WorldWideScience

Sample records for path sampling technique

  1. Heating and thermal control of brazing technique to break contamination path for potential Mars sample return

    Science.gov (United States)

    Bao, Xiaoqi; Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph; Campos, Sergio

    2017-04-01

    The potential return of Mars sample material is of great interest to the planetary science community, as it would enable extensive analysis of samples with highly sensitive laboratory instruments. It is important to make sure such a mission concept would not bring any living microbes, which may possibly exist on Mars, back to Earth's environment. In order to ensure the isolation of Mars microbes from Earth's Atmosphere, a brazing sealing and sterilizing technique was proposed to break the Mars-to-Earth contamination path. Effectively, heating the brazing zone in high vacuum space and controlling the sample temperature for integrity are key challenges to the implementation of this technique. The break-thechain procedures for container configurations, which are being considered, were simulated by multi-physics finite element models. Different heating methods including induction and resistive/radiation were evaluated. The temperature profiles of Martian samples in a proposed container structure were predicted. The results show that the sealing and sterilizing process can be controlled such that the samples temperature is maintained below the level that may cause damage, and that the brazing technique is a feasible approach to breaking the contamination path.

  2. Nonadiabatic transition path sampling

    International Nuclear Information System (INIS)

    Sherman, M. C.; Corcelli, S. A.

    2016-01-01

    Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.

  3. Techniques and applications of path integration

    CERN Document Server

    Schulman, L S

    2005-01-01

    A book of techniques and applications, this text defines the path integral and illustrates its uses by example. It is suitable for advanced undergraduates and graduate students in physics; its sole prerequisite is a first course in quantum mechanics. For applications requiring specialized knowledge, the author supplies background material.The first part of the book develops the techniques of path integration. Topics include probability amplitudes for paths and the correspondence limit for the path integral; vector potentials; the Ito integral and gauge transformations; free particle and quadra

  4. The transformation techniques in path integration

    International Nuclear Information System (INIS)

    Inomata, A.

    1989-01-01

    In this paper general remarks are made concerning the time transformation techniques in path integration and their implementations. Time transformations may be divided into two classes: global (integrable) time transformations and local (nonintegrable) time transformations. Although a brief account of global time transformations is given, attention is focused on local transformations. First, time transformations in the classical Kepler problem are reviewed. Then, problems encountered in implementing a local time transformation in quantum mechanics are analyzed. A several propositions pertinent to the implementation of local time transformations, particularly basic to the local time rescaling trick in a discretized path integral, are presented

  5. Entropic sampling in the path integral Monte Carlo method

    International Nuclear Information System (INIS)

    Vorontsov-Velyaminov, P N; Lyubartsev, A P

    2003-01-01

    We have extended the entropic sampling Monte Carlo method to the case of path integral representation of a quantum system. A two-dimensional density of states is introduced into path integral form of the quantum canonical partition function. Entropic sampling technique within the algorithm suggested recently by Wang and Landau (Wang F and Landau D P 2001 Phys. Rev. Lett. 86 2050) is then applied to calculate the corresponding entropy distribution. A three-dimensional quantum oscillator is considered as an example. Canonical distributions for a wide range of temperatures are obtained in a single simulation run, and exact data for the energy are reproduced

  6. Water evaporation: a transition path sampling study.

    Science.gov (United States)

    Varilly, Patrick; Chandler, David

    2013-02-07

    We use transition path sampling to study evaporation in the SPC/E model of liquid water. On the basis of thousands of evaporation trajectories, we characterize the members of the transition state ensemble (TSE), which exhibit a liquid-vapor interface with predominantly negative mean curvature at the site of evaporation. We also find that after evaporation is complete, the distributions of translational and angular momenta of the evaporated water are Maxwellian with a temperature equal to that of the liquid. To characterize the evaporation trajectories in their entirety, we find that it suffices to project them onto just two coordinates: the distance of the evaporating molecule to the instantaneous liquid-vapor interface and the velocity of the water along the average interface normal. In this projected space, we find that the TSE is well-captured by a simple model of ballistic escape from a deep potential well, with no additional barrier to evaporation beyond the cohesive strength of the liquid. Equivalently, they are consistent with a near-unity probability for a water molecule impinging upon a liquid droplet to condense. These results agree with previous simulations and with some, but not all, recent experiments.

  7. An operator expansion technique for path integral analysis

    International Nuclear Information System (INIS)

    Tsvetkov, I.V.

    1995-01-01

    A new method of path integral analysis in the framework of a power series technique is presented. The method is based on the operator expansion of an exponential. A regular procedure to calculate the correction terms is found. (orig.)

  8. Advanced path sampling of the kinetic network of small proteins

    NARCIS (Netherlands)

    Du, W.

    2014-01-01

    This thesis is focused on developing advanced path sampling simulation methods to study protein folding and unfolding, and to build kinetic equilibrium networks describing these processes. In Chapter 1 the basic knowledge of protein structure and folding theories were introduced and a brief overview

  9. Efficient Unbiased Rendering using Enlightened Local Path Sampling

    DEFF Research Database (Denmark)

    Kristensen, Anders Wang

    measurements, which are the solution to the adjoint light transport problem. The second is a representation of the distribution of radiance and importance in the scene. We also derive a new method of particle sampling, which is advantageous compared to existing methods. Together we call the resulting algorithm....... The downside to using these algorithms is that they can be slow to converge. Due to the nature of Monte Carlo methods, the results are random variables subject to variance. This manifests itself as noise in the images, which can only be reduced by generating more samples. The reason these methods are slow...... is because of a lack of eeffective methods of importance sampling. Most global illumination algorithms are based on local path sampling, which is essentially a recipe for constructing random walks. Using this procedure paths are built based on information given explicitly as part of scene description...

  10. Development of SYVAC sampling techniques

    International Nuclear Information System (INIS)

    Prust, J.O.; Dalrymple, G.J.

    1985-04-01

    This report describes the requirements of a sampling scheme for use with the SYVAC radiological assessment model. The constraints on the number of samples that may be taken is considered. The conclusions from earlier studies using the deterministic generator sampling scheme are summarised. The method of Importance Sampling and a High Dose algorithm, which are designed to preferentially sample in the high dose region of the parameter space, are reviewed in the light of experience gained from earlier studies and the requirements of a site assessment and sensitivity analyses. In addition the use of an alternative numerical integration method for estimating risk is discussed. It is recommended that the method of Importance Sampling is developed and tested for use with SYVAC. An alternative numerical integration method is not recommended for investigation at this stage but should be the subject of future work. (author)

  11. Two sampling techniques for game meat

    OpenAIRE

    van der Merwe, Maretha; Jooste, Piet J.; Hoffman, Louw C.; Calitz, Frikkie J.

    2013-01-01

    A study was conducted to compare the excision sampling technique used by the export market and the sampling technique preferred by European countries, namely the biotrace cattle and swine test. The measuring unit for the excision sampling was grams (g) and square centimetres (cm2) for the swabbing technique. The two techniques were compared after a pilot test was conducted on spiked approved beef carcasses (n = 12) that statistically proved the two measuring units correlated. The two sampling...

  12. Detecting reactive islands using Lagrangian descriptors and the relevance to transition path sampling.

    Science.gov (United States)

    Patra, Sarbani; Keshavamurthy, Srihari

    2018-02-14

    It has been known for sometime now that isomerization reactions, classically, are mediated by phase space structures called reactive islands (RI). RIs provide one possible route to correct for the nonstatistical effects in the reaction dynamics. In this work, we map out the reactive islands for the two dimensional Müller-Brown model potential and show that the reactive islands are intimately linked to the issue of rare event sampling. In particular, we establish the sensitivity of the so called committor probabilities, useful quantities in the transition path sampling technique, to the hierarchical RI structures. Mapping out the RI structure for high dimensional systems, however, is a challenging task. Here, we show that the technique of Lagrangian descriptors is able to effectively identify the RI hierarchy in the model system. Based on our results, we suggest that the Lagrangian descriptors can be useful for detecting RIs in high dimensional systems.

  13. An adaptive dual-optimal path-planning technique for unmanned air vehicles

    Directory of Open Access Journals (Sweden)

    Whitfield Clifford A.

    2016-01-01

    Full Text Available A multi-objective technique for unmanned air vehicle path-planning generation through task allocation has been developed. The dual-optimal path-planning technique generates real-time adaptive flight paths based on available flight windows and environmental influenced objectives. The environmentally-influenced flight condition determines the aircraft optimal orientation within a downstream virtual window of possible vehicle destinations that is based on the vehicle’s kinematics. The intermittent results are then pursued by a dynamic optimization technique to determine the flight path. This path-planning technique is a multi-objective optimization procedure consisting of two goals that do not require additional information to combine the conflicting objectives into a single-objective. The technique was applied to solar-regenerative high altitude long endurance flight which can benefit significantly from an adaptive real-time path-planning technique. The objectives were to determine the minimum power required flight paths while maintaining maximum solar power for continual surveillance over an area of interest (AOI. The simulated path generation technique prolonged the flight duration over a sustained turn loiter flight path by approximately 2 months for a year of flight. The potential for prolonged solar powered flight was consistent for all latitude locations, including 2 months of available flight at 60° latitude, where sustained turn flight was no longer capable.

  14. Alternative Constraint Handling Technique for Four-Bar Linkage Path Generation

    Science.gov (United States)

    Sleesongsom, S.; Bureerat, S.

    2018-03-01

    This paper proposes an extension of a new concept for path generation from our previous work by adding a new constraint handling technique. The propose technique was initially designed for problems without prescribed timing by avoiding the timing constraint, while remain constraints are solving with a new constraint handling technique. The technique is one kind of penalty technique. The comparative study is optimisation of path generation problems are solved using self-adaptive population size teaching-learning based optimization (SAP-TLBO) and original TLBO. In this study, two traditional path generation test problem are used to test the proposed technique. The results show that the new technique can be applied with the path generation problem without prescribed timing and gives better results than the previous technique. Furthermore, SAP-TLBO outperforms the original one.

  15. Rare events via multiple reaction channels sampled by path replica exchange

    NARCIS (Netherlands)

    Bolhuis, P.G.

    2008-01-01

    Transition path sampling (TPS) was developed for studying activated processes in complex systems with unknown reaction coordinate. Transition interface sampling (TIS) allows efficient evaluation of the rate constants. However, when the transition can occur via more than one reaction channel

  16. Newly introduced sample preparation techniques: towards miniaturization.

    Science.gov (United States)

    Costa, Rosaria

    2014-01-01

    Sampling and sample preparation are of crucial importance in an analytical procedure, representing quite often a source of errors. The technique chosen for the isolation of analytes greatly affects the success of a chemical determination. On the other hand, growing concerns about environmental and human safety, along with the introduction of international regulations for quality control, have moved the interest of scientists towards specific needs. Newly introduced sample preparation techniques are challenged to meet new criteria: (i) miniaturization, (ii) higher sensitivity and selectivity, and (iii) automation. In this survey, the most recent techniques introduced in the field of sample preparation will be described and discussed, along with many examples of applications.

  17. Two sampling techniques for game meat

    Directory of Open Access Journals (Sweden)

    Maretha van der Merwe

    2013-03-01

    Full Text Available A study was conducted to compare the excision sampling technique used by the export market and the sampling technique preferred by European countries, namely the biotrace cattle and swine test. The measuring unit for the excision sampling was grams (g and square centimetres (cm2 for the swabbing technique. The two techniques were compared after a pilot test was conducted on spiked approved beef carcasses (n = 12 that statistically proved the two measuring units correlated. The two sampling techniques were conducted on the same game carcasses (n = 13 and analyses performed for aerobic plate count (APC, Escherichia coli and Staphylococcus aureus, for both techniques. A more representative result was obtained by swabbing and no damage was caused to the carcass. Conversely, the excision technique yielded fewer organisms and caused minor damage to the carcass. The recovery ratio from the sampling technique improved 5.4 times for APC, 108.0 times for E. coli and 3.4 times for S. aureus over the results obtained from the excision technique. It was concluded that the sampling methods of excision and swabbing can be used to obtain bacterial profiles from both export and local carcasses and could be used to indicate whether game carcasses intended for the local market are possibly on par with game carcasses intended for the export market and therefore safe for human consumption.

  18. Two sampling techniques for game meat.

    Science.gov (United States)

    van der Merwe, Maretha; Jooste, Piet J; Hoffman, Louw C; Calitz, Frikkie J

    2013-03-20

    A study was conducted to compare the excision sampling technique used by the export market and the sampling technique preferred by European countries, namely the biotrace cattle and swine test. The measuring unit for the excision sampling was grams (g) and square centimetres (cm2) for the swabbing technique. The two techniques were compared after a pilot test was conducted on spiked approved beef carcasses (n = 12) that statistically proved the two measuring units correlated. The two sampling techniques were conducted on the same game carcasses (n = 13) and analyses performed for aerobic plate count (APC), Escherichia coli and Staphylococcus aureus, for both techniques. A more representative result was obtained by swabbing and no damage was caused to the carcass. Conversely, the excision technique yielded fewer organisms and caused minor damage to the carcass. The recovery ratio from the sampling technique improved 5.4 times for APC, 108.0 times for E. coli and 3.4 times for S. aureus over the results obtained from the excision technique. It was concluded that the sampling methods of excision and swabbing can be used to obtain bacterial profiles from both export and local carcasses and could be used to indicate whether game carcasses intended for the local market are possibly on par with game carcasses intended for the export market and therefore safe for human consumption.

  19. Critical evaluation of sample pretreatment techniques.

    Science.gov (United States)

    Hyötyläinen, Tuulia

    2009-06-01

    Sample preparation before chromatographic separation is the most time-consuming and error-prone part of the analytical procedure. Therefore, selecting and optimizing an appropriate sample preparation scheme is a key factor in the final success of the analysis, and the judicious choice of an appropriate procedure greatly influences the reliability and accuracy of a given analysis. The main objective of this review is to critically evaluate the applicability, disadvantages, and advantages of various sample preparation techniques. Particular emphasis is placed on extraction techniques suitable for both liquid and solid samples.

  20. Multiscale simulations of patchy particle systems combining Molecular Dynamics, Path Sampling and Green's Function Reaction Dynamics

    Science.gov (United States)

    Bolhuis, Peter

    Important reaction-diffusion processes, such as biochemical networks in living cells, or self-assembling soft matter, span many orders in length and time scales. In these systems, the reactants' spatial dynamics at mesoscopic length and time scales of microns and seconds is coupled to the reactions between the molecules at microscopic length and time scales of nanometers and milliseconds. This wide range of length and time scales makes these systems notoriously difficult to simulate. While mean-field rate equations cannot describe such processes, the mesoscopic Green's Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. The recently developed multiscale Molecular Dynamics Green's Function Reaction Dynamics (MD-GFRD) approach combines GFRD for simulating the system at the mesocopic scale where particles are far apart, with microscopic Molecular (or Brownian) Dynamics, for simulating the system at the microscopic scale where reactants are in close proximity. The association and dissociation of particles are treated with rare event path sampling techniques. I will illustrate the efficiency of this method for patchy particle systems. Replacing the microscopic regime with a Markov State Model avoids the microscopic regime completely. The MSM is then pre-computed using advanced path-sampling techniques such as multistate transition interface sampling. I illustrate this approach on patchy particle systems that show multiple modes of binding. MD-GFRD is generic, and can be used to efficiently simulate reaction-diffusion systems at the particle level, including the orientational dynamics, opening up the possibility for large-scale simulations of e.g. protein signaling networks.

  1. Sample path analysis and distributions of boundary crossing times

    CERN Document Server

    Zacks, Shelemyahu

    2017-01-01

    This monograph is focused on the derivations of exact distributions of first boundary crossing times of Poisson processes, compound Poisson processes, and more general renewal processes.  The content is limited to the distributions of first boundary crossing times and their applications to various stochastic models. This book provides the theory and techniques for exact computations of distributions and moments of level crossing times. In addition, these techniques could replace simulations in many cases, thus providing more insight about the phenomenona studied. This book takes a general approach for studying telegraph processes and is based on nearly thirty published papers by the author and collaborators over the past twenty five years.  No prior knowledge of advanced probability is required, making the book widely available to students and researchers in applied probability, operations research, applied physics, and applied mathematics. .

  2. Path integral methods for primordial density perturbations - sampling of constrained Gaussian random fields

    International Nuclear Information System (INIS)

    Bertschinger, E.

    1987-01-01

    Path integrals may be used to describe the statistical properties of a random field such as the primordial density perturbation field. In this framework the probability distribution is given for a Gaussian random field subjected to constraints such as the presence of a protovoid or supercluster at a specific location in the initial conditions. An algorithm has been constructed for generating samples of a constrained Gaussian random field on a lattice using Monte Carlo techniques. The method makes possible a systematic study of the density field around peaks or other constrained regions in the biased galaxy formation scenario, and it is effective for generating initial conditions for N-body simulations with rare objects in the computational volume. 21 references

  3. NAIL SAMPLING TECHNIQUE AND ITS INTERPRETATION

    Directory of Open Access Journals (Sweden)

    TZAR MN

    2011-01-01

    Full Text Available The clinical suspicion of onychomyosis based on appearance of the nails, requires culture for confirmation. This is because treatment requires prolonged use of systemic agents which may cause side effects. One of the common problems encountered is improper nail sampling technique which results in loss of essential information. The unfamiliar terminologies used in reporting culture results may intimidate physicians resulting in misinterpretation and hamper treatment decision. This article provides a simple guide on nail sampling technique and the interpretation of culture results.

  4. Microextraction sample preparation techniques in biomedical analysis.

    Science.gov (United States)

    Szultka, Malgorzata; Pomastowski, Pawel; Railean-Plugaru, Viorica; Buszewski, Boguslaw

    2014-11-01

    Biologically active compounds are found in biological samples at relatively low concentration levels. The sample preparation of target compounds from biological, pharmaceutical, environmental, and food matrices is one of the most time-consuming steps in the analytical procedure. The microextraction techniques are dominant. Metabolomic studies also require application of proper analytical technique for the determination of endogenic metabolites present in biological matrix on trace concentration levels. Due to the reproducibility of data, precision, relatively low cost of the appropriate analysis, simplicity of the determination, and the possibility of direct combination of those techniques with other methods (combination types on-line and off-line), they have become the most widespread in routine determinations. Additionally, sample pretreatment procedures have to be more selective, cheap, quick, and environmentally friendly. This review summarizes the current achievements and applications of microextraction techniques. The main aim is to deal with the utilization of different types of sorbents for microextraction and emphasize the use of new synthesized sorbents as well as to bring together studies concerning the systematic approach to method development. This review is dedicated to the description of microextraction techniques and their application in biomedical analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Innovative directional and position specific sampling technique

    International Nuclear Information System (INIS)

    Hutzel, W.J.; Hill, J.L. III; Foster, E.L.

    1994-01-01

    UTD, Incorporated has developed a unique real-time, in-situ POsition LOcation (POLO) device which will directly enhance the Department of Energy's Environmental Restoration and Waste Management Program through improvements to finding contamination, identifying extent of contamination, remediating, and finally monitoring sites. POLO is smaller than existing technology and is unaffected by the presence of steel and other magnetic materials. The size of the device offers for the first time, the possibility to accurately determine the location of a penetrometer. It will be usable, in its present form, to map the position of a sampling device as that device is inserted into the ground. A three phase program was proposed to DOE to take the POLO System through the three levels of maturity prior to commercialization. Phase 1 included the design and testing of individual components of the device and met or exceeded success criteria. Phase 2 has included laboratory-scale tracking experiments of the integrated POLO System that have met or exceeded the success criterion as well. The success criterion is to demonstrate path tracking accuracy with a total error of less than 0.50% of the distance traveled for distances less than 70 meters. In Phase 3 we will develop and test a full-scale POLO System and conclude with a field demonstration. The goal of the Phase 3 effort is to achieve the same 0.50% accuracy or better with respect to the distance traveled for distances less than 70 meters in the field as was demonstrated in laboratory tests in the earlier phases. The final report details the design of a realistic laboratory-scale penetrometer path and describes the POLO tracking experiments that were conducted. Plans for demonstrations as well as commercialization and technology transfer with DOE field sites are described, highlighting the expected smooth transition to full-scale production

  6. Macrocell path loss prediction using artificial intelligence techniques

    Science.gov (United States)

    Usman, Abraham U.; Okereke, Okpo U.; Omizegba, Elijah E.

    2014-04-01

    The prediction of propagation loss is a practical non-linear function approximation problem which linear regression or auto-regression models are limited in their ability to handle. However, some computational Intelligence techniques such as artificial neural networks (ANNs) and adaptive neuro-fuzzy inference systems (ANFISs) have been shown to have great ability to handle non-linear function approximation and prediction problems. In this study, the multiple layer perceptron neural network (MLP-NN), radial basis function neural network (RBF-NN) and an ANFIS network were trained using actual signal strength measurement taken at certain suburban areas of Bauchi metropolis, Nigeria. The trained networks were then used to predict propagation losses at the stated areas under differing conditions. The predictions were compared with the prediction accuracy of the popular Hata model. It was observed that ANFIS model gave a better fit in all cases having higher R2 values in each case and on average is more robust than MLP and RBF models as it generalises better to a different data.

  7. Apical Transportation, Centering Ability, and Cleaning Effectiveness of Reciprocating Single-file System Associated with Different Glide Path Techniques.

    Science.gov (United States)

    de Carvalho, Guilherme Moreira; Sponchiado Junior, Emílio Carlos; Garrido, Angela Delfina Bittencourt; Lia, Raphael Carlos Comelli; Garcia, Lucas da Fonseca Roberti; Marques, André Augusto Franco

    2015-12-01

    The aim of this study was to evaluate the apical transportation, the centering ability, and the cleaning effectiveness of a reciprocating single-file system associated to different glide path techniques. The mesial root canals of 52 mandibular molars were randomly distributed into 4 groups (n = 13) according to the different glide path techniques used before biomechanical preparation with Reciproc System (RS): KF/RS (sizes 10 and 15 K-files), NGP/RS (no glide path, only reciprocating system), PF/RS (sizes 13, 16, and 19 PathFile instruments), and NP (no preparation). Cone-beam computed tomography analysis was performed before and after instrumentation for apical third images acquisition. Apical transportation and its direction were evaluated by using the formula D = (X1 - X2) - (Y1 - Y2), and the centering ability was analyzed by the formula CC = (X1 - X2/Y1 - Y2 or Y1 - Y2/X1 - X2). The samples were submitted to histologic processing and analyzed under a digital microscope for debris quantification. The values were statistically analyzed (Kruskal-Wallis, the Dunn multiple comparisons test, P .05). Groups had a tendency toward transportation in the mesial direction. No technique had perfect centering ability (=1.0), with no significant difference among them. KF/RS had larger amount of debris, with statistically significant difference in comparison with NGP/RS (P > .05). The different glide path techniques promoted minimal apical transportation, and the reciprocating single-file system tested remained relatively centralized within the root canal. Also, the different techniques interfered in the cleaning effectiveness of the reciprocating system. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Methodology for using root locus technique for mobile robots path planning

    Directory of Open Access Journals (Sweden)

    Mario Ricardo Arbulú Saavedra

    2015-11-01

    Full Text Available This paper shows the analysis and the implementation methodology of the technique of dynamic systems roots location used in free-obstacle path planning for mobile robots. First of all, the analysis and morphologic behavior identification of the paths depending on roots location in complex plane are performed, where paths type and their attraction and repulsion features in the presence of other roots similarly to the obtained with artificial potential fields are identified. An implementation methodology for this technique of mobile robots path planning is proposed, starting from three different methods of roots location for obstacles in the scene. Those techniques change depending on the obstacle key points selected for roots, such as borders, crossing points with original path, center and vertices. Finally, a behavior analysis of general technique and the effectiveness of each tried method is performed, doing 20 tests for each one, obtaining a value of 65% for the selected method. Modifications and possible improvements to this methodology are also proposed.

  9. NAIL SAMPLING TECHNIQUE AND ITS INTERPRETATION

    OpenAIRE

    TZAR MN; LEELAVATHI M

    2011-01-01

    The clinical suspicion of onychomyosis based on appearance of the nails, requires culture for confirmation. This is because treatment requires prolonged use of systemic agents which may cause side effects. One of the common problems encountered is improper nail sampling technique which results in loss of essential information. The unfamiliar terminologies used in reporting culture results may intimidate physicians resulting in misinterpretation and hamper treatment decision. This article prov...

  10. Sample preparation techniques for (p, X) spectrometry

    International Nuclear Information System (INIS)

    Whitehead, N.E.

    1985-01-01

    Samples are ashed at low temperature, using oxygen plasma; a rotary evaporator, and freeze drying speeded up the ashing. The new design of apparatus manufactured was only 10 watt but was as efficient as a 200 watt commercial machine; a circuit diagram is included. Samples of hair and biopsy samples of skin were analysed by the technique. A wool standard was prepared for interlaboratory comparison exercises. It was based on New Zealand merino sheep wool and was 2.9 kg in weight. A washing protocol was developed, which preserves most of the trace element content. The wool was ground in liquid nitrogen using a plastic pestle and beaker, driven by a rotary drill press. (author)

  11. Sample size estimation and sampling techniques for selecting a representative sample

    Directory of Open Access Journals (Sweden)

    Aamir Omair

    2014-01-01

    Full Text Available Introduction: The purpose of this article is to provide a general understanding of the concepts of sampling as applied to health-related research. Sample Size Estimation: It is important to select a representative sample in quantitative research in order to be able to generalize the results to the target population. The sample should be of the required sample size and must be selected using an appropriate probability sampling technique. There are many hidden biases which can adversely affect the outcome of the study. Important factors to consider for estimating the sample size include the size of the study population, confidence level, expected proportion of the outcome variable (for categorical variables/standard deviation of the outcome variable (for numerical variables, and the required precision (margin of accuracy from the study. The more the precision required, the greater is the required sample size. Sampling Techniques: The probability sampling techniques applied for health related research include simple random sampling, systematic random sampling, stratified random sampling, cluster sampling, and multistage sampling. These are more recommended than the nonprobability sampling techniques, because the results of the study can be generalized to the target population.

  12. Energy-Aware Path Planning for UAS Persistent Sampling and Surveillance

    Science.gov (United States)

    Shaw-Cortez, Wenceslao

    The focus of this work is to develop an energy-aware path planning algorithm that maximizes UAS endurance, while performing sampling and surveillance missions in a known, stationary wind environment. The energy-aware aspect is specifically tailored to extract energy from the wind to reduce thrust use, thereby increasing aircraft endurance. Wind energy extraction is performed by static soaring and dynamic soaring. Static soaring involves using upward wind currents to increase altitude and potential energy. Dynamic soaring involves taking advantage of wind gradients to exchange potential and kinetic energy. The path planning algorithm developed in this work uses optimization to combine these soaring trajectories with the overarching sampling and surveillance mission. The path planning algorithm uses a simplified aircraft model to tractably optimize soaring trajectories. This aircraft model is presented and along with the derivation of the equations of motion. A nonlinear program is used to create the soaring trajectories based on a given optimization problem. This optimization problem is defined using a heuristic decision tree, which defines appropriate problems given a sampling and surveillance mission and a wind model. Simulations are performed to assess the path planning algorithm. The results are used to identify properties of soaring trajectories as well as to determine what wind conditions support minimal thrust soaring. Additional results show how the path planning algorithm can be tuned between maximizing aircraft endurance and performing the sampling and surveillance mission. A means of trajectory stitching is demonstrated to show how the periodic soaring segments can be combined together to provide a full solution to an infinite/long horizon problem.

  13. Accelerated sampling by infinite swapping of path integral molecular dynamics with surface hopping

    Science.gov (United States)

    Lu, Jianfeng; Zhou, Zhennan

    2018-02-01

    To accelerate the thermal equilibrium sampling of multi-level quantum systems, the infinite swapping limit of a recently proposed multi-level ring polymer representation is investigated. In the infinite swapping limit, the ring polymer evolves according to an averaged Hamiltonian with respect to all possible surface index configurations of the ring polymer and thus connects the surface hopping approach to the mean-field path-integral molecular dynamics. A multiscale integrator for the infinite swapping limit is also proposed to enable efficient sampling based on the limiting dynamics. Numerical results demonstrate the huge improvement of sampling efficiency of the infinite swapping compared with the direct simulation of path-integral molecular dynamics with surface hopping.

  14. Comparison of Estimation Techniques for Vibro-Acoustic Transfer Path Analysis

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo França Padilha

    2006-01-01

    Full Text Available Vibro-acoustic Transfer Path Analysis (TPA is a tool to evaluate the contribution of different energy propagation paths between a source and a receiver, linked to each other by a number of connections. TPA is typically used to quantify and rank the relative importance of these paths in a given frequency band, determining the most significant one to the receiver. Basically, two quantities have to be determined for TPA: the operational forces at each transfer path and the Frequency Response Functions (FRF of these paths. The FRF are obtained either experimentally or analytically, and the influence of the mechanical impedance of the source can be taken into account or not. The operational forces can be directly obtained from measurements using force transducers or indirectly estimated from auxiliary response measurements. Two methods to obtain the operational forces indirectly – the Complex Stiffness Method (CSM and the Matrix Inversion Method (MIM – associated with two possible configurations to determine the FRF – including and excluding the source impedance – are presented and discussed in this paper. The effect of weak and strong coupling among the paths is also commented considering the techniques previously presented. The main conclusion is that, with the source removed, CSM gives more accurate results. On the other hand, with the source present, MIM is preferable. In the latter case, CSM should be used only if there is a high impedance mismatch between the source and the receiver. Both methods are not affected by a higher or lower degree of coupling among the transfer paths.

  15. Communication: importance sampling including path correlation in semiclassical initial value representation calculations for time correlation functions.

    Science.gov (United States)

    Pan, Feng; Tao, Guohua

    2013-03-07

    Full semiclassical (SC) initial value representation (IVR) for time correlation functions involves a double phase space average over a set of two phase points, each of which evolves along a classical path. Conventionally, the two initial phase points are sampled independently for all degrees of freedom (DOF) in the Monte Carlo procedure. Here, we present an efficient importance sampling scheme by including the path correlation between the two initial phase points for the bath DOF, which greatly improves the performance of the SC-IVR calculations for large molecular systems. Satisfactory convergence in the study of quantum coherence in vibrational relaxation has been achieved for a benchmark system-bath model with up to 21 DOF.

  16. Sample-Path Optimal Stationary Policies in Stable Markov Decision Chains with Average Reward Criterion

    Czech Academy of Sciences Publication Activity Database

    Cavazos-Cadena, R.; Montes-de-Oca, R.; Sladký, Karel

    2015-01-01

    Roč. 52, č. 2 (2015), s. 419-440 ISSN 0021-9002 Grant - others:GA AV ČR(CZ) 171396 Institutional support: RVO:67985556 Keywords : Dominated Convergence theorem for the expected average criterion * Discrepancy function * Kolmogorov inequality * Innovations * Strong sample-path optimality Subject RIV: BC - Control Systems Theory Impact factor: 0.665, year: 2015 http://library.utia.cas.cz/separaty/2015/E/sladky-0449029.pdf

  17. Path integration guided with a quality map for shape reconstruction in the fringe reflection technique

    Science.gov (United States)

    Jing, Xiaoli; Cheng, Haobo; Wen, Yongfu

    2018-04-01

    A new local integration algorithm called quality map path integration (QMPI) is reported for shape reconstruction in the fringe reflection technique. A quality map is proposed to evaluate the quality of gradient data locally, and functions as a guideline for the integrated path. The presented method can be employed in wavefront estimation from its slopes over the general shaped surface with slope noise equivalent to that in practical measurements. Moreover, QMPI is much better at handling the slope data with local noise, which may be caused by the irregular shapes of the surface under test. The performance of QMPI is discussed by simulations and experiment. It is shown that QMPI not only improves the accuracy of local integration, but can also be easily implemented with no iteration compared to Southwell zonal reconstruction (SZR). From an engineering point-of-view, the proposed method may also provide an efficient and stable approach for different shapes with high-precise demand.

  18. An open-chain imaginary-time path-integral sampling approach to the calculation of approximate symmetrized quantum time correlation functions.

    Science.gov (United States)

    Cendagorta, Joseph R; Bačić, Zlatko; Tuckerman, Mark E

    2018-03-14

    We introduce a scheme for approximating quantum time correlation functions numerically within the Feynman path integral formulation. Starting with the symmetrized version of the correlation function expressed as a discretized path integral, we introduce a change of integration variables often used in the derivation of trajectory-based semiclassical methods. In particular, we transform to sum and difference variables between forward and backward complex-time propagation paths. Once the transformation is performed, the potential energy is expanded in powers of the difference variables, which allows us to perform the integrals over these variables analytically. The manner in which this procedure is carried out results in an open-chain path integral (in the remaining sum variables) with a modified potential that is evaluated using imaginary-time path-integral sampling rather than requiring the generation of a large ensemble of trajectories. Consequently, any number of path integral sampling schemes can be employed to compute the remaining path integral, including Monte Carlo, path-integral molecular dynamics, or enhanced path-integral molecular dynamics. We believe that this approach constitutes a different perspective in semiclassical-type approximations to quantum time correlation functions. Importantly, we argue that our approximation can be systematically improved within a cumulant expansion formalism. We test this approximation on a set of one-dimensional problems that are commonly used to benchmark approximate quantum dynamical schemes. We show that the method is at least as accurate as the popular ring-polymer molecular dynamics technique and linearized semiclassical initial value representation for correlation functions of linear operators in most of these examples and improves the accuracy of correlation functions of nonlinear operators.

  19. An open-chain imaginary-time path-integral sampling approach to the calculation of approximate symmetrized quantum time correlation functions

    Science.gov (United States)

    Cendagorta, Joseph R.; Bačić, Zlatko; Tuckerman, Mark E.

    2018-03-01

    We introduce a scheme for approximating quantum time correlation functions numerically within the Feynman path integral formulation. Starting with the symmetrized version of the correlation function expressed as a discretized path integral, we introduce a change of integration variables often used in the derivation of trajectory-based semiclassical methods. In particular, we transform to sum and difference variables between forward and backward complex-time propagation paths. Once the transformation is performed, the potential energy is expanded in powers of the difference variables, which allows us to perform the integrals over these variables analytically. The manner in which this procedure is carried out results in an open-chain path integral (in the remaining sum variables) with a modified potential that is evaluated using imaginary-time path-integral sampling rather than requiring the generation of a large ensemble of trajectories. Consequently, any number of path integral sampling schemes can be employed to compute the remaining path integral, including Monte Carlo, path-integral molecular dynamics, or enhanced path-integral molecular dynamics. We believe that this approach constitutes a different perspective in semiclassical-type approximations to quantum time correlation functions. Importantly, we argue that our approximation can be systematically improved within a cumulant expansion formalism. We test this approximation on a set of one-dimensional problems that are commonly used to benchmark approximate quantum dynamical schemes. We show that the method is at least as accurate as the popular ring-polymer molecular dynamics technique and linearized semiclassical initial value representation for correlation functions of linear operators in most of these examples and improves the accuracy of correlation functions of nonlinear operators.

  20. Adaptive enhanced sampling with a path-variable for the simulation of protein folding and aggregation

    Science.gov (United States)

    Peter, Emanuel K.

    2017-12-01

    In this article, we present a novel adaptive enhanced sampling molecular dynamics (MD) method for the accelerated simulation of protein folding and aggregation. We introduce a path-variable L based on the un-biased momenta p and displacements dq for the definition of the bias s applied to the system and derive 3 algorithms: general adaptive bias MD, adaptive path-sampling, and a hybrid method which combines the first 2 methodologies. Through the analysis of the correlations between the bias and the un-biased gradient in the system, we find that the hybrid methodology leads to an improved force correlation and acceleration in the sampling of the phase space. We apply our method on SPC/E water, where we find a conservation of the average water structure. We then use our method to sample dialanine and the folding of TrpCage, where we find a good agreement with simulation data reported in the literature. Finally, we apply our methodologies on the initial stages of aggregation of a hexamer of Alzheimer's amyloid β fragment 25-35 (Aβ 25-35) and find that transitions within the hexameric aggregate are dominated by entropic barriers, while we speculate that especially the conformation entropy plays a major role in the formation of the fibril as a rate limiting factor.

  1. Evaluation of diesel particulate matter sampling techniques

    CSIR Research Space (South Africa)

    Pretorius, CJ

    2011-09-01

    Full Text Available The study evaluated diesel particulate matter (DPM) sampling methods used in the South African mining industry. The three-piece cassette respirable, open face and stopper sampling methods were compared with the SKC DPM cassette method to find a...

  2. Quality-of-Service Routing Using Path and Power Aware Techniques in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    R. Asokan

    2008-01-01

    Full Text Available Mobile ad hoc network (MANET is a collection of wireless mobile hosts dynamically forming a temporary network without the aid of any existing established infrastructure. Quality of service (QoS is a set of service requirements that needs to be met by the network while transporting a packet stream from a source to its destination. QoS support MANETs is a challenging task due to the dynamic topology and limited resources. The main objective of this paper is to enhance the QoS routing for MANET using temporally ordered routing algorithm (TORA with self-healing and optimized routing techniques (SHORT. SHORT improves routing optimality by monitoring routing paths continuously and redirecting the path whenever a shortcut path is available. In this paper, the performance comparison of TORA and TORA with SHORT has been analyzed using network simulator for various parameters. TORA with SHORT enhances performance of TORA in terms of throughput, packet loss, end-to-end delay, and energy.

  3. Judgments in the selection of path generation techniques: a meta-analytic approach

    DEFF Research Database (Denmark)

    Prato, Carlo Giacomo

    2012-01-01

    objective judgments for effective route choice set generation. Initially, path generation techniques are implemented within a synthetic network to generate possible subjective choice sets considered by travelers. Next, “true model estimates” and “postulated predicted routes” are assumed from the simulation...... of a route choice model. Then, objective choice sets are applied for model estimation and results are compared to the “true model estimates”. Last, predictions from the simulation of models estimated with objective choice sets are compared to the “postulated predicted routes”. Meta-analysis allows...

  4. Development of sampling techniques for ITER Type B radwaste

    International Nuclear Information System (INIS)

    Hong, Kwon Pyo; Kim, Sung Geun; Jung, Sang Hee; Oh, Wan Ho; Park, Myung Chul; Kim, Hee Moon; Ahn, Sang Bok

    2016-01-01

    There are several difficulties and limitation in sampling activities. As the Type B radwaste components are mostly metallic(mostly stainless steel) and bulk(∼ 1 m in size and ∼ 100 mm in thickness), it is difficult in taking samples from the surface of Type B radwaste by remote operation. But also, sampling should be performed without use of any liquid coolant to avoid the spread of contamination. And all sampling procedures are carried in the hot cell red zone with remote operation. Three kinds of sampling techniques are being developed. They are core sampling, chip sampling, and wedge sampling, which are the candidates of sampling techniques to be applied to ITER hot cell. Object materials for sampling are stainless steel or Cu alloy block in order to simulate ITER Type B radwaste. The best sampling technique for ITER Type B radwaste among the three sampling techniques will be suggested in several months after finishing the related experiment

  5. Development of sampling techniques for ITER Type B radwaste

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Kwon Pyo; Kim, Sung Geun; Jung, Sang Hee; Oh, Wan Ho; Park, Myung Chul; Kim, Hee Moon; Ahn, Sang Bok [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    There are several difficulties and limitation in sampling activities. As the Type B radwaste components are mostly metallic(mostly stainless steel) and bulk(∼ 1 m in size and ∼ 100 mm in thickness), it is difficult in taking samples from the surface of Type B radwaste by remote operation. But also, sampling should be performed without use of any liquid coolant to avoid the spread of contamination. And all sampling procedures are carried in the hot cell red zone with remote operation. Three kinds of sampling techniques are being developed. They are core sampling, chip sampling, and wedge sampling, which are the candidates of sampling techniques to be applied to ITER hot cell. Object materials for sampling are stainless steel or Cu alloy block in order to simulate ITER Type B radwaste. The best sampling technique for ITER Type B radwaste among the three sampling techniques will be suggested in several months after finishing the related experiment.

  6. Nuclear techniques for analysis of environmental samples

    International Nuclear Information System (INIS)

    1986-12-01

    The main purposes of this meeting were to establish the state-of-the-art in the field, to identify new research and development that is required to provide an adequate framework for analysis of environmental samples and to assess needs and possibilities for international cooperation in problem areas. This technical report was prepared on the subject based on the contributions made by the participants. A separate abstract was prepared for each of the 9 papers

  7. Automated Prediction of Catalytic Mechanism and Rate Law Using Graph-Based Reaction Path Sampling.

    Science.gov (United States)

    Habershon, Scott

    2016-04-12

    In a recent article [ J. Chem. Phys. 2015 , 143 , 094106 ], we introduced a novel graph-based sampling scheme which can be used to generate chemical reaction paths in many-atom systems in an efficient and highly automated manner. The main goal of this work is to demonstrate how this approach, when combined with direct kinetic modeling, can be used to determine the mechanism and phenomenological rate law of a complex catalytic cycle, namely cobalt-catalyzed hydroformylation of ethene. Our graph-based sampling scheme generates 31 unique chemical products and 32 unique chemical reaction pathways; these sampled structures and reaction paths enable automated construction of a kinetic network model of the catalytic system when combined with density functional theory (DFT) calculations of free energies and resultant transition-state theory rate constants. Direct simulations of this kinetic network across a range of initial reactant concentrations enables determination of both the reaction mechanism and the associated rate law in an automated fashion, without the need for either presupposing a mechanism or making steady-state approximations in kinetic analysis. Most importantly, we find that the reaction mechanism which emerges from these simulations is exactly that originally proposed by Heck and Breslow; furthermore, the simulated rate law is also consistent with previous experimental and computational studies, exhibiting a complex dependence on carbon monoxide pressure. While the inherent errors of using DFT simulations to model chemical reactivity limit the quantitative accuracy of our calculated rates, this work confirms that our automated simulation strategy enables direct analysis of catalytic mechanisms from first principles.

  8. Martian regolith geochemistry and sampling techniques

    Science.gov (United States)

    Clark, B. C.

    Laboratory study of samples of the intermediate and fine-grained regolith, including duricrust peds, is a fundamental prerequisite for understanding the types of physical and chemical weathering processes on Mars. The extraordinary importance of such samples is their relevance to understanding past changes in climate, availability (and possible physical state) of water, eolian forces, the thermal and chemical influences of volcanic and impact processes, and the inventory and fates of Martian volatiles. Fortunately, this regolith material appears to be ubiquitous over the Martian surface, and should be available at many different landing sites. Viking data has been interpreted to indicate a smectite-rich regolith material, implying extensive weathering involving aqueous activity and geochemical alteration. An all-igneous source of the Martian fines has also been proposed. The X-ray fluorescence measurement data set can now be fully explained in terms of a simple two-component model. The first component is silicate, having strong geochemical similarities with Shergottites, but not other SNC meteorites. The second component is salt. Variations in these components could produce silicate and salt-rich beds, the latter being of high potential importance for microenvironments in which liquid water (brines) could exist. It therefore would be desirable to scan the surface of the regolith for such prospects.

  9. Martian regolith geochemistry and sampling techniques

    Science.gov (United States)

    Clark, B. C.

    1988-01-01

    Laboratory study of samples of the intermediate and fine-grained regolith, including duricrust peds, is a fundamental prerequisite for understanding the types of physical and chemical weathering processes on Mars. The extraordinary importance of such samples is their relevance to understanding past changes in climate, availability (and possible physical state) of water, eolian forces, the thermal and chemical influences of volcanic and impact processes, and the inventory and fates of Martian volatiles. Fortunately, this regolith material appears to be ubiquitous over the Martian surface, and should be available at many different landing sites. Viking data has been interpreted to indicate a smectite-rich regolith material, implying extensive weathering involving aqueous activity and geochemical alteration. An all-igneous source of the Martian fines has also been proposed. The X-ray fluorescence measurement data set can now be fully explained in terms of a simple two-component model. The first component is silicate, having strong geochemical similarities with Shergottites, but not other SNC meteorites. The second component is salt. Variations in these components could produce silicate and salt-rich beds, the latter being of high potential importance for microenvironments in which liquid water (brines) could exist. It therefore would be desirable to scan the surface of the regolith for such prospects.

  10. A comparative study of sampling techniques for monitoring carcass contamination

    NARCIS (Netherlands)

    Snijders, J.M.A.; Janssen, M.H.W.; Gerats, G.E.; Corstiaensen, G.P.

    1984-01-01

    Four bacteriological sampling techniques i.e. the excision, double swab, agar contract and modified agar contact techniques were compared by sampling pig carcasses before and after chilling. As well as assessing the advantages and disadvantages of the techniques particular attention was paid to

  11. Petrosal sinus sampling: technique and rationale.

    Science.gov (United States)

    Miller, D L; Doppman, J L

    1991-01-01

    Bilateral simultaneous sampling of the inferior petrosal sinuses is an extremely sensitive, specific, and accurate test for diagnosing Cushing disease and distinguishing between that entity and the ectopic ACTH syndrome. It is also valuable for lateralizing small hormone-producing adenomas within the pituitary gland. The inferior petrosal sinuses connect the cavernous sinuses with the ipsilateral internal jugular veins. The anatomy of the anastomoses between the inferior petrosal sinus, the internal jugular vein, and the venous plexuses at the base of the skull varies, but it is almost always possible to catheterize the inferior petrosal sinus. In addition, variations in size and anatomy are often present between the two inferior petrosal sinuses in a patient. Advance preparation is required for petrosal sinus sampling. Teamwork is a critical element, and each member of the staff should know what he or she will be doing during the procedure. The samples must be properly labeled, processed, and stored. Specific needles, guide wires, and catheters are recommended for this procedure. The procedure is performed with specific attention to the three areas of potential technical difficulty: catheterization of the common femoral veins, crossing the valve at the base of the left internal jugular vein, and selective catheterization of the inferior petrosal sinuses. There are specific methods for dealing with each of these areas. The sine qua non of correct catheter position in the inferior petrosal sinus is demonstration of reflux of contrast material into the ipsilateral cavernous sinus. Images must always be obtained to document correct catheter position. Special attention must be paid to two points to prevent potential complications: The patient must be given an adequate dose of heparin, and injection of contrast material into the inferior petrosal sinuses and surrounding veins must be done gently and carefully. When the procedure is performed as outlined, both inferior

  12. A Novel Randomized Search Technique for Multiple Mobile Robot Paths Planning In Repetitive Dynamic Environment

    Directory of Open Access Journals (Sweden)

    Vahid Behravesh

    2012-08-01

    Full Text Available Presented article is studying the issue of path navigating for numerous robots. Our presented approach is based on both priority and the robust method for path finding in repetitive dynamic. Presented model can be generally implementable and useable: We do not assume any restriction regarding the quantity of levels of freedom for robots, and robots of diverse kinds can be applied at the same time. We proposed a random method and hill-climbing technique in the area based on precedence plans, which is used to determine a solution to a given trajectory planning problem and to make less the extent of total track. Our method plans trajectories for particular robots in the setting-time scope. Therefore, in order to specifying the interval of constant objects similar to other robots and the extent of the tracks which is traversed. For measuring the hazard for robots to conflict with each other it applied a method based on probability of the movements of robots. This algorithm applied to real robots with successful results. The proposed method performed and judged on both real robots and in simulation. We performed sequence of100tests with 8 robots for comparing with coordination method and current performances are effective. However, maximizing the performance is still possible. These performances estimations performed on Windows operating system and 3GHz Intel Pentium IV with and compiles with GCC 3.4. We used our PCGA robot for all experiments.  For a large environment of 19×15m2where we accomplished 40tests, our model is competent to plan high-quality paths in a severely short time (less than a second. Moreover, this article utilized lookup tables to keep expenses the formerly navigated robots made, increasing the number of robots don’t expand computation time.

  13. Another Look at the Mechanisms of Hydride Transfer Enzymes with Quantum and Classical Transition Path Sampling.

    Science.gov (United States)

    Dzierlenga, Michael W; Antoniou, Dimitri; Schwartz, Steven D

    2015-04-02

    The mechanisms involved in enzymatic hydride transfer have been studied for years, but questions remain due, in part, to the difficulty of probing the effects of protein motion and hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and human heart lactate dehydrogenase (LDH). Calculation of the work applied to the hydride allowed for observation of the change in barrier height upon inclusion of quantum dynamics. Similar calculations were performed using deuterium as the transferring particle in order to approximate kinetic isotope effects (KIEs). The change in barrier height in YADH is indicative of a zero-point energy (ZPE) contribution and is evidence that catalysis occurs via a protein compression that mediates a near-barrierless hydride transfer. Calculation of the KIE using the difference in barrier height between the hydride and deuteride agreed well with experimental results.

  14. SEM technique for experimentally locating latch-up paths in integrated circuits

    International Nuclear Information System (INIS)

    Dressendorfer, P.V.; Armendariz, M.G.

    1980-01-01

    A technique is presented for using the scanning electron microscope (SEM) in the electron-beam-induced current (EBIC) mode to delineate latch-up paths in CMOS ICs. In the EBIC mode, the current produced by the collection and separation of the electron-beam-generated electron-hole pairs in the space charge regions of the device is measured and used to form an image. Since the collection of these carriers is dependent on space charge region width (and thus junction potential), anything that alters the depletion layer width will affect the collection efficiency. In a latch condition the junctions involved in the latch will be biased differently from those which are not, and thus the EBIC signal from those regions should be measurably different

  15. Comparison of sampling techniques for use in SYVAC

    International Nuclear Information System (INIS)

    Dalrymple, G.J.

    1984-01-01

    The Stephen Howe review (reference TR-STH-1) recommended the use of a deterministic generator (DG) sampling technique for sampling the input values to the SYVAC (SYstems Variability Analysis Code) program. This technique was compared with Monte Carlo simple random sampling (MC) by taking a 1000 run case of SYVAC using MC as the reference case. The results show that DG appears relatively inaccurate for most values of consequence when used with 11 sample intervals. If 22 sample intervals are used then DG generates cumulative distribution functions that are statistically similar to the reference distribution. 400 runs of DG or MC are adequate to generate a representative cumulative distribution function. The MC technique appears to perform better than DG for the same number of runs. However, the DG predicts higher doses and in view of the importance of generating data in the high dose region this sampling technique with 22 sample intervals is recommended for use in SYVAC. (author)

  16. Comparative CO{sub 2} flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Fumiyoshi (Graduate School of Natural Science and Technology, Okayama Univ., Okayama (Japan); Atmosphere and Ocean Research Inst., Univ. of Tokyo, Tokyo (Japan)), Email: fkondo@aori.u-tokyo.ac.jp; Tsukamoto, Osamu (Graduate School of Natural Science and Technology, Okayama Univ., Okayama (Japan))

    2012-04-15

    Direct comparison of airsea CO{sub 2} fluxes by open-path eddy covariance (OPEC) and closed-path eddy covariance (CPEC) techniques was carried out over the equatorial Pacific Ocean. Previous studies over oceans have shown that the CO{sub 2} flux by OPEC was larger than the bulk CO{sub 2} flux using the gas transfer velocity estimated by the mass balance technique, while the CO{sub 2} flux by CPEC agreed with the bulk CO{sub 2} flux. We investigated a traditional conflict between the CO{sub 2} flux by the eddy covariance technique and the bulk CO{sub 2} flux, and whether the CO{sub 2} fluctuation attenuated using the closed-path analyser can be measured with sufficient time responses to resolve small CO{sub 2} flux over oceans. Our results showed that the closed-path analyser using a short sampling tube and a high volume air pump can be used to measure the small CO{sub 2} fluctuation over the ocean. Further, the underestimated CO{sub 2} flux by CPEC due to the attenuated fluctuation can be corrected by the bandpass covariance method; its contribution was almost identical to that of H{sub 2}O flux. The CO{sub 2} flux by CPEC agreed with the total CO{sub 2} flux by OPEC with density correction; however, both of them are one order of magnitude larger than the bulk CO{sub 2} flux

  17. Comparative CO2 flux measurements by eddy covariance technique using open- and closed-path gas analysers over the equatorial Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Fumiyoshi Kondo

    2012-04-01

    Full Text Available Direct comparison of air–sea CO2 fluxes by open-path eddy covariance (OPEC and closed-path eddy covariance (CPEC techniques was carried out over the equatorial Pacific Ocean. Previous studies over oceans have shown that the CO2 flux by OPEC was larger than the bulk CO2 flux using the gas transfer velocity estimated by the mass balance technique, while the CO2 flux by CPEC agreed with the bulk CO2 flux. We investigated a traditional conflict between the CO2 flux by the eddy covariance technique and the bulk CO2 flux, and whether the CO2 fluctuation attenuated using the closed-path analyser can be measured with sufficient time responses to resolve small CO2 flux over oceans. Our results showed that the closed-path analyser using a short sampling tube and a high volume air pump can be used to measure the small CO2 fluctuation over the ocean. Further, the underestimated CO2 flux by CPEC due to the attenuated fluctuation can be corrected by the bandpass covariance method; its contribution was almost identical to that of H2O flux. The CO2 flux by CPEC agreed with the total CO2 flux by OPEC with density correction; however, both of them are one order of magnitude larger than the bulk CO2 flux.

  18. Prevalence of Human Papillomavirus Infection in Unselected SurePath Samples Using the APTIMA HPV mRNA Assay

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Preisler, Sarah; Ejegod, Ditte M

    2013-01-01

    The APTIMA Human Papillomavirus (HPV) Assay detects E6/E7 mRNA from 14 human papillomavirus genotypes. Horizon was a population-based split-sample study among well-screened women, with an aim to compare APTIMA, Hybrid Capture 2 (HC2), and liquid-based cytology (LBC) using SurePath samples. APTIMA...

  19. Boat sampling technique for assessment of ageing of components

    International Nuclear Information System (INIS)

    Kumar, Kundan; Shyam, T.V.; Kayal, J.N.; Rupani, B.B.

    2006-01-01

    Boat sampling technique (BST) is a surface sampling technique, which has been developed for obtaining, in-situ, metal samples from the surface of an operating component without affecting its operating service life. The BST is non-destructive in nature and the sample is obtained without plastic deformation or without thermal degradation of the parent material. The shape and size of the sample depends upon the shape of the cutter and the surface geometry of the parent material. Miniature test specimens are generated from the sample and the specimens are subjected to various tests, viz. Metallurgical Evaluation, Metallographic Evaluation, Micro-hardness Evaluation, sensitisation test, small punch test etc. to confirm the integrity and assessment of safe operating life of the component. This paper highlights design objective of boat sampling technique, description of sampling module, sampling cutter and its performance evaluation, cutting process, boat samples, operational sequence of sampling module, qualification of sampling module, qualification of sampling technique, qualification of scooped region of the parent material, sample retrieval system, inspection, testing and examination to be carried out on the boat samples and scooped region. (author)

  20. Can an inadequate cervical cytology sample in ThinPrep be converted to a satisfactory sample by processing it with a SurePath preparation?

    Science.gov (United States)

    Sørbye, Sveinung Wergeland; Pedersen, Mette Kristin; Ekeberg, Bente; Williams, Merete E Johansen; Sauer, Torill; Chen, Ying

    2017-01-01

    The Norwegian Cervical Cancer Screening Program recommends screening every 3 years for women between 25 and 69 years of age. There is a large difference in the percentage of unsatisfactory samples between laboratories that use different brands of liquid-based cytology. We wished to examine if inadequate ThinPrep samples could be satisfactory by processing them with the SurePath protocol. A total of 187 inadequate ThinPrep specimens from the Department of Clinical Pathology at University Hospital of North Norway were sent to Akershus University Hospital for conversion to SurePath medium. Ninety-one (48.7%) were processed through the automated "gynecologic" application for cervix cytology samples, and 96 (51.3%) were processed with the "nongynecological" automatic program. Out of 187 samples that had been unsatisfactory by ThinPrep, 93 (49.7%) were satisfactory after being converted to SurePath. The rate of satisfactory cytology was 36.6% and 62.5% for samples run through the "gynecology" program and "nongynecology" program, respectively. Of the 93 samples that became satisfactory after conversion from ThinPrep to SurePath, 80 (86.0%) were screened as normal while 13 samples (14.0%) were given an abnormal diagnosis, which included 5 atypical squamous cells of undetermined significance, 5 low-grade squamous intraepithelial lesion, 2 atypical glandular cells not otherwise specified, and 1 atypical squamous cells cannot exclude high-grade squamous intraepithelial lesion. A total of 2.1% (4/187) of the women got a diagnosis of cervical intraepithelial neoplasia 2 or higher at a later follow-up. Converting cytology samples from ThinPrep to SurePath processing can reduce the number of unsatisfactory samples. The samples should be run through the "nongynecology" program to ensure an adequate number of cells.

  1. New trends in sample preparation techniques for environmental analysis.

    Science.gov (United States)

    Ribeiro, Cláudia; Ribeiro, Ana Rita; Maia, Alexandra S; Gonçalves, Virgínia M F; Tiritan, Maria Elizabeth

    2014-01-01

    Environmental samples include a wide variety of complex matrices, with low concentrations of analytes and presence of several interferences. Sample preparation is a critical step and the main source of uncertainties in the analysis of environmental samples, and it is usually laborious, high cost, time consuming, and polluting. In this context, there is increasing interest in developing faster, cost-effective, and environmentally friendly sample preparation techniques. Recently, new methods have been developed and optimized in order to miniaturize extraction steps, to reduce solvent consumption or become solventless, and to automate systems. This review attempts to present an overview of the fundamentals, procedure, and application of the most recently developed sample preparation techniques for the extraction, cleanup, and concentration of organic pollutants from environmental samples. These techniques include: solid phase microextraction, on-line solid phase extraction, microextraction by packed sorbent, dispersive liquid-liquid microextraction, and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe).

  2. A fracture-controlled path-following technique for phase-field modeling of brittle fracture

    NARCIS (Netherlands)

    Singh, N.; Verhoosel, C.V.; De Borst, R.; Van Brummelen, E.H.

    2016-01-01

    In the phase-field description of brittle fracture, the fracture-surface area can be expressed as a functional of the phase field (or damage field). In this work we study the applicability of this explicit expression as a (non-linear) path-following constraint to robustly track the equilibrium path

  3. Urine sampling techniques in symptomatic primary-care patients

    DEFF Research Database (Denmark)

    Holm, Anne; Aabenhus, Rune

    2016-01-01

    in infection rate between mid-stream-clean-catch, mid-stream-urine and random samples. Conclusions: At present, no evidence suggests that sampling technique affects the accuracy of the microbiological diagnosis in non-pregnant women with symptoms of urinary tract infection in primary care. However......Background: Choice of urine sampling technique in urinary tract infection may impact diagnostic accuracy and thus lead to possible over- or undertreatment. Currently no evidencebased consensus exists regarding correct sampling technique of urine from women with symptoms of urinary tract infection...... a randomized or paired design to compare the result of urine culture obtained with two or more collection techniques in adult, female, non-pregnant patients with symptoms of urinary tract infection. We evaluated quality of the studies and compared accuracy based on dichotomized outcomes. Results: We included...

  4. Cleaning and Cleanliness Verification Techniques for Mars Returned Sample Handling

    Science.gov (United States)

    Mickelson, E. T.; Lindstrom, D. J.; Allton, J. H.; Hittle, J. D.

    2002-01-01

    Precision cleaning and cleanliness verification techniques are examined as a subset of a comprehensive contamination control strategy for a Mars sample return mission. Additional information is contained in the original extended abstract.

  5. Cervical cancer incidence after normal cytological sample in routine screening using SurePath, ThinPrep, and conventional cytology

    DEFF Research Database (Denmark)

    Rozemeijer, Kirsten; Naber, Steffie K; Penning, Corine

    2017-01-01

    of histo- and cytopathology in the Netherlands (PALGA), January 2000 to March 2013.Population Women with 5 924 474 normal screening samples (23 833 123 person years).Exposure Use of SurePath or ThinPrep versus conventional cytology as screening test.Main outcome measure 72 month cumulative incidence...

  6. Constrained approximation of effective generators for multiscale stochastic reaction networks and application to conditioned path sampling

    Energy Technology Data Exchange (ETDEWEB)

    Cotter, Simon L., E-mail: simon.cotter@manchester.ac.uk

    2016-10-15

    Efficient analysis and simulation of multiscale stochastic systems of chemical kinetics is an ongoing area for research, and is the source of many theoretical and computational challenges. In this paper, we present a significant improvement to the constrained approach, which is a method for computing effective dynamics of slowly changing quantities in these systems, but which does not rely on the quasi-steady-state assumption (QSSA). The QSSA can cause errors in the estimation of effective dynamics for systems where the difference in timescales between the “fast” and “slow” variables is not so pronounced. This new application of the constrained approach allows us to compute the effective generator of the slow variables, without the need for expensive stochastic simulations. This is achieved by finding the null space of the generator of the constrained system. For complex systems where this is not possible, or where the constrained subsystem is itself multiscale, the constrained approach can then be applied iteratively. This results in breaking the problem down into finding the solutions to many small eigenvalue problems, which can be efficiently solved using standard methods. Since this methodology does not rely on the quasi steady-state assumption, the effective dynamics that are approximated are highly accurate, and in the case of systems with only monomolecular reactions, are exact. We will demonstrate this with some numerics, and also use the effective generators to sample paths of the slow variables which are conditioned on their endpoints, a task which would be computationally intractable for the generator of the full system.

  7. Mechanistic Insights on Human Phosphoglucomutase Revealed by Transition Path Sampling and Molecular Dynamics Calculations.

    Science.gov (United States)

    Brás, Natércia F; Fernandes, Pedro A; Ramos, Maria J; Schwartz, Steven D

    2018-02-06

    Human α-phosphoglucomutase 1 (α-PGM) catalyzes the isomerization of glucose-1-phosphate into glucose-6-phosphate (G6P) through two sequential phosphoryl transfer steps with a glucose-1,6-bisphosphate (G16P) intermediate. Given that the release of G6P in the gluconeogenesis raises the glucose output levels, α-PGM represents a tempting pharmacological target for type 2 diabetes. Here, we provide the first theoretical study of the catalytic mechanism of human α-PGM. We performed transition-path sampling simulations to unveil the atomic details of the two catalytic chemical steps, which could be key for developing transition state (TS) analogue molecules with inhibitory properties. Our calculations revealed that both steps proceed through a concerted S N 2-like mechanism, with a loose metaphosphate-like TS. Even though experimental data suggests that the two steps are identical, we observed noticeable differences: 1) the transition state ensemble has a well-defined TS region and a late TS for the second step, and 2) larger coordinated protein motions are required to reach the TS of the second step. We have identified key residues (Arg23, Ser117, His118, Lys389), and the Mg 2+ ion that contribute in different ways to the reaction coordinate. Accelerated molecular dynamics simulations suggest that the G16P intermediate may reorient without leaving the enzymatic binding pocket, through significant conformational rearrangements of the G16P and of specific loop regions of the human α-PGM. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Micro and Nano Techniques for the Handling of Biological Samples

    DEFF Research Database (Denmark)

    Micro and Nano Techniques for the Handling of Biological Samples reviews the different techniques available to manipulate and integrate biological materials in a controlled manner, either by sliding them along a surface (2-D manipulation), or by gripping and moving them to a new position (3-D...

  9. Non-terminal blood sampling techniques in guinea pigs.

    Science.gov (United States)

    Birck, Malene M; Tveden-Nyborg, Pernille; Lindblad, Maiken M; Lykkesfeldt, Jens

    2014-10-11

    Guinea pigs possess several biological similarities to humans and are validated experimental animal models(1-3). However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e.g., the saphenous and jugular veins, each technique containing both advantages and disadvantages(4,5). Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals(6). All the described methods have been thoroughly tested and applied for repeated in vivo blood sampling in studies within our research facility.

  10. Sampling techniques for thrips (Thysanoptera: Thripidae) in preflowering tomato.

    Science.gov (United States)

    Joost, P Houston; Riley, David G

    2004-08-01

    Sampling techniques for thrips (Thysanoptera: Thripidae) were compared in preflowering tomato plants at the Coastal Plain Experiment Station in Tifton, GA, in 2000 and 2003, to determine the most effective method of determining abundance of thrips on tomato foliage early in the growing season. Three relative sampling techniques, including a standard insect aspirator, a 946-ml beat cup, and an insect vacuum device, were compared for accuracy to an absolute method and to themselves for precision and efficiency of sampling thrips. Thrips counts of all relative sampling methods were highly correlated (R > 0.92) to the absolute method. The aspirator method was the most accurate compared with the absolute sample according to regression analysis in 2000. In 2003, all sampling methods were considered accurate according to Dunnett's test, but thrips numbers were lower and sample variation was greater than in 2000. In 2000, the beat cup method had the lowest relative variation (RV) or best precision, at 1 and 8 d after transplant (DAT). Only the beat cup method had RV values <25 for all sampling dates. In 2003, the beat cup method had the lowest RV value at 15 and 21 DAT. The beat cup method also was the most efficient method for all sample dates in both years. Frankliniella fusca (Pergande) was the most abundant thrips species on the foliage of preflowering tomato in both years of study at this location. Overall, the best thrips sampling technique tested was the beat cup method in terms of precision and sampling efficiency.

  11. Differences in sampling techniques on total post-mortem tryptase.

    Science.gov (United States)

    Tse, R; Garland, J; Kesha, K; Elstub, H; Cala, A D; Ahn, Y; Stables, S; Palmiere, C

    2017-11-20

    The measurement of mast cell tryptase is commonly used to support the diagnosis of anaphylaxis. In the post-mortem setting, the literature recommends sampling from peripheral blood sources (femoral blood) but does not specify the exact sampling technique. Sampling techniques vary between pathologists, and it is unclear whether different sampling techniques have any impact on post-mortem tryptase levels. The aim of this study is to compare the difference in femoral total post-mortem tryptase levels between two sampling techniques. A 6-month retrospective study comparing femoral total post-mortem tryptase levels between (1) aspirating femoral vessels with a needle and syringe prior to evisceration and (2) femoral vein cut down during evisceration. Twenty cases were identified, with three cases excluded from analysis. There was a statistically significant difference (paired t test, p sampling methods. The clinical significance of this finding and what factors may contribute to it are unclear. When requesting post-mortem tryptase, the pathologist should consider documenting the exact blood collection site and method used for collection. In addition, blood samples acquired by different techniques should not be mixed together and should be analyzed separately if possible.

  12. Simultaneous determination of sample thickness, tilt, and electron mean free path using tomographic tilt images based on Beer-Lambert law.

    Science.gov (United States)

    Yan, Rui; Edwards, Thomas J; Pankratz, Logan M; Kuhn, Richard J; Lanman, Jason K; Liu, Jun; Jiang, Wen

    2015-11-01

    Cryo-electron tomography (cryo-ET) is an emerging technique that can elucidate the architecture of macromolecular complexes and cellular ultrastructure in a near-native state. Some important sample parameters, such as thickness and tilt, are needed for 3-D reconstruction. However, these parameters can currently only be determined using trial 3-D reconstructions. Accurate electron mean free path plays a significant role in modeling image formation process essential for simulation of electron microscopy images and model-based iterative 3-D reconstruction methods; however, their values are voltage and sample dependent and have only been experimentally measured for a limited number of sample conditions. Here, we report a computational method, tomoThickness, based on the Beer-Lambert law, to simultaneously determine the sample thickness, tilt and electron inelastic mean free path by solving an overdetermined nonlinear least square optimization problem utilizing the strong constraints of tilt relationships. The method has been extensively tested with both stained and cryo datasets. The fitted electron mean free paths are consistent with reported experimental measurements. The accurate thickness estimation eliminates the need for a generous assignment of Z-dimension size of the tomogram. Interestingly, we have also found that nearly all samples are a few degrees tilted relative to the electron beam. Compensation of the intrinsic sample tilt can result in horizontal structure and reduced Z-dimension of tomograms. Our fast, pre-reconstruction method can thus provide important sample parameters that can help improve performance of tomographic reconstruction of a wide range of samples. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Design and performance analysis of global path planning techniques for autonomous mobile robots in grid environments

    Directory of Open Access Journals (Sweden)

    Imen Chaari

    2017-03-01

    Full Text Available This article presents the results of the 2-year iroboapp research project that aims at devising path planning algorithms for large grid maps with much faster execution times while tolerating very small slacks with respect to the optimal path. We investigated both exact and heuristic methods. We contributed with the design, analysis, evaluation, implementation and experimentation of several algorithms for grid map path planning for both exact and heuristic methods. We also designed an innovative algorithm called relaxed A-star that has linear complexity with relaxed constraints, which provides near-optimal solutions with an extremely reduced execution time as compared to A-star. We evaluated the performance of the different algorithms and concluded that relaxed A-star is the best path planner as it provides a good trade-off among all the metrics, but we noticed that heuristic methods have good features that can be exploited to improve the solution of the relaxed exact method. This led us to design new hybrid algorithms that combine our relaxed A-star with heuristic methods which improve the solution quality of relaxed A-star at the cost of slightly higher execution time, while remaining much faster than A* for large-scale problems. Finally, we demonstrate how to integrate the relaxed A-star algorithm in the robot operating system as a global path planner and show that it outperforms its default path planner with an execution time 38% faster on average.

  14. Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola

    2012-01-01

    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m...... from eddy-covariance systems featuring short (4 m) and very short (1 m) sampling lines running at the same clover field and show that relative humidity effects persist also for these setups, and should not be neglected. Starting from the work of Ibrom and co-workers, we propose a mixed method...... and correction method proposed here is deemed applicable to closed-path systems featuring a broad range of sampling lines, and indeed applicable also to passive gases as a special case. The methods described in this paper are incorporated, as processing options, in the free and open-source eddy...

  15. Comparison of Decisions Quality of Heuristic Methods with Limited Depth-First Search Techniques in the Graph Shortest Path Problem

    Directory of Open Access Journals (Sweden)

    Vatutin Eduard

    2017-12-01

    Full Text Available The article deals with the problem of analysis of effectiveness of the heuristic methods with limited depth-first search techniques of decision obtaining in the test problem of getting the shortest path in graph. The article briefly describes the group of methods based on the limit of branches number of the combinatorial search tree and limit of analyzed subtree depth used to solve the problem. The methodology of comparing experimental data for the estimation of the quality of solutions based on the performing of computational experiments with samples of graphs with pseudo-random structure and selected vertices and arcs number using the BOINC platform is considered. It also shows description of obtained experimental results which allow to identify the areas of the preferable usage of selected subset of heuristic methods depending on the size of the problem and power of constraints. It is shown that the considered pair of methods is ineffective in the selected problem and significantly inferior to the quality of solutions that are provided by ant colony optimization method and its modification with combinatorial returns.

  16. Comparison of Decisions Quality of Heuristic Methods with Limited Depth-First Search Techniques in the Graph Shortest Path Problem

    Science.gov (United States)

    Vatutin, Eduard

    2017-12-01

    The article deals with the problem of analysis of effectiveness of the heuristic methods with limited depth-first search techniques of decision obtaining in the test problem of getting the shortest path in graph. The article briefly describes the group of methods based on the limit of branches number of the combinatorial search tree and limit of analyzed subtree depth used to solve the problem. The methodology of comparing experimental data for the estimation of the quality of solutions based on the performing of computational experiments with samples of graphs with pseudo-random structure and selected vertices and arcs number using the BOINC platform is considered. It also shows description of obtained experimental results which allow to identify the areas of the preferable usage of selected subset of heuristic methods depending on the size of the problem and power of constraints. It is shown that the considered pair of methods is ineffective in the selected problem and significantly inferior to the quality of solutions that are provided by ant colony optimization method and its modification with combinatorial returns.

  17. Degree distribution of shortest path trees and bias of network sampling algorithms

    NARCIS (Netherlands)

    Bhamidi, S.; Goodman, J.A.; Hofstad, van der R.W.; Komjáthy, J.

    2013-01-01

    In this article, we explicitly derive the limiting distribution of the degree distribution of the shortest path tree from a single source on various random network models with edge weights. We determine the power-law exponent of the degree distribution of this tree and compare it to the degree

  18. Degree distribution of shortest path trees and bias of network sampling algorithms

    NARCIS (Netherlands)

    Bhamidi, S.; Goodman, J.A.; Hofstad, van der R.W.; Komjáthy, J.

    2015-01-01

    In this article, we explicitly derive the limiting degree distribution of the shortest path tree from a single source on various random network models with edge weights. We determine the asymptotics of the degree distribution for large degrees of this tree and compare it to the degree distribution

  19. Non-terminal blood sampling techniques in Guinea pigs

    DEFF Research Database (Denmark)

    Birck, Malene Muusfeldt; Tveden-Nyborg, Pernille; Lindblad, Maiken Marie

    2014-01-01

    Guinea pigs possess several biological similarities to humans and are validated experimental animal models(1-3). However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features...... of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require...... repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e...

  20. Water sampling techniques for continuous monitoring of pesticides in water

    Directory of Open Access Journals (Sweden)

    Šunjka Dragana

    2017-01-01

    Full Text Available Good ecological and chemical status of water represents the most important aim of the Water Framework Directive 2000/60/EC, which implies respect of water quality standards at the level of entire river basin (2008/105/EC and 2013/39/EC. This especially refers to the control of pesticide residues in surface waters. In order to achieve the set goals, a continuous monitoring program that should provide a comprehensive and interrelated overview of water status should be implemented. However, it demands the use of appropriate analysis techniques. Until now, the procedure for sampling and quantification of residual pesticide quantities in aquatic environment was based on the use of traditional sampling techniques that imply periodical collecting of individual samples. However, this type of sampling provides only a snapshot of the situation in regard to the presence of pollutants in water. As an alternative, the technique of passive sampling of pollutants in water, including pesticides has been introduced. Different samplers are available for pesticide sampling in surface water, depending on compounds. The technique itself is based on keeping a device in water over a longer period of time which varies from several days to several weeks, depending on the kind of compound. In this manner, the average concentrations of pollutants dissolved in water during a time period (time-weighted average concentrations, TWA are obtained, which enables monitoring of trends in areal and seasonal variations. The use of these techniques also leads to an increase in sensitivity of analytical methods, considering that pre-concentration of analytes takes place within the sorption medium. However, the use of these techniques for determination of pesticide concentrations in real water environments requires calibration studies for the estimation of sampling rates (Rs. Rs is a volume of water per time, calculated as the product of overall mass transfer coefficient and area of

  1. Triple-Pulse Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement - Novel Lidar Technologies and Techniques with Path to Space

    Science.gov (United States)

    Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta

    2017-01-01

    The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

  2. Assessment of Natural Radioactivity in TENORM Samples Using Different Techniques

    International Nuclear Information System (INIS)

    Salman, Kh.A.; Shahein, A.Y.

    2009-01-01

    In petroleum oil industries, technologically-enhanced, naturally occurring radioactive materials are produced. The presence of TENORM constitutes a significant radiological human health hazard. In the present work, liquid scintillation counting technique was used to determine both 222 Rn and 226 Ra concentrations in TENORM samples, by measuring 222 Rn concentrations in the sample at different intervals of time after preparation. The radiation doses from the TENORM samples were estimated using thermoluminenscent detector (TLD-4000). The estimated radiation doses were found to be proportional to both the measured radiation doses in site and natural activity concentration in the samples that measured with LSC

  3. Application of the Sampling Selection Technique in Approaching Financial Audit

    Directory of Open Access Journals (Sweden)

    Victor Munteanu

    2018-03-01

    Full Text Available In his professional approach, the financial auditor has a wide range of working techniques, including selection techniques. They are applied depending on the nature of the information available to the financial auditor, the manner in which they are presented - paper or electronic format, and, last but not least, the time available. Several techniques are applied, successively or in parallel, to increase the safety of the expressed opinion and to provide the audit report with a solid basis of information. Sampling is used in the phase of control or clarification of the identified error. The main purpose is to corroborate or measure the degree of risk detected following a pertinent analysis. Since the auditor does not have time or means to thoroughly rebuild the information, the sampling technique can provide an effective response to the need for valorization.

  4. New materials for sample preparation techniques in bioanalysis.

    Science.gov (United States)

    Nazario, Carlos Eduardo Domingues; Fumes, Bruno Henrique; da Silva, Meire Ribeiro; Lanças, Fernando Mauro

    2017-02-01

    The analysis of biological samples is a complex and difficult task owing to two basic and complementary issues: the high complexity of most biological matrices and the need to determine minute quantities of active substances and contaminants in such complex sample. To succeed in this endeavor samples are usually subject to three steps of a comprehensive analytical methodological approach: sample preparation, analytes isolation (usually utilizing a chromatographic technique) and qualitative/quantitative analysis (usually with the aid of mass spectrometric tools). Owing to the complex nature of bio-samples, and the very low concentration of the target analytes to be determined, selective sample preparation techniques is mandatory in order to overcome the difficulties imposed by these two constraints. During the last decade new chemical synthesis approaches has been developed and optimized, such as sol-gel and molecularly imprinting technologies, allowing the preparation of novel materials for sample preparation including graphene and derivatives, magnetic materials, ionic liquids, molecularly imprinted polymers, and much more. In this contribution we will review these novel techniques and materials, as well as their application to the bioanalysis niche. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Sample preparation for special PIE-techniques at ITU

    International Nuclear Information System (INIS)

    Toscano, E.H.; Manzel, R.

    2002-01-01

    Several sample preparation techniques were developed and installed in hot cells. The techniques were conceived to evaluate the performance of highly burnt fuel rods and include: (a) a device for the removal of the fuel, (b) a method for the preparation of the specimen ends for the welding of new end caps and for the careful cleaning of samples for Transmission Electron Microscopy and Glow Discharge Mass Spectroscopy, (c) a sample pressurisation device for long term creep tests, and (d) a diameter measuring device for creep or burst samples. Examples of the determination of the mechanical properties, the behaviour under transient conditions and for the assessment of the corrosion behaviour of high burnup cladding materials are presented. (author)

  6. Use of nuclear technique in samples for agricultural purposes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Kerley A. P. de; Sperling, Eduardo Von, E-mail: kerley@ufmg.br, E-mail: kerleyfisica@yahoo.com.br [Department of Sanitary and Environmental Engineering Federal University of Minas Gerais, Belo Horizonte (Brazil); Menezes, Maria Angela B. C.; Jacomino, Vanusa M.F. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-01-15

    The concern related to environment is growing. Due to this, it is needed to determine chemical elements in a large range of concentration. The neutron activation technique (NAA) determines the elemental composition by the measurement of artificial radioactivity in a sample that was submitted to a neutron flux. NAA is a sensitive and accurate technique with low detection limits. An example of application of NAA was the measurement of concentrations of rare earth elements (REE) in waste samples of phosphogypsum (PG) and cerrado soil samples (clayey and sandy soils). Additionally, a soil reference material of the International Atomic Energy Agency (IAEA) was also analyzed. The REE concentration in PG samples was two times higher than those found in national fertilizers, (total of 4,000 mg kg{sup -1}), 154 times greater than the values found in the sandy soil (26 mg kg{sup -1}) and 14 times greater than the in clayey soil (280 mg kg{sup -1}). The experimental results for the reference material were inside the uncertainty of the certified values pointing out the accuracy of the method (95%). The determination of La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Lu in the samples and reference material confirmed the versatility of the technique on REE determination in soil and phosphogypsum samples that are matrices for agricultural interest. (author)

  7. Development of analytical techniques for safeguards environmental samples at JAEA

    International Nuclear Information System (INIS)

    Sakurai, Satoshi; Magara, Masaaki; Usuda, Shigekazu; Watanabe, Kazuo; Esaka, Fumitaka; Hirayama, Fumio; Lee, Chi-Gyu; Yasuda, Kenichiro; Inagawa, Jun; Suzuki, Daisuke; Iguchi, Kazunari; Kokubu, Yoko S.; Miyamoto, Yutaka; Ohzu, Akira

    2007-01-01

    JAEA has been developing, under the auspices of the Ministry of Education, Culture, Sports, Science and Technology of Japan, analytical techniques for ultra-trace amounts of nuclear materials in environmental samples in order to contribute to the strengthened safeguards system. Development of essential techniques for bulk and particle analysis, as well as screening, of the environmental swipe samples has been established as ultra-trace analytical methods of uranium and plutonium. In January 2003, JAEA was qualified, including its quality control system, as a member of the JAEA network analytical laboratories for environmental samples. Since 2004, JAEA has conducted the analysis of domestic and the IAEA samples, through which JAEA's analytical capability has been verified and improved. In parallel, advanced techniques have been developed in order to expand the applicability to the samples of various elemental composition and impurities and to improve analytical accuracy and efficiency. This paper summarizes the trace of the technical development in environmental sample analysis at JAEA, and refers to recent trends of research and development in this field. (author)

  8. Use of nuclear technique in samples for agricultural purposes

    International Nuclear Information System (INIS)

    Oliveira, Kerley A. P. de; Sperling, Eduardo Von; Menezes, Maria Angela B. C.; Jacomino, Vanusa M.F.

    2013-01-01

    The concern related to environment is growing. Due to this, it is needed to determine chemical elements in a large range of concentration. The neutron activation technique (NAA) determines the elemental composition by the measurement of artificial radioactivity in a sample that was submitted to a neutron flux. NAA is a sensitive and accurate technique with low detection limits. An example of application of NAA was the measurement of concentrations of rare earth elements (REE) in waste samples of phosphogypsum (PG) and cerrado soil samples (clayey and sandy soils). Additionally, a soil reference material of the International Atomic Energy Agency (IAEA) was also analyzed. The REE concentration in PG samples was two times higher than those found in national fertilizers, (total of 4,000 mg kg -1 ), 154 times greater than the values found in the sandy soil (26 mg kg -1 ) and 14 times greater than the in clayey soil (280 mg kg -1 ). The experimental results for the reference material were inside the uncertainty of the certified values pointing out the accuracy of the method (95%). The determination of La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Lu in the samples and reference material confirmed the versatility of the technique on REE determination in soil and phosphogypsum samples that are matrices for agricultural interest. (author)

  9. A Counterexample on Sample-Path Optimality in Stable Markov Decision Chains with the Average Reward Criterion

    Czech Academy of Sciences Publication Activity Database

    Cavazos-Cadena, R.; Montes-de-Oca, R.; Sladký, Karel

    2014-01-01

    Roč. 163, č. 2 (2014), s. 674-684 ISSN 0022-3239 Grant - others:PSF Organization(US) 012/300/02; CONACYT (México) and ASCR (Czech Republic)(MX) 171396 Institutional support: RVO:67985556 Keywords : Strong sample-path optimality * Lyapunov function condition * Stationary policy * Expected average reward criterion Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.509, year: 2014 http://library.utia.cas.cz/separaty/2014/E/sladky-0432661.pdf

  10. A Monte Carlo Sampling Technique for Multi-phonon Processes

    Energy Technology Data Exchange (ETDEWEB)

    Hoegberg, Thure

    1961-12-15

    A sampling technique for selecting scattering angle and energy gain in Monte Carlo calculations of neutron thermalization is described. It is supposed that the scattering is separated into processes involving different numbers of phonons. The number of phonons involved is first determined. Scattering angle and energy gain are then chosen by using special properties of the multi-phonon term.

  11. Comparison of sampling techniques for Rift Valley Fever virus ...

    African Journals Online (AJOL)

    We investigated mosquito sampling techniques with two types of traps and attractants at different time for trapping potential vectors for Rift Valley Fever virus. The study was conducted in six villages in Ngorongoro district in Tanzania from September to October 2012. A total of 1814 mosquitoes were collected, of which 738 ...

  12. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Animesh, E-mail: animesh@zedat.fu-berlin.de; Delle Site, Luigi, E-mail: dellesite@fu-berlin.de [Institute for Mathematics, Freie Universität Berlin, Berlin (Germany)

    2015-09-07

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement.

  13. Analytical techniques for measurement of 99Tc in environmental samples

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Three new methods have been developed for measuring 99 Tc in environmental samples. The most sensitive method is isotope dilution mass spectrometry, which allows measurement of about 1 x 10 -12 grams of 99 Tc. Results on analysis of five samples by this method compare very well with values obtained by a second independent method, which involves counting of beta particles from 99 Tc and internal conversion electrons from /sup 97m/Tc. A third method involving electrothermal atomic absorption has also been developed. Although this method is not as sensitive as the first two techniques, the cost per analysis is expected to be considerably less for certain types of samples

  14. Decomposition and (importance) sampling techniques for multi-stage stochastic linear programs

    Energy Technology Data Exchange (ETDEWEB)

    Infanger, G.

    1993-11-01

    The difficulty of solving large-scale multi-stage stochastic linear programs arises from the sheer number of scenarios associated with numerous stochastic parameters. The number of scenarios grows exponentially with the number of stages and problems get easily out of hand even for very moderate numbers of stochastic parameters per stage. Our method combines dual (Benders) decomposition with Monte Carlo sampling techniques. We employ importance sampling to efficiently obtain accurate estimates of both expected future costs and gradients and right-hand sides of cuts. The method enables us to solve practical large-scale problems with many stages and numerous stochastic parameters per stage. We discuss the theory of sharing and adjusting cuts between different scenarios in a stage. We derive probabilistic lower and upper bounds, where we use importance path sampling for the upper bound estimation. Initial numerical results turned out to be promising.

  15. Radioisotope Sample Measurement Techniques in Medicine and Biology. Proceedings of the Symposium on Radioisotope Sample Measurement Techniques

    International Nuclear Information System (INIS)

    1965-01-01

    The medical and biological applications of radioisotopes depend on two basically different types of measurements, those on living subjects in vivo and those on samples in vitro. The International Atomic Energy Agency has in the past held several meetings on in vivo measurement techniques, notably whole-body counting and radioisotope scanning. The present volume contains the Proceedings of the first Symposium the Agency has organized to discuss the various aspects of techniques for sample measurement in vitro. The range of these sample measurement techniques is very wide. The sample may weigh a few milligrams or several hundred grams, and may be in the gaseous, liquid or solid state. Its radioactive content may consist of a single, known radioisotope or several unknown ones. The concentration of radioactivity may be low, medium or high. The measurements may be made manually or automatically and any one of the many radiation detectors now available may be used. The 53 papers presented at the Symposium illustrate the great variety of methods now in use for radioactive- sample measurements. The first topic discussed is gamma-ray spectrometry, which finds an increasing number of applications in sample measurements. Other sections of the Proceedings deal with: the use of computers in gamma-ray spectrometry and multiple tracer techniques; recent developments in activation analysis where both gamma-ray spectrometry and computing techniques are applied; thin-layer and paper radio chromatographic techniques for use with low energy beta-ray emitters; various aspects of liquid scintillation counting techniques in the measurement of alpha- and beta-ray emitters, including chemical and colour quenching; autoradiographic techniques; calibration of equipment; and standardization of radioisotopes. Finally, some applications of solid-state detectors are presented; this section may be regarded as a preview of important future developments. The meeting was attended by 203 participants

  16. Application of digital sampling techniques to particle identification

    International Nuclear Information System (INIS)

    Bardelli, L.; Poggi, G.; Bini, M.; Carraresi, L.; Pasquali, G.; Taccetti, N.

    2003-01-01

    An application of digital sampling techniques is presented which can greatly simplify experiments involving sub-nanosecond time-mark determinations and energy measurements with nuclear detectors, used for Pulse Shape Analysis and Time of Flight measurements in heavy ion experiments. In this work a 100 M Sample/s, 12 bit analog to digital converter has been used: examples of this technique applied to Silicon and CsI(Tl) detectors in heavy-ions experiments involving particle identification via Pulse Shape analysis and Time of Flight measurements are presented. The system is suited for applications to large detector arrays and to different kinds of detectors. Some preliminary results regarding the simulation of current signals in Silicon detectors are also discussed. (authors)

  17. Development of core sampling technique for ITER Type B radwaste

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. G.; Hong, K. P.; Oh, W. H.; Park, M. C.; Jung, S. H.; Ahn, S. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Type B radwaste (intermediate level and long lived radioactive waste) imported from ITER vacuum vessel are to be treated and stored in basement of hot cell building. The Type B radwaste treatment process is composed of buffer storage, cutting, sampling/tritium measurement, tritium removal, characterization, pre-packaging, inspection/decontamination, and storage etc. The cut slices of Type B radwaste components generated from cutting process undergo sampling process before and after tritium removal process. The purpose of sampling is to obtain small pieces of samples in order to investigate the tritium content and concentration of Type B radwaste. Core sampling, which is the candidates of sampling technique to be applied to ITER hot cell, is available for not thick (less than 50 mm) metal without use of coolant. Experimented materials were SS316L and CuCrZr in order to simulate ITER Type B radwaste. In core sampling, substantial secondary wastes from cutting chips will be produced unavoidably. Thus, core sampling machine will have to be equipped with disposal system such as suction equipment. Core sampling is considered an unfavorable method for tool wear compared to conventional drilling.

  18. Manipulation of biological samples using micro and nano techniques.

    Science.gov (United States)

    Castillo, Jaime; Dimaki, Maria; Svendsen, Winnie Edith

    2009-01-01

    The constant interest in handling, integrating and understanding biological systems of interest for the biomedical field, the pharmaceutical industry and the biomaterial researchers demand the use of techniques that allow the manipulation of biological samples causing minimal or no damage to their natural structure. Thanks to the advances in micro- and nanofabrication during the last decades several manipulation techniques offer us the possibility to image, characterize and manipulate biological material in a controlled way. Using these techniques the integration of biomaterials with remarkable properties with physical transducers has been possible, giving rise to new and highly sensitive biosensing devices. This article reviews the different techniques available to manipulate and integrate biological materials in a controlled manner either by sliding them along a surface (2-D manipulation), by grapping them and moving them to a new position (3-D manipulation), or by manipulating and relocating them applying external forces. The advantages and drawbacks are mentioned together with examples that reflect the state of the art of manipulation techniques for biological samples (171 references).

  19. Determination of palladium in biological samples applying nuclear analytical techniques

    International Nuclear Information System (INIS)

    Cavalcante, Cassio Q.; Sato, Ivone M.; Salvador, Vera L. R.; Saiki, Mitiko

    2008-01-01

    This study presents Pd determinations in bovine tissue samples containing palladium prepared in the laboratory, and CCQM-P63 automotive catalyst materials of the Proficiency Test, using instrumental thermal and epithermal neutron activation analysis and energy dispersive X-ray fluorescence techniques. Solvent extraction and solid phase extraction procedures were also applied to separate Pd from interfering elements before the irradiation in the nuclear reactor. The results obtained by different techniques were compared against each other to examine sensitivity, precision and accuracy. (author)

  20. Developing Students' Reasoning about Samples and Sampling Variability as a Path to Expert Statistical Thinking

    Science.gov (United States)

    Garfield, Joan; Le, Laura; Zieffler, Andrew; Ben-Zvi, Dani

    2015-01-01

    This paper describes the importance of developing students' reasoning about samples and sampling variability as a foundation for statistical thinking. Research on expert-novice thinking as well as statistical thinking is reviewed and compared. A case is made that statistical thinking is a type of expert thinking, and as such, research…

  1. Proteomic Challenges: Sample Preparation Techniques for Microgram-Quantity Protein Analysis from Biological Samples

    Science.gov (United States)

    Feist, Peter; Hummon, Amanda B.

    2015-01-01

    Proteins regulate many cellular functions and analyzing the presence and abundance of proteins in biological samples are central focuses in proteomics. The discovery and validation of biomarkers, pathways, and drug targets for various diseases can be accomplished using mass spectrometry-based proteomics. However, with mass-limited samples like tumor biopsies, it can be challenging to obtain sufficient amounts of proteins to generate high-quality mass spectrometric data. Techniques developed for macroscale quantities recover sufficient amounts of protein from milligram quantities of starting material, but sample losses become crippling with these techniques when only microgram amounts of material are available. To combat this challenge, proteomicists have developed micro-scale techniques that are compatible with decreased sample size (100 μg or lower) and still enable excellent proteome coverage. Extraction, contaminant removal, protein quantitation, and sample handling techniques for the microgram protein range are reviewed here, with an emphasis on liquid chromatography and bottom-up mass spectrometry-compatible techniques. Also, a range of biological specimens, including mammalian tissues and model cell culture systems, are discussed. PMID:25664860

  2. Proteomic challenges: sample preparation techniques for microgram-quantity protein analysis from biological samples.

    Science.gov (United States)

    Feist, Peter; Hummon, Amanda B

    2015-02-05

    Proteins regulate many cellular functions and analyzing the presence and abundance of proteins in biological samples are central focuses in proteomics. The discovery and validation of biomarkers, pathways, and drug targets for various diseases can be accomplished using mass spectrometry-based proteomics. However, with mass-limited samples like tumor biopsies, it can be challenging to obtain sufficient amounts of proteins to generate high-quality mass spectrometric data. Techniques developed for macroscale quantities recover sufficient amounts of protein from milligram quantities of starting material, but sample losses become crippling with these techniques when only microgram amounts of material are available. To combat this challenge, proteomicists have developed micro-scale techniques that are compatible with decreased sample size (100 μg or lower) and still enable excellent proteome coverage. Extraction, contaminant removal, protein quantitation, and sample handling techniques for the microgram protein range are reviewed here, with an emphasis on liquid chromatography and bottom-up mass spectrometry-compatible techniques. Also, a range of biological specimens, including mammalian tissues and model cell culture systems, are discussed.

  3. Proteomic Challenges: Sample Preparation Techniques for Microgram-Quantity Protein Analysis from Biological Samples

    Directory of Open Access Journals (Sweden)

    Peter Feist

    2015-02-01

    Full Text Available Proteins regulate many cellular functions and analyzing the presence and abundance of proteins in biological samples are central focuses in proteomics. The discovery and validation of biomarkers, pathways, and drug targets for various diseases can be accomplished using mass spectrometry-based proteomics. However, with mass-limited samples like tumor biopsies, it can be challenging to obtain sufficient amounts of proteins to generate high-quality mass spectrometric data. Techniques developed for macroscale quantities recover sufficient amounts of protein from milligram quantities of starting material, but sample losses become crippling with these techniques when only microgram amounts of material are available. To combat this challenge, proteomicists have developed micro-scale techniques that are compatible with decreased sample size (100 μg or lower and still enable excellent proteome coverage. Extraction, contaminant removal, protein quantitation, and sample handling techniques for the microgram protein range are reviewed here, with an emphasis on liquid chromatography and bottom-up mass spectrometry-compatible techniques. Also, a range of biological specimens, including mammalian tissues and model cell culture systems, are discussed.

  4. Development of environmental sample analysis techniques for safeguards

    International Nuclear Information System (INIS)

    Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka

    1999-01-01

    JAERI has been developing environmental sample analysis techniques for safeguards and preparing a clean chemistry laboratory with clean rooms. Methods to be developed are a bulk analysis and a particle analysis. In the bulk analysis, Inductively-Coupled Plasma Mass Spectrometer or Thermal Ionization Mass Spectrometer are used to measure nuclear materials after chemical treatment of sample. In the particle analysis, Electron Probe Micro Analyzer and Secondary Ion Mass Spectrometer are used for elemental analysis and isotopic analysis, respectively. The design of the clean chemistry laboratory has been carried out and construction will be completed by the end of March, 2001. (author)

  5. Nuclear analytical techniques and their application to environmental samples

    International Nuclear Information System (INIS)

    Lieser, K.H.

    1986-01-01

    A survey is given on nuclear analytical techniques and their application to environmental samples. Measurement of the inherent radioactivity of elements or radionuclides allows determination of natural radioelements (e.g. Ra), man-made radioelements (e.g. Pu) and radionuclides in the environment. Activation analysis, in particular instrumental neutron activation analysis, is a very reliable and sensitive method for determination of a great number of trace elements in environmental samples, because the most abundant main constituents are not activated. Tracer techniques are very useful for studies of the behaviour and of chemical reactions of trace elements and compounds in the environment. Radioactive sources are mainly applied for excitation of characteristic X-rays (X-ray fluorescence analysis). (author)

  6. Column carbon dioxide and water vapor measurements by an airborne triple-pulse integrated path differential absorption lidar: novel lidar technologies and techniques with path to space

    Science.gov (United States)

    Singh, U. N.; Petros, M.; Refaat, T. F.; Yu, J.; Ismail, S.

    2017-09-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO2) and water vapor (XH2O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

  7. Improved mesh based photon sampling techniques for neutron activation analysis

    International Nuclear Information System (INIS)

    Relson, E.; Wilson, P. P. H.; Biondo, E. D.

    2013-01-01

    The design of fusion power systems requires analysis of neutron activation of large, complex volumes, and the resulting particles emitted from these volumes. Structured mesh-based discretization of these problems allows for improved modeling in these activation analysis problems. Finer discretization of these problems results in large computational costs, which drives the investigation of more efficient methods. Within an ad hoc subroutine of the Monte Carlo transport code MCNP, we implement sampling of voxels and photon energies for volumetric sources using the alias method. The alias method enables efficient sampling of a discrete probability distribution, and operates in 0(1) time, whereas the simpler direct discrete method requires 0(log(n)) time. By using the alias method, voxel sampling becomes a viable alternative to sampling space with the 0(1) approach of uniformly sampling the problem volume. Additionally, with voxel sampling it is straightforward to introduce biasing of volumetric sources, and we implement this biasing of voxels as an additional variance reduction technique that can be applied. We verify our implementation and compare the alias method, with and without biasing, to direct discrete sampling of voxels, and to uniform sampling. We study the behavior of source biasing in a second set of tests and find trends between improvements and source shape, material, and material density. Overall, however, the magnitude of improvements from source biasing appears to be limited. Future work will benefit from the implementation of efficient voxel sampling - particularly with conformal unstructured meshes where the uniform sampling approach cannot be applied. (authors)

  8. A Comparison of Soil-Water Sampling Techniques

    Science.gov (United States)

    Tindall, J. A.; Figueroa-Johnson, M.; Friedel, M. J.

    2007-12-01

    The representativeness of soil pore water extracted by suction lysimeters in ground-water monitoring studies is a problem that often confounds interpretation of measured data. Current soil water sampling techniques cannot identify the soil volume from which a pore water sample is extracted, neither macroscopic, microscopic, or preferential flowpath. This research was undertaken to compare values of extracted suction lysimeters samples from intact soil cores with samples obtained by the direct extraction methods to determine what portion of soil pore water is sampled by each method. Intact soil cores (30 centimeter (cm) diameter by 40 cm height) were extracted from two different sites - a sandy soil near Altamonte Springs, Florida and a clayey soil near Centralia in Boone County, Missouri. Isotopically labeled water (O18? - analyzed by mass spectrometry) and bromide concentrations (KBr- - measured using ion chromatography) from water samples taken by suction lysimeters was compared with samples obtained by direct extraction methods of centrifugation and azeotropic distillation. Water samples collected by direct extraction were about 0.25 ? more negative (depleted) than that collected by suction lysimeter values from a sandy soil and about 2-7 ? more negative from a well structured clayey soil. Results indicate that the majority of soil water in well-structured soil is strongly bound to soil grain surfaces and is not easily sampled by suction lysimeters. In cases where a sufficient volume of water has passed through the soil profile and displaced previous pore water, suction lysimeters will collect a representative sample of soil pore water from the sampled depth interval. It is suggested that for stable isotope studies monitoring precipitation and soil water, suction lysimeter should be installed at shallow depths (10 cm). Samples should also be coordinated with precipitation events. The data also indicate that each extraction method be use to sample a different

  9. Comparison of correlation analysis techniques for irregularly sampled time series

    Directory of Open Access Journals (Sweden)

    K. Rehfeld

    2011-06-01

    Full Text Available Geoscientific measurements often provide time series with irregular time sampling, requiring either data reconstruction (interpolation or sophisticated methods to handle irregular sampling. We compare the linear interpolation technique and different approaches for analyzing the correlation functions and persistence of irregularly sampled time series, as Lomb-Scargle Fourier transformation and kernel-based methods. In a thorough benchmark test we investigate the performance of these techniques.

    All methods have comparable root mean square errors (RMSEs for low skewness of the inter-observation time distribution. For high skewness, very irregular data, interpolation bias and RMSE increase strongly. We find a 40 % lower RMSE for the lag-1 autocorrelation function (ACF for the Gaussian kernel method vs. the linear interpolation scheme,in the analysis of highly irregular time series. For the cross correlation function (CCF the RMSE is then lower by 60 %. The application of the Lomb-Scargle technique gave results comparable to the kernel methods for the univariate, but poorer results in the bivariate case. Especially the high-frequency components of the signal, where classical methods show a strong bias in ACF and CCF magnitude, are preserved when using the kernel methods.

    We illustrate the performances of interpolation vs. Gaussian kernel method by applying both to paleo-data from four locations, reflecting late Holocene Asian monsoon variability as derived from speleothem δ18O measurements. Cross correlation results are similar for both methods, which we attribute to the long time scales of the common variability. The persistence time (memory is strongly overestimated when using the standard, interpolation-based, approach. Hence, the Gaussian kernel is a reliable and more robust estimator with significant advantages compared to other techniques and suitable for large scale application to paleo-data.

  10. Separation Techniques for Quantification of Radionuclides in Environmental Samples

    Directory of Open Access Journals (Sweden)

    Dusan Galanda

    2009-01-01

    Full Text Available The reliable and quantitative measurement of radionuclides is important in order to determine environmental quality and radiation safety, and to monitor regulatory compliance. We examined soil samples from Podunajske Biskupice, near the city of Bratislava in the Slovak Republic, for the presence of several natural (238U, 232Th, 40K and anthropogenic (137Cs, 90Sr, 239Pu, 240Pu, 241Am radionuclides. The area is adjacent to a refinery and hazardous waste processing center, as well as the municipal incinerator plant, and so might possess an unusually high level of ecotoxic metals. We found that the levels of both naturally occurring and anthropogenic radionuclides fell within the expected ranges, indicating that these facilities pose no radiological threat to the local environment. During the course of our analysis, we modified existing techniques in order to allow us to handle the unusually large and complex samples that were needed to determine the levels of 239Pu, 240Pu, and 241Am activity. We also rated three commercial techniques for the separation of 90Sr from aqueous solutions and found that two of them, AnaLig Sr-01 and Empore Extraction Disks, were suitable for the quantitative and reliable separation of 90Sr, while the third, Sr-Spec Resin, was less so. The main criterion in evaluating these methods was the chemical recovery of 90Sr, which was less than we had expected. We also considered speed of separation and additional steps needed to prepare the sample for separation.

  11. The path of least resistance: Regulatory resource depletion and the effectiveness of social influence techniques

    NARCIS (Netherlands)

    Janssen, L.; Fennis, B.M.; Pruyn, Adriaan T.H.; Vohs, Kathleen D.

    2008-01-01

    Two experiments examine the role of regulatory resource depletion in the effectiveness of social influence techniques aimed at inducing consumer compliance. They test the two-step hypothesis that a) responding to the initial request stage of an influence technique requires self-control, thereby

  12. Nonactivation interaction techniques in the analysis of environmental samples

    International Nuclear Information System (INIS)

    Tolgyessy, J.

    1986-01-01

    Nonactivation interaction analytical methods are based on the interaction processes of nuclear and X-ray radiation with a sample, leading to their absorption and backscattering, to the ionization of gases or excitation of fluorescent X-ray by radiation, but not to the activation of determined elements. From the point of view of environmental analysis, the most useful nonactivation interaction techniques are X-ray fluorescence by photon or charged particle excitation, ionization of gases by nuclear radiation, elastic scattering of charged particles and backscattering of beta radiation. The significant advantage of these methods is that they are nondestructive. (author)

  13. Waste minimization in analytical chemistry through innovative sample preparation techniques

    International Nuclear Information System (INIS)

    Smith, L. L.

    1998-01-01

    water samples. In this SPME technique, a fused-silica fiber coated with a polymeric film is exposed to the sample, extraction is allowed to take place, and then the analytes are thermally desorbed for GC analysis. Unlike liquid-liquid extraction or solid-phase extraction, SPME consumes all of the extracted sample in the analysis, significantly reducing the required sample volume

  14. Stratified source-sampling techniques for Monte Carlo eigenvalue analysis

    International Nuclear Information System (INIS)

    Mohamed, A.

    1998-01-01

    In 1995, at a conference on criticality safety, a special session was devoted to the Monte Carlo ''Eigenvalue of the World'' problem. Argonne presented a paper, at that session, in which the anomalies originally observed in that problem were reproduced in a much simplified model-problem configuration, and removed by a version of stratified source-sampling. In this paper, stratified source-sampling techniques are generalized and applied to three different Eigenvalue of the World configurations which take into account real-world statistical noise sources not included in the model problem, but which differ in the amount of neutronic coupling among the constituents of each configuration. It is concluded that, in Monte Carlo eigenvalue analysis of loosely-coupled arrays, the use of stratified source-sampling reduces the probability of encountering an anomalous result over that if conventional source-sampling methods are used. However, this gain in reliability is substantially less than that observed in the model-problem results

  15. Hybrid Capture 2 and cobas human papillomavirus assays perform similarly on SurePath samples from women with abnormalities

    DEFF Research Database (Denmark)

    Fornari, D; Rebolj, M; Bjerregaard, B

    2016-01-01

    OBJECTIVE: In two laboratories (Departments of Pathology, Copenhagen University Hospitals of Herlev and Hvidovre), we compared cobas and Hybrid Capture 2 (HC2) human papillomavirus (HPV) assays using SurePath® samples from women with atypical squamous cells of undetermined significance (ASCUS......) at ≥30 years and women after treatment of cervical intraepithelial neoplasia (CIN). METHODS: Samples from 566 women with ASCUS and 411 women after treatment were routinely tested with HC2 and, thereafter, with cobas. Histological outcomes were retrieved from the Danish Pathology Data Base. We calculated...... the overall agreement between the assays, and compared their sensitivity and specificity for ≥CIN2. RESULTS: In women with ASCUS, HC2 and cobas testing results were similar in the two laboratories. The overall agreement was 91% (95% CI, 88-93). After CIN treatment, the overall agreement was 87% (95% CI, 82...

  16. A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data

    Science.gov (United States)

    2013-06-26

    representation of the scattering problem, to within the computational tolerance specified, unlike approximate methods such as physical or geometric optics...above expression is useful in providing an understanding of MOMI from a physical perspective, that is by iteratively scattering forwards and backwards...electromagnetic wavelength λ [82]. Pr = Pt AtAr λ2r2 (6.9) Antenna theory likewise has a well established identity relating the quantities of effective

  17. Identification of unknown sample using NAA, EDXRF, XRD techniques

    International Nuclear Information System (INIS)

    Dalvi, Aditi A.; Swain, K.K.; Chavan, Trupti; Remya Devi, P.S.; Wagh, D.N.; Verma, R.

    2015-01-01

    Analytical Chemistry Division (ACD), Bhabha Atomic Research Centre (BARC) receives samples from law enforcement agencies such as Directorate of Revenue Intelligence, Customs for analysis. Five unknown grey powdered samples were received for identification and were suspected to be Iridium (Ir). Identification of unknown sample is always a challenging task and suitable analytical techniques have to be judiciously utilized for arriving at the conclusion. Qualitative analysis was carried out using Jordan Valley, EX-3600 M Energy dispersive X-ray fluorescence (EDXRF) spectrometer at ACD, BARC. A SLP series LEO Si (Li) detector (active area: 30 mm 2 ; thickness: 3.5 mm; resolution: 140 eV at 5.9 keV of Mn K X-ray) was used during the measurement and only characteristic X-rays of Ir (Lα: 9.17 keV and Lβ: 10.70 keV) was seen in the X-ray spectrum. X-ray diffraction (XRD) measurement results indicated that the Ir was in the form of metal. To confirm the XRD data, neutron activation analysis (NAA) was carried out by irradiating samples and elemental standards (as comparator) in graphite reflector position of Advanced Heavy Water Reactor Critical Facility (AHWR CF) reactor, BARC, Mumbai. After suitable decay period, gamma activity measurements were carried out using 45% HPGe detector coupled to 8 k multi channel analyzer. Characteristic gamma line at 328.4 keV of the activation product 194 Ir was used for quantification of iridium and relative method of NAA was used for concentration calculations. NAA results confirmed that all the samples were Iridium metal. (author)

  18. Water stable isotope measurements of Antarctic samples by means of IRMS and WS-CRDS techniques

    Science.gov (United States)

    Michelini, Marzia; Bonazza, Mattia; Braida, Martina; Flora, Onelio; Dreossi, Giuliano; Stenni, Barbara

    2010-05-01

    In the last years in the scientific community there has been an increasing interest for the application of stable isotope techniques to several environmental problems such as drinking water safeguarding, groundwater management, climate change, soils and paleoclimate studies etc. For example, the water stable isotopes, being natural tracers of the hydrological cycle, have been extensively used as tools to characterize regional aquifers and to reconstruct past temperature changes from polar ice cores. Here the need for improvements in analytical techniques: the high request for information calls for technologies that can offer a great quantity of analyses in short times and with low costs. Furthermore, sometimes it is difficult to obtain big amount of samples (as is the case for Antarctic ice cores or interstitial water) preventing the possibility to replicate the analyses. Here, we present oxygen and hydrogen measurements performed on water samples covering a big range of isotopic values (from very negative antarctic precipitation to mid-latitude precipitation values) carried out with both the conventional Isotope Ratio Mass Spectrometry (IRMS) technique and with a new method based on laser absorption techniques, the Wavelenght Scanned Cavity Ringdown Spectroscopy (WS-CRDS). This study is focusing on improving the precision of the measurements carried out with WS-CRDS in order to extensively apply this method to Antarctic ice core paleoclimate studies. The WS-CRDS is a variation of the CRDS developed in 1988 by O'Keef and Deacon. In CRDS a pulse of light goes through a box with high reflective inner surfaces; when there is no sample in the box the light beam doesn't find any obstacle in its path, but the reflectivity of the walls is not perfect so eventually there will be an absorption of the light beam; when the sample is injected in the box there is absorption and the difference between the time of absorption without and with sample is proportional to the quantity

  19. Particle filtering with path sampling and an application to a bimodal ocean current model

    International Nuclear Information System (INIS)

    Weare, Jonathan

    2009-01-01

    This paper introduces a recursive particle filtering algorithm designed to filter high dimensional systems with complicated non-linear and non-Gaussian effects. The method incorporates a parallel marginalization (PMMC) step in conjunction with the hybrid Monte Carlo (HMC) scheme to improve samples generated by standard particle filters. Parallel marginalization is an efficient Markov chain Monte Carlo (MCMC) strategy that uses lower dimensional approximate marginal distributions of the target distribution to accelerate equilibration. As a validation the algorithm is tested on a 2516 dimensional, bimodal, stochastic model motivated by the Kuroshio current that runs along the Japanese coast. The results of this test indicate that the method is an attractive alternative for problems that require the generality of a particle filter but have been inaccessible due to the limitations of standard particle filtering strategies.

  20. Elemental analysis of brazing alloy samples by neutron activation technique

    International Nuclear Information System (INIS)

    Eissa, E.A.; Rofail, N.B.; Hassan, A.M.; El-Shershaby, A.; Walley El-Dine, N.

    1996-01-01

    Two brazing alloy samples (C P 2 and C P 3 ) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 10 1 1 n/cm 2 /s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 10 1 2 n/cm 2 /s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab

  1. Analysis of soil samples from Gebeng area using NAA technique

    Science.gov (United States)

    Elias, Md Suhaimi; Wo, Yii Mei; Hamzah, Mohd Suhaimi; Shukor, Shakirah Abd; Rahman, Shamsiah Ab; Salim, Nazaratul Ashifa Abdullah; Azman, Muhamad Azfar; Hashim, Azian

    2017-01-01

    Rapid development and urbanization will increase number of residence and industrial area. Without proper management and control of pollution, these will give an adverse effect to environment and human life. The objective of this study to identify and quantify key contaminants into the environment of the Gebeng area as a result of industrial and human activities. Gebeng area was gazetted as one of the industrial estate in Pahang state. Assessment of elemental pollution in soil of Gebeng area base on level of concentration, enrichment factor and geo-accumulation index. The enrichment factors (EFs) were determined by the elemental rationing method, whilst the geo-accumulation index (Igeo) by comparing of current to continental crustal average concentration of element. Twenty-seven of soil samples were collected from Gebeng area. Soil samples were analysed by using Neutron Activation Analyses (NAA) technique. The obtained data showed higher concentration of iron (Fe) due to abundance in soil compared to other elements. The results of enrichment factor showed that Gebeng area have enrich with elements of As, Br, Hf, Sb, Th and U. Base on the geo-accumulation index (Igeo) classification, the soil quality of Gebeng area can be classified as class 0, (uncontaminated) to Class 3, (moderately to heavily contaminated).

  2. Elemental analysis of brazing alloy samples by neutron activation technique

    Energy Technology Data Exchange (ETDEWEB)

    Eissa, E A; Rofail, N B; Hassan, A M [Reactor and Neutron physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt); El-Shershaby, A; Walley El-Dine, N [Physics Department, Faculty of Girls, Ain Shams Universty, Cairo (Egypt)

    1997-12-31

    Two brazing alloy samples (C P{sup 2} and C P{sup 3}) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 10{sup 1}1 n/cm{sup 2}/s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 10{sup 1}2 n/cm{sup 2}/s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab.

  3. Lectures on 2d gauge theories. Topological aspects and path integral techniques

    International Nuclear Information System (INIS)

    Blau, M.; Thompson, G.

    1993-10-01

    In these lectures are discussed two classes of two-dimensional field theories which are not obviously topological, but which nevertheless exhibit an intriguing equivalence with certain topological theories. These classes are two-dimensional Yang-Mills theory and the so-called G/G gauged Wess-Zumino-Witten model. The aim is to exhibit and extract the topological information contained in these theories and to present a technique which allows to calculate directly their partition functions and topological correlation functions on arbitrary closed surfaces. 34 refs

  4. Active sampling technique to enhance chemical signature of buried explosives

    Science.gov (United States)

    Lovell, John S.; French, Patrick D.

    2004-09-01

    Deminers and dismounted countermine engineers commonly use metal detectors, ground penetrating radar and probes to locate mines. Many modern landmines have a very low metal content, which severely limits the effectiveness of metal detectors. Canines have also been used for landmine detection for decades. Experiments have shown that canines smell the explosives which are known to leak from most types of landmines. The fact that dogs can detect landmines indicates that vapor sensing is a viable approach to landmine detection. Several groups are currently developing systems to detect landmines by "sniffing" for the ultra-trace explosive vapors above the soil. The amount of material that is available to passive vapor sensing systems is limited to no more than the vapor in equilibrium with the explosive related chemicals (ERCs) distributed in the surface soils over and near the landmine. The low equilibrium vapor pressure of TNT in the soil/atmosphere boundary layer and the limited volume of the boundary layer air imply that passive chemical vapor sensing systems require sensitivities in the picogram range, or lower. ADA is working to overcome many of the limitations of passive sampling methods, by the use of an active sampling method that employs a high-powered (1,200+ joules) strobe lamp to create a highly amplified plume of vapor and/or ERC-bearing fine particulates. Initial investigations have demonstrated that this approach can amplify the detectability of TNT by two or three orders of magnitude. This new active sampling technique could be used with any suitable explosive sensor.

  5. Redundant manipulator techniques for partially decentralized path planning and control of a platoon of autonomous vehicles.

    Science.gov (United States)

    Stilwell, Daniel J; Bishop, Bradley E; Sylvester, Caleb A

    2005-08-01

    An approach to real-time trajectory generation for platoons of autonomous vehicles is developed from well-known control techniques for redundant robotic manipulators. The partially decentralized structure of this approach permits each vehicle to independently compute its trajectory in real-time using only locally generated information and low-bandwidth feedback generated by a system exogenous to the platoon. Our work is motivated by applications for which communications bandwidth is severely limited, such for platoons of autonomous underwater vehicles. The communication requirements for our trajectory generation approach are independent of the number of vehicles in the platoon, enabling platoons composed of a large number of vehicles to be coordinated despite limited communication bandwidth.

  6. Development of analytical techniques for water and environmental samples (2)

    Energy Technology Data Exchange (ETDEWEB)

    Eum, Chul Hun; Jeon, Chi Wan; Jung, Kang Sup; Song, Kyung Sun; Kim, Sang Yeon [Korea Institute of Geology Mining and Materials, Taejon (Korea)

    1998-12-01

    The purpose of this study is to develop new analytical methods with good detection limit for toxic inorganic and organic compounds. The analyses of CN, organic acids, particulate materials in environmental samples have been done using several methods such as Ion Chromatography, SPE, SPME, GC/MS, GC/FID, SPLITT (split-flow thin cell fractionation) during the second year of this project. Advantage and disadvantage of several distillation method (by KS, JIS, EPA) for CN analysis in wastewater were investigated. As the results, we proposed new distillation apparatus for CN analysis, which was proved to be simpler, faster and to get better recovery than conventional apparatus. And ion chromatograph/pulsed amperometric detector (IC/PAD) system instead of colorimetry for CN detection was setup to solve matrix interference. And SPE(solid phase extraction) and SPME (solid phase micro extraction) as liquid-solid extraction technique were applied to the analysis of phenols in wastewater. Optimum experimental conditions and factors influencing analytical results were determined. From these results, It could be concluded that C{sub 18} cartridge and polystyrene-divinylbenzene disk in SPE method, polyacrylate fiber in SPME were proper solid phase adsorbent for phenol. Optimum conditions to analyze phenol derivatives simultaneously were established. Also, Continuous SPLITT (Split-flow thin cell) Fractionation (CSF) is a new preparative separation technique that is useful for fractionation of particulate and macromolecular materials. CSF is carried out in a thin ribbon-like channel equipped with two splitters at both inlet and outlet of the channel. In this work, we set up a new CSF system, and tested using polystyrene latex standard particles. And then we fractionated particles contained in air and underground water based on their sedimentation coefficients using CSF. (author). 27 refs., 13 tabs., 31 figs.

  7. Voltammetric technique, a panacea for analytical examination of environmental samples

    International Nuclear Information System (INIS)

    Zahir, E.; Mohiuddin, S.; Naqvi, I.I.

    2012-01-01

    Voltammetric methods for trace metal analysis in environmental samples of marine origin like mangrove, sediments and shrimps are generally recommended. Three different electro-analytical techniques i.e. polarography, anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (ADSV) have been used. Cd/sub 2/+, Pb/sub 2/+, Cu/sub 2/+ and Mn/sub 2/+ were determined through ASV, Cr/sub 6/+ was analyzed by ADSV and Fe/sub 2/+, Zn/sub 2/+, Ni/sub 2/+ and Co/sub 2/+ were determined through polarography. Out of which pairs of Fe/sub 2/+Zn/sub 2/+ and Ni/sub 2/+Co/sub 2/+ were determined in two separate runs while Cd/sub 2/+, Pb/sub 2/+, Cu/sub 2/+ were analyzed in single run of ASV. Sensitivity and speciation capabilities of voltammetric methods have been employed. Analysis conditions were optimized that includes selection of supporting electrolyte, pH, working electrodes, sweep rate etc. Stripping voltammetry was adopted for analysis at ultra trace levels. Statistical parameters for analytical method development like selectivity factor, interference, repeatability (0.0065-0.130 macro g/g), reproducibility (0.08125-1.625 macro g/g), detection limits (0.032-5.06 macro g/g), limits of quantification (0.081-12.652 macro g/g), sensitivities (5.636-2.15 nA mL macro g-1) etc. were also determined. The percentage recoveries were found in between 95-105% using certified reference materials. Real samples of complex marine environment from Karachi coastline were also analyzed. The standard addition method was employed where any matrix effect was evidenced. (author)

  8. Macro elemental analysis of food samples by nuclear analytical technique

    Science.gov (United States)

    Syahfitri, W. Y. N.; Kurniawati, S.; Adventini, N.; Damastuti, E.; Lestiani, D. D.

    2017-06-01

    Energy-dispersive X-ray fluorescence (EDXRF) spectrometry is a non-destructive, rapid, multi elemental, accurate, and environment friendly analysis compared with other detection methods. Thus, EDXRF spectrometry is applicable for food inspection. The macro elements calcium and potassium constitute important nutrients required by the human body for optimal physiological functions. Therefore, the determination of Ca and K content in various foods needs to be done. The aim of this work is to demonstrate the applicability of EDXRF for food analysis. The analytical performance of non-destructive EDXRF was compared with other analytical techniques; neutron activation analysis and atomic absorption spectrometry. Comparison of methods performed as cross checking results of the analysis and to overcome the limitations of the three methods. Analysis results showed that Ca found in food using EDXRF and AAS were not significantly different with p-value 0.9687, whereas p-value of K between EDXRF and NAA is 0.6575. The correlation between those results was also examined. The Pearson correlations for Ca and K were 0.9871 and 0.9558, respectively. Method validation using SRM NIST 1548a Typical Diet was also applied. The results showed good agreement between methods; therefore EDXRF method can be used as an alternative method for the determination of Ca and K in food samples.

  9. APTIMA assay on SurePath liquid-based cervical samples compared to endocervical swab samples facilitated by a real time database

    Directory of Open Access Journals (Sweden)

    Khader Samer

    2010-01-01

    Full Text Available Background: Liquid-based cytology (LBC cervical samples are increasingly being used to test for pathogens, including: HPV, Chlamydia trachomatis (CT and Neisseria gonorrhoeae (GC using nucleic acid amplification tests. Several reports have shown the accuracy of such testing on ThinPrep (TP LBC samples. Fewer studies have evaluated SurePath (SP LBC samples, which utilize a different specimen preservative. This study was undertaken to assess the performance of the Aptima Combo 2 Assay (AC2 for CT and GC on SP versus endocervical swab samples in our laboratory. Materials and Methods: The live pathology database of Montefiore Medical Center was searched for patients with AC2 endocervical swab specimens and SP Paps taken the same day. SP samples from CT- and/or GC-positive endocervical swab patients and randomly selected negative patients were studied. In each case, 1.5 ml of the residual SP vial sample, which was in SP preservative and stored at room temperature, was transferred within seven days of collection to APTIMA specimen transfer tubes without any sample or patient identifiers. Blind testing with the AC2 assay was performed on the Tigris DTS System (Gen-probe, San Diego, CA. Finalized SP results were compared with the previously reported endocervical swab results for the entire group and separately for patients 25 years and younger and patients over 25 years. Results: SP specimens from 300 patients were tested. This included 181 swab CT-positive, 12 swab GC-positive, 7 CT and GC positive and 100 randomly selected swab CT and GC negative patients. Using the endocervical swab results as the patient′s infection status, AC2 assay of the SP samples showed: CT sensitivity 89.3%, CT specificity 100.0%; GC sensitivity and specificity 100.0%. CT sensitivity for patients 25 years or younger was 93.1%, versus 80.7% for patients over 25 years, a statistically significant difference (P = 0.02. Conclusions: Our results show that AC2 assay of 1.5 ml SP

  10. TECHNIQUES WITH POTENTIAL FOR HANDLING ENVIRONMENTAL SAMPLES IN CAPILLARY ELECTROPHORESIS

    Science.gov (United States)

    An assessment of the methods for handling environmental samples prior to capillary electrophoresis (CE) is presented for both aqueous and solid matrices. Sample handling in environmental analyses is the subject of ongoing research at the Environmental Protection Agency's National...

  11. Sampling Polya-Gamma random variates: alternate and approximate techniques

    OpenAIRE

    Windle, Jesse; Polson, Nicholas G.; Scott, James G.

    2014-01-01

    Efficiently sampling from the P\\'olya-Gamma distribution, ${PG}(b,z)$, is an essential element of P\\'olya-Gamma data augmentation. Polson et. al (2013) show how to efficiently sample from the ${PG}(1,z)$ distribution. We build two new samplers that offer improved performance when sampling from the ${PG}(b,z)$ distribution and $b$ is not unity.

  12. Manipulation of biological samples using micro and nano techniques

    DEFF Research Database (Denmark)

    Castillo, Jaime; Dimaki, Maria; Svendsen, Winnie Edith

    2009-01-01

    to their natural structure. Thanks to the advances in micro- and nanofabrication during the last decades several manipulation techniques offer us the possibility to image, characterize and manipulate biological material in a controlled way. Using these techniques the integration of biomaterials with remarkable...

  13. Statistical sampling techniques as applied to OSE inspections

    International Nuclear Information System (INIS)

    Davis, J.J.; Cote, R.W.

    1987-01-01

    The need has been recognized for statistically valid methods for gathering information during OSE inspections; and for interpretation of results, both from performance testing and from records reviews, interviews, etc. Battelle Columbus Division, under contract to DOE OSE has performed and is continuing to perform work in the area of statistical methodology for OSE inspections. This paper represents some of the sampling methodology currently being developed for use during OSE inspections. Topics include population definition, sample size requirements, level of confidence and practical logistical constraints associated with the conduct of an inspection based on random sampling. Sequential sampling schemes and sampling from finite populations are also discussed. The methods described are applicable to various data gathering activities, ranging from the sampling and examination of classified documents to the sampling of Protective Force security inspectors for skill testing

  14. A simple air sampling technique for monitoring nitrous oxide pollution

    Energy Technology Data Exchange (ETDEWEB)

    Austin, J C; Shaw, R; Moyes, D; Cleaton-Jones, P E

    1981-01-01

    A simple, inexpensive device for the continuous low-flow sampling of air was devised to permit monitoring of pollution by gaseous anaesthetics. The device consisted of a water-filled Perspex cylinder in which a double-walled flexible-film gas sample collection bag was suspended. Air samples could be aspirated into the collection bag at flow rates of as low as 1 ml min-1 by allowing the water to drain from the cylinder at a controlled rate. The maintenance of sample integrity with aspiration and storage of samples of nitrous oxide in air at concentrations of 1000, 100 and 30 p.p.m. v/v was examined using gas chromatography. The sample bags retained a mean 94% of the nitrous oxide in air samples containing nitrous oxide 25 p.p.m. over a 72-h storage period.

  15. Equipment and techniques for remote sampling of stored radioactive waste

    International Nuclear Information System (INIS)

    Nance, T.A.

    1996-01-01

    Several tools have been developed at the Savannah River Site (SRS) to remotely sample stored radioactive waste. These sampling tools have been developed to determine the chemical characteristics of the waste prior to processing. The processing of waste material varies according to the chemical characteristics of the waste, which change due to additions, settling, mixing, and chemical reactions during storage. Once the waste has been sampled to identify its characteristics, the chemical composition of the waste can then be altered if needed to prepare for processing. Various types of waste material in several types of containment must be sampled at SRS. Stored waste materials consist of liquids, floating organics, sludge, salt and solids. Waste is stored in four basic types of tanks with different means of access and interior obstructions. The waste tanks can only be accessed by small openings: access ports, risers and downcomers. Requirements for sampling depend on the type of tank being accessed, the waste within the tank, and the particular location in the tank desired for taking the sample. Sampling devices have been developed to sample all of the waste material forms found in the SRS tank farms. The fluid type samplers are capable of sampling surface liquid, subsurface liquid at varying depth, surface sludge, subsurface sludge, and floating organics. The solid type samplers are capable of sampling salt, sampling a solid layer on the bottom of the tank, and capturing a small solid mass on the tank bottom. The sampling devices are all designed to access the tanks through small access ports. The samplers are reusable and are designed to allow quick transfer of the samples to shielded packaging for transport, reducing the amount of radiation exposure to sampling personnel. The samplers weigh less than 100 lb. and are designed in sections to allow easy disassembly for storage and transport by personnel. (Abstract Truncated)

  16. Transport theory calculation for a heterogeneous multi-assembly problem by characteristics method with direct neutron path linking technique

    International Nuclear Information System (INIS)

    Kosaka, Shinya; Saji, Etsuro

    2000-01-01

    A characteristics transport theory code, CHAPLET, has been developed for the purpose of making it practical to perform a whole LWR core calculation with the same level of calculational model and accuracy as that of an ordinary single assembly calculation. The characteristics routine employs the CACTUS algorithm for drawing ray tracing lines, which assists the two key features of the flux solution in the CHAPLET code. One is the direct neutron path linking (DNPL) technique which strictly connects angular fluxes at each assembly interface in the flux solution separated between assemblies. Another is to reduce the required memory storage by sharing the data related to ray tracing among assemblies with the same configuration. For faster computation, the coarse mesh rebalance (CMR) method and the Aitken method were incorporated in the code and the combined use of both methods showed the most promising acceleration performance among the trials. In addition, the parallelization of the flux solution was attempted, resulting in a significant reduction in the wall-clock time of the calculation. By all these efforts, coupled with the results of many verification studies, a whole LWR core heterogeneous transport theory calculation finally became practical. CHAPLET is thought to be a useful tool which can produce the reference solutions for analyses of an LWR (author)

  17. Zero-Slack, Noncritical Paths

    Science.gov (United States)

    Simons, Jacob V., Jr.

    2017-01-01

    The critical path method/program evaluation and review technique method of project scheduling is based on the importance of managing a project's critical path(s). Although a critical path is the longest path through a network, its location in large projects is facilitated by the computation of activity slack. However, logical fallacies in…

  18. Comparison of sampling techniques for Rift Valley Fever virus ...

    African Journals Online (AJOL)

    time for trapping potential vectors for Rift Valley Fever virus. ..... Krockel, U., Rose, A., Eiras, A.E. & Geier, M. (2006) New tools for surveillance of adult yellow fever ... baited trapping systems for sampling outdoor mosquito populations in ...

  19. A non-destructive DNA sampling technique for herbarium specimens.

    Science.gov (United States)

    Shepherd, Lara D

    2017-01-01

    Herbarium specimens are an important source of DNA for plant research but current sampling methods require the removal of material for DNA extraction. This is undesirable for irreplaceable specimens such as rare species or type material. Here I present the first non-destructive sampling method for extracting DNA from herbarium specimens. DNA was successfully retrieved from robust leaves and/or stems of herbarium specimens up to 73 years old.

  20. Sample preparation techniques of biological material for isotope analysis

    International Nuclear Information System (INIS)

    Axmann, H.; Sebastianelli, A.; Arrillaga, J.L.

    1990-01-01

    Sample preparation is an essential step in all isotope-aided experiments but often it is not given enough attention. The methods of sample preparation are very important to obtain reliable and precise analytical data and for further interpretation of results. The size of a sample required for chemical analysis is usually very small (10mg-1500mg). On the other hand the amount of harvested plant material from plots in a field experiment is often bulky (several kilograms) and the entire sample is too large for processing. In addition, while approaching maturity many crops show not only differences in physical consistency but also a non-uniformity in 15 N content among plant parts, requiring a plant fractionation or separation into parts (vegetative and reproductive) e.g. shoots and spikes, in case of small grain cereals, shoots and pods in case of grain legumes and tops and roots or beets (including crown) in case of sugar beet, etc. In any case the ultimate goal of these procedures is to obtain representative subsample harvested from greenhouse or field experiments for chemical analysis. Before harvesting an isotopic-aided experiment the method of sampling has to be selected. It should be based on the type of information required in relation to the objectives of the research and the availability of resources (staff, sample preparation equipment, analytical facilities, chemicals and supplies, etc.). 10 refs, 3 figs, 3 tabs

  1. Comparison of sampling techniques for Bayesian parameter estimation

    Science.gov (United States)

    Allison, Rupert; Dunkley, Joanna

    2014-02-01

    The posterior probability distribution for a set of model parameters encodes all that the data have to tell us in the context of a given model; it is the fundamental quantity for Bayesian parameter estimation. In order to infer the posterior probability distribution we have to decide how to explore parameter space. Here we compare three prescriptions for how parameter space is navigated, discussing their relative merits. We consider Metropolis-Hasting sampling, nested sampling and affine-invariant ensemble Markov chain Monte Carlo (MCMC) sampling. We focus on their performance on toy-model Gaussian likelihoods and on a real-world cosmological data set. We outline the sampling algorithms themselves and elaborate on performance diagnostics such as convergence time, scope for parallelization, dimensional scaling, requisite tunings and suitability for non-Gaussian distributions. We find that nested sampling delivers high-fidelity estimates for posterior statistics at low computational cost, and should be adopted in favour of Metropolis-Hastings in many cases. Affine-invariant MCMC is competitive when computing clusters can be utilized for massive parallelization. Affine-invariant MCMC and existing extensions to nested sampling naturally probe multimodal and curving distributions.

  2. Study of gastric cancer samples using terahertz techniques

    Science.gov (United States)

    Wahaia, Faustino; Kasalynas, Irmantas; Seliuta, Dalius; Molis, Gediminas; Urbanowicz, Andrzej; Carvalho Silva, Catia D.; Carneiro, Fatima; Valusis, Gintaras; Granja, Pedro L.

    2014-08-01

    In the present work, samples of healthy and adenocarcinoma-affected human gastric tissue were analyzed using transmission time-domain THz spectroscopy (THz-TDS) and spectroscopic THz imaging at 201 and 590 GHz. The work shows that it is possible to distinguish between normal and cancerous regions in dried and paraffin-embedded samples. Plots of absorption coefficient α and refractive index n of normal and cancer affected tissues, as well as 2-D transmission THz images are presented and the conditions for discrimination between normal and affected tissues are discussed.

  3. Research on Innovating, Applying Multiple Paths Routing Technique Based on Fuzzy Logic and Genetic Algorithm for Routing Messages in Service - Oriented Routing

    Directory of Open Access Journals (Sweden)

    Nguyen Thanh Long

    2015-02-01

    Full Text Available MANET (short for Mobile Ad-Hoc Network consists of a set of mobile network nodes, network configuration changes very fast. In content based routing, data is transferred from source node to request nodes is not based on destination addresses. Therefore, it is very flexible and reliable, because source node does not need to know destination nodes. If We can find multiple paths that satisfies bandwidth requirement, split the original message into multiple smaller messages to transmit concurrently on these paths. On destination nodes, combine separated messages into the original message. Hence it can utilize better network resources, causes data transfer rate to be higher, load balancing, failover. Service Oriented Routing is inherited from the model of content based routing (CBR, combined with several advanced techniques such as Multicast, multiple path routing, Genetic algorithm to increase the data rate, and data encryption to ensure information security. Fuzzy logic is a logical field study evaluating the accuracy of the results based on the approximation of the components involved, make decisions based on many factors relative accuracy based on experimental or mathematical proof. This article presents some techniques to support multiple path routing from one network node to a set of nodes with guaranteed quality of service. By using these techniques can decrease the network load, congestion, use network resources efficiently.

  4. Parallel path nebulizer: Critical parameters for use with microseparation techniques combined with inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Yanes, Enrique G.; Miller-Ihli, Nancy J.

    2005-01-01

    Four different, low flow parallel path Mira Mist CE nebulizers were evaluated and compared in support of an ongoing project related to the use of microseparation techniques interfaced to inductively coupled plasma mass spectrometry for the quantification of cobalamin species (Vitamin B12). For the characterization of the different Mira Mist CE nebulizers, the nebulizer orientation as well as the effect of methanol on analytical response was the focus of the study. The position of the gas outlet on the nebulizer which consistently provided the maximum signal was when it was rotated to the 11 o'clock position when the nebulizer is viewed end-on. With this orientation the increased signal may be explained by the fact that the cone angle of the aerosol is such that the largest percentage of the aerosol is directed to the center of the spray chamber and consequently into the plasma. To characterize the nebulizer's performance, the signal response of a multielement solution containing elements with a variety of ionization potentials was used. The selection of elements with varying ionization energies and degrees of ionization was essential for a better understanding of observed increases in signal enhancement when methanol was used. Two different phenomena contribute to signal enhancement when using methanol: the first is improved transport efficiency and the second is the 'carbon enhancement effect'. The net result was that as much as a 30-fold increase in signal was observed for As and Mg when using a make-up solution of 20% methanol at a 15 μL/min flow rate which is equivalent to a net volume of 3 μL/min of pure methanol

  5. Electrodeposition as a sample preparation technique for TXRF analysis

    International Nuclear Information System (INIS)

    Griesel, S.; Reus, U.; Prange, A.

    2000-01-01

    TXRF analysis of trace elements at concentrations in the μg/L range and below in high salt matrices normally requires a number of sample preparation steps that include separation of the salt matrix and preconcentration of the trace elements. A neat approach which allows samples to be prepared straightforwardly in a single step involves the application of electrochemical deposition using the TXRF sample support itself as an electrode. For this work a common three-electrode arrangement (radiometer analytical) with a rotating disc electrode as the working electrode, as is frequently employed in voltametric analysis, has been used. A special electrode tip has been constructed as a holder for the sample carrier which consists of polished glassy carbon. This material has been proven to be suitable for both its electrical and chemical properties. Measurements of the trace elements were performed using the ATOMIKA 8030C TXRF spectrometer, with the option of variable incident angles. In first experiments an artificial sea water matrix containing various trace elements in the μg/L range has been used. Elements such as Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Hg, and Pb deposited on glassy carbon carriers. The deposition can be optimized by controlling the potential of the working electrode with respect to the reference electrode. Metal ions with a suitable standard potential are reduced to the metallic state and plated onto the electrode surface. When deposition is finished the sample carrier is demounted, rinsed with ultra-pure water and measured directly. Deposition yields for the elements under investigation are quite similar, and with an appropriate choice of the reference element, quantification can be achieved directly by internal standardization. The influence of parameters such as time, pH value, and trace element concentration on the deposition yield has been examined, and the results will be presented along with reproducibility studies. (author)

  6. Bioassay techniques for {sup 55}Fe in urine samples

    Energy Technology Data Exchange (ETDEWEB)

    Cregan, S P; Leon, J W; Linauskas, S H

    1993-11-01

    Solvent extraction, ion chromatography and several rapid screening methods were developed and evaluated for {sup 55}Fe bioassay applications. Isopropyl ether and TNOA column extractions had radiochemical recoveries exceeding 90%. These were very reproducible with a coefficient of variation less than 5%. Screening techniques investigated included direct counting of ashed urine solids, and Fe(OH){sub 3}. precipitated from urine. The sensitivities (2-50 Bq/d urine) of the screening methods were usually limited by the effective urine volume that could be counted in a liquid scintillation counter. The reference isopropyl ether and chromatography methods could easily achieve sensitivities well below the 1 Bq/d urine output target. (author). 49 refs., 3 tabs., 5 figs.

  7. Bioassay techniques for 55Fe in urine samples

    International Nuclear Information System (INIS)

    Cregan, S.P.; Leon, J.W.; Linauskas, S.H.

    1993-11-01

    Solvent extraction, ion chromatography and several rapid screening methods were developed and evaluated for 55 Fe bioassay applications. Isopropyl ether and TNOA column extractions had radiochemical recoveries exceeding 90%. These were very reproducible with a coefficient of variation less than 5%. Screening techniques investigated included direct counting of ashed urine solids, and Fe(OH) 3 . precipitated from urine. The sensitivities (2-50 Bq/d urine) of the screening methods were usually limited by the effective urine volume that could be counted in a liquid scintillation counter. The reference isopropyl ether and chromatography methods could easily achieve sensitivities well below the 1 Bq/d urine output target. (author). 49 refs., 3 tabs., 5 figs

  8. Image acquisition system using on sensor compressed sampling technique

    Science.gov (United States)

    Gupta, Pravir Singh; Choi, Gwan Seong

    2018-01-01

    Advances in CMOS technology have made high-resolution image sensors possible. These image sensors pose significant challenges in terms of the amount of raw data generated, energy efficiency, and frame rate. This paper presents a design methodology for an imaging system and a simplified image sensor pixel design to be used in the system so that the compressed sensing (CS) technique can be implemented easily at the sensor level. This results in significant energy savings as it not only cuts the raw data rate but also reduces transistor count per pixel; decreases pixel size; increases fill factor; simplifies analog-to-digital converter, JPEG encoder, and JPEG decoder design; decreases wiring; and reduces the decoder size by half. Thus, CS has the potential to increase the resolution of image sensors for a given technology and die size while significantly decreasing the power consumption and design complexity. We show that it has potential to reduce power consumption by about 23% to 65%.

  9. Monitoring well design and sampling techniques at NAPL sites

    International Nuclear Information System (INIS)

    Collins, M.; Rohrman, W.R.; Drake, K.D.

    1992-01-01

    The existence of Non-Aqueous Phase Liquids (NAPLs) at many Superfund and RCRA hazardous waste sites has become a recognized problem in recent years. The large number of sites exhibiting this problem results from the fact that many of the most frequently used industrial solvents and petroleum products can exist as NAPLs. Hazardous waste constituents occurring as NAPLs possess a common characteristic that causes great concern during groundwater contamination evaluation: while solubility in water is generally very low, it is sufficient to cause groundwater to exceed Maximum Contamination Levels (MCLs). Thus, even a small quantity of NAPL within a groundwater regime can act as a point source with the ability to contaminate vast quantities of groundwater over time. This property makes it imperative that groundwater investigations focus heavily on characterizing the nature, extent, and migration pathways of NAPLs at sites where it exists. Two types of NAPLs may exist in a groundwater system. Water-immiscible liquid constituents having a specific gravity greater than one are termed Dense Non-Aqueous Phase Liquids, while those with a specific gravity less than one are considered Light Non-Aqueous Phase Liquids. For a groundwater investigation to properly characterize the two types of NAPLs, careful consideration must be given to the placement and sampling of groundwater monitoring wells. Unfortunately, technical reviewers at EPA Region VII and the Corps of Engineers find that many groundwater investigations fall short in characterizing NAPLs because several basic considerations were overlooked. Included among these are monitoring well location and screen placement with respect to the water table and significant confining units, and the ability of the well sampling method to obtain samples of NAPL. Depending on the specific gravity of the NAPL that occurs at a site, various considerations can substantially enhance adequate characterization of NAPL contaminants

  10. An adaptive dual-optimal path-planning technique for unmanned air vehicles with application to solar-regenerative high altitude long endurance flight

    Science.gov (United States)

    Whitfield, Clifford A.

    2009-12-01

    A multi-objective technique for Unmanned Air Vehicle (UAV) path and trajectory autonomy generation, through task allocation and sensor fusion has been developed. The Dual-Optimal Path-Planning (D-O.P-P.) Technique generates on-line adaptive flight paths for UAVs based on available flight windows and environmental influenced objectives. The environmental influenced optimal condition, known as the driver' determines the condition, within a downstream virtual window of possible vehicle destinations and orientation built from the UAV kinematics. The intermittent results are pursued by a dynamic optimization technique to determine the flight path. This sequential optimization technique is a multi-objective optimization procedure consisting of two goals, without requiring additional information to combine the conflicting objectives into a single-objective. An example case-study and additional applications are developed and the results are discussed; including the application to the field of Solar Regenerative (SR) High Altitude Long Endurance (HALE) UAV flight. Harnessing solar energy has recently been adapted for use on high altitude UAV platforms. An aircraft that uses solar panels and powered by the sun during the day and through the night by SR systems, in principle could sustain flight for weeks or months. The requirements and limitations of solar powered flight were determined. The SR-HALE UAV platform geometry and flight characteristics were selected from an existing aircraft that has demonstrated the capability for sustained flight through flight tests. The goals were to maintain continual Situational Awareness (SA) over a case-study selected Area of Interest (AOI) and existing UAV power and surveillance systems. This was done for still wind and constant wind conditions at altitude along with variations in latitude. The characteristics of solar flux and the dependence on the surface location and orientation were established along with fixed flight maneuvers for

  11. Sampling hydrometeors in clouds in-situ - the replicator technique

    Science.gov (United States)

    Wex, Heike; Löffler, Mareike; Griesche, Hannes; Bühl, Johannes; Stratmann, Frank; Schmitt, Carl; Dirksen, Ruud; Reichardt, Jens; Wolf, Veronika; Kuhn, Thomas; Prager, Lutz; Seifert, Patric

    2017-04-01

    For the examination of ice crystals in clouds, concerning their number concentrations, sizes and shapes, often instruments mounted on fast flying aircraft are used. One related disadvantage is possible shattering of the ice crystals on inlets, which has been improved with the introduction of the "Korolev-tip" and by accounting for inter-arrival times (Korolev et al., 2013, 2015), but additionally, the typically fast flying aircraft allow only for a low spatial resolution. Alternative sampling methods have been introduced as e.g., a replicator by Miloshevich & Heymsfield (1997) and an in-situ imager by by Kuhn & Heymsfield (2016). They both sample ice crystals onto an advancing stripe while ascending on a balloon, conserving the ice crystals either in formvar for later off-line analysis under a microscope (Miloshevich & Heymsfield, 1997) or imaging them upon their impaction on silicone oil (Kuhn & Heymsfield, 2016), both yielding vertical profiles for different ice crystal properties. A measurement campaign was performed at the Lindenberg Meteorological Observatory of the German Meteorological Service (DWD) in Germany in October 2016, during which both types of instruments were used during balloon ascents, while ground-based Lidar and cloud-radar measurements were performed simultaneously. The two ice particle sondes were operated by people from the Lulea University of Technology and from TROPOS, where the latter one was made operational only recently. Here, we will show first results of the TROPOS replicator on ice crystals sampled during one ascent, for which the collected ice crystals were analyzed off-line using a microscope. Literature: Korolev, A., E. Emery, and K. Creelman (2013), Modification and tests of particle probe tips to mitigate effects of ice shattering, J. Atmos. Ocean. Tech., 30, 690-708, 2013. Korolev, A., and P. R. Field (2015), Assessment of the performance of the inter-arrival time algorithm to identify ice shattering artifacts in cloud

  12. Evaluation of an improved technique for lumen path definition and lumen segmentation of atherosclerotic vessels in CT angiography.

    Science.gov (United States)

    van Velsen, Evert F S; Niessen, Wiro J; de Weert, Thomas T; de Monyé, Cécile; van der Lugt, Aad; Meijering, Erik; Stokking, Rik

    2007-07-01

    Vessel image analysis is crucial when considering therapeutical options for (cardio-) vascular diseases. Our method, VAMPIRE (Vascular Analysis using Multiscale Paths Inferred from Ridges and Edges), involves two parts: a user defines a start- and endpoint upon which a lumen path is automatically defined, and which is used for initialization; the automatic segmentation of the vessel lumen on computed tomographic angiography (CTA) images. Both parts are based on the detection of vessel-like structures by analyzing intensity, edge, and ridge information. A multi-observer evaluation study was performed to compare VAMPIRE with a conventional method on the CTA data of 15 patients with carotid artery stenosis. In addition to the start- and endpoint, the two radiologists required on average 2.5 (SD: 1.9) additional points to define a lumen path when using the conventional method, and 0.1 (SD: 0.3) when using VAMPIRE. The segmentation results were quantitatively evaluated using Similarity Indices, which were slightly lower between VAMPIRE and the two radiologists (respectively 0.90 and 0.88) compared with the Similarity Index between the radiologists (0.92). The evaluation shows that the improved definition of a lumen path requires minimal user interaction, and that using this path as initialization leads to good automatic lumen segmentation results.

  13. Evaluation of an improved technique for lumen path definition and lumen segmentation of atherosclerotic vessels in CT angiography

    International Nuclear Information System (INIS)

    Velsen, Evert F.S. van; Niessen, Wiro J.; Meijering, Erik; Stokking, Rik; Weert, Thomas T. de; Monye, Cecile de; Lugt, Aad van der

    2007-01-01

    Vessel image analysis is crucial when considering therapeutical options for (cardio-) vascular diseases. Our method, VAMPIRE (Vascular Analysis using Multiscale Paths Inferred from Ridges and Edges), involves two parts: a user defines a start- and endpoint upon which a lumen path is automatically defined, and which is used for initialization; the automatic segmentation of the vessel lumen on computed tomographic angiography (CTA) images. Both parts are based on the detection of vessel-like structures by analyzing intensity, edge, and ridge information. A multi-observer evaluation study was performed to compare VAMPIRE with a conventional method on the CTA data of 15 patients with carotid artery stenosis. In addition to the start- and endpoint, the two radiologists required on average 2.5 (SD: 1.9) additional points to define a lumen path when using the conventional method, and 0.1 (SD: 0.3) when using VAMPIRE. The segmentation results were quantitatively evaluated using Similarity Indices, which were slightly lower between VAMPIRE and the two radiologists (respectively 0.90 and 0.88) compared with the Similarity Index between the radiologists (0.92). The evaluation shows that the improved definition of a lumen path requires minimal user interaction, and that using this path as initialization leads to good automatic lumen segmentation results. (orig.)

  14. Design and building of a homemade sample changer for automation of the irradiation in neutron activation analysis technique

    International Nuclear Information System (INIS)

    Gago, Javier; Hernandez, Yuri; Baltuano, Oscar; Bedregal, Patricia; Lopez, Yon; Urquizo, Rafael

    2014-01-01

    Because the RP-10 research reactor operates during weekends, it was necessary to design and build a sample changer for irradiation as part of the automation process of neutron activation analysis technique. The device is formed by an aluminum turntable disk which can accommodate 19 polyethylene capsules, containing samples to be sent using the pneumatic transfer system from the laboratory to the irradiation position. The system is operate by a control switchboard to send and return capsules in a variable preset time and by two different ways, allowing the determination of short, medium and long lived radionuclides. Also another mechanism is designed called 'exchange valve' for changing travel paths (pipelines) allowing the irradiated samples to be stored for a longer time in the reactor hall. The system design has allowed complete automation of this technique, enabling the irradiation of samples without the presence of an analyst. The design, construction and operation of the device is described and presented in this article. (authors).

  15. Solid Phase Microextraction and Related Techniques for Drugs in Biological Samples

    OpenAIRE

    Moein, Mohammad Mahdi; Said, Rana; Bassyouni, Fatma; Abdel-Rehim, Mohamed

    2014-01-01

    In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from o...

  16. Path Dependency

    OpenAIRE

    Mark Setterfield

    2015-01-01

    Path dependency is defined, and three different specific concepts of path dependency – cumulative causation, lock in, and hysteresis – are analyzed. The relationships between path dependency and equilibrium, and path dependency and fundamental uncertainty are also discussed. Finally, a typology of dynamical systems is developed to clarify these relationships.

  17. A new sampling technique for surface exposure dating using a portable electric rock cutter

    Directory of Open Access Journals (Sweden)

    Yusuke Suganuma

    2012-07-01

    Full Text Available Surface exposure dating using in situ cosmogenic nuclides has contributed to our understanding of Earth-surface processes. The precision of the ages estimated by this method is affected by the sample geometry; therefore, high accuracy measurements of the thickness and shape of the rock sample (thickness and shape is crucial. However, it is sometimes diffi cult to meet these requirements by conventional sampling methods with a hammer and chisel. Here, we propose a new sampling technique using a portable electric rock cutter. This sampling technique is faster, produces more precisely shaped samples, and allows for a more precise age interpretation. A simple theoretical modeldemonstrates that the age error due to defective sample geometry increases as the total sample thickness increases, indicating the importance of precise sampling for surface exposure dating.

  18. Magnetic separation techniques in sample preparation for biological analysis: a review.

    Science.gov (United States)

    He, Jincan; Huang, Meiying; Wang, Dongmei; Zhang, Zhuomin; Li, Gongke

    2014-12-01

    Sample preparation is a fundamental and essential step in almost all the analytical procedures, especially for the analysis of complex samples like biological and environmental samples. In past decades, with advantages of superparamagnetic property, good biocompatibility and high binding capacity, functionalized magnetic materials have been widely applied in various processes of sample preparation for biological analysis. In this paper, the recent advancements of magnetic separation techniques based on magnetic materials in the field of sample preparation for biological analysis were reviewed. The strategy of magnetic separation techniques was summarized. The synthesis, stabilization and bio-functionalization of magnetic nanoparticles were reviewed in detail. Characterization of magnetic materials was also summarized. Moreover, the applications of magnetic separation techniques for the enrichment of protein, nucleic acid, cell, bioactive compound and immobilization of enzyme were described. Finally, the existed problems and possible trends of magnetic separation techniques for biological analysis in the future were proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Sample preparation techniques based on combustion reactions in closed vessels - A brief overview and recent applications

    International Nuclear Information System (INIS)

    Flores, Erico M.M.; Barin, Juliano S.; Mesko, Marcia F.; Knapp, Guenter

    2007-01-01

    In this review, a general discussion of sample preparation techniques based on combustion reactions in closed vessels is presented. Applications for several kinds of samples are described, taking into account the literature data reported in the last 25 years. The operational conditions as well as the main characteristics and drawbacks are discussed for bomb combustion, oxygen flask and microwave-induced combustion (MIC) techniques. Recent applications of MIC techniques are discussed with special concern for samples not well digested by conventional microwave-assisted wet digestion as, for example, coal and also for subsequent determination of halogens

  20. A comparative study on full diagonalization of Hessian matrix and Gradient-only technique to trace out reaction path in doped noble gas clusters using stochastic optimization

    International Nuclear Information System (INIS)

    Biring, Shyamal Kumar; Chaudhury, Pinaki

    2012-01-01

    Highlights: ► Estimation of critical points in Noble-gas clusters. ► Evaluation of first order saddle point or transition states. ► Construction of reaction path for structural change in clusters. ► Use of Monte-Carlo Simulated Annealing to study structural changes. - Abstract: This paper proposes Simulated Annealing based search to locate critical points in mixed noble gas clusters where Ne and Xe are individually doped in Ar-clusters. Using Lennard–Jones (LJ) atomic interaction we try to explore the search process of transformation through Minimum Energy Path (MEP) from one minimum energy geometry to another via first order saddle point on the potential energy surface of the clusters. Here we compare the results based on diagonalization of the full Hessian all through the search and quasi-gradient only technique to search saddle points and construction of reaction path (RP) for three sizes of doped Ar-clusters, (Ar) 19 Ne/Xe,(Ar) 24 Ne/Xe and (Ar) 29 Ne/Xe.

  1. Methodological integrative review of the work sampling technique used in nursing workload research.

    Science.gov (United States)

    Blay, Nicole; Duffield, Christine M; Gallagher, Robyn; Roche, Michael

    2014-11-01

    To critically review the work sampling technique used in nursing workload research. Work sampling is a technique frequently used by researchers and managers to explore and measure nursing activities. However, work sampling methods used are diverse making comparisons of results between studies difficult. Methodological integrative review. Four electronic databases were systematically searched for peer-reviewed articles published between 2002-2012. Manual scanning of reference lists and Rich Site Summary feeds from contemporary nursing journals were other sources of data. Articles published in the English language between 2002-2012 reporting on research which used work sampling to examine nursing workload. Eighteen articles were reviewed. The review identified that the work sampling technique lacks a standardized approach, which may have an impact on the sharing or comparison of results. Specific areas needing a shared understanding included the training of observers and subjects who self-report, standardization of the techniques used to assess observer inter-rater reliability, sampling methods and reporting of outcomes. Work sampling is a technique that can be used to explore the many facets of nursing work. Standardized reporting measures would enable greater comparison between studies and contribute to knowledge more effectively. Author suggestions for the reporting of results may act as guidelines for researchers considering work sampling as a research method. © 2014 John Wiley & Sons Ltd.

  2. A line-based vegetation sampling technique and its application in ...

    African Journals Online (AJOL)

    percentage cover, density and intercept frequency) and also provides plant size distributions, yet requires no more sampling effort than the line-intercept method.. A field test of the three techniques in succulent karoo, showed that the discriminating ...

  3. Fabrication Techniques of Stretchable and Cloth Electroadhesion Samples for Implementation on Devices with Space Application

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this study is to determine materials and fabrication techniques for efficient space-rated electroadhesion (EA) samples. Liquid metals, including...

  4. Sampling phased array a new technique for signal processing and ultrasonic imaging

    OpenAIRE

    Bulavinov, A.; Joneit, D.; Kröning, M.; Bernus, L.; Dalichow, M.H.; Reddy, K.M.

    2006-01-01

    Different signal processing and image reconstruction techniques are applied in ultrasonic non-destructive material evaluation. In recent years, rapid development in the fields of microelectronics and computer engineering lead to wide application of phased array systems. A new phased array technique, called "Sampling Phased Array" has been developed in Fraunhofer Institute for non-destructive testing. It realizes unique approach of measurement and processing of ultrasonic signals. The sampling...

  5. Standardization of proton-induced x-ray emission technique for analysis of thick samples

    Science.gov (United States)

    Ali, Shad; Zeb, Johar; Ahad, Abdul; Ahmad, Ishfaq; Haneef, M.; Akbar, Jehan

    2015-09-01

    This paper describes the standardization of the proton-induced x-ray emission (PIXE) technique for finding the elemental composition of thick samples. For the standardization, three different samples of standard reference materials (SRMs) were analyzed using this technique and the data were compared with the already known data of these certified SRMs. These samples were selected in order to cover the maximum range of elements in the periodic table. Each sample was irradiated for three different values of collected beam charges at three different times. A proton beam of 2.57 MeV obtained using 5UDH-II Pelletron accelerator was used for excitation of x-rays from the sample. The acquired experimental data were analyzed using the GUPIXWIN software. The results show that the SRM data and the data obtained using the PIXE technique are in good agreement.

  6. Cone penetrometer tests and HydroPunch sampling: A screening technique for plume definition

    International Nuclear Information System (INIS)

    Smolley, M.; Kappmeyer, J.C.

    1991-01-01

    Cone penetrometer tests and HydroPunch sampling were used to define the extent of volatile organic compounds in ground water. The investigation indicated that the combination of the these techniques is effective for obtaining ground water samples for preliminary plume definition. HydroPunch samples can be collected in unconsolidated sediments and the analytical results obtained from these samples are comparable to those obtained from adjacent monitoring wells. This sampling method is a rapid and cost-effective screening technique for characterizing the extent of contaminant plumes in soft sediment environments. Use of this screening technique allowed monitoring wells to be located at the plume boundary, thereby reducing the number of wells installed and the overall cost of the plume definition program

  7. The BD Onclarity HPV assay on SurePath collected samples meets the International Guidelines for Human Papillomavirus Test Requirements for Cervical Screening

    DEFF Research Database (Denmark)

    Ejegod, Ditte; Bottari, Fabio; Pedersen, Helle

    2016-01-01

    This study describes a validation of the BD Onclarity HPV (Onclarity) assay using the international guidelines for HPV test requirements for cervical cancer screening of women 30 years and above using Danish SurePath screening samples. The clinical specificity (0.90, 95% CI: 0.88-0.91) and sensit......This study describes a validation of the BD Onclarity HPV (Onclarity) assay using the international guidelines for HPV test requirements for cervical cancer screening of women 30 years and above using Danish SurePath screening samples. The clinical specificity (0.90, 95% CI: 0.......88-0.91) and sensitivity (0.97, 95% CI: 0.87-1.0) of the Onclarity assay were shown to be non-inferior to the reference assay (specificity 0.90, 95% CI: 0.88-0.92, sensitivity 0.98, 95% CI: 0.91-1.0). The intra-laboratory reproducibility of Onclarity was 97% with a lower confidence bound of 96% (kappa value: 0...

  8. First- and zero-sound velocity and Fermi liquid parameter F2s in liquid 3He determined by a path length modulation technique

    International Nuclear Information System (INIS)

    Hamot, P.J.; Lee, Y.; Sprague, D.T.

    1995-01-01

    We have measured the velocity of first- and zero-sound in liquid 3 He at 12.6 MHz over the pressure range of 0.6 to 14.5 bar using a path length modulation technique that we have recently developed. From these measurements, the pressure dependent value of the Fermi liquid parameter F 2 s was calculated and found to be larger at low pressure than previously reported. These new values of F 2 s indicate that transverse zero-sound is a propagating mode at all pressures. The new values are important for the interpretation of the frequencies of order parameter collective modes in the superfluid phases. The new acoustic technique permits measurements in regimes of very high attenuation with a sensitivity in phase velocity of about 10 ppm achieved by a feedback arrangement. The sound velocity is thus measured continuously throughout the highly attenuating crossover (ωt ∼ 1) regime, even at the lowest pressures

  9. Sample preparation techniques in trace element analysis by X-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Valkovic, V.

    1983-11-01

    The report, written under a research contract with the IAEA, contains a detailed presentation of the most difficult problem encountered in the trace element analysis by methods of the X-ray emission spectroscopy, namely the sample preparation techniques. The following items are covered. Sampling - with specific consideration of aerosols, water, soil, biological materials, petroleum and its products, storage of samples and their handling. Pretreatment of samples - preconcentration, ashing, solvent extraction, ion exchange and electrodeposition. Sample preparations for PIXE - analysis - backings, target uniformity and homogeneity, effects of irradiation, internal standards and specific examples of preparation (aqueous, biological, blood serum and solid samples). Sample preparations for radioactive sources or tube excitation - with specific examples (water, liquid and solid samples, soil, geological, plants and tissue samples). Finally, the problem of standards and reference materials, as well as that of interlaboratory comparisons, is discussed

  10. Mantle biopsy: a technique for nondestructive tissue-sampling of freshwater mussels

    Science.gov (United States)

    David J. Berg; Wendell R. Haag; Sheldon I. Guttman; James B. Sickel

    1995-01-01

    Mantle biopsy is a means of obtaining tissue samples for genetic, physiological, and contaminant studies of bivalves; but the effects of this biopsy on survival have not been determined. We describe a simple technique for obtaining such samples from unionacean bivalves and how we compared survival among biopsied and control organisms in field experiments. Survival was...

  11. RF Sub-sampling Receiver Architecture based on Milieu Adapting Techniques

    DEFF Research Database (Denmark)

    Behjou, Nastaran; Larsen, Torben; Jensen, Ole Kiel

    2012-01-01

    A novel sub-sampling based architecture is proposed which has the ability of reducing the problem of image distortion and improving the signal to noise ratio significantly. The technique is based on sensing the environment and adapting the sampling rate of the receiver to the best possible...

  12. Thermophilic Campylobacter spp. in turkey samples: evaluation of two automated enzyme immunoassays and conventional microbiological techniques

    DEFF Research Database (Denmark)

    Borck, Birgitte; Stryhn, H.; Ersboll, A.K.

    2002-01-01

    Aims: To determine the sensitivity and specificity of two automated enzyme immunoassays (EIA), EiaFoss and Minividas, and a conventional microbiological culture technique for detecting thermophilic Campylobacter spp. in turkey samples. Methods and Results: A total of 286 samples (faecal, meat...

  13. Laboratory techniques for safe encapsulation of α-emitting powder samples

    International Nuclear Information System (INIS)

    Chamberlain, H.E.; Pottinger, J.S.

    1984-01-01

    Plutonium oxide powder samples can be encapsulated in thin plastic film to prevent spread of contamination in counting and X-ray diffraction equipment. The film has to be thin enough to transmit X-rays and α-particles. Techniques are described for the wrapping process and the precautions necessary to keep the sample processing line free of significant contamination. (author)

  14. A fully blanketed early B star LTE model atmosphere using an opacity sampling technique

    International Nuclear Information System (INIS)

    Phillips, A.P.; Wright, S.L.

    1980-01-01

    A fully blanketed LTE model of a stellar atmosphere with Tsub(e) = 21914 K (thetasub(e) = 0.23), log g = 4 is presented. The model includes an explicit representation of the opacity due to the strongest lines, and uses a statistical opacity sampling technique to represent the weaker line opacity. The sampling technique is subjected to several tests and the model is compared with an atmosphere calculated using the line-distribution function method. The limitations of the distribution function method and the particular opacity sampling method used here are discussed in the light of the results obtained. (author)

  15. Prompt Gamma Activation Analysis (PGAA): Technique of choice for nondestructive bulk analysis of returned comet samples

    International Nuclear Information System (INIS)

    Lindstrom, D.J.; Lindstrom, R.M.

    1989-01-01

    Prompt gamma activation analysis (PGAA) is a well-developed analytical technique. The technique involves irradiation of samples in an external neutron beam from a nuclear reactor, with simultaneous counting of gamma rays produced in the sample by neutron capture. Capture of neutrons leads to excited nuclei which decay immediately with the emission of energetic gamma rays to the ground state. PGAA has several advantages over other techniques for the analysis of cometary materials: (1) It is nondestructive; (2) It can be used to determine abundances of a wide variety of elements, including most major and minor elements (Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Co, Ni), volatiles (H, C, N, F, Cl, S), and some trace elements (those with high neutron capture cross sections, including B, Cd, Nd, Sm, and Gd); and (3) It is a true bulk analysis technique. Recent developments should improve the technique's sensitivity and accuracy considerably

  16. Can groundwater sampling techniques used in monitoring wells influence methane concentrations and isotopes?

    Science.gov (United States)

    Rivard, Christine; Bordeleau, Geneviève; Lavoie, Denis; Lefebvre, René; Malet, Xavier

    2018-03-06

    Methane concentrations and isotopic composition in groundwater are the focus of a growing number of studies. However, concerns are often expressed regarding the integrity of samples, as methane is very volatile and may partially exsolve during sample lifting in the well and transfer to sampling containers. While issues concerning bottle-filling techniques have already been documented, this paper documents a comparison of methane concentration and isotopic composition obtained with three devices commonly used to retrieve water samples from dedicated observation wells. This work lies within the framework of a larger project carried out in the Saint-Édouard area (southern Québec, Canada), whose objective was to assess the risk to shallow groundwater quality related to potential shale gas exploitation. The selected sampling devices, which were tested on ten wells during three sampling campaigns, consist of an impeller pump, a bladder pump, and disposable sampling bags (HydraSleeve). The sampling bags were used both before and after pumping, to verify the appropriateness of a no-purge approach, compared to the low-flow approach involving pumping until stabilization of field physicochemical parameters. Results show that methane concentrations obtained with the selected sampling techniques are usually similar and that there is no systematic bias related to a specific technique. Nonetheless, concentrations can sometimes vary quite significantly (up to 3.5 times) for a given well and sampling event. Methane isotopic composition obtained with all sampling techniques is very similar, except in some cases where sampling bags were used before pumping (no-purge approach), in wells where multiple groundwater sources enter the borehole.

  17. Long-term monitoring of the Danube river-Sampling techniques, radionuclide metrology and radioecological assessment

    International Nuclear Information System (INIS)

    Maringer, F.J.; Gruber, V.; Hrachowitz, M.; Baumgartner, A.; Weilner, S.; Seidel, C.

    2009-01-01

    Sampling techniques and radiometric methods, developed and applied in a comprehensive radioecological study of the Danube River are presented. Results and radiometric data of sediment samples, collected by sediment traps in Austria and additionally by grab sampling in the Danube during research cruises between Germany and the delta (Black sea) are shown and discussed. Goal of the investigation is the protection of public and environment, especially the sustainable use and conservation of human freshwater resources against harmful radioactive exposure.

  18. Comparison between correlated sampling and the perturbation technique of MCNP5 for fixed-source problems

    International Nuclear Information System (INIS)

    He Tao; Su Bingjing

    2011-01-01

    Highlights: → The performance of the MCNP differential operator perturbation technique is compared with that of the MCNP correlated sampling method for three types of fixed-source problems. → In terms of precision, the MCNP perturbation technique outperforms correlated sampling for one type of problem but performs comparably with or even under-performs correlated sampling for the other two types of problems. → In terms of accuracy, the MCNP perturbation calculations may predict inaccurate results for some of the test problems. However, the accuracy can be improved if the midpoint correction technique is used. - Abstract: Correlated sampling and the differential operator perturbation technique are two methods that enable MCNP (Monte Carlo N-Particle) to simulate small response change between an original system and a perturbed system. In this work the performance of the MCNP differential operator perturbation technique is compared with that of the MCNP correlated sampling method for three types of fixed-source problems. In terms of precision of predicted response changes, the MCNP perturbation technique outperforms correlated sampling for the problem involving variation of nuclide concentrations in the same direction but performs comparably with or even underperforms correlated sampling for the other two types of problems that involve void or variation of nuclide concentrations in opposite directions. In terms of accuracy, the MCNP differential operator perturbation calculations may predict inaccurate results that deviate from the benchmarks well beyond their uncertainty ranges for some of the test problems. However, the accuracy of the MCNP differential operator perturbation can be improved if the midpoint correction technique is used.

  19. Elemental analyses of goundwater: demonstrated advantage of low-flow sampling and trace-metal clean techniques over standard techniques

    Science.gov (United States)

    Creasey, C. L.; Flegal, A. R.

    The combined use of both (1) low-flow purging and sampling and (2) trace-metal clean techniques provides more representative measurements of trace-element concentrations in groundwater than results derived with standard techniques. The use of low-flow purging and sampling provides relatively undisturbed groundwater samples that are more representative of in situ conditions, and the use of trace-element clean techniques limits the inadvertent introduction of contaminants during sampling, storage, and analysis. When these techniques are applied, resultant trace-element concentrations are likely to be markedly lower than results based on standard sampling techniques. In a comparison of data derived from contaminated and control groundwater wells at a site in California, USA, trace-element concentrations from this study were 2-1000 times lower than those determined by the conventional techniques used in sampling of the same wells prior to (5months) and subsequent to (1month) the collections for this study. Specifically, the cadmium and chromium concentrations derived using standard sampling techniques exceed the California Maximum Contaminant Levels (MCL), whereas in this investigation concentrations of both of those elements are substantially below their MCLs. Consequently, the combined use of low-flow and trace-metal clean techniques may preclude erroneous reports of trace-element contamination in groundwater. Résumé L'utilisation simultanée de la purge et de l'échantillonnage à faible débit et des techniques sans traces de métaux permet d'obtenir des mesures de concentrations en éléments en traces dans les eaux souterraines plus représentatives que les résultats fournis par les techniques classiques. L'utilisation de la purge et de l'échantillonnage à faible débit donne des échantillons d'eau souterraine relativement peu perturbés qui sont plus représentatifs des conditions in situ, et le recours aux techniques sans éléments en traces limite l

  20. A Comparison of Traditional, Step-Path, and Geostatistical Techniques in the Stability Analysis of a Large Open Pit

    Science.gov (United States)

    Mayer, J. M.; Stead, D.

    2017-04-01

    With the increased drive towards deeper and more complex mine designs, geotechnical engineers are often forced to reconsider traditional deterministic design techniques in favour of probabilistic methods. These alternative techniques allow for the direct quantification of uncertainties within a risk and/or decision analysis framework. However, conventional probabilistic practices typically discretize geological materials into discrete, homogeneous domains, with attributes defined by spatially constant random variables, despite the fact that geological media display inherent heterogeneous spatial characteristics. This research directly simulates this phenomenon using a geostatistical approach, known as sequential Gaussian simulation. The method utilizes the variogram which imposes a degree of controlled spatial heterogeneity on the system. Simulations are constrained using data from the Ok Tedi mine site in Papua New Guinea and designed to randomly vary the geological strength index and uniaxial compressive strength using Monte Carlo techniques. Results suggest that conventional probabilistic techniques have a fundamental limitation compared to geostatistical approaches, as they fail to account for the spatial dependencies inherent to geotechnical datasets. This can result in erroneous model predictions, which are overly conservative when compared to the geostatistical results.

  1. Path Expressions

    Science.gov (United States)

    1975-06-01

    Traditionally, synchronization of concurrent processes is coded in line by operations on semaphores or similar objects. Path expressions move the...discussion about a variety of synchronization primitives . An analysis of their relative power is found in [3]. Path expressions do not introduce yet...another synchronization primitive . A path expression relates to such primitives as a for- or while-statement of an ALGOL-like language relates to a JUMP

  2. Cis-to- Trans Isomerization of Azobenzene Derivatives Studied with Transition Path Sampling and Quantum Mechanical/Molecular Mechanical Molecular Dynamics.

    Science.gov (United States)

    Muždalo, Anja; Saalfrank, Peter; Vreede, Jocelyne; Santer, Mark

    2018-04-10

    Azobenzene-based molecular photoswitches are becoming increasingly important for the development of photoresponsive, functional soft-matter material systems. Upon illumination with light, fast interconversion between a more stable trans and a metastable cis configuration can be established resulting in pronounced changes in conformation, dipole moment or hydrophobicity. A rational design of functional photosensitive molecules with embedded azo moieties requires a thorough understanding of isomerization mechanisms and rates, especially the thermally activated relaxation. For small azo derivatives considered in the gas phase or simple solvents, Eyring's classical transition state theory (TST) approach yields useful predictions for trends in activation energies or corresponding half-life times of the cis isomer. However, TST or improved theories cannot easily be applied when the azo moiety is part of a larger molecular complex or embedded into a heterogeneous environment, where a multitude of possible reaction pathways may exist. In these cases, only the sampling of an ensemble of dynamic reactive trajectories (transition path sampling, TPS) with explicit models of the environment may reveal the nature of the processes involved. In the present work we show how a TPS approach can conveniently be implemented for the phenomenon of relaxation-isomerization of azobenzenes starting with the simple examples of pure azobenzene and a push-pull derivative immersed in a polar (DMSO) and apolar (toluene) solvent. The latter are represented explicitly at a molecular mechanical (MM) and the azo moiety at a quantum mechanical (QM) level. We demonstrate for the push-pull azobenzene that path sampling in combination with the chosen QM/MM scheme produces the expected change in isomerization pathway from inversion to rotation in going from a low to a high permittivity (explicit) solvent model. We discuss the potential of the simulation procedure presented for comparative calculation of

  3. The electron transport problem sampling by Monte Carlo individual collision technique

    International Nuclear Information System (INIS)

    Androsenko, P.A.; Belousov, V.I.

    2005-01-01

    The problem of electron transport is of most interest in all fields of the modern science. To solve this problem the Monte Carlo sampling has to be used. The electron transport is characterized by a large number of individual interactions. To simulate electron transport the 'condensed history' technique may be used where a large number of collisions are grouped into a single step to be sampled randomly. Another kind of Monte Carlo sampling is the individual collision technique. In comparison with condensed history technique researcher has the incontestable advantages. For example one does not need to give parameters altered by condensed history technique like upper limit for electron energy, resolution, number of sub-steps etc. Also the condensed history technique may lose some very important tracks of electrons because of its limited nature by step parameters of particle movement and due to weakness of algorithms for example energy indexing algorithm. There are no these disadvantages in the individual collision technique. This report presents some sampling algorithms of new version BRAND code where above mentioned technique is used. All information on electrons was taken from Endf-6 files. They are the important part of BRAND. These files have not been processed but directly taken from electron information source. Four kinds of interaction like the elastic interaction, the Bremsstrahlung, the atomic excitation and the atomic electro-ionization were considered. In this report some results of sampling are presented after comparison with analogs. For example the endovascular radiotherapy problem (P2) of QUADOS2002 was presented in comparison with another techniques that are usually used. (authors)

  4. The electron transport problem sampling by Monte Carlo individual collision technique

    Energy Technology Data Exchange (ETDEWEB)

    Androsenko, P.A.; Belousov, V.I. [Obninsk State Technical Univ. of Nuclear Power Engineering, Kaluga region (Russian Federation)

    2005-07-01

    The problem of electron transport is of most interest in all fields of the modern science. To solve this problem the Monte Carlo sampling has to be used. The electron transport is characterized by a large number of individual interactions. To simulate electron transport the 'condensed history' technique may be used where a large number of collisions are grouped into a single step to be sampled randomly. Another kind of Monte Carlo sampling is the individual collision technique. In comparison with condensed history technique researcher has the incontestable advantages. For example one does not need to give parameters altered by condensed history technique like upper limit for electron energy, resolution, number of sub-steps etc. Also the condensed history technique may lose some very important tracks of electrons because of its limited nature by step parameters of particle movement and due to weakness of algorithms for example energy indexing algorithm. There are no these disadvantages in the individual collision technique. This report presents some sampling algorithms of new version BRAND code where above mentioned technique is used. All information on electrons was taken from Endf-6 files. They are the important part of BRAND. These files have not been processed but directly taken from electron information source. Four kinds of interaction like the elastic interaction, the Bremsstrahlung, the atomic excitation and the atomic electro-ionization were considered. In this report some results of sampling are presented after comparison with analogs. For example the endovascular radiotherapy problem (P2) of QUADOS2002 was presented in comparison with another techniques that are usually used. (authors)

  5. LVQ-SMOTE - Learning Vector Quantization based Synthetic Minority Over-sampling Technique for biomedical data.

    Science.gov (United States)

    Nakamura, Munehiro; Kajiwara, Yusuke; Otsuka, Atsushi; Kimura, Haruhiko

    2013-10-02

    Over-sampling methods based on Synthetic Minority Over-sampling Technique (SMOTE) have been proposed for classification problems of imbalanced biomedical data. However, the existing over-sampling methods achieve slightly better or sometimes worse result than the simplest SMOTE. In order to improve the effectiveness of SMOTE, this paper presents a novel over-sampling method using codebooks obtained by the learning vector quantization. In general, even when an existing SMOTE applied to a biomedical dataset, its empty feature space is still so huge that most classification algorithms would not perform well on estimating borderlines between classes. To tackle this problem, our over-sampling method generates synthetic samples which occupy more feature space than the other SMOTE algorithms. Briefly saying, our over-sampling method enables to generate useful synthetic samples by referring to actual samples taken from real-world datasets. Experiments on eight real-world imbalanced datasets demonstrate that our proposed over-sampling method performs better than the simplest SMOTE on four of five standard classification algorithms. Moreover, it is seen that the performance of our method increases if the latest SMOTE called MWMOTE is used in our algorithm. Experiments on datasets for β-turn types prediction show some important patterns that have not been seen in previous analyses. The proposed over-sampling method generates useful synthetic samples for the classification of imbalanced biomedical data. Besides, the proposed over-sampling method is basically compatible with basic classification algorithms and the existing over-sampling methods.

  6. Modified emission-transmission method for determining trace elements in solid samples using the XRF techniques

    International Nuclear Information System (INIS)

    Poblete, V.; Alvarez, M.; Hermosilla, M.

    2000-01-01

    This is a study of an analysis of trace elements in medium thick solid samples, by the modified transmission emission method, using the energy dispersion X-ray fluorescence technique (EDXRF). The effects of absorption and reinforcement are the main disadvantages of the EDXRF technique for the quantitative analysis of bigger elements and trace elements in solid samples. The implementation of this method and its application to a variety of samples was carried out using an infinitely thick multi-element white sample that calculates the correction factors by absorbing all the analytes in the sample. The discontinuities in the masic absorption coefficients versus energies association for each element, with medium thick and homogenous samples, are analyzed and corrected. A thorough analysis of the different theoretical and test variables are proven by using real samples, including certified material with known concentration. The simplicity of the calculation method and the results obtained show the method's major precision, with possibilities for the non-destructive routine analysis of different solid samples, using the EDXRF technique (author)

  7. Bootstrap inversion technique for atmospheric trace gas source detection and quantification using long open-path laser measurements

    Directory of Open Access Journals (Sweden)

    C. B. Alden

    2018-03-01

    Full Text Available Advances in natural gas extraction technology have led to increased activity in the production and transport sectors in the United States and, as a consequence, an increased need for reliable monitoring of methane leaks to the atmosphere. We present a statistical methodology in combination with an observing system for the detection and attribution of fugitive emissions of methane from distributed potential source location landscapes such as natural gas production sites. We measure long (> 500 m, integrated open-path concentrations of atmospheric methane using a dual frequency comb spectrometer and combine measurements with an atmospheric transport model to infer leak locations and strengths using a novel statistical method, the non-zero minimum bootstrap (NZMB. The new statistical method allows us to determine whether the empirical distribution of possible source strengths for a given location excludes zero. Using this information, we identify leaking source locations (i.e., natural gas wells through rejection of the null hypothesis that the source is not leaking. The method is tested with a series of synthetic data inversions with varying measurement density and varying levels of model–data mismatch. It is also tested with field observations of (1 a non-leaking source location and (2 a source location where a controlled emission of 3.1  ×  10−5 kg s−1 of methane gas is released over a period of several hours. This series of synthetic data tests and outdoor field observations using a controlled methane release demonstrates the viability of the approach for the detection and sizing of very small leaks of methane across large distances (4+ km2 in synthetic tests. The field tests demonstrate the ability to attribute small atmospheric enhancements of 17 ppb to the emitting source location against a background of combined atmospheric (e.g., background methane variability and measurement uncertainty of 5 ppb (1σ, when

  8. Bootstrap inversion technique for atmospheric trace gas source detection and quantification using long open-path laser measurements

    Science.gov (United States)

    Alden, Caroline B.; Ghosh, Subhomoy; Coburn, Sean; Sweeney, Colm; Karion, Anna; Wright, Robert; Coddington, Ian; Rieker, Gregory B.; Prasad, Kuldeep

    2018-03-01

    Advances in natural gas extraction technology have led to increased activity in the production and transport sectors in the United States and, as a consequence, an increased need for reliable monitoring of methane leaks to the atmosphere. We present a statistical methodology in combination with an observing system for the detection and attribution of fugitive emissions of methane from distributed potential source location landscapes such as natural gas production sites. We measure long (> 500 m), integrated open-path concentrations of atmospheric methane using a dual frequency comb spectrometer and combine measurements with an atmospheric transport model to infer leak locations and strengths using a novel statistical method, the non-zero minimum bootstrap (NZMB). The new statistical method allows us to determine whether the empirical distribution of possible source strengths for a given location excludes zero. Using this information, we identify leaking source locations (i.e., natural gas wells) through rejection of the null hypothesis that the source is not leaking. The method is tested with a series of synthetic data inversions with varying measurement density and varying levels of model-data mismatch. It is also tested with field observations of (1) a non-leaking source location and (2) a source location where a controlled emission of 3.1 × 10-5 kg s-1 of methane gas is released over a period of several hours. This series of synthetic data tests and outdoor field observations using a controlled methane release demonstrates the viability of the approach for the detection and sizing of very small leaks of methane across large distances (4+ km2 in synthetic tests). The field tests demonstrate the ability to attribute small atmospheric enhancements of 17 ppb to the emitting source location against a background of combined atmospheric (e.g., background methane variability) and measurement uncertainty of 5 ppb (1σ), when measurements are averaged over 2 min. The

  9. Fractional path planning and path tracking

    International Nuclear Information System (INIS)

    Melchior, P.; Jallouli-Khlif, R.; Metoui, B.

    2011-01-01

    This paper presents the main results of the application of fractional approach in path planning and path tracking. A new robust path planning design for mobile robot was studied in dynamic environment. The normalized attractive force applied to the robot is based on a fictitious fractional attractive potential. This method allows to obtain robust path planning despite robot mass variation. The danger level of each obstacles is characterized by the fractional order of the repulsive potential of the obstacles. Under these conditions, the robot dynamic behavior was studied by analyzing its X - Y path planning with dynamic target or dynamic obstacles. The case of simultaneously mobile obstacles and target is also considered. The influence of the robot mass variation is studied and the robustness analysis of the obtained path shows the robustness improvement due to the non integer order properties. Pre shaping approach is used to reduce system vibration in motion control. Desired systems inputs are altered so that the system finishes the requested move without residual vibration. This technique, developed by N.C. Singer and W.P.Seering, is used for flexible structure control, particularly in the aerospace field. In a previous work, this method was extended for explicit fractional derivative systems and applied to second generation CRONE control, the robustness was also studied. CRONE (the French acronym of C ommande Robuste d'Ordre Non Entier ) control system design is a frequency-domain based methodology using complex fractional integration.

  10. X-ray spectrometry and X-ray microtomography techniques for soil and geological samples analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kubala-Kukuś, A.; Banaś, D.; Braziewicz, J. [Institute of Physics, Jan Kochanowski University, ul. Świetokrzyska 15, 25-406 Kielce (Poland); Holycross Cancer Center, ul. Artwińskiego 3, 25-734 Kielce (Poland); Dziadowicz, M.; Kopeć, E. [Institute of Physics, Jan Kochanowski University, ul. Świetokrzyska 15, 25-406 Kielce (Poland); Majewska, U. [Institute of Physics, Jan Kochanowski University, ul. Świetokrzyska 15, 25-406 Kielce (Poland); Holycross Cancer Center, ul. Artwińskiego 3, 25-734 Kielce (Poland); Mazurek, M.; Pajek, M.; Sobisz, M.; Stabrawa, I. [Institute of Physics, Jan Kochanowski University, ul. Świetokrzyska 15, 25-406 Kielce (Poland); Wudarczyk-Moćko, J. [Holycross Cancer Center, ul. Artwińskiego 3, 25-734 Kielce (Poland); Góźdź, S. [Holycross Cancer Center, ul. Artwińskiego 3, 25-734 Kielce (Poland); Institute of Public Health, Jan Kochanowski University, IX Wieków Kielc 19, 25-317 Kielce (Poland)

    2015-12-01

    A particular subject of X-ray fluorescence analysis is its application in studies of the multielemental sample of composition in a wide range of concentrations, samples with different matrices, also inhomogeneous ones and those characterized with different grain size. Typical examples of these kinds of samples are soil or geological samples for which XRF elemental analysis may be difficult due to XRF disturbing effects. In this paper the WDXRF technique was applied in elemental analysis concerning different soil and geological samples (therapeutic mud, floral soil, brown soil, sandy soil, calcium aluminum cement). The sample morphology was analyzed using X-ray microtomography technique. The paper discusses the differences between the composition of samples, the influence of procedures with respect to the preparation of samples as regards their morphology and, finally, a quantitative analysis. The results of the studies were statistically tested (one-way ANOVA and correlation coefficients). For lead concentration determination in samples of sandy soil and cement-like matrix, the WDXRF spectrometer calibration was performed. The elemental analysis of the samples was complemented with knowledge of chemical composition obtained by X-ray powder diffraction.

  11. X-ray spectrometry and X-ray microtomography techniques for soil and geological samples analysis

    International Nuclear Information System (INIS)

    Kubala-Kukuś, A.; Banaś, D.; Braziewicz, J.; Dziadowicz, M.; Kopeć, E.; Majewska, U.; Mazurek, M.; Pajek, M.; Sobisz, M.; Stabrawa, I.; Wudarczyk-Moćko, J.; Góźdź, S.

    2015-01-01

    A particular subject of X-ray fluorescence analysis is its application in studies of the multielemental sample of composition in a wide range of concentrations, samples with different matrices, also inhomogeneous ones and those characterized with different grain size. Typical examples of these kinds of samples are soil or geological samples for which XRF elemental analysis may be difficult due to XRF disturbing effects. In this paper the WDXRF technique was applied in elemental analysis concerning different soil and geological samples (therapeutic mud, floral soil, brown soil, sandy soil, calcium aluminum cement). The sample morphology was analyzed using X-ray microtomography technique. The paper discusses the differences between the composition of samples, the influence of procedures with respect to the preparation of samples as regards their morphology and, finally, a quantitative analysis. The results of the studies were statistically tested (one-way ANOVA and correlation coefficients). For lead concentration determination in samples of sandy soil and cement-like matrix, the WDXRF spectrometer calibration was performed. The elemental analysis of the samples was complemented with knowledge of chemical composition obtained by X-ray powder diffraction.

  12. Multi-technique approach for deriving a VLBI signal extra-path variation model induced by gravity: the example of Medicina

    Science.gov (United States)

    Sarti, P.; Abbondanza, C.; Negusini, M.; Vittuari, L.

    2009-09-01

    During the measurement sessions gravity might induce significant deformations in large VLBI telescopes. If neglected or mismodelled, these deformations might bias the phase of the incoming signal thus corrupting the estimate of some crucial geodetic parameters (e.g. the height component of VLBI Reference Point). This paper describes a multi-technique approach implemented for measuring and quantifying the gravity-dependent deformations experienced by the 32-m diameter VLBI antenna of Medicina (Northern Italy). Such an approach integrates three different methods: Terrestrial Triangulations and Trilaterations (TTT), Laser Scanning (LS) and a Finite Element Model (FEM) of the antenna. The combination of the observations performed with these methods allows to accurately define an elevation-dependent model of the signal path variation which appears to be, for the Medicina telescope, non negligible. In the range [0,90] deg the signal path increases monotonically by almost 2 cm. The effect of such a variation has not been introduced in actual VLBI analysis yet; nevertheless this is the task we are going to pursue in the very next future.

  13. Improved importance sampling technique for efficient simulation of digital communication systems

    Science.gov (United States)

    Lu, Dingqing; Yao, Kung

    1988-01-01

    A new, improved importance sampling (IIS) approach to simulation is considered. Some basic concepts of IS are introduced, and detailed evolutions of simulation estimation variances for Monte Carlo (MC) and IS simulations are given. The general results obtained from these evolutions are applied to the specific previously known conventional importance sampling (CIS) technique and the new IIS technique. The derivation for a linear system with no signal random memory is considered in some detail. For the CIS technique, the optimum input scaling parameter is found, while for the IIS technique, the optimum translation parameter is found. The results are generalized to a linear system with memory and signals. Specific numerical and simulation results are given which show the advantages of CIS over MC and IIS over CIS for simulations of digital communications systems.

  14. Symbol synchronization and sampling frequency synchronization techniques in real-time DDO-OFDM systems

    Science.gov (United States)

    Chen, Ming; He, Jing; Cao, Zizheng; Tang, Jin; Chen, Lin; Wu, Xian

    2014-09-01

    In this paper, we propose and experimentally demonstrate a symbol synchronization and sampling frequency synchronization techniques in real-time direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) system, over 100-km standard single mode fiber (SSMF) using a cost-effective directly modulated distributed feedback (DFB) laser. The experiment results show that the proposed symbol synchronization based on training sequence (TS) has a low complexity and high accuracy even at a sampling frequency offset (SFO) of 5000-ppm. Meanwhile, the proposed pilot-assisted sampling frequency synchronization between digital-to-analog converter (DAC) and analog-to-digital converter (ADC) is capable of estimating SFOs with an accuracy of technique can also compensate SFO effects within a small residual SFO caused by deviation of SFO estimation and low-precision or unstable clock source. The two synchronization techniques are suitable for high-speed DDO-OFDM transmission systems.

  15. A technique for extracting blood samples from mice in fire toxicity tests

    Science.gov (United States)

    Bucci, T. J.; Hilado, C. J.; Lopez, M. T.

    1976-01-01

    The extraction of adequate blood samples from moribund and dead mice has been a problem because of the small quantity of blood in each animal and the short time available between the animals' death and coagulation of the blood. These difficulties are particularly critical in fire toxicity tests because removal of the test animals while observing proper safety precautions for personnel is time-consuming. Techniques for extracting blood samples from mice were evaluated, and a technique was developed to obtain up to 0.8 ml of blood from a single mouse after death. The technique involves rapid exposure and cutting of the posterior vena cava and accumulation of blood in the peritoneal space. Blood samples of 0.5 ml or more from individual mice have been consistently obtained as much as 16 minutes after apparent death. Results of carboxyhemoglobin analyses of blood appeared reproducible and consistent with carbon monoxide concentrations in the exposure chamber.

  16. Exploring the Relationship between Reward and Punishment Sensitivity and Gambling Disorder in a Clinical Sample: A Path Modeling Analysis.

    Science.gov (United States)

    Jiménez-Murcia, Susana; Fernández-Aranda, Fernando; Mestre-Bach, Gemma; Granero, Roser; Tárrega, Salomé; Torrubia, Rafael; Aymamí, Neus; Gómez-Peña, Mónica; Soriano-Mas, Carles; Steward, Trevor; Moragas, Laura; Baño, Marta; Del Pino-Gutiérrez, Amparo; Menchón, José M

    2017-06-01

    Most individuals will gamble during their lifetime, yet only a select few will develop gambling disorder. Gray's Reinforcement Sensitivity Theory holds promise for providing insight into gambling disorder etiology and symptomatology as it ascertains that neurobiological differences in reward and punishment sensitivity play a crucial role in determining an individual's affect and motives. The aim of the study was to assess a mediational pathway, which included patients' sex, personality traits, reward and punishment sensitivity, and gambling-severity variables. The Sensitivity to Punishment and Sensitivity to Reward Questionnaire, the South Oaks Gambling Screen, the Symptom Checklist-Revised, and the Temperament and Character Inventory-Revised were administered to a sample of gambling disorder outpatients (N = 831), diagnosed according to DSM-5 criteria, attending a specialized outpatient unit. Sociodemographic variables were also recorded. A structural equation model found that both reward and punishment sensitivity were positively and directly associated with increased gambling severity, sociodemographic variables, and certain personality traits while also revealing a complex mediational role for these dimensions. To this end, our findings suggest that the Sensitivity to Punishment and Sensitivity to Reward Questionnaire could be a useful tool for gaining a better understanding of different gambling disorder phenotypes and developing tailored interventions.

  17. Systematic comparison of static and dynamic headspace sampling techniques for gas chromatography.

    Science.gov (United States)

    Kremser, Andreas; Jochmann, Maik A; Schmidt, Torsten C

    2016-09-01

    Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample.

  18. Sampling phased array - a new technique for ultrasonic signal processing and imaging

    OpenAIRE

    Verkooijen, J.; Boulavinov, A.

    2008-01-01

    Over the past 10 years, the improvement in the field of microelectronics and computer engineering has led to significant advances in ultrasonic signal processing and image construction techniques that are currently being applied to non-destructive material evaluation. A new phased array technique, called 'Sampling Phased Array', has been developed in the Fraunhofer Institute for Non-Destructive Testing([1]). It realises a unique approach of measurement and processing of ultrasonic signals. Th...

  19. Sampling phased array, a new technique for ultrasonic signal processing and imaging now available to industry

    OpenAIRE

    Verkooijen, J.; Bulavinov, A.

    2008-01-01

    Over the past 10 years the improvement in the field of microelectronics and computer engineering has led to significant advances in ultrasonic signal processing and image construction techniques that are currently being applied to non-destructive material evaluation. A new phased array technique, called "Sampling Phased Array" has been developed in the Fraunhofer Institute for non-destructive testing [1]. It realizes a unique approach of measurement and processing of ultrasonic signals. The s...

  20. Chance constrained problems: penalty reformulation and performance of sample approximation technique

    Czech Academy of Sciences Publication Activity Database

    Branda, Martin

    2012-01-01

    Roč. 48, č. 1 (2012), s. 105-122 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GBP402/12/G097 Institutional research plan: CEZ:AV0Z10750506 Keywords : chance constrained problems * penalty functions * asymptotic equivalence * sample approximation technique * investment problem Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.619, year: 2012 http://library.utia.cas.cz/separaty/2012/E/branda-chance constrained problems penalty reformulation and performance of sample approximation technique.pdf

  1. Human mixed lymphocyte cultures. Evaluation of microculture technique utilizing the multiple automated sample harvester (MASH)

    Science.gov (United States)

    Thurman, G. B.; Strong, D. M.; Ahmed, A.; Green, S. S.; Sell, K. W.; Hartzman, R. J.; Bach, F. H.

    1973-01-01

    Use of lymphocyte cultures for in vitro studies such as pretransplant histocompatibility testing has established the need for standardization of this technique. A microculture technique has been developed that has facilitated the culturing of lymphocytes and increased the quantity of cultures feasible, while lowering the variation between replicate samples. Cultures were prepared for determination of tritiated thymidine incorporation using a Multiple Automated Sample Harvester (MASH). Using this system, the parameters that influence the in vitro responsiveness of human lymphocytes to allogeneic lymphocytes have been investigated. PMID:4271568

  2. Experimental study of laser ablation as sample introduction technique for inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    Van Winckel, S.

    2001-01-01

    The contribution consists of an abstract of a PhD thesis. In the PhD study, several complementary applications of laser-ablation were investigated in order to characterise experimentally laser ablation (LA) as a sample introduction technique for ICP-MS. Three applications of LA as a sample introduction technique are discussed: (1) the microchemical analysis of the patina of weathered marble; (2) the possibility to measure isotope ratios (in particular Pb isotope ratios in archaeological bronze artefacts); and (3) the determination of Si in Al as part of a dosimetric study of the BR2 reactor vessel

  3. Preparation of quality control samples for thyroid hormones T3 and T4 in radioimmunoassay techniques

    International Nuclear Information System (INIS)

    Ahmed, F.O.A.

    2006-03-01

    Today, the radioimmunoassay becomes one of the best techniques for quantitative analysis of very low concentration of different substances. RIA is being widely used in medical and research laboratories. To maintain high specificity and accuracy in RIA and other related techniques the quality controls must be introduced. In this dissertation quality control samples for thyroid hormones (Triiodothyronine T3 and Thyroxin T4), using RIA techniques. Ready made chinese T4, T3 RIA kits were used. IAEA statistical package were selected.(Author)

  4. Practical aspects of the resin bead technique for mass spectrometric sample loading

    International Nuclear Information System (INIS)

    Walker, R.L.; Pritchard, C.A.; Carter, J.A.; Smith, D.H.

    1976-07-01

    Using an anion resin bead as a loading vehicle for uranium and plutonium samples which are to be analyzed isotopically in a mass spectrometer has many advantages over conventional techniques. It is applicable to any laboratory routinely performing such analyses, but should be particularly relevant for Safeguards' purposes. Because the techniques required differ markedly from those of conventional methods, this report has been written to describe them in detail to enable those unfamiliar with the technique to master it with a minimum of trouble

  5. Recent advances in sample preparation techniques and methods of sulfonamides detection - A review.

    Science.gov (United States)

    Dmitrienko, Stanislava G; Kochuk, Elena V; Apyari, Vladimir V; Tolmacheva, Veronika V; Zolotov, Yury A

    2014-11-19

    Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Analysis of pure and malachite green doped polysulfone sample using FT-IR technique

    Science.gov (United States)

    Nayak, Rashmi J.; Khare, P. K.; Nayak, J. G.

    2018-05-01

    The sample of pure and malachite green doped Polysulfone in the form of foil was prepared by isothermal immersion technique. For the preparation of pure sample 4 gm of Polysulfone was dissolved in 50 ml of Dimethyl farmamide (DMF) solvent, while for the preparation of doped sample 10 mg, 50 mg and 100 mg Malachite Green was mixed with 4 gm of Polysulfone respectively. For the study of structural characterization of these pure and doped sample, Fourier Transform Infra-Red Spectroscopy (FT-IR) technique was used. This study shows that the intensity of transmittance decreases as the ratio of doping increases in pure polysulfone. The reduction in intensity of transmittance is clearly apparent in the present case more over the bands were broader which indicates towards charge transfer interaction between the donar and acceptor molecule.

  7. Sampling methods and non-destructive examination techniques for large radioactive waste packages

    International Nuclear Information System (INIS)

    Green, T.H.; Smith, D.L.; Burgoyne, K.E.; Maxwell, D.J.; Norris, G.H.; Billington, D.M.; Pipe, R.G.; Smith, J.E.; Inman, C.M.

    1992-01-01

    Progress is reported on work undertaken to evaluate quality checking methods for radioactive wastes. A sampling rig was designed, fabricated and used to develop techniques for the destructive sampling of cemented simulant waste using remotely operated equipment. An engineered system for the containment of cooling water was designed and manufactured and successfully demonstrated with the drum and coring equipment mounted in both vertical and horizontal orientations. The preferred in-cell orientation was found to be with the drum and coring machinery mounted in a horizontal position. Small powdered samples can be taken from cemented homogeneous waste cores using a hollow drill/vacuum section technique with the preferred subsampling technique being to discard the outer 10 mm layer to obtain a representative sample of the cement core. Cement blends can be dissolved using fusion techniques and the resulting solutions are stable to gelling for periods in excess of one year. Although hydrochloric acid and nitric acid are promising solvents for dissolution of cement blends, the resultant solutions tend to form silicic acid gels. An estimate of the beta-emitter content of cemented waste packages can be obtained by a combination of non-destructive and destructive techniques. The errors will probably be in excess of +/-60 % at the 95 % confidence level. Real-time X-ray video-imaging techniques have been used to analyse drums of uncompressed, hand-compressed, in-drum compacted and high-force compacted (i.e. supercompacted) simulant waste. The results have confirmed the applicability of this technique for NDT of low-level waste. 8 refs., 12 figs., 3 tabs

  8. Comparison of Techniques for Sampling Adult Necrophilous Insects From Pig Carcasses.

    Science.gov (United States)

    Cruise, Angela; Hatano, Eduardo; Watson, David W; Schal, Coby

    2018-02-06

    Studies of the pre-colonization interval and mechanisms driving necrophilous insect ecological succession depend on effective sampling of adult insects and knowledge of their diel and successional activity patterns. The number of insects trapped, their diversity, and diel periodicity were compared with four sampling methods on neonate pigs. Sampling method, time of day and decomposition age of the pigs significantly affected the number of insects sampled from pigs. We also found significant interactions of sampling method and decomposition day, time of sampling and decomposition day. No single method was superior to the other methods during all three decomposition days. Sampling times after noon yielded the largest samples during the first 2 d of decomposition. On day 3 of decomposition however, all sampling times were equally effective. Therefore, to maximize insect collections from neonate pigs, the method used to sample must vary by decomposition day. The suction trap collected the most species-rich samples, but sticky trap samples were the most diverse, when both species richness and evenness were factored into a Shannon diversity index. Repeated sampling during the noon to 18:00 hours period was most effective to obtain the maximum diversity of trapped insects. The integration of multiple sampling techniques would most effectively sample the necrophilous insect community. However, because all four tested methods were deficient at sampling beetle species, future work should focus on optimizing the most promising methods, alone or in combinations, and incorporate hand-collections of beetles. © The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Improving mouse controlling and movement for people with Parkinson's disease and involuntary tremor using adaptive path smoothing technique via B-spline.

    Science.gov (United States)

    Hashem, Seyed Yashar Bani; Zin, Nor Azan Mat; Yatim, Noor Faezah Mohd; Ibrahim, Norlinah Mohamed

    2014-01-01

    Many input devices are available for interacting with computers, but the computer mouse is still the most popular device for interaction. People who suffer from involuntary tremor have difficulty using the mouse in the normal way. The target participants of this research were individuals who suffer from Parkinson's disease. Tremor in limbs makes accurate mouse movements impossible or difficult without any assistive technologies to help. This study explores a new assistive technique-adaptive path smoothing via B-spline (APSS)-to enhance mouse controlling based on user's tremor level and type. APSS uses Mean filtering and B-spline to provide a smoothed mouse trajectory. Seven participants who have unwanted tremor evaluated APSS. Results show that APSS is very promising and greatly increases their control of the computer mouse. Result of user acceptance test also shows that user perceived APSS as easy to use. They also believe it to be a useful tool and intend to use it once it is available. Future studies could explore the possibility of integrating APSS with one assistive pointing technique, such as the Bubble cursor or the Sticky target technique, to provide an all in one solution for motor disabled users.

  10. Experimental technique to measure thoron generation rate of building material samples using RAD7 detector

    International Nuclear Information System (INIS)

    Csige, I.; Szabó, Zs.; Szabó, Cs.

    2013-01-01

    Thoron ( 220 Rn) is the second most abundant radon isotope in our living environment. In some dwellings it is present in significant amount which calls for its identification and remediation. Indoor thoron originates mainly from building materials. In this work we have developed and tested an experimental technique to measure thoron generation rate in building material samples using RAD7 radon-thoron detector. The mathematical model of the measurement technique provides the thoron concentration response of RAD7 as a function of the sample thickness. For experimental validation of the technique an adobe building material sample was selected for measuring the thoron concentration at nineteen different sample thicknesses. Fitting the parameters of the model to the measurement results, both the generation rate and the diffusion length of thoron was estimated. We have also determined the optimal sample thickness for estimating the thoron generation rate from a single measurement. -- Highlights: • RAD7 is used for the determination of thoron generation rate (emanation). • The described model takes into account the thoron decay and attenuation. • The model describes well the experimental results. • A single point measurement method is offered at a determined sample thickness

  11. Determination of metals in air samples using X-Ray fluorescence associated the APDC preconcentration technique

    Energy Technology Data Exchange (ETDEWEB)

    Nardes, Raysa C.; Santos, Ramon S.; Sanches, Francis A.C.R.A.; Gama Filho, Hamilton S.; Oliveira, Davi F.; Anjos, Marcelino J., E-mail: rc.nardes@gmail.com, E-mail: ramonziosp@yahoo.com.br, E-mail: francissanches@gmail.com, E-mail: hamiltongamafilho@hotmail.com, E-mail: davi.oliveira@uerj.br, E-mail: marcelin@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Instituto de Fisica. Departamento de Fisica Aplicada e Termodinamica

    2015-07-01

    Air pollution has become one of the leading quality degradation factors of life for people in large urban centers. Studies indicate that the suspended particulate matter in the atmosphere is directly associated with risks to public health, in addition, it can cause damage to fauna, flora and public / cultural patrimonies. The inhalable particulate materials can cause the emergence and / or worsening of chronic diseases related to respiratory system and other diseases, such as reduced physical strength. In this study, we propose a new method to measure the concentration of total suspended particulate matter (TSP) in the air using an impinger as an air cleaning apparatus, preconcentration with APDC and Total Reflection X-ray Fluorescence technique (TXRF) to analyze the heavy metals present in the air. The samples were collected from five random points in the city of Rio de Janeiro/Brazil. Analyses of TXRF were performed at the Brazilian Synchrotron Light Laboratory (LNLS). The technique proved viable because it was able to detect five important metallic elements to environmental studies: Cr, Fe, Ni, Cu and Zn. This technique presented substantial efficiency in determining the elementary concentration of air pollutants, in addition to low cost. It can be concluded that the metals analysis technique in air samples using an impinger as sample collection instrument associated with a complexing agent (APDC) was viable because it is a low-cost technique, moreover, it was possible the detection of five important metal elements in environmental studies associated with industrial emissions and urban traffic. (author)

  12. Determination of metals in air samples using X-Ray fluorescence associated the APDC preconcentration technique

    International Nuclear Information System (INIS)

    Nardes, Raysa C.; Santos, Ramon S.; Sanches, Francis A.C.R.A.; Gama Filho, Hamilton S.; Oliveira, Davi F.; Anjos, Marcelino J.

    2015-01-01

    Air pollution has become one of the leading quality degradation factors of life for people in large urban centers. Studies indicate that the suspended particulate matter in the atmosphere is directly associated with risks to public health, in addition, it can cause damage to fauna, flora and public / cultural patrimonies. The inhalable particulate materials can cause the emergence and / or worsening of chronic diseases related to respiratory system and other diseases, such as reduced physical strength. In this study, we propose a new method to measure the concentration of total suspended particulate matter (TSP) in the air using an impinger as an air cleaning apparatus, preconcentration with APDC and Total Reflection X-ray Fluorescence technique (TXRF) to analyze the heavy metals present in the air. The samples were collected from five random points in the city of Rio de Janeiro/Brazil. Analyses of TXRF were performed at the Brazilian Synchrotron Light Laboratory (LNLS). The technique proved viable because it was able to detect five important metallic elements to environmental studies: Cr, Fe, Ni, Cu and Zn. This technique presented substantial efficiency in determining the elementary concentration of air pollutants, in addition to low cost. It can be concluded that the metals analysis technique in air samples using an impinger as sample collection instrument associated with a complexing agent (APDC) was viable because it is a low-cost technique, moreover, it was possible the detection of five important metal elements in environmental studies associated with industrial emissions and urban traffic. (author)

  13. 3D-Laser-Scanning Technique Applied to Bulk Density Measurements of Apollo Lunar Samples

    Science.gov (United States)

    Macke, R. J.; Kent, J. J.; Kiefer, W. S.; Britt, D. T.

    2015-01-01

    In order to better interpret gravimetric data from orbiters such as GRAIL and LRO to understand the subsurface composition and structure of the lunar crust, it is import to have a reliable database of the density and porosity of lunar materials. To this end, we have been surveying these physical properties in both lunar meteorites and Apollo lunar samples. To measure porosity, both grain density and bulk density are required. For bulk density, our group has historically utilized sub-mm bead immersion techniques extensively, though several factors have made this technique problematic for our work with Apollo samples. Samples allocated for measurement are often smaller than optimal for the technique, leading to large error bars. Also, for some samples we were required to use pure alumina beads instead of our usual glass beads. The alumina beads were subject to undesirable static effects, producing unreliable results. Other investigators have tested the use of 3d laser scanners on meteorites for measuring bulk volumes. Early work, though promising, was plagued with difficulties including poor response on dark or reflective surfaces, difficulty reproducing sharp edges, and large processing time for producing shape models. Due to progress in technology, however, laser scanners have improved considerably in recent years. We tested this technique on 27 lunar samples in the Apollo collection using a scanner at NASA Johnson Space Center. We found it to be reliable and more precise than beads, with the added benefit that it involves no direct contact with the sample, enabling the study of particularly friable samples for which bead immersion is not possible

  14. Review of sample preparation techniques for the analysis of pesticide residues in soil.

    Science.gov (United States)

    Tadeo, José L; Pérez, Rosa Ana; Albero, Beatriz; García-Valcárcel, Ana I; Sánchez-Brunete, Consuelo

    2012-01-01

    This paper reviews the sample preparation techniques used for the analysis of pesticides in soil. The present status and recent advances made during the last 5 years in these methods are discussed. The analysis of pesticide residues in soil requires the extraction of analytes from this matrix, followed by a cleanup procedure, when necessary, prior to their instrumental determination. The optimization of sample preparation is a very important part of the method development that can reduce the analysis time, the amount of solvent, and the size of samples. This review considers all aspects of sample preparation, including extraction and cleanup. Classical extraction techniques, such as shaking, Soxhlet, and ultrasonic-assisted extraction, and modern techniques like pressurized liquid extraction, microwave-assisted extraction, solid-phase microextraction and QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) are reviewed. The different cleanup strategies applied for the purification of soil extracts are also discussed. In addition, the application of these techniques to environmental studies is considered.

  15. A review of analytical techniques for the determination of carbon-14 in environmental samples

    International Nuclear Information System (INIS)

    Milton, G.M.; Brown, R.M.

    1993-11-01

    This report contains a brief summary of analytical techniques commonly used for the determination of radiocarbon in a variety of environmental samples. Details of the applicable procedures developed and tested in the Environmental Research Branch at Chalk River Laboratories are appended

  16. Attempts to develop a new nuclear measurement technique of β-glucuronidase levels in biological samples

    International Nuclear Information System (INIS)

    Unak, T.; Avcibasi, U.; Yildirim, Y.; Cetinkaya, B.

    2003-01-01

    β-Glucuronidase is one of the most important hydrolytic enzymes in living systems and plays an essential role in the detoxification pathway of toxic materials incorporated into the metabolism. Some organs, especially liver and some tumour tissues, have high level of β-glucuronidase activity. As a result the enzymatic activity of some kind of tumour cells, the radiolabelled glucuronide conjugates of cytotoxic, as well as radiotoxic compounds have potentially very valuable diagnostic and therapeutic applications in cancer research. For this reason, a sensitive measurement of β-glucuronidase levels in normal and tumour tissues is a very important step for these kinds of applications. According to the classical measurement method of β-glucuronidase activity, in general, the quantity of phenolphthalein liberated from its glucuronide conjugate, i.e. phenolphthalein-glucuronide, by β-glucuronidase has been measured by use of the spectrophotometric technique. The lower detection limit of phenolphthalein by the spectrophotometric technique is about 1-3 mg. This means that the β-glucuronidase levels could not be detected in biological samples having lower levels of β-glucuronidase activity and therefore the applications of the spectrophotometric technique in cancer research are very seriously limited. Starting from this consideration, we recently attempted to develop a new nuclear technique to measure much lower concentrations of β-glucuronidase in biological samples. To improve the detection limit, phenolphthalein-glucuronide and also phenyl-N-glucuronide were radioiodinated with 131 I and their radioactivity was measured by use of the counting technique. Therefore, the quantity of phenolphthalein or aniline radioiodinated with 131 I and liberated by the deglucuronidation reactivity of β-glucuronidase was used in an attempt to measure levels lower than the spectrophotometric measurement technique. The results obtained clearly verified that 0.01 pg level of

  17. Atmospheric pressure surface sampling/ionization techniques for direct coupling of planar separations with mass spectrometry.

    Science.gov (United States)

    Pasilis, Sofie P; Van Berkel, Gary J

    2010-06-18

    Planar separations, which include thin layer chromatography and gel electrophoresis, are in widespread use as important and powerful tools for conducting separations of complex mixtures. To increase the utility of planar separations, new methods are needed that allow in situ characterization of the individual components of the separated mixtures. A large number of atmospheric pressure surface sampling and ionization techniques for use with mass spectrometry have emerged in the past several years, and several have been investigated as a means for mass spectrometric read-out of planar separations. In this article, we review the atmospheric pressure surface sampling and ionization techniques that have been used for the read-out of planar separation media. For each technique, we briefly explain the operational basics and discuss the analyte type for which it is appropriate and some specific applications from the literature. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  18. Random sampling technique for ultra-fast computations of molecular opacities for exoplanet atmospheres

    Science.gov (United States)

    Min, M.

    2017-10-01

    Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.

  19. THE STUDY OF HEAVY METAL FROM ENVIRONMENTAL SAMPLES BY ATOMIC TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Ion V. POPESCU

    2011-05-01

    Full Text Available Using the Atomic Absorption Spectrometry (AAS and Energy Dispersive X-ray spectrometry (EDXRF techniques we analyzed the contents of heavy metals ( Cd, Cr, Ni, Pb, Ti, Sr, Co, Bi from eight wild mushrooms and soil substrate samples (48 samples of eight fungal species and 32 underlying soil samples, collected from ten forest sites of Dambovița County Romania. It was determined that the elements, especially heavy metals, in soil were characteristic of the acidic soils of the Romanian forest lands and are influenced by industrial pollution. Analytical possibilities of AAS and EDXRF analytical techniques have been compared and the heavy metal transfer from substrate to mushrooms has been studied. The coefficient of accumulation of essential and heavy metals has been calculated as well. Heavy metal contents of all analyzed mushrooms were generally higher than previously reported in literature.

  20. Toward greener analytical techniques for the absolute quantification of peptides in pharmaceutical and biological samples.

    Science.gov (United States)

    Van Eeckhaut, Ann; Mangelings, Debby

    2015-09-10

    Peptide-based biopharmaceuticals represent one of the fastest growing classes of new drug molecules. New reaction types included in the synthesis strategies to reduce the rapid metabolism of peptides, along with the availability of new formulation and delivery technologies, resulted in an increased marketing of peptide drug products. In this regard, the development of analytical methods for quantification of peptides in pharmaceutical and biological samples is of utmost importance. From the sample preparation step to their analysis by means of chromatographic or electrophoretic methods, many difficulties should be tackled to analyze them. Recent developments in analytical techniques emphasize more and more on the use of green analytical techniques. This review will discuss the progresses in and challenges observed during green analytical method development for the quantification of peptides in pharmaceutical and biological samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. [Influence of Natural Dissolved Organic Matter on the Passive Sampling Technique and its Application].

    Science.gov (United States)

    Yu, Shang-yun; Zhou, Yan-mei

    2015-08-01

    This paper studied the effects of different concentrations of natural dissolved organic matter (DOM) on the passive sampling technique. The results showed that the presence of DOM affected the organic pollutant adsorption ability of the membrane. For lgK(OW), 3-5, DOM had less impact on the adsorption of organic matter by the membrane; for lgK(OW), > 5.5, DOM significantly increased the adsorption capacity of the membrane. Meanwhile, LDPE passive sampling technique was applied to monitor PAHs and PAEs in pore water of three surface sediments in Taizi River. All of the target pollutants were detected in varying degrees at each sampling point. Finally, the quotient method was used to assess the ecological risks of PAHs and PAEs. The results showed that fluoranthene exceeded the reference value of the aquatic ecosystem, meaning there was a big ecological risk.

  2. Estimation of trace levels of plutonium in urine samples by fission track technique

    International Nuclear Information System (INIS)

    Sawant, P.D.; Prabhu, S.; Pendharkar, K.A.; Kalsi, P.C.

    2009-01-01

    Individual monitoring of radiation workers handling Pu in various nuclear installations requires the detection of trace levels of plutonium in bioassay samples. It is necessary to develop methods that can detect urinary excretion of Pu in fraction of mBq range. Therefore, a sensitive method such as fission track analysis has been developed for the measurement of trace levels of Pu in bioassay samples. In this technique, chemically separated plutonium from the sample and a Pu standard were electrodeposited on planchettes and covered with Lexan solid state nuclear track detector (SSNTD) and irradiated with thermal neutrons in APSARA reactor of Bhabha Atomic Research Centre, India. The fission track densities in the Lexan films of the sample and the standard were used to calculate the amount of Pu in the sample. The minimum amount of Pu that can be analyzed by this method using doubly distilled electronic grade (E. G.) reagents is about 12 μBq/L. (author)

  3. A radioanalytical technique using (n,2n) reaction for the elemental analysis of samples

    International Nuclear Information System (INIS)

    Labor, M.

    1985-11-01

    A technique to determine elemental composition of samples is reported. The principle of the technique employs the internal standard method and involves the resolution of complex annihilation spectra. The technique has been applied to the determination of the mass of nitrogen, msub(N), and that of potassium, msub(K), in known masses of potassium nitrate. The percentage difference between the calculated mass and actual masses in 2g and 3g of potassium nitrate is 1.0 and 0.7 respectively for potassium, and 1.0 for nitrogen. The use of more simultaneous equations than necessary in solving for msub(N) and msub(K) offers one of the advantages of the technique. (author)

  4. Accelerated Solvent Extraction: An Innovative Sample Extraction Technique for Natural Products

    International Nuclear Information System (INIS)

    Hazlina Ahmad Hassali; Azfar Hanif Abd Aziz; Rosniza Razali

    2015-01-01

    Accelerated solvent extraction (ASE) is one of the novel techniques that have been developed for the extraction of phytochemicals from plants in order to shorten the extraction time, decrease the solvent consumption, increase the extraction yield and enhance the quality of extracts. This technique combines elevated temperatures and pressure with liquid solvents. This paper gives a brief overview of accelerated solvent extraction technique for sample preparation and its application to the extraction of natural products. Through practical examples, the effects of operational parameters such as temperature, volume of solvent used, extraction time and extraction yields on the performance of ASE are discussed. It is demonstrated that ASE technique allows reduced solvent consumption and shorter extraction time, while the extraction yields are even higher than those obtained with conventional methods. (author)

  5. Lot quality assurance sampling techniques in health surveys in developing countries: advantages and current constraints.

    Science.gov (United States)

    Lanata, C F; Black, R E

    1991-01-01

    Traditional survey methods, which are generally costly and time-consuming, usually provide information at the regional or national level only. The utilization of lot quality assurance sampling (LQAS) methodology, developed in industry for quality control, makes it possible to use small sample sizes when conducting surveys in small geographical or population-based areas (lots). This article describes the practical use of LQAS for conducting health surveys to monitor health programmes in developing countries. Following a brief description of the method, the article explains how to build a sample frame and conduct the sampling to apply LQAS under field conditions. A detailed description of the procedure for selecting a sampling unit to monitor the health programme and a sample size is given. The sampling schemes utilizing LQAS applicable to health surveys, such as simple- and double-sampling schemes, are discussed. The interpretation of the survey results and the planning of subsequent rounds of LQAS surveys are also discussed. When describing the applicability of LQAS in health surveys in developing countries, the article considers current limitations for its use by health planners in charge of health programmes, and suggests ways to overcome these limitations through future research. It is hoped that with increasing attention being given to industrial sampling plans in general, and LQAS in particular, their utilization to monitor health programmes will provide health planners in developing countries with powerful techniques to help them achieve their health programme targets.

  6. Techniques of sample attack used in soil and mineral analysis. Phase I

    International Nuclear Information System (INIS)

    Chiu, N.W.; Dean, J.R.; Sill, C.W.

    1984-07-01

    Several techniques of sample attack for the determination of radioisotopes are reviewed. These techniques include: 1) digestion with nitric or hydrochloric acid in Parr digestion bomb, 2) digestion with a mixture of nitric and hydrochloric acids, 3) digestion with a mixture of hydrofluoric, nitric and perchloric acids, and 4) fusion with sodium carbonate, potassium fluoride or alkali pyrosulfates. The effectiveness of these techniques to decompose various soils and minerals containing radioisotopes such as lead-210 uranium, thorium and radium-226 are discussed. The combined procedure of potassium fluoride fusion followed by alkali pyrosulfate fusion is recommended for radium-226, uranium and thorium analysis. This technique guarantees the complete dissolution of samples containing refractory materials such as silica, silicates, carbides, oxides and sulfates. For the lead-210 analysis, the procedure of digestion with a mixture of hydrofluoric, nitric and perchloric acids followed by fusion with alkali pyrosulfate is recommended. These two procedures are detailed. Schemes for the sequential separation of the radioisotopes from a dissolved sample solution are outlined. Procedures for radiochemical analysis are suggested

  7. The role of graphene-based sorbents in modern sample preparation techniques.

    Science.gov (United States)

    de Toffoli, Ana Lúcia; Maciel, Edvaldo Vasconcelos Soares; Fumes, Bruno Henrique; Lanças, Fernando Mauro

    2018-01-01

    The application of graphene-based sorbents in sample preparation techniques has increased significantly since 2011. These materials have good physicochemical properties to be used as sorbent and have shown excellent results in different sample preparation techniques. Graphene and its precursor graphene oxide have been considered to be good candidates to improve the extraction and concentration of different classes of target compounds (e.g., parabens, polycyclic aromatic hydrocarbon, pyrethroids, triazines, and so on) present in complex matrices. Its applications have been employed during the analysis of different matrices (e.g., environmental, biological and food). In this review, we highlight the most important characteristics of graphene-based material, their properties, synthesis routes, and the most important applications in both off-line and on-line sample preparation techniques. The discussion of the off-line approaches includes methods derived from conventional solid-phase extraction focusing on the miniaturized magnetic and dispersive modes. The modes of microextraction techniques called stir bar sorptive extraction, solid phase microextraction, and microextraction by packed sorbent are discussed. The on-line approaches focus on the use of graphene-based material mainly in on-line solid phase extraction, its variation called in-tube solid-phase microextraction, and on-line microdialysis systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 238U And 232Th Concentration In Rock Samples using Alpha Autoradiography and Gamma Spectroscopy Techniques

    International Nuclear Information System (INIS)

    Hafez, A.F.; El-Farrash, A.H.; Yousef, H.A.

    2009-01-01

    The activity concentrations of uranium and thorium were measured for some rock samples selected from Dahab region in the south tip of Sinai. In order to detect any harmful radiation that would affect on the tourists and is becoming economic resource because Dahab have open fields of tourism in Egypt. The activity concentration of uranium and thorium in rocks samples was measured using two techniques. The first is .-autoradiography technique with LR-115 and CR-39 detectors and the second is gamma spectroscopic technique with NaI(Tl) detector. It was found that the average activity concentrations of uranium and thorium using .-autoradiography technique ranged from 6.41-49.31 Bqkg-1, 4.86- 40.87 Bqkg-1 respectively and by gamma detector are ranged from 6.70- 49.50 Bqkg-1, 4.47- 42.33 Bqkg-1 respectively. From the obtained data we can conclude that there is no radioactive healthy hazard for human and living beings in the area under investigation. It was found that there are no big differences between the calculated thorium to uranium ratios in both techniques

  9. Review of online coupling of sample preparation techniques with liquid chromatography.

    Science.gov (United States)

    Pan, Jialiang; Zhang, Chengjiang; Zhang, Zhuomin; Li, Gongke

    2014-03-07

    Sample preparation is still considered as the bottleneck of the whole analytical procedure, and efforts has been conducted towards the automation, improvement of sensitivity and accuracy, and low comsuption of organic solvents. Development of online sample preparation techniques (SP) coupled with liquid chromatography (LC) is a promising way to achieve these goals, which has attracted great attention. This article reviews the recent advances on the online SP-LC techniques. Various online SP techniques have been described and summarized, including solid-phase-based extraction, liquid-phase-based extraction assisted with membrane, microwave assisted extraction, ultrasonic assisted extraction, accelerated solvent extraction and supercritical fluids extraction. Specially, the coupling approaches of online SP-LC systems and the corresponding interfaces have been discussed and reviewed in detail, such as online injector, autosampler combined with transport unit, desorption chamber and column switching. Typical applications of the online SP-LC techniques have been summarized. Then the problems and expected trends in this field are attempted to be discussed and proposed in order to encourage the further development of online SP-LC techniques. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Advances in modern sample preparation techniques using microwaves assisted chemistry for metal species determination (W1)

    International Nuclear Information System (INIS)

    Ponard, O.F.X.

    2002-01-01

    Full text: Sample preparation has long been the bottleneck of environmental analysis for both total and species specific analysis. Digestion, extraction and preparation of the analytes are relying on a series of chemical reactions. The introduction of microwave assisted sample preparation has first been viewed as a mean to accelerate the kinetics of digestion of the matrix for total elements and fast samples preparation procedures. However, the extensive development and success of microwave digestion procedures in total elemental analysis has now allowed to have a larger insight of the perspectives offered by this technique. Microwave technologies now offer to have a precise control of the temperature and indirectly control the reaction kinetics taking place during the sample preparation procedures. Microwave assisted chemistry permits to perform simultaneously the fundamental steps required for metal species extraction and derivatization. The number of sample preparation steps used for organotin or organomercury species have been reduced to one and the total time of sample preparation brought down for a few hours to some minutes. Further, the developments of GC/ICP/MS techniques allow to routinely use speciated isotopic dilution methods has internal probe of the chemical reactions. These new approaches allow us to use the addition of the labeled species for isotopic dilution as a mean to evaluate and follow the chemical processes taking place during the extraction procedure. These procedures will help us to understand and check for the stability of the analytes during the chemistry of the sample preparation procedure and bring some insights of the chemistry taking place during the extraction. Understanding the different mechanisms involved in the sample preparation steps will allow us in return to further improve all theses procedures and bring us to the horizon of 'on-line sample preparation and detection'. (author)

  11. Determination of some trace elements in biological samples using XRF and TXRF techniques

    International Nuclear Information System (INIS)

    Khuder, A.; Karjou, J.; Sawan, M. K.

    2006-07-01

    XRF and TXRF techniques were successfully used for the multi-element determination of trace elements in whole blood and human head hair samples. This was achieved by the direct analysis using XRF technique with different collimation units and by the optimized chemical procedures for TXRF analysis. Light element of S and P were preferably determined by XRF with primary x-ray excitation, while, elements of K, Ca, Fe, and Br were determined with a very good accuracy and precision using XRF with Cu- and Mo-secondary targets. The chemical procedure dependent on the preconcentration of trace elements by APDC was superiorly used for the determination of traces of Ni and Pb in the range of 1.0-1.7 μg/dl and 11-23 μg/dl, respectively, in whole blood samples by TXRF technique; determination of other elements as Cu and Zn was also achievable using this approach. Rb in whole blood samples was determined directly after the digestion of samples using PTFE-bomb for TXRF analysis. (author)

  12. Direct sampling technique of bees on Vriesea philippocoburgii (Bromeliaceae, Tillandsioideae flowers

    Directory of Open Access Journals (Sweden)

    Afonso Inácio Orth

    2004-11-01

    Full Text Available In our study on Vriesea philippocoburgii Wawra pollination, due to the small proportion of flowers in anthesis on a single day and the damage caused to inflorescences when netting directly on flowers, we used the direct sampling technique (DST of bees on flowers. This technique was applied to 40 flowering plants and resulted in the capture of 160 specimens, belonging to nine genera of Apoidea and separated into 19 morph species. As DST maintains the integrity of flowers for later Bees’ visits, it can enhance the survey’s performance, constituting an alternative methodology for the collection of bees visiting flowering plants.

  13. Determination of trace element contents in grass samples for cattle feeding using NAA techniques

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Alias Mohamad; Jagir Singh, Jasbir Kaur

    1987-09-01

    An investigation on trace elements contents in six types of grass samples used for cattle feeding have been carried out using NAA techniques. The grass samples, Mardi Digit, African Star, Signal, Guinea, Setaria and Setaria Splendida were found to contain at least 19 trace elements in varying concentrations. The results were compared to the figures obtained from available sources to ascertain the status as to whether the grass samples studied would satisfy the minimum requirements of trace elements present in grass for cattle feeding or otherwise. Preference made on the suitability of the grass samples for cattle feeding was based on the availability and abundance of the trace elements, taking into account factors such as the degree of toxicity, inadequate amounts and contamination due to the presence of other trace elements not essential for cattle feeding.

  14. Determination of trace element contents in grass samples for cattle feeding using NAA techniques

    International Nuclear Information System (INIS)

    Alias Mohamad Yusof; Jasbir Kaur Jagir Singh

    1987-01-01

    An investigation on trace elements contents in six types of grass samples used for cattle feeding have been carried out using NAA techniques. The grass samples, Mardi Digit, African Star, Signal, Guinea, Setaria and Setaria Splendida were found to contain at least 19 trace elements in varying concentrations. The results were compared to the figures obtained from available sources to ascertain the status as to whether the grass samples studied would satisfy the minimum requirements of trace elements present in grass for cattle feeding or otherwise. Preference made on the suitability of the grass samples for cattle feeding was based on the availability and abundance of the trace elements, taking into account factors such as the degree of toxicity, inadequate amounts and contamination due to the presence of other trace elements not essential for cattle feeding. (author)

  15. Sampling methods for rumen microbial counts by Real-Time PCR techniques

    Directory of Open Access Journals (Sweden)

    S. Puppo

    2010-02-01

    Full Text Available Fresh rumen samples were withdrawn from 4 cannulated buffalo females fed a fibrous diets in order to quantify bacteria concentration in the rumen by Real-Time PCR techniques. To obtain DNA of a good quality from whole rumen fluid, eight (M1-M8 different pre-filtration methods (cheese cloths, glass-fibre and nylon filter in combination with various centrifugation speeds (1000, 5000 and 14,000 rpm were tested. Genomic DNA extraction was performed either on fresh or frozen samples (-20°C. The quantitative bacteria analysis was realized according to Real-Time PCR procedure for Butyrivibrio fibrisolvens reported in literature. M5 resulted the best sampling procedure allowing to obtain a suitable genomic DNA. No differences were revealed between fresh and frozen samples.

  16. Application of digital sampling techniques to particle identification in scintillation detectors

    International Nuclear Information System (INIS)

    Bardelli, L.; Bini, M.; Poggi, G.; Taccetti, N.

    2002-01-01

    In this paper, the use of a fast digitizing system for identification of fast charged particles with scintillation detectors is discussed. The three-layer phoswich detectors developed in the framework of the FIASCO experiment for the detection of light charged particles (LCP) and intermediate mass fragments (IMF) emitted in heavy-ion collisions at Fermi energies are briefly discussed. The standard analog electronics treatment of the signals for particle identification is illustrated. After a description of the digitizer designed to perform a fast digital sampling of the phoswich signals, the feasibility of particle identification on the sampled data is demonstrated. The results obtained with two different pulse shape discrimination analyses based on the digitally sampled data are compared with the standard analog signal treatment. The obtained results suggest, for the present application, the replacement of the analog methods with the digital sampling technique

  17. Uranium content measurement in drinking water samples using track etch technique

    International Nuclear Information System (INIS)

    Kumar, Mukesh; Kumar, Ajay; Singh, Surinder; Mahajan, R.K.; Walia, T.P.S.

    2003-01-01

    The concentration of uranium has been assessed in drinking water samples collected from different locations in Bathinda district, Punjab, India. The water samples are taken from hand pumps and tube wells. Uranium is determined using fission track technique. Uranium concentration in the water samples varies from 1.65±0.06 to 74.98±0.38 μg/l. These values are compared with safe limit values recommended for drinking water. Most of the water samples are found to have uranium concentration above the safe limit. Analysis of some heavy metals (Zn, Cd, Pb and Cu) in water is also done in order to see if some correlation exists between the concentration of uranium and these heavy metals. A weak positive correlation has been observed between the concentration of uranium and heavy metals of Pb, Cd and Cu

  18. Recent Trends in Microextraction Techniques Employed in Analytical and Bioanalytical Sample Preparation

    Directory of Open Access Journals (Sweden)

    Abuzar Kabir

    2017-12-01

    Full Text Available Sample preparation has been recognized as a major step in the chemical analysis workflow. As such, substantial efforts have been made in recent years to simplify the overall sample preparation process. Major focusses of these efforts have included miniaturization of the extraction device; minimizing/eliminating toxic and hazardous organic solvent consumption; eliminating sample pre-treatment and post-treatment steps; reducing the sample volume requirement; reducing extraction equilibrium time, maximizing extraction efficiency etc. All these improved attributes are congruent with the Green Analytical Chemistry (GAC principles. Classical sample preparation techniques such as solid phase extraction (SPE and liquid-liquid extraction (LLE are being rapidly replaced with emerging miniaturized and environmentally friendly techniques such as Solid Phase Micro Extraction (SPME, Stir bar Sorptive Extraction (SBSE, Micro Extraction by Packed Sorbent (MEPS, Fabric Phase Sorptive Extraction (FPSE, and Dispersive Liquid-Liquid Micro Extraction (DLLME. In addition to the development of many new generic extraction sorbents in recent years, a large number of molecularly imprinted polymers (MIPs created using different template molecules have also enriched the large cache of microextraction sorbents. Application of nanoparticles as high-performance extraction sorbents has undoubtedly elevated the extraction efficiency and method sensitivity of modern chromatographic analyses to a new level. Combining magnetic nanoparticles with many microextraction sorbents has opened up new possibilities to extract target analytes from sample matrices containing high volumes of matrix interferents. The aim of the current review is to critically audit the progress of microextraction techniques in recent years, which has indisputably transformed the analytical chemistry practices, from biological and therapeutic drug monitoring to the environmental field; from foods to phyto

  19. Development of Large Sample Neutron Activation Technique for New Applications in Thailand

    International Nuclear Information System (INIS)

    Laoharojanaphand, S.; Tippayakul, C.; Wonglee, S.; Channuie, J.

    2018-01-01

    The development of the Large Sample Neutron Activation Analysis (LSNAA) in Thailand is presented in this paper. The technique had been firstly developed with rice sample as the test subject. The Thai Research Reactor-1/Modification 1 (TRR-1/M1) was used as the neutron source. The first step was to select and characterize an appropriate irradiation facility for the research. An out-core irradiation facility (A4 position) was first attempted. The results performed with the A4 facility were then used as guides for the subsequent experiments with the thermal column facility. The characterization of the thermal column was performed with Cu-wire to determine spatial distribution without and with rice sample. The flux depression without rice sample was observed to be less than 30% while the flux depression with rice sample increased to within 60%. The flux monitors internal to the rice sample were used to determine average flux over the rice sample. The gamma selfshielding effect during gamma measurement was corrected using the Monte Carlo simulation. The ratio between the efficiencies of the volume source and the point source for each energy point was calculated by the MCNPX code. The research team adopted the k0-NAA methodology to calculate the element concentration in the research. The k0-NAA program which developed by IAEA was set up to simulate the conditions of the irradiation and measurement facilities used in this research. The element concentrations in the bulk rice sample were then calculated taking into account the flux depression and gamma efficiency corrections. At the moment, the results still show large discrepancies with the reference values. However, more research on the validation will be performed to identify sources of errors. Moreover, this LS-NAA technique was introduced for the activation analysis of the IAEA archaeological mock-up. The results are provided in this report. (author)

  20. Characterization of Some Iraqi Archaeological Samples Using IBA, Analytical X-ray and Other Complementary Techniques

    International Nuclear Information System (INIS)

    Al-Sarraj, Ziyad Shihab; Damboos, Hassan I; Roumie, Mohamad

    2012-01-01

    The present work aimed at investigating the compositions and microstructures of some archaeological samples which dated back to various periods of the ancient Iraqi civilizations using PIXE, XRF, XRD, and SEM techniques. The models selected for the study (ceramics, glaze, etc.) were diverse in size and nature, therefore a limited number of samples were then butted from them by a small diamond wheel. Conventional powder metallurgy method was then used to prepare the samples. Dried samples were then coated with a thin layer of carbon, and analyzed using the ion beam accelerator of the LAEC. Three other groups of samples were also prepared for the purpose of analysis by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscope (SEM). Analysis results of the chemical composition showed good agreement between the various techniques as well as for phases, while the fine structure analysis obtained by optical and scanning microscopy exhibited features of a structure where it got an intensified densification in the final stage of sintering and accompanied by quasi-homogeneous distribution of the closed pores. This will lead to the conclusion that the temperature used for sintering by ancient Iraqi was sufficient and it may fall in the range between 950-1200°C, also the mixes and the forming methods used by them, were both suitable to obtain good sintered bodies with even distribution of pores. A ring-shaped trace noticed in SEM micrographs need more work and study to explain what it is?

  1. Determination of elements in industrial waste sample and TENORM using XRF Technique in Nuclear Malaysia

    International Nuclear Information System (INIS)

    Paulus, W.; Sarimah Mahat; Meor Yusoff Meor Sulaiman

    2011-01-01

    Industrial waste such as aluminium dross and TENORM waste, oil sludge has been used as sample in this research. Determination of main elements by using X-Ray Fluorescence (XRF) in Material Technology Group, Malaysian Nuclear Agency. Results shows that main elements in these samples, aluminium and silicon, respectively. Thereby, this research shows that XRF can be considered as one of the techniques that can be used in waste characterization and furthermore, it can help researchers and engineer in the research related to waste treatment especially radioactive waste. (author)

  2. Application of nuclear and allied techniques for the characterisation of forensic samples

    International Nuclear Information System (INIS)

    Sudersanan, M.; Kayasth, S.R.; Pant, D.R.; Chattopadhyay, N.; Bhattacharyya, C.N.

    2002-01-01

    Full text: Forensic science deals with the application of various techniques for physics, chemistry and biology for crime investigation. The legal implication of such analysis put considerable restriction on the choice of analytical techniques. Moreover, the unknown nature of the materials, the limited availability of samples and the large number of elements to be analysed put considerable strain on the analytical chemist on the selection of the appropriate technique. The availability of nuclear techniques has considerably enhanced the scope of forensic analysis. This paper deals with the recent results on the use of nuclear and allied analytical techniques for forensic applications. One of the important types of samples of forensic importance pertain to the identification of gunshot residues. The use of nuclear techniques has considerably simplified the interpretation of results through the use of appropriate elements like Ba, Cu, Sb, Zn, As and Sn etc. The combination of non-nuclear techniques for elements like Pb and Ni which are not easily amenable to be analysed by NAA and the use of appropriate separation procedure has led to the use of this method as a valid and versatile analytical procedure. In view of the presence of a large amounts of extraneous materials like cloth, body tissues etc in these samples and the limited availability of materials, the procedures for sample collection, dissolution and analysis have been standardized. Analysis of unknown materials like powders, metallic pieces etc. for the possible presence of nuclear materials or as materials in illicit trafficking is becoming important in recent years. The use of multi-technique approach is important in this case. Use of non-destructive techniques like XRF and radioactive counting enables the preliminary identification of materials and for the detection of radioactivity. Subsequent analysis by NAA or other appropriate analytical methods allows the characterization of the materials. Such

  3. Computing Diffeomorphic Paths for Large Motion Interpolation.

    Science.gov (United States)

    Seo, Dohyung; Jeffrey, Ho; Vemuri, Baba C

    2013-06-01

    In this paper, we introduce a novel framework for computing a path of diffeomorphisms between a pair of input diffeomorphisms. Direct computation of a geodesic path on the space of diffeomorphisms Diff (Ω) is difficult, and it can be attributed mainly to the infinite dimensionality of Diff (Ω). Our proposed framework, to some degree, bypasses this difficulty using the quotient map of Diff (Ω) to the quotient space Diff ( M )/ Diff ( M ) μ obtained by quotienting out the subgroup of volume-preserving diffeomorphisms Diff ( M ) μ . This quotient space was recently identified as the unit sphere in a Hilbert space in mathematics literature, a space with well-known geometric properties. Our framework leverages this recent result by computing the diffeomorphic path in two stages. First, we project the given diffeomorphism pair onto this sphere and then compute the geodesic path between these projected points. Second, we lift the geodesic on the sphere back to the space of diffeomerphisms, by solving a quadratic programming problem with bilinear constraints using the augmented Lagrangian technique with penalty terms. In this way, we can estimate the path of diffeomorphisms, first, staying in the space of diffeomorphisms, and second, preserving shapes/volumes in the deformed images along the path as much as possible. We have applied our framework to interpolate intermediate frames of frame-sub-sampled video sequences. In the reported experiments, our approach compares favorably with the popular Large Deformation Diffeomorphic Metric Mapping framework (LDDMM).

  4. Coacervative extraction as a green technique for sample preparation for the analysis of organic compounds.

    Science.gov (United States)

    Melnyk, A; Wolska, L; Namieśnik, J

    2014-04-25

    One of the present trends in analytical chemistry is miniaturization, which is one of the methods of green analytical chemistry application. A particular emphasis is placed on the elimination of the use of large amounts of organic solvents which are toxic and harmful to the environment, maintaining high efficiency of the extraction process, high recovery values and low values of quantification (LOQ) and detection (LOD) limits. These requirements are fulfilled by coacervative extraction (CAE) technique. In this review, theoretical aspects of the coacervation process are presented along with environmental and bioanalytical applications of this technique, its advantages, limitations and competitiveness with other techniques. Due to its simplicity and rapidity, CAE is an excellent alternative for currently practiced procedures of sample preparation for the analysis of organic compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Nuclear techniques for trace element analysis. PIXE and its applications to biomedical samples

    International Nuclear Information System (INIS)

    Cata-Danil, I.; Moro, R.; Gialanella, G.

    1996-01-01

    Problems in understanding the role of trace elements in the functioning of life processes are discussed. A brief review of the state of the PIXE technique is given. Principles and recent advances in beam systems, instrumentation and sample handling are covered. A rather comprehensive list of references regarding varies methodological aspects and biomedical applications is given. Some applications are discussed. In particular, preliminary results of an investigation regarding pediatric obesity are presented. (author) 5 tabs., 21 refs

  6. A simple technique for measuring the superconducting critical temperature of small (>= 10 μg) samples

    International Nuclear Information System (INIS)

    Pereira, R.F.R.; Meyer, E.; Silveira, M.F. da.

    1983-01-01

    A simple technique for measuring the superconducting critical temperature of small (>=10μg) samples is described. The apparatus is built in the form of a probe, which can be introduced directly into a liquid He storage dewar and permits the determination of the critical temperature, with an imprecision of +- 0.05 K above 4.2 K, in about 10 minutes. (Author) [pt

  7. Multi-element analysis of lubricant oil by WDXRF technique using thin-film sample preparation

    International Nuclear Information System (INIS)

    Scapin, M. A.; Salvador, V. L. R.; Lopes, C. D.; Sato, I. M.

    2006-01-01

    The quantitative analysis of the chemical elements in matrices like oils or gels represents a challenge for the analytical chemists. The classics methods or instrumental techniques such as atomic absorption spectrometry (AAS) and plasma optical emission spectrometry (ICP-OES) need chemical treatments, mainly sample dissolution and degradation processes. X-ray fluorescence technique allows a direct and multi-element analysis without previous sample treatments. In this work, a sensible method for the determination of elements Mg, Al, Si, P, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mo, Ag, Sn, Ba and Pb in lubricating oil is presented. The x-ray fluorescence (WDXRF) technique using linear regression method and thin film sample preparation was used. The validation of the methodology (repeatability and accuracy) was obtained by the analysis of the standard reference materials SRM Alpha AESAR lot 703527D, applying the Chauvenet, Cochrane, ANOVA and Z-score statistical tests. The method presents a relative standard deviation lower than 10% for all the elements, except for Pb determination (RSD Pb 15%). The Z-score values for all the elements were in the range -2 < Z < 2, indicating a very good accuracy.(Full text)

  8. Differentiating between endocervical glandular neoplasia and high grade squamous intraepithelial lesions in endocervical crypts: cytological features in ThinPrep and SurePath cervical cytology samples.

    Science.gov (United States)

    Thiryayi, Sakinah A; Marshall, Janet; Rana, Durgesh N

    2009-05-01

    A recent audit at our institution revealed a higher number of cases diagnosed as endocervical glandular neoplasia on ThinPrep (TP) cervical cytology samples (9 cases) as opposed to SurePath (SP) (1 case), which on histology showed only high-grade cervical intraepithelial neoplasia (CIN) with endocervical crypt involvement (CI). We attempted to ascertain the reasons for this finding by reviewing the available slides of these cases, as well as slides of cases diagnosed as glandular neoplasia on cytology and histology; cases diagnosed as high-grade squamous intraepithelial lesions (HSIL) on cytology which had CIN with CI on histology and cases with mixed glandular and squamous abnormalities diagnosed both cytologically and histologically. Single neoplastic glandular cells and short pseudostratified strips were more prevalent in SP than TP with the cell clusters in glandular neoplasia 3-4 cells thick, in contrast to the dense crowded centre of cell groups in HSIL with CI. The cells at the periphery of groups can be misleading. Cases with HSIL and glandular neoplasia have a combination of the features of each entity in isolation. The diagnosis of glandular neoplasia remains challenging and conversion from conventional to liquid based cervical cytology requires a period of learning and adaptation, which can be facilitated by local audit and review of the cytology slides in cases with a cytology-histology mismatch. (c) 2009 Wiley-Liss, Inc.

  9. Detection of equine herpesvirus in horses with idiopathic keratoconjunctivitis and comparison of three sampling techniques.

    Science.gov (United States)

    Hollingsworth, Steven R; Pusterla, Nicola; Kass, Philip H; Good, Kathryn L; Brault, Stephanie A; Maggs, David J

    2015-09-01

    To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR). Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease. Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judged to be more severely affected. Samples were tested with qPCR for EHV-1, EHV-2, EHV-4, and EHV-5 DNA. Quantity of EHV DNA and viral replicative activity were compared between the two populations and among the different sampling techniques; relative sensitivities of the sampling techniques were determined. Prevalence of EHV DNA as assessed by qPCR did not differ significantly between control horses and those with idiopathic keratoconjunctivitis. Sampling by conjunctival swab was more likely to yield viral DNA as assessed by qPCR than was conjunctival biopsy. EHV-1 and EHV-4 DNA were not detected in either normal or IKC-affected horses; EHV-2 DNA was detected in two of 12 affected horses but not in normal horses. EHV-5 DNA was commonly found in ophthalmically normal horses and horses with idiopathic keratoconjunctivitis. Because EHV-5 DNA was commonly found in control horses and in horses with idiopathic keratoconjunctivitis, qPCR was not useful for the etiological diagnosis of equine keratoconjunctivitis. Conjunctival swabs were significantly better at obtaining viral DNA samples than conjunctival biopsy in horses in which EHV-5 DNA was found. © 2015 American College of Veterinary Ophthalmologists.

  10. Path Dependence

    DEFF Research Database (Denmark)

    Madsen, Mogens Ove

    Begrebet Path Dependence blev oprindelig udviklet inden for New Institutionel Economics af bl.a. David, Arthur og North. Begrebet har spredt sig vidt i samfundsvidenskaberne og undergået en udvikling. Dette paper propagerer for at der er sket så en så omfattende udvikling af begrebet, at man nu kan...... tale om 1. og 2. generation af Path Dependence begrebet. Den nyeste udvikling af begrebet har relevans for metodologi-diskusionerne i relation til Keynes...

  11. Multiple sensitive estimation and optimal sample size allocation in the item sum technique.

    Science.gov (United States)

    Perri, Pier Francesco; Rueda García, María Del Mar; Cobo Rodríguez, Beatriz

    2018-01-01

    For surveys of sensitive issues in life sciences, statistical procedures can be used to reduce nonresponse and social desirability response bias. Both of these phenomena provoke nonsampling errors that are difficult to deal with and can seriously flaw the validity of the analyses. The item sum technique (IST) is a very recent indirect questioning method derived from the item count technique that seeks to procure more reliable responses on quantitative items than direct questioning while preserving respondents' anonymity. This article addresses two important questions concerning the IST: (i) its implementation when two or more sensitive variables are investigated and efficient estimates of their unknown population means are required; (ii) the determination of the optimal sample size to achieve minimum variance estimates. These aspects are of great relevance for survey practitioners engaged in sensitive research and, to the best of our knowledge, were not studied so far. In this article, theoretical results for multiple estimation and optimal allocation are obtained under a generic sampling design and then particularized to simple random sampling and stratified sampling designs. Theoretical considerations are integrated with a number of simulation studies based on data from two real surveys and conducted to ascertain the efficiency gain derived from optimal allocation in different situations. One of the surveys concerns cannabis consumption among university students. Our findings highlight some methodological advances that can be obtained in life sciences IST surveys when optimal allocation is achieved. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Evaluation of primary immunization coverage of infants under universal immunization programme in an urban area of Bangalore city using cluster sampling and lot quality assurance sampling techniques

    Directory of Open Access Journals (Sweden)

    Punith K

    2008-01-01

    Full Text Available Research Question: Is LQAS technique better than cluster sampling technique in terms of resources to evaluate the immunization coverage in an urban area? Objective: To assess and compare the lot quality assurance sampling against cluster sampling in the evaluation of primary immunization coverage. Study Design: Population-based cross-sectional study. Study Setting: Areas under Mathikere Urban Health Center. Study Subjects: Children aged 12 months to 23 months. Sample Size: 220 in cluster sampling, 76 in lot quality assurance sampling. Statistical Analysis: Percentages and Proportions, Chi square Test. Results: (1 Using cluster sampling, the percentage of completely immunized, partially immunized and unimmunized children were 84.09%, 14.09% and 1.82%, respectively. With lot quality assurance sampling, it was 92.11%, 6.58% and 1.31%, respectively. (2 Immunization coverage levels as evaluated by cluster sampling technique were not statistically different from the coverage value as obtained by lot quality assurance sampling techniques. Considering the time and resources required, it was found that lot quality assurance sampling is a better technique in evaluating the primary immunization coverage in urban area.

  13. Improved sample preparation and counting techniques for enhanced tritium measurement sensitivity

    Science.gov (United States)

    Moran, J.; Aalseth, C.; Bailey, V. L.; Mace, E. K.; Overman, C.; Seifert, A.; Wilcox Freeburg, E. D.

    2015-12-01

    Tritium (T) measurements offer insight to a wealth of environmental applications including hydrologic tracking, discerning ocean circulation patterns, and aging ice formations. However, the relatively short half-life of T (12.3 years) limits its effective age dating range. Compounding this limitation is the decrease in atmospheric T content by over two orders of magnitude (from 1000-2000 TU in 1962 to testing in the 1960's. We are developing sample preparation methods coupled to direct counting of T via ultra-low background proportional counters which, when combined, offer improved T measurement sensitivity (~4.5 mmoles of H2 equivalent) and will help expand the application of T age dating to smaller sample sizes linked to persistent environmental questions despite the limitations above. For instance, this approach can be used to T date ~ 2.2 mmoles of CH4 collected from sample-limited systems including microbial communities, soils, or subsurface aquifers and can be combined with radiocarbon dating to distinguish the methane's formation age from C age in a system. This approach can also expand investigations into soil organic C where the improved sensitivity will permit resolution of soil C into more descriptive fractions and provide direct assessments of the stability of specific classes of organic matter in soils environments. We are employing a multiple step sample preparation system whereby organic samples are first combusted with resulting CO2 and H2O being used as a feedstock to synthesize CH4. This CH4 is mixed with Ar and loaded directly into an ultra-low background proportional counter for measurement of T β decay in a shallow underground laboratory. Analysis of water samples requires only the addition of geologic CO2 feedstock with the sample for methane synthesis. The chemical nature of the preparation techniques enable high sample throughput with only the final measurement requiring T decay with total sample analysis time ranging from 2 -5 weeks

  14. Sample preparation for large-scale bioanalytical studies based on liquid chromatographic techniques.

    Science.gov (United States)

    Medvedovici, Andrei; Bacalum, Elena; David, Victor

    2018-01-01

    Quality of the analytical data obtained for large-scale and long term bioanalytical studies based on liquid chromatography depends on a number of experimental factors including the choice of sample preparation method. This review discusses this tedious part of bioanalytical studies, applied to large-scale samples and using liquid chromatography coupled with different detector types as core analytical technique. The main sample preparation methods included in this paper are protein precipitation, liquid-liquid extraction, solid-phase extraction, derivatization and their versions. They are discussed by analytical performances, fields of applications, advantages and disadvantages. The cited literature covers mainly the analytical achievements during the last decade, although several previous papers became more valuable in time and they are included in this review. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Texture investigation in aluminium and iron - silicon samples by neutron diffraction technique

    International Nuclear Information System (INIS)

    Pugliese, R.; Yamasaki, J.M.

    1988-09-01

    By means of the neutron diffraction technique the texture of 5% and 98% rolled-aluminium and of iron-silicon steel used in the core of electric transformers, have been determined. The measurements were performed by using a neutron diffractometer installed at the IEA-R1 Nuclear Research Reactor, in the Beam-Hole n 0 . 6. To avoid corrections such as neutron absorption and sample luminosity the geometric form of the samples were approximated to spheric or octagonal prism, and its dimensions do not exceed that of the neutron beam. The texture of the samples were analysed with the help of a computer programme that analyses the intensity of the diffracted neutron beam and plot the pole figures. (author) [pt

  16. Application of Synthetic Storm Technique for Diurnal and Seasonal Variation of Slant Path Ka-Band Rain Attenuation Time Series over a Subtropical Location in South Africa

    Directory of Open Access Journals (Sweden)

    J. S. Ojo

    2015-01-01

    Full Text Available As technology advances and more demands are on satellite services, rain-induced attenuation still creates one of the most damaging effects of the atmosphere on the quality of radio communication signals, especially those operating above 10 GHz. System designers therefore require statistical information on rain-induced attenuation over the coverage area in order to determine the appropriate transmitter and receiver characteristics to be adopted. This paper presents results on the time-varying rain characterization and diurnal variation of slant path rain attenuation in the Ka-band frequency simulated with synthetic storm techniques over a subtropical location in South Africa using 10-year rain rate time-series data. The analysis is based on the CDF of one-minute rain rate; time-series seasonal variation of rain rate observed over four time intervals: 00:00–06:00, 06:00–12:00, 12:00–18:00, and 18:00–24:00; diurnal fades margin; and diurnal variation of rain attenuation. Comparison was also made between the synthesized values and measured attenuation data. The predicted statistics are in good agreement with those obtained from the propagation beacon measurement in the area. The overall results will be needed for an acceptable planning that can effectively reduce the fade margin to a very low value for an optimum data communication over this area.

  17. Determination of trace elements in plant samples using XRF, PIXE and ICP-OES techniques

    International Nuclear Information System (INIS)

    Ahmed, Hassan Elzain Hassan

    2014-07-01

    The purpose of this study is to determine trace element concentration (Ca, Cu, Cr, K,Fe, Mn,Sr, and Za) in some sudanese wild plants namely, Ziziphus Abyssinica and Grewia Tenax. X-ray fluorescence ( X RF), particle-induced x-ray emission ( PIXE) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) techniques were used for element determination. A series of plants standard references materials were used to check the reliability of the different employed techniques as well as to estimate possible factors for correcting the concentration of some elements that deviated significantly from their actual concentration. The results showed that, X RF, PIXE and ICP-OES are equally competitive methods for measuring Ca,K, Fe, Sr and Zn elements. Unlikely to ICP-OES seems to be superior techniques tend to be appropriate methods for Cu determination in plant samples however, for Mn element PIXE and ICP-OES are advisable techniques for measuring this element rather than X RF method. On the other hand, ICP-OES seems to be the superior techniques over PIXE and X RF methods for Cr and Ni determination in plant samples. The effect of geographical location on trace elements concentration in plants has been examined through determination of element in different species of Grewia Tenax than collected from different location. Most of measured elements showed similarity indicating there is no significant impact of locations on the difference of element contents. In addition, two plants with different genetic families namely, Ziziphus Spina Christi and Ziziphus Abyssinica were collected from the same location and screened for their trace element content. It was found that there were no difference between the two plants for Ca, K, Cu, Fe, and Sr element. However, significant variations were observed for Mn and Zn concentrations implying the possibility of using of those two elements for plant taxonomy purposes.(Author)

  18. Neutron activation analysis technique and X-ray fluorescence in bovine liver sample

    International Nuclear Information System (INIS)

    Maihara, V.A.; Favaro, D.I.T.; Vasconcellos, M.B.A.; Sato, I.M.; Salvador, V.L.

    2002-01-01

    Many analytical techniques have been used in food and diet analysis in order to determine a great number of nutritional elements, ranging from percentage to ng g -1 , with high sensitivity and accuracy. Instrumental Neutron activation Analysis (INAA) has been employed to certificate many trace elements in biological reference materials. More recently, the X-Ray Fluorescence (FRX-WD) has been also used to determine some essential elements in food samples. The INAA has been applied in nutrition studies in our laboratory at IPEN since the 80 s. For the development of analytical methodologies the use of the reference materials with the same characteristics of the sample analyzed is essential. Several Brazilian laboratories do not have conditions to use these materials due their high cost.In this paper preliminary results of commercial bovine liver sample analyses obtained by INAA and WD-XRF methods are presented. This sample was prepared to be a Brazilian candidate of reference material for a group of laboratories participating in a research project sponsored by FAPESP. The concentrations of some elements like Cl, K, Na, P, S and trace elements Br, Ca, Co, Cu, Fe, Mg, Mn, Mo, Rb, Se and Zn were determined by INAA and WD-XFR. For validation methodology of both techniques, NIST SRM 1577b Bovine Liver reference material was analyzed and the detection limits were calculated. The concentrations of elements determined by both analytical techniques were compared by using the Student's t-test and for Cl, Cu, Fe, K, Mg, Na, Rn and Zn the results do show no statistical difference for 95% significance level. (author)

  19. Evaluation of primary immunization coverage of infants under universal immunization programme in an urban area of bangalore city using cluster sampling and lot quality assurance sampling techniques.

    Science.gov (United States)

    K, Punith; K, Lalitha; G, Suman; Bs, Pradeep; Kumar K, Jayanth

    2008-07-01

    Is LQAS technique better than cluster sampling technique in terms of resources to evaluate the immunization coverage in an urban area? To assess and compare the lot quality assurance sampling against cluster sampling in the evaluation of primary immunization coverage. Population-based cross-sectional study. Areas under Mathikere Urban Health Center. Children aged 12 months to 23 months. 220 in cluster sampling, 76 in lot quality assurance sampling. Percentages and Proportions, Chi square Test. (1) Using cluster sampling, the percentage of completely immunized, partially immunized and unimmunized children were 84.09%, 14.09% and 1.82%, respectively. With lot quality assurance sampling, it was 92.11%, 6.58% and 1.31%, respectively. (2) Immunization coverage levels as evaluated by cluster sampling technique were not statistically different from the coverage value as obtained by lot quality assurance sampling techniques. Considering the time and resources required, it was found that lot quality assurance sampling is a better technique in evaluating the primary immunization coverage in urban area.

  20. Use of a multigrid technique to study effects of limited sampling of heterogeneity on transport prediction

    International Nuclear Information System (INIS)

    Cole, C.R.; Foote, H.P.

    1987-02-01

    Reliable ground water transport prediction requires accurate spatial and temporal characterization of a hydrogeologic system. However, cost constraints and the desire to maintain site integrity by minimizing drilling can restrict the amount of spatial sampling that can be obtained to resolve the flow parameter variability associated with heterogeneities. This study quantifies the errors in subsurface transport predictions resulting from incomplete characterization of hydraulic conductivity heterogeneity. A multigrid technique was used to simulate two-dimensional flow velocity fields with high resolution. To obtain these velocity fields, the finite difference code MGRID, which implements a multigrid solution technique, was applied to compute stream functions on a 256-by-256 grid for a variety of hypothetical systems having detailed distributions of hydraulic conductivity. Spatial variability in hydraulic conductivity distributions was characterized by the components in the spectrum of spatial frequencies. A low-pass spatial filtering technique was applied to the base case hydraulic conductivity distribution to produce a data set with lower spatial frequency content. Arrival time curves were then calculated for filtered hydraulic conductivity distribution and compared to base case results to judge the relative importance of the higher spatial frequency components. Results indicate a progression from multimode to single-mode arrival time curves as the number and extent of distinct flow pathways are reduced by low-pass filtering. This relationship between transport predictions and spatial frequencies was used to judge the consequences of sampling the hydraulic conductivity with reduced spatial resolution. 22 refs., 17 figs

  1. A cost-effective technique for integrating personal radiation dose assessment with personal gravimetric sampling

    International Nuclear Information System (INIS)

    Strydom, R.; Rolle, R.; Van der Linde, A.

    1992-01-01

    During recent years there has been an increasing awareness internationally of radiation levels in the mining and milling of radioactive ores, including those from non-uranium mines. A major aspect of radiation control is concerned with the measurement of radiation levels and the assessment of radiation doses incurred by individual workers. Current techniques available internationally for personnel monitoring of radiation exposures are expensive and there is a particular need to reduce the cost of personal radiation monitoring in South African gold mines because of the large labour force employed. In this regard the obvious benefits of integrating personal radiation monitoring with existing personal monitoring systems already in place in South African gold mines should be exploited. A system which can be utilized for this purpose is personal gravimetric sampling. A new cost-effective technique for personal radiation monitoring, which can be fully integrated with the personal gravimetric sampling strategy being implemented on mines, has been developed in South Africa. The basic principles of this technique and its potential in South African mines are described. 9 refs., 7 figs

  2. Micro-CT evaluation of several glide path techniques and ProTaper Next shaping outcomes in maxillary first molar curved canals.

    Science.gov (United States)

    Alovisi, M; Cemenasco, A; Mancini, L; Paolino, D; Scotti, N; Bianchi, C C; Pasqualini, D

    2017-04-01

    To evaluate the ability of ProGlider instruments, PathFiles and K-files to maintain canal anatomy during glide path preparation using X-ray computed micro-tomography (micro-CT). Forty-five extracted maxillary first permanent molars were selected. Mesio-buccal canals were randomly assigned (n = 15) to manual K-file, PathFile or ProGlider groups for glide path preparation. Irrigation was achieved with 5% NaOCl and 10% EDTA. After glide path preparation, each canal was shaped with ProTaper Next X1 and X2 to working length. Specimens were scanned (isotropic voxel size 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Canal volume, surface area, centroid shift, canal geometry variation through ratio of diameter ratios and ratio of cross-sectional areas were assessed in the apical and coronal levels and at the point of maximum canal curvature. One-way factorial anovas were used to evaluate the significance of instrument in the various canal regions. Post-glide path analysis revealed that instrument factor was significant at the apical level for both the ratio of diameter ratios and the ratio of cross-sectional areas (P flare the root canal compared with K-file and PathFile. PathFile and ProGlider demonstrated a significantly lower centroid shift compared with K-file at the apical level (P = 0.023). Post-shaping analysis demonstrated a more centred preparation of ProGlider, compared with PathFile and K-files, with no significant differences for other parameters. Use of ProGlider instruments led to less canal transportation than PathFiles and K-files. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  3. An Electromagnetic Gauge Technique for Measuring Shocked Particle Velocity in Electrically Conductive Samples

    Science.gov (United States)

    Cheng, David; Yoshinaka, Akio

    2014-11-01

    Electromagnetic velocity (EMV) gauges are a class of film gauges which permit the direct in-situ measurement of shocked material flow velocity. The active sensing element, typically a metallic foil, requires exposure to a known external magnetic field in order to produce motional electromotive force (emf). Due to signal distortion caused by mutual inductance between sample and EMV gauge, this technique is typically limited to shock waves in non-conductive materials. In conductive samples, motional emf generated in the EMV gauge has to be extracted from the measured signal which results from the combined effects of both motional emf and voltage changes from induced currents. An electromagnetic technique is presented which analytically models the dynamics of induced current between a copper disk moving as a rigid body with constant 1D translational velocity toward an EMV gauge, where both disk and gauge are exposed to a uniform external static magnetic field. The disk is modelled as a magnetic dipole loop where its Foucault current is evaluated from the characteristics of the fields, whereas the EMV gauge is modelled as a circuit loop immersed in the field of the magnetic dipole loop, the intensity of which is calculated as a function of space and, implicitly, time. Equations of mutual induction are derived and the current induced in the EMV gauge loop is solved, allowing discrimination of the motional emf. Numerical analysis is provided for the step response of the induced EMV gauge current with respect to the Foucault current in the moving copper sample.

  4. Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

    Science.gov (United States)

    Yan, Wei; Yang, Yanlong; Tan, Yu; Chen, Xun; Li, Yang; Qu, Junle; Ye, Tong

    2018-01-01

    Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens’ optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples. PMID:29400356

  5. Localisation and identification of radioactive particles in solid samples by means of a nuclear track technique

    International Nuclear Information System (INIS)

    Boehnke, Antje; Treutler, Hanns-Christian; Freyer, Klaus; Schubert, Michael; Holger Weiss

    2005-01-01

    This study is aimed to develop a generally applicable methodology of investigation that can be used for the localisation of single alpha-active particles in solid samples, such as industrial dust or natural soils, sediments and rocks by autoradiography using solid-state nuclear track detectors. The developed technique allows the detection of local enrichments of alpha-emitters in any solid material. The results of such an investigation are of interest from technical, biological and environmental points of view. The idea behind the methodology is to locate the position of alpha-active spots in a sample by attaching the track detector to the sample in a defined manner, thoroughly described in the paper. The located alpha-active particles are subsequently analysed by an electron microscope and an electron microprobe. An example of the application of this methodology is also given. An ultra-fine -grained ore-processing residue, which causes serious environmental pollution in the respective mining district and thus limits possible land use and affects quality of life in the area, was examined using the described technique. The investigation revealed considerable amounts of alpha-active particles in this material

  6. Review of cleaning techniques and their effects on the chemical composition of foliar samples

    Energy Technology Data Exchange (ETDEWEB)

    Rossini Oliva, S.; Raitio, H.

    2003-07-01

    Chemical foliar analysis is a tool widely used to study tree nutrition and to monitor the impact and extent of air pollutants. This paper reviews a number of cleaning methods, and the effects of cleaning on foliar chemistry. Cleaning may include mechanical techniques such as the use of dry or moistened tissues, shaking, blowing, and brushing, or use various washing techniques with water or other solvents. Owing to the diversity of plant species, tissue differences, etc., there is no standard procedure for all kinds of samples. Analysis of uncleaned leaves is considered a good method for assessing the degree of air contamination because it provides an estimate of the element content of the deposits on leaf surfaces or when the analysis is aimed at the investigation of transfer of elements along the food chain. Sample cleaning is recommended in order (1) to investigate the transfer rate of chemical elements from soil to plants, (2) to qualify the washoff of dry deposition from foliage and (3) to separate superficially absorbed and biomass-incorporated elements. Since there is not a standard cleaning procedure for all kinds of samples and aims, it is advised to conduct a pilot study in order to be able to establish a cleaning procedure to provide reliable foliar data. (orig.)

  7. Convergence and Efficiency of Adaptive Importance Sampling Techniques with Partial Biasing

    Science.gov (United States)

    Fort, G.; Jourdain, B.; Lelièvre, T.; Stoltz, G.

    2018-04-01

    We propose a new Monte Carlo method to efficiently sample a multimodal distribution (known up to a normalization constant). We consider a generalization of the discrete-time Self Healing Umbrella Sampling method, which can also be seen as a generalization of well-tempered metadynamics. The dynamics is based on an adaptive importance technique. The importance function relies on the weights (namely the relative probabilities) of disjoint sets which form a partition of the space. These weights are unknown but are learnt on the fly yielding an adaptive algorithm. In the context of computational statistical physics, the logarithm of these weights is, up to an additive constant, the free-energy, and the discrete valued function defining the partition is called the collective variable. The algorithm falls into the general class of Wang-Landau type methods, and is a generalization of the original Self Healing Umbrella Sampling method in two ways: (i) the updating strategy leads to a larger penalization strength of already visited sets in order to escape more quickly from metastable states, and (ii) the target distribution is biased using only a fraction of the free-energy, in order to increase the effective sample size and reduce the variance of importance sampling estimators. We prove the convergence of the algorithm and analyze numerically its efficiency on a toy example.

  8. Low-mass molecular dynamics simulation: A simple and generic technique to enhance configurational sampling

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yuan-Ping, E-mail: pang@mayo.edu

    2014-09-26

    Highlights: • Reducing atomic masses by 10-fold vastly improves sampling in MD simulations. • CLN025 folded in 4 of 10 × 0.5-μs MD simulations when masses were reduced by 10-fold. • CLN025 folded as early as 96.2 ns in 1 of the 4 simulations that captured folding. • CLN025 did not fold in 10 × 0.5-μs MD simulations when standard masses were used. • Low-mass MD simulation is a simple and generic sampling enhancement technique. - Abstract: CLN025 is one of the smallest fast-folding proteins. Until now it has not been reported that CLN025 can autonomously fold to its native conformation in a classical, all-atom, and isothermal–isobaric molecular dynamics (MD) simulation. This article reports the autonomous and repeated folding of CLN025 from a fully extended backbone conformation to its native conformation in explicit solvent in multiple 500-ns MD simulations at 277 K and 1 atm with the first folding event occurring as early as 66.1 ns. These simulations were accomplished by using AMBER forcefield derivatives with atomic masses reduced by 10-fold on Apple Mac Pros. By contrast, no folding event was observed when the simulations were repeated using the original AMBER forcefields of FF12SB and FF14SB. The results demonstrate that low-mass MD simulation is a simple and generic technique to enhance configurational sampling. This technique may propel autonomous folding of a wide range of miniature proteins in classical, all-atom, and isothermal–isobaric MD simulations performed on commodity computers—an important step forward in quantitative biology.

  9. GRAVTool, Advances on the Package to Compute Geoid Model path by the Remove-Compute-Restore Technique, Following Helmert's Condensation Method

    Science.gov (United States)

    Marotta, G. S.

    2017-12-01

    Currently, there are several methods to determine geoid models. They can be based on terrestrial gravity data, geopotential coefficients, astrogeodetic data or a combination of them. Among the techniques to compute a precise geoid model, the Remove Compute Restore (RCR) has been widely applied. It considers short, medium and long wavelengths derived from altitude data provided by Digital Terrain Models (DTM), terrestrial gravity data and Global Geopotential Model (GGM), respectively. In order to apply this technique, it is necessary to create procedures that compute gravity anomalies and geoid models, by the integration of different wavelengths, and adjust these models to one local vertical datum. This research presents the advances on the package called GRAVTool to compute geoid models path by the RCR, following Helmert's condensation method, and its application in a study area. The studied area comprehends the federal district of Brazil, with 6000 km², wavy relief, heights varying from 600 m to 1340 m, located between the coordinates 48.25ºW, 15.45ºS and 47.33ºW, 16.06ºS. The results of the numerical example on the studied area show a geoid model computed by the GRAVTool package, after analysis of the density, DTM and GGM values, more adequate to the reference values used on the study area. The accuracy of the computed model (σ = ± 0.058 m, RMS = 0.067 m, maximum = 0.124 m and minimum = -0.155 m), using density value of 2.702 g/cm³ ±0.024 g/cm³, DTM SRTM Void Filled 3 arc-second and GGM EIGEN-6C4 up to degree and order 250, matches the uncertainty (σ =± 0.073) of 26 points randomly spaced where the geoid was computed by geometrical leveling technique supported by positioning GNSS. The results were also better than those achieved by Brazilian official regional geoid model (σ = ± 0.076 m, RMS = 0.098 m, maximum = 0.320 m and minimum = -0.061 m).

  10. MUP, CEC-DES, STRADE. Codes for uncertainty propagation, experimental design and stratified random sampling techniques

    International Nuclear Information System (INIS)

    Amendola, A.; Astolfi, M.; Lisanti, B.

    1983-01-01

    The report describes the how-to-use of the codes: MUP (Monte Carlo Uncertainty Propagation) for uncertainty analysis by Monte Carlo simulation, including correlation analysis, extreme value identification and study of selected ranges of the variable space; CEC-DES (Central Composite Design) for building experimental matrices according to the requirements of Central Composite and Factorial Experimental Designs; and, STRADE (Stratified Random Design) for experimental designs based on the Latin Hypercube Sampling Techniques. Application fields, of the codes are probabilistic risk assessment, experimental design, sensitivity analysis and system identification problems

  11. Non-destructive high-resolution thermal imaging techniques to evaluate wildlife and delicate biological samples

    International Nuclear Information System (INIS)

    Lavers, C; Franklin, P; Franklin, P; Plowman, A; Sayers, G; Bol, J; Shepard, D; Fields, D

    2009-01-01

    Thermal imaging cameras now allows routine monitoring of dangerous yet endangered wildlife in captivity. This study looks at the potential applications of radiometrically calibrated thermal data to wildlife, as well as providing parameters for future materials applications. We present a non-destructive active testing technique suitable for enhancing imagery contrast of thin or delicate biological specimens yielding improved thermal contrast at room temperature, for analysis of sample thermal properties. A broad spectrum of animals is studied with different textured surfaces, reflective and emissive properties in the infra red part of the electromagnetic spectrum. Some surface features offer biomimetic materials design opportunities.

  12. A novel in-situ sampling and VFA sensor technique for anaerobic systems

    DEFF Research Database (Denmark)

    Pind, Peter Frode; Angelidaki, Irini; Ahring, Birgitte Kiær

    2002-01-01

    A key information for understanding and controlling the anaerobic biogas process is the concentration of Volatile Fatty Acids (VFA). However, access to this information has so far been limited to off-line measurements by manual time and labour consuming methods. We have developed a new technique ...... than 1000 samples on both a fullscale biogas plant and lab-scale reactors. The measuring range covers specific measurements of acetate, propionate, iso-/n-butyrate and iso-/n-valerate from 0.1 to 50 mM (6–3,000 mg)....

  13. Investigation of an egyptian phosphate ore sample by neutron activation analysis technique

    International Nuclear Information System (INIS)

    Eissa, E.A.; Aly, R.A.; Rofail, N.B.; Hassan, A.M.

    1995-01-01

    A domestic phosphate ore sample has been analysed by means of prompt and delayed gamma-ray spectrometry following the activation by thermal neutron capture technique. The rabbit pneumatic transfer system (RPTS), long irradiation facility and two Pu/Be (2,5 Ci each) neutron sources set-Pu for prompt (n,gamma) were applied. The high purity germanium (HPGe) gamma-ray spectrometer with a personal computer analyzer (PCA) system were used for spectrum measurements. Programmes on the VAX computer were utilized for estimating the elemental concentrations of 22 out of 36 elements identified in this work. 2 tabs

  14. Non-destructive high-resolution thermal imaging techniques to evaluate wildlife and delicate biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Lavers, C; Franklin, P; Franklin, P; Plowman, A; Sayers, G; Bol, J; Shepard, D; Fields, D, E-mail: brnc-radarcomms1@nrta.mod.u [Sensors Team, Plymouth University at Britannia Royal Naval College, Dartmouth, Devon (United Kingdom) and Paignton Zoological Park, Paignton, Devon (United Kingdom); Thermal Wave Imaging, Inc., 845 Livernoise St, Ferndale, MI (United States); Buckfast Butterfly and Otter Sanctuary, Buckfast, Devon (United Kingdom)

    2009-07-01

    Thermal imaging cameras now allows routine monitoring of dangerous yet endangered wildlife in captivity. This study looks at the potential applications of radiometrically calibrated thermal data to wildlife, as well as providing parameters for future materials applications. We present a non-destructive active testing technique suitable for enhancing imagery contrast of thin or delicate biological specimens yielding improved thermal contrast at room temperature, for analysis of sample thermal properties. A broad spectrum of animals is studied with different textured surfaces, reflective and emissive properties in the infra red part of the electromagnetic spectrum. Some surface features offer biomimetic materials design opportunities.

  15. Analysis of boron utilization in sample preparation for microorganisms detection by neutron radiography technique

    International Nuclear Information System (INIS)

    Wacha, Reinaldo; Crispim, Verginia R.

    2000-01-01

    The neutron radiography technique applied to the microorganisms detection is the study of a new and faster alternative for diagnosis of infectious means. This work presents the parameters and the effects involved in the use of the boron as a conversion agent, that convert neutrons in a particles, capable ones of generating latent tracks in a solid state nuclear tracks detector, CR-39. The collected samples are doped with the boron by the incubation method, propitiating an interaction microorganisms/boron, that will guarantee the identification of the images of those microorganisms, through your morphology. (author)

  16. A rapid method of radium-226 analysis in water samples using an alpha spectroscopic technique

    International Nuclear Information System (INIS)

    Lim, T.P.

    1981-01-01

    A fast, reliable and accurate method for radium-226 determination in environmental water samples has been devised, using an alpha spectroscopic technique. The correlation between barium-133 and radium-226 in the barium-radium sulphate precipitation mechanism was studied and in the limited experimental recovery range, the coefficient of correlation was r = 0.986. A self-absorption study for various barium carrier concentrations was also undertaken to obtain the least broadening of alpha energy line widths. An optimum value of 0.3 mg barium carrier was obtained for chemical recovery in the range of 85 percent. (auth)

  17. TRAN-STAT: statistics for environmental studies, Number 22. Comparison of soil-sampling techniques for plutonium at Rocky Flats

    International Nuclear Information System (INIS)

    Gilbert, R.O.; Bernhardt, D.E.; Hahn, P.B.

    1983-01-01

    A summary of a field soil sampling study conducted around the Rocky Flats Colorado plant in May 1977 is preseted. Several different soil sampling techniques that had been used in the area were applied at four different sites. One objective was to comparethe average 239 - 240 Pu concentration values obtained by the various soil sampling techniques used. There was also interest in determining whether there are differences in the reproducibility of the various techniques and how the techniques compared with the proposed EPA technique of sampling to 1 cm depth. Statistically significant differences in average concentrations between the techniques were found. The differences could be largely related to the differences in sampling depth-the primary physical variable between the techniques. The reproducibility of the techniques was evaluated by comparing coefficients of variation. Differences between coefficients of variation were not statistically significant. Average (median) coefficients ranged from 21 to 42 percent for the five sampling techniques. A laboratory study indicated that various sample treatment and particle sizing techniques could increase the concentration of plutonium in the less than 10 micrometer size fraction by up to a factor of about 4 compared to the 2 mm size fraction

  18. Three Proposed Compendia for Genesis Solar Wind Samples: Science Results, Collector Materials Characterization and Cleaning Techniques

    Science.gov (United States)

    Allton, J. H.; Calaway, M. J.; Nyquist, L. E.; Jurewicz, A. J. G.; Burnett, D. S.

    2018-01-01

    Final Paper and not the abstract is attached. Introduction: Planetary material and cosmochemistry research using Genesis solar wind samples (including the development and implementation of cleaning and analytical techniques) has matured sufficiently that compilations on several topics, if made publically accessible, would be beneficial for researchers and reviewers. We propose here three compendia based on content, organization and source of documents (e.g. published peer-reviewed, published, internal memos, archives). For planning purposes, suggestions are solicited from potential users of Genesis solar wind samples for the type of science content and/or organizational style that would be most useful to them. These compendia are proposed as living documents, periodically updated. Similar to the existing compendia described below, the curation compendia are like library or archival finding aids, they are guides to published or archival documents and should not be cited as primary sources.

  19. Path Creation

    DEFF Research Database (Denmark)

    Karnøe, Peter; Garud, Raghu

    2012-01-01

    This paper employs path creation as a lens to follow the emergence of the Danish wind turbine cluster. Supplier competencies, regulations, user preferences and a market for wind power did not pre-exist; all had to emerge in a tranformative manner involving multiple actors and artefacts. Competenc......This paper employs path creation as a lens to follow the emergence of the Danish wind turbine cluster. Supplier competencies, regulations, user preferences and a market for wind power did not pre-exist; all had to emerge in a tranformative manner involving multiple actors and artefacts....... Competencies emerged through processes and mechanisms such as co-creation that implicated multiple learning processes. The process was not an orderly linear one as emergent contingencies influenced the learning processes. An implication is that public policy to catalyse clusters cannot be based...

  20. Refinement of NMR structures using implicit solvent and advanced sampling techniques.

    Science.gov (United States)

    Chen, Jianhan; Im, Wonpil; Brooks, Charles L

    2004-12-15

    NMR biomolecular structure calculations exploit simulated annealing methods for conformational sampling and require a relatively high level of redundancy in the experimental restraints to determine quality three-dimensional structures. Recent advances in generalized Born (GB) implicit solvent models should make it possible to combine information from both experimental measurements and accurate empirical force fields to improve the quality of NMR-derived structures. In this paper, we study the influence of implicit solvent on the refinement of protein NMR structures and identify an optimal protocol of utilizing these improved force fields. To do so, we carry out structure refinement experiments for model proteins with published NMR structures using full NMR restraints and subsets of them. We also investigate the application of advanced sampling techniques to NMR structure refinement. Similar to the observations of Xia et al. (J.Biomol. NMR 2002, 22, 317-331), we find that the impact of implicit solvent is rather small when there is a sufficient number of experimental restraints (such as in the final stage of NMR structure determination), whether implicit solvent is used throughout the calculation or only in the final refinement step. The application of advanced sampling techniques also seems to have minimal impact in this case. However, when the experimental data are limited, we demonstrate that refinement with implicit solvent can substantially improve the quality of the structures. In particular, when combined with an advanced sampling technique, the replica exchange (REX) method, near-native structures can be rapidly moved toward the native basin. The REX method provides both enhanced sampling and automatic selection of the most native-like (lowest energy) structures. An optimal protocol based on our studies first generates an ensemble of initial structures that maximally satisfy the available experimental data with conventional NMR software using a simplified

  1. Issues in the analyze of low content gold mining samples by fire assay technique

    Science.gov (United States)

    Cetean, Valentina

    2016-04-01

    The classic technique analyze of samples with low gold content - below 0.1 g/t (=100 ppb = parts per billion), either ore or gold sediments, involves the preparation of sample by fire assay extraction, followed by the chemical attack with aqua regia (hydrochloric and nitric acid) and measuring the gold content by atomic absorption spectrometry or inductively coupled mass spectrometry. The issues raised by this analysis are well known for the world laboratories, commercial or research ones. The author's knowledge regarding this method of determining the gold content, accumulated in such laboratory from Romania (with more than 40 years of experience, even if not longer available from 2014) confirms the obtaining of reliable results required a lot of attention, amount of work and the involving of an experienced fire assayer specialist. The analytical conclusion for a research laboratory is that most reliable and statistically valid results are till reached for samples with more than 100 ppb gold content; the degree of confidence below this value is lower than 90%. Usually, for samples below 50 ppb, it does not exceed 50-70 %, unless without very strictly control of each stage, that involve additional percentage of hours allocated for successive extracting tests and knowing more precisely the other compounds that appear in the sample (Cu, Sb, As, sulfur / sulphides, Te, organic matter, etc.) or impurities. The most important operation is the preparation, namely: - grinding and splitting of sample (which can cause uneven distribution of gold flakes in the double samples for analyzed); - pyro-metallurgical recovery of gold = fire assay stage, involving the more precise temperature control in furnace during all stages (fusion and cupellation) and adjusting of the fire assay flux components to produce a successful fusion depending of the sample matrix and content; - reducing the sample weight to decrease the amount of impurities that can be concentrated in the lead button

  2. Robust Adaptive Photon Tracing using Photon Path Visibility

    DEFF Research Database (Denmark)

    Hachisuka, Toshiya; Jensen, Henrik Wann

    2011-01-01

    We present a new adaptive photon tracing algorithm which can handle illumination settings that are considered difficult for photon tracing approaches such as outdoor scenes, close-ups of a small part of an illuminated region, and illumination coming through a small gap. The key contribution in our...... algorithm is the use of visibility of photon path as the importance function which ensures that our sampling algorithm focuses on paths that are visible from the given viewpoint. Our sampling algorithm builds on two recent developments in Markov chain Monte Carlo methods: adaptive Markov chain sampling...... and replica exchange. Using these techniques, each photon path is adaptively mutated and it explores the sampling space efficiently without being stuck at a local peak of the importance function. We have implemented this sampling approach in the progressive photon mapping algorithm which provides visibility...

  3. A novel non-invasive diagnostic sampling technique for cutaneous leishmaniasis.

    Directory of Open Access Journals (Sweden)

    Yasaman Taslimi

    2017-07-01

    Full Text Available Accurate diagnosis of cutaneous leishmaniasis (CL is important for chemotherapy and epidemiological studies. Common approaches for Leishmania detection involve the invasive collection of specimens for direct identification of amastigotes by microscopy and the culturing of promastigotes from infected tissues. Although these techniques are highly specific, they require highly skilled health workers and have the inherent risks of all invasive procedures, such as pain and risk of bacterial and fungal super-infection. Therefore, it is essential to reduce discomfort, potential infection and scarring caused by invasive diagnostic approaches especially for children. In this report, we present a novel non-invasive method, that is painless, rapid and user-friendly, using sequential tape strips for sampling and isolation of DNA from the surface of active and healed skin lesions of CL patients. A total of 119 patients suspected of suffering from cutaneous leishmaniasis with different clinical manifestations were recruited and samples were collected both from their lesions and from uninfected areas. In addition, 15 fungal-infected lesions and 54 areas of healthy skin were examined. The duration of sampling is short (less than one minute and species identification by PCR is highly specific and sensitive. The sequential tape stripping sampling method is a sensitive, non-invasive and cost-effective alternative to traditional diagnostic assays and it is suitable for field studies as well as for use in health care centers.

  4. Separation of arsenic species by capillary electrophoresis with sample-stacking techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zu Liang; Naidu, Ravendra [Adelaide Laboratory, CSIRO Land and Water, PMB2, 5064, Glen Osmond, SA (Australia); Lin, Jin-Ming [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 100085, Beijing (China)

    2003-03-01

    A simple capillary zone electrophoresis procedure was developed for the separation of arsenic species (AsO{sub 2}{sup 2-}, AsO{sub 4}{sup 2-}, and dimethylarsinic acid, DMA). Both counter-electroosmotic and co-electroosmotic (EOF) modes were investigated for the separation of arsenic species with direct UV detection at 185 nm using 20 mmol L{sup -1} sodium phosphate as the electrolyte. The separation selectivity mainly depends on the separation modes and electrolyte pH. Inorganic anions (Cl{sup -}, NO{sub 2}{sup -}, NO{sub 3}{sup -} and SO{sub 4}{sup 2-}) presented in real samples did not interfere with arsenic speciation in either separation mode. To improve the detection limits, sample-stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were investigated for the preconcentration of As species in co-CZE mode. Less than 1 {mu}mol L{sup -1} of detection limits for As species were achieved using FASI. The proposed method was demonstrated for the separation and detection of As species in water. (orig.)

  5. Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques.

    Science.gov (United States)

    Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Göttlicher, Jörg; Denecke, Melissa A; Mangold, Stefan; Ruggiero, Pacifico

    2010-08-01

    Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg(-1). Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as mu-XRF, mu-XRD and mu-XANES were necessary to solve bulk Hg speciation, in both soil fractions soil samples were metacinnabar (beta-HgS), cinnabar (alpha-HgS), corderoite (Hg(3)S(2)Cl(2)), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Sample preparation technique for transmission electron microscopy anodized Al-Li-SiC metal matrix composite

    International Nuclear Information System (INIS)

    Shahid, M.; Thomson, G.E.

    1997-01-01

    Along with improved mechanical properties, metal matrix composites (MMC) have a disadvantage of enhanced corrosion susceptibility in aggressive environments. Recent studies on corrosion behaviour of an Al-alloy 8090/SiC MMC, revealed considerably high corrosion rates of the MMC in near neutral solutions containing chloride ions. Anodizing is one of the potential surface treatment for the MMC to provide protective coating against corrosion. The surface and cross section of the anodized MMC can easily be observed using scanning electron microscope. The anodizing behaviour of the MMC can be understood further if the anodized cross section in examined under transmission electron microscope (TEM). However, it is relatively difficult to prepare small (3 mm diameter) electron transparent specimens of the MMC supporting an anodic film. In the present study a technique has been developed for preparing thin electron transparent specimens of the anodized MMC. This technique employed conventional ion beam thinning process but the preparation of small discs was a problem. A MMMC consisting of Al-alloy 8090 with 20 % (by weight) SiC particulate with an average size of 5 Mu m, was anodized and observed in TEM after preparing the samples using the above mentioned techniques. (author)

  7. Endodontic pathogens causing deep neck space infections: clinical impact of different sampling techniques and antibiotic susceptibility.

    Science.gov (United States)

    Poeschl, Paul W; Crepaz, Valentina; Russmueller, Guenter; Seemann, Rudolf; Hirschl, Alexander M; Ewers, Rolf

    2011-09-01

    The aims of the present study were to compare microbial populations in patients suffering from deep neck space abscesses caused by primary endodontic infections by sampling the infections with aspiration or swabbing techniques and to determine the susceptibility rates of the isolated bacteria to commonly used antibiotics. A total of 89 patients with deep neck space abscesses caused by primary endodontic infections requiring extraoral incision and drainage under general anesthesia were included. Either aspiration or swabbing was used to sample microbial pus specimens. The culture of the microbial specimens and susceptibility testing were performed following standard procedures. A total of 142 strains were recovered from 76 patients. In 13 patients, no bacteria were found. The predominant bacteria observed were streptococci (36%), staphylococci (13%), Prevotella (8%), and Peptostreptococcus (6%). A statistically significant greater number of obligate anaerobes were found in the aspiration group. The majority of patients presented a mixed aerobic-anaerobic population of bacterial flora (62%). The antibiotic resistance rates for the predominant bacteria were 10% for penicillin G, 9% for amoxicillin, 0% for amoxicillin clavulanate, 24% for clindamycin, and 24% for erythromycin. The results of our study indicated that a greater number of anaerobes were found when sampling using the aspiration technique. Penicillin G and aminopenicillins alone are not always sufficient for the treatment of severe deep neck space abscesses; beta-lactamase inhibitor combinations are more effective. Bacteria showed significant resistant rates to clindamycin. Thus, its single use in penicillin-allergic patients has to be carefully considered. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Application of neutron activation analysis technique in elemental determination of lichen samples

    International Nuclear Information System (INIS)

    Djoko Prakoso Dwi Atmodjo; Syukria Kurniawati; Woro Yatu Niken Syahfitri; Nana Suherman; Dadang Supriatna

    2010-01-01

    Lichen is one of the biological materials as pollution monitor that can give information about level, direction, and history of various pollutants in environment. Small sample weights and elemental content of lichens is on the order of ppm, so that its characterization requires advanced analytical techniques that has high sensitivity and capable of analyzing samples with weight of - 25 mg, such as neutron activation analysis. In this research, determination of elements was done in lichen samples obtained from Kiaracondong and Holis areas in Bandung city, to understanding the difference of industrial exposure level on surrounding environment. Samples were irradiated in RSG GA Siwabessy, Serpong, at 15 MW for 1-2 and 60 minutes for short irradiation and long irradiation, respectively. The samples were then counted using HPGe detector with GENIE 2000 software. The level of element in lichen for Kiaracondong area were Co, Cr, Cs, Fe, Mg, Mn, Sb, Sc, and V in the range of 0.55-0.86, 1.47-2.57, 0.87-1.19, 540-1005, 949-1674, 34.91-45.94, 0.08-0.14, 0.16-0.31, and ≤ 2.33 mg/kg, respectively, while for Holis area were 1.04-2.37, 4.41-10.36, 0.41-0.89, 3166-709, 1131-1422, 40.97-72.51, 0.33-0.50, 0.98-2.18, and 5.30-13.05 mg/kg respectively. From these results, it is known that pollution exposure from the semi industrial area Holis provide greater influence than in the semi industrial area Kiaracondong. (author)

  9. Trace uranium analysis in Indian coal samples using the fission track technique

    International Nuclear Information System (INIS)

    Jojo, P.J.; Rawat, A.; Kumar, Ashavani; Prasad, Rajendra

    1993-01-01

    The ever-growing demand for energy has resulted in the extensive use of fossil fuels, especially coal, for power generation. Coal and its by-products often contain significant amounts of radionuclides, including uranium, which is the ultimate source of the radioactive gas Radon-222. The present study gives the concentration of uranium in coal samples of different collieries in India, collected from various thermal power plants in the state of Uttar Pradesh. The estimates were made using the fission track technique. Latent damage tracks were not found to be uniformly distributed but showed sun bursts and clusters. Non-uniform distributions of trace elements are a very common phenomenon in rocks. The levels of uranium in the coal samples were found to vary from 2.0 to 4.9 ppm in uniform distributions and from 21.3 to 41.0 ppm in non-uniform distributions. Measurements were also made on fly ash samples where the average uranium concentration was found to be 8.4 and 49.3 ppm in uniform and non-uniform distributions, respectively. (author)

  10. Performance evaluation of an importance sampling technique in a Jackson network

    Science.gov (United States)

    brahim Mahdipour, E.; Masoud Rahmani, Amir; Setayeshi, Saeed

    2014-03-01

    Importance sampling is a technique that is commonly used to speed up Monte Carlo simulation of rare events. However, little is known regarding the design of efficient importance sampling algorithms in the context of queueing networks. The standard approach, which simulates the system using an a priori fixed change of measure suggested by large deviation analysis, has been shown to fail in even the simplest network settings. Estimating probabilities associated with rare events has been a topic of great importance in queueing theory, and in applied probability at large. In this article, we analyse the performance of an importance sampling estimator for a rare event probability in a Jackson network. This article carries out strict deadlines to a two-node Jackson network with feedback whose arrival and service rates are modulated by an exogenous finite state Markov process. We have estimated the probability of network blocking for various sets of parameters, and also the probability of missing the deadline of customers for different loads and deadlines. We have finally shown that the probability of total population overflow may be affected by various deadline values, service rates and arrival rates.

  11. Determination of organically bound Tritium in environmental samples by application of the oxidizing plasma technique

    International Nuclear Information System (INIS)

    Strack, S.; Koenig, L.A.

    1981-12-01

    The low-temperature oxidizing plasma technique with a suitable system for trapping the water formed in the oxidation process can be used to determine T bound organically in low-level samples. First, the samples are freeze-dried and the tissue water obtained in this way is measured, after distillation, in a liquid scintillation spectrometer. The residual dry matter is ashed in the reactor chamber of the plasma system. Oxidation takes place at temperatures not exceeding 200 0 C in an oxygen flow of about 40 ml/min. The water of oxidation is collected in a cold trap installed behind the reactor chamber. A volume of about 10 ml of water is sufficient to measure the tritium activity without enrichment. The oxidation behavior of various organic materials has been tested. Some first results of T concentrations in tissue water and the organic dry matter from food and plant samples collected in the vicinity of the Nuclear Research Center are presented. The method has the advantage that a commercially available instrument can be used requiring only little additional equipment. Handling is much less dangerous and contamination effects by atmospheric T can be easily kept at a minimum. (orig./HP) [de

  12. Techniques for sampling nuclear waste tank contents and in situ measurement of activity

    International Nuclear Information System (INIS)

    Lawrence, R.C.

    1978-04-01

    A study was conducted to develop suitable sampling equipment and techniques for characterizing the mechanical properties of nuclear wastes; identifying effective means of measuring radiation levels, temperatures, and neutron fluxes in situ in wastes; and developing a waste core sampler. A portable, stainless steel probe was developed which is placed in the tank through a riser. This probe is built for the insertion of instrumentation that can measure the contents of the tank at any level and take temperature, radiation, and neutron activation readings with reliable accuracy. A simple and reliable instrument for the in situ extraction of waste materials ranging from liquid to concrete-like substances was also developed. This portable, stainless steel waste core sampler can remove up to one liter of radioactive waste from tanks for transportation to hot cell laboratories for analysis of hardness, chemical form, and isotopic content. A cask for transporting the waste samples from the tanks to the laboratory under radiation-protected conditions was also fabricated. This cask was designed with a ''boot'' or inner-seal liner to contain any radioactive wastes that might remain on the outside of the waste core sampling device

  13. Comparative study of modern extraction techniques for the determination of environmental samples (M14)

    International Nuclear Information System (INIS)

    Gfrerer, M.; Lankmayr, E.

    2002-01-01

    Full text: The aim of any extraction method in analytical chemistry is, to effectively separate the analytes from the matrix. The whole step should be fast and quantitative with minimal solvent and time required. The classical Soxhlet extraction usually requires large volumes (up to 200 ml) of solvent to be refluxed through the solid samples for several hours. Therefore, in the last decades, alternatives for this extraction method have been presented and investigated such as ultrasonic extraction (UE), supercritical fluid extraction (SFE), accelerated solvent extraction (ASE), microwave-assisted extraction (MAE) and fluidized-bed extraction (FBE). The actual choice for analytical application is frequently the initial capital cost, operating costs, simplicity of operation, amount of organic solvent required and sample throughput. Since sample preparation is a critical step in the analytical cycle, special care has to be taken for an accurate choice and optimization of extraction techniques and clean-up procedures. Therefore, MAE and FBE were investigated for their influential extraction parameters and these parameters were optimized for the extraction of organochlorine biocides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons from environmental matrices like soil, sediment and sewage sludge. The extraction yields were compared with those obtained by Soxhlet extraction performed following DIN-methods. Finally, the optimized modern methods were validated by systematic experiments with certified reference materials. Refs. 3 (author)

  14. Corrigendum to “Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines” [Agric. Forest Meteorol. 165 (2012) 53–63

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola

    2012-01-01

    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m...... from eddy-covariance systems featuring short (4 m) and very short (1 m) sampling lines running at the same clover field and show that relative humidity effects persist also for these setups, and should not be neglected. Starting from the work of Ibrom and co-workers, we propose a mixed method...... and correction method proposed here is deemed applicable to closed-path systems featuring a broad range of sampling lines, and indeed applicable also to passive gases as a special case. The methods described in this paper are incorporated, as processing options, in the free and open-source eddy...

  15. Paths correlation matrix.

    Science.gov (United States)

    Qian, Weixian; Zhou, Xiaojun; Lu, Yingcheng; Xu, Jiang

    2015-09-15

    Both the Jones and Mueller matrices encounter difficulties when physically modeling mixed materials or rough surfaces due to the complexity of light-matter interactions. To address these issues, we derived a matrix called the paths correlation matrix (PCM), which is a probabilistic mixture of Jones matrices of every light propagation path. Because PCM is related to actual light propagation paths, it is well suited for physical modeling. Experiments were performed, and the reflection PCM of a mixture of polypropylene and graphite was measured. The PCM of the mixed sample was accurately decomposed into pure polypropylene's single reflection, pure graphite's single reflection, and depolarization caused by multiple reflections, which is consistent with the theoretical derivation. Reflection parameters of rough surface can be calculated from PCM decomposition, and the results fit well with the theoretical calculations provided by the Fresnel equations. These theoretical and experimental analyses verify that PCM is an efficient way to physically model light-matter interactions.

  16. ANALYSIS OF MONTE CARLO SIMULATION SAMPLING TECHNIQUES ON SMALL SIGNAL STABILITY OF WIND GENERATOR- CONNECTED POWER SYSTEM

    Directory of Open Access Journals (Sweden)

    TEMITOPE RAPHAEL AYODELE

    2016-04-01

    Full Text Available Monte Carlo simulation using Simple Random Sampling (SRS technique is popularly known for its ability to handle complex uncertainty problems. However, to produce a reasonable result, it requires huge sample size. This makes it to be computationally expensive, time consuming and unfit for online power system applications. In this article, the performance of Latin Hypercube Sampling (LHS technique is explored and compared with SRS in term of accuracy, robustness and speed for small signal stability application in a wind generator-connected power system. The analysis is performed using probabilistic techniques via eigenvalue analysis on two standard networks (Single Machine Infinite Bus and IEEE 16–machine 68 bus test system. The accuracy of the two sampling techniques is determined by comparing their different sample sizes with the IDEAL (conventional. The robustness is determined based on a significant variance reduction when the experiment is repeated 100 times with different sample sizes using the two sampling techniques in turn. Some of the results show that sample sizes generated from LHS for small signal stability application produces the same result as that of the IDEAL values starting from 100 sample size. This shows that about 100 sample size of random variable generated using LHS method is good enough to produce reasonable results for practical purpose in small signal stability application. It is also revealed that LHS has the least variance when the experiment is repeated 100 times compared to SRS techniques. This signifies the robustness of LHS over that of SRS techniques. 100 sample size of LHS produces the same result as that of the conventional method consisting of 50000 sample size. The reduced sample size required by LHS gives it computational speed advantage (about six times over the conventional method.

  17. Whole arm manipulation planning based on feedback velocity fields and sampling-based techniques.

    Science.gov (United States)

    Talaei, B; Abdollahi, F; Talebi, H A; Omidi Karkani, E

    2013-09-01

    Changing the configuration of a cooperative whole arm manipulator is not easy while enclosing an object. This difficulty is mainly because of risk of jamming caused by kinematic constraints. To reduce this risk, this paper proposes a feedback manipulation planning algorithm that takes grasp kinematics into account. The idea is based on a vector field that imposes perturbation in object motion inducing directions when the movement is considerably along manipulator redundant directions. Obstacle avoidance problem is then considered by combining the algorithm with sampling-based techniques. As experimental results confirm, the proposed algorithm is effective in avoiding jamming as well as obstacles for a 6-DOF dual arm whole arm manipulator. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  18. Yield strength, shear stress and toughness of YBCO samples textured by Bridgman technique

    International Nuclear Information System (INIS)

    Roa, J J; Capdevila, X G; Martinez, M; Segarra, M; Jimenez-Pique, E

    2008-01-01

    Mechanical properties of the orthorhombic phase of YBa 2 Cu 3 O 7-δ (Y-123) at room temperature have been investigated at different applied loads using nanoindentation technique. The study was carried out for several monodomains on the (001) planes for textured Bridgman samples with dispersed Y 2 BaCuO 5 (Y-211) particles as pinning centers. The yield strength (σ ys ), shear stress (τ m ) and toughness (K IC ) of Y123/Y211composite was determined at different applied loads. First and second mechanical properties have been calculated though the Hertz equations and the last one with Lawn et al. equations. Finally, the ultra-low imprints obtained by nanoindentation have been correlated with parameters obtained by Field Emission Scanning Electron Microscope (FE-SEM)

  19. Importance sampling techniques and treatment of electron transport in MCNP 4A

    International Nuclear Information System (INIS)

    Ueki, K.

    1994-01-01

    The continuous energy Monte Carlo code MCNP was developed by the Radiation Transport Group at Los Alamos National Laboratory and the MCNP 4A version is available, now. The MCNP 4A is able to do the coupled neutron-secondary gamma-ray-electron-bremsstrahlung calculation. The calculated results, such as energy spectra, tally fluctuation chart, and geometrical input data can be displayed by using a work station. The document of the MCNP 4A code has no description on the subroutines, except few ones of 'SOURCE', 'TALLYX'. However, when we want to improve the MCNP Monte Carlo sampling techniques to get more accuracy or efficiency results for some problems, some subroutines are required or needed to revised. Three subroutines have been revised and built in the MCNP 4A code. (author)

  20. Simulative Investigation on Spectral Efficiency of Unipolar Codes based OCDMA System using Importance Sampling Technique

    Science.gov (United States)

    Farhat, A.; Menif, M.; Rezig, H.

    2013-09-01

    This paper analyses the spectral efficiency of Optical Code Division Multiple Access (OCDMA) system using Importance Sampling (IS) technique. We consider three configurations of OCDMA system namely Direct Sequence (DS), Spectral Amplitude Coding (SAC) and Fast Frequency Hopping (FFH) that exploits the Fiber Bragg Gratings (FBG) based encoder/decoder. We evaluate the spectral efficiency of the considered system by taking into consideration the effect of different families of unipolar codes for both coherent and incoherent sources. The results show that the spectral efficiency of OCDMA system with coherent source is higher than the incoherent case. We demonstrate also that DS-OCDMA outperforms both others in terms of spectral efficiency in all conditions.

  1. Calibrated Phase-Shifting Digital Holographic Microscope Using a Sampling Moiré Technique

    Directory of Open Access Journals (Sweden)

    Peng Xia

    2018-05-01

    Full Text Available A calibrated phase-shifting digital holographic microscope system capable of improving the quality of reconstructed images is proposed. Phase-shifting errors are introduced in phase-shifted holograms for numerous reasons, such as the non-linearity of piezoelectric transducers (PZTs, wavelength fluctuations in lasers, and environmental disturbances, leading to poor-quality reconstructions. In our system, in addition to the camera used to record object information, an extra camera is used to record interferograms, which are used to analyze phase-shifting errors using a sampling Moiré technique. The quality of the reconstructed object images can be improved by the phase-shifting error compensation algorithm. Both the numerical simulation and experiment demonstrate the effectiveness of the proposed system.

  2. Probabilistic techniques using Monte Carlo sampling for multi- component system diagnostics

    International Nuclear Information System (INIS)

    Aumeier, S.E.; Lee, J.C.; Akcasu, A.Z.

    1995-01-01

    We outline the structure of a new approach at multi-component system fault diagnostics which utilizes detailed system simulation models, uncertain system observation data, statistical knowledge of system parameters, expert opinion, and component reliability data in an effort to identify incipient component performance degradations of arbitrary number and magnitude. The technique involves the use of multiple adaptive Kalman filters for fault estimation, the results of which are screened using standard hypothesis testing procedures to define a set of component events that could have transpired. Latin Hypercube sample each of these feasible component events in terms of uncertain component reliability data and filter estimates. The capabilities of the procedure are demonstrated through the analysis of a simulated small magnitude binary component fault in a boiling water reactor balance of plant. The results show that the procedure has the potential to be a very effective tool for incipient component fault diagnosis

  3. Comparison of mobile and stationary spore-sampling techniques for estimating virulence frequencies in aerial barley powdery mildew populations

    DEFF Research Database (Denmark)

    Hovmøller, M.S.; Munk, L.; Østergård, Hanne

    1995-01-01

    Gene frequencies in samples of aerial populations of barley powdery mildew (Erysiphe graminis f.sp. hordei), which were collected in adjacent barley areas and in successive periods of time, were compared using mobile and stationary sampling techniques. Stationary samples were collected from trap ...

  4. Tracer techniques for urine volume determination and urine collection and sampling back-up system

    Science.gov (United States)

    Ramirez, R. V.

    1971-01-01

    The feasibility, functionality, and overall accuracy of the use of lithium were investigated as a chemical tracer in urine for providing a means of indirect determination of total urine volume by the atomic absorption spectrophotometry method. Experiments were conducted to investigate the parameters of instrumentation, tracer concentration, mixing times, and methods for incorporating the tracer material in the urine collection bag, and to refine and optimize the urine tracer technique to comply with the Skylab scheme and operational parameters of + or - 2% of volume error and + or - 1% accuracy of amount of tracer added to each container. In addition, a back-up method for urine collection and sampling system was developed and evaluated. This back-up method incorporates the tracer technique for volume determination in event of failure of the primary urine collection and preservation system. One chemical preservative was selected and evaluated as a contingency chemical preservative for the storage of urine in event of failure of the urine cooling system.

  5. Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Sanna F.; Knipe, Kevin; Manero, Albert; Raghavan, Seetha [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Meid, Carla; Wischek, Janine; Bartsch, Marion [German Aerospace Center (DLR), Institute of Materials Research, 51147 Cologne (Germany); Okasinski, John; Almer, Jonathan [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Karlsson, Anette M. [Cleveland State University, 2121 Euclid Avenue, Cleveland, Ohio 44115 (United States)

    2013-08-15

    Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

  6. The development and use of parametric sampling techniques for probabilistic risk assessment

    International Nuclear Information System (INIS)

    Dalrymple, G.J.; Broyd, T.W.

    1987-01-01

    In order to enable evaluation to be made of proposals for the underground disposal of low and intermediate level radioactive wastes in the United Kingdom, the Department of the Environment (DoE) research programme includes development of computer-based methods for use in a multistage assessment process. To test the adequacy of the various methods of data acquisitions and radiological assessment a mock assessment exercise is currently being conducted by the department. This paper outlines the proposed methodology which provides for the use of probabilistic modelling based upon the Atomic Energy of Canada Ltd SYVAC variability analysis approach using new models (SYVAC 'A') and data appropriate to UK conditions for a deep horizontal tunnel repository concept. This chapter describes the choice of a suitable technique for the sampling of data input to the SYVAC 'A' model and techniques for analysing the predictions of dose and risk made by the model. The sensitivity of the model predictions (risk and dose to man) to the input parameters was compared for four different methods. All four methods identified the same geological parameters as the most important. (author)

  7. Improved technique for measuring the size distribution of black carbon particles in rainwater and snow samples

    Science.gov (United States)

    Mori, T.; Moteki, N.; Ohata, S.; Koike, M.; Azuma, K. G.; Miyazaki, Y.; Kondo, Y.

    2015-12-01

    Black carbon (BC) is the strongest contributor to sunlight absorption among atmospheric aerosols. Quantitative understanding of wet deposition of BC, which strongly affects the spatial distribution of BC, is important to improve our understandings on climate change. We have devised a technique for measuring the masses of individual BC particles in rainwater and snow samples, as a combination of a nebulizer and a single-particle soot photometer (SP2) (Ohata et al. 2011, 2013; Schwarz et al. 2012; Mori et al. 2014). We show two important improvements in this technique: 1)We have extended the upper limit of detectable BC particle diameter from 0.9 μm to about 4.0 μm by modifying the photodetector for measuring the laser-induced incandescence signal. 2)We introduced a pneumatic nebulizer Marin-5 (Cetac Technologies Inc., Omaha, NE, USA) and experimentally confirmed its high extraction efficiency (~50%) independent of particle diameter up to 2.0 μm. Using our improved system, we simultaneously measured the size distribution of BC particles in air and rainwater in Tokyo. We observed that the size distribution of BC in rainwater was larger than that in air, indicating that large BC particles were effectively removed by precipitation. We also observed BC particles with diameters larger than 1.0 μm, indicating that further studies of wet deposition of BC will require the use of the modified SP2.

  8. Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques

    International Nuclear Information System (INIS)

    Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Goettlicher, Joerg; Denecke, Melissa A.; Mangold, Stefan; Ruggiero, Pacifico

    2010-01-01

    Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg -1 . Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as μ-XRF, μ-XRD and μ-XANES were necessary to solve bulk Hg speciation, in both soil fractions 3 S 2 Cl 2 ), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 μm. No interaction among Hg-species and soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. - Direct mercury (Hg) speciation in chlor-alkali plant contaminated soils enabled the identification of potentially dangerous Hg-S/Cl amorphous species.

  9. Effect of postmortem sampling technique on the clinical significance of autopsy blood cultures.

    Science.gov (United States)

    Hove, M; Pencil, S D

    1998-02-01

    Our objective was to investigate the value of postmortem autopsy blood cultures performed with an iodine-subclavian technique relative to the classical method of atrial heat searing and antemortem blood cultures. The study consisted of a prospective autopsy series with each case serving as its own control relative to subsequent testing, and a retrospective survey of patients coming to autopsy who had both autopsy blood cultures and premortem blood cultures. A busy academic autopsy service (600 cases per year) at University of Texas Medical Branch Hospitals, Galveston, Texas, served as the setting for this work. The incidence of non-clinically relevant (false-positive) culture results were compared using different methods for collecting blood samples in a prospective series of 38 adult autopsy specimens. One hundred eleven adult autopsy specimens in which both postmortem and antemortem blood cultures were obtained were studied retrospectively. For both studies, positive culture results were scored as either clinically relevant or false positives based on analysis of the autopsy findings and the clinical summary. The rate of false-positive culture results obtained by an iodine-subclavian technique from blood drawn soon after death were statistically significantly lower (13%) than using the classical method of obtaining blood through the atrium after heat searing at the time of the autopsy (34%) in the same set of autopsy subjects. When autopsy results were compared with subjects' antemortem blood culture results, there was no significant difference in the rate of non-clinically relevant culture results in a paired retrospective series of antemortem blood cultures and postmortem blood cultures using the iodine-subclavian postmortem method (11.7% v 13.5%). The results indicate that autopsy blood cultures obtained using the iodine-subclavian technique have reliability equivalent to that of antemortem blood cultures.

  10. Design and building of a homemade sample changer for automation of the irradiation in neutron activation analysis technique; Diseno y construccion de un prototipo de intercambiador para la automatizacion de la tecnica de analisis por activacion neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Gago, Javier; Hernandez, Yuri; Baltuano, Oscar; Bedregal, Patricia [Direccion de Investigacion y Desarrollo, Instituto Peruano de Energia Nuclear, Lima (Peru); Lopez, Yon [Universidad Nacional de Ingenieria, Lima (Peru); Urquizo, Rafael [Universidad Tecnologica del Peru, Lima (Peru)

    2014-07-01

    Because the RP-10 research reactor operates during weekends, it was necessary to design and build a sample changer for irradiation as part of the automation process of neutron activation analysis technique. The device is formed by an aluminum turntable disk which can accommodate 19 polyethylene capsules, containing samples to be sent using the pneumatic transfer system from the laboratory to the irradiation position. The system is operate by a control switchboard to send and return capsules in a variable preset time and by two different ways, allowing the determination of short, medium and long lived radionuclides. Also another mechanism is designed called 'exchange valve' for changing travel paths (pipelines) allowing the irradiated samples to be stored for a longer time in the reactor hall. The system design has allowed complete automation of this technique, enabling the irradiation of samples without the presence of an analyst. The design, construction and operation of the device is described and presented in this article. (authors).

  11. General principles governing sampling and measurement techniques for monitoring radioactive effluents from nuclear facilities

    International Nuclear Information System (INIS)

    Fitoussi, L.

    1978-01-01

    An explanation is given of the need to monitor the release of radioactive gases and liquid effluents from nuclear facilities, with particular emphasis on the ICRP recommendations and on the interest in this problem shown by the larger international organizations. This is followed by a description of the classes of radionuclides that are normally monitored in this way. The characteristics of monitoring 'in line' and 'by sample taking' are described; the disadvantages of in line monitoring and the problem of sample representativity are discussed. There follows an account of the general principles for measuring gaseous and liquid effluents that are applied in the techniques normally employed at nuclear facilities. Standards relating to the specifications for monitoring instruments are at present being devised by the International Electrotechnical Commission, and there are still major differences in national practices, at least as far as measurement thresholds are concerned. In conclusion, it is shown that harmonization of practices and standardization of equipment would probably help to make international relations in the field more productive. (author)

  12. Determination of elemental in soil samples from Gebeng area using NAA technique

    International Nuclear Information System (INIS)

    Md Suhaimi Elias; Wo, Y.M.; Mohd Suhaimi Hamzah

    2016-01-01

    Rapid development and urbanization will increase number of residence and industrial area. Without proper management and control of pollution, these will give an adverse effect to environment and human life. The objective of this study to identify and quantify key contaminants into the environment of the Gebeng area as a result of industrial and human activities. Gebeng area was gazetted as one of the industrial estate in Pahang state. Assessment of elemental pollution in soil of Gebeng area base on level of concentration, enrichment factor and geo-accumulation index. The enrichment factors (EFs) were determined by the elemental rationing method, whilst the geo-accumulation index (I_g_e_o) by comparing of current to continental crustal average concentration of element. Twenty-seven of soil samples were collected from Gebeng area. Soil samples were analysed by using Neutron Activation Analyses (NAA) technique. The obtained data showed higher concentration of iron (Fe) due to abundance in soil compared to other elements. The results of enrichment factor showed that Gebeng area have enrich with elements of As, Br, Hf, Sb, Th and U. Base on the geo-accumulation index (I_g_e_o) classification, the soil quality of Gebeng area can be classified as class 0, (uncontaminated) to Class 3, (moderately to heavily contaminated). (author)

  13. Determination of the uranium concentration in water samples by the technique of fission track recording

    International Nuclear Information System (INIS)

    Geraldo, L.P.

    1979-01-01

    The technique of fission track register was developed for the determination of micrograms of uranium. The Makrofol KG, a synthetic plastic made by Bayer, was used as the detector and the wet method was utilized. The detector calibration curve allows the determination of the uranium concentration in a sample within an interval from 8.0 to 0.4μgU/L, the total error ranging from 3.3% to 29.0% respectively. The method was used in the determination of the uranium content in various water samples, obtained from various sources like rivers, sea etc. in the state of Sao Paulo, Brazil. Results were compared with those obtained by other authors using different methods. The average concentration found in sea waters (3.27 +- 9.12μgU/l) by this method is compatible with the international average accepted value of 3.3μgU/l, irrespective of site and depth. The determination of the uranium content by fission track counting has proved to be very convenient. (Author) [pt

  14. Nuclear techniques to investigate source and origin of groundwater pollutants and their flow path at Indian Rare Earths Ltd., Cochin, Kerala

    International Nuclear Information System (INIS)

    Tirumalesh, K.; Shivanna, K.; Noble, J.

    2007-01-01

    Hydrochemical, environmental isotope and injected radiotracer investigations were carried out in order to investigate the possible source of contaminants and their movement in groundwater at Indian Rare Earths (IRE) site. Water samples were collected from piezometers, dug wells and river in and around IRE site for measurement of physical parameters, chemistry and isotopes. Chemical results show high fluoride, nitrate, sulphate and phosphate concentrations in piezometers whereas dug wells and river samples are free from contamination. Isotope data indicate that the contaminated groundwaters are enriched in δ 2 H and δ 18 O compared to dug well and river samples. Radiotracer experiments were carried out using single-well and multi-well techniques (radiotracers: 82 Br and 3 H) for determining groundwater filtration velocity and flow direction, respectively. Groundwater filtration velocity was found to be about 1.3 cm/day and flow direction is from south to north. Based on the investigations it can be concluded that groundwater is getting contamination from southern part of IRE campus and the possible source for these contaminants could be the Fertilizer and Chemical of Travancore (FACT) industry. (author)

  15. Aircraft automatic-flight-control system with inversion of the model in the feed-forward path using a Newton-Raphson technique for the inversion

    Science.gov (United States)

    Smith, G. A.; Meyer, G.; Nordstrom, M.

    1986-01-01

    A new automatic flight control system concept suitable for aircraft with highly nonlinear aerodynamic and propulsion characteristics and which must operate over a wide flight envelope was investigated. This exact model follower inverts a complete nonlinear model of the aircraft as part of the feed-forward path. The inversion is accomplished by a Newton-Raphson trim of the model at each digital computer cycle time of 0.05 seconds. The combination of the inverse model and the actual aircraft in the feed-forward path alloys the translational and rotational regulators in the feedback path to be easily designed by linear methods. An explanation of the model inversion procedure is presented. An extensive set of simulation data for essentially the full flight envelope for a vertical attitude takeoff and landing aircraft (VATOL) is presented. These data demonstrate the successful, smooth, and precise control that can be achieved with this concept. The trajectory includes conventional flight from 200 to 900 ft/sec with path accelerations and decelerations, altitude changes of over 6000 ft and 2g and 3g turns. Vertical attitude maneuvering as a tail sitter along all axes is demonstrated. A transition trajectory from 200 ft/sec in conventional flight to stationary hover in the vertical attitude includes satisfactory operation through lift-cure slope reversal as attitude goes from horizontal to vertical at constant altitude. A vertical attitude takeoff from stationary hover to conventional flight is also demonstrated.

  16. The particle analysis based on FT-TIMS technique for swipe sample under the frame of nuclear safeguard

    International Nuclear Information System (INIS)

    Yang Tianli; Liu Xuemei; Liu Zhao; Tang Lei; Long Kaiming

    2008-06-01

    Under the frame of nuclear safeguard, the particles analysis for swipe sample is an advance mean to detect the undeclared uranium enriched facilities and undeclared uranium enriched activity. The technique of particle analysis based on fission track-thermal ionization mass spectrometry (FT-TIMS) for swipe sample have been built. The reliability and the experimental background for selecting particles consisting of uranium from swipe sample by FT method have been verified. In addition, the utilization coefficient of particles on the surface of swipe sample have also been tested. These works have provided the technique support for application in the area of nuclear verification. (authors)

  17. Innovative directional and position specific sampling technique. Phase 3: Final report, July 1992--September 1994

    International Nuclear Information System (INIS)

    Hutzel, W.J.; Hill, J.L. III; Foster, E.L.

    1994-09-01

    The POLO System is a major enhancement to the state of the art for subsurface environmental restoration equipment. The system locate s the tip position of penetrometer probes as they are placed underground while meeting the rigid constraints of environmental restoration applications. POLO is applicable to small diameter probes, does not obstruct the center of the probe, is rugged, is unaffected by the presence of steel or other magnetic material, and is capable of remote operation beneath underground tanks or foundations. The development and adaptation of the POLO System for use with penetrometers has progressed through three development phases prior to commercialization. Phases I and II of the contract included the design, testing, and integration of all components of the POLO device. Efforts were made to simulate field conditions in terms of the scale of the components as well as the operating environment. The preestablished success criterion, which has been maintained throughout the research, was to demonstrate path tracking with a total error of less than 0.50% of the distance traveled for distances less than 70 meters. The results tests on individual POLO components showed that the equipment met or exceeded the success criterion. Phase II laboratory scale path tracking experiments also met the success criterion. Phase III moved the POLO System into the field. The full-scale field demonstration tested the ability of the new POLO Module to track the path of a small diameter probe as it moved underground

  18. Polygonal-path approximations on the path spaces of quantum-mechanical systems: properties of the polygonal paths

    International Nuclear Information System (INIS)

    Exner, P.; Kolerov, G.I.

    1981-01-01

    Properties of the subset of polygonal paths in the Hilbert space H of paths referring to a d-dimensional quantum-mechanical system are examined. Using the reproduction kernel technique we prove that each element of H is approximated by polygonal paths uniformly with respect to the ''norm'' of time-interval partitions. This result will be applied in the second part of the present paper to prove consistency of the uniform polygonal-path extension of the Feynman maps [ru

  19. Quantifying ruminal nitrogen metabolism using the omasal sampling technique in cattle--a meta-analysis.

    Science.gov (United States)

    Broderick, G A; Huhtanen, P; Ahvenjärvi, S; Reynal, S M; Shingfield, K J

    2010-07-01

    Mixed model analysis of data from 32 studies (122 diets) was used to evaluate the precision and accuracy of the omasal sampling technique for quantifying ruminal-N metabolism and to assess the relationships between nonammonia-N flow at the omasal canal and milk protein yield. Data were derived from experiments in cattle fed North American diets (n=36) based on alfalfa silage, corn silage, and corn grain and Northern European diets (n=86) composed of grass silage and barley-based concentrates. In all studies, digesta flow was quantified using a triple-marker approach. Linear regressions were used to predict microbial-N flow to the omasum from intake of dry matter (DM), organic matter (OM), or total digestible nutrients. Efficiency of microbial-N synthesis increased with DM intake and there were trends for increased efficiency with elevated dietary concentrations of crude protein (CP) and rumen-degraded protein (RDP) but these effects were small. Regression of omasal rumen-undegraded protein (RUP) flow on CP intake indicated that an average 32% of dietary CP escaped and 68% was degraded in the rumen. The slope from regression of observed omasal flows of RUP on flows predicted by the National Research Council (2001) model indicated that NRC predicted greater RUP supply. Measured microbial-N flow was, on average, 26% greater than that predicted by the NRC model. Zero ruminal N-balance (omasal CP flow=CP intake) was obtained at dietary CP and RDP concentrations of 147 and 106 g/kg of DM, corresponding to ruminal ammonia-N and milk urea N concentrations of 7.1 and 8.3mg/100mL, respectively. Milk protein yield was positively related to the efficiency of microbial-N synthesis and measured RUP concentration. Improved efficiency of microbial-N synthesis and reduced ruminal CP degradability were positively associated with efficiency of capture of dietary N as milk N. In conclusion, the results of this study indicate that the omasal sampling technique yields valuable estimates

  20. The novel programmable riometer for in-depth ionospheric and magnetospheric observations (PRIAMOS) using direct sampling DSP techniques

    OpenAIRE

    Dekoulis, G.; Honary, F.

    2005-01-01

    This paper describes the feasibility study and simulation results for the unique multi-frequency, multi-bandwidth, Programmable Riometer for in-depth Ionospheric And Magnetospheric ObservationS (PRIAMOS) based on direct sampling digital signal processing (DSP) techniques. This novel architecture is based on sampling the cosmic noise wavefront at the antenna. It eliminates the usage of any intermediate frequency (IF) mixer stages (-6 dB) and the noise balancing technique (-3 dB), providing a m...

  1. Application of BAT assessments for sampling and monitoring techniques in the UK EPR

    International Nuclear Information System (INIS)

    Kerdaniel, Erwan du Fou de; Colin, Julie; Moyano, Florian; Ardon, Audrey

    2014-01-01

    EDF Energy intends to build two EPR units at the Hinkley Point C site and has initiated the studies to build two more EPR units at Sizewell C. The project is lead by NNB GenCo, a subsidiary of EDF Energy. NNB GenCo, identified as the future operator and intelligent customer, relies upon EDF SA's expertise as responsible designer. UK EPR design substantiation has been carried out during the Generic Design Assessment (GDA), with two key reports, namely the Pre-Construction Environmental Report and the Pre-Construction Safety Report. These reports lead to specific enquiries initiated by the Regulators through 'Assessment Findings' in all areas, including Chemistry. Along the GDA process, the Environmental Agency (EA) has authorised chemical and radiochemical effluents discharges, requiring NNB GenCo to demonstrate that Best Available Techniques (BAT) are used to sample and monitor the discharges and the generation of solid wastes. BAT demonstrations deliverables are formalised via 'Commitment Plans' and detailed within 'Environmental Optimisation Studies (EOS)' reports, in line with NNB GenCo's management arrangements. NNB GenCo manages the production of the EOS reports. EDF CEIDRE Laboratory department (CEIDRE/DLAB) has been identified as a contributor to the BAT demonstration regarding sampling and monitoring of chemical effluents, active effluents and solid wastes. As required by the definition of BAT in the UK context, demonstrations are based on: UK Regulatory context and associated specific requirements, International feedback analysis of European, EPRI and IAEA documents, French fleet framework: benchmarks with the operator, analysis of technical and operational management documentation, Sizewell B framework: benchmarks with the operator, analysis of technical and operational management documents, International, British and French standards. A close partnership between the different EDF SA departments and a clear

  2. Analyses of archaeological pottery samples using X-ray fluorescence technique for provenance study

    International Nuclear Information System (INIS)

    Tamilarasu, S.; Swain, K.K.; Singhal, R.K; Reddy, A.V.R.; Acharya, R.; Velraj, G.

    2015-01-01

    Archaeological artifacts reveal information on past human activities, artifact preparation technology, art and possible trade. Ceramics are the most stable and abundant material in archaeological context. Pottery is the most abundant tracers in all archaeological excavations. Compared to major elements, elements present at trace concentrations levels are source specific and they maintain same concentration levels in source clay as well as finished products e.g., fired clay potteries. As it is difficult to find out exact source or origin, provenance study is carried out first to establish whether objects under study are from the same or different sources/origin. Various analytical techniques like instrumental neutron activation analysis (INAA), Ion beam analysis (IBA) and X-ray fluorescence (XRF) have been used for obtaining elemental concentrations in archaeological potteries. Portable X-ray fluorescence (pXRF) spectrometry provides a non-destructive means for elemental characterization of a wide range of archaeological materials. Ten archaeological pottery samples were collected from Kottapuram, Kerala under the supervision of archaeological survey of India. Portable X-ray fluorescence (pXRF) spectrometry using a handheld Olympus Innov-X Delta XRF device, ACD BARC, has been used for chemical characterization of the pottery samples. The instrument is equipped with the Delta Rhodium (Rh) anode X-Ray tube and uses a Silicon Drift Detector (resolution <200 eV at 5.95 keV Mn Kα X-ray). NIST 2781 SRM was analyzed for quality control purpose. Ten elements namely Fe, Ti, Mn, Co, Cu, Zn, Pb, Zr, Mo and Se were chosen for cluster analysis and their concentration values were utilized for multivariate statistical analysis using WinSTAT 9.0

  3. Development of novel separation techniques for biological samples in capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Huan -Tsung [Iowa State Univ., Ames, IA (United States)

    1994-07-27

    This dissertation includes three different topics: general introduction of capillary electrophoresis (CE); gradient in CE and CE in biological separations; and capillary gel electrophoresis (CGE) for DNA separation. Factors such as temperature, viscosity, pH, and the surface of capillary walls affecting the separation performance are demonstrated. A pH gradient between 3.0 and 5.2 is useful to improve the resolution among eight different organic acids. A flow gradient due to the change in the concentration of surfactant, which is able to coat to the capillary wall to change the flow rate and its direction, is also shown as a good way to improve the resolution for organic compounds. A temperature gradient caused by joule heat is shown by voltage programming to enhance the resolution and shorten the separation time for several phenolic compounds. The author also shows that self-regulating dynamic control of electroosmotic flow in CE by simply running separation in different concentrations of surfactant has less matrix effect on the separation performance. One of the most important demonstrations in this dissertation is that the author proposes on-column reaction which gives several advantages including the use of a small amount of sample, low risk of contamination, and time saving and kinetic features. The author uses this idea with laser induced fluorescence (LIF) as a detection mode to detect an on-column digestion of sub-ng of protein. This technique also is applied to single cell analysis in the group.

  4. Techniques for the detection of pathogenic Cryptococcus species in wood decay substrata and the evaluation of viability in stored samples

    Directory of Open Access Journals (Sweden)

    Christian Alvarez

    2013-02-01

    Full Text Available In this study, we evaluated several techniques for the detection of the yeast form of Cryptococcus in decaying wood and measured the viability of these fungi in environmental samples stored in the laboratory. Samples were collected from a tree known to be positive for Cryptococcus and were each inoculated on 10 Niger seed agar (NSA plates. The conventional technique (CT yielded a greater number of positive samples and indicated a higher fungal density [in colony forming units per gram of wood (CFU.g-1] compared to the humid swab technique (ST. However, the difference in positive and false negative results between the CT-ST was not significant. The threshold of detection for the CT was 0.05.10³ CFU.g-1, while the threshold for the ST was greater than 0.1.10³ CFU-1. No colonies were recovered using the dry swab technique. We also determined the viability of Cryptococcus in wood samples stored for 45 days at 25ºC using the CT and ST and found that samples not only continued to yield a positive response, but also exhibited an increase in CFU.g-1, suggesting that Cryptococcus is able to grow in stored environmental samples. The ST.1, in which samples collected with swabs were immediately plated on NSA medium, was more efficient and less laborious than either the CT or ST and required approximately 10 min to perform; however, additional studies are needed to validate this technique.

  5. Contributions from the data samples in NOC technique on the extracting of the Sq variation

    Science.gov (United States)

    Wu, Yingyan; Xu, Wenyao

    2015-04-01

    The solar quiet daily variation, Sq, a rather regular variation is usually observed at mid-low latitudes on magnetic quiet days or less-disturbed days. It is mainly resulted from the dynamo currents in the ionospheric E region, which are driven by the atmospheric tidal wind and different processes and flow as two current whorls in each of the northern and southern hemispheres[1]. The Sq exhibits a conspicuous day-to-day (DTD) variability in daily range (or strength), shape (or phase) and its current focus. This variability is mainly attributed to changes in the ionospheric conductivity and tidal winds, varying with solar radiation and ionospheric conditions. Furthermore, it presents a seasonal variation and solar cycle variation[2-4]. In generally, Sq is expressed with the average value of the five international magnetic quiet days. Using data from global magnetic stations, equivalent current system of daily variation can be constructed to reveal characteristics of the currents[5]. In addition, using the differences of H component at two stations on north and south side of the Sq currents of focus, Sq is extracted much better[6]. Recently, the method of Natural Orthoganal Components (NOC) is used to decompose the magnetic daily variation and express it as the summation of eigenmodes, and indicate the first NOC eigenmode as the solar quiet daily variation, the second as the disturbance daily variation[7-9]. As we know, the NOC technique can help reveal simpler patterns within a complex set of variables, without designed basic-functions such as FFT technique. But the physical explanation of the NOC eigenmodes is greatly depends on the number of data samples and data regular-quality. Using the NOC method, we focus our present study on the analysis of the hourly means of the H component at BMT observatory in China from 2001 to 2008. The contributions of the number and the regular-quality of the data samples on which eigenmode corresponds to the Sq are analyzed, by

  6. Efficient sampling techniques for uncertainty quantification in history matching using nonlinear error models and ensemble level upscaling techniques

    KAUST Repository

    Efendiev, Y.

    2009-11-01

    The Markov chain Monte Carlo (MCMC) is a rigorous sampling method to quantify uncertainty in subsurface characterization. However, the MCMC usually requires many flow and transport simulations in evaluating the posterior distribution and can be computationally expensive for fine-scale geological models. We propose a methodology that combines coarse- and fine-scale information to improve the efficiency of MCMC methods. The proposed method employs off-line computations for modeling the relation between coarse- and fine-scale error responses. This relation is modeled using nonlinear functions with prescribed error precisions which are used in efficient sampling within the MCMC framework. We propose a two-stage MCMC where inexpensive coarse-scale simulations are performed to determine whether or not to run the fine-scale (resolved) simulations. The latter is determined on the basis of a statistical model developed off line. The proposed method is an extension of the approaches considered earlier where linear relations are used for modeling the response between coarse-scale and fine-scale models. The approach considered here does not rely on the proximity of approximate and resolved models and can employ much coarser and more inexpensive models to guide the fine-scale simulations. Numerical results for three-phase flow and transport demonstrate the advantages, efficiency, and utility of the method for uncertainty assessment in the history matching. Copyright 2009 by the American Geophysical Union.

  7. Sampling

    CERN Document Server

    Thompson, Steven K

    2012-01-01

    Praise for the Second Edition "This book has never had a competitor. It is the only book that takes a broad approach to sampling . . . any good personal statistics library should include a copy of this book." —Technometrics "Well-written . . . an excellent book on an important subject. Highly recommended." —Choice "An ideal reference for scientific researchers and other professionals who use sampling." —Zentralblatt Math Features new developments in the field combined with all aspects of obtaining, interpreting, and using sample data Sampling provides an up-to-date treat

  8. Evaluation of alternative macroinvertebrate sampling techniques for use in a new tropical freshwater bioassessment scheme

    OpenAIRE

    Isabel Eleanor Moore; Kevin Joseph Murphy

    2015-01-01

    Aim: The study aimed to determine the effectiveness of benthic macroinvertebrate dredge net sampling procedures as an alternative method to kick net sampling in tropical freshwater systems, specifically as an evaluation of sampling methods used in the Zambian Invertebrate Scoring System (ZISS) river bioassessment scheme. Tropical freshwater ecosystems are sometimes dangerous or inaccessible to sampling teams using traditional kick-sampling methods, so identifying an alternative procedure that...

  9. Gamma self-shielding correction factors calculation for aqueous bulk sample analysis by PGNAA technique

    International Nuclear Information System (INIS)

    Nasrabadi, M.N.; Mohammadi, A.; Jalali, M.

    2009-01-01

    In this paper bulk sample prompt gamma neutron activation analysis (BSPGNAA) was applied to aqueous sample analysis using a relative method. For elemental analysis of an unknown bulk sample, gamma self-shielding coefficient was required. Gamma self-shielding coefficient of unknown samples was estimated by an experimental method and also by MCNP code calculation. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the gamma self-shielding within the sample volume is required.

  10. Laser-Assisted Sampling Techniques in Combination with ICP-MS: A Novel Approach for Particle Analysis at the IAEA Environmental Samples Laboratory

    International Nuclear Information System (INIS)

    Dzigal, N.; Chinea-Cano, E.

    2015-01-01

    Researchers have found many applications for lasers. About two decades ago, scientists started using lasers as sample introduction instruments for mass spectrometry measurements. Similarly, lasers as micro-dissection tools have also been increasingly on demand in the fields of life sciences, materials science, forensics, etc. This presentation deals with the interception of these aforementioned laser-assisted techniques to the field of particle analysis. Historically, the use of a nanosecond laser to ablate material has been used in materials science. Recently, it has been proven that in the analysis of particulate materials the disadvantages associated with the utilization of nanosecond lasers such as overheating and melting of the sample are suppressed when using femtosecond lasers. Further, due to the length of a single laser shot, fs-LA allows a more controlled ablation to occur and therefore the sample plasma is more homogeneous and less mass-fractionation events are detected. The use of laser micro-dissection devices enables the physical segmentation of microsized artefacts previously performed by a laborious manual procedure. By combining the precision of the laser cutting inherent to the LMD technique together with a particle identification methodology, one can increase the efficiency of single particle isolation. Further, besides the increase in throughput of analyses, this combination enhances the signal-to-noise ratio by removing matrix particles effectively. Specifically, this contribution describes the use of an Olympus+MMI laser microdissection device in improving the sample preparation of environmental swipe samples and the installation of an Applied Spectra J200 fs-LA/LIBS (laser ablation/laser inducedbreakdown spectroscopy) system as a sample introduction device to a quadrupole mass spectrometer, the iCap Q from Thermofisher Scientific at the IAEA Environmental Samples Laboratory are explored. Preliminary results of the ongoing efforts for the

  11. Spreading paths in partially observed social networks

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A.

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  12. Spreading paths in partially observed social networks.

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  13. Sample-interpolation timing: an optimized technique for the digital measurement of time of flight for γ rays and neutrons at relatively low sampling rates

    International Nuclear Information System (INIS)

    Aspinall, M D; Joyce, M J; Mackin, R O; Jarrah, Z; Boston, A J; Nolan, P J; Peyton, A J; Hawkes, N P

    2009-01-01

    A unique, digital time pick-off method, known as sample-interpolation timing (SIT) is described. This method demonstrates the possibility of improved timing resolution for the digital measurement of time of flight compared with digital replica-analogue time pick-off methods for signals sampled at relatively low rates. Three analogue timing methods have been replicated in the digital domain (leading-edge, crossover and constant-fraction timing) for pulse data sampled at 8 GSa s −1 . Events arising from the 7 Li(p, n) 7 Be reaction have been detected with an EJ-301 organic liquid scintillator and recorded with a fast digital sampling oscilloscope. Sample-interpolation timing was developed solely for the digital domain and thus performs more efficiently on digital signals compared with analogue time pick-off methods replicated digitally, especially for fast signals that are sampled at rates that current affordable and portable devices can achieve. Sample interpolation can be applied to any analogue timing method replicated digitally and thus also has the potential to exploit the generic capabilities of analogue techniques with the benefits of operating in the digital domain. A threshold in sampling rate with respect to the signal pulse width is observed beyond which further improvements in timing resolution are not attained. This advance is relevant to many applications in which time-of-flight measurement is essential

  14. Determination of structure of oriented samples using two-dimensional solid state NMR techniques

    International Nuclear Information System (INIS)

    Jin Hong; Harbison, G.S.

    1990-01-01

    One dimensional and two-dimensional MAS techniques can give detailed information about the structure and dynamics of oriented systems. We describe the application of such techniques to the liquid-crystalline polymer poly(p-phenyleneterphtalimide) (PPTA), and thence deduce the solid-state structure of the material. (author). 9 refs.; 6 figs

  15. ANALYTICAL TECHNIQUES FOR THE DETERMINATION OF MELOXICAM IN PHARMACEUTICAL FORMULATIONS AND BIOLOGICAL SAMPLES

    Directory of Open Access Journals (Sweden)

    Aisha Noreen

    2016-06-01

    Full Text Available Meloxicam (MX belongs to the family of oxicams which is the most important group of non steroidal anti-inflammatory drugs (NSAIDs and is widely used for their analgesics and antipyretic activities. It inhibits both COX-I and COX-II enzymes with less gastric and local tissues irritation. A number of analytical techniques have been used for the determination of MX in pharmaceutical as well as in biological fluids. These techniques include titrimetry, spectrometry, chromatography, flow injection spectrometry, fluorescence spectrometry, capillary zone electrophoresis and electrochemical techniques. Many of these techniques have also been used for the simultaneous determination of MX with other compounds. A comprehensive review of these analytical techniques has been done which could be useful for the analytical chemists and quality control pharmacists.

  16. Fast patient-specific Monte Carlo brachytherapy dose calculations via the correlated sampling variance reduction technique

    Energy Technology Data Exchange (ETDEWEB)

    Sampson, Andrew; Le Yi; Williamson, Jeffrey F. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

    2012-02-15

    Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose distributions for two patient cases: a clinical PSB postimplant prostate CT imaging study and a simulated post lumpectomy breast PSB implant planned on a screening dedicated breast cone-beam CT patient exam. CMC tallies the dose difference, {Delta}D, between highly correlated histories in homogeneous and heterogeneous geometries. The heterogeneous geometry histories were derived from photon collisions sampled in a geometrically identical but purely homogeneous medium geometry, by altering their particle weights to correct for bias. The prostate case consisted of 78 Model-6711 {sup 125}I seeds. The breast case consisted of 87 Model-200 {sup 103}Pd seeds embedded around a simulated lumpectomy cavity. Systematic and random errors in CMC were unfolded using low-uncertainty uncorrelated MC (UMC) as the benchmark. CMC efficiency gains, relative to UMC, were computed for all voxels, and the mean was classified in regions that received minimum doses greater than 20%, 50%, and 90% of D{sub 90}, as well as for various anatomical regions. Results: Systematic errors in CMC relative to UMC were less than 0.6% for 99% of the voxels and 0.04% for 100% of the voxels for the prostate and breast cases, respectively. For a 1 x 1 x 1 mm{sup 3} dose grid, efficiency gains were realized in all structures with 38.1- and 59.8-fold average gains within the prostate and breast clinical target volumes (CTVs), respectively. Greater than 99% of the voxels within the prostate and breast CTVs experienced an efficiency gain. Additionally, it was shown that efficiency losses were confined to low dose regions while the largest gains were located where little difference exists between the homogeneous and

  17. Sample application of sensitivity/uncertainty analysis techniques to a groundwater transport problem. National Low-Level Waste Management Program

    International Nuclear Information System (INIS)

    Seitz, R.R.; Rood, A.S.; Harris, G.A.; Maheras, S.J.; Kotecki, M.

    1991-06-01

    The primary objective of this document is to provide sample applications of selected sensitivity and uncertainty analysis techniques within the context of the radiological performance assessment process. These applications were drawn from the companion document Guidelines for Sensitivity and Uncertainty Analyses of Low-Level Radioactive Waste Performance Assessment Computer Codes (S. Maheras and M. Kotecki, DOE/LLW-100, 1990). Three techniques are illustrated in this document: one-factor-at-a-time (OFAT) analysis, fractional factorial design, and Latin hypercube sampling. The report also illustrates the differences in sensitivity and uncertainty analysis at the early and latter stages of the performance assessment process, and potential pitfalls that can be encountered when applying the techniques. The emphasis is on application of the techniques as opposed to the actual results, since the results are hypothetical and are not based on site-specific conditions

  18. Comparison of coarse coal dust sampling techniques in a laboratory-simulated longwall section.

    Science.gov (United States)

    Patts, Justin R; Barone, Teresa L

    2017-05-01

    Airborne coal dust generated during mining can deposit and accumulate on mine surfaces, presenting a dust explosion hazard. When assessing dust hazard mitigation strategies for airborne dust reduction, sampling is done in high-velocity ventilation air, which is used to purge the mining face and gallery tunnel. In this environment, the sampler inlet velocity should be matched to the air stream velocity (isokinetic sampling) to prevent oversampling of coarse dust at low sampler-to-air velocity ratios. Low velocity ratios are often encountered when using low flow rate, personal sampling pumps commonly used in underground mines. In this study, with a goal of employing mine-ready equipment, a personal sampler was adapted for area sampling of coarse coal dust in high-velocity ventilation air. This was done by adapting an isokinetic nozzle to the inlet of an Institute of Occupational Medicine (Edinburgh, Scotland) sampling cassette (IOM). Collected dust masses were compared for the modified IOM isokinetic sampler (IOM-MOD), the IOM without the isokinetic nozzle, and a conventional dust sampling cassette without the cyclone on the inlet. All samplers were operated at a flow rate typical of personal sampling pumps: 2 L/min. To ensure differences between collected masses that could be attributed to sampler design and were not influenced by artifacts from dust concentration gradients, relatively uniform and repeatable dust concentrations were demonstrated in the sampling zone of the National Institute for Occupational Safety and Health experimental mine gallery. Consistent with isokinetic theory, greater differences between isokinetic and non-isokinetic sampled masses were found for larger dust volume-size distributions and higher ventilation air velocities. Since isokinetic sampling is conventionally used to determine total dust concentration, and isokinetic sampling made a difference in collected masses, the results suggest when sampling for coarse coal dust the IOM-MOD may

  19. Prevalence of human papillomavirus in 5,072 consecutive cervical SurePath samples evaluated with the Roche cobas HPV real-time PCR assay

    DEFF Research Database (Denmark)

    Preisler, Sarah; Rebolj, Matejka; Untermann, Anette

    2013-01-01

    of the present study, Horizon, was to assess the prevalence of high-risk HPV infections in an area with a high background risk of cervical cancer, where women aged 23-65 years are targeted for cervical screening. We collected 6,258 consecutive cervical samples from the largest cervical screening laboratory......-29 years and 10% in women aged 60-65 years. HC2 assay was positive in 20% of samples, and cytology was abnormal (≥ atypical squamous cells of undetermined significance) for 7% samples. When only samples without recent abnormalities were taken into account, 24% tested positive on cobas, 19% on HC2, and 5...

  20. Experimental-calculation technique for Ksub(IC) determination using the samples of decreased dimensions

    International Nuclear Information System (INIS)

    Vinokurov, V.A.; Dymshits, A.V.; Pirusskij, M.V.; Ovsyannikov, B.M.; Kononov, V.V.

    1981-01-01

    A possibility to decrease the size of samples, which is necessary for the reliable determination of fractUre toughness Ksub(1c), is established. The dependences of crack-resistance caracteristics on the sample dimensions are determined experimentally. The static bending tests are made using the 1251 model of ''Instron'' installation with a specially designed device. The samples of the 20KhNMF steel have been tested. It is shown that the Ksub(1c) value, determined for the samples with the largest netto cross section (50x100 rm), is considerably lower than Ksub(1c) values, determined for the samples with the decreased sizes. it is shown that the developed experimental-calculated method of Ksub(1c) determination can be practically used for the samples of the decreased sizes with the introduction of the corresponding amendment coefficient [ru

  1. Path Creation, Path Dependence and Breaking Away from the Path

    OpenAIRE

    Wang, Jens; Hedman, Jonas; Tuunainen, Virpi Kristiina

    2016-01-01

    The explanation of how and why firms succeed or fail is a recurrent research challenge. This is particularly important in the context of technological innovations. We focus on the role of historical events and decisions in explaining such success and failure. Using a case study of Nokia, we develop and extend a multi-layer path dependence framework. We identify four layers of path dependence: technical, strategic and leadership, organizational, and external collaboration. We show how path dep...

  2. Electromembrane extraction as a rapid and selective miniaturized sample preparation technique for biological fluids

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Pedersen-Bjergaard, Stig; Seip, Knut Fredrik

    2015-01-01

    This special report discusses the sample preparation method electromembrane extraction, which was introduced in 2006 as a rapid and selective miniaturized extraction method. The extraction principle is based on isolation of charged analytes extracted from an aqueous sample, across a thin film....... Technical aspects of electromembrane extraction, important extraction parameters as well as a handful of examples of applications from different biological samples and bioanalytical areas are discussed in the paper....

  3. Demonstrating Reliable High Level Waste Slurry Sampling Techniques to Support Hanford Waste Processing

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Steven E.

    2013-11-11

    The Hanford Tank Operations Contractor (TOC) and the Hanford Waste Treatment and Immobilization Plant (WTP) contractor are both engaged in demonstrating mixing, sampling, and transfer system capability using simulated Hanford High-Level Waste (HL W) formulations. This work represents one of the remaining technical issues with the high-level waste treatment mission at Hanford. The TOC must demonstrate the ability to adequately mix and sample high-level waste feed to meet the WTP Waste Acceptance Criteria and Data Quality Objectives. The sampling method employed must support both TOC and WTP requirements. To facilitate information transfer between the two facilities the mixing and sampling demonstrations are led by the One System Integrated Project Team. The One System team, Waste Feed Delivery Mixing and Sampling Program, has developed a full scale sampling loop to demonstrate sampler capability. This paper discusses the full scale sampling loops ability to meet precision and accuracy requirements, including lessons learned during testing. Results of the testing showed that the Isolok(R) sampler chosen for implementation provides precise, repeatable results. The Isolok(R) sampler accuracy as tested did not meet test success criteria. Review of test data and the test platform following testing by a sampling expert identified several issues regarding the sampler used to provide reference material used to judge the Isolok's accuracy. Recommendations were made to obtain new data to evaluate the sampler's accuracy utilizing a reference sampler that follows good sampling protocol.

  4. Demonstrating Reliable High Level Waste Slurry Sampling Techniques to Support Hanford Waste Processing

    International Nuclear Information System (INIS)

    Kelly, Steven E.

    2013-01-01

    The Hanford Tank Operations Contractor (TOC) and the Hanford Waste Treatment and Immobilization Plant (WTP) contractor are both engaged in demonstrating mixing, sampling, and transfer system capability using simulated Hanford High-Level Waste (HL W) formulations. This work represents one of the remaining technical issues with the high-level waste treatment mission at Hanford. The TOC must demonstrate the ability to adequately mix and sample high-level waste feed to meet the WTP Waste Acceptance Criteria and Data Quality Objectives. The sampling method employed must support both TOC and WTP requirements. To facilitate information transfer between the two facilities the mixing and sampling demonstrations are led by the One System Integrated Project Team. The One System team, Waste Feed Delivery Mixing and Sampling Program, has developed a full scale sampling loop to demonstrate sampler capability. This paper discusses the full scale sampling loops ability to meet precision and accuracy requirements, including lessons learned during testing. Results of the testing showed that the Isolok(R) sampler chosen for implementation provides precise, repeatable results. The Isolok(R) sampler accuracy as tested did not meet test success criteria. Review of test data and the test platform following testing by a sampling expert identified several issues regarding the sampler used to provide reference material used to judge the Isolok's accuracy. Recommendations were made to obtain new data to evaluate the sampler's accuracy utilizing a reference sampler that follows good sampling protocol

  5. Behavioural sampling techniques and activity pattern of Indian Pangolin Manis crassicaudata (Mammalia: Manidae in captivity

    Directory of Open Access Journals (Sweden)

    R.K. Mohapatra

    2013-12-01

    Full Text Available The study presents data on six Indian Pangolins Manis crassicaudata observed in captivity at the Pangolin Conservation Breeding Centre, Nandankanan, Odisha, India over 1377 hours of video recordings for each pangolin between 1500hr and 0800hr on 81 consecutive observational days. Video recordings were made through digital systems assisted by infrared enabled CCTV cameras. The data highlights patterns relate to 12 different behaviour and enclosure utilization. Different interval periods for sampling of instantaneous behaviour from video recordings have been evaluated to develop optimal study methods for the future. The activity budgets of pangolins displayed natural patterns of nocturnal activity with a peak between 20:00-21:00 hr. When out of their burrow, they spent about 59% of the time walking in the enclosure, and 14% of the time feeding. The repeatability of the behaviours has a significant negative correlation with the mean time spent in that behaviour. Focal behavioural samples significantly correlated with instantaneous samples up to 15 minutes interval. The correlation values gradually decreased with the increase in sampling interval. The results indicate that results obtained from focal sampling and instantaneous sampling with relatively shorter intervals (=5 minutes are about equally reliable. The study suggests use of focal sampling, instead of instantaneous sampling to record behaviour relating to social interactions.

  6. Analysis of techniques of sample attack for soil and mineral analysis

    International Nuclear Information System (INIS)

    Dean, J.R.; Chiu, N.W.

    1985-05-01

    Four methods of sample attack were evaluated in the laboratory for use in the determination of uranium, radium-226, thorium-232, thorium-230, thorium-228, and lead-210. The methods evaluated were (1) KF/pyrosulfate fusion; (2) Sodium carbonate fusion; (3) Nitric, perchloric, hydrofluoric acid digestion; and, (4) combination nitric, perchloric, hydrofluoric acid/pyrosulfate fusion. Five samples were chosen for evaluation; two were mine tailings from Bancroft, Ontario and Beaverlodge, Saskatchewan, one was a synthetic uranium ore-silica mixture and two were soil samples supplied by AECB. The KF/pyrosulfate dissolution procedure was found to be the fastest and, overall, most accurate dissolution method for the analysis of 1-20 samples. For larger numbers of samples the three acid/pyrosulfate fusion combination was shown to have some merit

  7. Uranium, radium and radon exhalation study in some soil samples using track etch technique

    International Nuclear Information System (INIS)

    Harmanjit, Singh; Joga, Singh; Surinder, Singh; Bajwa, B.S.

    2006-01-01

    Full text of publication follows: Uranium, radium concentration and radon exhalation rates have been determined in the soil samples collected from some areas of Punjab using the L.R.-115 nuclear track detectors. Radium concentration in these samples has been found to be varying from 0.80 to 5.34 Bq Kg-1. The radon exhalation rate in these samples has been found to be varying from 0.99 to 6.60 mBq Kg -1 h -1 (32.82 to 218.49 mBqm -2 h -1 ). A good correlation has been observed between radon exhalation rate and radium concentration observed in the soil samples. The uranium concentration in all these samples is being carried out and the other correlations will also be established. (authors)

  8. Evaluation of oxidation techniques for preparing bioassay and environmental samples for liquid scintillation counting

    International Nuclear Information System (INIS)

    Miller, H.H.

    1979-10-01

    In environmental and biological monitoring for carbon-14 and tritium, the presence of color and chemical quenching agents in the samples can degrade the efficiency of liquid scintillation counting. A series of experiments was performed to evaluate the usefulness, under routine conditions, of first oxidizing the samples to improve the counting by removing the color and quenching agents. The scintillation counter was calibrated for the effects of quenching agents on its counting efficiency. Oxidizing apparatus was tested for its ability to accurately recover the 14 C and 3 H in the samples. Scintillation counting efficiences were compared for a variety of oxidized and unoxidized environmental and bioassay samples. The overall conclusion was that, for routine counting, oxidation of such samples is advantageous when they are highly quenched or in solid form

  9. Percutaneous CT-guided sacroiliac joint sampling for infection: aspiration, biopsy, and technique.

    Science.gov (United States)

    Knipp, David; Simeone, F Joseph; Nelson, Sandra B; Huang, Ambrose J; Chang, Connie Y

    2018-04-01

    To evaluate methods of CT-guided sacroiliac joint sampling in patients with suspected infection. All CT-guided sacroiliac joint sampling procedures for suspected infection were reviewed for sampling type (aspiration, lavage aspiration, biopsy), microbiology results, and clinical and imaging follow-up. The primary gold standard was anatomic pathology. If pathology was not available, then positive blood culture with the same organism as SIJ sampling, imaging and clinical follow-up, or clinical follow-up only were used. Anterior and posterior joint distention was evaluated by MRI within 7 days of the procedure. A total of 34 patients (age 39 ± 20 (range, 6-75) years; 21 F, 13 M) were included. Aspiration samples only were obtained in 13/34 (38%) cases, biopsy samples only in 9/34 (26%) cases, and both samples in 12/34 (35%) cases. There was an overall 54% sensitivity and 86% specificity. For the aspiration samples, sensitivity and specificity were 60 and 81%, respectively, compared to 45 and 90% for the biopsy samples. In cases with both samples, biopsy did not add additional microbial information. Seventeen (17/34, 50%) patients had an MRI. The anterior joint was more distended than the posterior joint in 15/17 (88%) of patients, and this difference was significant (P = 0.0003). All of these 17 patients had an attempted aspiration by a posterior approach; 6/17 (35%) resulted in a successful aspiration. Aspiration of the sacroiliac joint has a higher sensitivity than biopsy and should always be attempted first. MRI may be helpful for procedure planning.

  10. Percutaneous CT-guided sacroiliac joint sampling for infection. Aspiration, biopsy, and technique

    Energy Technology Data Exchange (ETDEWEB)

    Knipp, David; Simeone, F.J.; Huang, Ambrose J.; Chang, Connie Y. [Massachusetts General Hospital, Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States); Nelson, Sandra B. [Massachusetts General Hospital, Infectious Disease Unit, Department of Medicine, Boston, MA (United States)

    2018-04-15

    To evaluate methods of CT-guided sacroiliac joint sampling in patients with suspected infection. All CT-guided sacroiliac joint sampling procedures for suspected infection were reviewed for sampling type (aspiration, lavage aspiration, biopsy), microbiology results, and clinical and imaging follow-up. The primary gold standard was anatomic pathology. If pathology was not available, then positive blood culture with the same organism as SIJ sampling, imaging and clinical follow-up, or clinical follow-up only were used. Anterior and posterior joint distention was evaluated by MRI within 7 days of the procedure. A total of 34 patients (age 39 ± 20 (range, 6-75) years; 21 F, 13 M) were included. Aspiration samples only were obtained in 13/34 (38%) cases, biopsy samples only in 9/34 (26%) cases, and both samples in 12/34 (35%) cases. There was an overall 54% sensitivity and 86% specificity. For the aspiration samples, sensitivity and specificity were 60 and 81%, respectively, compared to 45 and 90% for the biopsy samples. In cases with both samples, biopsy did not add additional microbial information. Seventeen (17/34, 50%) patients had an MRI. The anterior joint was more distended than the posterior joint in 15/17 (88%) of patients, and this difference was significant (P = 0.0003). All of these 17 patients had an attempted aspiration by a posterior approach; 6/17 (35%) resulted in a successful aspiration. Aspiration of the sacroiliac joint has a higher sensitivity than biopsy and should always be attempted first. MRI may be helpful for procedure planning. (orig.)

  11. New Equipment and Techniques for Remote Sampling of Stored Radioactive Waste

    International Nuclear Information System (INIS)

    Nance, T.A.

    2001-01-01

    Radioactive waste is stored at the Savannah River Site (SRS), part of the Department of Energy (DOE) complex. This radioactive waste is stored in buried tanks and management of the waste requires several processes, including material addition, heating, cooling, mixing, and transfer from tank to tank. During waste processing, it is necessary to know the chemical components and their characteristics to determine the steps necessary to maintain the waste form or to manipulate the waste into the form desired. Waste characterization begins by obtaining a sample for analysis. High level radioactive waste sampling is routinely done with simple, standard samplers such as a dip sample. Other sampling is non-routine or specialized, with unique, special requirements, such as sampling remote areas that are difficult to reach. Other specialized sampling includes sampling materials with unknown characteristics or material that must be gathered to obtain an adequate sample or materials that must be broken up to sample or forcibly separated from the tank. The samplers described in this paper are specialized samplers. These samplers include the Dip Filter Sampler, Soft Core Sampler, Hard Core Sampler, Circle Scrape Sampler, Small Scrape Sampler, Suction and Strain Sampler, and Vial Snapper Sampler. The Dip Filter Sampler is used to sample floating particulate matter or floating organic matter. The Soft Core Sampler and Hard Core Sampler are used to obtain samples of solids from the tank floor. The Soft Core Sampler is used on soft solids such as sludge and saltcake and the Hard Core Sampler on hardened solid deposits. The Circle Scrape Sampler is used to obtain solid samples through a small entry riser and out from under the riser. The Small Scrape Sampler enters a small entry riser and is used to scrape a sample from the tank wall. The Suction and Strain Sampler is used to gather a remote submerged sample or filter a solid sample from supernate. The Vial Snapper Grab Sampler is

  12. Optimal Paths in Gliding Flight

    Science.gov (United States)

    Wolek, Artur

    Underwater gliders are robust and long endurance ocean sampling platforms that are increasingly being deployed in coastal regions. This new environment is characterized by shallow waters and significant currents that can challenge the mobility of these efficient (but traditionally slow moving) vehicles. This dissertation aims to improve the performance of shallow water underwater gliders through path planning. The path planning problem is formulated for a dynamic particle (or "kinematic car") model. The objective is to identify the path which satisfies specified boundary conditions and minimizes a particular cost. Several cost functions are considered. The problem is addressed using optimal control theory. The length scales of interest for path planning are within a few turn radii. First, an approach is developed for planning minimum-time paths, for a fixed speed glider, that are sub-optimal but are guaranteed to be feasible in the presence of unknown time-varying currents. Next the minimum-time problem for a glider with speed controls, that may vary between the stall speed and the maximum speed, is solved. Last, optimal paths that minimize change in depth (equivalently, maximize range) are investigated. Recognizing that path planning alone cannot overcome all of the challenges associated with significant currents and shallow waters, the design of a novel underwater glider with improved capabilities is explored. A glider with a pneumatic buoyancy engine (allowing large, rapid buoyancy changes) and a cylindrical moving mass mechanism (generating large pitch and roll moments) is designed, manufactured, and tested to demonstrate potential improvements in speed and maneuverability.

  13. Advanced sampling techniques for hand-held FT-IR instrumentation

    Science.gov (United States)

    Arnó, Josep; Frunzi, Michael; Weber, Chris; Levy, Dustin

    2013-05-01

    FT-IR spectroscopy is the technology of choice to identify solid and liquid phase unknown samples. The challenging ConOps in emergency response and military field applications require a significant redesign of the stationary FT-IR bench-top instruments typically used in laboratories. Specifically, field portable units require high levels of resistance against mechanical shock and chemical attack, ease of use in restrictive gear, extreme reliability, quick and easy interpretation of results, and reduced size. In the last 20 years, FT-IR instruments have been re-engineered to fit in small suitcases for field portable use and recently further miniaturized for handheld operation. This article introduces the HazMatID™ Elite, a FT-IR instrument designed to balance the portability advantages of a handheld device with the performance challenges associated with miniaturization. In this paper, special focus will be given to the HazMatID Elite's sampling interfaces optimized to collect and interrogate different types of samples: accumulated material using the on-board ATR press, dispersed powders using the ClearSampler™ tool, and the touch-to-sample sensor for direct liquid sampling. The application of the novel sample swipe accessory (ClearSampler) to collect material from surfaces will be discussed in some detail. The accessory was tested and evaluated for the detection of explosive residues before and after detonation. Experimental results derived from these investigations will be described in an effort to outline the advantages of this technology over existing sampling methods.

  14. Geospatial techniques for developing a sampling frame of watersheds across a region

    Science.gov (United States)

    Gresswell, Robert E.; Bateman, Douglas S.; Lienkaemper, George; Guy, T.J.

    2004-01-01

    Current land-management decisions that affect the persistence of native salmonids are often influenced by studies of individual sites that are selected based on judgment and convenience. Although this approach is useful for some purposes, extrapolating results to areas that were not sampled is statistically inappropriate because the sampling design is usually biased. Therefore, in recent investigations of coastal cutthroat trout (Oncorhynchus clarki clarki) located above natural barriers to anadromous salmonids, we used a methodology for extending the statistical scope of inference. The purpose of this paper is to apply geospatial tools to identify a population of watersheds and develop a probability-based sampling design for coastal cutthroat trout in western Oregon, USA. The population of mid-size watersheds (500-5800 ha) west of the Cascade Range divide was derived from watershed delineations based on digital elevation models. Because a database with locations of isolated populations of coastal cutthroat trout did not exist, a sampling frame of isolated watersheds containing cutthroat trout had to be developed. After the sampling frame of watersheds was established, isolated watersheds with coastal cutthroat trout were stratified by ecoregion and erosion potential based on dominant bedrock lithology (i.e., sedimentary and igneous). A stratified random sample of 60 watersheds was selected with proportional allocation in each stratum. By comparing watershed drainage areas of streams in the general population to those in the sampling frame and the resulting sample (n = 60), we were able to evaluate the how representative the subset of watersheds was in relation to the population of watersheds. Geospatial tools provided a relatively inexpensive means to generate the information necessary to develop a statistically robust, probability-based sampling design.

  15. Effect of DNA extraction methods and sampling techniques on the apparent structure of cow and sheep rumen microbial communities.

    Directory of Open Access Journals (Sweden)

    Gemma Henderson

    Full Text Available Molecular microbial ecology techniques are widely used to study the composition of the rumen microbiota and to increase understanding of the roles they play. Therefore, sampling and DNA extraction methods that result in adequate yields of microbial DNA that also accurately represents the microbial community are crucial. Fifteen different methods were used to extract DNA from cow and sheep rumen samples. The DNA yield and quality, and its suitability for downstream PCR amplifications varied considerably, depending on the DNA extraction method used. DNA extracts from nine extraction methods that passed these first quality criteria were evaluated further by quantitative PCR enumeration of microbial marker loci. Absolute microbial numbers, determined on the same rumen samples, differed by more than 100-fold, depending on the DNA extraction method used. The apparent compositions of the archaeal, bacterial, ciliate protozoal, and fungal communities in identical rumen samples were assessed using 454 Titanium pyrosequencing. Significant differences in microbial community composition were observed between extraction methods, for example in the relative abundances of members of the phyla Bacteroidetes and Firmicutes. Microbial communities in parallel samples collected from cows by oral stomach-tubing or through a rumen fistula, and in liquid and solid rumen digesta fractions, were compared using one of the DNA extraction methods. Community representations were generally similar, regardless of the rumen sampling technique used, but significant differences in the abundances of some microbial taxa such as the Clostridiales and the Methanobrevibacter ruminantium clade were observed. The apparent microbial community composition differed between rumen sample fractions, and Prevotellaceae were most abundant in the liquid fraction. DNA extraction methods that involved phenol-chloroform extraction and mechanical lysis steps tended to be more comparable. However

  16. Evaluation of alternative macroinvertebrate sampling techniques for use in a new tropical freshwater bioassessment scheme

    Directory of Open Access Journals (Sweden)

    Isabel Eleanor Moore

    2015-06-01

    Full Text Available Aim: The study aimed to determine the effectiveness of benthic macroinvertebrate dredge net sampling procedures as an alternative method to kick net sampling in tropical freshwater systems, specifically as an evaluation of sampling methods used in the Zambian Invertebrate Scoring System (ZISS river bioassessment scheme. Tropical freshwater ecosystems are sometimes dangerous or inaccessible to sampling teams using traditional kick-sampling methods, so identifying an alternative procedure that produces similar results is necessary in order to collect data from a wide variety of habitats.MethodsBoth kick and dredge nets were used to collect macroinvertebrate samples at 16 riverine sites in Zambia, ranging from backwaters and floodplain lagoons to fast flowing streams and rivers. The data were used to calculate ZISS, diversity (S: number of taxa present, and Average Score Per Taxon (ASPT scores per site, using the two sampling methods to compare their sampling effectiveness. Environmental parameters, namely pH, conductivity, underwater photosynthetically active radiation (PAR, temperature, alkalinity, flow, and altitude, were also recorded and used in statistical analysis. Invertebrate communities present at the sample sites were determined using multivariate procedures.ResultsAnalysis of the invertebrate community and environmental data suggested that the testing exercise was undertaken in four distinct macroinvertebrate community types, supporting at least two quite different macroinvertebrate assemblages, and showing significant differences in habitat conditions. Significant correlations were found for all three bioassessment score variables between results acquired using the two methods, with dredge-sampling normally producing lower scores than did the kick net procedures. Linear regression models were produced in order to correct each biological variable score collected by a dredge net to a score similar to that of one collected by kick net

  17. Dosimetric characterization of BeO samples in alpha, beta and X radiation beams using luminescent techniques

    International Nuclear Information System (INIS)

    Groppo, Daniela Piai

    2013-01-01

    In the medical field, the ionizing radiation is used both for therapeutic and diagnostic purposes, in a wide range of radiation doses. In order to ensure that the objective is achieved in practice, detailed studies of detectors and devices in different types of radiations beams are necessary. In this work a dosimetric characterization of BeO samples was performed using the techniques of thermoluminescence (TL) and optically stimulated luminescence (OSL) by a comparison of their response for alpha, beta and X radiations and the establishment of an appropriated system for use in monitoring of these radiations beams. The main results are: the high sensitivity to beta radiation for both techniques, good reproducibility of TL and OSL response (coefficients of variation lower than 5%), maximum energy dependence of the X radiation of 28% for the TL technique, and only 7% for the OSL technique, within the studied energy range. The dosimetric characteristics obtained in this work show the possibility of applying BeO samples to dosimetry of alpha, beta and X radiations, considering the studied dose ranges, using the TL and OSL techniques. From the results obtained, the samples of BeO showed their potential use for beam dosimetry in diagnostic radiology and radiotherapy. (author)

  18. An evaluation of sampling methods and supporting techniques for tackling lead in drinking water in Aberta Province

    Science.gov (United States)

    A collaborative project commenced in August 2013 with the aim of demonstrating a range of techniques that can be used in tackling the problems of lead in drinking water. The main project was completed in March 2014, with supplementary sampling exercises in mid-2014. It involved t...

  19. The alkali halide disk technique in infra-red spectrometry : Anomalous behaviour of some samples dispersed in alkali halide disks

    NARCIS (Netherlands)

    Tolk, A.

    1961-01-01

    Some difficulties encountered in the application of the alkali halide disk technique in infra-red spectrometry are discussed. Complications due to interaction of the sample with the alkali halide have been studied experimentally. It was found that the anomalous behaviour of benzoic acid, succinic

  20. A Comparative Evaluation of the Effect of Double Casting Technique Using Functionally Generated Path and Conventional Single Casting with Respect to Functional Articulation, Patient Satisfaction and Chair Side Time, in Single Unit Molar Teeth: An In Vivo Study.

    Science.gov (United States)

    Memon, Sarfaraz

    2014-12-01

    A stable centric occlusal position that shows no evidence of occlusal disease should not be altered. Confirmative restorative dentistry deals with making restorations that are in harmony with existing jaw relations. Conventional techniques for construction have been unsuccessful in producing a prosthesis that can be inserted without minor intraoral occlusal adjustment. This study was conducted to evaluate the benefits of the double casting technique with FGP over the conventional casting technique. Ten patients with root canal treated maxillary molar were selected for the fabrication of metal crown. Two techniques, one involving the conventional fabrication and other using functionally generated path with double casting were used to fabricate the prosthesis. A comparison based on various parameters which was done between the two techniques. The change in the height of castings for the double casting group was less compared to the conventional group and was highly statistically significant (P casting group than the conventional group (P casting group compared to conventional (P casting technique resulted in castings which had better dimensional accuracy, less occlusal correction and better patient satisfaction compared to the conventional castings.

  1. Green Aspects of Techniques for the Determination of Currently Used Pesticides in Environmental Samples

    OpenAIRE

    Maciej Tankiewicz; Jacek Namieśnik; Jolanta Stocka; Marek Biziuk

    2011-01-01

    Pesticides are among the most dangerous environmental pollutants because of their stability, mobility and long-term effects on living organisms. Their presence in the environment is a particular danger. It is therefore crucial to monitor pesticide residues using all available analytical methods. The analysis of environmental samples for the presence of pesticides is very difficult: the processes involved in sample preparation are labor-intensive and time-consuming. To date, it has been standa...

  2. Sample Preparation for Determination of Biological Thiols by Liquid Chromatography and Electromigration Techniques

    OpenAIRE

    Bald, Edward

    2004-01-01

    Wydrukowano z dostarczonych Wydawnictwu UŁ gotowych materiałów Majority of the bioanalytical or environmental methods do not use just one chromatografie or electrophoretic step, but rather involve several sample pretreatment steps which simplfy the matrix, and often preconcentrate and chemically modify the analytes. This work surveys typical procedures for sample preparation for most commonly analyzed biofluids with particular emphasis placed on chemical derivatization of su...

  3. A novel fluorescent in situ hybridization technique for detection of Rickettsia spp. in archival samples

    DEFF Research Database (Denmark)

    Svendsen, Claus Bo; Boye, Mette; Struve, Carsten

    2009-01-01

    A novel, sensitive and specific method for detecting Rickettsia spp. in archival samples is described. The method involves the use of fluorescently marked oligonucleotide probes for in situ hybridization. Specific hybridization of Ricekttsia was found without problems of cross-reactions with bact......A novel, sensitive and specific method for detecting Rickettsia spp. in archival samples is described. The method involves the use of fluorescently marked oligonucleotide probes for in situ hybridization. Specific hybridization of Ricekttsia was found without problems of cross...

  4. Internal Stress Distribution Measurement of TIG Welded SUS304 Samples Using Neutron Diffraction Technique

    Science.gov (United States)

    Muslih, M. Refai; Sumirat, I.; Sairun; Purwanta

    2008-03-01

    The distribution of residual stress of SUS304 samples that were undergone TIG welding process with four different electric currents has been measured. The welding has been done in the middle part of the samples that was previously grooved by milling machine. Before they were welded the samples were annealed at 650 degree Celsius for one hour. The annealing process was done to eliminate residual stress generated by grooving process so that the residual stress within the samples was merely produced from welding process. The calculation of distribution of residual stress was carried out by measuring the strains within crystal planes of Fe(220) SUS304. Strain, Young modulus, and Poisson ratio of Fe(220) SUS304 were measured using DN1-M neutron diffractometer. Young modulus and Poisson ratio of Fe(220) SUS304 sample were measured in-situ. The result of calculations showed that distribution of residual stress of SUS304 in the vicinity of welded area is influenced both by treatments given at the samples-making process and by the electric current used during welding process.

  5. Temporal and social contexts of heroin-using populations. An illustration of the snowball sampling technique.

    Science.gov (United States)

    Kaplan, C D; Korf, D; Sterk, C

    1987-09-01

    Snowball sampling is a method that has been used in the social sciences to study sensitive topics, rare traits, personal networks, and social relationships. The method involves the selection of samples utilizing "insider" knowledge and referral chains among subjects who possess common traits that are of research interest. It is especially useful in generating samples for which clinical sampling frames may be difficult to obtain or are biased in some way. In this paper, snowball samples of heroin users in two Dutch cities have been analyzed for the purpose of providing descriptions and limited inferences about the temporal and social contexts of their lifestyles. Two distinct heroin-using populations have been discovered who are distinguished by their life cycle stage. Significant contextual explanations have been found involving the passage from adolescent peer group to criminal occupation, the functioning of network "knots" and "outcroppings," and the frequency of social contact. It is suggested that the snowball sampling method may have utility in studying the temporal and social contexts of other populations of clinical interest.

  6. Detection of Chlamydophila psittaci from feral pigeons in environmental samples: problems with currently available techniques.

    Science.gov (United States)

    Geigenfeind, Ila; Haag-Wackernagel, Daniel

    2010-03-01

    Chlamydophila psittaci (Lillie, 1930) Everett et al., 1999, the pathogenic agent of human ornithosis, is widespread in feral pigeon populations and many cases of transmission from feral pigeons to humans have been reported. The aim of the present study was to detect C. psittaci in environmental samples to find out more about possible transmission routes and, therefore, to assess the zoonotic risk for humans. Fecal samples were collected from nest boxes in a feral pigeon loft. Additionally, samples were taken from the feather dust film covering the water surface of public fountains where pigeons regularly bathe. The samples were tested for the presence of chlamydial antigen using an antigen enzyme-linked immunosorbent assay to prove shedding of C. psittaci by feral pigeons. This test detects a genus specific lipopolysaccharide in the outer membrane of the chlamydial bacteria. Samples were tested using the IDEIA PCE Chlamydia Test kit (DakoCytomation) and positive results were verified with IDEIA Chlamydia Blocking Reagents (DakoCytomation). The IDEIA PCE Chlamydia Test yields a high proportion of positive results. However, when IDEIA Chlamydia Blocking was performed, most of the positive results turned out to be negative or could not be interpreted. We conclude that antigen-enzyme-linked immunosorbent assay tests are not suitable for detecting C. psittaci in environmental samples. Previous publications where no blocking test was used should be reconsidered critically. © 2010 ISZS, Blackwell Publishing and IOZ/CAS.

  7. An orientation-space super sampling technique for six-dimensional diffraction contrast tomography

    NARCIS (Netherlands)

    N.R. Viganò (Nicola); K.J. Batenburg (Joost); W. Ludwig (Wolfgang)

    2016-01-01

    textabstractDiffraction contrast tomography (DCT) is an X-ray full-field imaging technique that allows for the non-destructive three-dimensional investigation of polycrystalline materials and the determination of the physical and morphological properties of their crystallographic domains, called

  8. Direct Trace Element Analysis of Liquid Blood Samples by In-Air Ion Beam Analytical Techniques (PIXE-PIGE).

    Science.gov (United States)

    Huszank, Robert; Csedreki, László; Török, Zsófia

    2017-02-07

    There are various liquid materials whose elemental composition is of interest in various fields of science and technology. In many cases, sample preparation or the extraction can be complicated, or it would destroy the original environment before the analysis (for example, in the case of biological samples). However, multielement direct analysis of liquid samples can be realized by an external PIXE-PIGE measurement system. Particle-induced X-ray and gamma-ray emission spectroscopy (PIXE, PIGE) techniques were applied in external (in-air) microbeam configuration for the trace and main element determination of liquid samples. The direct analysis of standard solutions of several metal salts and human blood samples (whole blood, blood serum, blood plasma, and formed elements) was realized. From the blood samples, Na, P, S, Cl, K, Ca, Fe, Cu, Zn, and Br elemental concentrations were determined. The focused and scanned ion beam creates an opportunity to analyze very small volume samples (∼10 μL). As the sample matrix consists of light elements, the analysis is possible at ppm level. Using this external beam setup, it was found that it is possible to determine elemental composition of small-volume liquid samples routinely, while the liquid samples do not require any preparation processes, and thus, they can be analyzed directly. In the case of lower concentrations, the method is also suitable for the analysis (down to even ∼1 ppm level) but with less accuracy and longer measurement times.

  9. Determination of multi-element in marine sediment samples collected in Angola by the k0-NAA technique

    International Nuclear Information System (INIS)

    Teixeira, M.C.P.; Ho Manh Dung; Cao Dong Vu; Nguyen Thi Sy; Nguyen Thanh Binh; Vuong Huu Tan

    2006-01-01

    The marine sediment samples were designed to collect in Angola for marine environmental pollution study. The k 0 -standardization method of neutron activation analysis (k 0 -NAA) on Dalat research reactor has been developed to determine of multi-element in the Angola marine sediment samples. The samples were irradiated in cell 7-1 for short- and middle-lived nuclides and rotary specimen rack for long-lived nuclides. The irradiation facilities were characterized for neutron spectrum parameters and post-activated samples were measured on the calibrated gamma-ray spectrometers using HPGe detectors. The analytical results for 9 marine sediment samples with 27 elements: Al, As, Br, Ca, Ce,Cl, Co, Cs, Dy, Fe, Hf, I, K, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Th, Ti, U, V and Zn in term of mean concentration, standard deviation and their content range are shown in the report. The analytical quality assurance was done by analysis of a Japan's certified reference material namely marine sediment NMIJ-CRM-7302a. These preliminary results revealed that the k 0 -NAA technique on the Dalat research reactor is a good analytical technique for determination of multi-element in the marine sediment samples. Some heavy metals and trace elements determined in this work possibly connected to the human activities at the sampling region. (author)

  10. Extraction of Plutonium From Spiked INEEL Soil Samples Using the Ligand-Assisted Supercritical Fluid Extraction (LA-SFE) Technique

    International Nuclear Information System (INIS)

    Fox, R.V.; Mincher, B.J.; Holmes, R.G.G.

    1999-01-01

    In order to investigate the effectiveness of ligand-assisted supercritical fluid extraction for the removal of transuranic contaminations from soils an Idaho National Engineering and Environmental Laboratory (INEEL) silty-clay soil sample was obtained from near the Radioactive Waste Management Complex area and subjected to three different chemical preparations before being spiked with plutonium. The spiked INEEL soil samples were subjected to a sequential aqueous extraction procedure to determine radionuclide portioning in each sample. Results from those extractions demonstrate that plutonium consistently partitioned into the residual fraction across all three INEEL soil preparations whereas americium partitioned 73% into the iron/manganese fraction for soil preparation A, with the balance partitioning into the residual fraction. Plutonium and americium were extracted from the INEEL soil samples using a ligand-assisted supercritical fluid extraction technique. Initial supercritical fluid extraction runs produced plutonium extraction technique. Initial supercritical fluid extraction runs produced plutonium extraction efficiencies ranging from 14% to 19%. After a second round wherein the initial extraction parameters were changed, the plutonium extraction efficiencies increased to 60% and as high as 80% with the americium level in the post-extracted soil samples dropping near to the detection limits. The third round of experiments are currently underway. These results demonstrate that the ligand-assisted supercritical fluid extraction technique can effectively extract plutonium from the spiked INEEL soil preparations

  11. Provenance validation of polished rice samples using nuclear and isotopic analytical techniques

    International Nuclear Information System (INIS)

    Pabroa, P.C.B.; Sucgang, R.J.; Mendoza, N.D.S.; Ebihara, M.; Peña, M.

    2015-01-01

    Rice (Oryza sativa) has been considered the best staple food among all cereals and is the staple food for over 3 billion people, constituting over half of the world’s population. Elemental and isotopic analysis revealed variance between Philippine and Japanese rice. Rice samples collected in Japan and in the Philippines (market survey samples from Metro Manila, and farm harvests from Aklan province and Central Luzon) were washed, dried and ground to fine powder. Elemental analyses of the samples were carried out using instrumental neutron activation analysis (INAA) while isotopic signatures of the samples were determined using the isotope ratio mass spectrometry (IRMS). Results show that compared with the unpolished rice standard NIES CRM10b, the polished Japanese and Philippine rice sampled show reduced concentrations of elements by as much as 1/10. 1/4 , 1/5 and 1/3 for Mg, Mn, K and Na, respectively. Levels of Ca and Zn are not greatly affected. Arsenic, probably introduced from fertilizers used in rice fields is found in all the Japanese rice tested at an average concentration of 0.103 μg/g and three out of four of the Philippine rice at an average concentration of 0.70μg/g. Higher levels of Br seen in two of the Philippine rice at 14 and 34μg/g indicated probable contamination source from the pesticide methyl bromide during quarantine. Good correlation of isotopic signatures with geographical location of polished, but not for unpolished, rice samples from Central Luzon and Aklan indicated that provenance studies are best done on polished rice samples. Isotopic with of ω’”13C show signature that of a C3 plant with possible narrow distinguishable signature with Japanese rice falling within -27.5 to -28.5 while Philippine rice within -29 to -30. Rice provenance can be ascertained using elemental analysis and isotopic abundance determination as shown by the study.(author)

  12. Trace uranium analysis in geological sample by isotope dilution-alpha spectrometry and comparison with other techniques

    International Nuclear Information System (INIS)

    Shihomatsu, H.M.; Iyer, S.S.

    1988-12-01

    Establishment of uranium determination in geological samples by alpha spectrometric isotope dilution technique using 233 U tracer is described in the present work. The various steps involved in the method namely, preparation of the sample, electrodeposition, alpha spectrometry, isotope dilution, calculation of the concentration and error statistics are discussed in detail. The experimental parameters for the electrodeposition of uranium, like current density, pH concentration of the electrolyte solution, deposition time, electrode distance were all optimised based on the efficiency of the deposition. The total accuracy and precision of the IDAS using 233 U tracer in the determination of uranium in mineral and granite samples were of the order of 1 to 2% for the concentration range of 50-1500 ppm of U. Our results are compared with those obtained by others workers using similar and different techniques. (author) [pt

  13. Clinical application of microsampling versus conventional sampling techniques in the quantitative bioanalysis of antibiotics: a systematic review.

    Science.gov (United States)

    Guerra Valero, Yarmarly C; Wallis, Steven C; Lipman, Jeffrey; Stove, Christophe; Roberts, Jason A; Parker, Suzanne L

    2018-03-01

    Conventional sampling techniques for clinical pharmacokinetic studies often require the removal of large blood volumes from patients. This can result in a physiological or emotional burden, particularly for neonates or pediatric patients. Antibiotic pharmacokinetic studies are typically performed on healthy adults or general ward patients. These may not account for alterations to a patient's pathophysiology and can lead to suboptimal treatment. Microsampling offers an important opportunity for clinical pharmacokinetic studies in vulnerable patient populations, where smaller sample volumes can be collected. This systematic review provides a description of currently available microsampling techniques and an overview of studies reporting the quantitation and validation of antibiotics using microsampling. A comparison of microsampling to conventional sampling in clinical studies is included.

  14. Sampling technique for collection of expired COsub(2) in studies using naturally labelled sup(13)C in calves

    International Nuclear Information System (INIS)

    Chevalier, R.; Pelletier, G.; Gagnon, M.

    1984-01-01

    Natural isotopic labelling of animal metabolic processes presents great advantages over the use of artificially enriched compounds. These advantages include the use of natural diets, low cost and easiness of handling, sampling and disposal. Changes in the sup(13)C/sup(12)C ratio of expired COsub(2) after ingestion of a test meal containing a variable proportion of Csub(3) and/or Csub(4) plant-derived products permits measurements of the immediate oxidation of dietary carbohydrates. A breathing device for collection of expired COsub(2) and purification techniques are described. The breath-sampling device is composed of a polypropylene enclosure and a rubber bag. The rubber bag is blown up by the animal and a sample of the expired gas is transferred to a sampling glass holder in which a vacuum had been previously achieved. Sample purification of expired COsub(2) is done by differential freezing

  15. Elemental analysis of water and soil environmental samples in Tabuk area by neutron capture gamma-ray spectroscopy techniques

    International Nuclear Information System (INIS)

    Al-Aseery, Sh.M.; Alamoudi, Z.; Hassan, A.M.

    2006-01-01

    The prompt and delayed gamma-rays due to neutron capture in the nuclei of the constituent elements of three soil samples and one drinking water sample have been measured. The 252 Cf and 226 Ra/Be isotopic neutron sources are used for neutron irradiation. Also, the hyper pure germanium detection system is used. The soil samples were from Astra, Tadco and El-Gammaz farms, while the water sample was taken from Tabuk city. In case of prompt gamma-ray analysis, a total of 16 elements were identified and the concentration percentage values by weight were calculated for: C, Na, Mg, Al, Si, S, Cl,, Ca, Ti, Cr, Mn, Fe, Co, Zn, Sr ad Pb elements. A comparative study between the results obtained in this work and the results obtained by ICP-MS and EDX-Ray techniques for the same samples is given

  16. Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Urine Samples by Isotope Ratio Mass Spectrometry

    International Nuclear Information System (INIS)

    2010-01-01

    The IAEA has fostered the more widespread use of a stable isotope technique to assess body composition in different population groups to address priority areas in public health nutrition in Member States. It has done this by supporting national and regional nutrition projects through its technical cooperation programme and coordinated research projects over many years. This publication was developed by an international group of experts to provide practical hands-on guidance in the use of this technique in settings where analysis of stable isotope ratios in biological samples is to be made by isotope ratio mass spectrometry. The publication is targeted at new users of this technique, for example nutritionists, analytical chemists and other professionals. More detailed information on the theoretical background and the practical applications of state of the art methodologies to monitor changes in body composition can be found in IAEA Human Health Series No. 3, Assessment of Body Composition and Total Energy Expenditure in Humans by Stable Isotope Techniques

  17. Seasonal comparison of moss bag technique against vertical snow samples for monitoring atmospheric pollution.

    Science.gov (United States)

    Salo, Hanna; Berisha, Anna-Kaisa; Mäkinen, Joni

    2016-03-01

    This is the first study seasonally applying Sphagnum papillosum moss bags and vertical snow samples for monitoring atmospheric pollution. Moss bags, exposed in January, were collected together with snow samples by early March 2012 near the Harjavalta Industrial Park in southwest Finland. Magnetic, chemical, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), K-means clustering, and Tomlinson pollution load index (PLI) data showed parallel spatial trends of pollution dispersal for both materials. Results strengthen previous findings that concentrate and slag handling activities were important (dust) emission sources while the impact from Cu-Ni smelter's pipe remained secondary at closer distances. Statistically significant correlations existed between the variables of snow and moss bags. As a summary, both methods work well for sampling and are efficient pollutant accumulators. Moss bags can be used also in winter conditions and they provide more homogeneous and better controlled sampling method than snow samples. Copyright © 2015. Published by Elsevier B.V.

  18. Fast neutron and gamma-ray transmission technique in mixed samples. MCNP calculations

    International Nuclear Information System (INIS)

    Perez, N.; Padron, I.

    2001-01-01

    In this paper the moisture in sand and also the sulfur content in toluene have been described by using the simultaneous fast neutron/gamma transmission technique (FNGT). Monte Carlo calculations show that it is possible to apply this technique with accelerator-based and isotopic neutron sources in the on-line analysis to perform the product quality control, specifically in the building materials industry and the petroleum one. It has been used particles from a 14MeV neutron generator and also from an Am-Be neutron source. The estimation of optimal system parameters like the efficiency, detection time, hazards and costs were performed in order to compare both neutron sources

  19. Sport Sampling Is Associated With Improved Landing Technique in Youth Athletes.

    Science.gov (United States)

    DiStefano, Lindsay J; Beltz, Eleanor M; Root, Hayley J; Martinez, Jessica C; Houghton, Andrew; Taranto, Nicole; Pearce, Katherine; McConnell, Erin; Muscat, Courtney; Boyle, Steve; Trojian, Thomas H

    Sport sampling is recommended to promote fundamental movement skill acquisition and physical activity. In contrast, sport specialization is associated with musculoskeletal injury risk, burnout, and attrition from sport. There is limited evidence to support the influence of sport sampling on neuromuscular control, which is associated with injury risk, in youth athletes. Athletes who participated in only 1 sport during the previous year would demonstrate higher Landing Error Scoring System (LESS) scores than their counterparts. Cross-sectional study. Level 3. A total of 355 youth athletes (age range, 8-14 years) completed a test session with a jump-landing task, which was evaluated using the LESS. Participants were categorized as single sport (SS) or multisport (MS) based on their self-reported sport participation in the past year. Their duration of sport sampling (low, moderate, high) was determined based on their sport participation history. Participants were dichotomized into good (LESS sampling duration (low, moderate, high). The MS group was 2.5 times (95% CI, 1.9-3.1) as likely to be categorized as having good control compared with the SS group (χ 2 (355) = 10.10, P sampling duration group were 5.8 times (95% CI, 3.1-8.5) and 5.4 times (95% CI, 4.0-6.8) as likely to be categorized as having good control compared with the moderate and low groups (χ 2 (216) = 11.20, P sampling at a young age is associated with improved neuromuscular control, which may reduce injury risk in youth athletes. Youth athletes should be encouraged to try participating in multiple sports to enhance their neuromuscular control and promote long-term physical activity.

  20. Feynman's path integrals and Bohm's particle paths

    International Nuclear Information System (INIS)

    Tumulka, Roderich

    2005-01-01

    Both Bohmian mechanics, a version of quantum mechanics with trajectories, and Feynman's path integral formalism have something to do with particle paths in space and time. The question thus arises how the two ideas relate to each other. In short, the answer is, path integrals provide a re-formulation of Schroedinger's equation, which is half of the defining equations of Bohmian mechanics. I try to give a clear and concise description of the various aspects of the situation. (letters and comments)

  1. Hierarchical sampling of multiple strata: an innovative technique in exposure characterization

    International Nuclear Information System (INIS)

    Ericson, J.E.; Gonzalez, Elisabeth J.

    2003-01-01

    Sampling of multiple strata, or hierarchical sampling of various exposure sources and activity areas, has been tested and is suggested as a method to sample (or to locate) areas with a high prevalence of elevated blood lead in children. Hierarchical sampling was devised to supplement traditional soil lead sampling of a single stratum, either residential or fixed point source, using a multistep strategy. Blood lead (n=1141) and soil lead (n=378) data collected under the USEPA/UCI Tijuana Lead Project (1996-1999) were analyzed to evaluate the usefulness of sampling soil lead from background sites, schools and parks, point sources, and residences. Results revealed that industrial emissions have been a contributing factor to soil lead contamination in Tijuana. At the regional level, point source soil lead was associated with mean blood lead levels and concurrent high background, and point source soil lead levels were predictive of a high percentage of subjects with blood lead equal to or greater than 10 μg/dL (pe 10). Significant relationships were observed between mean blood lead level and fixed point source soil lead (r=0.93; P 2 =0.72 using a quadratic model) and between residential soil lead and fixed point source soil lead (r=0.90; P 2 =0.86 using a cubic model). This study suggests that point sources alone are not sufficient for predicting the relative risk of exposure to lead in the urban environment. These findings will be useful in defining regions for targeted or universal soil lead sampling by site type. Point sources have been observed to be predictive of mean blood lead at the regional level; however, this relationship alone was not sufficient to predict pe 10. It is concluded that when apparently undisturbed sites reveal high soil lead levels in addition to local point sources, dispersion of lead is widespread and will be associated with a high prevalence of elevated blood lead in children. Multiple strata sampling was shown to be useful in

  2. Mercury speciation in environmental solid samples using thermal release technique with atomic absorption detection

    Energy Technology Data Exchange (ETDEWEB)

    Shuvaeva, Olga V. [Institute of Inorganic Chemistry, Academician Lavrent' ev Prospect 3, 630090 Novosbirsk (Russian Federation)], E-mail: olga@che.nsk.su; Gustaytis, Maria A.; Anoshin, Gennadii N. [Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Koptyug Prospect 3, 630090 Novosibirsk (Russian Federation)

    2008-07-28

    A sensitive and very simple method for determination of mercury species in solid samples has been developed involving thermal release analysis in combination with atomic absorption (AAS) detection. The method allows determination of mercury(II) chloride, methylmercury and mercury sulfide at the level of 0.70, 0.35 and 0.20 ng with a reproducibility of the results of 14, 25 and 18%, respectively. The accuracy of the developed assay has been estimated using certified reference materials and by comparison of the results with those of an independent method. The method has been applied for Hg species determination in original samples of lake sediments and plankton.

  3. UMTRA ground water sampling techniques: Comparison of the traditional and low flow methods

    International Nuclear Information System (INIS)

    1995-07-01

    This report describes the potential changes in water quality data that may occur with the conversion from MBV (multiple bore volume) to LF (low flow) sampling and provides two examples of how such a change might impact Project decisions. The existing scientific literature on LF sampling is reviewed and the new LF data from three UMTRA Uranium Mill Tailings Remedial Action Project sites are evaluated seeking answers to the questions posed above. Several possible approaches, that the UMTRA Project may take to address issues unanswered by the literature are presented and compared, and a recommendation is offered for the future direction of the LF conversion effort

  4. Path coupling and aggregate path coupling

    CERN Document Server

    Kovchegov, Yevgeniy

    2018-01-01

    This book describes and characterizes an extension to the classical path coupling method applied to statistical mechanical models, referred to as aggregate path coupling. In conjunction with large deviations estimates, the aggregate path coupling method is used to prove rapid mixing of Glauber dynamics for a large class of statistical mechanical models, including models that exhibit discontinuous phase transitions which have traditionally been more difficult to analyze rigorously. The book shows how the parameter regions for rapid mixing for several classes of statistical mechanical models are derived using the aggregate path coupling method.

  5. SU-F-J-193: Efficient Dose Extinction Method for Water Equivalent Path Length (WEPL) of Real Tissue Samples for Validation of CT HU to Stopping Power Conversion

    International Nuclear Information System (INIS)

    Zhang, R; Baer, E; Jee, K; Sharp, G; Flanz, J; Lu, H

    2016-01-01

    Purpose: For proton therapy, an accurate model of CT HU to relative stopping power (RSP) conversion is essential. In current practice, validation of these models relies solely on measurements of tissue substitutes with standard compositions. Validation based on real tissue samples would be much more direct and can address variations between patients. This study intends to develop an efficient and accurate system based on the concept of dose extinction to measure WEPL and retrieve RSP in biological tissue in large number of types. Methods: A broad AP proton beam delivering a spread out Bragg peak (SOBP) is used to irradiate the samples with a Matrixx detector positioned immediately below. A water tank was placed on top of the samples, with the water level controllable in sub-millimeter by a remotely controlled dosing pump. While gradually lowering the water level with beam on, the transmission dose was recorded at 1 frame/sec. The WEPL were determined as the difference between the known beam range of the delivered SOBP (80%) and the water level corresponding to 80% of measured dose profiles in time. A Gammex 467 phantom was used to test the system and various types of biological tissue was measured. Results: RSP for all Gammex inserts, expect the one made with lung-450 material (<2% error), were determined within ±0.5% error. Depends on the WEPL of investigated phantom, a measurement takes around 10 min, which can be accelerated by a faster pump. Conclusion: Based on the concept of dose extinction, a system was explored to measure WEPL efficiently and accurately for a large number of samples. This allows the validation of CT HU to stopping power conversions based on large number of samples and real tissues. It also allows the assessment of beam uncertainties due to variations over patients, which issue has never been sufficiently studied before.

  6. SU-F-J-193: Efficient Dose Extinction Method for Water Equivalent Path Length (WEPL) of Real Tissue Samples for Validation of CT HU to Stopping Power Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R; Baer, E; Jee, K; Sharp, G; Flanz, J; Lu, H [Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)

    2016-06-15

    Purpose: For proton therapy, an accurate model of CT HU to relative stopping power (RSP) conversion is essential. In current practice, validation of these models relies solely on measurements of tissue substitutes with standard compositions. Validation based on real tissue samples would be much more direct and can address variations between patients. This study intends to develop an efficient and accurate system based on the concept of dose extinction to measure WEPL and retrieve RSP in biological tissue in large number of types. Methods: A broad AP proton beam delivering a spread out Bragg peak (SOBP) is used to irradiate the samples with a Matrixx detector positioned immediately below. A water tank was placed on top of the samples, with the water level controllable in sub-millimeter by a remotely controlled dosing pump. While gradually lowering the water level with beam on, the transmission dose was recorded at 1 frame/sec. The WEPL were determined as the difference between the known beam range of the delivered SOBP (80%) and the water level corresponding to 80% of measured dose profiles in time. A Gammex 467 phantom was used to test the system and various types of biological tissue was measured. Results: RSP for all Gammex inserts, expect the one made with lung-450 material (<2% error), were determined within ±0.5% error. Depends on the WEPL of investigated phantom, a measurement takes around 10 min, which can be accelerated by a faster pump. Conclusion: Based on the concept of dose extinction, a system was explored to measure WEPL efficiently and accurately for a large number of samples. This allows the validation of CT HU to stopping power conversions based on large number of samples and real tissues. It also allows the assessment of beam uncertainties due to variations over patients, which issue has never been sufficiently studied before.

  7. Evaluation of enzyme immunoassay techniques for diagnosis of the most common intestinal protozoa in fecal samples.

    Science.gov (United States)

    Gaafar, Maha R

    2011-08-01

    This study was designed to evaluate the antigen capture enzyme immunoassays (EIAs) Triage parasite panel and TechLab Entamoeba histolytica II in detecting Giardia intestinalis, Cryptosporidium sp, and Entamoeba histolytica in fecal samples in comparison to microscopy, and in differentiating Entamoeba histolytica from Entamoeba dispar. The Triage EIA was evaluated using 100 stool specimens that were tested by standard ova and parasite examination, including staining with both trichrome and modified acid-fast stains. Differentiation between E. histolytica and E. dispar was performed using TechLab. Microscopic examination revealed that 19% of the samples were positive for Giardia, 4% for Cryptosporidium, and 1% for E. histolytica/E. dispar, and other parasites were found in 5%. By Triage, 23% of the samples were infected with Giardia, 5% with Cryptosporidium, and 2% with E. histolytica/E. dispar. Triage showed a sensitivity of 100% and specificity of 91.5%. The TechLab assay was negative for both samples diagnosed as E. histolytica/E. dispar by Triage, which suggested that they were E. dispar. Both tests showed no cross-reactivity with other intestinal protozoa. These results indicate that antigen detection by EIA has the potential to become a valuable tool, capable of making stool diagnostics more effective. Copyright © 2011 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  8. Soil and Water – What is Detectable through Microbiological Sample Preparation Techniques

    Science.gov (United States)

    The concerns of a potential terrorist’s use of biological agents in soil and ground water are articulated by comparisons to major illnesses in this Country involving contaminated drinking water sources. Objectives are focused on the importance of sample preparation in the rapid, ...

  9. Recent trends in sorption-based sample preparation and liquid chromatography techniques for food analysis.

    Science.gov (United States)

    V Soares Maciel, Edvaldo; de Toffoli, Ana Lúcia; Lanças, Fernando Mauro

    2018-04-20

    The accelerated rising of the world's population increased the consumption of food, thus demanding more rigors in the control of residue and contaminants in food-based products marketed for human consumption. In view of the complexity of most food matrices, including fruits, vegetables, different types of meat, beverages, among others, a sample preparation step is important to provide more reliable results when combined with HPLC separations. An adequate sample preparation step before the chromatographic analysis is mandatory in obtaining higher precision and accuracy in order to improve the extraction of the target analytes, one of the priorities in analytical chemistry. The recent discovery of new materials such as ionic liquids, graphene-derived materials, molecularly imprinted polymers, restricted access media, magnetic nanoparticles, and carbonaceous nanomaterials, provided high sensitivity and selectivity results in an extensive variety of applications. These materials, as well as their several possible combinations, have been demonstrated to be highly appropriate for the extraction of different analytes in complex samples such as food products. The main characteristics and application of these new materials in food analysis will be presented and discussed in this paper. Another topic discussed in this review covers the main advantages and limitations of sample preparation microtechniques, as well as their off-line and on-line combination with HPLC for food analysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Stir Bar Sorptive Extraction (SBSE), a novel extraction technique for aqueous samples: theory and principles

    NARCIS (Netherlands)

    Baltussen, H.A.; Sandra, P.J.F.; David, F.; Cramers, C.A.M.G.

    1999-01-01

    The theory and practice of a novel approach for sample enrichment, namely the application of stir bars coated with the sorbent polydimethylsiloxane (PDMS) and referred to as stir bar sorptive extraction (SBSE) are presented. Stir bars with a length of 10 and 40 mm coated with 55 and 219 L of PDMS

  11. Alternative sample-introduction technique to avoid breakthrough in gradient-elution liquid chromatography of polymers

    NARCIS (Netherlands)

    Reingruber, E.; Bedani, F.; Buchberger, W.; Schoenmakers, P.

    2010-01-01

    Gradient-elution liquid chromatography (GELC) is a powerful tool for the characterization of synthetic polymers. However, gradient-elution chromatograms often suffer from breakthrough phenomena. Breakthrough can be averted by using a sample solvent as weak as the mobile phase. However, this approach

  12. Methods and Techniques of Sampling, Culturing and Identifying of Subsurface Bacteria

    International Nuclear Information System (INIS)

    Lee, Seung Yeop; Baik, Min Hoon

    2010-11-01

    This report described sampling, culturing and identifying of KURT underground bacteria, which existed as iron-, manganese-, and sulfate-reducing bacteria. The methods of culturing and media preparation were different by bacteria species affecting bacteria growth-rates. It will be possible for the cultured bacteria to be used for various applied experiments and researches in the future

  13. Environmental gamma-ray measurements using in situ and core sampling techniques

    International Nuclear Information System (INIS)

    Dickson, H.W.; Kerr, G.D.; Perdue, P.T.; Abdullah, S.A.

    1976-01-01

    Dose rates from natural radionuclides and 137 Cs in soils of the Oak Ridge area have been determined from in situ and core sample measurements. In situ γ-ray measurements were made with a transportable spectrometer. A tape of spectral data and a soil core sample from each site were returned to ORNL for further analysis. Information on soil composition, density and moisture content and on the distribution of cesium in the soil was obtained from the core samples. In situ spectra were analyzed by a computer program which identified and assigned energies to peaks, integrated the areas under the peaks, and calculated radionuclide concentrations based on a uniform distribution in the soil. The assumption of a uniform distribution was adequate only for natural radionuclides, but simple corrections can be made to the computer calculations for man-made radionuclides distributed on the surface or exponentially in the soil. For 137 Cs a correction was used based on an exponential function fitted to the distribution measured in core samples. At typical sites in Oak Ridge, the dose rate determined from these measurements was about 5 μrad/hr. (author)

  14. Use of X-ray diffraction technique and chemometrics to aid soil sampling strategies in traceability studies.

    Science.gov (United States)

    Bertacchini, Lucia; Durante, Caterina; Marchetti, Andrea; Sighinolfi, Simona; Silvestri, Michele; Cocchi, Marina

    2012-08-30

    Aim of this work is to assess the potentialities of the X-ray powder diffraction technique as fingerprinting technique, i.e. as a preliminary tool to assess soil samples variability, in terms of geochemical features, in the context of food geographical traceability. A correct approach to sampling procedure is always a critical issue in scientific investigation. In particular, in food geographical traceability studies, where the cause-effect relations between the soil of origin and the final foodstuff is sought, a representative sampling of the territory under investigation is certainly an imperative. This research concerns a pilot study to investigate the field homogeneity with respect to both field extension and sampling depth, taking also into account the seasonal variability. Four Lambrusco production sites of the Modena district were considered. The X-Ray diffraction spectra, collected on the powder of each soil sample, were treated as fingerprint profiles to be deciphered by multivariate and multi-way data analysis, namely PCA and PARAFAC. The differentiation pattern observed in soil samples, as obtained by this fast and non-destructive analytical approach, well matches with the results obtained by characterization with other costly analytical techniques, such as ICP/MS, GFAAS, FAAS, etc. Thus, the proposed approach furnishes a rational basis to reduce the number of soil samples to be collected for further analytical characterization, i.e. metals content, isotopic ratio of radiogenic element, etc., while maintaining an exhaustive description of the investigated production areas. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Correlations Between Life-Detection Techniques and Implications for Sampling Site Selection in Planetary Analog Missions

    Science.gov (United States)

    Gentry, Diana M.; Amador, Elena S.; Cable, Morgan L.; Chaudry, Nosheen; Cullen, Thomas; Jacobsen, Malene B.; Murukesan, Gayathri; Schwieterman, Edward W.; Stevens, Adam H.; Stockton, Amanda; Tan, George; Yin, Chang; Cullen, David C.; Geppert, Wolf

    2017-10-01

    We conducted an analog sampling expedition under simulated mission constraints to areas dominated by basaltic tephra of the Eldfell and Fimmvörðuháls lava fields (Iceland). Sites were selected to be "homogeneous" at a coarse remote sensing resolution (10-100 m) in apparent color, morphology, moisture, and grain size, with best-effort realism in numbers of locations and replicates. Three different biomarker assays (counting of nucleic-acid-stained cells via fluorescent microscopy, a luciferin/luciferase assay for adenosine triphosphate, and quantitative polymerase chain reaction (qPCR) to detect DNA associated with bacteria, archaea, and fungi) were characterized at four nested spatial scales (1 m, 10 m, 100 m, and >1 km) by using five common metrics for sample site representativeness (sample mean variance, group F tests, pairwise t tests, and the distribution-free rank sum H and u tests). Correlations between all assays were characterized with Spearman's rank test. The bioluminescence assay showed the most variance across the sites, followed by qPCR for bacterial and archaeal DNA; these results could not be considered representative at the finest resolution tested (1 m). Cell concentration and fungal DNA also had significant local variation, but they were homogeneous over scales of >1 km. These results show that the selection of life detection assays and the number, distribution, and location of sampling sites in a low biomass environment with limited a priori characterization can yield both contrasting and complementary results, and that their interdependence must be given due consideration to maximize science return in future biomarker sampling expeditions.

  16. Development of spatial scaling technique of forest health sample point information

    Science.gov (United States)

    Lee, J.; Ryu, J.; Choi, Y. Y.; Chung, H. I.; Kim, S. H.; Jeon, S. W.

    2017-12-01

    Most forest health assessments are limited to monitoring sampling sites. The monitoring of forest health in Britain in Britain was carried out mainly on five species (Norway spruce, Sitka spruce, Scots pine, Oak, Beech) Database construction using Oracle database program with density The Forest Health Assessment in GreatBay in the United States was conducted to identify the characteristics of the ecosystem populations of each area based on the evaluation of forest health by tree species, diameter at breast height, water pipe and density in summer and fall of 200. In the case of Korea, in the first evaluation report on forest health vitality, 1000 sample points were placed in the forests using a systematic method of arranging forests at 4Km × 4Km at regular intervals based on an sample point, and 29 items in four categories such as tree health, vegetation, soil, and atmosphere. As mentioned above, existing researches have been done through the monitoring of the survey sample points, and it is difficult to collect information to support customized policies for the regional survey sites. In the case of special forests such as urban forests and major forests, policy and management appropriate to the forest characteristics are needed. Therefore, it is necessary to expand the survey headquarters for diagnosis and evaluation of customized forest health. For this reason, we have constructed a method of spatial scale through the spatial interpolation according to the characteristics of each index of the main sample point table of 29 index in the four points of diagnosis and evaluation report of the first forest health vitality report, PCA statistical analysis and correlative analysis are conducted to construct the indicators with significance, and then weights are selected for each index, and evaluation of forest health is conducted through statistical grading.

  17. The application of statistical and/or non-statistical sampling techniques by internal audit functions in the South African banking industry

    Directory of Open Access Journals (Sweden)

    D.P. van der Nest

    2015-03-01

    Full Text Available This article explores the use by internal audit functions of audit sampling techniques in order to test the effectiveness of controls in the banking sector. The article focuses specifically on the use of statistical and/or non-statistical sampling techniques by internal auditors. The focus of the research for this article was internal audit functions in the banking sector of South Africa. The results discussed in the article indicate that audit sampling is still used frequently as an audit evidence-gathering technique. Non-statistical sampling techniques are used more frequently than statistical sampling techniques for the evaluation of the sample. In addition, both techniques are regarded as important for the determination of the sample size and the selection of the sample items

  18. Composition of atmospheric precipitation. I. Sampling technique. Use of ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Egner, H; Eriksson, E; Emanuelsson, A

    1947-01-01

    In order to investigate the composition of atmospheric precipitations in Sweden, a technique using ion exchange resins has been developed. The possibilities of nitrate reduction, and ammonia losses, when the precipitation is collected in zinc gauges is stressed. Glass funnels are used, and they are effectively protected from bird droppings. The ion exchange resins so far available are quite serviceable but show some deficiencies as to stability, and activity in alkaline solutions. New resins, which are not yet available, seem to offer definite advantages.

  19. Elemental analysis and plant samples at el-Manzala lake by neutron activation analysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Eissa, E A; Rofail, N B; Abdel-Haleem, A S; El-Abbady, W H; Hassan, A M [Arab Republic of Egypt, Atomic energy Authority, Reactor and Neutron Physiscs Department, Cairo (Egypt)

    1996-12-31

    A soil and a plant samples were taken from two locations, Bahr el-Bakar and Bahr Kados at the Manzala lake, where a high pollution is expected. The samples were especially treated and prepared for investigation by thermal neutron activation analysis (NAA). The irradiation facilities of the first egyptian research reactor (ET-R R-1) and the hyper pure germanium (HPGe) detection system were used for such a type of analysis. Among the 34 identified elements Fe, Co, As, Ru, Cd, Te, La, Sm, Eu, Tb, Hg, Th, and U are of a special significance because of their toxic deleterious impact to organisms. This work is a part of a research project concerning pollution studies on the river nile and some lakes of egypt. The data obtained in the present work stand as a reference basic record for any future follow up of the contamination level. 1 tab.

  20. Elemental analysis and plant samples at el-Manzala lake by neutron activation analysis technique

    International Nuclear Information System (INIS)

    Eissa, E.A.; Rofail, N.B.; Abdel-Haleem, A.S.; El-Abbady, W.H.; Hassan, A.M.

    1995-01-01

    A soil and a plant samples were taken from two locations, Bahr el-Bakar and Bahr Kados at the Manzala lake, where a high pollution is expected. The samples were especially treated and prepared for investigation by thermal neutron activation analysis (NAA). The irradiation facilities of the first egyptian research reactor (ET-R R-1) and the hyper pure germanium (HPGe) detection system were used for such a type of analysis. Among the 34 identified elements Fe, Co, As, Ru, Cd, Te, La, Sm, Eu, Tb, Hg, Th, and U are of a special significance because of their toxic deleterious impact to organisms. This work is a part of a research project concerning pollution studies on the river nile and some lakes of egypt. The data obtained in the present work stand as a reference basic record for any future follow up of the contamination level. 1 tab

  1. The Application of Adaptive Sampling and Analysis Program (ASAP) Techniques to NORM Sites; FINAL

    International Nuclear Information System (INIS)

    Johnson, Robert; Smith, Karen P.; Quinn, John

    1999-01-01

    The results from the Michigan demonstration establish that this type of approach can be very effective for NORM sites. The advantages include (1) greatly reduced per sample analytical costs; (2) a reduced reliance on soil sampling and ex situ gamma spectroscopy analyses; (3) the ability to combine characterization with remediation activities in one fieldwork cycle; (4) improved documentation; and (5) ultimately better remediation, as measured by greater precision in delineating soils that are not in compliance with requirements from soils that are in compliance. In addition, the demonstration showed that the use of real-time technologies, such as the RadInSoil, can facilitate the implementation of a Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM)-based final status survey program

  2. Determination of alpha activity produced by Indian tea samples using solid state nuclear track detection technique

    International Nuclear Information System (INIS)

    Azam, Ameer; Naqvi, A.H.; Srivastava, D.S.

    2001-01-01

    India has first place in the world in the production, consumption and export of tea. The average production of tea in India is about 780 million kg annually. Indian population uses tea as a favourite beverage specially with the breakfast. Tea leaves are perennial plants and they have extension root system spread over deeper layers in the soil. Soil contains uranium as trace element. Hence, uranium is transferred to the leaves as a result of uptake from the soil over the years. Since many of the decay products of uranium are alpha emitters hence tea is a source of alpha radioactivity and can cause damaging effects. Therefore, data on alpha activity of tea samples will be useful in estimating these harmful effects at least qualitatively. In the present study the alpha activity produced by thirteen samples of tea available in the local market was measured

  3. Comparison of soil solution sampling techniques to assess metal fluxes from contaminated soil to groundwater.

    Science.gov (United States)

    Coutelot, F; Sappin-Didier, V; Keller, C; Atteia, O

    2014-12-01

    The unsaturated zone plays a major role in elemental fluxes in terrestrial ecosystems. A representative chemical analysis of soil pore water is required for the interpretation of soil chemical phenomena and particularly to assess Trace Elements (TEs) mobility. This requires an optimal sampling system to avoid modification of the extracted soil water chemistry and allow for an accurate estimation of solute fluxes. In this paper, the chemical composition of soil solutions sampled by Rhizon® samplers connected to a standard syringe was compared to two other types of suction probes (Rhizon® + vacuum tube and Rhizon® + diverted flow system). We investigated the effects of different vacuum application procedures on concentrations of spiked elements (Cr, As, Zn) mixed as powder into the first 20 cm of 100-cm columns and non-spiked elements (Ca, Na, Mg) concentrations in two types of columns (SiO2 sand and a mixture of kaolinite + SiO2 sand substrates). Rhizon® was installed at different depths. The metals concentrations showed that (i) in sand, peak concentrations cannot be correctly sampled, thus the flux cannot be estimated, and the errors can easily reach a factor 2; (ii) in sand + clay columns, peak concentrations were larger, indicating that they could be sampled but, due to sorption on clay, it was not possible to compare fluxes at different depths. The different samplers tested were not able to reflect the elemental flux to groundwater and, although the Rhizon® + syringe device was more accurate, the best solution remains to be the use of a lysimeter, whose bottom is kept continuously at a suction close to the one existing in the soil.

  4. use of nuclear spectroscopic techniques for assessment of polluting elements in environmental samples

    International Nuclear Information System (INIS)

    El Reefy, H.I.

    2011-01-01

    The concentrations of elements and radioisotopes in sediment, soil, water and wild plant samples collected from Burullus Lake, Egypt, has been studied in order to understand current contamination due to agricultural and industrial wastewaters. A multiple approaches were applied to assess properly sediment contamination in the Burullus Lake. The distributions of the Al, Fe and Mn in the lake's sediments are relatively homogenous with the exception of three locations with significantly high levels of Al and Fe in close approximation in the southeastern part. Sediments collected from the lake can be categorized as unpolluted with the exception of three locations which were very low polluted with Sr based on the geo-accumulation indices. High enrichment factors were obtained for Mn, Co, Cr, Cu and Zn. The MPIs indicate that one of the drain may have a major role in mobilizing major and trace metals in the lake environment while cluster analysis indicates possible pollution from only three of the drainage channels. Comparisons with consensus-based sediment quality guidelines revealed that 100%, ∼69%, ∼92% and ∼∼15% of the samples exceeded the threshold effect concentration for Cr, Cu, Ni and Zn, respectively, with over 15% for Cr and Ni of the sample concentrations falling above the probable effect concentration. On the other hand, no samples exceed both levels for Pb. The concentration of 40 K is uniform and that of 137 Cs is generally higher in eastern part of the lake. The result indicate that 226 Ra is less soluble in the lake environment than 232 Th. Elemental concentrations in water have uniform distributions and the Fe, Mn, Co, Cr, Cu and Ni are more likely to exist in soluble phase in the lake environment.

  5. Determination of uranium in urine samples for workers in the phosphoric acid purification using fluorimetry technique

    International Nuclear Information System (INIS)

    Kharita, M. H.; Sakhita, Kh.; Aldalal, Z.

    2003-10-01

    There is probability of exposure to uranium for workers in the phosphoric acid purification (internal exposure) by inhalation, and the deposition of this uranium in organs and tissues, and the consequence excreation out of the body by perspiration or urine. This study focuses on the determination of uranium in urine samples of workers. All results seem to be under the detection limit of the method, therefore no routine monitoring is required. (author)

  6. Application of Compton suppression spectrometry in the improvement of nuclear analytical techniques for biological samples

    International Nuclear Information System (INIS)

    Ahmed, Y. A.; Ewa, I.O.B.; Funtua, I.I.; Jonah, S.A.; Landsberger, S.

    2007-01-01

    Compton Suppression Factors (SF) and Compton Reduction Factors (RF) of the UT Austin's Compton suppression spectrometer being parameters characterizing the system performance were measured using ''1''3''7Cs and ''6''0Co point sources. The system performance was evaluated as a function of energy and geometry. The (P/C), A(P/C), (P/T), Cp, and Ce were obtained for each of the parameters. The natural background reduction factor in the anticoincidence mode and that of normal mode was calculated and its effect on the detection limit of biological samples evaluated. Applicability of the spectrometer and the method for biological samples was tested in the measurement of twenty-four elements (Ba, Sr, I, Br, Cu, V, Mg, Na, Cl, Mn, Ca, Sn, In, K, Mo, Cd, Zn, As, Sb, Ni, Rb, Cs, Fe, and Co) commonly found in food, milk, tea and tobacco items. They were determined from seven National Institute for Standard and Technology (NIST) certified reference materials (rice flour, oyster tissue, non-fat powdered milk, peach leaves, tomato leaves, apple leaves, and citrus leaves). Our results shows good agreement with the NIST certified values, indicating that the method developed in the present study is suitable for the determination of aforementioned elements in biological samples without undue interference problems

  7. [Transabdominal chorionic villus sampling using biopsy forceps or needle: pregnancy outcomes by technique used].

    Science.gov (United States)

    Spallina, J; Anselem, O; Haddad, B; Touboul, C; Tsatsaris, V; Le Ray, C

    2014-11-01

    To compare pregnancy outcomes after transabdominal chorionic villus sampling using biopsy forceps or needle. Retrospective bicentric study including all women who had a transabdominal chorionic villus sampling between 2005 and 2009 (172 using biopsy forceps and 160 using needle). The primary endpoint was the rate of fetal loss, after excluding medical abortion due to the result of the biopsy. The secondary endpoint was the rate of premature rupture of the membrane. All cases were reviewed to try to determine the responsibility of the biopsy. The pregnancy outcomes were not different between the two groups: 4 (4.4%) fetal losses in the biopsy forceps group and 6 (7.4%) in the needle group (P=0.52). Only one case (1.2%) of fetal loss can be attributed to the biopsy, using a needle, and none (0%) following a forceps biospy (P=0.29). The rate of premature rupture of the membrane was comparable in the two groups. The pregnancy outcomes following chorionic villus sampling using a biopsy forceps or a needle seem comparable. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  8. Spatial distribution of metals in soil samples from Zona da Mata, Pernambuco, Brazil using XRF technique

    International Nuclear Information System (INIS)

    Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Menezes, Romulo Simoes Cezar; Santos, Josineide Marques do Nascimento; Bezerra, Jairo Dias; Damascena, Kennedy Francys Rodrigues; Silva, Edvane Borges da; Silva, Alberto Antonio da

    2015-01-01

    Soil contamination is today one of the most important environmental issues for society. In the past, soil pollution was not considered as important as air and water contamination, because this was more difficult to be controlled, becoming an important topic in studies of environmental protection worldwide. Based on this, this paper provides information on the determination of metals in soil samples collected in Zona da Mata, Pernambuco, Brazil, where normally the application of pesticides, insecticides and other agricultural additives are used in a disorderly manner and without control. A total of 24 sampling points were monitored. The analysis of Mn, Fe, Ni, Zn, Br, Rb, Sr, Pb, Ti, La, Al, Si and P were performed using Energy Dispersive X-Ray Fluorescence. In order to assess the development of analytical method, inorganic Certified Reference Materials (IAEA-SOIL-7 and SRM 2709) were analyzed. In each sampling site, the geoaccumulation index were calculated to estimate the level of metal contamination in the soil, this was made taking into account the resolution 460 of the National Environmental Council (CONAMA in Portuguese). The elemental distribution patterns obtained for each metal were associated with different pollution sources. This assessment provides an initial description of pollution levels presented by metals in soils from several areas of Zona da Mata, providing quantitative evidence and demonstrating the need to improve the regulation of agricultural and industrial activities. (author)

  9. Spatial distribution of metals in soil samples from Zona da Mata, Pernambuco, Brazil using XRF technique

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Menezes, Romulo Simoes Cezar; Santos, Josineide Marques do Nascimento; Bezerra, Jairo Dias; Damascena, Kennedy Francys Rodrigues, E-mail: zahily1985@gmail.com, E-mail: jaraujo@ufpe.br, E-mail: romilton@ufpe.br, E-mail: rmenezes@ufpe.br, E-mail: neideden@hotmail.com, E-mail: jairo.dias@ufpe.br, E-mail: kennedy.eng.ambiental@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Energia Nuclear; Alvarez, Juan Reinaldo Estevez, E-mail: jestevez@ceaden.cu [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Silva, Edvane Borges da, E-mail: edvane.borges@pq.cnpq.br [Universidade Federal de Pernambuco (UFPE), Vitoria de Santo Antao, PE (Brazil). Nucleo de Biologia; Franca, Elvis Joacir de; Farias, Emerson Emiliano Gualberto de, E-mail: ejfranca@cnen.gov.br, E-mail: emersonemiliano@yahoo.com.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Silva, Alberto Antonio da, E-mail: alberto.silva@barreiros.ifpe.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Barreiros, PE (Brazil)

    2015-07-01

    Soil contamination is today one of the most important environmental issues for society. In the past, soil pollution was not considered as important as air and water contamination, because this was more difficult to be controlled, becoming an important topic in studies of environmental protection worldwide. Based on this, this paper provides information on the determination of metals in soil samples collected in Zona da Mata, Pernambuco, Brazil, where normally the application of pesticides, insecticides and other agricultural additives are used in a disorderly manner and without control. A total of 24 sampling points were monitored. The analysis of Mn, Fe, Ni, Zn, Br, Rb, Sr, Pb, Ti, La, Al, Si and P were performed using Energy Dispersive X-Ray Fluorescence. In order to assess the development of analytical method, inorganic Certified Reference Materials (IAEA-SOIL-7 and SRM 2709) were analyzed. In each sampling site, the geoaccumulation index were calculated to estimate the level of metal contamination in the soil, this was made taking into account the resolution 460 of the National Environmental Council (CONAMA in Portuguese). The elemental distribution patterns obtained for each metal were associated with different pollution sources. This assessment provides an initial description of pollution levels presented by metals in soils from several areas of Zona da Mata, providing quantitative evidence and demonstrating the need to improve the regulation of agricultural and industrial activities. (author)

  10. Variable sampling-time technique for improving count rate performance of scintillation detectors

    International Nuclear Information System (INIS)

    Tanaka, E.; Nohara, N.; Murayama, H.

    1979-01-01

    A new technique is presented to improve the count rate capability of a scintillation spectrometer or a position sensitive detector with minimum loss of resolution. The technique is based on the combination of pulse shortening and selective integration in which the integration period is not fixed but shortened by the arrival of the following pulse. Theoretical analysis of the degradation of the statiscal component of resolution is made for the proposed system with delay line pulse shortening, and the factor of resolution loss is formulated as a function of the input pulse rate. A new method is also presented for determining the statistical component of resolution separately from the non-statistical system resolution. Preliminary experiments with a NaI(Tl) detector have been carried out, the results of which are consistent with the theoretical prediction. However, due to the non-exponential scintillation decay of the NaI(Tl) crystal, a simple delay line clipping is not satisfactory, and an RC high-pass filter has been added, which results in further degradation of the statistical resolution. (Auth.)

  11. A cost-saving statistically based screening technique for focused sampling of a lead-contaminated site

    International Nuclear Information System (INIS)

    Moscati, A.F. Jr.; Hediger, E.M.; Rupp, M.J.

    1986-01-01

    High concentrations of lead in soils along an abandoned railroad line prompted a remedial investigation to characterize the extent of contamination across a 7-acre site. Contamination was thought to be spotty across the site reflecting its past use in battery recycling operations at discrete locations. A screening technique was employed to delineate the more highly contaminated areas by testing a statistically determined minimum number of random samples from each of seven discrete site areas. The approach not only quickly identified those site areas which would require more extensive grid sampling, but also provided a statistically defensible basis for excluding other site areas from further consideration, thus saving the cost of additional sample collection and analysis. The reduction in the number of samples collected in ''clean'' areas of the site ranged from 45 to 60%

  12. Use of an oscillation technique to measure effective cross-sections of fissionable samples in critical assemblies

    International Nuclear Information System (INIS)

    Tretiakoff, O.; Vidal, R.; Carre, J.C.; Robin, M.

    1964-01-01

    The authors describe the technique used to measure the effective absorption and neutron-yield cross-sections of a fissionable sample. These two values are determined by analysing the signals due to the variation in reactivity (over-all signal) and the local perturbation in the flux (local signal) produced by the oscillating sample. These signals are standardized by means of a set of samples containing quantities of fissionable material ( 235 U) and an absorber, boron, which are well known. The measurements are made for different neutron spectra characterized by lattice parameters which constitute the central zone within which the sample moves. This technique is used to study the effective cross-sections of uranium-plutonium alloys for different heavy-water and graphite lattices in the MINERVE and MARIUS critical assemblies. The same experiments are carried out on fuel samples of different irradiations in order to determine the evolution of effective cross-sections as a function of the spectrum and the irradiations. (authors) [fr

  13. Reverse sample genome probing, a new technique for identification of bacteria in environmental samples by DNA hybridization, and its application to the identification of sulfate-reducing bacteria in oil field samples

    International Nuclear Information System (INIS)

    Voordouw, G.; Voordouw, J.K.; Karkhoff-Schweizer, R.R.; Fedorak, P.M.; Westlake, D.W.S.

    1991-01-01

    A novel method for identification of bacteria in environmental samples by DNA hybridization is presented. It is based on the fact that, even within a genus, the genomes of different bacteria may have little overall sequence homology. This allows the use of the labeled genomic DNA of a given bacterium (referred to as a standard) to probe for its presence and that of bacteria with highly homologous genomes in total DNA obtained from an environmental sample. Alternatively, total DNA extracted from the sample can be labeled and used to probe filters on which denatured chromosomal DNA from relevant bacterial standards has been spotted. The latter technique is referred to as reverse sample genome probing, since it is the reverse of the usual practice of deriving probes from reference bacteria for analyzing a DNA sample. Reverse sample genome probing allows identification of bacteria in a sample in a single step once a master filter with suitable standards has been developed. Application of reverse sample genome probing to the identification of sulfate-reducing bacteria in 31 samples obtained primarily from oil fields in the province of Alberta has indicated that there are at least 20 genotypically different sulfate-reducing bacteria in these samples

  14. Study of uranium mineralization in rock samples from marwat range bannu basin by fission track analysis technique

    International Nuclear Information System (INIS)

    Qureshi, A.Z.; Ullah, K.; Ullah, N.; Akram, M.

    2004-07-01

    The Geophysics Division, Atomic Energy Minerals Centre (AEMC), Lahore has planned a uranium exploration program in Marwat Range, Bannu Basin. In this connection 30 thin sections of rock samples, collected from four areas; namely, Darra Tang, Simukili, Karkanwal and Sheikhillah from Marwat Range, and one from Salt Range were provided to Nuclear Geology Group of Physics Research Division, PINSTECH for the study of nature and mechanism of uranium mineralization These studies are aimed to help in designing uranium exploration strategy by providing the loci of uranium sources in the Marwat and Salt Ranges. The samples have been studied using fission track analysis technique. (author)

  15. Facile and Sensitive Spectrophotometric Technique for the Determination of Carbofuran in its Formulations, Water and Grain Samples with Substituted Anilines

    Directory of Open Access Journals (Sweden)

    V. Harikishna

    2005-01-01

    Full Text Available Methods are described for the determination of carbofuran in its formulations, in water and grain samples by the diazotization coupling spectrophotometric technique, using substituted anilines such as 4-bromoaniline, 4-methylaniline and 4-aminobenzaldehyde as the coupling agents. The orange red colour formed with 4-bromoaniline shows maximum absorption at 478 nm, yellow colour obtained with 4-methylaniline have maximum absorption at 465 nm whereas a red colour derivative formed with 4-aminobenzaldehyde shows λmax at 472 nm. The methods could be successfully applied for the determination of carbofuran in its formulations, water and grain samples.

  16. Separation and sampling technique of light element isotopes by chemical exchange process

    International Nuclear Information System (INIS)

    Kato, Shunsaku; Oi, Kenta; Takagi, Norio; Hirotsu, Takafumi; Kano, Hirofumi; Sonoda, Akinari; Makita, Yoji

    2000-01-01

    Lithium and boron isotope separation technique were studied. Granulation of lithium isotope separation agent was carried out by cure covering in solution. Separation of lithium isotope was stepped up by ammonium carbonate used as elusion agent. Styrene and ester resin derived three kinds of agents such as 2-amino-1, 3-propanediol (1, 3-PD), 2-amino-2-methyl-1, 3-propanediol (Me-1,3-PD) and tris(2-hydroxyethyl)amine (Tris) were used as absorbent.The ester resin with Tris showed larger amount of adsorption (1.4 mmol/g) than other resins. However, all resins with agent indicated more large adsorption volume of boron than the objective value (0.5 mmol/g). Large isotope shift was shown by the unsymmetrical vibration mode of lithium ion on the basis of quantum chemical calculation of isotope effect on dehydration of hydrated lithium ion. (S.Y.)

  17. Laser Based In Situ Techniques: Novel Methods for Generating Extreme Conditions in TEM Samples

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, M; Lagrange, T; Reed, B; Armstrong, M; Campbell, G; DeHope, W; Kim, J; King, W; Masiel, D; Browning, N

    2008-02-25

    The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

  18. Seasonal atmospheric deposition variations of polychlorinated biphenyls (PCBs) and comparison of some deposition sampling techniques.

    Science.gov (United States)

    Birgül, Askın; Tasdemir, Yücel

    2011-03-01

    Ambient air and bulk deposition samples were collected between June 2008 and June 2009. Eighty-three polychlorinated biphenyl (PCB) congeners were targeted in the samples. The average gas and particle PCB concentrations were found as 393 ± 278 and 70 ± 102 pg/m(3), respectively, and 85% of the atmospheric PCBs were in the gas phase. Bulk deposition samples were collected by using a sampler made of stainless steel. The average PCB bulk deposition flux value was determined as 6,020 ± 4,350 pg/m(2) day. The seasonal bulk deposition fluxes were not statistically different from each other, but the summer flux had higher values. Flux values differed depending on the precipitation levels. The average flux value in the rainy periods was 7,480 ± 4,080 pg/m(2) day while the average flux value in dry periods was 5,550 ± 4,420 pg/m(2) day. The obtained deposition values were lower than the reported values given for the urban and industrialized areas, yet close to the ones for the rural sites. The reported deposition values were also influenced by the type of the instruments used. The average dry deposition and total deposition velocity values calculated based on deposition and concentration values were found as 0.23 ± 0.21 and 0.13 ± 0.13 cm/s, respectively.

  19. The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

    Directory of Open Access Journals (Sweden)

    Daniel Gandyra

    2015-01-01

    Full Text Available We report a novel, practical technique for the concerted, simultaneous determination of both the adhesion force of a small structure or structural unit (e.g., an individual filament, hair, micromechanical component or microsensor to a liquid and its elastic properties. The method involves the creation and development of a liquid meniscus upon touching a liquid surface with the structure, and the subsequent disruption of this liquid meniscus upon removal. The evaluation of the meniscus shape immediately before snap-off of the meniscus allows the quantitative determination of the liquid adhesion force. Concurrently, by measuring and evaluating the deformation of the structure under investigation, its elastic properties can be determined. The sensitivity of the method is remarkably high, practically limited by the resolution of the camera capturing the process. Adhesion forces down to 10 µN and spring constants up to 2 N/m were measured. Three exemplary applications of this method are demonstrated: (1 determination of the water adhesion force and the elasticity of individual hairs (trichomes of the floating fern Salvinia molesta. (2 The investigation of human head hairs both with and without functional surface coatings (a topic of high relevance in the field of hair cosmetics was performed. The method also resulted in the measurement of an elastic modulus (Young’s modulus for individual hairs of 3.0 × 105 N/cm2, which is within the typical range known for human hair. (3 Finally, the accuracy and validity of the capillary adhesion technique was proven by examining calibrated atomic force microscopy cantilevers, reproducing the spring constants calibrated using other methods.

  20. Calibrating passive sampling and passive dosing techniques to lipid based concentrations

    DEFF Research Database (Denmark)

    Mayer, Philipp; Schmidt, Stine Nørgaard; Annika, A.

    2011-01-01

    Equilibrium sampling into various formats of the silicone polydimethylsiloxane (PDMS) is increasingly used to measure the exposure of hydrophobic organic chemicals in environmental matrices, and passive dosing from silicone is increasingly used to control and maintain their exposure in laboratory...... coated vials and with Head Space Solid Phase Microextraction (HS-SPME) yielded lipid based concentrations that were in good agreement with each other, but about a factor of two higher than measured lipid-normalized concentrations in the organisms. Passive dosing was applied to bioconcentration...

  1. Gamma-ray attenuation technique for determining density and water content of wood samples

    International Nuclear Information System (INIS)

    Ferraz, E.S.B.; Aguiar, O.

    1985-01-01

    The theoretical aspects of application of the Beer-Lambert law are discussed, with emphasis on the maximum theoretical error expected. A serie of measurements of moisture content within the range of 8g/cm 3 to 30g/cm 3 are made on samples of Pinus oocarpa by gamma-ray ( 241 Am) attenuation methods and by the conventional gravimetric method. The relative deviations (experimental errors) found in the determinations made by these two methods are compared with the theoretical errors calculated, showing the viability of the gamma-ray method. (M.A.C.) [pt

  2. Use of the electrodeposition technique in the preparation of samples of 237Np and its determination by alpha spectrometry

    International Nuclear Information System (INIS)

    Mertzig, W.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A. de.

    1981-05-01

    The electroplating technique to prepare 237 Np source and its determination by alpha spectrometry is presented. The samples were prepared using a lucite-eletrolitic cell manufactured at IPEN, specially to trace amounts of actinides. A polished brass disk coated with Ni film has been used as cathodo and a fixed Pt wire as anode. The electroplated samples were alpha counted using a surface barrier detector. The optimum conditions to obtain the quantitative deposition of 237 Np have been achieved by studying the effects of some parameters as current density, pH and concentration of eletrolitic solution and time of eletrodeposition, using a carrier technique. After preliminary purification, the method is applied to control trace amounts of 237 Np in the Purex process solutions. (Author) [pt

  3. Product-selective blot: a technique for measuring enzyme activities in large numbers of samples and in native electrophoresis gels

    International Nuclear Information System (INIS)

    Thompson, G.A.; Davies, H.M.; McDonald, N.

    1985-01-01

    A method termed product-selective blotting has been developed for screening large numbers of samples for enzyme activity. The technique is particularly well suited to detection of enzymes in native electrophoresis gels. The principle of the method was demonstrated by blotting samples from glutaminase or glutamate synthase reactions into an agarose gel embedded with ion-exchange resin under conditions favoring binding of product (glutamate) over substrates and other substances in the reaction mixture. After washes to remove these unbound substances, the product was measured using either fluorometric staining or radiometric techniques. Glutaminase activity in native electrophoresis gels was visualized by a related procedure in which substrates and products from reactions run in the electrophoresis gel were blotted directly into a resin-containing image gel. Considering the selective-binding materials available for use in the image gel, along with the possible detection systems, this method has potentially broad application

  4. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments

    Directory of Open Access Journals (Sweden)

    Wim Bras

    2014-11-01

    Full Text Available Small- and wide-angle X-ray scattering (SAXS, WAXS are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

  5. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments.

    Science.gov (United States)

    Bras, Wim; Koizumi, Satoshi; Terrill, Nicholas J

    2014-11-01

    Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

  6. Sampling practices and analytical techniques used in the monitoring of steam and water in CEGB nuclear boilers

    International Nuclear Information System (INIS)

    Goodfellow, G.I.

    1978-01-01

    The steam and water in CEGB Magnox and AGR nuclear boilers are continuously monitored, using both laboratory techniques and on-line instrumentation, in order to maintain the chemical quality within pre-determined limits. The sampling systems in use and some of the difficulties associated with sampling requirements are discussed. The relative merits of chemical instruments installed either locally in various parts of the plant or in centralized instrument rooms are reviewed. The quality of water in nuclear boilers, as with all high-pressure steam-raising plant, is extremely high; consequently very sensitive analytical procedures are required, particularly for monitoring the feed-water of 'once-through boiler' systems. Considerable progress has been made in this field and examples are given of some of the techniques developed for analyses at the 'μ/kg' level together with some of the current problems.(author)

  7. [Which route leads from chronic back pain to depression? A path analysis on direct and indirect effects using the cognitive mediators catastrophizing and helplessness/hopelessness in a general population sample].

    Science.gov (United States)

    Fahland, R A; Kohlmann, T; Hasenbring, M; Feng, Y-S; Schmidt, C O

    2012-12-01

    Chronic pain and depression are highly comorbid; however, the longitudinal link is only partially understood. This study examined direct and indirect effects of chronic back pain on depression using path analysis in a general population sample, focussing on cognitive mediator variables. Analyses are based on 413 participants (aged 18-75 years) in a population-based postal survey on back pain who reported chronic back pain at baseline. Follow-up data were collected after 1 year. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Fear-avoidance-beliefs (FABQ), catastrophizing and helplessness/hopelessness (KRSS) were considered as cognitive mediators. Data were analyzed using path analysis. Chronic back pain had no direct effect on depression at follow-up when controlling for cognitive mediators. A mediating effect emerged for helplessness/hopelessness but not for catastrophizing or fear-avoidance beliefs. These results support the cognitive mediation hypothesis which assumes that psychological variables mediate the association between pain and depression. The importance of helplessness/hopelessness is of relevance for the treatment of patients with chronic back pain.

  8. World nuclear energy paths

    International Nuclear Information System (INIS)

    Connolly, T.J.; Hansen, U.; Jaek, W.; Beckurts, K.H.

    1979-01-01

    In examing the world nuclear energy paths, the following assumptions were adopted: the world economy will grow somewhat more slowly than in the past, leading to reductions in electricity demand growth rates; national and international political impediments to the deployment of nuclear power will gradually disappear over the next few years; further development of nuclear power will proceed steadily, without serious interruption but with realistic lead times for the introduction of advanced technologies. Given these assumptions, this paper attempts a study of possible world nuclear energy developments, disaggregated on a regional and national basis. The scenario technique was used and a few alternative fuel-cycle scenarios were developed. Each is an internally consistent model of technically and economically feasible paths to the further development of nuclear power in an aggregate of individual countries and regions of the world. The main purpose of this modeling exercise was to gain some insight into the probable international locations of reactors and other nuclear facilities, the future requirements for uranium and for fuel-cycle services, and the problems of spent-fuel storage and waste management. The study also presents an assessment of the role that nuclear power might actually play in meeting future world energy demand

  9. Amorphous and liquid samples structure and density measurements at high pressure - high temperature using diffraction and imaging techniques

    Science.gov (United States)

    Guignot, N.; King, A.; Clark, A. N.; Perrillat, J. P.; Boulard, E.; Morard, G.; Deslandes, J. P.; Itié, J. P.; Ritter, X.; Sanchez-Valle, C.

    2016-12-01

    Determination of the density and structure of liquids such as iron alloys, silicates and carbonates is a key to understand deep Earth structure and dynamics. X-ray diffraction provided by large synchrotron facilities gives excellent results as long as the signal scattered from the sample can be isolated from its environment. Different techniques already exist; we present here the implementation and the first results given by the combined angle- and energy-dispersive structural analysis and refinement (CAESAR) technique introduced by Wang et al. in 2004, that has never been used in this context. It has several advantages in the study of liquids: 1/ the standard energy-dispersive technique (EDX), fast and compatible with large multi-anvil presses frames, is used for fast analysis free of signal pollution from the sample environment 2/ some limitations of the EDX technique (homogeneity of the sample, low resolution) are irrelevant in the case of liquid signals, others (wrong intensities, escape peaks artifacts, background subtraction) are solved by the CAESAR technique 3/ high Q data (up to 15 A-1 and more) can be obtained in a few hours (usually less than 2). We present here the facilities available on the PSICHE beamline (SOLEIL synchrotron, France) and a few results obtained using a Paris-Edinburgh (PE) press and a 1200 tons load capacity multi-anvil press with a (100) DIA compression module. X-ray microtomography, used in conjunction with a PE press featuring rotating anvils (RotoPEc, Philippe et al., 2013) is also very effective, by simply measuring the 3D volume of glass or liquid spheres at HPHT, thus providing density. This can be done in conjunction with the CAESAR technique and we illustrate this point. Finally, absorption profiles can be obtained via imaging techniques, providing another independent way to measure the density of these materials. References Y. Wang et al., A new technique for angle-dispersive powder diffraction using an energy

  10. Microextraction Techniques Coupled to Liquid Chromatography with Mass Spectrometry for the Determination of Organic Micropollutants in Environmental Water Samples

    Directory of Open Access Journals (Sweden)

    Mª Esther Torres Padrón

    2014-07-01

    Full Text Available Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE, that use large volumes of organic solvents. Solid-phase extraction (SPE uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS and time-of-flight mass spectrometric (TOF/MS techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME, stir bar sorptive extraction (SBSE and liquid-phase microextraction (LPME. Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These

  11. Demonstration of Novel Sampling Techniques for Measurement of Turbine Engine Volatile and Non-Volatile Particulate Matter (PM) Emissions

    Science.gov (United States)

    2017-03-06

    WP-201317) Demonstration of Novel Sampling Techniques for Measurement of Turbine Engine Volatile and Non-volatile Particulate Matter (PM... Engine Volatile and Non-Volatile Particulate Matter (PM) Emissions 6. AUTHOR(S) E. Corporan, M. DeWitt, C. Klingshirn, M.D. Cheng, R. Miake-Lye, J. Peck...the performance and viability of two devices to condition aircraft turbine engine exhaust to allow the accurate measurement of total (volatile and non

  12. Separation techniques for low-level determination of actinides in soil samples

    Energy Technology Data Exchange (ETDEWEB)

    Eikenberg, J. [Paul Scherrer Institute, Department Logistics for Radiation Safety and Security, CH-5232 Villigen (Switzerland)], E-mail: jost.eikenberg@psi.ch; Jaeggi, M.; Beer, H.; Ruethi, M.; Zumsteg, I. [Paul Scherrer Institute, Department Logistics for Radiation Safety and Security, CH-5232 Villigen (Switzerland)

    2009-05-15

    The separation methods for soil samples applied at PSI are based on extraction chromatography and ion exchange. After sample leaching, the actinides are pre-concentrated via precipitation using oxalic acid. Besides the classical separation methods applying the extraction chromatographic resins U/TEVA{sup TM} (for U, Th), TRU{sup TM} (Pu, Am), new methods were recently implemented to increase the radiochemical recovery of particularly trivalent Am and Cm. These methods do not require initial reduction of Pu(IV) to Pu(III) but stabilize Pu on the tetravalent oxidation state using a mixture of NaNO{sub 2}/H{sub 2}O{sub 2} in strong acidic medium. The Pu-fraction is then fixed along with Th onto Dowex AG 1-X2 anion exchanger resin. Th is eluted via complexation with 10 M HCl, Pu via reduction with HI. The fractions of Am+Cm and U are loaded onto DGA{sup TM} resin. This resin shows extraordinary high distribution coefficients (k'-values) exceeding 10{sup 4} (for Am) in strong nitric acid medium. The separation between U and Am is obtained quantitatively by decreasing the HNO{sub 3} concentration from 3 to 0.25 M (stripping of the U-fraction) while Am can be easily eluted thereafter using 0.25 M HCl as complexation compound.

  13. A comparison of quantitative reconstruction techniques for PIXE-tomography analysis applied to biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Beasley, D.G., E-mail: dgbeasley@ctn.ist.utl.pt [IST/C2TN, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); Alves, L.C. [IST/C2TN, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); Barberet, Ph.; Bourret, S.; Devès, G.; Gordillo, N.; Michelet, C. [Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Le Trequesser, Q. [Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB, UPR9048) CNRS, Université de Bordeaux, 87 avenue du Dr. A. Schweitzer, Pessac F-33608 (France); Marques, A.C. [IST/IPFN, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); Seznec, H. [Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Silva, R.C. da [IST/IPFN, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal)

    2014-07-15

    The tomographic reconstruction of biological specimens requires robust algorithms, able to deal with low density contrast and low element concentrations. At the IST/ITN microprobe facility new GPU-accelerated reconstruction software, JPIXET, has been developed, which can significantly increase the speed of quantitative reconstruction of Proton Induced X-ray Emission Tomography (PIXE-T) data. It has a user-friendly graphical user interface for pre-processing, data analysis and reconstruction of PIXE-T and Scanning Transmission Ion Microscopy Tomography (STIM-T). The reconstruction of PIXE-T data is performed using either an algorithm based on a GPU-accelerated version of the Maximum Likelihood Expectation Maximisation (MLEM) method or a GPU-accelerated version of the Discrete Image Space Reconstruction Algorithm (DISRA) (Sakellariou (2001) [2]). The original DISRA, its accelerated version, and the MLEM algorithm, were compared for the reconstruction of a biological sample of Caenorhabditis elegans – a small worm. This sample was analysed at the microbeam line of the AIFIRA facility of CENBG, Bordeaux. A qualitative PIXE-T reconstruction was obtained using the CENBG software package TomoRebuild (Habchi et al. (2013) [6]). The effects of pre-processing and experimental conditions on the elemental concentrations are discussed.

  14. Landslide Susceptibility Assessment Using Frequency Ratio Technique with Iterative Random Sampling

    Directory of Open Access Journals (Sweden)

    Hyun-Joo Oh

    2017-01-01

    Full Text Available This paper assesses the performance of the landslide susceptibility analysis using frequency ratio (FR with an iterative random sampling. A pair of before-and-after digital aerial photographs with 50 cm spatial resolution was used to detect landslide occurrences in Yongin area, Korea. Iterative random sampling was run ten times in total and each time it was applied to the training and validation datasets. Thirteen landslide causative factors were derived from the topographic, soil, forest, and geological maps. The FR scores were calculated from the causative factors and training occurrences repeatedly ten times. The ten landslide susceptibility maps were obtained from the integration of causative factors that assigned FR scores. The landslide susceptibility maps were validated by using each validation dataset. The FR method achieved susceptibility accuracies from 89.48% to 93.21%. And the landslide susceptibility accuracy of the FR method is higher than 89%. Moreover, the ten times iterative FR modeling may contribute to a better understanding of a regularized relationship between the causative factors and landslide susceptibility. This makes it possible to incorporate knowledge-driven considerations of the causative factors into the landslide susceptibility analysis and also be extensively used to other areas.

  15. Statistical Symbolic Execution with Informed Sampling

    Science.gov (United States)

    Filieri, Antonio; Pasareanu, Corina S.; Visser, Willem; Geldenhuys, Jaco

    2014-01-01

    Symbolic execution techniques have been proposed recently for the probabilistic analysis of programs. These techniques seek to quantify the likelihood of reaching program events of interest, e.g., assert violations. They have many promising applications but have scalability issues due to high computational demand. To address this challenge, we propose a statistical symbolic execution technique that performs Monte Carlo sampling of the symbolic program paths and uses the obtained information for Bayesian estimation and hypothesis testing with respect to the probability of reaching the target events. To speed up the convergence of the statistical analysis, we propose Informed Sampling, an iterative symbolic execution that first explores the paths that have high statistical significance, prunes them from the state space and guides the execution towards less likely paths. The technique combines Bayesian estimation with a partial exact analysis for the pruned paths leading to provably improved convergence of the statistical analysis. We have implemented statistical symbolic execution with in- formed sampling in the Symbolic PathFinder tool. We show experimentally that the informed sampling obtains more precise results and converges faster than a purely statistical analysis and may also be more efficient than an exact symbolic analysis. When the latter does not terminate symbolic execution with informed sampling can give meaningful results under the same time and memory limits.

  16. Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

    Directory of Open Access Journals (Sweden)

    Magdalena Jabłońska-Czapla

    2015-01-01

    Full Text Available Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples. An important issue addressed is the preparation of environmental samples for speciation analysis.

  17. An intercomparison of sampling techniques among five European laboratories for measurements of radiocaesium in upland pasture and soil

    International Nuclear Information System (INIS)

    Nielsen, S.P.; Aarkrog, A.; Colgan, P.A.; McGee, E.; Synnott, H.J.; Johansson, K.J.; Horrill, A.D.; Kennedy, V.H.; Barbayiannis, N.

    1992-02-01

    An intercomparison of sampling procedures used by five European laboratories for the determination of radiocaesium in vegetation and peaty soil was carried out at two locations in Cumbria. The soil sampling procedures included th ecollection of depth profiles in order to obtain information on the vertical distribution of radiocaesium in addition to the total deposition. The number of samples taken by each laboratory varied from one to five. The multiple sampling has given information on the homogeneity of the parameters studied at each location. The parameters comprise soil bulk densities, total deposition of 137 Cs, deposition of 137 Cs in three soil layers, biomass densities, concentrations of 137 Cs in pasture, and activity ratios ( 134 Cs/ 137 Cs) in soil and vegetation. The determination of total deposition of 137 Cs gave no indication of differences between the laboratories. The total depositions of 134 Cs and 137 Cs observed at one site were compared with levels obtained from another study and the two sets of data were found to be in good agreement. The results from the soil profiles do indicate significant differences between laboratories. This covers the vertical distributions of 137 Cs deposition including the 134 Cs/ 137 Cs-activity ratios as well as the soil bulk densities. One laboratory using a coring technique observed difficulties during sampling due to compression of the soil. The coring technique should thus be avoided or applied with extreme care for the sampling of depth profiles in peaty soil. The results from the sampling of pasture show no indication of differences between the laboratories. For the parameters studied the observed variabilities across soil depths and locations range from 10% to 82% in terms of relative standard deviations. A comparison across all results at the two locations indicate a 50% higher field variability at one of the sites relative to the other. (au) (24 tabs., 9 ills., 3 refs.)

  18. Evaluation of vacuum microwave-assisted extraction technique for the extraction of antioxidants from plant samples.

    Science.gov (United States)

    Xiao, Xiao-Hua; Wang, Jun-Xia; Wang, Gang; Wang, Jia-Yue; Li, Gong-Ke

    2009-12-18

    In the present work, vacuum microwave-assisted extraction (VMAE) was to perform microwave-assisted extraction in vacuum. Two well-known antioxidants, vitamin C from guava and green pepper, and vitamin E (alpha-tocopherol and gamma-tocopherol) from soybean and tea leaves, which were easy to be oxidized, were chosen as representative target compounds for the evaluation of VMAE. The extraction yields of vitamin C, alpha-tocopherol and gamma-tocopherol in VMAE and those in MAE performed in atmosphere (air-MAE) were compared and the effects of extraction time, extraction temperature and sample matrix were studied. Moreover, the effects of the oxygen and subpressure invacuo were also discussed via performed MAE in N(2) atmosphere (N(2)-MAE). The extraction yields of vitamin C, alpha-tocopherol and gamma-tocopherol in VMAE were higher than that in air-MAE, 35% increments of vitamin C from green pepper, 22% increments of alpha-tocopherol and 47% increments of gamma-tocopherol from tea leaves were obtained, respectively. The comparable increased extraction yields of vitamin C, alpha-tocopherol and gamma-tocopherol in N(2)-MAE to that in air-MAE confirmed that oxygen in system was the crucial factor for the oxidation of vitamin C and vitamin E, VMAE was beneficial for the extraction of these oxygen-sensitive compounds. In addition, the subpressure invacuo in the VMAE system also showed positive affect on the extraction yields. On the basis of preventing oxidation and improving extraction efficiency of target compounds because of less oxygen and subpressure invacuo in the extraction system, VMAE has good potential for the extraction of oxygen-sensitive and thermosensitive compounds from plant samples.

  19. Analysis of plutonium isotopes in marine samples by radiometric, ICP-MS and AMS techniques

    International Nuclear Information System (INIS)

    Lee, S.H.; Gastaud, J.; La Rosa, J.J.; Liong Wee Kwong, L.; Povinec, P.P.; Wyse, E.

    2001-01-01

    IAEA reference materials (radionuclides in the marine environment) collected in areas affected by nuclear reprocessing plants and nuclear weapons tests have been analysed by semiconductor alpha-spectrometry (SAS), liquid scintillation spectrometry (LSS) and mass spectrometric techniques (high resolution ICP-MS and AMS) with the aim of developing analytical procedures and to study the geochemical behavior of plutonium in the marine environment. The Pu results obtained by SAS, ICP-MS and AMS were in reasonably good agreement (R 2 = 0.99). The mean atom ratios of 240 Pu/ 239 Pu in IAEA reference materials, IAEA-134, 135 and 381 were (0.212±0.010), (0.211±0.004) and (0.242±0.004), respectively. IAEA-384 (Fangataufa Lagoon Sediment) gave a 240 Pu/ 239 Pu mean atom ratio of 0.051±0.001. The results of 241 Pu obtained buy ICP-MS and LSS also show reasonable agreement (R 2 = 0.91). Pu isotopic signatures were useful in tracing Pu origin and in interpreting biogeochemical processes involving Pu in the marine environment. (author)

  20. Elemental analysis of different varieties of rice samples using XRF technique

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jaspreet, E-mail: gillpreet05051812@gmail.com; Kumar, Anil, E-mail: gilljaspreet06@gmail.com [Department of Basic and Applied Physics, Punjabi University, Patiala 147002 (India)

    2016-05-06

    Rice is most consumed staple food in the world providing over 21% of the calorie intake of world’s population having high yielding capacity. Elements detected in rice are Al, As, Br, Cd, Cl, Co, Cs, Cu, Fe, Hg, K, Mg, Mn, Mo, Rb, Se and Zn by using Instrumental Neutron Activation with k0 standardization (R. Jayasekera etal,2004). Some of these trace elements are C, H, O, N, S, Ca, P, K, Na, Cl, Mn, Ti, Mg, Cu, Fe, Ni, Si and Zn are essential for growth of human physique The deficiency or excess of these elements in food is known to cause a variety of malnutrition or health disorders in the world. Every year, various varieties of rice are launched by Punjab Agriculture University, Ludhiana. The main purpose of which is to increases the yield to attain the maximum profit. But this leads to changing the elemental concentration in them, which may affect the human health according to variation in the nutrition values. The main objective is to study the presence of elemental concentration in various varieties of rice using EDXRF technique.

  1. Elemental analysis of different varieties of rice samples using XRF technique

    International Nuclear Information System (INIS)

    Kaur, Jaspreet; Kumar, Anil

    2016-01-01

    Rice is most consumed staple food in the world providing over 21% of the calorie intake of world’s population having high yielding capacity. Elements detected in rice are Al, As, Br, Cd, Cl, Co, Cs, Cu, Fe, Hg, K, Mg, Mn, Mo, Rb, Se and Zn by using Instrumental Neutron Activation with k0 standardization (R. Jayasekera etal,2004). Some of these trace elements are C, H, O, N, S, Ca, P, K, Na, Cl, Mn, Ti, Mg, Cu, Fe, Ni, Si and Zn are essential for growth of human physique The deficiency or excess of these elements in food is known to cause a variety of malnutrition or health disorders in the world. Every year, various varieties of rice are launched by Punjab Agriculture University, Ludhiana. The main purpose of which is to increases the yield to attain the maximum profit. But this leads to changing the elemental concentration in them, which may affect the human health according to variation in the nutrition values. The main objective is to study the presence of elemental concentration in various varieties of rice using EDXRF technique.

  2. Subsurface stormflow modeling with sensitivity analysis using a Latin-hypercube sampling technique

    International Nuclear Information System (INIS)

    Gwo, J.P.; Toran, L.E.; Morris, M.D.; Wilson, G.V.

    1994-09-01

    Subsurface stormflow, because of its dynamic and nonlinear features, has been a very challenging process in both field experiments and modeling studies. The disposal of wastes in subsurface stormflow and vadose zones at Oak Ridge National Laboratory, however, demands more effort to characterize these flow zones and to study their dynamic flow processes. Field data and modeling studies for these flow zones are relatively scarce, and the effect of engineering designs on the flow processes is poorly understood. On the basis of a risk assessment framework and a conceptual model for the Oak Ridge Reservation area, numerical models of a proposed waste disposal site were built, and a Latin-hypercube simulation technique was used to study the uncertainty of model parameters. Four scenarios, with three engineering designs, were simulated, and the effectiveness of the engineering designs was evaluated. Sensitivity analysis of model parameters suggested that hydraulic conductivity was the most influential parameter. However, local heterogeneities may alter flow patterns and result in complex recharge and discharge patterns. Hydraulic conductivity, therefore, may not be used as the only reference for subsurface flow monitoring and engineering operations. Neither of the two engineering designs, capping and French drains, was found to be effective in hydrologically isolating downslope waste trenches. However, pressure head contours indicated that combinations of both designs may prove more effective than either one alone

  3. Use of higher order signal moments and high speed digital sampling technique for neutron flux measurements

    Science.gov (United States)

    Baers, L. B.; Gutierrez, T. Rivero; Mendoza, R. A. Carrillo; Santana, G. Jimenez

    1993-08-01

    The second (conventional variance or Campbell signal), the third, and the modified fourth order central signal moments associated with the amplified and filtered currents from two electrodes of an ex-core neutron sensitive fission detector were measured versus the reactor power of the 1-MW TRIGA reactor in Mexico City. Two channels of a high-speed (400-MHz) multiplexing data sampler and an analog-to-digital converter with 12-b resolution and 1-Mword buffer memory were used. The data were further retrieved into a PC, and estimates for autocorrelation and cross-correlation moments up to the fifth order, coherence, skewness, excess, etc., quantities were calculated offline. Five-mode operation of the detector was achieved, including conventional counting rates and currents in agreement with theory and the authors' previous results with analog techniques. The signals are proportional to the neutron flux and reactor power in some flux ranges. The suppression of background noise is improved and the lower limit of the measurement range is extended as the order of moment is increased, in agreement with theory.

  4. Shortest Path Problems in a Stochastic and Dynamic Environment

    National Research Council Canada - National Science Library

    Cho, Jae

    2003-01-01

    .... Particularly, we develop a variety of algorithms to solve the expected shortest path problem in addition to techniques for computing the total travel time distribution along a path in the network...

  5. Introduction to body composition assessment using the deuterium dilution technique with analysis of saliva samples by fourier transform infrared spectrometry

    International Nuclear Information System (INIS)

    2010-01-01

    For many years, the IAEA has fostered the more widespread use of stable isotope techniques to assess body composition in different population groups to address priority areas in public health nutrition in Member States. The objective is to support national and regional nutrition projects through both the IAEA's technical cooperation programme and its coordinated research projects. In particular, during the last few years, the increased access to analyses of deuterium enrichment by Fourier transform infrared (FTIR) spectrometry has increased the application of this technique in Africa, Asia and Latin America. This publication was developed by an international group of experts to provide practical, hands-on guidance in the use of this technique in settings where the analysis of deuterium enrichment in saliva samples will be made by FTIR. It is targeted at new users of this technique, for example nutritionists, analytical chemists and other professionals. More detailed information on the theoretical background and the practical application of state of the art methodologies to monitor changes in body composition can be found in an IAEA publication entitled Assessment of Body Composition and Total Energy Expenditure in Humans by Stable Isotope Techniques (IAEA Human Health Series No. 3)

  6. Accelerated Evaluation of Automated Vehicles Safety in Lane-Change Scenarios Based on Importance Sampling Techniques.

    Science.gov (United States)

    Zhao, Ding; Lam, Henry; Peng, Huei; Bao, Shan; LeBlanc, David J; Nobukawa, Kazutoshi; Pan, Christopher S

    2017-03-01

    Automated vehicles (AVs) must be thoroughly evaluated before their release and deployment. A widely used evaluation approach is the Naturalistic-Field Operational Test (N-FOT), which tests prototype vehicles directly on the public roads. Due to the low exposure to safety-critical scenarios, N-FOTs are time consuming and expensive to conduct. In this paper, we propose an accelerated evaluation approach for AVs. The results can be used to generate motions of the other primary vehicles to accelerate the verification of AVs in simulations and controlled experiments. Frontal collision due to unsafe cut-ins is the target crash type of this paper. Human-controlled vehicles making unsafe lane changes are modeled as the primary disturbance to AVs based on data collected by the University of Michigan Safety Pilot Model Deployment Program. The cut-in scenarios are generated based on skewed statistics of collected human driver behaviors, which generate risky testing scenarios while preserving the statistical information so that the safety benefits of AVs in nonaccelerated cases can be accurately estimated. The cross-entropy method is used to recursively search for the optimal skewing parameters. The frequencies of the occurrences of conflicts, crashes, and injuries are estimated for a modeled AV, and the achieved accelerated rate is around 2000 to 20 000. In other words, in the accelerated simulations, driving for 1000 miles will expose the AV with challenging scenarios that will take about 2 to 20 million miles of real-world driving to encounter. This technique thus has the potential to greatly reduce the development and validation time for AVs.

  7. Model determination in a case of heterogeneity of variance using sampling techniques.

    Science.gov (United States)

    Varona, L; Moreno, C; Garcia-Cortes, L A; Altarriba, J

    1997-01-12

    A sampling determination procedure has been described in a case of heterogeneity of variance. The procedure makes use of the predictive distributions of each data given the rest of the data and the structure of the assumed model. The computation of these predictive distributions is carried out using a Gibbs Sampling procedure. The final criterion to compare between models is the Mean Square Error between the expectation of predictive distributions and real data. The procedure has been applied to a data set of weight at 210 days in the Spanish Pirenaica beef cattle breed. Three proposed models have been compared: (a) Single Trait Animal Model; (b) Heterogeneous Variance Animal Model; and (c) Multiple Trait Animal Model. After applying the procedure, the most adjusted model was the Heterogeneous Variance Animal Model. This result is probably due to a compromise between the complexity of the model and the amount of available information. The estimated heritabilities under the preferred model have been 0.489 ± 0.076 for males and 0.331 ± 0.082 for females. RESUMEN: Contraste de modelos en un caso de heterogeneidad de varianzas usando métodos de muestreo Se ha descrito un método de contraste de modelos mediante técnicas de muestreo en un caso de heterogeneidad de varianza entre sexos. El procedimiento utiliza las distribucviones predictivas de cada dato, dado el resto de datos y la estructura del modelo. El criterio para coparar modelos es el error cuadrático medio entre la esperanza de las distribuciones predictivas y los datos reales. El procedimiento se ha aplicado en datos de peso a los 210 días en la raza bovina Pirenaica. Se han propuesto tres posibles modelos: (a) Modelo Animal Unicaracter; (b) Modelo Animal con Varianzas Heterogéneas; (c) Modelo Animal Multicaracter. El modelo mejor ajustado fue el Modelo Animal con Varianzas Heterogéneas. Este resultado es probablemente debido a un compromiso entre la complejidad del modelo y la cantidad de datos

  8. Application of the spectrometric and radiochemical techniques in analyzing environmental samples from the Bulgarian Black Sea region

    International Nuclear Information System (INIS)

    Veleva, B.S.; Mungov, G.; Galabov, N.; Kolarova, M.; Guenchev, T.

    1999-01-01

    Development of the appropriate methods and techniques for marine and atmospheric radioactivity measurements in the NIMH-BAS during the last 5 years is presented. Approaches for pre-concentration of the radionuclides from the atmosphere and sea water samples followed with reliable radiochemical methods for radionuclides separation and low level counting are discussed. Dissolved radiocesium concentrations measured in a period of time starting in 1993 show some decrease with years and spatial variations probably due to the hydrophysical features of the sampling sides - the lower measured concentrations during 1995 and 1998 correspond to the lower salinity. Application of the radiochemical separation of Plutonium, Thorium, 90 Sr and Americium on the samples from the Bulgarian Black Sea coastal region is reported. (author)

  9. RIA of PGFsub(2α) and PGE2 in biological samples of different origin: comparison with the mass fragmentographic technique

    International Nuclear Information System (INIS)

    Cattabeni, F.; Borghi, C.; Folco, G.C.; Nicosia, S.; Spagnuolo, C.

    1979-01-01

    The aim of this paper is to describe some results obtained measuring PGFsub(2α) and PGE 2 with bioassay, RIA and mass fragmentography in samples of different biological origin such as rat brain cortex and human urine of normal subjects and patients with Bartter's Syndrome. The results reported here clearly indicate that the assay of PGFsub(2α) and PGE 2 require an accurate validation with different analytical techniques. In fact, RIA of PGFsub(2α) gave different results if the samples were of different origin. It can be concluded that all the methods today available for PGs measurements need to be accurately validated utilizing different assays and that this validation is required everytime the sample matrix is changed. (Auth.)

  10. Development of Spatial Scaling Technique of Forest Health Sample Point Information

    Science.gov (United States)

    Lee, J. H.; Ryu, J. E.; Chung, H. I.; Choi, Y. Y.; Jeon, S. W.; Kim, S. H.

    2018-04-01

    Forests provide many goods, Ecosystem services, and resources to humans such as recreation air purification and water protection functions. In rececnt years, there has been an increase in the factors that threaten the health of forests such as global warming due to climate change, environmental pollution, and the increase in interest in forests, and efforts are being made in various countries for forest management. Thus, existing forest ecosystem survey method is a monitoring method of sampling points, and it is difficult to utilize forests for forest management because Korea is surveying only a small part of the forest area occupying 63.7 % of the country (Ministry of Land Infrastructure and Transport Korea, 2016). Therefore, in order to manage large forests, a method of interpolating and spatializing data is needed. In this study, The 1st Korea Forest Health Management biodiversity Shannon;s index data (National Institute of Forests Science, 2015) were used for spatial interpolation. Two widely used methods of interpolation, Kriging method and IDW(Inverse Distance Weighted) method were used to interpolate the biodiversity index. Vegetation indices SAVI, NDVI, LAI and SR were used. As a result, Kriging method was the most accurate method.

  11. Study of organohalogens in foodstuffs and environmental samples by neutron activation analysis and related techniques

    International Nuclear Information System (INIS)

    Xu, D. D.; Mao, X.Y.; Ouyang, H.; Chai, Z. F.; Zhang, H.; Sun, H. B.

    2004-01-01

    Pine needles and foodstuffs collected from Beijing, China, were analyzed by instrumental neutron activation analysis (INAA) combined with organic solvent extraction for total halogens, extractable organohalogens (EOX) and extractable persistent organohalogens (EPOX). The INAA detection limits are 50 ng, 8 ng and 3.5 ng for Cl, Br and I, respectively. The contents and distribution patterns of organohalogens in these samples are reported. EOCl accounted for 0.013-0.016% and 1.6-2.7% of the total chlorine in yogurt and apples, respectively, which suggested that chlorine in foodstuffs mainly existed as inorganic species and non-extractable organochlorines. EOCl contents in pine needles and foodstuffs were noticeably higher than those of EOBr and EOI. For pine needles, yogurt and apples, 1.6-34%, 23-58% and 29-35% of EOCl remained as extractable persistent organochlorine (EPOCl), respectively. Pine needle containing higher EOCl contents in chemical industrial and traffic hub areas indicated that chemical industries and exhaust emission from vehicle were the main sources of organochlorines in the Beijing's air. The relative proportions of the known organochlorines (such as HCHs, DDTs, chlordanes, heptachlor, HCB and PCBs) to the total EOCl and EPOCl were 0.04-1.6% and 0.7-21.5%, respectively, which implied that the identity of species of a major portion of the EOCl and EPOCl measured in pine needles was unknown. (author)

  12. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Cruz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the sample allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studied. Special care has been dedicated to the influence of the presence of a 13C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used is an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer. (Author) 98 refs

  13. Analysis of sample composition using resonant ionization and time-of-flight techniques

    International Nuclear Information System (INIS)

    Luz, A. de la; Ortiz, M.; Campos, J.

    1995-01-01

    This paper describes the setting up of a linear time-of-flight mass spectrometer that uses a tunable laser to produce resonant ionization of atoms and molecules in a pulsed supersonic beam. The ability of this kind of systems to produce time resolved signals for each species present in the samples allows quantitative analysis of its composition. By using a tunable laser beam of high spectral resolution to produce ionization, studies based on the structure of the photoionization spectra obtained are possible. In the present work several isotopic species of ordinary and deuterated benzene have been studies. special care has been dedicated to the influence of the presence of a ''13 C in the ring. In this way values for spectroscopic constants and isotopic shifts have been obtained. Another system based in a homemade proportional counter has been designed and used as an auxiliary system. The results obtained with it are independent of these mentioned above and compatible with them. This system is of great utility for laser wavelength tuning to produce ionization in the mass spectrometer

  14. DEVELOPMENT OF SPATIAL SCALING TECHNIQUE OF FOREST HEALTH SAMPLE POINT INFORMATION

    Directory of Open Access Journals (Sweden)

    J. H. Lee

    2018-04-01

    Full Text Available Forests provide many goods, Ecosystem services, and resources to humans such as recreation air purification and water protection functions. In rececnt years, there has been an increase in the factors that threaten the health of forests such as global warming due to climate change, environmental pollution, and the increase in interest in forests, and efforts are being made in various countries for forest management. Thus, existing forest ecosystem survey method is a monitoring method of sampling points, and it is difficult to utilize forests for forest management because Korea is surveying only a small part of the forest area occupying 63.7 % of the country (Ministry of Land Infrastructure and Transport Korea, 2016. Therefore, in order to manage large forests, a method of interpolating and spatializing data is needed. In this study, The 1st Korea Forest Health Management biodiversity Shannon;s index data (National Institute of Forests Science, 2015 were used for spatial interpolation. Two widely used methods of interpolation, Kriging method and IDW(Inverse Distance Weighted method were used to interpolate the biodiversity index. Vegetation indices SAVI, NDVI, LAI and SR were used. As a result, Kriging method was the most accurate method.

  15. Sample preparation for total reflection X-ray fluorescence analysis using resist pattern technique

    Science.gov (United States)

    Tsuji, K.; Yomogita, N.; Konyuba, Y.

    2018-06-01

    A circular resist pattern layer with a diameter of 9 mm was prepared on a glass substrate (26 mm × 76 mm; 1.5 mm thick) for total reflection X-ray fluorescence (TXRF) analysis. The parallel cross pattern was designed with a wall thickness of 10 μm, an interval of 20 μm, and a height of 1.4 or 0.8 μm. This additional resist layer did not significantly increase background intensity on the XRF peaks in TXRF spectra. Dotted residue was obtained from a standard solution (10 μL) containing Ti, Cr, Ni, Pb, and Ga, each at a final concentration of 10 ppm, on a normal glass substrate with a silicone coating layer. The height of the residue was more than 100 μm, where self-absorption in the large residue affected TXRF quantification (intensity relative standard deviation (RSD): 12-20%). In contrast, from a droplet composed of a small volume of solution dropped and cast on the resist pattern structure, the obtained residue was not completely film but a film-like residue with a thickness less than 1 μm, where self-absorption was not a serious problem. In the end, this sample preparation was demonstrated to improve TXRF quantification (intensity RSD: 2-4%).

  16. Ecology and sampling techniques of an understudied subterranean habitat: the Milieu Souterrain Superficiel (MSS).

    Science.gov (United States)

    Mammola, Stefano; Giachino, Pier Mauro; Piano, Elena; Jones, Alexandra; Barberis, Marcel; Badino, Giovanni; Isaia, Marco

    2016-12-01

    The term Milieu Souterrain Superficiel (MSS) has been used since the early 1980s in subterranean biology to categorize an array of different hypogean habitats. In general terms, a MSS habitat represents the underground network of empty air-filled voids and cracks developing within multiple layers of rock fragments. Its origins can be diverse and is generally covered by topsoil. The MSS habitat is often connected both with the deep hypogean domain-caves and deep rock cracks-and the superficial soil horizon. A MSS is usually characterized by peculiar microclimatic conditions, and it can harbor specialized hypogean, endogean, and surface-dwelling species. In light of the many interpretations given by different authors, we reviewed 235 papers regarding the MSS in order to provide a state-of-the-art description of these habitats and facilitate their study. We have briefly described the different types of MSS mentioned in the scientific literature (alluvial, bedrock, colluvial, volcanic, and other types) and synthesized the advances in the study of the physical and ecological factors affecting this habitat-i.e., microclimate, energy flows, animal communities, and trophic interactions. We finally described and reviewed the available sampling methods used to investigate MSS fauna.

  17. Path integration on hyperbolic spaces

    Energy Technology Data Exchange (ETDEWEB)

    Grosche, C [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    1991-11-01

    Quantum mechanics on the hyperbolic spaces of rank one is discussed by path integration technique. Hyperbolic spaces are multi-dimensional generalisation of the hyperbolic plane, i.e. the Poincare upper half-plane endowed with a hyperbolic geometry. We evalute the path integral on S{sub 1} {approx equal} SO (n,1)/SO(n) and S{sub 2} {approx equal} SU(n,1)/S(U(1) x U(n)) in a particular coordinate system, yielding explicitly the wave-functions and the energy spectrum. Futhermore we can exploit a general property of all these spaces, namely that they can be parametrized by a pseudopolar coordinate system. This allows a separation in path integration over spheres and an additional path integration over the remaining hyperbolic coordinate, yielding effectively a path integral for a modified Poeschl-Teller potential. Only continuous spectra can exist in all the cases. For all the hyperbolic spaces of rank one we find a general formula for the largest lower bound (zero-point energy) of the spectrum which is given by E{sub O} = h{sup 2} /8m(m{sub {alpha}} +2m{sub 2} {alpha}){sup 2} (m {alpha} and m{sub 2}{alpha} denote the dimension of the root subspace corresponding to the roots {alpha} and 2{alpha}, respectively). I also discuss the case, where a constant magnetic field on H{sup n} is incorporated. (orig.).

  18. Path integration on hyperbolic spaces

    International Nuclear Information System (INIS)

    Grosche, C.

    1991-11-01

    Quantum mechanics on the hyperbolic spaces of rank one is discussed by path integration technique. Hyperbolic spaces are multi-dimensional generalisation of the hyperbolic plane, i.e. the Poincare upper half-plane endowed with a hyperbolic geometry. We evalute the path integral on S 1 ≅ SO (n,1)/SO(n) and S 2 ≅ SU(n,1)/S[U(1) x U(n)] in a particular coordinate system, yielding explicitly the wave-functions and the energy spectrum. Futhermore we can exploit a general property of all these spaces, namely that they can be parametrized by a pseudopolar coordinate system. This allows a separation in path integration over spheres and an additional path integration over the remaining hyperbolic coordinate, yielding effectively a path integral for a modified Poeschl-Teller potential. Only continuous spectra can exist in all the cases. For all the hyperbolic spaces of rank one we find a general formula for the largest lower bound (zero-point energy) of the spectrum which is given by E O = h 2 /8m(m α +2m 2 α) 2 (m α and m 2 α denote the dimension of the root subspace corresponding to the roots α and 2α, respectively). I also discuss the case, where a constant magnetic field on H n is incorporated. (orig.)

  19. Single-particle characterization of ice-nucleating particles and ice particles residuals sampled by three different techniques

    Science.gov (United States)

    Kandler, Konrad; Worringen, Annette; Benker, Nathalie; Dirsch, Thomas; Mertes, Stephan; Schenk, Ludwig; Kästner, Udo; Frank, Fabian; Nillius, Björn; Bundke, Ulrich; Rose, Diana; Curtius, Joachim; Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Schneider, Johannes; Schmidt, Susan; Weinbruch, Stephan; Ebert, Martin

    2015-04-01

    During January/February 2013, at the High Alpine Research Station Jungfraujoch a measurement campaign was carried out, which was centered on atmospheric ice-nucleating particles (INP) and ice particle residuals (IPR). Three different techniques for separation of INP and IPR from the non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed phase clouds and allow for the analysis of the residuals. The combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated INP for analysis. Collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine size, chemical composition and mixing state. All INP/IPR-separating techniques had considerable abundances (median 20 - 70 %) of instrumental contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH+IN-PCVI: steel particles). Also, potential sampling artifacts (e.g., pure soluble material) occurred with a median abundance of separated by all three techniques. Soot was a minor contributor. Lead was detected in less than 10 % of the particles, of which the majority were internal mixtures with other particle types. Sea-salt and sulfates were identified by all three methods as INP/IPR. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 µm, while the Ice-CVI also separated many submicron IPR. As strictly parallel sampling could not be performed, a part of the discrepancies between the different techniques may result from

  20. Seven-hour fluorescence in situ hybridization technique for enumeration of Enterobacteriaceae in food and environmental water sample.

    Science.gov (United States)

    Ootsubo, M; Shimizu, T; Tanaka, R; Sawabe, T; Tajima, K; Ezura, Y

    2003-01-01

    A fluorescent in situ hybridization (FISH) technique using an Enterobacteriaceae-specific probe (probe D) to target 16S rRNA was improved in order to enumerate, within a single working day, Enterobacteriaceae present in food and environmental water samples. In order to minimize the time required for the FISH procedure, each step of FISH with probe D was re-evaluated using cultured Escherichia coli. Five minutes of ethanol treatment for cell fixation and hybridization were sufficient to visualize cultured E. coli, and FISH could be performed within 1 h. Because of the difficulties in detecting low levels of bacterial cells by FISH without cultivation, a FISH technique for detecting microcolonies on membrane filters was investigated to improve the bacterial detection limit. FISH with probe D following 6 h of cultivation to grow microcolonies on a 13 mm diameter membrane filter was performed, and whole Enterobacteriaceae microcolonies on the filter were then detected and enumerated by manual epifluorescence microscopic scanning at magnification of x100 in ca 5 min. The total time for FISH with probe D following cultivation (FISHFC) was reduced to within 7 h. FISHFC can be applied to enumerate cultivable Enterobacteriaceae in food (above 100 cells g-1) and environmental water samples (above 1 cell ml-1). Cultivable Enterobacteriaceae in food and water samples were enumerated accurately within 7 h using the FISHFC method. A FISHFC method capable of evaluating Enterobacteriaceae contamination in food and environmental water within a single working day was developed.

  1. Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

    Energy Technology Data Exchange (ETDEWEB)

    Dahing, Lahasen Normanshah [School of Applied Physics, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia and Malaysian Nuclear Agency (Nuklear Malaysia), Bangi 43000, Kajang (Malaysia); Yahya, Redzuan [School of Applied Physics, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Yahya, Roslan; Hassan, Hearie [Malaysian Nuclear Agency (Nuklear Malaysia), Bangi 43000, Kajang (Malaysia)

    2014-09-03

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm{sup 3} and 15×15×15 cm{sup 3} were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed.

  2. Impact of changing from staining to culture techniques on detection rates of Campylobacter spp. in routine stool samples in Chile.

    Science.gov (United States)

    Porte, Lorena; Varela, Carmen; Haecker, Thomas; Morales, Sara; Weitzel, Thomas

    2016-05-13

    Campylobacter is a leading cause of bacterial gastroenteritis, but sensitive diagnostic methods such as culture are expensive and often not available in resource limited settings. Therefore, direct staining techniques have been developed as a practical and economical alternative. We analyzed the impact of replacing Campylobacter staining with culture for routine stool examinations in a private hospital in Chile. From January to April 2014, a total of 750 consecutive stool samples were examined in parallel by Hucker stain and Campylobacter culture. Isolation rates of Campylobacter were determined and the performance of staining was evaluated against culture as the gold standard. Besides, isolation rates of Campylobacter and other enteric pathogens were compared to those of past years. Campylobacter was isolated by culture in 46 of 750 (6.1 %) stool samples. Direct staining only identified three samples as Campylobacter positive and reached sensitivity and specificity values of 6.5 and 100 %, respectively. In comparison to staining-based detection rates of previous years, we observed a significant increase of Campylobacter cases in our patients. Direct staining technique for Campylobacter had a very low sensitivity compared to culture. Staining methods might lead to a high rate of false negative results and an underestimation of the importance of campylobacteriosis. With the inclusion of Campylobacter culture, this pathogen became a leading cause of intestinal infection in our patient population.

  3. [Comparison of the determination of cyclosporin-A in blood samples collected on filter paper and by the ordinary technique].

    Science.gov (United States)

    Azevedo, L S; Manrique, R; Sabbaga, E

    1995-01-01

    Monitoring cyclosporin-A (CsA) blood levels is of utmost importance for the rational use of this drug. Although many centers perform transplants, in Brazil there are few laboratories able to measure CsA blood levels. Therefore making blood samples reach the laboratory emerged as a problem. Collection of blood on filter paper has been a technique used for a long time in special cases. PURPOSE--To confirm the usefulness of measuring CsA blood levels in blood samples collected on filter paper and in the usual way. METHOD--We studied twenty renal cadaver kidney recipients who were receiving CsA, azathioprine and prednisone. Ninety five blood samples were collected and divided into two aliquots. One of them was sent routinely to one laboratory to perform whole blood CsA measurements. From the other aliquot, 20 microliters were pipetted on filter paper. When dried they were mailed to the other laboratory, where, after elution, CsA was measured. In both cases radioimmunoassay with polyclonal antibody was used. RESULTS--Linear correlation between both measurements revealed r = 0.81 with no statistical difference. CONCLUSION--The technique showed to be useful in clinical practice. In countries with continental size, as Brazil, it may be very helpful.

  4. XRF and TXRF techniques for multi-element determination of trace elements in whole blood and human hair samples

    International Nuclear Information System (INIS)

    Khuder, A.; Karjou, J.; Sawan, M.Kh.; Bakir, M.A.

    2007-01-01

    XRF and TXRF were established as useful techniques for multi-element analysis of whole blood and human head hair samples. Direct-XRF with different collimation units and different X-ray excitation modes was successfully used for the determination of S, P, K, Ca, Fe, and Br elements in blood samples and K, Ca, Mn, Fe elements in human hair samples. Direct analysis by TXRF was used for the determination of Rb and Sr in digested blood and human hair samples, respectively, while, the co-precipitation method using APDC for TXRF analysis was used for the determination of Ni, Cu, Zn, and Pb elements in both matrices. As a result, the improved XRF and TXRF methods were applied for multi-element determination of elements in whole blood and human hair samples in non-occupational exposed population living in Damascus city. The mean concentrations of analyzed elements in both matrices were on the reported range values for non-occupational population in other countries. (author)

  5. XRF and TXRF techniques for multi-element determination of trace elements in whole blood and human hair samples

    International Nuclear Information System (INIS)

    Khuder, A.; Karjou, J.; Sawan, M.Kh.; Bakir, M.A.

    2008-01-01

    XRF and TXRF were established as useful techniques for multi-element analysis of whole blood and human head hair samples. Direct-XRF with different collimation units and different X-ray excitation modes was successfully used for the determination of S, P, K, Ca, Fe, and Br elements in blood samples and K, Ca, Mn, Fe elements in human hair samples. Direct analysis by TXRF was used for the determination of Rb and Sr in digested blood and human hair samples, respectively, while, the co-precipitation method using APDC for TXRF analysis was used for the determination of Ni, Cu, Zn, and Pb elements in both matrices. As a result, the improved XRF and TXRF methods were applied for multi-element determination of elements in whole blood and human hair samples in non-occupational exposed population living in Damascus city. The mean concentrations of analyzed elements in both matrices were on the reported range values for non-occupational population in other countries. (author)

  6. Agarose gel electrophoresis of cerebrospinal fluid proteins of dogs after sample concentration using a membrane microconcentrator technique.

    Science.gov (United States)

    Gama, Fernanda Gomes Velasque; Santana, Aureo Evangelista; Filho, Eugênio de Campos; Nogueira, Cláudia Aparecida da Silva

    2007-03-01

    Cerebrospinal fluid (CSF) is produced in the cerebral ventricles through ultrafiltration of plasma and active transport mechanisms. Evaluation of proteins in CSF may provide important information about the production of immunoglobulins within the central nervous system as well as possible disturbances in the blood-brain barrier. The objective of this study was to measure the concentration and fractions of protein in CSF samples using a membrane microconcentrator technique followed by electrophoresis, and to compare the protein fractions obtained with those in serum. CSF samples from 3 healthy dogs and 3 dogs with canine distemper virus infection were concentrated using a membrane microconcentrator having a 0.5 to 30,000 d nominal molecular weight limit (Ultrafree, Millipore, Billerica, MA, USA). Protein concentration was determined before and after concentration. Agarose gel electrophoresis was done on concentrated CSF samples, serum, and serial dilutions of one of the CSF samples. Electrophoretic bands were clearly identified in densitometer tracings in CSF samples with protein concentrations as low as 1.3 g/dL. The higher CSF protein concentration in dogs with distemper was mainly the result of increased albumin concentration. The microconcentrating method used in this study enables characterization of the main protein fractions in CSF by routine electrophoresis and may be useful for interpreting the underlying cause of changes in CSF protein concentrations.

  7. X-Ray Micro-Computed Tomography of Apollo Samples as a Curation Technique Enabling Better Research

    Science.gov (United States)

    Ziegler, R. A.; Almeida, N. V.; Sykes, D.; Smith, C. L.

    2014-01-01

    X-ray micro-computed tomography (micro-CT) is a technique that has been used to research meteorites for some time and many others], and recently it is becoming a more common tool for the curation of meteorites and Apollo samples. Micro-CT is ideally suited to the characterization of astromaterials in the curation process as it can provide textural and compositional information at a small spatial resolution rapidly, nondestructively, and without compromising the cleanliness of the samples (e.g., samples can be scanned sealed in Teflon bags). This data can then inform scientists and curators when making and processing future sample requests for meteorites and Apollo samples. Here we present some preliminary results on micro-CT scans of four Apollo regolith breccias. Methods: Portions of four Apollo samples were used in this study: 14321, 15205, 15405, and 60639. All samples were 8-10 cm in their longest dimension and approximately equant. These samples were micro-CT scanned on the Nikon HMXST 225 System at the Natural History Museum in London. Scans were made at 205-220 kV, 135-160 microamps beam current, with an effective voxel size of 21-44 microns. Results: Initial examination of the data identify a variety of mineral clasts (including sub-voxel FeNi metal grains) and lithic clasts within the regolith breccias. Textural information within some of the lithic clasts was also discernable. Of particular interest was a large basalt clast (approx.1.3 cc) found within sample 60639, which appears to have a sub-ophitic texture. Additionally, internal void space, e.g., fractures and voids, is readily identifiable. Discussion: It is clear from the preliminary data that micro-CT analyses are able to identify important "new" clasts within the Apollo breccias, and better characterize previously described clasts or igneous samples. For example, the 60639 basalt clast was previously believed to be quite small based on its approx.0.5 sq cm exposure on the surface of the main mass

  8. A comparative examination of several techniques for the routine determination of mercury in biological samples by neutron activation analysis

    International Nuclear Information System (INIS)

    Faanhof, A.; Das, H.A.

    1978-01-01

    A comparative examination of the most important techniques for the separation of mercury from irradiated biological material was made. Procedures for routine analysis and results for standard materials are given. Activation was performed at a thermal neutron flux of approximately 5x10 12 nxcm -2 xs -1 during ( 3 ) 2 offers a convenient solution to this problem. The variation of the neutron flux with the irradiation position can be measured by the application of thin iron rings as flux monitors. Losses of mercury due to uptake in the wall of the irradiation containers are negligible. The most powerful destruction technique for large samples is that based on a stainless-steel bomb. (T. I.)

  9. Carbon diffusion paths and segregation at high-angle tilt grain boundaries in α-Fe studied by using a kinetic activation-relation technique

    Science.gov (United States)

    Restrepo, Oscar A.; Mousseau, Normand; Trochet, Mickaël; El-Mellouhi, Fedwa; Bouhali, Othmane; Becquart, Charlotte S.

    2018-02-01

    Carbon diffusion and segregation in iron is fundamental to steel production but is also associated with corrosion. Using the kinetic activation-relaxation technique (k-ART), a kinetic Monte Carlo (KMC) algorithm with an on-the-fly catalog that allows to obtain diffusion properties over large time scales taking into account long-range elastic effects coupled with an EAM force field, we study the motion of a carbon impurity in four Fe systems with high-angle grain boundaries (GB), focusing on the impact of these extended defects on the long-time diffusion of C. Short and long-time stability of the various GBs is first analyzed, which allows us to conclude that the Σ 3 (1 1 1 ) θ =109 .53∘ GB is unstable, with Fe migration barriers of ˜0.1 eV or less, and C acts as a pinning center. Focusing on three stable GBs, in all cases, these extended defects trap C in energy states lower than found in the crystal. Yet, contrary to general understanding, we show, through simulations extending to 0.1 s, that even tough C diffusion takes place predominantly in the GB, it is not necessarily faster than in the bulk and can even be slower by one to two orders of magnitude depending on the GB type. Analysis of the energy landscape provided by k-ART also shows that the free cavity volume around the impurity is not a strong predictor of diffusion barrier height. Overall, results show rather complex diffusion kinetics intimately dependent on the local environment.

  10. [Amanitine determination as an example of peptide analysis in the biological samples with HPLC-MS technique].

    Science.gov (United States)

    Janus, Tomasz; Jasionowicz, Ewa; Potocka-Banaś, Barbara; Borowiak, Krzysztof

    Routine toxicological analysis is mostly focused on the identification of non-organic and organic, chemically different compounds, but generally with low mass, usually not greater than 500–600 Da. Peptide compounds with atomic mass higher than 900 Da are a specific analytical group. Several dozen of them are highly-toxic substances well known in toxicological practice, for example mushroom toxin and animal venoms. In the paper the authors present an example of alpha-amanitin to explain the analytical problems and different original solutions in identifying peptides in urine samples with the use of the universal LC MS/MS procedure. The analyzed material was urine samples collected from patients with potential mushroom intoxication, routinely diagnosed for amanitin determination. Ultra filtration with centrifuge filter tubes (limited mass cutoff 3 kDa) was used. Filtrate fluid was directly injected on the chromatographic column and analyzed with a mass detector (MS/MS). The separation of peptides as organic, amphoteric compounds from biological material with the use of the SPE technique is well known but requires dedicated, specific columns. The presented paper proved that with the fast and simple ultra filtration technique amanitin can be effectively isolated from urine, and the procedure offers satisfactory sensitivity of detection and eliminates the influence of the biological matrix on analytical results. Another problem which had to be solved was the non-characteristic fragmentation of peptides in the MS/MS procedure providing non-selective chromatograms. It is possible to use higher collision energies in the analytical procedure, which results in more characteristic mass spectres, although it offers lower sensitivity. The ultra filtration technique as a procedure of sample preparation is effective for the isolation of amanitin from the biological matrix. The monitoring of selected mass corresponding to transition with the loss of water molecule offers

  11. Path Integrals in Quantum Mechanics

    International Nuclear Information System (INIS)

    Louko, J

    2005-01-01

    Jean Zinn-Justin's textbook Path Integrals in Quantum Mechanics aims to familiarize the reader with the path integral as a calculational tool in quantum mechanics and field theory. The emphasis is on quantum statistical mechanics, starting with the partition function Tr exp(-β H) and proceeding through the diffusion equation to barrier penetration problems and their semiclassical limit. The 'real time' path integral is defined via analytic continuation and used for the path-integral representation of the nonrelativistic S-matrix and its perturbative expansion. Holomorphic and Grassmannian path integrals are introduced and applied to nonrelativistic quantum field theory. There is also a brief discussion of path integrals in phase space. The introduction includes a brief historical review of path integrals, supported by a bibliography with some 40 entries. As emphasized in the introduction, mathematical rigour is not a central issue in the book. This allows the text to present the calculational techniques in a very readable manner: much of the text consists of worked-out examples, such as the quartic anharmonic oscillator in the barrier penetration chapter. At the end of each chapter there are exercises, some of which are of elementary coursework type, but the majority are more in the style of extended examples. Most of the exercises indeed include the solution or a sketch thereof. The book assumes minimal previous knowledge of quantum mechanics, and some basic quantum mechanical notation is collected in an appendix. The material has a large overlap with selected chapters in the author's thousand-page textbook Quantum Field Theory and Critical Phenomena (2002 Oxford: Clarendon). The stand-alone scope of the present work has, however, allowed a more focussed organization of this material, especially in the chapters on, respectively, holomorphic and Grassmannian path integrals. In my view the book accomplishes its aim admirably and is eminently usable as a textbook

  12. SU-C-207A-05: Feature Based Water Equivalent Path Length (WEPL) Determination for Proton Radiography by the Technique of Time Resolved Dose Measurement

    International Nuclear Information System (INIS)

    Zhang, R; Jee, K; Sharp, G; Flanz, J; Lu, H

    2016-01-01

    Purpose: Studies show that WEPL can be determined from modulated dose rate functions (DRF). However, the previous calibration method based on statistics of the DRF is sensitive to energy mixing of protons due to scattering through different materials (termed as range mixing here), causing inaccuracies in the determination of WEPL. This study intends to explore time-domain features of the DRF to reduce the effect of range mixing in proton radiography (pRG) by this technique. Methods: An amorphous silicon flat panel (PaxScan™ 4030CB, Varian Medical Systems, Inc., Palo Alto, CA) was placed behind phantoms to measure DRFs from a proton beam modulated by a specially designed modulator wheel. The performance of two methods, the previously used method based on the root mean square (RMS) and the new approach based on time-domain features of the DRF, are compared for retrieving WEPL and RSP from pRG of a Gammex phantom. Results: Calibration by T_8_0 (the time point for 80% of the major peak) was more robust to range mixing and produced WEPL with improved accuracy. The error of RSP was reduced from 8.2% to 1.7% for lung equivalent material, with the mean error for all other materials reduced from 1.2% to 0.7%. The mean error of the full width at half maximum (FWHM) of retrieved inserts was decreased from 25.85% to 5.89% for the RMS and T_8_0 method respectively. Monte Carlo simulations in simplified cases also demonstrated that the T_8_0 method is less sensitive to range mixing than the RMS method. Conclusion: WEPL images have been retrieved based on single flat panel measured DRFs, with inaccuracies reduced by exploiting time-domain features as the calibration parameter. The T_8_0 method is validated to be less sensitive to range mixing and can thus retrieve the WEPL values in proximity of interfaces with improved numerical and spatial accuracy for proton radiography.

  13. Optical waveguide lightmode spectroscopy technique-based immunosensor development for aflatoxin B1 determination in spice paprika samples.

    Science.gov (United States)

    Majer-Baranyi, Krisztina; Zalán, Zsolt; Mörtl, Mária; Juracsek, Judit; Szendrő, István; Székács, András; Adányi, Nóra

    2016-11-15

    Optical waveguide lightmode spectroscopy (OWLS) technique has been applied to label-free detection of aflatoxin B1 in a competitive immunoassay format, with the aim to compare the analytical goodness of the developed OWLS immunosenor with HPLC and enzyme-linked immunosorbent assay (ELISA) methods for the detection of aflatoxin in spice paprika matrix. We have also assessed applicability of the QuEChERS method prior to ELISA measurements, and the results were compared to those obtained by traditional solvent extraction followed by immunoaffinity clean-up. The AFB1 content of sixty commercial spice paprika samples from different countries were measured with the developed and optimized OWLS immunosensor. Comparing the results from the indirect immunosensor to that obtained by HPLC or ELISA provided excellent correlation (with regression coefficients above 0.94) indicating that the competitive OWLS immunosensor has a potential for quick determination of aflatoxin B1 in paprika samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

    Science.gov (United States)

    Roseman, Edward F.; Kennedy, Gregory W.; Craig, Jaquelyn; Boase, James; Soper, Karen

    2011-01-01

    In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8 m) Detroit River using an anchor and buoy system.

  15. Sampling and sample preparation development for analytical and on-line measurement techniques of process liquids; Naeytteenoton ja kaesittelyn kehittaeminen prosessinesteiden analytiikan ja on-line mittaustekniikan tarpeisiin - MPKT 11

    Energy Technology Data Exchange (ETDEWEB)

    Karttunen, K [Oulu Univ. (Finland)

    1999-12-31

    Main goal of the research project is to develop sampling and sample handling methods and techniques for pulp and paper industry to be used for analysis and on-line purposes. The research focus specially on the research and development of the classification and separation methods and techniques needed for liquid and colloidal substances as well as in ion analysis. (orig.)

  16. Sampling and sample preparation development for analytical and on-line measurement techniques of process liquids; Naeytteenoton ja kaesittelyn kehittaeminen prosessinesteiden analytiikan ja on-line mittaustekniikan tarpeisiin - MPKT 11

    Energy Technology Data Exchange (ETDEWEB)

    Karttunen, K. [Oulu Univ. (Finland)

    1998-12-31

    Main goal of the research project is to develop sampling and sample handling methods and techniques for pulp and paper industry to be used for analysis and on-line purposes. The research focus specially on the research and development of the classification and separation methods and techniques needed for liquid and colloidal substances as well as in ion analysis. (orig.)

  17. Evaluating organochlorine pesticide residues in the aquatic environment of the Lake Naivasha River basin using passive sampling techniques.

    Science.gov (United States)

    Abbasi, Yasser; Mannaerts, Chris M

    2018-05-18

    Passive sampling techniques can improve the discovery of low concentrations by continuous collecting the contaminants, which usually go undetected with classic and once-off time-point grab sampling. The aim of this study was to evaluate organochlorine pesticide (OCP) residues in the aquatic environment of the Lake Naivasha river basin (Kenya) using passive sampling techniques. Silicone rubber sheet and Speedisk samplers were used to detect residues of α-HCH, β-HCH, γ-HCH, δ-HCH, heptachlor, aldrin, heptachlor epoxide, pp-DDE, endrin, dieldrin, α-endosulfan, β-endosulfan, pp-DDD, endrin aldehyde, pp-DDT, endosulfan sulfate, and methoxychlor in the Malewa River and Lake Naivasha. After solvent extraction from the sampling media, the residues were analyzed using gas chromatography electron capture detection (GC-ECD) for the OCPs and gas chromatography-mass spectrometry (GC-MS) for the PCB reference compounds. Measuring the OCP residues using the silicone rubber samplers revealed the highest concentration of residues (∑OCPs of 81 (± 18.9 SD) μg/L) to be at the Lake site, being the ultimate accumulation environment for surficial hydrological, chemical, and sediment transport through the river basin. The total OCP residue sums changed to 71.5 (± 11.3 SD) μg/L for the Middle Malewa and 59 (± 12.5 SD) μg/L for the Upper Malewa River sampling sites. The concentration sums of OCPs detected using the Speedisk samplers at the Upper Malewa, Middle Malewa, and the Lake Naivasha sites were 28.2 (± 4.2 SD), 31.3 (± 1.8 SD), and 34.2 (± 6.4 SD) μg/L, respectively. An evaluation of the different pesticide compound variations identified at the three sites revealed that endosulfan sulfate, α-HCH, methoxychlor, and endrin aldehyde residues were still found at all sampling sites. However, the statistical analysis of one-way ANOVA for testing the differences of ∑OCPs between the sampling sites for both the silicone rubber sheet and Speedisk samplers

  18. Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

    Science.gov (United States)

    Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schneider, J.; Schmidt, S.; Weinbruch, S.; Ebert, M.

    2015-04-01

    In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200

  19. Xenosurveillance reflects traditional sampling techniques for the identification of human pathogens: A comparative study in West Africa.

    Directory of Open Access Journals (Sweden)

    Joseph R Fauver

    2018-03-01

    Full Text Available Novel surveillance strategies are needed to detect the rapid and continuous emergence of infectious disease agents. Ideally, new sampling strategies should be simple to implement, technologically uncomplicated, and applicable to areas where emergence events are known to occur. To this end, xenosurveillance is a technique that makes use of blood collected by hematophagous arthropods to monitor and identify vertebrate pathogens. Mosquitoes are largely ubiquitous animals that often exist in sizable populations. As well, many domestic or peridomestic species of mosquitoes will preferentially take blood-meals from humans, making them a unique and largely untapped reservoir to collect human blood.We sought to take advantage of this phenomenon by systematically collecting blood-fed mosquitoes during a field trail in Northern Liberia to determine whether pathogen sequences from blood engorged mosquitoes accurately mirror those obtained directly from humans. Specifically, blood was collected from humans via finger-stick and by aspirating bloodfed mosquitoes from the inside of houses. Shotgun metagenomic sequencing of RNA and DNA derived from these specimens was performed to detect pathogen sequences. Samples obtained from xenosurveillance and from finger-stick blood collection produced a similar number and quality of reads aligning to two human viruses, GB virus C and hepatitis B virus.This study represents the first systematic comparison between xenosurveillance and more traditional sampling methodologies, while also demonstrating the viability of xenosurveillance as a tool to sample human blood for circulating pathogens.

  20. Comparison of analysis techniques by liquid scintillation and Cerenkov Effect for 40K quantification in aqueous samples

    International Nuclear Information System (INIS)

    Miranda C, L.; Davila R, J. I.; Lopez del R, H.; Mireles G, F.

    2015-09-01

    In this work the counting by liquid scintillation and Cerenkov Effect to quantify 40 K in aqueous samples was used. The performance of both techniques was studied by comparing the response of three commercial liquid scintillation OptiPhase HiSafe 3, Ultima Gold Ab and OptiPhase TriSafe, the vial type and presentation conditions of the sample for counting. In liquid scintillation, the ability to form homogeneous mixtures depended on the ionic strength of the aqueous solutions. The scintillator OptiPhase HiSafe 3 showed a greater charge capacity for solutions with high ionic strength (<3.4), while the scintillator OptiSafe TriSafe no form homogeneous mixtures for solutions of ionic strength higher than 0.3. Counting efficiencies for different proportions of sample and scintillator near 100% for the scintillators OptiSafe HiSafe 3 and Ultima Gold Ab were obtained. In the counting by Cerenkov Effect, the efficiency and sensitivity depended of the vial type; polyethylene vials were more suitable for counting that the glass vials. The sample volume had not significant effect on counting efficiency, obtaining an average value of 44.8% for polyethylene vials and 37.3% for glass vials. Therefore, the liquid scintillation was more efficient and sensitive for the measurement of 40 K in aqueous solutions. (Author)

  1. Large-volume constant-concentration sampling technique coupling with surface-enhanced Raman spectroscopy for rapid on-site gas analysis.

    Science.gov (United States)

    Zhang, Zhuomin; Zhan, Yisen; Huang, Yichun; Li, Gongke

    2017-08-05

    In this work, a portable large-volume constant-concentration (LVCC) sampling technique coupling with surface-enhanced Raman spectroscopy (SERS) was developed for the rapid on-site gas analysis based on suitable derivatization methods. LVCC sampling technique mainly consisted of a specially designed sampling cell including the rigid sample container and flexible sampling bag, and an absorption-derivatization module with a portable pump and a gas flowmeter. LVCC sampling technique allowed large, alterable and well-controlled sampling volume, which kept the concentration of gas target in headspace phase constant during the entire sampling process and made the sampling result more representative. Moreover, absorption and derivatization of gas target during LVCC sampling process were efficiently merged in one step using bromine-thiourea and OPA-NH 4 + strategy for ethylene and SO 2 respectively, which made LVCC sampling technique conveniently adapted to consequent SERS analysis. Finally, a new LVCC sampling-SERS method was developed and successfully applied for rapid analysis of trace ethylene and SO 2 from fruits. It was satisfied that trace ethylene and SO 2 from real fruit samples could be actually and accurately quantified by this method. The minor concentration fluctuations of ethylene and SO 2 during the entire LVCC sampling process were proved to be gas targets from real samples by SERS. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Cooperative organic mine avoidance path planning

    Science.gov (United States)

    McCubbin, Christopher B.; Piatko, Christine D.; Peterson, Adam V.; Donnald, Creighton R.; Cohen, David

    2005-06-01

    The JHU/APL Path Planning team has developed path planning techniques to look for paths that balance the utility and risk associated with different routes through a minefield. Extending on previous years' efforts, we investigated real-world Naval mine avoidance requirements and developed a tactical decision aid (TDA) that satisfies those requirements. APL has developed new mine path planning techniques using graph based and genetic algorithms which quickly produce near-minimum risk paths for complicated fitness functions incorporating risk, path length, ship kinematics, and naval doctrine. The TDA user interface, a Java Swing application that obtains data via Corba interfaces to path planning databases, allows the operator to explore a fusion of historic and in situ mine field data, control the path planner, and display the planning results. To provide a context for the minefield data, the user interface also renders data from the Digital Nautical Chart database, a database created by the National Geospatial-Intelligence Agency containing charts of the world's ports and coastal regions. This TDA has been developed in conjunction with the COMID (Cooperative Organic Mine Defense) system. This paper presents a description of the algorithms, architecture, and application produced.

  3. Two-compartment, two-sample technique for accurate estimation of effective renal plasma flow: Theoretical development and comparison with other methods

    International Nuclear Information System (INIS)

    Lear, J.L.; Feyerabend, A.; Gregory, C.

    1989-01-01

    Discordance between effective renal plasma flow (ERPF) measurements from radionuclide techniques that use single versus multiple plasma samples was investigated. In particular, the authors determined whether effects of variations in distribution volume (Vd) of iodine-131 iodohippurate on measurement of ERPF could be ignored, an assumption implicit in the single-sample technique. The influence of Vd on ERPF was found to be significant, a factor indicating an important and previously unappreciated source of error in the single-sample technique. Therefore, a new two-compartment, two-plasma-sample technique was developed on the basis of the observations that while variations in Vd occur from patient to patient, the relationship between intravascular and extravascular components of Vd and the rate of iodohippurate exchange between the components are stable throughout a wide range of physiologic and pathologic conditions. The new technique was applied in a series of 30 studies in 19 patients. Results were compared with those achieved with the reference, single-sample, and slope-intercept techniques. The new two-compartment, two-sample technique yielded estimates of ERPF that more closely agreed with the reference multiple-sample method than either the single-sample or slope-intercept techniques

  4. Investigation of CPD and HMDS Sample Preparation Techniques for Cervical Cells in Developing Computer-Aided Screening System Based on FE-SEM/EDX

    Science.gov (United States)

    Ng, Siew Cheok; Abu Osman, Noor Azuan

    2014-01-01

    This paper investigated the effects of critical-point drying (CPD) and hexamethyldisilazane (HMDS) sample preparation techniques for cervical cells on field emission scanning electron microscopy and energy dispersive X-ray (FE-SEM/EDX). We investigated the visualization of cervical cell image and elemental distribution on the cervical cell for two techniques of sample preparation. Using FE-SEM/EDX, the cervical cell images are captured and the cell element compositions are extracted for both sample preparation techniques. Cervical cell image quality, elemental composition, and processing time are considered for comparison of performances. Qualitatively, FE-SEM image based on HMDS preparation technique has better image quality than CPD technique in terms of degree of spread cell on the specimen and morphologic signs of cell deteriorations (i.e., existence of plate and pellet drying artifacts and membrane blebs). Quantitatively, with mapping and line scanning EDX analysis, carbon and oxygen element compositions in HMDS technique were higher than the CPD technique in terms of weight percentages. The HMDS technique has shorter processing time than the CPD technique. The results indicate that FE-SEM imaging, elemental composition, and processing time for sample preparation with the HMDS technique were better than CPD technique for cervical cell preparation technique for developing computer-aided screening system. PMID:25610902

  5. Improved abdominal MRI in non-breath-holding children using a radial k-space sampling technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Hyuk; Choi, Young Hun; Cheon, Jung Eun; Lee, So Mi; Cho, Hyun Hae; Kim, Woo Sun; Kim, In One [Seoul National University Children' s Hospital, Department of Radiology, Seoul (Korea, Republic of); Shin, Su Mi [SMG-SNU Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of)

    2015-06-15

    Radial k-space sampling techniques have been shown to reduce motion artifacts in adult abdominal MRI. To compare a T2-weighted radial k-space sampling MRI pulse sequence (BLADE) with standard respiratory-triggered T2-weighted turbo spin echo (TSE) in pediatric abdominal imaging. Axial BLADE and respiratory-triggered turbo spin echo sequences were performed without fat suppression in 32 abdominal MR examinations in children. We retrospectively assessed overall image quality, the presence of respiratory, peristaltic and radial artifact, and lesion conspicuity. We evaluated signal uniformity of each sequence. BLADE showed improved overall image quality (3.35 ± 0.85 vs. 2.59 ± 0.59, P < 0.001), reduced respiratory motion artifact (0.51 ± 0.56 vs. 1.89 ± 0.68, P < 0.001), and improved lesion conspicuity (3.54 ± 0.88 vs. 2.92 ± 0.77, P = 0.006) compared to respiratory triggering turbo spin-echo (TSE) sequences. The bowel motion artifact scores were similar for both sequences (1.65 ± 0.77 vs. 1.79 ± 0.74, P = 0.691). BLADE introduced a radial artifact that was not observed on the respiratory triggering-TSE images (1.10 ± 0.85 vs. 0, P < 0.001). BLADE was associated with diminished signal variation compared with respiratory triggering-TSE in the liver, spleen and air (P < 0.001). The radial k-space sampling technique improved the quality and reduced respiratory motion artifacts in young children compared with conventional respiratory-triggered turbo spin-echo sequences. (orig.)

  6. Monitoring of persistent organic pollutants in seawater of the Pearl River Estuary with rapid on-site active SPME sampling technique

    International Nuclear Information System (INIS)

    Huang, Siming; He, Shuming; Xu, Hao; Wu, Peiyan; Jiang, Ruifen; Zhu, Fang; Luan, Tiangang; Ouyang, Gangfeng

    2015-01-01

    An on-site active solid-phase microextraction (SPME) sampling technique coupled with gas chromatography-mass spectrometry (GC–MS) for sampling and monitoring 16 polycyclic aromatic hydrocarbons (PAHs) and 8 organochlorine pesticides (OCPs) in seawater was developed. Laboratory experiments demonstrated that the sampling-rate calibration method was practical and could be used for the quantification of on-site sampling. The proposed method was employed for field tests which covered large amounts of water samples in the Pearl River Estuary in rainy and dry seasons. The on-site SPME sampling method can avoid the contamination of sample, the losses of analytes during sample transportation, as well as the usage of solvent and time-consuming sample preparation process. Results indicated that the technique with the designed device can address the requirement of modern environment water analysis. In addition, the sources, bioaccumulation and potential risk to human of the PAHs and OCPs in seawater of the Pearl River Estuary were discussed. - Highlights: • SPME on-site active sampling technique was developed and validated. • The technique was employed for field tests in the Pearl River Estuary. • 16 PAHs and 8 OCPs in the seawater of Pearl River Estuary were monitored. • The potential risk of the PAHs and OCPs in Pearl River Estuary were discussed. - An on-site active SPME sampling technique was developed and successfully applied for sampling and monitoring 16 PAHs and 8 OCPs in the Pearl River Estuary

  7. Path-dependent functions

    International Nuclear Information System (INIS)

    Khrapko, R.I.

    1985-01-01

    A uniform description of various path-dependent functions is presented with the help of expansion of the type of the Taylor series. So called ''path-integrals'' and ''path-tensor'' are introduced which are systems of many-component quantities whose values are defined for arbitrary paths in coordinated region of space in such a way that they contain a complete information on the path. These constructions are considered as elementary path-dependent functions and are used instead of power monomials in the usual Taylor series. Coefficients of such an expansion are interpreted as partial derivatives dependent on the order of the differentiations or else as nonstandard cavariant derivatives called two-point derivatives. Some examples of pathdependent functions are presented.Space curvature tensor is considered whose geometrica properties are determined by the (non-transitive) translator of parallel transport of a general type. Covariant operation leading to the ''extension'' of tensor fiels is pointed out

  8. Iterated Leavitt Path Algebras

    International Nuclear Information System (INIS)

    Hazrat, R.

    2009-11-01

    Leavitt path algebras associate to directed graphs a Z-graded algebra and in their simplest form recover the Leavitt algebras L(1,k). In this note, we introduce iterated Leavitt path algebras associated to directed weighted graphs which have natural ± Z grading and in their simplest form recover the Leavitt algebras L(n,k). We also characterize Leavitt path algebras which are strongly graded. (author)

  9. Success and failure rates of tumor genotyping techniques in routine pathological samples with non-small-cell lung cancer.

    Science.gov (United States)

    Vanderlaan, Paul A; Yamaguchi, Norihiro; Folch, Erik; Boucher, David H; Kent, Michael S; Gangadharan, Sidharta P; Majid, Adnan; Goldstein, Michael A; Huberman, Mark S; Kocher, Olivier N; Costa, Daniel B

    2014-04-01

    Identification of some somatic molecular alterations in non-small-cell lung cancer (NSCLC) has become evidence-based practice. The success and failure rate of using commercially available tumor genotyping techniques in routine day-to-day NSCLC pathology samples is not well described. We sought to evaluate the success and failure rate of EGFR mutation, KRAS mutation, and ALK FISH in a cohort of lung cancers subjected to routine clinical tumor genotype. Clinicopathologic data, tumor genotype success and failure rates were retrospectively compiled and analyzed from 381 patient-tumor samples. From these 381 patients with lung cancer, the mean age was 65 years, 61.2% were women, 75.9% were white, 27.8% were never smokers, 73.8% had advanced NSCLC and 86.1% had adenocarcinoma histology. The tumor tissue was obtained from surgical specimens in 48.8%, core needle biopsies in 17.9%, and as cell blocks from aspirates or fluid in 33.3% of cases. Anatomic sites for tissue collection included lung (49.3%), lymph nodes (22.3%), pleura (11.8%), bone (6.0%), brain (6.0%), among others. The overall success rate for EGFR mutation analysis was 94.2%, for KRAS mutation 91.6% and for ALK FISH 91.6%. The highest failure rates were observed when the tissue was obtained from image-guided percutaneous transthoracic core-needle biopsies (31.8%, 27.3%, and 35.3% for EGFR, KRAS, and ALK tests, respectively) and bone specimens (23.1%, 15.4%, and 23.1%, respectively). In specimens obtained from bone, the failure rates were significantly higher for biopsies than resection specimens (40% vs. 0%, p=0.024 for EGFR) and for decalcified compared to non-decalcified samples (60% vs. 5.5%, p=0.021 for EGFR). Tumor genotype techniques are feasible in most samples, outside small image-guided percutaneous transthoracic core-needle biopsies and bone samples from core biopsies with decalcification, and therefore expansion of routine tumor genotype into the care of patients with NSCLC may not require special

  10. Pulled Motzkin paths

    Energy Technology Data Exchange (ETDEWEB)

    Janse van Rensburg, E J, E-mail: rensburg@yorku.c [Department of Mathematics and Statistics, York University, Toronto, ON, M3J 1P3 (Canada)

    2010-08-20

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) {yields} f as f {yields} {infinity}, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) {yields} 2f as f {yields} {infinity}, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  11. Pulled Motzkin paths

    Science.gov (United States)

    Janse van Rensburg, E. J.

    2010-08-01

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  12. Pulled Motzkin paths

    International Nuclear Information System (INIS)

    Janse van Rensburg, E J

    2010-01-01

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  13. Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women

    Directory of Open Access Journals (Sweden)

    Verhelst Rita

    2010-09-01

    Full Text Available Abstract Background Streptococcus agalactiae (group B streptococcus; GBS is a significant cause of perinatal and neonatal infections worldwide. To detect GBS colonization in pregnant women, the CDC recommends isolation of the bacterium from vaginal and anorectal swab samples by growth in a selective enrichment medium, such as Lim broth (Todd-Hewitt broth supplemented with selective antibiotics, followed by subculture on sheep blood agar. However, this procedure may require 48 h to complete. We compared different sampling and culture techniques for the detection of GBS. Methods A total of 300 swabs was taken from 100 pregnant women at 35-37 weeks of gestation. For each subject, one rectovaginal, one vaginal and one rectal ESwab were collected. Plating onto Columbia CNA agar (CNA, group B streptococcus differential agar (GBSDA (Granada Medium and chromID Strepto B agar (CA, with and without Lim broth enrichment, were compared. The isolates were confirmed as S. agalactiae using the CAMP test on blood agar and by molecular identification with tDNA-PCR or by 16S rRNA gene sequence determination. Results The overall GBS colonization rate was 22%. GBS positivity for rectovaginal sampling (100% was significantly higher than detection on the basis of vaginal sampling (50%, but not significantly higher than for rectal sampling (82%. Direct plating of the rectovaginal swab on CNA, GBSDA and CA resulted in detection of 59, 91 and 95% of the carriers, respectively, whereas subculturing of Lim broth yielded 77, 95 and 100% positivity, respectively. Lim broth enrichment enabled the detection of only one additional GBS positive subject. There was no significant difference between GBSDA and CA, whereas both were more sensitive than CNA. Direct culture onto GBSDA or CA (91 and 95% detected more carriers than Lim broth enrichment and subculture onto CNA (77%. One false negative isolate was observed on GBSDA, and three false positives on CA. Conclusions In

  14. Compact, common path quantitative phase microscopic techniques ...

    Indian Academy of Sciences (India)

    2014-01-05

    refractive index information as a change in intensity). ... phase imaging method which provides information about the optical thickness of live .... index values of the material of the glass bead and the surrounding medium was ...

  15. Large-volume constant-concentration sampling technique coupling with surface-enhanced Raman spectro