STS-35 crew and NASA management inspect OV-102 after landing at EAFB, Calif

NASA Technical Reports Server (NTRS)

1990-01-01

STS-35 NASA JSC Flight Crew Operations Directorate (FCOD) Director Donald R. Puddy (center) joins the STS-35 crewmembers in a post landing walk-around inspection of Columbia, Orbiter Vehicle (OV) 102, at Edwards Air Force Base (EAFB), California. Crewmembers, wearing launch and entry suits (LESs), include (left to right) Commander Vance D. Brand, Mission Specialist (MS) John M. Lounge, Payload Specialist Ronald A. Parise, Pilot Guy S. Gardner, and MS Jeffrey A. Hoffman. NASA Associate Administrator for Space Flight Dr. William B. Lenoir is at far left in the background. OV-102 landed on concrete runway 22 at EAFB at 9:54:09 pm (Pacific Standard Time (PST)). OV-102's nose cone and nose landing gear (NLG) door are visible at the left corner of the frame.

Vertical Seismic Profiling at riser drilling site in the rupture area of the 1944 Tonankai Earthquake, Japan (Invited)

NASA Astrophysics Data System (ADS)

Hino, R.; Kinoshita, M.; Araki, E.; Byrne, T. B.; McNeill, L. C.; Saffer, D. M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.

2009-12-01

A series of scientific drilling expeditions is in operation in the Nankai Trough to reveal the faulting mechanism of the magathrust earthquakes, through clarifying composition, fine structure, mechanical behavior, and environmental variables of the seismogenic faults. In the studied area, extensive seismic surveys for site characterization have been made to image detailed geometry of the fault complex in the accretionary prism as well as Vp distribution around the faults. Although these previous surveys provided invaluable information for understanding seismotectonic processes in this subduction zone, more complete knowledge is needed to be acquired to predict dynamic behavior of the faults, such as geometrical irregularities in short wavelength, Vs and seismic attenuation which are sensitive to fluid distribution in and around fault zones. It is expected that estimation of these parameters would be improved considerably by a seismic exploration using a vertical array of seismographs installed in a deep borehole (VSP: vertical seismic profiling). In July 2009, we made a VSP at one of the drilling sites located just above the rupture area of the 1994 Tonankai Earthquake (M 8.1), during the IODP Exp.319. The well site of our VSP was made by the riser drilling of D/V Chikyu. The seismic array, lowered from Chikyu into the hole, was composed of a three-component accelerometer and vertical separation of the array elements was 15.12 m. The VSP was composed of offset VSP and zero-offset VSP. In the offset VSP, a tuned airgun array towed by R/V Kairei was shot along one straight line (walk-away VSP) and another circular line (walk-around VSP) and seismic signals were recorded by an array consisting of 16 elements installed from 907 to 1,135 m in depth from seafloor. The object of the walk-away VSP is to obtain fine image of the faults using reflection arrivals with less attenuation. It is also expected to obtain spatial variation of Vs from arrival time tomography of refracted S waves. For this purpose, we preferred extraordinarily longer (~ 30 km) offset shooting than usual industrial VSPs. Shot spacing was 60 m along the same line as the previous 3D reflection and OBS wide angle surveys. The radius of circle of the walk-around VSP was 3.5 km to detect azimuthal anisotropy of downgoing P and S waves, correlated to stress state around the site. In zero-offset VSP, shots just above the hole were recorded by the 8 element array moving from 0 to 1,135 mbsf along the hole so that seismic structure with comparable vertical resolution as core-log information would be obtained. In the records of the walk-away VSP, clear first arrivals as well as several evident later arrivals were clearly identified. The later phases contain the reflection from the megasplay fault and the refracted S wave through the accretional prism, on both of which we have significant interest. The walk-around VSP also provided us with high S/N records but detailed data reduction, such as velocity analysis using vertical array, are required to derive anisotropic nature of the formation around the hole.

Operators in the Plum Brook Reactor Facility Control Room

NASA Image and Video Library

1970-03-21

Donald Rhodes, left, and Clyde Greer, right, monitor the operation of the National Aeronautics and Space Administration’s (NASA) Plum Brook Reactor Facility from the control room. The 60-megawatt test reactor, NASA’s only reactor, was the eighth largest test reactor in the world. The facility was built by the Lewis Research Center in the late 1950s to study the effects of radiation on different materials that could be used to construct nuclear propulsion systems for aircraft or rockets. The reactor went critical for the first time in 1961. For the next two years, two operators were on duty 24 hours per day working on the fission process until the reactor reached its full-power level in 1963. Reactor Operators were responsible for monitoring and controlling the reactor systems. Once the reactor was running under normal operating conditions, the work was relatively uneventful. Normally the reactor was kept at a designated power level within certain limits. Occasionally the operators had to increase the power for a certain test. The shift supervisor and several different people would get together and discuss the change before boosting the power. All operators were required to maintain a Reactor Operator License from the Atomic Energy Commission. The license included six months of training, an eight-hour written exam, a four-hour walkaround, and testing on the reactor controls.

Virtual environment navigation with look-around mode to explore new real spaces by people who are blind.

PubMed

Lahav, Orly; Gedalevitz, Hadas; Battersby, Steven; Brown, David; Evett, Lindsay; Merritt, Patrick

2018-05-01

This paper examines the ability of people who are blind to construct a mental map and perform orientation tasks in real space by using Nintendo Wii technologies to explore virtual environments. The participant explores new spaces through haptic and auditory feedback triggered by pointing or walking in the virtual environments and later constructs a mental map, which can be used to navigate in real space. The study included 10 participants who were congenitally or adventitiously blind, divided into experimental and control groups. The research was implemented by using virtual environments exploration and orientation tasks in real spaces, using both qualitative and quantitative methods in its methodology. The results show that the mode of exploration afforded to the experimental group is radically new in orientation and mobility training; as a result 60% of the experimental participants constructed mental maps that were based on map model, compared with only 30% of the control group participants. Using technology that enabled them to explore and to collect spatial information in a way that does not exist in real space influenced the ability of the experimental group to construct a mental map based on the map model. Implications for rehabilitation The virtual cane system for the first time enables people who are blind to explore and collect spatial information via the look-around mode in addition to the walk-around mode. People who are blind prefer to use look-around mode to explore new spaces, as opposed to the walking mode. Although the look-around mode requires users to establish a complex collecting and processing procedure for the spatial data, people who are blind using this mode are able to construct a mental map as a map model. For people who are blind (as for the sighted) construction of a mental map based on map model offers more flexibility in choosing a walking path in a real space, accounting for changes that occur in the space.

Evaluation of give kids a boost: A school-based program to increase booster seat use among urban children in economically disadvantaged areas.

PubMed

Yellman, Merissa A; Rodriguez, Marissa A; Colunga, Maria Isabel; McCoy, Mary A; Stephens-Stidham, Shelli; Brown, L Steven; Istre, Gregory R

2018-05-19

This study evaluated the effectiveness of a series of 1-year multifaceted school-based programs aimed at increasing booster seat use among urban children 4-7 years of age in economically disadvantaged areas. During 4 consecutive school years, 2011-2015, the Give Kids a Boost (GKB) program was implemented in a total of 8 schools with similar demographics in Dallas County. Observational surveys were conducted at project schools before project implementation (P 0 ), 1-4 weeks after the completion of project implementation (P 1 ), and 4-5 months later (P 2 ). Changes in booster seat use for the 3 time periods were compared for the 8 project and 14 comparison schools that received no intervention using a nonrandomized trial process. The intervention included (1) train-the-trainer sessions with teachers and parents; (2) presentations about booster seat safety; (3) tailored communication to parents; (4) distribution of fact sheets/resources; (5) walk-around education; and (6) booster seat inspections. The association between the GKB intervention and proper booster seat use was determined initially using univariate analysis. The association was also estimated using a generalized linear mixed model predicting a binomial outcome (booster seat use) for those aged 4 to 7 years, adjusted for child-level variables (age, sex, race/ethnicity) and car-level variables (vehicle type). The model incorporated the effects of clustering by site and by collection date to account for the possibility of repeated sampling. In the 8 project schools, booster seat use for children 4-7 years of age increased an average of 20.9 percentage points between P 0 and P 1 (P 0 = 4.8%, P 1 = 25.7%; odds ratio [OR] = 6.9; 95% confidence interval [CI], 5.5, 8.7; P < .001) and remained at that level in the P 2 time period (P 2 = 25.7%; P < .001, for P 0 vs. P 2 ) in the univariate analysis. The 14 comparison schools had minimal change in booster seat use. The multivariable model showed that children at the project schools were significantly more likely to be properly restrained in a booster seat after the intervention (OR = 2.7; 95% CI, 2.2, 3.3) compared to the P 0 time period and compared to the comparison schools. Despite study limitations, the GKB program was positively associated with an increase in proper booster seat use for children 4-7 years of age in school settings among diverse populations in economically disadvantaged areas. These increases persisted into the following school year in a majority of the project schools. The GKB model may be a replicable strategy to increase booster seat use among school-age children in similar urban settings.

Strengthened IAEA Safeguards-Imagery Analysis: Geospatial Tools for Nonproliferation Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pabian, Frank V

2012-08-14

This slide presentation focuses on the growing role and importance of imagery analysis for IAEA safeguards applications and how commercial satellite imagery, together with the newly available geospatial tools, can be used to promote 'all-source synergy.' As additional sources of openly available information, satellite imagery in conjunction with the geospatial tools can be used to significantly augment and enhance existing information gathering techniques, procedures, and analyses in the remote detection and assessment of nonproliferation relevant activities, facilities, and programs. Foremost of the geospatial tools are the 'Digital Virtual Globes' (i.e., GoogleEarth, Virtual Earth, etc.) that are far better than previouslymore » used simple 2-D plan-view line drawings for visualization of known and suspected facilities of interest which can be critical to: (1) Site familiarization and true geospatial context awareness; (2) Pre-inspection planning; (3) Onsite orientation and navigation; (4) Post-inspection reporting; (5) Site monitoring over time for changes; (6) Verification of states site declarations and for input to State Evaluation reports; and (7) A common basis for discussions among all interested parties (Member States). Additionally, as an 'open-source', such virtual globes can also provide a new, essentially free, means to conduct broad area search for undeclared nuclear sites and activities - either alleged through open source leads; identified on internet BLOGS and WIKI Layers, with input from a 'free' cadre of global browsers and/or by knowledgeable local citizens (a.k.a.: 'crowdsourcing'), that can include ground photos and maps; or by other initiatives based on existing information and in-house country knowledge. They also provide a means to acquire ground photography taken by locals, hobbyists, and tourists of the surrounding locales that can be useful in identifying and discriminating between relevant and non-relevant facilities and their associated infrastructure. The digital globes also provide highly accurate terrain mapping for better geospatial context and allow detailed 3-D perspectives of all sites or areas of interest. 3-D modeling software (i.e., Google's SketchUp6 newly available in 2007) when used in conjunction with these digital globes can significantly enhance individual building characterization and visualization (including interiors), allowing for better assessments including walk-arounds or fly-arounds and perhaps better decision making on multiple levels (e.g., the best placement for International Atomic Energy Agency (IAEA) video monitoring cameras).« less

Methodology Series Module 5: Sampling Strategies.

PubMed

Setia, Maninder Singh

2016-01-01

Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the ' Sampling Method'. There are essentially two types of sampling methods: 1) probability sampling - based on chance events (such as random numbers, flipping a coin etc.); and 2) non-probability sampling - based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample) is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term ' random sample' when the researcher has used convenience sample). The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the ' generalizability' of these results. In such a scenario, the researcher may want to use ' purposive sampling' for the study.

Toward cost-efficient sampling methods

NASA Astrophysics Data System (ADS)

Luo, Peng; Li, Yongli; Wu, Chong; Zhang, Guijie

2015-09-01

The sampling method has been paid much attention in the field of complex network in general and statistical physics in particular. This paper proposes two new sampling methods based on the idea that a small part of vertices with high node degree could possess the most structure information of a complex network. The two proposed sampling methods are efficient in sampling high degree nodes so that they would be useful even if the sampling rate is low, which means cost-efficient. The first new sampling method is developed on the basis of the widely used stratified random sampling (SRS) method and the second one improves the famous snowball sampling (SBS) method. In order to demonstrate the validity and accuracy of two new sampling methods, we compare them with the existing sampling methods in three commonly used simulation networks that are scale-free network, random network, small-world network, and also in two real networks. The experimental results illustrate that the two proposed sampling methods perform much better than the existing sampling methods in terms of achieving the true network structure characteristics reflected by clustering coefficient, Bonacich centrality and average path length, especially when the sampling rate is low.

Methodology Series Module 5: Sampling Strategies

PubMed Central

Setia, Maninder Singh

2016-01-01

Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the ‘ Sampling Method’. There are essentially two types of sampling methods: 1) probability sampling – based on chance events (such as random numbers, flipping a coin etc.); and 2) non-probability sampling – based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample) is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term ‘ random sample’ when the researcher has used convenience sample). The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the ‘ generalizability’ of these results. In such a scenario, the researcher may want to use ‘ purposive sampling’ for the study. PMID:27688438

40 CFR Appendix I to Part 261 - Representative Sampling Methods

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Representative Sampling Methods I...—Representative Sampling Methods The methods and equipment used for sampling waste materials will vary with the form and consistency of the waste materials to be sampled. Samples collected using the sampling...

40 CFR Appendix I to Part 261 - Representative Sampling Methods

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Representative Sampling Methods I...—Representative Sampling Methods The methods and equipment used for sampling waste materials will vary with the form and consistency of the waste materials to be sampled. Samples collected using the sampling...

A new sampling method for fibre length measurement

NASA Astrophysics Data System (ADS)

Wu, Hongyan; Li, Xianghong; Zhang, Junying

2018-06-01

This paper presents a new sampling method for fibre length measurement. This new method can meet the three features of an effective sampling method, also it can produce the beard with two symmetrical ends which can be scanned from the holding line to get two full fibrograms for each sample. The methodology was introduced and experiments were performed to investigate effectiveness of the new method. The results show that the new sampling method is an effective sampling method.

Overseeing oversight: governance of quality and safety by hospital boards in the English NHS.

PubMed

Mannion, Russell; Davies, Huw; Freeman, Tim; Millar, Ross; Jacobs, Rowena; Kasteridis, Panos

2015-01-01

To contribute towards an understanding of hospital board composition and to explore board oversight of patient safety and health care quality in the English NHS. We reviewed the theory related to hospital board governance and undertook two national surveys about board management in NHS acute and specialist hospital trusts in England. The first survey was issued to 150 trusts in 2011/2012 and was completed online via a dedicated web tool. A total 145 replies were received (97% response rate). The second online survey was undertaken in 2012/2013 and targeted individual board members, using a previously validated standard instrument on board members' attitudes and competencies (the Board Self-Assessment Questionnaire). A total of 334 responses were received from 165 executive and 169 non-executive board members, providing at least one response from 95 of the 144 NHS trusts then in existence (66% response rate). Over 90% of the English NHS trust boards had 10-15 members. We found no significant difference in board size between trusts of different types (e.g. Foundation Trusts versus non-Foundation Trusts and Teaching Hospital Trusts versus non-Teaching Hospital Trusts). Clinical representation on boards was limited: around 62% had three or fewer members with clinical backgrounds. For about two-thirds of the trusts (63%), board members with a clinical background comprised less than 30% of the members. Boards were using a wide range and mix of quantitative performance metrics and soft intelligence (e.g. walk-arounds, patient stories) to monitor their organisations with regard to patient safety. The Board Self-Assessment Questionnaire data showed generally high or very high levels of agreement with desirable statements of practice in each of its six dimensions. Aggregate levels of agreement within each dimension ranged from 73% (for the dimension addressing interpersonal issues) to 85% (on the political). English NHS boards largely hold a wide range of attitudes and behaviours that might be expected to benefit patient safety and quality. However, there is significant scope for improvement as regards formal training for board members on quality and safety, routine morbidity reporting at boards and attention to the interpersonal dynamics within boards. Directors with clinical backgrounds remain a minority on most boards despite policies to increase their representation. A better understanding of board composition, actions and attitudes should help refine policy recommendations around boards. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Log sampling methods and software for stand and landscape analyses.

Treesearch

Lisa J. Bate; Torolf R. Torgersen; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

2008-01-01

We describe methods for efficient, accurate sampling of logs at landscape and stand scales to estimate density, total length, cover, volume, and weight. Our methods focus on optimizing the sampling effort by choosing an appropriate sampling method and transect length for specific forest conditions and objectives. Sampling methods include the line-intersect method and...

Comparison of diffusion- and pumped-sampling methods to monitor volatile organic compounds in ground water, Massachusetts Military Reservation, Cape Cod, Massachusetts, July 1999-December 2002

USGS Publications Warehouse

Archfield, Stacey A.; LeBlanc, Denis R.

2005-01-01

To evaluate diffusion sampling as an alternative method to monitor volatile organic compound (VOC) concentrations in ground water, concentrations in samples collected by traditional pumped-sampling methods were compared to concentrations in samples collected by diffusion-sampling methods for 89 monitoring wells at or near the Massachusetts Military Reservation, Cape Cod. Samples were analyzed for 36 VOCs. There was no substantial difference between the utility of diffusion and pumped samples to detect the presence or absence of a VOC. In wells where VOCs were detected, diffusion-sample concentrations of tetrachloroethene (PCE) and trichloroethene (TCE) were significantly lower than pumped-sample concentrations. Because PCE and TCE concentrations detected in the wells dominated the calculation of many of the total VOC concentrations, when VOC concentrations were summed and compared by sampling method, visual inspection also showed a downward concentration bias in the diffusion-sample concentration. The degree to which pumped- and diffusion-sample concentrations agreed was not a result of variability inherent within the sampling methods or the diffusion process itself. A comparison of the degree of agreement in the results from the two methods to 13 quantifiable characteristics external to the sampling methods offered only well-screen length as being related to the degree of agreement between the methods; however, there is also evidence to indicate that the flushing rate of water through the well screen affected the agreement between the sampling methods. Despite poor agreement between the concentrations obtained by the two methods at some wells, the degree to which the concentrations agree at a given well is repeatable. A one-time, well-bywell comparison between diffusion- and pumped-sampling methods could determine which wells are good candidates for the use of diffusion samplers. For wells with good method agreement, the diffusion-sampling method is a time-saving and cost-effective alternative to pumped-sampling methods in a long-term monitoring program, such as at the Massachusetts Military Reservation.

Comparison of soil sampling and analytical methods for asbestos at the Sumas Mountain Asbestos Site-Working towards a toolbox for better assessment.

PubMed

Wroble, Julie; Frederick, Timothy; Frame, Alicia; Vallero, Daniel

2017-01-01

Established soil sampling methods for asbestos are inadequate to support risk assessment and risk-based decision making at Superfund sites due to difficulties in detecting asbestos at low concentrations and difficulty in extrapolating soil concentrations to air concentrations. Environmental Protection Agency (EPA)'s Office of Land and Emergency Management (OLEM) currently recommends the rigorous process of Activity Based Sampling (ABS) to characterize site exposures. The purpose of this study was to compare three soil analytical methods and two soil sampling methods to determine whether one method, or combination of methods, would yield more reliable soil asbestos data than other methods. Samples were collected using both traditional discrete ("grab") samples and incremental sampling methodology (ISM). Analyses were conducted using polarized light microscopy (PLM), transmission electron microscopy (TEM) methods or a combination of these two methods. Data show that the fluidized bed asbestos segregator (FBAS) followed by TEM analysis could detect asbestos at locations that were not detected using other analytical methods; however, this method exhibited high relative standard deviations, indicating the results may be more variable than other soil asbestos methods. The comparison of samples collected using ISM versus discrete techniques for asbestos resulted in no clear conclusions regarding preferred sampling method. However, analytical results for metals clearly showed that measured concentrations in ISM samples were less variable than discrete samples.

Comparison of soil sampling and analytical methods for asbestos at the Sumas Mountain Asbestos Site—Working towards a toolbox for better assessment

PubMed Central

2017-01-01

Established soil sampling methods for asbestos are inadequate to support risk assessment and risk-based decision making at Superfund sites due to difficulties in detecting asbestos at low concentrations and difficulty in extrapolating soil concentrations to air concentrations. Environmental Protection Agency (EPA)’s Office of Land and Emergency Management (OLEM) currently recommends the rigorous process of Activity Based Sampling (ABS) to characterize site exposures. The purpose of this study was to compare three soil analytical methods and two soil sampling methods to determine whether one method, or combination of methods, would yield more reliable soil asbestos data than other methods. Samples were collected using both traditional discrete (“grab”) samples and incremental sampling methodology (ISM). Analyses were conducted using polarized light microscopy (PLM), transmission electron microscopy (TEM) methods or a combination of these two methods. Data show that the fluidized bed asbestos segregator (FBAS) followed by TEM analysis could detect asbestos at locations that were not detected using other analytical methods; however, this method exhibited high relative standard deviations, indicating the results may be more variable than other soil asbestos methods. The comparison of samples collected using ISM versus discrete techniques for asbestos resulted in no clear conclusions regarding preferred sampling method. However, analytical results for metals clearly showed that measured concentrations in ISM samples were less variable than discrete samples. PMID:28759607

Modified electrokinetic sample injection method in chromatography and electrophoresis analysis

DOEpatents

Davidson, J. Courtney; Balch, Joseph W.

2001-01-01

A sample injection method for horizontal configured multiple chromatography or electrophoresis units, each containing a number of separation/analysis channels, that enables efficient introduction of analyte samples. This method for loading when taken in conjunction with horizontal microchannels allows much reduced sample volumes and a means of sample stacking to greatly reduce the concentration of the sample. This reduction in the amount of sample can lead to great cost savings in sample preparation, particularly in massively parallel applications such as DNA sequencing. The essence of this method is in preparation of the input of the separation channel, the physical sample introduction, and subsequent removal of excess material. By this method, sample volumes of 100 nanoliter to 2 microliters have been used successfully, compared to the typical 5 microliters of sample required by the prior separation/analysis method.

[Comparison study on sampling methods of Oncomelania hupensis snail survey in marshland schistosomiasis epidemic areas in China].

PubMed

An, Zhao; Wen-Xin, Zhang; Zhong, Yao; Yu-Kuan, Ma; Qing, Liu; Hou-Lang, Duan; Yi-di, Shang

2016-06-29

To optimize and simplify the survey method of Oncomelania hupensis snail in marshland endemic region of schistosomiasis and increase the precision, efficiency and economy of the snail survey. A quadrate experimental field was selected as the subject of 50 m×50 m size in Chayegang marshland near Henghu farm in the Poyang Lake region and a whole-covered method was adopted to survey the snails. The simple random sampling, systematic sampling and stratified random sampling methods were applied to calculate the minimum sample size, relative sampling error and absolute sampling error. The minimum sample sizes of the simple random sampling, systematic sampling and stratified random sampling methods were 300, 300 and 225, respectively. The relative sampling errors of three methods were all less than 15%. The absolute sampling errors were 0.221 7, 0.302 4 and 0.047 8, respectively. The spatial stratified sampling with altitude as the stratum variable is an efficient approach of lower cost and higher precision for the snail survey.

Methods for purifying carbon materials

DOEpatents

Dailly, Anne [Pasadena, CA; Ahn, Channing [Pasadena, CA; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

2009-05-26

Methods of purifying samples are provided that are capable of removing carbonaceous and noncarbonaceous impurities from a sample containing a carbon material having a selected structure. Purification methods are provided for removing residual metal catalyst particles enclosed in multilayer carbonaceous impurities in samples generate by catalytic synthesis methods. Purification methods are provided wherein carbonaceous impurities in a sample are at least partially exfoliated, thereby facilitating subsequent removal of carbonaceous and noncarbonaceous impurities from the sample. Methods of purifying carbon nanotube-containing samples are provided wherein an intercalant is added to the sample and subsequently reacted with an exfoliation initiator to achieve exfoliation of carbonaceous impurities.

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

PubMed

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.

A Comparison of EPI Sampling, Probability Sampling, and Compact Segment Sampling Methods for Micro and Small Enterprises

PubMed Central

Chao, Li-Wei; Szrek, Helena; Peltzer, Karl; Ramlagan, Shandir; Fleming, Peter; Leite, Rui; Magerman, Jesswill; Ngwenya, Godfrey B.; Pereira, Nuno Sousa; Behrman, Jere

2011-01-01

Finding an efficient method for sampling micro- and small-enterprises (MSEs) for research and statistical reporting purposes is a challenge in developing countries, where registries of MSEs are often nonexistent or outdated. This lack of a sampling frame creates an obstacle in finding a representative sample of MSEs. This study uses computer simulations to draw samples from a census of businesses and non-businesses in the Tshwane Municipality of South Africa, using three different sampling methods: the traditional probability sampling method, the compact segment sampling method, and the World Health Organization’s Expanded Programme on Immunization (EPI) sampling method. Three mechanisms by which the methods could differ are tested, the proximity selection of respondents, the at-home selection of respondents, and the use of inaccurate probability weights. The results highlight the importance of revisits and accurate probability weights, but the lesser effect of proximity selection on the samples’ statistical properties. PMID:22582004

Comparison of indoor air sampling and dust collection methods for fungal exposure assessment using quantitative PCR

EPA Science Inventory

Evaluating fungal contamination indoors is complicated because of the many different sampling methods utilized. In this study, fungal contamination was evaluated using five sampling methods and four matrices for results. The five sampling methods were a 48 hour indoor air sample ...

Evaluation of seven aquatic sampling methods for amphibians and other aquatic fauna

USGS Publications Warehouse

Gunzburger, M.S.

2007-01-01

To design effective and efficient research and monitoring programs researchers must have a thorough understanding of the capabilities and limitations of their sampling methods. Few direct comparative studies exist for aquatic sampling methods for amphibians. The objective of this study was to simultaneously employ seven aquatic sampling methods in 10 wetlands to compare amphibian species richness and number of individuals detected with each method. Four sampling methods allowed counts of individuals (metal dipnet, D-frame dipnet, box trap, crayfish trap), whereas the other three methods allowed detection of species (visual encounter, aural, and froglogger). Amphibian species richness was greatest with froglogger, box trap, and aural samples. For anuran species, the sampling methods by which each life stage was detected was related to relative length of larval and breeding periods and tadpole size. Detection probability of amphibians varied across sampling methods. Box trap sampling resulted in the most precise amphibian count, but the precision of all four count-based methods was low (coefficient of variation > 145 for all methods). The efficacy of the four count sampling methods at sampling fish and aquatic invertebrates was also analyzed because these predatory taxa are known to be important predictors of amphibian habitat distribution. Species richness and counts were similar for fish with the four methods, whereas invertebrate species richness and counts were greatest in box traps. An effective wetland amphibian monitoring program in the southeastern United States should include multiple sampling methods to obtain the most accurate assessment of species community composition at each site. The combined use of frogloggers, crayfish traps, and dipnets may be the most efficient and effective amphibian monitoring protocol. ?? 2007 Brill Academic Publishers.

Sample size determination for mediation analysis of longitudinal data.

PubMed

Pan, Haitao; Liu, Suyu; Miao, Danmin; Yuan, Ying

2018-03-27

Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design. To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel's method, distribution of product method and the bootstrap method. Among the three methods of testing the mediation effects, Sobel's method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel's method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use. Extensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel's method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

Monitoring benthic aIgal communides: A comparison of targeted and coefficient sampling methods

USGS Publications Warehouse

Edwards, Matthew S.; Tinker, M. Tim

2009-01-01

Choosing an appropriate sample unit is a fundamental decision in the design of ecological studies. While numerous methods have been developed to estimate organism abundance, they differ in cost, accuracy and precision.Using both field data and computer simulation modeling, we evaluated the costs and benefits associated with two methods commonly used to sample benthic organisms in temperate kelp forests. One of these methods, the Targeted Sampling method, relies on different sample units, each "targeted" for a specific species or group of species while the other method relies on coefficients that represent ranges of bottom cover obtained from visual esti-mates within standardized sample units. Both the field data and the computer simulations suggest that both methods yield remarkably similar estimates of organism abundance and among-site variability, although the Coefficient method slightly underestimates variability among sample units when abundances are low. In contrast, the two methods differ considerably in the effort needed to sample these communities; the Targeted Sampling requires more time and twice the personnel to complete. We conclude that the Coefficent Sampling method may be better for environmental monitoring programs where changes in mean abundance are of central concern and resources are limiting, but that the Targeted sampling methods may be better for ecological studies where quantitative relationships among species and small-scale variability in abundance are of central concern.

Perpendicular distance sampling: an alternative method for sampling downed coarse woody debris

Treesearch

Michael S. Williams; Jeffrey H. Gove

2003-01-01

Coarse woody debris (CWD) plays an important role in many forest ecosystem processes. In recent years, a number of new methods have been proposed to sample CWD. These methods select individual logs into the sample using some form of unequal probability sampling. One concern with most of these methods is the difficulty in estimating the volume of each log. A new method...

Comparison of Relative Bias, Precision, and Efficiency of Sampling Methods for Natural Enemies of Soybean Aphid (Hemiptera: Aphididae).

PubMed

Bannerman, J A; Costamagna, A C; McCornack, B P; Ragsdale, D W

2015-06-01

Generalist natural enemies play an important role in controlling soybean aphid, Aphis glycines (Hemiptera: Aphididae), in North America. Several sampling methods are used to monitor natural enemy populations in soybean, but there has been little work investigating their relative bias, precision, and efficiency. We compare five sampling methods: quadrats, whole-plant counts, sweep-netting, walking transects, and yellow sticky cards to determine the most practical methods for sampling the three most prominent species, which included Harmonia axyridis (Pallas), Coccinella septempunctata L. (Coleoptera: Coccinellidae), and Orius insidiosus (Say) (Hemiptera: Anthocoridae). We show an important time by sampling method interaction indicated by diverging community similarities within and between sampling methods as the growing season progressed. Similarly, correlations between sampling methods for the three most abundant species over multiple time periods indicated differences in relative bias between sampling methods and suggests that bias is not consistent throughout the growing season, particularly for sticky cards and whole-plant samples. Furthermore, we show that sticky cards produce strongly biased capture rates relative to the other four sampling methods. Precision and efficiency differed between sampling methods and sticky cards produced the most precise (but highly biased) results for adult natural enemies, while walking transects and whole-plant counts were the most efficient methods for detecting coccinellids and O. insidiosus, respectively. Based on bias, precision, and efficiency considerations, the most practical sampling methods for monitoring in soybean include walking transects for coccinellid detection and whole-plant counts for detection of small predators like O. insidiosus. Sweep-netting and quadrat samples are also useful for some applications, when efficiency is not paramount. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Comparability of river suspended-sediment sampling and laboratory analysis methods

USGS Publications Warehouse

Groten, Joel T.; Johnson, Gregory D.

2018-03-06

Accurate measurements of suspended sediment, a leading water-quality impairment in many Minnesota rivers, are important for managing and protecting water resources; however, water-quality standards for suspended sediment in Minnesota are based on grab field sampling and total suspended solids (TSS) laboratory analysis methods that have underrepresented concentrations of suspended sediment in rivers compared to U.S. Geological Survey equal-width-increment or equal-discharge-increment (EWDI) field sampling and suspended sediment concentration (SSC) laboratory analysis methods. Because of this underrepresentation, the U.S. Geological Survey, in collaboration with the Minnesota Pollution Control Agency, collected concurrent grab and EWDI samples at eight sites to compare results obtained using different combinations of field sampling and laboratory analysis methods.Study results determined that grab field sampling and TSS laboratory analysis results were biased substantially low compared to EWDI sampling and SSC laboratory analysis results, respectively. Differences in both field sampling and laboratory analysis methods caused grab and TSS methods to be biased substantially low. The difference in laboratory analysis methods was slightly greater than field sampling methods.Sand-sized particles had a strong effect on the comparability of the field sampling and laboratory analysis methods. These results indicated that grab field sampling and TSS laboratory analysis methods fail to capture most of the sand being transported by the stream. The results indicate there is less of a difference among samples collected with grab field sampling and analyzed for TSS and concentration of fines in SSC. Even though differences are present, the presence of strong correlations between SSC and TSS concentrations provides the opportunity to develop site specific relations to address transport processes not captured by grab field sampling and TSS laboratory analysis methods.

Some connections between importance sampling and enhanced sampling methods in molecular dynamics.

PubMed

Lie, H C; Quer, J

2017-11-21

In molecular dynamics, enhanced sampling methods enable the collection of better statistics of rare events from a reference or target distribution. We show that a large class of these methods is based on the idea of importance sampling from mathematical statistics. We illustrate this connection by comparing the Hartmann-Schütte method for rare event simulation (J. Stat. Mech. Theor. Exp. 2012, P11004) and the Valsson-Parrinello method of variationally enhanced sampling [Phys. Rev. Lett. 113, 090601 (2014)]. We use this connection in order to discuss how recent results from the Monte Carlo methods literature can guide the development of enhanced sampling methods.

Some connections between importance sampling and enhanced sampling methods in molecular dynamics

NASA Astrophysics Data System (ADS)

Lie, H. C.; Quer, J.

2017-11-01

In molecular dynamics, enhanced sampling methods enable the collection of better statistics of rare events from a reference or target distribution. We show that a large class of these methods is based on the idea of importance sampling from mathematical statistics. We illustrate this connection by comparing the Hartmann-Schütte method for rare event simulation (J. Stat. Mech. Theor. Exp. 2012, P11004) and the Valsson-Parrinello method of variationally enhanced sampling [Phys. Rev. Lett. 113, 090601 (2014)]. We use this connection in order to discuss how recent results from the Monte Carlo methods literature can guide the development of enhanced sampling methods.

Rapid detection of Salmonella spp. in food by use of the ISO-GRID hydrophobic grid membrane filter.

PubMed Central

Entis, P; Brodsky, M H; Sharpe, A N; Jarvis, G A

1982-01-01

A rapid hydrophobic grid-membrane filter (HGMF) method was developed and compared with the Health Protection Branch cultural method for the detection of Salmonella spp. in 798 spiked samples and 265 naturally contaminated samples of food. With the HGMF method, Salmonella spp. were isolated from 618 of the spiked samples and 190 of the naturally contaminated samples. The conventional method recovered Salmonella spp. from 622 spiked samples and 204 unspiked samples. The isolation rates from Salmonella-positive samples for the two methods were not significantly different (94.6% overall for the HGMF method and 96.7% for the conventional approach), but the HGMF results were available in only 2 to 3 days after sample receipt compared with 3 to 4 days by the conventional method. Images PMID:7059168

Uniform Sampling Table Method and its Applications II--Evaluating the Uniform Sampling by Experiment.

PubMed

Chen, Yibin; Chen, Jiaxi; Chen, Xuan; Wang, Min; Wang, Wei

2015-01-01

A new method of uniform sampling is evaluated in this paper. The items and indexes were adopted to evaluate the rationality of the uniform sampling. The evaluation items included convenience of operation, uniformity of sampling site distribution, and accuracy and precision of measured results. The evaluation indexes included operational complexity, occupation rate of sampling site in a row and column, relative accuracy of pill weight, and relative deviation of pill weight. They were obtained from three kinds of drugs with different shape and size by four kinds of sampling methods. Gray correlation analysis was adopted to make the comprehensive evaluation by comparing it with the standard method. The experimental results showed that the convenience of uniform sampling method was 1 (100%), odds ratio of occupation rate in a row and column was infinity, relative accuracy was 99.50-99.89%, reproducibility RSD was 0.45-0.89%, and weighted incidence degree exceeded the standard method. Hence, the uniform sampling method was easy to operate, and the selected samples were distributed uniformly. The experimental results demonstrated that the uniform sampling method has good accuracy and reproducibility, which can be put into use in drugs analysis.

Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods

USGS Publications Warehouse

Coes, Alissa L.; Paretti, Nicholas V.; Foreman, William T.; Iverson, Jana L.; Alvarez, David A.

2014-01-01

A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19–23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method.

Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods.

PubMed

Coes, Alissa L; Paretti, Nicholas V; Foreman, William T; Iverson, Jana L; Alvarez, David A

2014-03-01

A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19-23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method. Published by Elsevier B.V.

Lipidomic analysis of biological samples: Comparison of liquid chromatography, supercritical fluid chromatography and direct infusion mass spectrometry methods.

PubMed

Lísa, Miroslav; Cífková, Eva; Khalikova, Maria; Ovčačíková, Magdaléna; Holčapek, Michal

2017-11-24

Lipidomic analysis of biological samples in a clinical research represents challenging task for analytical methods given by the large number of samples and their extreme complexity. In this work, we compare direct infusion (DI) and chromatography - mass spectrometry (MS) lipidomic approaches represented by three analytical methods in terms of comprehensiveness, sample throughput, and validation results for the lipidomic analysis of biological samples represented by tumor tissue, surrounding normal tissue, plasma, and erythrocytes of kidney cancer patients. Methods are compared in one laboratory using the identical analytical protocol to ensure comparable conditions. Ultrahigh-performance liquid chromatography/MS (UHPLC/MS) method in hydrophilic interaction liquid chromatography mode and DI-MS method are used for this comparison as the most widely used methods for the lipidomic analysis together with ultrahigh-performance supercritical fluid chromatography/MS (UHPSFC/MS) method showing promising results in metabolomics analyses. The nontargeted analysis of pooled samples is performed using all tested methods and 610 lipid species within 23 lipid classes are identified. DI method provides the most comprehensive results due to identification of some polar lipid classes, which are not identified by UHPLC and UHPSFC methods. On the other hand, UHPSFC method provides an excellent sensitivity for less polar lipid classes and the highest sample throughput within 10min method time. The sample consumption of DI method is 125 times higher than for other methods, while only 40μL of organic solvent is used for one sample analysis compared to 3.5mL and 4.9mL in case of UHPLC and UHPSFC methods, respectively. Methods are validated for the quantitative lipidomic analysis of plasma samples with one internal standard for each lipid class. Results show applicability of all tested methods for the lipidomic analysis of biological samples depending on the analysis requirements. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevalence of Mixed-Methods Sampling Designs in Social Science Research

ERIC Educational Resources Information Center

Collins, Kathleen M. T.

2006-01-01

The purpose of this mixed-methods study was to document the prevalence of sampling designs utilised in mixed-methods research and to examine the interpretive consistency between interpretations made in mixed-methods studies and the sampling design used. Classification of studies was based on a two-dimensional mixed-methods sampling model. This…

Assessment of the effect of population and diary sampling methods on estimation of school-age children exposure to fine particles.

PubMed

Che, W W; Frey, H Christopher; Lau, Alexis K H

2014-12-01

Population and diary sampling methods are employed in exposure models to sample simulated individuals and their daily activity on each simulation day. Different sampling methods may lead to variations in estimated human exposure. In this study, two population sampling methods (stratified-random and random-random) and three diary sampling methods (random resampling, diversity and autocorrelation, and Markov-chain cluster [MCC]) are evaluated. Their impacts on estimated children's exposure to ambient fine particulate matter (PM2.5 ) are quantified via case studies for children in Wake County, NC for July 2002. The estimated mean daily average exposure is 12.9 μg/m(3) for simulated children using the stratified population sampling method, and 12.2 μg/m(3) using the random sampling method. These minor differences are caused by the random sampling among ages within census tracts. Among the three diary sampling methods, there are differences in the estimated number of individuals with multiple days of exposures exceeding a benchmark of concern of 25 μg/m(3) due to differences in how multiday longitudinal diaries are estimated. The MCC method is relatively more conservative. In case studies evaluated here, the MCC method led to 10% higher estimation of the number of individuals with repeated exposures exceeding the benchmark. The comparisons help to identify and contrast the capabilities of each method and to offer insight regarding implications of method choice. Exposure simulation results are robust to the two population sampling methods evaluated, and are sensitive to the choice of method for simulating longitudinal diaries, particularly when analyzing results for specific microenvironments or for exposures exceeding a benchmark of concern. © 2014 Society for Risk Analysis.

40 CFR 80.8 - Sampling methods for gasoline, diesel fuel, fuel additives, and renewable fuels.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Sampling methods for gasoline, diesel... Provisions § 80.8 Sampling methods for gasoline, diesel fuel, fuel additives, and renewable fuels. The sampling methods specified in this section shall be used to collect samples of gasoline, diesel fuel...

Evaluation of respondent-driven sampling.

PubMed

McCreesh, Nicky; Frost, Simon D W; Seeley, Janet; Katongole, Joseph; Tarsh, Matilda N; Ndunguse, Richard; Jichi, Fatima; Lunel, Natasha L; Maher, Dermot; Johnston, Lisa G; Sonnenberg, Pam; Copas, Andrew J; Hayes, Richard J; White, Richard G

2012-01-01

Respondent-driven sampling is a novel variant of link-tracing sampling for estimating the characteristics of hard-to-reach groups, such as HIV prevalence in sex workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. We evaluated respondent-driven sampling by comparing estimates from a respondent-driven sampling survey with total population data. Total population data on age, tribe, religion, socioeconomic status, sexual activity, and HIV status were available on a population of 2402 male household heads from an open cohort in rural Uganda. A respondent-driven sampling (RDS) survey was carried out in this population, using current methods of sampling (RDS sample) and statistical inference (RDS estimates). Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). We recruited 927 household heads. Full and small RDS samples were largely representative of the total population, but both samples underrepresented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status. Respondent-driven sampling statistical inference methods failed to reduce these biases. Only 31%-37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%-74% of respondent-driven sampling bootstrap 95% confidence intervals included the population proportion. Respondent-driven sampling produced a generally representative sample of this well-connected nonhidden population. However, current respondent-driven sampling inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a respondent-driven sampling survey is unresolved. Respondent-driven sampling should be regarded as a (potentially superior) form of convenience sampling method, and caution is required when interpreting findings based on the sampling method.

Transmission Electron Microscopy (TEM) Sample Preparation of Si(1-x)Gex in c-Plane Sapphire Substrate

NASA Technical Reports Server (NTRS)

Kim, Hyun Jung; Choi, Sang H.; Bae, Hyung-Bin; Lee, Tae Woo

2012-01-01

The National Aeronautics and Space Administration-invented X-ray diffraction (XRD) methods, including the total defect density measurement method and the spatial wafer mapping method, have confirmed super hetero epitaxy growth for rhombohedral single crystalline silicon germanium (Si1-xGex) on a c-plane sapphire substrate. However, the XRD method cannot observe the surface morphology or roughness because of the method s limited resolution. Therefore the authors used transmission electron microscopy (TEM) with samples prepared in two ways, the focused ion beam (FIB) method and the tripod method to study the structure between Si1-xGex and sapphire substrate and Si1?xGex itself. The sample preparation for TEM should be as fast as possible so that the sample should contain few or no artifacts induced by the preparation. The standard sample preparation method of mechanical polishing often requires a relatively long ion milling time (several hours), which increases the probability of inducing defects into the sample. The TEM sampling of the Si1-xGex on sapphire is also difficult because of the sapphire s high hardness and mechanical instability. The FIB method and the tripod method eliminate both problems when performing a cross-section TEM sampling of Si1-xGex on c-plane sapphire, which shows the surface morphology, the interface between film and substrate, and the crystal structure of the film. This paper explains the FIB sampling method and the tripod sampling method, and why sampling Si1-xGex, on a sapphire substrate with TEM, is necessary.

Evaluation of Respondent-Driven Sampling

PubMed Central

McCreesh, Nicky; Frost, Simon; Seeley, Janet; Katongole, Joseph; Tarsh, Matilda Ndagire; Ndunguse, Richard; Jichi, Fatima; Lunel, Natasha L; Maher, Dermot; Johnston, Lisa G; Sonnenberg, Pam; Copas, Andrew J; Hayes, Richard J; White, Richard G

2012-01-01

Background Respondent-driven sampling is a novel variant of link-tracing sampling for estimating the characteristics of hard-to-reach groups, such as HIV prevalence in sex-workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. We evaluated respondent-driven sampling by comparing estimates from a respondent-driven sampling survey with total-population data. Methods Total-population data on age, tribe, religion, socioeconomic status, sexual activity and HIV status were available on a population of 2402 male household-heads from an open cohort in rural Uganda. A respondent-driven sampling (RDS) survey was carried out in this population, employing current methods of sampling (RDS sample) and statistical inference (RDS estimates). Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). Results We recruited 927 household-heads. Full and small RDS samples were largely representative of the total population, but both samples under-represented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status. Respondent-driven-sampling statistical-inference methods failed to reduce these biases. Only 31%-37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%-74% of respondent-driven-sampling bootstrap 95% confidence intervals included the population proportion. Conclusions Respondent-driven sampling produced a generally representative sample of this well-connected non-hidden population. However, current respondent-driven-sampling inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a respondent-driven sampling survey is unresolved. Respondent-driven sampling should be regarded as a (potentially superior) form of convenience-sampling method, and caution is required when interpreting findings based on the sampling method. PMID:22157309

[Sampling methods for PM2.5 from stationary sources: a review].

PubMed

Jiang, Jing-Kun; Deng, Jian-Guo; Li, Zhen; Li, Xing-Hua; Duan, Lei; Hao, Ji-Ming

2014-05-01

The new China national ambient air quality standard has been published in 2012 and will be implemented in 2016. To meet the requirements in this new standard, monitoring and controlling PM2,,5 emission from stationary sources are very important. However, so far there is no national standard method on sampling PM2.5 from stationary sources. Different sampling methods for PM2.5 from stationary sources and relevant international standards were reviewed in this study. It includes the methods for PM2.5 sampling in flue gas and the methods for PM2.5 sampling after dilution. Both advantages and disadvantages of these sampling methods were discussed. For environmental management, the method for PM2.5 sampling in flue gas such as impactor and virtual impactor was suggested as a standard to determine filterable PM2.5. To evaluate environmental and health effects of PM2.5 from stationary sources, standard dilution method for sampling of total PM2.5 should be established.

Comparison of methods for sampling plant bugs on cotton in South Texas (2010)

USDA-ARS?s Scientific Manuscript database

A total of 26 cotton fields were sampled by experienced and inexperienced samplers at 3 growth stages using 5 methods to compare the most efficient and accurate method for sampling plant bugs in cotton. Each of the 5 methods had its own distinct advantages and disadvantages as a sampling method (too...

Advantage of multiple spot urine collections for estimating daily sodium excretion: comparison with two 24-h urine collections as reference.

PubMed

Uechi, Ken; Asakura, Keiko; Ri, Yui; Masayasu, Shizuko; Sasaki, Satoshi

2016-02-01

Several estimation methods for 24-h sodium excretion using spot urine sample have been reported, but accurate estimation at the individual level remains difficult. We aimed to clarify the most accurate method of estimating 24-h sodium excretion with different numbers of available spot urine samples. A total of 370 participants from throughout Japan collected multiple 24-h urine and spot urine samples independently. Participants were allocated randomly into a development and a validation dataset. Two estimation methods were established in the development dataset using the two 24-h sodium excretion samples as reference: the 'simple mean method' estimated by multiplying the sodium-creatinine ratio by predicted 24-h creatinine excretion, whereas the 'regression method' employed linear regression analysis. The accuracy of the two methods was examined by comparing the estimated means and concordance correlation coefficients (CCC) in the validation dataset. Mean sodium excretion by the simple mean method with three spot urine samples was closest to that by 24-h collection (difference: -1.62  mmol/day). CCC with the simple mean method increased with an increased number of spot urine samples at 0.20, 0.31, and 0.42 using one, two, and three samples, respectively. This method with three spot urine samples yielded higher CCC than the regression method (0.40). When only one spot urine sample was available for each study participant, CCC was higher with the regression method (0.36). The simple mean method with three spot urine samples yielded the most accurate estimates of sodium excretion. When only one spot urine sample was available, the regression method was preferable.

Application of the BMWP-Costa Rica biotic index in aquatic biomonitoring: sensitivity to collection method and sampling intensity.

PubMed

Gutiérrez-Fonseca, Pablo E; Lorion, Christopher M

2014-04-01

The use of aquatic macroinvertebrates as bio-indicators in water quality studies has increased considerably over the last decade in Costa Rica, and standard biomonitoring methods have now been formulated at the national level. Nevertheless, questions remain about the effectiveness of different methods of sampling freshwater benthic assemblages, and how sampling intensity may influence biomonitoring results. In this study, we compared the results of qualitative sampling using commonly applied methods with a more intensive quantitative approach at 12 sites in small, lowland streams on the southern Caribbean slope of Costa Rica. Qualitative samples were collected following the official protocol using a strainer during a set time period and macroinvertebrates were field-picked. Quantitative sampling involved collecting ten replicate Surber samples and picking out macroinvertebrates in the laboratory with a stereomicroscope. The strainer sampling method consistently yielded fewer individuals and families than quantitative samples. As a result, site scores calculated using the Biological Monitoring Working Party-Costa Rica (BMWP-CR) biotic index often differed greatly depending on the sampling method. Site water quality classifications using the BMWP-CR index differed between the two sampling methods for 11 of the 12 sites in 2005, and for 9 of the 12 sites in 2006. Sampling intensity clearly had a strong influence on BMWP-CR index scores, as well as perceived differences between reference and impacted sites. Achieving reliable and consistent biomonitoring results for lowland Costa Rican streams may demand intensive sampling and requires careful consideration of sampling methods.

Evaluation of Two Surface Sampling Methods for Microbiological and Chemical Analyses To Assess the Presence of Biofilms in Food Companies.

PubMed

Maes, Sharon; Huu, Son Nguyen; Heyndrickx, Marc; Weyenberg, Stephanie van; Steenackers, Hans; Verplaetse, Alex; Vackier, Thijs; Sampers, Imca; Raes, Katleen; Reu, Koen De

2017-12-01

Biofilms are an important source of contamination in food companies, yet the composition of biofilms in practice is still mostly unknown. The chemical and microbiological characterization of surface samples taken after cleaning and disinfection is very important to distinguish free-living bacteria from the attached bacteria in biofilms. In this study, sampling methods that are potentially useful for both chemical and microbiological analyses of surface samples were evaluated. In the manufacturing facilities of eight Belgian food companies, surfaces were sampled after cleaning and disinfection using two sampling methods: the scraper-flocked swab method and the sponge stick method. Microbiological and chemical analyses were performed on these samples to evaluate the suitability of the sampling methods for the quantification of extracellular polymeric substance components and microorganisms originating from biofilms in these facilities. The scraper-flocked swab method was most suitable for chemical analyses of the samples because the material in these swabs did not interfere with determination of the chemical components. For microbiological enumerations, the sponge stick method was slightly but not significantly more effective than the scraper-flocked swab method. In all but one of the facilities, at least 20% of the sampled surfaces had more than 10 2 CFU/100 cm 2 . Proteins were found in 20% of the chemically analyzed surface samples, and carbohydrates and uronic acids were found in 15 and 8% of the samples, respectively. When chemical and microbiological results were combined, 17% of the sampled surfaces were contaminated with both microorganisms and at least one of the analyzed chemical components; thus, these surfaces were characterized as carrying biofilm. Overall, microbiological contamination in the food industry is highly variable by food sector and even within a facility at various sampling points and sampling times.

40 CFR 261.20 - General.

Code of Federal Regulations, 2010 CFR

2010-07-01

... will consider a sample obtained using any of the applicable sampling methods specified in appendix I to... appendix I sampling methods are not being formally adopted by the Administrator, a person who desires to employ an alternative sampling method is not required to demonstrate the equivalency of his method under...

A new design of groundwater sampling device and its application.

PubMed

Tsai, Yih-jin; Kuo, Ming-ching T

2005-01-01

Compounds in the atmosphere contaminate samples of groundwater. An inexpensive and simple method for collecting groundwater samples is developed to prevent contamination when the background concentration of contaminants is high. This new design of groundwater sampling device involves a glass sampling bottle with a Teflon-lined valve at each end. A cleaned and dried sampling bottle was connected to a low flow-rate peristaltic pump with Teflon tubing and was filled with water. No headspace volume was remained in the sampling bottle. The sample bottle was then packed in a PVC bag to prevent the target component from infiltrating into the water sample through the valves. In this study, groundwater was sampled at six wells using both the conventional method and the improved method. The analysis of trichlorofluoromethane (CFC-11) concentrations at these six wells indicates that all the groundwater samples obtained by the conventional sampling method were contaminated by CFC-11 from the atmosphere. The improved sampling method greatly eliminated the problems of contamination, preservation and quantitative analysis of natural water.

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

PubMed

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.

40 CFR Appendix I to Part 261 - Representative Sampling Methods

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Representative Sampling Methods I Appendix I to Part 261 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES...—Representative Sampling Methods The methods and equipment used for sampling waste materials will vary with the...

Monte Carlo approaches to sampling forested tracts with lines or points

Treesearch

Harry T. Valentine; Jeffrey H. Gove; Timothy G. Gregoire

2001-01-01

Several line- and point-based sampling methods can be employed to estimate the aggregate dimensions of trees standing on a forested tract or pieces of coarse woody debris lying on the forest floor. Line methods include line intersect sampling, horizontal line sampling, and transect relascope sampling; point methods include variable- and fixed-radius plot sampling, and...

Passive Samplers for Investigations of Air Quality: Method Description, Implementation, and Comparison to Alternative Sampling Methods

EPA Science Inventory

This Paper covers the basics of passive sampler design, compares passive samplers to conventional methods of air sampling, and discusses considerations when implementing a passive sampling program. The Paper also discusses field sampling and sample analysis considerations to ensu...

Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

PubMed

Verschave, S H; Levecke, B; Duchateau, L; Vercruysse, J; Charlier, J

2015-06-15

Assessing levels of pasture larval contamination is frequently used to study the population dynamics of the free-living stages of parasitic nematodes of livestock. Direct quantification of infective larvae (L3) on herbage is the most applied method to measure pasture larval contamination. However, herbage collection remains labour intensive and there is a lack of studies addressing the variation induced by the sampling method and the required sample size. The aim of this study was (1) to compare two different sampling methods in terms of pasture larval count results and time required to sample, (2) to assess the amount of variation in larval counts at the level of sample plot, pasture and season, respectively and (3) to calculate the required sample size to assess pasture larval contamination with a predefined precision using random plots across pasture. Eight young stock pastures of different commercial dairy herds were sampled in three consecutive seasons during the grazing season (spring, summer and autumn). On each pasture, herbage samples were collected through both a double-crossed W-transect with samples taken every 10 steps (method 1) and four random located plots of 0.16 m(2) with collection of all herbage within the plot (method 2). The average (± standard deviation (SD)) pasture larval contamination using sampling methods 1 and 2 was 325 (± 479) and 305 (± 444)L3/kg dry herbage (DH), respectively. Large discrepancies in pasture larval counts of the same pasture and season were often seen between methods, but no significant difference (P = 0.38) in larval counts between methods was found. Less time was required to collect samples with method 2. This difference in collection time between methods was most pronounced for pastures with a surface area larger than 1 ha. The variation in pasture larval counts from samples generated by random plot sampling was mainly due to the repeated measurements on the same pasture in the same season (residual variance component = 6.2), rather than due to pasture (variance component = 0.55) or season (variance component = 0.15). Using the observed distribution of L3, the required sample size (i.e. number of plots per pasture) for sampling a pasture through random plots with a particular precision was simulated. A higher relative precision was acquired when estimating PLC on pastures with a high larval contamination and a low level of aggregation compared to pastures with a low larval contamination when the same sample size was applied. In the future, herbage sampling through random plots across pasture (method 2) seems a promising method to develop further as no significant difference in counts between the methods was found and this method was less time consuming. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of preprocessing methods and storage times for touch DNA samples

PubMed Central

Dong, Hui; Wang, Jing; Zhang, Tao; Ge, Jian-ye; Dong, Ying-qiang; Sun, Qi-fan; Liu, Chao; Li, Cai-xia

2017-01-01

Aim To select appropriate preprocessing methods for different substrates by comparing the effects of four different preprocessing methods on touch DNA samples and to determine the effect of various storage times on the results of touch DNA sample analysis. Method Hand touch DNA samples were used to investigate the detection and inspection results of DNA on different substrates. Four preprocessing methods, including the direct cutting method, stubbing procedure, double swab technique, and vacuum cleaner method, were used in this study. DNA was extracted from mock samples with four different preprocessing methods. The best preprocess protocol determined from the study was further used to compare performance after various storage times. DNA extracted from all samples was quantified and amplified using standard procedures. Results The amounts of DNA and the number of alleles detected on the porous substrates were greater than those on the non-porous substrates. The performances of the four preprocessing methods varied with different substrates. The direct cutting method displayed advantages for porous substrates, and the vacuum cleaner method was advantageous for non-porous substrates. No significant degradation trend was observed as the storage times increased. Conclusion Different substrates require the use of different preprocessing method in order to obtain the highest DNA amount and allele number from touch DNA samples. This study provides a theoretical basis for explorations of touch DNA samples and may be used as a reference when dealing with touch DNA samples in case work. PMID:28252870

Photoacoustic spectroscopy sample array vessels and photoacoustic spectroscopy methods for using the same

DOEpatents

Amonette, James E.; Autrey, S. Thomas; Foster-Mills, Nancy S.

2006-02-14

Methods and apparatus for simultaneous or sequential, rapid analysis of multiple samples by photoacoustic spectroscopy are disclosed. Particularly, a photoacoustic spectroscopy sample array vessel including a vessel body having multiple sample cells connected thereto is disclosed. At least one acoustic detector is acoustically positioned near the sample cells. Methods for analyzing the multiple samples in the sample array vessels using photoacoustic spectroscopy are provided.

7 CFR 58.812 - Methods of sample analysis.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Methods of sample analysis. 58.812 Section 58.812... Procedures § 58.812 Methods of sample analysis. Samples shall be tested according to the applicable methods of laboratory analysis contained in either DA Instruction 918-RL, as issued by the USDA, Agricultural...

7 CFR 58.245 - Method of sample analysis.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Method of sample analysis. 58.245 Section 58.245... Procedures § 58.245 Method of sample analysis. Samples shall be tested according to the applicable methods of laboratory analysis contained in either DA Instruction 918-RL as issued by the USDA, Agricultural Marketing...

Environmental Asbestos Assessment Manual: Superfund Method for the Determination of Asbestos in Ambient Air, Part 1: Method

EPA Science Inventory

This is a sampling and analysis method for the determination of asbestos in air. Samples are analyzed by transmission electron microscopy (TEM). Although a small subset of samples are to be prepared using a direct procedure, the majority of samples analyzed using this method wil...

An improved sampling method of complex network

NASA Astrophysics Data System (ADS)

Gao, Qi; Ding, Xintong; Pan, Feng; Li, Weixing

2014-12-01

Sampling subnet is an important topic of complex network research. Sampling methods influence the structure and characteristics of subnet. Random multiple snowball with Cohen (RMSC) process sampling which combines the advantages of random sampling and snowball sampling is proposed in this paper. It has the ability to explore global information and discover the local structure at the same time. The experiments indicate that this novel sampling method could keep the similarity between sampling subnet and original network on degree distribution, connectivity rate and average shortest path. This method is applicable to the situation where the prior knowledge about degree distribution of original network is not sufficient.

Equilibrium Molecular Thermodynamics from Kirkwood Sampling

PubMed Central

2015-01-01

We present two methods for barrierless equilibrium sampling of molecular systems based on the recently proposed Kirkwood method (J. Chem. Phys.2009, 130, 134102). Kirkwood sampling employs low-order correlations among internal coordinates of a molecule for random (or non-Markovian) sampling of the high dimensional conformational space. This is a geometrical sampling method independent of the potential energy surface. The first method is a variant of biased Monte Carlo, where Kirkwood sampling is used for generating trial Monte Carlo moves. Using this method, equilibrium distributions corresponding to different temperatures and potential energy functions can be generated from a given set of low-order correlations. Since Kirkwood samples are generated independently, this method is ideally suited for massively parallel distributed computing. The second approach is a variant of reservoir replica exchange, where Kirkwood sampling is used to construct a reservoir of conformations, which exchanges conformations with the replicas performing equilibrium sampling corresponding to different thermodynamic states. Coupling with the Kirkwood reservoir enhances sampling by facilitating global jumps in the conformational space. The efficiency of both methods depends on the overlap of the Kirkwood distribution with the target equilibrium distribution. We present proof-of-concept results for a model nine-atom linear molecule and alanine dipeptide. PMID:25915525

A novel sampling method for multiple multiscale targets from scattering amplitudes at a fixed frequency

NASA Astrophysics Data System (ADS)

Liu, Xiaodong

2017-08-01

A sampling method by using scattering amplitude is proposed for shape and location reconstruction in inverse acoustic scattering problems. Only matrix multiplication is involved in the computation, thus the novel sampling method is very easy and simple to implement. With the help of the factorization of the far field operator, we establish an inf-criterion for characterization of underlying scatterers. This result is then used to give a lower bound of the proposed indicator functional for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functional decays like the bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functional continuously depends on the scattering amplitude, this further implies that the novel sampling method is extremely stable with respect to errors in the data. Different to the classical sampling method such as the linear sampling method or the factorization method, from the numerical point of view, the novel indicator takes its maximum near the boundary of the underlying target and decays like the bessel functions as the sampling points go away from the boundary. The numerical simulations also show that the proposed sampling method can deal with multiple multiscale case, even the different components are close to each other.

A general method to determine sampling windows for nonlinear mixed effects models with an application to population pharmacokinetic studies.

PubMed

Foo, Lee Kien; McGree, James; Duffull, Stephen

2012-01-01

Optimal design methods have been proposed to determine the best sampling times when sparse blood sampling is required in clinical pharmacokinetic studies. However, the optimal blood sampling time points may not be feasible in clinical practice. Sampling windows, a time interval for blood sample collection, have been proposed to provide flexibility in blood sampling times while preserving efficient parameter estimation. Because of the complexity of the population pharmacokinetic models, which are generally nonlinear mixed effects models, there is no analytical solution available to determine sampling windows. We propose a method for determination of sampling windows based on MCMC sampling techniques. The proposed method attains a stationary distribution rapidly and provides time-sensitive windows around the optimal design points. The proposed method is applicable to determine sampling windows for any nonlinear mixed effects model although our work focuses on an application to population pharmacokinetic models. Copyright © 2012 John Wiley & Sons, Ltd.

At convenience and systematic random sampling: effects on the prognostic value of nuclear area assessments in breast cancer patients.

PubMed

Jannink, I; Bennen, J N; Blaauw, J; van Diest, P J; Baak, J P

1995-01-01

This study compares the influence of two different nuclear sampling methods on the prognostic value of assessments of mean and standard deviation of nuclear area (MNA, SDNA) in 191 consecutive invasive breast cancer patients with long term follow up. The first sampling method used was 'at convenience' sampling (ACS); the second, systematic random sampling (SRS). Both sampling methods were tested with a sample size of 50 nuclei (ACS-50 and SRS-50). To determine whether, besides the sampling methods, sample size had impact on prognostic value as well, the SRS method was also tested using a sample size of 100 nuclei (SRS-100). SDNA values were systematically lower for ACS, obviously due to (unconsciously) not including small and large nuclei. Testing prognostic value of a series of cut off points, MNA and SDNA values assessed by the SRS method were prognostically significantly stronger than the values obtained by the ACS method. This was confirmed in Cox regression analysis. For the MNA, the Mantel-Cox p-values from SRS-50 and SRS-100 measurements were not significantly different. However, for the SDNA, SRS-100 yielded significantly lower p-values than SRS-50. In conclusion, compared with the 'at convenience' nuclear sampling method, systematic random sampling of nuclei is not only superior with respect to reproducibility of results, but also provides a better prognostic value in patients with invasive breast cancer.

Comparability among four invertebrate sampling methods, Fountain Creek Basin, Colorado, 2010-2012

USGS Publications Warehouse

Zuellig, Robert E.; Bruce, James F.; Stogner, Sr., Robert W.; Brown, Krystal D.

2014-01-01

The U.S. Geological Survey, in cooperation with Colorado Springs City Engineering and Colorado Springs Utilities, designed a study to determine if sampling method and sample timing resulted in comparable samples and assessments of biological condition. To accomplish this task, annual invertebrate samples were collected concurrently using four sampling methods at 15 U.S. Geological Survey streamflow gages in the Fountain Creek basin from 2010 to 2012. Collectively, the four methods are used by local (U.S. Geological Survey cooperative monitoring program) and State monitoring programs (Colorado Department of Public Health and Environment) in the Fountain Creek basin to produce two distinct sample types for each program that target single-and multiple-habitats. This study found distinguishable differences between single-and multi-habitat sample types using both community similarities and multi-metric index values, while methods from each program within sample type were comparable. This indicates that the Colorado Department of Public Health and Environment methods were compatible with the cooperative monitoring program methods within multi-and single-habitat sample types. Comparisons between September and October samples found distinguishable differences based on community similarities for both sample types, whereas only differences were found for single-habitat samples when multi-metric index values were considered. At one site, differences between September and October index values from single-habitat samples resulted in opposing assessments of biological condition. Direct application of the results to inform the revision of the existing Fountain Creek basin U.S. Geological Survey cooperative monitoring program are discussed.

Calculating Confidence, Uncertainty, and Numbers of Samples When Using Statistical Sampling Approaches to Characterize and Clear Contaminated Areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piepel, Gregory F.; Matzke, Brett D.; Sego, Landon H.

2013-04-27

This report discusses the methodology, formulas, and inputs needed to make characterization and clearance decisions for Bacillus anthracis-contaminated and uncontaminated (or decontaminated) areas using a statistical sampling approach. Specifically, the report includes the methods and formulas for calculating the • number of samples required to achieve a specified confidence in characterization and clearance decisions • confidence in making characterization and clearance decisions for a specified number of samples for two common statistically based environmental sampling approaches. In particular, the report addresses an issue raised by the Government Accountability Office by providing methods and formulas to calculate the confidence that amore » decision area is uncontaminated (or successfully decontaminated) if all samples collected according to a statistical sampling approach have negative results. Key to addressing this topic is the probability that an individual sample result is a false negative, which is commonly referred to as the false negative rate (FNR). The two statistical sampling approaches currently discussed in this report are 1) hotspot sampling to detect small isolated contaminated locations during the characterization phase, and 2) combined judgment and random (CJR) sampling during the clearance phase. Typically if contamination is widely distributed in a decision area, it will be detectable via judgment sampling during the characterization phrase. Hotspot sampling is appropriate for characterization situations where contamination is not widely distributed and may not be detected by judgment sampling. CJR sampling is appropriate during the clearance phase when it is desired to augment judgment samples with statistical (random) samples. The hotspot and CJR statistical sampling approaches are discussed in the report for four situations: 1. qualitative data (detect and non-detect) when the FNR = 0 or when using statistical sampling methods that account for FNR > 0 2. qualitative data when the FNR > 0 but statistical sampling methods are used that assume the FNR = 0 3. quantitative data (e.g., contaminant concentrations expressed as CFU/cm2) when the FNR = 0 or when using statistical sampling methods that account for FNR > 0 4. quantitative data when the FNR > 0 but statistical sampling methods are used that assume the FNR = 0. For Situation 2, the hotspot sampling approach provides for stating with Z% confidence that a hotspot of specified shape and size with detectable contamination will be found. Also for Situation 2, the CJR approach provides for stating with X% confidence that at least Y% of the decision area does not contain detectable contamination. Forms of these statements for the other three situations are discussed in Section 2.2. Statistical methods that account for FNR > 0 currently only exist for the hotspot sampling approach with qualitative data (or quantitative data converted to qualitative data). This report documents the current status of methods and formulas for the hotspot and CJR sampling approaches. Limitations of these methods are identified. Extensions of the methods that are applicable when FNR = 0 to account for FNR > 0, or to address other limitations, will be documented in future revisions of this report if future funding supports the development of such extensions. For quantitative data, this report also presents statistical methods and formulas for 1. quantifying the uncertainty in measured sample results 2. estimating the true surface concentration corresponding to a surface sample 3. quantifying the uncertainty of the estimate of the true surface concentration. All of the methods and formulas discussed in the report were applied to example situations to illustrate application of the methods and interpretation of the results.« less

A Sequential Optimization Sampling Method for Metamodels with Radial Basis Functions

PubMed Central

Pan, Guang; Ye, Pengcheng; Yang, Zhidong

2014-01-01

Metamodels have been widely used in engineering design to facilitate analysis and optimization of complex systems that involve computationally expensive simulation programs. The accuracy of metamodels is strongly affected by the sampling methods. In this paper, a new sequential optimization sampling method is proposed. Based on the new sampling method, metamodels can be constructed repeatedly through the addition of sampling points, namely, extrema points of metamodels and minimum points of density function. Afterwards, the more accurate metamodels would be constructed by the procedure above. The validity and effectiveness of proposed sampling method are examined by studying typical numerical examples. PMID:25133206

Validated Test Method 5030C: Purge-and-Trap for Aqueous Samples

EPA Pesticide Factsheets

This method describes a purge-and-trap procedure for the analysis of volatile organic compoundsin aqueous samples & water miscible liquid samples. It also describes the analysis of high concentration soil and waste sample extracts prepared in Method 5035.

Photoacoustic spectroscopy sample array vessel and photoacoustic spectroscopy method for using the same

DOEpatents

Amonette, James E.; Autrey, S. Thomas; Foster-Mills, Nancy S.; Green, David

2005-03-29

Methods and apparatus for analysis of multiple samples by photoacoustic spectroscopy are disclosed. Particularly, a photoacoustic spectroscopy sample array vessel including a vessel body having multiple sample cells connected thereto is disclosed. At least one acoustic detector is acoustically coupled with the vessel body. Methods for analyzing the multiple samples in the sample array vessels using photoacoustic spectroscopy are provided.

Evaluation of common methods for sampling invertebrate pollinator assemblages: net sampling out-perform pan traps.

PubMed

Popic, Tony J; Davila, Yvonne C; Wardle, Glenda M

2013-01-01

Methods for sampling ecological assemblages strive to be efficient, repeatable, and representative. Unknowingly, common methods may be limited in terms of revealing species function and so of less value for comparative studies. The global decline in pollination services has stimulated surveys of flower-visiting invertebrates, using pan traps and net sampling. We explore the relative merits of these two methods in terms of species discovery, quantifying abundance, function, and composition, and responses of species to changing floral resources. Using a spatially-nested design we sampled across a 5000 km(2) area of arid grasslands, including 432 hours of net sampling and 1296 pan trap-days, between June 2010 and July 2011. Net sampling yielded 22% more species and 30% higher abundance than pan traps, and better reflected the spatio-temporal variation of floral resources. Species composition differed significantly between methods; from 436 total species, 25% were sampled by both methods, 50% only by nets, and the remaining 25% only by pans. Apart from being less comprehensive, if pan traps do not sample flower-visitors, the link to pollination is questionable. By contrast, net sampling functionally linked species to pollination through behavioural observations of flower-visitation interaction frequency. Netted specimens are also necessary for evidence of pollen transport. Benefits of net-based sampling outweighed minor differences in overall sampling effort. As pan traps and net sampling methods are not equivalent for sampling invertebrate-flower interactions, we recommend net sampling of invertebrate pollinator assemblages, especially if datasets are intended to document declines in pollination and guide measures to retain this important ecosystem service.

Evaluation of Common Methods for Sampling Invertebrate Pollinator Assemblages: Net Sampling Out-Perform Pan Traps

PubMed Central

Popic, Tony J.; Davila, Yvonne C.; Wardle, Glenda M.

2013-01-01

Methods for sampling ecological assemblages strive to be efficient, repeatable, and representative. Unknowingly, common methods may be limited in terms of revealing species function and so of less value for comparative studies. The global decline in pollination services has stimulated surveys of flower-visiting invertebrates, using pan traps and net sampling. We explore the relative merits of these two methods in terms of species discovery, quantifying abundance, function, and composition, and responses of species to changing floral resources. Using a spatially-nested design we sampled across a 5000 km2 area of arid grasslands, including 432 hours of net sampling and 1296 pan trap-days, between June 2010 and July 2011. Net sampling yielded 22% more species and 30% higher abundance than pan traps, and better reflected the spatio-temporal variation of floral resources. Species composition differed significantly between methods; from 436 total species, 25% were sampled by both methods, 50% only by nets, and the remaining 25% only by pans. Apart from being less comprehensive, if pan traps do not sample flower-visitors, the link to pollination is questionable. By contrast, net sampling functionally linked species to pollination through behavioural observations of flower-visitation interaction frequency. Netted specimens are also necessary for evidence of pollen transport. Benefits of net-based sampling outweighed minor differences in overall sampling effort. As pan traps and net sampling methods are not equivalent for sampling invertebrate-flower interactions, we recommend net sampling of invertebrate pollinator assemblages, especially if datasets are intended to document declines in pollination and guide measures to retain this important ecosystem service. PMID:23799127

A new sampling scheme for developing metamodels with the zeros of Chebyshev polynomials

NASA Astrophysics Data System (ADS)

Wu, Jinglai; Luo, Zhen; Zhang, Nong; Zhang, Yunqing

2015-09-01

The accuracy of metamodelling is determined by both the sampling and approximation. This article proposes a new sampling method based on the zeros of Chebyshev polynomials to capture the sampling information effectively. First, the zeros of one-dimensional Chebyshev polynomials are applied to construct Chebyshev tensor product (CTP) sampling, and the CTP is then used to construct high-order multi-dimensional metamodels using the 'hypercube' polynomials. Secondly, the CTP sampling is further enhanced to develop Chebyshev collocation method (CCM) sampling, to construct the 'simplex' polynomials. The samples of CCM are randomly and directly chosen from the CTP samples. Two widely studied sampling methods, namely the Smolyak sparse grid and Hammersley, are used to demonstrate the effectiveness of the proposed sampling method. Several numerical examples are utilized to validate the approximation accuracy of the proposed metamodel under different dimensions.

A "three-in-one" sample preparation method for simultaneous determination of B-group water-soluble vitamins in infant formula using VitaFast(®) kits.

PubMed

Zhang, Heng; Lan, Fang; Shi, Yupeng; Wan, Zhi-Gang; Yue, Zhen-Feng; Fan, Fang; Lin, Yan-Kui; Tang, Mu-Jin; Lv, Jing-Zhang; Xiao, Tan; Yi, Changqing

2014-06-15

VitaFast(®) test kits designed for the microbiological assay in microtiter plate format can be applied to quantitative determination of B-group water-soluble vitamins such as vitamin B12, folic acid and biotin, et al. Compared to traditional microbiological methods, VitaFast(®) kits significantly reduce sample processing time and provide greater reliability, higher productivity and better accuracy. Recently, simultaneous determination of vitamin B12, folic acid and biotin in one sample is urgently required when evaluating the quality of infant formulae in our practical work. However, the present sample preparation protocols which are developed for individual test systems, are incompatible with simultaneous determination of several analytes. To solve this problem, a novel "three-in-one" sample preparation method is herein developed for simultaneous determination of B-group water-soluble vitamins using VitaFast(®) kits. The performance of this novel "three-in-one" sample preparation method was systematically evaluated through comparing with individual sample preparation protocols. The experimental results of the assays which employed "three-in-one" sample preparation method were in good agreement with those obtained from conventional VitaFast(®) extraction methods, indicating that the proposed "three-in-one" sample preparation method is applicable to the present three VitaFast(®) vitamin test systems, thus offering a promising alternative for the three independent sample preparation methods. The proposed new sample preparation method will significantly improve the efficiency of infant formulae inspection. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surveying immigrants without sampling frames - evaluating the success of alternative field methods.

PubMed

Reichel, David; Morales, Laura

2017-01-01

This paper evaluates the sampling methods of an international survey, the Immigrant Citizens Survey, which aimed at surveying immigrants from outside the European Union (EU) in 15 cities in seven EU countries. In five countries, no sample frame was available for the target population. Consequently, alternative ways to obtain a representative sample had to be found. In three countries 'location sampling' was employed, while in two countries traditional methods were used with adaptations to reach the target population. The paper assesses the main methodological challenges of carrying out a survey among a group of immigrants for whom no sampling frame exists. The samples of the survey in these five countries are compared to results of official statistics in order to assess the accuracy of the samples obtained through the different sampling methods. It can be shown that alternative sampling methods can provide meaningful results in terms of core demographic characteristics although some estimates differ to some extent from the census results.

Effects of sampling methods on the quantity and quality of dissolved organic matter in sediment pore waters as revealed by absorption and fluorescence spectroscopy.

PubMed

Chen, Meilian; Lee, Jong-Hyeon; Hur, Jin

2015-10-01

Despite literature evidence suggesting the importance of sampling methods on the properties of sediment pore waters, their effects on the dissolved organic matter (PW-DOM) have been unexplored to date. Here, we compared the effects of two commonly used sampling methods (i.e., centrifuge and Rhizon sampler) on the characteristics of PW-DOM for the first time. The bulk dissolved organic carbon (DOC), ultraviolet-visible (UV-Vis) absorption, and excitation-emission matrixes coupled with parallel factor analysis (EEM-PARAFAC) of the PW-DOM samples were compared for the two sampling methods with the sediments from minimal to severely contaminated sites. The centrifuged samples were found to have higher average values of DOC, UV absorption, and protein-like EEM-PARAFAC components. The samples collected with the Rhizon sampler, however, exhibited generally more humified characteristics than the centrifuged ones, implying a preferential collection of PW-DOM with respect to the sampling methods. Furthermore, the differences between the two sampling methods seem more pronounced in relatively more polluted sites. Our observations were possibly explained by either the filtration effect resulting from the smaller pore size of the Rhizon sampler or the desorption of DOM molecules loosely bound to minerals during centrifugation, or both. Our study suggests that consistent use of one sampling method is crucial for PW-DOM studies and also that caution should be taken in the comparison of data collected with different sampling methods.

77 FR 3230 - Codex Alimentarius Commission: Meeting of the Codex Committee on Methods of Analysis and Sampling

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-23

... Alimentarius Commission: Meeting of the Codex Committee on Methods of Analysis and Sampling AGENCY: Office of... discussed at the 33rd Session of the Codex Committee on Methods of Analysis and Sampling (CCMAS) of the... the criteria appropriate to Codex Methods of Analysis and Sampling; serving as a coordinating body for...

76 FR 3603 - Codex Alimentarius Commission: Meeting of the Codex Committee on Methods of Analysis and Sampling

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-20

... Alimentarius Commission: Meeting of the Codex Committee on Methods of Analysis and Sampling AGENCY: Office of... discussed at the 32nd session of the Codex Committee on Methods of Analysis and Sampling (CCMAS) of the... appropriate to Codex Methods of Analysis and Sampling; serving as a coordinating body for Codex with other...

Intra prediction using face continuity in 360-degree video coding

NASA Astrophysics Data System (ADS)

Hanhart, Philippe; He, Yuwen; Ye, Yan

2017-09-01

This paper presents a new reference sample derivation method for intra prediction in 360-degree video coding. Unlike the conventional reference sample derivation method for 2D video coding, which uses the samples located directly above and on the left of the current block, the proposed method considers the spherical nature of 360-degree video when deriving reference samples located outside the current face to which the block belongs, and derives reference samples that are geometric neighbors on the sphere. The proposed reference sample derivation method was implemented in the Joint Exploration Model 3.0 (JEM-3.0) for the cubemap projection format. Simulation results for the all intra configuration show that, when compared with the conventional reference sample derivation method, the proposed method gives, on average, luma BD-rate reduction of 0.3% in terms of the weighted spherical PSNR (WS-PSNR) and spherical PSNR (SPSNR) metrics.

7 CFR 29.110 - Method of sampling.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Method of sampling. 29.110 Section 29.110 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.110 Method of sampling. In sampling tobacco...

7 CFR 29.110 - Method of sampling.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Method of sampling. 29.110 Section 29.110 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.110 Method of sampling. In sampling tobacco...

Analysis of methods commonly used in biomedicine for treatment versus control comparison of very small samples.

PubMed

Ristić-Djurović, Jasna L; Ćirković, Saša; Mladenović, Pavle; Romčević, Nebojša; Trbovich, Alexander M

2018-04-01

A rough estimate indicated that use of samples of size not larger than ten is not uncommon in biomedical research and that many of such studies are limited to strong effects due to sample sizes smaller than six. For data collected from biomedical experiments it is also often unknown if mathematical requirements incorporated in the sample comparison methods are satisfied. Computer simulated experiments were used to examine performance of methods for qualitative sample comparison and its dependence on the effectiveness of exposure, effect intensity, distribution of studied parameter values in the population, and sample size. The Type I and Type II errors, their average, as well as the maximal errors were considered. The sample size 9 and the t-test method with p = 5% ensured error smaller than 5% even for weak effects. For sample sizes 6-8 the same method enabled detection of weak effects with errors smaller than 20%. If the sample sizes were 3-5, weak effects could not be detected with an acceptable error; however, the smallest maximal error in the most general case that includes weak effects is granted by the standard error of the mean method. The increase of sample size from 5 to 9 led to seven times more accurate detection of weak effects. Strong effects were detected regardless of the sample size and method used. The minimal recommended sample size for biomedical experiments is 9. Use of smaller sizes and the method of their comparison should be justified by the objective of the experiment. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of individual and pooled sampling methods for detecting bacterial pathogens of fish

USGS Publications Warehouse

Mumford, Sonia; Patterson, Chris; Evered, J.; Brunson, Ray; Levine, J.; Winton, J.

2005-01-01

Examination of finfish populations for viral and bacterial pathogens is an important component of fish disease control programs worldwide. Two methods are commonly used for collecting tissue samples for bacteriological culture, the currently accepted standards for detection of bacterial fish pathogens. The method specified in the Office International des Epizooties Manual of Diagnostic Tests for Aquatic Animals permits combining renal and splenic tissues from as many as 5 fish into pooled samples. The American Fisheries Society (AFS) Blue Book/US Fish and Wildlife Service (USFWS) Inspection Manual specifies the use of a bacteriological loop for collecting samples from the kidney of individual fish. An alternative would be to more fully utilize the pooled samples taken for virology. If implemented, this approach would provide substantial savings in labor and materials. To compare the relative performance of the AFS/USFWS method and this alternative approach, cultures of Yersinia ruckeri were used to establish low-level infections in groups of rainbow trout (Oncorhynchus mykiss) that were sampled by both methods. Yersinia ruckeri was cultured from 22 of 37 groups by at least 1 method. The loop method yielded 18 positive groups, with 1 group positive in the loop samples but negative in the pooled samples. The pooled samples produced 21 positive groups, with 4 groups positive in the pooled samples but negative in the loop samples. There was statistically significant agreement (Spearman coefficient 0.80, P < 0.001) in the relative ability of the 2 sampling methods to permit detection of low-level bacterial infections of rainbow trout.

Neutron activation analysis of certified samples by the absolute method

NASA Astrophysics Data System (ADS)

Kadem, F.; Belouadah, N.; Idiri, Z.

2015-07-01

The nuclear reactions analysis technique is mainly based on the relative method or the use of activation cross sections. In order to validate nuclear data for the calculated cross section evaluated from systematic studies, we used the neutron activation analysis technique (NAA) to determine the various constituent concentrations of certified samples for animal blood, milk and hay. In this analysis, the absolute method is used. The neutron activation technique involves irradiating the sample and subsequently performing a measurement of the activity of the sample. The fundamental equation of the activation connects several physical parameters including the cross section that is essential for the quantitative determination of the different elements composing the sample without resorting to the use of standard sample. Called the absolute method, it allows a measurement as accurate as the relative method. The results obtained by the absolute method showed that the values are as precise as the relative method requiring the use of standard sample for each element to be quantified.

Application of work sampling technique to analyze logging operations.

Treesearch

Edwin S. Miyata; Helmuth M. Steinhilb; Sharon A. Winsauer

1981-01-01

Discusses the advantages and disadvantages of various time study methods for determining efficiency and productivity in logging. The work sampling method is compared with the continuous time-study method. Gives the feasibility, capability, and limitation of the work sampling method.

Methods of sampling airborne fungi in working environments of waste treatment facilities.

PubMed

Černá, Kristýna; Wittlingerová, Zdeňka; Zimová, Magdaléna; Janovský, Zdeněk

2016-01-01

The objective of the present study was to evaluate and compare the efficiency of a filter based sampling method and a high volume sampling method for sampling airborne culturable fungi present in waste sorting facilities. Membrane filters method was compared with surface air system method. The selected sampling methods were modified and tested in 2 plastic waste sorting facilities. The total number of colony-forming units (CFU)/m3 of airborne fungi was dependent on the type of sampling device, on the time of sampling, which was carried out every hour from the beginning of the work shift, and on the type of cultivation medium (p < 0.001). Detected concentrations of airborne fungi ranged 2×102-1.7×106 CFU/m3 when using the membrane filters (MF) method, and 3×102-6.4×104 CFU/m3 when using the surface air system (SAS) method. Both methods showed comparable sensitivity to the fluctuations of the concentrations of airborne fungi during the work shifts. The SAS method is adequate for a fast indicative determination of concentration of airborne fungi. The MF method is suitable for thorough assessment of working environment contamination by airborne fungi. Therefore we recommend the MF method for the implementation of a uniform standard methodology of airborne fungi sampling in working environments of waste treatment facilities. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

[Study of spatial stratified sampling strategy of Oncomelania hupensis snail survey based on plant abundance].

PubMed

Xun-Ping, W; An, Z

2017-07-27

Objective To optimize and simplify the survey method of Oncomelania hupensis snails in marshland endemic regions of schistosomiasis, so as to improve the precision, efficiency and economy of the snail survey. Methods A snail sampling strategy (Spatial Sampling Scenario of Oncomelania based on Plant Abundance, SOPA) which took the plant abundance as auxiliary variable was explored and an experimental study in a 50 m×50 m plot in a marshland in the Poyang Lake region was performed. Firstly, the push broom surveyed data was stratified into 5 layers by the plant abundance data; then, the required numbers of optimal sampling points of each layer through Hammond McCullagh equation were calculated; thirdly, every sample point in the line with the Multiple Directional Interpolation (MDI) placement scheme was pinpointed; and finally, the comparison study among the outcomes of the spatial random sampling strategy, the traditional systematic sampling method, the spatial stratified sampling method, Sandwich spatial sampling and inference and SOPA was performed. Results The method (SOPA) proposed in this study had the minimal absolute error of 0.213 8; and the traditional systematic sampling method had the largest estimate, and the absolute error was 0.924 4. Conclusion The snail sampling strategy (SOPA) proposed in this study obtains the higher estimation accuracy than the other four methods.

Extending the solvent-free MALDI sample preparation method.

PubMed

Hanton, Scott D; Parees, David M

2005-01-01

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is an important technique to characterize many different materials, including synthetic polymers. MALDI mass spectral data can be used to determine the polymer average molecular weights, repeat units, and end groups. One of the key issues in traditional MALDI sample preparation is making good solutions of the analyte and the matrix. Solvent-free sample preparation methods have been developed to address these issues. Previous results of solvent-free or dry prepared samples show some advantages over traditional wet sample preparation methods. Although the results of the published solvent-free sample preparation methods produced excellent mass spectra, we found the method to be very time-consuming, with significant tool cleaning, which presents a significant possibility of cross contamination. To address these issues, we developed an extension of the solvent-free method that replaces the mortar and pestle grinding with ball milling the sample in a glass vial with two small steel balls. This new method generates mass spectra with equal quality of the previous methods, but has significant advantages in productivity, eliminates cross contamination, and is applicable to liquid and soft or waxy analytes.

Configurations and calibration methods for passive sampling techniques.

PubMed

Ouyang, Gangfeng; Pawliszyn, Janusz

2007-10-19

Passive sampling technology has developed very quickly in the past 15 years, and is widely used for the monitoring of pollutants in different environments. The design and quantification of passive sampling devices require an appropriate calibration method. Current calibration methods that exist for passive sampling, including equilibrium extraction, linear uptake, and kinetic calibration, are presented in this review. A number of state-of-the-art passive sampling devices that can be used for aqueous and air monitoring are introduced according to their calibration methods.

IAEA Sampling Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geist, William H.

2017-09-15

The objectives for this presentation are to describe the method that the IAEA uses to determine a sampling plan for nuclear material measurements; describe the terms detection probability and significant quantity; list the three nuclear materials measurement types; describe the sampling method applied to an item facility; and describe multiple method sampling.

Surface sampling techniques for 3D object inspection

NASA Astrophysics Data System (ADS)

Shih, Chihhsiong S.; Gerhardt, Lester A.

1995-03-01

While the uniform sampling method is quite popular for pointwise measurement of manufactured parts, this paper proposes three novel sampling strategies which emphasize 3D non-uniform inspection capability. They are: (a) the adaptive sampling, (b) the local adjustment sampling, and (c) the finite element centroid sampling techniques. The adaptive sampling strategy is based on a recursive surface subdivision process. Two different approaches are described for this adaptive sampling strategy. One uses triangle patches while the other uses rectangle patches. Several real world objects were tested using these two algorithms. Preliminary results show that sample points are distributed more closely around edges, corners, and vertices as desired for many classes of objects. Adaptive sampling using triangle patches is shown to generally perform better than both uniform and adaptive sampling using rectangle patches. The local adjustment sampling strategy uses a set of predefined starting points and then finds the local optimum position of each nodal point. This method approximates the object by moving the points toward object edges and corners. In a hybrid approach, uniform points sets and non-uniform points sets, first preprocessed by the adaptive sampling algorithm on a real world object were then tested using the local adjustment sampling method. The results show that the initial point sets when preprocessed by adaptive sampling using triangle patches, are moved the least amount of distance by the subsequently applied local adjustment method, again showing the superiority of this method. The finite element sampling technique samples the centroids of the surface triangle meshes produced from the finite element method. The performance of this algorithm was compared to that of the adaptive sampling using triangular patches. The adaptive sampling with triangular patches was once again shown to be better on different classes of objects.

Methods of analyzing crude oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooks, Robert Graham; Jjunju, Fred Paul Mark; Li, Anyin

The invention generally relates to methods of analyzing crude oil. In certain embodiments, methods of the invention involve obtaining a crude oil sample, and subjecting the crude oil sample to mass spectrometry analysis. In certain embodiments, the method is performed without any sample pre-purification steps.

Volatile organic compounds: sampling methods and their worldwide profile in ambient air.

PubMed

Kumar, Anuj; Víden, Ivan

2007-08-01

The atmosphere is a particularly difficult analytical system because of the very low levels of substances to be analysed, sharp variations in pollutant levels with time and location, differences in wind, temperature and humidity. This makes the selection of an efficient sampling technique for air analysis a key step to reliable results. Generally, methods for volatile organic compounds sampling include collection of the whole air or preconcentration of samples on adsorbents. All the methods vary from each other according to the sampling technique, type of sorbent, method of extraction and identification technique. In this review paper we discuss various important aspects for sampling of volatile organic compounds by the widely used and advanced sampling methods. Characteristics of various adsorbents used for VOCs sampling are also described. Furthermore, this paper makes an effort to comprehensively review the concentration levels of volatile organic compounds along with the methodology used for analysis, in major cities of the world.

40 CFR 60.496 - Test methods and procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Surface Coating Industry § 60.496 Test methods and procedures. (a) The reference methods in appendix A to...) Method 4 for stack gas moisture. (b) For Method 24, the coating sample must be a 1-litre sample collected... volume must be 0.003 dscm except that shorter sampling times or smaller volumes, when necessitated by...

40 CFR 60.496 - Test methods and procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Surface Coating Industry § 60.496 Test methods and procedures. (a) The reference methods in appendix A to...) Method 4 for stack gas moisture. (b) For Method 24, the coating sample must be a 1-litre sample collected... volume must be 0.003 dscm except that shorter sampling times or smaller volumes, when necessitated by...

40 CFR 60.496 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Surface Coating Industry § 60.496 Test methods and procedures. (a) The reference methods in appendix A to...) Method 4 for stack gas moisture. (b) For Method 24, the coating sample must be a 1-litre sample collected... volume must be 0.003 dscm except that shorter sampling times or smaller volumes, when necessitated by...

40 CFR 60.496 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Surface Coating Industry § 60.496 Test methods and procedures. (a) The reference methods in appendix A to...) Method 4 for stack gas moisture. (b) For Method 24, the coating sample must be a 1-litre sample collected... volume must be 0.003 dscm except that shorter sampling times or smaller volumes, when necessitated by...

40 CFR 60.496 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Surface Coating Industry § 60.496 Test methods and procedures. (a) The reference methods in appendix A to...) Method 4 for stack gas moisture. (b) For Method 24, the coating sample must be a 1-litre sample collected... volume must be 0.003 dscm except that shorter sampling times or smaller volumes, when necessitated by...

[Comparison of the Conventional Centrifuged and Filtrated Preparations in Urine Cytology].

PubMed

Sekita, Nobuyuki; Shimosakai, Hirofumi; Nishikawa, Rika; Sato, Hiroaki; Kouno, Hiroyoshi; Fujimura, Masaaki; Mikami, Kazuo

2016-03-01

The urine cytology test is one of the most important tools for the diagnosis of malignant urinary tract tumors. This test is also of great value for predicting malignancy. However, the sensitivity of this test is not high enough to screen for malignant cells. In our laboratory, we were able to attain a high sensitivity of urine cytology tests after changing the preparation method of urine samples. The differences in the cytodiagnosis between the two methods are discussed here. From January 2012 to June 2013, 2,031 urine samples were prepared using the conventional centrifuge method (C method) ; and from September 2013 to March 2015, 2,453 urine samples were prepared using the filtration method (F method) for the cytology test. When the samples included in category 4 or 5, were defined as cytological positive, the sensitivities of this test with samples prepared using the F method were significantly high compared with samples prepared using the C method (72% vs 28%, p＜0.001). The number of cells on the glass slides prepared by the F method was significantly higher than that of the samples prepared by the C method (p＜0.001). After introduction of the F method, the number of f alse negative cases was decreased in the urine cytology test because a larger number of cells was seen and easily detected as atypical or malignant epithelial cells. Therefore, this method has a higher sensitivity than the conventional C method as the sensitivity of urine cytology tests relies partially on the number of cells visualized in the prepared samples.

Flow Cytometric Human Leukocyte Antigen-B27 Typing with Stored Samples for Batch Testing

PubMed Central

Seo, Bo Young

2013-01-01

Background Flow cytometry (FC) HLA-B27 typing is still used extensively for the diagnosis of spondyloarthropathies. If patient blood samples are stored for a prolonged duration, this testing can be performed in a batch manner, and in-house cellular controls could easily be procured. In this study, we investigated various methods of storing patient blood samples. Methods We compared four storage methods: three methods of analyzing lymphocytes (whole blood stored at room temperature, frozen mononuclear cells, and frozen white blood cells [WBCs] after lysing red blood cells [RBCs]), and one method using frozen platelets (FPLT). We used three ratios associated with mean fluorescence intensities (MFI) for HLAB27 assignment: the B27 MFI ratio (sample/control) for HLA-B27 fluorescein-5-isothiocyanate (FITC); the B7 MFI ratio for HLA-B7 phycoerythrin (PE); and the ratio of these two ratios, B7/B27 ratio. Results Comparing the B27 MFI ratios of each storage method for the HLA-B27+ samples and the B7/B27 ratios for the HLA-B7+ samples revealed that FPLT was the best of the four methods. FPLT had a sensitivity of 100% and a specificity of 99.3% for HLA-B27 assignment in DNA-typed samples (N=164) when the two criteria, namely, B27 MFI ratio >4.0 and B7/B27 ratio <1.5, were used. Conclusions The FPLT method was found to offer a simple, economical, and accurate method of FC HLA-B27 typing by using stored patient samples. If stored samples are used, this method has the potential to replace the standard FC typing method when used in combination with a complementary DNA-based method. PMID:23667843

Sampling Methods in Cardiovascular Nursing Research: An Overview.

PubMed

Kandola, Damanpreet; Banner, Davina; O'Keefe-McCarthy, Sheila; Jassal, Debbie

2014-01-01

Cardiovascular nursing research covers a wide array of topics from health services to psychosocial patient experiences. The selection of specific participant samples is an important part of the research design and process. The sampling strategy employed is of utmost importance to ensure that a representative sample of participants is chosen. There are two main categories of sampling methods: probability and non-probability. Probability sampling is the random selection of elements from the population, where each element of the population has an equal and independent chance of being included in the sample. There are five main types of probability sampling including simple random sampling, systematic sampling, stratified sampling, cluster sampling, and multi-stage sampling. Non-probability sampling methods are those in which elements are chosen through non-random methods for inclusion into the research study and include convenience sampling, purposive sampling, and snowball sampling. Each approach offers distinct advantages and disadvantages and must be considered critically. In this research column, we provide an introduction to these key sampling techniques and draw on examples from the cardiovascular research. Understanding the differences in sampling techniques may aid nurses in effective appraisal of research literature and provide a reference pointfor nurses who engage in cardiovascular research.

Face recognition based on symmetrical virtual image and original training image

NASA Astrophysics Data System (ADS)

Ke, Jingcheng; Peng, Yali; Liu, Shigang; Li, Jun; Pei, Zhao

2018-02-01

In face representation-based classification methods, we are able to obtain high recognition rate if a face has enough available training samples. However, in practical applications, we only have limited training samples to use. In order to obtain enough training samples, many methods simultaneously use the original training samples and corresponding virtual samples to strengthen the ability of representing the test sample. One is directly using the original training samples and corresponding mirror samples to recognize the test sample. However, when the test sample is nearly symmetrical while the original training samples are not, the integration of the original training and mirror samples might not well represent the test samples. To tackle the above-mentioned problem, in this paper, we propose a novel method to obtain a kind of virtual samples which are generated by averaging the original training samples and corresponding mirror samples. Then, the original training samples and the virtual samples are integrated to recognize the test sample. Experimental results on five face databases show that the proposed method is able to partly overcome the challenges of the various poses, facial expressions and illuminations of original face image.

19 CFR 151.83 - Method of sampling.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 2 2010-04-01 2010-04-01 false Method of sampling. 151.83 Section 151.83 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) EXAMINATION, SAMPLING, AND TESTING OF MERCHANDISE Cotton § 151.83 Method of sampling. For...

Comparing three sampling techniques for estimating fine woody down dead biomass

Treesearch

Robert E. Keane; Kathy Gray

2013-01-01

Designing woody fuel sampling methods that quickly, accurately and efficiently assess biomass at relevant spatial scales requires extensive knowledge of each sampling method's strengths, weaknesses and tradeoffs. In this study, we compared various modifications of three common sampling methods (planar intercept, fixed-area microplot and photoload) for estimating...

Model-based inference for small area estimation with sampling weights

PubMed Central

Vandendijck, Y.; Faes, C.; Kirby, R.S.; Lawson, A.; Hens, N.

2017-01-01

Obtaining reliable estimates about health outcomes for areas or domains where only few to no samples are available is the goal of small area estimation (SAE). Often, we rely on health surveys to obtain information about health outcomes. Such surveys are often characterised by a complex design, stratification, and unequal sampling weights as common features. Hierarchical Bayesian models are well recognised in SAE as a spatial smoothing method, but often ignore the sampling weights that reflect the complex sampling design. In this paper, we focus on data obtained from a health survey where the sampling weights of the sampled individuals are the only information available about the design. We develop a predictive model-based approach to estimate the prevalence of a binary outcome for both the sampled and non-sampled individuals, using hierarchical Bayesian models that take into account the sampling weights. A simulation study is carried out to compare the performance of our proposed method with other established methods. The results indicate that our proposed method achieves great reductions in mean squared error when compared with standard approaches. It performs equally well or better when compared with more elaborate methods when there is a relationship between the responses and the sampling weights. The proposed method is applied to estimate asthma prevalence across districts. PMID:28989860

Sampling Strategies for Evaluating the Rate of Adventitious Transgene Presence in Non-Genetically Modified Crop Fields.

PubMed

Makowski, David; Bancal, Rémi; Bensadoun, Arnaud; Monod, Hervé; Messéan, Antoine

2017-09-01

According to E.U. regulations, the maximum allowable rate of adventitious transgene presence in non-genetically modified (GM) crops is 0.9%. We compared four sampling methods for the detection of transgenic material in agricultural non-GM maize fields: random sampling, stratified sampling, random sampling + ratio reweighting, random sampling + regression reweighting. Random sampling involves simply sampling maize grains from different locations selected at random from the field concerned. The stratified and reweighting sampling methods make use of an auxiliary variable corresponding to the output of a gene-flow model (a zero-inflated Poisson model) simulating cross-pollination as a function of wind speed, wind direction, and distance to the closest GM maize field. With the stratified sampling method, an auxiliary variable is used to define several strata with contrasting transgene presence rates, and grains are then sampled at random from each stratum. With the two methods involving reweighting, grains are first sampled at random from various locations within the field, and the observations are then reweighted according to the auxiliary variable. Data collected from three maize fields were used to compare the four sampling methods, and the results were used to determine the extent to which transgene presence rate estimation was improved by the use of stratified and reweighting sampling methods. We found that transgene rate estimates were more accurate and that substantially smaller samples could be used with sampling strategies based on an auxiliary variable derived from a gene-flow model. © 2017 Society for Risk Analysis.

Salmonella detection in poultry samples. Comparison of two commercial real-time PCR systems with culture methods for the detection of Salmonella spp. in environmental and fecal samples of poultry.

PubMed

Sommer, D; Enderlein, D; Antakli, A; Schönenbrücher, H; Slaghuis, J; Redmann, T; Lierz, M

2012-01-01

The efficiency of two commercial PCR methods based on real-time technology, the foodproof® Salmonella detection system and the BAX® PCR Assay Salmonella system was compared to standardized culture methods (EN ISO 6579:2002 - Annex D) for the detection of Salmonella spp. in poultry samples. Four sample matrices (feed, dust, boot swabs, feces) obtained directly from poultry flocks, as well as artificially spiked samples of the same matrices, were used. All samples were tested for Salmonella spp. using culture methods first as the gold standard. In addition samples spiked with Salmonella Enteridis were tested to evaluate the sensitivity of both PCR methods. Furthermore all methods were evaluated in an annual ring-trial of the National Salmonella Reference Laboratory of Germany. Salmonella detection in the matrices feed, dust and boot swabs were comparable in both PCR systems whereas the results from feces differed markedly. The quality, especially the freshness, of the fecal samples had an influence on the sensitivity of the real-time PCR and the results of the culture methods. In fresh fecal samples an initial spiking level of 100cfu/25g Salmonella Enteritidis was detected. Two-days-dried fecal samples allowed the detection of 14cfu/25g. Both real- time PCR protocols appear to be suitable for the detection of Salmonella spp. in all four matrices. The foodproof® system detected eight samples more to be positive compared to the BAX® system, but had a potential false positive result in one case. In 7-days-dried samples none of the methods was able to detect Salmonella likely through letal cell damage. In general the advantage of PCR analyses over the culture method is the reduction of working time from 4-5 days to only 2 days. However, especially for the analysis of fecal samples official validation should be conducted according to the requirement of EN ISO6579:2002 - Annex D.

Comparison of concentration methods for rapid detection of hookworm ova in wastewater matrices using quantitative PCR.

PubMed

Gyawali, P; Ahmed, W; Jagals, P; Sidhu, J P S; Toze, S

2015-12-01

Hookworm infection contributes around 700 million infections worldwide especially in developing nations due to increased use of wastewater for crop production. The effective recovery of hookworm ova from wastewater matrices is difficult due to their low concentrations and heterogeneous distribution. In this study, we compared the recovery rates of (i) four rapid hookworm ova concentration methods from municipal wastewater, and (ii) two concentration methods from sludge samples. Ancylostoma caninum ova were used as surrogate for human hookworm (Ancylostoma duodenale and Necator americanus). Known concentration of A. caninum hookworm ova were seeded into wastewater (treated and raw) and sludge samples collected from two wastewater treatment plants (WWTPs) in Brisbane and Perth, Australia. The A. caninum ova were concentrated from treated and raw wastewater samples using centrifugation (Method A), hollow fiber ultrafiltration (HFUF) (Method B), filtration (Method C) and flotation (Method D) methods. For sludge samples, flotation (Method E) and direct DNA extraction (Method F) methods were used. Among the four methods tested, filtration (Method C) method was able to recover higher concentrations of A. caninum ova consistently from treated wastewater (39-50%) and raw wastewater (7.1-12%) samples collected from both WWTPs. The remaining methods (Methods A, B and D) yielded variable recovery rate ranging from 0.2 to 40% for treated and raw wastewater samples. The recovery rates for sludge samples were poor (0.02-4.7), although, Method F (direct DNA extraction) provided 1-2 orders of magnitude higher recovery rate than Method E (flotation). Based on our results it can be concluded that the recovery rates of hookworm ova from wastewater matrices, especially sludge samples, can be poor and highly variable. Therefore, choice of concentration method is vital for the sensitive detection of hookworm ova in wastewater matrices. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Quantifying Uncertainties from Presence Data Sampling Methods for Species Distribution Modeling: Focused on Vegetation.

NASA Astrophysics Data System (ADS)

Sung, S.; Kim, H. G.; Lee, D. K.; Park, J. H.; Mo, Y.; Kil, S.; Park, C.

2016-12-01

The impact of climate change has been observed throughout the globe. The ecosystem experiences rapid changes such as vegetation shift, species extinction. In these context, Species Distribution Model (SDM) is one of the popular method to project impact of climate change on the ecosystem. SDM basically based on the niche of certain species with means to run SDM present point data is essential to find biological niche of species. To run SDM for plants, there are certain considerations on the characteristics of vegetation. Normally, to make vegetation data in large area, remote sensing techniques are used. In other words, the exact point of presence data has high uncertainties as we select presence data set from polygons and raster dataset. Thus, sampling methods for modeling vegetation presence data should be carefully selected. In this study, we used three different sampling methods for selection of presence data of vegetation: Random sampling, Stratified sampling and Site index based sampling. We used one of the R package BIOMOD2 to access uncertainty from modeling. At the same time, we included BioCLIM variables and other environmental variables as input data. As a result of this study, despite of differences among the 10 SDMs, the sampling methods showed differences in ROC values, random sampling methods showed the lowest ROC value while site index based sampling methods showed the highest ROC value. As a result of this study the uncertainties from presence data sampling methods and SDM can be quantified.

A Hybrid DNA Extraction Method for the Qualitative and Quantitative Assessment of Bacterial Communities from Poultry Production Samples

PubMed Central

Rothrock, Michael J.; Hiett, Kelli L.; Gamble, John; Caudill, Andrew C.; Cicconi-Hogan, Kellie M.; Caporaso, J. Gregory

2014-01-01

The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses performed. Considering that the use of new bacterial community analysis techniques (e.g., microbiomics, metagenomics) is becoming more prevalent in the agricultural and environmental sciences and many environmental samples within these disciplines can be physiochemically and microbiologically unique (e.g., fecal and litter/bedding samples from the poultry production spectrum), appropriate and effective DNA extraction methods need to be carefully chosen. Therefore, a novel semi-automated hybrid DNA extraction method was developed specifically for use with environmental poultry production samples. This method is a combination of the two major types of DNA extraction: mechanical and enzymatic. A two-step intense mechanical homogenization step (using bead-beating specifically formulated for environmental samples) was added to the beginning of the “gold standard” enzymatic DNA extraction method for fecal samples to enhance the removal of bacteria and DNA from the sample matrix and improve the recovery of Gram-positive bacterial community members. Once the enzymatic extraction portion of the hybrid method was initiated, the remaining purification process was automated using a robotic workstation to increase sample throughput and decrease sample processing error. In comparison to the strict mechanical and enzymatic DNA extraction methods, this novel hybrid method provided the best overall combined performance when considering quantitative (using 16S rRNA qPCR) and qualitative (using microbiomics) estimates of the total bacterial communities when processing poultry feces and litter samples. PMID:25548939

Improving the analysis of composite endpoints in rare disease trials.

PubMed

McMenamin, Martina; Berglind, Anna; Wason, James M S

2018-05-22

Composite endpoints are recommended in rare diseases to increase power and/or to sufficiently capture complexity. Often, they are in the form of responder indices which contain a mixture of continuous and binary components. Analyses of these outcomes typically treat them as binary, thus only using the dichotomisations of continuous components. The augmented binary method offers a more efficient alternative and is therefore especially useful for rare diseases. Previous work has indicated the method may have poorer statistical properties when the sample size is small. Here we investigate small sample properties and implement small sample corrections. We re-sample from a previous trial with sample sizes varying from 30 to 80. We apply the standard binary and augmented binary methods and determine the power, type I error rate, coverage and average confidence interval width for each of the estimators. We implement Firth's adjustment for the binary component models and a small sample variance correction for the generalized estimating equations, applying the small sample adjusted methods to each sub-sample as before for comparison. For the log-odds treatment effect the power of the augmented binary method is 20-55% compared to 12-20% for the standard binary method. Both methods have approximately nominal type I error rates. The difference in response probabilities exhibit similar power but both unadjusted methods demonstrate type I error rates of 6-8%. The small sample corrected methods have approximately nominal type I error rates. On both scales, the reduction in average confidence interval width when using the adjusted augmented binary method is 17-18%. This is equivalent to requiring a 32% smaller sample size to achieve the same statistical power. The augmented binary method with small sample corrections provides a substantial improvement for rare disease trials using composite endpoints. We recommend the use of the method for the primary analysis in relevant rare disease trials. We emphasise that the method should be used alongside other efforts in improving the quality of evidence generated from rare disease trials rather than replace them.

Comparison of a New Cobinamide-Based Method to a Standard Laboratory Method for Measuring Cyanide in Human Blood

PubMed Central

Swezey, Robert; Shinn, Walter; Green, Carol; Drover, David R.; Hammer, Gregory B.; Schulman, Scott R.; Zajicek, Anne; Jett, David A.; Boss, Gerry R.

2013-01-01

Most hospital laboratories do not measure blood cyanide concentrations, and samples must be sent to reference laboratories. A simple method is needed for measuring cyanide in hospitals. The authors previously developed a method to quantify cyanide based on the high binding affinity of the vitamin B12 analog, cobinamide, for cyanide and a major spectral change observed for cyanide-bound cobinamide. This method is now validated in human blood, and the findings include a mean inter-assay accuracy of 99.1%, precision of 8.75% and a lower limit of quantification of 3.27 µM cyanide. The method was applied to blood samples from children treated with sodium nitroprusside and it yielded measurable results in 88 of 172 samples (51%), whereas the reference laboratory yielded results in only 19 samples (11%). In all 19 samples, the cobinamide-based method also yielded measurable results. The two methods showed reasonable agreement when analyzed by linear regression, but not when analyzed by a standard error of the estimate or paired t-test. Differences in results between the two methods may be because samples were assayed at different times on different sample types. The cobinamide-based method is applicable to human blood, and can be used in hospital laboratories and emergency rooms. PMID:23653045

Molecular cancer classification using a meta-sample-based regularized robust coding method.

PubMed

Wang, Shu-Lin; Sun, Liuchao; Fang, Jianwen

2014-01-01

Previous studies have demonstrated that machine learning based molecular cancer classification using gene expression profiling (GEP) data is promising for the clinic diagnosis and treatment of cancer. Novel classification methods with high efficiency and prediction accuracy are still needed to deal with high dimensionality and small sample size of typical GEP data. Recently the sparse representation (SR) method has been successfully applied to the cancer classification. Nevertheless, its efficiency needs to be improved when analyzing large-scale GEP data. In this paper we present the meta-sample-based regularized robust coding classification (MRRCC), a novel effective cancer classification technique that combines the idea of meta-sample-based cluster method with regularized robust coding (RRC) method. It assumes that the coding residual and the coding coefficient are respectively independent and identically distributed. Similar to meta-sample-based SR classification (MSRC), MRRCC extracts a set of meta-samples from the training samples, and then encodes a testing sample as the sparse linear combination of these meta-samples. The representation fidelity is measured by the l2-norm or l1-norm of the coding residual. Extensive experiments on publicly available GEP datasets demonstrate that the proposed method is more efficient while its prediction accuracy is equivalent to existing MSRC-based methods and better than other state-of-the-art dimension reduction based methods.

Experimental Investigations on Subsequent Yield Surface of Pure Copper by Single-Sample and Multi-Sample Methods under Various Pre-Deformation.

PubMed

Liu, Gui-Long; Huang, Shi-Hong; Shi, Che-Si; Zeng, Bin; Zhang, Ke-Shi; Zhong, Xian-Ci

2018-02-10

Using copper thin-walled tubular specimens, the subsequent yield surfaces under pre-tension, pre-torsion and pre-combined tension-torsion are measured, where the single-sample and multi-sample methods are applied respectively to determine the yield stresses at specified offset strain. The rule and characteristics of the evolution of the subsequent yield surface are investigated. Under the conditions of different pre-strains, the influence of test point number, test sequence and specified offset strain on the measurement of subsequent yield surface and the concave phenomenon for measured yield surface are studied. Moreover, the feasibility and validity of the two methods are compared. The main conclusions are drawn as follows: (1) For the single or multi-sample method, the measured subsequent yield surfaces are remarkably different from cylindrical yield surfaces proposed by the classical plasticity theory; (2) there are apparent differences between the test results from the two kinds of methods: the multi-sample method is not influenced by the number of test points, test order and the cumulative effect of residual plastic strain resulting from the other test point, while those are very influential in the single-sample method; and (3) the measured subsequent yield surface may appear concave, which can be transformed to convex for single-sample method by changing the test sequence. However, for the multiple-sample method, the concave phenomenon will disappear when a larger offset strain is specified.

Estimation of the sensitivity of various environmental sampling methods for detection of Salmonella in duck flocks.

PubMed

Arnold, Mark E; Mueller-Doblies, Doris; Gosling, Rebecca J; Martelli, Francesca; Davies, Robert H

2015-01-01

Reports of Salmonella in ducks in the UK currently rely upon voluntary submissions from the industry, and as there is no harmonized statutory monitoring and control programme, it is difficult to compare data from different years in order to evaluate any trends in Salmonella prevalence in relation to sampling methodology. Therefore, the aim of this project was to assess the sensitivity of a selection of environmental sampling methods, including the sampling of faeces, dust and water troughs or bowls for the detection of Salmonella in duck flocks, and a range of sampling methods were applied to 67 duck flocks. Bayesian methods in the absence of a gold standard were used to provide estimates of the sensitivity of each of the sampling methods relative to the within-flock prevalence. There was a large influence of the within-flock prevalence on the sensitivity of all sample types, with sensitivity reducing as the within-flock prevalence reduced. Boot swabs (individual and pool of four), swabs of faecally contaminated areas and whole house hand-held fabric swabs showed the overall highest sensitivity for low-prevalence flocks and are recommended for use to detect Salmonella in duck flocks. The sample type with the highest proportion positive was a pool of four hair nets used as boot swabs, but this was not the most sensitive sample for low-prevalence flocks. All the environmental sampling types (faeces swabs, litter pinches, drag swabs, water trough samples and dust) had higher sensitivity than individual faeces sampling. None of the methods consistently identified all the positive flocks, and at least 10 samples would be required for even the most sensitive method (pool of four boot swabs) to detect a 5% prevalence. The sampling of dust had a low sensitivity and is not recommended for ducks.

Improved radiation dose efficiency in solution SAXS using a sheath flow sample environment

PubMed Central

Kirby, Nigel; Cowieson, Nathan; Hawley, Adrian M.; Mudie, Stephen T.; McGillivray, Duncan J.; Kusel, Michael; Samardzic-Boban, Vesna; Ryan, Timothy M.

2016-01-01

Radiation damage is a major limitation to synchrotron small-angle X-ray scattering analysis of biomacromolecules. Flowing the sample during exposure helps to reduce the problem, but its effectiveness in the laminar-flow regime is limited by slow flow velocity at the walls of sample cells. To overcome this limitation, the coflow method was developed, where the sample flows through the centre of its cell surrounded by a flow of matched buffer. The method permits an order-of-magnitude increase of X-ray incident flux before sample damage, improves measurement statistics and maintains low sample concentration limits. The method also efficiently handles sample volumes of a few microlitres, can increase sample throughput, is intrinsically resistant to capillary fouling by sample and is suited to static samples and size-exclusion chromatography applications. The method unlocks further potential of third-generation synchrotron beamlines to facilitate new and challenging applications in solution scattering. PMID:27917826

Acupuncture injection for field amplified sample stacking and glass microchip-based capillary gel electrophoresis.

PubMed

Ha, Ji Won; Hahn, Jong Hoon

2017-02-01

Acupuncture sample injection is a simple method to deliver well-defined nanoliter-scale sample plugs in PDMS microfluidic channels. This acupuncture injection method in microchip CE has several advantages, including minimization of sample consumption, the capability of serial injections of different sample solutions into the same microchannel, and the capability of injecting sample plugs into any desired position of a microchannel. Herein, we demonstrate that the simple and cost-effective acupuncture sample injection method can be used for PDMS microchip-based field amplified sample stacking in the most simplified straight channel by applying a single potential. We achieved the increase in electropherogram signals for the case of sample stacking. Furthermore, we present that microchip CGE of ΦX174 DNA-HaeⅢ digest can be performed with the acupuncture injection method on a glass microchip while minimizing sample loss and voltage control hardware. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method for chromium analysis and speciation

DOEpatents

Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

2004-11-02

A method of detecting a metal in a sample comprising a plurality of metal is disclosed. The method comprises providing the sample comprising a metal to be detected. The sample is added to a reagent solution comprising an enzyme and a substrate, where the enzyme is inhibited by the metal to be detected. An array of chelating agents is used to eliminate the inhibitory effects of additional metals in the sample. An enzymatic activity in the sample is determined and compared to an enzymatic activity in a control solution to detect the metal to be detected. A method of determining a concentration of the metal in the sample is also disclosed. A method of detecting a valence state of a metal is also disclosed.

A nonparametric method to generate synthetic populations to adjust for complex sampling design features.

PubMed

Dong, Qi; Elliott, Michael R; Raghunathan, Trivellore E

2014-06-01

Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs.

A nonparametric method to generate synthetic populations to adjust for complex sampling design features

PubMed Central

Dong, Qi; Elliott, Michael R.; Raghunathan, Trivellore E.

2017-01-01

Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs. PMID:29200608

Using lot quality-assurance sampling and area sampling to identify priority areas for trachoma control: Viet Nam.

PubMed Central

Myatt, Mark; Mai, Nguyen Phuong; Quynh, Nguyen Quang; Nga, Nguyen Huy; Tai, Ha Huy; Long, Nguyen Hung; Minh, Tran Hung; Limburg, Hans

2005-01-01

OBJECTIVE: To report on the use of lot quality-assurance sampling (LQAS) surveys undertaken within an area-sampling framework to identify priority areas for intervention with trachoma control activities in Viet Nam. METHODS: The LQAS survey method for the rapid assessment of the prevalence of active trachoma was adapted for use in Viet Nam with the aim of classifying individual communes by the prevalence of active trachoma among children in primary school. School-based sampling was used; school sites to be sampled were selected using an area-sampling approach. A total of 719 communes in 41 districts in 18 provinces were surveyed. FINDINGS: Survey staff found the LQAS survey method both simple and rapid to use after initial problems with area-sampling methods were identified and remedied. The method yielded a finer spatial resolution of prevalence than had been previously achieved in Viet Nam using semiquantitative rapid assessment surveys and multistage cluster-sampled surveys. CONCLUSION: When used with area-sampling techniques, the LQAS survey method has the potential to form the basis of survey instruments that can be used to efficiently target resources for interventions against active trachoma. With additional work, such methods could provide a generally applicable tool for effective programme planning and for the certification of the elimination of trachoma as a blinding disease. PMID:16283052

Sampling for Patient Exit Interviews: Assessment of Methods Using Mathematical Derivation and Computer Simulations.

PubMed

Geldsetzer, Pascal; Fink, Günther; Vaikath, Maria; Bärnighausen, Till

2018-02-01

(1) To evaluate the operational efficiency of various sampling methods for patient exit interviews; (2) to discuss under what circumstances each method yields an unbiased sample; and (3) to propose a new, operationally efficient, and unbiased sampling method. Literature review, mathematical derivation, and Monte Carlo simulations. Our simulations show that in patient exit interviews it is most operationally efficient if the interviewer, after completing an interview, selects the next patient exiting the clinical consultation. We demonstrate mathematically that this method yields a biased sample: patients who spend a longer time with the clinician are overrepresented. This bias can be removed by selecting the next patient who enters, rather than exits, the consultation room. We show that this sampling method is operationally more efficient than alternative methods (systematic and simple random sampling) in most primary health care settings. Under the assumption that the order in which patients enter the consultation room is unrelated to the length of time spent with the clinician and the interviewer, selecting the next patient entering the consultation room tends to be the operationally most efficient unbiased sampling method for patient exit interviews. © 2016 The Authors. Health Services Research published by Wiley Periodicals, Inc. on behalf of Health Research and Educational Trust.

Sampling methods, dispersion patterns, and fixed precision sequential sampling plans for western flower thrips (Thysanoptera: Thripidae) and cotton fleahoppers (Hemiptera: Miridae) in cotton.

PubMed

Parajulee, M N; Shrestha, R B; Leser, J F

2006-04-01

A 2-yr field study was conducted to examine the effectiveness of two sampling methods (visual and plant washing techniques) for western flower thrips, Frankliniella occidentalis (Pergande), and five sampling methods (visual, beat bucket, drop cloth, sweep net, and vacuum) for cotton fleahopper, Pseudatomoscelis seriatus (Reuter), in Texas cotton, Gossypium hirsutum (L.), and to develop sequential sampling plans for each pest. The plant washing technique gave similar results to the visual method in detecting adult thrips, but the washing technique detected significantly higher number of thrips larvae compared with the visual sampling. Visual sampling detected the highest number of fleahoppers followed by beat bucket, drop cloth, vacuum, and sweep net sampling, with no significant difference in catch efficiency between vacuum and sweep net methods. However, based on fixed precision cost reliability, the sweep net sampling was the most cost-effective method followed by vacuum, beat bucket, drop cloth, and visual sampling. Taylor's Power Law analysis revealed that the field dispersion patterns of both thrips and fleahoppers were aggregated throughout the crop growing season. For thrips management decision based on visual sampling (0.25 precision), 15 plants were estimated to be the minimum sample size when the estimated population density was one thrips per plant, whereas the minimum sample size was nine plants when thrips density approached 10 thrips per plant. The minimum visual sample size for cotton fleahoppers was 16 plants when the density was one fleahopper per plant, but the sample size decreased rapidly with an increase in fleahopper density, requiring only four plants to be sampled when the density was 10 fleahoppers per plant. Sequential sampling plans were developed and validated with independent data for both thrips and cotton fleahoppers.

Performance of Traditional and Molecular Methods for Detecting Biological Agents in Drinking Water

USGS Publications Warehouse

Francy, Donna S.; Bushon, Rebecca N.; Brady, Amie M.G.; Bertke, Erin E.; Kephart, Christopher M.; Likirdopulos, Christina A.; Mailot, Brian E.; Schaefer, Frank W.; Lindquist, H.D. Alan

2009-01-01

To reduce the impact from a possible bioterrorist attack on drinking-water supplies, analytical methods are needed to rapidly detect the presence of biological agents in water. To this end, 13 drinking-water samples were collected at 9 water-treatment plants in Ohio to assess the performance of a molecular method in comparison to traditional analytical methods that take longer to perform. Two 100-liter samples were collected at each site during each sampling event; one was seeded in the laboratory with six biological agents - Bacillus anthracis (B. anthracis), Burkholderia cepacia (as a surrogate for Bu. pseudomallei), Francisella tularensis (F. tularensis), Salmonella Typhi (S. Typhi), Vibrio cholerae (V. cholerae), and Cryptospordium parvum (C. parvum). The seeded and unseeded samples were processed by ultrafiltration and analyzed by use of quantiative polymerase chain reaction (qPCR), a molecular method, and culture methods for bacterial agents or the immunomagnetic separation/fluorescent antibody (IMS/FA) method for C. parvum as traditional methods. Six replicate seeded samples were also processed and analyzed. For traditional methods, recoveries were highly variable between samples and even between some replicate samples, ranging from below detection to greater than 100 percent. Recoveries were significantly related to water pH, specific conductance, and dissolved organic carbon (DOC) for all bacteria combined by culture methods, but none of the water-quality characteristics tested were related to recoveries of C. parvum by IMS/FA. Recoveries were not determined by qPCR because of problems in quantifying organisms by qPCR in the composite seed. Instead, qPCR results were reported as detected, not detected (no qPCR signal), or +/- detected (Cycle Threshold or 'Ct' values were greater than 40). Several sample results by qPCR were omitted from the dataset because of possible problems with qPCR reagents, primers, and probes. For the remaining 14 qPCR results (including some replicate samples), F. tularensis and V. cholerae were detected in all samples after ultrafiltration, B. anthracis was detected in 13 and +/- detected in 1 sample, and C. parvum was detected in 9 and +/- detected in 4 samples. Bu. cepacia was detected in nine samples, +/- detected in two samples, and not detected in three samples (for two out of three samples not detected, a different strain was used). The qPCR assay for V. cholerae provided two false positive - but late - signals in one unseeded sample. Numbers found by qPCR after ultrafiltration were significantly or nearly significantly related to those found by traditional methods for B. anthracis, F. tularensis, and V. cholerae but not for Bu. cepacia and C. parvum. A qPCR assay for S. Typhi was not available. The qPCR method can be used to rapidly detect B. anthracis, F. tularensis, and V. cholerae with some certainty in drinking-water samples, but additional work would be needed to optimize and test qPCR for Bu. cepacia and C. parvum and establish relations to traditional methods. The specificity for the V. cholerae assay needs to be further investigated. Evidence is provided that ultrafiltration and qPCR are promising methods to rapidly detect biological agents in the Nation's drinking-water supplies and thus reduce the impact and consequences from intentional bioterrorist events. To our knowledge, this is the first study to compare the use of traditional and qPCR methods to detect biological agents in large-volume drinking-water samples.

Comparison of the Immunomagnetic Separation/Adenosine Triphosphate Rapid Method and the Modified mTEC Membrane-Filtration Method for Enumeration of Escherichia coli

USGS Publications Warehouse

Brady, Amie M.G.; Bushon, Rebecca N.; Bertke, Erin E.

2009-01-01

Water quality at beaches is monitored for fecal indicator bacteria by traditional, culture-based methods that can take 18 to 24 hours to obtain results. A rapid detection method that provides estimated concentrations of fecal indicator bacteria within 1 hour from the start of sample processing would allow beach managers to post advisories or close the beach when the conditions are actually considered unsafe instead of a day later, when conditions may have changed. A rapid method that couples immunomagnetic separation with adenosine triphosphate detection (IMS/ATP rapid method) was evaluated through monitoring of Escherichia coli (E. coli) at three Lake Erie beaches in Ohio (Edgewater and Villa Angela in Cleveland and Huntington in Bay Village). Beach water samples were collected between 4 and 5 days per week during the recreational seasons (May through September) of 2006 and 2007. Composite samples were created in the lab from two point samples collected at each beach and were shown to be comparable substitutes for analysis of two individual samples. E. coli concentrations in composite samples, as determined by the culture-based method, ranged from 4 to 24,000 colony-forming units per 100 milliliters during this study across all beaches. Turbidity also was measured for each sample and ranged from 0.8 to 260 neophelometric turbidity ratio units. Environmental variables were noted at the time of sampling, including number of birds at the beach and wave height. Rainfall amounts were measured at National Weather Service stations at local airports. Turbidity, rainfall, and wave height were significantly related to the culture-based method results each year and for both years combined at each beach. The number of birds at the beach was significantly related to the culture-based method results only at Edgewater during 2006 and during both years combined. Results of the IMS/ATP method were compared to results of the culture-based method for samples by year for each beach. The IMS/ATP method underwent several changes and refinements during the first year, including changes in reagents and antibodies and alterations to the method protocol. Because of the changes in the method, results from the two years of study could not be combined. Kendall's tau correlation coefficients for relations between the IMS/ATP and culture-based methods were significant except for samples collected during 2006 at Edgewater and for samples collected during 2007 at Villa Angela. Further, relations were stronger for samples collected in 2006 than for those collected in 2007, except at Edgewater where the reverse was observed. The 2007 dataset was examined to identify possible reasons for the observed difference in significance of relations by year. By dividing the 2007 data set into groups as a function of sampling date, relations (Kendall's tau) between methods were observed to be stronger for samples collected earlier in the season than for those collected later in the season. At Edgewater and Villa Angela, there were more birds at the beach at time of sampling later in the season compared to earlier in the season. (The number of birds was not examined at Huntington.) Also, more wet days (when rainfall during the 24 hours prior to sampling was greater than 0.05 inch) were sampled later in the season compared to earlier in the season. Differences in the dominant fecal source may explain the change in the relations between the culture-based and IMS/ATP methods.

Method and apparatus for data sampling

DOEpatents

Odell, Daniel M. C.

1994-01-01

A method and apparatus for sampling radiation detector outputs and determining event data from the collected samples. The method uses high speed sampling of the detector output, the conversion of the samples to digital values, and the discrimination of the digital values so that digital values representing detected events are determined. The high speed sampling and digital conversion is performed by an A/D sampler that samples the detector output at a rate high enough to produce numerous digital samples for each detected event. The digital discrimination identifies those digital samples that are not representative of detected events. The sampling and discrimination also provides for temporary or permanent storage, either serially or in parallel, to a digital storage medium.

40 CFR 80.8 - Sampling methods for gasoline and diesel fuel.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Sampling methods for gasoline and... gasoline and diesel fuel. The sampling methods specified in this section shall be used to collect samples of gasoline and diesel fuel for purposes of determining compliance with the requirements of this part...

40 CFR 80.8 - Sampling methods for gasoline and diesel fuel.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Sampling methods for gasoline and... gasoline and diesel fuel. The sampling methods specified in this section shall be used to collect samples of gasoline and diesel fuel for purposes of determining compliance with the requirements of this part...

40 CFR 80.8 - Sampling methods for gasoline and diesel fuel.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Sampling methods for gasoline and... gasoline and diesel fuel. The sampling methods specified in this section shall be used to collect samples of gasoline and diesel fuel for purposes of determining compliance with the requirements of this part...

Unconstrained Enhanced Sampling for Free Energy Calculations of Biomolecules: A Review

PubMed Central

Miao, Yinglong; McCammon, J. Andrew

2016-01-01

Free energy calculations are central to understanding the structure, dynamics and function of biomolecules. Yet insufficient sampling of biomolecular configurations is often regarded as one of the main sources of error. Many enhanced sampling techniques have been developed to address this issue. Notably, enhanced sampling methods based on biasing collective variables (CVs), including the widely used umbrella sampling, adaptive biasing force and metadynamics, have been discussed in a recent excellent review (Abrams and Bussi, Entropy, 2014). Here, we aim to review enhanced sampling methods that do not require predefined system-dependent CVs for biomolecular simulations and as such do not suffer from the hidden energy barrier problem as encountered in the CV-biasing methods. These methods include, but are not limited to, replica exchange/parallel tempering, self-guided molecular/Langevin dynamics, essential energy space random walk and accelerated molecular dynamics. While it is overwhelming to describe all details of each method, we provide a summary of the methods along with the applications and offer our perspectives. We conclude with challenges and prospects of the unconstrained enhanced sampling methods for accurate biomolecular free energy calculations. PMID:27453631

Unconstrained Enhanced Sampling for Free Energy Calculations of Biomolecules: A Review.

PubMed

Miao, Yinglong; McCammon, J Andrew

Free energy calculations are central to understanding the structure, dynamics and function of biomolecules. Yet insufficient sampling of biomolecular configurations is often regarded as one of the main sources of error. Many enhanced sampling techniques have been developed to address this issue. Notably, enhanced sampling methods based on biasing collective variables (CVs), including the widely used umbrella sampling, adaptive biasing force and metadynamics, have been discussed in a recent excellent review (Abrams and Bussi, Entropy, 2014). Here, we aim to review enhanced sampling methods that do not require predefined system-dependent CVs for biomolecular simulations and as such do not suffer from the hidden energy barrier problem as encountered in the CV-biasing methods. These methods include, but are not limited to, replica exchange/parallel tempering, self-guided molecular/Langevin dynamics, essential energy space random walk and accelerated molecular dynamics. While it is overwhelming to describe all details of each method, we provide a summary of the methods along with the applications and offer our perspectives. We conclude with challenges and prospects of the unconstrained enhanced sampling methods for accurate biomolecular free energy calculations.

Method of Analysis by the U.S. Geological Survey California District Sacramento Laboratory?Determination of Trihalomethane Formation Potential, Method Validation, and Quality-Control Practices

USGS Publications Warehouse

Crepeau, Kathryn L.; Fram, Miranda S.; Bush, Noel

2004-01-01

An analytical method for the determination of the trihalomethane formation potential of water samples has been developed. The trihalomethane formation potential is measured by dosing samples with chlorine under specified conditions of pH, temperature, incubation time, darkness, and residual-free chlorine, and then analyzing the resulting trihalomethanes by purge and trap/gas chromatography equipped with an electron capture detector. Detailed explanations of the method and quality-control practices are provided. Method validation experiments showed that the trihalomethane formation potential varies as a function of time between sample collection and analysis, residual-free chlorine concentration, method of sample dilution, and the concentration of bromide in the sample.

Mechanisms of fracture of ring samples made of FCC metals on loading with magnetic-pulse method

NASA Astrophysics Data System (ADS)

Morozov, Viktor; Kats, Victor; Savenkov, Georgiy; Lukin, Anton

2018-05-01

Results of study of deformation and fracture of ring-shaped samples made of thin strips of cuprum, aluminum and steel in wide range of loading velocity are presented. Three developed by us schemes of magnetic-pulse method are used for the samples loading. The method of samples fracture with the high electrical resistance (e.g. steel) is proposed. Crack velocity at the sample fracture is estimated. Fracture surfaces are inspected. Mechanisms of dynamic fracture of the sample arere discussed.

Evaluating performance of stormwater sampling approaches using a dynamic watershed model.

PubMed

Ackerman, Drew; Stein, Eric D; Ritter, Kerry J

2011-09-01

Accurate quantification of stormwater pollutant levels is essential for estimating overall contaminant discharge to receiving waters. Numerous sampling approaches exist that attempt to balance accuracy against the costs associated with the sampling method. This study employs a novel and practical approach of evaluating the accuracy of different stormwater monitoring methodologies using stormflows and constituent concentrations produced by a fully validated continuous simulation watershed model. A major advantage of using a watershed model to simulate pollutant concentrations is that a large number of storms representing a broad range of conditions can be applied in testing the various sampling approaches. Seventy-eight distinct methodologies were evaluated by "virtual samplings" of 166 simulated storms of varying size, intensity and duration, representing 14 years of storms in Ballona Creek near Los Angeles, California. The 78 methods can be grouped into four general strategies: volume-paced compositing, time-paced compositing, pollutograph sampling, and microsampling. The performances of each sampling strategy was evaluated by comparing the (1) median relative error between the virtually sampled and the true modeled event mean concentration (EMC) of each storm (accuracy), (2) median absolute deviation about the median or "MAD" of the relative error or (precision), and (3) the percentage of storms where sampling methods were within 10% of the true EMC (combined measures of accuracy and precision). Finally, costs associated with site setup, sampling, and laboratory analysis were estimated for each method. Pollutograph sampling consistently outperformed the other three methods both in terms of accuracy and precision, but was the most costly method evaluated. Time-paced sampling consistently underestimated while volume-paced sampling over estimated the storm EMCs. Microsampling performance approached that of pollutograph sampling at a substantial cost savings. The most efficient method for routine stormwater monitoring in terms of a balance between performance and cost was volume-paced microsampling, with variable sample pacing to ensure that the entirety of the storm was captured. Pollutograph sampling is recommended if the data are to be used for detailed analysis of runoff dynamics.

Using lot quality-assurance sampling and area sampling to identify priority areas for trachoma control: Viet Nam.

PubMed

Myatt, Mark; Mai, Nguyen Phuong; Quynh, Nguyen Quang; Nga, Nguyen Huy; Tai, Ha Huy; Long, Nguyen Hung; Minh, Tran Hung; Limburg, Hans

2005-10-01

To report on the use of lot quality-assurance sampling (LQAS) surveys undertaken within an area-sampling framework to identify priority areas for intervention with trachoma control activities in Viet Nam. The LQAS survey method for the rapid assessment of the prevalence of active trachoma was adapted for use in Viet Nam with the aim of classifying individual communes by the prevalence of active trachoma among children in primary school. School-based sampling was used; school sites to be sampled were selected using an area-sampling approach. A total of 719 communes in 41 districts in 18 provinces were surveyed. Survey staff found the LQAS survey method both simple and rapid to use after initial problems with area-sampling methods were identified and remedied. The method yielded a finer spatial resolution of prevalence than had been previously achieved in Viet Nam using semiquantitative rapid assessment surveys and multistage cluster-sampled surveys. When used with area-sampling techniques, the LQAS survey method has the potential to form the basis of survey instruments that can be used to efficiently target resources for interventions against active trachoma. With additional work, such methods could provide a generally applicable tool for effective programme planning and for the certification of the elimination of trachoma as a blinding disease.

DuPont Qualicon BAX System polymerase chain reaction assay. Performance Tested Method 100201.

PubMed

Tice, George; Andaloro, Bridget; Fallon, Dawn; Wallace, F Morgan

2009-01-01

A recent outbreak of Salmonella in peanut butter has highlighted the need for validation of rapid detection methods. A multilaboratory study for detecting Salmonella in peanut butter was conducted as part of the AOAC Research Institute Emergency Response Validation program for methods that detect outbreak threats to food safety. Three sites tested spiked samples from the same master mix according to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method and the BAX System method. Salmonella Typhimurium (ATCC 14028) was grown in brain heart infusion for 24 h at 37 degrees C, then diluted to appropriate levels for sample inoculation. Master samples of peanut butter were spiked at high and low target levels, mixed, and allowed to equilibrate at room temperature for 2 weeks. Spike levels were low [1.08 most probable number (MPN)/25 g]; high (11.5 MPN/25 g) and unspiked to serve as negative controls. Each master sample was divided into 25 g portions and coded to blind the samples. Twenty portions of each spiked master sample and five portions of the unspiked sample were tested at each site. At each testing site, samples were blended in 25 g portions with 225 mL prewarmed lactose broth until thoroughly homogenized, then allowed to remain at room temperature for 55-65 min. Samples were adjusted to a pH of 6.8 +/- 0.2, if necessary, and incubated for 22-26 h at 35 degrees C. Across the three reporting laboratories, the BAX System detected Salmonella in 10/60 low-spike samples and 58/60 high-spike samples. The reference FDA-BAM method yielded positive results for 11/60 low-spike and 58/60 high-spike samples. Neither method demonstrated positive results for any of the 15 unspiked samples.

Evaluation of environmental sampling methods for detection of Salmonella enterica in a large animal veterinary hospital.

PubMed

Goeman, Valerie R; Tinkler, Stacy H; Hammac, G Kenitra; Ruple, Audrey

2018-04-01

Environmental surveillance for Salmonella enterica can be used for early detection of contamination; thus routine sampling is an integral component of infection control programs in hospital environments. At the Purdue University Veterinary Teaching Hospital (PUVTH), the technique regularly employed in the large animal hospital for sample collection uses sterile gauze sponges for environmental sampling, which has proven labor-intensive and time-consuming. Alternative sampling methods use Swiffer brand electrostatic wipes for environmental sample collection, which are reportedly effective and efficient. It was hypothesized that use of Swiffer wipes for sample collection would be more efficient and less costly than the use of gauze sponges. A head-to-head comparison between the 2 sampling methods was conducted in the PUVTH large animal hospital and relative agreement, cost-effectiveness, and sampling efficiency were compared. There was fair agreement in culture results between the 2 sampling methods, but Swiffer wipes required less time and less physical effort to collect samples and were more cost-effective.

Validation of High Resolution Melting Analysis (HRM) of the Amplified ITS2 Region for the Detection and Identification of Yeasts from Clinical Samples: Comparison with Culture and MALDI-TOF Based Identification.

PubMed

Duyvejonck, Hans; Cools, Piet; Decruyenaere, Johan; Roelens, Kristien; Noens, Lucien; Vermeulen, Stefan; Claeys, Geert; Decat, Ellen; Van Mechelen, Els; Vaneechoutte, Mario

2015-01-01

Candida species are known as opportunistic pathogens, and a possible cause of invasive infections. Because of their species-specific antimycotic resistance patterns, reliable techniques for their detection, quantification and identification are needed. We validated a DNA amplification method for direct detection of Candida spp. from clinical samples, namely the ITS2-High Resolution Melting Analysis (direct method), by comparing it with a culture and MALDI-TOF Mass Spectrometry based method (indirect method) to establish the presence of Candida species in three different types of clinical samples. A total of 347 clinical samples, i.e. throat swabs, rectal swabs and vaginal swabs, were collected from the gynaecology/obstetrics, intensive care and haematology wards at the Ghent University Hospital, Belgium. For the direct method, ITS2-HRM was preceded by NucliSENS easyMAG DNA extraction, directly on the clinical samples. For the indirect method, clinical samples were cultured on Candida ID and individual colonies were identified by MALDI-TOF. For 83.9% of the samples there was complete concordance between both techniques, i.e. the same Candida species were detected in 31.1% of the samples or no Candida species were detected in 52.8% of the samples. In 16.1% of the clinical samples, discrepant results were obtained, of which only 6.01% were considered as major discrepancies. Discrepancies occurred mostly when overall numbers of Candida cells in the samples were low and/or when multiple species were present in the sample. Most of the discrepancies could be decided in the advantage of the direct method. This is due to samples in which no yeast could be cultured whereas low amounts could be detected by the direct method and to samples in which high quantities of Candida robusta according to ITS2-HRM were missed by culture on Candida ID agar. It remains to be decided whether the diagnostic advantages of the direct method compensate for its disadvantages.

Methyl-CpG island-associated genome signature tags

DOEpatents

Dunn, John J

2014-05-20

Disclosed is a method for analyzing the organismic complexity of a sample through analysis of the nucleic acid in the sample. In the disclosed method, through a series of steps, including digestion with a type II restriction enzyme, ligation of capture adapters and linkers and digestion with a type IIS restriction enzyme, genome signature tags are produced. The sequences of a statistically significant number of the signature tags are determined and the sequences are used to identify and quantify the organisms in the sample. Various embodiments of the invention described herein include methods for using single point genome signature tags to analyze the related families present in a sample, methods for analyzing sequences associated with hyper- and hypo-methylated CpG islands, methods for visualizing organismic complexity change in a sampling location over time and methods for generating the genome signature tag profile of a sample of fragmented DNA.

Methods for Determining Particle Size Distributions from Nuclear Detonations.

DTIC Science & Technology

1987-03-01

Debris . . . 30 IV. Summary of Sample Preparation Method . . . . 35 V. Set Parameters for PCS ... ........... 39 VI. Analysis by Vendors...54 XV. Results From Brookhaven Analysis Using The Method of Cumulants ... ........... . 54 XVI. Results From Brookhaven Analysis of Sample...R-3 Using Histogram Method ......... .55 XVII. Results From Brookhaven Analysis of Sample R-8 Using Histogram Method ........... 56 XVIII.TEM Particle

The differential path phase comparison method for determining pressure derivatives of elastic constants of solids

NASA Astrophysics Data System (ADS)

Peselnick, L.

1982-08-01

An ultrasonic method is presented which combines features of the differential path and the phase comparison methods. The proposed differential path phase comparison method, referred to as the `hybrid' method for brevity, eliminates errors resulting from phase changes in the bond between the sample and buffer rod. Define r(P) [and R(P)] as the square of the normalized frequency for cancellation of sample waves for shear [and for compressional] waves. Define N as the number of wavelengths in twice the sample length. The pressure derivatives r'(P) and R' (P) for samples of Alcoa 2024-T4 aluminum were obtained by using the phase comparison and the hybrid methods. The values of the pressure derivatives obtained by using the phase comparison method show variations by as much as 40% for small values of N (N < 50). The pressure derivatives as determined from the hybrid method are reproducible to within ±2% independent of N. The values of the pressure derivatives determined by the phase comparison method for large N are the same as those determined by the hybrid method. Advantages of the hybrid method are (1) no pressure dependent phase shift at the buffer-sample interface, (2) elimination of deviatoric stress in the sample portion of the sample assembly with application of hydrostatic pressure, and (3) operation at lower ultrasonic frequencies (for comparable sample lengths), which eliminates detrimental high frequency ultrasonic problems. A reduction of the uncertainties of the pressure derivatives of single crystals and of low porosity polycrystals permits extrapolation of such experimental data to deeper mantle depths.

Double-cross hydrostatic pressure sample injection for chip CE: variable sample plug volume and minimum number of electrodes.

PubMed

Luo, Yong; Wu, Dapeng; Zeng, Shaojiang; Gai, Hongwei; Long, Zhicheng; Shen, Zheng; Dai, Zhongpeng; Qin, Jianhua; Lin, Bingcheng

2006-09-01

A novel sample injection method for chip CE was presented. This injection method uses hydrostatic pressure, generated by emptying the sample waste reservoir, for sample loading and electrokinetic force for dispensing. The injection was performed on a double-cross microchip. One cross, created by the sample and separation channels, is used for formation of a sample plug. Another cross, formed by the sample and controlling channels, is used for plug control. By varying the electric field in the controlling channel, the sample plug volume can be linearly adjusted. Hydrostatic pressure takes advantage of its ease of generation on a microfluidic chip, without any electrode or external pressure pump, thus allowing a sample injection with a minimum number of electrodes. The potential of this injection method was demonstrated by a four-separation-channel chip CE system. In this system, parallel sample separation can be achieved with only two electrodes, which is otherwise impossible with conventional injection methods. Hydrostatic pressure maintains the sample composition during the sample loading, allowing the injection to be free of injection bias.

SLEPR: A Sample-Level Enrichment-Based Pathway Ranking Method — Seeking Biological Themes through Pathway-Level Consistency

PubMed Central

Yi, Ming; Stephens, Robert M.

2008-01-01

Analysis of microarray and other high throughput data often involves identification of genes consistently up or down-regulated across samples as the first step in extraction of biological meaning. This gene-level paradigm can be limited as a result of valid sample fluctuations and biological complexities. In this report, we describe a novel method, SLEPR, which eliminates this limitation by relying on pathway-level consistencies. Our method first selects the sample-level differentiated genes from each individual sample, capturing genes missed by other analysis methods, ascertains the enrichment levels of associated pathways from each of those lists, and then ranks annotated pathways based on the consistency of enrichment levels of individual samples from both sample classes. As a proof of concept, we have used this method to analyze three public microarray datasets with a direct comparison with the GSEA method, one of the most popular pathway-level analysis methods in the field. We found that our method was able to reproduce the earlier observations with significant improvements in depth of coverage for validated or expected biological themes, but also produced additional insights that make biological sense. This new method extends existing analyses approaches and facilitates integration of different types of HTP data. PMID:18818771

Evaluation of an alternate method for sampling benthic macroinvertebrates in low-gradient streams sampled as part of the National Rivers and Streams Assessment.

PubMed

Flotemersch, Joseph E; North, Sheila; Blocksom, Karen A

2014-02-01

Benthic macroinvertebrates are sampled in streams and rivers as one of the assessment elements of the US Environmental Protection Agency's National Rivers and Streams Assessment. In a 2006 report, the recommendation was made that different yet comparable methods be evaluated for different types of streams (e.g., low gradient vs. high gradient). Consequently, a research element was added to the 2008-2009 National Rivers and Streams Assessment to conduct a side-by-side comparison of the standard macroinvertebrate sampling method with an alternate method specifically designed for low-gradient wadeable streams and rivers that focused more on stream edge habitat. Samples were collected using each method at 525 sites in five of nine aggregate ecoregions located in the conterminous USA. Methods were compared using the benthic macroinvertebrate multimetric index developed for the 2006 Wadeable Streams Assessment. Statistical analysis did not reveal any trends that would suggest the overall assessment of low-gradient streams on a regional or national scale would change if the alternate method was used rather than the standard sampling method, regardless of the gradient cutoff used to define low-gradient streams. Based on these results, the National Rivers and Streams Survey should continue to use the standard field method for sampling all streams.

Novel joint selection methods can reduce sample size for rheumatoid arthritis clinical trials with ultrasound endpoints.

PubMed

Allen, John C; Thumboo, Julian; Lye, Weng Kit; Conaghan, Philip G; Chew, Li-Ching; Tan, York Kiat

2018-03-01

To determine whether novel methods of selecting joints through (i) ultrasonography (individualized-ultrasound [IUS] method), or (ii) ultrasonography and clinical examination (individualized-composite-ultrasound [ICUS] method) translate into smaller rheumatoid arthritis (RA) clinical trial sample sizes when compared to existing methods utilizing predetermined joint sites for ultrasonography. Cohen's effect size (ES) was estimated (ES^) and a 95% CI (ES^L, ES^U) calculated on a mean change in 3-month total inflammatory score for each method. Corresponding 95% CIs [nL(ES^U), nU(ES^L)] were obtained on a post hoc sample size reflecting the uncertainty in ES^. Sample size calculations were based on a one-sample t-test as the patient numbers needed to provide 80% power at α = 0.05 to reject a null hypothesis H 0 : ES = 0 versus alternative hypotheses H 1 : ES = ES^, ES = ES^L and ES = ES^U. We aimed to provide point and interval estimates on projected sample sizes for future studies reflecting the uncertainty in our study ES^S. Twenty-four treated RA patients were followed up for 3 months. Utilizing the 12-joint approach and existing methods, the post hoc sample size (95% CI) was 22 (10-245). Corresponding sample sizes using ICUS and IUS were 11 (7-40) and 11 (6-38), respectively. Utilizing a seven-joint approach, the corresponding sample sizes using ICUS and IUS methods were nine (6-24) and 11 (6-35), respectively. Our pilot study suggests that sample size for RA clinical trials with ultrasound endpoints may be reduced using the novel methods, providing justification for larger studies to confirm these observations. © 2017 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

Lead as a legendary pollutant with emerging concern: Survey of lead in tap water in an old campus building using four sampling methods.

PubMed

Ng, Ding-Quan; Liu, Shu-Wei; Lin, Yi-Pin

2018-09-15

In this study, a sampling campaign with a total of nine sampling events investigating lead in drinking water was conducted at 7 sampling locations in an old building with lead pipes in service in part of the building on the National Taiwan University campus. This study aims to assess the effectiveness of four different sampling methods, namely first draw sampling, sequential sampling, random daytime sampling and flush sampling, in lead contamination detection. In 3 out of the 7 sampling locations without lead pipe, lead could not be detected (<1.1 μg/L) in most samples regardless of the sampling methods. On the other hand, in the 4 sampling locations where lead pipes still existed, total lead concentrations >10 μg/L were consistently observed in 3 locations using any of the four sampling methods while the remaining location was identified to be contaminated using sequential sampling. High lead levels were consistently measured by the four sampling methods in the 3 locations in which particulate lead was either predominant or comparable to soluble lead. Compared to first draw and random daytime samplings, although flush sampling had a high tendency to reduce total lead in samples in lead-contaminated sites, the extent of lead reduction was location-dependent and not dependent on flush durations between 5 and 10 min. Overall, first draw sampling and random daytime sampling were reliable and effective in determining lead contamination in this study. Flush sampling could reveal the contamination if the extent is severe but tends to underestimate lead exposure risk. Copyright © 2018 Elsevier B.V. All rights reserved.

Concentration comparison of selected constituents between groundwater samples collected within the Missouri River alluvial aquifer using purge and pump and grab-sampling methods, near the city of Independence, Missouri, 2013

USGS Publications Warehouse

Krempa, Heather M.

2015-10-29

Relative percent differences between methods were greater than 10 percent for most analyzed trace elements. Barium, cobalt, manganese, and boron had concentrations that were significantly different between sampling methods. Barium, molybdenum, boron, and uranium method concentrations indicate a close association between pump and grab samples based on bivariate plots and simple linear regressions. Grab sample concentrations were generally larger than pump concentrations for these elements and may be because of using a larger pore sized filter for grab samples. Analysis of zinc blank samples suggests zinc contamination in filtered grab samples. Variations of analyzed trace elements between pump and grab samples could reduce the ability to monitor temporal changes and potential groundwater contamination threats. The degree of precision necessary for monitoring potential groundwater threats and application objectives need to be considered when determining acceptable variation amounts.

Representativeness of direct observations selected using a work-sampling equation.

PubMed

Sharp, Rebecca A; Mudford, Oliver C; Elliffe, Douglas

2015-01-01

Deciding on appropriate sampling to obtain representative samples of behavior is important but not straightforward, because the relative duration of the target behavior may affect its observation in a given sampling interval. Work-sampling methods, which offer a way to adjust the frequency of sampling according to a priori or ongoing estimates of the behavior to achieve a preselected level of representativeness, may provide a solution. Full-week observations of 7 behaviors were conducted for 3 students with autism spectrum disorder and intellectual disabilities. Work-sampling methods were used to select momentary time samples from the full time-of-interest, which produced representative samples. However, work sampling required impractically high numbers of time samples to obtain representative samples. More practical momentary time samples produced less representative samples, particularly for low-duration behaviors. The utility and limits of work-sampling methods for applied behavior analysis are discussed. © Society for the Experimental Analysis of Behavior.

Evaluating Composite Sampling Methods of Bacillus Spores at Low Concentrations

PubMed Central

Hess, Becky M.; Amidan, Brett G.; Anderson, Kevin K.; Hutchison, Janine R.

2016-01-01

Restoring all facility operations after the 2001 Amerithrax attacks took years to complete, highlighting the need to reduce remediation time. Some of the most time intensive tasks were environmental sampling and sample analyses. Composite sampling allows disparate samples to be combined, with only a single analysis needed, making it a promising method to reduce response times. We developed a statistical experimental design to test three different composite sampling methods: 1) single medium single pass composite (SM-SPC): a single cellulose sponge samples multiple coupons with a single pass across each coupon; 2) single medium multi-pass composite: a single cellulose sponge samples multiple coupons with multiple passes across each coupon (SM-MPC); and 3) multi-medium post-sample composite (MM-MPC): a single cellulose sponge samples a single surface, and then multiple sponges are combined during sample extraction. Five spore concentrations of Bacillus atrophaeus Nakamura spores were tested; concentrations ranged from 5 to 100 CFU/coupon (0.00775 to 0.155 CFU/cm2). Study variables included four clean surface materials (stainless steel, vinyl tile, ceramic tile, and painted dry wallboard) and three grime coated/dirty materials (stainless steel, vinyl tile, and ceramic tile). Analysis of variance for the clean study showed two significant factors: composite method (p< 0.0001) and coupon material (p = 0.0006). Recovery efficiency (RE) was higher overall using the MM-MPC method compared to the SM-SPC and SM-MPC methods. RE with the MM-MPC method for concentrations tested (10 to 100 CFU/coupon) was similar for ceramic tile, dry wall, and stainless steel for clean materials. RE was lowest for vinyl tile with both composite methods. Statistical tests for the dirty study showed RE was significantly higher for vinyl and stainless steel materials, but lower for ceramic tile. These results suggest post-sample compositing can be used to reduce sample analysis time when responding to a Bacillus anthracis contamination event of clean or dirty surfaces. PMID:27736999

Evaluating Composite Sampling Methods of Bacillus Spores at Low Concentrations.

PubMed

Hess, Becky M; Amidan, Brett G; Anderson, Kevin K; Hutchison, Janine R

2016-01-01

Restoring all facility operations after the 2001 Amerithrax attacks took years to complete, highlighting the need to reduce remediation time. Some of the most time intensive tasks were environmental sampling and sample analyses. Composite sampling allows disparate samples to be combined, with only a single analysis needed, making it a promising method to reduce response times. We developed a statistical experimental design to test three different composite sampling methods: 1) single medium single pass composite (SM-SPC): a single cellulose sponge samples multiple coupons with a single pass across each coupon; 2) single medium multi-pass composite: a single cellulose sponge samples multiple coupons with multiple passes across each coupon (SM-MPC); and 3) multi-medium post-sample composite (MM-MPC): a single cellulose sponge samples a single surface, and then multiple sponges are combined during sample extraction. Five spore concentrations of Bacillus atrophaeus Nakamura spores were tested; concentrations ranged from 5 to 100 CFU/coupon (0.00775 to 0.155 CFU/cm2). Study variables included four clean surface materials (stainless steel, vinyl tile, ceramic tile, and painted dry wallboard) and three grime coated/dirty materials (stainless steel, vinyl tile, and ceramic tile). Analysis of variance for the clean study showed two significant factors: composite method (p< 0.0001) and coupon material (p = 0.0006). Recovery efficiency (RE) was higher overall using the MM-MPC method compared to the SM-SPC and SM-MPC methods. RE with the MM-MPC method for concentrations tested (10 to 100 CFU/coupon) was similar for ceramic tile, dry wall, and stainless steel for clean materials. RE was lowest for vinyl tile with both composite methods. Statistical tests for the dirty study showed RE was significantly higher for vinyl and stainless steel materials, but lower for ceramic tile. These results suggest post-sample compositing can be used to reduce sample analysis time when responding to a Bacillus anthracis contamination event of clean or dirty surfaces.

SnagPRO: snag and tree sampling and analysis methods for wildlife

Treesearch

Lisa J. Bate; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

2008-01-01

We describe sampling methods and provide software to accurately and efficiently estimate snag and tree densities at desired scales to meet a variety of research and management objectives. The methods optimize sampling effort by choosing a plot size appropriate for the specified forest conditions and sampling goals. Plot selection and data analyses are supported by...

A Mixed Methods Investigation of Mixed Methods Sampling Designs in Social and Health Science Research

ERIC Educational Resources Information Center

Collins, Kathleen M. T.; Onwuegbuzie, Anthony J.; Jiao, Qun G.

2007-01-01

A sequential design utilizing identical samples was used to classify mixed methods studies via a two-dimensional model, wherein sampling designs were grouped according to the time orientation of each study's components and the relationship of the qualitative and quantitative samples. A quantitative analysis of 121 studies representing nine fields…

An evaluation of methods for estimating decadal stream loads

NASA Astrophysics Data System (ADS)

Lee, Casey J.; Hirsch, Robert M.; Schwarz, Gregory E.; Holtschlag, David J.; Preston, Stephen D.; Crawford, Charles G.; Vecchia, Aldo V.

2016-11-01

Effective management of water resources requires accurate information on the mass, or load of water-quality constituents transported from upstream watersheds to downstream receiving waters. Despite this need, no single method has been shown to consistently provide accurate load estimates among different water-quality constituents, sampling sites, and sampling regimes. We evaluate the accuracy of several load estimation methods across a broad range of sampling and environmental conditions. This analysis uses random sub-samples drawn from temporally-dense data sets of total nitrogen, total phosphorus, nitrate, and suspended-sediment concentration, and includes measurements of specific conductance which was used as a surrogate for dissolved solids concentration. Methods considered include linear interpolation and ratio estimators, regression-based methods historically employed by the U.S. Geological Survey, and newer flexible techniques including Weighted Regressions on Time, Season, and Discharge (WRTDS) and a generalized non-linear additive model. No single method is identified to have the greatest accuracy across all constituents, sites, and sampling scenarios. Most methods provide accurate estimates of specific conductance (used as a surrogate for total dissolved solids or specific major ions) and total nitrogen - lower accuracy is observed for the estimation of nitrate, total phosphorus and suspended sediment loads. Methods that allow for flexibility in the relation between concentration and flow conditions, specifically Beale's ratio estimator and WRTDS, exhibit greater estimation accuracy and lower bias. Evaluation of methods across simulated sampling scenarios indicate that (1) high-flow sampling is necessary to produce accurate load estimates, (2) extrapolation of sample data through time or across more extreme flow conditions reduces load estimate accuracy, and (3) WRTDS and methods that use a Kalman filter or smoothing to correct for departures between individual modeled and observed values benefit most from more frequent water-quality sampling.

An evaluation of methods for estimating decadal stream loads

USGS Publications Warehouse

Lee, Casey; Hirsch, Robert M.; Schwarz, Gregory E.; Holtschlag, David J.; Preston, Stephen D.; Crawford, Charles G.; Vecchia, Aldo V.

2016-01-01

Effective management of water resources requires accurate information on the mass, or load of water-quality constituents transported from upstream watersheds to downstream receiving waters. Despite this need, no single method has been shown to consistently provide accurate load estimates among different water-quality constituents, sampling sites, and sampling regimes. We evaluate the accuracy of several load estimation methods across a broad range of sampling and environmental conditions. This analysis uses random sub-samples drawn from temporally-dense data sets of total nitrogen, total phosphorus, nitrate, and suspended-sediment concentration, and includes measurements of specific conductance which was used as a surrogate for dissolved solids concentration. Methods considered include linear interpolation and ratio estimators, regression-based methods historically employed by the U.S. Geological Survey, and newer flexible techniques including Weighted Regressions on Time, Season, and Discharge (WRTDS) and a generalized non-linear additive model. No single method is identified to have the greatest accuracy across all constituents, sites, and sampling scenarios. Most methods provide accurate estimates of specific conductance (used as a surrogate for total dissolved solids or specific major ions) and total nitrogen – lower accuracy is observed for the estimation of nitrate, total phosphorus and suspended sediment loads. Methods that allow for flexibility in the relation between concentration and flow conditions, specifically Beale’s ratio estimator and WRTDS, exhibit greater estimation accuracy and lower bias. Evaluation of methods across simulated sampling scenarios indicate that (1) high-flow sampling is necessary to produce accurate load estimates, (2) extrapolation of sample data through time or across more extreme flow conditions reduces load estimate accuracy, and (3) WRTDS and methods that use a Kalman filter or smoothing to correct for departures between individual modeled and observed values benefit most from more frequent water-quality sampling.

A unified method to process biosolids samples for the recovery of bacterial, viral, and helminths pathogens.

PubMed

Alum, Absar; Rock, Channah; Abbaszadegan, Morteza

2014-01-01

For land application, biosolids are classified as Class A or Class B based on the levels of bacterial, viral, and helminths pathogens in residual biosolids. The current EPA methods for the detection of these groups of pathogens in biosolids include discrete steps. Therefore, a separate sample is processed independently to quantify the number of each group of the pathogens in biosolids. The aim of the study was to develop a unified method for simultaneous processing of a single biosolids sample to recover bacterial, viral, and helminths pathogens. At the first stage for developing a simultaneous method, nine eluents were compared for their efficiency to recover viruses from a 100 gm spiked biosolids sample. In the second stage, the three top performing eluents were thoroughly evaluated for the recovery of bacteria, viruses, and helminthes. For all three groups of pathogens, the glycine-based eluent provided higher recovery than the beef extract-based eluent. Additional experiments were performed to optimize performance of glycine-based eluent under various procedural factors such as, solids to eluent ratio, stir time, and centrifugation conditions. Last, the new method was directly compared with the EPA methods for the recovery of the three groups of pathogens spiked in duplicate samples of biosolids collected from different sources. For viruses, the new method yielded up to 10% higher recoveries than the EPA method. For bacteria and helminths, recoveries were 74% and 83% by the new method compared to 34% and 68% by the EPA method, respectively. The unified sample processing method significantly reduces the time required for processing biosolids samples for different groups of pathogens; it is less impacted by the intrinsic variability of samples, while providing higher yields (P = 0.05) and greater consistency than the current EPA methods.

A STANDARDIZED ASSESSMENT METHOD (SAM) FOR RIVERINE MACROINVERTEBRATES

EPA Science Inventory

A macroinvertebrate sampling method for large rivers based on desirable characteristics of existing nonwadeable methods was developed and tested. Six sites each were sampled on the Great Miami and Kentucky Rivers, reflecting a human disturbance gradient. Samples were collected ...

CTEPP STANDARD OPERATING PROCEDURE FOR PACKING AND SHIPPING STUDY SAMPLES (SOP-3.11)

EPA Science Inventory

This SOP describes the methods for packing and shipping study samples. These methods are for packing and shipping biological and environmental samples. The methods have been tested and used in the previous pilot studies.

Nonprobability and probability-based sampling strategies in sexual science.

PubMed

Catania, Joseph A; Dolcini, M Margaret; Orellana, Roberto; Narayanan, Vasudah

2015-01-01

With few exceptions, much of sexual science builds upon data from opportunistic nonprobability samples of limited generalizability. Although probability-based studies are considered the gold standard in terms of generalizability, they are costly to apply to many of the hard-to-reach populations of interest to sexologists. The present article discusses recent conclusions by sampling experts that have relevance to sexual science that advocates for nonprobability methods. In this regard, we provide an overview of Internet sampling as a useful, cost-efficient, nonprobability sampling method of value to sex researchers conducting modeling work or clinical trials. We also argue that probability-based sampling methods may be more readily applied in sex research with hard-to-reach populations than is typically thought. In this context, we provide three case studies that utilize qualitative and quantitative techniques directed at reducing limitations in applying probability-based sampling to hard-to-reach populations: indigenous Peruvians, African American youth, and urban men who have sex with men (MSM). Recommendations are made with regard to presampling studies, adaptive and disproportionate sampling methods, and strategies that may be utilized in evaluating nonprobability and probability-based sampling methods.

77 FR 39895 - New Analytic Methods and Sampling Procedures for the United States National Residue Program for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-06

... Analytic Methods and Sampling Procedures for the United States National Residue Program for Meat, Poultry... implementing several multi-residue methods for analyzing samples of meat, poultry, and egg products for animal.... These modern, high-efficiency methods will conserve resources and provide useful and reliable results...

Evaluation of a QuECHERS-like extraction approach for the determination of PBDEs in mussels by immuno-assay-based screening methods

USDA-ARS?s Scientific Manuscript database

A sample preparation method was evaluated for the determination of polybrominated diphenyl ethers (PBDEs) in mussel samples, by using colorimetric and electrochemical immunoassay-based screening methods. A simple sample preparation in conjunction with a rapid screening method possesses the desired c...

An Improved Manual Method for NOx Emission Measurement.

ERIC Educational Resources Information Center

Dee, L. A.; And Others

The current manual NO (x) sampling and analysis method was evaluated. Improved time-integrated sampling and rapid analysis methods were developed. In the new method, the sample gas is drawn through a heated bed of uniquely active, crystalline, Pb02 where NO (x) is quantitatively absorbed. Nitrate ion is later extracted with water and the…

Comparing two sampling methods to engage hard-to-reach communities in research priority setting.

PubMed

Valerio, Melissa A; Rodriguez, Natalia; Winkler, Paula; Lopez, Jaime; Dennison, Meagen; Liang, Yuanyuan; Turner, Barbara J

2016-10-28

Effective community-partnered and patient-centered outcomes research needs to address community priorities. However, optimal sampling methods to engage stakeholders from hard-to-reach, vulnerable communities to generate research priorities have not been identified. In two similar rural, largely Hispanic communities, a community advisory board guided recruitment of stakeholders affected by chronic pain using a different method in each community: 1) snowball sampling, a chain- referral method or 2) purposive sampling to recruit diverse stakeholders. In both communities, three groups of stakeholders attended a series of three facilitated meetings to orient, brainstorm, and prioritize ideas (9 meetings/community). Using mixed methods analysis, we compared stakeholder recruitment and retention as well as priorities from both communities' stakeholders on mean ratings of their ideas based on importance and feasibility for implementation in their community. Of 65 eligible stakeholders in one community recruited by snowball sampling, 55 (85 %) consented, 52 (95 %) attended the first meeting, and 36 (65 %) attended all 3 meetings. In the second community, the purposive sampling method was supplemented by convenience sampling to increase recruitment. Of 69 stakeholders recruited by this combined strategy, 62 (90 %) consented, 36 (58 %) attended the first meeting, and 26 (42 %) attended all 3 meetings. Snowball sampling recruited more Hispanics and disabled persons (all P < 0.05). Despite differing recruitment strategies, stakeholders from the two communities identified largely similar ideas for research, focusing on non-pharmacologic interventions for management of chronic pain. Ratings on importance and feasibility for community implementation differed only on the importance of massage services (P = 0.045) which was higher for the purposive/convenience sampling group and for city improvements/transportation services (P = 0.004) which was higher for the snowball sampling group. In each of the two similar hard-to-reach communities, a community advisory board partnered with researchers to implement a different sampling method to recruit stakeholders. The snowball sampling method achieved greater participation with more Hispanics but also more individuals with disabilities than a purposive-convenience sampling method. However, priorities for research on chronic pain from both stakeholder groups were similar. Although utilizing a snowball sampling method appears to be superior, further research is needed on implementation costs and resources.

Comparison of two sampling and culture systems for detection of Salmonella enterica in the environment of a large animal hospital.

PubMed

Ruple-Czerniak, A; Bolte, D S; Burgess, B A; Morley, P S

2014-07-01

Nosocomial salmonellosis is an important problem in veterinary hospitals that treat horses and other large animals. Detection and mitigation of outbreaks and prevention of healthcare-associated infections often require detection of Salmonella enterica in the hospital environment. To compare 2 previously published methods for detecting environmental contamination with S. enterica in a large animal veterinary teaching hospital. Hospital-based comparison of environmental sampling techniques. A total of 100 pairs of environmental samples were collected from stalls used to house large animal cases (horses, cows or New World camelids) that were confirmed to be shedding S. enterica by faecal culture. Stalls were cleaned and disinfected prior to sampling, and the same areas within each stall were sampled for the paired samples. One method of detection used sterile, premoistened sponges that were cultured using thioglycolate enrichment before plating on XLT-4 agar. The other method used electrostatic wipes that were cultured using buffered peptone water, tetrathionate and Rappaport-Vassiliadis R10 broths before plating on XLT-4 agar. Salmonella enterica was recovered from 14% of samples processed using the electrostatic wipe sampling and culture procedure, whereas S. enterica was recovered from only 4% of samples processed using the sponge sampling and culture procedure. There was test agreement for 85 pairs of culture-negative samples and 3 pairs of culture-positive samples. However, the remaining 12 pairs of samples with discordant results created significant disagreement between the 2 detection methods (P<0.01). Persistence of Salmonella in the environment of veterinary hospitals can occur even with rigorous cleaning and disinfection. Use of sensitive methods for detection of environmental contamination is critical when detecting and mitigating this problem in veterinary hospitals. These results suggest that the electrostatic wipe sampling and culture method was more sensitive than the sponge sampling and culture method. © 2013 EVJ Ltd.

Filter forensics: microbiota recovery from residential HVAC filters.

PubMed

Maestre, Juan P; Jennings, Wiley; Wylie, Dennis; Horner, Sharon D; Siegel, Jeffrey; Kinney, Kerry A

2018-01-30

Establishing reliable methods for assessing the microbiome within the built environment is critical for understanding the impact of biological exposures on human health. High-throughput DNA sequencing of dust samples provides valuable insights into the microbiome present in human-occupied spaces. However, the effect that different sampling methods have on the microbial community recovered from dust samples is not well understood across sample types. Heating, ventilation, and air conditioning (HVAC) filters hold promise as long-term, spatially integrated, high volume samplers to characterize the airborne microbiome in homes and other climate-controlled spaces. In this study, the effect that dust recovery method (i.e., cut and elution, swabbing, or vacuuming) has on the microbial community structure, membership, and repeatability inferred by Illumina sequencing was evaluated. The results indicate that vacuum samples captured higher quantities of total, bacterial, and fungal DNA than swab or cut samples. Repeated swab and vacuum samples collected from the same filter were less variable than cut samples with respect to both quantitative DNA recovery and bacterial community structure. Vacuum samples captured substantially greater bacterial diversity than the other methods, whereas fungal diversity was similar across all three methods. Vacuum and swab samples of HVAC filter dust were repeatable and generally superior to cut samples. Nevertheless, the contribution of environmental and human sources to the bacterial and fungal communities recovered via each sampling method was generally consistent across the methods investigated. Dust recovery methodologies have been shown to affect the recovery, repeatability, structure, and membership of microbial communities recovered from dust samples in the built environment. The results of this study are directly applicable to indoor microbiota studies utilizing the filter forensics approach. More broadly, this study provides a better understanding of the microbial community variability attributable to sampling methodology and helps inform interpretation of data collected from other types of dust samples collected from indoor environments.

A cryopreservation method for Pasteurella multocida from wetland samples

USGS Publications Warehouse

Moore, Melody K.; Shadduck, D.J.; Goldberg, Diana R.; Samuel, M.D.

1998-01-01

A cryopreservation method and improved isolation techniques for detection of Pasteurella multocida from wetland samples were developed. Wetland water samples were collected in the field, diluted in dimethyl sulfoxide (DMSO, final concentration 10%), and frozen at -180 C in a liquid nitrogen vapor shipper. Frozen samples were transported to the laboratory where they were subsequently thawed and processed in Pasteurella multocida selective broth (PMSB) to isolate P. multocida. This method allowed for consistent isolation of 2 to 18 organisms/ml from water seeded with known concentrations of P. multocida. The method compared favorably with the standard mouse inoculation method and allowed for preservation of the samples until they could be processed in the laboratory.

Method and apparatus for data sampling

DOEpatents

Odell, D.M.C.

1994-04-19

A method and apparatus for sampling radiation detector outputs and determining event data from the collected samples is described. The method uses high speed sampling of the detector output, the conversion of the samples to digital values, and the discrimination of the digital values so that digital values representing detected events are determined. The high speed sampling and digital conversion is performed by an A/D sampler that samples the detector output at a rate high enough to produce numerous digital samples for each detected event. The digital discrimination identifies those digital samples that are not representative of detected events. The sampling and discrimination also provides for temporary or permanent storage, either serially or in parallel, to a digital storage medium. 6 figures.

Evaluation of Offline Tandem and Online Solid-Phase Extraction with Liquid Chromatography/Electrospray Ionization-Mass Spectrometry for Analysis of Antibiotics in Ambient Water and Comparison to an Independent Method

USGS Publications Warehouse

Meyer, M.T.; Lee, E.A.; Ferrell, G.M.; Bumgarner, J.E.; Varns, Jerry

2007-01-01

This report describes the performance of an offline tandem solid-phase extraction (SPE) method and an online SPE method that use liquid chromatography/mass spectrometry for the analysis of 23 and 35 antibiotics, respectively, as used in several water-quality surveys conducted since 1999. In the offline tandem SPE method, normalized concentrations for the quinolone, macrolide, and sulfonamide antibiotics in spiked environmental samples averaged from 81 to 139 percent of the expected spiked concentrations. A modified standard-addition technique was developed to improve the quantitation of the tetracycline antibiotics, which had 'apparent' concentrations that ranged from 185 to 1,200 percent of their expected spiked concentrations in matrix-spiked samples. In the online SPE method, normalized concentrations for the quinolone, macrolide, sulfonamide, and tetracycline antibiotics in matrix-spiked samples averaged from 51 to 142 percent of their expected spiked concentrations, and the beta-lactam antibiotics in matrix-spiked samples averaged from 22 to 76 percent of their expected spiked concentration. Comparison of 44 samples analyzed by both the offline tandem SPE and online SPE methods showed 50 to 100 percent agreement in sample detection for overlapping analytes and 68 to 100 percent agreement in a presence-absence comparison for all analytes. The offline tandem and online SPE methods were compared to an independent method that contains two overlapping antibiotic compounds, sulfamethoxazole and trimethoprim, for 96 and 44 environmental samples, respectively. The offline tandem SPE showed 86 and 92 percent agreement in sample detection and 96 and 98 percent agreement in a presence-absence comparison for sulfamethoxazole and trimethoprim, respectively. The online SPE method showed 57 and 56 percent agreement in sample detection and 72 and 91 percent agreement in presence-absence comparison for sulfamethoxazole and trimethoprim, respectively. A linear regression with an R2 of 0.91 was obtained for trimethoprim concentrations, and an R2 of 0.35 was obtained for sulfamethoxazole concentrations determined from samples analyzed by the offline tandem SPE and online SPE methods. Linear regressions of trimethoprim and sulfamethoxazole concentrations determined from samples analyzed by the offline tandem SPE method and the independent M3 pharmaceutical method yielded R2 of 0.95 and 0.87, respectively. Regressed comparison of the offline tandem SPE method to the online SPE and M3 methods showed that the online SPE method gave higher concentrations for sulfamethoxazole and trimethoprim than were obtained from the offline tandem SPE or M3 methods.

Combined sample collection and gas extraction for the measurement of helium isotopes and neon in natural waters

NASA Astrophysics Data System (ADS)

Roether, Wolfgang; Vogt, Martin; Vogel, Sandra; Sültenfuß, Jürgen

2013-06-01

We present a new method to obtain samples for the measurement of helium isotopes and neon in water, to replace the classical sampling procedure using clamped-off Cu tubing containers that we have been using so far. The new method saves the gas extraction step prior to admission to the mass spectrometer, which the classical method requires. Water is drawn into evacuated glass ampoules with subsequent flame sealing. Approximately 50% headspace is left, from which admission into the mass spectrometer occurs without further treatment. Extensive testing has shown that, with due care and with small corrections applied, the samples represent the gas concentrations in the water within ±0.07% (95% confidence level; ±0.05% with special handling). Fast evacuation is achieved by pumping on a small charge of water placed in the ampoule. The new method was successfully tested at sea in comparison with Cu-tubing sampling. We found that the ampoule samples were superior in data precision and that a lower percentage of samples were lost prior to measurement. Further measurements revealed agreement between the two methods in helium, 3He and neon within ±0.1%. The new method facilitates the dealing with large sample sets and minimizes the delay between sampling and measurement. The method is applicable also for gases other than helium and neon.

Single-view phase retrieval of an extended sample by exploiting edge detection and sparsity

DOE PAGES

Tripathi, Ashish; McNulty, Ian; Munson, Todd; ...

2016-10-14

We propose a new approach to robustly retrieve the exit wave of an extended sample from its coherent diffraction pattern by exploiting sparsity of the sample's edges. This approach enables imaging of an extended sample with a single view, without ptychography. We introduce nonlinear optimization methods that promote sparsity, and we derive update rules to robustly recover the sample's exit wave. We test these methods on simulated samples by varying the sparsity of the edge-detected representation of the exit wave. Finally, our tests illustrate the strengths and limitations of the proposed method in imaging extended samples.

Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium.

PubMed

Boiano, J M; Wallace, M E; Sieber, W K; Groff, J H; Wang, J; Ashley, K

2000-08-01

A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method.

[Determination of ethylene glycol in biological fluids--propylene glycol interferences].

PubMed

Gomółka, Ewa; Cudzich-Czop, Sylwia; Sulka, Adrianna

2013-01-01

Many laboratories in Poland do not use gas chromatography (GC) method for determination of ethylene glycol (EG) and methanol in blood of poisoned patients, they use non specific spectrophotometry methods. One of the interfering substances is propylene glycol (PG)--compound present in many medical and cosmetic products: drops, air freshens, disinfectants, electronic cigarettes and others. In Laboratory of Analytical Toxicology and Drug Monitoring in Krakow determination of EG is made by GC method. The method enables to distinguish and make resolution of (EG) and (PG) in biological samples. In the years 2011-2012 in several serum samples from diagnosed patients PG was present in concentration from several to higher than 100 mg/dL. The aim of the study was to estimate PG interferences of serum EG determination by spectrophotometry method. Serum samples containing PG and EG were used in the study. The samples were analyzed by two methods: GC and spectrophotometry. Results of serum samples spiked with PG with no EG analysed by spectrophotometry method were improper ("false positive"). The results were correlated to PG concentration in samples. Calculated cross-reactivity of PG in the method was 42%. Positive results of EG measured by spectrophotometry method must be confirmed by reference GC method. Spectrophotometry method shouldn't be used for diagnostics and monitoring of patients poisoned by EG.

Comparability among four invertebrate sampling methods and two multimetric indexes, Fountain Creek Basin, Colorado, 2010–2012

USGS Publications Warehouse

Bruce, James F.; Roberts, James J.; Zuellig, Robert E.

2018-05-24

The U.S. Geological Survey (USGS), in cooperation with Colorado Springs City Engineering and Colorado Springs Utilities, analyzed previously collected invertebrate data to determine the comparability among four sampling methods and two versions (2010 and 2017) of the Colorado Benthic Macroinvertebrate Multimetric Index (MMI). For this study, annual macroinvertebrate samples were collected concurrently (in space and time) at 15 USGS surface-water gaging stations in the Fountain Creek Basin from 2010 to 2012 using four sampling methods. The USGS monitoring project in the basin uses two of the methods and the Colorado Department of Public Health and Environment recommends the other two. These methods belong to two distinct sample types, one that targets single habitats and one that targets multiple habitats. The study results indicate that there are significant differences in MMI values obtained from the single-habitat and multihabitat sample types but methods from each program within each sample type produced comparable values. This study also determined that MMI values calculated by different versions of the Colorado Benthic Macroinvertebrate MMI are indistinguishable. This indicates that the Colorado Department of Public Health and Environment methods are comparable with the USGS monitoring project methods for single-habitat and multihabitat sample types. This report discusses the direct application of the study results to inform the revision of the existing USGS monitoring project in the Fountain Creek Basin.

Towards robust and repeatable sampling methods in eDNA based studies.

PubMed

Dickie, Ian A; Boyer, Stephane; Buckley, Hannah; Duncan, Richard P; Gardner, Paul; Hogg, Ian D; Holdaway, Robert J; Lear, Gavin; Makiola, Andreas; Morales, Sergio E; Powell, Jeff R; Weaver, Louise

2018-05-26

DNA based techniques are increasingly used for measuring the biodiversity (species presence, identity, abundance and community composition) of terrestrial and aquatic ecosystems. While there are numerous reviews of molecular methods and bioinformatic steps, there has been little consideration of the methods used to collect samples upon which these later steps are based. This represents a critical knowledge gap, as methodologically sound field sampling is the foundation for subsequent analyses. We reviewed field sampling methods used for metabarcoding studies of both terrestrial and freshwater ecosystem biodiversity over a nearly three-year period (n = 75). We found that 95% (n = 71) of these studies used subjective sampling methods, inappropriate field methods, and/or failed to provide critical methodological information. It would be possible for researchers to replicate only 5% of the metabarcoding studies in our sample, a poorer level of reproducibility than for ecological studies in general. Our findings suggest greater attention to field sampling methods and reporting is necessary in eDNA-based studies of biodiversity to ensure robust outcomes and future reproducibility. Methods must be fully and accurately reported, and protocols developed that minimise subjectivity. Standardisation of sampling protocols would be one way to help to improve reproducibility, and have additional benefits in allowing compilation and comparison of data from across studies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Comparison of extraction methods for quantifying vitamin E from animal tissues.

PubMed

Xu, Zhimin

2008-12-01

Four extraction methods: (1) solvent (SOL), (2) ultrasound assisted solvent (UA), (3) saponification and solvent (SP), and (4) saponification and ultrasound assisted solvent (SP-UA), were used in sample preparation for quantifying vitamin E (tocopherols) in chicken liver and plasma samples. The extraction yields of SOL, UA, SP, and SP-UA methods obtained by adding delta-tocopherol as internal reference were 95%, 104%, 65%, and 62% for liver and 98%, 103%, 97%, and 94% for plasma, respectively. The methods with saponification significantly affected the stabilities of tocopherols in liver samples. The measured values of alpha- and gamma-tocopherols using the solvent only extraction (SOL) method were much lower than that using any of the other extraction methods. This indicated that less of the tocopherols in those samples were in a form that could be extracted directly by solvent. The measured value of alpha-tocopherol in the liver sample using the ultrasound assisted solvent (UA) method was 1.5-2.5 times of that obtained from the saponification and solvent (SP) method. The differences in measured values of tocopherols in the plasma samples by using the two methods were not significant. However, the measured value of the saponification and ultrasound assisted solvent (SP-UA) method was lower than either the saponification and solvent (SP) or the ultrasound assisted solvent (UA) method. Also, the reproducibility of the ultrasound assisted solvent (UA) method was greater than any of the saponification methods. Compared with the traditional saponification method, the ultrasound assisted solvent method could effectively extract tocopherols from sample matrix without any chemical degradation reactions, especially for complex animal tissue such as liver.

Appearance-based representative samples refining method for palmprint recognition

NASA Astrophysics Data System (ADS)

Wen, Jiajun; Chen, Yan

2012-07-01

The sparse representation can deal with the lack of sample problem due to utilizing of all the training samples. However, the discrimination ability will degrade when more training samples are used for representation. We propose a novel appearance-based palmprint recognition method. We aim to find a compromise between the discrimination ability and the lack of sample problem so as to obtain a proper representation scheme. Under the assumption that the test sample can be well represented by a linear combination of a certain number of training samples, we first select the representative training samples according to the contributions of the samples. Then we further refine the training samples by an iteration procedure, excluding the training sample with the least contribution to the test sample for each time. Experiments on PolyU multispectral palmprint database and two-dimensional and three-dimensional palmprint database show that the proposed method outperforms the conventional appearance-based palmprint recognition methods. Moreover, we also explore and find out the principle of the usage for the key parameters in the proposed algorithm, which facilitates to obtain high-recognition accuracy.

THE SCREENING AND RANKING ALGORITHM FOR CHANGE-POINTS DETECTION IN MULTIPLE SAMPLES

PubMed Central

Song, Chi; Min, Xiaoyi; Zhang, Heping

2016-01-01

The chromosome copy number variation (CNV) is the deviation of genomic regions from their normal copy number states, which may associate with many human diseases. Current genetic studies usually collect hundreds to thousands of samples to study the association between CNV and diseases. CNVs can be called by detecting the change-points in mean for sequences of array-based intensity measurements. Although multiple samples are of interest, the majority of the available CNV calling methods are single sample based. Only a few multiple sample methods have been proposed using scan statistics that are computationally intensive and designed toward either common or rare change-points detection. In this paper, we propose a novel multiple sample method by adaptively combining the scan statistic of the screening and ranking algorithm (SaRa), which is computationally efficient and is able to detect both common and rare change-points. We prove that asymptotically this method can find the true change-points with almost certainty and show in theory that multiple sample methods are superior to single sample methods when shared change-points are of interest. Additionally, we report extensive simulation studies to examine the performance of our proposed method. Finally, using our proposed method as well as two competing approaches, we attempt to detect CNVs in the data from the Primary Open-Angle Glaucoma Genes and Environment study, and conclude that our method is faster and requires less information while our ability to detect the CNVs is comparable or better. PMID:28090239

Efficient global biopolymer sampling with end-transfer configurational bias Monte Carlo

NASA Astrophysics Data System (ADS)

Arya, Gaurav; Schlick, Tamar

2007-01-01

We develop an "end-transfer configurational bias Monte Carlo" method for efficient thermodynamic sampling of complex biopolymers and assess its performance on a mesoscale model of chromatin (oligonucleosome) at different salt conditions compared to other Monte Carlo moves. Our method extends traditional configurational bias by deleting a repeating motif (monomer) from one end of the biopolymer and regrowing it at the opposite end using the standard Rosenbluth scheme. The method's sampling efficiency compared to local moves, pivot rotations, and standard configurational bias is assessed by parameters relating to translational, rotational, and internal degrees of freedom of the oligonucleosome. Our results show that the end-transfer method is superior in sampling every degree of freedom of the oligonucleosomes over other methods at high salt concentrations (weak electrostatics) but worse than the pivot rotations in terms of sampling internal and rotational sampling at low-to-moderate salt concentrations (strong electrostatics). Under all conditions investigated, however, the end-transfer method is several orders of magnitude more efficient than the standard configurational bias approach. This is because the characteristic sampling time of the innermost oligonucleosome motif scales quadratically with the length of the oligonucleosomes for the end-transfer method while it scales exponentially for the traditional configurational-bias method. Thus, the method we propose can significantly improve performance for global biomolecular applications, especially in condensed systems with weak nonbonded interactions and may be combined with local enhancements to improve local sampling.

A comprehensive evaluation of various sensitivity analysis methods: A case study with a hydrological model

DOE PAGES

Gan, Yanjun; Duan, Qingyun; Gong, Wei; ...

2014-01-01

Sensitivity analysis (SA) is a commonly used approach for identifying important parameters that dominate model behaviors. We use a newly developed software package, a Problem Solving environment for Uncertainty Analysis and Design Exploration (PSUADE), to evaluate the effectiveness and efficiency of ten widely used SA methods, including seven qualitative and three quantitative ones. All SA methods are tested using a variety of sampling techniques to screen out the most sensitive (i.e., important) parameters from the insensitive ones. The Sacramento Soil Moisture Accounting (SAC-SMA) model, which has thirteen tunable parameters, is used for illustration. The South Branch Potomac River basin nearmore » Springfield, West Virginia in the U.S. is chosen as the study area. The key findings from this study are: (1) For qualitative SA methods, Correlation Analysis (CA), Regression Analysis (RA), and Gaussian Process (GP) screening methods are shown to be not effective in this example. Morris One-At-a-Time (MOAT) screening is the most efficient, needing only 280 samples to identify the most important parameters, but it is the least robust method. Multivariate Adaptive Regression Splines (MARS), Delta Test (DT) and Sum-Of-Trees (SOT) screening methods need about 400–600 samples for the same purpose. Monte Carlo (MC), Orthogonal Array (OA) and Orthogonal Array based Latin Hypercube (OALH) are appropriate sampling techniques for them; (2) For quantitative SA methods, at least 2777 samples are needed for Fourier Amplitude Sensitivity Test (FAST) to identity parameter main effect. McKay method needs about 360 samples to evaluate the main effect, more than 1000 samples to assess the two-way interaction effect. OALH and LPτ (LPTAU) sampling techniques are more appropriate for McKay method. For the Sobol' method, the minimum samples needed are 1050 to compute the first-order and total sensitivity indices correctly. These comparisons show that qualitative SA methods are more efficient but less accurate and robust than quantitative ones.« less

GalaxyGPCRloop: Template-Based and Ab Initio Structure Sampling of the Extracellular Loops of G-Protein-Coupled Receptors.

PubMed

Won, Jonghun; Lee, Gyu Rie; Park, Hahnbeom; Seok, Chaok

2018-06-07

The second extracellular loops (ECL2s) of G-protein-coupled receptors (GPCRs) are often involved in GPCR functions, and their structures have important implications in drug discovery. However, structure prediction of ECL2 is difficult because of its long length and the structural diversity among different GPCRs. In this study, a new ECL2 conformational sampling method involving both template-based and ab initio sampling was developed. Inspired by the observation of similar ECL2 structures of closely related GPCRs, a template-based sampling method employing loop structure templates selected from the structure database was developed. A new metric for evaluating similarity of the target loop to templates was introduced for template selection. An ab initio loop sampling method was also developed to treat cases without highly similar templates. The ab initio method is based on the previously developed fragment assembly and loop closure method. A new sampling component that takes advantage of secondary structure prediction was added. In addition, a conserved disulfide bridge restraining ECL2 conformation was predicted and analytically incorporated into sampling, reducing the effective dimension of the conformational search space. The sampling method was combined with an existing energy function for comparison with previously reported loop structure prediction methods, and the benchmark test demonstrated outstanding performance.

Conceptual data sampling for breast cancer histology image classification.

PubMed

Rezk, Eman; Awan, Zainab; Islam, Fahad; Jaoua, Ali; Al Maadeed, Somaya; Zhang, Nan; Das, Gautam; Rajpoot, Nasir

2017-10-01

Data analytics have become increasingly complicated as the amount of data has increased. One technique that is used to enable data analytics in large datasets is data sampling, in which a portion of the data is selected to preserve the data characteristics for use in data analytics. In this paper, we introduce a novel data sampling technique that is rooted in formal concept analysis theory. This technique is used to create samples reliant on the data distribution across a set of binary patterns. The proposed sampling technique is applied in classifying the regions of breast cancer histology images as malignant or benign. The performance of our method is compared to other classical sampling methods. The results indicate that our method is efficient and generates an illustrative sample of small size. It is also competing with other sampling methods in terms of sample size and sample quality represented in classification accuracy and F1 measure. Copyright © 2017 Elsevier Ltd. All rights reserved.

14C sample preparation for AMS microdosing studies at Lund University using online combustion and septa-sealed vials

NASA Astrophysics Data System (ADS)

Sydoff, Marie; Stenström, Kristina

2010-04-01

The Department of Physics at Lund University is participating in a European Union project called EUMAPP (European Union Microdose AMS Partnership Programme), in which sample preparation and accelerator mass spectrometry (AMS) measurements of biological samples from microdosing studies have been made. This paper describes a simplified method of converting biological samples to solid graphite for 14C analysis with AMS. The method is based on online combustion of the samples, and reduction of CO 2 in septa-sealed vials. The septa-sealed vials and disposable materials are used to eliminate sample cross-contamination. Measurements of ANU and Ox I standards show deviations of 2% and 3%, respectively, relative to reference values. This level of accuracy is sufficient for biological samples from microdosing studies. Since the method has very few handling steps from sample to graphite, the risk of failure during the sample preparation process is minimized, making the method easy to use in routine preparation of samples.

Laboratory evaluation of sample collection methods (organs vs swabs) for Tasmanian salmon reovirus detection in farmed Atlantic salmon, Salmo salar L.

PubMed

Zainathan, S C; Carson, J; Crane, M St J; Nowak, B F

2013-04-01

The use of swabs relative to organs as a sample collection method for the detection of Tasmanian salmon reovirus (TSRV) in farmed Tasmanian Atlantic salmon, Salmo salar L., was evaluated by RT-qPCR. Evaluation of individual and pooled sample collection (organs vs swabs) was carried out to determine the sensitivity of the collection methods and the effect of pooling of samples for the detection of TSRV. Detection of TSRV in individual samples was as sensitive when organs were sampled compared to swabs, and in pooled samples, organs demonstrated a sensitivity of one 10-fold dilution higher than sampling of pooled swabs. Storage of swabs at 4 °C for t = 24 h demonstrated results similar to those at t = 0. Advantages of using swabs as a preferred sample collection method for the detection of TSRV compared to organ samples are evident from these experimental trials. © 2012 Blackwell Publishing Ltd.

Apparatus and method for handheld sampling

DOEpatents

Staab, Torsten A.

2005-09-20

The present invention includes an apparatus, and corresponding method, for taking a sample. The apparatus is built around a frame designed to be held in at least one hand. A sample media is used to secure the sample. A sample media adapter for securing the sample media is operated by a trigger mechanism connectively attached within the frame to the sample media adapter.

A METHODS COMPARISON FOR COLLECTING MACROINVERTEBRATES IN THE OHIO RIVER

EPA Science Inventory

Collection of representative benthic macroinvertebrate samples from large rivers has been challenging researchers for many years. The objective of our study was to develop an appropriate method(s) for sampling macroinvertebrates from the Ohio River. Four existing sampling metho...

Comparison of four sampling methods for the detection of Salmonella in broiler litter.

PubMed

Buhr, R J; Richardson, L J; Cason, J A; Cox, N A; Fairchild, B D

2007-01-01

Experiments were conducted to compare litter sampling methods for the detection of Salmonella. In experiment 1, chicks were challenged orally with a suspension of naladixic acid-resistant Salmonella and wing banded, and additional nonchallenged chicks were placed into each of 2 challenge pens. Nonchallenged chicks were placed into each nonchallenge pen located adjacent to the challenge pens. At 7, 8, 10, and 11 wk of age the litter was sampled using 4 methods: fecal droppings, litter grab, drag swab, and sock. For the challenge pens, Salmonella-positive samples were detected in 3 of 16 fecal samples, 6 of 16 litter grab samples, 7 of 16 drag swabs samples, and 7 of 16 sock samples. Samples from the nonchallenge pens were Salmonella positive in 2 of 16 litter grab samples, 9 of 16 drag swab samples, and 9 of 16 sock samples. In experiment 2, chicks were challenged with Salmonella, and the litter in the challenge and adjacent nonchallenge pens were sampled at 4, 6, and 8 wk of age with broilers remaining in all pens. For the challenge pens, Salmonella was detected in 10 of 36 fecal samples, 20 of 36 litter grab samples, 14 of 36 drag swab samples, and 26 of 36 sock samples. Samples from the adjacent nonchallenge pens were positive for Salmonella in 6 of 36 fecal droppings samples, 4 of 36 litter grab samples, 7 of 36 drag swab samples, and 19 of 36 sock samples. Sock samples had the highest rates of Salmonella detection. In experiment 3, the litter from a Salmonella-challenged flock was sampled at 7, 8, and 9 wk by socks and drag swabs. In addition, comparisons with drag swabs that were stepped on during sampling were made. Both socks (24 of 36, 67%) and drag swabs that were stepped on (25 of 36, 69%) showed significantly more Salmonella-positive samples than the traditional drag swab method (16 of 36, 44%). Drag swabs that were stepped on had comparable Salmonella detection level to that for socks. Litter sampling methods that incorporate stepping on the sample material while in contact with the litter appear to detect Salmonella in greater incidence than traditional sampling methods of dragging swabs over the litter surface.

A novel, efficient method for estimating the prevalence of acute malnutrition in resource-constrained and crisis-affected settings: A simulation study.

PubMed

Frison, Severine; Kerac, Marko; Checchi, Francesco; Nicholas, Jennifer

2017-01-01

The assessment of the prevalence of acute malnutrition in children under five is widely used for the detection of emergencies, planning interventions, advocacy, and monitoring and evaluation. This study examined PROBIT Methods which convert parameters (mean and standard deviation (SD)) of a normally distributed variable to a cumulative probability below any cut-off to estimate acute malnutrition in children under five using Middle-Upper Arm Circumference (MUAC). We assessed the performance of: PROBIT Method I, with mean MUAC from the survey sample and MUAC SD from a database of previous surveys; and PROBIT Method II, with mean and SD of MUAC observed in the survey sample. Specifically, we generated sub-samples from 852 survey datasets, simulating 100 surveys for eight sample sizes. Overall the methods were tested on 681 600 simulated surveys. PROBIT methods relying on sample sizes as small as 50 had better performance than the classic method for estimating and classifying the prevalence of acute malnutrition. They had better precision in the estimation of acute malnutrition for all sample sizes and better coverage for smaller sample sizes, while having relatively little bias. They classified situations accurately for a threshold of 5% acute malnutrition. Both PROBIT methods had similar outcomes. PROBIT Methods have a clear advantage in the assessment of acute malnutrition prevalence based on MUAC, compared to the classic method. Their use would require much lower sample sizes, thus enable great time and resource savings and permit timely and/or locally relevant prevalence estimates of acute malnutrition for a swift and well-targeted response.

Approximation of the exponential integral (well function) using sampling methods

NASA Astrophysics Data System (ADS)

Baalousha, Husam Musa

2015-04-01

Exponential integral (also known as well function) is often used in hydrogeology to solve Theis and Hantush equations. Many methods have been developed to approximate the exponential integral. Most of these methods are based on numerical approximations and are valid for a certain range of the argument value. This paper presents a new approach to approximate the exponential integral. The new approach is based on sampling methods. Three different sampling methods; Latin Hypercube Sampling (LHS), Orthogonal Array (OA), and Orthogonal Array-based Latin Hypercube (OA-LH) have been used to approximate the function. Different argument values, covering a wide range, have been used. The results of sampling methods were compared with results obtained by Mathematica software, which was used as a benchmark. All three sampling methods converge to the result obtained by Mathematica, at different rates. It was found that the orthogonal array (OA) method has the fastest convergence rate compared with LHS and OA-LH. The root mean square error RMSE of OA was in the order of 1E-08. This method can be used with any argument value, and can be used to solve other integrals in hydrogeology such as the leaky aquifer integral.

Comparison of indoor air sampling and dust collection methods for fungal exposure assessment using quantitative PCR.

PubMed

Cox, Jennie; Indugula, Reshmi; Vesper, Stephen; Zhu, Zheng; Jandarov, Roman; Reponen, Tiina

2017-10-18

Evaluating fungal contamination indoors is complicated because of the many different sampling methods utilized. In this study, fungal contamination was evaluated using five sampling methods and four matrices for results. The five sampling methods were a 48 hour indoor air sample collected with a Button™ inhalable aerosol sampler and four types of dust samples: a vacuumed floor dust sample, newly settled dust collected for four weeks onto two types of electrostatic dust cloths (EDCs) in trays, and a wipe sample of dust from above floor surfaces. The samples were obtained in the bedrooms of asthmatic children (n = 14). Quantitative polymerase chain reaction (qPCR) was used to analyze the dust and air samples for the 36 fungal species that make up the Environmental Relative Moldiness Index (ERMI). The results from the samples were compared by four matrices: total concentration of fungal cells, concentration of fungal species associated with indoor environments, concentration of fungal species associated with outdoor environments, and ERMI values (or ERMI-like values for air samples). The ERMI values for the dust samples and the ERMI-like values for the 48 hour air samples were not significantly different. The total cell concentrations of the 36 species obtained with the four dust collection methods correlated significantly (r = 0.64-0.79, p < 0.05), with the exception of the vacuumed floor dust and newly settled dust. In addition, fungal cell concentrations of indoor associated species correlated well between all four dust sampling methods (r = 0.68-0.86, p < 0.01). No correlation was found between the fungal concentrations in the air and dust samples primarily because of differences in concentrations of Cladosporium cladosporioides Type 1 and Epicoccum nigrum. A representative type of dust sample and a 48 hour air sample might both provide useful information about fungal exposures.

Combinatorial Screening Of Inorganic And Organometallic Materials

DOEpatents

Li, Yi , Li, Jing , Britton, Ted W.

2002-06-25

A method for differentiating and enumerating nucleated red blood cells in a blood sample is described. The method includes the steps of lysing red blood cells of a blood sample with a lytic reagent, measuring nucleated blood cells by DC impedance measurement in a non-focused flow aperture, differentiating nucleated red blood cells from other cell types, and reporting nucleated red blood cells in the blood sample. The method further includes subtracting nucleated red blood cells and other interference materials from the count of remaining blood cells, and reporting a corrected white blood cell count of the blood sample. Additionally, the method further includes measuring spectrophotometric absorbance of the sample mixture at a predetermined wavelength of a hemoglobin chromogen formed upon lysing the blood sample, and reporting hemoglobin concentration of the blood sample.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, Ashish; McNulty, Ian; Munson, Todd

We propose a new approach to robustly retrieve the exit wave of an extended sample from its coherent diffraction pattern by exploiting sparsity of the sample's edges. This approach enables imaging of an extended sample with a single view, without ptychography. We introduce nonlinear optimization methods that promote sparsity, and we derive update rules to robustly recover the sample's exit wave. We test these methods on simulated samples by varying the sparsity of the edge-detected representation of the exit wave. Finally, our tests illustrate the strengths and limitations of the proposed method in imaging extended samples.

Effect of DNA Extraction Methods and Sampling Techniques on the Apparent Structure of Cow and Sheep Rumen Microbial Communities

PubMed Central

Henderson, Gemma; Cox, Faith; Kittelmann, Sandra; Miri, Vahideh Heidarian; Zethof, Michael; Noel, Samantha J.; Waghorn, Garry C.; Janssen, Peter H.

2013-01-01

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, comparison of data from studies in which different sampling techniques, different rumen sample fractions or different DNA extraction methods were used should be avoided. PMID:24040342

Effect of DNA extraction methods and sampling techniques on the apparent structure of cow and sheep rumen microbial communities.

PubMed

Henderson, Gemma; Cox, Faith; Kittelmann, Sandra; Miri, Vahideh Heidarian; Zethof, Michael; Noel, Samantha J; Waghorn, Garry C; Janssen, Peter H

2013-01-01

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, comparison of data from studies in which different sampling techniques, different rumen sample fractions or different DNA extraction methods were used should be avoided.

Profiling Cholinesterase Adduction: A High-Throughput Prioritization Method for Organophosphate Exposure Samples

PubMed Central

Carter, Melissa D.; Crow, Brian S.; Pantazides, Brooke G.; Watson, Caroline M.; deCastro, B. Rey; Thomas, Jerry D.; Blake, Thomas A.; Johnson, Rudolph C.

2017-01-01

A high-throughput prioritization method was developed for use with a validated confirmatory method detecting organophosphorus nerve agent exposure by immunomagnetic separation-HPLC-MS/MS. A ballistic gradient was incorporated into this analytical method in order to profile unadducted butyrylcholinesterase (BChE) in clinical samples. With Zhang, et al. 1999’s Z′-factor of 0.88 ± 0.01 (SD) of control analytes and Z-factor of 0.25 ± 0.06 (SD) of serum samples, the assay is rated an “excellent assay” for the synthetic peptide controls used and a “double assay” when used to prioritize clinical samples. Hits, defined as samples containing BChE Ser-198 adducts or no BChE present, were analyzed in a confirmatory method for identification and quantitation of the BChE adduct, if present. The ability to prioritize samples by highest exposure for confirmatory analysis is of particular importance in an exposure to cholinesterase inhibitors such as organophosphorus nerve agents where a large number of clinical samples may be collected. In an initial blind screen, 67 out of 70 samples were accurately identified giving an assay accuracy of 96% and yielded no false negatives. The method is the first to provide a high-throughput prioritization assay for profiling adduction of Ser-198 BChE in clinical samples. PMID:23954929

Validation sampling can reduce bias in health care database studies: an illustration using influenza vaccination effectiveness.

PubMed

Nelson, Jennifer Clark; Marsh, Tracey; Lumley, Thomas; Larson, Eric B; Jackson, Lisa A; Jackson, Michael L

2013-08-01

Estimates of treatment effectiveness in epidemiologic studies using large observational health care databases may be biased owing to inaccurate or incomplete information on important confounders. Study methods that collect and incorporate more comprehensive confounder data on a validation cohort may reduce confounding bias. We applied two such methods, namely imputation and reweighting, to Group Health administrative data (full sample) supplemented by more detailed confounder data from the Adult Changes in Thought study (validation sample). We used influenza vaccination effectiveness (with an unexposed comparator group) as an example and evaluated each method's ability to reduce bias using the control time period before influenza circulation. Both methods reduced, but did not completely eliminate, the bias compared with traditional effectiveness estimates that do not use the validation sample confounders. Although these results support the use of validation sampling methods to improve the accuracy of comparative effectiveness findings from health care database studies, they also illustrate that the success of such methods depends on many factors, including the ability to measure important confounders in a representative and large enough validation sample, the comparability of the full sample and validation sample, and the accuracy with which the data can be imputed or reweighted using the additional validation sample information. Copyright © 2013 Elsevier Inc. All rights reserved.

Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

PubMed

Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco

2016-01-01

Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio

PubMed Central

Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco

2016-01-01

Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population’s sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns. PMID:27441554

[Free crystalline silica: a comparison of methods for its determination in total dust].

PubMed

Maciejewska, Aleksandra; Szadkowska-Stańczyk, Irena; Kondratowicz, Grzegorz

2005-01-01

The major objective of the study was to compare and investigate the usefulness of quantitative analyses of free crystalline silica (FCS) in the assessment of dust exposure in samples of total dust of varied composition, using three methods: chemical method in common use in Poland; infrared spectrometry; and x-ray powder diffraction. Mineral composition and FCS contents were investigated in 9 laboratory samples of raw materials, materials, and industrial wastes, containing from about 2 to over 80% of crystalline silica and reduced to particles of size corresponding with that of total dust. Sample components were identified using XRD and FT-IR methods. Ten independent determinations of FCS with each of the three study methods were performed in dust samples. An analysis of linear correlation was applied to investigate interrelationship between mean FCS determinations. In analyzed dust samples, along with silica dust there were numerous minerals interfering with silica during the quantitative analysis. Comparison of mean results of FCS determinations showed that the results obtained using the FT-IR method were by 12-13% lower than those obtained with two other methods. However, the differences observed were within the limits of changeability of results associated with their precision and dependence on reference materials used. Assessment of occupational exposure to dusts containing crystalline silica can be performed on the basis of quantitative analysis of FCS in total dusts using each of the compared methods. The FT-IR method is most appropriate for the FCS determination in samples of small amount of silica or collected at low dust concentrations; the XRD method for the analysis of multicomponent samples; and the chemical method in the case of medium and high FCS contents in samples or high concentrations of dusts in the work environment.

Assessment of Different Sampling Methods for Measuring and Representing Macular Cone Density Using Flood-Illuminated Adaptive Optics

PubMed Central

Feng, Shu; Gale, Michael J.; Fay, Jonathan D.; Faridi, Ambar; Titus, Hope E.; Garg, Anupam K.; Michaels, Keith V.; Erker, Laura R.; Peters, Dawn; Smith, Travis B.; Pennesi, Mark E.

2015-01-01

Purpose To describe a standardized flood-illuminated adaptive optics (AO) imaging protocol suitable for the clinical setting and to assess sampling methods for measuring cone density. Methods Cone density was calculated following three measurement protocols: 50 × 50-μm sampling window values every 0.5° along the horizontal and vertical meridians (fixed-interval method), the mean density of expanding 0.5°-wide arcuate areas in the nasal, temporal, superior, and inferior quadrants (arcuate mean method), and the peak cone density of a 50 × 50-μm sampling window within expanding arcuate areas near the meridian (peak density method). Repeated imaging was performed in nine subjects to determine intersession repeatability of cone density. Results Cone density montages could be created for 67 of the 74 subjects. Image quality was determined to be adequate for automated cone counting for 35 (52%) of the 67 subjects. We found that cone density varied with different sampling methods and regions tested. In the nasal and temporal quadrants, peak density most closely resembled histological data, whereas the arcuate mean and fixed-interval methods tended to underestimate the density compared with histological data. However, in the inferior and superior quadrants, arcuate mean and fixed-interval methods most closely matched histological data, whereas the peak density method overestimated cone density compared with histological data. Intersession repeatability testing showed that repeatability was greatest when sampling by arcuate mean and lowest when sampling by fixed interval. Conclusions We show that different methods of sampling can significantly affect cone density measurements. Therefore, care must be taken when interpreting cone density results, even in a normal population. PMID:26325414

Comparing the NIOSH Method 5040 to a Diesel Particulate Matter Meter for Elemental Carbon

NASA Astrophysics Data System (ADS)

Ayers, David Matthew

Introduction: The sampling of elemental carbon has been associated with monitoring exposures in the trucking and mining industries. Recently, in the field of engineered nanomaterials, single wall and muti-wall carbon nanotubes (MWCNTs) are being produced in ever increasing quantities. The only approved atmospheric sampling for multi-wall carbon nanotubes in NIOSH Method 5040. These results are accurate but can take up to 30 days for sample results to be received. Objectives: Compare the results of elemental carbon sampling from the NIOSH Method 5040 to a Diesel Particulate Matter (DPM) Meter. Methods: MWCNTs were transferred and weighed between several trays placed on a scale. The NIOSH Method 5040 and DPM sampling train was hung 6 inches above the receiving tray. The transferring and weighing of the MWCNTs created an aerosol containing elemental carbon. Twenty-one total samples using both meters type were collected. Results: The assumptions for a Two-Way ANOVA were violated therefore, Mann-Whitney U Tests and a Kruskal-Wallis Test were performed. The hypotheses for both research questions were rejected. There was a significant difference in the EC concentrations obtained by the NIOSH Method 5040 and the DPM meter. There were also significant differences in elemental carbon level concentrations when sampled using a DPM meter versus a sampling pump based upon the three concentration levels (low, medium and high). Conclusions: The differences in the EC concentrations were statistically significant therefore, the two methods (NIOSH Method 5040 and DPM) are not the same. The NIOSH Method 5040 should continue to be the only authorized method of establishing an EC concentration for MWCNTs until a MWCNT specific method or an instantaneous meter is invented.

Methods for estimating the amount of vernal pool habitat in the northeastern United States

USGS Publications Warehouse

Van Meter, R.; Bailey, L.L.; Grant, E.H.C.

2008-01-01

The loss of small, seasonal wetlands is a major concern for a variety of state, local, and federal organizations in the northeastern U.S. Identifying and estimating the number of vernal pools within a given region is critical to developing long-term conservation and management strategies for these unique habitats and their faunal communities. We use three probabilistic sampling methods (simple random sampling, adaptive cluster sampling, and the dual frame method) to estimate the number of vernal pools on protected, forested lands. Overall, these methods yielded similar values of vernal pool abundance for each study area, and suggest that photographic interpretation alone may grossly underestimate the number of vernal pools in forested habitats. We compare the relative efficiency of each method and discuss ways of improving precision. Acknowledging that the objectives of a study or monitoring program ultimately determine which sampling designs are most appropriate, we recommend that some type of probabilistic sampling method be applied. We view the dual-frame method as an especially useful way of combining incomplete remote sensing methods, such as aerial photograph interpretation, with a probabilistic sample of the entire area of interest to provide more robust estimates of the number of vernal pools and a more representative sample of existing vernal pool habitats.

Method and apparatus for measuring nuclear magnetic properties

DOEpatents

Weitekamp, D.P.; Bielecki, A.; Zax, D.B.; Zilm, K.W.; Pines, A.

1987-12-01

A method for studying the chemical and structural characteristics of materials is disclosed. The method includes placement of a sample material in a high strength polarizing magnetic field to order the sample nuclei. The condition used to order the sample is then removed abruptly and the ordering of the sample allowed to evolve for a time interval. At the end of the time interval, the ordering of the sample is measured by conventional nuclear magnetic resonance techniques. 5 figs.

Method and apparatus for measuring nuclear magnetic properties

DOEpatents

Weitekamp, Daniel P.; Bielecki, Anthony; Zax, David B.; Zilm, Kurt W.; Pines, Alexander

1987-01-01

A method for studying the chemical and structural characteristics of materials is disclosed. The method includes placement of a sample material in a high strength polarizing magnetic field to order the sample nucleii. The condition used to order the sample is then removed abruptly and the ordering of the sample allowed to evolve for a time interval. At the end of the time interval, the ordering of the sample is measured by conventional nuclear magnetic resonance techniques.

A LITERATURE REVIEW OF WIPE SAMPLING METHODS ...

EPA Pesticide Factsheets

Wipe sampling is an important technique for the estimation of contaminant deposition in buildings, homes, or outdoor surfaces as a source of possible human exposure. Numerousmethods of wipe sampling exist, and each method has its own specification for the type of wipe, wetting solvent, and determinative step to be used, depending upon the contaminant of concern. The objective of this report is to concisely summarize the findings of a literature review that was conducted to identify the state-of-the-art wipe sampling techniques for a target list of compounds. This report describes the methods used to perform the literature review; a brief review of wipe sampling techniques in general; an analysis of physical and chemical properties of each target analyte; an analysis of wipe sampling techniques for the target analyte list; and asummary of the wipe sampling techniques for the target analyte list, including existing data gaps. In general, no overwhelming consensus can be drawn from the current literature on how to collect a wipe sample for the chemical warfare agents, organophosphate pesticides, and other toxic industrial chemicals of interest to this study. Different methods, media, and wetting solvents have been recommended and used by various groups and different studies. For many of the compounds of interest, no specific wipe sampling methodology has been established for their collection. Before a wipe sampling method (or methods) can be established for the co

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

NASA Astrophysics Data System (ADS)

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 7Li(p, n)7Be 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.

Detection and monitoring of invasive exotic plants: a comparison of four sampling methods

Treesearch

Cynthia D. Huebner

2007-01-01

The ability to detect and monitor exotic invasive plants is likely to vary depending on the sampling method employed. Methods with strong qualitative thoroughness for species detection often lack the intensity necessary to monitor vegetation change. Four sampling methods (systematic plot, stratified-random plot, modified Whittaker, and timed meander) in hemlock and red...

A structured sparse regression method for estimating isoform expression level from multi-sample RNA-seq data.

PubMed

Zhang, L; Liu, X J

2016-06-03

With the rapid development of next-generation high-throughput sequencing technology, RNA-seq has become a standard and important technique for transcriptome analysis. For multi-sample RNA-seq data, the existing expression estimation methods usually deal with each single-RNA-seq sample, and ignore that the read distributions are consistent across multiple samples. In the current study, we propose a structured sparse regression method, SSRSeq, to estimate isoform expression using multi-sample RNA-seq data. SSRSeq uses a non-parameter model to capture the general tendency of non-uniformity read distribution for all genes across multiple samples. Additionally, our method adds a structured sparse regularization, which not only incorporates the sparse specificity between a gene and its corresponding isoform expression levels, but also reduces the effects of noisy reads, especially for lowly expressed genes and isoforms. Four real datasets were used to evaluate our method on isoform expression estimation. Compared with other popular methods, SSRSeq reduced the variance between multiple samples, and produced more accurate isoform expression estimations, and thus more meaningful biological interpretations.

Acid digestion of geological and environmental samples using open-vessel focused microwave digestion.

PubMed

Taylor, Vivien F; Toms, Andrew; Longerich, Henry P

2002-01-01

The application of open vessel focused microwave acid digestion is described for the preparation of geological and environmental samples for analysis using inductively coupled plasma-mass spectrometry (ICP-MS). The method is compared to conventional closed-vessel high pressure methods which are limited in the use of HF to break down silicates. Open-vessel acid digestion more conveniently enables the use of HF to remove Si from geological and plant samples as volatile SiF4, as well as evaporation-to-dryness and sequential acid addition during the procedure. Rock reference materials (G-2 granite, MRG-1 gabbros, SY-2 syenite, JA-1 andesite, and JB-2 and SRM-688 basalts) and plant reference materials (BCR and IAEA lichens, peach leaves, apple leaves, Durham wheat flour, and pine needles) were digested with results comparable to conventional hotplate digestion. The microwave digestion method gave poor results for granitic samples containing refractory minerals, however fusion was the preferred method of preparation for these samples. Sample preparation time was reduced from several days, using conventional hotplate digestion method, to one hour per sample using our microwave method.

Enhanced sampling simulations to construct free-energy landscape of protein-partner substrate interaction.

PubMed

Ikebe, Jinzen; Umezawa, Koji; Higo, Junichi

2016-03-01

Molecular dynamics (MD) simulations using all-atom and explicit solvent models provide valuable information on the detailed behavior of protein-partner substrate binding at the atomic level. As the power of computational resources increase, MD simulations are being used more widely and easily. However, it is still difficult to investigate the thermodynamic properties of protein-partner substrate binding and protein folding with conventional MD simulations. Enhanced sampling methods have been developed to sample conformations that reflect equilibrium conditions in a more efficient manner than conventional MD simulations, thereby allowing the construction of accurate free-energy landscapes. In this review, we discuss these enhanced sampling methods using a series of case-by-case examples. In particular, we review enhanced sampling methods conforming to trivial trajectory parallelization, virtual-system coupled multicanonical MD, and adaptive lambda square dynamics. These methods have been recently developed based on the existing method of multicanonical MD simulation. Their applications are reviewed with an emphasis on describing their practical implementation. In our concluding remarks we explore extensions of the enhanced sampling methods that may allow for even more efficient sampling.

A sequential bioequivalence design with a potential ethical advantage.

PubMed

Fuglsang, Anders

2014-07-01

This paper introduces a two-stage approach for evaluation of bioequivalence, where, in contrast to the designs of Diane Potvin and co-workers, two stages are mandatory regardless of the data obtained at stage 1. The approach is derived from Potvin's method C. It is shown that under circumstances with relatively high variability and relatively low initial sample size, this method has an advantage over Potvin's approaches in terms of sample sizes while controlling type I error rates at or below 5% with a minute occasional trade-off in power. Ethically and economically, the method may thus be an attractive alternative to the Potvin designs. It is also shown that when using the method introduced here, average total sample sizes are rather independent of initial sample size. Finally, it is shown that when a futility rule in terms of sample size for stage 2 is incorporated into this method, i.e., when a second stage can be abolished due to sample size considerations, there is often an advantage in terms of power or sample size as compared to the previously published methods.

Common methods for fecal sample storage in field studies yield consistent signatures of individual identity in microbiome sequencing data.

PubMed

Blekhman, Ran; Tang, Karen; Archie, Elizabeth A; Barreiro, Luis B; Johnson, Zachary P; Wilson, Mark E; Kohn, Jordan; Yuan, Michael L; Gesquiere, Laurence; Grieneisen, Laura E; Tung, Jenny

2016-08-16

Field studies of wild vertebrates are frequently associated with extensive collections of banked fecal samples-unique resources for understanding ecological, behavioral, and phylogenetic effects on the gut microbiome. However, we do not understand whether sample storage methods confound the ability to investigate interindividual variation in gut microbiome profiles. Here, we extend previous work on storage methods for gut microbiome samples by comparing immediate freezing, the gold standard of preservation, to three methods commonly used in vertebrate field studies: lyophilization, storage in ethanol, and storage in RNAlater. We found that the signature of individual identity consistently outweighed storage effects: alpha diversity and beta diversity measures were significantly correlated across methods, and while samples often clustered by donor, they never clustered by storage method. Provided that all analyzed samples are stored the same way, banked fecal samples therefore appear highly suitable for investigating variation in gut microbiota. Our results open the door to a much-expanded perspective on variation in the gut microbiome across species and ecological contexts.

Relative efficiency of anuran sampling methods in a restinga habitat (Jurubatiba, Rio de Janeiro, Brazil).

PubMed

Rocha, C F D; Van Sluys, M; Hatano, F H; Boquimpani-Freitas, L; Marra, R V; Marques, R V

2004-11-01

Studies on anurans in restinga habitats are few and, as a result, there is little information on which methods are more efficient for sampling them in this environment. Ten methods are usually used for sampling anuran communities in tropical and sub-tropical areas. In this study we evaluate which methods are more appropriate for this purpose in the restinga environment of Parque Nacional da Restinga de Jurubatiba. We analyzed six methods among those usually used for anuran samplings. For each method, we recorded the total amount of time spent (in min.), the number of researchers involved, and the number of species captured. We calculated a capture efficiency index (time necessary for a researcher to capture an individual frog) in order to make comparable the data obtained. Of the methods analyzed, the species inventory (9.7 min/searcher /ind.- MSI; richness = 6; abundance = 23) and the breeding site survey (9.5 MSI; richness = 4; abundance = 22) were the most efficient. The visual encounter inventory (45.0 MSI) and patch sampling (65.0 MSI) methods were of comparatively lower efficiency restinga, whereas the plot sampling and the pit-fall traps with drift-fence methods resulted in no frog capture. We conclude that there is a considerable difference in efficiency of methods used in the restinga environment and that the complete species inventory method is highly efficient for sampling frogs in the restinga studied and may be so in other restinga environments. Methods that are usually efficient in forested areas seem to be of little value in open restinga habitats.

Rapid method for sampling metals for materials identification

NASA Technical Reports Server (NTRS)

Higgins, L. E.

1971-01-01

Nondamaging process similar to electrochemical machining is useful in obtaining metal samples from places inaccessible to conventional sampling methods or where methods would be hazardous or contaminating to specimens. Process applies to industries where metals or metal alloys play a vital role.

Methods for making nucleotide probes for sequencing and synthesis

DOEpatents

Church, George M; Zhang, Kun; Chou, Joseph

2014-07-08

Compositions and methods for making a plurality of probes for analyzing a plurality of nucleic acid samples are provided. Compositions and methods for analyzing a plurality of nucleic acid samples to obtain sequence information in each nucleic acid sample are also provided.

Systematic Evaluation of Aggressive Air Sampling for Bacillus ...

EPA Pesticide Factsheets

Report The primary objectives of this project were to evaluate the Aggressive Air Sampling (AAS) method compared to currently used surface sampling methods and to determine if AAS is a viable option for sampling Bacillus anthracis spores.

Evaluation of Surface Sampling for Bacillus Spores Using ...

EPA Pesticide Factsheets

Report The primary objectives of this project were to evaluate the Aggressive Air Sampling (AAS) method compared to currently used surface sampling methods and to determine if AAS is a viable option for sampling Bacillus anthracis spores.

Effects of Sample Preparation on the Infrared Reflectance Spectra of Powders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.

2015-05-22

While reflectance spectroscopy is a useful tool in identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-packedmore » as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.« less

Effects of sample preparation on the infrared reflectance spectra of powders

NASA Astrophysics Data System (ADS)

Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.; Su, Yin-Fong; Blake, Thomas A.; Forland, Brenda M.

2015-05-01

While reflectance spectroscopy is a useful tool for identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-loaded as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample can have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.

Mapping species distributions with MAXENT using a geographically biased sample of presence data: a performance assessment of methods for correcting sampling bias.

PubMed

Fourcade, Yoan; Engler, Jan O; Rödder, Dennis; Secondi, Jean

2014-01-01

MAXENT is now a common species distribution modeling (SDM) tool used by conservation practitioners for predicting the distribution of a species from a set of records and environmental predictors. However, datasets of species occurrence used to train the model are often biased in the geographical space because of unequal sampling effort across the study area. This bias may be a source of strong inaccuracy in the resulting model and could lead to incorrect predictions. Although a number of sampling bias correction methods have been proposed, there is no consensual guideline to account for it. We compared here the performance of five methods of bias correction on three datasets of species occurrence: one "virtual" derived from a land cover map, and two actual datasets for a turtle (Chrysemys picta) and a salamander (Plethodon cylindraceus). We subjected these datasets to four types of sampling biases corresponding to potential types of empirical biases. We applied five correction methods to the biased samples and compared the outputs of distribution models to unbiased datasets to assess the overall correction performance of each method. The results revealed that the ability of methods to correct the initial sampling bias varied greatly depending on bias type, bias intensity and species. However, the simple systematic sampling of records consistently ranked among the best performing across the range of conditions tested, whereas other methods performed more poorly in most cases. The strong effect of initial conditions on correction performance highlights the need for further research to develop a step-by-step guideline to account for sampling bias. However, this method seems to be the most efficient in correcting sampling bias and should be advised in most cases.

Mapping Species Distributions with MAXENT Using a Geographically Biased Sample of Presence Data: A Performance Assessment of Methods for Correcting Sampling Bias

PubMed Central

Fourcade, Yoan; Engler, Jan O.; Rödder, Dennis; Secondi, Jean

2014-01-01

MAXENT is now a common species distribution modeling (SDM) tool used by conservation practitioners for predicting the distribution of a species from a set of records and environmental predictors. However, datasets of species occurrence used to train the model are often biased in the geographical space because of unequal sampling effort across the study area. This bias may be a source of strong inaccuracy in the resulting model and could lead to incorrect predictions. Although a number of sampling bias correction methods have been proposed, there is no consensual guideline to account for it. We compared here the performance of five methods of bias correction on three datasets of species occurrence: one “virtual” derived from a land cover map, and two actual datasets for a turtle (Chrysemys picta) and a salamander (Plethodon cylindraceus). We subjected these datasets to four types of sampling biases corresponding to potential types of empirical biases. We applied five correction methods to the biased samples and compared the outputs of distribution models to unbiased datasets to assess the overall correction performance of each method. The results revealed that the ability of methods to correct the initial sampling bias varied greatly depending on bias type, bias intensity and species. However, the simple systematic sampling of records consistently ranked among the best performing across the range of conditions tested, whereas other methods performed more poorly in most cases. The strong effect of initial conditions on correction performance highlights the need for further research to develop a step-by-step guideline to account for sampling bias. However, this method seems to be the most efficient in correcting sampling bias and should be advised in most cases. PMID:24818607

Characterization of long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads in vitro by two distinct sample collection methods.

PubMed

Tulipan, Rachel J; Phillips, Heidi; Garrett, Laura D; Dirikolu, Levent; Mitchell, Mark A

2017-05-01

OBJECTIVE To characterize long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads in vitro by comparing 2 distinct sample collection methods designed to mimic 2 in vivo environments. SAMPLES 162 CI-CSH beads containing 4.6 mg of carboplatin (2.4 mg of platinum/bead). PROCEDURES For method 1, which mimicked an in vivo environment with rapid and complete fluid exchange, each of 3 plastic 10-mL conical tubes contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained by evacuation of all fluid at 1, 2, 3, 6, 9, and 12 hours and 1, 2, 3, 6, 9, 12, 15, 18, 22, 26, and 30 days. Five milliliters of fresh PBS solution was then added to each tube. For method 2, which mimicked an in vivo environment with no fluid exchange, each of 51 tubes (ie, 3 tubes/17 sample collection times) contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained from the assigned tubes for each time point. All samples were analyzed for platinum content by inductively coupled plasma-mass spectrometry. RESULTS Platinum was released from CI-CSH beads for 22 to 30 days. Significant differences were found in platinum concentration and percentage of platinum eluted from CI-CSH beads over time for each method. Platinum concentrations and elution percentages in method 2 samples were significantly higher than those of method 1 samples, except for the first hour measurements. CONCLUSIONS AND CLINICAL RELEVANCE Sample collection methods 1 and 2 may provide estimates of the minimum and maximum platinum release, respectively, from CI-CSH beads in vivo.

Probabilistic inference using linear Gaussian importance sampling for hybrid Bayesian networks

NASA Astrophysics Data System (ADS)

Sun, Wei; Chang, K. C.

2005-05-01

Probabilistic inference for Bayesian networks is in general NP-hard using either exact algorithms or approximate methods. However, for very complex networks, only the approximate methods such as stochastic sampling could be used to provide a solution given any time constraint. There are several simulation methods currently available. They include logic sampling (the first proposed stochastic method for Bayesian networks, the likelihood weighting algorithm) the most commonly used simulation method because of its simplicity and efficiency, the Markov blanket scoring method, and the importance sampling algorithm. In this paper, we first briefly review and compare these available simulation methods, then we propose an improved importance sampling algorithm called linear Gaussian importance sampling algorithm for general hybrid model (LGIS). LGIS is aimed for hybrid Bayesian networks consisting of both discrete and continuous random variables with arbitrary distributions. It uses linear function and Gaussian additive noise to approximate the true conditional probability distribution for continuous variable given both its parents and evidence in a Bayesian network. One of the most important features of the newly developed method is that it can adaptively learn the optimal important function from the previous samples. We test the inference performance of LGIS using a 16-node linear Gaussian model and a 6-node general hybrid model. The performance comparison with other well-known methods such as Junction tree (JT) and likelihood weighting (LW) shows that LGIS-GHM is very promising.

Detection of oral HPV infection - Comparison of two different specimen collection methods and two HPV detection methods.

PubMed

de Souza, Marjorie M A; Hartel, Gunter; Whiteman, David C; Antonsson, Annika

2018-04-01

Very little is known about the natural history of oral HPV infection. Several different methods exist to collect oral specimens and detect HPV, but their respective performance characteristics are unknown. We compared two different methods for oral specimen collection (oral saline rinse and commercial saliva kit) from 96 individuals and then analyzed the samples for HPV by two different PCR detection methods (single GP5+/6+ PCR and nested MY09/11 and GP5+/6+ PCR). For the oral rinse samples, the oral HPV prevalence was 10.4% (GP+ PCR; 10% repeatability) vs 11.5% (nested PCR method; 100% repeatability). For the commercial saliva kit samples, the prevalences were 3.1% vs 16.7% with the GP+ PCR vs the nested PCR method (repeatability 100% for both detection methods). Overall the agreement was fair or poor between samples and methods (kappa 0.06-0.36). Standardizing methods of oral sample collection and HPV detection would ensure comparability between future oral HPV studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of sampling methods for Bacillus spore-contaminated HVAC filters

PubMed Central

Calfee, M. Worth; Rose, Laura J.; Tufts, Jenia; Morse, Stephen; Clayton, Matt; Touati, Abderrahmane; Griffin-Gatchalian, Nicole; Slone, Christina; McSweeney, Neal

2016-01-01

The objective of this study was to compare an extraction-based sampling method to two vacuum-based sampling methods (vacuum sock and 37 mm cassette filter) with regards to their ability to recover Bacillus atrophaeus spores (surrogate for Bacillus anthracis) from pleated heating, ventilation, and air conditioning (HVAC) filters that are typically found in commercial and residential buildings. Electrostatic and mechanical HVAC filters were tested, both without and after loading with dust to 50% of their total holding capacity. The results were analyzed by one-way ANOVA across material types, presence or absence of dust, and sampling device. The extraction method gave higher relative recoveries than the two vacuum methods evaluated (p ≤ 0.001). On average, recoveries obtained by the vacuum methods were about 30% of those achieved by the extraction method. Relative recoveries between the two vacuum methods were not significantly different (p > 0.05). Although extraction methods yielded higher recoveries than vacuum methods, either HVAC filter sampling approach may provide a rapid and inexpensive mechanism for understanding the extent of contamination following a wide-area biological release incident. PMID:24184312

Evaluation of sampling methods for Bacillus spore-contaminated HVAC filters.

PubMed

Calfee, M Worth; Rose, Laura J; Tufts, Jenia; Morse, Stephen; Clayton, Matt; Touati, Abderrahmane; Griffin-Gatchalian, Nicole; Slone, Christina; McSweeney, Neal

2014-01-01

The objective of this study was to compare an extraction-based sampling method to two vacuum-based sampling methods (vacuum sock and 37mm cassette filter) with regards to their ability to recover Bacillus atrophaeus spores (surrogate for Bacillus anthracis) from pleated heating, ventilation, and air conditioning (HVAC) filters that are typically found in commercial and residential buildings. Electrostatic and mechanical HVAC filters were tested, both without and after loading with dust to 50% of their total holding capacity. The results were analyzed by one-way ANOVA across material types, presence or absence of dust, and sampling device. The extraction method gave higher relative recoveries than the two vacuum methods evaluated (p≤0.001). On average, recoveries obtained by the vacuum methods were about 30% of those achieved by the extraction method. Relative recoveries between the two vacuum methods were not significantly different (p>0.05). Although extraction methods yielded higher recoveries than vacuum methods, either HVAC filter sampling approach may provide a rapid and inexpensive mechanism for understanding the extent of contamination following a wide-area biological release incident. Published by Elsevier B.V.

An evaluation of flow-stratified sampling for estimating suspended sediment loads

Treesearch

Robert B. Thomas; Jack Lewis

1995-01-01

Abstract - Flow-stratified sampling is a new method for sampling water quality constituents such as suspended sediment to estimate loads. As with selection-at-list-time (SALT) and time-stratified sampling, flow-stratified sampling is a statistical method requiring random sampling, and yielding unbiased estimates of load and variance. It can be used to estimate event...

Reconstructing genealogies of serial samples under the assumption of a molecular clock using serial-sample UPGMA.

PubMed

Drummond, A; Rodrigo, A G

2000-12-01

Reconstruction of evolutionary relationships from noncontemporaneous molecular samples provides a new challenge for phylogenetic reconstruction methods. With recent biotechnological advances there has been an increase in molecular sequencing throughput, and the potential to obtain serial samples of sequences from populations, including rapidly evolving pathogens, is fast being realized. A new method called the serial-sample unweighted pair grouping method with arithmetic means (sUPGMA) is presented that reconstructs a genealogy or phylogeny of sequences sampled serially in time using a matrix of pairwise distances. The resulting tree depicts the terminal lineages of each sample ending at a different level consistent with the sample's temporal order. Since sUPGMA is a variant of UPGMA, it will perform best when sequences have evolved at a constant rate (i.e., according to a molecular clock). On simulated data, this new method performs better than standard cluster analysis under a variety of longitudinal sampling strategies. Serial-sample UPGMA is particularly useful for analysis of longitudinal samples of viruses and bacteria, as well as ancient DNA samples, with the minimal requirement that samples of sequences be ordered in time.

A Novel Method to Handle the Effect of Uneven Sampling Effort in Biodiversity Databases

PubMed Central

Pardo, Iker; Pata, María P.; Gómez, Daniel; García, María B.

2013-01-01

How reliable are results on spatial distribution of biodiversity based on databases? Many studies have evidenced the uncertainty related to this kind of analysis due to sampling effort bias and the need for its quantification. Despite that a number of methods are available for that, little is known about their statistical limitations and discrimination capability, which could seriously constrain their use. We assess for the first time the discrimination capacity of two widely used methods and a proposed new one (FIDEGAM), all based on species accumulation curves, under different scenarios of sampling exhaustiveness using Receiver Operating Characteristic (ROC) analyses. Additionally, we examine to what extent the output of each method represents the sampling completeness in a simulated scenario where the true species richness is known. Finally, we apply FIDEGAM to a real situation and explore the spatial patterns of plant diversity in a National Park. FIDEGAM showed an excellent discrimination capability to distinguish between well and poorly sampled areas regardless of sampling exhaustiveness, whereas the other methods failed. Accordingly, FIDEGAM values were strongly correlated with the true percentage of species detected in a simulated scenario, whereas sampling completeness estimated with other methods showed no relationship due to null discrimination capability. Quantifying sampling effort is necessary to account for the uncertainty in biodiversity analyses, however, not all proposed methods are equally reliable. Our comparative analysis demonstrated that FIDEGAM was the most accurate discriminator method in all scenarios of sampling exhaustiveness, and therefore, it can be efficiently applied to most databases in order to enhance the reliability of biodiversity analyses. PMID:23326357

A novel method to handle the effect of uneven sampling effort in biodiversity databases.

PubMed

Pardo, Iker; Pata, María P; Gómez, Daniel; García, María B

2013-01-01

How reliable are results on spatial distribution of biodiversity based on databases? Many studies have evidenced the uncertainty related to this kind of analysis due to sampling effort bias and the need for its quantification. Despite that a number of methods are available for that, little is known about their statistical limitations and discrimination capability, which could seriously constrain their use. We assess for the first time the discrimination capacity of two widely used methods and a proposed new one (FIDEGAM), all based on species accumulation curves, under different scenarios of sampling exhaustiveness using Receiver Operating Characteristic (ROC) analyses. Additionally, we examine to what extent the output of each method represents the sampling completeness in a simulated scenario where the true species richness is known. Finally, we apply FIDEGAM to a real situation and explore the spatial patterns of plant diversity in a National Park. FIDEGAM showed an excellent discrimination capability to distinguish between well and poorly sampled areas regardless of sampling exhaustiveness, whereas the other methods failed. Accordingly, FIDEGAM values were strongly correlated with the true percentage of species detected in a simulated scenario, whereas sampling completeness estimated with other methods showed no relationship due to null discrimination capability. Quantifying sampling effort is necessary to account for the uncertainty in biodiversity analyses, however, not all proposed methods are equally reliable. Our comparative analysis demonstrated that FIDEGAM was the most accurate discriminator method in all scenarios of sampling exhaustiveness, and therefore, it can be efficiently applied to most databases in order to enhance the reliability of biodiversity analyses.

Viability qPCR, a new tool for Legionella risk management.

PubMed

Lizana, X; López, A; Benito, S; Agustí, G; Ríos, M; Piqué, N; Marqués, A M; Codony, F

2017-11-01

Viability quantitative Polymerase Chain Reaction (v-qPCR) is a recent analytical approach for only detecting live microorganisms by DNA amplification-based methods This approach is based on the use of a reagent that irreversibly fixes dead cells DNA. In this study, we evaluate the utility of v-qPCR versus culture method for Legionellosis risk management. The present study was performed using 116 real samples. Water samples were simultaneously analysed by culture, v-qPCR and qPCR methods. Results were compared by means of a non-parametric test. In 11.6% of samples using both methods (culture method and v-qPCR) results were positive, in 50.0% of samples both methods gave rise to negative results. As expected, equivalence between methods was not observed in all cases, as in 32.1% of samples positive results were obtained by v-qPCR and all of them gave rise to negative results by culture. Only in 6.3% of samples, with very low Legionella levels, was culture positive and v-qPCR negative. In 3.5% of samples, overgrowth of other bacteria did not allow performing the culture. When comparing both methods, significant differences between culture and v-qPCR were in the samples belonging to the cooling towers-evaporative condensers group. The v-qPCR method detected greater presence and obtained higher concentrations of Legionella spp. (p<0.001). Otherwise, no significant differences between methods were found in the rest of the groups. The v-qPCR method can be used as a quick tool to evaluate Legionellosis risk, especially in cooling towers-evaporative condensers, where this technique can detect higher levels than culture. The combined interpretation of PCR results along with the ratio of live cells is proposed as a tool for understanding the sample context and estimating the Legionellosis risk potential according to 4 levels of hierarchy. Copyright © 2017 Elsevier GmbH. All rights reserved.

A Typology of Mixed Methods Sampling Designs in Social Science Research

ERIC Educational Resources Information Center

Onwuegbuzie, Anthony J.; Collins, Kathleen M. T.

2007-01-01

This paper provides a framework for developing sampling designs in mixed methods research. First, we present sampling schemes that have been associated with quantitative and qualitative research. Second, we discuss sample size considerations and provide sample size recommendations for each of the major research designs for quantitative and…

Sampling bee communities using pan traps: alternative methods increase sample size

USDA-ARS?s Scientific Manuscript database

Monitoring of the status of bee populations and inventories of bee faunas require systematic sampling. Efficiency and ease of implementation has encouraged the use of pan traps to sample bees. Efforts to find an optimal standardized sampling method for pan traps have focused on pan trap color. Th...

Universal nucleic acids sample preparation method for cells, spores and their mixture

DOEpatents

Bavykin, Sergei [Darien, IL

2011-01-18

The present invention relates to a method for extracting nucleic acids from biological samples. More specifically the invention relates to a universal method for extracting nucleic acids from unidentified biological samples. An advantage of the presently invented method is its ability to effectively and efficiently extract nucleic acids from a variety of different cell types including but not limited to prokaryotic or eukaryotic cells and/or recalcitrant organisms (i.e. spores). Unlike prior art methods which are focused on extracting nucleic acids from vegetative cell or spores, the present invention effectively extracts nucleic acids from spores, multiple cell types or mixtures thereof using a single method. Important that the invented method has demonstrated an ability to extract nucleic acids from spores and vegetative bacterial cells with similar levels effectiveness. The invented method employs a multi-step protocol which erodes the cell structure of the biological sample, isolates, labels, fragments nucleic acids and purifies labeled samples from the excess of dye.

Interval sampling methods and measurement error: a computer simulation.

PubMed

Wirth, Oliver; Slaven, James; Taylor, Matthew A

2014-01-01

A simulation study was conducted to provide a more thorough account of measurement error associated with interval sampling methods. A computer program simulated the application of momentary time sampling, partial-interval recording, and whole-interval recording methods on target events randomly distributed across an observation period. The simulation yielded measures of error for multiple combinations of observation period, interval duration, event duration, and cumulative event duration. The simulations were conducted up to 100 times to yield measures of error variability. Although the present simulation confirmed some previously reported characteristics of interval sampling methods, it also revealed many new findings that pertain to each method's inherent strengths and weaknesses. The analysis and resulting error tables can help guide the selection of the most appropriate sampling method for observation-based behavioral assessments. © Society for the Experimental Analysis of Behavior.

Preparation of bone samples in the Gliwice Radiocarbon Laboratory for AMS radiocarbon dating.

PubMed

Piotrowska, N; Goslar, T

2002-12-01

In the Gliwice Radiocarbon Laboratory, a system for preparation of samples for AMS dating has been built. At first it was used to produce graphite targets from plant macrofossils and sediments. In this study we extended its capabilities with the preparation of bones. We dealt with 3 methods; the first was the classical Longin method of collagen extraction, the second one included additional treatment of powdered bone in alkali solution, while in the third one carboxyl carbon was separated from amino acids obtained after hydrolysis of protein. The suitability of the methods was tested on 2 bone samples. Most of our samples gave ages > 40 kyr BP, suggesting good performance of the adapted methods, except for one sample prepared with simple Longin method. For routine preparation of bones we chose the Longin method with additional alkali treatment.

A Rapid Identification Method for Calamine Using Near-Infrared Spectroscopy Based on Multi-Reference Correlation Coefficient Method and Back Propagation Artificial Neural Network.

PubMed

Sun, Yangbo; Chen, Long; Huang, Bisheng; Chen, Keli

2017-07-01

As a mineral, the traditional Chinese medicine calamine has a similar shape to many other minerals. Investigations of commercially available calamine samples have shown that there are many fake and inferior calamine goods sold on the market. The conventional identification method for calamine is complicated, therefore as a result of the large scale of calamine samples, a rapid identification method is needed. To establish a qualitative model using near-infrared (NIR) spectroscopy for rapid identification of various calamine samples, large quantities of calamine samples including crude products, counterfeits and processed products were collected and correctly identified using the physicochemical and powder X-ray diffraction method. The NIR spectroscopy method was used to analyze these samples by combining the multi-reference correlation coefficient (MRCC) method and the error back propagation artificial neural network algorithm (BP-ANN), so as to realize the qualitative identification of calamine samples. The accuracy rate of the model based on NIR and MRCC methods was 85%; in addition, the model, which took comprehensive multiple factors into consideration, can be used to identify crude calamine products, its counterfeits and processed products. Furthermore, by in-putting the correlation coefficients of multiple references as the spectral feature data of samples into BP-ANN, a BP-ANN model of qualitative identification was established, of which the accuracy rate was increased to 95%. The MRCC method can be used as a NIR-based method in the process of BP-ANN modeling.

Application of a Permethrin Immunosorbent Assay Method to Residential Soil and Dust Samples

EPA Science Inventory

A low-cost, high throughput bioanalytical screening method was developed for monitoring cis/trans-permethrin in dust and soil samples. The method consisted of a simple sample preparation procedure [sonication with dichloromethane followed by a solvent exchange into methanol:wate...

Rapid fusion method for the determination of Pu, Np, and Am in large soil samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

2015-02-14

A new rapid sodium hydroxide fusion method for the preparation of 10-20 g soil samples has been developed by the Savannah River National Laboratory (SRNL). The method enables lower detection limits for plutonium, neptunium, and americium in environmental soil samples. The method also significantly reduces sample processing time and acid fume generation compared to traditional soil digestion techniques using hydrofluoric acid. Ten gram soil aliquots can be ashed and fused using the new method in 1-2 hours, completely dissolving samples, including refractory particles. Pu, Np and Am are separated using stacked 2mL cartridges of TEVA and DGA Resin and measuredmore » using alpha spectrometry. The method can be adapted for measurement by inductively-coupled plasma mass spectrometry (ICP-MS). Two 10 g soil aliquots of fused soil may be combined prior to chromatographic separations to further improve detection limits. Total sample preparation time, including chromatographic separations and alpha spectrometry source preparation, is less than 8 hours.« less

Local Feature Selection for Data Classification.

PubMed

Armanfard, Narges; Reilly, James P; Komeili, Majid

2016-06-01

Typical feature selection methods choose an optimal global feature subset that is applied over all regions of the sample space. In contrast, in this paper we propose a novel localized feature selection (LFS) approach whereby each region of the sample space is associated with its own distinct optimized feature set, which may vary both in membership and size across the sample space. This allows the feature set to optimally adapt to local variations in the sample space. An associated method for measuring the similarities of a query datum to each of the respective classes is also proposed. The proposed method makes no assumptions about the underlying structure of the samples; hence the method is insensitive to the distribution of the data over the sample space. The method is efficiently formulated as a linear programming optimization problem. Furthermore, we demonstrate the method is robust against the over-fitting problem. Experimental results on eleven synthetic and real-world data sets demonstrate the viability of the formulation and the effectiveness of the proposed algorithm. In addition we show several examples where localized feature selection produces better results than a global feature selection method.

Resampling methods in Microsoft Excel® for estimating reference intervals

PubMed Central

Theodorsson, Elvar

2015-01-01

Computer- intensive resampling/bootstrap methods are feasible when calculating reference intervals from non-Gaussian or small reference samples. Microsoft Excel® in version 2010 or later includes natural functions, which lend themselves well to this purpose including recommended interpolation procedures for estimating 2.5 and 97.5 percentiles.
The purpose of this paper is to introduce the reader to resampling estimation techniques in general and in using Microsoft Excel® 2010 for the purpose of estimating reference intervals in particular.
Parametric methods are preferable to resampling methods when the distributions of observations in the reference samples is Gaussian or can transformed to that distribution even when the number of reference samples is less than 120. Resampling methods are appropriate when the distribution of data from the reference samples is non-Gaussian and in case the number of reference individuals and corresponding samples are in the order of 40. At least 500-1000 random samples with replacement should be taken from the results of measurement of the reference samples. PMID:26527366

Resampling methods in Microsoft Excel® for estimating reference intervals.

PubMed

Theodorsson, Elvar

2015-01-01

Computer-intensive resampling/bootstrap methods are feasible when calculating reference intervals from non-Gaussian or small reference samples. Microsoft Excel® in version 2010 or later includes natural functions, which lend themselves well to this purpose including recommended interpolation procedures for estimating 2.5 and 97.5 percentiles. 
The purpose of this paper is to introduce the reader to resampling estimation techniques in general and in using Microsoft Excel® 2010 for the purpose of estimating reference intervals in particular.
 Parametric methods are preferable to resampling methods when the distributions of observations in the reference samples is Gaussian or can transformed to that distribution even when the number of reference samples is less than 120. Resampling methods are appropriate when the distribution of data from the reference samples is non-Gaussian and in case the number of reference individuals and corresponding samples are in the order of 40. At least 500-1000 random samples with replacement should be taken from the results of measurement of the reference samples.

Effects of cooking methods and temperatures on nutritional and quality characteristics of anchovy (Engraulis encrasicholus).

PubMed

Uran, Harun; Gokoglu, Nalan

2014-04-01

The aim of this study was to determine the nutritional and quality characteristics of anchovy after cooking. The fish were cooked by different methods (frying, baking and grilling) at two different temperatures (160 °C, 180 °C). Crude ash, crude protein and crude fat contents of cooked fish increased due to rise in dry matter contents. While cooking methods affected mineral content of anchovy, cooking temperature did not affect. The highest values of monounsaturated fatty acids were found in baked samples. Polyunsaturated fatty acids in baked samples were also high and similar in fried samples. Fried samples, which were the most preferred, lost its nutritional characteristics more than baked and grilled samples. Grilled and baked fish samples can be recommended for healthy consumption. However, grilled fish samples had hard texture due to more moisture loss than other methods. Therefore, it is concluded that baking is the best cooking method for anchovy.

Improved Butanol-Methanol (BUME) Method by Replacing Acetic Acid for Lipid Extraction of Biological Samples.

PubMed

Cruz, Mutya; Wang, Miao; Frisch-Daiello, Jessica; Han, Xianlin

2016-07-01

Extraction of lipids from biological samples is a critical step in lipidomics, especially for shotgun lipidomics where lipid extracts are directly infused into a mass spectrometer. The butanol-methanol (BUME) extraction method was originally developed to extract lipids from plasma samples with 1 % acetic acid. Considering some lipids are sensitive to acidic environments, we modified this protocol by replacing acetic acid with lithium chloride solution and extended the modified extraction to tissue samples. Although no significant reduction of plasmalogen levels in the acidic BUME extracts of rat heart samples was found, the modified method was established to extract various tissue samples, including rat liver, heart, and plasma. Essentially identical profiles of the majority of lipid classes were obtained from the extracts of the modified BUME and traditional Bligh-Dyer methods. However, it was found that neither the original, nor the modified BUME method was suitable for 4-hydroxyalkenal species measurement in biological samples.

Improved Butanol-Methanol (BUME) Method by Replacing Acetic Acid for Lipid Extraction of Biological Samples

PubMed Central

Cruz, Mutya; Wang, Miao; Frisch-Daiello, Jessica; Han, Xianlin

2016-01-01

Extraction of lipids from biological samples is a critical step in lipidomics, especially for shotgun lipidomics where lipid extracts are directly infused into a mass spectrometer. The butanol-methanol (BUME) extraction method was originally developed to extract lipids from plasma samples with 1% acetic acid. Considering some lipids are sensitive to acidic environments, we modified this protocol by replacing acetic acid with lithium chloride solution and extended the modified extraction to tissue samples. Although no significant reduction of plasmalogen levels in the acidic BUME extracts of rat heart samples was found, the modified method was established to extract various tissue samples, including rat liver, heart, and plasma. Essentially identical profiles of the majority of lipid classes were obtained from the extracts of the modified BUME and traditional Bligh-Dyer methods. However, it was found that neither the original, nor the modified BUME method was suitable for 4-hydroxyalkenal species measurement in biological samples. PMID:27245345

Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system.

PubMed

Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

2014-03-01

Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system

NASA Astrophysics Data System (ADS)

Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

2014-03-01

Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

Rapid fusion method for the determination of refractory thorium and uranium isotopes in soil samples

DOE PAGES

Maxwell, Sherrod L.; Hutchison, Jay B.; McAlister, Daniel R.

2015-02-14

Recently, approximately 80% of participating laboratories failed to accurately determine uranium isotopes in soil samples in the U.S Department of Energy Mixed Analyte Performance Evaluation Program (MAPEP) Session 30, due to incomplete dissolution of refractory particles in the samples. Failing laboratories employed acid dissolution methods, including hydrofluoric acid, to recover uranium from the soil matrix. The failures illustrate the importance of rugged soil dissolution methods for the accurate measurement of analytes in the sample matrix. A new rapid fusion method has been developed by the Savannah River National Laboratory (SRNL) to prepare 1-2 g soil sample aliquots very quickly, withmore » total dissolution of refractory particles. Soil samples are fused with sodium hydroxide at 600 ºC in zirconium crucibles to enable complete dissolution of the sample. Uranium and thorium are separated on stacked TEVA and TRU extraction chromatographic resin cartridges, prior to isotopic measurements by alpha spectrometry on cerium fluoride microprecipitation sources. Plutonium can also be separated and measured using this method. Batches of 12 samples can be prepared for measurement in <5 hours.« less

A Comparison of Two Sampling Strategies to Assess Discomycete Diversity in Wet Tropical Forests

Treesearch

SHARON A. CANTRELL

2004-01-01

Most of the fungal diversity studies that have used a systematic collecting scheme have not included the discomycetes, so optimal sampling methods are not available for this group. In this study, I tested two sampling methods at each sites in the Caribbean National Forest, Puerto Rico and Ebano Verde Reserve, Dominican Republic. For a plot-based sampling method, 10 ×...

Comparison of a real-time PCR method with a culture method for the detection of Salmonella enterica serotype enteritidis in naturally contaminated environmental samples from integrated poultry houses.

PubMed

Lungu, Bwalya; Waltman, W Douglas; Berghaus, Roy D; Hofacre, Charles L

2012-04-01

Conventional culture methods have traditionally been considered the "gold standard" for the isolation and identification of foodborne bacterial pathogens. However, culture methods are labor-intensive and time-consuming. A Salmonella enterica serotype Enteritidis-specific real-time PCR assay that recently received interim approval by the National Poultry Improvement Plan for the detection of Salmonella Enteritidis was evaluated against a culture method that had also received interim National Poultry Improvement Plan approval for the analysis of environmental samples from integrated poultry houses. The method was validated with 422 field samples collected by either the boot sock or drag swab method. The samples were cultured by selective enrichment in tetrathionate broth followed by transfer onto a modified semisolid Rappaport-Vassiliadis medium and then plating onto brilliant green with novobiocin and xylose lysine brilliant Tergitol 4 plates. One-milliliter aliquots of the selective enrichment broths from each sample were collected for DNA extraction by the commercial PrepSEQ nucleic acid extraction assay and analysis by the Salmonella Enteritidis-specific real-time PCR assay. The real-time PCR assay detected no significant differences between the boot sock and drag swab samples. In contrast, the culture method detected a significantly higher number of positive samples from boot socks. The diagnostic sensitivity of the real-time PCR assay for the field samples was significantly higher than that of the culture method. The kappa value obtained was 0.46, indicating moderate agreement between the real-time PCR assay and the culture method. In addition, the real-time PCR method had a turnaround time of 2 days compared with 4 to 8 days for the culture method. The higher sensitivity as well as the reduction in time and labor makes this real-time PCR assay an excellent alternative to conventional culture methods for diagnostic purposes, surveillance, and research studies to improve food safety.

RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, S.; Jones, V.

2009-05-27

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are splitmore » between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry.« less

Subrandom methods for multidimensional nonuniform sampling.

PubMed

Worley, Bradley

2016-08-01

Methods of nonuniform sampling that utilize pseudorandom number sequences to select points from a weighted Nyquist grid are commonplace in biomolecular NMR studies, due to the beneficial incoherence introduced by pseudorandom sampling. However, these methods require the specification of a non-arbitrary seed number in order to initialize a pseudorandom number generator. Because the performance of pseudorandom sampling schedules can substantially vary based on seed number, this can complicate the task of routine data collection. Approaches such as jittered sampling and stochastic gap sampling are effective at reducing random seed dependence of nonuniform sampling schedules, but still require the specification of a seed number. This work formalizes the use of subrandom number sequences in nonuniform sampling as a means of seed-independent sampling, and compares the performance of three subrandom methods to their pseudorandom counterparts using commonly applied schedule performance metrics. Reconstruction results using experimental datasets are also provided to validate claims made using these performance metrics. Copyright © 2016 Elsevier Inc. All rights reserved.

[Local Regression Algorithm Based on Net Analyte Signal and Its Application in Near Infrared Spectral Analysis].

PubMed

Zhang, Hong-guang; Lu, Jian-gang

2016-02-01

Abstract To overcome the problems of significant difference among samples and nonlinearity between the property and spectra of samples in spectral quantitative analysis, a local regression algorithm is proposed in this paper. In this algorithm, net signal analysis method(NAS) was firstly used to obtain the net analyte signal of the calibration samples and unknown samples, then the Euclidean distance between net analyte signal of the sample and net analyte signal of calibration samples was calculated and utilized as similarity index. According to the defined similarity index, the local calibration sets were individually selected for each unknown sample. Finally, a local PLS regression model was built on each local calibration sets for each unknown sample. The proposed method was applied to a set of near infrared spectra of meat samples. The results demonstrate that the prediction precision and model complexity of the proposed method are superior to global PLS regression method and conventional local regression algorithm based on spectral Euclidean distance.

Equivalency testing of TTC Tergitol 7 agar (ISO 9308-1:2000) with five culture media for the detection of E. coli in water samples in Greece.

PubMed

Mavridou, A; Smeti, E; Mandilara, G; Mandilara, G; Boufa, P; Vagiona-Arvanitidou, M; Vantarakis, A; Vassilandonopoulou, G; Pappa, O; Roussia, V; Tzouanopoulos, A; Livadara, M; Aisopou, I; Maraka, V; Nikolaou, E; Mandilara, G

2010-01-01

In this study ten laboratories in Greece compared the performance of reference method TTC Tergitol 7 Agar (with the additional test of beta-glucuronidase production) with five alternative methods, to detect E. coli in water, in line with European Water Directive recommendations. The samples were prepared by spiking drinking water with sewage effluent following a standard protocol. Chlorinated and non-chlorinated samples were used. The statistical analysis was based on the mean relative difference of confirmed counts and was performed in line with ISO 17994. The results showed that in total, three of the alternative methods (Chromocult Coliform agar, Membrane Lauryl Sulfate agar and Trypton Bilex-glucuronidase medium) were not different from TTC Tergitol 7 agar (TTC Tergitol 7 agar vs Chromocult Coliform agar, 294 samples, mean RD% 5.55; vs MLSA, 302 samples, mean RD% 1; vs TBX, 297 samples, mean RD% -2.78). The other two alternative methods (Membrane Faecal coliform medium and Colilert 18/ Quantitray) gave significantly higher counts than TTC Tergitol 7 agar (TTC Tergitol 7 agar vs MFc, 303 samples, mean RD% 8.81; vs Colilert-18/Quantitray, 76 samples, mean RD% 18.91). In other words, the alternative methods generated performance that was as reliable as, or even better than, the reference method. This study will help laboratories in Greece overcome culture and counting problems deriving from the EU reference method for E. coli counts in water samples.

Evaluation on determination of iodine in coal by energy dispersive X-ray fluorescence

USGS Publications Warehouse

Wang, B.; Jackson, J.C.; Palmer, C.; Zheng, B.; Finkelman, R.B.

2005-01-01

A quick and inexpensive method of relative high iodine determination from coal samples was evaluated. Energy dispersive X-ray fluorescence (EDXRF) provided a detection limit of about 14 ppm (3 times of standard deviations of the blank sample), without any complex sample preparation. An analytical relative standard deviation of 16% was readily attainable for coal samples. Under optimum conditions, coal samples with iodine concentrations higher than 5 ppm can be determined using this EDXRF method. For the time being, due to the general iodine concentrations of coal samples lower than 5 ppm, except for some high iodine content coal, this method can not effectively been used for iodine determination. More work needed to meet the requirement of determination of iodine from coal samples for this method. Copyright ?? 2005 by The Geochemical Society of Japan.

Validation and comparison of two sampling methods to assess dermal exposure to drilling fluids and crude oil.

PubMed

Galea, Karen S; McGonagle, Carolyn; Sleeuwenhoek, Anne; Todd, David; Jiménez, Araceli Sánchez

2014-06-01

Dermal exposure to drilling fluids and crude oil is an exposure route of concern. However, there have been no published studies describing sampling methods or reporting dermal exposure measurements. We describe a study that aimed to evaluate a wipe sampling method to assess dermal exposure to an oil-based drilling fluid and crude oil, as well as to investigate the feasibility of using an interception cotton glove sampler for exposure on the hands/wrists. A direct comparison of the wipe and interception methods was also completed using pigs' trotters as a surrogate for human skin and a direct surface contact exposure scenario. Overall, acceptable recovery and sampling efficiencies were reported for both methods, and both methods had satisfactory storage stability at 1 and 7 days, although there appeared to be some loss over 14 days. The methods' comparison study revealed significantly higher removal of both fluids from the metal surface with the glove samples compared with the wipe samples (on average 2.5 times higher). Both evaluated sampling methods were found to be suitable for assessing dermal exposure to oil-based drilling fluids and crude oil; however, the comparison study clearly illustrates that glove samplers may overestimate the amount of fluid transferred to the skin. Further comparison of the two dermal sampling methods using additional exposure situations such as immersion or deposition, as well as a field evaluation, is warranted to confirm their appropriateness and suitability in the working environment. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Validation and Comparison of Two Sampling Methods to Assess Dermal Exposure to Drilling Fluids and Crude Oil

PubMed Central

Galea, Karen S.; McGonagle, Carolyn; Sleeuwenhoek, Anne; Todd, David; Jiménez, Araceli Sánchez

2014-01-01

Dermal exposure to drilling fluids and crude oil is an exposure route of concern. However, there have been no published studies describing sampling methods or reporting dermal exposure measurements. We describe a study that aimed to evaluate a wipe sampling method to assess dermal exposure to an oil-based drilling fluid and crude oil, as well as to investigate the feasibility of using an interception cotton glove sampler for exposure on the hands/wrists. A direct comparison of the wipe and interception methods was also completed using pigs’ trotters as a surrogate for human skin and a direct surface contact exposure scenario. Overall, acceptable recovery and sampling efficiencies were reported for both methods, and both methods had satisfactory storage stability at 1 and 7 days, although there appeared to be some loss over 14 days. The methods’ comparison study revealed significantly higher removal of both fluids from the metal surface with the glove samples compared with the wipe samples (on average 2.5 times higher). Both evaluated sampling methods were found to be suitable for assessing dermal exposure to oil-based drilling fluids and crude oil; however, the comparison study clearly illustrates that glove samplers may overestimate the amount of fluid transferred to the skin. Further comparison of the two dermal sampling methods using additional exposure situations such as immersion or deposition, as well as a field evaluation, is warranted to confirm their appropriateness and suitability in the working environment. PMID:24598941

Sensitivity and specificity of normality tests and consequences on reference interval accuracy at small sample size: a computer-simulation study.

PubMed

Le Boedec, Kevin

2016-12-01

According to international guidelines, parametric methods must be chosen for RI construction when the sample size is small and the distribution is Gaussian. However, normality tests may not be accurate at small sample size. The purpose of the study was to evaluate normality test performance to properly identify samples extracted from a Gaussian population at small sample sizes, and assess the consequences on RI accuracy of applying parametric methods to samples that falsely identified the parent population as Gaussian. Samples of n = 60 and n = 30 values were randomly selected 100 times from simulated Gaussian, lognormal, and asymmetric populations of 10,000 values. The sensitivity and specificity of 4 normality tests were compared. Reference intervals were calculated using 6 different statistical methods from samples that falsely identified the parent population as Gaussian, and their accuracy was compared. Shapiro-Wilk and D'Agostino-Pearson tests were the best performing normality tests. However, their specificity was poor at sample size n = 30 (specificity for P < .05: .51 and .50, respectively). The best significance levels identified when n = 30 were 0.19 for Shapiro-Wilk test and 0.18 for D'Agostino-Pearson test. Using parametric methods on samples extracted from a lognormal population but falsely identified as Gaussian led to clinically relevant inaccuracies. At small sample size, normality tests may lead to erroneous use of parametric methods to build RI. Using nonparametric methods (or alternatively Box-Cox transformation) on all samples regardless of their distribution or adjusting, the significance level of normality tests depending on sample size would limit the risk of constructing inaccurate RI. © 2016 American Society for Veterinary Clinical Pathology.

A comparative proteomics method for multiple samples based on a 18O-reference strategy and a quantitation and identification-decoupled strategy.

PubMed

Wang, Hongbin; Zhang, Yongqian; Gui, Shuqi; Zhang, Yong; Lu, Fuping; Deng, Yulin

2017-08-15

Comparisons across large numbers of samples are frequently necessary in quantitative proteomics. Many quantitative methods used in proteomics are based on stable isotope labeling, but most of these are only useful for comparing two samples. For up to eight samples, the iTRAQ labeling technique can be used. For greater numbers of samples, the label-free method has been used, but this method was criticized for low reproducibility and accuracy. An ingenious strategy has been introduced, comparing each sample against a 18 O-labeled reference sample that was created by pooling equal amounts of all samples. However, it is necessary to use proportion-known protein mixtures to investigate and evaluate this new strategy. Another problem for comparative proteomics of multiple samples is the poor coincidence and reproducibility in protein identification results across samples. In present study, a method combining 18 O-reference strategy and a quantitation and identification-decoupled strategy was investigated with proportion-known protein mixtures. The results obviously demonstrated that the 18 O-reference strategy had greater accuracy and reliability than other previously used comparison methods based on transferring comparison or label-free strategies. By the decoupling strategy, the quantification data acquired by LC-MS and the identification data acquired by LC-MS/MS are matched and correlated to identify differential expressed proteins, according to retention time and accurate mass. This strategy made protein identification possible for all samples using a single pooled sample, and therefore gave a good reproducibility in protein identification across multiple samples, and allowed for optimizing peptide identification separately so as to identify more proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

Shear Strength of Remoulding Clay Samples Using Different Methods of Moulding

NASA Astrophysics Data System (ADS)

Norhaliza, W.; Ismail, B.; Azhar, A. T. S.; Nurul, N. J.

2016-07-01

Shear strength for clay soil was required to determine the soil stability. Clay was known as a soil with complex natural formations and very difficult to obtain undisturbed samples at the site. The aim of this paper was to determine the unconfined shear strength of remoulded clay on different methods in moulding samples which were proctor compaction, hand operated soil compacter and miniature mould methods. All the samples were remoulded with the same optimum moisture content (OMC) and density that were 18% and 1880 kg/m3 respectively. The unconfined shear strength results of remoulding clay soils for proctor compaction method was 289.56kPa with the strain 4.8%, hand operated method was 261.66kPa with the strain 4.4% and miniature mould method was 247.52kPa with the strain 3.9%. Based on the proctor compaction method, the reduction percentage of unconfined shear strength of remoulded clay soil of hand operated method was 9.66%, and for miniature mould method was 14.52%. Thus, because there was no significant difference of reduction percentage of unconfined shear strength between three different methods, so it can be concluded that remoulding clay by hand operated method and miniature mould method were accepted and suggested to perform remoulding clay samples by other future researcher. However for comparison, the hand operated method was more suitable to form remoulded clay sample in term of easiness, saving time and less energy for unconfined shear strength determination purposes.

Purification of crude glycerol from transesterification reaction of palm oil using direct method and multistep method

NASA Astrophysics Data System (ADS)

Nasir, N. F.; Mirus, M. F.; Ismail, M.

2017-09-01

Crude glycerol which produced from transesterification reaction has limited usage if it does not undergo purification process. It also contains excess methanol, catalyst and soap. Conventionally, purification method of the crude glycerol involves high cost and complex processes. This study aimed to determine the effects of using different purification methods which are direct method (comprises of ion exchange and methanol removal steps) and multistep method (comprises of neutralization, filtration, ion exchange and methanol removal steps). Two crude glycerol samples were investigated; the self-produced sample through the transesterification process of palm oil and the sample obtained from biodiesel plant. Samples were analysed using Fourier Transform Infrared Spectroscopy, Gas Chromatography and High Performance Liquid Chromatography. The results of this study for both samples after purification have showed that the pure glycerol was successfully produced and fatty acid salts were eliminated. Also, the results indicated the absence of methanol in both samples after purification process. In short, the combination of 4 purification steps has contributed to a higher quality of glycerol. Multistep purification method gave a better result compared to the direct method as neutralization and filtration steps helped in removing most excess salt, fatty acid and catalyst.

Novel methodology to isolate microplastics from vegetal-rich samples.

PubMed

Herrera, Alicia; Garrido-Amador, Paloma; Martínez, Ico; Samper, María Dolores; López-Martínez, Juan; Gómez, May; Packard, Theodore T

2018-04-01

Microplastics are small plastic particles, globally distributed throughout the oceans. To properly study them, all the methodologies for their sampling, extraction, and measurement should be standardized. For heterogeneous samples containing sediments, animal tissues and zooplankton, several procedures have been described. However, definitive methodologies for samples, rich in algae and plant material, have not yet been developed. The aim of this study was to find the best extraction protocol for vegetal-rich samples by comparing the efficacies of five previously described digestion methods, and a novel density separation method. A protocol using 96% ethanol for density separation was better than the five digestion methods tested, even better than using H 2 O 2 digestion. As it was the most efficient, simple, safe and inexpensive method for isolating microplastics from vegetal rich samples, we recommend it as a standard separation method. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method and system for laser-based formation of micro-shapes in surfaces of optical elements

DOEpatents

Bass, Isaac Louis; Guss, Gabriel Mark

2013-03-05

A method of forming a surface feature extending into a sample includes providing a laser operable to emit an output beam and modulating the output beam to form a pulse train having a plurality of pulses. The method also includes a) directing the pulse train along an optical path intersecting an exposed portion of the sample at a position i and b) focusing a first portion of the plurality of pulses to impinge on the sample at the position i. Each of the plurality of pulses is characterized by a spot size at the sample. The method further includes c) ablating at least a portion of the sample at the position i to form a portion of the surface feature and d) incrementing counter i. The method includes e) repeating steps a) through d) to form the surface feature. The sample is free of a rim surrounding the surface feature.

Validation of the 3M molecular detection system for the detection of listeria in meat, seafood, dairy, and retail environments.

PubMed

Fortes, Esther D; David, John; Koeritzer, Bob; Wiedmann, Martin

2013-05-01

There is a continued need to develop improved rapid methods for detection of foodborne pathogens. The aim of this project was to evaluate the 3M Molecular Detection System (3M MDS), which uses isothermal DNA amplification, and the 3M Molecular Detection Assay Listeria using environmental samples obtained from retail delicatessens and meat, seafood, and dairy processing plants. Environmental sponge samples were tested for Listeria with the 3M MDS after 22 and 48 h of enrichment in 3M Modified Listeria Recovery Broth (3M mLRB); enrichments were also used for cultural detection of Listeria spp. Among 391 samples tested for Listeria, 74 were positive by both the 3M MDS and the cultural method, 310 were negative by both methods, 2 were positive by the 3M MDS and negative by the cultural method, and one sample was negative by the 3M MDS and positive by the cultural method. Four samples were removed from the sample set, prior to statistical analyses, due to potential cross-contamination during testing. Listeria isolates from positive samples represented L. monocytogenes, L. innocua, L. welshimeri, and L. seeligeri. Overall, the 3M MDS and culture-based detection after enrichment in 3M mLRB did not differ significantly (P < 0.05) with regard to the number of positive samples, when chi-square analyses were performed for (i) number of positive samples after 22 h, (ii) number of positive samples after 48 h, and (iii) number of positive samples after 22 and/or 48 h of enrichment in 3M mLRB. Among 288 sampling sites that were tested with duplicate sponges, 67 each tested positive with the 3M MDS and the traditional U.S. Food and Drug Administration Bacteriological Analytical Manual method, further supporting that the 3M MDS performs equivalently to traditional methods when used with environmental sponge samples.

Evaluating Composite Sampling Methods of Bacillus spores at Low Concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hess, Becky M.; Amidan, Brett G.; Anderson, Kevin K.

Restoring facility operations after the 2001 Amerithrax attacks took over three months to complete, highlighting the need to reduce remediation time. The most time intensive tasks were environmental sampling and sample analyses. Composite sampling allows disparate samples to be combined, with only a single analysis needed, making it a promising method to reduce response times. We developed a statistical experimental design to test three different composite sampling methods: 1) single medium single pass composite: a single cellulose sponge samples multiple coupons; 2) single medium multi-pass composite: a single cellulose sponge is used to sample multiple coupons; and 3) multi-medium post-samplemore » composite: a single cellulose sponge samples a single surface, and then multiple sponges are combined during sample extraction. Five spore concentrations of Bacillus atrophaeus Nakamura spores were tested; concentrations ranged from 5 to 100 CFU/coupon (0.00775 to 0.155CFU/cm2, respectively). Study variables included four clean surface materials (stainless steel, vinyl tile, ceramic tile, and painted wallboard) and three grime coated/dirty materials (stainless steel, vinyl tile, and ceramic tile). Analysis of variance for the clean study showed two significant factors: composite method (p-value < 0.0001) and coupon material (p-value = 0.0008). Recovery efficiency (RE) was higher overall using the post-sample composite (PSC) method compared to single medium composite from both clean and grime coated materials. RE with the PSC method for concentrations tested (10 to 100 CFU/coupon) was similar for ceramic tile, painted wall board, and stainless steel for clean materials. RE was lowest for vinyl tile with both composite methods. Statistical tests for the dirty study showed RE was significantly higher for vinyl and stainless steel materials, but significantly lower for ceramic tile. These results suggest post-sample compositing can be used to reduce sample analysis time when responding to a Bacillus anthracis contamination event of clean or dirty surfaces.« less

Assessment of Different Sampling Methods for Measuring and Representing Macular Cone Density Using Flood-Illuminated Adaptive Optics.

PubMed

Feng, Shu; Gale, Michael J; Fay, Jonathan D; Faridi, Ambar; Titus, Hope E; Garg, Anupam K; Michaels, Keith V; Erker, Laura R; Peters, Dawn; Smith, Travis B; Pennesi, Mark E

2015-09-01

To describe a standardized flood-illuminated adaptive optics (AO) imaging protocol suitable for the clinical setting and to assess sampling methods for measuring cone density. Cone density was calculated following three measurement protocols: 50 × 50-μm sampling window values every 0.5° along the horizontal and vertical meridians (fixed-interval method), the mean density of expanding 0.5°-wide arcuate areas in the nasal, temporal, superior, and inferior quadrants (arcuate mean method), and the peak cone density of a 50 × 50-μm sampling window within expanding arcuate areas near the meridian (peak density method). Repeated imaging was performed in nine subjects to determine intersession repeatability of cone density. Cone density montages could be created for 67 of the 74 subjects. Image quality was determined to be adequate for automated cone counting for 35 (52%) of the 67 subjects. We found that cone density varied with different sampling methods and regions tested. In the nasal and temporal quadrants, peak density most closely resembled histological data, whereas the arcuate mean and fixed-interval methods tended to underestimate the density compared with histological data. However, in the inferior and superior quadrants, arcuate mean and fixed-interval methods most closely matched histological data, whereas the peak density method overestimated cone density compared with histological data. Intersession repeatability testing showed that repeatability was greatest when sampling by arcuate mean and lowest when sampling by fixed interval. We show that different methods of sampling can significantly affect cone density measurements. Therefore, care must be taken when interpreting cone density results, even in a normal population.

Comparative Evaluation of Three Homogenization Methods for Isolating Middle East Respiratory Syndrome Coronavirus Nucleic Acids From Sputum Samples for Real-Time Reverse Transcription PCR

PubMed Central

Yong, Dongeun; Ki, Chang-Seok; Kim, Jae-Seok; Seong, Moon-Woo; Lee, Hyukmin

2016-01-01

Background Real-time reverse transcription PCR (rRT-PCR) of sputum samples is commonly used to diagnose Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Owing to the difficulty of extracting RNA from sputum containing mucus, sputum homogenization is desirable prior to nucleic acid isolation. We determined optimal homogenization methods for isolating viral nucleic acids from sputum. Methods We evaluated the following three sputum-homogenization methods: proteinase K and DNase I (PK-DNase) treatment, phosphate-buffered saline (PBS) treatment, and N-acetyl-L-cysteine and sodium citrate (NALC) treatment. Sputum samples were spiked with inactivated MERS-CoV culture isolates. RNA was extracted from pretreated, spiked samples using the easyMAG system (bioMérieux, France). Extracted RNAs were then subjected to rRT-PCR for MERS-CoV diagnosis (DiaPlex Q MERS-coronavirus, SolGent, Korea). Results While analyzing 15 spiked sputum samples prepared in technical duplicate, false-negative results were obtained with five (16.7%) and four samples (13.3%), respectively, by using the PBS and NALC methods. The range of threshold cycle (Ct) values observed when detecting upE in sputum samples was 31.1–35.4 with the PK-DNase method, 34.7–39.0 with the PBS method, and 33.9–38.6 with the NALC method. Compared with the control, which were prepared by adding a one-tenth volume of 1:1,000 diluted viral culture to PBS solution, the ranges of Ct values obtained by the PBS and NALC methods differed significantly from the mean control Ct of 33.2 (both P<0.0001). Conclusions The PK-DNase method is suitable for homogenizing sputum samples prior to RNA extraction. PMID:27374711

GROUND WATER PURGING AND SAMPLING METHODS: HISTORY VS. HYSTERIA

EPA Science Inventory

It has been over 10 years since the low-flow ground water purging and sampling method was initially reported in the literature. The method grew from the recognition that well purging was necessary to collect representative samples, bailers could not achieve well purging, and high...

THE INFLUENCE OF PHYSICAL FACTORS ON COMPARATIVE PERFORMANCE OF SAMPLING METHODS IN LARGE RIVERS

EPA Science Inventory

In 1999, we compared five existing benthic macroinvertebrate sampling methods used in boatable rivers. Each sampling protocol was performed at each of 60 sites distributed among four rivers in the Ohio River drainage basin. Initial comparison of methods using key macroinvertebr...

Low acetaldehyde collection efficiencies for 24-hour sampling with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents.

PubMed

Herrington, Jason S; Fan, Zhi-Hua Tina; Lioy, Paul J; Zhang, Junfeng Jim

2007-01-15

Airborne aldehyde and ketone (carbonyl) sampling methodologies based on derivatization with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents could unequivocally be considered the "gold" standard. Originally developed in the late 1970s, these methods have been extensively evaluated and developed up to the present day. However, these methods have been inadequately evaluated for the long-term (i.e., 24 h or greater) sampling collection efficiency (CE) of carbonyls other than formaldehyde. The current body of literature fails to demonstrate that DNPH-coated solid sorbent sampling methods have acceptable CEs for the long-term sampling of carbonyls other than formaldehyde. Despite this, such methods are widely used to report the concentrations of multiple carbonyls from long-term sampling, assuming approximately 100% CEs. Laboratory experiments were conducted in this study to evaluate the long-term formaldehyde and acetaldehyde sampling CEs for several commonly used DNPH-coated solid sorbents. Results from sampling known concentrations of formaldehyde and acetaldehyde generated in a dynamic atmosphere generation system demonstrate that the 24-hour formaldehyde sampling CEs ranged from 83 to 133%, confirming the findings made in previous studies. However, the 24-hour acetaldehyde sampling CEs ranged from 1 to 62%. Attempts to increase the acetaldehyde CEs by adding acid to the samples post sampling were unsuccessful. These results indicate that assuming approximately 100% CEs for 24-hour acetaldehyde sampling, as commonly done with DNPH-coated solid sorbent methods, would substantially under estimate acetaldehyde concentrations.

[Respondent-Driven Sampling: a new sampling method to study visible and hidden populations].

PubMed

Mantecón, Alejandro; Juan, Montse; Calafat, Amador; Becoña, Elisardo; Román, Encarna

2008-01-01

The paper introduces a variant of chain-referral sampling: respondent-driven sampling (RDS). This sampling method shows that methods based on network analysis can be combined with the statistical validity of standard probability sampling methods. In this sense, RDS appears to be a mathematical improvement of snowball sampling oriented to the study of hidden populations. However, we try to prove its validity with populations that are not within a sampling frame but can nonetheless be contacted without difficulty. The basics of RDS are explained through our research on young people (aged 14 to 25) who go clubbing, consume alcohol and other drugs, and have sex. Fieldwork was carried out between May and July 2007 in three Spanish regions: Baleares, Galicia and Comunidad Valenciana. The presentation of the study shows the utility of this type of sampling when the population is accessible but there is a difficulty deriving from the lack of a sampling frame. However, the sample obtained is not a random representative one in statistical terms of the target population. It must be acknowledged that the final sample is representative of a 'pseudo-population' that approximates to the target population but is not identical to it.

Systems and methods for separating particles and/or substances from a sample fluid

DOEpatents

Mariella, Jr., Raymond P.; Dougherty, George M.; Dzenitis, John M.; Miles, Robin R.; Clague, David S.

2016-11-01

Systems and methods for separating particles and/or toxins from a sample fluid. A method according to one embodiment comprises simultaneously passing a sample fluid and a buffer fluid through a chamber such that a fluidic interface is formed between the sample fluid and the buffer fluid as the fluids pass through the chamber, the sample fluid having particles of interest therein; applying a force to the fluids for urging the particles of interest to pass through the interface into the buffer fluid; and substantially separating the buffer fluid from the sample fluid.

Detecting the sampling rate through observations

NASA Astrophysics Data System (ADS)

Shoji, Isao

2018-09-01

This paper proposes a method to detect the sampling rate of discrete time series of diffusion processes. Using the maximum likelihood estimates of the parameters of a diffusion process, we establish a criterion based on the Kullback-Leibler divergence and thereby estimate the sampling rate. Simulation studies are conducted to check whether the method can detect the sampling rates from data and their results show a good performance in the detection. In addition, the method is applied to a financial time series sampled on daily basis and shows the detected sampling rate is different from the conventional rates.

Probe Heating Method for the Analysis of Solid Samples Using a Portable Mass Spectrometer

PubMed Central

Kumano, Shun; Sugiyama, Masuyuki; Yamada, Masuyoshi; Nishimura, Kazushige; Hasegawa, Hideki; Morokuma, Hidetoshi; Inoue, Hiroyuki; Hashimoto, Yuichiro

2015-01-01

We previously reported on the development of a portable mass spectrometer for the onsite screening of illicit drugs, but our previous sampling system could only be used for liquid samples. In this study, we report on an attempt to develop a probe heating method that also permits solid samples to be analyzed using a portable mass spectrometer. An aluminum rod is used as the sampling probe. The powdered sample is affixed to the sampling probe or a droplet of sample solution is placed on the tip of the probe and dried. The probe is then placed on a heater to vaporize the sample. The vapor is then introduced into the portable mass spectrometer and analyzed. With the heater temperature set to 130°C, the developed system detected 1 ng of methamphetamine, 1 ng of amphetamine, 3 ng of 3,4-methylenedioxymethamphetamine, 1 ng of 3,4-methylenedioxyamphetamine, and 0.3 ng of cocaine. Even from mixtures consisting of clove powder and methamphetamine powder, methamphetamine ions were detected by tandem mass spectrometry. The developed probe heating method provides a simple method for the analysis of solid samples. A portable mass spectrometer incorporating this method would thus be useful for the onsite screening of illicit drugs. PMID:26819909

Frequency-Modulated Continuous Flow Analysis Electrospray Ionization Mass Spectrometry (FM-CFA-ESI-MS) for Sample Multiplexing.

PubMed

Filla, Robert T; Schrell, Adrian M; Coulton, John B; Edwards, James L; Roper, Michael G

2018-02-20

A method for multiplexed sample analysis by mass spectrometry without the need for chemical tagging is presented. In this new method, each sample is pulsed at unique frequencies, mixed, and delivered to the mass spectrometer while maintaining a constant total flow rate. Reconstructed ion currents are then a time-dependent signal consisting of the sum of the ion currents from the various samples. Spectral deconvolution of each reconstructed ion current reveals the identity of each sample, encoded by its unique frequency, and its concentration encoded by the peak height in the frequency domain. This technique is different from other approaches that have been described, which have used modulation techniques to increase the signal-to-noise ratio of a single sample. As proof of concept of this new method, two samples containing up to 9 analytes were multiplexed. The linear dynamic range of the calibration curve was increased with extended acquisition times of the experiment and longer oscillation periods of the samples. Because of the combination of the samples, salt had little effect on the ability of this method to achieve relative quantitation. Continued development of this method is expected to allow for increased numbers of samples that can be multiplexed.

Evaluation of DNA extraction methods for the analysis of microbial community in biological activated carbon.

PubMed

Zheng, Lu; Gao, Naiyun; Deng, Yang

2012-01-01

It is difficult to isolate DNA from biological activated carbon (BAC) samples used in water treatment plants, owing to the scarcity of microorganisms in BAC samples. The aim of this study was to identify DNA extraction methods suitable for a long-term, comprehensive ecological analysis of BAC microbial communities. To identify a procedure that can produce high molecular weight DNA, maximizes detectable diversity and is relatively free from contaminants, the microwave extraction method, the cetyltrimethylammonium bromide (CTAB) extraction method, a commercial DNA extraction kit, and the ultrasonic extraction method were used for the extraction of DNA from BAC samples. Spectrophotometry, agarose gel electrophoresis and polymerase chain reaction (PCR)-restriction fragment length polymorphisms (RFLP) analysis were conducted to compare the yield and quality of DNA obtained using these methods. The results showed that the CTAB method produce the highest yield and genetic diversity of DNA from BAC samples, but DNA purity was slightly less than that obtained with the DNA extraction-kit method. This study provides a theoretical basis for establishing and selecting DNA extraction methods for BAC samples.

Performance and separation occurrence of binary probit regression estimator using maximum likelihood method and Firths approach under different sample size

NASA Astrophysics Data System (ADS)

Lusiana, Evellin Dewi

2017-12-01

The parameters of binary probit regression model are commonly estimated by using Maximum Likelihood Estimation (MLE) method. However, MLE method has limitation if the binary data contains separation. Separation is the condition where there are one or several independent variables that exactly grouped the categories in binary response. It will result the estimators of MLE method become non-convergent, so that they cannot be used in modeling. One of the effort to resolve the separation is using Firths approach instead. This research has two aims. First, to identify the chance of separation occurrence in binary probit regression model between MLE method and Firths approach. Second, to compare the performance of binary probit regression model estimator that obtained by MLE method and Firths approach using RMSE criteria. Those are performed using simulation method and under different sample size. The results showed that the chance of separation occurrence in MLE method for small sample size is higher than Firths approach. On the other hand, for larger sample size, the probability decreased and relatively identic between MLE method and Firths approach. Meanwhile, Firths estimators have smaller RMSE than MLEs especially for smaller sample sizes. But for larger sample sizes, the RMSEs are not much different. It means that Firths estimators outperformed MLE estimator.

Valid statistical inference methods for a case-control study with missing data.

PubMed

Tian, Guo-Liang; Zhang, Chi; Jiang, Xuejun

2018-04-01

The main objective of this paper is to derive the valid sampling distribution of the observed counts in a case-control study with missing data under the assumption of missing at random by employing the conditional sampling method and the mechanism augmentation method. The proposed sampling distribution, called the case-control sampling distribution, can be used to calculate the standard errors of the maximum likelihood estimates of parameters via the Fisher information matrix and to generate independent samples for constructing small-sample bootstrap confidence intervals. Theoretical comparisons of the new case-control sampling distribution with two existing sampling distributions exhibit a large difference. Simulations are conducted to investigate the influence of the three different sampling distributions on statistical inferences. One finding is that the conclusion by the Wald test for testing independency under the two existing sampling distributions could be completely different (even contradictory) from the Wald test for testing the equality of the success probabilities in control/case groups under the proposed distribution. A real cervical cancer data set is used to illustrate the proposed statistical methods.

A novel strategy to obtain quantitative data for modelling: combined enrichment and real-time PCR for enumeration of salmonellae from pig carcasses.

PubMed

Krämer, Nadine; Löfström, Charlotta; Vigre, Håkan; Hoorfar, Jeffrey; Bunge, Cornelia; Malorny, Burkhard

2011-03-01

Salmonella is a major zoonotic pathogen which causes outbreaks and sporadic cases of gastroenteritis in humans worldwide. The primary sources for Salmonella are food-producing animals such as pigs and poultry. For risk assessment and hazard analysis and critical control point (HACCP) concepts, it is essential to produce large amounts of quantitative data, which is currently not achievable with the standard cultural based methods for enumeration of Salmonella. This study presents the development of a novel strategy to enumerate low numbers of Salmonella in cork borer samples taken from pig carcasses as a first concept and proof of principle for a new sensitive and rapid quantification method based on combined enrichment and real-time PCR. The novelty of the approach is in the short pre-enrichment step, where for most bacteria, growth is in the log phase. The method consists of an 8h pre-enrichment of the cork borer sample diluted 1:10 in non-selective buffered peptone water, followed by DNA extraction, and Salmonella detection and quantification by real-time PCR. The limit of quantification was 1.4 colony forming units (CFU)/20 cm(2) (approximately 10 g) of artificially contaminated sample with 95% confidence interval of ± 0.7 log CFU/sample. The precision was similar to the standard reference most probable number (MPN) method. A screening of 200 potentially naturally contaminated cork borer samples obtained over seven weeks in a slaughterhouse resulted in 25 Salmonella-positive samples. The analysis of salmonellae within these samples showed that the PCR method had a higher sensitivity for samples with a low contamination level (<6.7 CFU/sample), where 15 of the samples negative with the MPN method was detected with the PCR method and 5 were found to be negative by both methods. For the samples with a higher contamination level (6.7-310 CFU/sample) a good agreement between the results obtained with the PCR and MPN methods was obtained. The quantitative real-time PCR method can easily be applied to other food and environmental matrices by adaptation of the pre-enrichment time and media. Copyright © 2010 Elsevier B.V. All rights reserved.

Comparisons of discrete and integrative sampling accuracy in estimating pulsed aquatic exposures.

PubMed

Morrison, Shane A; Luttbeg, Barney; Belden, Jason B

2016-11-01

Most current-use pesticides have short half-lives in the water column and thus the most relevant exposure scenarios for many aquatic organisms are pulsed exposures. Quantifying exposure using discrete water samples may not be accurate as few studies are able to sample frequently enough to accurately determine time-weighted average (TWA) concentrations of short aquatic exposures. Integrative sampling methods that continuously sample freely dissolved contaminants over time intervals (such as integrative passive samplers) have been demonstrated to be a promising measurement technique. We conducted several modeling scenarios to test the assumption that integrative methods may require many less samples for accurate estimation of peak 96-h TWA concentrations. We compared the accuracies of discrete point samples and integrative samples while varying sampling frequencies and a range of contaminant water half-lives (t 50  = 0.5, 2, and 8 d). Differences the predictive accuracy of discrete point samples and integrative samples were greatest at low sampling frequencies. For example, when the half-life was 0.5 d, discrete point samples required 7 sampling events to ensure median values > 50% and no sampling events reporting highly inaccurate results (defined as < 10% of the true 96-h TWA). Across all water half-lives investigated, integrative sampling only required two samples to prevent highly inaccurate results and measurements resulting in median values > 50% of the true concentration. Regardless, the need for integrative sampling diminished as water half-life increased. For an 8-d water half-life, two discrete samples produced accurate estimates and median values greater than those obtained for two integrative samples. Overall, integrative methods are the more accurate method for monitoring contaminants with short water half-lives due to reduced frequency of extreme values, especially with uncertainties around the timing of pulsed events. However, the acceptability of discrete sampling methods for providing accurate concentration measurements increases with increasing aquatic half-lives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of Legionella species in environmental water by the quantitative PCR method in combination with ethidium monoazide treatment.

PubMed

Inoue, Hiroaki; Takama, Tomoko; Yoshizaki, Miwa; Agata, Kunio

2015-01-01

We detected Legionella species in 111 bath water samples and 95 cooling tower water samples by using a combination of conventional plate culture, quantitative polymerase chain reaction (qPCR) and qPCR combined with ethidium monoazide treatment (EMA-qPCR) methods. In the case of bath water samples, Legionella spp. were detected in 30 samples by plate culture, in 85 samples by qPCR, and in 49 samples by EMA-qPCR. Of 81 samples determined to be Legionella-negative by plate culture, 56 and 23 samples were positive by qPCR and EMA-qPCR, respectively. Therefore, EMA treatment decreased the number of Legionella-positive bath water samples detected by qPCR. In contrast, EMA treatment had no effect on cooling tower water samples. We therefore expect that EMA-qPCR is a useful method for the rapid detection of viable Legionella spp. from bath water samples.

Validation and Clinical Evaluation of a Novel Method To Measure Miltefosine in Leishmaniasis Patients Using Dried Blood Spot Sample Collection

PubMed Central

Rosing, H.; Hillebrand, M. J. X.; Blesson, S.; Mengesha, B.; Diro, E.; Hailu, A.; Schellens, J. H. M.; Beijnen, J. H.

2016-01-01

To facilitate future pharmacokinetic studies of combination treatments against leishmaniasis in remote regions in which the disease is endemic, a simple cheap sampling method is required for miltefosine quantification. The aims of this study were to validate a liquid chromatography-tandem mass spectrometry method to quantify miltefosine in dried blood spot (DBS) samples and to validate its use with Ethiopian patients with visceral leishmaniasis (VL). Since hematocrit (Ht) levels are typically severely decreased in VL patients, returning to normal during treatment, the method was evaluated over a range of clinically relevant Ht values. Miltefosine was extracted from DBS samples using a simple method of pretreatment with methanol, resulting in >97% recovery. The method was validated over a calibration range of 10 to 2,000 ng/ml, and accuracy and precision were within ±11.2% and ≤7.0% (≤19.1% at the lower limit of quantification), respectively. The method was accurate and precise for blood spot volumes between 10 and 30 μl and for Ht levels of 20 to 35%, although a linear effect of Ht levels on miltefosine quantification was observed in the bioanalytical validation. DBS samples were stable for at least 162 days at 37°C. Clinical validation of the method using paired DBS and plasma samples from 16 VL patients showed a median observed DBS/plasma miltefosine concentration ratio of 0.99, with good correlation (Pearson's r = 0.946). Correcting for patient-specific Ht levels did not further improve the concordance between the sampling methods. This successfully validated method to quantify miltefosine in DBS samples was demonstrated to be a valid and practical alternative to venous blood sampling that can be applied in future miltefosine pharmacokinetic studies with leishmaniasis patients, without Ht correction. PMID:26787691

Methods for sample size determination in cluster randomized trials

PubMed Central

Rutterford, Clare; Copas, Andrew; Eldridge, Sandra

2015-01-01

Background: The use of cluster randomized trials (CRTs) is increasing, along with the variety in their design and analysis. The simplest approach for their sample size calculation is to calculate the sample size assuming individual randomization and inflate this by a design effect to account for randomization by cluster. The assumptions of a simple design effect may not always be met; alternative or more complicated approaches are required. Methods: We summarise a wide range of sample size methods available for cluster randomized trials. For those familiar with sample size calculations for individually randomized trials but with less experience in the clustered case, this manuscript provides formulae for a wide range of scenarios with associated explanation and recommendations. For those with more experience, comprehensive summaries are provided that allow quick identification of methods for a given design, outcome and analysis method. Results: We present first those methods applicable to the simplest two-arm, parallel group, completely randomized design followed by methods that incorporate deviations from this design such as: variability in cluster sizes; attrition; non-compliance; or the inclusion of baseline covariates or repeated measures. The paper concludes with methods for alternative designs. Conclusions: There is a large amount of methodology available for sample size calculations in CRTs. This paper gives the most comprehensive description of published methodology for sample size calculation and provides an important resource for those designing these trials. PMID:26174515

Improved Sampling Method Reduces Isokinetic Sampling Errors.

ERIC Educational Resources Information Center

Karels, Gale G.

The particulate sampling system currently in use by the Bay Area Air Pollution Control District, San Francisco, California is described in this presentation for the 12th Conference on Methods in Air Pollution and Industrial Hygiene Studies, University of Southern California, April, 1971. The method represents a practical, inexpensive tool that can…

40 CFR 53.59 - Aerosol transport test for Class I equivalent method samplers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... sample collection filter) differs significantly from that specified for reference method samplers as... transport is the percentage of a laboratory challenge aerosol which penetrates to the active sample filter of the candidate equivalent method sampler. (2) The active sample filter is the exclusive filter...

40 CFR 53.59 - Aerosol transport test for Class I equivalent method samplers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sample collection filter) differs significantly from that specified for reference method samplers as... transport is the percentage of a laboratory challenge aerosol which penetrates to the active sample filter of the candidate equivalent method sampler. (2) The active sample filter is the exclusive filter...

40 CFR 53.59 - Aerosol transport test for Class I equivalent method samplers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... sample collection filter) differs significantly from that specified for reference method samplers as... transport is the percentage of a laboratory challenge aerosol which penetrates to the active sample filter of the candidate equivalent method sampler. (2) The active sample filter is the exclusive filter...

40 CFR 53.59 - Aerosol transport test for Class I equivalent method samplers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... sample collection filter) differs significantly from that specified for reference method samplers as... transport is the percentage of a laboratory challenge aerosol which penetrates to the active sample filter of the candidate equivalent method sampler. (2) The active sample filter is the exclusive filter...

40 CFR 53.59 - Aerosol transport test for Class I equivalent method samplers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... sample collection filter) differs significantly from that specified for reference method samplers as... transport is the percentage of a laboratory challenge aerosol which penetrates to the active sample filter of the candidate equivalent method sampler. (2) The active sample filter is the exclusive filter...

CHARACTERIZATION OF HAZARDOUS WASTE SITES, A METHODS MANUAL. VOLUME 2. AVAILABLE SAMPLING METHODS (SECOND EDITION)

EPA Science Inventory

Investigations at hazardous waste sites and sites of chemical spills often require on-site measurements and sampling activities to assess the type and extent of contamination. This document is a compilation of sampling methods and materials suitable to address most needs that ari...

Absolute method of measuring magnetic susceptibility

USGS Publications Warehouse

Thorpe, A.; Senftle, F.E.

1959-01-01

An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.

The special case of the 2 × 2 table: asymptotic unconditional McNemar test can be used to estimate sample size even for analysis based on GEE.

PubMed

Borkhoff, Cornelia M; Johnston, Patrick R; Stephens, Derek; Atenafu, Eshetu

2015-07-01

Aligning the method used to estimate sample size with the planned analytic method ensures the sample size needed to achieve the planned power. When using generalized estimating equations (GEE) to analyze a paired binary primary outcome with no covariates, many use an exact McNemar test to calculate sample size. We reviewed the approaches to sample size estimation for paired binary data and compared the sample size estimates on the same numerical examples. We used the hypothesized sample proportions for the 2 × 2 table to calculate the correlation between the marginal proportions to estimate sample size based on GEE. We solved the inside proportions based on the correlation and the marginal proportions to estimate sample size based on exact McNemar, asymptotic unconditional McNemar, and asymptotic conditional McNemar. The asymptotic unconditional McNemar test is a good approximation of GEE method by Pan. The exact McNemar is too conservative and yields unnecessarily large sample size estimates than all other methods. In the special case of a 2 × 2 table, even when a GEE approach to binary logistic regression is the planned analytic method, the asymptotic unconditional McNemar test can be used to estimate sample size. We do not recommend using an exact McNemar test. Copyright © 2015 Elsevier Inc. All rights reserved.

A Predictive Model for Toxicity Effects Assessment of Biotransformed Hepatic Drugs Using Iterative Sampling Method.

PubMed

Tharwat, Alaa; Moemen, Yasmine S; Hassanien, Aboul Ella

2016-12-09

Measuring toxicity is one of the main steps in drug development. Hence, there is a high demand for computational models to predict the toxicity effects of the potential drugs. In this study, we used a dataset, which consists of four toxicity effects:mutagenic, tumorigenic, irritant and reproductive effects. The proposed model consists of three phases. In the first phase, rough set-based methods are used to select the most discriminative features for reducing the classification time and improving the classification performance. Due to the imbalanced class distribution, in the second phase, different sampling methods such as Random Under-Sampling, Random Over-Sampling and Synthetic Minority Oversampling Technique are used to solve the problem of imbalanced datasets. ITerative Sampling (ITS) method is proposed to avoid the limitations of those methods. ITS method has two steps. The first step (sampling step) iteratively modifies the prior distribution of the minority and majority classes. In the second step, a data cleaning method is used to remove the overlapping that is produced from the first step. In the third phase, Bagging classifier is used to classify an unknown drug into toxic or non-toxic. The experimental results proved that the proposed model performed well in classifying the unknown samples according to all toxic effects in the imbalanced datasets.

[Recent advances in sample preparation methods of plant hormones].

PubMed

Wu, Qian; Wang, Lus; Wu, Dapeng; Duan, Chunfeng; Guan, Yafeng

2014-04-01

Plant hormones are a group of naturally occurring trace substances which play a crucial role in controlling the plant development, growth and environment response. With the development of the chromatography and mass spectroscopy technique, chromatographic analytical method has become a widely used way for plant hormone analysis. Among the steps of chromatographic analysis, sample preparation is undoubtedly the most vital one. Thus, a highly selective and efficient sample preparation method is critical for accurate identification and quantification of phytohormones. For the three major kinds of plant hormones including acidic plant hormones & basic plant hormones, brassinosteroids and plant polypeptides, the sample preparation methods are reviewed in sequence especially the recently developed methods. The review includes novel methods, devices, extractive materials and derivative reagents for sample preparation of phytohormones analysis. Especially, some related works of our group are included. At last, the future developments in this field are also prospected.

[Standard sample preparation method for quick determination of trace elements in plastic].

PubMed

Yao, Wen-Qing; Zong, Rui-Long; Zhu, Yong-Fa

2011-08-01

Reference sample was prepared by masterbatch method, containing heavy metals with known concentration of electronic information products (plastic), the repeatability and precision were determined, and reference sample preparation procedures were established. X-Ray fluorescence spectroscopy (XRF) analysis method was used to determine the repeatability and uncertainty in the analysis of the sample of heavy metals and bromine element. The working curve and the metrical methods for the reference sample were carried out. The results showed that the use of the method in the 200-2000 mg x kg(-1) concentration range for Hg, Pb, Cr and Br elements, and in the 20-200 mg x kg(-1) range for Cd elements, exhibited a very good linear relationship, and the repeatability of analysis methods for six times is good. In testing the circuit board ICB288G and ICB288 from the Mitsubishi Heavy Industry Company, results agreed with the recommended values.

A study of active learning methods for named entity recognition in clinical text.

PubMed

Chen, Yukun; Lasko, Thomas A; Mei, Qiaozhu; Denny, Joshua C; Xu, Hua

2015-12-01

Named entity recognition (NER), a sequential labeling task, is one of the fundamental tasks for building clinical natural language processing (NLP) systems. Machine learning (ML) based approaches can achieve good performance, but they often require large amounts of annotated samples, which are expensive to build due to the requirement of domain experts in annotation. Active learning (AL), a sample selection approach integrated with supervised ML, aims to minimize the annotation cost while maximizing the performance of ML-based models. In this study, our goal was to develop and evaluate both existing and new AL methods for a clinical NER task to identify concepts of medical problems, treatments, and lab tests from the clinical notes. Using the annotated NER corpus from the 2010 i2b2/VA NLP challenge that contained 349 clinical documents with 20,423 unique sentences, we simulated AL experiments using a number of existing and novel algorithms in three different categories including uncertainty-based, diversity-based, and baseline sampling strategies. They were compared with the passive learning that uses random sampling. Learning curves that plot performance of the NER model against the estimated annotation cost (based on number of sentences or words in the training set) were generated to evaluate different active learning and the passive learning methods and the area under the learning curve (ALC) score was computed. Based on the learning curves of F-measure vs. number of sentences, uncertainty sampling algorithms outperformed all other methods in ALC. Most diversity-based methods also performed better than random sampling in ALC. To achieve an F-measure of 0.80, the best method based on uncertainty sampling could save 66% annotations in sentences, as compared to random sampling. For the learning curves of F-measure vs. number of words, uncertainty sampling methods again outperformed all other methods in ALC. To achieve 0.80 in F-measure, in comparison to random sampling, the best uncertainty based method saved 42% annotations in words. But the best diversity based method reduced only 7% annotation effort. In the simulated setting, AL methods, particularly uncertainty-sampling based approaches, seemed to significantly save annotation cost for the clinical NER task. The actual benefit of active learning in clinical NER should be further evaluated in a real-time setting. Copyright © 2015 Elsevier Inc. All rights reserved.

Observational studies of patients in the emergency department: a comparison of 4 sampling methods.

PubMed

Valley, Morgan A; Heard, Kennon J; Ginde, Adit A; Lezotte, Dennis C; Lowenstein, Steven R

2012-08-01

We evaluate the ability of 4 sampling methods to generate representative samples of the emergency department (ED) population. We analyzed the electronic records of 21,662 consecutive patient visits at an urban, academic ED. From this population, we simulated different models of study recruitment in the ED by using 2 sample sizes (n=200 and n=400) and 4 sampling methods: true random, random 4-hour time blocks by exact sample size, random 4-hour time blocks by a predetermined number of blocks, and convenience or "business hours." For each method and sample size, we obtained 1,000 samples from the population. Using χ(2) tests, we measured the number of statistically significant differences between the sample and the population for 8 variables (age, sex, race/ethnicity, language, triage acuity, arrival mode, disposition, and payer source). Then, for each variable, method, and sample size, we compared the proportion of the 1,000 samples that differed from the overall ED population to the expected proportion (5%). Only the true random samples represented the population with respect to sex, race/ethnicity, triage acuity, mode of arrival, language, and payer source in at least 95% of the samples. Patient samples obtained using random 4-hour time blocks and business hours sampling systematically differed from the overall ED patient population for several important demographic and clinical variables. However, the magnitude of these differences was not large. Common sampling strategies selected for ED-based studies may affect parameter estimates for several representative population variables. However, the potential for bias for these variables appears small. Copyright © 2012. Published by Mosby, Inc.

Correlative multiple porosimetries for reservoir sandstones with adoption of a new reference-sample-guided computed-tomographic method.

PubMed

Jin, Jae Hwa; Kim, Junho; Lee, Jeong-Yil; Oh, Young Min

2016-07-22

One of the main interests in petroleum geology and reservoir engineering is to quantify the porosity of reservoir beds as accurately as possible. A variety of direct measurements, including methods of mercury intrusion, helium injection and petrographic image analysis, have been developed; however, their application frequently yields equivocal results because these methods are different in theoretical bases, means of measurement, and causes of measurement errors. Here, we present a set of porosities measured in Berea Sandstone samples by the multiple methods, in particular with adoption of a new method using computed tomography and reference samples. The multiple porosimetric data show a marked correlativeness among different methods, suggesting that these methods are compatible with each other. The new method of reference-sample-guided computed tomography is more effective than the previous methods when the accompanied merits such as experimental conveniences are taken into account.

Correlative multiple porosimetries for reservoir sandstones with adoption of a new reference-sample-guided computed-tomographic method

PubMed Central

Jin, Jae Hwa; Kim, Junho; Lee, Jeong-Yil; Oh, Young Min

2016-01-01

One of the main interests in petroleum geology and reservoir engineering is to quantify the porosity of reservoir beds as accurately as possible. A variety of direct measurements, including methods of mercury intrusion, helium injection and petrographic image analysis, have been developed; however, their application frequently yields equivocal results because these methods are different in theoretical bases, means of measurement, and causes of measurement errors. Here, we present a set of porosities measured in Berea Sandstone samples by the multiple methods, in particular with adoption of a new method using computed tomography and reference samples. The multiple porosimetric data show a marked correlativeness among different methods, suggesting that these methods are compatible with each other. The new method of reference-sample-guided computed tomography is more effective than the previous methods when the accompanied merits such as experimental conveniences are taken into account. PMID:27445105

An Overview of Conventional and Emerging Analytical Methods for the Determination of Mycotoxins

PubMed Central

Cigić, Irena Kralj; Prosen, Helena

2009-01-01

Mycotoxins are a group of compounds produced by various fungi and excreted into the matrices on which they grow, often food intended for human consumption or animal feed. The high toxicity and carcinogenicity of these compounds and their ability to cause various pathological conditions has led to widespread screening of foods and feeds potentially polluted with them. Maximum permissible levels in different matrices have also been established for some toxins. As these are quite low, analytical methods for determination of mycotoxins have to be both sensitive and specific. In addition, an appropriate sample preparation and pre-concentration method is needed to isolate analytes from rather complicated samples. In this article, an overview of methods for analysis and sample preparation published in the last ten years is given for the most often encountered mycotoxins in different samples, mainly in food. Special emphasis is on liquid chromatography with fluorescence and mass spectrometric detection, while in the field of sample preparation various solid-phase extraction approaches are discussed. However, an overview of other analytical and sample preparation methods less often used is also given. Finally, different matrices where mycotoxins have to be determined are discussed with the emphasis on their specific characteristics important for the analysis (human food and beverages, animal feed, biological samples, environmental samples). Various issues important for accurate qualitative and quantitative analyses are critically discussed: sampling and choice of representative sample, sample preparation and possible bias associated with it, specificity of the analytical method and critical evaluation of results. PMID:19333436

Usefulness of in-house PCR methods for hepatitis B virus DNA detection.

PubMed

Portilho, Moyra Machado; Baptista, Marcia Leite; da Silva, Messias; de Sousa, Paulo Sérgio Fonseca; Lewis-Ximenez, Lia Laura; Lampe, Elisabeth; Villar, Livia Melo

2015-10-01

The aim of the present study was to evaluate the performance of three in-house PCR techniques for HBV DNA detection and compare it with commercial quantitative methods to evaluate the usefulness of in-house methods for HBV diagnosis. Three panels of HBsAg reactive sera samples were evaluated: (i) 50 samples were examined using three methods for in-house qualitative PCR and the Cobas Amplicor HBV Monitor Assay; (ii) 87 samples were assayed using in-house semi-nested PCR and the Cobas TaqMan HBV test; (iii) 11 serial samples obtained from 2 HBV-infected individuals were assayed using the Cobas Amplicor HBV test and semi-nested PCR. In panel I, HBV DNA was detected in 44 samples using the Cobas Amplicor HBV test, 42 samples using semi-nested PCR (90% concordance with Cobas Amplicor), 22 samples using PCR for the core gene (63.6% concordance) and 29 samples using single-round PCR for the pre-S/S gene (75% concordance). In panel II, HBV DNA was quantified in 78 of the 87 HBsAg reactive samples using Cobas TaqMan but 52 samples using semi-nested PCR (67.8% concordance). HBV DNA was detected in serial samples until the 17th and 26th week after first donation using in-house semi-nested PCR and the Cobas Amplicor HBV test, respectively. In-house semi-nested PCR presented adequate concordance with commercial methods as an alternative method for HBV molecular diagnosis in low-resource settings. Copyright © 2015 Elsevier B.V. All rights reserved.

Confidence intervals for the population mean tailored to small sample sizes, with applications to survey sampling.

PubMed

Rosenblum, Michael A; Laan, Mark J van der

2009-01-07

The validity of standard confidence intervals constructed in survey sampling is based on the central limit theorem. For small sample sizes, the central limit theorem may give a poor approximation, resulting in confidence intervals that are misleading. We discuss this issue and propose methods for constructing confidence intervals for the population mean tailored to small sample sizes. We present a simple approach for constructing confidence intervals for the population mean based on tail bounds for the sample mean that are correct for all sample sizes. Bernstein's inequality provides one such tail bound. The resulting confidence intervals have guaranteed coverage probability under much weaker assumptions than are required for standard methods. A drawback of this approach, as we show, is that these confidence intervals are often quite wide. In response to this, we present a method for constructing much narrower confidence intervals, which are better suited for practical applications, and that are still more robust than confidence intervals based on standard methods, when dealing with small sample sizes. We show how to extend our approaches to much more general estimation problems than estimating the sample mean. We describe how these methods can be used to obtain more reliable confidence intervals in survey sampling. As a concrete example, we construct confidence intervals using our methods for the number of violent deaths between March 2003 and July 2006 in Iraq, based on data from the study "Mortality after the 2003 invasion of Iraq: A cross sectional cluster sample survey," by Burnham et al. (2006).

A Monte-Carlo method which is not based on Markov chain algorithm, used to study electrostatic screening of ion potential

NASA Astrophysics Data System (ADS)

Šantić, Branko; Gracin, Davor

2017-12-01

A new simple Monte Carlo method is introduced for the study of electrostatic screening by surrounding ions. The proposed method is not based on the generally used Markov chain method for sample generation. Each sample is pristine and there is no correlation with other samples. As the main novelty, the pairs of ions are gradually added to a sample provided that the energy of each ion is within the boundaries determined by the temperature and the size of ions. The proposed method provides reliable results, as demonstrated by the screening of ion in plasma and in water.

Preliminary evaluation of a gel tube agglutination major cross-match method in dogs.

PubMed

Villarnovo, Dania; Burton, Shelley A; Horney, Barbara S; MacKenzie, Allan L; Vanderstichel, Raphaël

2016-09-01

A major cross-match gel tube test is available for use in dogs yet has not been clinically evaluated. This study compared cross-match results obtained using the gel tube and the standard tube methods for canine samples. Study 1 included 107 canine sample donor-recipient pairings cross-match tested with the RapidVet-H method gel tube test and compared results with the standard tube method. Additionally, 120 pairings using pooled sera containing anti-canine erythrocyte antibody at various concentrations were tested with leftover blood from a hospital population to assess sensitivity and specificity of the gel tube method in comparison with the standard method. The gel tube method had a good relative specificity of 96.1% in detecting lack of agglutination (compatibility) compared to the standard tube method. Agreement between the 2 methods was moderate. Nine of 107 pairings showed agglutination/incompatibility on either test, too few to allow reliable calculation of relative sensitivity. Fifty percent of the gel tube method results were difficult to interpret due to sample spreading in the reaction and/or negative control tubes. The RapidVet-H method agreed with the standard cross-match method on compatible samples, but detected incompatibility in some sample pairs that were compatible with the standard method. Evaluation using larger numbers of incompatible pairings is needed to assess diagnostic utility. The gel tube method results were difficult to categorize due to sample spreading. Weak agglutination reactions or other factors such as centrifuge model may be responsible. © 2016 American Society for Veterinary Clinical Pathology.

A modified method for diffusive monitoring of 3-ethenylpyridine as a specific marker of environmental tobacco smoke

NASA Astrophysics Data System (ADS)

Kuusimäki, Leea; Peltonen, Kimmo; Vainiotalo, Sinikka

A previously introduced method for monitoring environmental tobacco smoke (ETS) was further validated. The method is based on diffusive sampling of a vapour-phase marker, 3-ethenylpyridine (3-EP), with 3 M passive monitors (type 3500). Experiments were done in a dynamic chamber to assess diffusive sampling in comparison with active sampling in charcoal tubes or XAD-4 tubes. The sampling rate for 3-EP collected on the diffusive sampler was 23.1±0.6 mL min -1. The relative standard deviation for parallel samples ( n=6) ranged from 4% to 14% among experiments ( n=9). No marked reverse diffusion of 3-EP was detected nor any significant effect of relative humidity at 20%, 50% or 80%. The diffusive sampling of 3-EP was validated in field measurements in 15 restaurants in comparison with 3-EP and nicotine measurements using active sampling. The 3-EP concentration in restaurants ranged from 0.01 to 9.8 μg m -3, and the uptake rate for 3-EP based on 92 parallel samples was 24.0±0.4 mL min -1. A linear correlation ( r=0.98) was observed between 3-EP and nicotine concentrations, the average ratio of 3-EP to nicotine being 1:8. Active sampling of 3-EP and nicotine in charcoal tubes provided more reliable results than sampling in XAD-4 tubes. All samples were analysed using gas chromatography-mass spectrometry after elution with a 15% solution of pyridine in toluene. For nicotine, the limit of quantification of the charcoal tube method was 4 ng per sample, corresponding to 0.04 μg m -3 for an air sample of 96 L. For 3-EP, the limit of quantification of the diffusive method was 0.5-1.0 ng per sample, corresponding to 0.04-0.09 μg m -3 for 8 h sampling. The diffusive method proved suitable for ETS monitoring, even at low levels of ETS.

Feasibility of zero tolerance for Salmonella on raw poultry

USDA-ARS?s Scientific Manuscript database

Ideally, poultry producing countries around the globe should use internationally standardized sampling methods for Salmonella. It is difficult to compare prevalence data from country-to-country when sample plan, sample type, sample frequency and laboratory media along with methods differ. The Europe...

Flexible sampling large-scale social networks by self-adjustable random walk

NASA Astrophysics Data System (ADS)

Xu, Xiao-Ke; Zhu, Jonathan J. H.

2016-12-01

Online social networks (OSNs) have become an increasingly attractive gold mine for academic and commercial researchers. However, research on OSNs faces a number of difficult challenges. One bottleneck lies in the massive quantity and often unavailability of OSN population data. Sampling perhaps becomes the only feasible solution to the problems. How to draw samples that can represent the underlying OSNs has remained a formidable task because of a number of conceptual and methodological reasons. Especially, most of the empirically-driven studies on network sampling are confined to simulated data or sub-graph data, which are fundamentally different from real and complete-graph OSNs. In the current study, we propose a flexible sampling method, called Self-Adjustable Random Walk (SARW), and test it against with the population data of a real large-scale OSN. We evaluate the strengths of the sampling method in comparison with four prevailing methods, including uniform, breadth-first search (BFS), random walk (RW), and revised RW (i.e., MHRW) sampling. We try to mix both induced-edge and external-edge information of sampled nodes together in the same sampling process. Our results show that the SARW sampling method has been able to generate unbiased samples of OSNs with maximal precision and minimal cost. The study is helpful for the practice of OSN research by providing a highly needed sampling tools, for the methodological development of large-scale network sampling by comparative evaluations of existing sampling methods, and for the theoretical understanding of human networks by highlighting discrepancies and contradictions between existing knowledge/assumptions of large-scale real OSN data.

Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

PubMed

Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

2017-10-20

The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m 3 ) and benzene (1.7±0.5μg/m 3 ) is lower when using TGDE compared to methanol, which was previously used (385μg/m 3 for TCE and 130μg/m 3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ 13 C analysis. Due to a different analytical procedure, the method detection limit associated with δ 37 Cl analysis was found to be 156±6μg/m 3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method without the need to determine the initial gas phase TCE concentration. The simplified field deployment approach of the solvent-based dissolution method combined with the conventional analytical procedure used for groundwater samples substantially facilitates the application of CSIA to gas phase studies. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Eggenkamp, H G M; Louvat, P

2018-04-30

In natural samples bromine is present in trace amounts, and measurement of stable Br isotopes necessitates its separation from the matrix. Most methods described previously need large samples or samples with high Br/Cl ratios. The use of metals as reagents, proposed in previous Br distillation methods, must be avoided for multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analyses, because of risk of cross-contamination, since the instrument is also used to measure stable isotopes of metals. Dedicated to water and evaporite samples with low Br/Cl ratios, the proposed method is a simple distillation that separates bromide from chloride for isotopic analyses by MC-ICP-MS. It is based on the difference in oxidation potential between chloride and bromide in the presence of nitric acid. The sample is mixed with dilute (1:5) nitric acid in a distillation flask and heated over a candle flame for 10 min. The distillate (bromine) is trapped in an ammonia solution and reduced to bromide. Chloride is only distilled to a very small extent. The obtained solution can be measured directly by MC-ICP-MS for stable Br isotopes. The method was tested for a variety of volumes, ammonia concentrations, pH values and distillation times and compared with the classic ion-exchange chromatography method. The method more efficiently separates Br from Cl, so that samples with lower Br/Cl ratios can be analysed, with Br isotope data in agreement with those obtained by previous methods. Unlike other Br extraction methods based on oxidation, the distillation method presented here does not use any metallic ion for redox reactions that could contaminate the mass spectrometer. It is efficient in separating Br from samples with low Br/Cl ratios. The method ensures reproducible recovery yields and a long-term reproducibility of ±0.11‰ (1 standard deviation). The distillation method was successfully applied to samples with low Br/Cl ratios and low Br amounts (down to 20 μg). Copyright © 2018 John Wiley & Sons, Ltd.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of organophosphate pesticides in filtered water by gas chromatography with flame photometric detection

USGS Publications Warehouse

Jha, Virendra K.; Wydoski, Duane S.

2002-01-01

A method for the isolation of 20 parent organophosphate pesticides and 5 pesticide degradates from filtered natural-water samples is described. Seven of these compounds are reported permanently with an estimated concentration because of performance issues. Water samples are filtered to remove suspended particulate matter, and then 1 liter of filtrate is pumped through disposable solid-phase extraction columns that contain octadecyl-bonded porous silica to extract the compounds. The C-18 columns are dried with nitrogen gas, and method compounds are eluted from the columns with ethyl acetate. The extract is analyzed by dual capillary-column gas chromatography with flame photometric detection. Single-operator method detection limits in all three water-matrix samples ranged from 0.004 to 0.012 microgram per liter. Method performance was validated by spiking all compounds into three different matrices at three different concentrations. Eight replicates were analyzed at each concentration level in each matrix. Mean recoveries of method compounds spiked in surface-water samples ranged from 39 to 149 percent and those in ground-water samples ranged from 40 to 124 percent for all pesticides except dimethoate. Mean recoveries of method compounds spiked in reagent-water samples ranged from 41 to 119 percent for all pesticides except dimethoate. Dimethoate exhibited reduced recoveries (mean of 43 percent in low- and medium-concentration level spiked samples and 20 percent in high-concentration level spiked samples) in all matrices because of incomplete collection on the C-18 column. As a result, concen-trations of dimethoate and six other compounds (based on performance issues) in samples are reported in this method with an estimated remark code.

A passive guard for low thermal conductivity measurement of small samples by the hot plate method

NASA Astrophysics Data System (ADS)

Jannot, Yves; Degiovanni, Alain; Grigorova-Moutiers, Veneta; Godefroy, Justine

2017-01-01

Hot plate methods under steady state conditions are based on a 1D model to estimate the thermal conductivity, using measurements of the temperatures T 0 and T 1 of the two sides of the sample and of the heat flux crossing it. To be consistent with the hypothesis of the 1D heat flux, either a hot plate guarded apparatus is used, or the temperature is measured at the centre of the sample. On one hand the latter method can be used only if the ratio thickness/width of the sample is sufficiently low and on the other hand the guarded hot plate method requires large width samples (typical cross section of 0.6  ×  0.6 m2). That is why both methods cannot be used for low width samples. The method presented in this paper is based on an optimal choice of the temperatures T 0 and T 1 compared to the ambient temperature T a, enabling the estimation of the thermal conductivity with a centered hot plate method, by applying the 1D heat flux model. It will be shown that these optimal values do not depend on the size or on the thermal conductivity of samples (in the range 0.015-0.2 W m-1 K-1), but only on T a. The experimental results obtained validate the method for several reference samples for values of the ratio thickness/width up to 0.3, thus enabling the measurement of the thermal conductivity of samples having a small cross-section, down to 0.045  ×  0.045 m2.

Screen Space Ambient Occlusion Based Multiple Importance Sampling for Real-Time Rendering

NASA Astrophysics Data System (ADS)

Zerari, Abd El Mouméne; Babahenini, Mohamed Chaouki

2018-03-01

We propose a new approximation technique for accelerating the Global Illumination algorithm for real-time rendering. The proposed approach is based on the Screen-Space Ambient Occlusion (SSAO) method, which approximates the global illumination for large, fully dynamic scenes at interactive frame rates. Current algorithms that are based on the SSAO method suffer from difficulties due to the large number of samples that are required. In this paper, we propose an improvement to the SSAO technique by integrating it with a Multiple Importance Sampling technique that combines a stratified sampling method with an importance sampling method, with the objective of reducing the number of samples. Experimental evaluation demonstrates that our technique can produce high-quality images in real time and is significantly faster than traditional techniques.

A novel quality by design approach for developing an HPLC method to analyze herbal extracts: A case study of sugar content analysis.

PubMed

Shao, Jingyuan; Cao, Wen; Qu, Haibin; Pan, Jianyang; Gong, Xingchu

2018-01-01

The aim of this study was to present a novel analytical quality by design (AQbD) approach for developing an HPLC method to analyze herbal extracts. In this approach, critical method attributes (CMAs) and critical method parameters (CMPs) of the analytical method were determined using the same data collected from screening experiments. The HPLC-ELSD method for separation and quantification of sugars in Codonopsis Radix extract (CRE) samples and Astragali Radix extract (ARE) samples was developed as an example method with a novel AQbD approach. Potential CMAs and potential CMPs were found with Analytical Target Profile. After the screening experiments, the retention time of the D-glucose peak of CRE samples, the signal-to-noise ratio of the D-glucose peak of CRE samples, and retention time of the sucrose peak in ARE samples were considered CMAs. The initial and final composition of the mobile phase, flow rate, and column temperature were found to be CMPs using a standard partial regression coefficient method. The probability-based design space was calculated using a Monte-Carlo simulation method and verified by experiments. The optimized method was validated to be accurate and precise, and then it was applied in the analysis of CRE and ARE samples. The present AQbD approach is efficient and suitable for analysis objects with complex compositions.

A non-uniformly under-sampled blade tip-timing signal reconstruction method for blade vibration monitoring.

PubMed

Hu, Zheng; Lin, Jun; Chen, Zhong-Sheng; Yang, Yong-Min; Li, Xue-Jun

2015-01-22

High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT) have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes.

Sampling Methods for Detection and Monitoring of the Asian Citrus Psyllid (Hemiptera: Psyllidae).

PubMed

Monzo, C; Arevalo, H A; Jones, M M; Vanaclocha, P; Croxton, S D; Qureshi, J A; Stansly, P A

2015-06-01

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is a key pest of citrus due to its role as vector of citrus greening disease or "huanglongbing." ACP monitoring is considered an indispensable tool for management of vector and disease. In the present study, datasets collected between 2009 and 2013 from 245 citrus blocks were used to evaluate precision, sensitivity for detection, and efficiency of five sampling methods. The number of samples needed to reach a 0.25 standard error-mean ratio was estimated using Taylor's power law and used to compare precision among sampling methods. Comparison of detection sensitivity and time expenditure (cost) between stem-tap and other sampling methodologies conducted consecutively at the same location were also assessed. Stem-tap sampling was the most efficient sampling method when ACP densities were moderate to high and served as the basis for comparison with all other methods. Protocols that grouped trees near randomly selected locations across the block were more efficient than sampling trees at random across the block. Sweep net sampling was similar to stem-taps in number of captures per sampled unit, but less precise at any ACP density. Yellow sticky traps were 14 times more sensitive than stem-taps but much more time consuming and thus less efficient except at very low population densities. Visual sampling was efficient for detecting and monitoring ACP at low densities. Suction sampling was time consuming and taxing but the most sensitive of all methods for detection of sparse populations. This information can be used to optimize ACP monitoring efforts. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Capillary microextraction: A new method for sampling methamphetamine vapour.

PubMed

Nair, M V; Miskelly, G M

2016-11-01

Clandestine laboratories pose a serious health risk to first responders, investigators, decontamination companies, and the public who may be inadvertently exposed to methamphetamine and other chemicals used in its manufacture. Therefore there is an urgent need for reliable methods to detect and measure methamphetamine at such sites. The most common method for determining methamphetamine contamination at former clandestine laboratory sites is selected surface wipe sampling, followed by analysis with gas chromatography-mass spectrometry (GC-MS). We are investigating the use of sampling for methamphetamine vapour to complement such wipe sampling. In this study, we report the use of capillary microextraction (CME) devices for sampling airborne methamphetamine, and compare their sampling efficiency with a previously reported dynamic SPME method. The CME devices consisted of PDMS-coated glass filter strips inside a glass tube. The devices were used to dynamically sample methamphetamine vapour in the range of 0.42-4.2μgm -3 , generated by a custom-built vapour dosing system, for 1-15min, and methamphetamine was analysed using a GC-MS fitted with a ChromatoProbe thermal desorption unit. The devices showed good reproducibility (RSD<15%), and a curvilinear pre-equilibrium relationship between sampling times and peak area, which can be utilised for calibration. Under identical sampling conditions, the CME devices were approximately 30 times more sensitive than the dynamic SPME method. The CME devices could be stored for up to 3days after sampling prior to analysis. Consecutive sampling of methamphetamine and its isotopic substitute, d-9 methamphetamine showed no competitive displacement. This suggests that CME devices, pre-loaded with an internal standard, could be a feasible method for sampling airborne methamphetamine at former clandestine laboratories. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

A Non-Uniformly Under-Sampled Blade Tip-Timing Signal Reconstruction Method for Blade Vibration Monitoring

PubMed Central

Hu, Zheng; Lin, Jun; Chen, Zhong-Sheng; Yang, Yong-Min; Li, Xue-Jun

2015-01-01

High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT) have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes. PMID:25621612

Recommendations for level-determined sampling in wells

NASA Astrophysics Data System (ADS)

Lerner, David N.; Teutsch, Georg

1995-10-01

Level-determined samples of groundwater are increasingly important for hydrogeological studies. The techniques for collecting them range from the use of purpose drilled wells, sometimes with sophisticated dedicated multi-level samplers in them, to a variety of methods used in open wells. Open, often existing, wells are frequently used on cost grounds, but there are risks of obtaining poor and unrepresentative samples. Alternative approaches to level-determined sampling incorporate seven concepts: depth sampling; packer systems; individual wells; dedicated multi-level systems; separation pumping; baffle systems; multi-port sock samplers. These are outlined and evaluated in terms of the environment to be sampled, and the features and performance of the methods. Recommendations are offered to match methods to sampling problems.

Compendium of selected methods for sampling and analysis at geothermal facilities

NASA Astrophysics Data System (ADS)

Kindle, C. H.; Pool, K. H.; Ludwick, J. D.; Robertson, D. E.

1984-06-01

An independent study of the field has resulted in a compilation of the best methods for sampling, preservation and analysis of potential pollutants from geothermally fueled electric power plants. These methods are selected as the most usable over the range of application commonly experienced in the various geothermal plant sample locations. In addition to plant and well piping, techniques for sampling cooling towers, ambient gases, solids, surface and subsurface waters are described. Emphasis is placed on the use of sampling proves to extract samples from heterogeneous flows. Certain sampling points, constituents and phases of plant operation are more amenable to quality assurance improvement in the emission measurements than others and are so identified.

Application toward Confocal Full-Field Microscopic X-ray Absorption Near Edge Structure Spectroscopy.

PubMed

Tack, Pieter; Vekemans, Bart; Laforce, Brecht; Rudloff-Grund, Jennifer; Hernández, Willinton Y; Garrevoet, Jan; Falkenberg, Gerald; Brenker, Frank; Van Der Voort, Pascal; Vincze, Laszlo

2017-02-07

Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples. Here, a fluorescence method is displayed using an energy-dispersive pnCCD detector, the SLcam, characterized by measurement times far superior to what is generally applicable. Additionally, this method operates in confocal mode, thus providing direct 3D spatially resolved chemical state information from a selected subvolume of a sample, without the need of rotating a sample. The method is applied to two samples: a gold-supported magnesia catalyst (Au/MgO) and a natural diamond containing Fe-rich inclusions. Both samples provide XANES spectra that can be overlapped with reference XANES spectra, allowing this method to be used for fingerprinting and linear combination analysis of known XANES reference compounds.

Rapid method to determine 226Ra in steel samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

2017-09-22

The rapid measurement of 226Ra in steel samples is very important in the event of a radiological emergency. 226Ra (T 1/2 = 1600 y) is a natural radionuclide present in the environment and a highly toxic alpha-emitter. Due to its long life and tendency to concentrate in bones, 226Ra ingestion or inhalation can lead to significant committed dose to individuals. A new method for the determination of 226Ra in steel samples has been developed at the Savannah River Environmental Laboratory. The new method employs a rugged acid digestion method that includes hydrofluoric acid, followed by a single precipitation step tomore » rapidly preconcentrate the radium and remove most of the dissolved steel sample matrix. Radium is then separated using a combination of cation exchange and extraction chromatography, and 226Ra is measured by alpha spectrometry. This approach has a sample preparation time of ~ 8 h for steel samples, has a very high tracer yield (> 88%), and removes interferences effectively. A 133Ba yield tracer is used so that samples can be counted immediately following the separation method, avoiding lengthy ingrowth times that are required in other methods.« less

Rapid method to determine 226Ra in steel samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.

The rapid measurement of 226Ra in steel samples is very important in the event of a radiological emergency. 226Ra (T 1/2 = 1600 y) is a natural radionuclide present in the environment and a highly toxic alpha-emitter. Due to its long life and tendency to concentrate in bones, 226Ra ingestion or inhalation can lead to significant committed dose to individuals. A new method for the determination of 226Ra in steel samples has been developed at the Savannah River Environmental Laboratory. The new method employs a rugged acid digestion method that includes hydrofluoric acid, followed by a single precipitation step tomore » rapidly preconcentrate the radium and remove most of the dissolved steel sample matrix. Radium is then separated using a combination of cation exchange and extraction chromatography, and 226Ra is measured by alpha spectrometry. This approach has a sample preparation time of ~ 8 h for steel samples, has a very high tracer yield (> 88%), and removes interferences effectively. A 133Ba yield tracer is used so that samples can be counted immediately following the separation method, avoiding lengthy ingrowth times that are required in other methods.« less

Oral sampling methods are associated with differences in immune marker concentrations.

PubMed

Fakhry, Carole; Qeadan, Fares; Gilman, Robert H; Yori, Pablo; Kosek, Margaret; Patterson, Nicole; Eisele, David W; Gourin, Christine G; Chitguppi, Chandala; Marks, Morgan; Gravitt, Patti

2018-06-01

To determine whether the concentration and distribution of immune markers in paired oral samples were similar. Clinical research. Cross-sectional study. Paired saliva and oral secretions (OS) samples were collected. The concentration of immune markers was estimated using Luminex multiplex assay (Thermo Fisher Scientific, Waltham, MA). For each sample, the concentration of respective immune markers was normalized to total protein present and log-transformed. Median concentrations of immune markers were compared between both types of samples. Intermarker correlation in each sampling method and across sampling methods was evaluated. There were 90 study participants. Concentrations of immune markers in saliva samples were significantly different from concentrations in OS samples. Oral secretions samples showed higher concentrations of immunoregulatory markers, whereas the saliva samples contained proinflammatory markers in higher concentration. The immune marker profile in saliva samples is distinct from the immune marker profile in paired OS samples. 2b. Laryngoscope, 128:E214-E221, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Trace elemental analysis of glass and paint samples of forensic interest by ICP-MS using laser ablation solid sample introduction

NASA Astrophysics Data System (ADS)

Almirall, Jose R.; Trejos, Tatiana; Hobbs, Andria; Furton, Kenneth G.

2003-09-01

The importance of small amounts of glass and paint evidence as a means to associate a crime event to a suspect or a suspect to another individual has been demonstrated in many cases. Glass is a fragile material that is often found at the scenes of crimes such as burglaries, hit-and-run accidents and violent crime offenses. Previous work has demonstrated the utility of elemental analysis by solution ICP-MS of small amounts of glass for the comparison between a fragment found at a crime scene to a possible source of the glass. The multi-element capability and the sensitivity of ICP-MS combined with the simplified sample introduction of laser ablation prior to ion detection provides for an excellent and relatively non-destructive technique for elemental analysis of glass fragments. The direct solid sample introduction technique of laser ablation (LA) is reported as an alternative to the solution method. Direct solid sampling provides several advantages over solution methods and shows great potential for a number of solid sample analyses in forensic science. The advantages of laser ablation include the simplification of sample preparation, thereby reducing the time and complexity of the analysis, the elimination of handling acid dissolution reagents such as HF and the reduction of sources of interferences in the ionization plasma. Direct sampling also provides for essentially "non-destructive" sampling due to the removal of very small amounts of sample needed for analysis. The discrimination potential of LA-ICP-MS is compared with previously reported solution ICP-MS methods using external calibration with internal standardization and a newly reported solution isotope dilution (ID) method. A total of ninety-one different glass samples were used for the comparison study using the techniques mentioned. One set consisted of forty-five headlamps taken from a variety of automobiles representing a range of twenty years of manufacturing dates. A second set consisted of forty-six automotive glasses (side windows and windshields) representing casework glass from different vehicle manufacturers over several years was also characterized by RI and elemental composition analysis. The solution sample introduction techniques (external calibration and isotope dilution) provide for excellent sensitivity and precision but have the disadvantages of destroying the sample and also involve complex sample preparation. The laser ablation method was simpler, faster and produced comparable discrimination to the EC-ICP-MS and ID-ICP-MS. LA-ICP-MS can provide for an excellent alternative to solution analysis of glass in forensic casework samples. Paints and coatings are frequently encountered as trace evidence samples submitted to forensic science laboratories. A LA-ICP-MS method has been developed to complement the commonly used techniques in forensic laboratories in order to better characterize these samples for forensic purposes. Time-resolved plots of each sample can be compared to associate samples to each other or to discriminate between samples. Additionally, the concentration of lead and the ratios of other elements have been determined in various automotive paints by the reported method. A sample set of eighteen (18) survey automotive paint samples have been analyzed with the developed method in order to determine the utility of LA-ICP-MS and to compare the method to the more commonly used scanning electron microscopy (SEM) method for elemental characterization of paint layers in forensic casework.

Evaluation of the direct and diffusion methods for the determination of fluoride content in table salt

PubMed Central

Martínez-Mier, E. Angeles; Soto-Rojas, Armando E.; Buckley, Christine M.; Margineda, Jorge; Zero, Domenick T.

2010-01-01

Objective The aim of this study was to assess methods currently used for analyzing fluoridated salt in order to identify the most useful method for this type of analysis. Basic research design Seventy-five fluoridated salt samples were obtained. Samples were analyzed for fluoride content, with and without pretreatment, using direct and diffusion methods. Element analysis was also conducted in selected samples. Fluoride was added to ultra pure NaCl and non-fluoridated commercial salt samples and Ca and Mg were added to fluoride samples in order to assess fluoride recoveries using modifications to the methods. Results Larger amounts of fluoride were found and recovered using diffusion than direct methods (96%–100% for diffusion vs. 67%–90% for direct). Statistically significant differences were obtained between direct and diffusion methods using different ion strength adjusters. Pretreatment methods reduced the amount of recovered fluoride. Determination of fluoride content was influenced both by the presence of NaCl and other ions in the salt. Conclusion Direct and diffusion techniques for analysis of fluoridated salt are suitable methods for fluoride analysis. The choice of method should depend on the purpose of the analysis. PMID:20088217

Sample Size Calculations for Population Size Estimation Studies Using Multiplier Methods With Respondent-Driven Sampling Surveys.

PubMed

Fearon, Elizabeth; Chabata, Sungai T; Thompson, Jennifer A; Cowan, Frances M; Hargreaves, James R

2017-09-14

While guidance exists for obtaining population size estimates using multiplier methods with respondent-driven sampling surveys, we lack specific guidance for making sample size decisions. To guide the design of multiplier method population size estimation studies using respondent-driven sampling surveys to reduce the random error around the estimate obtained. The population size estimate is obtained by dividing the number of individuals receiving a service or the number of unique objects distributed (M) by the proportion of individuals in a representative survey who report receipt of the service or object (P). We have developed an approach to sample size calculation, interpreting methods to estimate the variance around estimates obtained using multiplier methods in conjunction with research into design effects and respondent-driven sampling. We describe an application to estimate the number of female sex workers in Harare, Zimbabwe. There is high variance in estimates. Random error around the size estimate reflects uncertainty from M and P, particularly when the estimate of P in the respondent-driven sampling survey is low. As expected, sample size requirements are higher when the design effect of the survey is assumed to be greater. We suggest a method for investigating the effects of sample size on the precision of a population size estimate obtained using multipler methods and respondent-driven sampling. Uncertainty in the size estimate is high, particularly when P is small, so balancing against other potential sources of bias, we advise researchers to consider longer service attendance reference periods and to distribute more unique objects, which is likely to result in a higher estimate of P in the respondent-driven sampling survey. ©Elizabeth Fearon, Sungai T Chabata, Jennifer A Thompson, Frances M Cowan, James R Hargreaves. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 14.09.2017.

Efficient free energy calculations by combining two complementary tempering sampling methods.

PubMed

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-14

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

Efficient free energy calculations by combining two complementary tempering sampling methods

NASA Astrophysics Data System (ADS)

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-01

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

A novel method for effective diffusion coefficient measurement in gas diffusion media of polymer electrolyte fuel cells

NASA Astrophysics Data System (ADS)

Yang, Linlin; Sun, Hai; Fu, Xudong; Wang, Suli; Jiang, Luhua; Sun, Gongquan

2014-07-01

A novel method for measuring effective diffusion coefficient of porous materials is developed. The oxygen concentration gradient is established by an air-breathing proton exchange membrane fuel cell (PEMFC). The porous sample is set in a sample holder located in the cathode plate of the PEMFC. At a given oxygen flux, the effective diffusion coefficients are related to the difference of oxygen concentration across the samples, which can be correlated with the differences of the output voltage of the PEMFC with and without inserting the sample in the cathode plate. Compared to the conventional electrical conductivity method, this method is more reliable for measuring non-wetting samples.

Rapid method for the determination of 226Ra in hydraulic fracturing wastewater samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Sherrod L.; Culligan, Brian K.; Warren, Richard A.

A new method that rapidly preconcentrates and measures 226Ra from hydraulic fracturing wastewater samples was developed in the Savannah River Environmental Laboratory. The method improves the quality of 226Ra measurements using gamma spectrometry by providing up to 100x preconcentration of 226Ra from this difficult sample matrix, which contains very high levels of calcium, barium, strontium, magnesium and sodium. The high chemical yield, typically 80-90%, facilitates a low detection limit, important for lower level samples, and indicates method ruggedness. Ba-133 tracer is used to determine chemical yield and correct for geometry-related counting issues. The 226Ra sample preparation takes < 2 hours.

Rapid method for the determination of 226Ra in hydraulic fracturing wastewater samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian K.; Warren, Richard A.; ...

2016-03-24

A new method that rapidly preconcentrates and measures 226Ra from hydraulic fracturing wastewater samples was developed in the Savannah River Environmental Laboratory. The method improves the quality of 226Ra measurements using gamma spectrometry by providing up to 100x preconcentration of 226Ra from this difficult sample matrix, which contains very high levels of calcium, barium, strontium, magnesium and sodium. The high chemical yield, typically 80-90%, facilitates a low detection limit, important for lower level samples, and indicates method ruggedness. Ba-133 tracer is used to determine chemical yield and correct for geometry-related counting issues. The 226Ra sample preparation takes < 2 hours.

After site selection and before data analysis: sampling, sorting, and laboratory procedures used in stream benthic macroinvertebrate monitoring programs by USA state agencies

USGS Publications Warehouse

Carter, James L.; Resh, Vincent H.

2001-01-01

A survey of methods used by US state agencies for collecting and processing benthic macroinvertebrate samples from streams was conducted by questionnaire; 90 responses were received and used to describe trends in methods. The responses represented an estimated 13,000-15,000 samples collected and processed per year. Kicknet devices were used in 64.5% of the methods; other sampling devices included fixed-area samplers (Surber and Hess), artificial substrates (Hester-Dendy and rock baskets), grabs, and dipnets. Regional differences existed, e.g., the 1-m kicknet was used more often in the eastern US than in the western US. Mesh sizes varied among programs but 80.2% of the methods used a mesh size between 500 and 600 (mu or u)m. Mesh size variations within US Environmental Protection Agency regions were large, with size differences ranging from 100 to 700 (mu or u)m. Most samples collected were composites; the mean area sampled was 1.7 m2. Samples rarely were collected using a random method (4.7%); most samples (70.6%) were collected using "expert opinion", which may make data obtained operator-specific. Only 26.3% of the methods sorted all the organisms from a sample; the remainder subsampled in the laboratory. The most common method of subsampling was to remove 100 organisms (range = 100-550). The magnification used for sorting ranged from 1 (sorting by eye) to 30x, which results in inconsistent separation of macroinvertebrates from detritus. In addition to subsampling, 53% of the methods sorted large/rare organisms from a sample. The taxonomic level used for identifying organisms varied among taxa; Ephemeroptera, Plecoptera, and Trichoptera were generally identified to a finer taxonomic resolution (genus and species) than other taxa. Because there currently exists a large range of field and laboratory methods used by state programs, calibration among all programs to increase data comparability would be exceptionally challenging. However, because many techniques are shared among methods, limited testing could be designed to evaluate whether procedural differences affect the ability to determine levels of environmental impairment using benthic macroinvertebrate communities.

A Multilevel, Hierarchical Sampling Technique for Spatially Correlated Random Fields

DOE PAGES

Osborn, Sarah; Vassilevski, Panayot S.; Villa, Umberto

2017-10-26

In this paper, we propose an alternative method to generate samples of a spatially correlated random field with applications to large-scale problems for forward propagation of uncertainty. A classical approach for generating these samples is the Karhunen--Loève (KL) decomposition. However, the KL expansion requires solving a dense eigenvalue problem and is therefore computationally infeasible for large-scale problems. Sampling methods based on stochastic partial differential equations provide a highly scalable way to sample Gaussian fields, but the resulting parametrization is mesh dependent. We propose a multilevel decomposition of the stochastic field to allow for scalable, hierarchical sampling based on solving amore » mixed finite element formulation of a stochastic reaction-diffusion equation with a random, white noise source function. Lastly, numerical experiments are presented to demonstrate the scalability of the sampling method as well as numerical results of multilevel Monte Carlo simulations for a subsurface porous media flow application using the proposed sampling method.« less

A Multilevel, Hierarchical Sampling Technique for Spatially Correlated Random Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osborn, Sarah; Vassilevski, Panayot S.; Villa, Umberto

In this paper, we propose an alternative method to generate samples of a spatially correlated random field with applications to large-scale problems for forward propagation of uncertainty. A classical approach for generating these samples is the Karhunen--Loève (KL) decomposition. However, the KL expansion requires solving a dense eigenvalue problem and is therefore computationally infeasible for large-scale problems. Sampling methods based on stochastic partial differential equations provide a highly scalable way to sample Gaussian fields, but the resulting parametrization is mesh dependent. We propose a multilevel decomposition of the stochastic field to allow for scalable, hierarchical sampling based on solving amore » mixed finite element formulation of a stochastic reaction-diffusion equation with a random, white noise source function. Lastly, numerical experiments are presented to demonstrate the scalability of the sampling method as well as numerical results of multilevel Monte Carlo simulations for a subsurface porous media flow application using the proposed sampling method.« less

Least squares polynomial chaos expansion: A review of sampling strategies

NASA Astrophysics Data System (ADS)

Hadigol, Mohammad; Doostan, Alireza

2018-04-01

As non-institutive polynomial chaos expansion (PCE) techniques have gained growing popularity among researchers, we here provide a comprehensive review of major sampling strategies for the least squares based PCE. Traditional sampling methods, such as Monte Carlo, Latin hypercube, quasi-Monte Carlo, optimal design of experiments (ODE), Gaussian quadratures, as well as more recent techniques, such as coherence-optimal and randomized quadratures are discussed. We also propose a hybrid sampling method, dubbed alphabetic-coherence-optimal, that employs the so-called alphabetic optimality criteria used in the context of ODE in conjunction with coherence-optimal samples. A comparison between the empirical performance of the selected sampling methods applied to three numerical examples, including high-order PCE's, high-dimensional problems, and low oversampling ratios, is presented to provide a road map for practitioners seeking the most suitable sampling technique for a problem at hand. We observed that the alphabetic-coherence-optimal technique outperforms other sampling methods, specially when high-order ODE are employed and/or the oversampling ratio is low.

Densitometry By Acoustic Levitation

NASA Technical Reports Server (NTRS)

Trinh, Eugene H.

1989-01-01

"Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

Mixture and method for simulating soiling and weathering of surfaces

DOEpatents

Sleiman, Mohamad; Kirchstetter, Thomas; Destaillats, Hugo; Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem

2018-01-02

This disclosure provides systems, methods, and apparatus related to simulated soiling and weathering of materials. In one aspect, a soiling mixture may include an aqueous suspension of various amounts of salt, soot, dust, and humic acid. In another aspect, a method may include weathering a sample of material in a first exposure of the sample to ultraviolet light, water vapor, and elevated temperatures, depositing a soiling mixture on the sample, and weathering the sample in a second exposure of the sample to ultraviolet light, water vapor, and elevated temperatures.

Study on Big Database Construction and its Application of Sample Data Collected in CHINA'S First National Geographic Conditions Census Based on Remote Sensing Images

NASA Astrophysics Data System (ADS)

Cheng, T.; Zhou, X.; Jia, Y.; Yang, G.; Bai, J.

2018-04-01

In the project of China's First National Geographic Conditions Census, millions of sample data have been collected all over the country for interpreting land cover based on remote sensing images, the quantity of data files reaches more than 12,000,000 and has grown in the following project of National Geographic Conditions Monitoring. By now, using database such as Oracle for storing the big data is the most effective method. However, applicable method is more significant for sample data's management and application. This paper studies a database construction method which is based on relational database with distributed file system. The vector data and file data are saved in different physical location. The key issues and solution method are discussed. Based on this, it studies the application method of sample data and analyzes some kinds of using cases, which could lay the foundation for sample data's application. Particularly, sample data locating in Shaanxi province are selected for verifying the method. At the same time, it takes 10 first-level classes which defined in the land cover classification system for example, and analyzes the spatial distribution and density characteristics of all kinds of sample data. The results verify that the method of database construction which is based on relational database with distributed file system is very useful and applicative for sample data's searching, analyzing and promoted application. Furthermore, sample data collected in the project of China's First National Geographic Conditions Census could be useful in the earth observation and land cover's quality assessment.

Air and Surface Sampling Method for Assessing Exposures to Quaternary Ammonium Compounds Using Liquid Chromatography Tandem Mass Spectrometry.

PubMed

LeBouf, Ryan F; Virji, Mohammed Abbas; Ranpara, Anand; Stefaniak, Aleksandr B

2017-07-01

This method was designed for sampling select quaternary ammonium (quat) compounds in air or on surfaces followed by analysis using ultraperformance liquid chromatography tandem mass spectrometry. Target quats were benzethonium chloride, didecyldimethylammonium bromide, benzyldimethyldodecylammonium chloride, benzyldimethyltetradecylammonium chloride, and benzyldimethylhexadecylammonium chloride. For air sampling, polytetrafluoroethylene (PTFE) filters are recommended for 15-min to 24-hour sampling. For surface sampling, Pro-wipe® 880 (PW) media was chosen. Samples were extracted in 60:40 acetonitrile:0.1% formic acid for 1 hour on an orbital shaker. Method detection limits range from 0.3 to 2 ng/ml depending on media and analyte. Matrix effects of media are minimized through the use of multiple reaction monitoring versus selected ion recording. Upper confidence limits on accuracy meet the National Institute for Occupational Safety and Health 25% criterion for PTFE and PW media for all analytes. Using PTFE and PW analyzed with multiple reaction monitoring, the method quantifies levels among the different quats compounds with high precision (<10% relative standard deviation) and low bias (<11%). The method is sensitive enough with very low method detection limits to capture quats on air sampling filters with only a 15-min sample duration with a maximum assessed storage time of 103 days before sample extraction. This method will support future exposure assessment and quantitative epidemiologic studies to explore exposure-response relationships and establish levels of quats exposures associated with adverse health effects. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

A two-dimensional matrix image based feature extraction method for classification of sEMG: A comparative analysis based on SVM, KNN and RBF-NN.

PubMed

Wen, Tingxi; Zhang, Zhongnan; Qiu, Ming; Zeng, Ming; Luo, Weizhen

2017-01-01

The computer mouse is an important human-computer interaction device. But patients with physical finger disability are unable to operate this device. Surface EMG (sEMG) can be monitored by electrodes on the skin surface and is a reflection of the neuromuscular activities. Therefore, we can control limbs auxiliary equipment by utilizing sEMG classification in order to help the physically disabled patients to operate the mouse. To develop a new a method to extract sEMG generated by finger motion and apply novel features to classify sEMG. A window-based data acquisition method was presented to extract signal samples from sEMG electordes. Afterwards, a two-dimensional matrix image based feature extraction method, which differs from the classical methods based on time domain or frequency domain, was employed to transform signal samples to feature maps used for classification. In the experiments, sEMG data samples produced by the index and middle fingers at the click of a mouse button were separately acquired. Then, characteristics of the samples were analyzed to generate a feature map for each sample. Finally, the machine learning classification algorithms (SVM, KNN, RBF-NN) were employed to classify these feature maps on a GPU. The study demonstrated that all classifiers can identify and classify sEMG samples effectively. In particular, the accuracy of the SVM classifier reached up to 100%. The signal separation method is a convenient, efficient and quick method, which can effectively extract the sEMG samples produced by fingers. In addition, unlike the classical methods, the new method enables to extract features by enlarging sample signals' energy appropriately. The classical machine learning classifiers all performed well by using these features.

Comparative Evaluation of Three Homogenization Methods for Isolating Middle East Respiratory Syndrome Coronavirus Nucleic Acids From Sputum Samples for Real-Time Reverse Transcription PCR.

PubMed

Sung, Heungsup; Yong, Dongeun; Ki, Chang Seok; Kim, Jae Seok; Seong, Moon Woo; Lee, Hyukmin; Kim, Mi Na

2016-09-01

Real-time reverse transcription PCR (rRT-PCR) of sputum samples is commonly used to diagnose Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Owing to the difficulty of extracting RNA from sputum containing mucus, sputum homogenization is desirable prior to nucleic acid isolation. We determined optimal homogenization methods for isolating viral nucleic acids from sputum. We evaluated the following three sputum-homogenization methods: proteinase K and DNase I (PK-DNase) treatment, phosphate-buffered saline (PBS) treatment, and N-acetyl-L-cysteine and sodium citrate (NALC) treatment. Sputum samples were spiked with inactivated MERS-CoV culture isolates. RNA was extracted from pretreated, spiked samples using the easyMAG system (bioMérieux, France). Extracted RNAs were then subjected to rRT-PCR for MERS-CoV diagnosis (DiaPlex Q MERS-coronavirus, SolGent, Korea). While analyzing 15 spiked sputum samples prepared in technical duplicate, false-negative results were obtained with five (16.7%) and four samples (13.3%), respectively, by using the PBS and NALC methods. The range of threshold cycle (Ct) values observed when detecting upE in sputum samples was 31.1-35.4 with the PK-DNase method, 34.7-39.0 with the PBS method, and 33.9-38.6 with the NALC method. Compared with the control, which were prepared by adding a one-tenth volume of 1:1,000 diluted viral culture to PBS solution, the ranges of Ct values obtained by the PBS and NALC methods differed significantly from the mean control Ct of 33.2 (both P<0.0001). The PK-DNase method is suitable for homogenizing sputum samples prior to RNA extraction.

The PneuCarriage Project: A Multi-Centre Comparative Study to Identify the Best Serotyping Methods for Examining Pneumococcal Carriage in Vaccine Evaluation Studies

PubMed Central

Satzke, Catherine; Dunne, Eileen M.; Porter, Barbara D.; Klugman, Keith P.; Mulholland, E. Kim

2015-01-01

Background The pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies. Methods and Findings Reference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample). For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included. Conclusions Most methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high. PMID:26575033

Field efficiency and bias of snag inventory methods

Treesearch

Robert S. Kenning; Mark J. Ducey; John C. Brissette; Jeffery H. Gove

2005-01-01

Snags and cavity trees are important components of forests, but can be difficult to inventory precisely and are not always included in inventories because of limited resources. We tested the application of N-tree distance sampling as a time-saving snag sampling method and compared N-tree distance sampling to fixed-area sampling and modified horizontal line sampling in...

40 CFR 761.292 - Chemical extraction and analysis of individual samples and composite samples.

Code of Federal Regulations, 2011 CFR

2011-07-01

... individual samples and composite samples. 761.292 Section 761.292 Protection of Environment ENVIRONMENTAL... Cleanup and On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761... individual and composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated...

40 CFR 761.292 - Chemical extraction and analysis of individual samples and composite samples.

Code of Federal Regulations, 2013 CFR

2013-07-01

... individual samples and composite samples. 761.292 Section 761.292 Protection of Environment ENVIRONMENTAL... Cleanup and On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761... individual and composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated...

40 CFR 761.292 - Chemical extraction and analysis of individual samples and composite samples.

Code of Federal Regulations, 2014 CFR

2014-07-01

... individual samples and composite samples. 761.292 Section 761.292 Protection of Environment ENVIRONMENTAL... Cleanup and On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761... individual and composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated...

40 CFR 761.292 - Chemical extraction and analysis of individual samples and composite samples.

Code of Federal Regulations, 2012 CFR

2012-07-01

... individual samples and composite samples. 761.292 Section 761.292 Protection of Environment ENVIRONMENTAL... Cleanup and On-Site Disposal of Bulk PCB Remediation Waste and Porous Surfaces in Accordance With § 761... individual and composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated...

Sampling Operations on Big Data

DTIC Science & Technology

2015-11-29

gories. These include edge sampling methods where edges are selected by a predetermined criteria; snowball sampling methods where algorithms start... Sampling Operations on Big Data Vijay Gadepally, Taylor Herr, Luke Johnson, Lauren Milechin, Maja Milosavljevic, Benjamin A. Miller Lincoln...process and disseminate information for discovery and exploration under real-time constraints. Common signal processing operations such as sampling and

Improved sampling and analysis of images in corneal confocal microscopy.

PubMed

Schaldemose, E L; Fontain, F I; Karlsson, P; Nyengaard, J R

2017-10-01

Corneal confocal microscopy (CCM) is a noninvasive clinical method to analyse and quantify corneal nerve fibres in vivo. Although the CCM technique is in constant progress, there are methodological limitations in terms of sampling of images and objectivity of the nerve quantification. The aim of this study was to present a randomized sampling method of the CCM images and to develop an adjusted area-dependent image analysis. Furthermore, a manual nerve fibre analysis method was compared to a fully automated method. 23 idiopathic small-fibre neuropathy patients were investigated using CCM. Corneal nerve fibre length density (CNFL) and corneal nerve fibre branch density (CNBD) were determined in both a manual and automatic manner. Differences in CNFL and CNBD between (1) the randomized and the most common sampling method, (2) the adjusted and the unadjusted area and (3) the manual and automated quantification method were investigated. The CNFL values were significantly lower when using the randomized sampling method compared to the most common method (p = 0.01). There was not a statistical significant difference in the CNBD values between the randomized and the most common sampling method (p = 0.85). CNFL and CNBD values were increased when using the adjusted area compared to the standard area. Additionally, the study found a significant increase in the CNFL and CNBD values when using the manual method compared to the automatic method (p ≤ 0.001). The study demonstrated a significant difference in the CNFL values between the randomized and common sampling method indicating the importance of clear guidelines for the image sampling. The increase in CNFL and CNBD values when using the adjusted cornea area is not surprising. The observed increases in both CNFL and CNBD values when using the manual method of nerve quantification compared to the automatic method are consistent with earlier findings. This study underlines the importance of improving the analysis of the CCM images in order to obtain more objective corneal nerve fibre measurements. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Potential artifacts associated with historical preparation of joint compound samples and reported airborne asbestos concentrations.

PubMed

Brorby, G P; Sheehan, P J; Berman, D W; Bogen, K T; Holm, S E

2011-05-01

Airborne samples collected in the 1970s for drywall workers using asbestos-containing joint compounds were likely prepared and analyzed according to National Institute of Occupational Safety and Health Method P&CAM 239, the historical precursor to current Method 7400. Experimentation with a re-created, chrysotile-containing, carbonate-based joint compound suggested that analysis following sample preparation by the historical vs. current method produces different fiber counts, likely because of an interaction between the different clearing and mounting chemicals used and the carbonate-based joint compound matrix. Differences were also observed during analysis using Method 7402, depending on whether acetic acid/dimethylformamide or acetone was used during preparation to collapse the filter. Specifically, air samples of sanded chrysotile-containing joint compound prepared by the historical method yielded fiber counts significantly greater (average of 1.7-fold, 95% confidence interval: 1.5- to 2.0-fold) than those obtained by the current method. In addition, air samples prepared by Method 7402 using acetic acid/dimethylformamide yielded fiber counts that were greater (2.8-fold, 95% confidence interval: 2.5- to 3.2-fold) than those prepared by this method using acetone. These results indicated (1) there is an interaction between Method P&CAM 239 preparation chemicals and the carbonate-based joint compound matrix that reveals fibers that were previously bound in the matrix, and (2) the same appeared to be true for Method 7402 preparation chemicals acetic acid/dimethylformamide. This difference in fiber counts is the opposite of what has been reported historically for samples of relatively pure chrysotile dusts prepared using the same chemicals. This preparation artifact should be considered when interpreting historical air samples for drywall workers prepared by Method P&CAM 239. Copyright © 2011 JOEH, LLC

Establishing Statistical Equivalence of Data from Different Sampling Approaches for Assessment of Bacterial Phenotypic Antimicrobial Resistance

PubMed Central

2018-01-01

ABSTRACT To assess phenotypic bacterial antimicrobial resistance (AMR) in different strata (e.g., host populations, environmental areas, manure, or sewage effluents) for epidemiological purposes, isolates of target bacteria can be obtained from a stratum using various sample types. Also, different sample processing methods can be applied. The MIC of each target antimicrobial drug for each isolate is measured. Statistical equivalence testing of the MIC data for the isolates allows evaluation of whether different sample types or sample processing methods yield equivalent estimates of the bacterial antimicrobial susceptibility in the stratum. We demonstrate this approach on the antimicrobial susceptibility estimates for (i) nontyphoidal Salmonella spp. from ground or trimmed meat versus cecal content samples of cattle in processing plants in 2013-2014 and (ii) nontyphoidal Salmonella spp. from urine, fecal, and blood human samples in 2015 (U.S. National Antimicrobial Resistance Monitoring System data). We found that the sample types for cattle yielded nonequivalent susceptibility estimates for several antimicrobial drug classes and thus may gauge distinct subpopulations of salmonellae. The quinolone and fluoroquinolone susceptibility estimates for nontyphoidal salmonellae from human blood are nonequivalent to those from urine or feces, conjecturally due to the fluoroquinolone (ciprofloxacin) use to treat infections caused by nontyphoidal salmonellae. We also demonstrate statistical equivalence testing for comparing sample processing methods for fecal samples (culturing one versus multiple aliquots per sample) to assess AMR in fecal Escherichia coli. These methods yield equivalent results, except for tetracyclines. Importantly, statistical equivalence testing provides the MIC difference at which the data from two sample types or sample processing methods differ statistically. Data users (e.g., microbiologists and epidemiologists) may then interpret practical relevance of the difference. IMPORTANCE Bacterial antimicrobial resistance (AMR) needs to be assessed in different populations or strata for the purposes of surveillance and determination of the efficacy of interventions to halt AMR dissemination. To assess phenotypic antimicrobial susceptibility, isolates of target bacteria can be obtained from a stratum using different sample types or employing different sample processing methods in the laboratory. The MIC of each target antimicrobial drug for each of the isolates is measured, yielding the MIC distribution across the isolates from each sample type or sample processing method. We describe statistical equivalence testing for the MIC data for evaluating whether two sample types or sample processing methods yield equivalent estimates of the bacterial phenotypic antimicrobial susceptibility in the stratum. This includes estimating the MIC difference at which the data from the two approaches differ statistically. Data users (e.g., microbiologists, epidemiologists, and public health professionals) can then interpret whether that present difference is practically relevant. PMID:29475868

Establishing Statistical Equivalence of Data from Different Sampling Approaches for Assessment of Bacterial Phenotypic Antimicrobial Resistance.

PubMed

Shakeri, Heman; Volkova, Victoriya; Wen, Xuesong; Deters, Andrea; Cull, Charley; Drouillard, James; Müller, Christian; Moradijamei, Behnaz; Jaberi-Douraki, Majid

2018-05-01

To assess phenotypic bacterial antimicrobial resistance (AMR) in different strata (e.g., host populations, environmental areas, manure, or sewage effluents) for epidemiological purposes, isolates of target bacteria can be obtained from a stratum using various sample types. Also, different sample processing methods can be applied. The MIC of each target antimicrobial drug for each isolate is measured. Statistical equivalence testing of the MIC data for the isolates allows evaluation of whether different sample types or sample processing methods yield equivalent estimates of the bacterial antimicrobial susceptibility in the stratum. We demonstrate this approach on the antimicrobial susceptibility estimates for (i) nontyphoidal Salmonella spp. from ground or trimmed meat versus cecal content samples of cattle in processing plants in 2013-2014 and (ii) nontyphoidal Salmonella spp. from urine, fecal, and blood human samples in 2015 (U.S. National Antimicrobial Resistance Monitoring System data). We found that the sample types for cattle yielded nonequivalent susceptibility estimates for several antimicrobial drug classes and thus may gauge distinct subpopulations of salmonellae. The quinolone and fluoroquinolone susceptibility estimates for nontyphoidal salmonellae from human blood are nonequivalent to those from urine or feces, conjecturally due to the fluoroquinolone (ciprofloxacin) use to treat infections caused by nontyphoidal salmonellae. We also demonstrate statistical equivalence testing for comparing sample processing methods for fecal samples (culturing one versus multiple aliquots per sample) to assess AMR in fecal Escherichia coli These methods yield equivalent results, except for tetracyclines. Importantly, statistical equivalence testing provides the MIC difference at which the data from two sample types or sample processing methods differ statistically. Data users (e.g., microbiologists and epidemiologists) may then interpret practical relevance of the difference. IMPORTANCE Bacterial antimicrobial resistance (AMR) needs to be assessed in different populations or strata for the purposes of surveillance and determination of the efficacy of interventions to halt AMR dissemination. To assess phenotypic antimicrobial susceptibility, isolates of target bacteria can be obtained from a stratum using different sample types or employing different sample processing methods in the laboratory. The MIC of each target antimicrobial drug for each of the isolates is measured, yielding the MIC distribution across the isolates from each sample type or sample processing method. We describe statistical equivalence testing for the MIC data for evaluating whether two sample types or sample processing methods yield equivalent estimates of the bacterial phenotypic antimicrobial susceptibility in the stratum. This includes estimating the MIC difference at which the data from the two approaches differ statistically. Data users (e.g., microbiologists, epidemiologists, and public health professionals) can then interpret whether that present difference is practically relevant. Copyright © 2018 Shakeri et al.

Modified Sample Preparation Approach for the Determination of the Phenolic and Humic-Like Substances in Natural Organic Materials By the Folin Ciocalteu Method.

PubMed

Pontoni, Ludovico; Panico, Antonio; Matanò, Alessia; van Hullebusch, Eric D; Fabbricino, Massimiliano; Esposito, Giovanni; Pirozzi, Francesco

2017-12-06

A novel modification of the sample preparation procedure for the Folin-Ciocalteu colorimetric assay for the determination of total phenolic compounds in natural solid and semisolid organic materials (e.g., foods, organic solid waste, soils, plant tissues, agricultural residues, manure) is proposed. In this method, the sample is prepared by adding sodium sulfate as a solid diluting agent before homogenization. The method allows for the determination of total phenols (TP) in samples with high solids contents, and it provides good accuracy and reproducibility. Additionally, this method permits analyses of significant amounts of sample, which reduces problems related to heterogeneity. We applied this method to phenols-rich lignocellulosic and humic-like solids and semisolid samples, including rice straw (RS), peat-rich soil (PS), and food waste (FW). The TP concentrations measured with the solid dilution (SD) preparation were substantially higher (increases of 41.4%, 15.5%, and 59.4% in RS, PS and FW, respectively) than those obtained with the traditional method (solids suspended in water). These results showed that the traditional method underestimates the phenolic contents in the studied solids.

Comparison of Clark's presence-absence test and the membrane filter method for coliform detection in potable water samples.

PubMed Central

Pipes, W O; Minnigh, H A; Moyer, B; Troy, M A

1986-01-01

A total of 2,601 water samples from six different water systems were tested for coliform bacteria by Clark's presence-absence (P-A) test and by the membrane filter (MF) method. There was no significant difference in the fraction of samples positive for coliform bacteria for any of the systems tested. It was concluded that the two tests are equivalent for monitoring purposes. However, 152 samples were positive for coliform bacteria by the MF method but negative by the P-A test, and 132 samples were positive by the P-A test but negative by the MF method. Many of these differences for individual samples can be explained by random dispersion of bacteria in subsamples when the coliform density is low. However, 15 samples had MF counts greater than 3 and gave negative P-A results. The only apparent explanation for most of these results is that coliform bacteria were present in the P-A test bottles but did not produce acid and gas. Two other studies have reported more samples positive by Clark's P-A test than by the MF method. PMID:3532953

Investigating Test Equating Methods in Small Samples through Various Factors

ERIC Educational Resources Information Center

Asiret, Semih; Sünbül, Seçil Ömür

2016-01-01

In this study, equating methods for random group design using small samples through factors such as sample size, difference in difficulty between forms, and guessing parameter was aimed for comparison. Moreover, which method gives better results under which conditions was also investigated. In this study, 5,000 dichotomous simulated data…

Biomass Compositional Analysis Laboratory Procedures | Bioenergy | NREL

Science.gov Websites

Compositional Analysis This procedure describes methods for sample drying and size reduction, obtaining samples methods used to determine the amount of solids or moisture present in a solid or slurry biomass sample as values? We have found that neutral detergent fiber (NDF) and acid detergent fiber (ADF) methods report

Sampling Methods and the Accredited Population in Athletic Training Education Research

ERIC Educational Resources Information Center

Carr, W. David; Volberding, Jennifer

2009-01-01

Context: We describe methods of sampling the widely-studied, yet poorly defined, population of accredited athletic training education programs (ATEPs). Objective: There are two purposes to this study; first to describe the incidence and types of sampling methods used in athletic training education research, and second to clearly define the…

A LITERATURE REVIEW OF WIPE SAMPLING METHODS FOR CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS

EPA Science Inventory

Wipe sampling is an important technique for the estimation of contaminant deposition in buildings, homes, or outdoor surfaces as a source of possible human exposure. Numerous

methods of wipe sampling exist, and each method has its own specification for the type of wipe, we...

Comparison of no-purge and pumped sampling methods for monitoring concentrations of ordnance-related compounds in groundwater, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts, 2009-2010

USGS Publications Warehouse

Savoie, Jennifer G.; LeBlanc, Denis R.

2012-01-01

Field tests were conducted near the Impact Area at Camp Edwards on the Massachusetts Military Reservation, Cape Cod, Massachusetts, to determine the utility of no-purge groundwater sampling for monitoring concentrations of ordnance-related explosive compounds and perchlorate in the sand and gravel aquifer. The no-purge methods included (1) a diffusion sampler constructed of rigid porous polyethylene, (2) a diffusion sampler constructed of regenerated-cellulose membrane, and (3) a tubular grab sampler (bailer) constructed of polyethylene film. In samples from 36 monitoring wells, concentrations of perchlorate (ClO4-), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), the major contaminants of concern in the Impact Area, in the no-purge samples were compared to concentrations of these compounds in samples collected by low-flow pumped sampling with dedicated bladder pumps. The monitoring wells are constructed of 2- and 2.5-inch-diameter polyvinyl chloride pipe and have approximately 5- to 10-foot-long slotted screens. The no-purge samplers were left in place for 13-64 days to ensure that ambient groundwater flow had flushed the well screen and concentrations in the screen represented water in the adjacent formation. The sampling methods were compared first in six monitoring wells. Concentrations of ClO4-, RDX, and HMX in water samples collected by the three no-purge sampling methods and low-flow pumped sampling were in close agreement for all six monitoring wells. There is no evidence of a systematic bias in the concentration differences among the methods on the basis of type of sampling device, type of contaminant, or order in which the no-purge samplers were tested. A subsequent examination of vertical variations in concentrations of ClO4- in the 10-foot-long screens of six wells by using rigid porous polyethylene diffusion samplers indicated that concentrations in a given well varied by less than 15 percent and the small variations were unlikely to affect the utility of the various sampling methods. The grab sampler was selected for additional tests in 29 of the 36 monitoring wells used during the study. Concentrations of ClO4-, RDX, HMX, and other minor explosive compounds in water samples collected by using a 1-liter grab sampler and low-flow pumped sampling were in close agreement in field tests in the 29 wells. A statistical analysis based on the sign test indicated that there was no bias in the concentration differences between the methods. There also was no evidence for a systematic bias in concentration differences between the methods related to location of the monitoring wells laterally or vertically in the groundwater-flow system. Field tests in five wells also demonstrated that sample collection by using a 2-liter grab sampler and sequential bailing with the 1-liter grab sampler were options for obtaining sufficient sample volume for replicate and spiked quality assurance and control samples. The evidence from the field tests supports the conclusion that diffusion sampling with the rigid porous polyethylene and regenerated-cellulose membranes and grab sampling with the polyethylene-film samplers provide comparable data on the concentrations of ordnance-related compounds in groundwater at the MMR to that obtained by low-flow pumped sampling. These sampling methods are useful methods for monitoring these compounds at the MMR and in similar hydrogeologic environments.

Validation sampling can reduce bias in healthcare database studies: an illustration using influenza vaccination effectiveness

PubMed Central

Nelson, Jennifer C.; Marsh, Tracey; Lumley, Thomas; Larson, Eric B.; Jackson, Lisa A.; Jackson, Michael

2014-01-01

Objective Estimates of treatment effectiveness in epidemiologic studies using large observational health care databases may be biased due to inaccurate or incomplete information on important confounders. Study methods that collect and incorporate more comprehensive confounder data on a validation cohort may reduce confounding bias. Study Design and Setting We applied two such methods, imputation and reweighting, to Group Health administrative data (full sample) supplemented by more detailed confounder data from the Adult Changes in Thought study (validation sample). We used influenza vaccination effectiveness (with an unexposed comparator group) as an example and evaluated each method’s ability to reduce bias using the control time period prior to influenza circulation. Results Both methods reduced, but did not completely eliminate, the bias compared with traditional effectiveness estimates that do not utilize the validation sample confounders. Conclusion Although these results support the use of validation sampling methods to improve the accuracy of comparative effectiveness findings from healthcare database studies, they also illustrate that the success of such methods depends on many factors, including the ability to measure important confounders in a representative and large enough validation sample, the comparability of the full sample and validation sample, and the accuracy with which data can be imputed or reweighted using the additional validation sample information. PMID:23849144

Sparse feature learning for instrument identification: Effects of sampling and pooling methods.

PubMed

Han, Yoonchang; Lee, Subin; Nam, Juhan; Lee, Kyogu

2016-05-01

Feature learning for music applications has recently received considerable attention from many researchers. This paper reports on the sparse feature learning algorithm for musical instrument identification, and in particular, focuses on the effects of the frame sampling techniques for dictionary learning and the pooling methods for feature aggregation. To this end, two frame sampling techniques are examined that are fixed and proportional random sampling. Furthermore, the effect of using onset frame was analyzed for both of proposed sampling methods. Regarding summarization of the feature activation, a standard deviation pooling method is used and compared with the commonly used max- and average-pooling techniques. Using more than 47 000 recordings of 24 instruments from various performers, playing styles, and dynamics, a number of tuning parameters are experimented including the analysis frame size, the dictionary size, and the type of frequency scaling as well as the different sampling and pooling methods. The results show that the combination of proportional sampling and standard deviation pooling achieve the best overall performance of 95.62% while the optimal parameter set varies among the instrument classes.

Comparison of methods for determination of total oil sands-derived naphthenic acids in water samples.

PubMed

Hughes, Sarah A; Huang, Rongfu; Mahaffey, Ashley; Chelme-Ayala, Pamela; Klamerth, Nikolaus; Meshref, Mohamed N A; Ibrahim, Mohamed D; Brown, Christine; Peru, Kerry M; Headley, John V; Gamal El-Din, Mohamed

2017-11-01

There are several established methods for the determination of naphthenic acids (NAs) in waters associated with oil sands mining operations. Due to their highly complex nature, measured concentration and composition of NAs vary depending on the method used. This study compared different common sample preparation techniques, analytical instrument methods, and analytical standards to measure NAs in groundwater and process water samples collected from an active oil sands operation. In general, the high- and ultrahigh-resolution methods, namely high performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) and Orbitrap mass spectrometry (Orbitrap-MS), were within an order of magnitude of the Fourier transform infrared spectroscopy (FTIR) methods. The gas chromatography mass spectrometry (GC-MS) methods consistently had the highest NA concentrations and greatest standard error. Total NAs concentration was not statistically different between sample preparation of solid phase extraction and liquid-liquid extraction. Calibration standards influenced quantitation results. This work provided a comprehensive understanding of the inherent differences in the various techniques available to measure NAs and hence the potential differences in measured amounts of NAs in samples. Results from this study will contribute to the analytical method standardization for NA analysis in oil sands related water samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

An integrated bioanalytical method development and validation approach: case studies.

PubMed

Xue, Y-J; Melo, Brian; Vallejo, Martha; Zhao, Yuwen; Tang, Lina; Chen, Yuan-Shek; Keller, Karin M

2012-10-01

We proposed an integrated bioanalytical method development and validation approach: (1) method screening based on analyte's physicochemical properties and metabolism information to determine the most appropriate extraction/analysis conditions; (2) preliminary stability evaluation using both quality control and incurred samples to establish sample collection, storage and processing conditions; (3) mock validation to examine method accuracy and precision and incurred sample reproducibility; and (4) method validation to confirm the results obtained during method development. This integrated approach was applied to the determination of compound I in rat plasma and compound II in rat and dog plasma. The effectiveness of the approach was demonstrated by the superior quality of three method validations: (1) a zero run failure rate; (2) >93% of quality control results within 10% of nominal values; and (3) 99% incurred sample within 9.2% of the original values. In addition, rat and dog plasma methods for compound II were successfully applied to analyze more than 900 plasma samples obtained from Investigational New Drug (IND) toxicology studies in rats and dogs with near perfect results: (1) a zero run failure rate; (2) excellent accuracy and precision for standards and quality controls; and (3) 98% incurred samples within 15% of the original values. Copyright © 2011 John Wiley & Sons, Ltd.

Drinking water test methods in crisis-afflicted areas: comparison of methods under field conditions.

PubMed

Merle, Roswitha; Bleul, Ingo; Schulenburg, Jörg; Kreienbrock, Lothar; Klein, Günter

2011-11-01

To simplify the testing of drinking water in crisis-afflicted areas (as in Kosovo in 2007), rapid test methods were compared with the standard test. For Escherichia coli and coliform pathogens, rapid tests were made available: Colilert(®)-18, P/A test with 4-methylumbelliferyl-β-D-glucoronid, and m-Endo Broth. Biochemical differentiation was carried out by Enterotube™ II. Enterococci were determined following the standard ISO test and by means of Enterolert™. Four hundred ninety-nine water samples were tested for E. coli and coliforms using four methods. Following the standard method, 20.8% (n=104) of the samples contained E. coli, whereas the rapid tests detected between 19.6% (m-Endo Broth, 92.0% concordance) and 20.0% (concordance: 93.6% Colilert-18 and 94.8% P/A-test) positive samples. Regarding coliforms, the percentage of concordant results ranged from 98.4% (P/A-test) to 99.0% (Colilert-18). Colilert-18 and m-Endo Broth detected even more positive samples than the standard method did. Enterococci were detected in 93 of 573 samples by the standard method, but in 92 samples by Enterolert (concordance: 99.5%). Considering the high-quality equipment and time requirements of the standard method, the use of rapid tests in crisis-afflicted areas is sufficiently reliable.

Digital simulation of scalar optical diffraction: revisiting chirp function sampling criteria and consequences.

PubMed

Voelz, David G; Roggemann, Michael C

2009-11-10

Accurate simulation of scalar optical diffraction requires consideration of the sampling requirement for the phase chirp function that appears in the Fresnel diffraction expression. We describe three sampling regimes for FFT-based propagation approaches: ideally sampled, oversampled, and undersampled. Ideal sampling, where the chirp and its FFT both have values that match analytic chirp expressions, usually provides the most accurate results but can be difficult to realize in practical simulations. Under- or oversampling leads to a reduction in the available source plane support size, the available source bandwidth, or the available observation support size, depending on the approach and simulation scenario. We discuss three Fresnel propagation approaches: the impulse response/transfer function (angular spectrum) method, the single FFT (direct) method, and the two-step method. With illustrations and simulation examples we show the form of the sampled chirp functions and their discrete transforms, common relationships between the three methods under ideal sampling conditions, and define conditions and consequences to be considered when using nonideal sampling. The analysis is extended to describe the sampling limitations for the more exact Rayleigh-Sommerfeld diffraction solution.

A fast learning method for large scale and multi-class samples of SVM

NASA Astrophysics Data System (ADS)

Fan, Yu; Guo, Huiming

2017-06-01

A multi-class classification SVM(Support Vector Machine) fast learning method based on binary tree is presented to solve its low learning efficiency when SVM processing large scale multi-class samples. This paper adopts bottom-up method to set up binary tree hierarchy structure, according to achieved hierarchy structure, sub-classifier learns from corresponding samples of each node. During the learning, several class clusters are generated after the first clustering of the training samples. Firstly, central points are extracted from those class clusters which just have one type of samples. For those which have two types of samples, cluster numbers of their positive and negative samples are set respectively according to their mixture degree, secondary clustering undertaken afterwards, after which, central points are extracted from achieved sub-class clusters. By learning from the reduced samples formed by the integration of extracted central points above, sub-classifiers are obtained. Simulation experiment shows that, this fast learning method, which is based on multi-level clustering, can guarantee higher classification accuracy, greatly reduce sample numbers and effectively improve learning efficiency.

Evaluation of direct saponification method for determination of cholesterol in meats.

PubMed

Adams, M L; Sullivan, D M; Smith, R L; Richter, E F

1986-01-01

A gas chromatographic (GC) method has been developed for determination of cholesterol in meats. The method involves ethanolic KOH saponification of the sample material, homogeneous-phase toluene extraction of the unsaponifiables, derivatization of cholesterol to its trimethylsilylether, and quantitation by GC-flame ionization detection using 5-alpha-cholestane as internal standard. This direct saponification method is compared with the current AOAC official method for determination of cholesterol in 20 different meat products. The direct saponification method eliminates the need for initial lipid extraction, thus offering a 30% savings in labor, and requires fewer solvents than the AOAC method. It produced comparable or slightly higher cholesterol results than the AOAC method in all meat samples examined. Precision, determined by assaying a turkey meat sample 16 times over 4 days, was excellent (CV = 1.74%). Average recovery of cholesterol added to meat samples was 99.8%.

Mixed Methods Sampling: A Typology with Examples

ERIC Educational Resources Information Center

Teddlie, Charles; Yu, Fen

2007-01-01

This article presents a discussion of mixed methods (MM) sampling techniques. MM sampling involves combining well-established qualitative and quantitative techniques in creative ways to answer research questions posed by MM research designs. Several issues germane to MM sampling are presented including the differences between probability and…

40 CFR 761.272 - Chemical extraction and analysis of samples.

Code of Federal Regulations, 2012 CFR

2012-07-01

... samples. 761.272 Section 761.272 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in... composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated under subpart...

40 CFR 761.272 - Chemical extraction and analysis of samples.

Code of Federal Regulations, 2011 CFR

2011-07-01

... samples. 761.272 Section 761.272 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in... composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated under subpart...

40 CFR 761.272 - Chemical extraction and analysis of samples.

Code of Federal Regulations, 2013 CFR

2013-07-01

... samples. 761.272 Section 761.272 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in... composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated under subpart...

40 CFR 761.272 - Chemical extraction and analysis of samples.

Code of Federal Regulations, 2014 CFR

2014-07-01

... samples. 761.272 Section 761.272 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in... composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated under subpart...

The PneuCarriage Project: A Multi-Centre Comparative Study to Identify the Best Serotyping Methods for Examining Pneumococcal Carriage in Vaccine Evaluation Studies.

PubMed

Satzke, Catherine; Dunne, Eileen M; Porter, Barbara D; Klugman, Keith P; Mulholland, E Kim

2015-11-01

The pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies. Reference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample). For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included. Most methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high.

Comparative evaluation of two methods of enumerating enterococci in foods: collaborative study.

PubMed

Peterz, M; Steneryd, A C

1993-05-01

Two methods of enumerating enterococci in foods were compared in a collaborative study. Thirteen laboratories tested four blind duplicate samples containing different levels of enterococci and two negative control samples. Freeze-dried mixtures of bacteria were used as simulated food samples. The freeze-dried samples were reconstituted and either spread directly on the surface of Slanetz and Bartley medium (SB) and incubated at 44 degrees C for 48 h or preincubated in tryptone soya agar at 37 degrees C for 2 h before being overlaid by SB and incubated at 37 degrees C for a further 46 h. The numbers CFU of enterococci recovered by the two methods were not significantly different except for one sample where the 37 degrees C method gave a somewhat higher recovery. The 44 degrees C method was less time-consuming and less laborious.

Estimating the sample mean and standard deviation from the sample size, median, range and/or interquartile range.

PubMed

Wan, Xiang; Wang, Wenqian; Liu, Jiming; Tong, Tiejun

2014-12-19

In systematic reviews and meta-analysis, researchers often pool the results of the sample mean and standard deviation from a set of similar clinical trials. A number of the trials, however, reported the study using the median, the minimum and maximum values, and/or the first and third quartiles. Hence, in order to combine results, one may have to estimate the sample mean and standard deviation for such trials. In this paper, we propose to improve the existing literature in several directions. First, we show that the sample standard deviation estimation in Hozo et al.'s method (BMC Med Res Methodol 5:13, 2005) has some serious limitations and is always less satisfactory in practice. Inspired by this, we propose a new estimation method by incorporating the sample size. Second, we systematically study the sample mean and standard deviation estimation problem under several other interesting settings where the interquartile range is also available for the trials. We demonstrate the performance of the proposed methods through simulation studies for the three frequently encountered scenarios, respectively. For the first two scenarios, our method greatly improves existing methods and provides a nearly unbiased estimate of the true sample standard deviation for normal data and a slightly biased estimate for skewed data. For the third scenario, our method still performs very well for both normal data and skewed data. Furthermore, we compare the estimators of the sample mean and standard deviation under all three scenarios and present some suggestions on which scenario is preferred in real-world applications. In this paper, we discuss different approximation methods in the estimation of the sample mean and standard deviation and propose some new estimation methods to improve the existing literature. We conclude our work with a summary table (an Excel spread sheet including all formulas) that serves as a comprehensive guidance for performing meta-analysis in different situations.

Comparative analysis of a modified ecolite method, the colicomplete method, and a most-probable-number method for detecting Escherichia coli in orange juice.

PubMed

Durbin, Gregory W; Salter, Robert

2006-01-01

The Ecolite High Volume Juice (HVJ) presence-absence method for a 10-ml juice sample was compared with the U.S. Food and Drug Administration Bacteriological Analytical Manual most-probable-number (MPN) method for analysis of artificially contaminated orange juices. Samples were added to Ecolite-HVJ medium and incubated at 35 degrees C for 24 to 48 h. Fluorescent blue results were positive for glucuronidase- and galactosidase-producing microorganisms, specifically indicative of about 94% of Escherichia coli strains. Four strains of E. coli were added to juices at concentrations of 0.21 to 6.8 CFU/ ml. Mixtures of enteric bacteria (Enterobacter plus Klebsiella, Citrobacter plus Proteus, or Hafnia plus Citrobacter plus Enterobacter) were added to simulate background flora. Three orange juice types were evaluated (n = 10) with and without the addition of the E. coli strains. Ecolite-HVJ produced 90 of 90 (10 of 10 samples of three juice types, each inoculated with three different E. coli strains) positive (blue-fluorescent) results with artificially contaminated E. coli that had MPN concentrations of <0.3 to 9.3 CFU/ml. Ten of 30 E. coli ATCC 11229 samples with MPN concentrations of <0.3 CFU/ml were identified as positive with Ecolite-HVJ. Isolated colonies recovered from positive Ecolite-HVJ samples were confirmed biochemically as E. coli. Thirty (10 samples each of three juice types) negative (not fluorescent) results were obtained for samples contaminated with only enteric bacteria and for uninoculated control samples. A juice manufacturer evaluated citrus juice production with both the Ecolite-HVJ and Colicomplete methods and recorded identical negative results for 95 20-ml samples and identical positive results for 5 20-ml samples artificially contaminated with E. coli. The Ecolite-HVJ method requires no preenrichment and subsequent transfer steps, which makes it a simple and easy method for use by juice producers.

Determination of Oebalus pugnax (Hemiptera: Pentatomidae) spatial pattern in rice and development of visual sampling methods and population sampling plans.

PubMed

Espino, L; Way, M O; Wilson, L T

2008-02-01

Commercial rice, Oryza sativa L., fields in southeastern Texas were sampled during 2003 and 2004, and visual samples were compared with sweep net samples. Fields were sampled at different stages of panicle development, times of day, and by different operators. Significant differences were found between perimeter and within field sweep net samples, indicating that samples taken 9 m from the field margin overestimate within field Oebalus pugnax (F.) (Hemiptera: Pentatomidae) populations. Time of day did not significantly affect the number of O. pugnax caught with the sweep net; however, there was a trend to capture more insects during morning than afternoon. For all sampling methods evaluated during this study, O. pugnax was found to have an aggregated spatial pattern at most densities. When comparing sweep net with visual sampling methods, one sweep of the "long stick" and two sweeps of the "sweep stick" correlated well with the sweep net (r2 = 0.639 and r2 = 0.815, respectively). This relationship was not affected by time of day of sampling, stage of panicle development, type of planting or operator. Relative cost-reliability, which incorporates probability of adoption, indicates the visual methods are more cost-reliable than the sweep net for sampling O.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; in-bottle acid digestion of whole-water samples

USGS Publications Warehouse

Hoffman, G.L.; Fishman, M. J.; Garbarino, J.R.

1996-01-01

Water samples for trace-metal determinations routinely have been prepared in open laboratories. For example, the U.S. Geological Survey method I-3485-85 (Extraction Procedure, for Water- Suspended Sediment) is performed in a laboratory hood on a laboratory bench without any special precautions to control airborne contamination. This method tends to be contamination prone for several trace metals primarily because the samples are transferred, acidified, digested, and filtered in an open laboratory environment. To reduce trace-metal contamination of digested water samples, procedures were established that rely on minimizing sample-transfer steps and using a class-100 clean bench during sample filtration. This new procedure involves the following steps: 1. The sample is acidified with HCl directly in the original water-sample bottle. 2. The water-sample bottle with the cap secured is heated in a laboratory oven. 3. The digestate is filtered in a class-100 laminar-flow clean bench. The exact conditions used (that is, oven temperature, time of heating, and filtration methods) for this digestion procedure are described. Comparisons between the previous U.S Geological Survey open-beaker method I-3485-85 and the new in-bottle procedure for synthetic and field-collected water samples are given. When the new procedure is used, blank concentrations for most trace metals determined are reduced significantly.

Sampling and Pooling Methods for Capturing Herd Level Antibiotic Resistance in Swine Feces using qPCR and CFU Approaches

PubMed Central

Mellerup, Anders; Ståhl, Marie

2015-01-01

The aim of this article was to define the sampling level and method combination that captures antibiotic resistance at pig herd level utilizing qPCR antibiotic resistance gene quantification and culture-based quantification of antibiotic resistant coliform indicator bacteria. Fourteen qPCR assays for commonly detected antibiotic resistance genes were developed, and used to quantify antibiotic resistance genes in total DNA from swine fecal samples that were obtained using different sampling and pooling methods. In parallel, the number of antibiotic resistant coliform indicator bacteria was determined in the same swine fecal samples. The results showed that the qPCR assays were capable of detecting differences in antibiotic resistance levels in individual animals that the coliform bacteria colony forming units (CFU) could not. Also, the qPCR assays more accurately quantified antibiotic resistance genes when comparing individual sampling and pooling methods. qPCR on pooled samples was found to be a good representative for the general resistance level in a pig herd compared to the coliform CFU counts. It had significantly reduced relative standard deviations compared to coliform CFU counts in the same samples, and therefore differences in antibiotic resistance levels between samples were more readily detected. To our knowledge, this is the first study to describe sampling and pooling methods for qPCR quantification of antibiotic resistance genes in total DNA extracted from swine feces. PMID:26114765

Development and evaluation of an enzyme-linked immunosorbent assay (ELISA) method for the measurement of 2,4-dichlorophenoxyacetic acid in human urine.

PubMed

Chuang, Jane C; Emon, Jeanette M Van; Durnford, Joyce; Thomas, Kent

2005-09-15

An enzyme-linked immunosorbent assay (ELISA) method was developed to quantitatively measure 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine. Samples were diluted (1:5) with phosphate-buffered saline containing 0.05% Tween and 0.02% sodium azide, with analysis by a 96-microwell plate immunoassay format. No clean up was required as dilution step minimized sample interferences. Fifty urine samples were received without identifiers from a subset of pesticide applicators and their spouses in an EPA pesticide exposure study (PES) and analyzed by the ELISA method and a conventional gas chromatography/mass spectrometry (GC/MS) procedure. For the GC/MS analysis, urine samples were extracted with acidic dichloromethane (DCM); methylated by diazomethane and fractionated by a Florisil solid phase extraction (SPE) column prior to GC/MS detection. The percent relative standard deviation (%R.S.D.) of the 96-microwell plate triplicate assays ranged from 1.2 to 22% for the urine samples. Day-to-day variation of the assay results was within +/-20%. Quantitative recoveries (>70%) of 2,4-D were obtained for the spiked urine samples by the ELISA method. Quantitative recoveries (>80%) of 2,4-D were also obtained for these samples by the GC/MS procedure. The overall method precision of these samples was within +/-20% for both the ELISA and GC/MS methods. The estimated quantification limit for 2,4-D in urine was 30ng/mL by ELISA and 0.2ng/mL by GC/MS. A higher quantification limit for the ELISA method is partly due to the requirement of a 1:5 dilution to remove the urine sample matrix effect. The GC/MS method can accommodate a 10:1 concentration factor (10mL of urine converted into 1mL organic solvent for analysis) but requires extraction, methylation and clean up on a solid phase column. The immunoassay and GC/MS data were highly correlated, with a correlation coefficient of 0.94 and a slope of 1.00. Favorable results between the two methods were achieved despite the vast differences in sample preparation. Results indicated that the ELISA method could be used as a high throughput, quantitative monitoring tool for human urine samples to identify individuals with exposure to 2,4-D above the typical background levels.

The efficacy of respondent-driven sampling for the health assessment of minority populations.

PubMed

Badowski, Grazyna; Somera, Lilnabeth P; Simsiman, Brayan; Lee, Hye-Ryeon; Cassel, Kevin; Yamanaka, Alisha; Ren, JunHao

2017-10-01

Respondent driven sampling (RDS) is a relatively new network sampling technique typically employed for hard-to-reach populations. Like snowball sampling, initial respondents or "seeds" recruit additional respondents from their network of friends. Under certain assumptions, the method promises to produce a sample independent from the biases that may have been introduced by the non-random choice of "seeds." We conducted a survey on health communication in Guam's general population using the RDS method, the first survey that has utilized this methodology in Guam. It was conducted in hopes of identifying a cost-efficient non-probability sampling strategy that could generate reasonable population estimates for both minority and general populations. RDS data was collected in Guam in 2013 (n=511) and population estimates were compared with 2012 BRFSS data (n=2031) and the 2010 census data. The estimates were calculated using the unweighted RDS sample and the weighted sample using RDS inference methods and compared with known population characteristics. The sample size was reached in 23days, providing evidence that the RDS method is a viable, cost-effective data collection method, which can provide reasonable population estimates. However, the results also suggest that the RDS inference methods used to reduce bias, based on self-reported estimates of network sizes, may not always work. Caution is needed when interpreting RDS study findings. For a more diverse sample, data collection should not be conducted in just one location. Fewer questions about network estimates should be asked, and more careful consideration should be given to the kind of incentives offered to participants. Copyright © 2017. Published by Elsevier Ltd.

An atomic-absorption method for the determination of gold in large samples of geologic materials

USGS Publications Warehouse

VanSickle, Gordon H.; Lakin, Hubert William

1968-01-01

A laboratory method for the determination of gold in large (100-gram) samples has been developed for use in the study of the gold content of placer deposits and of trace amounts of gold in other geologic materials. In this method the sample is digested with bromine and ethyl ether, the gold is extracted into methyl isobutyl ketone, and the determination is made by atomicabsorption spectrophotometry. The lower limit of detection is 0.005 part per million in the sample. The few data obtained so far by this method agree favorably with those obtained by assay and by other atomic-absorption methods. About 25 determinations can be made per man-day.

Multi-laboratory survey of qPCR enterococci analysis method performance

EPA Pesticide Factsheets

Quantitative polymerase chain reaction (qPCR) has become a frequently used technique for quantifying enterococci in recreational surface waters, but there are several methodological options. Here we evaluated how three method permutations, type of mastermix, sample extract dilution and use of controls in results calculation, affect method reliability among multiple laboratories with respect to sample interference. Multiple samples from each of 22 sites representing an array of habitat types were analyzed using EPA Method 1611 and 1609 reagents with full strength and five-fold diluted extracts. The presence of interference was assessed three ways: using sample processing and PCR amplifications controls; consistency of results across extract dilutions; and relative recovery of target genes from spiked enterococci in water sample compared to control matrices with acceptable recovery defined as 50 to 200%. Method 1609, which is based on an environmental mastermix, was found to be superior to Method 1611, which is based on a universal mastermix. Method 1611 had over a 40% control assay failure rate with undiluted extracts and a 6% failure rate with diluted extracts. Method 1609 failed in only 11% and 3% of undiluted and diluted extracts analyses. Use of sample processing control assay results in the delta-delta Ct method for calculating relative target gene recoveries increased the number of acceptable recovery results. Delta-delta tended to bias recoveries fr

40 CFR 761.272 - Chemical extraction and analysis of samples.

Code of Federal Regulations, 2010 CFR

2010-07-01

... COMMERCE, AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in... composite samples of PCB remediation waste. Use Method 8082 from SW-846, or a method validated under subpart...

A review of empirical research related to the use of small quantitative samples in clinical outcome scale development.

PubMed

Houts, Carrie R; Edwards, Michael C; Wirth, R J; Deal, Linda S

2016-11-01

There has been a notable increase in the advocacy of using small-sample designs as an initial quantitative assessment of item and scale performance during the scale development process. This is particularly true in the development of clinical outcome assessments (COAs), where Rasch analysis has been advanced as an appropriate statistical tool for evaluating the developing COAs using a small sample. We review the benefits such methods are purported to offer from both a practical and statistical standpoint and detail several problematic areas, including both practical and statistical theory concerns, with respect to the use of quantitative methods, including Rasch-consistent methods, with small samples. The feasibility of obtaining accurate information and the potential negative impacts of misusing large-sample statistical methods with small samples during COA development are discussed.

Liquid-Based Medium Used to Prepare Cytological Breast Nipple Fluid Improves the Quality of Cellular Samples Automatic Collection

PubMed Central

Zonta, Marco Antonio; Velame, Fernanda; Gema, Samara; Filassi, Jose Roberto; Longatto-Filho, Adhemar

2014-01-01

Background Breast cancer is the second cause of death in women worldwide. The spontaneous breast nipple discharge may contain cells that can be analyzed for malignancy. Halo® Mamo Cyto Test (HMCT) was recently developed as an automated system indicated to aspirate cells from the breast ducts. The objective of this study was to standardize the methodology of sampling and sample preparation of nipple discharge obtained by the automated method Halo breast test and perform cytological evaluation in samples preserved in liquid medium (SurePath™). Methods We analyzed 564 nipple fluid samples, from women between 20 and 85 years old, without history of breast disease and neoplasia, no pregnancy, and without gynecologic medical history, collected by HMCT method and preserved in two different vials with solutions for transport. Results From 306 nipple fluid samples from method 1, 199 (65%) were classified as unsatisfactory (class 0), 104 (34%) samples were classified as benign findings (class II), and three (1%) were classified as undetermined to neoplastic cells (class III). From 258 samples analyzed in method 2, 127 (49%) were classified as class 0, 124 (48%) were classified as class II, and seven (2%) were classified as class III. Conclusion Our study suggests an improvement in the quality and quantity of cellular samples when the association of the two methodologies is performed, Halo breast test and the method in liquid medium. PMID:29147397

La 2-xSr xCuO 4-δ superconducting samples prepared by the wet-chemical method

NASA Astrophysics Data System (ADS)

Loose, A.; Gonzalez, J. L.; Lopez, A.; Borges, H. A.; Baggio-Saitovitch, E.

2009-10-01

In this work, we report on the physical properties of good-quality polycrystalline superconducting samples of La 2-xSr xCu 1-yZn yO 4-δ ( y=0, 0.02) prepared by a wet-chemical method, focusing on the temperature dependence of the critical current. Using the wet-chemical method, we were able to produce samples with improved homogeneity compared to the solid-state method. A complete set of samples with several carrier concentrations, ranging from the underdoped (strontium concentration x≈0.05) to the highly overdoped ( x≈0.25) region, were prepared and investigated. The X-ray diffraction analysis, zero-field cooling magnetization and electrical resistivity measurements were reported on earlier. The structural parameters of the prepared samples seem to be slightly modified by the preparation method and their critical temperatures were lower than reported in the literature. The temperature dependence of the critical current was explained by a theoretical model which took the granular structure of the samples into account.

Correcting for Sample Contamination in Genotype Calling of DNA Sequence Data

PubMed Central

Flickinger, Matthew; Jun, Goo; Abecasis, Gonçalo R.; Boehnke, Michael; Kang, Hyun Min

2015-01-01

DNA sample contamination is a frequent problem in DNA sequencing studies and can result in genotyping errors and reduced power for association testing. We recently described methods to identify within-species DNA sample contamination based on sequencing read data, showed that our methods can reliably detect and estimate contamination levels as low as 1%, and suggested strategies to identify and remove contaminated samples from sequencing studies. Here we propose methods to model contamination during genotype calling as an alternative to removal of contaminated samples from further analyses. We compare our contamination-adjusted calls to calls that ignore contamination and to calls based on uncontaminated data. We demonstrate that, for moderate contamination levels (5%–20%), contamination-adjusted calls eliminate 48%–77% of the genotyping errors. For lower levels of contamination, our contamination correction methods produce genotypes nearly as accurate as those based on uncontaminated data. Our contamination correction methods are useful generally, but are particularly helpful for sample contamination levels from 2% to 20%. PMID:26235984

Flagging versus dragging as sampling methods for nymphal Ixodes scapularis (Acari: Ixodidae)

USGS Publications Warehouse

Rulison, Eric L.; Kuczaj, Isis; Pang, Genevieve; Hickling, Graham J.; Tsao, Jean I.; Ginsberg, Howard S.

2013-01-01

The nymphal stage of the blacklegged tick, Ixodes scapularis (Acari: Ixodidae), is responsible for most transmission of Borrelia burgdorferi, the etiologic agent of Lyme disease, to humans in North America. From 2010 to fall of 2012, we compared two commonly used techniques, flagging and dragging, as sampling methods for nymphal I. scapularis at three sites, each with multiple sampling arrays (grids), in the eastern and central United States. Flagging and dragging collected comparable numbers of nymphs, with no consistent differences between methods. Dragging collected more nymphs than flagging in some samples, but these differences were not consistent among sites or sampling years. The ratio of nymphs collected by flagging vs dragging was not significantly related to shrub density, so habitat type did not have a strong effect on the relative efficacy of these methods. Therefore, although dragging collected more ticks in a few cases, the numbers collected by each method were so variable that neither technique had a clear advantage for sampling nymphal I. scapularis.

Fluidics platform and method for sample preparation

DOEpatents

Benner, Henry W.; Dzenitis, John M.

2016-06-21

Provided herein are fluidics platforms and related methods for performing integrated sample collection and solid-phase extraction of a target component of the sample all in one tube. The fluidics platform comprises a pump, particles for solid-phase extraction and a particle-holding means. The method comprises contacting the sample with one or more reagents in a pump, coupling a particle-holding means to the pump and expelling the waste out of the pump while the particle-holding means retains the particles inside the pump. The fluidics platform and methods herein described allow solid-phase extraction without pipetting and centrifugation.

Sampling Based Influence Maximization on Linear Threshold Model

NASA Astrophysics Data System (ADS)

Jia, Su; Chen, Ling

2018-04-01

A sampling based influence maximization on linear threshold (LT) model method is presented. The method samples the routes in the possible worlds in the social networks, and uses Chernoff bound to estimate the number of samples so that the error can be constrained within a given bound. Then the active possibilities of the routes in the possible worlds are calculated, and are used to compute the influence spread of each node in the network. Our experimental results show that our method can effectively select appropriate seed nodes set that spreads larger influence than other similar methods.

Reflexion on linear regression trip production modelling method for ensuring good model quality

NASA Astrophysics Data System (ADS)

Suprayitno, Hitapriya; Ratnasari, Vita

2017-11-01

Transport Modelling is important. For certain cases, the conventional model still has to be used, in which having a good trip production model is capital. A good model can only be obtained from a good sample. Two of the basic principles of a good sampling is having a sample capable to represent the population characteristics and capable to produce an acceptable error at a certain confidence level. It seems that this principle is not yet quite understood and used in trip production modeling. Therefore, investigating the Trip Production Modelling practice in Indonesia and try to formulate a better modeling method for ensuring the Model Quality is necessary. This research result is presented as follows. Statistics knows a method to calculate span of prediction value at a certain confidence level for linear regression, which is called Confidence Interval of Predicted Value. The common modeling practice uses R2 as the principal quality measure, the sampling practice varies and not always conform to the sampling principles. An experiment indicates that small sample is already capable to give excellent R2 value and sample composition can significantly change the model. Hence, good R2 value, in fact, does not always mean good model quality. These lead to three basic ideas for ensuring good model quality, i.e. reformulating quality measure, calculation procedure, and sampling method. A quality measure is defined as having a good R2 value and a good Confidence Interval of Predicted Value. Calculation procedure must incorporate statistical calculation method and appropriate statistical tests needed. A good sampling method must incorporate random well distributed stratified sampling with a certain minimum number of samples. These three ideas need to be more developed and tested.

A simple modification of the Baermann method for diagnosis of strongyloidiasis.

PubMed

Hernández-Chavarría, F; Avendaño, L

2001-08-01

The diagnosis of Strongyloides stercoralis infections is routinely made by microscopic observation of larvae in stool samples, a low sensitivity method, or by other, most effective methods, such as the Baermann or agar culture plate methods. We propose in this paper a practical modification of Baermann method. One hundred and six stool samples from alcoholic patients were analyzed using the direct smear test, agar culture plate method, the standard Baermann method, and its proposed modification. For this modification the funnel used in the original version of the method is substituted by a test tube with a rubber stopper, perforated to allow insertion of a pipette tip. The tube with a fecal suspension is inverted over another tube containing 6 ml of saline solution and incubated at 37 degrees C for at least 2 h. The saline solution from the second tube is centrifuged and the pellet is observed microscopically. Larva of S. stercoralis were detected in six samples (5.7%) by the two versions of the Baermann method. Five samples were positive using the agar culture plate method, and only in two samples the larva were observed using direct microscopic observation of fecal smears. Cysts of Endolimax nana and Entamoeba histolytica/dyspar were also detected in the modification of Baermann method. Data obtained by the modified Baermann method suggest that this methodology may helps concentrate larvae of S. stercoralis as efficiently as the original method.

Phytoforensics—Using trees to find contamination

USGS Publications Warehouse

Wilson, Jordan L.

2017-09-28

The water we drink, air we breathe, and soil we come into contact with have the potential to adversely affect our health because of contaminants in the environment. Environmental samples can characterize the extent of potential contamination, but traditional methods for collecting water, air, and soil samples below the ground (for example, well drilling or direct-push soil sampling) are expensive and time consuming. Trees are closely connected to the subsurface and sampling tree trunks can indicate subsurface pollutants, a process called phytoforensics. Scientists at the Missouri Water Science Center were among the first to use phytoforensics to screen sites for contamination before using traditional sampling methods, to guide additional sampling, and to show the large cost savings associated with tree sampling compared to traditional methods. 

Exploring high dimensional free energy landscapes: Temperature accelerated sliced sampling

NASA Astrophysics Data System (ADS)

Awasthi, Shalini; Nair, Nisanth N.

2017-03-01

Biased sampling of collective variables is widely used to accelerate rare events in molecular simulations and to explore free energy surfaces. However, computational efficiency of these methods decreases with increasing number of collective variables, which severely limits the predictive power of the enhanced sampling approaches. Here we propose a method called Temperature Accelerated Sliced Sampling (TASS) that combines temperature accelerated molecular dynamics with umbrella sampling and metadynamics to sample the collective variable space in an efficient manner. The presented method can sample a large number of collective variables and is advantageous for controlled exploration of broad and unbound free energy basins. TASS is also shown to achieve quick free energy convergence and is practically usable with ab initio molecular dynamics techniques.

Quantitative Evaluation of Hard X-ray Damage to Biological Samples using EUV Ptychography

NASA Astrophysics Data System (ADS)

Baksh, Peter; Odstrcil, Michal; Parsons, Aaron; Bailey, Jo; Deinhardt, Katrin; Chad, John E.; Brocklesby, William S.; Frey, Jeremy G.

2017-06-01

Coherent diffractive imaging (CDI) has become a standard method on a variety of synchrotron beam lines. The high brilliance short wavelength radiation from these sources can be used to reconstruct attenuation and relative phase of a sample with nanometre resolution via CDI methods. However, the interaction between the sample and high energy ionising radiation can cause degradation to sample structure. We demonstrate, using a laboratory based high harmonic generation (HHG) based extreme ultraviolet (EUV) source, imaging a sample of hippocampal neurons using the ptychography method. The significant increase in contrast of the sample in the EUV light allows identification of damage induced from exposure to 7.3 keV photons, without causing any damage to the sample itself.

Small Body GN and C Research Report: G-SAMPLE - An In-Flight Dynamical Method for Identifying Sample Mass [External Release Version

NASA Technical Reports Server (NTRS)

Carson, John M., III; Bayard, David S.

2006-01-01

G-SAMPLE is an in-flight dynamical method for use by sample collection missions to identify the presence and quantity of collected sample material. The G-SAMPLE method implements a maximum-likelihood estimator to identify the collected sample mass, based on onboard force sensor measurements, thruster firings, and a dynamics model of the spacecraft. With G-SAMPLE, sample mass identification becomes a computation rather than an extra hardware requirement; the added cost of cameras or other sensors for sample mass detection is avoided. Realistic simulation examples are provided for a spacecraft configuration with a sample collection device mounted on the end of an extended boom. In one representative example, a 1000 gram sample mass is estimated to within 110 grams (95% confidence) under realistic assumptions of thruster profile error, spacecraft parameter uncertainty, and sensor noise. For convenience to future mission design, an overall sample-mass estimation error budget is developed to approximate the effect of model uncertainty, sensor noise, data rate, and thrust profile error on the expected estimate of collected sample mass.

Moment and maximum likelihood estimators for Weibull distributions under length- and area-biased sampling

Treesearch

Jeffrey H. Gove

2003-01-01

Many of the most popular sampling schemes used in forestry are probability proportional to size methods. These methods are also referred to as size biased because sampling is actually from a weighted form of the underlying population distribution. Length- and area-biased sampling are special cases of size-biased sampling where the probability weighting comes from a...

Molecular detection of Toxoplasma gondii in water samples from Scotland and a comparison between the 529bp real-time PCR and ITS1 nested PCR.

PubMed

Wells, Beth; Shaw, Hannah; Innocent, Giles; Guido, Stefano; Hotchkiss, Emily; Parigi, Maria; Opsteegh, Marieke; Green, James; Gillespie, Simon; Innes, Elisabeth A; Katzer, Frank

2015-12-15

Waterborne transmission of Toxoplasma gondii is a potential public health risk and there are currently no agreed optimised methods for the recovery, processing and detection of T. gondii oocysts in water samples. In this study modified methods of T. gondii oocyst recovery and DNA extraction were applied to 1427 samples collected from 147 public water supplies throughout Scotland. T. gondii DNA was detected, using real time PCR (qPCR) targeting the 529bp repeat element, in 8.79% of interpretable samples (124 out of 1411 samples). The samples which were positive for T. gondii DNA originated from a third of the sampled water sources. The samples which were positive by qPCR and some of the negative samples were reanalysed using ITS1 nested PCR (nPCR) and results compared. The 529bp qPCR was the more sensitive technique and a full analysis of assay performance, by Bayesian analysis using a Markov Chain Monte Carlo method, was completed which demonstrated the efficacy of this method for the detection of T. gondii in water samples. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Multilattice sampling strategies for region of interest dynamic MRI.

PubMed

Rilling, Gabriel; Tao, Yuehui; Marshall, Ian; Davies, Mike E

2013-08-01

A multilattice sampling approach is proposed for dynamic MRI with Cartesian trajectories. It relies on the use of sampling patterns composed of several different lattices and exploits an image model where only some parts of the image are dynamic, whereas the rest is assumed static. Given the parameters of such an image model, the methodology followed for the design of a multilattice sampling pattern adapted to the model is described. The multi-lattice approach is compared to single-lattice sampling, as used by traditional acceleration methods such as UNFOLD (UNaliasing by Fourier-Encoding the Overlaps using the temporal Dimension) or k-t BLAST, and random sampling used by modern compressed sensing-based methods. On the considered image model, it allows more flexibility and higher accelerations than lattice sampling and better performance than random sampling. The method is illustrated on a phase-contrast carotid blood velocity mapping MR experiment. Combining the multilattice approach with the KEYHOLE technique allows up to 12× acceleration factors. Simulation and in vivo undersampling results validate the method. Compared to lattice and random sampling, multilattice sampling provides significant gains at high acceleration factors. © 2012 Wiley Periodicals, Inc.

Sampling strategies for estimating brook trout effective population size

Treesearch

Andrew R. Whiteley; Jason A. Coombs; Mark Hudy; Zachary Robinson; Keith H. Nislow; Benjamin H. Letcher

2012-01-01

The influence of sampling strategy on estimates of effective population size (Ne) from single-sample genetic methods has not been rigorously examined, though these methods are increasingly used. For headwater salmonids, spatially close kin association among age-0 individuals suggests that sampling strategy (number of individuals and location from...

40 CFR 761.289 - Compositing samples.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.289 Compositing samples. Compositing is a method of combining several samples of a specific type of bulk PCB remediation waste or... compositing bulk PCB remediation waste samples. These procedures are based on the method for selecting...

40 CFR 761.289 - Compositing samples.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Remediation Waste and Porous Surfaces in Accordance With § 761.61(a)(6) § 761.289 Compositing samples. Compositing is a method of combining several samples of a specific type of bulk PCB remediation waste or... compositing bulk PCB remediation waste samples. These procedures are based on the method for selecting...

Robust gene selection methods using weighting schemes for microarray data analysis.

PubMed

Kang, Suyeon; Song, Jongwoo

2017-09-02

A common task in microarray data analysis is to identify informative genes that are differentially expressed between two different states. Owing to the high-dimensional nature of microarray data, identification of significant genes has been essential in analyzing the data. However, the performances of many gene selection techniques are highly dependent on the experimental conditions, such as the presence of measurement error or a limited number of sample replicates. We have proposed new filter-based gene selection techniques, by applying a simple modification to significance analysis of microarrays (SAM). To prove the effectiveness of the proposed method, we considered a series of synthetic datasets with different noise levels and sample sizes along with two real datasets. The following findings were made. First, our proposed methods outperform conventional methods for all simulation set-ups. In particular, our methods are much better when the given data are noisy and sample size is small. They showed relatively robust performance regardless of noise level and sample size, whereas the performance of SAM became significantly worse as the noise level became high or sample size decreased. When sufficient sample replicates were available, SAM and our methods showed similar performance. Finally, our proposed methods are competitive with traditional methods in classification tasks for microarrays. The results of simulation study and real data analysis have demonstrated that our proposed methods are effective for detecting significant genes and classification tasks, especially when the given data are noisy or have few sample replicates. By employing weighting schemes, we can obtain robust and reliable results for microarray data analysis.

Comparison of gel column, card, and cartridge techniques for dog erythrocyte antigen 1.1 blood typing

PubMed Central

Seth, Mayank; Jackson, Karen V.; Winzelberg, Sarah; Giger, Urs

2012-01-01

Objective To compare accuracy and ease of use of a card agglutination assay, an immunochromatographic cartridge method, and a gel-based method for canine blood typing. Sample Blood samples from 52 healthy blood donor dogs, 10 dogs with immune-mediated hemolytic anemia (IMHA), and 29 dogs with other diseases. Procedures Blood samples were tested in accordance with manufacturer guidelines. Samples with low PCVs were created by the addition of autologous plasma to separately assess the effects of anemia on test results. Results Compared with a composite reference standard of agreement between 2 methods, the gel-based method was found to be 100% accurate. The card agglutination assay was 89% to 91% accurate, depending on test interpretation, and the immunochromatographic cartridge method was 93% accurate but 100% specific. Errors were observed more frequently in samples from diseased dogs, particularly those with IMHA. In the presence of persistent autoagglutination, dog erythrocyte antigen (DEA) 1.1 typing was not possible, except with the immunochromatographic cartridge method. Conclusions and Clinical Relevance The card agglutination assay and immunochromatographic cartridge method, performed by trained personnel, were suitable for in-clinic emergency DEA 1.1 blood typing. There may be errors, particularly for samples from dogs with IMHA, and the immunochromatographic cartridge method may have an advantage of allowing typing of samples with persistent autoagglutination. The laboratory gel-based method would be preferred for routine DEA 1.1 typing of donors and patients if it is available and time permits. Current DEA 1.1 typing techniques appear to be appropriately standardized and easy to use. PMID:22280380

Rapid-viability PCR method for detection of live, virulent Bacillus anthracis in environmental samples.

PubMed

Létant, Sonia E; Murphy, Gloria A; Alfaro, Teneile M; Avila, Julie R; Kane, Staci R; Raber, Ellen; Bunt, Thomas M; Shah, Sanjiv R

2011-09-01

In the event of a biothreat agent release, hundreds of samples would need to be rapidly processed to characterize the extent of contamination and determine the efficacy of remediation activities. Current biological agent identification and viability determination methods are both labor- and time-intensive such that turnaround time for confirmed results is typically several days. In order to alleviate this issue, automated, high-throughput sample processing methods were developed in which real-time PCR analysis is conducted on samples before and after incubation. The method, referred to as rapid-viability (RV)-PCR, uses the change in cycle threshold after incubation to detect the presence of live organisms. In this article, we report a novel RV-PCR method for detection of live, virulent Bacillus anthracis, in which the incubation time was reduced from 14 h to 9 h, bringing the total turnaround time for results below 15 h. The method incorporates a magnetic bead-based DNA extraction and purification step prior to PCR analysis, as well as specific real-time PCR assays for the B. anthracis chromosome and pXO1 and pXO2 plasmids. A single laboratory verification of the optimized method applied to the detection of virulent B. anthracis in environmental samples was conducted and showed a detection level of 10 to 99 CFU/sample with both manual and automated RV-PCR methods in the presence of various challenges. Experiments exploring the relationship between the incubation time and the limit of detection suggest that the method could be further shortened by an additional 2 to 3 h for relatively clean samples.

Active Search on Carcasses versus Pitfall Traps: a Comparison of Sampling Methods.

PubMed

Zanetti, N I; Camina, R; Visciarelli, E C; Centeno, N D

2016-04-01

The study of insect succession in cadavers and the classification of arthropods have mostly been done by placing a carcass in a cage, protected from vertebrate scavengers, which is then visited periodically. An alternative is to use specific traps. Few studies on carrion ecology and forensic entomology involving the carcasses of large vertebrates have employed pitfall traps. The aims of this study were to compare both sampling methods (active search on a carcass and pitfall trapping) for each coleopteran family, and to establish whether there is a discrepancy (underestimation and/or overestimation) in the presence of each family by either method. A great discrepancy was found for almost all families with some of them being more abundant in samples obtained through active search on carcasses and others in samples from traps, whereas two families did not show any bias towards a given sampling method. The fact that families may be underestimated or overestimated by the type of sampling technique highlights the importance of combining both methods, active search on carcasses and pitfall traps, in order to obtain more complete information on decomposition, carrion habitat and cadaveric families or species. Furthermore, a hypothesis advanced on the reasons for the underestimation by either sampling method showing biases towards certain families. Information about the sampling techniques indicating which would be more appropriate to detect or find a particular family is provided.

Estimating the Effective Sample Size of Tree Topologies from Bayesian Phylogenetic Analyses

PubMed Central

Lanfear, Robert; Hua, Xia; Warren, Dan L.

2016-01-01

Bayesian phylogenetic analyses estimate posterior distributions of phylogenetic tree topologies and other parameters using Markov chain Monte Carlo (MCMC) methods. Before making inferences from these distributions, it is important to assess their adequacy. To this end, the effective sample size (ESS) estimates how many truly independent samples of a given parameter the output of the MCMC represents. The ESS of a parameter is frequently much lower than the number of samples taken from the MCMC because sequential samples from the chain can be non-independent due to autocorrelation. Typically, phylogeneticists use a rule of thumb that the ESS of all parameters should be greater than 200. However, we have no method to calculate an ESS of tree topology samples, despite the fact that the tree topology is often the parameter of primary interest and is almost always central to the estimation of other parameters. That is, we lack a method to determine whether we have adequately sampled one of the most important parameters in our analyses. In this study, we address this problem by developing methods to estimate the ESS for tree topologies. We combine these methods with two new diagnostic plots for assessing posterior samples of tree topologies, and compare their performance on simulated and empirical data sets. Combined, the methods we present provide new ways to assess the mixing and convergence of phylogenetic tree topologies in Bayesian MCMC analyses. PMID:27435794

Solid-phase extraction and GC-MS analysis of THC-COOH method optimized for a high-throughput forensic drug-testing laboratory.

PubMed

Stout, P R; Horn, C K; Klette, K L

2001-10-01

In order to facilitate the confirmation analysis of large numbers of urine samples previously screened positive for delta9-tetrahydrocannabinol (THC), an extraction, derivitization, and GC-MS analysis method was developed. This method utilized a positive pressure manifold anion-exchange polymer-based solid-phase extraction followed by elution directly into the automated liquid sampling (ALS) vials. Rapid derivitization was accomplished using pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFPOH). Recoveries averaged 95% with a limit of detection of 0.875 ng/mL with a 3-mL sample volume. Performance of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH)-d3 and THC-COOH-d9 internal standards were evaluated. The method was linear to 900 ng/mL THC-COOH using THC-COOH-d9 with negligible contribution from the internal standard to very weak samples. Excellent agreement was seen with previous quantitations of human urine samples. More than 1000 human urine samples were analyzed using the method with 300 samples analyzed using an alternate qualifier ion (m/z 622) after some interference was observed with a qualifier ion (m/z 489). The 622 ion did not exhibit any interference even in samples with interfering peaks present in the 489 ion. The method resulted in dramatic reductions in processing time, waste production, and exposure hazards to laboratory personnel.

A green analytical method using ultrasound in sample preparation for the flow injection determination of iron, manganese, and zinc in soluble solid samples by flame atomic absorption spectrometry.

PubMed

Yebra, M Carmen

2012-01-01

A simple and rapid analytical method was developed for the determination of iron, manganese, and zinc in soluble solid samples. The method is based on continuous ultrasonic water dissolution of the sample (5-30 mg) at room temperature followed by flow injection flame atomic absorption spectrometric determination. A good precision of the whole procedure (1.2-4.6%) and a sample throughput of ca. 25 samples h(-1) were obtained. The proposed green analytical method has been successfully applied for the determination of iron, manganese, and zinc in soluble solid food samples (soluble cocoa and soluble coffee) and pharmaceutical preparations (multivitamin tablets). The ranges of concentrations found were 21.4-25.61 μg g(-1) for iron, 5.74-18.30 μg g(-1) for manganese, and 33.27-57.90 μg g(-1) for zinc in soluble solid food samples and 3.75-9.90 μg g(-1) for iron, 0.47-5.05 μg g(-1) for manganese, and 1.55-15.12 μg g(-1) for zinc in multivitamin tablets. The accuracy of the proposed method was established by a comparison with the conventional wet acid digestion method using a paired t-test, indicating the absence of systematic errors.

Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust.

PubMed

Barone, T L; Patts, J R; Janisko, S J; Colinet, J F; Patts, L D; Beck, T W; Mischler, S E

2016-01-01

Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine.

Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust

PubMed Central

Barone, T. L.; Patts, J. R.; Janisko, S. J.; Colinet, J. F.; Patts, L. D.; Beck, T. W.; Mischler, S. E.

2016-01-01

Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine. PMID:26618374

Linear model correction: A method for transferring a near-infrared multivariate calibration model without standard samples.

PubMed

Liu, Yan; Cai, Wensheng; Shao, Xueguang

2016-12-05

Calibration transfer is essential for practical applications of near infrared (NIR) spectroscopy because the measurements of the spectra may be performed on different instruments and the difference between the instruments must be corrected. For most of calibration transfer methods, standard samples are necessary to construct the transfer model using the spectra of the samples measured on two instruments, named as master and slave instrument, respectively. In this work, a method named as linear model correction (LMC) is proposed for calibration transfer without standard samples. The method is based on the fact that, for the samples with similar physical and chemical properties, the spectra measured on different instruments are linearly correlated. The fact makes the coefficients of the linear models constructed by the spectra measured on different instruments are similar in profile. Therefore, by using the constrained optimization method, the coefficients of the master model can be transferred into that of the slave model with a few spectra measured on slave instrument. Two NIR datasets of corn and plant leaf samples measured with different instruments are used to test the performance of the method. The results show that, for both the datasets, the spectra can be correctly predicted using the transferred partial least squares (PLS) models. Because standard samples are not necessary in the method, it may be more useful in practical uses. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of active sampling strategies for the determination of 1,3-butadiene in air

NASA Astrophysics Data System (ADS)

Vallecillos, Laura; Maceira, Alba; Marcé, Rosa Maria; Borrull, Francesc

2018-03-01

Two analytical methods for determining levels of 1,3-butadiene in urban and industrial atmospheres were evaluated in this study. Both methods are extensively used for determining the concentration of volatile organic compounds in the atmosphere and involve collecting samples by active adsorptive enrichment on solid sorbents. The first method uses activated charcoal as the sorbent and involves liquid desorption with carbon disulfide. The second involves the use of a multi-sorbent bed with two graphitised carbons and a carbon molecular sieve as the sorbent, with thermal desorption. Special attention was paid to the optimization of the sampling procedure through the study of sample volume, the stability of 1,3-butadiene once inside the sampling tube and the humidity effect. In the end, the thermal desorption method showed better repeatability and limits of detection and quantification for 1,3-butadiene than the liquid desorption method, which makes the thermal desorption method more suitable for analysing air samples from both industrial and urban atmospheres. However, sampling must be performed with a pre-tube filled with a drying agent to prevent the loss of the adsorption capacity of the solid adsorbent caused by water vapour. The thermal desorption method has successfully been applied to determine of 1,3-butadiene inside a 1,3-butadiene production plant and at three locations in the vicinity of the same plant.

US Fish and Wildlife Service biomonitoring operations manual, Appendices A--K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianotto, D.F.; Rope, R.C.; Mondecar, M.

1993-04-01

Volume 2 contains Appendices and Summary Sheets for the following areas: A-Legislative Background and Key to Relevant Legislation, B- Biomonitoring Operations Workbook, C-Air Monitoring, D-Introduction to the Flora and Fauna for Biomonitoring, E-Decontamination Guidance Reference Field Methods, F-Documentation Guidance, Sample Handling, and Quality Assurance/Quality Control Standard Operating Procedures, G-Field Instrument Measurements Reference Field Methods, H-Ground Water Sampling Reference Field Methods, I-Sediment Sampling Reference Field Methods, J-Soil Sampling Reference Field Methods, K-Surface Water Reference Field Methods. Appendix B explains how to set up strategy to enter information on the ``disk workbook``. Appendix B is enhanced by DE97006389, an on-line workbook formore » users to be able to make revisions to their own biomonitoring data.« less

Self-adaptive enhanced sampling in the energy and trajectory spaces: accelerated thermodynamics and kinetic calculations.

PubMed

Gao, Yi Qin

2008-04-07

Here, we introduce a simple self-adaptive computational method to enhance the sampling in energy, configuration, and trajectory spaces. The method makes use of two strategies. It first uses a non-Boltzmann distribution method to enhance the sampling in the phase space, in particular, in the configuration space. The application of this method leads to a broad energy distribution in a large energy range and a quickly converged sampling of molecular configurations. In the second stage of simulations, the configuration space of the system is divided into a number of small regions according to preselected collective coordinates. An enhanced sampling of reactive transition paths is then performed in a self-adaptive fashion to accelerate kinetics calculations.

Integrating conventional and inverse representation for face recognition.

PubMed

Xu, Yong; Li, Xuelong; Yang, Jian; Lai, Zhihui; Zhang, David

2014-10-01

Representation-based classification methods are all constructed on the basis of the conventional representation, which first expresses the test sample as a linear combination of the training samples and then exploits the deviation between the test sample and the expression result of every class to perform classification. However, this deviation does not always well reflect the difference between the test sample and each class. With this paper, we propose a novel representation-based classification method for face recognition. This method integrates conventional and the inverse representation-based classification for better recognizing the face. It first produces conventional representation of the test sample, i.e., uses a linear combination of the training samples to represent the test sample. Then it obtains the inverse representation, i.e., provides an approximation representation of each training sample of a subject by exploiting the test sample and training samples of the other subjects. Finally, the proposed method exploits the conventional and inverse representation to generate two kinds of scores of the test sample with respect to each class and combines them to recognize the face. The paper shows the theoretical foundation and rationale of the proposed method. Moreover, this paper for the first time shows that a basic nature of the human face, i.e., the symmetry of the face can be exploited to generate new training and test samples. As these new samples really reflect some possible appearance of the face, the use of them will enable us to obtain higher accuracy. The experiments show that the proposed conventional and inverse representation-based linear regression classification (CIRLRC), an improvement to linear regression classification (LRC), can obtain very high accuracy and greatly outperforms the naive LRC and other state-of-the-art conventional representation based face recognition methods. The accuracy of CIRLRC can be 10% greater than that of LRC.

Evaluation of beef trim sampling methods for detection of Shiga toxin-producing Escherichia coli (STEC)

USDA-ARS?s Scientific Manuscript database

Presence of Shiga toxin-producing Escherichia coli (STEC) is a major concern in ground beef. Several methods for sampling beef trim prior to grinding are currently used in the beef industry. The purpose of this study was to determine the efficacy of the sampling methods for detecting STEC in beef ...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and... weigh ten pounds or less, or in any container where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and... weigh ten pounds or less, or in any container where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated...

40 CFR 63.1385 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... applicable emission limits: (1) Method 1 (40 CFR part 60, appendix A) for the selection of the sampling port location and number of sampling ports; (2) Method 2 (40 CFR part 60, appendix A) for volumetric flow rate.... Each run shall consist of a minimum run time of 2 hours and a minimum sample volume of 60 dry standard...

Random vs. systematic sampling from administrative databases involving human subjects.

PubMed

Hagino, C; Lo, R J

1998-09-01

Two sampling techniques, simple random sampling (SRS) and systematic sampling (SS), were compared to determine whether they yield similar and accurate distributions for the following four factors: age, gender, geographic location and years in practice. Any point estimate within 7 yr or 7 percentage points of its reference standard (SRS or the entire data set, i.e., the target population) was considered "acceptably similar" to the reference standard. The sampling frame was from the entire membership database of the Canadian Chiropractic Association. The two sampling methods were tested using eight different sample sizes of n (50, 100, 150, 200, 250, 300, 500, 800). From the profile/characteristics, summaries of four known factors [gender, average age, number (%) of chiropractors in each province and years in practice], between- and within-methods chi 2 tests and unpaired t tests were performed to determine whether any of the differences [descriptively greater than 7% or 7 yr] were also statistically significant. The strengths of the agreements between the provincial distributions were quantified by calculating the percent agreements for each (provincial pairwise-comparison methods). Any percent agreement less than 70% was judged to be unacceptable. Our assessments of the two sampling methods (SRS and SS) for the different sample sizes tested suggest that SRS and SS yielded acceptably similar results. Both methods started to yield "correct" sample profiles at approximately the same sample size (n > 200). SS is not only convenient, it can be recommended for sampling from large databases in which the data are listed without any inherent order biases other than alphabetical listing by surname.

Neuston Trawl and Whole Water Samples: A Comparison of Microplastic Sampling Techniques in The Gulf of Maine and Their Application to Citizen-Driven Science

NASA Astrophysics Data System (ADS)

Kautz, M.

2016-12-01

Microplastic research in aquatic environments has quickly evolved over the last decade. To have meaningful inter-study comparisons, it is necessary to define methodological criteria for both the sampling and sorting of microplastics. The most common sampling method used for sea surface samples has traditionally been a neuston net (NN) tow. Originally designed for plankton collection, neuston tows allow for a large volume of water to be sampled and can be coupled with phytoplankton monitoring. The widespread use of surface nets allows for easy comparison between data sets, but the units of measurement for calculating microplastic concentration vary, from surface area m2 and Km2, to volume of water sampled, m3. Contamination by the air, equipment, or sampler is a constant concern in microplastic research. Significant in-field contamination concerns for neuston tow sampling include air exposure time, microplastics in rinse water, sampler contact, and plastic net material. Seeking to overcome the lack of contamination control and the intrinsic instrumental size limitation associated with surface tow nets, we developed an alternative sampling method. The whole water (WW) method is a one-liter grab sample of surface water adapted from College of the Atlantic and Sea Education Association (SEA) student, Marina Garland. This is the only WW method that we are aware of being used to sample microplastic. The method addresses the increasing need to explore smaller size domains, to reduce potential contamination and to incorporate citizen scientists into data collection. Less water is analyzed using the WW method, but it allows for targeted sampling of point-source pollution, intertidal, and shallow areas. The WW methodology can easily be integrated into long-term or citizen science monitoring initiatives due to its simplicity and low equipment demands. The aim of our study was to demonstrate a practical and economically feasible method for sampling microplastic abundance at the micro (10-6m) and nano (10-8m) scale that can be used in a wide variety of environments, and for assessing spatial and temporal distributions. The method has been employed in a multi-year citizen science collaboration with Adventurers and Scientists for Conservation to study microplastic worldwide.

THE NEW YORK CITY URBAN DISPERSION PROGRAM MARCH 2005 FIELD STUDY: TRACER METHODS AND RESULTS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WATSON, T.B.; HEISER, J.; KALB, P.

The Urban Dispersion Program March 2005 Field Study tracer releases, sampling, and analytical methods are described in detail. There were two days where tracer releases and sampling were conducted. A total of 16.0 g of six tracers were released during the first test day or Intensive Observation Period (IOP) 1 and 15.7 g during IOP 2. Three types of sampling instruments were used in this study. Sequential air samplers, or SAS, collected six-minute samples, while Brookhaven atmospheric tracer samplers (BATS) and personal air samplers (PAS) collected thirty-minute samples. There were a total of 1300 samples resulting from the two IOPs.more » Confidence limits in the sampling and analysis method were 20% as determined from 100 duplicate samples. The sample recovery rate was 84%. The integrally averaged 6-minute samples were compared to the 30-minute samples. The agreement was found to be good in most cases. The validity of using a background tracer to calculate sample volumes was examined and also found to have a confidence level of 20%. Methods for improving sampling and analysis are discussed. The data described in this report are available as Excel files. An additional Excel file of quality assured tracer data for use in model validation efforts is also available. The file consists of extensively quality assured BATS tracer data with background concentrations subtracted.« less

Sample processing approach for detection of ricin in surface samples.

PubMed

Kane, Staci; Shah, Sanjiv; Erler, Anne Marie; Alfaro, Teneile

2017-12-01

With several ricin contamination incidents reported over the past decade, rapid and accurate methods are needed for environmental sample analysis, especially after decontamination. A sample processing method was developed for common surface sampling devices to improve the limit of detection and avoid false negative/positive results for ricin analysis. Potential assay interferents from the sample matrix (bleach residue, sample material, wetting buffer), including reference dust, were tested using a Time-Resolved Fluorescence (TRF) immunoassay. Test results suggested that the sample matrix did not cause the elevated background fluorescence sometimes observed when analyzing post-bleach decontamination samples from ricin incidents. Furthermore, sample particulates (80mg/mL Arizona Test Dust) did not enhance background fluorescence or interfere with ricin detection by TRF. These results suggested that high background fluorescence in this immunoassay could be due to labeled antibody quality and/or quantity issues. Centrifugal ultrafiltration devices were evaluated for ricin concentration as a part of sample processing. Up to 30-fold concentration of ricin was observed by the devices, which serve to remove soluble interferents and could function as the front-end sample processing step to other ricin analytical methods. The procedure has the potential to be used with a broader range of environmental sample types and with other potential interferences and to be followed by other ricin analytical methods, although additional verification studies would be required. Published by Elsevier B.V.

Sampling and estimating recreational use.

Treesearch

Timothy G. Gregoire; Gregory J. Buhyoff

1999-01-01

Probability sampling methods applicable to estimate recreational use are presented. Both single- and multiple-access recreation sites are considered. One- and two-stage sampling methods are presented. Estimation of recreational use is presented in a series of examples.

REPRESENTATIVE SAMPLING AND ANALYSIS OF HETEROGENEOUS SOILS

EPA Science Inventory

Standard sampling and analysis methods for hazardous substances in contaminated soils currently are available and routinely employed. Standard methods inherently assume a homogeneous soil matrix and contaminant distribution; therefore only small sample quantities typically are p...

Air sampling with solid phase microextraction

NASA Astrophysics Data System (ADS)

Martos, Perry Anthony

There is an increasing need for simple yet accurate air sampling methods. The acceptance of new air sampling methods requires compatibility with conventional chromatographic equipment, and the new methods have to be environmentally friendly, simple to use, yet with equal, or better, detection limits, accuracy and precision than standard methods. Solid phase microextraction (SPME) satisfies the conditions for new air sampling methods. Analyte detection limits, accuracy and precision of analysis with SPME are typically better than with any conventional air sampling methods. Yet, air sampling with SPME requires no pumps, solvents, is re-usable, extremely simple to use, is completely compatible with current chromatographic equipment, and requires a small capital investment. The first SPME fiber coating used in this study was poly(dimethylsiloxane) (PDMS), a hydrophobic liquid film, to sample a large range of airborne hydrocarbons such as benzene and octane. Quantification without an external calibration procedure is possible with this coating. Well understood are the physical and chemical properties of this coating, which are quite similar to those of the siloxane stationary phase used in capillary columns. The log of analyte distribution coefficients for PDMS are linearly related to chromatographic retention indices and to the inverse of temperature. Therefore, the actual chromatogram from the analysis of the PDMS air sampler will yield the calibration parameters which are used to quantify unknown airborne analyte concentrations (ppb v to ppm v range). The second fiber coating used in this study was PDMS/divinyl benzene (PDMS/DVB) onto which o-(2,3,4,5,6- pentafluorobenzyl) hydroxylamine (PFBHA) was adsorbed for the on-fiber derivatization of gaseous formaldehyde (ppb v range), with and without external calibration. The oxime formed from the reaction can be detected with conventional gas chromatographic detectors. Typical grab sampling times were as small as 5 seconds. With 300 seconds sampling, the formaldehyde detection limit was 2.1 ppbv, better than any other 5 minute sampling device for formaldehyde. The first-order rate constant for product formation was used to quantify formaldehyde concentrations without a calibration curve. This spot sampler was used to sample the headspace of hair gel, particle board, plant material and coffee grounds for formaldehyde, and other carbonyl compounds, with extremely promising results. The SPME sampling devices were also used for time- weighted average sampling (30 minutes to 16 hours). Finally, the four new SPME air sampling methods were field tested with side-by-side comparisons to standard air sampling methods, showing a tremendous use of SPME as an air sampler.

Detection of Mycobacterium tuberculosis in extrapulmonary biopsy samples using PCR targeting IS6110, rpoB, and nested-rpoB PCR Cloning

PubMed Central

Meghdadi, Hossein; Khosravi, Azar D.; Ghadiri, Ata A.; Sina, Amir H.; Alami, Ameneh

2015-01-01

Present study was aimed to examine the diagnostic utility of polymerase chain reaction (PCR) and nested PCR techniques for the detection of Mycobacterium tuberculosis (MTB) DNA in samples from patients with extra pulmonary tuberculosis (EPTB). In total 80 formalin-fixed, paraffin-embedded (FFPE) samples comprising 70 samples with definite diagnosis of EPTB and 10 samples from known non- EPTB on the basis of histopathology examination, were included in the study. PCR amplification targeting IS6110, rpoB gene and nested PCR targeting the rpoB gene were performed on the extracted DNAs from 80 FFPE samples. The strong positive samples were directly sequenced. For negative samples and those with weak band in nested-rpoB PCR, TA cloning was performed by cloning the products into the plasmid vector with subsequent sequencing. The 95% confidence intervals (CI) for the estimates of sensitivity and specificity were calculated for each method. Fourteen (20%), 34 (48.6%), and 60 (85.7%) of the 70 positive samples confirmed by histopathology, were positive by rpoB-PCR, IS6110-PCR, and nested-rpoB PCR, respectively. By performing TA cloning on samples that yielded weak (n = 8) or negative results (n = 10) in the PCR methods, we were able to improve their quality for later sequencing. All samples with weak band and 7 out of 10 negative samples, showed strong positive results after cloning. So nested-rpoB PCR cloning revealed positivity in 67 out of 70 confirmed samples (95.7%). The sensitivity of these combination methods was calculated as 95.7% in comparison with histopathology examination. The CI for sensitivity of the PCR methods were calculated as 11.39–31.27% for rpoB-PCR, 36.44–60.83% for IS6110- PCR, 75.29–92.93% for nested-rpoB PCR, and 87.98–99.11% for nested-rpoB PCR cloning. The 10 true EPTB negative samples by histopathology, were negative by all tested methods including cloning and were used to calculate the specificity of the applied methods. The CI for 100% specificity of each PCR method were calculated as 69.15–100%. Our results indicated that nested-rpoB PCR combined with TA cloning and sequencing is a preferred method for the detection of MTB DNA in EPTB samples with high sensitivity and specificity which confirm the histopathology results. PMID:26191059

Detection of Mycobacterium tuberculosis in extrapulmonary biopsy samples using PCR targeting IS6110, rpoB, and nested-rpoB PCR Cloning.

PubMed

Meghdadi, Hossein; Khosravi, Azar D; Ghadiri, Ata A; Sina, Amir H; Alami, Ameneh

2015-01-01

Present study was aimed to examine the diagnostic utility of polymerase chain reaction (PCR) and nested PCR techniques for the detection of Mycobacterium tuberculosis (MTB) DNA in samples from patients with extra pulmonary tuberculosis (EPTB). In total 80 formalin-fixed, paraffin-embedded (FFPE) samples comprising 70 samples with definite diagnosis of EPTB and 10 samples from known non- EPTB on the basis of histopathology examination, were included in the study. PCR amplification targeting IS6110, rpoB gene and nested PCR targeting the rpoB gene were performed on the extracted DNAs from 80 FFPE samples. The strong positive samples were directly sequenced. For negative samples and those with weak band in nested-rpoB PCR, TA cloning was performed by cloning the products into the plasmid vector with subsequent sequencing. The 95% confidence intervals (CI) for the estimates of sensitivity and specificity were calculated for each method. Fourteen (20%), 34 (48.6%), and 60 (85.7%) of the 70 positive samples confirmed by histopathology, were positive by rpoB-PCR, IS6110-PCR, and nested-rpoB PCR, respectively. By performing TA cloning on samples that yielded weak (n = 8) or negative results (n = 10) in the PCR methods, we were able to improve their quality for later sequencing. All samples with weak band and 7 out of 10 negative samples, showed strong positive results after cloning. So nested-rpoB PCR cloning revealed positivity in 67 out of 70 confirmed samples (95.7%). The sensitivity of these combination methods was calculated as 95.7% in comparison with histopathology examination. The CI for sensitivity of the PCR methods were calculated as 11.39-31.27% for rpoB-PCR, 36.44-60.83% for IS6110- PCR, 75.29-92.93% for nested-rpoB PCR, and 87.98-99.11% for nested-rpoB PCR cloning. The 10 true EPTB negative samples by histopathology, were negative by all tested methods including cloning and were used to calculate the specificity of the applied methods. The CI for 100% specificity of each PCR method were calculated as 69.15-100%. Our results indicated that nested-rpoB PCR combined with TA cloning and sequencing is a preferred method for the detection of MTB DNA in EPTB samples with high sensitivity and specificity which confirm the histopathology results.

Survey of South African fruit juices using a fast screening HILIC-MS method.

PubMed

Stander, Marietjie A; Kühn, Wernich; Hiten, Nicholas F

2013-01-01

Adulteration of fruit juices--by the addition of sugar or other less expensive fruit juices as well as preservatives, artificial sweeteners and colours--was tested for by using a developed screening method. The method employs hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) using electrospray ionisation in the negative mode and ultraviolet light detection. Different fruit juices can be differentiated by the content of marker compounds like sorbitol, certain phenolic molecules and their saccharide profile. This method was used to test 46 fruit juice samples from the retail market as well as 12 control samples. The study focused on the main types of fruit juices consumed on the South African market including apple, orange, grape and blends of these juices with other fruits like mango, pear and guava. Overall, the 46 samples tested mostly agreed with label claims. One grape juice sample was adulterated, probably with apple juice. Natamycin above the legal limits was found in two samples. In addition, two samples contained natamycin and one sample benzoate without it being indicated on the label. The method is well suited as a quick screening method for fruit juice adulteration and if used routinely would reduce fruit juice adulteration without the cost of the current array of tests needed for authenticity testing.

Development and validation of an HPLC–MS/MS method to determine clopidogrel in human plasma

PubMed Central

Liu, Gangyi; Dong, Chunxia; Shen, Weiwei; Lu, Xiaopei; Zhang, Mengqi; Gui, Yuzhou; Zhou, Qinyi; Yu, Chen

2015-01-01

A quantitative method for clopidogrel using online-SPE tandem LC–MS/MS was developed and fully validated according to the well-established FDA guidelines. The method achieves adequate sensitivity for pharmacokinetic studies, with lower limit of quantifications (LLOQs) as low as 10 pg/mL. Chromatographic separations were performed on reversed phase columns Kromasil Eternity-2.5-C18-UHPLC for both methods. Positive electrospray ionization in multiple reaction monitoring (MRM) mode was employed for signal detection and a deuterated analogue (clopidogrel-d4) was used as internal standard (IS). Adjustments in sample preparation, including introduction of an online-SPE system proved to be the most effective method to solve the analyte back-conversion in clinical samples. Pooled clinical samples (two levels) were prepared and successfully used as real-sample quality control (QC) in the validation of back-conversion testing under different conditions. The result showed that the real samples were stable in room temperature for 24 h. Linearity, precision, extraction recovery, matrix effect on spiked QC samples and stability tests on both spiked QCs and real sample QCs stored in different conditions met the acceptance criteria. This online-SPE method was successfully applied to a bioequivalence study of 75 mg single dose clopidogrel tablets in 48 healthy male subjects. PMID:26904399

MRI-determined liver proton density fat fraction, with MRS validation: Comparison of regions of interest sampling methods in patients with type 2 diabetes.

PubMed

Vu, Kim-Nhien; Gilbert, Guillaume; Chalut, Marianne; Chagnon, Miguel; Chartrand, Gabriel; Tang, An

2016-05-01

To assess the agreement between published magnetic resonance imaging (MRI)-based regions of interest (ROI) sampling methods using liver mean proton density fat fraction (PDFF) as the reference standard. This retrospective, internal review board-approved study was conducted in 35 patients with type 2 diabetes. Liver PDFF was measured by magnetic resonance spectroscopy (MRS) using a stimulated-echo acquisition mode sequence and MRI using a multiecho spoiled gradient-recalled echo sequence at 3.0T. ROI sampling methods reported in the literature were reproduced and liver mean PDFF obtained by whole-liver segmentation was used as the reference standard. Intraclass correlation coefficients (ICCs), Bland-Altman analysis, repeated-measures analysis of variance (ANOVA), and paired t-tests were performed. ICC between MRS and MRI-PDFF was 0.916. Bland-Altman analysis showed excellent intermethod agreement with a bias of -1.5 ± 2.8%. The repeated-measures ANOVA found no systematic variation of PDFF among the nine liver segments. The correlation between liver mean PDFF and ROI sampling methods was very good to excellent (0.873 to 0.975). Paired t-tests revealed significant differences (P < 0.05) with ROI sampling methods that exclusively or predominantly sampled the right lobe. Significant correlations with mean PDFF were found with sampling methods that included higher number of segments, total area equal or larger than 5 cm(2) , or sampled both lobes (P = 0.001, 0.023, and 0.002, respectively). MRI-PDFF quantification methods should sample each liver segment in both lobes and include a total surface area equal or larger than 5 cm(2) to provide a close estimate of the liver mean PDFF. © 2015 Wiley Periodicals, Inc.

Selected problems with boron determination in water treatment processes. Part I: comparison of the reference methods for ICP-MS and ICP-OES determinations.

PubMed

Kmiecik, Ewa; Tomaszewska, Barbara; Wątor, Katarzyna; Bodzek, Michał

2016-06-01

The aim of the study was to compare the two reference methods for the determination of boron in water samples and further assess the impact of the method of preparation of samples for analysis on the results obtained. Samples were collected during different desalination processes, ultrafiltration and the double reverse osmosis system, connected in series. From each point, samples were prepared in four different ways: the first was filtered (through a membrane filter of 0.45 μm) and acidified (using 1 mL ultrapure nitric acid for each 100 mL of samples) (FA), the second was unfiltered and not acidified (UFNA), the third was filtered but not acidified (FNA), and finally, the fourth was unfiltered but acidified (UFA). All samples were analysed using two analytical methods: inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained were compared and correlated, and the differences between them were studied. The results show that there are statistically significant differences between the concentrations obtained using the ICP-MS and ICP-OES techniques regardless of the methods of sampling preparation (sample filtration and preservation). Finally, both the ICP-MS and ICP-OES methods can be used for determination of the boron concentration in water. The differences in the boron concentrations obtained using these two methods can be caused by several high-level concentrations in selected whole-water digestates and some matrix effects. Higher concentrations of iron (from 1 to 20 mg/L) than chromium (0.02-1 mg/L) in the samples analysed can influence boron determination. When iron concentrations are high, we can observe the emission spectrum as a double joined and overlapping peak.

[Examination of analytical method for triphenyltin (TPT) and tributyltin (TBT) to revise the official methods based on "Act on the Control of Household Products Containing Harmful Substances"].

PubMed

Kawakami, Tsuyoshi; Isama, Kazuo; Nakashima, Harunobu; Yoshida, Jin; Ooshima, Tomoko; Ohno, Hiroyuki; Uemura, Hitoshi; Shioda, Hiroko; Kikuchi, Yoko; Matsuoka, Atsuko; Nishimura, Tetsuji

2012-01-01

The use of triphenyltin (TPT) and tributyltin (TBT) in some household products is banned by "Act on the Control of Household Products Containing Harmful Substances" in Japan. To revise the official analytical method, the method for detecting these organotin compounds was examined in six laboratories using a textile product, water-based adhesive, oil-based paint, which contained known amounts of TPT and TBT (0.1, 1.0, 10 μg/g). TPT and TBT were measured by GC-MS after ethyl-derivation with sodium tetraethylborate. The TBT recoveries in the samples were 70-120%. The TPT recoveries in the water-based adhesive samples were 80-110%, while its concentrations in the textile product and oil-based paint samples decreased because of dephenylation during storage. However, the precision of the method examined was satisfactory because most coefficients of variation for TPT and TBT in the samples were less than 10%. Furthermore, the revised method was able to detect concentrations lower than the officially regulated value. However, the sample matrix and the condition of analytical instrument might affect the estimated TPT and TBT concentrations. Therefore, the revised method may not be suitable for quantitative tests; rather, it can be employed to judge the acceptable levels of these organotin compounds by comparing the values of control sample containing regulated amounts of TPT and TBT with those for an unknown sample, with deuterated TPT and TBT as surrogate substances. It is desirable that TPT in textile and oil-based paint samples are analyzed immediately after the samples obtained because of the decomposition of TPT.

Developmental validation of a Nextera XT mitogenome Illumina MiSeq sequencing method for high-quality samples.

PubMed

Peck, Michelle A; Sturk-Andreaggi, Kimberly; Thomas, Jacqueline T; Oliver, Robert S; Barritt-Ross, Suzanne; Marshall, Charla

2018-05-01

Generating mitochondrial genome (mitogenome) data from reference samples in a rapid and efficient manner is critical to harnessing the greater power of discrimination of the entire mitochondrial DNA (mtDNA) marker. The method of long-range target enrichment, Nextera XT library preparation, and Illumina sequencing on the MiSeq is a well-established technique for generating mitogenome data from high-quality samples. To this end, a validation was conducted for this mitogenome method processing up to 24 samples simultaneously along with analysis in the CLC Genomics Workbench and utilizing the AQME (AFDIL-QIAGEN mtDNA Expert) tool to generate forensic profiles. This validation followed the Federal Bureau of Investigation's Quality Assurance Standards (QAS) for forensic DNA testing laboratories and the Scientific Working Group on DNA Analysis Methods (SWGDAM) validation guidelines. The evaluation of control DNA, non-probative samples, blank controls, mixtures, and nonhuman samples demonstrated the validity of this method. Specifically, the sensitivity was established at ≥25 pg of nuclear DNA input for accurate mitogenome profile generation. Unreproducible low-level variants were observed in samples with low amplicon yields. Further, variant quality was shown to be a useful metric for identifying sequencing error and crosstalk. Success of this method was demonstrated with a variety of reference sample substrates and extract types. These studies further demonstrate the advantages of using NGS techniques by highlighting the quantitative nature of heteroplasmy detection. The results presented herein from more than 175 samples processed in ten sequencing runs, show this mitogenome sequencing method and analysis strategy to be valid for the generation of reference data. Copyright © 2018 Elsevier B.V. All rights reserved.

A Simulation Approach to Assessing Sampling Strategies for Insect Pests: An Example with the Balsam Gall Midge

PubMed Central

Carleton, R. Drew; Heard, Stephen B.; Silk, Peter J.

2013-01-01

Estimation of pest density is a basic requirement for integrated pest management in agriculture and forestry, and efficiency in density estimation is a common goal. Sequential sampling techniques promise efficient sampling, but their application can involve cumbersome mathematics and/or intensive warm-up sampling when pests have complex within- or between-site distributions. We provide tools for assessing the efficiency of sequential sampling and of alternative, simpler sampling plans, using computer simulation with “pre-sampling” data. We illustrate our approach using data for balsam gall midge (Paradiplosis tumifex) attack in Christmas tree farms. Paradiplosis tumifex proved recalcitrant to sequential sampling techniques. Midge distributions could not be fit by a common negative binomial distribution across sites. Local parameterization, using warm-up samples to estimate the clumping parameter k for each site, performed poorly: k estimates were unreliable even for samples of n∼100 trees. These methods were further confounded by significant within-site spatial autocorrelation. Much simpler sampling schemes, involving random or belt-transect sampling to preset sample sizes, were effective and efficient for P. tumifex. Sampling via belt transects (through the longest dimension of a stand) was the most efficient, with sample means converging on true mean density for sample sizes of n∼25–40 trees. Pre-sampling and simulation techniques provide a simple method for assessing sampling strategies for estimating insect infestation. We suspect that many pests will resemble P. tumifex in challenging the assumptions of sequential sampling methods. Our software will allow practitioners to optimize sampling strategies before they are brought to real-world applications, while potentially avoiding the need for the cumbersome calculations required for sequential sampling methods. PMID:24376556

Free-energy analyses of a proton transfer reaction by simulated-tempering umbrella sampling and first-principles molecular dynamics simulations.

PubMed

Mori, Yoshiharu; Okamoto, Yuko

2013-02-01

A simulated tempering method, which is referred to as simulated-tempering umbrella sampling, for calculating the free energy of chemical reactions is proposed. First principles molecular dynamics simulations with this simulated tempering were performed to study the intramolecular proton transfer reaction of malonaldehyde in an aqueous solution. Conformational sampling in reaction coordinate space can be easily enhanced with this method, and the free energy along a reaction coordinate can be calculated accurately. Moreover, the simulated-tempering umbrella sampling provides trajectory data more efficiently than the conventional umbrella sampling method.

Spacelab Charcoal Analyses

NASA Technical Reports Server (NTRS)

Slivon, L. E.; Hernon-Kenny, L. A.; Katona, V. R.; Dejarme, L. E.

1995-01-01

This report describes analytical methods and results obtained from chemical analysis of 31 charcoal samples in five sets. Each set was obtained from a single scrubber used to filter ambient air on board a Spacelab mission. Analysis of the charcoal samples was conducted by thermal desorption followed by gas chromatography/mass spectrometry (GC/MS). All samples were analyzed using identical methods. The method used for these analyses was able to detect compounds independent of their polarity or volatility. In addition to the charcoal samples, analyses of three Environmental Control and Life Support System (ECLSS) water samples were conducted specifically for trimethylamine.

MStern Blotting-High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates.

PubMed

Berger, Sebastian T; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

2015-10-01

We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used membrane-based proteomic sample processing method. We validated our approach on whole-cell lysate and urine and cerebrospinal fluid as clinically relevant body fluids. Without compromising peptide and protein identification, our method uses a vacuum manifold and circumvents the need for digest desalting, making our processing method compatible with standard liquid handling robots. In summary, our new method maintains the strengths of FASP and simultaneously overcomes one of the major limitations of FASP without compromising protein identification and quantification. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Conic Sampling: An Efficient Method for Solving Linear and Quadratic Programming by Randomly Linking Constraints within the Interior

PubMed Central

Serang, Oliver

2012-01-01

Linear programming (LP) problems are commonly used in analysis and resource allocation, frequently surfacing as approximations to more difficult problems. Existing approaches to LP have been dominated by a small group of methods, and randomized algorithms have not enjoyed popularity in practice. This paper introduces a novel randomized method of solving LP problems by moving along the facets and within the interior of the polytope along rays randomly sampled from the polyhedral cones defined by the bounding constraints. This conic sampling method is then applied to randomly sampled LPs, and its runtime performance is shown to compare favorably to the simplex and primal affine-scaling algorithms, especially on polytopes with certain characteristics. The conic sampling method is then adapted and applied to solve a certain quadratic program, which compute a projection onto a polytope; the proposed method is shown to outperform the proprietary software Mathematica on large, sparse QP problems constructed from mass spectometry-based proteomics. PMID:22952741

High-throughput analysis of lipid hydroperoxides in edible oils and fats using the fluorescent reagent diphenyl-1-pyrenylphosphine.

PubMed

Santas, Jonathan; Guzmán, Yeimmy J; Guardiola, Francesc; Rafecas, Magdalena; Bou, Ricard

2014-11-01

A fluorometric method for the determination of hydroperoxides (HP) in edible oils and fats using the reagent diphenyl-1-pyrenylphosphine (DPPP) was developed and validated. Two solvent media containing 100% butanol or a mixture of chloroform/methanol (2:1, v/v) can be used to solubilise lipid samples. Regardless of the solvent used to solubilise the sample, the DPPP method was precise, accurate, sensitive and easy to perform. The HP content of 43 oil and fat samples was determined and the results were compared with those obtained by means of the AOCS Official Method for the determination of peroxide value (PV) and the ferrous oxidation-xylenol orange (FOX) method. The proposed method not only correlates well with the PV and FOX methods, but also presents some advantages such as requiring low sample and solvent amounts and being suitable for high-throughput sample analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison method for uranium determination in ore sample by inductively coupled plasma optical emission spectrometry (ICP-OES).

PubMed

Sert, Şenol

2013-07-01

A comparison method for the determination (without sample pre-concentration) of uranium in ore by inductively coupled plasma optical emission spectrometry (ICP-OES) has been performed. The experiments were conducted using three procedures: matrix matching, plasma optimization, and internal standardization for three emission lines of uranium. Three wavelengths of Sm were tested as internal standard for the internal standardization method. The robust conditions were evaluated using applied radiofrequency power, nebulizer argon gas flow rate, and sample uptake flow rate by considering the intensity ratio of the Mg(II) 280.270 nm and Mg(I) 285.213 nm lines. Analytical characterization of method was assessed by limit of detection and relative standard deviation values. The certificated reference soil sample IAEA S-8 was analyzed, and the uranium determination at 367.007 nm with internal standardization using Sm at 359.260 nm has been shown to improve accuracy compared with other methods. The developed method was used for real uranium ore sample analysis.

A modified approach to estimating sample size for simple logistic regression with one continuous covariate.

PubMed

Novikov, I; Fund, N; Freedman, L S

2010-01-15

Different methods for the calculation of sample size for simple logistic regression (LR) with one normally distributed continuous covariate give different results. Sometimes the difference can be large. Furthermore, some methods require the user to specify the prevalence of cases when the covariate equals its population mean, rather than the more natural population prevalence. We focus on two commonly used methods and show through simulations that the power for a given sample size may differ substantially from the nominal value for one method, especially when the covariate effect is large, while the other method performs poorly if the user provides the population prevalence instead of the required parameter. We propose a modification of the method of Hsieh et al. that requires specification of the population prevalence and that employs Schouten's sample size formula for a t-test with unequal variances and group sizes. This approach appears to increase the accuracy of the sample size estimates for LR with one continuous covariate.

A new low-cost procedure for detecting nucleic acids in low-incidence samples: a case study of detecting spores of Paenibacillus larvae from bee debris.

PubMed

Ryba, Stepan; Kindlmann, Pavel; Titera, Dalibor; Haklova, Marcela; Stopka, Pavel

2012-10-01

American foulbrood, because of its virulence and worldwide spread, is currently one of the most dangerous diseases of honey bees. Quick diagnosis of this disease is therefore vitally important. For its successful eradication, however, all the hives in the region must be tested. This is time consuming and costly. Therefore, a fast and sensitive method of detecting American foulbrood is needed. Here we present a method that significantly reduces the number of tests needed by combining batches of samples from different hives. The results of this method were verified by testing each sample. A simulation study was used to compare the efficiency of the new method with testing all the samples and to develop a decision tool for determining when best to use the new method. The method is suitable for testing large numbers of samples (over 100) when the incidence of the disease is low (10% or less).

MStern Blotting–High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates*

PubMed Central

Berger, Sebastian T.; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

2015-01-01

We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used membrane-based proteomic sample processing method. We validated our approach on whole-cell lysate and urine and cerebrospinal fluid as clinically relevant body fluids. Without compromising peptide and protein identification, our method uses a vacuum manifold and circumvents the need for digest desalting, making our processing method compatible with standard liquid handling robots. In summary, our new method maintains the strengths of FASP and simultaneously overcomes one of the major limitations of FASP without compromising protein identification and quantification. PMID:26223766

Development, evaluation and comparison of two independent sampling and analytical methods for ortho-phthalaldehyde vapors and condensation aerosols in air† ‡

PubMed Central

2015-01-01

Two independent sampling and analytical methods for ortho-phthalaldehyde (OPA) in air have been developed, evaluated and compared (1) a reagent-coated solid sorbent HPLC-UV method and (2) an impinger-fluorescence method. In the first method, air sampling is conducted at 1.0 L min−1 with a sampler containing 350 mg of silica gel coated with 1 mg of acidified 2,4-dinitrophenylhydrazine (DNPH). After sampling, excess DNPH in ethyl acetate is added to the sampler prior to storage for 68 hours. The OPA-DNPH derivative is eluted with 4.0 mL of dimethyl sulfoxide (DMSO) for measurement by HPLC with a UV detector set at 3S5 nm. The estimated detection limit is 0.016 µg per sample or 0.067 µg m−3 (0.012 ppb) for a 240 L air sample. Recoveries of vapor spikes at levels of 1.2 to 6.2 µg were 96 to 101%. Recoveries of spikes as mixtures of vapor and condensation aerosols were 97 to 100%. In the second method, air sampling is conducted at 1.0 L mm−1 with a midget impinger containing 10 mL of DMSO solution containing N-acetyl-l-cysteine and ethylenediamine. The fluorescence reading is taken 80 min after the completion of air sampling. Since the time of taking the fluorescence reading is critical, the reading is taken with a portable fluorometer. The estimated detection limit is 0.024 µg per sample or 0.1 µg m−3 (0.018 ppb) for a 240 L air sample. Recoveries of OPA vapor spikes at levels of 1.4 to 5.0 µg per sample were 97 to 105%. Recoveries of spikes as mixtures of vapors and condensation aerosols were 95 to 99%. The collection efficiency for a mixture of vapor and condensation aerosol was 99.4%. The two methods were compared side-by-side in a generation system constructed for producing controlled atmospheres of OPA vapor in air. Average air concentrations of OPA vapor found by both methods agreed within ±10%. PMID:26346658

Determination of low methylmercury concentrations in peat soil samples by isotope dilution GC-ICP-MS using distillation and solvent extraction methods.

PubMed

Pietilä, Heidi; Perämäki, Paavo; Piispanen, Juha; Starr, Mike; Nieminen, Tiina; Kantola, Marjatta; Ukonmaanaho, Liisa

2015-04-01

Most often, only total mercury concentrations in soil samples are determined in environmental studies. However, the determination of extremely toxic methylmercury (MeHg) in addition to the total mercury is critical to understand the biogeochemistry of mercury in the environment. In this study, N2-assisted distillation and acidic KBr/CuSO4 solvent extraction methods were applied to isolate MeHg from wet peat soil samples collected from boreal forest catchments. Determination of MeHg was performed using a purge and trap GC-ICP-MS technique with a species-specific isotope dilution quantification. Distillation is known to be more prone to artificial MeHg formation compared to solvent extraction which may result in the erroneous MeHg results, especially with samples containing high amounts of inorganic mercury. However, methylation of inorganic mercury during the distillation step had no effect on the reliability of the final MeHg results when natural peat soil samples were distilled. MeHg concentrations determined in peat soil samples after distillation were compared to those determined after the solvent extraction method. MeHg concentrations in peat soil samples varied from 0.8 to 18 μg kg(-1) (dry weight) and the results obtained with the two different methods did not differ significantly (p=0.05). The distillation method with an isotope dilution GC-ICP-MS was shown to be a reliable method for the determination of low MeHg concentrations in unpolluted soil samples. Furthermore, the distillation method is solvent-free and less time-consuming and labor-intensive when compared to the solvent extraction method. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of B{sub 2}O{sub 3} flux on growth NLBCO superconductor by solid state reaction and wet-mixing methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suharta, W. G., E-mail: wgsuharta@gmail.com; Wendri, N.; Ratini, N.

The synthesis of B{sub 2}O{sub 3} flux substituted NLBCO superconductor NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂} has been done using solid state reaction and wet-mixing methods in order to obtain homogeneous crystals and single phase. From DTA/TGA characteritations showed the synthesis process by wet-mixing requires a lower temperature than the solid state reaction in growing the superconductor NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂}. Therefore, in this research NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂} sample calcinated at 650°C for wet-mixing method and 820°C for solid state reaction methods. The all samples was sintered at 950°C for ten hours. Crystallinity of the sample was confirmedmore » using X-ray techniques and generally obtained sharp peaks that indicates the sample already well crystallized. Search match analyses for diffraction data gave weight fractions of impurity phase of the solid state reaction method higher than wet-mixing method. In this research showed decreasing the price of the lattice parameter about 1% with the addition of B{sub 2}O{sub 3} flux for the both synthesis process and 2% of wet mixing process for all samples. Characterization using scanning electron microscopy (SEM) showed the distribution of crystal zise for wet-mixing method more homogeneous than solid state reaction method, with he grain size of samples is around 150–250 nm. The results of vibrating sample magnetometer (VSM) showed the paramagnetic properties for all samples.« less

Effects of Linking Methods on Detection of DIF.

ERIC Educational Resources Information Center

Kim, Seock-Ho; Cohen, Allan S.

1992-01-01

Effects of the following methods for linking metrics on detection of differential item functioning (DIF) were compared: (1) test characteristic curve method (TCC); (2) weighted mean and sigma method; and (3) minimum chi-square method. With large samples, results were essentially the same. With small samples, TCC was most accurate. (SLD)

Molecular detection of airborne Coccidioides in Tucson, Arizona

USGS Publications Warehouse

Chow, Nancy A.; Griffin, Dale W.; Barker, Bridget M.; Loparev, Vladimir N.; Litvintseva, Anastasia P.

2016-01-01

Environmental surveillance of the soil-dwelling fungus Coccidioides is essential for the prevention of Valley fever, a disease primarily caused by inhalation of the arthroconidia. Methods for collecting and detectingCoccidioides in soil samples are currently in use by several laboratories; however, a method utilizing current air sampling technologies has not been formally demonstrated for the capture of airborne arthroconidia. In this study, we collected air/dust samples at two sites (Site A and Site B) in the endemic region of Tucson, Arizona, and tested a variety of air samplers and membrane matrices. We then employed a single-tube nested qPCR assay for molecular detection. At both sites, numerous soil samples (n = 10 at Site A and n = 24 at Site B) were collected and Coccidioides was detected in two samples (20%) at Site A and in eight samples (33%) at Site B. Of the 25 air/dust samples collected at both sites using five different air sampling methods, we detected Coccidioides in three samples from site B. All three samples were collected using a high-volume sampler with glass-fiber filters. In this report, we describe these methods and propose the use of these air sampling and molecular detection strategies for environmental surveillance of Coccidioides.

A two-stage cluster sampling method using gridded population data, a GIS, and Google Earth(TM) imagery in a population-based mortality survey in Iraq.

PubMed

Galway, Lp; Bell, Nathaniel; Sae, Al Shatari; Hagopian, Amy; Burnham, Gilbert; Flaxman, Abraham; Weiss, Wiliam M; Rajaratnam, Julie; Takaro, Tim K

2012-04-27

Mortality estimates can measure and monitor the impacts of conflict on a population, guide humanitarian efforts, and help to better understand the public health impacts of conflict. Vital statistics registration and surveillance systems are rarely functional in conflict settings, posing a challenge of estimating mortality using retrospective population-based surveys. We present a two-stage cluster sampling method for application in population-based mortality surveys. The sampling method utilizes gridded population data and a geographic information system (GIS) to select clusters in the first sampling stage and Google Earth TM imagery and sampling grids to select households in the second sampling stage. The sampling method is implemented in a household mortality study in Iraq in 2011. Factors affecting feasibility and methodological quality are described. Sampling is a challenge in retrospective population-based mortality studies and alternatives that improve on the conventional approaches are needed. The sampling strategy presented here was designed to generate a representative sample of the Iraqi population while reducing the potential for bias and considering the context specific challenges of the study setting. This sampling strategy, or variations on it, are adaptable and should be considered and tested in other conflict settings.

A two-stage cluster sampling method using gridded population data, a GIS, and Google EarthTM imagery in a population-based mortality survey in Iraq

PubMed Central

2012-01-01

Background Mortality estimates can measure and monitor the impacts of conflict on a population, guide humanitarian efforts, and help to better understand the public health impacts of conflict. Vital statistics registration and surveillance systems are rarely functional in conflict settings, posing a challenge of estimating mortality using retrospective population-based surveys. Results We present a two-stage cluster sampling method for application in population-based mortality surveys. The sampling method utilizes gridded population data and a geographic information system (GIS) to select clusters in the first sampling stage and Google Earth TM imagery and sampling grids to select households in the second sampling stage. The sampling method is implemented in a household mortality study in Iraq in 2011. Factors affecting feasibility and methodological quality are described. Conclusion Sampling is a challenge in retrospective population-based mortality studies and alternatives that improve on the conventional approaches are needed. The sampling strategy presented here was designed to generate a representative sample of the Iraqi population while reducing the potential for bias and considering the context specific challenges of the study setting. This sampling strategy, or variations on it, are adaptable and should be considered and tested in other conflict settings. PMID:22540266

Methods for estimating population coverage of mass distribution programmes: a review of practices in relation to trachoma control.

PubMed

Cromwell, Elizabeth A; Ngondi, Jeremiah; McFarland, Deborah; King, Jonathan D; Emerson, Paul M

2012-10-01

In the context of trachoma control, population coverage with mass drug administration (MDA) using antibiotics is measured using routine data. Due to the limitations of administrative records as well as the potential for bias from incomplete or incorrect records, a literature review of coverage survey methods applied in neglected tropical disease control programmes and immunisation outreach was conducted to inform the design of coverage surveys for trachoma control. Several methods were identified, including the '30 × 7' survey method for the Expanded Programme on Immunization (EPI 30×7), other cluster random sampling (CRS) methods, lot quality assurance sampling (LQAS), purposive sampling and routine data. When compared against one another, the EPI and other CRS methods produced similar population coverage estimates, whilst LQAS, purposive sampling and use of administrative data did not generate estimates consistent with CRS. In conclusion, CRS methods present a consistent approach for MDA coverage surveys despite different methods of household selection. They merit use until standard guidelines are available. CRS methods should be used to verify population coverage derived from LQAS, purposive sampling methods and administrative reports. Copyright © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Comparing concentration methods: parasitrap® versus Kato-Katz for studying the prevalence of Helminths in Bengo province, Angola.

PubMed

Mirante, Clara; Clemente, Isabel; Zambu, Graciette; Alexandre, Catarina; Ganga, Teresa; Mayer, Carlos; Brito, Miguel

2016-09-01

Helminth intestinal parasitoses are responsible for high levels of child mortality and morbidity. Hence, the capacity to diagnose these parasitoses and consequently ensure due treatment represents a factor of great importance. The main objective of this study involves comparing two methods of concentration, parasitrap and Kato-Katz, for the diagnosis of intestinal parasitoses in faecal samples. Sample processing made recourse to two different concentration methods: the commercial parasitrap® method and the Kato-Katz method. We correspondingly collected a total of 610 stool samples from pre-school and school age children. The results demonstrate the incidence of helminth parasites in 32.8% or 32.3% of the sample collected depending on whether the concentration method applied was either the parasitrap method or the Kato-Katz method. We detected a relatively high percentage of samples testing positive for two or more species of helminth parasites. We would highlight that in searching for larvae the Kato-Katz method does not prove as appropriate as the parasitrap method. Both techniques prove easily applicable even in field working conditions and returning mutually agreeing results. This study concludes in favour of the need for deworming programs and greater public awareness among the rural populations of Angola.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fangyan; Zhang, Song; Chung Wong, Pak

Effectively visualizing large graphs and capturing the statistical properties are two challenging tasks. To aid in these two tasks, many sampling approaches for graph simplification have been proposed, falling into three categories: node sampling, edge sampling, and traversal-based sampling. It is still unknown which approach is the best. We evaluate commonly used graph sampling methods through a combined visual and statistical comparison of graphs sampled at various rates. We conduct our evaluation on three graph models: random graphs, small-world graphs, and scale-free graphs. Initial results indicate that the effectiveness of a sampling method is dependent on the graph model, themore » size of the graph, and the desired statistical property. This benchmark study can be used as a guideline in choosing the appropriate method for a particular graph sampling task, and the results presented can be incorporated into graph visualization and analysis tools.« less

Influence of ECG sampling rate in fetal heart rate variability analysis.

PubMed

De Jonckheere, J; Garabedian, C; Charlier, P; Champion, C; Servan-Schreiber, E; Storme, L; Debarge, V; Jeanne, M; Logier, R

2017-07-01

Fetal hypoxia results in a fetal blood acidosis (pH<;7.10). In such a situation, the fetus develops several adaptation mechanisms regulated by the autonomic nervous system. Many studies demonstrated significant changes in heart rate variability in hypoxic fetuses. So, fetal heart rate variability analysis could be of precious help for fetal hypoxia prediction. Commonly used fetal heart rate variability analysis methods have been shown to be sensitive to the ECG signal sampling rate. Indeed, a low sampling rate could induce variability in the heart beat detection which will alter the heart rate variability estimation. In this paper, we introduce an original fetal heart rate variability analysis method. We hypothesize that this method will be less sensitive to ECG sampling frequency changes than common heart rate variability analysis methods. We then compared the results of this new heart rate variability analysis method with two different sampling frequencies (250-1000 Hz).

Generalized sample entropy analysis for traffic signals based on similarity measure

NASA Astrophysics Data System (ADS)

Shang, Du; Xu, Mengjia; Shang, Pengjian

2017-05-01

Sample entropy is a prevailing method used to quantify the complexity of a time series. In this paper a modified method of generalized sample entropy and surrogate data analysis is proposed as a new measure to assess the complexity of a complex dynamical system such as traffic signals. The method based on similarity distance presents a different way of signals patterns match showing distinct behaviors of complexity. Simulations are conducted over synthetic data and traffic signals for providing the comparative study, which is provided to show the power of the new method. Compared with previous sample entropy and surrogate data analysis, the new method has two main advantages. The first one is that it overcomes the limitation about the relationship between the dimension parameter and the length of series. The second one is that the modified sample entropy functions can be used to quantitatively distinguish time series from different complex systems by the similar measure.

A novel method for the determination of chemical purity and assay of menaquinone-7. Comparison with the methods from the official USP monograph.

PubMed

Jedynak, Łukasz; Jedynak, Maria; Kossykowska, Magdalena; Zagrodzka, Joanna

2017-02-20

An HPLC method with UV detection and separation with the use of a C30 reversed phase analytical column for the determination of chemical purity and assay of menaquinone-7 (MK7) in one chromatographic run was developed. The method is superior to the methods published in the USP Monograph in terms of selectivity, sensitivity and accuracy, as well as time, solvent and sample consumption. The developed methodology was applied to MK7 samples of active pharmaceutical ingredient (API) purity, MK7 samples of lower quality and crude MK7 samples before purification. The comparison of the results revealed that the use of USP methodology could lead to serious overestimation (up to a few percent) of both purity and MK7 assay in menaquinone-7 samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of 129I in environmental samples by AMS and NAA using an anion exchange resin disk

NASA Astrophysics Data System (ADS)

Suzuki, Takashi; Banba, Shigeru; Kitamura, Toshikatsu; Kabuto, Shoji; Isogai, Keisuke; Amano, Hikaru

2007-06-01

We have developed a new extraction method for the measurement of 129I by accelerator mass spectrometry (AMS) utilizing an anion exchange resin disk. In comparison to traditional methods such as solvent extraction and ion exchange, this method provides for simple and quick sample handling. This extraction method was tested on soil, seaweed and milk samples, but because of disk clogging, the milk samples and some of the seaweed could not be applied successfully. Using this new extraction method to prepare samples for AMS analysis produced isotope ratios of iodine in good agreement with neutron activation analysis (NAA). The disk extraction method which take half an hour is faster than previous techniques, such as solvent extraction or ion exchange which take a few hours. The combination of the disk method and the AMS measurement is a powerful tool for the determination of 129I. Furthermore, these data will be available for the environmental monitoring before and during the operation of a new nuclear fuel reprocessing plant in Japan.

Effect of salt concentrations and drying methods on the quality and formation of histamine in dried milkfish (Chanos chanos).

PubMed

Hwang, Chiu-Chu; Lin, Chia-Min; Kung, Hsien-Feng; Huang, Ya-Ling; Hwang, Deng-Fwu; Su, Yi-Cheng; Tsai, Yung-Hsiang

2012-11-15

The effects of salt concentrations (0-15.0%) and drying methods on the quality of dried milkfish were studied. The results showed that the levels of aerobic plate counts, total coliform, water activity, moisture contents, total volatile basic nitrogen (TVBN) and thiobarbituric acid (TBA) of the dried milkfish samples prepared with the same drying method decreased with increased salt concentrations. The samples prepared with the cold-air drying method had better quality in term of lower TVBN and TBA values than those of samples prepared with other drying methods. The histamine contents in all samples, except two, prepared with various salt concentrations by different drying methods were less than 1.9 mg/100 g. Two unsalted samples prepared with hot-air drying at 35 °C and sun drying methods were found to contain histamine at levels of 249.7 and 67.4 mg/100 g, respectively, which were higher than the potential hazard level of 50 mg/100 g. Copyright © 2012 Elsevier Ltd. All rights reserved.

A comparison of four sampling methods among men having sex with men in China: implications for HIV/STD surveillance and prevention

PubMed Central

Guo, Yan; Li, Xiaoming; Fang, Xiaoyi; Lin, Xiuyun; Song, Yan; Jiang, Shuling; Stanton, Bonita

2011-01-01

Sample representativeness remains one of the challenges in effective HIV/STD surveillance and prevention targeting MSM worldwide. Although convenience samples are widely used in studies of MSM, previous studies suggested that these samples might not be representative of the broader MSM population. This issue becomes even more critical in many developing countries where needed resources for conducting probability sampling are limited. We examined variations in HIV and Syphilis infections and sociodemographic and behavioral factors among 307 young migrant MSM recruited using four different convenience sampling methods (peer outreach, informal social network, Internet, and venue-based) in Beijing, China in 2009. The participants completed a self-administered survey and provided blood specimens for HIV/STD testing. Among the four MSM samples using different recruitment methods, rates of HIV infections were 5.1%, 5.8%, 7.8%, and 3.4%; rates of Syphilis infection were 21.8%, 36.2%, 11.8%, and 13.8%; rates of inconsistent condom use were 57%, 52%, 58%, and 38%. Significant differences were found in various sociodemographic characteristics (e.g., age, migration history, education, income, places of employment) and risk behaviors (e.g., age at first sex, number of sex partners, involvement in commercial sex, and substance use) among samples recruited by different sampling methods. The results confirmed the challenges of obtaining representative MSM samples and underscored the importance of using multiple sampling methods to reach MSM from diverse backgrounds and in different social segments and to improve the representativeness of the MSM samples when the use of probability sampling approach is not feasible. PMID:21711162

A comparison of four sampling methods among men having sex with men in China: implications for HIV/STD surveillance and prevention.

PubMed

Guo, Yan; Li, Xiaoming; Fang, Xiaoyi; Lin, Xiuyun; Song, Yan; Jiang, Shuling; Stanton, Bonita

2011-11-01

Sample representativeness remains one of the challenges in effective HIV/STD surveillance and prevention targeting men who have sex with men (MSM) worldwide. Although convenience samples are widely used in studies of MSM, previous studies suggested that these samples might not be representative of the broader MSM population. This issue becomes even more critical in many developing countries where needed resources for conducting probability sampling are limited. We examined variations in HIV and Syphilis infections and sociodemographic and behavioral factors among 307 young migrant MSM recruited using four different convenience sampling methods (peer outreach, informal social network, Internet, and venue-based) in Beijing, China in 2009. The participants completed a self-administered survey and provided blood specimens for HIV/STD testing. Among the four MSM samples using different recruitment methods, rates of HIV infections were 5.1%, 5.8%, 7.8%, and 3.4%; rates of Syphilis infection were 21.8%, 36.2%, 11.8%, and 13.8%; and rates of inconsistent condom use were 57%, 52%, 58%, and 38%. Significant differences were found in various sociodemographic characteristics (e.g., age, migration history, education, income, and places of employment) and risk behaviors (e.g., age at first sex, number of sex partners, involvement in commercial sex, and substance use) among samples recruited by different sampling methods. The results confirmed the challenges of obtaining representative MSM samples and underscored the importance of using multiple sampling methods to reach MSM from diverse backgrounds and in different social segments and to improve the representativeness of the MSM samples when the use of probability sampling approach is not feasible.

Persistent Organic Pollutant Determination in Killer Whale Scat Samples: Optimization of a Gas Chromatography/Mass Spectrometry Method and Application to Field Samples.

PubMed

Lundin, Jessica I; Dills, Russell L; Ylitalo, Gina M; Hanson, M Bradley; Emmons, Candice K; Schorr, Gregory S; Ahmad, Jacqui; Hempelmann, Jennifer A; Parsons, Kim M; Wasser, Samuel K

2016-01-01

Biologic sample collection in wild cetacean populations is challenging. Most information on toxicant levels is obtained from blubber biopsy samples; however, sample collection is invasive and strictly regulated under permit, thus limiting sample numbers. Methods are needed to monitor toxicant levels that increase temporal and repeat sampling of individuals for population health and recovery models. The objective of this study was to optimize measuring trace levels (parts per billion) of persistent organic pollutants (POPs), namely polychlorinated-biphenyls (PCBs), polybrominated-diphenyl-ethers (PBDEs), dichlorodiphenyltrichloroethanes (DDTs), and hexachlorocyclobenzene, in killer whale scat (fecal) samples. Archival scat samples, initially collected, lyophilized, and extracted with 70 % ethanol for hormone analyses, were used to analyze POP concentrations. The residual pellet was extracted and analyzed using gas chromatography coupled with mass spectrometry. Method detection limits ranged from 11 to 125 ng/g dry weight. The described method is suitable for p,p'-DDE, PCBs-138, 153, 180, and 187, and PBDEs-47 and 100; other POPs were below the limit of detection. We applied this method to 126 scat samples collected from Southern Resident killer whales. Scat samples from 22 adult whales also had known POP concentrations in blubber and demonstrated significant correlations (p < 0.01) between matrices across target analytes. Overall, the scat toxicant measures matched previously reported patterns from blubber samples of decreased levels in reproductive-age females and a decreased p,p'-DDE/∑PCB ratio in J-pod. Measuring toxicants in scat samples provides an unprecedented opportunity to noninvasively evaluate contaminant levels in wild cetacean populations; these data have the prospect to provide meaningful information for vital management decisions.

Efficiency of snake sampling methods in the Brazilian semiarid region.

PubMed

Mesquita, Paula C M D; Passos, Daniel C; Cechin, Sonia Z

2013-09-01

The choice of sampling methods is a crucial step in every field survey in herpetology. In countries where time and financial support are limited, the choice of the methods is critical. The methods used to sample snakes often lack objective criteria, and the traditional methods have apparently been more important when making the choice. Consequently researches using not-standardized methods are frequently found in the literature. We have compared four commonly used methods for sampling snake assemblages in a semiarid area in Brazil. We compared the efficacy of each method based on the cost-benefit regarding the number of individuals and species captured, time, and financial investment. We found that pitfall traps were the less effective method in all aspects that were evaluated and it was not complementary to the other methods in terms of abundance of species and assemblage structure. We conclude that methods can only be considered complementary if they are standardized to the objectives of the study. The use of pitfall traps in short-term surveys of the snake fauna in areas with shrubby vegetation and stony soil is not recommended.

Application of Solid Phase Microextraction Coupled with Gas Chromatography/Mass Spectrometry as a Rapid Method for Field Sampling and Analysis of Chemical Warfare Agents and Toxic Industrial Chemicals

DTIC Science & Technology

2003-01-01

PHASE MICROEXTRACTION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS...SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS

Flow injection trace gas analysis method for on-site determination of organoarsenicals

DOEpatents

Aldstadt, III, Joseph H.

1997-01-01

A method for real-time determination of the concentration of Lewisite in the ambient atmosphere, the method includes separating and collecting a Lewisite sample from the atmosphere in a collection chamber, converting the collected Lewisite to an arsenite ion solution sample, pumping the arsenite ion containing sample to an electrochemical detector connected to the collection chamber, and electrochemically detecting the converted arsenite ions in the sample, whereby the concentration of arsenite ions detected is proportional to the concentration of Lewisite in the atmosphere.

Possibility of successive SRXFA use along with chemical-spectral methods for palladium analysis in geological samples

NASA Astrophysics Data System (ADS)

Kislov, E. V.; Kulikov, A. A.; Kulikova, A. B.

1989-10-01

Samples of basit-ultrabasit rocks and NiCu ores of the Ioko-Dovyren and Chaya massifs were analysed by SRXFA and a chemical-spectral method. SRXFA perfectly satisfies the quantitative noble-metals analysis of ore-free rocks. Combination of SRXFA and chemical-spectral analysis has good prospects. After analysis of a great number of samples by SRXFA it is necessary to select samples which would show minimal and maximal results for the chemical-spectral method.

Electrodeposition as an alternate method for preparation of environmental samples for iodide by AMS

DOE PAGES

Adamic, M. L.; Lister, T. E.; Dufek, E. J.; ...

2015-03-25

This paper presents an evaluation of an alternate method for preparing environmental samples for 129I analysis by accelerator mass spectrometry (AMS) at Idaho National Laboratory. The optimal sample preparation method is characterized by ease of preparation, capability of processing very small quantities of iodide, and ease of loading into a cathode. Electrodeposition of iodide on a silver wire was evaluated using these criteria. This study indicates that the electrochemically-formed silver iodide deposits produce ion currents similar to those from precipitated silver iodide for the same sample mass. Furthermore, precipitated silver iodide samples are usually mixed with niobium or silver powdermore » prior to loading in a cathode. Using electrodeposition, the silver is already mixed with the sample and can simply be picked up with tweezers, placed in the sample die, and pressed into a cathode. The major advantage of this method is that the silver wire/electrodeposited silver iodide is much easier to load into a cathode.« less

Evaluation of passive samplers for the collection of dissolved organic matter in streams.

PubMed

Warner, Daniel L; Oviedo-Vargas, Diana; Royer, Todd V

2015-01-01

Traditional sampling methods for dissolved organic matter (DOM) in streams limit opportunities for long-term studies due to time and cost constraints. Passive DOM samplers were constructed following a design proposed previously which utilizes diethylaminoethyl (DEAE) cellulose as a sampling medium, and they were deployed throughout a temperate stream network in Indiana. Two deployments of the passive samplers were conducted, during which grab samples were frequently collected for comparison. Differences in DOM quality between sites and sampling methods were assessed using several common optical analyses. The analyses revealed significant differences in optical properties between sampling methods, with the passive samplers preferentially collecting terrestrial, humic-like DOM. We assert that the differences in DOM composition from each sampling method were caused by preferential binding of complex humic compounds to the DEAE cellulose in the passive samplers. Nonetheless, the passive samplers may provide a cost-effective, integrated sample of DOM in situations where the bulk DOM pool is composed mainly of terrestrial, humic-like compounds.

A field test of point relascope sampling of down coarse woody material in managed stands in the Acadian Forest

Treesearch

John C. Brissette; Mark J. Ducey; Jeffrey H. Gove

2003-01-01

We field tested a new method for sampling down coarse woody material (CWM) using an angle gauge and compared it with the more traditional line intersect sampling (LIS) method. Permanent sample locations in stands managed with different silvicultural treatments within the Penobscot Experimental Forest (Maine, USA) were used as the sampling locations. Point relascope...

Bioanalytical method development and validation for the determination of glycine in human cerebrospinal fluid by ion-pair reversed-phase liquid chromatography-tandem mass spectrometry.

PubMed

Jiang, Jian; James, Christopher A; Wong, Philip

2016-09-05

A LC-MS/MS method has been developed and validated for the determination of glycine in human cerebrospinal fluid (CSF). The validated method used artificial cerebrospinal fluid as a surrogate matrix for calibration standards. The calibration curve range for the assay was 100-10,000ng/mL and (13)C2, (15)N-glycine was used as an internal standard (IS). Pre-validation experiments were performed to demonstrate parallelism with surrogate matrix and standard addition methods. The mean endogenous glycine concentration in a pooled human CSF determined on three days by using artificial CSF as a surrogate matrix and the method of standard addition was found to be 748±30.6 and 768±18.1ng/mL, respectively. A percentage difference of -2.6% indicated that artificial CSF could be used as a surrogate calibration matrix for the determination of glycine in human CSF. Quality control (QC) samples, except the lower limit of quantitation (LLOQ) QC and low QC samples, were prepared by spiking glycine into aliquots of pooled human CSF sample. The low QC sample was prepared from a separate pooled human CSF sample containing low endogenous glycine concentrations, while the LLOQ QC sample was prepared in artificial CSF. Standard addition was used extensively to evaluate matrix effects during validation. The validated method was used to determine the endogenous glycine concentrations in human CSF samples. Incurred sample reanalysis demonstrated reproducibility of the method. Copyright © 2016 Elsevier B.V. All rights reserved.

Sex Determination from Fragmented and Degenerated DNA by Amplified Product-Length Polymorphism Bidirectional SNP Analysis of Amelogenin and SRY Genes.

PubMed

Masuyama, Kotoka; Shojo, Hideki; Nakanishi, Hiroaki; Inokuchi, Shota; Adachi, Noboru

2017-01-01

Sex determination is important in archeology and anthropology for the study of past societies, cultures, and human activities. Sex determination is also one of the most important components of individual identification in criminal investigations. We developed a new method of sex determination by detecting a single-nucleotide polymorphism in the amelogenin gene using amplified product-length polymorphisms in combination with sex-determining region Y analysis. We particularly focused on the most common types of postmortem DNA damage in ancient and forensic samples: fragmentation and nucleotide modification resulting from deamination. Amplicon size was designed to be less than 60 bp to make the method more useful for analyzing degraded DNA samples. All DNA samples collected from eight Japanese individuals (four male, four female) were evaluated correctly using our method. The detection limit for accurate sex determination was determined to be 20 pg of DNA. We compared our new method with commercial short tandem repeat analysis kits using DNA samples artificially fragmented by ultraviolet irradiation. Our novel method was the most robust for highly fragmented DNA samples. To deal with allelic dropout resulting from deamination, we adopted "bidirectional analysis," which analyzed samples from both sense and antisense strands. This new method was applied to 14 Jomon individuals (3500-year-old bone samples) whose sex had been identified morphologically. We could correctly identify the sex of 11 out of 14 individuals. These results show that our method is reliable for the sex determination of highly degenerated samples.

Sex Determination from Fragmented and Degenerated DNA by Amplified Product-Length Polymorphism Bidirectional SNP Analysis of Amelogenin and SRY Genes

PubMed Central

Masuyama, Kotoka; Shojo, Hideki; Nakanishi, Hiroaki; Inokuchi, Shota; Adachi, Noboru

2017-01-01

Sex determination is important in archeology and anthropology for the study of past societies, cultures, and human activities. Sex determination is also one of the most important components of individual identification in criminal investigations. We developed a new method of sex determination by detecting a single-nucleotide polymorphism in the amelogenin gene using amplified product-length polymorphisms in combination with sex-determining region Y analysis. We particularly focused on the most common types of postmortem DNA damage in ancient and forensic samples: fragmentation and nucleotide modification resulting from deamination. Amplicon size was designed to be less than 60 bp to make the method more useful for analyzing degraded DNA samples. All DNA samples collected from eight Japanese individuals (four male, four female) were evaluated correctly using our method. The detection limit for accurate sex determination was determined to be 20 pg of DNA. We compared our new method with commercial short tandem repeat analysis kits using DNA samples artificially fragmented by ultraviolet irradiation. Our novel method was the most robust for highly fragmented DNA samples. To deal with allelic dropout resulting from deamination, we adopted “bidirectional analysis,” which analyzed samples from both sense and antisense strands. This new method was applied to 14 Jomon individuals (3500-year-old bone samples) whose sex had been identified morphologically. We could correctly identify the sex of 11 out of 14 individuals. These results show that our method is reliable for the sex determination of highly degenerated samples. PMID:28052096

Fast acquisition of multidimensional NMR spectra of solids and mesophases using alternative sampling methods.

PubMed

Lesot, Philippe; Kazimierczuk, Krzysztof; Trébosc, Julien; Amoureux, Jean-Paul; Lafon, Olivier

2015-11-01

Unique information about the atom-level structure and dynamics of solids and mesophases can be obtained by the use of multidimensional nuclear magnetic resonance (NMR) experiments. Nevertheless, the acquisition of these experiments often requires long acquisition times. We review here alternative sampling methods, which have been proposed to circumvent this issue in the case of solids and mesophases. Compared to the spectra of solutions, those of solids and mesophases present some specificities because they usually display lower signal-to-noise ratios, non-Lorentzian line shapes, lower spectral resolutions and wider spectral widths. We highlight herein the advantages and limitations of these alternative sampling methods. A first route to accelerate the acquisition time of multidimensional NMR spectra consists in the use of sparse sampling schemes, such as truncated, radial or random sampling ones. These sparsely sampled datasets are generally processed by reconstruction methods differing from the Discrete Fourier Transform (DFT). A host of non-DFT methods have been applied for solids and mesophases, including the G-matrix Fourier transform, the linear least-square procedures, the covariance transform, the maximum entropy and the compressed sensing. A second class of alternative sampling consists in departing from the Jeener paradigm for multidimensional NMR experiments. These non-Jeener methods include Hadamard spectroscopy as well as spatial or orientational encoding of the evolution frequencies. The increasing number of high field NMR magnets and the development of techniques to enhance NMR sensitivity will contribute to widen the use of these alternative sampling methods for the study of solids and mesophases in the coming years. Copyright © 2015 John Wiley & Sons, Ltd.

Identification of discriminant proteins through antibody profiling, methods and apparatus for identifying an individual

DOEpatents

Apel, William A.; Thompson, Vicki S; Lacey, Jeffrey A.; Gentillon, Cynthia A.

2016-08-09

A method for determining a plurality of proteins for discriminating and positively identifying an individual based from a biological sample. The method may include profiling a biological sample from a plurality of individuals against a protein array including a plurality of proteins. The protein array may include proteins attached to a support in a preselected pattern such that locations of the proteins are known. The biological sample may be contacted with the protein array such that a portion of antibodies in the biological sample reacts with and binds to the proteins forming immune complexes. A statistical analysis method, such as discriminant analysis, may be performed to determine discriminating proteins for distinguishing individuals. Proteins of interest may be used to form a protein array. Such a protein array may be used, for example, to compare a forensic sample from an unknown source with a sample from a known source.

Identification of discriminant proteins through antibody profiling, methods and apparatus for identifying an individual

DOEpatents

Thompson, Vicki S; Lacey, Jeffrey A; Gentillon, Cynthia A; Apel, William A

2015-03-03

A method for determining a plurality of proteins for discriminating and positively identifying an individual based from a biological sample. The method may include profiling a biological sample from a plurality of individuals against a protein array including a plurality of proteins. The protein array may include proteins attached to a support in a preselected pattern such that locations of the proteins are known. The biological sample may be contacted with the protein array such that a portion of antibodies in the biological sample reacts with and binds to the proteins forming immune complexes. A statistical analysis method, such as discriminant analysis, may be performed to determine discriminating proteins for distinguishing individuals. Proteins of interest may be used to form a protein array. Such a protein array may be used, for example, to compare a forensic sample from an unknown source with a sample from a known source.

A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples.

PubMed

Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Rani, Manviri; Lee, Jongmyoung; Shim, Won Joon

2015-04-15

The analysis of microplastics in various environmental samples requires the identification of microplastics from natural materials. The identification technique lacks a standardized protocol. Herein, stereomicroscope and Fourier transform infrared spectroscope (FT-IR) identification methods for microplastics (<1mm) were compared using the same samples from the sea surface microlayer (SML) and beach sand. Fragmented microplastics were significantly (p<0.05) underestimated and fiber was significantly overestimated using the stereomicroscope both in the SML and beach samples. The total abundance by FT-IR was higher than by microscope both in the SML and beach samples, but they were not significantly (p>0.05) different. Depending on the number of samples and the microplastic size range of interest, the appropriate identification method should be determined; selecting a suitable identification method for microplastics is crucial for evaluating microplastic pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Floating Ultrasonic Transducer Inspection System and Method for Nondestructive Evaluation

NASA Technical Reports Server (NTRS)

Johnston, Patrick H. (Inventor); Zalameda, Joseph N. (Inventor)

2016-01-01

A method for inspecting a structural sample using ultrasonic energy includes positioning an ultrasonic transducer adjacent to a surface of the sample, and then transmitting ultrasonic energy into the sample. Force pulses are applied to the transducer concurrently with transmission of the ultrasonic energy. A host machine processes ultrasonic return pulses from an ultrasonic pulser/receiver to quantify attenuation of the ultrasonic energy within the sample. The host machine detects a defect in the sample using the quantified level of attenuation. The method may include positioning a dry couplant between an ultrasonic transducer and the surface. A system includes an actuator, an ultrasonic transducer, a dry couplant between the transducer the sample, a scanning device that moves the actuator and transducer, and a measurement system having a pulsed actuator power supply, an ultrasonic pulser/receiver, and a host machine that executes the above method.

Method and apparatus for generating motor current spectra to enhance motor system fault detection

DOEpatents

Linehan, Daniel J.; Bunch, Stanley L.; Lyster, Carl T.

1995-01-01

A method and circuitry for sampling periodic amplitude modulations in a nonstationary periodic carrier wave to determine frequencies in the amplitude modulations. The method and circuit are described in terms of an improved motor current signature analysis. The method insures that the sampled data set contains an exact whole number of carrier wave cycles by defining the rate at which samples of motor current data are collected. The circuitry insures that a sampled data set containing stationary carrier waves is recreated from the analog motor current signal containing nonstationary carrier waves by conditioning the actual sampling rate to adjust with the frequency variations in the carrier wave. After the sampled data is transformed to the frequency domain via the Discrete Fourier Transform, the frequency distribution in the discrete spectra of those components due to the carrier wave and its harmonics will be minimized so that signals of interest are more easily analyzed.

Discrimination of whisky brands and counterfeit identification by UV-Vis spectroscopy and multivariate data analysis.

PubMed

Martins, Angélica Rocha; Talhavini, Márcio; Vieira, Maurício Leite; Zacca, Jorge Jardim; Braga, Jez Willian Batista

2017-08-15

The discrimination of whisky brands and counterfeit identification were performed by UV-Vis spectroscopy combined with partial least squares for discriminant analysis (PLS-DA). In the proposed method all spectra were obtained with no sample preparation. The discrimination models were built with the employment of seven whisky brands: Red Label, Black Label, White Horse, Chivas Regal (12years), Ballantine's Finest, Old Parr and Natu Nobilis. The method was validated with an independent test set of authentic samples belonging to the seven selected brands and another eleven brands not included in the training samples. Furthermore, seventy-three counterfeit samples were also used to validate the method. Results showed correct classification rates for genuine and false samples over 98.6% and 93.1%, respectively, indicating that the method can be helpful for the forensic analysis of whisky samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

COMPARISON OF LABORATORY SUBSAMPLING METHODS OF BENTHIC SAMPLES FROM BOATABLE RIVERS USING ACTUAL AND SIMULATED COUNT DATA

EPA Science Inventory

We examined the effects of using a fixed-count subsample of 300 organisms on metric values using macroinvertebrate samples collected with 3 field sampling methods at 12 boatable river sites. For each sample, we used metrics to compare an initial fixed-count subsample of approxima...

A random spatial sampling method in a rural developing nation

Treesearch

Michelle C. Kondo; Kent D.W. Bream; Frances K. Barg; Charles C. Branas

2014-01-01

Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method...