demonstrate that the share of renewable energies in canola production is very low in the studied region and agriculture in Iran is very much dependent on non-renewable energies. In this study, the energy use status in RCPSs has analyzed and the main involved causes have been interpreted. - Highlights: • Fertilizers had the highest share in GHG emission. • The share of renewable energy was low in canola production. • Canola production is efficient in Iran.

  18. The quantile regression approach to efficiency measurement: insights from Monte Carlo simulations.

    Science.gov (United States)

    Liu, Chunping; Laporte, Audrey; Ferguson, Brian S

    2008-09-01

    In the health economics literature there is an ongoing debate over approaches used to estimate the efficiency of health systems at various levels, from the level of the individual hospital - or nursing home - up to that of the health system as a whole. The two most widely used approaches to evaluating the efficiency with which various units deliver care are non-parametric data envelopment analysis (DEA) and parametric stochastic frontier analysis (SFA). Productivity researchers tend to have very strong preferences over which methodology to use for efficiency estimation. In this paper, we use Monte Carlo simulation to compare the performance of DEA and SFA in terms of their ability to accurately estimate efficiency. We also evaluate quantile regression as a potential alternative approach. A Cobb-Douglas production function, random error terms and a technical inefficiency term with different distributions are used to calculate the observed output. The results, based on these experiments, suggest that neither DEA nor SFA can be regarded as clearly dominant, and that, depending on the quantile estimated, the quantile regression approach may be a useful addition to the armamentarium of methods for estimating technical efficiency.

  19. Quantum tomography via compressed sensing: error bounds, sample complexity and efficient estimators

    International Nuclear Information System (INIS)

    Flammia, Steven T; Gross, David; Liu, Yi-Kai; Eisert, Jens

    2012-01-01

    Intuitively, if a density operator has small rank, then it should be easier to estimate from experimental data, since in this case only a few eigenvectors need to be learned. We prove two complementary results that confirm this intuition. Firstly, we show that a low-rank density matrix can be estimated using fewer copies of the state, i.e. the sample complexity of tomography decreases with the rank. Secondly, we show that unknown low-rank states can be reconstructed from an incomplete set of measurements, using techniques from compressed sensing and matrix completion. These techniques use simple Pauli measurements, and their output can be certified without making any assumptions about the unknown state. In this paper, we present a new theoretical analysis of compressed tomography, based on the restricted isometry property for low-rank matrices. Using these tools, we obtain near-optimal error bounds for the realistic situation where the data contain noise due to finite statistics, and the density matrix is full-rank with decaying eigenvalues. We also obtain upper bounds on the sample complexity of compressed tomography, and almost-matching lower bounds on the sample complexity of any procedure using adaptive sequences of Pauli measurements. Using numerical simulations, we compare the performance of two compressed sensing estimators—the matrix Dantzig selector and the matrix Lasso—with standard maximum-likelihood estimation (MLE). We find that, given comparable experimental resources, the compressed sensing estimators consistently produce higher fidelity state reconstructions than MLE. In addition, the use of an incomplete set of measurements leads to faster classical processing with no loss of accuracy. Finally, we show how to certify the accuracy of a low-rank estimate using direct fidelity estimation, and describe a method for compressed quantum process tomography that works for processes with small Kraus rank and requires only Pauli eigenstate preparations

  20. An Efficient Code-Timing Estimator for DS-CDMA Systems over Resolvable Multipath Channels

    Directory of Open Access Journals (Sweden)

    Jian Li

    2005-04-01

    Full Text Available We consider the problem of training-based code-timing estimation for the asynchronous direct-sequence code-division multiple-access (DS-CDMA system. We propose a modified large-sample maximum-likelihood (MLSML estimator that can be used for the code-timing estimation for the DS-CDMA systems over the resolvable multipath channels in closed form. Simulation results show that MLSML can be used to provide a high correct acquisition probability and a high estimation accuracy. Simulation results also show that MLSML can have very good near-far resistant capability due to employing a data model similar to that for adaptive array processing where strong interferences can be suppressed.