Speed-of-light limitations in passive linear media

NASA Astrophysics Data System (ADS)

Welters, Aaron; Avniel, Yehuda; Johnson, Steven G.

2014-08-01

We prove that well-known speed-of-light restrictions on electromagnetic energy velocity can be extended to a new level of generality, encompassing even nonlocal chiral media in periodic geometries, while at the same time weakening the underlying assumptions to only passivity and linearity of the medium (either with a transparency window or with dissipation). As was also shown by other authors under more limiting assumptions, passivity alone is sufficient to guarantee causality and positivity of the energy density (with no thermodynamic assumptions). Our proof is general enough to include a very broad range of material properties, including anisotropy, bianisotropy (chirality), nonlocality, dispersion, periodicity, and even delta functions or similar generalized functions. We also show that the "dynamical energy density" used by some previous authors in dissipative media reduces to the standard Brillouin formula for dispersive energy density in a transparency window. The results in this paper are proved by exploiting deep results from linear-response theory, harmonic analysis, and functional analysis that had previously not been brought together in the context of electrodynamics.

The effects of maternal passive smoking on maternal milk lipid.

PubMed

Baheiraei, Azam; Shamsi, Azar; Khaghani, Shahnaz; Shams, Sedigheh; Chamari, Maryam; Boushehri, Hoda; Khedri, Azam

2014-01-01

Passive smoking was long overlooked by those in the medical and legal professions as being harmful to one's health, but in recent years the negative effect of passive smoking has come to the fore in the media and laws have been changed so that less people are obliged to unwillingly suffer from passive smoking, particularly in the workplace and in indoor settings. To study the effects of environmental tobacco smoking exposure during the breast-feeding period on maternal milk lipids. This cohort study was conducted on 45 mothers environmental tobacco smoking exposure and 40 non-exposed post-partum mothers referred to the Shahid Ayat health center, Tehran, Iran. Socioeconomic conditions and the demographic characteristics of exposed and non-exposed groups were recorded. Milk samples were collected twice--at baseline (5-7 days after delivery) and four months after delivery. The samples were reserved at -20°C until assay. Milk lipids including cholesterol, triglyceride (TG), high density lipoprotein (HDL) and low density lipoprotein (LDL) were evaluated. Dietary intake assessment was performed by means of the 24-hour dietary recall questionnaire both times. Maternal occupation status and education levels were significantly different between the two groups. Lipids profiles of milk were significantly higher 5-7 days after delivery in the non-exposed group and four months after delivery. Dietary intake was not significantly different between the two groups. Maternal environmental tobacco smoking exposure affects milk lipids which are essential for infant growth.

Audience Activity and Media Use.

ERIC Educational Resources Information Center

Rubin, Alan M.

1993-01-01

Explores a view of audience behavior that lies between the extremes of a passive audience expected to be influenced by communication messages and an active audience expected to make rational decisions about what media content to accept and reject. (RS)

Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.

2016-03-29

A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

Distinct kinetics and mechanisms of mZVI particles aging in saline and fresh groundwater: H2 Evolution and surface passivation

NASA Astrophysics Data System (ADS)

Xin, Jia; Tang, Fenglin; Zheng, Xilai

2016-04-01

Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation. However, its longevity would be negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behaviors of mZVI particles were investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance in different field conditions. The results indicated that mZVI was reactive between 0-7 days exposure to water and then gradually lost reactivity over the next few hundred days. The patterns of kinetic curve were analogous among the three different media. In comparison, during the early phase (0-7 d), mZVI in saline groundwater showed a faster corrosion rate with a k value of 1.357, which was relatively higher than k values in milli-Q water and fresh groundwater. However, as the corrosion process further developed, the fastest corrosion rate was observed in milli-Q water followed with fresh groundwater and saline groundwater. These changes in reactivity provided evidence for different patterns and formation mechanisms of passive layers on mZVI in three media. The SEM-EDS analysis demonstrated that in the saline groundwater, a compact and even oxide film of carbonate green rust or Fe oxide (hydroxyl) species was formed immediately on the surface due to the high concentration and widely distributed bicarbonate and hardness, whereas in the fresh groundwater and milli-Q water, the passive layer was composed of loosely and unevenly distributed precipitates which much slowly formed as the iron corrosion proceeded. These findings provide insight into the molecular-scale mechanism of mZVI passivation by inorganic salts with particular implications in saline groundwater.

U-937 Toxicity Testing of Lunar Dust Stimulant (JSC-1A-vf)

NASA Technical Reports Server (NTRS)

Bales, Kristyn; Hammond, Dianne; Wallace, William; Jeevarajan, Antony

2007-01-01

With NASA planning to extend the human presence to the moon by 2020, the dangers of the lunar environment must be assessed and appropriate countermeasures must be developed. Possible toxic effects of the lunar dust are of particular importance to human health because of the dust's chemical composition, reactivity, and small size. This project focuses on the toxicity of lunar dust stimulant (JSC-1A-vf), in both its active and passive forms, using U-937 human monocyte cells. Simulant was mechanically activated from its passive form by grinding, and its ability to produce hydroxyl radicals was determined. To test for toxicity, active and passivated simulant was diluted in media and applied to the cells for various time periods. Toxicity was then estimated using flow cytometry on the Guava Personal Cell Analysis system. Preliminary results suggest that passivated stimulant is slightly toxic, with an increase in toxicity for activated stimulant. Toxicity results may be affected by cell lysing behavior and quenching of hydroxyl radical production by the cell media.

Chemical surface alteration of biodegradable magnesium exposed to corrosion media.

PubMed

Willumeit, Regine; Fischer, Janine; Feyerabend, Frank; Hort, Norbert; Bismayer, Ulrich; Heidrich, Stefanie; Mihailova, Boriana

2011-06-01

The understanding of corrosion processes of metal implants in the human body is a key problem in modern biomaterial science. Because of the complicated and adjustable in vivo environment, in vitro experiments require the analysis of various physiological corrosion media to elucidate the underlying mechanism of "biological" metal surface modification. In this paper magnesium samples were incubated under cell culture conditions (i.e. including CO(2)) in electrolyte solutions and cell growth media, with and without proteins. Chemical mapping by high-resolution electron-induced X-ray emission spectroscopy and infrared reflection microspectroscopy revealed a complex structure of the formed corrosion layer. The presence of CO(2) in concentrations close to that in blood is significant for the chemistry of the oxidised layer. The presence of proteins leads to a less dense but thicker passivation layer which is still ion and water permeable, as osmolality and weight measurements indicate. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

From Snow White to Digimon: Using Popular Media to Confront Confucian Values in Taiwanese Peer Cultures

ERIC Educational Resources Information Center

Hadley, Kathryn Gold; Nenga, Sandi Kawecka

2004-01-01

Parents, educators and social commentators have repeatedly claimed that passive media consumption can harm children. Building on recent attempts to understand how children actively interpret media, the authors use an interpretive model of socialization to analyze fieldnote excerpts from a Taiwanese kindergarten and first grade. Contrary to popular…

Print media coverage of research on passive smoking

PubMed Central

Kennedy, G.; Bero, L.

1999-01-01

OBJECTIVE—To assess the extent and content of newspaper and magazine coverage of research on passive smoking.
DESIGN—Content analysis of newspaper and magazine articles.
SUBJECTS—Articles reporting on passive smoking research published in newspapers (n = 180) or magazines (n = 92) between January 1981 and December 1994.
MAIN OUTCOME MEASURES—Numbers of articles, conclusions of articles, sources quoted, numbers and characteristics of research studies cited, presence of tobacco advertising.
RESULTS—The number of newspaper and magazine articles reporting on passive smoking research increased from four in 1981 to 57 in 1992 and 32 in 1994. Sixty-two per cent (168/272) of articles concluded that the research on passive smoking is controversial. Tobacco industry representatives were quoted significantly more often in newspaper articles (52%, 94/180) than magazine articles (12%, 11/92) (p<0.0001). Of 121 different research studies cited in the lay press articles, only 15 were from tobacco-industry sponsored projects or publications. In magazines, acceptance of tobacco industry advertising was associated with the conclusion that research on passive smoking is controversial (p<0.0001).
CONCLUSIONS—Although research on the harmful effects of passive smoking accumulated between 1981 and 1994, lay press coverage of the research maintained that the science was controversial. Few research studies were cited to support the industry's claim that passive smoking is not harmful to health. However, tobacco industry representatives who were critical of the research methods used to study the health effects of passive smoking were frequently quoted.


Keywords: environmental tobacco smoke; media; passive smoking PMID:10599568

Discreet passive explosive detection through 2-sided waveguided fluorescence

DOEpatents

Harper, Ross James [Stillwater, OK; la Grone, Marcus [Cushing, OK; Fisher, Mark [Stillwater, OK

2011-10-18

The current invention provides a passive sampling device suitable for collecting and detecting the presence of target analytes. In particular, the passive sampling device is suitable for detecting nitro-aromatic compounds. The current invention further provides a passive sampling device reader suitable for determining the collection of target analytes. Additionally, the current invention provides methods for detecting target analytes using the passive sampling device and the passive sampling device reader.

Scaling theory in a model of corrosion and passivation.

PubMed

Aarão Reis, F D A; Stafiej, Janusz; Badiali, J-P

2006-09-07

We study a model for corrosion and passivation of a metallic surface after small damage of its protective layer using scaling arguments and simulation. We focus on the transition between an initial regime of slow corrosion rate (pit nucleation) to a regime of rapid corrosion (propagation of the pit), which takes place at the so-called incubation time. The model is defined in a lattice in which the states of the sites represent the possible states of the metal (bulk, reactive, and passive) and the solution (neutral, acidic, or basic). Simple probabilistic rules describe passivation of the metal surface, dissolution of the passive layer, which is enhanced in acidic media, and spatially separated electrochemical reactions, which may create pH inhomogeneities in the solution. On the basis of a suitable matching of characteristic times of creation and annihilation of pH inhomogeneities in the solution, our scaling theory estimates the average radius of the dissolved region at the incubation time as a function of the model parameters. Among the main consequences, that radius decreases with the rate of spatially separated reactions and the rate of dissolution in acidic media, and it increases with the diffusion coefficient of H(+) and OH(-) ions in solution. The average incubation time can be written as the sum of a series of characteristic times for the slow dissolution in neutral media, until significant pH inhomogeneities are observed in the dissolved cavity. Despite having a more complex dependence on the model parameters, it is shown that the average incubation time linearly increases with the rate of dissolution in neutral media, under the reasonable assumption that this is the slowest rate of the process. Our theoretical predictions are expected to apply in realistic ranges of values of the model parameters. They are confirmed by numerical simulation in two-dimensional lattices, and the expected extension of the theory to three dimensions is discussed.

Electrochemical stability and corrosion resistance of Ti-Mo alloys for biomedical applications.

PubMed

Oliveira, N T C; Guastaldi, A C

2009-01-01

Electrochemical behavior of pure Ti and Ti-Mo alloys (6-20wt.% Mo) was investigated as a function of immersion time in electrolyte simulating physiological media. Open-circuit potential values indicated that all Ti-Mo alloys studied and pure Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the chloride-containing solution. It also indicated that the addition of Mo to pure Ti up to 15wt.% seems to improve the protection characteristics of its spontaneous oxides. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all samples, increasing with immersion time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metals' surface, improving their resistance with immersion time, presenting the highest values to Ti-15Mo alloy. Potentiodynamic polarization showed a typical valve-metal behavior, with anodic formation of barrier-type oxide films, without pitting corrosion, even in chloride-containing solution. In all cases, the passive current values were quite small, and decrease after 360h of immersion. All these electrochemical results suggest that the Ti-15Mo alloy is a promising material for orthopedic devices, since electrochemical stability is directly associated with biocompatibility and is a necessary condition for applying a material as biomaterial.

Social media in dermatology: moving to Web 2.0.

PubMed

Travers, Robin L

2012-09-01

Patient use of social media platforms for accessing medical information has accelerated in parallel with overall use of the Internet. Dermatologists must keep pace with our patients' use of these media through either passive or active means are outlined in detail for 4 specific social media outlets. A 5-step plan for active engagement in social media applications is presented. Implications for medical professionalism, Health Insurance Portability and Accountability Act compliance, and crisis management are discussed. Copyright © 2012. Published by Elsevier Inc.

Discreet passive explosive detection through 2-sided wave guided fluorescence

DOEpatents

Harper, Ross James; la Grone, Marcus; Fisher, Mark

2012-10-16

The current invention provides a passive sampling device suitable for collecting and detecting the presence of target analytes. In particular, the passive sampling device is suitable for detecting nitro-aromatic compounds. The current invention further provides a passive sampling device reader suitable for determining the collection of target analytes. Additionally, the current invention provides methods for detecting target analytes using the passive sampling device and the passive sampling device reader.

Desensitizing Children's Emotional Reactions to the Mass Media.

ERIC Educational Resources Information Center

Wilson, Barbara J.

1989-01-01

Assesses effectiveness of two desensitization strategies for reducing children's emotional reactions to mass media. Examines children having passive exposure, modeled exposure, or no exposure to lizards before watching a horror movie involving lizards. Finds that modeled exposure decreases emotional reactions and negative interpretations, whereas…

Investigating the relationship between media multitasking and processes involved in task-switching.

PubMed

Alzahabi, Reem; Becker, Mark W; Hambrick, David Z

2017-11-01

Although multitasking with media has increased dramatically in recent years (Rideout, Foehr, & Roberts, 2010), the association between media multitasking and cognitive performance is poorly understood. In addition, the literature on the relationship between media multitasking and task-switching, one measure of cognitive control, has produced mixed results (Alzahabi & Becker, 2013; Minear et al., 2013; Ophir, Nass, & Wagner, 2009). Here we use an individual differences approach to investigate the relationship between media multitasking and task-switching performance by first examining the structure of task-switching and identifying the latent factors that contribute to switch costs. Participants performed a series of 3 different task-switching paradigms, each designed to isolate the effects of a specific putative mechanism (e.g., advanced preparation) related to task-switching performance, as well as a series of surveys to measure media multitasking and intelligence. The results suggest that task-switching performance is related to 2 somewhat independent factors, namely an advanced preparation factor and passive decay factor. In addition, multitasking with media was related to a faster ability to prepare for tasks, resulting in faster task-switching performance without a cost to accuracy. Media multitasking and intelligence were both unrelated to passive decay factors. These findings are consistent with a 2-component model of task-switching (Sohn & Anderson, 2001), as well as an automatic/executive framework of cognitive control (Schneider & Shiffrin, 1977). (PsycINFO Database Record (c) 2017 APA, all rights reserved).

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...

New laser media based on microporous glasses

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

Altshuler, G.B.; Bakanov, V.A.; Dulneva, E.G.

The results of the investigation of new class of the laser media based on dye solutions impregnated microporous glasses are presented. Based on such media highly effective active elements of tunable dye lasers and passive modulators for solid-state lasers are created. This article is devoted to laser media of the new type - the heterogenous solid-liquid media on the basis of the impregnated by the solutions of the dyes of the microporous glasses. The microporous glasses represent themselves the products of the leaching of heat - treated sodium borosilicate glasses of a certain composition range. As a result of heatmore » treatment is realized the phase separated glass. It consists of two interconnected phases: the silica rich phase and the chemical unstable sodium - borate - rich phase. If we place this glass in the acid then the ions of sodium and borate will be transfered to the solution. As a result we obtain the porous glass and this process produces the continuous claster. Therefore it could be easily impregnated by liquids and gases. We now have the technology that permits us to obtain the samples with the volume porosity from ten to fifty percent and the size of this poroses could be varied from twenty angstroms up to one thousand angstroms.« less

Elasticity-induced force reversal between active spinning particles in dense passive media

PubMed Central

Aragones, J. L.; Steimel, J. P.; Alexander-Katz, A.

2016-01-01

The self-organization of active particles is governed by their dynamic effective interactions. Such interactions are controlled by the medium in which such active agents reside. Here we study the interactions between active agents in a dense non-active medium. Our system consists of actuated, spinning, active particles embedded in a dense monolayer of passive, or non-active, particles. We demonstrate that the presence of the passive monolayer alters markedly the properties of the system and results in a reversal of the forces between active spinning particles from repulsive to attractive. The origin of such reversal is due to the coupling between the active stresses and elasticity of the system. This discovery provides a mechanism for the interaction between active agents in complex and structured media, opening up opportunities to tune the interaction range and directionality via the mechanical properties of the medium. PMID:27112961

Tobacco smoke increases the risk of otitis media among Greenlandic Inuit children while exposure to organochlorines remain insignificant.

PubMed

Jensen, Ramon Gordon; Koch, Anders; Homøe, Preben; Bjerregaard, Peter

2013-04-01

Prenatal exposure to environmental levels of organochlorines (OCs) has been demonstrated to have immunotoxic effects in humans. We investigated the relationship between prenatal exposure to OCs and the occurrence of otitis media (OM) among Inuit children in Greenland. We estimated the concentration of 14 PCB congeners and 11 pesticides in maternal and cord blood samples and in breast milk in a population-based cohort of 400 mother-child pairs. At follow-up, we examined the children's ears and used their medical records to assess the OM occurrence and severity. Multivariate regression analyses were used with adjustments for passive smoking, crowding, dietary habits, parent's educational level, breast feeding and the use of child-care. The children were 4-10 years of age at follow-up and 223 (85%) participated. We found no association between prenatal OC exposure and the development of OM. Factors associated with the child's hazard of OM during the first 4 years of life were: mother's history of OM (HR 1.70, 95% CI 1.11-2.59, p=0.01); mother's smoking habits: current (HR 2.47, 95% CI 1.45-4.21, p<0.01) and previous (HR 2.00, 95% CI 1.19-3.36, p<0.01); number of smokers in the home (HR 1.17, 95% CI 1.05-1.31, p<0.01). After adjustment mothers' smoking habits remained significant. We found no relationship between high levels of prenatal exposure of OCs and occurrence of OM. Passive smoking was found as the strongest environmental risk factor for the development of OM. Interventions to reduce passive smoke in children's environment are needed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Advancing the Use of Passive Sampling in Risk Assessment and Management of Sediments Contaminated with Hydrophobic Organic Chemicals: Results of an International Ex Situ Passive Sampling Interlaboratory Comparison

PubMed Central

2018-01-01

This work presents the results of an international interlaboratory comparison on ex situ passive sampling in sediments. The main objectives were to map the state of the science in passively sampling sediments, identify sources of variability, provide recommendations and practical guidance for standardized passive sampling, and advance the use of passive sampling in regulatory decision making by increasing confidence in the use of the technique. The study was performed by a consortium of 11 laboratories and included experiments with 14 passive sampling formats on 3 sediments for 25 target chemicals (PAHs and PCBs). The resulting overall interlaboratory variability was large (a factor of ∼10), but standardization of methods halved this variability. The remaining variability was primarily due to factors not related to passive sampling itself, i.e., sediment heterogeneity and analytical chemistry. Excluding the latter source of variability, by performing all analyses in one laboratory, showed that passive sampling results can have a high precision and a very low intermethod variability (

Simulating anomalous transport and multiphase segregation in porous media with the Lattice Boltzmann Method

NASA Astrophysics Data System (ADS)

Matin, Rastin; Hernandez, Anier; Misztal, Marek; Mathiesen, Joachim

2015-04-01

Many hydrodynamic phenomena ranging from flows at micron scale in porous media, large Reynolds numbers flows, non-Newtonian and multiphase flows have been simulated on computers using the lattice Boltzmann (LB) method. By solving the Lattice Boltzmann Equation on unstructured meshes in three dimensions, we have developed methods to efficiently model the fluid flow in real rock samples. We use this model to study the spatio-temporal statistics of the velocity field inside three-dimensional real geometries and investigate its relation to the, in general, anomalous transport of passive tracers for a wide range of Peclet and Reynolds numbers. We extend this model by free-energy based method, which allows us to simulate binary systems with large-density ratios in a thermodynamically consistent way and track the interface explicitly. In this presentation we will present our recent results on both anomalous transport and multiphase segregation.

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.

Hybrid monitoring scheme for end-to-end performance enhancement of multicast-based real-time media

NASA Astrophysics Data System (ADS)

Park, Ju-Won; Kim, JongWon

2004-10-01

As real-time media applications based on IP multicast networks spread widely, end-to-end QoS (quality of service) provisioning for these applications have become very important. To guarantee the end-to-end QoS of multi-party media applications, it is essential to monitor the time-varying status of both network metrics (i.e., delay, jitter and loss) and system metrics (i.e., CPU and memory utilization). In this paper, targeting the multicast-enabled AG (Access Grid) a next-generation group collaboration tool based on multi-party media services, the applicability of hybrid monitoring scheme that combines active and passive monitoring is investigated. The active monitoring measures network-layer metrics (i.e., network condition) with probe packets while the passive monitoring checks both application-layer metrics (i.e., user traffic condition by analyzing RTCP packets) and system metrics. By comparing these hybrid results, we attempt to pinpoint the causes of performance degradation and explore corresponding reactions to improve the end-to-end performance. The experimental results show that the proposed hybrid monitoring can provide useful information to coordinate the performance improvement of multi-party real-time media applications.

An assessment of polyurethane foam passive samplers for atmospheric metals compared with active samplers.

PubMed

Li, Qilu; Yang, Kong; Li, Jun; Zeng, Xiangying; Yu, Zhiqiang; Zhang, Gan

2018-05-01

In this study, we conducted an assessment of polyurethane foam (PUF) passive sampling for metals combining active sampling. Remarkably, we found that the metals collected in the passive samples differed greatly from those collected in active samples. By composition, Cu and Ni accounted for significantly higher proportions in passive samples than in active samples, leading to significantly higher uptake rates of Cu and Ni. In assessing seasonal variation, metals in passive samples had higher concentrations in summer (excluding Heshan), which differed greatly from the pattern of active samples (winter > summer), indicating that the uptake rates of most metals were higher in summer than in winter. Overall, due to the stable passive uptake rates, we considered that PUF passive samplers can be applied to collect atmospheric metals. Additionally, we created a snapshot of the metal pollution in the Pearl River Delta using principal component analysis of PUF samples and their source apportionment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Design and technology parameters influence on durability for heat exchangers tube to tubesheet joints

NASA Astrophysics Data System (ADS)

Ripeanu, R. G.

2017-02-01

The main failures of heat exchangers are: corrosion of tubes and jacket, tubes blockage and failures of tube to tubesheet joints also by corrosion. The most critical zone is tube to tubesheet joints. Depending on types of tube to tubesheet joints, in order to better respect conditions of tension and compression, this paper analyses the tubesheet holes shapes, smooth and with a grove, on corrosion behavior. In the case of welding tubes with tubesheet, welding parameters modify corrosion behavior. Were realized welded joints by three welding regimes and tested at corrosion in two media, tap water and industrial water. Were tested also samples made of smooth tubes, finned tubes and tubes coated with a passive product as applied by a heat exchanger manufacturer. For all samples, the roughness parameters were measured, before and after the corrosion tests. The obtained corrosion rates show that stress values and their distribution along the joint modify the corrosion behavior. The optimum welding parameters were established in order to increase the joint durability. The paper has shown that passive product used is not proper chosen and the technology of obtaining rolled thread pipes diminishes tubes’ durability by increasing the corrosion rate.

Passivated aluminum nanohole arrays for label-free biosensing applications.

PubMed

Canalejas-Tejero, Víctor; Herranz, Sonia; Bellingham, Alyssa; Moreno-Bondi, María Cruz; Barrios, Carlos Angulo

2014-01-22

We report the fabrication and performance of a surface plasmon resonance aluminum nanohole array refractometric biosensor. An aluminum surface passivation treatment based on oxygen plasma is developed in order to circumvent the undesired effects of oxidation and corrosion usually found in aluminum-based biosensors. Immersion tests in deionized water and device simulations are used to evaluate the effectiveness of the passivation process. A label-free bioassay based on biotin analysis through biotin-functionalized dextran-lipase conjugates immobilized on the biosensor-passivated surface in aqueous media is performed as a proof of concept to demonstrate the suitability of these nanostructured aluminum films for biosensing.

Education as Infomercial: From a Culture of Acceptance to a Culture of Action

ERIC Educational Resources Information Center

Willis, Corey J.

2004-01-01

In recent years, some educators have witnessed a decline in the attention span and work ethic of their students. Students have become passive participants in their education. What has caused this shift away from engagement? One thought is that the passivity is a symptom of the programming directed at youth. The multi-media barrage of fast-paced…

Advancing the Use of Passive Sampling in Risk Assessment and Management of Sediments Contaminated with Hydrophobic Organic Chemicals: Results of an International Ex Situ Passive Sampling Interlaboratory Comparison

EPA Science Inventory

This work presents the results of an international interlaboratory comparison on ex situ passive sampling in sediments. The main objectives were to map the state of the science in passively sampling sediments, identify sources of variability, provide recommendations and practica...

Advancing the Use of Passive Sampling in Risk Assessment and Management of Sediments Contaminated with Hydrophobic Organic Chemicals: Results of an International Ex Situ Passive Sampling Interlaboratory Comparison

EPA Science Inventory

This work presents the results of an international interlaboratory comparison on ex situ passive sampling in sediments. The main objectives were to map the state of the science in passively sampling sediments, identify sources of variability, provide recommendations and practical...

Passive Sampling in Regulatory Chemical Monitoring of Nonpolar Organic Compounds in the Aquatic Environment.

PubMed

Booij, Kees; Robinson, Craig D; Burgess, Robert M; Mayer, Philipp; Roberts, Cindy A; Ahrens, Lutz; Allan, Ian J; Brant, Jan; Jones, Lisa; Kraus, Uta R; Larsen, Martin M; Lepom, Peter; Petersen, Jördis; Pröfrock, Daniel; Roose, Patrick; Schäfer, Sabine; Smedes, Foppe; Tixier, Céline; Vorkamp, Katrin; Whitehouse, Paul

2016-01-05

We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths and shortcomings of passive sampling are assessed for water, sediments, and biota. Passive water sampling is a suitable technique for measuring concentrations of freely dissolved compounds. This method yields results that are incompatible with the EU's quality standard definition in terms of total concentrations in water, but this definition has little scientific basis. Insufficient quality control is a present weakness of passive sampling in water. Laboratory performance studies and the development of standardized methods are needed to improve data quality and to encourage the use of passive sampling by commercial laboratories and monitoring agencies. Successful prediction of bioaccumulation based on passive sampling is well documented for organisms at the lower trophic levels, but requires more research for higher levels. Despite the existence of several knowledge gaps, passive sampling presently is the best available technology for chemical monitoring of nonpolar organic compounds. Key issues to be addressed by scientists and environmental managers are outlined.

Passive potassium transport in LK sheep red cells. Modification by N- ethyl maleimide

PubMed Central

1983-01-01

Passive K transport, as modified by N-ethyl maleimide (NEM), was studied in erythrocytes of the low-K (LK) phenotype of sheep. Brief (5- min) treatment with NEM at less than 0.5 mM caused inhibition of passive K influx; NEM at concentrations greater than 0.5 mM caused stimulation of K influx. NEM had similar effects on K efflux. The treatments with NEM did not affect cell volumes (passive K transport in LK cells is sensitive to changes in cell volume). The stimulation of K transport by high [NEM] was also not a consequence of an effect on the metabolic state of the cells. Passive K transport in LK cells is dependent on Cl (it is inhibited in Cl-free media; it may be K/Cl cotransport). NEM had no effect on K influx in Cl-free (NO3- substituted) media. Pretreatment of the cells with anti-L antiserum (L antigen is found on LK cells and not on HK cells) prevented stimulation of K influx by NEM, but did not prevent inhibition. Therefore, NEM modifies the Cl-dependent K transport pathway at two separate sites, a low-affinity site, at which it stimulates, and a high-affinity site, at which it inhibits. Anti-L antibody prevents NEM's action, but only at the low-affinity site. PMID:6875508

Intracochlear Scala Media Pressure Measurement: Implications for Models of Cochlear Mechanics.

PubMed

Kale, Sushrut S; Olson, Elizabeth S

2015-12-15

Models of the active cochlea build upon the underlying passive mechanics. Passive cochlear mechanics is based on physical and geometrical properties of the cochlea and the fluid-tissue interaction between the cochlear partition and the surrounding fluid. Although the fluid-tissue interaction between the basilar membrane and the fluid in scala tympani (ST) has been explored in both active and passive cochleae, there was no experimental data on the fluid-tissue interaction on the scala media (SM) side of the partition. To this aim, we measured sound-evoked intracochlear pressure in SM close to the partition using micropressure sensors. All the SM pressure data are from passive cochleae, likely because the SM cochleostomy led to loss of endocochlear potential. Thus, these experiments are studies of passive cochlear mechanics. SM pressure close to the tissue showed a pattern of peaks and notches, which could be explained as an interaction between fast and slow (i.e., traveling wave) pressure modes. In several animals SM and ST pressure were measured in the same cochlea. Similar to previous studies, ST-pressure was dominated by a slow, traveling wave mode at stimulus frequencies in the vicinity of the best frequency of the measurement location, and by a fast mode above best frequency. Antisymmetric pressure between SM and ST supported the classic single-partition cochlear models, or a dual-partition model with tight coupling between partitions. From the SM and ST pressure we calculated slow and fast modes, and from active ST pressure we extrapolated the passive findings to the active case. The passive slow mode estimated from SM and ST data was low-pass in nature, as predicted by cochlear models. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Intracochlear Scala Media Pressure Measurement: Implications for Models of Cochlear Mechanics

PubMed Central

Kale, Sushrut S.; Olson, Elizabeth S.

2015-01-01

Models of the active cochlea build upon the underlying passive mechanics. Passive cochlear mechanics is based on physical and geometrical properties of the cochlea and the fluid-tissue interaction between the cochlear partition and the surrounding fluid. Although the fluid-tissue interaction between the basilar membrane and the fluid in scala tympani (ST) has been explored in both active and passive cochleae, there was no experimental data on the fluid-tissue interaction on the scala media (SM) side of the partition. To this aim, we measured sound-evoked intracochlear pressure in SM close to the partition using micropressure sensors. All the SM pressure data are from passive cochleae, likely because the SM cochleostomy led to loss of endocochlear potential. Thus, these experiments are studies of passive cochlear mechanics. SM pressure close to the tissue showed a pattern of peaks and notches, which could be explained as an interaction between fast and slow (i.e., traveling wave) pressure modes. In several animals SM and ST pressure were measured in the same cochlea. Similar to previous studies, ST-pressure was dominated by a slow, traveling wave mode at stimulus frequencies in the vicinity of the best frequency of the measurement location, and by a fast mode above best frequency. Antisymmetric pressure between SM and ST supported the classic single-partition cochlear models, or a dual-partition model with tight coupling between partitions. From the SM and ST pressure we calculated slow and fast modes, and from active ST pressure we extrapolated the passive findings to the active case. The passive slow mode estimated from SM and ST data was low-pass in nature, as predicted by cochlear models. PMID:26682824

Surface passivation and aging of InGaAs/InP heterojunction phototransistors

NASA Astrophysics Data System (ADS)

Park, Min-Su; Razaei, Mohsen; Barnhart, Katie; Tan, Chee Leong; Mohseni, Hooman

2017-06-01

We report the effect of different surface treatment and passivation techniques on the stability of InGaAs/InP heterojunction phototransistors (HPTs). An In0.53Ga0.47As surface passivated with aqueous ammonium sulfide ((NH4)2S), aluminum oxide (Al2O3) grown by atomic layer deposition (ALD), and their combination is evaluated by using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All samples were kept in the air ambient, and their performances were periodically measured to investigate their long-term stability. Raman spectroscopy revealed that the peak intensity of the GaAs-like longitudinal optical phonon of all passivated samples is decreased compared with that of the control sample. This is attributable to the diminution of the carriers near the passivated surfaces, which was proven by extracted surface potential (Vs). The Vs of all passivated samples was decreased to less than half of that for the control sample. XPS evaluation of As3d spectra showed that arsenic oxides (As2O3 and As2O5) on the surfaces of the samples can be removed by passivation. However, both Raman and XPS spectra show that the (NH4)2S passivated sample reverts back over time and will resemble the untreated control sample. When capped with ALD-grown Al2O3, passivated samples irrespective of the pretreatment show no degradation over the measured time of 4 weeks. Similar conclusions are made from our experimental measurement of the performance of differently passivated HPTs. The ALD-grown Al2O3 passivated devices show an improved optical gain at low optical powers and long-term stability.

Field application of passive SBSE for the monitoring of pesticides in surface waters.

PubMed

Assoumani, A; Coquery, M; Liger, L; Mazzella, N; Margoum, C

2015-03-01

Spot sampling lacks representativeness for monitoring organic contaminants in most surface waters. Passive sampling has emerged as a cost-effective complementary sampling technique. We recently developed passive stir bar sorptive extraction (passive SBSE), with Twister from Gerstel, for monitoring moderately hydrophilic to hydrophobic pesticides (2.18 < log K ow < 5.11) in surface water. The aims of the present study were to assess this new passive sampler for the determination of representative average concentrations and to evaluate the contamination levels of two French rivers. Passive SBSE was evaluated for the monitoring of 16 pesticides in two rivers located in a small vineyard watershed during two 1-month field campaigns in spring 2010 and spring 2011. Passive SBSE was applied for periods of 1 or 2 weeks during the field campaigns and compared with spot sampling and weekly average automated sampling. The results showed that passive SBSE could achieve better time-representativeness than spot sampling and lower limits of quantification than automated sampling coupled with analytical SBSE for the pesticides studied. Finally, passive SBSE proved useful for revealing spatial and temporal variations in pesticide contamination of both rivers and the impact of rainfall and runoff on the river water quality.

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.

Digital Campaigning: Using the Bill of Rights to Advance a Political Position

ERIC Educational Resources Information Center

Swan, Kathy; Hofer, Mark

2006-01-01

Educating students to understand overt, subtle, and erroneous claims made by partisan advertisers is no small feat. Often students are passive consumers who need to learn how to become critical listeners, viewers, readers, and producers of all types of media. Because of this, media literacy--the ability to access, analyze, evaluate, and produce…

Twitter Gets Favorited in the Education Debate

ERIC Educational Resources Information Center

Supovitz, Jonathan

2015-01-01

The author describes how the interactive study of social media's effect on the Common Core debate was designed and executed. Important findings from the study were: 1) We live in an increasingly interconnected social world. 2) Media has evolved over the last half century from a passive system dominated by a few central opinion makers to the…

Comparison between active (pumped) and passive (diffusive) sampling methods for formaldehyde in pathology and histology laboratories.

PubMed

Lee, Eun Gyung; Magrm, Rana; Kusti, Mohannad; Kashon, Michael L; Guffey, Steven; Costas, Michelle M; Boykin, Carie J; Harper, Martin

2017-01-01

This study was to determine occupational exposures to formaldehyde and to compare concentrations of formaldehyde obtained by active and passive sampling methods. In one pathology and one histology laboratories, exposure measurements were collected with sets of active air samplers (Supelco LpDNPH tubes) and passive badges (ChemDisk Aldehyde Monitor 571). Sixty-six sample pairs (49 personal and 17 area) were collected and analyzed by NIOSH NMAM 2016 for active samples and OSHA Method 1007 (using the manufacturer's updated uptake rate) for passive samples. All active and passive 8-hr time-weighted average (TWA) measurements showed compliance with the OSHA permissible exposure limit (PEL-0.75 ppm) except for one passive measurement, whereas 78% for the active and 88% for the passive samples exceeded the NIOSH recommended exposure limit (REL-0.016 ppm). Overall, 73% of the passive samples showed higher concentrations than the active samples and a statistical test indicated disagreement between two methods for all data and for data without outliers. The OSHA Method cautions that passive samplers should not be used for sampling situations involving formalin solutions because of low concentration estimates in the presence of reaction products of formaldehyde and methanol (a formalin additive). However, this situation was not observed, perhaps because the formalin solutions used in these laboratories included much less methanol (3%) than those tested in the OSHA Method (up to 15%). The passive samplers in general overestimated concentrations compared to the active method, which is prudent for demonstrating compliance with an occupational exposure limit, but occasional large differences may be a result of collecting aerosolized droplets or splashes on the face of the samplers. In the situations examined in this study the passive sampler generally produces higher results than the active sampler so that a body of results from passive samplers demonstrating compliance with the OSHA PEL would be a valid conclusion. However, individual passive samples can show lower results than a paired active sampler so that a single result should be treated with caution.

[Epidemiology of secretory otitis media in children examined at the Otolaryngologic Clinic in Wrocław in 1996-1999].

PubMed

Pośpiech, Lucyna; Rak, Jerzy; Jaworska, Marzena; Klempous, Joanna

2002-01-01

The aim of the work was an evaluation of epidemiological factors in otitis media with effusion (OME) in children. Material consisted of 191 children treated surgically in Wroclaw ENT Clinic. The control group consisted of 95 healthy children. The evaluation was based on detailed history of the patients and physical ORL examination. The factors taken into considerations were: age, sex, birth factors, breast feeding, attending to kindergarten, passive smoking, social and environmental factors, incidents of upper respiratory airways and middle ear infections before OME being diagnosed. Frequent upper respiratory infections, acute and recurrent middle ear infections, staying with other children (kindergarten) and passive smoking increase the risk of OME incidence.

Clogging and depinning of ballistic active matter systems in disordered media

NASA Astrophysics Data System (ADS)

Reichhardt, C.; Reichhardt, C. J. O.

2018-05-01

We numerically examine ballistic active disks driven through a random obstacle array. Formation of a pinned or clogged state occurs at much lower obstacle densities for the active disks than for passive disks. As a function of obstacle density, we identify several distinct phases including a depinned fluctuating cluster state, a pinned single-cluster or jammed state, a pinned multicluster state, a pinned gel state, and a pinned disordered state. At lower active disk densities, a drifting uniform liquid forms in the absence of obstacles, but when even a small number of obstacles are introduced, the disks organize into a pinned phase-separated cluster state in which clusters nucleate around the obstacles, similar to a wetting phenomenon. We examine how the depinning threshold changes as a function of disk or obstacle density and find a crossover from a collectively pinned cluster state to a disordered plastic depinning transition as a function of increasing obstacle density. We compare this to the behavior of nonballistic active particles and show that as we vary the activity from completely passive to completely ballistic, a clogged phase-separated state appears in both the active and passive limits, while for intermediate activity, a readily flowing liquid state appears and there is an optimal activity level that maximizes the flux through the sample.

[Ambient air interference in oxygen intake measurements in liquid incubating media with the use of open polarographic cells].

PubMed

Miniaev, M V; Voronchikhina, L I

2007-01-01

A model of oxygen intake by aerobic bio-objects in liquid incubating media was applied to investigate the influence air-media interface area on accuracy of measuring the oxygen intake and error value. It was shown that intrusion of air oxygen increases the relative error to 24% in open polarographic cells and to 13% in cells with a reduced interface area. Results of modeling passive media oxygenation laid a basis for proposing a method to reduce relative error by 66% for open cells and by 15% for cells with a reduced interface area.

Prepare to Engage: Building Relationships through Social Media Is a Smart Investment for Institutions

ERIC Educational Resources Information Center

Doak, Jennifer

2011-01-01

The people an educational institution is trying to reach--prospective and current students, alumni and parents, to name a few--are no longer passive recipients of press releases and newsletters. They are on Facebook, Twitter, LinkedIn, Google+, and any other social media platform that comes to mind. What can sometimes get lost amid the constant…

Light-Driven Chiral Molecular Motors for Passive Agile Filters

DTIC Science & Technology

2014-05-20

liquid crystal , we fabricated the self-organized, phototubable 3D photonic superstructure, i.e. photoresponsive monodisperse cholesteric liquid...systems for applications. Here the new light-driven chiral molecular switch and upconversion nanoparticles, doped in a liquid crystal media, were...the bottom-up nanofabrication of intelligent molecular devices. Light-driven chiral molecular switches or motors in liquid crystal (LC) media that

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.

Distinct kinetics and mechanisms of mZVI particles aging in saline and fresh groundwater: H2 evolution and surface passivation.

PubMed

Xin, Jia; Tang, Fenglin; Zheng, Xilai; Shao, Haibing; Kolditz, Olaf; Lu, Xin

2016-09-01

Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation; however, its longevity is negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behavior of mZVI particles was investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance under different field conditions. The results indicated that mZVI was reactive for 0-7 days of exposure to water and then gradually lost H2-generating capacity over the next hundred days in all of the tested media. In comparison, mZVI in saline groundwater exhibited the fastest corrosion rate during the early phase (0-7 d), followed by the sharpest kinetic constant decline in the latter phases. The SEM-EDS and XPS analyses demonstrated that in the saline groundwater, a thin and compact oxide film was immediately formed on the surface and significantly shielded the iron reactive site. Nevertheless, in fresh groundwater and milli-Q water, a passive layer composed of loosely and unevenly distributed precipitates slowly formed, with abundant reactive sites available to support continuous iron corrosion. These findings provide insight into the molecular-scale mechanism that governs mZVI passivation and provide implications for long-term mZVI application in saline contaminated groundwater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluating organochlorine pesticide residues in the aquatic environment of the Lake Naivasha River basin using passive sampling techniques.

PubMed

Abbasi, Yasser; Mannaerts, Chris M

2018-05-18

Passive sampling techniques can improve the discovery of low concentrations by continuous collecting the contaminants, which usually go undetected with classic and once-off time-point grab sampling. The aim of this study was to evaluate organochlorine pesticide (OCP) residues in the aquatic environment of the Lake Naivasha river basin (Kenya) using passive sampling techniques. Silicone rubber sheet and Speedisk samplers were used to detect residues of α-HCH, β-HCH, γ-HCH, δ-HCH, heptachlor, aldrin, heptachlor epoxide, pp-DDE, endrin, dieldrin, α-endosulfan, β-endosulfan, pp-DDD, endrin aldehyde, pp-DDT, endosulfan sulfate, and methoxychlor in the Malewa River and Lake Naivasha. After solvent extraction from the sampling media, the residues were analyzed using gas chromatography electron capture detection (GC-ECD) for the OCPs and gas chromatography-mass spectrometry (GC-MS) for the PCB reference compounds. Measuring the OCP residues using the silicone rubber samplers revealed the highest concentration of residues (∑OCPs of 81 (± 18.9 SD) μg/L) to be at the Lake site, being the ultimate accumulation environment for surficial hydrological, chemical, and sediment transport through the river basin. The total OCP residue sums changed to 71.5 (± 11.3 SD) μg/L for the Middle Malewa and 59 (± 12.5 SD) μg/L for the Upper Malewa River sampling sites. The concentration sums of OCPs detected using the Speedisk samplers at the Upper Malewa, Middle Malewa, and the Lake Naivasha sites were 28.2 (± 4.2 SD), 31.3 (± 1.8 SD), and 34.2 (± 6.4 SD) μg/L, respectively. An evaluation of the different pesticide compound variations identified at the three sites revealed that endosulfan sulfate, α-HCH, methoxychlor, and endrin aldehyde residues were still found at all sampling sites. However, the statistical analysis of one-way ANOVA for testing the differences of ∑OCPs between the sampling sites for both the silicone rubber sheet and Speedisk samplers showed that there was no significant difference from the Upper Malewa to the Lake site (P < 0.05). Finally, the finding of this study indicated that continued monitoring of pesticides residues in the catchment remains highly recommended.

Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials

PubMed Central

Maxwell, Adam D.; Cain, Charles A.; Hall, Timothy L.; Fowlkes, J. Brian; Xu, Zhen

2012-01-01

In this article, the negative pressure values at which inertial cavitation consistently occurs in response to a single, 2-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex-vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (Pcav) for a single pulse as a function of peak negative pressure (p−) followed a sigmoid curve, with the probability approaching 1 when the pressure amplitude was sufficient. The statistical threshold (defined as Pcav = 0.5) was between p− = 26.0–30.0 MPa in all samples with a high water content, but varied between p− = 13.7 to > 36 MPa for other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p− = 28.2 MPa was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at different pressure levels and dimensions of cavitation-induced lesions in tissue. PMID:23380152

Technical basis for using passive sampling as a biomimetic extraction procedure to assess bioavailability and predict toxicity of petroleum substances.

PubMed

Redman, A D; Butler, J D; Letinski, D J; Di Toro, D M; Leon Paumen, M; Parkerton, T F

2018-05-01

Solid-phase microextraction fibers coated with polydimethylsiloxane (PDMS) provide a convenient passive sampling format to characterize bioavailability of petroleum substances. Hydrocarbons absorb onto PDMS in proportion to both freely dissolved concentrations and partitioning properties of the individual constituents, which parallels the mechanistic basis used to predict aquatic toxicity in the PETROTOX model. When deployed in a non-depletive manner, combining SPME with thermal desorption and quantification using gas chromatography-flame ionization creates a biomimetic extraction (BE) procedure that has the potential to simplify aquatic hazard assessments of petroleum substances since the total moles of all hydrocarbons sorbed to the fiber can be related to toxic thresholds in target lipid of aquatic organisms. The objective of this work is to describe the technical basis for applying BE measurements to predict toxicity of petroleum substances. Critical BE-based PDMS concentrations corresponding to adverse effects were empirically derived from toxicity tests on different petroleum substances with multiple test species. The resulting species sensitivity distribution (SSD) of PDMS effect concentrations was then compared and found consistent with the previously reported target lipid-based SSD. Further, BE data collected on samples of aqueous media dosed with a wide range of petroleum substances were highly correlated to predicted toxic units derived using the PETROTOX model. These findings provide justification for applying BE in environmental hazard and risk evaluations of petroleum substances and related mixtures. Copyright © 2018 Elsevier Ltd. All rights reserved.

A comparison of passive and active acoustic sampling for a bat community impacted by White-nose syndrome

USGS Publications Warehouse

Coleman, Laci S.; Ford, W. Mark; Dobony, Christopher A.; Britzke, Eric R.

2014-01-01

In the summers of 2011 and 2012, we compared passive and active acoustic sampling for bats at 31 sites at Fort Drum Military Installation, New York. We defined active sampling as acoustic sampling that occurred in 30-min intervals between the hours of sunset and 0200 with a user present to manipulate the directionality of the microphone. We defined passive sampling as acoustic sampling that occurred over a 12-h period (1900–0700 hours) without a user present and with the microphone set in a predetermined direction. We detected seven of the nine possible species at Fort Drum, including the federally endangered Indiana bat Myotis sodalis, the proposed-for-listing northern bat M. septentrionalis, the little brown bat M. lucifugus, and the big brown bat Eptesicus fuscus, which are impacted by white-nose syndrome (WNS); and the eastern red bat Lasiurus borealis, the hoary bat L. cinereus, and the silver-haired bat Lasionycteris noctivagans, which are not known to be impacted by WNS. We did not detect two additional WNS-impacted species known to historically occur in the area: the eastern small-footed bat Myotis leibii and the tri-colored bat Perimyotis subflavus. Single-season occupancy models revealed lower detection probabilities of all detected species using active sampling versus passive sampling. Additionally, overall detection probabilities declined in detected WNS-impacted species between years. A paired t-test of simultaneous sampling on 21 occasions revealed that overall recorded foraging activity per hour was greater using active than passive sampling for big brown bats and greater using passive than active sampling for little brown bats. There was no significant difference in recorded activity between methods for other WNS-impacted species, presumably because these species have been so reduced in number that their “apparency” on the landscape is lower. Finally, a cost analysis of standard passive and active sampling protocols revealed that passive sampling is substantially more cost-effective than active sampling per hour of data collection. We recommend passive sampling over active sampling methodologies as they are defined in our study for detection probability and/or occupancy studies focused on declining bat species in areas that have experienced severe WNS-associated impacts.

Multiple mechanisms quench passive spiral galaxies

NASA Astrophysics Data System (ADS)

Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin; Dolley, Tim; Bonne, Nicolas J.

2018-02-01

We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low-mass (M⋆ < 1 × 1010 M⊙) passive spiral galaxies are located in the rich Virgo cluster. This is in contrast to low-mass spiral galaxies with star formation, which inhabit a range of environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low-mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74 ± 15 per cent, compared with 36 ± 5 per cent for a mass, redshift and T-type matched comparison sample of star-forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74 ± 15 per cent is similar to that of the comparison sample of star-forming galaxies at 61 ± 7 per cent. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms is required to produce the passive spiral distribution we see today.

Measurement of Passive Uptake Rates for Volatile Organic Compounds on Commercial Thermal Desorption Tubes and the Effect of Ozone on Sampling

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

Maddalena, Randy; Parra, Amanda; Russell, Marion

Diffusive or passive sampling methods using commercially filled axial-sampling thermal desorption tubes are widely used for measuring volatile organic compounds (VOCs) in air. The passive sampling method provides a robust, cost effective way to measure air quality with time-averaged concentrations spanning up to a week or more. Sampling rates for VOCs can be calculated using tube geometry and Fick’s Law for ideal diffusion behavior or measured experimentally. There is evidence that uptake rates deviate from ideal and may not be constant over time. Therefore, experimentally measured sampling rates are preferred. In this project, a calibration chamber with a continuous stirredmore » tank reactor design and constant VOC source was combined with active sampling to generate a controlled dynamic calibration environment for passive samplers. The chamber air was augmented with a continuous source of 45 VOCs ranging from pentane to diethyl phthalate representing a variety of chemical classes and physiochemical properties. Both passive and active samples were collected on commercially filled Tenax TA thermal desorption tubes over an 11-day period and used to calculate passive sampling rates. A second experiment was designed to determine the impact of ozone on passive sampling by using the calibration chamber to passively load five terpenes on a set of Tenax tubes and then exposing the tubes to different ozone environments with and without ozone scrubbers attached to the tube inlet. During the sampling rate experiment, the measured diffusive uptake was constant for up to seven days for most of the VOCs tested but deviated from linearity for some of the more volatile compounds between seven and eleven days. In the ozone experiment, both exposed and unexposed tubes showed a similar decline in terpene mass over time indicating back diffusion when uncapped tubes were transferred to a clean environment but there was no indication of significant loss by ozone reaction.« less

Optimization of Integrative Passive Sampling Approaches for Use in the Epibenthic Environment

DTIC Science & Technology

2016-12-23

Passive sampler, POCIS, Integrative, Sediment , Benthic 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a...Unexploded ordnance, Passive sampler, POCIS, Integrative, Sediment , Benthic v Acknowledgements Dr. Shane Morrison and Ms. Ingrid...flow and turbulence near the sampler. In complex environments at the sediment – water interface, this may limit the utility of passive sampling

Development of solid materials for UF 6 sampling: FY16 Annual Report

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

Smith, Nicholas; Savina, Joseph; Hebden, Andrew

2016-10-31

A handheld implementation of the ABACC-developed Cristallini method, which captures uranium hexafluoride samples as an inert salt, was organized in FY17 and succeeded in demonstrating the handheld sampler concept with reactive hexafluoride gases. The Cristallini method relies on the use of a hydrated substrate to react the incoming hexafluoride resulting in the formation of a stable uranyl fluoride salt. The Cristallini method has been demonstrated as a facility modification installed near the sampling tap of a gas centrifuge enrichment plant. While very successful in reducing the hazards of uranium hexafluoride sample, the method still takes a considerable amount of timemore » and can only be used in facilities where the apparatus has been installed; this arrangement generally prohibits the sampling of filled cylinders that have already exited the facility and have been deposited in the on-site tank storage yard. The handheld unit under development will allow the use of the Cristallini method at facilities that have not been converted as well as tanks in the storage yard. The handheld system utilizes an active vacuum system, rather than a passive vacuum system in the facility setup, to drive the uranium hexafluoride onto the adsorbing media. The handheld unit will be battery operated for fully autonomous operation and will include onboard pressure sensing and flushing capability. To date, the system concept of operations was demonstrated with tungsten hexafluoride that showed the active vacuum pump with multiple cartridges of adsorbing media was viable. Concurrently, the hardened prototype system was developed and tested; removable sample cartridges were developed (the only non-COTS component to date); and preparations were made for uranium tests and a domestic field test.« less

Theoretical and practical aspects of improving the durability of steel reinforcement in transport designs, using passivation and plasticizing chemical additives

NASA Astrophysics Data System (ADS)

Velichko, Evgenij; Talipov, Linar

2017-10-01

The article deals with the problem of steel reinforcement corrosion in reinforced concrete structures exposed to aggressive media, in particular in reinforced concrete construction of transport infrastructure, in snowy areas, and subject to the influence of chlorides contained in applied deicing agents. Basic schemes for preventing the reinforcement corrosion in reinforced-concrete structures have been considered and analyzed. Prospects of primary protection against corrosion of reinforcement by introducing chemical additives with plasticizing/passivating action in a concrete mixture with mixing water have been considered in detail. The physical/chemical mechanism of the protective action of a superplasticizer together with a passivator has been highlighted.

Screen media usage, sleep time and academic performance in adolescents: clustering a self-organizing maps analysis.

PubMed

Peiró-Velert, Carmen; Valencia-Peris, Alexandra; González, Luis M; García-Massó, Xavier; Serra-Añó, Pilar; Devís-Devís, José

2014-01-01

Screen media usage, sleep time and socio-demographic features are related to adolescents' academic performance, but interrelations are little explored. This paper describes these interrelations and behavioral profiles clustered in low and high academic performance. A nationally representative sample of 3,095 Spanish adolescents, aged 12 to 18, was surveyed on 15 variables linked to the purpose of the study. A Self-Organizing Maps analysis established non-linear interrelationships among these variables and identified behavior patterns in subsequent cluster analyses. Topological interrelationships established from the 15 emerging maps indicated that boys used more passive videogames and computers for playing than girls, who tended to use mobile phones to communicate with others. Adolescents with the highest academic performance were the youngest. They slept more and spent less time using sedentary screen media when compared to those with the lowest performance, and they also showed topological relationships with higher socioeconomic status adolescents. Cluster 1 grouped boys who spent more than 5.5 hours daily using sedentary screen media. Their academic performance was low and they slept an average of 8 hours daily. Cluster 2 gathered girls with an excellent academic performance, who slept nearly 9 hours per day, and devoted less time daily to sedentary screen media. Academic performance was directly related to sleep time and socioeconomic status, but inversely related to overall sedentary screen media usage. Profiles from the two clusters were strongly differentiated by gender, age, sedentary screen media usage, sleep time and academic achievement. Girls with the highest academic results had a medium socioeconomic status in Cluster 2. Findings may contribute to establishing recommendations about the timing and duration of screen media usage in adolescents and appropriate sleep time needed to successfully meet the demands of school academics and to improve interventions targeting to affect behavioral change.

Screen Media Usage, Sleep Time and Academic Performance in Adolescents: Clustering a Self-Organizing Maps Analysis

PubMed Central

Peiró-Velert, Carmen; Valencia-Peris, Alexandra; González, Luis M.; García-Massó, Xavier; Serra-Añó, Pilar; Devís-Devís, José

2014-01-01

Screen media usage, sleep time and socio-demographic features are related to adolescents' academic performance, but interrelations are little explored. This paper describes these interrelations and behavioral profiles clustered in low and high academic performance. A nationally representative sample of 3,095 Spanish adolescents, aged 12 to 18, was surveyed on 15 variables linked to the purpose of the study. A Self-Organizing Maps analysis established non-linear interrelationships among these variables and identified behavior patterns in subsequent cluster analyses. Topological interrelationships established from the 15 emerging maps indicated that boys used more passive videogames and computers for playing than girls, who tended to use mobile phones to communicate with others. Adolescents with the highest academic performance were the youngest. They slept more and spent less time using sedentary screen media when compared to those with the lowest performance, and they also showed topological relationships with higher socioeconomic status adolescents. Cluster 1 grouped boys who spent more than 5.5 hours daily using sedentary screen media. Their academic performance was low and they slept an average of 8 hours daily. Cluster 2 gathered girls with an excellent academic performance, who slept nearly 9 hours per day, and devoted less time daily to sedentary screen media. Academic performance was directly related to sleep time and socioeconomic status, but inversely related to overall sedentary screen media usage. Profiles from the two clusters were strongly differentiated by gender, age, sedentary screen media usage, sleep time and academic achievement. Girls with the highest academic results had a medium socioeconomic status in Cluster 2. Findings may contribute to establishing recommendations about the timing and duration of screen media usage in adolescents and appropriate sleep time needed to successfully meet the demands of school academics and to improve interventions targeting to affect behavioral change. PMID:24941009

Evaluating the Relationship between Equilibrium Passive ...

EPA Pesticide Factsheets

This review evaluates passive sampler uptake of hydrophobic organic contaminants (HOCs) as it relates to organism bioaccumulation in the water column and interstitial water. Fifty-five studies were found where both passive samplers and organism bioaccumulation were used to measured water quality. Of these investigations, 19 provided direct comparisons relating passive sampler concentrations and organism bioaccumulation. Passive sampling polymers included in the review were: low density polyethylene (LDPE); polyoxymethylene (POM); and polydimethylsiloxane (PDMS), and organisms ranged from polychaetes and oligochaetes to bivalves, aquatic insects, and gastropods. Log-linear regressions correlating bioaccumulation (CL) and passive sampler concentration (CPS) were used to assess the strength of observed relationships. In general, the passive sampler concentrations resulted in statistically-significant, logarithmic, predictive relationships, most of which were within one to two orders of magnitude of measured bioaccumulation. Overall, bioaccumulation values were greater than passive sampler concentrations. A mean ratio of CL to CPS was 10.8 ± 18.4 (n = 609) for available data. Given that all studies presented resulted in a strong CL versus CPS relationship suggests that using passive sampling as a surrogate for organism bioaccumulation is viable when biomonitoring organisms are not available. Passive sampling based measurements can provide useful information for ma

Alternating Current Delivered into the Scala Media Alters Sound Pressure at the Eardrum

NASA Astrophysics Data System (ADS)

Hubbard, Allyn E.; Mountain, David C.

1983-11-01

Alternating current delivered into the scala media of the gerbil cochlea modulates the amplitude of a test tone measured near the eardrum. Variations in the electromechanical effect with acoustic stimulus parameters and observed physiological vulnerability suggest that cochlear hair cells are the biophysical origin of the process. Cochlear hair cells have traditionally been thought of as passive receptor cells, but they may play an active role in cochlear micromechanics.

Selecting Performance Reference Compounds (PRCS)for Polyethylene Passive Samplers Deployed at Contaminated Sediment Sites

EPA Science Inventory

Use of equilibrium passive samplers for performing aquatic environmental monitoring at contaminated sediment sites, including Superfund sites, is becoming more common. However, a current challenge in passive sampling is determining when equilibrium is achieved between the sampl...

A passivity criterion for sampled-data bilateral teleoperation systems.

PubMed

Jazayeri, Ali; Tavakoli, Mahdi

2013-01-01

A teleoperation system consists of a teleoperator, a human operator, and a remote environment. Conditions involving system and controller parameters that ensure the teleoperator passivity can serve as control design guidelines to attain maximum teleoperation transparency while maintaining system stability. In this paper, sufficient conditions for teleoperator passivity are derived for when position error-based controllers are implemented in discrete-time. This new analysis is necessary because discretization causes energy leaks and does not necessarily preserve the passivity of the system. The proposed criterion for sampled-data teleoperator passivity imposes lower bounds on the teleoperator's robots dampings, an upper bound on the sampling time, and bounds on the control gains. The criterion is verified through simulations and experiments.

Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium

NASA Astrophysics Data System (ADS)

Samantaroy, Pradeep Kumar; Suresh, Girija; Paul, Ranita; Kamachi Mudali, U.; Raj, Baldev

2011-11-01

Nickel based alloys are candidate materials for the storage of high level waste (HLW) generated from reprocessing of spent nuclear fuel. In the present investigation Alloy 690 and Alloy 693 are assessed by potentiodynamic anodic polarization technique for their corrosion behavior in 3 M HNO 3, 3 M HNO 3 containing simulated HLW and in chloride medium. Both the alloys were found to possess good corrosion resistance in both the media at ambient condition. Microstructural examination was carried out by SEM for both the alloys after electrolytic etching. Compositional analysis of the passive film formed on the alloys in 3 M HNO 3 and 3 M HNO 3 with HLW was carried out by XPS. The surface of Alloy 690 and Alloy 693, both consists of a thin layer of oxide of Ni, Cr, and Fe under passivation in both the media. The results of investigation are presented in the paper.

Evaluation of spot and passive sampling for monitoring, flux estimation and risk assessment of pesticides within the constraints of a typical regulatory monitoring scheme.

PubMed

Zhang, Zulin; Troldborg, Mads; Yates, Kyari; Osprey, Mark; Kerr, Christine; Hallett, Paul D; Baggaley, Nikki; Rhind, Stewart M; Dawson, Julian J C; Hough, Rupert L

2016-11-01

In many agricultural catchments of Europe and North America, pesticides occur at generally low concentrations with significant temporal variation. This poses several challenges for both monitoring and understanding ecological risks/impacts of these chemicals. This study aimed to compare the performance of passive and spot sampling strategies given the constraints of typical regulatory monitoring. Nine pesticides were investigated in a river currently undergoing regulatory monitoring (River Ugie, Scotland). Within this regulatory framework, spot and passive sampling were undertaken to understand spatiotemporal occurrence, mass loads and ecological risks. All the target pesticides were detected in water by both sampling strategies. Chlorotoluron was observed to be the dominant pesticide by both spot (maximum: 111.8ng/l, mean: 9.35ng/l) and passive sampling (maximum: 39.24ng/l, mean: 4.76ng/l). The annual pesticide loads were estimated to be 2735g and 1837g based on the spot and passive sampling data, respectively. The spatiotemporal trend suggested that agricultural activities were the primary source of the compounds with variability in loads explained in large by timing of pesticide applications and rainfall. The risk assessment showed chlorotoluron and chlorpyrifos posed the highest ecological risks with 23% of the chlorotoluron spot samples and 36% of the chlorpyrifos passive samples resulting in a Risk Quotient greater than 0.1. This suggests that mitigation measures might need to be taken to reduce the input of pesticides into the river. The overall comparison of the two sampling strategies supported the hypothesis that passive sampling tends to integrate the contaminants over a period of exposure and allows quantification of contamination at low concentration. The results suggested that within a regulatory monitoring context passive sampling was more suitable for flux estimation and risk assessment of trace contaminants which cannot be diagnosed by spot sampling and for determining if long-term average concentrations comply with specified standards. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of soil water saturation on sampling equilibrium and kinetics of selected polycyclic aromatic hydrocarbons.

PubMed

Kim, Pil-Gon; Roh, Ji-Yeon; Hong, Yongseok; Kwon, Jung-Hwan

2017-10-01

Passive sampling can be applied for measuring the freely dissolved concentration of hydrophobic organic chemicals (HOCs) in soil pore water. When using passive samplers under field conditions, however, there are factors that might affect passive sampling equilibrium and kinetics, such as soil water saturation. To determine the effects of soil water saturation on passive sampling, the equilibrium and kinetics of passive sampling were evaluated by observing changes in the distribution coefficient between sampler and soil (K sampler/soil ) and the uptake rate constant (k u ) at various soil water saturations. Polydimethylsiloxane (PDMS) passive samplers were deployed into artificial soils spiked with seven selected polycyclic aromatic hydrocarbons (PAHs). In dry soil (0% water saturation), both K sampler/soil and k u values were much lower than those in wet soils likely due to the contribution of adsorption of PAHs onto soil mineral surfaces and the conformational changes in soil organic matter. For high molecular weight PAHs (chrysene, benzo[a]pyrene, and dibenzo[a,h]anthracene), both K sampler/soil and k u values increased with increasing soil water saturation, whereas they decreased with increasing soil water saturation for low molecular weight PAHs (phenanthrene, anthracene, fluoranthene, and pyrene). Changes in the sorption capacity of soil organic matter with soil water content would be the main cause of the changes in passive sampling equilibrium. Henry's law constant could explain the different behaviors in uptake kinetics of the selected PAHs. The results of this study would be helpful when passive samplers are deployed under various soil water saturations. Copyright © 2017 Elsevier Ltd. All rights reserved.

THE IMPACT OF PASSIVE SAMPLING METHODOLOGIES USED IN THE DEARS

EPA Science Inventory

This abstract details the use of passive sampling methodologies in the Detroit Exposure and Aerosol Research Study (DEARS). A discussion about the utility of various gas-phase passive samplers used in the study will be described along with examples of field data measurements empl...

Evaluating the Relationship between Equilibrium Passive ...

EPA Pesticide Factsheets

This Critcal Review evaluates passive sampler uptake of hydrophobic organic contaminants (HOCs) in water column and interstitial water exposures as a surrogate for organism bioaccumulation. Fifty-seven studies were found where both passive sampler uptake and organism bioaccumulation were measured and 19 of these investigations provided direct comparisons relating passive sampler uptake and organism bioaccumulation. Polymers compared included low-density polyethylene (LDPE), polyoxymethylene (POM), and polydimethylsiloxane (PDMS), and organisms ranged from polychaetes and oligochaetes to bivalves, aquatic insects, and gastropods. Regression equations correlating bioaccumulation (CL) and passive sampler uptake (CPS) were used to assess the strength of observed relationships. Passive sampling based concentrations resulted in log–log predictive relationships, most of which were within one to 2 orders of magnitude of measured bioaccumulation. Mean coefficients of determination (r2) for LDPE, PDMS, and POM were 0.68, 0.76, and 0.58, respectively. For the available raw, untransformed data, the mean ratio of CL and CPS was 10.8 ± 18.4 (n = 609). Using passive sampling as a surrogate for organism bioaccumulation is viable when biomonitoring organisms are not available. Passive sampling based estimates of bioaccumulation provide useful information for making informed decisions about the bioavailability of HOCs. This review evaluates passive sampler uptake of hydrophobi

Focal Plane Array Technology for IR Detectors

DTIC Science & Technology

1996-06-01

samples are determined. Our results on p-(HgCd)Te coated with passivation layers are evident from Figs 3.1 and 3.2. In the first case (native sulphides ...samples are evident from the Table II. We studied influence of (a) atmosphere, (b) ZnS passivation, (c) native sulphides + ZnS passivation. The (HgCd)Te...native sulphides + ZnS, full symbols RH<O, open symbols RH>O. 10 5 6408A3 10- 010o E 102 000 2 days after passivation 10 : 80 days after passivation 0

Comparative study of passively Q-switched c-cut Nd:YVO4/Nd:YAG lasers based on CVD graphene and controlled operation

NASA Astrophysics Data System (ADS)

Jia, Fuqiang; Liu, Pei; Li, Kang; Chen, Hao; Cheng, Yongjie; Cai, Zhiping; Copner, Nigel

2017-07-01

In this paper, a comparative study of passively Q-switched c-cut Nd:YVO4 and Nd:YAG lasers using four different layers CVD graphene as saturable absorber are demonstrated experimentally for the first time. Moreover, it is successful to accurately control the frequency of repetition rates of the CVD graphern passively Q-switched lasers by pulsed pump. The impacts of laser materials, layers of CVD graphene and cavity length on output parameters are investigated intensively as well, the result shows that the c-cut Nd:YVO4 is a promising laser media compared with Nd:YAG for passively Q-switched lasers based on CVD graphene, as it has better performances in pulse width, pulse energy and peak power. A useful and cost-effective way to generate stable pulsed lasers by CVD graphene or other novel saturable materials are demonstrated.

Using bioavailability to assess contaminated sediment risk: Passive sampling and Pore Water Remedial Guidelines (PWRGs)

EPA Science Inventory

Hosted by the Contaminated Sediment Forum, this half-day course will introduce the RPM to the use of passive samplers to assess bioavailability and in ecological risk assessment. Passive sampling devices (PSD) are a technology with growing acceptance for measuring porewater conce...

New Media Vision for IYA

NASA Astrophysics Data System (ADS)

Gay, P. L.; Koppelman, M.

2008-11-01

The International Year of Astronomy New Media Committee seeks to provide and promote online astronomy experiences in the places that people work, play and learn; create content that will expose people to astronomy, provide them regular content, and create special opportunities for learning; distribute content for active (pull) and passive (push) channels and through guerilla marketing technique; use a diverse suite of technologies to reach people on multiple platforms and in diverse online settings. To make these goals a reality we have brought together a diverse group of astronomy new media practitioners to both mentor grass roots efforts and spearhead national initiatives. You are invited to partner you programs with the New Media Task Group. In this paper we lay out are goals and define our vision.

Overview of the US EPA/SERDP/ESTCP: Laboratory, Field ...

EPA Pesticide Factsheets

Passive sampling can be used for applications at contaminated sediment sites including performing assessments of contaminant bioavailability (i.e., freely dissolved concentration (Cfree)), conducting remedial investigations and feasibility studies, and assessing the potential for contaminant bioaccumulation. Previous research articles and documents have discussed many aspects of passive sampling however no definitive guidance on the laboratory, field and analytical procedures for using passive sampling at contaminated sediment sites has been provided. The document discussed in this presentation provides passive sampler users with the guidance necessary to apply the technology to evaluate contaminated sediments. Contaminants discussed include polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and the metals, cadmium, copper, nickel, lead and zinc. The document is divided into sections including discussions of different types of samplers used commonly in the United States, the selection and use of performance reference compounds (PRCs), the extraction and instrumental analysis of passive samplers, data analysis and quality assurance/quality control, and a list of passive sampling related references. The document is not intended to serve as a series of standard operating procedures (SOPs) but rather seeks to provide users with the information needed to develop their own SOPs. The document also includes the names of selected passive sam

Shaping complex microwave fields in reverberating media with binary tunable metasurfaces

PubMed Central

Kaina, Nadège; Dupré, Matthieu; Lerosey, Geoffroy; Fink, Mathias

2014-01-01

In this article we propose to use electronically tunable metasurfaces as spatial microwave modulators. We demonstrate that like spatial light modulators, which have been recently proved to be ideal tools for controlling light propagation through multiple scattering media, spatial microwave modulators can efficiently shape in a passive way complex existing microwave fields in reverberating environments with a non-coherent energy feedback. Unlike in free space, we establish that a binary-only phase state tunable metasurface allows a very good control over the waves, owing to the random nature of the electromagnetic fields in these complex media. We prove in an everyday reverberating medium, that is, a typical office room, that a small spatial microwave modulator placed on the walls can passively increase the wireless transmission between two antennas by an order of magnitude, or on the contrary completely cancel it. Interestingly and contrary to free space, we show that this results in an isotropic shaped microwave field around the receiving antenna, which we attribute again to the reverberant nature of the propagation medium. We expect that spatial microwave modulators will be interesting tools for fundamental physics and will have applications in the field of wireless communications. PMID:25331498

Marijuana advertising exposure among current marijuana users in the U.S

PubMed Central

Krauss, Melissa J.; Sowles, Shaina J.; Sehi, Auriann; Spitznagel, Edward L.; Berg, Carla J.; Bierut, Laura J.; Cavazos-Rehg, Patricia A.

2017-01-01

Background Little is known about marijuana advertising exposure among users in the U.S. We examined the prevalence of advertising exposure among young adult marijuana users through traditional and new media, and identified characteristics associated with seeking advertisements. Methods We conducted a cross-sectional survey of 18–34 year-old past-month marijuana users in the U.S. using a pre-existing online panel (N=742). The survey queried about passively viewing and actively seeking marijuana advertisements in the past month, sources of advertisements, and marijuana use characteristics. Results Over half of participants were exposed to marijuana advertising in the past month (28% passively observed advertisements, 26% actively sought advertisements). Common sources for observing advertisements were digital media (i.e., social media, online, text/emails; 77%). Similarly, those actively seeking advertisements often used Internet search engines (65%) and social media (53%). Seeking advertisements was more common among those who used medically (41% medical only, 36% medical and recreational) than recreational users (18%), who used concentrates or edibles (44% and 43%) compared to those who did not (20% and 19%), and who used multiple times per day (33%) compared to those who did not (19%) (all p<0.01). Conclusions Exposure to marijuana advertising among users is common, especially via digital media, and is associated with medical use, heavier use, and use of novel products with higher THC concentrations (i.e., concentrates) or longer intoxication duration (i.e., edibles). As the U.S. marijuana policy landscape changes, it will be important to examine potential causal associations between advertising exposure and continuation or frequency/quantity of use. PMID:28365173

Application of passive sampling for measuring dissolved concentrations of organic contaminants in the water column at three marine superfund sites.

PubMed

Burgess, Robert M; Lohmann, Rainer; Schubauer-Berigan, Joseph P; Reitsma, Pamela; Perron, Monique M; Lefkovitz, Lisa; Cantwell, Mark G

2015-08-01

Currently, there is an effort under way to encourage remedial project managers at contaminated sites to use passive sampling to collect freely dissolved concentrations (Cfree ) of hydrophobic organic contaminants to improve site assessments. The objective of the present study was to evaluate the use of passive sampling for measuring water column Cfree for several hydrophobic organic contaminants at 3 US Environmental Protection Agency Superfund sites. Sites investigated included New Bedford Harbor (New Bedford, MA, USA), Palos Verdes Shelf (Los Angeles, CA, USA), and Naval Station Newport (Newport, RI, USA); and the passive samplers evaluated were polyethylene, polydimethylsiloxane-coated solid-phase microextraction fibers, semipermeable membrane devices, and polyoxymethylene. In general, the different passive samplers demonstrated good agreement, with Cfree values varying by a factor of 2 to 3. Further, at New Bedford Harbor, where conventional water sample concentrations were also measured (i.e., grab samples), passive sampler-based Cfree values agreed within a factor of 2. These findings suggest that all of the samplers were experiencing and measuring similar Cfree during their respective deployments. Also, at New Bedford Harbor, a strong log-linear, correlative, and predictive relationship was found between polyethylene passive sampler accumulation and lipid-normalized blue mussel bioaccumulation of polychlorinated biphenyls (r(2)  = 0.92, p < 0.05). The present study demonstrates the utility of passive sampling for generating scientifically accurate water column Cfree values, which is critical for making informed environmental management decisions at contaminated sediment sites. Published 2015 SETAC. This article is a US Government work and is in the public domain in the USA.

Influence of point defects on the near edge structure of hexagonal boron nitride

NASA Astrophysics Data System (ADS)

McDougall, Nicholas L.; Partridge, Jim G.; Nicholls, Rebecca J.; Russo, Salvy P.; McCulloch, Dougal G.

2017-10-01

Hexagonal boron nitride (hBN) is a wide-band-gap semiconductor with applications including gate insulation layers in graphene transistors, far-ultraviolet light emitting devices and as hydrogen storage media. Due to its complex microstructure, defects in hBN are challenging to identify. Here, we combine x-ray absorption near edge structure (XANES) spectroscopy with ab initio theoretical modeling to identify energetically favorable defects. Following annealing of hBN samples in vacuum and oxygen, the B and N K edges exhibited angular-dependent peak modifications consistent with in-plane defects. Theoretical calculations showed that the energetically favorable defects all produce signature features in XANES. Comparing these calculations with experiments, the principle defects were attributed to substitutional oxygen at the nitrogen site, substitutional carbon at the boron site, and hydrogen passivated boron vacancies. Hydrogen passivation of defects was found to significantly affect the formation energies, electronic states, and XANES. In the B K edge, multiple peaks above the major 1 s to π* peak occur as a result of these defects and the hydrogen passivated boron vacancy produces the frequently observed doublet in the 1 s to σ* transition. While the N K edge is less sensitive to defects, features attributable to substitutional C at the B site were observed. This defect was also calculated to have mid-gap states in its band structure that may be responsible for the 4.1-eV ultraviolet emission frequently observed from this material.

On the Ni-Ion release rate from surfaces of binary NiTi shape memory alloys

NASA Astrophysics Data System (ADS)

Ševčíková, Jana; Bártková, Denisa; Goldbergová, Monika; Kuběnová, Monika; Čermák, Jiří; Frenzel, Jan; Weiser, Adam; Dlouhý, Antonín

2018-01-01

The study is focused on Ni-ion release rates from NiTi surfaces exposed in the cell culture media and human vascular endothelial cell (HUVEC) culture environments. The NiTi surface layers situated in the depth of 70 μm below a NiTi oxide scale are affected by interactions between the NiTi alloys and the bio-environments. The finding was proved with use of inductively coupled plasma mass spectrometry and electron microscopy experiments. As the exclusive factor controlling the Ni-ion release rates was not only thicknesses of the oxide scale, but also the passivation depth, which was two-fold larger. Our experimental data strongly suggested that some other factors, in addition to the Ni concentration in the oxide scale, admittedly hydrogen soaking deep below the oxide scale, must be taken into account in order to rationalize the concentrations of Ni-ions released into the bio-environments. The suggested role of hydrogen as the surface passivation agent is also in line with the fact that the Ni-ion release rates considerably decrease in NiTi samples that were annealed in controlled hydrogen atmospheres prior to bio-environmental exposures.

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Dara Entekhabi, SMAP science team lead, Massachusetts Institute of Technology, center, speaks during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Dara Entekhabi, SMAP science team lead, Massachusetts Institute of Technology, speaks during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

A novel active-passive sampling approach for measuring time-averaged concentrations of pollutants in water.

PubMed

Amato, Elvio D; Covaci, Adrian; Town, Raewyn M; Hereijgers, Jonas; Bellekens, Ben; Giacometti, Valentina; Breugelmans, Tom; Weyn, Maarten; Dardenne, Freddy; Bervoets, Lieven; Blust, Ronny

2018-06-14

Passive sampling with in situ devices offers several advantages over traditional sampling methods (i.e., discrete spot sampling), however, data interpretation from conventional passive samplers is hampered by difficulties in estimating the thickness of the diffusion layer at the sampler/medium interface (δ), often leading to inaccurate determinations of target analyte concentrations. In this study, the performance of a novel device combining active and passive sampling was investigated in the laboratory. The active-passive sampling (APS) device is comprised of a diffusion cell fitted with a pump and a flowmeter. Three receiving phases traditionally used in passive sampling devices (i.e., chelex resin, Oasis HLB, and silicone rubber), were incorporated in the diffusion cell and allowed the simultaneous accumulation of cationic metals, polar, and non-polar organic compounds, respectively. The flow within the diffusion cell was accurately controlled and monitored, and, combined with diffusion coefficients measurements, enabled the average δ to be estimated. Strong agreement between APS and time-averaged total concentrations measured in discrete water samples was found for most of the substances investigated. Accuracies for metals ranged between 87 and 116%, except Cu and Pb (∼50%), whilst accuracies between 64 and 101%, and 92 and 151% were achieved for polar and non-polar organic compounds, respectively. These results indicate that, via a well-defined in situ preconcentration step, the proposed APS approach shows promise for monitoring the concentration of a range of pollutants in water. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of recruitment methods for a trial targeting childhood obesity: Families for Health randomised controlled trial.

PubMed

Fleming, J; Kamal, A; Harrison, E; Hamborg, T; Stewart-Brown, S; Thorogood, M; Griffiths, F; Robertson, W

2015-11-25

Recruitment to trials evaluating the effectiveness of childhood obesity management interventions is challenging. We report our experience of recruitment to the Families for Health study, a randomised controlled trial evaluating the effectiveness of a family-based community programme for children aged 6-11 years, versus usual care. We evaluated the effectiveness of active recruitment (contacting eligible families directly) versus passive recruitment (informing the community through flyers, public events, media). Initial approaches included passive recruitment via the media (newspapers and radio) and two active recruitment methods: National Child Measurement Programme (letters to families with overweight children) and referrals from health-care professionals. With slow initial recruitment, further strategies were employed, including active (e.g. targeted letters from general practices) and passive (e.g. flyers, posters and public events) methods. At first enquiry from a potential participant, families were asked where they heard about the study. Further quantitative (questionnaire) and qualitative data (one-to-one interviews with parents/carers), were collected from recruited families at baseline and 3-month follow-up and included questions about recruitment. In total, 194 families enquired about Families for Health, and 115 (59.3 %) were recruited and randomised. Active recruitment yielded 85 enquiries, with 43 families recruited (50.6 %); passive recruitment yielded 99 enquiries with 72 families recruited (72.7 %). Information seen at schools or GP surgeries accounted for over a quarter of enquiries (28.4 %) and over a third (37.4 %) of final recruitment. Eight out of ten families who enquired this way were recruited. Media-led enquiries were low (5 %), but all were recruited. Children of families recruited actively were more likely to be Asian or mixed race. Despite extensive recruitment methods, the trial did not recruit as planned, and was awarded a no-cost extension to complete the 12-month follow-up. The higher number of participants recruited through passive methods may be due to the large number of potential participants these methods reached and because participants may see the information more than once. Recruiting to a child obesity treatment study is complex and it is advisable to use multiple recruitment strategies, some aiming at blanket coverage and some targeted at families with children who are overweight. Current Controlled Trials ISRCTN45032201 (Date: 18 August 2011).

Multipurpose Sediment Passive Sampler with Improved Tissue Mimicry to Measure the Bioavailable Fraction

DTIC Science & Technology

2016-11-01

sieved to a 35-60 mesh particle size (250-500 μm) for testing. Sampler construction. Media (500 mg) was placed in 150 mesh stainless steel which...ASP400P), and 5% kaolin clay (ASP900) by weight into a cement mixer. The sediment was mixed for 1.5 hr to 10 ensure homogeneity. This resulted in...fabricated using stainless steel mesh and 500 mg of the identified media blend. A manufacturing space and process was established for Osorb enhanced

Reactive granular optics for passive tracking of the sun

NASA Astrophysics Data System (ADS)

Frenkel, I.; Niv, A.

2017-08-01

The growing need for cost-effective renewable energy sources is hampered by the stagnation in solar cell technology, thus preventing a substantial reduction in the module and energy-production price. Lowering the energy-production cost could be achieved by using modules with efficiency. One of the possible means for increasing the module efficiency is concentrated photovoltaics (CPV). CPV, however, requires complex and accurate active tracking of the sun that reduces much of its cost-effectiveness. Here, we propose a passive tracking scheme based on a reactive optical device. The optical reaction is achieved by a new kind of light activated mechanical force that acts on micron-sized particles. This optical force allows the formation of granular disordered optical media that can be switched from being opaque to become transparent based on the intensity of light it interacts with. Such media gives rise to an efficient passive tracking scheme that when combined with an external optical cavity forms a new solar power conversion approach. Being external to the cell itself, this approach is indifferent to the type of semiconducting material that is used, as well as to other aspects of the cell design. This, in turn, liberates the cell layout from its optical constraints thus paving the way to higher efficiencies at lower module price.

Divergent Mechanisms for Passive Pneumococcal Resistance to β-Lactam Antibiotics in the Presence of Haemophilus influenzae

PubMed Central

Weimer, Kristin E.D.; Juneau, Richard A.; Murrah, Kyle A.; Pang, Bing; Armbruster, Chelsie E.; Richardson, Stephen H.

2011-01-01

Background. Otitis media, for which antibiotic treatment failure is increasingly common, is a leading pediatric public health problem. Methods. In vitro and in vivo studies using the chinchilla model of otitis media were performed using a β-lactamase-producing strain of nontypeable Haemophilus influenzae (NTHi 86-028NP) and an isogenic mutant deficient in β-lactamase production (NTHi 86-028NP bla) to define the roles of biofilm formation and β-lactamase production in antibiotic resistance. Coinfection studies were done with Streptococcus pneumoniae to determine if NTHi provides passive protection by means of β-lactamase production, biofilm formation, or both. Results. NTHi 86-028NP bla was resistant to amoxicillin killing in biofilm studies in vitro; however, it was cleared by amoxicillin treatment in vivo, whereas NTHi 86-028NP was unaffected in either system. NTHi 86-028NP protected pneumococcus in vivo in both the effusion fluid and bullar homogenate. NTHi 86-028NP bla and pneumococcus were both recovered from the surface-associated bacteria of amoxicillin-treated animals; only NTHi 86-028NP bla was recovered from effusion. Conclusions. Based on these studies, we conclude that NTHi provides passive protection for S. pneumoniae in vivo through 2 distinct mechanisms: production of β-lactamase and formation of biofilm communities. PMID:21220774

Divergent mechanisms for passive pneumococcal resistance to β-lactam antibiotics in the presence of Haemophilus influenzae.

PubMed

Weimer, Kristin E D; Juneau, Richard A; Murrah, Kyle A; Pang, Bing; Armbruster, Chelsie E; Richardson, Stephen H; Swords, W Edward

2011-02-15

Otitis media, for which antibiotic treatment failure is increasingly common, is a leading pediatric public health problem. In vitro and in vivo studies using the chinchilla model of otitis media were performed using a β-lactamase-producing strain of nontypeable Haemophilus influenzae (NTHi 86-028NP) and an isogenic mutant deficient in β-lactamase production (NTHi 86-028NP bla) to define the roles of biofilm formation and β-lactamase production in antibiotic resistance. Coinfection studies were done with Streptococcus pneumoniae to determine if NTHi provides passive protection by means of β-lactamase production, biofilm formation, or both. NTHi 86-028NP bla was resistant to amoxicillin killing in biofilm studies in vitro; however, it was cleared by amoxicillin treatment in vivo, whereas NTHi 86-028NP was unaffected in either system. NTHi 86-028NP protected pneumococcus in vivo in both the effusion fluid and bullar homogenate. NTHi 86-028NP bla and pneumococcus were both recovered from the surface-associated bacteria of amoxicillin-treated animals; only NTHi 86-028NP bla was recovered from effusion. Based on these studies, we conclude that NTHi provides passive protection for S. pneumoniae in vivo through 2 distinct mechanisms: production of β-lactamase and formation of biofilm communities.

Evaluating the Relationship between Equilibrium Passive ...

EPA Pesticide Factsheets

This review evaluates passive sampler uptake of hydrophobic organic contaminants (HOCs) in water column and interstitial water exposures as a surrogate for organism bioaccumulation. Fifty-four studies were found where both passive sampler uptake and organism bioaccumulation were measured and 19 of these investigations provided direct comparisons relating passive sampler uptake and organism bioaccumulation. Polymers compared included low density polyethylene (LDPE), polyoxymethylene (POM), and polydimethylsiloxane (PDMS), and organisms ranged from polychaetes and oligochaetes to bivalves, aquatic insects, and gastropods. Regression equations correlating bioaccumulation (CL) and passive sampler uptake (CPS) were used to assess the strength of observed relationships. Passive sampling based concentrations resulted in logarithmic predictive relationships, most of which were within one to two orders of magnitude of measured bioaccumulation. Mean coefficients of determination (r2) for LDPE, PDMS and POM were 0.68, 0.76 and 0.58, respectively. For the available raw data, the mean ratio of CL and CPS was 10.8 ± 18.4 (n = 609). This review concludes that in many applications passive sampling may serve as a reliable surrogate for biomonitoring organisms when biomonitoring organisms are not available. When applied properly, passive sampling based estimates of bioaccumulation provide useful information for making informed decisions about the bioavailability of HOCs

Limitations of Reverse Polyethylene Samplers (RePES) for Evaluating Toxicity of Field Contaminated Sediments

EPA Science Inventory

Passive samplers are used to measure dissolved nonionic organic contaminants (NOCs) in environmental media. More recently, reverse polyethylene samplers (RePES) have been used with spiked sediments to recreate interstitial water exposure concentrations and observed toxicity. In...

Evaluation of the availability of bound analyte for passive sampling in the presence of mobile binding matrix.

PubMed

Xu, Jianqiao; Huang, Shuyao; Jiang, Ruifen; Cui, Shufen; Luan, Tiangang; Chen, Guosheng; Qiu, Junlang; Cao, Chenyang; Zhu, Fang; Ouyang, Gangfeng

2016-04-21

Elucidating the availability of the bound analytes for the mass transfer through the diffusion boundary layers (DBLs) adjacent to passive samplers is important for understanding the passive sampling kinetics in complex samples, in which the lability factor of the bound analyte in the DBL is an important parameter. In this study, the mathematical expression of lability factor was deduced by assuming a pseudo-steady state during passive sampling, and the equation indicated that the lability factor was equal to the ratio of normalized concentration gradients between the bound and free analytes. Through the introduction of the mathematical expression of lability factor, the modified effective average diffusion coefficient was proven to be more suitable for describing the passive sampling kinetics in the presence of mobile binding matrixes. Thereafter, the lability factors of the bound polycyclic aromatic hydrocarbons (PAHs) with sodium dodecylsulphate (SDS) micelles as the binding matrixes were figured out according to the improved theory. The lability factors were observed to decrease with larger binding ratios and smaller micelle sizes, and were successfully used to predict the mass transfer efficiencies of PAHs through DBLs. This study would promote the understanding of the availability of bound analytes for passive sampling based on the theoretical improvements and experimental assessments. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative passive soil vapor sampling for VOCs--Part 4: Flow-through cell.

PubMed

McAlary, Todd; Groenevelt, Hester; Seethapathy, Suresh; Sacco, Paolo; Crump, Derrick; Tuday, Michael; Schumacher, Brian; Hayes, Heidi; Johnson, Paul; Parker, Louise; Górecki, Tadeusz

2014-05-01

This paper presents a controlled experiment comparing several quantitative passive samplers for monitoring concentrations of volatile organic compound (VOC) vapors in soil gas using a flow-through cell. This application is simpler than conventional active sampling using adsorptive tubes because the flow rate does not need to be precisely measured and controlled, which is advantageous because the permeability of subsurface materials affects the flow rate and the permeability of geologic materials is highly variable. Using passive samplers in a flow-through cell, the flow rate may not need to be known exactly, as long as it is sufficient to purge the cell in a reasonable time and minimize any negative bias attributable to the starvation effect. An experiment was performed in a 500 mL flow-through cell using a two-factor, one-half fraction fractional factorial test design with flow rates of 80, 670 and 930 mL min(-1) and sample durations of 10, 15 and 20 minutes for each of five different passive samplers (passive Automatic Thermal Desorption Tube, Radiello®, SKC Ultra, Waterloo Membrane Sampler™ and 3M™ OVM 3500). A Summa canister was collected coincident with each passive sampler and analyzed by EPA Method TO-15 to provide a baseline for comparison of the passive sampler concentrations. The passive sampler concentrations were within a factor of 2 of the Summa canister concentrations in 32 of 35 cases. Passive samples collected at the low flow rate and short duration showed low concentrations, which is likely attributable to insufficient purging of the cell after sampler placement.

Comparison of sampling methodologies for nutrient monitoring in streams: uncertainties, costs and implications for mitigation

NASA Astrophysics Data System (ADS)

Audet, J.; Martinsen, L.; Hasler, B.; de Jonge, H.; Karydi, E.; Ovesen, N. B.; Kronvang, B.

2014-07-01

Eutrophication of aquatic ecosystems caused by excess concentrations of nitrogen and phosphorus may have harmful consequences for biodiversity and poses a health risk to humans via the water supplies. Reduction of nitrogen and phosphorus losses to aquatic ecosystems involves implementation of costly measures, and reliable monitoring methods are therefore essential to select appropriate mitigation strategies and to evaluate their effects. Here, we compare the performances and costs of three methodologies for the monitoring of nutrients in rivers: grab sampling, time-proportional sampling and passive sampling using flow proportional samplers. Assuming time-proportional sampling to be the best estimate of the "true" nutrient load, our results showed that the risk of obtaining wrong total nutrient load estimates by passive samplers is high despite similar costs as the time-proportional sampling. Our conclusion is that for passive samplers to provide a reliable monitoring alternative, further development is needed. Grab sampling was the cheapest of the three methods and was more precise and accurate than passive sampling. We conclude that although monitoring employing time-proportional sampling is costly, its reliability precludes unnecessarily high implementation expenses.

Comparison of sampling methodologies for nutrient monitoring in streams: uncertainties, costs and implications for mitigation

NASA Astrophysics Data System (ADS)

Audet, J.; Martinsen, L.; Hasler, B.; de Jonge, H.; Karydi, E.; Ovesen, N. B.; Kronvang, B.

2014-11-01

Eutrophication of aquatic ecosystems caused by excess concentrations of nitrogen and phosphorus may have harmful consequences for biodiversity and poses a health risk to humans via water supplies. Reduction of nitrogen and phosphorus losses to aquatic ecosystems involves implementation of costly measures, and reliable monitoring methods are therefore essential to select appropriate mitigation strategies and to evaluate their effects. Here, we compare the performances and costs of three methodologies for the monitoring of nutrients in rivers: grab sampling; time-proportional sampling; and passive sampling using flow-proportional samplers. Assuming hourly time-proportional sampling to be the best estimate of the "true" nutrient load, our results showed that the risk of obtaining wrong total nutrient load estimates by passive samplers is high despite similar costs as the time-proportional sampling. Our conclusion is that for passive samplers to provide a reliable monitoring alternative, further development is needed. Grab sampling was the cheapest of the three methods and was more precise and accurate than passive sampling. We conclude that although monitoring employing time-proportional sampling is costly, its reliability precludes unnecessarily high implementation expenses.

Uncertainties in monitoring of SVOCs in air caused by within-sampler degradation during active and passive air sampling

NASA Astrophysics Data System (ADS)

Melymuk, Lisa; Bohlin-Nizzetto, Pernilla; Prokeš, Roman; Kukučka, Petr; Přibylová, Petra; Vojta, Šimon; Kohoutek, Jiří; Lammel, Gerhard; Klánová, Jana

2017-10-01

Degradation of semivolatile organic compounds (SVOCs) occurs naturally in ambient air due to reactions with reactive trace gases (e.g., ozone, NOx). During air sampling there is also the possibility for degradation of SVOCs within the air sampler, leading to underestimates of ambient air concentrations. We investigated the possibility of this sampling artifact in commonly used active and passive air samplers for seven classes of SVOCs, including persistent organic pollutants (POPs) typically covered by air monitoring programs, as well as SVOCs of emerging concern. Two active air samplers were used, one equipped with an ozone denuder and one without, to compare relative differences in mass of collected compounds. Two sets of passive samplers were also deployed to determine the influence of degradation during longer deployment times in passive sampling. In active air samplers, comparison of the two sampling configurations suggested degradation of particle-bound polycyclic aromatic hydrocarbons (PAHs), with concentrations up to 2× higher in the denuder-equipped sampler, while halogenated POPs did not have clear evidence of degradation. In contrast, more polar, reactive compounds (e.g., organophosphate esters and current use pesticides) had evidence of losses in the sampler with denuder. This may be caused by the denuder itself, suggesting sampling bias for these compounds can be created when typical air sampling apparatuses are adapted to limit degradation. Passive air samplers recorded up to 4× higher concentrations when deployed for shorter consecutive sampling periods, suggesting that within-sampler degradation may also be relevant in passive air monitoring programs.

Evaluation of passive diffusion bag and dialysis samplers in selected wells at Hickam Air Force Base, Hawaii, July 2001

USGS Publications Warehouse

Vroblesky, Don A.; Pravecek, Tasha

2002-01-01

Field comparisons of chemical concentrations obtained from dialysis samplers, passive diffusion bag samplers, and low-flow samplers showed generally close agreement in most of the 13 wells tested during July 2001 at Hickam Air Force Base, Hawaii. The data for chloride, sulfate, iron, alkalinity, arsenic, and methane appear to show that the dialysis samplers are capable of accurately collecting a passive sample for these constituents. In general, the comparisons of volatile organic compound concentrations showed a relatively close correspondence between the two different types of diffusion samples and between the diffusion samples and the low-flow samples collected in most wells. Divergence appears to have resulted primarily from the pumping method, either producing a mixed sample or water not characteristic of aquifer water moving through the borehole under ambient conditions. The fact that alkalinity was not detected in the passive diffusion bag samplers, highly alkaline waters without volatilization loss from effervescence, which can occur when a sample is acidified for preservation. Both dialysis and passive diffusion bag samplers are relatively inexpensive and can be deployed rapidly and easily. Passive diffusion bag samplers are intended for sampling volatile organic compounds only, but dialysis samplers can be used to sample both volatile organic compounds and inorganic solutes. Regenerated cellulose dialysis samplers, however, are subject to biodegradation and probably should be deployed no sooner than 2 weeks prior to recovery. 1 U.S. Geological Survey, Columbia, South Carolina. 2 Air Florce Center for Environmental Excellence, San Antionio, Texas.

A simple linear model for estimating ozone AOT40 at forest sites from raw passive sampling data.

PubMed

Ferretti, Marco; Cristofolini, Fabiana; Cristofori, Antonella; Gerosa, Giacomo; Gottardini, Elena

2012-08-01

A rapid, empirical method is described for estimating weekly AOT40 from ozone concentrations measured with passive samplers at forest sites. The method is based on linear regression and was developed after three years of measurements in Trentino (northern Italy). It was tested against an independent set of data from passive sampler sites across Italy. It provides good weekly estimates compared with those measured by conventional monitors (0.85 ≤R(2)≤ 0.970; 97 ≤ RMSE ≤ 302). Estimates obtained using passive sampling at forest sites are comparable to those obtained by another estimation method based on modelling hourly concentrations (R(2) = 0.94; 131 ≤ RMSE ≤ 351). Regression coefficients of passive sampling are similar to those obtained with conventional monitors at forest sites. Testing against an independent dataset generated by passive sampling provided similar results (0.86 ≤R(2)≤ 0.99; 65 ≤ RMSE ≤ 478). Errors tend to accumulate when weekly AOT40 estimates are summed to obtain the total AOT40 over the May-July period, and the median deviation between the two estimation methods based on passive sampling is 11%. The method proposed does not require any assumptions, complex calculation or modelling technique, and can be useful when other estimation methods are not feasible, either in principle or in practice. However, the method is not useful when estimates of hourly concentrations are of interest.

FIELD METHOD COMPARISON BETWEEN PASSIVE AIR SAMPLERS AND CONTINUOUS MONITORS FOR VOLATILE ORGANIC COMPOUNDS AND NO2 IN EL PASO, TEXAS, USA

EPA Science Inventory

Passive sampling of gas-phase air toxics and criteria pollutants has become an attractive monitoring method in human exposure studies due to the relatively low sampling cost and ease of use. This study evaluates the performance of Model 3300 Ogawa(TM) Passive NO2 Samplers and 3...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR COLLECTION OF FIXED SITE INDOOR AND OUTDOOR FORMALDEHYDE PASSIVE SAMPLES (UA-F-13.1)

EPA Science Inventory

The purpose of this SOP is to describe the methods used to sample residential indoor and outdoor atmospheres for the presence of formaldehyde using the PF-1 passive formaldehyde sampler. The PF-1 passive sampler is used as a fixed location monitor to determine time integrated ex...

Coping and metabolic syndrome indicators in urban black South African men: the SABPA study.

PubMed

du Plessis, A; Malan, L; Malan, N T

2010-01-01

Urbanisation is associated with obesity, hypertension and development of the metabolic syndrome (MS). We aimed to assess the use of different coping styles and their influence on increases in MS indicators and target end-organ damage (TOD) in urban black African men. A sample of 53 men was classified as clear high active (AC, n = 30) or passive coping (PC, n = 23) responders, using the Amirkhan African validated coping style indicator. Blood pressure (BP) was recorded with an aneroid sphygmomanometer and waist circumference (WC) was determined. Carotid intima-media thickness (CIMT) and microalbuminuria were analysed to determine TOD. Fasting serum and eight-hour urine samples revealed elevated MS indicators in AC men. Strong associations existed between MS indicators and TOD in AC but not PC men. To conclude, only BP and seeking social support were positively associated with TOD in urban PC African men, while in urban AC African men, most MS indicators were positively associated with TOD, i.e. sub-clinical atherosclerosis and renal impairment.

Comparison of using polyurethane foam passive samplers and tree bark samples from Western China to determine atmospheric organochlorine pesticide.

PubMed

Li, Qiuxu; Lu, Yao; Jin, Jun; Li, Guangyao; Li, Peng; He, Chang; Wang, Ying

2016-03-01

Polyurethane foam (PUF) passive samplers were deployed and tree bark samples were collected at 15 sites across western China in 2013, and the organochlorine pesticide (OCP) concentrations in the samples were determined. Dichlorodiphenyltrichloroethane and its degradation products (collectively called DDTs), hexachlorocyclohexanes (HCHs), and hexachlorobenzene (HCB) were the dominant OCPs in the PUF samples and tree bark samples. The mean DDTs, HCHs and HCB concentrations were 33, 22 and 18ng/sample in the PUF samples, and 428, 74, and 43ng/(g lipid weight (lw)) in the tree bark, respectively. The OCP concentrations in the air, calculated using PUF-air and tree-bark-air partitioning models, were of the same order of magnitude. Both sample types showed that relatively fresh inputs of DDT and HCHs to the environment have occurred in western China. Meanwhile, PUF passive samplers were compared with the use of tree bark samples as passive samplers. The OCP compositions in the PUF and tree bark samples were different. Only the relatively stable OCPs (such as HCB, β-HCH and p,p'-dichlorodiphenyldichloro-ethylene (DDE)) were consistent in the PUF and tree bark samples. Copyright © 2015. Published by Elsevier B.V.

Political Implications of Heavy Television Viewing.

ERIC Educational Resources Information Center

Jackson-Beeck, Marilyn

This paper empirically evaluates the proposition that political conformism, specifically structural, passive, psychological, and defensive conformism, is a function of exposure to mass media. Secondary analysis of data from the National Opinion Research Center's 1975 General Social Survey revealed a significant relationship between TV viewing and…

Significance of likes: Analysing passive interactions on Facebook during campaigning.

PubMed

Khairuddin, Mohammad Adib; Rao, Asha

2017-01-01

With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions) in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS) to measure the passive interactions between a candidate's posts on Facebook and the users (liking the posts). Using this method on original Malaysian General Election (MGE13) and Australian Federal Elections (AFE13) Facebook Pages (FP) campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning.

Cutting through the noise: an evaluative framework for research communication

NASA Astrophysics Data System (ADS)

Strickert, G. E.; Bradford, L. E.; Shantz, S.; Steelman, T.; Orozs, C.; Rose, I.

2017-12-01

With an ever-increasing amount of research, there is a parallel challenge to mobilize the research for decision making, policy development and management actions. The tradition of "loading dock" model of science to policy is under renovation, replaced by more engaging methods of research communication. Research communication falls on a continuum from passive methods (e.g. reports, social media, infographics) to more active methods (e.g. forum theatre, decision labs, and stakeholder planning, and mix media installations that blend, art, science and traditional knowledge). Drawing on a five-year water science research program in the Saskatchewan River Basin, an evaluation framework is presented that draws on a wide communities of knowledge users including: First Nation and Metis, Community Organizers, Farmers, Consultants, Researchers, and Civil Servants. A mixed method framework consisting of quantitative surveys, qualitative interviews, focus groups, and q-sorts demonstrates that participants prefer more active means of research communication to draw them into the research, but they also value more traditional and passive methods to provide more in-depth information when needed.

Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials.

PubMed

Maxwell, Adam D; Cain, Charles A; Hall, Timothy L; Fowlkes, J Brian; Xu, Zhen

2013-03-01

In this study, the negative pressure values at which inertial cavitation consistently occurs in response to a single, two-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (P(cav)) for a single pulse as a function of peak negative pressure (p(-)) followed a sigmoid curve, with the probability approaching one when the pressure amplitude was sufficient. The statistical threshold (defined as P(cav) = 0.5) was between p(-) = 26 and 30 MPa in all samples with high water content but varied between p(-) = 13.7 and >36 MPa in other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p(-) = 28.2 megapascals was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at various pressure levels and dimensions of cavitation-induced lesions in tissue. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Grab and passive sampling applied to pesticide analysis in the São Lourenço river headwater in Campo Verde - MT, Brazil.

PubMed

Berton, André; Brugnera, Michelle F; Dores, Eliana F G C

2018-04-03

In this study, the quality of surface water in the headwaters of São Lourenço River in Mato Grosso, Brazil, was evaluated in relation to contamination by pesticides. For this purpose, samples were collected between December 2015 and June 2016 by grab sampling and by passive sampling using an integrative polar organic compound sampler installed in the field during four 14-day cycles between March and June 2016. The analyses were performed by gas chromatography (CG/MS) and by liquid chromatography (UPLC-MS/MS). The results showed the detection of two pesticides (atrazine and pyraclostrobin) of the five analyzed by passive sampling and eight active principles among the 20 analyzed (malathion, diuron, carbofuran, carbendazim, trifluralin, imidacloprid, metolachlor, and acetamiprid) by grab sampling. The detection of 10 pesticides, even almost a decade after the beginning of a recovery process of the ciliary forest, confirms the headwaters' vulnerability to these contaminants and passive sampling proved to be an important tool in capturing small concentrations of pesticides constituting an interesting complement to grab sampling.

Contaminants of legacy and emerging concern in largescale suckers (Catostomus macrocheilus) and the foodweb in the lower Columbia River, Oregon and Washington, USA.

PubMed

Nilsen, Elena; Zaugg, Steven; Alvarez, David; Morace, Jennifer; Waite, Ian; Counihan, Timothy; Hardiman, Jill; Torres, Leticia; Patiño, Reynaldo; Mesa, Matthew; Grove, Robert

2014-06-15

We investigated occurrence, transport pathways, and effects of polybrominated diphenyl ether (PBDE) flame retardants and other endocrine disrupting chemicals (EDCs) in aquatic media and the foodweb in the lower Columbia River. In 2009 and 2010, foodweb sampling at three sites along a gradient of contaminant exposure near Skamania (Washington), Columbia City (Oregon) and Longview (Washington) included water (via passive samplers), bed sediment, invertebrate biomass residing in sediment, a resident fish species (largescale suckers [Catostomus macrocheilus]), and eggs from osprey (Pandion haliaetus). This paper primarily reports fish tissue concentrations. In 2009, composites of fish brain, fillet, liver, stomach, and gonad tissues revealed that overall contaminant concentrations were highest in livers, followed by brain, stomach, gonad, and fillet. Concentrations of halogenated compounds in tissue samples from all three sites ranged from <1 to 400nanograms per gram of wet tissue. Several chemical classes, including PBDEs, organochlorine pesticides, and polychlorinated biphenyls (PCBs), were detected at all sites and in nearly all fish tissues sampled. In 2010, only fish livers were sampled and inter-site concentration differences were not as pronounced as in 2009. Chemical concentrations in sediments, fish tissues, and osprey eggs increased moving downstream from Skamania to the urbanized sites near Columbia City and Longview. Numerous organochlorine (OC) pesticides, both banned and currently used, and PBDEs, were present at each site in multiple media and concentrations exceeded environmental quality benchmarks in some cases. Frequently detected OC compounds included hexachlorobenzene, pentachloroanisole, dichlorodiphenyltrichloroethane (DDT) and its degradates, chlorpyrifos, and oxyfluorofen. Biomagnification of BDE47, 100, 153, and 154 occurred in largescale suckers and osprey eggs. Results support the hypothesis that contaminants in the environment lead to bioaccumulation and potential negative effects in multiple levels of the foodweb. Published by Elsevier B.V.

Contaminants of legacy and emerging concern in largescale suckers (Catostomus macrocheilus) and the foodweb in the lower Columbia River, Oregon and Washington, USA

USGS Publications Warehouse

Nilsen, Elena B.; Zaugg, Steven D.; Alvarez, David A.; Morace, Jennifer L.; Waite, Ian R.; Counihan, Timothy D.; Hardiman, Jill M.; Torres, Leticia; Patino, Reynaldo; Mesa, Matthew G.; Grove, Robert

2014-01-01

We investigated occurrence, transport pathways, and effects of polybrominated diphenyl ether (PBDE) flame retardants and other endocrine disrupting chemicals (EDCs) in aquatic media and the foodweb in the lower Columbia River. In 2009 and 2010, foodweb sampling at three sites along a gradient of contaminant exposure near Skamania (Washington), Columbia City (Oregon) and Longview (Washington) included water (via passive samplers), bed sediment, invertebrate biomass residing in sediment, a resident fish species (largescale suckers [Catostomus macrocheilus]), and eggs from osprey (Pandion haliaetus). This paper primarily reports fish tissue concentrations. In 2009, composites of fish brain, fillet, liver, stomach, and gonad tissues revealed that overall contaminant concentrations were highest in livers, followed by brain, stomach, gonad, and fillet. Concentrations of halogenated compounds in tissue samples from all three sites ranged from < 1 to 400 nanograms per gram of wet tissue. Several chemical classes, including PBDEs, organochlorine pesticides, and polychlorinated biphenyls (PCBs), were detected at all sites and in nearly all fish tissues sampled. In 2010, only fish livers were sampled and inter-site concentration differences were not as pronounced as in 2009. Chemical concentrations in sediments, fish tissues, and osprey eggs increased moving downstream from Skamania to the urbanized sites near Columbia City and Longview. Numerous organochlorine (OC) pesticides, both banned and currently used, and PBDEs, were present at each site in multiple media and concentrations exceeded environmental quality benchmarks in some cases. Frequently detected OC compounds included hexachlorobenzene, pentachloroanisole, dichlorodiphenyltrichloroethane (DDT) and its degradates, chlorpyrifos, and oxyfluorofen. Biomagnification of BDE47, 100, 153, and 154 occurred in largescale suckers and osprey eggs. Results support the hypothesis that contaminants in the environment lead to bioaccumulation and potential negative effects in multiple levels of the foodweb.

KSC-2015-1220

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Representatives of the social media were given the opportunity to ask questions from the experts of NASA's Soil Moisture Active Passive mission, or SMAP, at the NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

Transforming nursing education in a 140-character world: The efficacy of becoming social.

PubMed

Stevens, Karen Patterson; Nies, Mary A

A generational gap exists across educational settings today. The potential and actual mismatch of learning styles and curriculum delivery suggests that the current educational models are in need of change. The advent of social media has transformed students from passive recipients of information to co-creators and engaged members of a global and information rich community. Responding proactively with social media integration through a responsive curriculum delivery system would serve to enhance student engagement and improve collaborative learning opportunities. Future implications for social media use in research and education will allow for rapid and efficient research to practice dissemination. Copyright © 2017 Elsevier Inc. All rights reserved.

Bear Creek Valley characterization area mixed wastes passive in situ treatment technology demonstration project - status report

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

Watson, D.; Leavitt, M.; Moss, D.

1997-03-01

Historical waste disposal activities within the Bear Creek Valley (BCV) Characterization Area (CA), at the U.S. Department of Energy (DOE) Oak Ridge Y-12 plant, have contaminated groundwater and surface water above human health risk levels and impacted the ecology of Bear Creek. Contaminates include nitrate, radioisotopes, metals, volatile organic chemicals (VOCS), and common ions. This paper provides a status report on a technology demonstration project that is investigating the feasibility of using passive in situ treatment systems to remove these contaminants. Although this technology may be applicable to many locations at the Oak Ridge Y-12 Plant, the project focuses onmore » collecting the information needed to take CERCLA removal actions in 1998 at the S-3 Disposal Ponds site. Phase 1 has been completed and included site characterization, laboratory screening of treatment media (sorbents; and iron), and limited field testing of biological treatment systems. Batch tests using different Y-12 Plant waters were conducted to evaluate the removal efficiencies of most of the media. Phase 1 results suggest that the most promising treatment media are Dowex 21 k resin, peat moss, zero-valent iron, and iron oxides. Phase 2 will include in-field column testing of these media to assess loading rates, and concerns with clogging, by-products, and long-term treatment efficiency and media stability. Continued testing of wetlands and algal mats (MATs) will be conducted to determine if they can be used for in-stream polishing of surface water. Hydraulic testing of a shallow trench and horizontal well will also be completed during Phase 2. 4 refs., 3 tabs.« less

Marijuana advertising exposure among current marijuana users in the U.S.

PubMed

Krauss, Melissa J; Sowles, Shaina J; Sehi, Auriann; Spitznagel, Edward L; Berg, Carla J; Bierut, Laura J; Cavazos-Rehg, Patricia A

2017-05-01

Little is known about marijuana advertising exposure among users in the U.S. We examined the prevalence of advertising exposure among young adult marijuana users through traditional and new media, and identified characteristics associated with seeking advertisements. We conducted a cross-sectional survey of 18-34 year-old past-month marijuana users in the U.S. using a pre-existing online panel (N=742). The survey queried about passively viewing and actively seeking marijuana advertisements in the past month, sources of advertisements, and marijuana use characteristics. Over half of participants were exposed to marijuana advertising in the past month (28% passively observed advertisements, 26% actively sought advertisements). Common sources for observing advertisements were digital media (i.e., social media, online, text/emails; 77%). Similarly, those actively seeking advertisements often used Internet search engines (65%) and social media (53%). Seeking advertisements was more common among those who used medically (41% medical only, 36% medical and recreational) than recreational users (18%), who used concentrates or edibles (44% and 43%) compared to those who did not (20% and 19%), and who used multiple times per day (33%) compared to those who did not (19%) (all p<0.01). Exposure to marijuana advertising among users is common, especially via digital media, and is associated with medical use, heavier use, and use of novel products with higher THC concentrations (i.e., concentrates) or longer intoxication duration (i.e., edibles). As the U.S. marijuana policy landscape changes, it will be important to examine potential causal associations between advertising exposure and continuation or frequency/quantity of use. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of trichloroanisole and trichlorophenol in wineries' ambient air by passive sampling and thermal desorption-gas chromatography coupled to tandem mass spectrometry.

PubMed

Camino-Sánchez, F J; Bermúdez-Peinado, R; Zafra-Gómez, A; Ruíz-García, J; Vílchez-Quero, J L

2015-02-06

The present paper describes the calibration of selected passive samplers used in the quantitation of trichlorophenol and trichloroanisole in wineries' ambient air, by calculating the corresponding sampling rates. The method is based on passive sampling with sorbent tubes and involves thermal desorption-gas chromatography-triple quadrupole mass spectrometry analysis. Three commercially available sorbents were tested using sampling cartridges with a radial design instead of axial ones. The best results were found for Tenax TA™. Sampling rates (R-values) for the selected sorbents were determined. Passive sampling was also used for accurately determining the amount of compounds present in the air. Adequate correlation coefficients between the mass of the target analytes and exposure time were obtained. The proposed validated method is a useful tool for the early detection of trichloroanisole and its precursor trichlorophenol in wineries' ambient air while avoiding contamination of wine or winery facilities. Copyright © 2015 Elsevier B.V. All rights reserved.

PCDD/PCDF and dl-PCB in the ambient air of a tropical Andean city: passive and active sampling measurements near industrial and vehicular pollution sources.

PubMed

Cortés, J; González, C M; Morales, L; Abalos, M; Abad, E; Aristizábal, B H

2014-09-01

Concentration gradients were observed in gas and particulate phases of PCDD/F originating from industrial and vehicular sources in the densely populated tropical Andean city of Manizales, using passive and active air samplers. Preliminary results suggest greater concentrations of dl-PCB in the mostly gaseous fraction (using quarterly passive samplers) and greater concentrations of PCDD/F in the mostly particle fraction (using daily active samplers). Dioxin-like PCB predominance was associated with the semi-volatility property, which depends on ambient temperature. Slight variations of ambient temperature in Manizales during the sampling period (15°C-27°C) may have triggered higher concentrations in all passive samples. This was the first passive air sampling monitoring of PCDD/F conducted in an urban area of Colombia. Passive sampling revealed that PCDD/F in combination with dioxin-like PCB ranged from 16 WHO-TEQ2005/m(3) near industrial sources to 7 WHO-TEQ2005/m(3) in an intermediate zone-a reduction of 56% over 2.8 km. Active sampling of particulate phase PCDD/F and dl-PCB were analyzed in PM10 samples. PCDD/F combined with dl-PCB ranged from 46 WHO-TEQ2005/m(3) near vehicular sources to 8 WHO-TEQ2005/m(3) in the same intermediate zone, a reduction of 83% over 2.6 km. Toxic equivalent quantities in both PCDD/F and dl-PCB decreased toward an intermediate zone of the city. Variations in congener profiles were consistent with variations expected from nearby sources, such as a secondary metallurgy plant, areas of concentrated vehicular emissions and a municipal solid waste incinerator (MSWI). These variations in congener profile measurements of dioxins and dl-PCBs in passive and active samples can be partly explained by congener variations expected from the various sources. Copyright © 2014 Elsevier B.V. All rights reserved.

Hurdles to organic quinone flow cells. Electrode passivation by quinone reduction in acetonitrile Li electrolytes

NASA Astrophysics Data System (ADS)

Rueda-García, D.; Dubal, D. P.; Huguenin, F.; Gómez-Romero, P.

2017-05-01

The uses of quinones in Redox Flow Batteries (RFBs) has been mainly circumscribed to aqueous solutions (of derivatives with polar groups) despite a larger solubility and wider electrochemical window provided by organic media. The redox mechanism of quinones in protic media is simpler and better known than in aprotic media, where radical species are involved. This paper reports the behaviour of methyl-p-benzoquinone (MBQ) under electrochemical reduction conditions in a LiClO4sbnd CH3CN electrolyte and various working electrodes. We detected the reversible generation of a bright green coating on the working electrode and the subsequent formation of a polymer (the nature of which depends on the presence or absence of oxygen). These coatings prevent the regular redox process of methyl-p-benzoquinone from taking place on the surface of the electrode and is generated regardless of the electrode material used or the presence of O2 in solution. In addition to MBQ, the green passivating layer was also found for less sterically hindered quinones such as p-benzoquinone or 1,4-naphthoquinone, but not for anthraquinone. We have also shown the central role of Li+ in the formation of this green layer. This work provides important guidelines for the final use of quinones in RFBs with organic electrolytes.

"Honk against homophobia": rethinking relations between media and sexual minorities.

PubMed

Venzo, Paul; Hess, Kristy

2013-01-01

The theory of "symbolic annihilation" or "symbolic violence" has been used in academic literature to describe the way in which sexual minorities have been ignored, trivialized, or condemned by the media. This article aims to de-center research from issues of media representation to consider the capacity for minority groups to proactively use new media and its various avenues for interactivity, social networking, and feedback to fight social exclusion. This work suggests that new media has become a space in which the nominally marginal in society may acquire "social artillery"-a term used to describe how sexual minorities utilize their expanding and more readily accessible social connections in digital space to combat instances of homophobia. The research draws on the results of an inquiry into the relation between media and a regional youth social justice group in Australia tackling homophobia. The research demonstrates that the group is becoming increasingly adept and comfortable with using a cross-section of media platforms to fulfill their own objectives, rather than seeing themselves as passive subjects of media representation. This article argues that this sets an example for other socially excluded groups looking to renegotiate their relation with the media in regional areas.

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Brad Doorn, SMAP applications lead, Science Mission Directorate’s Applied Sciences Program at NASA Headquarters speaks during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Christine Bonniksen, SMAP program executive with the Science Mission Directorate’s Earth Science Division at NASA Headquarters speaks during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Kent Kellogg, SMAP project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, CA, speaks during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

How and Why Parents Guide the Media Use of Young Children.

PubMed

Nikken, Peter; Schols, Marjon

Children use electronic screens at ever younger ages, but there is still little empirical research on how and why parents mediate this media use. In line with Vygotsky's zone of proximal development, we explored whether children's media skills and media activities, next to parents' attitudes about media for children, and several child and parent-family characteristics, predicted parental mediation practices. Furthermore, we investigated children's use and ownership of electronic screens in the bedroom in relationship to the child's media skills. Data from an online survey among 896 Dutch parents with young children (0-7 years) showed that children's use and ownership of TV, game consoles, computers and touchscreens, primarily depended on their media skills and age, not on parent's attitudes about media for children. Only touchscreens were used more often by children, when parents perceived media as helpful in providing moments of rest for the child. In line with former studies, parents consistently applied co-use, supervision, active mediation, restrictive mediation, and monitoring, depending on positive and negative attitudes about media. The child's media skills and media activities, however, had stronger relationships with parental mediation styles, whereas age was not related. Canonical discriminant analysis, finally, captured how the five mediation strategies varied among infants, toddlers, pre-schoolers, and early childhood children, predominantly as a result of children's media skills, and media activities, i.e., playing educational games and passive entertainment use.

Performance of Passive Samplers for Monitoring Estuarine Water Column Concentrations: 1. Contaminants of Concern

EPA Science Inventory

Contaminants enter marine and estuarine environments and can potentially pose risk to human and ecological health. Measuring contaminants of concern (COC) in these aqueous media can be difficult due to their relatively low solubilities and tendency to associate with environmenta...

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: IN-DRAIN TREATMENT DEVICE. HYDRO INTERNATIONAL UP-FLO™ FILTER

EPA Science Inventory

Verification testing of the Hydro International Up-Flo™ Filter with one filter module and CPZ Mix™ filter media was conducted at the Penn State Harrisburg Environmental Engineering Laboratory in Middletown, Pennsylvania. The Up-Flo™ Filter is designed as a passive, modular filtr...

"Cold" Media Victims

ERIC Educational Resources Information Center

Grant, Barbara M.

1976-01-01

The solo activity of watching television makes children function as passive receivers of ideas rather than creators; the teacher should counter this by encouraging team play and active involvement in group situations so that the child's ability to understand and communicate with others and to make value judgments is developed. (JD)

Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

USGS Publications Warehouse

Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

2008-01-01

The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

Soil gas screening for chlorinated solvents at three contaminated karst sites in Tennessee

USGS Publications Warehouse

Wolfe, W.J.; Williams, S.D.

2002-01-01

Soil gas was sampled using active sampling techniques and passive collectors at three sites in Tennessee to evaluate the effectiveness of these techniques for locating chlorinated solvent sources and flowpaths in karst aquifers. Actively collected soil gas samples were analyzed in the field with a portable gas chromatograph, and the passive soil gas collectors were analyzed in the lab with gas chromatography/mass spectrometry. Results of the sampling indicate that the effectiveness of both techniques is highly dependent on the distribution of the contaminants in the subsurface, the geomorphic and hydrogeologic characteristics of the site, and, in one case, on seasonal conditions. Both active and passive techniques identified areas of elevated subsurface chlorinated solvent concentrations at a landfill site where contamination remains concentrated in the regolith. Neither technique detected chlorinated solvents known to be moving in the bedrock at a manufacturing site characterized by thick regolith and an absence of surficial karst features. Passive soil gas sampling had varied success detecting flowpaths for chloroform in the bedrock at a train derailment site characterized by shallow regolith and abundant surficial karst features. At the train derailment site, delineation of the contaminant flowpath through passive soil gas sampling was stronger and more detailed under Winter conditions than summer.

Reduced-Order Direct Numerical Simulation of Solute Transport in Porous Media

NASA Astrophysics Data System (ADS)

Mehmani, Yashar; Tchelepi, Hamdi

2017-11-01

Pore-scale models are an important tool for analyzing fluid dynamics in porous materials (e.g., rocks, soils, fuel cells). Current direct numerical simulation (DNS) techniques, while very accurate, are computationally prohibitive for sample sizes that are statistically representative of the porous structure. Reduced-order approaches such as pore-network models (PNM) aim to approximate the pore-space geometry and physics to remedy this problem. Predictions from current techniques, however, have not always been successful. This work focuses on single-phase transport of a passive solute under advection-dominated regimes and delineates the minimum set of approximations that consistently produce accurate PNM predictions. Novel network extraction (discretization) and particle simulation techniques are developed and compared to high-fidelity DNS simulations for a wide range of micromodel heterogeneities and a single sphere pack. Moreover, common modeling assumptions in the literature are analyzed and shown that they can lead to first-order errors under advection-dominated regimes. This work has implications for optimizing material design and operations in manufactured (electrodes) and natural (rocks) porous media pertaining to energy systems. This work was supported by the Stanford University Petroleum Research Institute for Reservoir Simulation (SUPRI-B).

40 CFR 1065.690 - Buoyancy correction for PM sample media.

Code of Federal Regulations, 2014 CFR

2014-07-01

... media. 1065.690 Section 1065.690 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Buoyancy correction for PM sample media. (a) General. Correct PM sample media for their buoyancy in air if you weigh them on a balance. The buoyancy correction depends on the sample media density, the density...

40 CFR 1065.690 - Buoyancy correction for PM sample media.

Code of Federal Regulations, 2011 CFR

2011-07-01

... media. 1065.690 Section 1065.690 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Buoyancy correction for PM sample media. (a) General. Correct PM sample media for their buoyancy in air if you weigh them on a balance. The buoyancy correction depends on the sample media density, the density...

40 CFR 1065.690 - Buoyancy correction for PM sample media.

Code of Federal Regulations, 2012 CFR

2012-07-01

... media. 1065.690 Section 1065.690 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Buoyancy correction for PM sample media. (a) General. Correct PM sample media for their buoyancy in air if you weigh them on a balance. The buoyancy correction depends on the sample media density, the density...

40 CFR 1065.690 - Buoyancy correction for PM sample media.

Code of Federal Regulations, 2013 CFR

2013-07-01

... media. 1065.690 Section 1065.690 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Buoyancy correction for PM sample media. (a) General. Correct PM sample media for their buoyancy in air if you weigh them on a balance. The buoyancy correction depends on the sample media density, the density...

Trapping behavior of Shockley-Read-Hall recombination centers in silicon solar cells

NASA Astrophysics Data System (ADS)

Gogolin, R.; Harder, N. P.

2013-08-01

We investigate the correlation between increased apparent carrier lifetime in photoconductance-based lifetime measurements and actually reduced recombination lifetime as measured by photoluminescence measurements. These findings are further reconfirmed by I-V curve measurements of solar cells. In particular, we show experimental results for lifetime samples and solar cells with and without hydrogen passivation. In the samples and solar cells without hydrogen passivation, we find both a stronger trapping behavior and a lower recombination lifetime. Our model provides a consistent description of the observation of both, the increased apparent lifetime from carrier trapping and the decreasing recombination lifetime. In our model, both are caused by a single physical mechanism; i.e., by Recombination-Active-Trap (RAT) states. Upon fitting the experimental lifetime data, we find that the RAT-defect parameters for the hydrogen-passivated and non-hydrogen-passivated lifetime samples and solar cells are identical except for the defect concentration: hydrogen-passivation reduced the defect density by 50% in both, the lifetime samples and solar cells. We conclude that trapping should be considered as an indication for hidden, yet potentially strongly increased, low injection recombination activity.

Hydrodynamic interactions between a self-rotation rotator and passive particles

NASA Astrophysics Data System (ADS)

Ouyang, Zhenyu; Lin, Jian-Zhong; Ku, Xiaoke

2017-10-01

In this paper, we numerically investigate the hydrodynamic interaction between a self-rotation rotator and passive particles in a two-dimensional confined cavity at two typical Reynolds numbers according to the different flow features. Both the fluid-particle interaction and particle-particle interaction through fluid media are taken into consideration. The results show that from the case of a rotator and one passive particle to the case of a rotator and two passive particles, the system becomes much more complex because the relative displacement between the rotator and the passive particles and the velocity of passive particles are strongly dependent on the Reynolds number and the initial position of passive particles. For the system of two particles, the passive particle gradually departs from the rotator although its relative displacement to the rotator exhibits a periodic oscillation at the lower Reynolds number. Furthermore, the relative distance between the two particles and the rotator's rotational frequency are responsible for the oscillation amplitude and frequency of the passive particle's velocity. For the system of three particles, the passive particle's velocities exhibit a superposition of a large amplitude oscillation and a small amplitude oscillation at the lower Reynolds number, and the large amplitude oscillation will disappear at the higher Reynolds number. The change of the included angle of the two passive particles is dependent on the initial positions of the passive particles at the lower Reynolds number, whereas the included angle of the two passive particles finally approaches a fixed value at the higher Reynolds number. It is interesting that the two passive particles periodically approach and depart from each other when the included angle is not equal to π, while all the three particles (including the rotator) keep the positions in a straight line when the included angle is equal to π because the interference between two passive particles disappears. In addition, the passive particle rotates not only around the rotator but also around its own axis, and the rotation speed of the former is far greater than that of the latter.

Quantitative passive soil vapor sampling for VOCs--part 1: theory.

PubMed

McAlary, Todd; Wang, Xiaomin; Unger, Andre; Groenevelt, Hester; Górecki, Tadeusz

2014-03-01

Volatile organic compounds are the primary chemicals of concern at many contaminated sites and soil vapor sampling and analysis is a valuable tool for assessing the nature and extent of contamination. Soil gas samples are typically collected by applying vacuum to a probe in order to collect a whole-gas sample, or by drawing gas through a tube filled with an adsorbent (active sampling). There are challenges associated with flow and vacuum levels in low permeability materials, and leak prevention and detection during active sample collection can be cumbersome. Passive sampling has been available as an alternative to conventional gas sample collection for decades, but quantitative relationships between the mass of chemicals sorbed, the soil vapor concentrations, and the sampling time have not been established. This paper presents transient and steady-state mathematical models of radial vapor diffusion to a drilled hole and considerations for passive sampler sensitivity and practical sampling durations. The results indicate that uptake rates in the range of 0.1 to 1 mL min(-1) will minimize the starvation effect for most soil moisture conditions and provide adequate sensitivity for human health risk assessment with a practical sampling duration. This new knowledge provides a basis for improved passive soil vapour sampler design.

Toward a Pedagogy of Materially Engaged Listening

ERIC Educational Resources Information Center

LaVecchia, Christina M.

2017-01-01

As writing teachers increasingly engage students with audio media, it has become crucial to coach listening explicitly in the classroom, activities that students may otherwise approach passively. In this article I suggest that a rhetorical approach applicable to (or derived from) print texts is not enough to help students listen actively, and…

Is Media Literacy Passive or Active?

ERIC Educational Resources Information Center

Brooks, Zachary S.

2010-01-01

The ability to "read" and "write", i.e. literacy, was once considered a trade secret by the professional scribes who depended on it for job security. The ability to read and write is still the most commonly understood notion of literacy, but technological developments require that the definition of literacy be expanded and…

KINETICS OF SOLUBLE CHROMIUM REMOVAL FROM CONTAMINATED WATER BY ZEROVALENT IRON MEDIA: CORROSION INHIBITION AND PASSIVE OXIDE EFFECTS. (R825223)

EPA Science Inventory

Permeable reactive barriers containing zerovalent iron are being increasingly
employed for in situ remediation of groundwater contaminated with redox active
metals and chlorinated organic compounds. This research investigated the effect
of chromate concentration on...

The University's Role in National Life--Passive or Active?

ERIC Educational Resources Information Center

Bowden, G. T.

1980-01-01

Some kind of coalition of universities, corporations, and other private organizations, it is argued, will be necessary to gain sufficient credibility to influence public policy. The complexities of modern mass media communication and of public policy issues have reached levels that justify a review of university and corporate roles. (MLW)

Young People Speaking Back from the Margins

ERIC Educational Resources Information Center

Smyth, John

2010-01-01

The diminished educational opportunities and subsequent life chances of many marginalized young people have been dramatic, even to the point of being catastrophic. But they are not hapless victims, nor are they passive recipients of deficit categories like "at riskness", placed upon them by the media, politicians, agencies, and some…

Media education in pediatric residencies: a national survey.

PubMed

Christakis, Dimitri A; Frintner, Mary Pat; Mulligan, Deborah A; Fuld, Gilbert L; Olson, Lynn M

2013-01-01

Little is known about the current state of residency education with respect to counseling parents about media usage and whether trainees consider it to be adequate. A national survey of graduating pediatric residents was conducted in the United States to determine the amount of training they receive on traditional and new media, their perceptions of its quality, and their self-reported practices regarding talking to families about media usage. A 58% response rate was achieved with no evidence of response bias based on age or gender. Only 38% rated their residency program as "very good" or "excellent" in preparing them to provide anticipatory guidance on the effects of media on children and adolescents. In logistic regression analyses, controlling for demographic characteristics, more training on media issues was a significant predictor for usually/always advising families on traditional, passive media (adjusted odds ratio = 3.29; 95% confidence interval 2.26-4.81) and usually/always advising families on new, interactive media use (adjusted odds ratio = 3.96; 95% confidence interval 2.61-6.00) during well-child visits. The majority of residents believe their training on children in media is inadequate. Enhanced training on media is needed in US pediatric residencies. Copyright © 2013 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Effect of passive smoking on growth and infection rates of breast-fed and non-breast-fed infants.

PubMed

Yilmaz, Gonca; Hizli, Samil; Karacan, Candemir; Yurdakök, Kadriye; Coşkun, Turgay; Dilmen, Uğur

2009-06-01

The aim of the present study was to determine the effect of passive tobacco smoking on growth and infection rate of infants, and to evaluate whether breast-feeding might be protective against harmful effects of cigarette smoke. A cross-sectional study on 254 6-7-month-old infants was carried out. A questionnaire was given to mothers; and infants' head circumference, bodyweight, height, and urinary cotinine levels were measured. Multivariate analysis of factors influencing lower respiratory tract infections showed that smoking mothers increased the rate by 9.1-fold; breast-feeding decreased it by 3.3-fold; formula feeding at birth increased it by a factor of 15.2; another smoker at home increased it by a factor of 40.1. Multivariate analysis of factors influencing upper respiratory tract infections showed that smoking mothers increased the rate by a factor of 23; early formula feeding increased it by a factor of 62; breast-feeding decreased it by a factor of 5; smoking fathers increased it by a factor of 15. Multivariate analysis of factors influencing otitis media found that smoking mothers and fathers increased it by a factor of 9.4 and 6.15, respectively, and breast-feeding decreased it by a factor of 5.4. Tobacco smoke exposure of infants has negative consequences on growth, otitis media, and upper and lower respiratory tract infections. Breast-feeding promoted the growth of infants who were passively exposed to tobacco smoke and protected them against infections. Smoking should not be permitted in households with infants. When this is impossible, breast-feeding should be promoted to protect the infants against the health hazards of passive smoking.

A direct passive method for measuring water and contaminant fluxes in porous media

NASA Astrophysics Data System (ADS)

Hatfield, Kirk; Annable, Michael; Cho, Jaehyun; Rao, P. S. C.; Klammler, Harald

2004-12-01

This paper introduces a new direct method for measuring water and contaminant fluxes in porous media. The method uses a passive flux meter (PFM), which is essentially a self-contained permeable unit properly sized to fit tightly in a screened well or boring. The meter is designed to accommodate a mixed medium of hydrophobic and/or hydrophilic permeable sorbents, which retain dissolved organic/inorganic contaminants present in the groundwater flowing passively through the meter. The contaminant mass intercepted and retained on the sorbent is used to quantify cumulative contaminant mass flux. The sorptive matrix is also impregnated with known amounts of one or more water soluble 'resident tracers'. These tracers are displaced from the sorbent at rates proportional to the groundwater flux; hence, in the current meter design, the resident tracers are used to quantify cumulative groundwater flux. Theory is presented and quantitative tools are developed to interpret the water flux from tracers possessing linear and nonlinear elution profiles. The same theory is extended to derive functional relationships useful for quantifying cumulative contaminant mass flux. To validate theory and demonstrate the passive flux meter, results of multiple box-aquifer experiments are presented and discussed. From these experiments, it is seen that accurate water flux measurements are obtained when the tracer used in calculations resides in the meter at levels representing 20 to 70 percent of the initial condition. 2,4-Dimethyl-3-pentanol (DMP) is used as a surrogate groundwater contaminant in the box aquifer experiments. Cumulative DMP fluxes are measured within 5% of known fluxes. The accuracy of these estimates generally increases with the total volume of water intercepted.

Social media is a necessary component of surgery practice.

PubMed

Steele, Scott R; Arshad, Seyed; Bush, Ruth; Dasani, Serena; Cologne, Kyle; Bleier, Joshua I S; Raphaeli, Tal; Kelz, Rachel R

2015-09-01

Social media is a necessary component of the practice of surgery. Each surgeon must embrace the power and potential of social media and serve as a guide or content expert for patients and other health care providers to facilitate and share responsible use of the various media available. Social media facilitates rapid communication of information not only across providers but also between patients and providers. The power of social media has the potential to improve consultation and collaboration, facilitate patient education, and expand research efforts; moreover, by harnessing its potential, the appropriate use of many of the avenues of social media also can be used to disseminate campaigns to increase disease awareness and communicate new research findings and best-practice guidelines. Because its reach is so broad within as well as outside the censorship of medical experts, professional oversight and engagement is required to maximize responsible use. Staying consistent with our history of surgery, rich in innovation and technologic advancement, surgeons must get to the front of this evolving field and direct the path of social media as it applies to the practice of surgery rather than take a passive role. Published by Elsevier Inc.

Comparison of Passive and Active Air Sampling (PAAS) Methods for PCBs – A Pilot Study in New York City Schools

EPA Science Inventory

PCBs were used extensively in school building materials (caulk and lighting fixture ballasts) during the approximate period of 1950-1978. Most of the schools built nationwide during this period have not had indoor air sampling conducted for PCBs. Passive air sampling holds promi...

Comparison of active and passive sampling strategies for the monitoring of pesticide contamination in streams

NASA Astrophysics Data System (ADS)

Assoumani, Azziz; Margoum, Christelle; Guillemain, Céline; Coquery, Marina

2014-05-01

The monitoring of water bodies regarding organic contaminants, and the determination of reliable estimates of concentrations are challenging issues, in particular for the implementation of the Water Framework Directive. Several strategies can be applied to collect water samples for the determination of their contamination level. Grab sampling is fast, easy, and requires little logistical and analytical needs in case of low frequency sampling campaigns. However, this technique lacks of representativeness for streams with high variations of contaminant concentrations, such as pesticides in rivers located in small agricultural watersheds. Increasing the representativeness of this sampling strategy implies greater logistical needs and higher analytical costs. Average automated sampling is therefore a solution as it allows, in a single analysis, the determination of more accurate and more relevant estimates of concentrations. Two types of automatic samplings can be performed: time-related sampling allows the assessment of average concentrations, whereas flow-dependent sampling leads to average flux concentrations. However, the purchase and the maintenance of automatic samplers are quite expensive. Passive sampling has recently been developed as an alternative to grab or average automated sampling, to obtain at lower cost, more realistic estimates of the average concentrations of contaminants in streams. These devices allow the passive accumulation of contaminants from large volumes of water, resulting in ultratrace level detection and smoothed integrative sampling over periods ranging from days to weeks. They allow the determination of time-weighted average (TWA) concentrations of the dissolved fraction of target contaminants, but they need to be calibrated in controlled conditions prior to field applications. In other words, the kinetics of the uptake of the target contaminants into the sampler must be studied in order to determine the corresponding sampling rate constants (Rs). Each constant links the mass of the a target contaminant accumulated in the sampler to its concentration in water. At the end of the field application, the Rs are used to calculate the TWA concentration of each target contaminant with the final mass of the contaminants accumulated in the sampler. Stir Bar Sorptive Extraction (SBSE) is a solvent free sample preparation technique dedicated to the analysis of moderately hydrophobic to hydrophobic compounds in liquid and gas samples. It is composed of a magnet enclosed in a glass tube coated with a thick film of polydimethysiloxane (PDMS). We recently developed the in situ application of SBSE as a passive sampling technique (herein named "Passive SBSE") for the monitoring of agricultural pesticides. The aim of this study is to perform the calibration of the passive SBSE in the laboratory, and to apply and compare this technique to active sampling strategies for the monitoring of 16 relatively hydrophobic to hydrophobic pesticides in streams, during 2 1-month sampling campaigns. Time-weighted averaged concentrations of the target pesticides obtained from passive SBSE were compared to the target pesticide concentrations of grab samples, and time-related and flow-dependent samples of the streams. Results showed passive SBSE as an efficient alternative to conventional active sampling strategies.

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 Thermally Desorbable Miniature Passive Dosimeter for Organic Vapors

NASA Astrophysics Data System (ADS)

Gonzalez, Jesus Antonio

A thermally desorbable miniature passive dosimeter (MPD) for organic vapors has been developed in conformity with theoretical and practical aspects of passive dosimeter design. The device was optimized for low sample loadings resulting from short-term and/or low concentration level exposure. This was accomplished by the use of thermal desorption rather than solvent elution, which provided the GC method with significantly higher sensitivity. Laboratory evaluation of this device for factors critical to the performance of passive dosimeters using benzene as the test vapor included: desorption efficiency (97.2%), capacity (1400 ppm-min), sensitivity (7ng/sample or 0.06 ppmv for 15 minutes sampling) accuracy and precision, concentration level, environmental conditions (i.e., air face velocity, relative humidity) and sample stability during short (15 minutes) and long periods of time (15 days). This device has demonstrated that its overall accuracy meets NIOSH and OSHA requirements for a sampling and analytical method for the exposure concentration range of 0.1 to 50 ppm (v/v) and 15 minutes exposures. It was demonstrated that the MPD operates in accordance with theoretically predicted performance and should be adequate for short-term and/or low concentration exposure monitoring of organic vapors in the workplace. In addition a dynamic vapor exposure evaluation system for passive dosimeters have been validated using benzene as the test vapor. The system is capable of generating well defined short-square wave concentration profiles suitable for the evaluation of passive dosimeters for ceiling exposure monitoring.

Surface characteristics, corrosion and bioactivity of chemically treated biomedical grade NiTi alloy.

PubMed

Chembath, Manju; Balaraju, J N; Sujata, M

2015-11-01

The surface of NiTi alloy was chemically modified using acidified ferric chloride solution and the characteristics of the alloy surface were studied from the view point of application as a bioimplant. Chemically treated NiTi was also subjected to post treatments by annealing at 400°C and passivation in nitric acid. The surface of NiTi alloy after chemical treatment developed a nanogrid structure with a combination of one dimensional channel and two dimensional network-like patterns. From SEM studies, it was found that the undulations formed after chemical treatment remained unaffected after annealing, while after passivation process the undulated surface was filled with oxides of titanium. XPS analysis revealed that the surface of passivated sample was enriched with oxides of titanium, predominantly TiO2. The influence of post treatment on the corrosion resistance of chemically treated NiTi alloy was monitored using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in Phosphate Buffered Saline (PBS) solution. In the chemically treated condition, NiTi alloy exhibited poor corrosion resistance due to the instability of the surface. On the other hand, the breakdown potential (0.8V) obtained was highest for the passivated samples compared to other surface treated samples. During anodic polarization, chemically treated samples displayed dissolution phenomenon which was predominantly activation controlled. But after annealing and passivation processes, the behavior of anodic polarization was typical of a diffusion controlled process which confirmed the enhanced passivity of the post treated surfaces. The total resistance, including the porous and barrier layer, was in the range of mega ohms for passivated surfaces, which could be attributed to the decrease in surface nickel content and formation of compact titanium oxide. The passivated sample displayed good bioactivity in terms of hydroxyapatite growth, noticed after 14days immersion in Hanks' solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Marvelous medicines and dangerous drugs: the representation of prescription medicine in the UK newsprint media.

PubMed

Prosser, Helen

2010-01-01

Using discourse analysis, this study examines the representation of prescription medicines in the UK newsprint media and, specifically, how the meaning and function of medicines are constructed. At the same time, it examines the extent to which the newsprint media represents a resource for health information, and considers how it may encourage or challenge faith in modern medicine and medical authority. As such, it extends analysis around concepts such as the informed patient and examines the representation of patients and doctors and the extent to which patient-doctor identities promoted in the newsprint media reflect a shift away from paternalism to negotiated encounters. Findings show the media constructs a discrete, contradictory, and frequently oversimplified set of characterizations about medicine. Moreover, it discursively constructs realities that justify and sustain medial dominance. Ideological paradigms in discourse assign patients as passive and disempowered while simultaneously privileging "expert" knowledge. This constructs a reality that marginalizes patients' participation in decision-making.

A passive sampler for airborne formaldehyde

NASA Astrophysics Data System (ADS)

Grosjean, Daniel; Williams, Edwin L.

A simple, inexpensive passive sampler is described that is capable of reliable measurements of formaldehyde at the parts per billion (ppb) levels relevant to indoor and outdoor air quality. The passive sampler consists of a modified dual filter holder in which the upper stage serves as the diffusion barrier, the lower stage includes a 2,4-dinitrophenylhydrazine (DNPH)-coated filter which collects formaldehyde, and the space between the two stages serve as the diffusion gap. The measured sampling rate, 18.8 ± 1.8 ml min -1, was determined in experiments involving sampling of ppb levels of formaldehyde with the passive sampler and with DNPH-coated C 18 cartridges and agrees well with the value of 19.4 ± 2.0 ml min -1 calculated from theory. The measured sampling rate was independent of formaldehyde concentration (16-156 ppb) and sampling duration (1.5-72 h). The precision of the measurements for colocated passive samplers averaged 8.6% in purified and indoor air (office and museums) and 10.2% in photochemically polluted outdoor air. With a 1.2-μm pore size Teflon filter as the diffusion barrier, the detection limit is 32 ppb h, e.g. 4 ppb in an 8-h sample, 1.3 ppb in a 24-h sample, and so on. Perceived advantages and limitations of the sampler are discussed including flexibility, cost effectiveness and possible negative bias at high ambient levels of ozone.

Use of mass media campaigns to change health behaviour

PubMed Central

Wakefield, Melanie A.; Loken, Barbara; Hornik, Robert C.

2014-01-01

Mass media campaigns are widely used to expose high proportions of large populations to messages through routine uses of existing media, such as television, radio, and newspapers. Exposure to such messages is, therefore, generally passive. Such campaigns are frequently competing with factors, such as pervasive product marketing, powerful social norms, and behaviours driven by addiction or habit. In this Review we discuss the outcomes of mass media campaigns in the context of various health-risk behaviours (eg, use of tobacco, alcohol, and other drugs, heart disease risk factors, sex-related behaviours, road safety, cancer screening and prevention, child survival, and organ or blood donation). We conclude that mass media campaigns can produce positive changes or prevent negative changes in health-related behaviours across large populations. We assess what contributes to these outcomes, such as concurrent availability of required services and products, availability of community-based programmes, and policies that support behaviour change. Finally, we propose areas for improvement, such as investment in longer better-funded campaigns to achieve adequate population exposure to media messages. PMID:20933263

Use of mass media campaigns to change health behaviour.

PubMed

Wakefield, Melanie A; Loken, Barbara; Hornik, Robert C

2010-10-09

Mass media campaigns are widely used to expose high proportions of large populations to messages through routine uses of existing media, such as television, radio, and newspapers. Exposure to such messages is, therefore, generally passive. Such campaigns are frequently competing with factors, such as pervasive product marketing, powerful social norms, and behaviours driven by addiction or habit. In this Review we discuss the outcomes of mass media campaigns in the context of various health-risk behaviours (eg, use of tobacco, alcohol, and other drugs, heart disease risk factors, sex-related behaviours, road safety, cancer screening and prevention, child survival, and organ or blood donation). We conclude that mass media campaigns can produce positive changes or prevent negative changes in health-related behaviours across large populations. We assess what contributes to these outcomes, such as concurrent availability of required services and products, availability of community-based programmes, and policies that support behaviour change. Finally, we propose areas for improvement, such as investment in longer better-funded campaigns to achieve adequate population exposure to media messages. Copyright © 2010 Elsevier Ltd. All rights reserved.

A meta-analysis of prosocial media on prosocial behavior, aggression, and empathic concern: A multidimensional approach.

PubMed

Coyne, Sarah M; Padilla-Walker, Laura M; Holmgren, Hailey G; Davis, Emilie J; Collier, Kevin M; Memmott-Elison, Madison K; Hawkins, Alan J

2018-02-01

Studies examining the effects of exposure to prosocial media on positive outcomes are increasing in number and strength. However, existing meta-analyses use a broad definition of prosocial media that does not recognize the multidimensionality of prosocial behavior. The aim of the current study is to conduct a meta-analysis on the effects of exposure to prosocial media on prosocial behavior, aggression, and empathic concern while examining multiple moderators that the prosocial behavior literature suggests are important to our understanding of why individuals voluntarily help others (e.g., target, type, cost). Results from 72 studies involving 243 effect sizes revealed that exposure to prosocial media was related to higher levels of prosocial behavior and empathic concern and lower levels of aggressive behavior. Moderation analyses suggest that several moderators accounted for heterogeneity in the model, including age of participant, region, media type (active vs. passive), and study design. In terms of multidimensional moderators, prosocial media had stronger effects on prosocial behavior toward strangers than did any other target and on helping and prosocial thinking but not donating or volunteering. Comparisons with other meta-analyses on media effects are made and implications for parents, media producers, and researchers are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Multifractal Modeling of Turbulent Mixing

NASA Astrophysics Data System (ADS)

Samiee, Mehdi; Zayernouri, Mohsen; Meerschaert, Mark M.

2017-11-01

Stochastic processes in random media are emerging as interesting tools for modeling anomalous transport phenomena. Applications include intermittent passive scalar transport with background noise in turbulent flows, which are observed in atmospheric boundary layers, turbulent mixing in reactive flows, and long-range dependent flow fields in disordered/fractal environments. In this work, we propose a nonlocal scalar transport equation involving the fractional Laplacian, where the corresponding fractional index is linked to the multifractal structure of the nonlinear passive scalar power spectrum. This work was supported by the AFOSR Young Investigator Program (YIP) award (FA9550-17-1-0150) and partially by MURI/ARO (W911NF-15-1-0562).

Design and laboratory testing of a new flow-through directional passive air sampler for ambient particulate matter.

PubMed

Lin, Chun; Solera Garcia, Maria Angeles; Timmis, Roger; Jones, Kevin C

2011-03-01

A new type of directional passive air sampler (DPAS) is described for collecting particulate matter (PM) in ambient air. The prototype sampler has a non-rotating circular sampling tray that is divided into covered angular channels, whose ends are open to winds from sectors covering the surrounding 360°. Wind-blown PM from different directions enters relevant wind-facing channels, and is retained there in collecting pools containing various sampling media. Information on source direction and type can be obtained by examining the distribution of PM between channels. Wind tunnel tests show that external wind velocities are at least halved over an extended area of the collecting pools, encouraging PM to settle from the air stream. Internal and external wind velocities are well-correlated over an external velocity range of 2.0-10.0 m s⁻¹, which suggests it may be possible to relate collected amounts of PM simply to ambient concentrations and wind velocities. Measurements of internal wind velocities in different channels show that velocities decrease from the upwind channel round to the downwind channel, so that the sampler effectively resolves wind directions. Computational fluid dynamics (CFD) analyses were performed on a computer-generated model of the sampler for a range of external wind velocities; the results of these analyses were consistent with those from the wind tunnel. Further wind tunnel tests were undertaken using different artificial particulates in order to assess the collection performance of the sampler in practice. These tests confirmed that the sampler can resolve the directions of sources, by collecting particulates preferentially in source-facing channels.

Active and realistic passive marijuana exposure tested by three immunoassays and GC/MS in urine

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

Mule, S.J.; Lomax, P.; Gross, S.J.

Human urine samples obtained before and after active and passive exposure to marijuana were analyzed by immune kits (Roche, Amersham, and Syva) and gas chromatography/mass spectrometry (GC/MS). Seven of eight subjects were positive for the entire five-day test period with one immune kit. The latter correlated with GC/MS in 98% of the samples. Passive inhalation experiments under conditions likely to reflect realistic exposure resulted consistently in less than 10 ng/mL of cannabinoids. The 10-100-ng/mL cannabinoid concentration range essential for detection of occasional and moderate marijuana users is thus unaffected by realistic passive inhalation.

Comparison of the Electrochemical Behavior of Ti and Nanostructured Ti-Coated AISI 304 Stainless Steel in Strongly Acidic Solutions

NASA Astrophysics Data System (ADS)

Attarzadeh, Farid Reza; Elmkhah, Hassan; Fattah-Alhosseini, Arash

2017-02-01

In this study, the electrochemical behaviors of pure titanium (Ti) and nanostructured (NS) Ti-coated AISI 304 stainless steel (SS) in strongly acidic solutions of H2SO4 were investigated and compared. A type of physical vapor deposition method, cathodic arc evaporation, was applied to deposit NS Ti on 304 SS. Scanning electron microscope and X-ray diffraction were used to characterize surface coating morphology. Potentiodynamic polarization, electrochemical impedance spectroscopy, and Mott-Schottky (M-S) analysis were used to evaluate the passive behavior of the samples. Electrochemical measurements revealed that the passive behavior of NS Ti coating was better than that of pure Ti in 0.1 and 0.01 M H2SO4 solutions. M-S analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and the deposition method did not affect the semiconducting type of passive films formed on the coated samples. In addition, this analysis showed that the NS Ti coating had lower donor densities. Finally, all electrochemical tests showed that the passive behavior of the Ti-coated samples was superior, mainly due to the formation of thicker, yet less defective passive films.

Preliminary assessment of using tree-tissue analysis and passive-diffusion samplers to evaluate trichloroethene contamination of ground water at Site SS-34N, McChord Air Force Base, Washington, 2001

USGS Publications Warehouse

Cox, S.E.

2002-01-01

Two low-cost innovative sampling procedures for characterizing trichloroethene (TCE) contamination in ground water were evaluated for use at McChord Air Force Base (AFB) by the U.S. Geological Survey, in cooperation with the U.S. Air Force McChord Air Force Base Installation Restoration Program, in 2001. Previous attempts to characterize the source of ground-water contamination in the heterogeneous glacial outwash aquifer at McChord site SS-34N using soil-gas surveys, direct-push exploration, and more than a dozen ground-water monitoring wells have had limited success. The procedures assessed in this study involved analysis of tree-tissue samples to map underlying ground-water contamination and deploying passive-diffusion samplers to measure TCE concentrations in existing monitoring wells. These procedures have been used successfully at other U.S. Department of Defense sites and have resulted in cost avoidance and accelerated site characterization. Despite the presence of TCE in ground water at site SS-34N, TCE was not detected in any of the 20 trees sampled at the site during either early spring or late summer sampling. The reason the tree tissue procedure was not successful at the McChord AFB site SS-34N may have been due to an inability of tree roots to extract moisture from a water table 30 feet below the land surface, or that concentrations of TCE in ground water were not large enough to be detectable in the tree tissue at the sampling point. Passive-diffusion samplers were placed near the top, middle, and bottom of screened intervals in three monitoring wells and TCE was observed in all samplers. Concentrations of TCE from the passive-diffusion samplers were generally similar to concentrations found in samples collected in the same wells using conventional pumping methods. In contrast to conventional pumping methods, the collection of ground-water samples using the passive-diffusion samples did not generate waste purge water that would require hazardous-waste disposal. In addition, the results from the passive-diffusion samples may show that TCE concentrations are stratified across some screened intervals. The overall results of the limited test of passive-diffusion samplers at site SS-34N were similar to more detailed tests conducted at other contaminated sites across the country and indicate that further evaluation of the use of passive-diffusion samplers at McChord site SS-34N is warranted.

Poly (3,4-ethylenedioxythiophene) graphene oxide composite coatings for controlling magnesium implant corrosion.

PubMed

Catt, Kasey; Li, Huaxiu; Cui, X Tracy

2017-01-15

Magnesium (Mg) is a promising biodegradable implant material because of its appropriate mechanical properties and safe degradation products. However, in vivo corrosion speed and hydrogen gas production need to be controlled for uses in biomedical applications. Here we report the development of a conducting polymer 3,4-ethylenedioxythiphene (PEDOT) and graphene oxide (GO) composite coating as a corrosion control layer. PEDOT/GO was electropolymerized on Mg samples in ethanol media. The coated Mg samples were subjected to various corrosion tests. The PEDOT/GO coating significantly reduced the rate of corrosion as evidenced by lower Mg ion concentration and pH of the corrosion media. In addition, the coating decreased the evolved hydrogen. Electrochemical analysis of the corroding samples showed more positive corrosion potential, a decreased corrosion current, and an increase in the polarization resistance. PEDOT/GO corrosion protection is attributed to three factors; an initial passive layer preventing solution ingress, buildup of negative charges in the film, and formation of corrosion protective Mg phosphate layer through redox coupling with Mg corrosion. To explore the biocompatibility of the coated implants in vitro, corrosion media from PEDOT/GO coated or uncoated Mg samples were exposed to cultured neurons where PEDOT/GO coated samples showed decreased toxicity. These results suggest that PEDOT/GO coating will be an effective treatment for controlling corrosion of Mg based medical implants. Coating Mg substrates with a PEDOT/GO composite coating showed a significant decrease in corrosion rate. While conducting polymer coatings have been used to prevent corrosion on various metals, there has been little work on the use of these coatings for Mg. Additionally, to our knowledge, there has not been a report of the combined used of conducting polymer and GO as a corrosion control layer. Corrosion control is attributed to an initial barrier layer followed by electrochemical coupling of the PEDOT/GO coating with the substrate to facilitate the formation of a protective phosphate layer. This coupling also resulted in a decrease in hydrogen produced during corrosion, which could further improve the host tissue integration of Mg implants. This work elaborates on the potential for electroactive polymers to serve as corrosion control methods. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Performance of passive samplers for monitoring estuarine water column concentrations: 2. Emerging contaminants.

PubMed

Perron, Monique M; Burgess, Robert M; Suuberg, Eric M; Cantwell, Mark G; Pennell, Kelly G

2013-10-01

Measuring dissolved concentrations of emerging contaminants, such as polybrominated diphenyl ethers (PBDEs) and triclosan, can be challenging due to their physicochemical properties resulting in low aqueous solubilities and association with particles. Passive sampling methods have been applied to assess dissolved concentrations in water and sediments primarily for legacy contaminants. Although the technology is applicable to some emerging contaminants, the use of passive samplers with emerging contaminants is limited. In the present study, the performance of 3 common passive samplers was evaluated for sampling PBDEs and triclosan. Passive sampling polymers included low-density polyethylene (PE) and polyoxymethylene (POM) sheets, and polydimethylsiloxane (PDMS)-coated solid-phase microextraction (SPME) fibers. Dissolved concentrations were calculated using measured sampler concentrations and laboratory-derived partition coefficients. Dissolved tri-, tetra-, and pentabrominated PBDE congeners were detected at several of the study sites at very low pg/L concentrations using PE and POM. Calculated dissolved water concentrations of triclosan ranged from 1.7 ng/L to 18 ng/L for POM and 8.8 ng/L to 13 ng/L for PE using performance reference compound equilibrium adjustments. Concentrations in SPME were not reported due to lack of detectable chemical in the PDMS polymer deployed. Although both PE and POM were found to effectively accumulate emerging contaminants from the water column, further research is needed to determine their utility as passive sampling devices for emerging contaminants. © 2013 SETAC.

Deriving sediment Interstitial Water Remediation Goals (IWRGs) for the protection of benthic organisms from direct toxicity

EPA Science Inventory

Background/Objectives. Passive sampling is becoming a frequently used measurement technique at Superfund sites with contaminated sediments. Passive sampling measures the concentrations of freely dissolved chemicals (Cfrees) in the sediment interstitial water. The freely dissol...

Assessment of Envi-Carb™ as a passive sampler binding phase for acid herbicides without pH adjustment.

PubMed

Seen, Andrew; Bizeau, Oceane; Sadler, Lachlan; Jordan, Timothy; Nichols, David

2014-05-01

The graphitised carbon solid phase extraction (SPE) sorbent Envi-Carb has been used to fabricate glass fibre filter- Envi-Carb "sandwich" disks for use as a passive sampler for acid herbicides. Passive sampler uptake of a suite of herbicides, including the phenoxyacetic acid herbicides 4-chloro-o-tolyloxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (Dicamba), was achieved without pH adjustment, demonstrating for the first time a suitable binding phase for passive sampling of acid herbicides at neutral pH. Passive sampling experiments with Duck River (Tasmania, Australia) water spiked at 0.5 μg L(-1) herbicide concentration over a 7 d deployment period showed that sampling rates in Duck River water decreased for seven out of eight herbicides, and in the cases of 3,6-dichloro-2-pyridinecarboxylic acid (Clopyralid) and Dicamba no accumulation of the herbicides occurred in the Envi-Carb over the deployment period. Sampling rates for 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (Picloram), 2,4-D and MCPA decreased to approximately 30% of the sampling rates in ultrapure water, whilst sampling rates for 2-(4,6-dimethylpyrimidin-2-ylcarbamoylsulfamoyl) benzoic acid, methyl ester (Sulfometuron-methyl) and 3,5,6-Trichloro-2-pyridinyloxyacetic acid (Triclopyr) were approximately 60% of the ultrapure water sampling rate. For methyl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-D-alaninate (Metalaxyl-M) there was little variation in sampling rate between passive sampling experiments in ultrapure water and Duck River water. SPE experiments undertaken with Envi-Carb disks using ultrapure water and filtered and unfiltered Duck River water showed that not only is adsorption onto particulate matter in Duck River water responsible for a reduction in herbicide sampling rate, but interactions of herbicides with dissolved or colloidal matter (matter able to pass through a 0.2 μm membrane filter) also reduces the herbicide sampling rate. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Emissivity of half-space random media. [in passive remote sensing

NASA Technical Reports Server (NTRS)

Tsang, L.; Kong, J. A.

1976-01-01

Scattering of electromagnetic waves by a half-space random medium with three-dimensional correlation functions is studied with the Born approximation. The emissivity is calculated from a simple integral and is illustrated for various cases. The results are valid over a wavelength range smaller or larger than the correlation lengths.

sTeam--Providing Primary Media Functions for Web-Based Computer-Supported Cooperative Learning.

ERIC Educational Resources Information Center

Hampel, Thorsten

The World Wide Web has developed as the de facto standard for computer based learning. However, as a server-centered approach, it confines readers and learners to passive nonsequential reading. Authoring and Web-publishing systems aim at supporting the authors' design process. Consequently, learners' activities are confined to selecting and…

Net Smart: How to Thrive Online

ERIC Educational Resources Information Center

Rheingold, Howard

2012-01-01

Like it or not, knowing how to make use of online tools without being overloaded with too much information is an essential ingredient to personal success in the twenty-first century. But how can we use digital media so that they make us empowered participants rather than passive receivers, grounded, well-rounded people rather than multitasking…

Something's Wrong Here and It's Not Me: Challenging the Dilemmas that Block Girls' Success.

ERIC Educational Resources Information Center

Bell, Lee Anne

1989-01-01

A group of high-potential girls in grades three-six met with researchers to discuss internal barriers to female achievement. Dilemmas identified as blocking girls' success in school included: smart versus social, silence versus bragging, failure versus perfection, media beauty versus marginality, passive versus aggressive, conforming versus being…

Significance of likes: Analysing passive interactions on Facebook during campaigning

PubMed Central

2017-01-01

With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions) in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS) to measure the passive interactions between a candidate’s posts on Facebook and the users (liking the posts). Using this method on original Malaysian General Election (MGE13) and Australian Federal Elections (AFE13) Facebook Pages (FP) campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning. PMID:28622350

The impact of mass media health communication on health decision-making and medical advice-seeking behavior of u.s. Hispanic population.

PubMed

De Jesus, Maria

2013-01-01

Mass media health communication has enormous potential to drastically alter how health-related information is disseminated and obtained by different populations. However, there is little evidence regarding the influence of media channels on health decision-making and medical advice-seeking behaviors among the Hispanic population. The Pew 2007 Hispanic Healthcare Survey was used to test the hypothesis that the amount of mass media health communication (i.e., quantity of media-based health information received) is more likely to influence Hispanic adults' health decision-making and medical advice-seeking behavior compared to health literacy and language proficiency variables. Results indicated that quantity of media-based health information is positively associated with health decision-making and medical advice-seeking behavior above and beyond the influence of health literacy and English and Spanish language proficiency. In a context where physician-patient dynamics are increasingly shifting from a passive patient role model to a more active patient role model, media-based health information can serve as an influential cue to action, prompting Hispanic individuals to make certain health-related decisions and to seek more health advice and information from a health provider. Study implications are discussed.

Selecting Performance Reference Compounds (PRCS) for Low Density Polyethylene Passive Samplers

EPA Science Inventory

Use of equilibrium passive samplers for performing aquatic environmental monitoring at contaminated sites is becoming more common. However, a current challenge in passive sampling is determining when equilibrium is achieved between the sampler, target contaminants, and environm...

Screen time and passive school travel as independent predictors of cardiorespiratory fitness in youth.

PubMed

Sandercock, Gavin R H; Ogunleye, Ayodele A

2012-05-01

The most prevalent sedentary behaviours in children and adolescents are engagement with small screen media (screen-time) and passive travel (by motorised vehicle). The objective of this research was to assess the independence of these behaviours from one another and from physical activity as predictors of cardiorespiratory fitness in youth. We measured cardiorespiratory fitness in n=6819 10-16 year olds (53% male) who self-reported their physical activity (7-day recall) school travel and screen time habits. Travel was classified as active (walking, cycling) or passive; screen time as <2 h, 2-4 h or >4 h. The multivariate odds of being fit were higher in active travel (Boys: OR 1.32, 95% CI: 1.09-1.59; Girls: OR 1.46, 1.15-1.84) than in passive travel groups. Boys reporting low screen time were more likely to be fit than those reporting >4 h (OR 2.11, 95% CI: 1.68-2.63) as were girls (OR 1.66, 95% CI: 1.24-2.20). These odds remained significant after additionally controlling for physical activity. Passive travel and high screen time are independently associated with poor cardiorespiratory fitness in youth, and this relationship is independent of physical activity levels. A lifestyle involving high screen time and habitual passive school travel appears incompatible with healthful levels of cardiorespiratory fitness in youth. Copyright © 2012 Elsevier Inc. All rights reserved.

Outstanding resistance and passivation behaviour of new Fe-Co metal-metal glassy alloys in alkaline media

PubMed Central

Al-Harbi, Albandaree K.

2018-01-01

The electrochemical behavior of the oxide layers on two metal-metal glassy alloys, Fe78Co9Cr10Mo2Al1 (VX9)and Fe49Co49V2 (VX50) (at.%), were studied using electrochemical techniques including electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP) measurements. The morphology and composition of the alloy surfaces were investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion rate and surface roughness of both alloys increased as the concentration of NaOH in aqueous solution was raised. The presence of some protective elements in the composition of the alloys led to the formation of a spontaneous passive layer on the alloy surface. The higher resistance values of both alloys were associated with the magnitude of the dielectric properties of the passive films formed on their surfaces. Both alloys are classified as having outstanding resistance to corrosion, which results from the formation of a passive film that acts as an efficient barrier to corrosion in alkaline solution. PMID:29337992

Outstanding resistance and passivation behaviour of new Fe-Co metal-metal glassy alloys in alkaline media.

PubMed

Emran, Khadijah M; Al-Harbi, Albandaree K

2018-01-01

The electrochemical behavior of the oxide layers on two metal-metal glassy alloys, Fe78Co9Cr10Mo2Al1 (VX9)and Fe49Co49V2 (VX50) (at.%), were studied using electrochemical techniques including electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP) measurements. The morphology and composition of the alloy surfaces were investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion rate and surface roughness of both alloys increased as the concentration of NaOH in aqueous solution was raised. The presence of some protective elements in the composition of the alloys led to the formation of a spontaneous passive layer on the alloy surface. The higher resistance values of both alloys were associated with the magnitude of the dielectric properties of the passive films formed on their surfaces. Both alloys are classified as having outstanding resistance to corrosion, which results from the formation of a passive film that acts as an efficient barrier to corrosion in alkaline solution.

Passive Sampling Methods for Contaminated Sediments: Practical Guidance for Selection, Calibration, and Implementation

EPA Science Inventory

This article provides practical guidance on the use of passive sampling methods(PSMs) that target the freely dissolved concentration (Cfree) for improved exposure assessment of hydrophobic organic chemicals in sediments. Primary considerations for selecting a PSM for a specific a...

On the passive and semiconducting behavior of severely deformed pure titanium in Ringer's physiological solution at 37°C: A trial of the point defect model.

PubMed

Ansari, Ghazaleh; Fattah-Alhosseini, Arash

2017-06-01

The effects of sever plastic deformation through multi-pass accumulative roll bonding on the passive and semiconducting behavior of pure titanium is evaluated in Ringer's physiological solution at 37°C in the present paper. Produced results by polarization plots and electrochemical impedance spectroscopy measurements revealed a significant advance in the passive response of the nano-grained sample compared to that of the annealed pure titanium. Also, Mott-Schottky test results of the nano-grained pure titanium represented a lower donor density and reduced flat-band potential in the formed passive film in comparison with the annealed sample. Moreover, based on the Mott-Schottky analysis in conjunction with the point defect model, it was suggested that with increase in formation potential, the calculated donor density of both annealed and nano-grained samples decreases exponentially and the thickness of the passive film linearly increases. These observations were consistent with the point defect model predictions, considering that the point defects within the passive film are metal interstitials, oxygen vacancies, or both. From the viewpoint of passive and semiconducting behavior, nano-grained pure titanium appeared to be more suitable for implant applications in simulate human body environment compared to annealed pure titanium. Copyright © 2017 Elsevier B.V. All rights reserved.

40 CFR 1065.690 - Buoyancy correction for PM sample media.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Buoyancy correction for PM sample media. (a) General. Correct PM sample media for their buoyancy in air if you weigh them on a balance. The buoyancy correction depends on the sample media density, the density of air, and the density of the calibration weight used to calibrate the balance. The buoyancy...

A holistic passive integrative sampling approach for assessing the presence and potential impacts of waterborne environmental contaminants

USGS Publications Warehouse

Petty, J.D.; Huckins, J.N.; Alvarez, D.A.; Brumbaugh, W. G.; Cranor, W.L.; Gale, R.W.; Rastall, A.C.; Jones-Lepp, T. L.; Leiker, T.J.; Rostad, C. E.; Furlong, E.T.

2004-01-01

As an integral part of our continuing research in environmental quality assessment approaches, we have developed a variety of passive integrative sampling devices widely applicable for use in defining the presence and potential impacts of a broad array of contaminants. The semipermeable membrane device has gained widespread use for sampling hydrophobic chemicals from water and air, the polar organic chemical integrative sampler is applicable for sequestering waterborne hydrophilic organic chemicals, the stabilized liquid membrane device is used to integratively sample waterborne ionic metals, and the passive integrative mercury sampler is applicable for sampling vapor phase or dissolved neutral mercury species. This suite of integrative samplers forms the basis for a new passive sampling approach for assessing the presence and potential toxicological significance of a broad spectrum of environmental contaminants. In a proof-of-concept study, three of our four passive integrative samplers were used to assess the presence of a wide variety of contaminants in the waters of a constructed wetland, and to determine the effectiveness of the constructed wetland in removing contaminants. The wetland is used for final polishing of secondary-treatment municipal wastewater and the effluent is used as a source of water for a state wildlife area. Numerous contaminants, including organochlorine pesticides, polycyclic aromatic hydrocarbons, organophosphate pesticides, and pharmaceutical chemicals (e.g., ibuprofen, oxindole, etc.) were detected in the wastewater. Herein we summarize the results of the analysis of the field-deployed samplers and demonstrate the utility of this holistic approach.

NEW APPLICATION OF PASSIVE SAMPLING DEVICES FOR ASSESSMENT OF RESPIRATORY EXPOSURE TO PESTICIDES IN INDOOR AIR

EPA Science Inventory

The United States Environmental Protection Agency (EPA) has long maintained an interest in potential applications of passive sampling devices (PSDs) for estimating the concentrations of various pollutants in air. Typically PSDs were designed for the workplace monitoring of vola...

Air sampling procedures to evaluate microbial contamination: a comparison between active and passive methods in operating theatres.

PubMed

Napoli, Christian; Marcotrigiano, Vincenzo; Montagna, Maria Teresa

2012-08-02

Since air can play a central role as a reservoir for microorganisms, in controlled environments such as operating theatres regular microbial monitoring is useful to measure air quality and identify critical situations. The aim of this study is to assess microbial contamination levels in operating theatres using both an active and a passive sampling method and then to assess if there is a correlation between the results of the two different sampling methods. The study was performed in 32 turbulent air flow operating theatres of a University Hospital in Southern Italy. Active sampling was carried out using the Surface Air System and passive sampling with settle plates, in accordance with ISO 14698. The Total Viable Count (TVC) was evaluated at rest (in the morning before the beginning of surgical activity) and in operational (during surgery). The mean TVC at rest was 12.4 CFU/m3 and 722.5 CFU/m2/h for active and passive samplings respectively. The mean in operational TVC was 93.8 CFU/m3 (SD = 52.69; range = 22-256) and 10496.5 CFU/m2/h (SD = 7460.5; range = 1415.5-25479.7) for active and passive samplings respectively. Statistical analysis confirmed that the two methods correlate in a comparable way with the quality of air. It is possible to conclude that both methods can be used for general monitoring of air contamination, such as routine surveillance programs. However, the choice must be made between one or the other to obtain specific information.

Wallboard with Latent Heat Storage for Passive Solar Applications

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

Kedl, R.J.

2001-05-31

Conventional wallboard impregnated with octadecane paraffin [melting point-23 C (73.5 F)] is being developed as a building material with latent heat storage for passive solar and other applications. Impregnation was accomplished simply by soaking the wallboard in molten wax. Concentrations of wax in the combined product as high as 35% by weight can be achieved. Scale-up of the soaking process, from small laboratory samples to full-sized 4- by 8-ft sheets, has been successfully accomplished. The required construction properties of wallboard are maintained after impregnation, that is, it can be painted and spackled. Long-term, high-temperature exposure tests and thermal cycling testsmore » showed no tendency of the paraffin to migrate within the wallboard, and there was no deterioration of thermal energy storage capacity. In support of this concept, a computer model was developed to handle thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions and also by comparison with temperatures measured in wallboard during an experimentally generated thermal transient. Agreement between the model and known solution was excellent. Agreement between the model and thermal transient was good, only after the model was modified to allow the PCM to melt over a temperature range, rather than at a specific melting point. When the melting characteristics of the PCM (melting point, melting range, and heat of fusion), as determined from a differential scanning calorimeter plot, were used in the model, agreement between the model and transient data was very good. The confirmed computer model may now be used in conjunction with a building heating and cooling code to evaluate design parameters and operational characteristics of latent heat storage wallboard for passive solar applications.« less

Passive alcohol sensors tested in 3 states for youth alcohol enforcement

DOT National Transportation Integrated Search

1996-05-01

Passive alcohol sensors were tested in three states to determine their effectiveness in enforcing zero tolerance or low BAC laws for under 21 age drivers. The passive alcohol sensor was designed to sample the air immediately around the suspect for si...

Equilibrium Passive Sampling of POP in Lipid-Rich and Lean Fish Tissue: Quality Control Using Performance Reference Compounds.

PubMed

Rusina, Tatsiana P; Carlsson, Pernilla; Vrana, Branislav; Smedes, Foppe

2017-10-03

Passive sampling is widely used to measure levels of contaminants in various environmental matrices, including fish tissue. Equilibrium passive sampling (EPS) of persistent organic pollutants (POP) in fish tissue has been hitherto limited to application in lipid-rich tissue. We tested several exposure methods to extend EPS applicability to lean tissue. Thin-film polydimethylsiloxane (PDMS) passive samplers were exposed statically to intact fillet and fish homogenate and dynamically by rolling with cut fillet cubes. The release of performance reference compounds (PRC) dosed to passive samplers prior to exposure was used to monitor the exchange process. The sampler-tissue exchange was isotropic, and PRC were shown to be good indicators of sampler-tissue equilibration status. The dynamic exposures demonstrated equilibrium attainment in less than 2 days for all three tested fish species, including lean fish containing 1% lipid. Lipid-based concentrations derived from EPS were in good agreement with lipid-normalized concentrations obtained using conventional solvent extraction. The developed in-tissue EPS method is robust and has potential for application in chemical monitoring of biota and bioaccumulation studies.

Increased concentrations of polycyclic aromatic hydrocarbons in Alpine streams during annual snowmelt: investigating effects of sampling method, site characteristics, and meteorology.

PubMed

Shahpoury, Pourya; Hageman, Kimberly J; Matthaei, Christoph D; Alumbaugh, Robert E; Cook, Michelle E

2014-10-07

Silicone passive samplers and macroinvertebrates were used to measure time-integrated concentrations of polycyclic aromatic hydrocarbons (PAHs) in alpine streams during annual snowmelt. The three sampling sites were located near a main highway in Arthur's Pass National Park in the Southern Alps of New Zealand. A similar set of PAH congeners, composed of 2-4 rings, were found in silicone passive samplers and macroinvertebrates. The background PAH concentrations were similar at all sites, implying that proximity to the highway did not affect concentrations. In passive samplers, an increase of PAH concentrations by up to seven times was observed during snowmelt. In macroinvertebrates, the concentration changes were moderate; however, macroinvertebrate sampling did not occur during the main pulse observed in the passive samplers. The extent of vegetation in the catchment appeared to affect the concentration patterns seen at the different stream sites. A strong correlation was found between PAH concentrations in passive samplers and the amount of rainfall in the study area, indicating that the washout of contaminants from snowpack by rainfall was an important process.

Development of a passive sampler for gaseous mercury

NASA Astrophysics Data System (ADS)

Gustin, M. S.; Lyman, S. N.; Kilner, P.; Prestbo, E.

2011-10-01

Here we describe work toward development of the components of a cost effective passive sampling system for gaseous Hg that could be broadly deployed by nontechnical staff. The passive sampling system included an external shield to reduce turbulence and exposure to precipitation and dust, a diffusive housing that directly protects the collection surface during deployment and handling, and a collection surface. A protocol for cleaning and deploying the sampler and an analytical method were developed. Our final design consisted of a polycarbonate external shield enclosing a custom diffusive housing made from expanded PTFE tubing. Two collection surfaces were investigated, gold sputter-coated quartz plates and silver wires. Research showed the former would require extensive quality control for use, while the latter had interferences with other atmosphere constituents. Although the gold surface exhibited the best performance over space and time, gradual passivation would limit reuse. For both surfaces lack of contamination during shipping, deployment and storage indicated that the handling protocols developed worked well with nontechnical staff. We suggest that the basis for this passive sampling system is sound, but further exploration and development of a reliable collection surface is needed.

Effect of surface pre-treatments on biocompatibility of magnesium.

PubMed

Lorenz, Carla; Brunner, Johannes G; Kollmannsberger, Philip; Jaafar, Leila; Fabry, Ben; Virtanen, Sannakaisa

2009-09-01

This study reports the influence of Mg surface passivation on the survival rate of human HeLa cells and mouse fibroblasts in cell culture experiments. Polished samples of commercially pure Mg show high reactivity in the cell culture medium, leading to a pH shift in the alkaline direction, and therefore cell adhesion and survival is strongly impaired. Passivation of the Mg surface in 1M NaOH can strongly enhance cell survival. The best initial cell adhesion is observed for Mg samples incubated in simulated body fluid (M-SBF), which leads to the formation of a biomimetic, amorphous Ca/Mg-phosphate layer with high surface roughness. This surface layer, however, passivates and seals the Mg surface only partially. Subsequent Mg dissolution leads to a significantly stronger pH increase compared to NaOH-passivated samples, which prevents long-term cell survival. These results demonstrate that surface passivation with NaOH and M-SBF together with the associated changes of surface reactivity, chemistry and roughness provide a viable strategy to facilitate cell survival on otherwise non-biocompatible Mg surfaces.

Thermal control materials on EOIM-3

NASA Technical Reports Server (NTRS)

Finckenor, Miria M.; Linton, Roger C.; Kamenetzky, Rachel R.; Vaughn, Jason A.

1995-01-01

Thermal control paints, anodized aluminum, and beta cloth samples were flown on STS-46 as part of the Evaluation of Oxygen Interaction with Materials Experiment (EOIM-3). The thermal control paints flown on EOIM-3 include ceramic and polyurethane-based paints. Passively exposed samples are compared to actively heated samples and controlled exposure samples. Optical property measurements of absorptivity, emissivity, and spectrofluorescence are presented for each paint. Several variations of anodized aluminum, including chromic acid anodize, sulfuric acid anodize, and boric/sulfuric acid anodize were flown on the actively heated trays and the passive exposure trays. The post-flight optical properties are within tolerances for these materials. Also flown were two samples of yellow anodized aluminum. The yellow anodized aluminum samples darkened noticeably. Samples of aluminized and unaluminized beta cloth, a fiberglass woven mat impregnated with TFE Teflon, were flown with passive exposure to the space environment. Data from this part of the experiment is correlated to observations from LDEF and erosion of the Teflon thin film samples also flown on EOIM-3 and LDEF.

Microwave gain medium with negative refractive index.

PubMed

Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

2014-12-19

Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false PM sampling media (e.g., filters... Specified Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and tare weighing. Before an emission test, take the following steps to prepare PM sampling media (e.g., filters) and equipment...

Passive Sampling in Regulatory Chemical Monitoring of Nonpolar Organic Compounds in the Aquatic Environment

EPA Science Inventory

We reviewed compliance monitoring requirements in the European Union (EU), the United States(USA), and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic (OSPAR), and evaluated if these are met by passive sampling methods for nonpola...

The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

NASA Astrophysics Data System (ADS)

Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

2013-01-01

The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

The Effects of Applied Stress and Sensitization on the Passive Film Stability of Al-Mg Alloys

DTIC Science & Technology

2013-06-01

and residual tensile and compressive stresses impact the passive layer film and the material’s electrochemistry. Sample plates of AA5083 were...electrochemistry. Sample plates of AA5083 were sensitized to different levels to promote the formation of intergranular β phase (Al3Mg2). The...41  A.  MATERIAL PROCESSING: FABRICATION AND APPLIED STRESSES OF TEST SAMPLES

Changes in national park visitation (2000-2008) and interest in outdoor activities (1993-2008)

Treesearch

Rodney B. Warnick; Michael A. Schuett; Walt Kuentzel; Thomas A. More

2010-01-01

This paper addresses Pergams and Zaradic's (2006) assertions that recent national park visitation has declined sharply and that these declines are directly related to the increased use of electronic media and passive forms of entertainment. We analyzed two large, national datasets that have used consistently replicated methods of annual data collection over a...

Music Videos and Sexual Risk in African American Adolescent Girls: Gender, Power and the Need for Media Literacy

ERIC Educational Resources Information Center

Robillard, Alyssa

2012-01-01

Background: Music videos contain sexual content often reflecting women as promiscuous, submissive, or passive. Few studies have examined gender- and sex-related attitudes in African American females, particularly across genres of music videos. Purpose: Using constructs from Cultivation Theory, Theory of Gender and Power and Social Cognitive…

Ending the "War against Youth": Social Media and Hip-Hop Culture as Sites of Resistance, Transformation and (Re) Conceptualization

ERIC Educational Resources Information Center

Porfilio, Brad J.; Roychoudhury, Debangshu; Gardner, Lauren

2013-01-01

The purpose of this essay is to ameliorate the virulent discursive and material attack against today's "border" youth launched by large-scale corporations and Western politicians. Specifically, the authors problematize the dominant tropes of youth being mindless, obedient objects who passively accept the stark social reality they…

The active and passive sampling of benzene, toluene, ethyl benzene and xylenes compounds using the inside needle capillary adsorption trap device.

PubMed

Shojania, S; Oleschuk, R D; McComb, M E; Gesser, H D; Chow, A

1999-08-23

A new and simple method of solventless extraction of volatile organic compounds (VOCs) from air is presented. The sampling device has an adsorbing carbon coating on the interior surface of a hollow needle, and is called the inside needle capillary adsorption trap (INCAT). This paper describes a study of the reproducibility in the preparation and sampling of the INCAT device. In addition, this paper examines the effects of sample volume in active sampling and exposure time in passive sampling on the analyte adsorption. Analysis was achieved by sampling the air from an environmental chamber doped with benzene, toluene, ethyl benzene and xylenes (BTEX) compounds. Initial rates of adsorption were found to vary among the different compounds, but ranged from 0.0099 to 0.016 nmol h(-1) for passive sampling and from 2.2 to 10 nmol h(-1) for active sampling. Analysis was done by thermal desorption of the adsorbed compounds directly into a gas chromatograph injection port. Quantification of the analysis was done by comparison to actively sampled activated carbon solid phase extraction (SPE) measurements.

Natural Arabidopsis brx loss-of-function alleles confer root adaptation to acidic soil.

PubMed

Gujas, Bojan; Alonso-Blanco, Carlos; Hardtke, Christian S

2012-10-23

Soil acidification is a major agricultural problem that negatively affects crop yield. Root systems counteract detrimental passive proton influx from acidic soil through increased proton pumping into the apoplast, which is presumably also required for cell elongation and stimulated by auxin. Here, we found an unexpected impact of extracellular pH on auxin activity and cell proliferation rate in the root meristem of two Arabidopsis mutants with impaired auxin perception, axr3 and brx. Surprisingly, neutral to slightly alkaline media rescued their severely reduced root (meristem) growth by stimulating auxin signaling, independent of auxin uptake. The finding that proton pumps are hyperactive in brx roots could explain this phenomenon and is consistent with more robust growth and increased fitness of brx mutants on overly acidic media or soil. Interestingly, the original brx allele was isolated from a natural stock center accession collected from acidic soil. Our discovery of a novel brx allele in accessions recently collected from another acidic sampling site demonstrates the existence of independently maintained brx loss-of-function alleles in nature and supports the notion that they are advantageous in acidic soil pH conditions, a finding that might be exploited for crop breeding. Copyright © 2012 Elsevier Ltd. All rights reserved.

Study of Nox Levels At The Castellon Area (spain) By Means of Passive Samplers

NASA Astrophysics Data System (ADS)

Delgado, J. M.; Esteve, V.

Nitrogen oxides are emitted by mobile sources like traffic, heating engines and indus- tries. In the case of La Plana de Castellon area, the cities, the industrial area called El Serrallo (with its oil refinery and power plant), the tile factories and the main roads (A7-E15 and N-340), all they are the main pollutant focus of NOx. Those pollutants are precursors of tropospheric ozone formation. The aim of this work is the study of nitrogen oxides levels in La Plana de Castellon area, by means of passive samplers and stand relationships between NOx levels and ozone levels both measured with pas- sive samplers. The measurement campaign is made during summer, the higher pho- tochemical activity period (from May to September) in order to obtain the necessary data of NOx levels to make the relationship with measured ozone levels. Measuring campaing has been divided into sampling periods of one week. Twelve samples are collected each sampling period to cover an interest area of 1400 Km2, Two of these samples are laboratory blanks, four are situated at reference points (beside an auto- matic NOx sampler), one is situated at A7-E15 expressway, other at the main road N-340 and another one in a hard traffic road. The other three are placed in the main cities (Castellon and Benicassim). We employ Radielloo samplers developed by Dr. Cocheo at Fondazione Salvatore Maugeri. Samples located far from the main roads, at countryside show the lowest levels of NOx, lower than 10 ppb. Samples located at Castellon city show a difference between downtown and boundaries of about 33% higher at downtown, raising from 11 ppb to 14,5 ppb of NOx. The highest levels of NOx are measured at roads and their surroundings with medium levels of 14,3 ppb of NOx. Moreover, the sample located close to the expressway raises its level until 18 ppb of NOx, 53,4% higher than the media of all the samples measured. We would like to thank Dr. M. Wolfson(Harvard University), Dr. Carlos Felis (Conselleria de Medi Ambient) and Ms. C. Clemente for their contribution and work on this project as well as to Generalitat Valenciana for the FPI grant.

Passivation effect on optical and electrical properties of molecular beam epitaxy-grown HgCdTe/CdTe/Si layers

NASA Astrophysics Data System (ADS)

Kiran, Rajni; Mallick, Shubhrangshu; Hahn, Suk-Ryong; Lee, T. S.; Sivananthan, Sivalingam; Ghosh, Siddhartha; Wijewarnasuriya, P. S.

2006-06-01

The effects of passivation with two different passivants, ZnS and CdTe, and two different passivation techniques, physical vapor deposition (PVD) and molecular beam epitaxy (MBE), were quantified in terms of the minority carrier lifetime and extracted surface recombination velocity on both MBE-grown medium-wavelength ir (MWIR) and long-wavelength ir HgCdTe samples. A gradual increment of the minority carrier lifetime was reported as the passivation technique was changed from PVD ZnS to PVD CdTe, and finally to MBE CdTe, especially at low temperatures. A corresponding reduction in the extracted surface recombination velocity in the same order was also reported for the first time. Initial data on the 1/ f noise values of as-grown MWIR samples showed a reduction of two orders of noise power after 1200-Å ZnS deposition.

Performance Evaluation of Automated Passive Capillary Sampler for Estimating Water Drainage in the Vadose Zone

USDA-ARS?s Scientific Manuscript database

Passive capillary samplers (PCAPs) are widely used to monitor, measure and sample drainage water under saturated and unsaturated soil conditions in the vadose zone. The objective of this study was to evaluate the performance and accuracy of automated passive capillary sampler for estimating drainage...

Measurement of gaseous PAHs with an innovative passive sampler in community exposure studies

EPA Science Inventory

A sensitive, simple, and cost-effective passive sampling methodology was developed to quantify gaseous polycyclic aromatic hydrocarbons (PAHs) in personal, indoor and outdoor air. A Fan-Lioy passive PAH sampler (FL-PPS) is constructed from four 80 sections of 1 cm long SPB-5 GC c...

An Application of Passive Samplers to Understand Atmospheric Mercury Concentration and Dry Deposition Spatial Distributions

EPA Science Inventory

Two modified passive samplers were evaluated at multiple field locations. The sampling rate (SR) of the modified polyurethane foam (PUF)-disk passive sampler for total gaseous mercury (TGM) using gold-coated quartz fiber filters (GcQFF) and gaseous oxidized mercury (GOM) using io...

Evaluating the Relationship between Equilibrium Passive ...

EPA Pesticide Factsheets

Objectives. This review evaluates passive sampler uptake of hydrophobic organic contaminants (HOCs) in water column and interstitial water exposures as a surrogate for organism bioaccumulation. Approach/Activities. Fifty-five studies were found where both passive sampler uptake and organism bioaccumulation were measured and 19 of these investigations provided direct comparisons relating passive sampler uptake and organism bioaccumulation. Polymers compared included low density polyethylene (LDPE), polyoxymethylene (POM), and polydimethylsiloxane (PDMS), and organisms ranged from polychaetes and oligochaetes to bivalves, aquatic insects, and gastropods. Regression equations correlating bioaccumulation (CL) and passive sampler uptake (CPS) were used to assess the strength of observed relationships. Results/Lessons Learned. Passive sampling based concentrations resulted in strong logarithmic regression relationships, most of which were within one to two orders of magnitude of measured bioaccumulation. Mean coefficients of determination (r2) for LDPE, PDMS and POM were 0.68, 0.76 and 0.58, respectively. For the available raw data, the mean ratio of CL and CPS was 10.8 ± 18.4 (n = 609). Passive sampler uptake and bioaccumulation were not found to be identical (i.e., CPS ≠ CL) but the logarithmic-based relationships between these values were consistently linear and predictive. This review concludes that in many applications passive sampling may serve as a

Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae

PubMed Central

Murrah, Kyle A.; Pang, Bing; Richardson, Stephen; Perez, Antonia; Reimche, Jennifer; King, Lauren; Wren, John; Swords, W. Edward

2014-01-01

Streptococcus pneumoniae strains lacking capsular polysaccharide have been increasingly reported in carriage and disease contexts. Since most cases of otitis media involve more than one bacterial species, we aimed to determine the capacity of a nonencapsulated S. pneumoniae clinical isolate to induce disease in the context of a single-species infection and as a polymicrobial infection with nontypeable Haemophilus influenzae. Using the chinchilla model of otitis media, we found that nonencapsulated S. pneumoniae colonizes the nasopharynx following intranasal inoculation, but does not readily ascend into the middle ear. However, when we inoculated nonencapsulated S. pneumoniae directly into the middle ear, the bacteria persisted for two weeks post-inoculation and induced symptoms consistent with chronic otitis media. During coinfection with nontypeable H. influenzae, both species persisted for one week and induced polymicrobial otitis media. We also observed that nontypeable H. influenzae conferred passive protection from killing by amoxicillin upon S. pneumoniae from within polymicrobial biofilms in vitro. Therefore, based on these results, we conclude that nonencapsulated pneumococci are a potential causative agent of chronic/recurrent otitis media, and can also cause mutualistic infection with other opportunists, which could complicate treatment outcomes. PMID:26014114

Overview of the U.S. EPA/SERDP/ESTCP: Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments: User’s Manual

EPA Science Inventory

Passive sampling can be used for applications at contaminated sediment sites including performing assessments of contaminant bioavailability (i.e., freely dissolved concentration (Cfree)), conducting remedial investigations and feasibility studies, and assessing the potential for...

Overview of the U.S. EPA/SERDP/ESTCP: Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments: User’s Manual.

EPA Science Inventory

Passive sampling is used for applications at contaminated sediment sites including performing assessments of contaminant bioavailability (i.e., freely dissolved concentration (Cfree)), conducting remedial investigations and feasibility studies, and assessing the potential for con...

Passive Sampling to Measure Baseline Dissolved Persistent Organic Pollutant Concentrations in the Water Column of the Palos Verdes Shelf Superfund Site

EPA Science Inventory

Passive sampling was used to deduce water concentrations of persistent organic pollutants (POPs) in the vicinity of a marine Superfund site on the Palos Verdes Shelf, California, USA. Pre-calibrated solid phase microextraction (SPME) fibers and polyethylene (PE) strips that were...

Developing Sediment Remediation Goals at Superfund Sites Based on Pore Water for the Protection of Benthic Organisms from Direct Toxicity to Non-ionic Organic Contaminants

EPA Science Inventory

A methodology for developing remediation goals for sites with contaminated sediments is provided. The remediation goals are based upon the concentrations of chemicals in the sediment interstitial water measured using the passive sampling technique. The passive sampling technique ...

KSC-2015-1216

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Sam Thurman, deputy project manager for NASA's Soil Moisture Active Passive mission, or SMAP, addresses the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

Air sampling procedures to evaluate microbial contamination: a comparison between active and passive methods in operating theatres

PubMed Central

2012-01-01

Background Since air can play a central role as a reservoir for microorganisms, in controlled environments such as operating theatres regular microbial monitoring is useful to measure air quality and identify critical situations. The aim of this study is to assess microbial contamination levels in operating theatres using both an active and a passive sampling method and then to assess if there is a correlation between the results of the two different sampling methods. Methods The study was performed in 32 turbulent air flow operating theatres of a University Hospital in Southern Italy. Active sampling was carried out using the Surface Air System and passive sampling with settle plates, in accordance with ISO 14698. The Total Viable Count (TVC) was evaluated at rest (in the morning before the beginning of surgical activity) and in operational (during surgery). Results The mean TVC at rest was 12.4 CFU/m3 and 722.5 CFU/m2/h for active and passive samplings respectively. The mean in operational TVC was 93.8 CFU/m3 (SD = 52.69; range = 22-256) and 10496.5 CFU/m2/h (SD = 7460.5; range = 1415.5-25479.7) for active and passive samplings respectively. Statistical analysis confirmed that the two methods correlate in a comparable way with the quality of air. Conclusion It is possible to conclude that both methods can be used for general monitoring of air contamination, such as routine surveillance programs. However, the choice must be made between one or the other to obtain specific information. PMID:22853006

Onsite wastewater nitrogen reduction with expanded media and elemental sulfur biofiltration.

PubMed

Smith, D P

2012-01-01

A passive biofiltration process has been developed to enhance nitrogen removal from onsite sanitation water. The system employs an initial unsaturated vertical flow biofilter with expanded clay media (nitrification), followed in series by a horizontal saturated biofilter for denitrification containing elemental sulfur media as electron donor. A small-scale prototype was operated continuously over eight months on primary wastewater effluent with total nitrogen (TN) of 72.2 mg/L. The average hydraulic loading to the unsaturated biofilter surface was 11.9 cm/day, applied at a 30 min dosing cycle. Average effluent TN was 2.6 mg/L and average TN reduction efficiency was 96.2%. Effluent nitrogen was 1.7 mg/L as organic N, 0.93 mg/L as ammonium (NH(4)-N), and 0.03 as oxidized (NO(3) + NO(2)) N. There was no surface clogging of unsaturated media, nitrate breakthrough, or replenishment of sulfur media over eight months. Visual and microscopic examinations revealed substantially open pores with limited material accumulation on the upper surface of the unsaturated media. Material accumulation was observed at the inlet zone of the denitrification biofilter, and sulfur media exhibited surface cavities consistent with oxidative dissolution. Two-stage biofiltration is a simple and resilient system for achieving high nitrogen reductions in onsite wastewater.

Try to be healthy, but don't forgo your masculinity: deconstructing men's health discourse in the media.

PubMed

Gough, Brendan

2006-11-01

The emergence of discourse around men's health has been evident now for at least 10 years across academic, policy and media texts. However, recent research has begun to question some of the assumptions presented concerning masculinity and men's health, particularly within popular media representations. The present paper builds on previous research by interrogating the construction of men's health presented in a recent special feature of a UK national newspaper (The Observer, November 27, 2005). The dataset was subjected to intensive scrutiny using techniques from discourse analysis. Several inter-related discursive patterns were identified which drew upon essentialist notions of masculinity, unquestioned differences between men and women, and constructions of men as naïve, passive and in need of dedicated help. The implications of such representations for health promotion are discussed.

Transferring mixtures of chemicals from sediment to a bioassay using silicone-based passive sampling and dosing.

PubMed

Mustajärvi, Lukas; Eriksson-Wiklund, Ann-Kristin; Gorokhova, Elena; Jahnke, Annika; Sobek, Anna

2017-11-15

Environmental mixtures of chemicals consist of a countless number of compounds with unknown identity and quantity. Yet, chemical regulation is mainly built around the assessment of single chemicals. Existing frameworks for assessing the toxicity of mixtures require that both the chemical composition and quantity are known. Quantitative analyses of the chemical composition of environmental mixtures are however extremely challenging and resource-demanding. Bioassays may therefore serve as a useful approach for investigating the combined toxicity of environmental mixtures of chemicals in a cost-efficient and holistic manner. In this study, an unknown environmental mixture of bioavailable semi-hydrophobic to hydrophobic chemicals was sampled from a contaminated sediment in a coastal Baltic Sea area using silicone polydimethylsiloxane (PDMS) as an equilibrium passive sampler. The chemical mixture was transferred to a PDMS-based passive dosing system, and its applicability was demonstrated using green algae Tetraselmis suecica in a cell viability assay. The proportion of dead cells increased significantly with increasing exposure level and in a dose-response manner. At an ambient concentration, the proportion of dead cells in the population was nearly doubled compared to the control; however, the difference was non-significant due to high inter-replicate variability and a low number of replicates. The validation of the test system regarding equilibrium sampling, loading efficiency into the passive dosing polymer, stability of the mixture composition, and low algal mortality in control treatments demonstrates that combining equilibrium passive sampling and passive dosing is a promising tool for investigating the toxicity of bioavailable semi-hydrophobic and hydrophobic chemicals in complex environmental mixtures.

Chemical and toxicologic assessment of organic contaminants in surface water using passive samplers

USGS Publications Warehouse

Alvarez, D.A.; Cranor, W.L.; Perkins, S.D.; Clark, R.C.; Smith, S.B.

2008-01-01

Passive sampling methodologies were used to conduct a chemical and toxicologic assessment of organic contaminants in the surface waters of three geographically distinct agricultural watersheds. A selection of current-use agrochemicals and persistent organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides, were targeted using the polar organic chemical integrative sampler (POCIS) and the semipermeable membrane device passive samplers. In addition to the chemical analysis, the Microtox assay for acute toxicity and the yeast estrogen screen (YES) were conducted as potential assessment tools in combination with the passive samplers. During the spring of 2004, the passive samplers were deployed for 29 to 65 d at Leary Weber Ditch, IN; Morgan Creek, MD; and DR2 Drain, WA. Chemical analysis of the sampler extracts identified the agrochemicals predominantly used in those areas, including atrazine, simazine, acetochlor, and metolachlor. Other chemicals identified included deethylatrazine and deisopropylatrazine, trifluralin, fluoranthene, pyrene, cis- and trans-nonachlor, and pentachloroanisole. Screening using Microtox resulted in no acutely toxic samples. POCIS samples screened by the YES assay failed to elicit a positive estrogenic response. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

A Passive Earth-Entry Capsule for Mars Sample Return

NASA Technical Reports Server (NTRS)

Mitcheltree, Robert A.; Kellas, Sotiris

1999-01-01

A combination of aerodynamic analysis and testing, aerothermodynamic analysis, structural analysis and testing, impact analysis and testing, thermal analysis, ground characterization tests, configuration packaging, and trajectory simulation are employed to determine the feasibility of an entirely passive Earth entry capsule for the Mars Sample Return mission. The design circumvents the potential failure modes of a parachute terminal descent system by replacing that system with passive energy absorbing material to cushion the Mars samples during ground impact. The suggested design utilizes a spherically blunted 45-degree half-angle cone forebody with an ablative heat shield. The primary structure is a hemispherical, composite sandwich enclosing carbon foam energy absorbing material. Though no demonstration test of the entire system is included, results of the tests and analysis presented indicate that the design is a viable option for the Mars Sample Return Mission.

Characterization of five passive sampling devices for monitoring of pesticides in water.

PubMed

Ahrens, Lutz; Daneshvar, Atlasi; Lau, Anna E; Kreuger, Jenny

2015-07-31

Five different passive sampler devices were characterized under laboratory conditions for measurement of 124 legacy and current used pesticides in water. In addition, passive sampler derived time-weighted average (TWA) concentrations were compared to time-integrated active sampling in the field. Sampling rates (RS) and passive sampler-water partition coefficients (KPW) were calculated for individual pesticides using silicone rubber (SR), polar organic chemical integrative sampler (POCIS)-A, POCIS-B, Chemcatcher(®) SDB-RPS and Chemcatcher(®) C18. The median RS (Lday(-1)) decreased as follows: SR (0.86)>POCIS-B (0.22)>POCIS-A (0.18)>Chemcatcher(®) SDB-RPS (0.05)>Chemcatcher(®) C18 (0.02), while the median logKPW (Lkg(-1)) decreased as follows: POCIS-B (4.78)>POCIS-A (4.56)>Chemcatcher(®) SDB-RPS (3.17)>SR (3.14)>Chemcatcher(®)C18 (2.71). The uptake of the selected compounds depended on their physicochemical properties, i.e. SR showed a better uptake for more hydrophobic compounds (log octanol-water partition coefficient (KOW)>5.3), whereas POCIS-A, POCIS-B and Chemcatcher(®) SDB-RPS were more suitable for hydrophilic compounds (logKOW<0.70). Overall, the comparison between passive sampler and time-integrated active sampler concentrations showed a good agreement and the tested passive samplers were suitable for capturing compounds with a wide range of KOW's in water. Copyright © 2015 Elsevier B.V. All rights reserved.

Calibration and field application of passive sampling for episodic exposure to polar organic pesticides in streams.

PubMed

Fernández, Diego; Vermeirssen, Etiënne L M; Bandow, Nicole; Muñoz, Katherine; Schäfer, Ralf B

2014-11-01

Rainfall-triggered runoff is a major driver of pesticide input in streams. Only few studies have examined the suitability of passive sampling to quantify such episodic exposures. In this study, we used Empore™ styrene-divinylbenzene reverse phase sulfonated disks (SDB disks) and event-driven water samples (EDS) to assess exposure to 15 fungicides and 4 insecticides in 17 streams in a German vineyard area during 4 rainfall events. We also conducted a microcosm experiment to determine the SDB-disk sampling rates and provide a free-software solution to derive sampling rates under time-variable exposure. Sampling rates ranged from 0.26 to 0.77 L d(-1) and time-weighted average (TWA) concentrations from 0.05 to 2.11 μg/L. The 2 sampling systems were in good agreement and EDS exceeded TWA concentrations on average by a factor of 3. Our study demonstrates that passive sampling is suitable to quantify episodic exposures from polar organic pesticides. Copyright © 2014 Elsevier Ltd. All rights reserved.

Coping Strategies of International Chinese Undergraduates in Response to Academic Challenges in U.S. Colleges

ERIC Educational Resources Information Center

Heng, Tang

2018-01-01

Background/Context: One in three international students in the U.S. comes from China, propelled by a steep increase in undergraduate enrollment in U.S. colleges. This phenomenon has been accompanied by negative media discourse that portrays them as needy, passive, and unable to cope with their new educational demands. Purpose/Objective: Using a…

Examining the Blogging Habits of Agricultural Leadership Students: Understanding Motivation, Use, and Self-Efficacy

ERIC Educational Resources Information Center

Bumguardner, Kalee M.; Strong, Robert; Murphrey, Theresa Pesl; Dooley, Larry M.

2014-01-01

Blogging is a form of social media and student engagement is at the center of blogging. The benefits of blogging include ease in making writing easier to share, encouraging students to write outside of the classroom, and supporting group collaboration. The findings suggest students are more passive in their blogging experiences, as the data found…

"It Makes You Think More when You Watch Things": Scaffolding for Historical Inquiry Using Film in the Middle School Classroom

ERIC Educational Resources Information Center

Woelders, Adam

2007-01-01

Students' understanding of history may be shaped less by their social studies teachers than by the powerfully ubiquitous, historically themed media images they passively consume outside of school. In this article, the author describes two strategies conducted during a classroom-based action research study designed to explore how historically…

Are Contemporary Media Images Which Seem to Display Women as Sexually Empowered Actually Harmful to Women?

ERIC Educational Resources Information Center

Halliwell, Emma; Malson, Helen; Tischner, Irmgard

2011-01-01

There has been a shift in the depiction of women in advertising from objectifying representations of women as passive sex objects to agentic sexual representations where the women appear powerful and in control (Gill, 2007a, 2008), and there is substantial evidence that these representations have a negative impact on women's body image. However,…

Developing sediment remediation goals at superfund sites based on pore water for the protection of benthic organisms from direct toxicity to non-ionic organic contaminants (presentation)

EPA Science Inventory

Passive sampling is becoming a frequently used measurement technique at Superfund sites with contaminated sediments. Passive sampling measures the concentrations of freely dissolved chemicals (Cfrees) in the sediment pore water. Cfree has been found to be a very practical means f...

Stability of monitoring weak changes in multiply scattering media with ambient noise correlation: laboratory experiments.

PubMed

Hadziioannou, Céline; Larose, Eric; Coutant, Olivier; Roux, Philippe; Campillo, Michel

2009-06-01

Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics, and engineering. Usually, this is done under the assumption that a properly reconstructed Green function (GF), as well as stable background noise sources, is necessary. In order to further develop this monitoring technique, a laboratory experiment was performed in the 2.5 MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Present results show that temperature changes in the medium can be observed even if the GF of the medium is not reconstructed. Moreover, this article establishes that the GF reconstruction in the correlations is not a necessary condition: The only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure.

Mapping the spatial distribution and time evolution of snow water equivalent with passive microwave measurements

USGS Publications Warehouse

Guo, J.; Tsang, L.; Josberger, E.G.; Wood, A.W.; Hwang, J.-N.; Lettenmaier, D.P.

2003-01-01

This paper presents an algorithm that estimates the spatial distribution and temporal evolution of snow water equivalent and snow depth based on passive remote sensing measurements. It combines the inversion of passive microwave remote sensing measurements via dense media radiative transfer modeling results with snow accumulation and melt model predictions to yield improved estimates of snow depth and snow water equivalent, at a pixel resolution of 5 arc-min. In the inversion, snow grain size evolution is constrained based on pattern matching by using the local snow temperature history. This algorithm is applied to produce spatial snow maps of Upper Rio Grande River basin in Colorado. The simulation results are compared with that of the snow accumulation and melt model and a linear regression method. The quantitative comparison with the ground truth measurements from four Snowpack Telemetry (SNOTEL) sites in the basin shows that this algorithm is able to improve the estimation of snow parameters.

Passive Sampling for Indoor and Outdoor Exposures to Chlorpyrifos, Azinphos-Methyl, and Oxygen Analogs in a Rural Agricultural Community.

PubMed

Gibbs, Jenna L; Yost, Michael G; Negrete, Maria; Fenske, Richard A

2017-03-01

Recent studies have highlighted the increased potency of oxygen analogs of organophosphorus pesticides. These pesticides and oxygen analogs have previously been identified in the atmosphere following spray applications in the states of California and Washington. We used two passive sampling methods to measure levels of the ollowing organophosphorus pesticides: chlorpyrifos, azinphos-methyl, and their oxygen analogs at 14 farmworker and 9 non-farmworker households in an agricultural region of central Washington State in 2011. The passive methods included polyurethane foam passive air samplers deployed outdoors and indoors and polypropylene deposition plates deployed indoors. We collected cumulative monthly samples during the pesticide application seasons and during the winter season as a control. Monthly outdoor air concentrations ranged from 9.2 to 199 ng/m 3 for chlorpyrifos, 0.03 to 20 ng/m 3 for chlorpyrifos-oxon, < LOD (limit of detection) to 7.3 ng/m 3 for azinphos-methyl, and < LOD to 0.8 ng/m 3 for azinphos-methyl-oxon. Samples from proximal households (≤ 250 m) had significantly higher outdoor air concentrations of chlorpyrifos, chlorpyrifos-oxon, and azinphos-methyl than did samples from nonproximal households ( p ≤ 0.02). Overall, indoor air concentrations were lower than outdoors. For example, all outdoor air samples for chlorpyrifos and 97% of samples for azinphos-methyl were > LOD. Indoors, only 78% of air samples for chlorpyrifos and 35% of samples for azinphos-methyl were > LOD. Samples from farmworker households had higher indoor air concentrations of both pesticides than did samples from non-farmworker households. Mean indoor and outdoor air concentration ratios for chlorpyrifos and azinphos-methyl were 0.17 and 0.44, respectively. We identified higher levels in air and on surfaces at both proximal and farmworker households. Our findings further confirm the presence of pesticides and their oxygen analogs in air and highlight their potential for infiltration of indoor living environments. Citation: Gibbs JL, Yost MG, Negrete M, Fenske RA. 2017. Passive sampling for indoor and outdoor exposures to chlorpyrifos, azinphos-methyl, and oxygen analogs in a rural agricultural community. Environ Health Perspect 125:333-341; http://dx.doi.org/10.1289/EHP425.

Should health organizations use web 2.0 media in times of an infectious disease crisis? An in-depth qualitative study of citizens' information behavior during an EHEC outbreak.

PubMed

van Velsen, Lex; van Gemert-Pijnen, Julia E W C; Beaujean, Desirée J M A; Wentzel, Jobke; van Steenbergen, Jim E

2012-12-20

Web 2.0 media (eg, Facebook, Wikipedia) are considered very valuable for communicating with citizens in times of crisis. However, in the case of infectious disease outbreaks, their value has not been determined empirically. In order to be able to take full advantage of Web 2.0 media in such a situation, the link between these media, citizens' information behavior, and citizens' information needs has to be investigated. The goal of our study was to assess citizens' Web 2.0 media use during an infectious disease outbreak and to determine which Web 2.0 medium is used for which goal. With this information, we wanted to formulate recommendations for health organizations that consider using Web 2.0 media as part of their communication strategy during an infectious disease outbreak. A total of 18 student participants kept an information diary for 4 weeks during the 2011 enterohemorrhagic E. coli (EHEC) outbreak in Germany. Of them, 9 lived at the epicenter of the outbreak and 9 of them at some distance. The diaries were supplemented by a qualitative pre-survey (demographics) and postsurvey (questioning their satisfaction with information provision during the outbreak). The Internet appeared to be the most popular medium for passively receiving EHEC-related information, with news websites and websites of newspapers as the most consulted sources. Twitter was used for receiving information to a small degree, while Facebook played virtually no role. Participants indicated that they thought information posted on Twitter or Facebook was not reliable or was out of place. When actively seeking information, online newspapers and wikis were important sources. Several causes for (dis)satisfaction with information provision were uncovered: source credibility, contradicting messages, and a need for closure. During an infectious disease outbreak, our small sample of students did not see social media (like Facebook and Twitter) as suitable or reliable sources for communicating information, but primarily viewed them as a tool for communicating with friends. Wikis, however, did fill several information needs, especially when citizens are actively searching for information. For many, source credibility is an important asset of information usefulness. Finally, we provide several general recommendations for communicating with citizens during an infectious disease outbreak.

Should Health Organizations Use Web 2.0 Media in Times of an Infectious Disease Crisis? An In-depth Qualitative Study of Citizens’ Information Behavior During an EHEC Outbreak

PubMed Central

van Gemert-Pijnen, Julia E.W.C; Beaujean, Desirée J.M.A; Wentzel, Jobke; van Steenbergen, Jim E

2012-01-01

Background Web 2.0 media (eg, Facebook, Wikipedia) are considered very valuable for communicating with citizens in times of crisis. However, in the case of infectious disease outbreaks, their value has not been determined empirically. In order to be able to take full advantage of Web 2.0 media in such a situation, the link between these media, citizens’ information behavior, and citizens’ information needs has to be investigated. Objective The goal of our study was to assess citizens’ Web 2.0 media use during an infectious disease outbreak and to determine which Web 2.0 medium is used for which goal. With this information, we wanted to formulate recommendations for health organizations that consider using Web 2.0 media as part of their communication strategy during an infectious disease outbreak. Methods A total of 18 student participants kept an information diary for 4 weeks during the 2011 enterohemorrhagic E. coli (EHEC) outbreak in Germany. Of them, 9 lived at the epicenter of the outbreak and 9 of them at some distance. The diaries were supplemented by a qualitative pre-survey (demographics) and postsurvey (questioning their satisfaction with information provision during the outbreak). Results The Internet appeared to be the most popular medium for passively receiving EHEC-related information, with news websites and websites of newspapers as the most consulted sources. Twitter was used for receiving information to a small degree, while Facebook played virtually no role. Participants indicated that they thought information posted on Twitter or Facebook was not reliable or was out of place. When actively seeking information, online newspapers and wikis were important sources. Several causes for (dis)satisfaction with information provision were uncovered: source credibility, contradicting messages, and a need for closure. Conclusions During an infectious disease outbreak, our small sample of students did not see social media (like Facebook and Twitter) as suitable or reliable sources for communicating information, but primarily viewed them as a tool for communicating with friends. Wikis, however, did fill several information needs, especially when citizens are actively searching for information. For many, source credibility is an important asset of information usefulness. Finally, we provide several general recommendations for communicating with citizens during an infectious disease outbreak. PMID:23257066

The role of hydrodynamics, matrix and sampling duration in passive sampling of polar compounds with Empore SDB-RPS disks.

PubMed

Vermeirssen, Etiënne L M; Asmin, Josef; Escher, Beate I; Kwon, Jung-Hwan; Steimen, Irene; Hollender, Juliane

2008-01-01

There is an increasing need to monitor concentrations of polar organic contaminants in the aquatic environment. Integrative passive samplers can be used to assess time weighted average aqueous concentrations, provided calibration data are available and sampling rates are known. The sampling rate depends on environmental factors, such as temperature and water flow rate. Here we introduce an apparatus to investigate the sampling properties of passive samplers using river-like flow conditions and ambient environmental matrices: river water and treated sewage effluent. As a model sampler we selected Empore SDB-RPS disks in a Chemcatcher housing. The disks were exposed for 1 to 8 days at flow rates between 0.03 and 0.4 m s(-1). Samples were analysed using a bioassay for estrogenic activity and by LC-MS-MS target analysis of the pharmaceuticals sulfamethoxazole, carbamazepine and clarithromycin. In order to assess sampling rates of SDB disks, we also measured aqueous concentrations of the pharmaceuticals. Sampling rates increased with increasing flow rate and this relationship was not affected by the environmental matrix. However, SDB disks were only sampling in the integrative mode at low flow rates <0.1 m s(-1) and/or for short sampling times. The duration of linear uptake was particularly short for sulfamethoxazole (1 day) and longer for clarithromycin (5 days). At 0.03 m s(-1) and 12-14 degrees C, the sampling rate of SDB disks was 0.09 L day(-1) for clarithromycin, 0.14 L day(-1) for sulfamethoxazole and 0.25 L day(-1) for carbamazepine. The results show that under controlled conditions, SDB disks can be effectively used as passive sampling devices.

Omeprazole decreases magnesium transport across Caco-2 monolayers

PubMed Central

Thongon, Narongrit; Krishnamra, Nateetip

2011-01-01

AIM: To elucidate the effect and underlying mechanisms of omeprazole action on Mg2+ transport across the intestinal epithelium. METHODS: Caco-2 monolayers were cultured in various dose omeprazole-containing media for 14 or 21 d before being inserted into a modified Ussing chamber apparatus to investigate the bi-directional Mg2+ transport and electrical parameters. Paracellular permeability of the monolayer was also observed by the dilution potential technique and a cation permeability study. An Arrhenius plot was performed to elucidate the activation energy of passive Mg2+ transport across the Caco-2 monolayers. RESULTS: Both apical to basolateral and basolateral to apical passive Mg2+ fluxes of omeprazole-treated epithelium were decreased in a dose- and time-dependent manner. Omeprazole also decreased the paracellular cation selectivity and changed the paracellular selective permeability profile of Caco-2 epithelium to Li+, Na+, K+, Rb+, and Cs+ from series VII to series VI of the Eisenman sequence. The Arrhenius plot revealed the higher activation energy for passive Mg2+ transport in omeprazole-treated epithelium than that of control epithelium, indicating that omeprazole affected the paracellular channel of Caco-2 epithelium in such a way that Mg2+ movement was impeded. CONCLUSION: Omeprazole decreased paracellular cation permeability and increased the activation energy for passive Mg2+ transport of Caco-2 monolayers that led to the suppression of passive Mg2+ absorption. PMID:21472124

Omeprazole decreases magnesium transport across Caco-2 monolayers.

PubMed

Thongon, Narongrit; Krishnamra, Nateetip

2011-03-28

To elucidate the effect and underlying mechanisms of omeprazole action on Mg(2+) transport across the intestinal epithelium. Caco-2 monolayers were cultured in various dose omeprazole-containing media for 14 or 21 d before being inserted into a modified Ussing chamber apparatus to investigate the bi-directional Mg(2+) transport and electrical parameters. Paracellular permeability of the monolayer was also observed by the dilution potential technique and a cation permeability study. An Arrhenius plot was performed to elucidate the activation energy of passive Mg(2+) transport across the Caco-2 monolayers. Both apical to basolateral and basolateral to apical passive Mg(2+) fluxes of omeprazole-treated epithelium were decreased in a dose- and time-dependent manner. Omeprazole also decreased the paracellular cation selectivity and changed the paracellular selective permeability profile of Caco-2 epithelium to Li(+), Na(+), K(+), Rb(+), and Cs(+) from series VII to series VI of the Eisenman sequence. The Arrhenius plot revealed the higher activation energy for passive Mg(2+) transport in omeprazole-treated epithelium than that of control epithelium, indicating that omeprazole affected the paracellular channel of Caco-2 epithelium in such a way that Mg(2+) movement was impeded. Omeprazole decreased paracellular cation permeability and increased the activation energy for passive Mg(2+) transport of Caco-2 monolayers that led to the suppression of passive Mg(2+) absorption.

Guidelines for the use of the semipermeable membrane device (SPMD) and the polar organic chemical integrative sampler (POCIS) in environmental monitoring studies

USGS Publications Warehouse

Alvarez, David A.

2010-01-01

The success of an environmental monitoring study using passive samplers, or any sampling method, begins in the office or laboratory. Regardless of the specific methods used, the general steps include the formulation of a sampling plan, training of personnel, performing the field (sampling) work, processing the collected samples to recover chemicals of interest, analysis of the enriched extracts, and interpretation of the data. Each of these areas will be discussed in the following sections with emphasis on specific considerations with the use of passive samplers. Water is an extremely heterogeneous matrix both spatially and temporally (Keith, 1991). The mixing and distribution of dissolved organic chemicals in a water body are controlled by the hydrodynamics of the water, the sorption partition coefficients of the chemicals, and the amount of organic matter (suspended sediments, colloids, and dissolved organic carbon) present. In lakes and oceans, stratification because of changes in temperature, water movement, and water composition can occur resulting in dramatic changes in chemical concentrations with depth (Keith, 1991). Additional complications related to episodic events, such as surface runoff, spills, and other point source contamination, can result in isolated or short-lived pulses of contaminants in the water. The application of passive sampling technologies for the monitoring of legacy and emerging organic chemicals in the environment is becoming widely accepted worldwide. The primary use of passive sampling methods for environmental studies is in the area of surface-water monitoring; however, these techniques have been applied to air and groundwater monitoring studies. Although these samplers have no mechanical or moving parts, electrical or fuel needs which require regular monitoring, there are still considerations that need to be understood in order to have a successful study. Two of the most commonly used passive samplers for organic contaminants are the semipermeable membrane device (SPMD) and the polar organic chemical integrative sampler (POCIS). The tips given in this document focus on these two samplers but are applicable to most types of passive sampling devices. The information in this guide is heavily weighted towards the sampling of water; however, information specific to the use of SPMDs for air sampling will also be covered.

Comparison of marine sampling methods for organic contaminants: Passive samplers, water extractions, and live oyster deployment.

PubMed

Raub, Kristin B; Vlahos, Penny; Whitney, Michael

2015-08-01

Laboratory and field trials evaluated the efficacy of three methods of detecting aquatic pesticide concentrations. Currently used pesticides: atrazine, metolachlor, and diazinon and legacy pesticide dieldrin were targeted. Pesticides were extracted using solid-phase extraction (SPE) of water samples, titanium plate passive samplers coated in ethylene vinyl acetate (EVA) and eastern oysters (Crassostrea viginica) as biosamplers. A laboratory study assessed the extraction efficiencies and precision of each method. Passive samplers yielded the highest precision of the three methods (RSD: 3-14% EVA plates; 19-60% oysters; and 25-56% water samples). Equilibrium partition coefficients were derived. A significant relationship was found between the concentration in oyster tissue and the ambient aquatic concentration. In the field (Housatonic River, CT (U.S.)) water sampling (n = 5) detected atrazine at 1.61-7.31 μg L(-1), oyster sampling (n = 2×15) detected dieldrin at n.d.-0.096 μg L(-1) SW and the passive samplers (n = 5×3) detected atrazine at 0.97-3.78 μg L(-1) SW and dieldrin at n.d.-0.68 μg L(-1) SW. Copyright © 2015 Elsevier Ltd. All rights reserved.

In situ passive sampling of sediments in the Lower Duwamish Waterway Superfund site: Replicability, comparison with ex situ measurements, and use of data.

PubMed

Apell, Jennifer N; Gschwend, Philip M

2016-11-01

Superfund sites with sediments contaminated by hydrophobic organic compounds (HOCs) can be difficult to characterize because of the complex nature of sorption to sediments. Porewater concentrations, which are often used to model transport of HOCs from the sediment bed into overlying water, benthic organisms, and the larger food web, are traditionally estimated using sediment concentrations and sorption coefficients estimated using equilibrium partitioning (EqP) theory. However, researchers have begun using polymeric samplers to determine porewater concentrations since this method does not require knowledge of the sediment's sorption properties. In this work, polyethylene passive samplers were deployed into sediments in the field (in situ passive sampling) and mixed with sediments in the laboratory (ex situ active sampling) that were contaminated with polychlorinated biphenyls (PCBs). The results show that porewater concentrations based on in situ and ex situ sampling generally agreed within a factor of two, but in situ concentrations were consistently lower than ex situ porewater concentrations. Imprecision arising from in situ passive sampling procedures does not explain this bias suggesting that field processes like bioirrigation may cause the differences observed between in situ and ex situ polymeric samplers. Copyright © 2016 Elsevier Ltd. All rights reserved.

HOLISTIC APPROACH FOR ASSESSING THE PRESENCE ...

EPA Pesticide Factsheets

As an integral part of our continuing research in environmental quality assessment approaches, we have developed a variety of passive integrative sampling devices widely applicable for use in defining the presence and potential impacts of a broad array of contaminants. The semipermeable membrane device (SPMD) has gained widespread use for sampling hydrophobic chemicals from water and air, the polar organic chemical integrative sampler (POCIS) is applicable for sequestering waterborne hydrophilic organic chemicals, the stabilized liquid membrane device (SLMD) is used to integratively sample waterborne ionic metals, and the passive integrative mercury sampler (PIMS) is applicable for sampling vapor phase or dissolved neutral mercury species. This suite of integrative samplers forms the basis for a new passive sampling approach for assessing the presence and potential toxicological significance of a broad spectrum of environmental contaminants. In a proof-of-concept study, three of our four passive integrative samplers were used to assess the presence o,f a wide variety of contaminants in , the waters of a constructed wetland, and to determine the effectiveness of the constructed wetland in removing contaminants. The wetland is used for fmal polishing of secondary- treatment municipal wastewater and the effluent is used as a source of water for a state wildlife area. Numerous contaminants, including organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons

Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

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

Cary, Robert E.

2015-12-08

Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

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

Cary, Robert B.

Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

Development of a silicone-membrane passive sampler for monitoring cylindrospermopsin and microcystin LR-YR-RR in natural waters

NASA Astrophysics Data System (ADS)

Nyoni, Hlengilizwe; Mamba, Bhekie B.; Msagati, Titus A. M.

2017-08-01

Silicone membrane tubes were functionalised by filling them with synthesised γ-Fe2O3 nanoparticles and used as a passive sampling device for monitoring microcystins and cylindrospermopsin in aquatic environments. This novel device was calibrated for the measurement of microcystin and cylindrospermopsin concentrations in water. The effect of temperature and hydrodynamics on the sampler performance was studied in a flow-through system under controlled conditions. The chemical uptake of microcystins (MCs) and cylindrospermopsin (CYN) into the passive sampler remained linear and integrative throughout the exposure period. The rate of accumulation of most of the MC compounds tested was dependent on temperature and flow velocity. The use of 13C labelled polychlorinated biphenyls as performance reference compounds (PRCs) in silicone membrane/γ-Fe2O3 nanoparticle passive sampler, Chemcatcher and polar organic chemical integrative sampler (POCIS) was evaluated. The majority of PRCs improved the semi quantitative nature of water concentration estimated by the three samplers. The corrected sampling rate values of model biotoxin compounds were used to estimate the time-weighted average concentrations in natural cyanobacterial water blooms of the Hartbeespoort dam. The corrected sampling rates RScorr values varied from 0.1140 to 0.5628 Ld-1 between samplers with silicone membrane having the least RScorr values compared to the Chemcatcher and POCIS. The three passive sampling devises provided a more relevant picture of the biotoxin concentration in the Hartbeespoort dam. The results suggested that the three sampling devices are suitable for use in monitoring microcystins and cylindrospermopsin concentrations in aquatic environments.

A fast passive and planar liquid sample micromixer.

PubMed

Melin, Jessica; Gimenéz, Guillem; Roxhed, Niclas; van der Wijngaart, Wouter; Stemme, Göran

2004-06-01

A novel microdevice for passively mixing liquid samples based on surface tension and a geometrical mixing chamber is presented. Due to the laminar flow regime on the microscale, mixing becomes difficult if not impossible. We present a micromixer where a constantly changing time dependent flow pattern inside a two sample liquid plug is created as the plug simply passes through the planar mixer chamber. The device requires no actuation during mixing and is fabricated using a single etch process. The effective mixing of two coloured liquid samples is demonstrated.

Passive injection control for microfluidic systems

DOEpatents

Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

2004-12-21

Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

Hydrodebridement of wounds: effectiveness in reducing wound bacterial contamination and potential for air bacterial contamination.

PubMed

Bowling, Frank L; Stickings, Daryl S; Edwards-Jones, Valerie; Armstrong, David G; Boulton, Andrew Jm

2009-05-08

The purpose of this study was to assess the level of air contamination with bacteria after surgical hydrodebridement and to determine the effectiveness of hydro surgery on bacterial reduction of a simulated infected wound. Four porcine samples were scored then infected with a broth culture containing a variety of organisms and incubated at 37 degrees C for 24 hours. The infected samples were then debrided with the hydro surgery tool (Versajet, Smith and Nephew, Largo, Florida, USA). Samples were taken for microbiology, histology and scanning electron microscopy pre-infection, post infection and post debridement. Air bacterial contamination was evaluated before, during and after debridement by using active and passive methods; for active sampling the SAS-Super 90 air sampler was used, for passive sampling settle plates were located at set distances around the clinic room. There was no statistically significant reduction in bacterial contamination of the porcine samples post hydrodebridement. Analysis of the passive sampling showed a significant (p < 0.001) increase in microbial counts post hydrodebridement. Levels ranging from 950 colony forming units per meter cubed (CFUs/m3) to 16780 CFUs/m3 were observed with active sampling of the air whilst using hydro surgery equipment compared with a basal count of 582 CFUs/m3. During removal of the wound dressing, a significant increase was observed relative to basal counts (p < 0.05). Microbial load of the air samples was still significantly raised 1 hour post-therapy. The results suggest a significant increase in bacterial air contamination both by active sampling and passive sampling. We believe that action might be taken to mitigate fallout in the settings in which this technique is used.

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

PubMed

Yu, Shang-yun; Zhou, Yan-mei

2015-08-01

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

Faraday Shields within a Solenoidal Coil to Reduce Sample Heating: Numerical Comparison of Designs and Experimental Verification

PubMed Central

Park, BuSik; Neuberger, Thomas; Webb, Andrew G.; Bigler, Don C.; Collins, Christopher M.

2009-01-01

A comparison of methods to decrease RF power dissipation and related heating in conductive samples using passive conductors surrounding a sample in a solenoid coil is presented. Full-Maxwell finite difference time domain numerical calculations were performed to evaluate the effect of the passive conductors by calculating conservative and magnetically-induced electric field and magnetic field distributions. To validate the simulation method, experimental measurements of temperature increase were conducted using a solenoidal coil (diameter 3 mm), a saline sample (10 mM NaCl) and passive copper shielding wires (50 μm diameter). The temperature increase was 58% lower with the copper wires present for several different input powers to the coil. This was in good agreement with simulation for the same geometry, which indicated 57% lower power dissipated in the sample with conductors present. Simulations indicate that some designs should be capable of reducing temperature increase by more than 85%. PMID:19879784

An economic passive sampling method to detect particulate pollutants using magnetic measurements.

PubMed

Cao, Liwan; Appel, Erwin; Hu, Shouyun; Ma, Mingming

2015-10-01

Identifying particulate matter (PM) emitted from industrial processes into the atmosphere is an important issue in environmental research. This paper presents a passive sampling method using simple artificial samplers that maintains the advantage of bio-monitoring, but overcomes some of its disadvantages. The samplers were tested in a heavily polluted area (Linfen, China) and compared to results from leaf samples. Spatial variations of magnetic susceptibility from artificial passive samplers and leaf samples show very similar patterns. Scanning electron microscopy suggests that the collected PM are mostly in the range of 2-25 μm; frequent occurrence of spherical shape indicates industrial combustion dominates PM emission. Magnetic properties around power plants show different features than other plants. This sampling method provides a suitable and economic tool for semi-quantifying temporal and spatial distribution of air quality; they can be installed in a regular grid and calibrate the weight of PM. Copyright © 2015 Elsevier Ltd. All rights reserved.

KSC-2015-1221

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Col. Marc Del Rosario, commander of the 30th Space Wing Operations Group, addresses the audience of a NASA Social held for NASA's Soil Moisture Active Passive mission, or SMAP, at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

KSC-2015-1217

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Wendy Edelstein, instrument manager for NASA's Soil Moisture Active Passive mission, or SMAP, discusses the science and engineering of the mission with the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

KSC-2015-1205

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Jared Entin, program scientist for NASA's Soil Moisture Active Passive mission, or SMAP, discusses the science and engineering of the mission with the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

KSC-2015-1204

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Jared Entin, program scientist for NASA's Soil Moisture Active Passive mission, or SMAP, discusses the science and engineering of the mission with the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

"Sleeping Beauty Gets a Makeover": Using the Retelling of Fairytales to Create an Awareness of Hegemonic Norms and the Social Construction of Value

ERIC Educational Resources Information Center

Brule, Nancy J.

2008-01-01

Media use gender imagery to define "the cultural representations of gender and embodiment of gender in symbolic language and artistic productions that reproduce and legitimate gender statuses." The heroines and heroes in fairytales present images of women being young, beautiful, passive, and helpless while men are portrayed as strong, powerful,…

The effects of risk-glorifying media exposure on risk-positive cognitions, emotions, and behaviors: a meta-analytic review.

PubMed

Fischer, Peter; Greitemeyer, Tobias; Kastenmüller, Andreas; Vogrincic, Claudia; Sauer, Anne

2011-05-01

In recent years, there has been a surge in the quantity of media content that glorifies risk-taking behavior, such as risky driving, extreme sports, or binge drinking. The authors conducted a meta-analysis involving more than 80,000 participants and 105 independent effect sizes to examine whether exposure to such media depictions increased their recipients' risk-taking inclinations. A positive connection was found for overall, combined risk taking (g=.41); as well as its underlying dimensions: risk-taking behaviors (g=.41), risk-positive cognitions and attitudes (g=.35), and risk-positive emotions (g=.56). This effect was observed across varying research methods (experimental, correlational, longitudinal); types of media (video games, movies, advertising, TV, music); and differing risk-related outcome measures (e.g., smoking, drinking, risky driving, sexual behavior). Multiple moderator analyses revealed 2 theoretically new boundary conditions for sociocognitive models. First, the effect was stronger for active (i.e., video games) than for passive (e.g., film, music) exposure to risk-glorifying media content. Second, the effect was stronger when there was a high degree of contextual fit between the media content and type of risk-taking measure. The theoretical, practical, and societal implications of the present research synthesis are discussed. © 2011 American Psychological Association

Experimental analysis of the flow near the boundary of random porous media

NASA Astrophysics Data System (ADS)

Wu, Zhenxing; Mirbod, Parisa

2018-04-01

The aim of this work is to experimentally examine flow over and near random porous media. Different porous materials were chosen to achieve porosity ranging from 0.95 to 0.99. In this study, we report the detailed velocity measurements of the flow over and near random porous material inside a rectangular duct using a planar particle image velocimetry (PIV) technique. By controlling the flow rate, two different Reynolds numbers were achieved. We determined the slip velocity at the interface between the porous media and free flow. Values of the slip velocity normalized either by the maximum flow velocity or by the shear rate at the interface and the screening distance K1/2 were found to depend on porosity. It was also shown that the depth of penetration inside the porous material was larger than the screening length using Brinkman's prediction. Moreover, we examined a model for the laminar coupled flow over and inside porous media and analyzed the permeability of a random porous medium. This study provided detailed analysis of flow over and at the interface of various specific random porous media using the PIV technique. This analysis has the potential to serve as a first step toward using random porous media as a new passive technique to control the flow over smooth surfaces.

Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae.

PubMed

Murrah, Kyle A; Pang, Bing; Richardson, Stephen; Perez, Antonia; Reimche, Jennifer; King, Lauren; Wren, John; Swords, W Edward

2015-07-01

Streptococcus pneumoniae strains lacking capsular polysaccharide have been increasingly reported in carriage and disease contexts. Since most cases of otitis media involve more than one bacterial species, we aimed to determine the capacity of a nonencapsulated S. pneumoniae clinical isolate to induce disease in the context of a single-species infection and as a polymicrobial infection with nontypeable Haemophilus influenzae. Using the chinchilla model of otitis media, we found that nonencapsulated S. pneumoniae colonizes the nasopharynx following intranasal inoculation, but does not readily ascend into the middle ear. However, when we inoculated nonencapsulated S. pneumoniae directly into the middle ear, the bacteria persisted for two weeks post-inoculation and induced symptoms consistent with chronic otitis media. During coinfection with nontypeable H. influenzae, both species persisted for one week and induced polymicrobial otitis media. We also observed that nontypeable H. influenzae conferred passive protection from killing by amoxicillin upon S. pneumoniae from within polymicrobial biofilms in vitro. Therefore, based on these results, we conclude that nonencapsulated pneumococci are a potential causative agent of chronic/recurrent otitis media, and can also cause mutualistic infection with other opportunists, which could complicate treatment outcomes. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Presence of active pharmaceutical ingredients in the continuum of surface and ground water used in drinking water production.

PubMed

Ahkola, Heidi; Tuominen, Sirkku; Karlsson, Sanja; Perkola, Noora; Huttula, Timo; Saraperä, Sami; Artimo, Aki; Korpiharju, Taina; Äystö, Lauri; Fjäder, Päivi; Assmuth, Timo; Rosendahl, Kirsi; Nysten, Taina

2017-12-01

Anthropogenic chemicals in surface water and groundwater cause concern especially when the water is used in drinking water production. Due to their continuous release or spill-over at waste water treatment plants, active pharmaceutical ingredients (APIs) are constantly present in aquatic environment and despite their low concentrations, APIs can still cause effects on the organisms. In the present study, Chemcatcher passive sampling was applied in surface water, surface water intake site, and groundwater observation wells to estimate whether the selected APIs are able to end up in drinking water supply through an artificial groundwater recharge system. The API concentrations measured in conventional wastewater, surface water, and groundwater grab samples were assessed with the results obtained with passive samplers. Out of the 25 APIs studied with passive sampling, four were observed in groundwater and 21 in surface water. This suggests that many anthropogenic APIs released to waste water proceed downstream and can be detectable in groundwater recharge. Chemcatcher passive samplers have previously been used in monitoring several harmful chemicals in surface and wastewaters, but the path of chemicals to groundwater has not been studied. This study provides novel information on the suitability of the Chemcatcher passive samplers for detecting APIs in groundwater wells.

Polyurethane foam (PUF) passive samplers for monitoring phenanthrene in stormwater.

PubMed

Dou, Yueqin; Zhang, Tian C; Zeng, Jing; Stansbury, John; Moussavi, Massoum; Richter-Egger, Dana L; Klein, Mitchell R

2016-04-01

Pollution from highway stormwater runoff has been an increasing area of concern. Many structural Best Management Practices (BMPs) have been implemented for stormwater treatment and management. One challenge for these BMPs is to sample stormwater and monitor BMP performance. The main objective of this study was to evaluate the feasibility of using polyurethane foam (PUF) passive samplers (PSs) for sampling phenanthrene (PHE) in highway stormwater runoff and BMPs. Tests were conducted using batch reactors, glass-tube columns, and laboratory-scale BMPs (bioretention cells). Results indicate that sorption for PHE by PUF is mainly linearly relative to time, and the high sorption capacity allows the PUF passive sampler to monitor stormwater events for months or years. The PUF passive samplers could be embedded in BMPs for monitoring influent and effluent PHE concentrations. Models developed to link the results of batch and column tests proved to be useful for determining removal or sorption parameters and performance of the PUF-PSs. The predicted removal efficiencies of BMPs were close to the real values obtained from the control columns with errors ranging between -8.46 and 1.52%. This research showed that it is possible to use PUF passive samplers for sampling stormwater and monitoring the performance of stormwater BMPs, which warrants the field-scale feasibility studies in the future.

The Role of Personal Attributes and Social Support Factors on Passive Behaviour in Classroom among Secondary School Students: A Prospective Study

ERIC Educational Resources Information Center

Murberg, Terje A.

2010-01-01

The present study prospectively explored the effects of personal attributes (self-esteem and introversion) and social support factors on passive behaviour in the classroom in a sample of 259 (132 females, 127 males) students in two secondary schools. In the longitudinal multivariate analysis, the student's perceived passive behaviour in the…

Small passive student experiments on G324 261 individual quests for student knowledge

NASA Technical Reports Server (NTRS)

Nicholson, James H.; Tempel, Carol A.; Ashcraft, Ruth; Rutherford, Robin

1995-01-01

The Charleston County School District CAN DO Project payload on STS-57 had a primary goal of photographing the Earth with the GeoCam camera system. In addition, the payload carried 261 passive student experiments representing the efforts of several thousand students throughout the district and in four other states. These experiments represented the individual concepts of teams ranging in age from pre-school to high school. Consequently, a tremendous variety of samples from collard green seeds to microscopic 'water bears' were flown. Each prospective team was provided a simple kit equipped with five vials. Each student team submitted five coded samples, one for space flight and four control samples. The control samples were exposed to radiation, cold and centrifugation respectively while one negative control sample was passively stored. The students received the samples back still coded so that they were unaware of which samples were flown. They then investigated their samples according to their individual research protocols. The results were presented in poster and platform form at a student research symposium. Space Trees grown from tree seeds flown in the payload have been planted at all district schools, and at many guest schools. These seeds represented another way in which to involve additional classes and students. Both the passive experiments and the space trees were housed in what otherwise would have been wasted space within the payload. They extended the GAS programs worthwhile ballast concept to another level. The opportunity to fly an experiment in space is too previous not to be extended to the greatest number of students possible.

Performances and application of a passive sampling method for the simultaneous determination of nitrogen dioxide and sulfur dioxide in ambient air.

PubMed

Plaisance, H; Sagnier, I; Saison, J Y; Galloo, J C; Guillermo, R

2002-11-01

The performances and applicability of a diffusion tube sampler for the simultaneous measurements of NO2 and SO2 in ambient air were evaluated. SO2 and NO2 are collected by the passive sampler using triethanolamine as trapping agent and are determined as sulphate and nitrite with ion chromatography. The detection limit (2.3 microg m(-3) of NO2 and 4.2 microg m(-3) of SO2 for two weeks sampling) is adequate for the determination of concentrations in urban and industrial areas. Precision of the method as RSD is in mean 5% for NO2 and 12% for SO2 at the concentration levels in urban areas. Calibration of the method was performed in the field conditions by comparison between the responses of sampler and the concentrations measured by the continuous monitors. High degree of linearity (correlation coefficients > 0.8) is found between the passive sampler tube and the continuous monitor data for both NO2 and SO2. To reduce the wind velocity influence on passive sampling of diffusion tubes, a protective shelter was tested in this study. The overall uncertainty of one measure for the optimised method is estimated at 5 microg m(-3) for NO2 and 6 microg m(-3) for SO2. Suitability of this passive sampling method for air pollution monitoring in urban areas was demonstrated by the results shown in this paper on a campaign carried out in the French agglomeration.

Network Plus

NASA Astrophysics Data System (ADS)

Bender, Walter; Chesnais, Pascal

1988-05-01

Over the past several years, the Electronic Publishing Group at the MIT Media Laboratory has been conducting a family of media experiments which explore a new kind of broadcast: the distribution of data and computer programs rather than pre-packaged material. This broadcast is not directed to a human recipient, but to a local computational agent acting on his behalf. In response to instructions from both the broadcaster and the reader, this agent selects from the incoming data and presents it in a manner suggestive of traditional media. The embodiment of these media experiments is a news retrieval system where the news editor has been replaced by the personal computer. A variety of both local and remote databases which operate passively as well as interac-tively are accessed by "reporters." These "reporters" are actually software interfaces, which are programmed to gather news. Ideally, they are "broadcatching" that is to say, watching all broadcast television channels, listening to all radio transmissions, and reading all newspapers, magazines, and journals. 1 A possible consequence of the synthesis of media through active processing is the merger of newspapers and television (figure 1). The result is either a newspaper with illustrations which move 2 or, conversely, print as television output. The latter is the theme of Network Plus.

Achieving Accuracy Requirements for Forest Biomass Mapping: A Data Fusion Method for Estimating Forest Biomass and LiDAR Sampling Error with Spaceborne Data

NASA Technical Reports Server (NTRS)

Montesano, P. M.; Cook, B. D.; Sun, G.; Simard, M.; Zhang, Z.; Nelson, R. F.; Ranson, K. J.; Lutchke, S.; Blair, J. B.

2012-01-01

The synergistic use of active and passive remote sensing (i.e., data fusion) demonstrates the ability of spaceborne light detection and ranging (LiDAR), synthetic aperture radar (SAR) and multispectral imagery for achieving the accuracy requirements of a global forest biomass mapping mission. This data fusion approach also provides a means to extend 3D information from discrete spaceborne LiDAR measurements of forest structure across scales much larger than that of the LiDAR footprint. For estimating biomass, these measurements mix a number of errors including those associated with LiDAR footprint sampling over regional - global extents. A general framework for mapping above ground live forest biomass (AGB) with a data fusion approach is presented and verified using data from NASA field campaigns near Howland, ME, USA, to assess AGB and LiDAR sampling errors across a regionally representative landscape. We combined SAR and Landsat-derived optical (passive optical) image data to identify forest patches, and used image and simulated spaceborne LiDAR data to compute AGB and estimate LiDAR sampling error for forest patches and 100m, 250m, 500m, and 1km grid cells. Forest patches were delineated with Landsat-derived data and airborne SAR imagery, and simulated spaceborne LiDAR (SSL) data were derived from orbit and cloud cover simulations and airborne data from NASA's Laser Vegetation Imaging Sensor (L VIS). At both the patch and grid scales, we evaluated differences in AGB estimation and sampling error from the combined use of LiDAR with both SAR and passive optical and with either SAR or passive optical alone. This data fusion approach demonstrates that incorporating forest patches into the AGB mapping framework can provide sub-grid forest information for coarser grid-level AGB reporting, and that combining simulated spaceborne LiDAR with SAR and passive optical data are most useful for estimating AGB when measurements from LiDAR are limited because they minimized forest AGB sampling errors by 15 - 38%. Furthermore, spaceborne global scale accuracy requirements were achieved. At least 80% of the grid cells at 100m, 250m, 500m, and 1km grid levels met AGB density accuracy requirements using a combination of passive optical and SAR along with machine learning methods to predict vegetation structure metrics for forested areas without LiDAR samples. Finally, using either passive optical or SAR, accuracy requirements were met at the 500m and 250m grid level, respectively.

Two-dimensional numerical simulation of boron diffusion for pyramidally textured silicon

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

Ma, Fa-Jun, E-mail: Fajun.Ma@nus.edu.sg; Duttagupta, Shubham; Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576

2014-11-14

Multidimensional numerical simulation of boron diffusion is of great relevance for the improvement of industrial n-type crystalline silicon wafer solar cells. However, surface passivation of boron diffused area is typically studied in one dimension on planar lifetime samples. This approach neglects the effects of the solar cell pyramidal texture on the boron doping process and resulting doping profile. In this work, we present a theoretical study using a two-dimensional surface morphology for pyramidally textured samples. The boron diffusivity and segregation coefficient between oxide and silicon in simulation are determined by reproducing measured one-dimensional boron depth profiles prepared using different boronmore » diffusion recipes on planar samples. The established parameters are subsequently used to simulate the boron diffusion process on textured samples. The simulated junction depth is found to agree quantitatively well with electron beam induced current measurements. Finally, chemical passivation on planar and textured samples is compared in device simulation. Particularly, a two-dimensional approach is adopted for textured samples to evaluate chemical passivation. The intrinsic emitter saturation current density, which is only related to Auger and radiative recombination, is also simulated for both planar and textured samples. The differences between planar and textured samples are discussed.« less

Passive Range of Motion in a Population-Based Sample of Children with Spastic Cerebral Palsy Who Walk

ERIC Educational Resources Information Center

McDowell, Brona C.; Salazar-Torres, Jose J.; Kerr, Claire; Cosgrove, Aidan P.

2012-01-01

-While passive range of motion (PROM) is commonly used to inform decisions on therapeutic management, knowledge of PROM of children with spastic cerebral palsy (CP) is limited. A population-based sample of 178 children with spastic CP (110 male; unilateral, n = 94; bilateral, n = 84; age range 4-17 years) and 68 typically developing children (24…

Laboratory Sampling Guide

DTIC Science & Technology

2012-05-11

their uses: Table 10. Types of Solid Sorbent Tubes Tube Type Typical Uses Anasorb® 747 Methyl Ethyl Ketone , Ethylene Oxide Charcoal Tube...Silica Gel Aliphatic Amines, Methanol, Aldehydes , Acid Mist 2.5.3 Passive Samplers. Passive samplers do not require a sampling pump (Figure 9). They...often encountered within the first 6 inches of soil. Water-soluble contaminants such as metals, acids, ketones , and alcohols will be encountered at

Impact of Moisture Content and Grain Size on Hydrocarbon Diffusion in Porous Media

NASA Astrophysics Data System (ADS)

McLain, A. A.; Ho, C. K.

2001-12-01

Diffusion of hydrocarbon vapors in porous media can play an important role in our ability to characterize subsurface contaminants such as trichloroethylene (TCE). For example, traditional monitoring methods often rely on direct sampling of contaminated soils or vapor. These samples may be influenced by the diffusion of vapors away from the contaminant source term, such as non-aqueous-phase TCE liquid. In addition, diffusion of hydrocarbon vapors can also impact the migration and dispersion of the contaminant in the subsurface. Therefore, understanding the diffusion rates and vapor transport processes of hydrocarbons in variably-saturated, heterogeneous porous media will assist in the characterization and detection of these subsurface contaminants. The purpose of this study was to investigate the impact of soil heterogeneity and water-moisture content on the diffusion processes for TCE. A one-dimensional column experiment was used to monitor the rates of vapor diffusion through sand. Experiments were performed with different average water-moisture contents and different grain sizes. On one end of the column, a reservoir cap is used to encase the TCE, providing a constant vapor boundary condition while sealing the end. The other end of the column contains a novel microchemical sensor. The sensor employs a polymer-absorption resistor (chemiresistor) that reversibly swells and increases in resistance when exposed to hydrocarbons. Once calibrated, the chemiresistors can be used to passively monitor vapor concentrations. This unique method allows the detection of in-situ vapor concentrations without disturbing the local environment. Results are presented in the form of vapor-concentration breakthrough curves as detected by the sensor. The shape of the breakthrough curve is dependent on several key parameters, including the length of the column and parameters (e.g., water-moisture content and grain-size) that affect the effective diffusion coefficient of TCE in air. Comparisons are made between theoretical and observed breakthrough curves to evaluate the diffusion of TCE and other relevant physical processes (e.g., air-water partitioning of TCE). The relative impact of water-moisture content and grain size on the diffusion of TCE vapor in porous media is also addressed. The authors thank Bob Hughes, who developed the chemiresistor sensors, and Chad Davis, who assisted with the calibrations. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

An in vitro evaluation of passive ultrasonic agitation of different irrigants on smear layer removal after post space preparation: a scanning electron microscopic study.

PubMed

Srirekha, A; Rashmi, K; Hegde, Jayshree; Lekha, S; Rupali, K; Reshmi, George

2013-09-01

This study evaluated the removal of debris and smear layer after post space preparation using different irrigations and passive ultrasonic agitation. Sixty human premolars were decoronated and post space prepared after endodontic therapy. The samples were then randomly divided into three experimental groups (Groups A, B, C) and one control group (Group D) with fifteen samples in each group. Groups A and B samples were treated with 10 % citric acid and 17 % ethylenediamintetraacetic acid (EDTA), respectively and passive ultrasonic agitation was done, rinsed with sodium hypochlorite and finally flushed with saline. Group C samples were conditioned with 36 % phosphoric acid and then rinsed with saline. The control group was treated with 3 % sodium hypochlorite, passive ultrasonic agitation done and flushed with saline. The samples were sectioned and evaluated for debris and smear layer removal under scanning electron microscope. 10 % citric acid showed the best removal of smear layer when compared with 17 % EDTA and 36 % phosphoric acid, but was not statistically significant (p > 0.05). The difference in scoring for debris and smear layer removal in the coronal, middle and apical third of post space of experimental groups in comparison with control group was statistically significant (p < 0.001).

The value of fame: preadolescent perceptions of popular media and their relationship to future aspirations.

PubMed

Uhls, Yalda T; Greenfield, Patricia M

2012-03-01

In line with Greenfield's (2009) theory of social change and human development, current popular preadolescent TV shows suggest that fame, an individualistic goal, is an important and achievable aspiration (Uhls & Greenfield, 2011). Such messages may be particularly salient for preadolescents, ages 10-12. This study used focus groups and mixed analytic methods (qualitative and quantitative) to examine how popular media, passive and interactive, are interpreted by preadolescents and how their interpretations relate to their media practices and future goals. Quantitative analysis revealed that fame was the number one value, selected as the most important value for participants' future goals significantly more frequently than expected by chance. Qualitative analysis of focus group discourse suggested that (a) youth absorb messages in their media environment regarding fame as a future goal and (b) their interpretations of these messages highlight the importance and value of public recognition. Enacting the value of fame, the majority of preadolescent participants use online video sharing sites (e.g., YouTube) to seek an audience beyond their immediate community. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Passive Sampling for Indoor and Outdoor Exposures to Chlorpyrifos, Azinphos-Methyl, and Oxygen Analogs in a Rural Agricultural Community

PubMed Central

Gibbs, Jenna L.; Yost, Michael G.; Negrete, Maria; Fenske, Richard A.

2016-01-01

Background: Recent studies have highlighted the increased potency of oxygen analogs of organophosphorus pesticides. These pesticides and oxygen analogs have previously been identified in the atmosphere following spray applications in the states of California and Washington. Objectives: We used two passive sampling methods to measure levels of the ollowing organophosphorus pesticides: chlorpyrifos, azinphos-methyl, and their oxygen analogs at 14 farmworker and 9 non-farmworker households in an agricultural region of central Washington State in 2011. Methods: The passive methods included polyurethane foam passive air samplers deployed outdoors and indoors and polypropylene deposition plates deployed indoors. We collected cumulative monthly samples during the pesticide application seasons and during the winter season as a control. Results: Monthly outdoor air concentrations ranged from 9.2 to 199 ng/m3 for chlorpyrifos, 0.03 to 20 ng/m3 for chlorpyrifos-oxon, < LOD (limit of detection) to 7.3 ng/m3 for azinphos-methyl, and < LOD to 0.8 ng/m3 for azinphos-methyl-oxon. Samples from proximal households (≤ 250 m) had significantly higher outdoor air concentrations of chlorpyrifos, chlorpyrifos-oxon, and azinphos-methyl than did samples from nonproximal households (p ≤ 0.02). Overall, indoor air concentrations were lower than outdoors. For example, all outdoor air samples for chlorpyrifos and 97% of samples for azinphos-methyl were > LOD. Indoors, only 78% of air samples for chlorpyrifos and 35% of samples for azinphos-methyl were > LOD. Samples from farmworker households had higher indoor air concentrations of both pesticides than did samples from non-farmworker households. Mean indoor and outdoor air concentration ratios for chlorpyrifos and azinphos-methyl were 0.17 and 0.44, respectively. Conclusions: We identified higher levels in air and on surfaces at both proximal and farmworker households. Our findings further confirm the presence of pesticides and their oxygen analogs in air and highlight their potential for infiltration of indoor living environments. Citation: Gibbs JL, Yost MG, Negrete M, Fenske RA. 2017. Passive sampling for indoor and outdoor exposures to chlorpyrifos, azinphos-methyl, and oxygen analogs in a rural agricultural community. Environ Health Perspect 125:333–341; http://dx.doi.org/10.1289/EHP425 PMID:27517732

Contamination of indoor dust and air by polychlorinated biphenyls and brominated flame retardants and relevance of non-dietary exposure in Vietnamese informal e-waste recycling sites.

PubMed

Tue, Nguyen Minh; Takahashi, Shin; Suzuki, Go; Isobe, Tomohiko; Viet, Pham Hung; Kobara, Yuso; Seike, Nobuyasu; Zhang, Gan; Sudaryanto, Agus; Tanabe, Shinsuke

2013-01-01

This study investigated the occurrence of polychlorinated biphenyls (PCBs), and several additive brominated flame retardants (BFRs) in indoor dust and air from two Vietnamese informal e-waste recycling sites (EWRSs) and an urban site in order to assess the relevance of these media for human exposure. The levels of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenyl ethane (DBDPE) in settled house dust from the EWRSs (130-12,000, 5.4-400, 5.2-620 and 31-1400 ng g(-1), respectively) were significantly higher than in urban house dust but the levels of PCBs (4.8-320 ng g(-1)) were not higher. The levels of PCBs and PBDEs in air at e-waste recycling houses (1000-1800 and 620-720 pg m(-3), respectively), determined using passive sampling, were also higher compared with non-e-waste houses. The composition of BFRs in EWRS samples suggests the influence from high-temperature processes and occurrence of waste materials containing older BFR formulations. Results of daily intake estimation for e-waste recycling workers are in good agreement with the accumulation patterns previously observed in human milk and indicate that dust ingestion contributes a large portion of the PBDE intake (60%-88%), and air inhalation to the low-chlorinated PCB intake (>80% for triCBs) due to their high levels in dust and air, respectively. Further investigation of both indoor dust and air as the exposure media for other e-waste recycling-related contaminants and assessment of health risk associated with exposure to these contaminant mixtures is necessary. Copyright © 2012 Elsevier Ltd. All rights reserved.

Passive cavitation imaging with ultrasound arrays

PubMed Central

Salgaonkar, Vasant A.; Datta, Saurabh; Holland, Christy K.; Mast, T. Douglas

2009-01-01

A method is presented for passive imaging of cavitational acoustic emissions using an ultrasound array, with potential application in real-time monitoring of ultrasound ablation. To create such images, microbubble emissions were passively sensed by an imaging array and dynamically focused at multiple depths. In this paper, an analytic expression for a passive image is obtained by solving the Rayleigh–Sommerfield integral, under the Fresnel approximation, and passive images were simulated. A 192-element array was used to create passive images, in real time, from 520-kHz ultrasound scattered by a 1-mm steel wire. Azimuthal positions of this target were accurately estimated from the passive images. Next, stable and inertial cavitation was passively imaged in saline solution sonicated at 520 kHz. Bubble clusters formed in the saline samples were consistently located on both passive images and B-scans. Passive images were also created using broadband emissions from bovine liver sonicated at 2.2 MHz. Agreement was found between the images and source beam shape, indicating an ability to map therapeutic ultrasound beams in situ. The relation between these broadband emissions, sonication amplitude, and exposure conditions are discussed. PMID:20000921

Passive cavitation imaging with ultrasound arrays.

PubMed

Salgaonkar, Vasant A; Datta, Saurabh; Holland, Christy K; Mast, T Douglas

2009-12-01

A method is presented for passive imaging of cavitational acoustic emissions using an ultrasound array, with potential application in real-time monitoring of ultrasound ablation. To create such images, microbubble emissions were passively sensed by an imaging array and dynamically focused at multiple depths. In this paper, an analytic expression for a passive image is obtained by solving the Rayleigh-Sommerfield integral, under the Fresnel approximation, and passive images were simulated. A 192-element array was used to create passive images, in real time, from 520-kHz ultrasound scattered by a 1-mm steel wire. Azimuthal positions of this target were accurately estimated from the passive images. Next, stable and inertial cavitation was passively imaged in saline solution sonicated at 520 kHz. Bubble clusters formed in the saline samples were consistently located on both passive images and B-scans. Passive images were also created using broadband emissions from bovine liver sonicated at 2.2 MHz. Agreement was found between the images and source beam shape, indicating an ability to map therapeutic ultrasound beams in situ. The relation between these broadband emissions, sonication amplitude, and exposure conditions are discussed.

Light Propagation in Turbulent Media

NASA Astrophysics Data System (ADS)

Perez, Dario G.

2003-07-01

First, we make a revision of the up-to-date Passive Scalar Fields properties: also, the refractive index is among them. Afterwards, we formulated the properties that make the family of `isotropic' fractional Brownian motion (with parameter H) a good candidate to simulate the turbulent refractive index. Moreover, we obtained its fractal dimension which matches the estimated by Constantin for passive scalar, and thus the parameter H determines the state of the turbulence. Next, using a path integral velocity representation, with the Markovian model, to calculate the effects of the turbulence over a system of grids. Finally, with the tools of Stochastic Calculus for fractional Brownian motions we studied the ray-equation coming from the Geometric Optics in the turbulent case. Our analysis covers those cases where average temperature gradients are relevant.

Effects of annealing and conformal alumina passivation on anisotropy and hysteresis of magneto-optical properties of cobalt slanted columnar thin films

NASA Astrophysics Data System (ADS)

Briley, Chad; Mock, Alyssa; Korlacki, Rafał; Hofmann, Tino; Schubert, Eva; Schubert, Mathias

2017-11-01

We present magneto-optical dielectric tensor data of cobalt and cobalt oxide slanted columnar thin films obtained by vector magneto-optical generalized ellipsometry. Room-temperature hysteresis magnetization measurements were performed in longitudinal and polar Kerr geometries on samples prior to and after a heat treatment process with and without a conformal Al2O3 passivation coating. The samples have been characterized by generalized ellipsometry, scanning electron microscopy, and Raman spectroscopy in conjuncture with density functional theory. We observe strongly anisotropic hysteresis behaviors, which depend on the nanocolumn and magnetizing field orientations. We find that deposited cobalt films that have been exposed to heat treatment and subsequent atmospheric oxidation into Co3O4, when not conformally passivated, reveal no measurable magneto-optical properties while cobalt films with passivation coatings retain highly anisotropic magneto-optical properties.

A simple homogeneous model for regular and irregular metallic wire media samples

NASA Astrophysics Data System (ADS)

Kosulnikov, S. Y.; Mirmoosa, M. S.; Simovski, C. R.

2018-02-01

To simplify the solution of electromagnetic problems with wire media samples, it is reasonable to treat them as the samples of a homogeneous material without spatial dispersion. The account of spatial dispersion implies additional boundary conditions and makes the solution of boundary problems difficult especially if the sample is not an infinitely extended layer. Moreover, for a novel type of wire media - arrays of randomly tilted wires - a spatially dispersive model has not been developed. Here, we introduce a simplistic heuristic model of wire media samples shaped as bricks. Our model covers WM of both regularly and irregularly stretched wires.

Enhancing the Electrochemical Behavior of Pure Copper by Cyclic Potentiodynamic Passivation: A Comparison between Coarse- and Nano-Grained Pure Copper

NASA Astrophysics Data System (ADS)

Fattah-alhosseini, Arash; Imantalab, Omid; Attarzadeh, Farid Reza

2016-10-01

Electrochemical behavior of coarse- and nano-grained pure copper were modified and improved to a large extent by the application of cyclic potentiodynamic passivation. The efficacy of this method was evaluated on the basis of grain size which is of great importance in corrosion studies. In this study, the eight passes of accumulative roll bonding process at room temperature were successfully performed to produce nano-grained pure copper. Transmission electron microscopy image indicated that the average grain size reached below 100 nm after eight passes. On the basis of cyclic voltammetry and also the electrochemical tests performed after that, it was revealed that cyclic potentiodynamic passivation had a significant improving effect on the passive behavior of both coarse- and nano-grained samples. In addition, a superior behavior of nano-grained sample in comparison to coarse-grained one was distinguished by its smaller cyclic voltammogram loops, nobler free potentials, larger capacitive arcs in the Nyquist plots, and less charge carrier densities within the passive film.

How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study

PubMed Central

Léger, Julie; Tandé, Didier; Plouzeau, Chloé; Valentin, Anne Sophie; Jolivet-Gougeon, Anne; Lemarié, Carole; Kempf, Marie; Héry-Arnaud, Geneviève; Bret, Laurent; Juvin, Marie Emmanuelle; Giraudeau, Bruno; Burucoa, Christophe

2015-01-01

Although numerous perioperative samples and culture media are required to diagnose prosthetic joint infection (PJI), their exact number and types have not yet been definitely determined with a high level of proof. We conducted a prospective multicenter study to determine the minimal number of samples and culture media required for accurate diagnosis of PJI. Over a 2-year period, consecutive patients with clinical signs suggesting PJI were included, with five perioperative samples per patient. The bacteriological and PJI diagnosis criteria were assessed using a random selection of two, three, or four samples and compared with those obtained using the recommended five samples (references guidelines). The results obtained with two or three culture media were then compared with those obtained with five culture media for both criteria. The times-to-positivity of the different culture media were calculated. PJI was confirmed in 215/264 suspected cases, with a bacteriological criterion in 192 (89%). The PJI was monomicrobial (85%) or polymicrobial (15%). Percentages of agreement of 98.1% and 99.7%, respectively, for the bacteriological criterion and confirmed PJI diagnosis were obtained when four perioperative samples were considered. The highest percentages of agreement were obtained with the association of three culture media, a blood culture bottle, a chocolate agar plate, and Schaedler broth, incubated for 5, 7, and 14 days, respectively. This new procedure leads to significant cost saving. Our prospective multicenter study showed that four samples seeded on three culture media are sufficient for diagnosing PJI. PMID:26637380

How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study.

PubMed

Bémer, Pascale; Léger, Julie; Tandé, Didier; Plouzeau, Chloé; Valentin, Anne Sophie; Jolivet-Gougeon, Anne; Lemarié, Carole; Kempf, Marie; Héry-Arnaud, Geneviève; Bret, Laurent; Juvin, Marie Emmanuelle; Giraudeau, Bruno; Corvec, Stéphane; Burucoa, Christophe

2016-02-01

Although numerous perioperative samples and culture media are required to diagnose prosthetic joint infection (PJI), their exact number and types have not yet been definitely determined with a high level of proof. We conducted a prospective multicenter study to determine the minimal number of samples and culture media required for accurate diagnosis of PJI. Over a 2-year period, consecutive patients with clinical signs suggesting PJI were included, with five perioperative samples per patient. The bacteriological and PJI diagnosis criteria were assessed using a random selection of two, three, or four samples and compared with those obtained using the recommended five samples (references guidelines). The results obtained with two or three culture media were then compared with those obtained with five culture media for both criteria. The times-to-positivity of the different culture media were calculated. PJI was confirmed in 215/264 suspected cases, with a bacteriological criterion in 192 (89%). The PJI was monomicrobial (85%) or polymicrobial (15%). Percentages of agreement of 98.1% and 99.7%, respectively, for the bacteriological criterion and confirmed PJI diagnosis were obtained when four perioperative samples were considered. The highest percentages of agreement were obtained with the association of three culture media, a blood culture bottle, a chocolate agar plate, and Schaedler broth, incubated for 5, 7, and 14 days, respectively. This new procedure leads to significant cost saving. Our prospective multicenter study showed that four samples seeded on three culture media are sufficient for diagnosing PJI. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Temperature dependent absorption measurement of various transition metal doped laser materials

NASA Astrophysics Data System (ADS)

Horackova, Lucie; Šulc, Jan; Jelinkova, Helena; Jambunathan, Venkatesan; Lucianetti, Antonio; Mocek, Tomás.

2015-05-01

In recent years, there has been a vast development of high energy class lasers of the order of 100 J to kJ level which have potential applications in the field of science and technology. Many such systems use the gain media cooled at cryogenic temperatures which will help in enhancing the spectroscopic and thermo-optical properties. Nevertheless, parasitic effects like amplified spontaneous emission enhance and affect the overall efficiency. The best way to suppress this effect is to use cladding element attached to the gain material. Based on these facts, this work was focused on the systematic investigation of temperature dependent absorption of several materials doped with transition metals, which can be used as cladding, as laser gain material, or as passive Q-switching element. The Ti:sapphire, Cr:YAG, V:YAG, and Co:MALO samples were measured in temperature range from 80 K to 330 K by step of 50 K. Using Beer-Lambert law we estimated the absorption coefficient of these materials.

Assessment of the usefulness of semipermeable membrane devices for long-term watershed monitoring in an urban slough system

USGS Publications Warehouse

McCarthy, K.

2006-01-01

Semipermeable membrane devices (SPMDs) were deployed at eight sites within the Buffalo Slough, near Portland, Oregon, to (1) measure the spatial and seasonal distribution of dissolved polycyclic aromatic hydrocarbon (PAH) and organochlorine (OC) compounds in the slough, (2) assess the usefulness of SPMDs as a tool for investigating and monitoring hydrophobic compounds throughout the Columbia Slough system, and (3) evaluate the utility of SPMDs as a tool for measuring the long-term effects of watershed improvement activities. Data from the SPMDs revealed clear spatial and seasonal differences in water quality within the slough and indicate that for hydrophobic compounds, this time-integrated passive-sampling technique is a useful tool for long-term watershed monitoring. In addition, the data suggest that a spiking rate of 2-5 ??g/SPMD of permeability/performance reference compounds, including at least one compound that is not susceptible to photodegradation, may be optimum for the conditions encountered here. ?? Springer Science + Business Media, Inc. 2006.

Laboratory, Field, and Analytical Procedures for Using ...

EPA Pesticide Factsheets

Regardless of the remedial technology invoked to address contaminated sediments in the environment, there is a critical need to have tools for assessing the effectiveness of the remedy. In the past, these tools have included chemical and biomonitoring of the water column and sediments, toxicity testing and bioaccumulation studies performed on site sediments, and application of partitioning, transport and fate modeling. All of these tools served as lines of evidence for making informed environmental management decisions at contaminated sediment sites. In the last ten years, a new tool for assessing remedial effectiveness has gained a great deal of attention. Passive sampling offers a tool capable of measuring the freely dissolved concentration (Cfree) of legacy contaminants in water and sediments. In addition to assessing the effectiveness of the remedy, passive sampling can be applied for a variety of other contaminated sediments site purposes involved with performing the preliminary assessment and site inspection, conducting the remedial investigation and feasibility study, preparing the remedial design, and assessing the potential for contaminant bioaccumulation. While there is a distinct need for using passive sampling at contaminated sediments sites and several previous documents and research articles have discussed various aspects of passive sampling, there has not been definitive guidance on the laboratory, field and analytical procedures for using pas

Modern Social Media and Social Revolutions

DTIC Science & Technology

2011-12-16

Ravi Kumar, Jasmine Noval, and Andrew Tomkins found similar results in their study of “Flickr” and “Yahoo! 360” (Kumar, Novak, and Tomkins 2006...the event through passive engagement, in essence , creating a feedback loop that gets stronger with the passage of time. Given the instantaneity at...to the digital age. New York: The Continuum Publishing Company. Kumar, Ravi, Jasmine Novak, and Andrew Tomkins. 2006. Structure and evolution of

Passive flux meter measurement of water and nutrient flux in saturated porous media: bench-scale laboratory tests.

PubMed

Cho, Jaehyun; Annable, Michael D; Jawitz, James W; Hatfield, Kirk

2007-01-01

The passive nutrient flux meter (PNFM) is introduced for simultaneous measurement of both water and nutrient flux through saturated porous media. The PNFM comprises a porous sorbent pre-equilibrated with a suite of alcohol tracers, which have different partitioning coefficients. Water flux was estimated based on the loss of loaded resident tracers during deployment, while nutrient flux was quantified based on the nutrient solute mass captured on the sorbent. An anionic resin, Lewatit 6328 A, was used as a permeable sorbent and phosphate (PO4(3-)) was the nutrient studied. The phosphate sorption capacity of the resin was measured in batch equilibration tests as 56 mg PO4(3-) g(-1), which was determined to be adequate capacity to retain PO4(3-) loads intercepted over typical PNFM deployment periods in most natural systems. The PNFM design was validated with bench-scale laboratory tests for a range of 9.8 to 28.3 cm d(-1) Darcy velocities and 6 to 43 h deployment durations. Nutrient and water fluxes measured by the PNFM averaged within 6 and 12% of the applied values, respectively, indicating that the PNFM shows promise as a tool for simultaneous measurement of water and nutrient fluxes.

Prevalence and Effect of Cyberbullying on Children and Young People: A Scoping Review of Social Media Studies.

PubMed

Hamm, Michele P; Newton, Amanda S; Chisholm, Annabritt; Shulhan, Jocelyn; Milne, Andrea; Sundar, Purnima; Ennis, Heather; Scott, Shannon D; Hartling, Lisa

2015-08-01

Social media has had a profound effect on how children and adolescents interact. While there are many benefits to the use of social media, cyberbullying has emerged as a potential harm, raising questions regarding its influence on mental health. To review existing publications that examine the health-related effects of cyberbullying via social media among children and adolescents. We searched 11 electronic databases from January 1, 2000, through January 17, 2012 (updated June 24, 2014). Studies were screened by 2 independent reviewers and were included if they reported primary research, described or evaluated the use of a social media tool in the context of cyberbullying, and were conducted with children or adolescents. Data were extracted by 1 reviewer and verified by a second. All studies were assessed by 2 reviewers for methodological quality using the Mixed Methods Appraisal Tool. Results were not pooled owing to heterogeneity in study objectives and outcomes; a narrative analysis is presented. Thirty-six studies in 34 publications were included. Most were conducted in the United States (21 [58.3%]), sampled middle and high school populations (24 [66.7%]), and included adolescents who were 12 to 18 years of age (35 [97.2%]). The median reported prevalence of cyberbullying was 23.0% (interquartile range, 11.0%-42.6%). Five studies reported inconsistent and/or weak correlations between cyberbullying and anxiety. Ten studies found a statistically significant association between cyberbullying and report of depression. Five studies investigated self-harm or suicidality, with conflicting results. Results indicate that the most common reason for cyberbullying is relationship issues, with girls most often being the recipients. Responses to cyberbullying are most often passive, with a pervasive lack of awareness or confidence that anything can be done. There is a consistent relationship across studies between cyberbullying and depression among children and adolescents; however, the evidence of the effect of cyberbullying on other mental health conditions is inconsistent. This review provides important information that characterizes cyberbullying within the context of social media, including attributes of the recipients and perpetrators, reasons for and the nature of bullying behaviors, and how recipients react to and manage bullying behaviors. This information is critical to the development of effective prevention and management strategies.

Statistical Methods for Passive Vehicle Classification in Urban Traffic Surveillance and Control

DOT National Transportation Integrated Search

1980-01-01

A statistical approach to passive vehicle classification using the phase-shift signature from electromagnetic presence-type vehicle detectors is developed with digitized samples of the analog phase-shift signature, the problem of classifying vehicle ...

The Mediating Roles of Upward Social Comparison and Self-esteem and the Moderating Role of Social Comparison Orientation in the Association between Social Networking Site Usage and Subjective Well-Being.

PubMed

Wang, Jin-Liang; Wang, Hai-Zhen; Gaskin, James; Hawk, Skyler

2017-01-01

The increased pervasiveness of social media use has raised questions about potential effects on users' subjective well-being, with studies reaching contrasting conclusions. To reconcile these discrepancies and shed new light on this phenomenon, the current study examined: (1) whether upward social comparison and self-esteem mediate the association between social networking site (SNS) usage and users' subjective well-being, and (2) whether the association between SNS usage and upward social comparison is moderated by users' social comparison orientation. Data from 696 participants were collected. Structural equation modeling revealed that upward social comparison and self-esteem mediated the relationship between SNS usage and users' subjective well-being. We found that social comparison orientation moderated the association between passive SNS usage and users' upward social comparison. Specifically, social comparison orientation strengthened the association between passive SNS usage and upward social comparison. The results might suggest a process through which passive SNS usage is related to subjective well-being, and identify a context under which these associations may differ.

The Mediating Roles of Upward Social Comparison and Self-esteem and the Moderating Role of Social Comparison Orientation in the Association between Social Networking Site Usage and Subjective Well-Being

PubMed Central

Wang, Jin-Liang; Wang, Hai-Zhen; Gaskin, James; Hawk, Skyler

2017-01-01

The increased pervasiveness of social media use has raised questions about potential effects on users’ subjective well-being, with studies reaching contrasting conclusions. To reconcile these discrepancies and shed new light on this phenomenon, the current study examined: (1) whether upward social comparison and self-esteem mediate the association between social networking site (SNS) usage and users’ subjective well-being, and (2) whether the association between SNS usage and upward social comparison is moderated by users’ social comparison orientation. Data from 696 participants were collected. Structural equation modeling revealed that upward social comparison and self-esteem mediated the relationship between SNS usage and users’ subjective well-being. We found that social comparison orientation moderated the association between passive SNS usage and users’ upward social comparison. Specifically, social comparison orientation strengthened the association between passive SNS usage and upward social comparison. The results might suggest a process through which passive SNS usage is related to subjective well-being, and identify a context under which these associations may differ. PMID:28553256

Children Deserve Smoke Free World.

PubMed

Remesh Kumar, R; Jayakumar, P R; Krishna Mohan, R

2018-04-01

Tobacco smoke, active or passive exposure was the major cause of preventable morbidity and mortality in the world during twentieth century and will continue to be the same in the twenty-first century also if the current trends continue. Both active and passive smoking are having significance in relation to child health. Exposure starts antenatally from placenta to the fetus and later phases through passive exposure to experimental and regular smoking and ultimately addiction and habitual smoking. Evidences are in favour of causal relationship with intrauterine growth restriction, sudden infant death syndrome, decreased pulmonary function, increased risk for respiratory tract infection, otitis media, wheeze, asthma, neurobehavioral disorders, cleft palate and triggering pathogenesis of fetal and childhood onset of adult diseases, especially pulmonary and cardio vascular diseases. All these facts stress the importance of behavioral changes in the population as well as stringent public health measures and legislation for ensuring smoke free work places, public places and households for children. M POWER- Package by WHO is a novel global initiative taking us closer to the target of achieving tobacco free environment for children in the near future.

Comparison of a novel passive sampler to standard water-column sampling for organic contaminants associated with wastewater effluents entering a New Jersey stream

USGS Publications Warehouse

Alvarez, D.A.; Stackelberg, P.E.; Petty, J.D.; Huckins, J.N.; Furlong, E.T.; Zaugg, S.D.; Meyer, M.T.

2005-01-01

Four water samples collected using standard depth and width water-column sampling methodology were compared to an innovative passive, in situ, sampler (the polar organic chemical integrative sampler or POCIS) for the detection of 96 organic wastewater-related contaminants (OWCs) in a stream that receives agricultural, municipal, and industrial wastewaters. Thirty-two OWCs were identified in POCIS extracts whereas 9-24 were identified in individual water-column samples demonstrating the utility of POCIS for identifying contaminants whose occurrence are transient or whose concentrations are below routine analytical detection limits. Overall, 10 OWCs were identified exclusively in the POCIS extracts and only six solely identified in the water-column samples, however, repetitive water samples taken using the standard method during the POCIS deployment period required multiple trips to the sampling site and an increased number of samples to store, process, and analyze. Due to the greater number of OWCs detected in the POCIS extracts as compared to individual water-column samples, the ease of performing a single deployment as compared to collecting and processing multiple water samples, the greater mass of chemical residues sequestered, and the ability to detect chemicals which dissipate quickly, the passive sampling technique offers an efficient and effective alternative for detecting OWCs in our waterways for wastewater contaminants.

Model-based monitoring of stormwater runoff quality.

PubMed

Birch, Heidi; Vezzaro, Luca; Mikkelsen, Peter Steen

2013-01-01

Monitoring of micropollutants (MP) in stormwater is essential to evaluate the impacts of stormwater on the receiving aquatic environment. The aim of this study was to investigate how different strategies for monitoring of stormwater quality (combining a model with field sampling) affect the information obtained about MP discharged from the monitored system. A dynamic stormwater quality model was calibrated using MP data collected by automatic volume-proportional sampling and passive sampling in a storm drainage system on the outskirts of Copenhagen (Denmark) and a 10-year rain series was used to find annual average (AA) and maximum event mean concentrations. Use of this model reduced the uncertainty of predicted AA concentrations compared to a simple stochastic method based solely on data. The predicted AA concentration, obtained by using passive sampler measurements (1 month installation) for calibration of the model, resulted in the same predicted level but with narrower model prediction bounds than by using volume-proportional samples for calibration. This shows that passive sampling allows for a better exploitation of the resources allocated for stormwater quality monitoring.

Techniques for active passivation

DOEpatents

Roscioli, Joseph R.; Herndon, Scott C.; Nelson, Jr., David D.

2016-12-20

In one embodiment, active (continuous or intermittent) passivation may be employed to prevent interaction of sticky molecules with interfaces inside of an instrument (e.g., an infrared absorption spectrometer) and thereby improve response time. A passivation species may be continuously or intermittently applied to an inlet of the instrument while a sample gas stream is being applied. The passivation species may have a highly polar functional group that strongly binds to either water or polar groups of the interfaces, and once bound presents a non-polar group to the gas phase in order to prevent further binding of polar molecules. The instrument may be actively used to detect the sticky molecules while the passivation species is being applied.

KSC-2015-1219

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Dara Entekhabi, science team leader at the Massachusetts Institute of Technology in Cambridge, Massachusetts, and other experts discuss the science and engineering of NASA's Soil Moisture Active Passive mission, or SMAP, with the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

KSC-2015-1218

NASA Image and Video Library

2015-01-28

VANDENBERG AIR FORCE BASE, Calif. – Dara Entekhabi, science team leader at the Massachusetts Institute of Technology in Cambridge, Massachusetts, discusses the science and engineering of NASA's Soil Moisture Active Passive mission, or SMAP, with the audience of a NASA Social held at Vandenberg Air Force Base in California. This NASA Social brought together mission scientists and engineers with an audience of 70 students, educators, social media managers, bloggers, photographers and videographers who were selected from a pool of 325 applicants from 45 countries to participate in launch activities and communicate their experience with social media followers. The SMAP mission is scheduled to launch from Vandenberg on Jan. 29. To learn more about SMAP, visit http://www.nasa.gov/smap. Photo credit: NASA/Kim Shiflett

Hydrodynamic dispersion in porous media with macroscopic disorder of parameters

NASA Astrophysics Data System (ADS)

Goldobin, D. S.; Maryshev, B. S.

2017-10-01

We present an analytical derivation of the macroscopic hydrodynamic dispersion for flows in porous media with frozen disorder of macroscopic parameters: porosity and permeability. The parameter inhomogeneities generate inhomogeneities of filtration flow which perform fluid mixing and, on the large spacial scale, act as an additional effective diffusion (eddy diffusivity or hydrodynamic dispersion). The derivation is performed for the general case, where the only restrictions are (i) the spatial autocorrelation functions of parameter inhomogeneities decay with the distance r not slower than 1/rn with n > 1, and (ii) the amplitudes of inhomogeneities are small compared to the mean value of parameters. Our analytical findings are confirmed with the results of direct numerical simulation for the transport of a passive scalar in inhomogeneous filtration flow.

Optical effects module and passive sample array

NASA Technical Reports Server (NTRS)

Linton, R. C.

1983-01-01

The Optical Effects Module (OEM) has the objective to monitor the effects of the deposition and adhesion of both molecular species and particles on optical surfaces in the Shuttle cargo bay environment. The OEM performs inflight measurements of the ultraviolet (253.7 nm) transmittance and diffuse reflectance of five optical samples at regular intervals throughout the orbital mission. Most of the obtained results indicates or implies the absence of a significant accumulation of contamination other than particulates on the samples. The contaminant species (or particulates) adhering to the samples of the Passive Sample Array (PSA) were identified by means of Auger and X-ray energy dispersive analyses. The elements silicon, chlorine, and phosphorus were discovered.

Simulating and explaining passive air sampling rates for semi-volatile compounds on polyurethane foam passive samplers

PubMed Central

Petrich, Nicholas T.; Spak, Scott N.; Carmichael, Gregory R.; Hu, Dingfei; Martinez, Andres; Hornbuckle, Keri C.

2013-01-01

Passive air samplers (PAS) including polyurethane foam (PUF) are widely deployed as an inexpensive and practical way to sample semi-volatile pollutants. However, concentration estimates from PAS rely on constant empirical mass transfer rates, which add unquantified uncertainties to concentrations. Here we present a method for modeling hourly sampling rates for semi-volatile compounds from hourly meteorology using first-principle chemistry, physics, and fluid dynamics, calibrated from depuration experiments. This approach quantifies and explains observed effects of meteorology on variability in compound-specific sampling rates and analyte concentrations; simulates nonlinear PUF uptake; and recovers synthetic hourly concentrations at a reference temperature. Sampling rates are evaluated for polychlorinated biphenyl congeners at a network of Harner model samplers in Chicago, Illinois during 2008, finding simulated average sampling rates within analytical uncertainty of those determined from loss of depuration compounds, and confirming quasi-linear uptake. Results indicate hourly, daily and interannual variability in sampling rates, sensitivity to temporal resolution in meteorology, and predictable volatility-based relationships between congeners. We quantify importance of each simulated process to sampling rates and mass transfer and assess uncertainty contributed by advection, molecular diffusion, volatilization, and flow regime within the PAS, finding PAS chamber temperature contributes the greatest variability to total process uncertainty (7.3%). PMID:23837599

Biofilm imaging in porous media by laboratory X-Ray tomography: Combining a non-destructive contrast agent with propagation-based phase-contrast imaging tools.

PubMed

Carrel, Maxence; Beltran, Mario A; Morales, Verónica L; Derlon, Nicolas; Morgenroth, Eberhard; Kaufmann, Rolf; Holzner, Markus

2017-01-01

X-ray tomography is a powerful tool giving access to the morphology of biofilms, in 3D porous media, at the mesoscale. Due to the high water content of biofilms, the attenuation coefficient of biofilms and water are very close, hindering the distinction between biofilms and water without the use of contrast agents. Until now, the use of contrast agents such as barium sulfate, silver-coated micro-particles or 1-chloronaphtalene added to the liquid phase allowed imaging the biofilm 3D morphology. However, these contrast agents are not passive and potentially interact with the biofilm when injected into the sample. Here, we use a natural inorganic compound, namely iron sulfate, as a contrast agent progressively bounded in dilute or colloidal form into the EPS matrix during biofilm growth. By combining a very long source-to-detector distance on a X-ray laboratory source with a Lorentzian filter implemented prior to tomographic reconstruction, we substantially increase the contrast between the biofilm and the surrounding liquid, which allows revealing the 3D biofilm morphology. A comparison of this new method with the method proposed by Davit et al (Davit et al., 2011), which uses barium sulfate as a contrast agent to mark the liquid phase was performed. Quantitative evaluations between the methods revealed substantial differences for the volumetric fractions obtained from both methods. Namely, contrast agent-biofilm interactions (e.g. biofilm detachment) occurring during barium sulfate injection caused a reduction of the biofilm volumetric fraction of more than 50% and displacement of biofilm patches elsewhere in the column. Two key advantages of the newly proposed method are that passive addition of iron sulfate maintains the integrity of the biofilm prior to imaging, and that the biofilm itself is marked by the contrast agent, rather than the liquid phase as in other available methods. The iron sulfate method presented can be applied to understand biofilm development and bioclogging mechanisms in porous materials and the obtained biofilm morphology could be an ideal basis for 3D numerical calculations of hydrodynamic conditions to investigate biofilm-flow coupling.

Biofilm imaging in porous media by laboratory X-Ray tomography: Combining a non-destructive contrast agent with propagation-based phase-contrast imaging tools

PubMed Central

Beltran, Mario A.; Morales, Verónica L.; Derlon, Nicolas; Morgenroth, Eberhard; Kaufmann, Rolf; Holzner, Markus

2017-01-01

X-ray tomography is a powerful tool giving access to the morphology of biofilms, in 3D porous media, at the mesoscale. Due to the high water content of biofilms, the attenuation coefficient of biofilms and water are very close, hindering the distinction between biofilms and water without the use of contrast agents. Until now, the use of contrast agents such as barium sulfate, silver-coated micro-particles or 1-chloronaphtalene added to the liquid phase allowed imaging the biofilm 3D morphology. However, these contrast agents are not passive and potentially interact with the biofilm when injected into the sample. Here, we use a natural inorganic compound, namely iron sulfate, as a contrast agent progressively bounded in dilute or colloidal form into the EPS matrix during biofilm growth. By combining a very long source-to-detector distance on a X-ray laboratory source with a Lorentzian filter implemented prior to tomographic reconstruction, we substantially increase the contrast between the biofilm and the surrounding liquid, which allows revealing the 3D biofilm morphology. A comparison of this new method with the method proposed by Davit et al (Davit et al., 2011), which uses barium sulfate as a contrast agent to mark the liquid phase was performed. Quantitative evaluations between the methods revealed substantial differences for the volumetric fractions obtained from both methods. Namely, contrast agent—biofilm interactions (e.g. biofilm detachment) occurring during barium sulfate injection caused a reduction of the biofilm volumetric fraction of more than 50% and displacement of biofilm patches elsewhere in the column. Two key advantages of the newly proposed method are that passive addition of iron sulfate maintains the integrity of the biofilm prior to imaging, and that the biofilm itself is marked by the contrast agent, rather than the liquid phase as in other available methods. The iron sulfate method presented can be applied to understand biofilm development and bioclogging mechanisms in porous materials and the obtained biofilm morphology could be an ideal basis for 3D numerical calculations of hydrodynamic conditions to investigate biofilm-flow coupling. PMID:28732010

Quantitative assessment of bio-aerosols contamination in indoor air of University dormitory rooms.

PubMed

Hayleeyesus, Samuel Fekadu; Ejeso, Amanuel; Derseh, Fikirte Aklilu

2015-07-01

The purpose of this study is to provide insight into how students are exposed to indoor bio-aerosols in the dormitory rooms and to figure out the major possible factors that govern the contamination levels. The Bio-aerosols concentration level of indoor air of thirty dormitory rooms of Jimma University was determined by taking 120 samples. Passive air sampling technique; the settle plate method using open Petri-dishes containing different culture media was employed to collect sample twice daily. The range of bio-aerosols contamination detected in the dormitory rooms was 511-9960 CFU/m(3) for bacterial and 531-6568 CFU/m(3) for fungi. Based on the criteria stated by WHO expert group, from the total 120 samples 95 of the samples were above the recommended level. The statistical analysis showed that, occupancy were significantly affected the concentrations of bacteria that were measured in all dormitory rooms at 6:00 am sampling time (p-value=0.000) and also the concentrations of bacteria that were measured in all dormitory rooms were significantly different to each other (p-value=0.013) as of their significance difference in occupancy (p-value=0.000). Moreover, there were a significant different on the contamination level of bacteria at 6:00 am and 7:00 pm sampling time (p=0.015), whereas there is no significant difference for fungi contamination level for two sampling times (p= 0.674). There is excessive bio-aerosols contaminant in indoor air of dormitory rooms of Jimma University and human occupancy produces a marked concentration increase of bacterial contamination levels and most fungi species present into the rooms air of Jimma University dormitory were not human-borne.

Quantitative assessment of bio-aerosols contamination in indoor air of University dormitory rooms

PubMed Central

Hayleeyesus, Samuel Fekadu; Ejeso, Amanuel; Derseh, Fikirte Aklilu

2015-01-01

Objectives The purpose of this study is to provide insight into how students are exposed to indoor bio-aerosols in the dormitory rooms and to figure out the major possible factors that govern the contamination levels. Methodology The Bio-aerosols concentration level of indoor air of thirty dormitory rooms of Jimma University was determined by taking 120 samples. Passive air sampling technique; the settle plate method using open Petri-dishes containing different culture media was employed to collect sample twice daily. Results The range of bio-aerosols contamination detected in the dormitory rooms was 511–9960 CFU/m3 for bacterial and 531–6568 CFU/m3 for fungi. Based on the criteria stated by WHO expert group, from the total 120 samples 95 of the samples were above the recommended level. The statistical analysis showed that, occupancy were significantly affected the concentrations of bacteria that were measured in all dormitory rooms at 6:00 am sampling time (p-value=0.000) and also the concentrations of bacteria that were measured in all dormitory rooms were significantly different to each other (p-value=0.013) as of their significance difference in occupancy (p-value=0.000). Moreover, there were a significant different on the contamination level of bacteria at 6:00 am and 7:00 pm sampling time (p=0.015), whereas there is no significant difference for fungi contamination level for two sampling times (p= 0.674). Conclusion There is excessive bio-aerosols contaminant in indoor air of dormitory rooms of Jimma University and human occupancy produces a marked concentration increase of bacterial contamination levels and most fungi species present into the rooms air of Jimma University dormitory were not human-borne. PMID:26609289

Performance of Passive Samplers for Monitoring Estuarine Water Column Concentrations: 2. Emerging Contaminants

EPA Science Inventory

Measuring dissolved concentrations of emerging contaminants, such as polybrominated diphenyl ethers (PBDEs) and triclosan (TCS), can be challenging due to their physicochemical properties resulting in low aqueous solubilities and association with particles. Passive sampling meth...

Trends in monitoring pharmaceuticals and personal-care products in the aquatic environment by use of passive sampling devices

USGS Publications Warehouse

Mills, G.A.; Vrana, B.; Allan, I.; Alvarez, D.A.; Huckins, J.N.; Greenwood, R.

2007-01-01

The use of passive sampling in monitoring pharmaceuticals and personal-care products (PPCPs) in the aquatic environment is discussed. The utility of passive sampling methods for monitoring the fraction of heavy metals and the biologically available fraction of non-polar organic priority pollutants is recognized and these technologies are being used in surveys of water quality. These devices are used to measure the dissolved fraction and they can yield information that can be used in the development of risk assessments models. These devices can also be used to locate illegal dumping and to monitor specific sources of input of PPCPs into the environment, or to monitor the effectiveness of water treatment processes in the removal of these compounds from wastewater. These devices can provide representative information at low cost which necessitate a combination of laboratory calibration and field studies for emerging pollutants.

Labile, dissolved and particulate PAHs and trace metals in wastewater: passive sampling, occurrence, partitioning in treatment plants.

PubMed

Gourlay-Francé, C; Bressy, A; Uher, E; Lorgeoux, C

2011-01-01

The occurrence and the partitioning of polycyclic aromatic hydrocarbons (PAHs) and seven metals (Al, Cd, Cr, Cu, Ni, Pb and Zn) were investigated in activated sludge wastewater treatment plants by means of passive and active sampling. Concentrations total dissolved and particulate contaminants were determined in wastewater at several points across the treatment system by means of grab sampling. Truly dissolved PAHs were sampled by means of semipermeable membrane devices. Labile (inorganic and weakly complexed) dissolved metals were also sampled using the diffusive gradient in thin film technique. This study confirms the robustness and the validity of these two passive sampling techniques in wastewater. All contaminant concentrations decreased in wastewater along the treatment, although dissolved and labile concentrations sometimes increased for substances with less affinity with organic matter. Solid-liquid and dissolved organic matter/water partitioning constants were estimated. The high variability of both partitioning constants for a simple substance and the poor relation between K(D) and K(OW) shows that the binding capacities of particles and organic matter are not uniform within the treatment and that other process than equilibrium sorption affect contaminant repartition and fate in wastewater.

Passive sampling for the isotopic fingerprinting of atmospheric mercury

NASA Astrophysics Data System (ADS)

Bergquist, B. A.; MacLagan, D.; Spoznar, N.; Kaplan, R.; Chandan, P.; Stupple, G.; Zimmerman, L.; Wania, F.; Mitchell, C. P. J.; Steffen, A.; Monaci, F.; Derry, L. A.

2017-12-01

Recent studies show that there are variations in the mercury (Hg) isotopic signature of atmospheric Hg, which demonstrates the potential for source tracing and improved understanding of atmospheric cycling of Hg. However, current methods for both measuring atmospheric Hg and collecting enough atmospheric Hg for isotopic analyses require expensive instruments that need power and expertise. Additionally, methods for collecting enough atmospheric Hg for isotopic analysis require pumping air through traps for long periods (weeks and longer). Combining a new passive atmospheric sampler for mercury (Hg) with novel Hg isotopic analyses will allow for the application of stable Hg isotopes to atmospheric studies of Hg. Our group has been testing a new passive sampler for gaseous Hg that relies on the diffusion of Hg through a diffusive barrier and adsorption onto a sulphur-impregnated activated carbon sorbent. The benefit of this passive sampler is that it is low cost, requires no power, and collects gaseous Hg for up to one year with linear, well-defined uptake, which allows for reproducible and accurate measurements of atmospheric gaseous Hg concentrations ( 8% uncertainty). As little as one month of sampling is often adequate to collect sufficient Hg for isotopic analysis at typical background concentrations. Experiments comparing the isotopic Hg signature in activated carbon samples using different approaches (i.e. by passive diffusion, by passive diffusion through diffusive barriers of different thickness, by active pumping) and at different temperatures confirm that the sampling process itself does not impose mass-independent fractionation (MIF). However, sampling does result in a consistent and thus correctable mass-dependent fractionation (MDF) effect. Therefore, the sampler preserves Hg MIF with very high accuracy and precision, which is necessary for atmospheric source tracing, and reasonable MDF can be estimated with some increase in error. In addition to experimental work, initial field data will be presented including a transect of increasing distance from a known strong source of Hg (Mt. Amiata mine, Italy), downwind of Kilauea volcano in Hawaii, and several other locales including the Arctic station Alert and various sites across Ontario, Canada.

Extraction tools for identification of chemical contaminants in estuarine and coastal waters to determine toxic pressure on primary producers.

PubMed

Booij, Petra; Sjollema, Sascha B; Leonards, Pim E G; de Voogt, Pim; Stroomberg, Gerard J; Vethaak, A Dick; Lamoree, Marja H

2013-09-01

The extent to which chemical stressors affect primary producers in estuarine and coastal waters is largely unknown. However, given the large number of legacy pollutants and chemicals of emerging concern present in the environment, this is an important and relevant issue that requires further study. The purpose of our study was to extract and identify compounds which are inhibitors of photosystem II activity in microalgae from estuarine and coastal waters. Field sampling was conducted in the Western Scheldt estuary (Hansweert, The Netherlands). We compared four different commonly used extraction methods: passive sampling with silicone rubber sheets, polar organic integrative samplers (POCIS) and spot water sampling using two different solid phase extraction (SPE) cartridges. Toxic effects of extracts prepared from spot water samples and passive samplers were determined in the Pulse Amplitude Modulation (PAM) fluorometry bioassay. With target chemical analysis using LC-MS and GC-MS, a set of PAHs, PCBs and pesticides was determined in field samples. These compound classes are listed as priority substances for the marine environment by the OSPAR convention. In addition, recovery experiments with both SPE cartridges were performed to evaluate the extraction suitability of these methods. Passive sampling using silicone rubber sheets and POCIS can be applied to determine compounds with different structures and polarities for further identification and determination of toxic pressure on primary producers. The added value of SPE lies in its suitability for quantitative analysis; calibration of passive samplers still needs further investigation for quantification of field concentrations of contaminants. Copyright © 2013 Elsevier Ltd. All rights reserved.

A pragmatic examination of active and passive recruitment methods to improve the reach of community lifestyle programs: The Talking Health Trial.

PubMed

Estabrooks, Paul; You, Wen; Hedrick, Valisa; Reinholt, Margaret; Dohm, Erin; Zoellner, Jamie

2017-01-19

A primary challenge for behavior change strategies is ensuring that interventions can be effective while also attracting a broad and representative sample of the target population. The purpose of this case-study was to report on (1) the reach of a randomized controlled trial targeting reduced sugary beverages, (2) potential participant characteristic differences based on active versus passive recruitment strategies, and (3) recruitment strategy cost. Demographic and recruitment information was obtained for 8 counties and for individuals screened for participation. Personnel activities and time were tracked. Costs were calculated and compared by active versus passive recruitment. Six-hundred and twenty, of 1,056 screened, individuals were eligible and 301enrolled (77% women; 90% white; mean income $21,981 ± 16,443). Eighty-two and 44% of those responding to passive and active methods, respectively, enrolled in the trial. However, active recruitment strategies yielded considerably more enrolled (active = 199; passive = 102) individuals. Passive recruitment strategies yielded a less representative sample in terms of gender (more women), education (higher), and income (higher; p's <0.05). The average cost of an actively recruited and enrolled participant was $278 compared to $117 for a passively recruited and enrolled participant. Though passive recruitment is more cost efficient it may reduce the reach of sugary drink reduction strategies in lower educated and economic residents in rural communities. Clinicaltrials.gov; ID: NCT02193009 , July 2014, retrospectively registered.

Obstetric and perinatal effects of active and/or passive smoking during pregnancy.

PubMed

Nakamura, Mary Uchiyama; Alexandre, Sandra Maria; Kuhn dos Santos, Jorge Francisco; de Souza, Eduardo; Sass, Nelson; Auritscher Beck, Anna Paula; Trayna, Evelyn; Andrade, Carla Maria de Araújo; Barroso, Teresa; Kulay Júnior, Luiz

2004-05-06

Cigarette smoke, whether inhaled voluntarily or not, causes damage to the mother-infant pair. The antenatal period may present the best opportunity for performing effective anti-smoking campaigns. To study the obstetric and perinatal effects of smoking on pregnancy and the infant. Prospective study, interviewing pregnant women who were randomly selected at the maternity hospital as they were being discharged after giving birth. Hospital Municipal Vereador José Storópolli, São Paulo, Brazil. 758 patients were interviewed regarding smoke inhalation before being discharged from the maternity hospital. The groups were formed by 42 active smokers, 272 passive smokers, 108 who inhaled smoke both actively and passively, and 336 non-smokers. The groups were compared regarding age, parity, school education, incidence of spontaneous abortion, rate of caesarian births, average gestational age at birth, rate of low birth weight and adequacy of weight in relation to the gestational age of newborn infants. For all variables we considered p < 0.05 as statistically significant. There was a high rate (55.7%) of pregnant smokers, including 5.5% active, 35.9% passive and 14.3% active-passive smokers. Active and active-passive smokers were older and had higher parity. Active smokers had lower education levels and higher rates of previous spontaneous abortion. The weights of newborn babies were lower for smoking mothers. The study was performed among patients that were mostly of low economic, social and cultural levels, thus possibly explaining the high incidence of smokers. Worse still was that 35.9% of the non-smokers were actually passive smokers. These rates we report were similar to those from the literature. The typical receptiveness of teenage girls to unrestricted advertising in the media contributes towards an early start to acquiring the habit of smoking, including during pregnancy in our country. We emphasize the difficulties in quantifying exposure to cigarettes even among active smokers. Cigarette smoke, whether inhaled voluntarily or not, has an unfavorable effect on the mother-infant pair.

Occurrence and seasonal distribution of polycyclic aromatic hydrocarbons and legacy and current-use pesticides in air from a Mediterranean coastal lagoon (Mar Menor, SE Spain).

PubMed

Carratalá, A; Moreno-González, R; León, V M

2017-01-01

The occurrence and seasonal distribution of polycyclic aromatic hydrocarbons (PAHs) and legacy and current-use pesticides (CUPs) in air were characterized around the Mar Menor lagoon using both active and passive sampling devices. The seasonal distribution of these pollutants was determined at 6 points using passive samplers. Passive sampler sampling rates were estimated for all detected analytes using an active sampler, considering preferentially winter data, due to probable losses in active sampling during summer (high temperatures and solar irradiation). The presence of 28 compounds (14 CUPs, 11 PAHs and 3 organochlorinated pesticides) were detected in air by polyurethane passive sampling. The most commonly detected contaminants (>95% of samples) in air were chlorpyrifos, chlorpyrifos-methyl and phenanthrene. The maximum concentrations corresponded to phenanthrene (6000 pg m -3 ) and chlorpyrifos (4900 pg m -3 ). The distribution of contaminants was spatially and seasonally heterogeneous. The highest concentrations of PAHs were found close to the airport, while the highest concentrations of pesticides were found in the influence area of agricultural fields (western stations). PAH and herbicide concentrations were higher in winter than in the other seasons, although some insecticides such as chlorpyrifos were more abundant in autumn. The presence of PAHs and legacy and current-use pesticides in air confirmed their transference potential to marine coastal areas such as the Mar Menor lagoon. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improving Toxicity Assessment of Pesticide Mixtures: The Use of Polar Passive Sampling Devices Extracts in Microalgae Toxicity Tests

PubMed Central

Kim Tiam, Sandra; Fauvelle, Vincent; Morin, Soizic; Mazzella, Nicolas

2016-01-01

Complexity of contaminants exposure needs to be taking in account for an appropriate evaluation of risks related to mixtures of pesticides released in the ecosystems. Toxicity assessment of such mixtures can be made through a variety of toxicity tests reflecting different level of biological complexity. This paper reviews the recent developments of passive sampling techniques for polar compounds, especially Polar Organic Chemical Integrative Samplers (POCIS) and Chemcatcher® and the principal assessment techniques using microalgae in laboratory experiments. The progresses permitted by the coupled use of such passive samplers and ecotoxicology testing as well as their limitations are presented. Case studies combining passive sampling devices (PSD) extracts and toxicity assessment toward microorganisms at different biological scales from single organisms to communities level are presented. These case studies, respectively, aimed (i) at characterizing the “toxic potential” of waters using dose-response curves, and (ii) at performing microcosm experiments with increased environmental realism in the toxicant exposure in term of cocktail composition and concentration. Finally perspectives and limitations of such approaches for future applications in the area of environmental risk assessment are discussed. PMID:27667986

The Endemicity of Human Fascioliasis in Guilan Province, Northern Iran: the Baseline for Implementation of Control Strategies

PubMed Central

ASHRAFI, Keyhan; SAADAT, Farshid; O’NEILL, Sandra; RAHMATI, Behnaz; AMIN TAHMASBI, Hadid; PIUS DALTON, John; NADIM, Abolhassan; ASADINEZHAD, Mohsen; REZVANI, Sayed Mahmood

2015-01-01

Background: The largest global outbreaks of liver fluke disease (Fascioliasis) in humans, caused by species of the genus Fasciola, have occurred in Guilan Province of Iran, affecting more than 15000 people. Although, different aspects of fascioliasis have been the subject of various researches during last two decades, nevertheless no community-based study has been performed in endemic regions of Guilan. The aim of present study was to obtain the basic information needed to develop future control strategies. Methods: Fecal and blood samples were collected from 1,984 volunteers in the Bandar-Anzali district, the region where previous epidemics occurred. Fecal samples were examined by Kato-Katz and formalin-ether methods for the presence of Fasciola eggs. Sera samples were analyzed by ELISA to detect anti-cathepsin L antibodies. Results: Twenty-seven (1.36%) individuals were seropositive, 9 (0.45%) individuals were egg positive (mean egg count 50.7 (±30.36) eggs per gram of faeces) and 30 individuals (1.51%) were positive using both methods. No statistical association was observed between infection and age, gender, location, occupation, educational status and dietary habits. The prevalence of intestinal parasites is also included. Conclusion: Human fascioliasis is hypoendemic in this region and recommends a passive case-finding approach, effective primary prevention measures, health education through mass media and effective veterinary public health measures for control of human disease. PMID:26056669

Recruitment of healthy first-trimester pregnant women: lessons from the Chemicals, Health & Pregnancy study (CHirP).

PubMed

Webster, Glenys M; Teschke, Kay; Janssen, Patricia A

2012-02-01

To describe and evaluate recruitment techniques used to enroll 152 healthy pregnant women fewer than 15 weeks gestation into a prospective study of environmental chemical exposure during pregnancy. Posters, a website, online and print advertising, recruitment emails, media coverage, recruitment from clinic waiting rooms, networking within the pregnancy community and presenting a study booth at baby "trade shows" were used to advertise the study. Participants had to meet a strict set of eligibility criteria, and were asked to donate two-second-trimester blood samples, complete two questionnaires, have samples of air, dust, lint and tap water collected from their homes, and donate a cord blood sample at delivery. Over 17 months, 171 women enrolled (49% of initial contacts, and 99% of all eligible women) and 152 women completed the study (89% retention). Total recruitment costs were approximately $400 Cdn per final participant. Posters, study booth presentations and online advertising generated the most inquiries about the study. Word of mouth, referral from another study and direct email were the most cost-effective strategies. Not surprisingly, the recruited study population was less ethnically diverse, more affluent and more educated than the background population of pregnant women in Vancouver. A combination of passive and active recruitment techniques were successful for recruiting healthy women in roughly the first trimester of pregnancy (<15 weeks gestation). While a convenience sample of women is suitable for our study questions, additional strategies may be required to recruit a more representative pregnant population in future studies.

Reductions in Aprotic Media. I. Cathodic Reduction Limits in Acetonitrile at a Platinum Electrode.

DTIC Science & Technology

1981-08-15

specifically; (1) The difference in the effect of water on lithium solutions and tetraalkylammonium solutions, (2) the passivation of a platinum electrode...solutions. 5 EXPERIMENTAL Procedure for Controlled Potential Electrolysis The electrolyses were performed in a glass H-cell. The anode and cathode...fine porous glass frit from the Luggin section. The electrolyses were run in constant potential mode. After electrolysis, the catholyte was removed and

Reconfigurable Optical Elements Based on Single and Coupled Microdisk Resonators with Quantum Dot Active Media

DTIC Science & Technology

2009-08-31

Firstly we investigated the bend loss mechanism in a waveguide made using SU8 - a negative photosensitive polymer . Simulations were performed using...present demonstration, the polymer used was SU8 (Microchem Corp.), a negative photoresist. Patterning of the microdisks were achieved using both soft...Proposed All-optical flip flop which uses a passive microring resonator integrated with active elements. Also shown is the crossesction of the SU8

Storytelling in the digital world: achieving higher-level learning objectives.

PubMed

Schwartz, Melissa R

2012-01-01

Nursing students are not passive media consumers but instead live in a technology ecosystem where digital is the language they speak. To prepare the next generation of nurses, educators must incorporate multiple technologies to improve higher-order learning. The author discusses the evolution and use of storytelling as part of the digital world and how digital stories can be aligned with Bloom's Taxonomy so that students achieve higher-level learning objectives.

Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes

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

Lunden, Melissa; Faulkner, David; Heredia, Elizabeth

2012-10-01

This report documents experiments performed in three homes to assess the methodology used to determine air exchange rates using passive tracer techniques. The experiments used four different tracer gases emitted simultaneously but implemented with different spatial coverage in the home. Two different tracer gas sampling methods were used. The results characterize the factors of the execution and analysis of the passive tracer technique that affect the uncertainty in the calculated air exchange rates. These factors include uncertainties in tracer gas emission rates, differences in measured concentrations for different tracer gases, temporal and spatial variability of the concentrations, the comparison betweenmore » different gas sampling methods, and the effect of different ventilation conditions.« less

Use of mobile and passive badge air monitoring data for NOX and ozone air pollution spatial exposure prediction models.

PubMed

Xu, Wei; Riley, Erin A; Austin, Elena; Sasakura, Miyoko; Schaal, Lanae; Gould, Timothy R; Hartin, Kris; Simpson, Christopher D; Sampson, Paul D; Yost, Michael G; Larson, Timothy V; Xiu, Guangli; Vedal, Sverre

2017-03-01

Air pollution exposure prediction models can make use of many types of air monitoring data. Fixed location passive samples typically measure concentrations averaged over several days to weeks. Mobile monitoring data can generate near continuous concentration measurements. It is not known whether mobile monitoring data are suitable for generating well-performing exposure prediction models or how they compare with other types of monitoring data in generating exposure models. Measurements from fixed site passive samplers and mobile monitoring platform were made over a 2-week period in Baltimore in the summer and winter months in 2012. Performance of exposure prediction models for long-term nitrogen oxides (NO X ) and ozone (O 3 ) concentrations were compared using a state-of-the-art approach for model development based on land use regression (LUR) and geostatistical smoothing. Model performance was evaluated using leave-one-out cross-validation (LOOCV). Models performed well using the mobile peak traffic monitoring data for both NO X and O 3 , with LOOCV R 2 s of 0.70 and 0.71, respectively, in the summer, and 0.90 and 0.58, respectively, in the winter. Models using 2-week passive samples for NO X had LOOCV R 2 s of 0.60 and 0.65 in the summer and winter months, respectively. The passive badge sampling data were not adequate for developing models for O 3 . Mobile air monitoring data can be used to successfully build well-performing LUR exposure prediction models for NO X and O 3 and are a better source of data for these models than 2-week passive badge data.

Soil Moisture Active Passive (SMAP) Media Briefing

NASA Image and Video Library

2015-01-09

Christine Bonniksen, SMAP program executive with the Science Mission Directorate’s Earth Science Division, NASA Headquarters, left, Kent Kellogg, SMAP project manager, NASA Jet Propulsion Laboratory (JPL), second from left, Dara Entekhabi, SMAP science team lead, Massachusetts Institute of Technology, second from right, and Brad Doorn, SMAP applications lead, Science Mission Directorate’s Applied Sciences Program, NASA Headquarters, right, are seen during a briefing about the upcoming launch of the Soil Moisture Active Passive (SMAP) mission, Thursday, Jan. 08, 2015, at NASA Headquarters in Washington DC. The mission is scheduled for a Jan. 29 launch from Vandenberg Air Force Base in California, and will provide the most accurate, highest-resolution global measurements of soil moisture ever obtained from space. The data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles. Photo Credit: (NASA/Aubrey Gemignani)

A population survey on legislative measures to restrict smoking in Ontario: 4. Variables related to knowledge of active and passive smoking health effects and to predicted behavior of smokers and nonsmokers.

PubMed

Pederson, L L; Bull, S B; Ashley, M J; Lefcoe, N M

1989-01-01

Results from the further analysis of a population survey on legislative measures to restrict smoking revealed that identification of subgroups of smokers is more reliable than identification of subgroups of nonsmokers when a variety of attitudes were the measures of interest. A similar pattern emerged when analyses were carried out on knowledge of active and passive smoking health effects and on predicted personal and general compliance. Because distinct sets of variables were found to be related to distinct outcomes, program planning for changes in knowledge and behavior might, of necessity, have to be different. Media messages might be useful for changes in knowledge, while actual experience might be more important for attitude and behavior change.

On-Chip Microwave Quantum Hall Circulator

NASA Astrophysics Data System (ADS)

Mahoney, A. C.; Colless, J. I.; Pauka, S. J.; Hornibrook, J. M.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.; Doherty, A. C.; Reilly, D. J.

2017-01-01

Circulators are nonreciprocal circuit elements that are integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their nonreciprocity arises from the interference of microwaves over the centimeter scale of the signal wavelength, in the presence of bulky magnetic media that breaks time-reversal symmetry. Here, we realize a completely passive on-chip microwave circulator with size 1 /1000 th the wavelength by exploiting the chiral, "slow-light" response of a two-dimensional electron gas in the quantum Hall regime. For an integrated GaAs device with 330 μ m diameter and about 1-GHz center frequency, a nonreciprocity of 25 dB is observed over a 50-MHz bandwidth. Furthermore, the nonreciprocity can be dynamically tuned by varying the voltage at the port, an aspect that may enable reconfigurable passive routing of microwave signals on chip.

Is there a "net generation" in veterinary medicine? A comparative study on the use of the Internet and Web 2.0 by students and the veterinary profession.

PubMed

Tenhaven, Christoph; Tipold, Andrea; Fischer, Martin R; Ehlers, Jan P

2013-01-01

Informal and formal lifelong learning is essential at university and in the workplace. Apart from classical learning techniques, Web 2.0 tools can be used. It is controversial whether there is a so-called net generation amongst people under 30. To test the hypothesis that a net generation among students and young veterinarians exists. An online survey of students and veterinarians was conducted in the German-speaking countries which was advertised via online media and traditional print media. 1780 people took part in the survey. Students and veterinarians have different usage patterns regarding social networks (91.9% vs. 69%) and IM (55.9% vs. 24.5%). All tools were predominantly used passively and in private, to a lesser extent also professionally and for studying. The use of Web 2.0 tools is useful, however, teaching information and media skills, preparing codes of conduct for the internet and verification of user generated content is essential.

Social media in clinical trials.

PubMed

Thompson, Michael A

2014-01-01

Social media has potential in clinical trials for pointing out trial issues, addressing barriers, educating, and engaging multiple groups involved in cancer clinical research. Social media is being used in clinical trials to highlight issues such as poor accrual and barriers; educate potential participants and physicians about clinical trial options; and is a potential indirect or direct method to improve accrual. We are moving from a passive "push" of information to patients to a "pull" of patients requesting information. Patients and advocates are often driving an otherwise reluctant health care system into communication. Online patient communities are creating new information repositories. Potential clinical trial participants are using the Twittersphere and other sources to learn about potential clinical trial options. We are seeing more organized patient-centric and patient-engaged forums with the potential to crowd source to improve clinical trial accrual and design. This is an evolving process that will meet many individual, institutional, and regulatory obstacles as we move forward in a changed research landscape.

Problematic Social Media Use: Results from a Large-Scale Nationally Representative Adolescent Sample

PubMed Central

Bányai, Fanni; Zsila, Ágnes; Király, Orsolya; Maraz, Aniko; Elekes, Zsuzsanna; Griffiths, Mark D.; Andreassen, Cecilie Schou

2017-01-01

Despite social media use being one of the most popular activities among adolescents, prevalence estimates among teenage samples of social media (problematic) use are lacking in the field. The present study surveyed a nationally representative Hungarian sample comprising 5,961 adolescents as part of the European School Survey Project on Alcohol and Other Drugs (ESPAD). Using the Bergen Social Media Addiction Scale (BSMAS) and based on latent profile analysis, 4.5% of the adolescents belonged to the at-risk group, and reported low self-esteem, high level of depression symptoms, and elevated social media use. Results also demonstrated that BSMAS has appropriate psychometric properties. It is concluded that adolescents at-risk of problematic social media use should be targeted by school-based prevention and intervention programs. PMID:28068404

Problematic Social Media Use: Results from a Large-Scale Nationally Representative Adolescent Sample.

PubMed

Bányai, Fanni; Zsila, Ágnes; Király, Orsolya; Maraz, Aniko; Elekes, Zsuzsanna; Griffiths, Mark D; Andreassen, Cecilie Schou; Demetrovics, Zsolt

2017-01-01

Despite social media use being one of the most popular activities among adolescents, prevalence estimates among teenage samples of social media (problematic) use are lacking in the field. The present study surveyed a nationally representative Hungarian sample comprising 5,961 adolescents as part of the European School Survey Project on Alcohol and Other Drugs (ESPAD). Using the Bergen Social Media Addiction Scale (BSMAS) and based on latent profile analysis, 4.5% of the adolescents belonged to the at-risk group, and reported low self-esteem, high level of depression symptoms, and elevated social media use. Results also demonstrated that BSMAS has appropriate psychometric properties. It is concluded that adolescents at-risk of problematic social media use should be targeted by school-based prevention and intervention programs.

Combination of sorption properties of polydimethylsiloxane and solid-phase extraction sorbents in a single composite material for the passive sampling of polar and apolar pesticides in water.

PubMed

Martin, Alexis; Margoum, Christelle; Coquery, Marina; Randon, Jérôme

2016-10-01

Passive sampling techniques have been developed as an alternative method for in situ integrative monitoring of trace levels of neutral pesticides in environmental waters. The objective of this work was to develop a new receiving phase for pesticides with a wide range of polarities in a single step. We describe the development of three new composite silicone rubbers, combining polydimethylsiloxane mechanical and sorption properties with solid-phase extraction sorbents, prepared as a receiving phase for passive sampling. A composite silicone rubber composed of polydimethylsiloxane/poly(divinylbenzene-co-N-vinylpyrrolidone) was selected by batch experiments for its high sorption properties for pesticides with octanol-water partition coefficients ranging from 2.3 to 5.5. We named this composite material "Polar/Apolar Composite Silicone Rubber". A structural study by scanning electron microscopy confirmed the homogeneous dispersion of the sorbent particles and the encapsulation of particles within the polydimethylsiloxane matrix. We also demonstrate that this composite material is resistant to common solvents used for the back-extraction of analytes and has a maximal resistance temperature of 350°C. Therefore, the characteristics of the "Polar/Apolar Composite Silicone Rubber" meet most of the criteria for use as a receiving phase for the passive sampling of pesticides. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of water-based recovery on blood lactate removal after high-intensity exercise.

PubMed

Lucertini, Francesco; Gervasi, Marco; D'Amen, Giancarlo; Sisti, Davide; Rocchi, Marco Bruno Luigi; Stocchi, Vilberto; Benelli, Piero

2017-01-01

This study assessed the effectiveness of water immersion to the shoulders in enhancing blood lactate removal during active and passive recovery after short-duration high-intensity exercise. Seventeen cyclists underwent active water- and land-based recoveries and passive water and land-based recoveries. The recovery conditions lasted 31 minutes each and started after the identification of each cyclist's blood lactate accumulation peak, induced by a 30-second all-out sprint on a cycle ergometer. Active recoveries were performed on a cycle ergometer at 70% of the oxygen consumption corresponding to the lactate threshold (the control for the intensity was oxygen consumption), while passive recoveries were performed with subjects at rest and seated on the cycle ergometer. Blood lactate concentration was measured 8 times during each recovery condition and lactate clearance was modeled over a negative exponential function using non-linear regression. Actual active recovery intensity was compared to the target intensity (one sample t-test) and passive recovery intensities were compared between environments (paired sample t-tests). Non-linear regression parameters (coefficients of the exponential decay of lactate; predicted resting lactates; predicted delta decreases in lactate) were compared between environments (linear mixed model analyses for repeated measures) separately for the active and passive recovery modes. Active recovery intensities did not differ significantly from the target oxygen consumption, whereas passive recovery resulted in a slightly lower oxygen consumption when performed while immersed in water rather than on land. The exponential decay of blood lactate was not significantly different in water- or land-based recoveries in either active or passive recovery conditions. In conclusion, water immersion at 29°C would not appear to be an effective practice for improving post-exercise lactate removal in either the active or passive recovery modes.

Evaluating the precision of passive sampling methods using PRCs in the water column

EPA Science Inventory

Low-Density polyethylene (LDPE) sheets are often used as passive samplers for aquatic environmental monitoring to measure the dissolved concentrations of hydrophobic organic contaminants (HOCs). HOCs that are freely dissolved in water (Cfree) will partition into the LDPE until a ...

Spatial analysis of volatile organic compounds in South Philadelphia using passive samplers

EPA Science Inventory

Select volatile organic compounds (VOCs) were measured in the vicinity of a petroleum refinery and related operations in South Philadelphia, Pennsylvania, USA, using passive air sampling and laboratory analysis methods. Two-week, time-integrated samplers were deployed at 17 sites...

Evaluating Cost when Selecting Performance Reference Compounds for the Environmental Deployment of Polyethylene Passive Samplers

EPA Science Inventory

A challenge in environmental passive sampling is determining when equilibrium is achieved between the sampler, target contaminants, and environmental phases. A common approach is the use of performance reference compounds (PRCs) to indicate degree of equilibrium. One logistical...

Association between passive smoking and mental distress in adult never-smokers: a cross-sectional study.

PubMed

Wang, Rui; Zhang, Peng; Lv, Xin; Gao, Chunshi; Song, Yuanyuan; Li, Zhijun; Yu, Yaqin; Li, Bo

2016-07-29

Many studies have suggested exposure to secondhand smoke (SHS) is a risk factor for various somatic diseases, but only few studies based on small sample size or specific groups have explored the association between passive smoking and mental distress. We performed this study to examine the relationship between passive smoking and mental distress in adult never-smokers of north-east China. Multistage, stratified random cluster sampling design was used in this cross-sectional study in 2012. A total of 12 978 never-smokers from Jilin, north-east China, were included. Data on passive smoking and baseline characteristics were collected by face-to-face interviews. The 12-item General Health Questionnaire (GHQ-12) was used to measure mental health status. Rao-Scott χ(2) tests were used to compare the prevalence between different groups; multivariable logistic regression was used to assess the association between passive smoking and mental distress, and Spearman rank analysis was employed to assess the correlation between passive smoking and GHQ-12 scores. The estimated prevalence of mental distress among never-smokers in Jilin province is 24.5%, and the estimated prevalence of passive smoking among the mental distressing group is 65.0%. After adjusting for gender, age, region, body mass index (BMI), occupation, marriage, education, drinking status and family monthly income per capita, passive smoking conferred a risk for mental distress (adjusted OR=1.26, 95% CI 1.13 to 1.40). A high proportion of adults, especially women, were passive smokers at home, but for men, passive smoking was more common at workplace. The more frequently participants exposed to SHS, the higher GHQ-12 scores they got. Passive smoking is an important risk factor for mental distress in never-smokers of Jilin province, which reminds Chinese government of increasing the awareness of public health and take measure to prevent SHS, especially with regard to SHS exposure at home and workplace. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Modeling the transport of organic chemicals between polyethylene passive samplers and water in finite and infinite bath conditions.

PubMed

Tcaciuc, A Patricia; Apell, Jennifer N; Gschwend, Philip M

2015-12-01

Understanding the transfer of chemicals between passive samplers and water is essential for their use as monitoring devices of organic contaminants in surface waters. By applying Fick's second law to diffusion through the polymer and an aqueous boundary layer, the authors derived a mathematical model for the uptake of chemicals into a passive sampler from water, in finite and infinite bath conditions. The finite bath model performed well when applied to laboratory observations of sorption into polyethylene (PE) sheets for various chemicals (polycyclic aromatic hydrocarbons, polychlorinated biphenyls [PCBs], and dichlorodiphenyltrichloroethane [DDT]) and at varying turbulence levels. The authors used the infinite bath model to infer fractional equilibration of PCB and DDT analytes in field-deployed PE, and the results were nearly identical to those obtained using the sampling rate model. However, further comparison of the model and the sampling rate model revealed that the exchange of chemicals was inconsistent with the sampling rate model for partially or fully membrane-controlled transfer, which would be expected in turbulent conditions or when targeting compounds with small polymer diffusivities and small partition coefficients (e.g., phenols, some pesticides, and others). The model can be applied to other polymers besides PE as well as other chemicals and in any transfer regime (membrane, mixed, or water boundary layer-controlled). Lastly, the authors illustrate practical applications of this model such as improving passive sampler design and understanding the kinetics of passive dosing experiments. © 2015 SETAC.

Rapid detection of single E. coli bacteria using a graphene-based field-effect transistor device.

PubMed

Thakur, Bhawana; Zhou, Guihua; Chang, Jingbo; Pu, Haihui; Jin, Bing; Sui, Xiaoyu; Yuan, Xiaochen; Yang, Ching-Hong; Magruder, Matthew; Chen, Junhong

2018-07-01

Contamination of surface and drinking water due to the presence of Escherichia coli bacteria is a major cause of water-borne disease outbreak. To address unmet challenges for practical pathogen detection in contaminated samples, we report fabrication of thermally reduced graphene oxide-based field-effect transistor (rGO FET) passivated with an ultrathin layer of Al 2 O 3 for real-time detection of E. coli bacteria. The sensor could detect a single E. coli cell within 50 s in a 1 µL sample volume. The ultrathin layer of Al 2 O 3 acted as a barrier between rGO and potential interferents present in the sample. E. coli specific antibodies anchored on gold nanoparticles acted as probes for selective capture of E. coli. The high density of negative charge on the surface of E. coli cells strongly modulates the concentration of majority charge carriers in the rGO monolayer, thereby allowing real-time monitoring of E. coli concentration in a given sample. With a low detection limit of single cell, the FET sensor had a linear range of 1-100 CFU in 1 µL volume of sample (i.e., 10 3 to 10 5 CFU/ mL). The biosensor with good selectivity and rapid detection was further successfully demonstrated for E. coli sensing in river water. The rGO-based FET sensor provides a low cost and label-free approach, and can be mass produced for detection of a broad spectrum of pathogens in water or other liquid media. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrical properties of spin coated ultrathin titanium oxide films on GaAs

NASA Astrophysics Data System (ADS)

Dutta, Shankar; Pal, Ramjay; Chatterjee, Ratnamala

2015-04-01

In recent years, ultrathin (<50 nm) metal oxide films have been being extensively studied as high-k dielectrics for future metal oxide semiconductor (MOS) technology. This paper discusses deposition of ultrathin TiO2 films (˜10 nm) on GaAs substrates (one sulfur-passivated, another unpassivated) by spin coating technique. The sulfur passivation is done to reduce the surface states of GaAs substrate. After annealing at 400 °C in a nitrogen environment, the TiO2 films are found to be polycrystalline in nature with rutile phase. The TiO2 films exhibit consistent grain size of 10-20 nm with thickness around 10-12 nm. Dielectric constants of the films are found to be 65.4 and 47.1 corresponding to S-passivated and unpassivated substrates, respectively. Corresponding threshold voltages of the MOS structures are measured to be -0.1 V to -0.3 V for the S-passivated and unpassivated samples, respectively. The S-passivated TiO2 film showed improved (lower) leakage current density (5.3 × 10-4 A cm-2 at 3 V) compared to the unpassivated film (1.8 × 10-3 A/cm2 at 3 V). Dielectric breakdown-field of the TiO2 films on S-passivated and unpassivated GaAs samples are found to be 8.4 MV cm-1 and 7.2 MV cm-1 respectively.

Emerging investigator series: development and application of polymeric electrospun nanofiber mats as equilibrium-passive sampler media for organic compounds.

PubMed

Qian, Jiajie; Jennings, Brandon; Cwiertny, David M; Martinez, Andres

2017-11-15

We fabricated a suite of polymeric electrospun nanofiber mats (ENMs) and investigated their performance as next-generation passive sampler media for environmental monitoring of organic compounds. Electrospinning of common polymers [e.g., polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polystyrene (PS), among others] yielded ENMs with reproducible control of nanofiber diameters (from 50 to 340 nm). The ENM performance was investigated initially with model hydrophilic (aniline and nitrobenzene) and hydrophobic (selected PCB congeners and dioxin) compounds, generally revealing fast chemical uptake into all of these ENMs, which was well described by a one compartment, first-order kinetic model. Typical times to reach 90% equilibrium (t 90% ) were ≤7 days under mixing conditions for all the ENMs and <0.5 days for the best performing materials under static (i.e., no mixing) conditions. Collectively, these short equilibrium timescales suggest that ENMs may be used in the field as an equilibrium-passive sampler, at least for our model compounds. Equilibrium partitioning coefficients (K ENM-W , L kg -1 ) averaged 2 and 4.7 log units for the hydrophilic and hydrophobic analytes, respectively. PAN, PMMA and PS were prioritized for additional studies because they exhibited not only the greatest capacity for simultaneous uptake of the entire model suite (log K ENM-W ∼1.5-6.2), but also fast uptake. For these optimized ENMs, the rates of uptake into PAN and PMMA were limited by aqueous phase diffusion to the nanofiber surface, and the rate-determining step for PS was analyte specific. Sorption isotherms also revealed that the environmental application of these optimized ENMs would occur within the linear uptake regime. We examined the ENM performance for the measurement of pore water concentrations from spiked soil and freshwater sediments. Soil and sediment studies not only yielded reproducible pore water concentrations and comparable values to other passive sampler materials, but also provided practical insights into ENM stability and fouling in such systems. Furthermore, fast uptake for a suite of structurally diverse hydrophilic and moderately hydrophobic compounds was obtained for PAN and PS, with t 90% ranging from 0.01 to 4 days with mixing and K ENM-W values ranging from 1.3 to 3.2 log units. Our findings show promise for the development and use of ENMs as equilibrium-passive samplers for a range of organic pollutants across soil/sediment and water systems.

Baseline element concentrations in soils and plants, Wattenmeer National Park, North and East Frisian Islands, Federal Republic of Germany

USGS Publications Warehouse

Severson, R.C.; Gough, L.P.; van den Boom, G.

1992-01-01

Baseline element concentrations are given for dune grass (Ammophilia arenaria), willow (Salix repens), moss (Hylocomium splendens) and associated surface soils. Baseline and variability data for pH, ash, Al, As, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Se, Sr, Th, Ti, V, Y, Yb, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration between five Frisian Islands are given for each of the sample media. In general, only a few elements in each media showed statistically significant differences between the islands sampled. The measured concentrations in all sample media exhibited ranges that cannot be attributed to anthropogenic additions of trace elements, with the possible exception of Hg and Pb in surface soils.Baseline element concentrations are given for dune grass (Ammophilia arenaria), willow (Salix repens), moss (Hylocomium splendens) and associated surface soils. Baseline and variability data for pH, ash, Al, As, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Se, Sr, Th, Ti, V, Y, Yb, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration between five Frisian Islands are given for each of the sample media. In general, only a few elements in each media showed statistically significant differences between the islands sampled. The measured concentrations in all sample media exhibited ranges that cannot be attributed to anthropogenic additions of trace elements, with the possible exception of Hg and Pb in surface soils.

Facility fence-line monitoring using passive samplers

EPA Science Inventory

In 2009, the U.S. EPA executed a year-long field study at a refinery in Corpus Christi, Texas, to evaluate the use of passive diffusive sampling technology for assessing time-averaged benzene concentrations at the facility fence line. The study utilized 14-day time-integrated Car...

Risk estimation and annual fluxes of emerging contaminants from a Scottish priority catchment to the estuary and North Sea.

PubMed

Zhang, Zulin; Lebleu, Melanie; Osprey, Mark; Kerr, Christine; Courtot, Estelle

2017-06-28

Emerging contaminants (ECs) such as endocrine-disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) attracted global concern during the last decades due to their potential adverse effects on humans and ecosystems. This work is the first study to assess the spatiotemporal changes, annual fluxes and ecological risk of ECs (4 EDCs and 6 PPCPs) by different monitoring strategies (spot and passive sampling) over 12 months in a Scottish priority catchment (River Ugie, Scotland, 335 km 2 ). Overall, the total concentration in water ranged from 1. This suggests that mitigation measures might need to be taken to reduce the input of emerging contaminants into the river and its adjacent estuary and sea.

Passivation of silicon surfaces by heat treatment in liquid water at 110 °C

NASA Astrophysics Data System (ADS)

Nakamura, Tomohiko; Sameshima, Toshiyuki; Hasumi, Masahiko; Mizuno, Tomohisa

2015-10-01

We report the effective passivation of silicon surfaces by heating single-crystalline silicon substrates in liquid water at 110 °C for 1 h. High photo-induced effective minority carrier lifetimes τeff were obtained ranging from 8.3 × 10-4 to 3.1 × 10-3 s and from 1.2 × 10-4 to 6.0 × 10-4 s for the n- and p-type samples, respectively, under 635 nm light illumination, while the τeff values of the initial bare samples were lower than 1.2 × 10-5 s. The heat treatment in liquid water at 110 °C for 1 h resulted in low surface recombination velocities ranging from 7 to 34 cm/s and from 49 to 250 cm/s for the n- and p-type samples, respectively. The photo-conductivity of the n-type sample was increased from 3.8 × 10-3 (initial) to 1.4 × 10-1 S/cm by the present heat treatment under air-mass (AM) 1.5 light illumination at 100 mW/cm2. The thickness of the passivation layer was estimated to be only approximately 0.7 nm. Metal-insulator-semiconductor-type solar cells were demonstrated with Al and Au metal formation on the passivated surface. Rectified current voltage and solar cell characteristics were observed. The open circuit voltages were obtained to be 0.52 and 0.49 V under AM 1.5 light illumination at 100 mW/cm2 for the n- and p-type samples, respectively.

Influence of Passive Joint Stiffness on Proprioceptive Acuity in Individuals With Functional Instability of the Ankle.

PubMed

Marinho, Hellen Veloso Rocha; Amaral, Giovanna Mendes; de Souza Moreira, Bruno; Araújo, Vanessa Lara; Souza, Thales Rezende; Ocarino, Juliana Melo; da Fonseca, Sérgio Teixeira

2017-12-01

Study Design Controlled laboratory study, cross-sectional. Background Deficits in ankle proprioceptive acuity have been reported in persons with functional instability of the ankle. Passive stiffness has been proposed as a possible mechanism underlying proprioceptive acuity. Objective To compare proprioceptive acuity and passive ankle stiffness in persons with and without functional ankle instability, and to assess the influence of passive joint stiffness on proprioceptive acuity in persons with functional ankle instability. Methods A sample of 18 subjects with and 18 without complaints of functional ankle instability following lateral ankle sprain participated. An isokinetic dynamometer was used to compare motion perception threshold, passive position sense, and passive ankle stiffness between groups. To evaluate the influence of passive stiffness on proprioceptive acuity, individuals in the lateral functional ankle instability group were divided into 2 subgroups: "high" and "low" passive ankle stiffness. Results The functional ankle instability group exhibited increased motion perception threshold when compared with the corresponding limb of the control group. Between-group differences were not found for passive position sense and passive ankle stiffness. Those in the functional ankle instability group with higher passive ankle stiffness had smaller motion perception thresholds than those with lower passive ankle stiffness. Conclusion Unlike motion perception threshold, passive position sense is not affected by the presence of functional ankle instability. Passive ankle stiffness appears to influence proprioceptive acuity in persons with functional ankle instability. J Orthop Sports Phys Ther 2017;47(12):899-905. Epub 7 Oct 2017. doi:10.2519/jospt.2017.7030.

Analysis of High Spatial, Temporal, and Directional Resolution Recordings of Biological Sounds in the Southern California Bight

DTIC Science & Technology

2013-09-30

transiting whales in the Southern California Bight, b) the use of passive underwater acoustic techniques for improved habitat assessment in biologically...sensitive areas and improved ecosystem modeling, and c) the application of the physics of excitable media to numerical modeling of biological choruses...was on the potential impact of man-made sounds on the calling behavior of transiting humpback whales in the Southern California Bight. The main

Reconfigurable Optical Elements Based on Single and Coupled Microdisk Resonators with Quantum DOT Active Media

DTIC Science & Technology

2012-06-29

of active-passive integrated polymer waveguides. The active waveguides consist of CdSe quantum dots dispersed in SU8 . Bottom panel shows CCD images...successfully demonstrated (i) incorporation of CdSe QDs into polymer and dielectric host and realization of devices such as active waveguides, microdisk...the significant outcomes of the program: • Successful incorporation of CdSe QDs into polymer and dielectric host and realization of devices such as

A sonotrode for electroanalysis: the determination of copper in passivating media.

PubMed

Floate, Simon; Hardcastle, Joanna L; Cordemans, Eric; Compton, Richard G

2002-08-01

A sonotrode consisting of a disc shaped glassy carbon electrode attached to a quartz rod and inserted into a drilled ultrasonic probe tip has been designed and used as a novel alternative to the traditional 'face on' cell arrangement where an ultrasonic micro-tip probe is placed opposite a glassy carbon working electrode. The 'single probe' arrangement is both convenient and optimised for electroanalysis. We first report how under ultrasonic agitation of the sonotrode the mass transport to the electrode surface is enhanced compared to that observed under silent conditions and also how the sonotrode cell geometry compares with the well-established 'face on' cell geometry for cobalt electrodeposition. Second, we will show that the new sonotrode can be used in the application for the determination of copper in a series of fouling media in which conventional silent electroanalysis fails. The passivation of the electrodes surface by surfactant species can be overcome by cavitationally induced streaming and/or erosion at the sonotrode surface with recoveries of 100% and 93.8% achieved at 42 W cm-2 for Triton X-100 and sodium dodecyl sulfate (SDS), respectively. Other data indicates that the sonotrode can be successfully employed for the detection of copper in beer (Marston's bitter), a system known to be complex and highly electrode fouling and difficult to analyse using standard, silent electroanalytical techniques.

College Women's Health

MedlinePlus

... the College Women's Social Media Kit! College Women's Social Media Toolkit Use the Social Media Toolkit to share health tips with your campus ... toolkit includes resources for young women including sample social media messages, flyers and blogs posts. NEW Social Media ...

Bomb-Pulse Chlorine-36 At The Proposed Yucca Mountain Repository Horizon: An Investigation Of Previous Conflicting Results And Collection Of New Data

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

J. Cizdziel

2006-07-28

Previous studies by scientists at Los Alamos National Laboratory (LANL) found elevated ratios of chlorine-36 to total chloride ({sup 36}Cl/Cl) in samples of rock collected from the Exploratory Studies Facility (ESF) and the Enhanced Characterization of the Repository Block (ECRB) at Yucca Mountain as the tunnels were excavated. The data were interpreted as an indication that fluids containing 'bomb-pulse' {sup 36}Cl reached the repository horizon in the {approx}50 years since the peak period of above-ground nuclear testing. Moreover, the data support the concept that so-called fast pathways for infiltration not only exist but are active, possibly through a combination ofmore » porous media, faults and/or other geologic features. Due to the significance of {sup 36}Cl data to conceptual models of unsaturated zone flow and transport, the United States Geological Survey (USGS) was requested by the Department of Energy (DOE) to design and implement a study to validate the LANL findings. The USGS chose to drill new boreholes at select locations across zones where bomb-pulse ratios had previously been identified. The drill cores were analyzed at Lawrence Livermore National Laboratory (LLNL) for {sup 36}Cl/Cl using both active and passive leaches, with the USGS/LLNL concluding that the active leach extracted too much rock-Cl and the passive leach did not show bomb-pulse ratios. Because consensus was not reached between the USGS/LLNL and LANL on several fundamental points, including the conceptual strategy for sampling, interpretation and use of tritium ({sup 3}H) data, and the importance and interpretation of blanks, in addition to the presence or absence of bomb-pulse {sup 36}Cl, an evaluation by an independent entity, the University of Nevada, Las Vegas (UNLV), using new samples was initiated. This report is the result of that study. The overall objectives of the UNLV study were to investigate the source or sources of the conflicting results from the previous validation study, and to obtain additional data to determine whether or not there are bomb-pulse isotopes at the repository horizon. To that en4 we have engaged in discussions with previous investigators, reviewed reports, and analyzed archived samples. We have also collected new samples of rock from the ESF, soil profiles from the surface of Yucca Mountain, and opportunistic samples of seep water from inside the south ramp of the ESF.« less

Experimental Modification of Rat Pituitary Prolactin Cell Function During and After Spaceflight

NASA Technical Reports Server (NTRS)

Hymer, W. C.; Salada, T.; Avery, L.; Grindeland, R. E.

1996-01-01

Experimental modification of rat pituitary prolactin cell function during and after spaceflight. This study was done to evaluate the effects of microgravity on prolactin (PRL) cells of the male rat pituitary gland. We used the identical passive closed-vial cell culture system that was described for the culture of growth hormone cells (W C. Hymer, R. E. Grindeland, T. Salada, P. Nye, E. Grossman, and R Lane). After an 8-day spaceflight, all flight media (containing released PRL), as well as extracts (containing intracellular PRL), contained significantly lower amounts of immunoreactive PRL than their corresponding ground control samples. On the other hand, these same samples, when assessed for their biological activities by two different in vitro lymphocyte assays, yielded disparate results that may reflect posttranslational modifications to the hormone molecule. Other data showed that: (1) the apparent molecular weights of released PRL molecules were not altered by microgravity; but (2) the region from which the PRL cells came (dorsal or ventral) made a significant difference in the amount and activity of PRL released from the flight cells. Because there is much current interest in the role that PRL may play in the regulation of the immune system and because changes in both cellular and humoral immunity accompany spaceflight, this study could help define future microgravity research in this area.

The 4-8 GHz Microwave Active and Passive Spectrometer (MAPS). Volume 1: Radar section

NASA Technical Reports Server (NTRS)

Ulaby, F. T.

1973-01-01

The performance characteristics of the radar section of the prototype 4-8 GHz Microwave Active and Passive Spectrometer system are reported. Active and passive spectral responses were measured of natural, cultivated, and human-made surfaces over the 4-18 GHz region of frequencies for look angles between zero and 70 degrees and for all possible linear polarization combinations. Soil and plant samples were collected to measure their dielectric properties and moisture content. The FORTRAN program for area calculation is provided.

Evaluation of Urban Air Quality By Passive Sampling Technique

NASA Astrophysics Data System (ADS)

Nunes, T. V.; Miranda, A. I.; Duarte, S.; Lima, M. J.

Aveiro is a flat small city in the centre of Portugal, close to the Atlantic coast. In the last two decades an intensive development of demographic, traffic and industry growth in the region was observed which was reflected on the air quality degrada- tion. In order to evaluate the urban air quality in Aveiro, a field-monitoring network by passive sampling with high space resolution was implemented. Twenty-four field places were distributed in a area of 3x3 Km2 and ozone and NO2 concentrations were measured. The site distribution density was higher in the centre, 250x250 m2 than in periphery where a 500x500 m2 grid was used. The selection of field places took into consideration the choice criteria recommendation by United Kingdom environmental authorities, and three tubes and a blank tube for each pollutant were used at each site. The sampling system was mounted at 3m from the ground usually profiting the street lampposts. Concerning NO2 acrylic tubes were used with 85 mm of length and an in- ternal diameter of 12mm, where in one of the extremities three steel grids impregnated with a solution of TEA were placed and fixed with a polyethylene end cup (Heal et al., 1999); PFA Teflon tube with 53 mm of length and 9 mm of internal diameter and three impregnated glass filters impregnated with DPE solution fixed by a teflon end cup was used for ozone sampling (Monn and Hargartner, 1990). The passive sampling method for ozone and nitrogen dioxide was compared with continuous measurements, but the amount of measurements wasnSt enough for an accurate calibration and validation of the method. Although this constraint the field observations (June to August 2001) for these two pollutants assign interesting information about the air quality in the urban area. A krigger method of interpolation (Surfer- Golden Software-2000) was applied to field data to obtain isolines distribution of NO2 and ozone concentration for the studied area. Even the used passive sampling method has many limitations it is possi- ble to say that the NO2 concentrations were strictly related with traffic intensity and in the centre 3 to 10 times higher values were observed than the incoming air to the city; on the contrary the ozone seems to be consumed where we observe the highest NO2 concentrations. Heal, M. R.; O'Donoghue, M. A. and Cape, J. N., Overestimation of Urban Nitrogen Dioxide by Passive Sampling Tubes: a comparative exposure and model study, Atmo- spheric Environment, Vol 33, pp 513-524, 1999 Monn, Ch., Hangartner, M., Passive Sampling for Ozone, J. of Air and Waste Management Association, Vol. 40, Nz 3, 1990

Wallboard with latent heat storage for passive solar applications

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

Kedl, R.J.

1991-05-01

Conventional wallboard impregnated with octadecane paraffin is being developed as a building material with latent heat storage for passive solar and other applications. Impregnation was accomplished simply by soaking the wallboard in molten wax. Concentrations of wax in the combined product as high as 35% by weight can be achieved. Scale-up of the soaking process, from small laboratory samples to full-sized 4- by 8-ft sheets, has been successfully accomplished. The required construction properties of wallboard are maintained after impregnation, that is, it can be painted and spackled. Long-term, high-temperature exposure tests and thermal cycling tests showed no tendency of themore » paraffin to migrate within the wallboard, and there was no deterioration of thermal energy storage capacity. In support of this concept, a computer model was developed to handle thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions and also by comparison with temperatures measured in wallboard during an experimentally generated thermal transient. Agreement between the model and known solution was excellent. Agreement between the model and thermal transient was good, only after the model was modified to allow the PCM to melt over a temperature range, rather than at a specific melting point. When the melting characteristics of the PCM, as determined from a differential scanning calorimeter plot, were used in the model, agreement between the model and transient data was very good. 11 refs., 25 figs., 2 tabs.« less

Evaluating the precision of passive sampling methods using PRCs in the water column.

EPA Science Inventory

To assess these models, four different thicknesses of low-density polyethylene (LDPE) passive samplers were co-deployed for 28 days in the water column at three sites in New Bedford Harbor, MA, USA. Each sampler was pre-loaded with six PCB performance reference compounds (PRCs) t...

Assessing cellulolysis in passive treatment systems for mine drainage: a modified enzyme assay.

PubMed

McDonald, Corina M; Gould, W Douglas; Lindsay, Matthew B J; Blowes, David W; Ptacek, Carol J; Condon, Peter D

2013-01-01

A modified cellulase enzyme assay was developed to monitor organic matter degradation in passive treatment systems for mine drainage. This fluorogenic substrate method facilitates assessment of exo-(1,4)-β-D-glucanase, endo-(1,4)-β-D-glucanase, and β-glucosidase, which compose an important cellulase enzyme system. The modified method was developed and refined using samples of organic carbon-amended mine tailings from field experiments where sulfate reduction was induced as a strategy for managing water quality. Sample masses (3 g) and the number of replicates ( ≥ 3) were optimized. Matrix interferences within these metal-rich samples were found to be insignificant. Application of this modified cellulase assay method provided insight into the availability and degradation of organic carbon within the amended tailings. Results of this study indicate that cellulase enzyme assays can be applied to passive treatment systems for mine drainage, which commonly contain elevated concentrations of metals. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Development of a passive air sampler to measure airborne organophosphorus pesticides and oxygen analogs in an agricultural community.

PubMed

Armstrong, Jenna L; Yost, Michael G; Fenske, Richard A

2014-09-01

Organophosphorus pesticides are some of the most widely used insecticides in the US, and spray drift may result in human exposures. We investigate sampling methodologies using the polyurethane foam passive air sampling device to measure cumulative monthly airborne concentrations of OP pesticides chlorpyrifos, azinphos-methyl, and oxygen analogs. Passive sampling rates (m(3)d(-1)) were determined using calculations using chemical properties, loss of depuration compounds, and calibration with side-by-side active air sampling in a dynamic laboratory exposure chamber and in the field. The effects of temperature, relative humidity, and wind velocity on outdoor sampling rates were examined at 23 sites in Yakima Valley, Washington. Indoor sampling rates were significantly lower than outdoors. Outdoor rates significantly increased with average wind velocity, with high rates (>4m(3)d(-1)) observed above 8ms(-1). In exposure chamber studies, very little oxygen analog was observed on the PUF-PAS, yet substantial amounts chlorpyrifos-oxon and azinphos methyl oxon were measured in outdoor samples. PUF-PAS is a practical and useful alternative to AAS because it results in little artificial transformation to the oxygen analog during sampling, it provides cumulative exposure estimates, and the measured sampling rates were comparable to rates for other SVOCs. It is ideal for community based participatory research due to low subject burden and simple deployment in remote areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient energy transmission and amplification in the cochlea relies on frequency-dependent material properties of the tectorial membrane

NASA Astrophysics Data System (ADS)

Jones, Gareth P.; Lukashkina, Victoria A.; Russell, Ian J.; Elliott, Stephen J.; Lukashkin, Andrei N.

2015-12-01

The remarkable sensitivity, frequency selectivity, and dynamic range of the mammalian cochlea relies on longitudinal transmission of minuscule amounts of energy as passive, pressure-driven, basilar membrane (BM) traveling waves which are actively amplified at frequency-specific locations. Transmission of passive waves through viscous tissue situated in a viscous media is not an easy task. Here we describe mechanical properties of the tectorial membrane (TM) which facilitate this transmission. From mechanical measurements of isolated segments of the TM, we discovered that the stiffness of the TM is reduced when it is mechanically stimulated at physiologically relevant magnitudes and at frequencies below their frequency place in the cochlea. The reduction in stiffness functionally uncouples the TM from the organ of Corti, thereby minimizing energy losses during passive traveling wave propagation. Stiffening and decreased viscosity of the TM at high stimulus frequencies can potentially facilitate active amplification, especially in the high-frequency, basal turn, where energy loss due to internal friction within the TM is less than in the apex. This prediction is confirmed by neural recordings from several frequency regions of the cochlea.

Cost-effective parallel optical interconnection module based on fully passive-alignment process

NASA Astrophysics Data System (ADS)

Son, Dong Hoon; Heo, Young Soon; Park, Hyoung-Jun; Kang, Hyun Seo; Kim, Sung Chang

2017-11-01

In optical interconnection technology, high-speed and large data transitions with low error rate and cost reduction are key issues for the upcoming 8K media era. The researchers present notable types of optical manufacturing structures of a four-channel parallel optical module by fully passive alignment, which are able to reduce manufacturing time and cost. Each of the components, such as vertical-cavity surface laser/positive-intrinsic negative-photodiode array, microlens array, fiber array, and receiver (RX)/transmitter (TX) integrated circuit, is integrated successfully using flip-chip bonding, die bonding, and passive alignment with a microscope. Clear eye diagrams are obtained by 25.78-Gb/s (for TX) and 25.7-Gb/s (for RX) nonreturn-to-zero signals of pseudorandom binary sequence with a pattern length of 231 to 1. The measured responsivity and minimum sensitivity of the RX are about 0.5 A/W and ≤-6.5 dBm at a bit error rate (BER) of 10-12, respectively. The optical power margin at a BER of 10-12 is 7.5 dB, and cross talk by the adjacent channel is ≤1 dB.

Suitability of Commercial Transport Media for Biological Pathogens under Nonideal Conditions

PubMed Central

Hubbard, Kyle; Pellar, Gregory; Emanuel, Peter

2011-01-01

There is extensive data to support the use of commercial transport media as a stabilizer for known clinical samples; however, there is little information to support their use outside of controlled conditions specified by the manufacturer. Furthermore, there is no data to determine the suitability of said media for biological pathogens, specifically those of interest to the US military. This study evaluates commercial off-the-shelf (COTS) transport media based on sample recovery, viability, and quality of nucleic acids and peptides for nonpathogenic strains of Bacillus anthracis, Yersinia pestis, and Venezuelan equine encephalitis virus, in addition to ricin toxin. Samples were stored in COTS, PBST, or no media at various temperatures over an extended test period. The results demonstrate that COTS media, although sufficient for the preservation of nucleic acid and proteinaceous material, are not capable of maintaining an accurate representation of biothreat agents at the time of collection. PMID:22121364

Passive ultrasonics using sub-Nyquist sampling of high-frequency thermal-mechanical noise.

PubMed

Sabra, Karim G; Romberg, Justin; Lani, Shane; Degertekin, F Levent

2014-06-01

Monolithic integration of capacitive micromachined ultrasonic transducer arrays with low noise complementary metal oxide semiconductor electronics minimizes interconnect parasitics thus allowing the measurement of thermal-mechanical (TM) noise. This enables passive ultrasonics based on cross-correlations of diffuse TM noise to extract coherent ultrasonic waves propagating between receivers. However, synchronous recording of high-frequency TM noise puts stringent requirements on the analog to digital converter's sampling rate. To alleviate this restriction, high-frequency TM noise cross-correlations (12-25 MHz) were estimated instead using compressed measurements of TM noise which could be digitized at a sampling frequency lower than the Nyquist frequency.

Understanding bioavailability and toxicity of sediment-associated contaminants by combining passive sampling with in vitro bioassays in an urban river catchment.

PubMed

Li, Juan-Ying; Tang, Janet Yat Man; Jin, Ling; Escher, Beate I

2013-12-01

Bioavailable and bioaccessible fractions of sediment-associated contaminants are considered as better dose metrics for sediment-quality assessment than total concentrations. The authors applied exhaustive solvent extraction and nondepletive equilibrium sampling techniques to sediment samples collected along the Brisbane River in South East Queensland, Australia, which range from pristine environments to urban and industry-impacted areas. The wide range of chemicals expected prevents comprehensive chemical analysis, but a battery of cell-based bioassays sheds light on mixture effects of chemicals in relation to various modes of toxic action. Toxic effects were expressed as bioanalytical equivalent concentrations (BEQs) normalized to the organic carbon content of each sediment sample. Bioanalytical equivalent concentrations from exhaustive extraction agreed fairly well with values estimated from polydimethylsiloxane passive sampling extracts via the constant organic carbon to polydimethylsiloxane partition coefficient. Agreement was best for bioassays indicative of photosynthesis inhibition and oxidative stress response and discrepancy within a factor of 3 for the induction of the aryl hydrocarbon receptor. For nonspecific cytotoxicity, BEQ from exhaustive extraction were 1 order of magnitude higher than values from equilibrium sampling, possibly because of coextraction of bioactive natural organic matter that led to an overestimation of toxicity in the exhaustive extracts, which suggests that passive sampling is better suited in combination with bioanalytical assessment than exhaustive extraction. © 2013 SETAC.

Ion exchange membranes as novel passive sampling material for organic ions: application for the determination of freely dissolved concentrations.

PubMed

Oemisch, Luise; Goss, Kai-Uwe; Endo, Satoshi

2014-11-28

Many studies in pharmacology, toxicology and environmental science require a method for determining the freely dissolved concentration of a target substance. A recently developed tool for this purpose is equilibrium passive sampling with polymeric materials. However, this method has rarely been applied to ionic organic substances, primarily due to limited availability of convenient sorption materials. This study introduces ion exchange membranes (IEMs) as a novel passive sampling material for organic ions. The partitioning of 4-ethylbenzene-1-sulfonate, 2,4-dichlorophenoxyacetic acid and pentachlorophenol to one anion exchange membrane (FAS) and of difenzoquat, nicotine and verapamil to one cation exchange membrane (FKS) was investigated. All test substances exhibited a sufficiently high affinity for the respective IEM with logarithmic IEM-water partition coefficients >2.3. Sorption equilibrium was established quickly, within several hours for the FAS membrane and within 1-3 days for the FKS membrane. For permanently charged substances the partitioning to the IEMs was independent of pH, but was influenced by the salt composition of the test solution. For all test substances sorption to IEM was dependent on the substance concentration. Bovine serum albumin-water partition coefficients determined by passive sampling with IEMs agree well with those determined by the conventional dialysis method. The results of this study indicate that IEMs exhibit the potential to measure freely dissolved concentrations of organic ions in a simple and time-saving manner. Copyright © 2014 Elsevier B.V. All rights reserved.

Effectiveness analyses may underestimate protection of infants after group C meningococcal immunization.

PubMed

Vu, David M; Kelly, Dominic; Heath, Paul T; McCarthy, Noel D; Pollard, Andrew J; Granoff, Dan M

2006-07-15

Group C meningococcal conjugate-vaccine effectiveness in the United Kingdom declines from ~90% in the first year to 0% between 1 and 4 years after immunization in infants immunized at 2, 3, and 4 months of age and to 61% in toddlers given a single dose. Confidence intervals are wide, and the extent of protection is uncertain. Serum samples were obtained from children 3-5 years of age who were participants in a preschool booster-vaccine trial. Serum bactericidal activity was measured with human complement. Group C anticapsular antibody concentrations were measured by a radioantigen binding assay. Passive protection was analyzed in an infant rat bacteremia model. Serum samples from UK children who had been immunized 2-3 years earlier as infants or toddlers had higher levels of radioantigen binding, bactericidal activity, and passive protection than did historical control serum samples from unimmunized children (P<.05). A higher proportion of children immunized as infants had serum bactericidal activity titers > or =1 : 4 (considered to be protective) than those immunized as toddlers (61% vs. 24%; P<.01), but there were no significant differences in the proportion of serum samples conferring passive protection (50% and 41%, respectively; P=.4). We found no evidence of lower immunity in children immunized as infants than as toddlers. On the basis of serum bactericidal activity and/or passive protection, 40%-50% of both age groups are protected at 2-3 years after immunization, which was significantly greater than in unimmunized historical controls (<5%).

NiTi shape memory alloys treated by plasma-polymerized tetrafluoroethylene. A physicochemical and electrochemical characterization.

PubMed

Yahia, L H; Lombardi, S; Piron, D; Klemberg-Sapieha, J E; Wertheimer, M R

NiTi alloy specimens were plasma cleaned and then coated with a thin film of plasma-polymerized tetrafluoroethylene (TFE) in a Radio-Frequency reactor. The corrosion protection provided by these films was studied by potentiodynamic tests performed in Hank's physiological solution. Surface properties which determine biocompatibility were characterized by X-ray photoelectron spectroscopy (XPS). The results showed that the surface of untreated NiTi was mostly composed by oxygen, carbon, titanium oxide (TiO2) with traces of nickel oxides (NiO and Ni2O3) and metallic Ni. The passivity of untreated NiTi was found to be unstable in the simulated human body media. After plasma treatment, the NiTi surface contained only carbon and fluor. The plasma-polymerized thin film was found to stabilize the NiTi passivity and to increase its pitting potential. This treatment provides a good protection against dissolution of nickel from NiTi alloys.

Turbulent transport of He II in active and passive phase separators using slit devices and porous media

NASA Technical Reports Server (NTRS)

Yuan, S. W. K.; Lee, J. M.; Frederking, T. H. K.

1988-01-01

The turbulent transport mode of vapor liquid phase separators (VLPS) for He II has been investigated comparing passive porous plug separators with active phase separators (APS) using slits of variable flow paths within a common frame of reference. It is concluded that the basic transport regimes in both devices are identical. An integrated Gorter-Mellink (1949) equation, found previously to predict VLPS results of porous plugs, is employed to analyze APS data published in the literature. It is found that the Gorter-Mellink flow rate parameter for 9-micron and 14-micron APS slit widths are relatively independent of the slit width, having a rate constant of about 9 + or - 10 percent. This agrees with the early heat flow results for He II entropy transport at zero net mass flow in wide capillaries and slits.

Romantic relationship stages and social networking sites: uncertainty reduction strategies and perceived relational norms on facebook.

PubMed

Fox, Jesse; Anderegg, Courtney

2014-11-01

Due to their pervasiveness and unique affordances, social media play a distinct role in the development of modern romantic relationships. This study examines how a social networking site is used for information seeking about a potential or current romantic partner. In a survey, Facebook users (N=517) were presented with Facebook behaviors categorized as passive (e.g., reading a partner's profile), active (e.g., "friending" a common third party), or interactive (e.g., commenting on the partner's wall) uncertainty reduction strategies. Participants reported how normative they perceived these behaviors to be during four possible stages of relationship development (before meeting face-to-face, after meeting face-to-face, casual dating, and exclusive dating). Results indicated that as relationships progress, perceived norms for these behaviors change. Sex differences were also observed, as women perceived passive and interactive strategies as more normative than men during certain relationship stages.

Using hydrogels in microscopy: A tutorial.

PubMed

Flood, Peter; Page, Henry; Reynaud, Emmanuel G

2016-05-01

Sample preparation for microscopy is a crucial step to ensure the best experimental outcome. It often requires the use of specific mounting media that have to be tailored to not just the sample but the chosen microscopy technique. The media must not damage the sample or impair the optical path, and may also have to support the correct physiological function/development of the sample. For decades, researchers have used embedding media such as hydrogels to maintain samples in place. Their ease of use and transparency has promoted them as mainstream mounting media. However, they are not as straightforward to implement as assumed. They can contain contaminants, generate forces on the sample, have complex diffusion and structural properties that are influenced by multiple factors and are generally not designed for microscopy in mind. This short review will discuss the advantages and disadvantages of using hydrogels for microscopy sample preparation and highlight some of the less obvious problems associated with the area. Copyright © 2016 Elsevier Ltd. All rights reserved.

A passive ozone sampler based on a reaction with nitrite.

PubMed

Koutrakis, P; Wolfson, J M; Bunyaviroch, A; Froehlich, S

1994-02-01

Standard ozone monitoring techniques utilize large, heavy, and expensive instruments that are not easily adapted for personal or microenvironmental monitoring. For large-scale monitoring projects that examine spatial variations of a pollutant and human exposure assessments, passive sampling devices can provide the methodology to meet monitoring and statistical goals. Recently, we developed a coated filter for ozone collection that we used in a commercially available passive sampling device. Successful preliminary results merited further validation tests, which are presented in this report. The passive ozone sampler used in field and laboratory experiments consists of a badge clip supporting a barrel-shaped body that contains two coated glass fiber filters. The principle component of the coating is nitrite ion, which in the presence of ozone is oxidized to nitrate ion on the filter medium (NO2- + O3 produces NO3- + O2). After sample collection, the filters were extracted with ultrapure water and analyzed for nitrate ion by ion chromatography. The results from laboratory and field validation tests indicated excellent agreement between the passive method and standard ozone monitoring techniques. We determined that relative humidity (ranging from 10% to 80%) and temperature (ranging from 0 degrees C to 40 degrees C) at typical ambient ozone levels (40 to 100 parts per billion) do not influence sampler performance. Face velocity and sampler orientation with respect to wind direction were found to affect the sampler's collection rate of ozone. Using a protective cup, which acts as both a wind screen and a rain cover, we were able to obtain a constant collection rate over a wide range of wind speeds.

Theories of otitis media pathogenesis, with a focus on Indigenous children.

PubMed

Wiertsema, Selma P; Leach, Amanda J

2009-11-02

Otitis media is a common childhood illness associated with hearing loss, social disadvantage and medical costs. Prevalence and severity are high among Indigenous children. Respiratory bacterial and viral pathogens ascend the eustachian tube from the nasopharynx to the middle ear, causing inflammation, fluid accumulation, and bulging of the tympanic membrane, with or without pain. Among Australian Indigenous children, ear disease commences earlier in life, and involves multiple strains of bacterial pathogens at high density that persist longer. Persistent nasal discharge, overcrowded living conditions (particularly exposure to many children) and poor facilities for washing children perpetuate a vicious cycle of transmission and infection. Risk factors include environmental tobacco smoke, season, lack of breastfeeding, younger age and immature immune system, and possibly genetic factors. The innate immune system is a critical first response to infection, particularly as passive maternal antibodies decline and during the maturation of the infant adaptive immune response. The relative contributions of innate factors to protection from otitis media are currently not well understood. A diversity of antibodies that target strain-specific and conserved antigens are generated in response to natural exposure to otitis media pathogens (or to vaccines). Deficiencies in these antibodies may explain susceptibility to recurrent infections. Incremental contributions from all these elements are likely to be important in otitis media susceptibility versus protection. Effective medical and social strategies to prevent early age of onset are urgently needed.

Characterization and Application of Passive Samplers for Monitoring of Pesticides in Water.

PubMed

Ahrens, Lutz; Daneshvar, Atlasi; Lau, Anna E; Kreuger, Jenny

2016-08-03

Five different water passive samplers were calibrated under laboratory conditions for measurement of 124 legacy and current used pesticides. This study provides a protocol for the passive sampler preparation, calibration, extraction method and instrumental analysis. Sampling rates (RS) and passive sampler-water partition coefficients (KPW) were calculated for silicone rubber, polar organic chemical integrative sampler POCIS-A, POCIS-B, SDB-RPS and C18 disk. The uptake of the selected compounds depended on their physicochemical properties, i.e., silicone rubber showed a better uptake for more hydrophobic compounds (log octanol-water partition coefficient (KOW) > 5.3), whereas POCIS-A, POCIS-B and SDB-RPS disk were more suitable for hydrophilic compounds (log KOW < 0.70).

High-resolution passive sampling of dissolved methane in the water column of lakes in Greenland

NASA Astrophysics Data System (ADS)

Goldman, A. E.; Cadieux, S. B.; White, J. R.; Pratt, L. M.

2013-12-01

Arctic lakes are important participants in the global carbon cycle, releasing methane in a warming climate and contributing to a positive feedback to climate change. In order to yield detailed methane budgets and understand the implications of warming on methane dynamics, high-resolution profiles revealing methane behavior within the water column need to be obtained. Single day sampling using disruptive techniques has the potential to result in biases. In order to obtain high-resolution, undisturbed profiles of methane concentration and isotopic composition, this study evaluates a passive sampling method over a multi-day equilibration period. Selected for this study were two small lakes (<1km2) within a narrow valley stretching between Russells Glacier and Søndre Strømfjord in southwestern Greenland, which are part of an ongoing study of a series of seven lakes. Commercially available, 150 mL, polyethylene Passive Diffusion Bags (PDB's) were deployed in July 2013 for five days at 0.5-meter depth intervals. PDB samples were compared to samples collected with a submersible, electric pump taken immediately before PBD deployment. Preliminary CH4 concentrations and carbon isotopes for one lake were obtained in the field using a Los Gatos Research Methane Carbon Isotope Analyzer. PDB sampling and pump sampling resulted in statistically similar concentrations (R2=0.89), ranging from 0.85 to 135 uM from PDB and 0.74 to 143 uM from pump sampling. In anoxic waters of the lake, where concentrations were high enough to yield robust isotopic results on the LGR MCIA, δ13C were also similar between the two methods, yielding -73‰ from PDB and -74‰ from pump sampling. Further investigation will produce results for a second lake and methane carbon and hydrogen isotopic composition for both lakes. Preliminary results for this passive sampling method are promising. We envision the use of this technique in future studies of dissolved methane and expect that it will provide a more finely resolved vertical profile, allowing for a more complete understanding of lacustrine methane dynamics.

Passive Facebook usage undermines affective well-being: Experimental and longitudinal evidence.

PubMed

Verduyn, Philippe; Lee, David Seungjae; Park, Jiyoung; Shablack, Holly; Orvell, Ariana; Bayer, Joseph; Ybarra, Oscar; Jonides, John; Kross, Ethan

2015-04-01

Prior research indicates that Facebook usage predicts declines in subjective well-being over time. How does this come about? We examined this issue in 2 studies using experimental and field methods. In Study 1, cueing people in the laboratory to use Facebook passively (rather than actively) led to declines in affective well-being over time. Study 2 replicated these findings in the field using experience-sampling techniques. It also demonstrated how passive Facebook usage leads to declines in affective well-being: by increasing envy. Critically, the relationship between passive Facebook usage and changes in affective well-being remained significant when controlling for active Facebook use, non-Facebook online social network usage, and direct social interactions, highlighting the specificity of this result. These findings demonstrate that passive Facebook usage undermines affective well-being. (c) 2015 APA, all rights reserved).

A XPS Study of the Passivity of Stainless Steels Influenced by Sulfate-Reducing Bacteria.

NASA Astrophysics Data System (ADS)

Chen, Guocun

The influence of sulfate-reducing bacteria (SRB) on the passivity of type 304 and 317L stainless steels (SS) was investigated by x-ray photoelectron spectroscopy (XPS), microbiological and electrochemical techniques. Samples were exposed to SRB, and then the resultant surfaces were analyzed by XPS, and the corrosion resistance by potentiodynamic polarization in deaerated 0.1 M HCl. To further understand their passivity, the SRB-exposed samples were analyzed by XPS after potentiostatic polarization at a passive potential in the hydrochloric solution. The characterization was performed under two surface conditions: unrinsed and rinsed by deaerated alcohol and deionized water. Comparisons were made with control samples immersed in uninoculated medium. SRB caused a severe loss of the passivity of 304 SS through sulfide formation and possible additional activation to form hexavalent chromium. The sulfides included FeS, FeS_2, Cr_2S _3, NiS and possibly Fe_ {rm 1-x}S. The interaction took place nonuniformly, resulting in undercutting of the passive film and preferential hydration of inner surface layers. The bacterial activation of the Cr^{6+ }^ecies was magnified by subsequent potentiostatic polarization. In contrast, 317L SS exhibited a limited passivity. The sulfides were formed mainly in the outer layers. Although Cr^{6+}^ecies were observed after the exposure, they were dissolved upon polarization. Since 317L SS has a higher Mo content, its higher passivity was ascribed to Mo existing as molybdate on the surface and Mo^{5+} species in the biofilm. Consequently, the interaction of SRB with Mo was studied. It was observed that molybdate could be retained on the surfaces of Mo coupons by corrosion products. In the presence of SRB, however, a considerable portion of the molybdate interacted with intermediate sulfur -containing proteins, forming Mo(V)-S complexes and reducing bacterial growth and sulfate reduction. The limited insolubility of the Mo(V)-S complexes in 0.1 M HCl provided a certain protection so that the pitting potential of the SRB-exposed Mo coupons was not considerably decreased. The interaction of the sulfur-containing proteins with Mo also provided mechanistic information about the adhesion of biofilm to Mo-bearing steels. Additionally, the interactions of SRB with other alloying elements, Cr and Ni, were investigated.

Chromogenic culture media or rapid immunochromatographic test: Which is better for detecting Klebsiella pneumoniae that produce OXA-48 and can they be used in blood and urine specimens.

PubMed

Genc, Ozlem; Aksu, Evrim

2018-05-01

Our goal was to compare a rapid test (OXA-48K-SeT) and four different chromogenic media (CHROMagar KPC, CHROMagar mSuperCARBA, ChromID Carba and ChromID OXA-48) for the detection of OXA-48 producing Klebsiella pneumoniae isolates and spiked urine/blood samples with these bacteria. In total 100 K.pneumoniae isolates, including 60 OXA-48 positive, 15 other carbapenemase producing, 15 Extended spectrum betalactamases (ESBL) positive and 10 carbapenem sensitive K.pneumoniae were included in the study. After all samples were inoculated into all chromogenic media, temocillin discs were placed onto the media. OXA-48K-SeT was studied according to the manufacturer's instructions and the lower detection limit was determined. Sensitivities and specificities of all chromogenic media and rapid test were detected as 100%. All of the OXA-48 producers were found resistant to temocillin on all chromogenic media. The lower detection limit of the rapid assay was determined as 10 6 in both direct bacterial samples and in spiked urine/blood samples. As a result, four chromogenic culture media and OXA-48 K-SeT can be used safely for detection of OXA-48 positive K.pneumoniae isolates. Although direct clinical specimens were not used, our study suggests that this media and OXA-48 K-SeT may be used in patient samples like blood and urine. Further studies are needed to assess this suggestion. Copyright © 2018 Elsevier B.V. All rights reserved.

Electronic band-gap modified passive silicon optical modulator at telecommunications wavelengths.

PubMed

Zhang, Rui; Yu, Haohai; Zhang, Huaijin; Liu, Xiangdong; Lu, Qingming; Wang, Jiyang

2015-11-13

The silicon optical modulator is considered to be the workhorse of a revolution in communications. In recent years, the capabilities of externally driven active silicon optical modulators have dramatically improved. Self-driven passive modulators, especially passive silicon modulators, possess advantages in compactness, integration, low-cost, etc. Constrained by a large indirect band-gap and sensitivity-related loss, the passive silicon optical modulator is scarce and has been not advancing, especially at telecommunications wavelengths. Here, a passive silicon optical modulator is fabricated by introducing an impurity band in the electronic band-gap, and its nonlinear optics and applications in the telecommunications-wavelength lasers are investigated. The saturable absorption properties at the wavelength of 1.55 μm was measured and indicates that the sample is quite sensitive to light intensity and has negligible absorption loss. With a passive silicon modulator, pulsed lasers were constructed at wavelengths at 1.34 and 1.42 μm. It is concluded that the sensitive self-driven passive silicon optical modulator is a viable candidate for photonics applications out to 2.5 μm.

Calibration of polyurethane foam (PUF) disk passive air samplers for quantitative measurement of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs): factors influencing sampling rates.

PubMed

Hazrati, Sadegh; Harrad, Stuart

2007-03-01

PUF disk passive air samplers are increasingly employed for monitoring of POPs in ambient air. In order to utilize them as quantitative sampling devices, a calibration experiment was conducted. Time integrated indoor air concentrations of PCBs and PBDEs were obtained from a low volume air sampler operated over a 50 d period alongside the PUF disk samplers in the same office microenvironment. Passive sampling rates for the fully-sheltered sampler design employed in our research were determined for the 51 PCB and 7 PBDE congeners detected in all calibration samples. These values varied from 0.57 to 1.55 m3 d(-1) for individual PCBs and from 1.1 to 1.9 m3 d(-1) for PBDEs. These values are appreciably lower than those reported elsewhere for different PUF disk sampler designs (e.g. partially sheltered) employed under different conditions (e.g. in outdoor air), and derived using different calibration experiment configurations. This suggests that sampling rates derived for a specific sampler configuration deployed under specific environmental conditions, should not be extrapolated to different sampler configurations. Furthermore, our observation of variable congener-specific sampling rates (consistent with other studies), implies that more research is required in order to understand fully the factors that influence sampling rates. Analysis of wipe samples taken from the inside of the sampler housing, revealed evidence that the housing surface scavenges particle bound PBDEs.

Use of Passive Samplers to Determine the Source of Dissolved PAHs in the Ottawa River, Toledo, Ohio

EPA Science Inventory

As part of a larger study on the remedy effectiveness on the Ottawa River, (Ohio, USA), research was focused on the source of PAHs to water and sediment. Polyethylene passive samplers, or polyethylene devices (PEDs), were deployed and analyzed, along with whole water samples and...

Passive Sampling to Capture the Spatial Variability of Coarse Particles by Composition in Cleveland, OH

EPA Science Inventory

Passive samplers deployed at 25 sites for three week-long intervals were used to characterize spatial variability in the mass and composition of coarse particulate matter (PM_10-2.5) in Cleveland, OH in summer 2008. The size and composition of individual particles deter...

Testing Of An Ultraviolet (UV)-Transparent Polymer-Based Passive Sampler for Rapid, Ultra-Low-Cost EDC Screening Applications

EPA Science Inventory

A new passive sampling method with rapid low-cost spectral detection has recently been developed. The method makes use of an ultraviolet (UV)-transparent polymer which serves as both a concentrator for dissolved compounds, and an optical cell for UV spectral detection. Because ...

Strategy for Passivating Char Efficiently at the Pilot Scale

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

Dunning, Timothy C

Fast pyrolysis is a promising pathway for the commercialization of liquid transportation fuels from biomass. Fast pyrolysis is performed at moderate heat (450-600 degrees Celcius) in an oxygen-deficient environment. One of the products of fast pyrolysis is biochar, which is often used as a heat source or as a soil amendment. Biochar is a partially reacted solid that is created in the production of bio-oil during fast pyrolysis. Biochar produced at these conditions contains significant quantities of carbon that adsorb oxygen when exposed to air. Biochar adsorption of oxygen is an exothermic process that may generate sufficient heat for combustionmore » in ambient air. Biochar is also a self-insulating material which compounds the effects of heat generated internally. These factors lead to safety concerns and material handling difficulties. The Thermochemical Process Development Unit at the National Renewable Energy Laboratory operates a pilot plant that may be configured for fast pyrolysis, gasification, and will be introducing catalytic fast pyrolysis capabilities in 2018. The TCPDU designed and installed a system to introduce oxygen to collected biochar systematically for a controlled passivation. Biochar is collected and cooled in an oxygen deficient environment during fast pyrolysis. Oxygen is then introduced to the biochar on a mass flow basis. A sparger imbedded within the biochar sample near the bottom of the bed flows air diluted with nitrogen into the char bed, and excess gasses are removed from the top of the collection drum, above the char bed. Pressure within the collection drum is measured indicating adequate flow through filters. Sample weight is recorded before and after passivation. During passivation, temperature is measured at 18 points within the char bed. Oxygen content and temperature are measured leaving the char bed. Maximum temperature parameters were established to ensure operator safety during biochar passivation. Extensive passivation data was collected on pine and blended feedstocks and has been analyzed to characterize the exotherm of char samples. Observations and data collected while passivating char will be discussed.« less

Performance evaluation of a tailor-made passive sampler for monitoring of tropospheric ozone.

PubMed

Ozden, Ozlem; Döğeroğlu, Tuncay

2012-09-01

This study presents the performance evaluation of a tailor-made passive sampler developed for the monitoring of tropospheric ozone. The performance of the passive sampler was tested in the field conditions in terms of accuracy, precision, blank values, detection limit, effects of some parameters such as sampling site characteristics and sampling period on the field blanks, self-consistency, experimental and theoretical uptake rates, shelf life and comparison with commercial passive samplers. There was an agreement (R (2) = 0.84) between the responses of passive sampler and the continuous automatic analyser. The accuracy of the sampler, expressed as percent relative error, was obtained lower than 15%. Method precision in terms of coefficient of variance for three simultaneously applied passive samplers was 12%. Sampler detection limit was 2.42 μg m(-3) for an exposure period of 1 week, and the sampler can be stored safely for a period of up to 8 weeks before exposure. Satisfactory self-consistency results showed that extended periods gave the same integrated response as a series of short-term samplers run side by side. The uptake rate of ozone was found to be 10.21 mL min(-1) in a very good agreement with the theoretical uptake rate (10.32 mL min(-1)). The results of the comparison study conducted against a commercially available diffusion tube (Gradko diffusion tube) showed a good linear relationship (R (2) = 0.93) between two passive samplers. The sampler seems suitable to be used in large-scale measurements of ozone where no data are available or the number of existing automated monitors is not sufficient.

The Distinct Build-Up Of Dense And Normal Massive Passive Galaxies In Vipers

NASA Astrophysics Data System (ADS)

Gargiulo, Adriana; Vipers Team

2017-06-01

At fixed stellar mass, the population of passive galaxies has increased its mean effective radius < Re > by a factor 5 in the last 10 Gyr, decreasing its mean stellar mass density (S = Mstar/(2πRe 2 ) by a factor >> 10. Whether this increase in < Re > is mainly due to the size-growth of individual galaxies through dry mergers, or to the fact that newly quenched galaxies have a larger size, is still matter of debate. A promising approach to shed light on this issue is to investigate the evolution of the number density of passive galaxies as a function of their mass density. In this context, massive (Mstar >10^11 Msun) passive galaxies are the most intriguing systems to study, since, in a hierarchical scenario, they are expected to accrete their stellar mass mainly by mergers. The wide area (˜ 16 sq. deg) and high sampling rate (˜ 40%) of the spectroscopic survey VIPERS allowed us to collect a sample of ˜ 2000 passive massive galaxies over the redshift range 0.5 < z < 1.0 and to study, with unprecedented statistics, the evolution of their number density as function of their mean stellar mass density in this redshift range. Taking advantage of both spectroscopic (D4000) and photometric (SED fitting) data available, we studied the age of the stellar population of passive galaxies as function both of redshift and mass density. This information, combined with the evolution of the number density allowed us to put constraints on the mass accretion scenarios of passive galaxies. In this talk I will present our results and conclusions and how they depend on the environment in which the galaxies reside.

Oxidation precursor dependence of atomic layer deposited Al2O3 films in a-Si:H(i)/Al2O3 surface passivation stacks.

PubMed

Xiang, Yuren; Zhou, Chunlan; Jia, Endong; Wang, Wenjing

2015-01-01

In order to obtain a good passivation of a silicon surface, more and more stack passivation schemes have been used in high-efficiency silicon solar cell fabrication. In this work, we prepared a-Si:H(i)/Al2O3 stacks on KOH solution-polished n-type solar grade mono-silicon(100) wafers. For the Al2O3 film deposition, both thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) were used. Interface trap density spectra were obtained for Si passivation with a-Si films and a-Si:H(i)/Al2O3 stacks by a non-contact corona C-V technique. After the fabrication of a-Si:H(i)/Al2O3 stacks, the minimum interface trap density was reduced from original 3 × 10(12) to 1 × 10(12) cm(-2) eV(-1), the surface total charge density increased by nearly one order of magnitude for PE-ALD samples and about 0.4 × 10(12) cm(-2) for a T-ALD sample, and the carrier lifetimes increased by a factor of three (from about 10 μs to about 30 μs). Combining these results with an X-ray photoelectron spectroscopy analysis, we discussed the influence of an oxidation precursor for ALD Al2O3 deposition on Al2O3 single layers and a-Si:H(i)/Al2O3 stack surface passivation from field-effect passivation and chemical passivation perspectives. In addition, the influence of the stack fabrication process on the a-Si film structure was also discussed in this study.

Three Dimensional Transient Analysis of Microstrip Circuits in Multilayered Anisotropic Media

DTIC Science & Technology

1994-01-18

time fat rfVWh ifl~ttUktOnS. watching e..,ing| galai• fld t gatlwnq and maintaningn~ te data needed. an cems~l~lzn andI reuiewing 1h cOllection Of...noise on the passive via are derived. The coupling responses in the frequency domain and crosstalk waveforms in the time domain for some multilayered...source, developed across the module-backplane connector. The finite-difference time -domain (FD-TD) technique, which is based on the discretization of

Information management for clinicians.

PubMed

Mehta, Neil B; Martin, Stephen A; Maypole, Jack; Andrews, Rebecca

2016-08-01

Clinicians are bombarded with information daily by social media, mainstream television news, e-mail, and print and online reports. They usually do not have much control over these information streams and thus are passive recipients, which means they get more noise than signal. Accessing, absorbing, organizing, storing, and retrieving useful medical information can improve patient care. The authors outline how to create a personalized stream of relevant information that can be scanned regularly and saved so that it is readily accessible. Copyright © 2016 Cleveland Clinic.

Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

NASA Astrophysics Data System (ADS)

Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

2016-02-01

In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

Four passive sampling elements (quatrefoil)--I. Monitoring radon and its progeny by surface-contamination monitors.

PubMed

Tommasino, L; Tokonami, S

2011-05-01

Four passive sampling elements (quatrefoil) have been recently developed, which transform airborne radionuclides into surface-bound radionuclides. These samplers, once exposed, result in thin radiation sources that can be detected by any real-time or passive detector. In particular, by using a large collecting-area sampler with a low surface density (g cm(-2)), it is possible to measure radon and its decay products by beta surface-contamination monitors, which are rarely used for these applications. The results obtained to date prove that it is finally possible to carry out the measurements of radon (and its decay products) indoors, in soil and in water simply by a Pancake Geiger-Muller counter. Emphasis will be given to those measurements, which are difficult, if not impossible, to carry out with existing technologies.

Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air Part 1: Sorbent-based air monitoring options.

PubMed

Woolfenden, Elizabeth

2010-04-16

Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species. Airborne vapour concentrations will vary depending on the nature of the location, nearby pollution sources, weather conditions, etc. Levels can range from low percent concentrations in stack and vent emissions to low part per trillion (ppt) levels in ultra-clean outdoor locations. Hundreds, even thousands of different compounds may be present in any given atmosphere. GC is commonly used in combination with mass spectrometry (MS) detection especially for environmental monitoring or for screening uncharacterised workplace atmospheres. Given the complexity and variability of organic vapours in air, no one sampling approach suits every monitoring scenario. A variety of different sampling strategies and sorbent media have been developed to address specific applications. Key sorbent-based examples include: active (pumped) sampling onto tubes packed with one or more sorbents held at ambient temperature; diffusive (passive) sampling onto sorbent tubes/cartridges; on-line sampling of air/gas streams into cooled sorbent traps; and transfer of air samples from containers (canisters, Tedlar) bags, etc.) into cooled sorbent focusing traps. Whichever sampling approach is selected, subsequent analysis almost always involves either solvent extraction or thermal desorption (TD) prior to GC(/MS) analysis. The overall performance of the air monitoring method will depend heavily on appropriate selection of key sampling and analytical parameters. This comprehensive review of air monitoring using sorbent tubes/traps is divided into 2 parts. (1) Sorbent-based air sampling option. (2) Sorbent selection and other aspects of optimizing sorbent-based air monitoring methods. The paper presents current state-of-the-art and recent developments in relevant areas such as sorbent research, sampler design, enhanced approaches to analytical quality assurance and on-tube derivatisation. Copyright 2009 Elsevier B.V. All rights reserved.

Attitudes of a Sample of English, Maltese and German Teachers towards Media Education

ERIC Educational Resources Information Center

Lauri, M. A.; Borg, J.; Gunnel, T.; Gillum, R.

2010-01-01

Media education forms part of the National Minimum Curriculum of England, Malta and Germany. Teacher training courses differ greatly in how teachers are prepared to teach media education. In this paper we shall investigate the attitudes of a sample of teachers trained in England, Malta and in Germany towards their perceived importance of media…

Passive-solar homes for Texas

NASA Astrophysics Data System (ADS)

Garrison, M. L.

1982-06-01

Acceptance of passive solar technologies has been slow within the conventional building trades in Texas because it is a common misconception that solar is expensive, and data on local applications is severely limited or nonexistent. It is the purpose of this solar development to move passive solar design into the mainstream of public acceptance by helping to overcome and eliminate these barriers. Specifically, the goal is to develop a set of regional climatic building standards to help guide the conventional building trade toward the utilization of soft energy systems which will reduce overall consumption at a price and convenience most Texans can afford. To meet this objective, eight sample passive design structures are presented. These designs represent state of the art regional applications of passive solar space conditioning. The methodology used in the passive solar design process included: analysis of regional climatic data; analysis of historical regional building prototypes; determination of regional climatic design priorities and assets; prototypical design models for the discretionary housing market; quantitative thermal analysis of prototypical designs; and construction drawings of building prototypes.

APPLICATION OF SEMIPERMEABLE MEMBRANE DEVICES TO INDOOR AIR SAMPLING

EPA Science Inventory

Semipermeable membrane devices (SPMDs) are a relatively new passive sampling technique for nonpolar organic compounds that have been extensively used for surface water sampling. A small body of literature indicates that SPMDs are also useful for air sampling. Because SPMDs ha...

Family coping and premenstrual symptomatology.

PubMed

Ornitz, A W; Brown, M A

1993-01-01

To examine how families cope when the woman experiences premenstrual symptomatology. A descriptive panel design and purposive, nonprobability sampling through interviews and questionnaires. Participants' homes. One hundred four couples who met the study criteria were recruited from medical practices and community seminars and through media announcements. Study outcome measures were formulated after data collection. High-symptom families used spiritual coping strategies more frequently than low-symptom families (R = .427, p = 0.003 in women, p < 0.001 in men). Husbands were more likely than wives to report that their families coped by believing that the problem would go away if they waited long enough (t = -3.06, p = 0.003). Husbands of women with high symptomatology reported that their families used this passive approach to a significant degree (t = -3.43, p = 0.001). Religious or spiritual support may be especially important to families in which the woman suffers from premenstrual symptomatology. These families may also keep problems within the family and be socially detached. Nurses may help by encouraging the use of social supports, religious or spiritual support, and other family resources.

Occurrence and Phase Distribution of Neutral and Ionizable Per- and Polyfluoroalkyl Substances (PFASs) in the Atmosphere and Plant Leaves around Landfills: A Case Study in Tianjin, China.

PubMed

Tian, Ying; Yao, Yiming; Chang, Shuai; Zhao, Zhen; Zhao, Yangyang; Yuan, Xiaojia; Wu, Fengchang; Sun, Hongwen

2018-02-06

A total of 23 per- and polyfluoroalkyl substances (PFASs) were investigated in the air, dry deposition, and plant leaves at two different landfills and one suburban reference site in Tianjin, China. The potential of landfills as sources of PFASs to the atmosphere and the phase distribution therein were evaluated. The maximum concentrations of ∑PFASs in the two landfills were up to 9.5 ng/m 3 in the air, 4.1 μg/g in dry deposition, and 48 μg/g lipid in leaves with trifluoroacetic acid and perfluoropropionic acid being dominant (71%-94%). Spatially, the distribution trend of ionizable and neutral PFASs in all three kinds of media consistently showed the central landfill > the downwind > the upwind > the reference sites, indicating that landfills are important sources to PFASs in the environment. Plant leaves were found effective in uptake of a variety of airborne PFASs including polyfluoroalkyl phosphoric acid diesters, thus capable of acting as a passive air sampling approach for air monitoring.

Degradation of 2DEG transport properties in GaN-capped AlGaN/GaN heterostructures at 600 °C in oxidizing and inert environments

NASA Astrophysics Data System (ADS)

Hou, Minmin; Jain, Sambhav R.; So, Hongyun; Heuser, Thomas A.; Xu, Xiaoqing; Suria, Ateeq J.; Senesky, Debbie G.

2017-11-01

In this paper, the electron mobility and sheet density of the two-dimensional electron gas (2DEG) in both air and argon environments at 600 °C were measured intermittently over a 5 h duration using unpassivated and Al2O3-passivated AlGaN/GaN (with 3 nm GaN cap) van der Pauw test structures. The unpassivated AlGaN/GaN heterostructures annealed in air showed the smallest decrease (˜8%) in 2DEG electron mobility while Al2O3-passivated samples annealed in argon displayed the largest drop (˜70%) based on the Hall measurements. Photoluminescence and atomic force microscopy showed that minimal strain relaxation and surface roughness changes have occurred in the unpassivated samples annealed in air, while those with Al2O3 passivation annealed in argon showed significant microstructural degradations. This suggests that cracks developed in the samples annealed in air were healed by oxidation reactions. To further confirm this, Auger electron spectroscopy was conducted on the unpassivated samples after the anneal in air and results showed that extra surface oxides have been generated, which could act as a dislocation pinning layer to suppress the strain relaxation in AlGaN. On the other hand, similar 2DEG sheet densities were observed in passivated and unpassivated AlGaN/GaN samples at the end of the 5-h anneal in air or argon due to the combined impact of strain relaxation and changes in the ionized electronic states. The results support the use of unpassivated GaN-capped AlGaN/GaN heterostructures as the material platform for high-temperature electronics and sensors used in oxidizing environmental conditions.

Field-based evaluation of semipermeable membrane devices (SPMDs) as passive air samplers of polyaromatic hydrocarbons (PAHs)

USGS Publications Warehouse

Bartkow, M.E.; Huckins, J.N.; Muller, J.F.

2004-01-01

Semipermeable membrane devices (SPMDs) have been used as passive air samplers of semivolatile organic compounds in a range of studies. However, due to a lack of calibration data for polyaromatic hydrocarbons (PAHs), SPMD data have not been used to estimate air concentrations of target PAHs. In this study, SPMDs were deployed for 32 days at two sites in a major metropolitan area in Australia. High-volume active sampling systems (HiVol) were co-deployed at both sites. Using the HiVol air concentration data from one site, SPMD sampling rates were measured for 12 US EPA Priority Pollutant PAHs and then these values were used to determine air concentrations at the second site from SPMD concentrations. Air concentrations were also measured at the second site with co-deployed HiVols to validate the SPMD results. PAHs mostly associated with the vapour phase (Fluorene to Pyrene) dominated both the HiVol and passive air samples. Reproducibility between replicate passive samplers was satisfactory (CV<20%) for the majority of compounds. Sampling rates ranged between 0.6 and 6.1 m3 d-1. SPMD-based air concentrations were calculated at the second site for each compound using these sampling rates and the differences between SPMD-derived air concentrations and those measured using a HiVol were, on average, within a factor of 1.5. The dominant processes for the uptake of PAHs by SPMDs were also assessed. Using the SPMD method described herein, estimates of particulate sorbed airborne PAHs with five rings or greater were within 1.8-fold of HiVol measured values. ?? 2004 Elsevier Ltd. All rights reserved.

Decision and function problems based on boson sampling

NASA Astrophysics Data System (ADS)

Nikolopoulos, Georgios M.; Brougham, Thomas

2016-07-01

Boson sampling is a mathematical problem that is strongly believed to be intractable for classical computers, whereas passive linear interferometers can produce samples efficiently. So far, the problem remains a computational curiosity, and the possible usefulness of boson-sampling devices is mainly limited to the proof of quantum supremacy. The purpose of this work is to investigate whether boson sampling can be used as a resource of decision and function problems that are computationally hard, and may thus have cryptographic applications. After the definition of a rather general theoretical framework for the design of such problems, we discuss their solution by means of a brute-force numerical approach, as well as by means of nonboson samplers. Moreover, we estimate the sample sizes required for their solution by passive linear interferometers, and it is shown that they are independent of the size of the Hilbert space.

Microbiological Assessment of Indoor Air of Teaching Hospital Wards: A case of Jimma University Specialized Hospital.

PubMed

Fekadu, Samuel; Getachewu, Bahilu

2015-04-01

Hospital environment represents a congenial situation where microorganisms and susceptible patients are indoors together. Thus, the objective of this study is to provide fundamental data related to the microbial quality of indoor air of Jimma University Specialized Hospital wards, to estimate the health hazard and to create standards for indoor air quality control. The microbial quality of indoor air of seven wards of Jimma University Specialized Hospital was determined. Passive air sampling technique, using open Petri-dishes containing different culture media, was employed to collect sample twice daily. The concentrations of bacteria and fungi aerosols in the indoor environment of the wards ranged between 2123 - 9733 CFU/m(3). The statistical analysis showed that the concentrations of bacteria that were measured in all studied wards were significantly different from each other (p-value=0.017), whereas the concentrations of fungi that were measured in all sampled wards were not significantly different from each other (p-value=0.850). Moreover, the concentrations of bacteria that were measured at different sampling time (morning and afternoon) were significantly different (p-value =0.001). All wards that were included in the study were heavily contaminated with bacteria and fungi. Thus, immediate interventions are needed to control those environmental factors which favor the growth and multiplication of microbes, and it is vital to control visitors and students in and out the wards. Moreover, it is advisable that strict measures be put in place to check the increasing microbial load in the hospital environment.

Investigation of hydrophobic contaminants in an urban slough system using passive sampling - Insights from sampling rate calculations

USGS Publications Warehouse

McCarthy, K.

2008-01-01

Semipermeable membrane devices (SPMDs) were deployed in the Columbia Slough, near Portland, Oregon, on three separate occasions to measure the spatial and seasonal distribution of dissolved polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) in the slough. Concentrations of PAHs and OCs in SPMDs showed spatial and seasonal differences among sites and indicated that unusually high flows in the spring of 2006 diluted the concentrations of many of the target contaminants. However, the same PAHs - pyrene, fluoranthene, and the alkylated homologues of phenanthrene, anthracene, and fluorene - and OCs - polychlorinated biphenyls, pentachloroanisole, chlorpyrifos, dieldrin, and the metabolites of dichlorodiphenyltrichloroethane (DDT) - predominated throughout the system during all three deployment periods. The data suggest that storm washoff may be a predominant source of PAHs in the slough but that OCs are ubiquitous, entering the slough by a variety of pathways. Comparison of SPMDs deployed on the stream bed with SPMDs deployed in the overlying water column suggests that even for the very hydrophobic compounds investigated, bed sediments may not be a predominant source in this system. Perdeuterated phenanthrene (phenanthrene-d10). spiked at a rate of 2 ??g per SPMD, was shown to be a reliable performance reference compound (PRC) under the conditions of these deployments. Post-deployment concentrations of the PRC revealed differences in sampling conditions among sites and between seasons, but indicate that for SPMDs deployed throughout the main slough channel, differences in sampling rates were small enough to make site-to-site comparisons of SPMD concentrations straightforward. ?? Springer Science+Business Media B.V. 2007.

Electrochemical Behavior Assessment of Micro- and Nano-Grained Commercial Pure Titanium in H2SO4 Solutions

NASA Astrophysics Data System (ADS)

Fattah-alhosseini, Arash; Ansari, Ali Reza; Mazaheri, Yousef; Karimi, Mohsen

2017-02-01

In this study, the electrochemical behavior of commercial pure titanium with both coarse-grained (annealed sample with the average grain size of about 45 µm) and nano-grained microstructure was compared by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Nano-grained Ti, which typically has a grain size of about 90 nm, is successfully made by six-cycle accumulative roll-bonding process at room temperature. Potentiodynamic polarization plots and impedance measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure Ti in H2SO4 solutions. Mott-Schottky analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and grain refinement did not change the semiconductor type of passive films. Also, Mott-Schottky analysis showed that the donor densities decreased as the grain size of the samples reduced. Finally, all electrochemical tests showed that the electrochemical behavior of the nano-grained sample was improved compared to that of annealed pure Ti, mainly due to the formation of thicker and less defective oxide film.

Facebook and Twitter, communication and shelter, and the 2011 Tuscaloosa tornado.

PubMed

Stokes, Courtney; Senkbeil, Jason C

2017-01-01

This paper represents one of the first attempts to analyse the many ways in which Facebook and Twitter were used during a tornado disaster. Comparisons between five randomly selected campus samples and a city of Tuscaloosa, Alabama, sample revealed that campus samples used Facebook and Twitter significantly more both before and after the tornado, but Facebook usage was not significantly different after the event. Furthermore, differences in social media usage and other forms of communication before the tornado were found for age, education, and years lived in Tuscaloosa. Generally, age and education were inversely proportionate to social media usage. Influences on shelter-seeking actions varied between social media users and three random samples of non-social media users; however, it appears that social media respondents were likely to be using a smartphone simultaneously to access warning polygon information, to receive text message alerts, and to listen or respond to environmental cues. © 2017 The Author(s). Disasters © Overseas Development Institute, 2017.

The Role of Social Media User Experience as a Mediator for Understanding Social Media User Behavior in Indonesia’s Museum Industry: Literature Review

NASA Astrophysics Data System (ADS)

Sundjaja, A. M.; LumanGaol, F.; Budiarti, T.; Abbas, B. S.; Abdinagoro, S. B.; Ongowarsito, H.

2017-01-01

Social media has changed the interaction between the customer and the business, social media has proven to provide new opportunities in facilitating access to information, efficiency and ease of interaction between customers and businesses that are distributed geographically dispersed. Ease of interaction to improve access to information about products, services, and prices have proven to have a positive impact for consumers. The purpose of this article is to develop a conceptual model to test the effect of user motivation, user expectations, and online community involvement to the intention of behavior that is mediated by the use of social media museum experience. This article is a literature study on exploration of social media user experiences museum in Indonesia. Authors searched and examined 85 articles from google scholar with the following keywords: motivation, expectations, online communities, user experience, social media, Technology Acceptance Model, Experiential Marketing, Uses and Gratification Theory. Proposed data collection techniques are literature study, survey and observation. The sample used in this research is 400 respondents of social media users that follow the social media managed by Indonesia’s museum. The sampling technique are systematic sampling. We use Structural Equation Model with AMOS for analyze the data.

Potential Use of Passive Sampling for Environmental Monitoring of Petroleum E&P Operations

EPA Pesticide Factsheets

Traditional environmental monitoring relies on water or soil samples being taken at various time increments and sent to offsite laboratories for analysis. Reliance on grab samples generally captures limited “snapshots” of environmental contaminant concentrations, is time intensive, costly, and generates residual waste from excess sample and/or reagents used in the analysis procedures. As an alternative, we are evaluating swellable organosilica sorbents to create passive sampling systems for monitoring applications. Previous work has focused on absorption and detection of fuels, chlorinated solvents, endocrine disruptors, explosives, pesticides, fluorinated chemicals, and metals including Ba, Sr, Hg, Pb, Fe, Cu, and Zn. The advantages of swellable organosilica are that the material cancapture target compounds for an extended periods of time, does not absorb natural organic matter, and resists biofilm formation since the sorbent possesses an animated surface morphology.

Genetic Stability of Streptomyces Lividans pIJ702 in Response to Spaceflight

NASA Astrophysics Data System (ADS)

Lim, K. S.; Goins, T. L.; Voeikova, T. A.; Pyle, B. H.

2008-06-01

Streptomyces lividans carrying plasmid pIJ702 encoding genes for thiostrepton resistance (tsr-) and melanin production (mel+) was plated on agar and flown on the Russian satellite Foton-M3 for 16 days. The percentage loss of plasmid expression in flight samples was lower than that in ground samples when both samples were grown in enriched (ISP) media. Differences in media content also affect plasmid expression rate; ISP media have a higher loss of plasmid expression than samples in minimum media when both were grown on ground conditions. Results suggest that stress resulted in the increased expression of plasmid pIJ702 by S. lividans. Screening of thiostrepton resistant white (tsr+ mel-) mutants showed similar proportions of variants in ground samples and flight samples. To determine if there are mutations in the mel gene, DNA extracted from flight and control white mutants was amplified and gel electrophoresis of amplified products show no major mutation in the products. Sequencing of amplified products is required to identify mutations resulting in loss of pigmentation.

Calibration of Passive Samplers for the Monitoring of Pharmaceuticals in Water-Sampling Rate Variation.

PubMed

Męczykowska, Hanna; Kobylis, Paulina; Stepnowski, Piotr; Caban, Magda

2017-05-04

Passive sampling is one of the most efficient methods of monitoring pharmaceuticals in environmental water. The reliability of the process relies on a correctly performed calibration experiment and a well-defined sampling rate (R s ) for target analytes. Therefore, in this review the state-of-the-art methods of passive sampler calibration for the most popular pharmaceuticals: antibiotics, hormones, β-blockers and non-steroidal anti-inflammatory drugs (NSAIDs), along with the sampling rate variation, were presented. The advantages and difficulties in laboratory and field calibration were pointed out, according to the needs of control of the exact conditions. Sampling rate calculating equations and all the factors affecting the R s value - temperature, flow, pH, salinity of the donor phase and biofouling - were discussed. Moreover, various calibration parameters gathered from the literature published in the last 16 years, including the device types, were tabled and compared. What is evident is that the sampling rate values for pharmaceuticals are impacted by several factors, whose influence is still unclear and unpredictable, while there is a big gap in experimental data. It appears that the calibration procedure needs to be improved, for example, there is a significant deficiency of PRCs (Performance Reference Compounds) for pharmaceuticals. One of the suggestions is to introduce correction factors for R s values estimated in laboratory conditions.

Silicone rubber selection for passive sampling of pesticides in water.

PubMed

Martin, A; Margoum, C; Randon, J; Coquery, M

2016-11-01

Silicone rubber can extract organic compounds with a broad range of polarities (logKow>2-3) from aqueous samples. Such compounds include substances of major concern in the protection of aquatic ecosystems and human health, e.g. pesticides. Silicone rubbers (SRs) with various characteristics have been successfully used in sorptive methods for water sample extraction in the laboratory (SPME, SBSE), and for passive sampling in aquatic environments. However, only few studies have evaluated variability in organic compound sorption due to the origin of SRs, particularly for pesticides. The aim of this study was to select an SR for the extraction of pesticides from water samples by passive sampling. To this end we measured the impact of seven SR formulations on sorption capacity, defined by the partition coefficient (Ksw). Kinetic experiments and sorption isotherms were performed to determine extraction recovery as a selection criterion for SRs, and pesticide partition coefficients. Very large differences in affinity for pesticides were found between two kinds of SRs: "Polymerized SR kits" and "Manufactured SRs". One SR was chosen among the "Manufactured SRs", and the Ksw values of 21 pesticides were determined, filling a gap in the literature (1.50

Characterising Passive Dosemeters for Dosimetry of Biological Experiments in Space (dobies)

NASA Astrophysics Data System (ADS)

Vanhavere, Filip; Spurny, Frantisek; Yukihara, Eduardo; Genicot, Jean-Louis

Introduction: The DOBIES (Dosimetry of biological experi-ments in space) project focusses on the use of a stan-dard dosimetric method (as a combination of differ-ent passive techniques) to measure accurately the absorbed doses and equivalent doses in biological samples. Dose measurements on biological samples are of high interest in the fields of radiobiology and exobiology. Radiation doses absorbed by biological samples must be quantified to be able to determine the relationship between observed biological effects and the radiation dose. The radiation field in space is very complex, con-sisting of protons, neutrons, electrons and high-energy heavy charged particles. It is not straightfor-ward to measure doses in this radiation field, cer-tainly not with only small and light passive doseme-ters. The properties of the passive detectors must be tested in radiation fields that are representative of the space radiation. We will report on the characterisation of different type of passive detectors at high energy fields. The results from such characterisation measurements will be applied to recent exposures of detectors on the International Space Station. Material and methods: Following passive detectors are used: • thermoluminescent detectors (TLD) • optically stimulated luminescence detectors (OSLD) • track etch detectors (TED) The different groups have participated in the past to the ICCHIBAN series of irradiations. Here protons and other particles of high energy were used to de-termine the LET-dependency of the passive detec-tors. The last few months, new irradiations have been done at the iThemba labs (100-200 MeV protons), Dubna (145 MeV protons) and the JRC-IRMM (quasi mono energetic neutrons up to 19 MeV). All these detectors were also exposed to a simulated space radiation field at CERN (CERF-field). Discussion: The interpretation of the TLD and OSLD results is done using the measured LET spectrum (TED) and the LET-dependency curves of ths TLD and OSLDs. These LET- dependency curves are determined based on the different irradiations listed above. We will report on the results of the different detectors in these fields. Further information on the LET of the space irradia-tion can be deduced from the ratio of the different peaks of the TLDs after glow curve deconvolution, and from the shape of the decay curve of the OSLDs. The results in the CERF field can on the other hand directly being used as a calibration for space radia-tion fields. Conclusion: Combining different passive detectors will lead to improved information on the radiation field, and thus to a better estimation of the absorbed dose to the bio-logical samples. We use the characterisations on high energy accelerators to improve the estimation of some recent space doses.

Reducing bacterial contamination in an Orthopedic Theatre ventilated by natural ventilation, in a Developing Country.

PubMed

Thomas, Stephanie; Palmer, Rish; Phillipo, Edward; Chipungu, Geoffrey

2016-05-31

All surgical procedures have the potential for infection and some of the main sources are contamination from airborne particles, theatre personnel and the theatre environment.  There is strong evidence that the use of ultra-clean air flow systems in orthopedic operating theatres reduces the incidence of deep sepsis after surgery. In the developing world however, this is often an unrealistic solution. The aim of this study was to establish baseline levels of contamination in a working orthopedic theatre, at the Queen Elizabeth Central Hospital, Blantyre, Malawi. To feedback results to the theatre team, promote infection prevention discussion and work with the team to implement workable and realistic goals to improve the intra-operative environment. Samples were collected from theatre equipment available at the time of surgery, from theatre water and theatre air using passive air sampling techniques. Samples were immediately transferred to the Central Microbiology Laboratory for culture on basic culture media. Bacterial contamination of theatre equipment, intra-operative theatre air and water was detected. Results were discussed with the theatre and infection prevention team who were receptive to feedback with regards to infection prevention strategies and keen to develop simple measures which could be put in place to change practice. In this setting, we suggest that implementing workable and realistic goals such as, establishing baseline rates of bacterial contamination and introduction of strict protocols for asepsis and theatre etiquette, may reduce bacterial contamination rates and subsequent intra-operative infection in the absence of expensive engineering solutions.

Do complex matrices modify the sorptive properties of polydimethylsiloxane (PDMS) for non-polar organic chemicals?

PubMed

Jahnke, Annika; Mayer, Philipp

2010-07-16

The partitioning of non-polar analytes into the silicone polydimethylsiloxane (PDMS) is the basis for many analytical approaches such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE) and environmental passive sampling. Recently, the methods have been applied to increasingly complex sample matrices. The present work investigated the possible effect of complex matrices on the sorptive properties of PDMS. First, SPME fibers with a 30 microm PDMS coating were immersed in 15 different matrices, including sediment, suspensions of soil and humic substances, mayonnaise, meat, fish, olive oil and fish oil. Second, the surface of the fibers was wiped clean, and together with matrix-free control fibers, they were exposed via headspace to 7 non-polar halogenated organic chemicals in spiked olive oil. The fibers were then solvent-extracted, analyzed, and the ratios of the mean concentrations in the matrix-immersed fibers to the control fibers were determined for all matrices. These ratios ranged from 92% to 112% for the four analytes with the highest analytical precision (i.e. polychlorinated biphenyls (PCBs) 3, 28, 52 and brominated diphenyl ether (BDE) 3), and they ranged from 74% to 133% for the other three compounds (i.e. PCBs 101, 105 and gamma-hexachlorocyclohexane (HCH)). We conclude that, for non-polar, hydrophobic chemicals, the sorptive properties of the PDMS were not modified by the diverse investigated media and consequently that PDMS is suited for sampling of these analytes even in highly complex matrices. 2010 Elsevier B.V. All rights reserved.

Is there a “net generation” in veterinary medicine? A comparative study on the use of the Internet and Web 2.0 by students and the veterinary profession

PubMed Central

Tenhaven, Christoph; Tipold, Andrea; Fischer, Martin R.; Ehlers, Jan P.

2013-01-01

Introduction: Informal and formal lifelong learning is essential at university and in the workplace. Apart from classical learning techniques, Web 2.0 tools can be used. It is controversial whether there is a so-called net generation amongst people under 30. Aims: To test the hypothesis that a net generation among students and young veterinarians exists. Methods: An online survey of students and veterinarians was conducted in the German-speaking countries which was advertised via online media and traditional print media. Results: 1780 people took part in the survey. Students and veterinarians have different usage patterns regarding social networks (91.9% vs. 69%) and IM (55.9% vs. 24.5%). All tools were predominantly used passively and in private, to a lesser extent also professionally and for studying. Outlook: The use of Web 2.0 tools is useful, however, teaching information and media skills, preparing codes of conduct for the internet and verification of user generated content is essential. PMID:23467682

Media and youth: access, exposure, and privatization.

PubMed

Roberts, D F

2000-08-01

To describe U.S. youth's access and exposure to the full array of media, as well as the social contexts in which media exposure occurs. A cross-sectional national random sample of 2065 adolescents aged 8 through 18 years, including oversamples of African-American and Hispanic youth, completed questionnaires about use of television, videotapes, movies, computers, video games, radio, compact discs, tape players, books, newspapers, and magazines. U.S. youngsters are immersed in media. Most households contain most media (computers and video game systems are the exception); the majority of youth have their own personal media. The average youth devotes 6 3/4 h to media; simultaneous use of multiple media increases exposure to 8 h of media messages daily. Overall, media exposure and exposure to individual media vary as a function of age, gender, race/ethnicity, and family socioeconomic level. Television remains the dominant medium. About one-half of the youth sampled uses a computer daily. A substantial proportion of children's and adolescents' media use occurs in the absence of parents. American youth devote more time to media than to any other waking activity, as much as one-third of each day. This demands increased parental attention and research into the effects of such extensive exposure.

The effects of parametric changes in electropolishing process on surface properties of 316L stainless steel

NASA Astrophysics Data System (ADS)

ur Rahman, Zia; Deen, K. M.; Cano, Lawrence; Haider, Waseem

2017-07-01

Corrosion resistance and biocompatibility of 316L stainless steel implants depend on the surface features and the nature of the passive film. The influence of electropolishing on the surface topography, surface free energy and surface chemistry was determined by atomic force microscopy, contact angle meter and X-ray photoelectron spectroscopy, respectively. The electropolishing of 316L stainless steel was conducted at the oxygen evolution potential (EPO) and below the oxygen evolution potential (EPBO). Compared to mechanically polished (MP) and EPO, the EPBO sample depicted lower surface roughness (Ra = 6.07 nm) and smaller surface free energy (44.21 mJ/m2). The relatively lower corrosion rate (0.484 mpy) and smaller passive current density (0.619 μA/cm2) as determined from cyclic polarization scans was found to be related with the presence of OH, Cr(III), Fe(0), Fe(II) and Fe(III) species at the surface. These species assured the existence of relatively uniform passive oxide film over EPBO surface. Moreover, the relatively large charge transfer (Rct) and passive film resistance (Rf) registered by EPBO sample from impedance spectroscopy analysis confirmed its better electrochemical performance. The in vitro response of these polished samples toward MC3T3 pre-osteoblast cell proliferation was determined to be directly related with their surface and electrochemical properties.

Evaluation of multiple-frequency, active and passive acoustics as surrogates for bedload transport

USGS Publications Warehouse

Wood, Molly S.; Fosness, Ryan L.; Pachman, Gregory; Lorang, Mark; Tonolla, Diego

2015-01-01

The use of multiple-frequency, active acoustics through deployment of acoustic Doppler current profilers (ADCPs) shows potential for estimating bedload in selected grain size categories. The U.S. Geological Survey (USGS), in cooperation with the University of Montana (UM), evaluated the use of multiple-frequency, active and passive acoustics as surrogates for bedload transport during a pilot study on the Kootenai River, Idaho, May 17-18, 2012. Four ADCPs with frequencies ranging from 600 to 2000 kHz were used to measure apparent moving bed velocities at 20 stations across the river in conjunction with physical bedload samples. Additionally, UM scientists measured the sound frequencies of moving particles with two hydrophones, considered passive acoustics, along longitudinal transects in the study reach. Some patterns emerged in the preliminary analysis which show promise for future studies. Statistically significant relations were successfully developed between apparent moving bed velocities measured by ADCPs with frequencies 1000 and 1200 kHz and bedload in 0.5 to 2.0 mm grain size categories. The 600 kHz ADCP seemed somewhat sensitive to the movement of gravel bedload in the size range 8.0 to 31.5 mm, but the relation was not statistically significant. The passive hydrophone surveys corroborated the sample results and could be used to map spatial variability in bedload transport and to select a measurement cross-section with moving bedload for active acoustic surveys and physical samples.

Origin and composition of cell-free DNA in spent medium from human embryo culture during preimplantation development.

PubMed

Vera-Rodriguez, M; Diez-Juan, A; Jimenez-Almazan, J; Martinez, S; Navarro, R; Peinado, V; Mercader, A; Meseguer, M; Blesa, D; Moreno, I; Valbuena, D; Rubio, C; Simon, C

2018-04-01

What is the origin and composition of cell-free DNA in human embryo spent culture media? Cell-free DNA from human embryo spent culture media represents a mix of maternal and embryonic DNA, and the mixture can be more complex for mosaic embryos. In 2016, ~300 000 human embryos were chromosomally and/or genetically analyzed using preimplantation genetic testing for aneuploidies (PGT-A) or monogenic disorders (PGT-M) before transfer into the uterus. While progress in genetic techniques has enabled analysis of the full karyotype in a single cell with high sensitivity and specificity, these approaches still require an embryo biopsy. Thus, non-invasive techniques are sought as an alternative. This study was based on a total of 113 human embryos undergoing trophectoderm biopsy as part of PGT-A analysis. For each embryo, the spent culture media used between Day 3 and Day 5 of development were collected for cell-free DNA analysis. In addition to the 113 spent culture media samples, 28 media drops without embryo contact were cultured in parallel under the same conditions to use as controls. In total, 141 media samples were collected and divided into two groups: one for direct DNA quantification (53 spent culture media and 17 controls), the other for whole-genome amplification (60 spent culture media and 11 controls) and subsequent quantification. Some samples with amplified DNA (N = 56) were used for aneuploidy testing by next-generation sequencing; of those, 35 samples underwent single-nucleotide polymorphism (SNP) sequencing to detect maternal contamination. Finally, from the 35 spent culture media analyzed by SNP sequencing, 12 whole blastocysts were analyzed by fluorescence in situ hybridization (FISH) to determine the level of mosaicism in each embryo, as a possible origin for discordance between sample types. Trophectoderm biopsies and culture media samples (20 μl) underwent whole-genome amplification, then libraries were generated and sequenced for an aneuploidy study. For SNP sequencing, triads including trophectoderm DNA, cell-free DNA, and follicular fluid DNA were analyzed. In total, 124 SNPs were included with 90 SNPs distributed among all autosomes and 34 SNPs located on chromosome Y. Finally, 12 whole blastocysts were fixed and individual cells were analyzed by FISH using telomeric/centromeric probes for the affected chromosomes. We found a higher quantity of cell-free DNA in spent culture media co-cultured with embryos versus control media samples (P ≤ 0.001). The presence of cell-free DNA in the spent culture media enabled a chromosomal diagnosis, although results differed from those of trophectoderm biopsy analysis in most cases (67%). Discordant results were mainly attributable to a high percentage of maternal DNA in the spent culture media, with a median percentage of embryonic DNA estimated at 8%. Finally, from the discordant cases, 91.7% of whole blastocysts analyzed by FISH were mosaic and 75% of the analyzed chromosomes were concordant with the trophectoderm DNA diagnosis instead of the cell-free DNA result. This study was limited by the sample size and the number of cells analyzed by FISH. This is the first study to combine chromosomal analysis of cell-free DNA, SNP sequencing to identify maternal contamination, and whole-blastocyst analysis for detecting mosaicism. Our results provide a better understanding of the origin of cell-free DNA in spent culture media, offering an important step toward developing future non-invasive karyotyping that must rely on the specific identification of DNA released from human embryos. This work was funded by Igenomix S.L. There are no competing interests.

The corrosion behavior of technetium metal exposed to aqueous sulfate and chloride solutions

DOE PAGES

Kolman, David Gary; Goff, George Scott; Cisneros, Michael Ruben; ...

2017-04-19

Here, metal waste forms are being studied as possible disposal forms for technetium and other fission products from spent nuclear fuel. As an initial step in assessing the viability of waste forms, technetium corrosion and passivity behavior was assessed across a broad pH spectrum (pH –1 to pH 13). Measurements indicate that the open circuit potential falls into the region of Tc +7 stability, more noble than the region of presumed passivity. Potentiodynamic polarization tests indicate that the Tc samples are not passive. Both electrochemical results and visual inspection suggest the presence of a nonprotective film. The corrosion rate ismore » relatively independent of pH and low, as measured by linear polarization resistance. No evidence of passivity was observed in the Tc +4 region of the potential-pH diagram following in-situ abrasion, suggesting that Tc does not passivate, regardless of potential.« less

The corrosion behavior of technetium metal exposed to aqueous sulfate and chloride solutions

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

Kolman, David Gary; Goff, George Scott; Cisneros, Michael Ruben

Here, metal waste forms are being studied as possible disposal forms for technetium and other fission products from spent nuclear fuel. As an initial step in assessing the viability of waste forms, technetium corrosion and passivity behavior was assessed across a broad pH spectrum (pH –1 to pH 13). Measurements indicate that the open circuit potential falls into the region of Tc +7 stability, more noble than the region of presumed passivity. Potentiodynamic polarization tests indicate that the Tc samples are not passive. Both electrochemical results and visual inspection suggest the presence of a nonprotective film. The corrosion rate ismore » relatively independent of pH and low, as measured by linear polarization resistance. No evidence of passivity was observed in the Tc +4 region of the potential-pH diagram following in-situ abrasion, suggesting that Tc does not passivate, regardless of potential.« less

A Seismic Shift: Evaluating Changes in Scientists' Attitudes Regarding Journalists and Science Communication After Media Workshops

NASA Astrophysics Data System (ADS)

McBride, S.; Herbulock, D.

2015-12-01

Providing natural hazards scientists the opportunity to question and engage directly with journalists in a workshop setting proved effective at shifting scientists' attitudes on their role in media and public communication during natural disasters. Scientists surveyed after the encounter expressed a more responsive attitude to communicating during crises, increased willingness to support scientific peers' communication efforts and more realistic perspectives on journalists' needs and objectives. Geoscientists experienced unprecedented and intensive media and public scrutiny during the Canterbury, New Zealand earthquakes of 2010-2012. Following major quakes and aftershocks, there was a sustained high level of public demand for information and expert analysis of the underlying geological events and ongoing hazards and risks. Once the crisis ended, a period of reflection gave rise to understanding of the need for further media and communication training amongst natural hazards scientists. A workshop designed to explore scientists' attitudes to public communication during disasters and challenge their views on media, press offices and the expectations of the public was developed and implemented by the Science Media Centre, New Zealand and Massey University. This research was developed as an evaluation of this workshop. Quantitative analysis with some qualititive analysis were the methods used. Some findings include: a shift in how journalists were perceived by scientists after the workshop, largely influenced by perspectives shared during a panel where invited journalists reflected on their own experiences and answered questions from scientists. discussions on different spokespeople from different science institutions contributing to the public discussion showed a change in perception from a preference for one central spokesperson to increased support for a variety of perspectives from multiple scientists. This was influenced by insight provided by journalists during the workshop into the practical demands of media and the need for multiple voices in media coverage. changes in how they would manage media queries, as well as a shift from passive to responsive attitudes towards communicating in crises.

A predictive parameter estimation approach for the thermodynamically constrained averaging theory applied to diffusion in porous media

NASA Astrophysics Data System (ADS)

Valdes-Parada, F. J.; Ostvar, S.; Wood, B. D.; Miller, C. T.

2017-12-01

Modeling of hierarchical systems such as porous media can be performed by different approaches that bridge microscale physics to the macroscale. Among the several alternatives available in the literature, the thermodynamically constrained averaging theory (TCAT) has emerged as a robust modeling approach that provides macroscale models that are consistent across scales. For specific closure relation forms, TCAT models are expressed in terms of parameters that depend upon the physical system under study. These parameters are usually obtained from inverse modeling based upon either experimental data or direct numerical simulation at the pore scale. Other upscaling approaches, such as the method of volume averaging, involve an a priori scheme for parameter estimation for certain microscale and transport conditions. In this work, we show how such a predictive scheme can be implemented in TCAT by studying the simple problem of single-phase passive diffusion in rigid and homogeneous porous media. The components of the effective diffusivity tensor are predicted for several porous media by solving ancillary boundary-value problems in periodic unit cells. The results are validated through a comparison with data from direct numerical simulation. This extension of TCAT constitutes a useful advance for certain classes of problems amenable to this estimation approach.

How Does Active Parental Consent Influence the Findings of Drug-Use Surveys in Schools?

ERIC Educational Resources Information Center

White, Victoria M.; Hill, David J.; Effendi, Yuksel

2004-01-01

This study examines the impact of passive and active parental consent procedures on the type of adolescents participating in a school-based survey examining substance use. Schools recruited from a random sample of metropolitan schools were assigned to passive or active parental consent condition. Results showed that participation rates in active…

Passive Sampling Provides Evidence for Neward Bay as a Source of Polychlorinated Dibenzo-p-Dioxins and Furans to the New York/New Jersey, USA, Atmosphere

EPA Science Inventory

Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were measured in the water column and atmosphere at five locations within Newark Bay (New Jersey, USA) from May 2008 to August 2009 with polyethylene (PE) passive ...

Variation in isotopologues of atmospheric nitric acid in passively collected samples along an air pollution gradient in southern California

Treesearch

Michael D. Bell; James O. Sickman; Andrzej Bytnerowicz; Pamela E. Padgett; Edith B. Allen

2014-01-01

The sources and oxidation pathways of atmospheric nitric acid (HNO3) can be evaluated using the isotopic signatures of oxygen (O) and nitrogen (N). This study evaluated the ability of Nylasorb nylon filters to passively collect unbiased isotopologues of atmospheric HNO3 under controlled and field conditions. Filters...

Proof of concept: preimplantation genetic screening without embryo biopsy through analysis of cell-free DNA in spent embryo culture media.

PubMed

Shamonki, Mousa I; Jin, Helen; Haimowitz, Zachary; Liu, Lian

2016-11-01

To assess whether preimplantation genetic screening (PGS) is possible by testing for free embryonic DNA in spent IVF media from embryos undergoing trophectoderm biopsy. Prospective cohort analysis. Academic fertility center. Seven patients undergoing IVF and 57 embryos undergoing trophectoderm biopsy for PGS. On day 3 of development, each embryo was placed in a separate media droplet. All biopsied embryos received a PGS result by array comparative genomic hybridization. Preimplantation genetic screening was performed on amplified DNA extracted from media and results were compared with PGS results for the corresponding biopsy. [1] Presence of DNA in spent IVF culture media. [2] Correlation between genetic screening result from spent media and corresponding biopsy. Fifty-five samples had detectable DNA ranging from 2-642 ng/μL after a 2-hour amplification. Six samples with the highest DNA levels underwent PGS, rendering one result with a derivative log ratio SD (DLRSD) of <0.85 (a quality control metric of oligonucleotide array comparative genomic hybridization). The fluid sample and trophectoderm results were identical demonstrating (45XY, -13). Three samples were reamplified 1 hour later and tested showing improving DLRSD. One of the three samples with a DLRSD of 0.85 demonstrated (46XY), consistent with the biopsy. Overnight DNA amplification showed DNA in all samples. We demonstrate two novel findings: the presence of free embryonic DNA in spent media and a result that is consistent with trophectoderm biopsy. Improvements in DNA collection, amplification, and testing may allow for PGS without biopsy in the future. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

The Effects of Requiring Parental Consent for Research on Adolescents' Risk Behaviors: A Meta-analysis.

PubMed

Liu, Chao; Cox, Ronald B; Washburn, Isaac J; Croff, Julie M; Crethar, Hugh C

2017-07-01

Requiring parental consent may result in sampling biases that confound scientific conclusions and stifle the representation of children most at risk for adverse outcomes. This study aims to investigate whether active parental consent, compared with passive parental consent, creates a bias in response rate, demographic makeup, and adverse outcomes in adolescent samples. A meta-analysis was performed on peer-reviewed articles and unpublished dissertations from 1975 to 2016 in five computerized databases ERIC, PsycINFO, MEDLINE, PubMed and ProQuest. Quantitative studies were retained if they included the following keywords: active consent (or informed consent or parental consent), passive consent (or waiver of consent), risk behavior, adolescen*. Fifteen studies were identified with a total number of 104,074 children. Results showed (1) response rates were significantly lower for studies using active consent procedure than those using passive consent procedure (Z = 3.05, p = .002); (2) more females, younger participants, and less African-Americans were included in studies using active consent procedures than studies using passive procedures (Z = -2.73, p = .006; Z = -12.06, p < .00001; Z = 2.19, p = .03, respectively); (3) studies with passive consent procedures showed higher rates of self-reported substance use than studies using active consent procedures (Z = 3.07, p = .002). Requiring active parental consent can lead to a systematic bias in the sample where the population under study is misrepresented. Institutional review board committees should collaborate with researchers to find solutions that protect minors without silencing the voice of high-risk youth in the literature. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Use of Passive Diffusion Samplers for Monitoring Volatile Organic Compounds in Ground Water

USGS Publications Warehouse

Harte, Philip T.; Brayton, Michael J.; Ives, Wayne

2000-01-01

Passive diffusion samplers have been tested at a number of sites where volatile organic compounds (VOC's) are the principal contaminants in ground water. Test results generally show good agreement between concentrations of VOC's in samples collected with diffusion samplers and concentrations in samples collected by purging the water from a well. Diffusion samplers offer several advantages over conventional and low-flow ground-water sampling procedures: * Elimination of the need to purge a well before collecting a sample and to dispose of contaminated water. * Elimination of cross-contamination of samples associated with sampling with non-dedicated pumps or sample delivery tubes. * Reduction in sampling time by as much as 80 percent of that required for 'purge type' sampling methods. * An increase in the frequency and spatial coverage of monitoring at a site because of the associated savings in time and money. The successful use of diffusion samplers depends on the following three primary factors: (1) understanding site conditions and contaminants of interest (defining sample objectives), (2) validating of results of diffusion samplers against more widely acknowledged sampling methods, and (3) applying diffusion samplers in the field.

Rapid quantification of pharmaceuticals and pesticides in passive samplers using ultra high performance liquid chromatography coupled to high resolution mass spectrometry.

PubMed

Wille, Klaas; Claessens, Michiel; Rappé, Karen; Monteyne, Els; Janssen, Colin R; De Brabander, Hubert F; Vanhaecke, Lynn

2011-12-23

The presence of both pharmaceuticals and pesticides in the aquatic environment has become a well-known environmental issue during the last decade. An increasing demand however still exists for sensitive and reliable monitoring tools for these rather polar contaminants in the marine environment. In recent years, the great potential of passive samplers or equilibrium based sampling techniques for evaluation of the fate of these contaminants has been shown in literature. Therefore, we developed a new analytical method for the quantification of a high number of pharmaceuticals and pesticides in passive sampling devices. The analytical procedure consisted of extraction using 1:1 methanol/acetonitrile followed by detection with ultra-high performance liquid chromatography coupled to high resolution and high mass accuracy Orbitrap mass spectrometry. Validation of the analytical method resulted in limits of quantification and recoveries ranging between 0.2 and 20 ng per sampler sheet and between 87.9 and 105.2%, respectively. Determination of the sampler-water partition coefficients of all compounds demonstrated that several pharmaceuticals and most pesticides exert a high affinity for the polydimethylsiloxane passive samplers. Finally, the developed analytical methods were used to measure the time-weighted average (TWA) concentrations of the targeted pollutants in passive samplers, deployed at eight stations in the Belgian coastal zone. Propranolol, carbamazepine and seven pesticides were found to be very abundant in the passive samplers. These obtained long-term and large-scale TWA concentrations will contribute in assessing the environmental and human health risk of these emerging pollutants. Copyright © 2011 Elsevier B.V. All rights reserved.

Active learning for clinical text classification: is it better than random sampling?

PubMed

Figueroa, Rosa L; Zeng-Treitler, Qing; Ngo, Long H; Goryachev, Sergey; Wiechmann, Eduardo P

2012-01-01

This study explores active learning algorithms as a way to reduce the requirements for large training sets in medical text classification tasks. Three existing active learning algorithms (distance-based (DIST), diversity-based (DIV), and a combination of both (CMB)) were used to classify text from five datasets. The performance of these algorithms was compared to that of passive learning on the five datasets. We then conducted a novel investigation of the interaction between dataset characteristics and the performance results. Classification accuracy and area under receiver operating characteristics (ROC) curves for each algorithm at different sample sizes were generated. The performance of active learning algorithms was compared with that of passive learning using a weighted mean of paired differences. To determine why the performance varies on different datasets, we measured the diversity and uncertainty of each dataset using relative entropy and correlated the results with the performance differences. The DIST and CMB algorithms performed better than passive learning. With a statistical significance level set at 0.05, DIST outperformed passive learning in all five datasets, while CMB was found to be better than passive learning in four datasets. We found strong correlations between the dataset diversity and the DIV performance, as well as the dataset uncertainty and the performance of the DIST algorithm. For medical text classification, appropriate active learning algorithms can yield performance comparable to that of passive learning with considerably smaller training sets. In particular, our results suggest that DIV performs better on data with higher diversity and DIST on data with lower uncertainty.

Active learning for clinical text classification: is it better than random sampling?

PubMed Central

Figueroa, Rosa L; Ngo, Long H; Goryachev, Sergey; Wiechmann, Eduardo P

2012-01-01

Objective This study explores active learning algorithms as a way to reduce the requirements for large training sets in medical text classification tasks. Design Three existing active learning algorithms (distance-based (DIST), diversity-based (DIV), and a combination of both (CMB)) were used to classify text from five datasets. The performance of these algorithms was compared to that of passive learning on the five datasets. We then conducted a novel investigation of the interaction between dataset characteristics and the performance results. Measurements Classification accuracy and area under receiver operating characteristics (ROC) curves for each algorithm at different sample sizes were generated. The performance of active learning algorithms was compared with that of passive learning using a weighted mean of paired differences. To determine why the performance varies on different datasets, we measured the diversity and uncertainty of each dataset using relative entropy and correlated the results with the performance differences. Results The DIST and CMB algorithms performed better than passive learning. With a statistical significance level set at 0.05, DIST outperformed passive learning in all five datasets, while CMB was found to be better than passive learning in four datasets. We found strong correlations between the dataset diversity and the DIV performance, as well as the dataset uncertainty and the performance of the DIST algorithm. Conclusion For medical text classification, appropriate active learning algorithms can yield performance comparable to that of passive learning with considerably smaller training sets. In particular, our results suggest that DIV performs better on data with higher diversity and DIST on data with lower uncertainty. PMID:22707743

Nicotine cut-off value in human hair as a tool to distinguish active from passive smokers: A cross-sectional study in Japanese men.

PubMed

Tsuji, Masayoshi; Kanda, Hideyuki; Hayakawa, Takehito; Mori, Yayoi; Ito, Teruna; Hidaka, Tomoo; Kakamu, Takeyasu; Kumagai, Tomohiro; Osaki, Yoneatsu; Kawazoe, Miki; Sato, Sei; Fukushima, Tetsuhito

2017-07-19

Nicotine concentration in hair is a useful marker of tobacco exposure. Detection of nicotine in the hair of non-smokers indicates passive smoking. Accurate measurement of nicotine among active and passive smokers can help in smoking cessation programs or programs designed to prevent secondhand smoke exposure. To establish, using high-performance liquid chromatography-ultraviolet detection (HPLC/UV), a hair nicotine cut-off value to distinguish active from passive smokers. Hair samples were collected from randomly chosen Japanese men (n= 192) between 2009 and 2011. Nicotine and cotinine levels in hair were measured using HPLC/UV with column-switching. T-tests and chi-square tests were performed to compare active and passive smokers, while receiver operating characteristic curves were used to evaluate the effectiveness of the cut-off value. There were 69 active smokers and 123 passive smokers. The nicotine and cotinine concentrations in hair were significantly higher in active than in passive smokers (p< 0.01). The area under the curve for nicotine was 0.92. A hair nicotine cut-off value of 5.68 ng/mg, with a sensitivity of 94.2% and specificity of 87.0%, was identified as the optimal cut-off value for separating active from passive smokers. Nicotine and cotinine concentrations in hair clearly distinguished active from passive smokers.

In planta passive sampling devices for assessing subsurface chlorinated solvents.

PubMed

Shetty, Mikhil K; Limmer, Matt A; Waltermire, Kendra; Morrison, Glenn C; Burken, Joel G

2014-06-01

Contaminant concentrations in trees have been used to delineate groundwater contaminant plumes (i.e., phytoscreening); however, variability in tree composition hinders accurate measurement of contaminant concentrations in planta, particularly for long-term monitoring. This study investigated in planta passive sampling devices (PSDs), termed solid phase samplers (SPSs) to be used as a surrogate tree core. Characteristics studied for five materials included material-air partitioning coefficients (Kma) for chlorinated solvents, sampler equilibration time and field suitability. The materials investigated were polydimethylsiloxane (PDMS), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyoxymethylene (POM) and plasticized polyvinyl chloride (PVC). Both PDMS and LLDPE samplers demonstrated high partitioning coefficients and diffusivities and were further tested in greenhouse experiments and field trials. While most of the materials could be used for passive sampling, the PDMS SPSs performed best as an in planta sampler. Such a sampler was able to accurately measure trichloroethylene (TCE) and tetrachloroethylene (PCE) concentrations while simultaneously incorporating simple operation and minimal impact to the surrounding property and environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Passive vs. Parachute System Architecture for Robotic Sample Return Vehicles

NASA Technical Reports Server (NTRS)

Maddock, Robert W.; Henning, Allen B.; Samareh, Jamshid A.

2016-01-01

The Multi-Mission Earth Entry Vehicle (MMEEV) is a flexible vehicle concept based on the Mars Sample Return (MSR) EEV design which can be used in the preliminary sample return mission study phase to parametrically investigate any trade space of interest to determine the best entry vehicle design approach for that particular mission concept. In addition to the trade space dimensions often considered (e.g. entry conditions, payload size and mass, vehicle size, etc.), the MMEEV trade space considers whether it might be more beneficial for the vehicle to utilize a parachute system during descent/landing or to be fully passive (i.e. not use a parachute). In order to evaluate this trade space dimension, a simplified parachute system model has been developed based on inputs such as vehicle size/mass, payload size/mass and landing requirements. This model works in conjunction with analytical approximations of a mission trade space dataset provided by the MMEEV System Analysis for Planetary EDL (M-SAPE) tool to help quantify the differences between an active (with parachute) and a passive (no parachute) vehicle concept.

Remedy performance monitoring at contaminated sediment sites using profiling solid phase microextraction (SPME) polydimethylsiloxane (PDMS) fibers.

PubMed

Thomas, Courtney; Lampert, David; Reible, Danny

2014-03-01

Passive sampling using polydimethylsiloxane (PDMS) profilers was evaluated as a tool to assess the performance of in situ sediment remedies at three locations, Chattanooga Creek (Chattanooga, TN), Eagle Harbor (Bainbridge Island, WA) and Hunter's Point (San Francisco, CA). The remedy at the first two locations was capping over PAH contaminated sediments while at Hunter's Point, the assessment was part of an in situ treatment demonstration led by R. G. Luthy (Stanford University) using activated carbon mixed into PCB contaminated sediments. The implementation and results at these contaminated sediment sites were used to illustrate the utility and usefulness of the passive sampling approach. Two different approaches were employed to evaluate kinetics of uptake onto the sorbent fibers. At the capping sites, the passive sampling approach was employed to measure intermixing during cap placement, contamination migration into the cap post-placement and recontamination over time. At the in situ treatment demonstration site, reductions in porewater concentrations in treated versus untreated sediments were compared to measurements of bioaccumulation of PCBs in Neanthes arenaceodentata.

Size, time, and asynchrony matter: the species-area relationship for parasites of freshwater fishes.

PubMed

Zelmer, Derek A

2014-10-01

The tendency to attribute species-area relationships to "island biogeography" effectively bypasses the examination of specific mechanisms that act to structure parasite communities. Positive covariation between fish size and infrapopulation richness should not be examined within the typical extinction-based paradigm, but rather should be addressed from the standpoint of differences in colonization potential among individual hosts. Although most mechanisms producing the aforementioned pattern constitute some variation of passive sampling, the deterministic aspects of the accumulation of parasite individuals by fish hosts makes untenable the suggestion that infracommunities of freshwater fishes are stochastic assemblages. At the component community level, application of extinction-dependent mechanisms might be appropriate, given sufficient time for colonization, but these structuring forces likely act indirectly through their effects on the host community to increase the probability of parasite persistence. At all levels, the passive sampling hypothesis is a relevant null model. The tendency for mechanisms that produce species-area relationships to produce nested subset patterns means that for most systems, the passive sampling hypothesis can be addressed through the application of appropriate null models of nested subset structure.

Assessment of passive knee stiffness and viscosity in individuals with spinal cord injury using pendulum test.

PubMed

Joghtaei, Mahmoud; Arab, Amir Massoud; Hashemi-Nasl, Hamed; Joghataei, Mohammad Taghi; Tokhi, Mohammad Osman

2015-03-01

Stiffness and viscosity represent passive resistances to joint motion related with the structural properties of the joint tissue and of the musculotendinous complex. Both parameters can be affected in patients with spinal cord injury (SCI). The purpose of this study was to measure passive knee stiffness and viscosity in patients with SCI with paraplegia and healthy subjects using Wartenberg pendulum test. Non-experimental, cross-sectional, case-control design. An outpatient physical therapy clinic, University of social welfare and Rehabilitation Science, Iran. A sample of convenience sample of 30 subjects participated in the study. Subjects were categorized into two groups: individuals with paraplegic SCI (n = 15, age: 34.60 ± 9.18 years) and 15 able-bodied individuals as control group (n = 15, age: 30.66 ± 11.13 years). Not applicable. Passive pendulum test of Wartenberg was used to measure passive viscous-elastic parameters of the knee (stiffness, viscosity) in all subjects. Statistical analysis (independent t-test) revealed significant difference in the joint stiffness between healthy subjects and those with paraplegic SCI (P = 0.01). However, no significant difference was found in the viscosity between two groups (P = 0.17). Except for first peak flexion angle, all other displacement kinematic parameters exhibited no statistically significant difference between normal subjects and subjects with SCI. Patients with SCI have significantly greater joint stiffness compared to able-bodied subjects.

Referring Physicians' Tendency to Collaborate With Radiologists in Managing Contrast Media-Related Risk Factors.

PubMed

İmamoğlu, Hakan; Doğan, Serap; Erdoğan, Nuri

2018-02-01

The aim of this study was to investigate the tendency of referring physicians to collaborate with radiologists in managing contrast media (CM)-related risk factors. The study was conducted at a single academic hospital. Among 150 referring physicians from various specialties, 51 referring physicians (34%) responded to the invitation letter asking for an interview with a radiologist. During the interview, a modified form of the Control Preferences Scale was administered, in which there were five preferences (each displayed on a separate card) that ranged from the fully active to fully passive involvement of referring physicians in managing CM-related risk factors. A descriptive analysis was performed through categorization of the results depending on the respondents' two most preferred roles. Thirty-six referring physicians (70.5%) preferred a collaborative role, and 15 (29.4%) preferred a noncollaborative role (i.e., remained on either the fully active or fully passive side). Among the referring physicians who preferred a collaborative role, the most common response (n = 15 [29.4%]) was collaborative-active. Referring physicians at the authors' institution have basic cognitive and motivational-affective tone toward collaboration in future teamwork aimed at the management of CM-related risk factors. A modified form of the Control Preferences Scale, as in this study, can be used to investigate the tendency of referring physicians to collaborate with radiologists. The results are discussed from ethical and legal perspectives. Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Prevalence and Associated Factors of Passive Smoking among Women in Jilin Province, China: A Cross-Sectional Study

PubMed Central

Li, Zhijun; Yao, Yan; Yu, Yaqin; Shi, Jieping; Liu, Yawen; Tao, Yuchun; Kou, Changgui; Zhang, Huiping; Han, Weiqing; Yin, Yutian; Jiang, Lingling; Li, Bo

2015-01-01

Background: The present study aimed to investigate the prevalence and associated socio-demographic factors of passive smoking among women in Jilin Province, China. Methods: A cross-sectional study was conducted in 2012, using a self-reported questionnaire interview. A representative sample of 9788 non-smoking women aged 18–79 years was collected in Jilin Province of China by a multistage stratified random cluster sampling design. Descriptive data analysis and 95% confidence intervals (CI) of prevalence/frequency were conducted. Multivariable logistic regressions were used to examine the associated socio-demographic factors of passive smoking. Results: The overall prevalence of passive smoking among non-smoking women in Jilin Province was 60.6% (95% CI: 59.3–61.8), 58.3% (95% CI: 56.7–59.9) from urban areas, and 63.4% (95% CI: 61.6–65.3) from rural areas. Twenty-six percent (95% CI: 24.9–27.1) of the non-smoking women reported daily passive smoking, of which 42.9% (95% CI: 41.6–44.1) reported passive smoking at home, and 5.1% (95% CI: 4.5–5.7) reported passive smoking in restaurants. Women in urban areas were less likely to be passive smokers than those in rural ones (OR-Odds Ratio: 0.825, 95% CI: 0.729–0.935), elderly women were less likely to be passive smokers than younger women (55–64 years OR: 0.481, 95% CI: 0.342–0.674; 65–79 years OR: 0.351, 95% CI: 0.241–0.511). Seperated/divorced women were less likely to be passive smokers (OR: 0.701, 95% CI: 0.500–0.982), and widowed women (OR: 0.564, 95%CI: 0.440–0.722), as the married were the reference group. Retired women second-hand smoked due to environmental causes significantly less than manual workers (OR: 0.810, 95% CI: 0.708–0.928). Women with a monthly family income of more than 5000 RMB were less likely to be passive smokers than those with an income less than 500 RMB (OR: 0.615, 95% CI: 0.432–0.876). Conclusions: The prevalence of passive smoking is lower than that reported in 2010 Global Adult Tobacco Survey (GATS) China, but passive smoking is still prevalent and has been an acute public health problem among non-smoking women in Jilin Province, China. Our findings suggest an urgent need for tobacco control and the efforts of public health should be both comprehensive and focus on high-risk populations in Jilin Province, China. PMID:26529002

Partitioning of fluoranthene between free and bound forms in stormwater runoff and other urban discharges using passive dosing.

PubMed

Birch, Heidi; Mayer, Philipp; Lützhøft, Hans-Christian Holten; Mikkelsen, Peter Steen

2012-11-15

Partitioning of fluoranthene in stormwater runoff and other urban discharges was measured by a new analytical method based on passive dosing. Samples were collected at the inlet (n = 11) and outlet (n = 8) from a stormwater retention pond in Albertslund (Denmark), and for comparison samples were also obtained at a municipal wastewater treatment plant, a power plant, a contaminated site and a waste deposit in Copenhagen (n = 1 at each site). The freely dissolved concentration of (14)C-fluoranthene in the samples was controlled by equilibrium partitioning from a pre-loaded polymer and the total sample concentration measured. The measurements yielded free fractions of fluoranthene in stormwater in the range 0.04-0.15 in the inlet during the first part of the runoff events increasing to 0.3-0.5 at the end of the events and in the outlet from the retention pond. The enhanced capacity of the different stormwater samples for carrying fluoranthene was 2-23 relative to pure water and decreasing during rain events. The enhanced capacity of stormwater showed a different relationship with suspended solid concentrations than the other types of urban discharges. Partitioning of fluoranthene to dissolved organic carbon was lower than partitioning to particulate organic carbon. Partitioning of fluoranthene to particulate organic matter in the 19 stormwater samples yielded a log K(POM) of 5.18. The presented results can be used in stormwater quality modeling and assessment of efficiency of stormwater treatment systems. This work also shows the potential of the passive dosing method to obtain conversion factors between total concentrations, which are needed for comparison with water quality criteria, and freely dissolved concentrations, which are more related to toxicity and obtained by the use of most passive samplers. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development and Validation of a SPME-GC-MS Method for In situ Passive Sampling of Root Volatiles from Glasshouse-Grown Broccoli Plants Undergoing Below-Ground Herbivory by Larvae of Cabbage Root Fly, Delia radicum L.

PubMed

Deasy, William; Shepherd, Tom; Alexander, Colin J; Birch, A Nicholas E; Evans, K Andrew

2016-11-01

Research on plant root chemical ecology has benefited greatly from recent developments in analytical chemistry. Numerous reports document techniques for sampling root volatiles, although only a limited number describe in situ collection. To demonstrate a new method for non-invasive in situ passive sampling using solid phase micro extraction (SPME), from the immediate vicinity of growing roots. SPME fibres inserted into polyfluorotetrafluoroethylene (PTFE) sampling tubes located in situ which were either perforated, covered with stainless steel mesh or with microporous PTFE tubing, were used for non-invasive sub-surface sampling of root volatiles from glasshouse-grown broccoli. Sampling methods were compared with above surface headspace collection using Tenax TA. The roots were either mechanically damaged or infested with Delia radicum larvae. Principal component analysis (PCA) was used to investigate the effect of damage on the composition of volatiles released by broccoli roots. Analyses by gas chromatography-mass spectrometry (GC-MS) with SPME and automated thermal desorption (ATD) confirmed that sulphur compounds, showing characteristic temporal emission patterns, were the principal volatiles released by roots following insect larval damage. Use of SPME with in situ perforated PTFE sampling tubes was the most robust method for out-of-lab sampling. This study describes a new method for non-invasive passive sampling of volatiles in situ from intact and insect damaged roots using SPME. The method is highly suitable for remote sampling and has potential for wide application in chemical ecology/root/soil research. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Body Image Concerns in Young Girls: The Role of Peers and Media Prior to Adolescence

ERIC Educational Resources Information Center

Dohnt, Hayley K.; Tiggemann, Marika

2006-01-01

Peer and media influences have been identified as important conveyors of socio-cultural ideals in adolescent and preadolescent samples. This study aims to explore peer and media influences in the body image concerns and dieting awareness of younger girls, aged 5-8 years. A sample of 128 girls was recruited from the first 4 years of formal…

PRIMUS/NAVCARE Cost-Effectiveness Analysis

DTIC Science & Technology

1991-04-08

ICD-9-CM diagnosis codes that occurred most frequently in the medical record sample - 328.9 ( otitis media , unspecified) and 465.9 (upper...when attention is focused upon a single diagnosis, the MTF CECs are no longer consistently above the PRIMUS CECs. For otitis media , the MTF CECs are...CHAMPUS-EQUIVALENT COSTS FOR SELECTED DIAGNOSES 328.9 OTITIS MEDIA , UNSPECIFIED Sample Size Mean 95% Confidence Interval Upper Limit Lower

Adaptive Fusion of Information for Seeing into Ordos Basin, China: A China-Germany-US Joint Venture.

NASA Astrophysics Data System (ADS)

Yeh, T. C. J.; Yin, L.; Sauter, M.; Hu, R.; Ptak, T.; Hou, G. C.

2014-12-01

Adaptive fusion of information for seeing into geological basins is the theme of this joint venture. The objective of this venture is to initiate possible collaborations between scientists from China, Germany, and US to develop innovative technologies, which can be utilized to characterize geological and hydrological structures and processes as well as other natural resources in regional scale geological basins of hundreds of thousands of kilometers (i.e., the Ordos Basin, China). This adaptive fusion of information aims to assimilate active (manmade) and passive (natural) hydrologic and geophysical tomography surveys to enhance our ability of seeing into hydrogeological basins at the resolutions of our interests. The active hydrogeophysical tomography refers to recently developed hydraulic tomgoraphic surveys by Chinese and German scientists, as well as well-established geophysical tomography surveys (such as electrical resistivity tomography, cross-borehole radars, electrical magnetic surveys). These active hydrogeophysical tomgoraphic surveys have been proven to be useful high-resolution surveys for geological media of tens and hundreds of meters wide and deep. For basin-scale (i.e., tens and hundreds of kilometers) problems, their applicabilities are however rather limited. The passive hydrogeophysical tomography refers to unexplored technologies that exploit natural stimuli as energy sources for tomographic surveys, which include direct lightning strikes, groundwater level fluctuations due to earthquakes, river stage fluctuations, precipitation storms, barometric pressure variations, and long term climate changes. These natural stimuli are spatially varying, recurrent, and powerful, influencing geological media over great distances and depths (e.g., tens and hundreds of kilometers). Monitoring hydrological and geophysical responses of geological media to these stimuli at different locations is tantamount to collecting data of naturally occurring tomographic surveys. Exploiting natural stimuli as tomographic surveys is a novel concept for cost-effective characterization and monitor of subsurface processes in regional-scale basins at great depths.

Development and validation of a microchip pulsed laser for ESA space altimeters

NASA Astrophysics Data System (ADS)

Couto, Bruno; Abreu, Hernâni; Gordo, Paulo; Amorim, António

2016-10-01

The development and validation of small size laser sources for space based range finding is of crucial importance to the development of miniature LIDAR devices for European space missions, particularly for planet lander probes. In this context, CENTRA-SIM is developing a passively q-switched microchip laser in the 1.5μm wavelength range. Pulses in the order of 2 ns and 100μJ were found to be suitable for range finding for small landing platforms. Both glass and crystalline Yb-Er doped active media are commonly available. Crystalline media present higher thermal conductivity and hardness, which allows for higher pumping intensities. However, glass laser media present longer laser upper-state lifetime and 99% Yb-Er transfer efficiency make phosphate glasses the typically preferred host for this type of application. In addition to this, passively q-switched microchip lasers with Yb-Er doped phosphate glass have been reported to output >100μJ pulses while their crystalline host counterparts achieve a few tens of μJ at best. Two different types of rate equation models have been found: microscopic quantities based models and macroscopic quantities based models. Based on the works of Zolotovskaya et al. and Spühler et al, we have developed a computer model that further exploits the equivalence between the two types of approaches. The simulation studies, using commercial available components allowed us to design a compact laser emitting 80μJ pulses with up to 30kW peak power and 1 to 2 ns pulse width. We considered EAT14 Yb-Er doped glass as active medium and Co2+:MgAl2O4 as saturable absorber. The active medium is pumped by a 975nm semiconductor laser focused into a 200μm spot. Measurements on an experimental test bench to validate the numerical model were carried out. Several different combinations of, saturable absorber length and output coupling were experimented.

Media exposure and parental mediation on fast-food consumption among children in metropolitan and suburban Indonesian.

PubMed

Lwin, May O; Malik, Shelly; Ridwan, Hardinsyah; Au, Cyndy Sook Sum

2017-01-01

Fast-food companies have been reproached for rising obesity levels due to aggressive marketing tactics targeted at children. They have countered that parents should be held responsible considering their critical role as nutritional gatekeepers. This study examined the comparative effects of media exposure and parental mediation on Indonesian children's fast food consumption and how the effects compare in the metropolitan versus suburban areas. The sample consisted of 394 child-mother pairs comprising grade three and four children and their mothers from two schools each in Jakarta and Bogor representing 40.9% metropolitan sample and 59.1% suburban sample, respectively. The children completed a guided inclass survey, while the mothers completed a paper-and-pen survey at home. Measures comprised children's weekly media exposure to broadcast media, computer and mobile games, print media, and online and social media, active and restrictive parental mediation strategies, children's fast food consumption and nutrition knowledge. The relationship of media exposure and parental mediation with children's fast food consumption was analyzed using Structural Equation Modelling. Fast food consumption was positively influenced by exposure to broadcast media among metropolitan children, and by exposure to online and social media among suburban children. Active parental mediation was related to lower fast food consumption, but only for suburban children. Active parental mediation is critical in preventing fast food consumption. The media play a key role in influencing fast food consumption, and hence, literacy education is important to alleviate the adverse effects of exposure to junk food marketing.

Invited commentary: recruiting for epidemiologic studies using social media.

PubMed

Allsworth, Jenifer E

2015-05-15

Social media-based recruitment for epidemiologic studies has the potential to expand the demographic and geographic reach of investigators and identify potential participants more cost-effectively than traditional approaches. In fact, social media are particularly appealing for their ability to engage traditionally "hard-to-reach" populations, including young adults and low-income populations. Despite their great promise as a tool for epidemiologists, social media-based recruitment approaches do not currently compare favorably with gold-standard probability-based sampling approaches. Sparse data on the demographic characteristics of social media users, patterns of social media use, and appropriate sampling frames limit our ability to implement probability-based sampling strategies. In a well-conducted study, Harris et al. (Am J Epidemiol. 2015;181(10):737-746) examined the cost-effectiveness of social media-based recruitment (advertisements and promotion) in the Contraceptive Use, Pregnancy Intention, and Decisions (CUPID) Study, a cohort study of 3,799 young adult Australian women, and the approximate representativeness of the CUPID cohort. Implications for social media-based recruitment strategies for cohort assembly, data accuracy, implementation, and human subjects concerns are discussed. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography.

PubMed

D'Autry, Ward; Zheng, Chao; Wolfs, Kris; Yarramraju, Sitaramaraju; Hoogmartens, Jos; Van Schepdael, Ann; Adams, Erwin

2011-06-01

Static headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS-gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthetic Constraint of Ecosystem C Models Using Radiocarbon and Net Primary Production (NPP) in New Zealand Grazing Land

NASA Astrophysics Data System (ADS)

Baisden, W. T.

2011-12-01

Time-series radiocarbon measurements have substantial ability to constrain the size and residence time of the soil C pools commonly represented in ecosystem models. Radiocarbon remains unique in the ability to constrain the large stabilized C pool with decadal residence times. Radiocarbon also contributes usefully to constraining the size and turnover rate of the passive pool, but typically struggles to constrain pools with residence times less than a few years. Overall, the number of pools and associated turnover rates that can be constrained depends upon the number of time-series samples available, the appropriateness of chemical or physical fractions to isolate unequivocal pools, and the utility of additional C flux data to provide additional constraints. In New Zealand pasture soils, we demonstrate the ability to constrain decadal turnover times with in a few years for the stabilized pool and reasonably constrain the passive fraction. Good constraint is obtained with two time-series samples spaced 10 or more years apart after 1970. Three or more time-series samples further improve the level of constraint. Work within this context shows that a two-pool model does explain soil radiocarbon data for the most detailed profiles available (11 time-series samples), and identifies clear and consistent differences in rates of C turnover and passive fraction in Andisols vs Non-Andisols. Furthermore, samples from multiple horizons can commonly be combined, yielding consistent residence times and passive fraction estimates that are stable with, or increase with, depth in different sites. Radiocarbon generally fails to quantify rapid C turnover, however. Given that the strength of radiocarbon is estimating the size and turnover of the stabilized (decadal) and passive (millennial) pools, the magnitude of fast cycling pool(s) can be estimated by subtracting the radiocarbon-based estimates of turnover within stabilized and passive pools from total estimates of NPP. In grazing land, these estimates can be derived primarily from measured aboveground NPP and calculated belowground NPP. Results suggest that only 19-36% of heterotrophic soil respiration is derived from the soil C with rapid turnover times. A final logical step in synthesis is the analysis of temporal variation in NPP, primarily due to climate, as driver of changes in plant inputs and resulting in dynamic changes in rapid and decadal soil C pools. In sites with good time series samples from 1959-1975, we examine the apparent impacts of measured or modelled (Biome-BGC) NPP on soil Δ14C. Ultimately, these approaches have the ability to empirically constrain, and provide limited verification, of the soil C cycle as commonly depicted ecosystem biogeochemistry models.

Coupling passive air sampling with emission estimates and chemical fate modeling for persistent organic pollutants (POPs): a feasibility study for Northern Europe.

PubMed

Gioia, Rosalinda; Sweetman, Andy J; Jones, Kevin C

2007-04-01

Passive air samplers (polyurethane foam disks) were deployed at 23 background locations along a broadly west-east transect in 8 northern European countries and analyzed for PCBs, PBDEs, PAHs, and a range of organochlorine pesticides (HCB, DDTs, and DDEs). PCBs and PAHs were highest at the center of the transect (Denmark) and lowest in northern Norway. HCB was relatively uniformly distributed, reflecting its persistence and high degree of mixing in air. Higher DDE and DDT levels occurred in Eastern Europe and at several sites in Central Europe. PBDE levels were generally similar at all sites, but lower for some locations in Eastern Europe and Ireland. Emissions information for PCBs, HCB, and PBDEs was used as input for a multi-media chemical fate model, to generate predicted air concentrations and compare with these measured values. Different scenarios were highlighted by this exercise: (i) country and compound combinations where the national inventory gave predicted air concentrations in close agreement with those measured (e.g., PCBs in the UK); (ii) country and compound combinations where predicted concentrations were well below those measured, but where advection of emissions from elsewhere is likely to be important (e.g., PCBs in Norway); (iii) consistent underestimation of compound concentrations by the emissions modeling (i.e., HCB); and (iv) general overestimation of ambient concentrations (i.e., PBDEs). Air mass trajectory analysis showed the likely role of long-range atmospheric transport (LRAT) on national levels. In general, advection from the south and west of Europe appeared to contribute to ambient POPs levels for countries in the center and northeast of the transect. Guidelines are presented as to how countries that want to assess their POPs source inventories can do so with this relatively cheap initial screening approach.

'Born in Michigan? You're in the biobank': engaging population biobank participants through Facebook advertisements.

PubMed

Platt, J E; Platt, T; Thiel, D; Kardia, S L R

2013-01-01

Despite a broad call for biobanks to use social media, data is lacking regarding the capacity of social media tools, especially advertising, to engage large populations on this topic. We used Facebook advertising to engage Michigan residents about the BioTrust for Health. We conducted a low-budget (

‘Born in Michigan? You’re in the Biobank’: Engaging Population Biobank Participants through Facebook Advertisements

PubMed Central

Platt, J.E.; Platt, T.; Thiel, D.; Kardia, S.L.R.

2016-01-01

Background/Aims Despite a broad call for biobanks to use social media, data is lacking regarding the capacity of social media tools, especially advertising, to engage large populations on this topic. Methods We used Facebook advertising to engage Michigan residents about the BioTrust for Health. We conducted a low-budget (

[Tobacco smoke and risk of bacterial infection].

PubMed

Trosini-Desert, V; Germaud, P; Dautzenberg, B

2004-06-01

Tobacco smoke is a proven risk factor for bacterial infection. In adults without COPD, smoking is associated with a significant increase in the relative risk (RR) of pneumonia (RR=2.97; 95% CI 1.52-5.81), S pneumoniae pneumonia (RR=2.50; 95% IC 1.50-5.10), Legionella infection (RR=3.75; 95% CI 2.17-6.17). Smoking has clearly been shown to be associated with an increased risk of tuberculosis (RR=2.60; 95% CI 2,20-3,20), and also with increased incidence of post-operative infections. In young children whose parents smoke, passive exposure to tobacco smoke is associated with an increased relative risk of seasonal infections (RR=1.7; CI 95% 1.55-1.91) and recurrent otitis media (RR=1.48; 95% CI 1.08-2.04). Passive smoking also increases risk of pneumonia in adults (RR=2.5; CI 95% 1.2-5.1). Plausible explanations of the increased risk of infection in active or passive smokers include increased bacterial adherence, decrease of lung and nasal clearance, and changes in the immune response. Exposure to tobacco smoke approximately doubles the risk of infection. This increased burden of infection has significant healthcare cost implications. Each infectious episode in an individual should prompt an attempt at smoking cessation.

A Longitudinal Study of the Associations between Moral Disengagement and Active Defending versus Passive Bystanding during Bullying Situations

ERIC Educational Resources Information Center

Doramajian, Caroline; Bukowski, William M.

2015-01-01

This study investigated the prospective association between moral disengagement and bystander behaviors in bullying situations, including both defending and passive bystanding. A diverse sample of Canadian school children (N = 130; 68 boys and 62 girls; mean age = 11.36 years) participated in a three-wave longitudinal study over a 4-month period.…

En las Manos de Dios [in God's Hands]: Religious and Other Forms of Coping among Latinos with Arthritis

ERIC Educational Resources Information Center

Abraido-Lanza, Ana F.; Vasquez, Elizabeth; Echeverria, Sandra E.

2004-01-01

This study tested a theoretical model concerning religious, passive, and active coping; pain; and psychological adjustment among a sample of 200 Latinos with arthritis. Respondents reported using high levels of religious coping. A path analysis indicated that religious coping was correlated with active but not with passive coping. Religious coping…

40 CFR 1065.595 - PM sample post-conditioning and total weighing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sample media (e.g., filters) to the weighing and PM-stabilization environments. (a) Make sure the...). If those specifications are not met, leave the test sample media (e.g., filters) covered until proper.... If you use filters, you may remove them from their cassettes before or after stabilization. We...

40 CFR 1065.595 - PM sample post-conditioning and total weighing.

Code of Federal Regulations, 2013 CFR

2013-07-01

... sample media (e.g., filters) to the weighing and PM-stabilization environments. (a) Make sure the...). If those specifications are not met, leave the test sample media (e.g., filters) covered until proper.... If you use filters, you may remove them from their cassettes before or after stabilization. We...

40 CFR 1065.595 - PM sample post-conditioning and total weighing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... sample media (e.g., filters) to the weighing and PM-stabilization environments. (a) Make sure the...). If those specifications are not met, leave the test sample media (e.g., filters) covered until proper.... If you use filters, you may remove them from their cassettes before or after stabilization. We...

40 CFR 1065.595 - PM sample post-conditioning and total weighing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... sample media (e.g., filters) to the weighing and PM-stabilization environments. (a) Make sure the...). If those specifications are not met, leave the test sample media (e.g., filters) covered until proper.... If you use filters, you may remove them from their cassettes before or after stabilization. We...

40 CFR 1065.595 - PM sample post-conditioning and total weighing.

Code of Federal Regulations, 2012 CFR

2012-07-01

... sample media (e.g., filters) to the weighing and PM-stabilization environments. (a) Make sure the...). If those specifications are not met, leave the test sample media (e.g., filters) covered until proper.... If you use filters, you may remove them from their cassettes before or after stabilization. We...

QUANTIFICATION OF 2,4-D ON SOLID-PHASE EXPOSURE SAMPLING MEDIA BY LC/MS/MS

EPA Science Inventory

Three types of solid phase chemical exposure sampling media: cellulose, polyurethane foam (PUF) and XAD-2, were analyzed for 2,4-D and the amine salts of 2,4-D. Individual samples were extracted into acidified methanol and the extracts were analyzed via LC/MS/MS using electrospra...

Hybrid microfluidics combined with active and passive approaches for continuous cell separation.

PubMed

Yan, Sheng; Zhang, Jun; Yuan, Dan; Li, Weihua

2017-01-01

Microfluidics, which is classified as either active or passive, is capable of separating cells of interest from a complex and heterogeneous sample. Active methods utilise external fields such as electric, magnetic, acoustic, and optical to drive cells for separation, while passive methods utilise channel structures, intrinsic hydrodynamic forces, and steric hindrances to manipulate cells. However, when processing complex biological samples such as whole blood with rare cells, separation with a single module microfluidic device is difficult. Hybrid microfluidics is an emerging technique, which utilises active and passive methods whilst fulfilling higher requirements for stable performance, versatility, and convenience, including (i) the ability to process multi-target cells, (ii) enhanced ability for multiplexed separation, (iii) higher sensitivity, and (iv) tunability for a wider operational range. This review introduces the fundamental physics and typical formats for subclasses of hybrid microfluidic devices based on their different physical fields; presents current examples of cell sorting to highlight the advantage and usefulness of hybrid microfluidics on biomedicine, and then discusses the challenges and perspective of future development and the promising direction of research in this field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of enrichment and isolation media on the detection of Campylobacter spp. in naturally contaminated chicken samples.

PubMed

Repérant, E; Laisney, M J; Nagard, B; Quesne, S; Rouxel, S; Le Gall, F; Chemaly, M; Denis, M

2016-09-01

Investigating Campylobacter epidemiology requires adequate technique and media to ensure optimal culturing and accurate detection and isolation of Campylobacter strains. In the present study, we investigated the performances of three enrichment durations in Bolton broth (0, 24 and 48h) and compared four isolation media (mCCDA, Karmali, Butzler no. 2 and CampyFood agar (CFA)) for the detection of Campylobacter positive samples and the identification of Campylobacter species, from naturally contaminated broiler chicken samples (caeca, neck skin from carcasses, and skin from thighs). We compared our local results to those we obtained with samples from a European survey (caeca and neck skin) and a national survey (neck skin, thigh skin, and breast). Direct plating favored the detection of positive samples highly contaminated by Campylobacter (caeca and neck skin from carcasses) whatever the media. A longer enrichment reduced the rates of Campylobacter recovery except when using Butzler no. 2, more particularly for neck skin which background microflora was less important than in caeca. As a matter of fact, enrichment allowed a higher detection rate of positive samples with low Campylobacter contamination levels (breast, thigh skin), this detection being enhanced when using Butzler no. 2. When comparing the 3 other selective media, CFA was the 2nd most efficient media prior to mCCDA and Karmali. Interestingly, enrichment promoted the growth of Campylobacter coli but this promotion was least with Butzler no. 2 agar. Our study has confirmed the need to adapt the method to the types of samples for improving the detection of Campylobacter and that the method may affect the prevalence of the species. Copyright © 2016 Elsevier B.V. All rights reserved.

If Only my Leader Would just Do Something! Passive Leadership Undermines Employee Well-being Through Role Stressors and Psychological Resource Depletion.

PubMed

Barling, Julian; Frone, Michael R

2017-08-01

The goal of this study was to develop and test a sequential mediational model explaining the negative relationship of passive leadership to employee well-being. Based on role stress theory, we posit that passive leadership will predict higher levels of role ambiguity, role conflict and role overload. Invoking Conservation of Resources theory, we further hypothesize that these role stressors will indirectly and negatively influence two aspects of employee well-being, namely overall mental health and overall work attitude, through psychological work fatigue. Using a probability sample of 2467 US workers, structural equation modelling supported the model by showing that role stressors and psychological work fatigue partially mediated the negative relationship between passive leadership and both aspects of employee well-being. The hypothesized, sequential indirect relationships explained 47.9% of the overall relationship between passive leadership and mental health and 26.6% of the overall relationship between passive leadership and overall work attitude. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A new passive system for contamination-free long-distance cryo-transfer of biological tissues

NASA Astrophysics Data System (ADS)

Cheng, Tian; Plane, Florent; Søgaard Jensen, Louise Helene; van den Brandt, Ben; Comment, Arnaud; Meibom, Anders

2017-12-01

Several new analytical techniques require long-distance cryogenic transfer of samples that need to be kept at stable temperatures for long time periods, but also to be additionally contamination-free. In this study we developed a passive transfer system to fulfil those requirements. With 125mL of liquid nitrogen stored, one cryo-sectioned sample was maintained around 120±1 K and a pressure of about 3x10-7 mbar for at least 2 hours. With a total transfer weight of 5 Kg this system can be easily handled and carried by any transportation means so that the same sample can be used for different imaging centres located remotely permitting correlative studies.

Deep Sea Drilling Project

ERIC Educational Resources Information Center

Kaneps, Ansis

1977-01-01

Discusses the goals of the ocean drilling under the International Phase of Ocean Drilling, which include sampling of the ocean crust at great depths and sampling of the sedimentary sequence of active and passive continental margins. (MLH)

Design considerations of Miller oscillators for high-sensitivity QCM sensors in damping media.

PubMed

Rodriguez-Pardo, Loreto; Fariña, Jose; Gabrielli, Claude; Perrot, Hubert; Brendel, Remi

2007-10-01

In this paper, a new contribution to the design of quartz crystal oscillators for high-sensitivity microbalance sensors used in liquid media is presented. The oscillation condition for a Miller configuration was studied to work in a wide dynamic range of the resonator losses. The equations relating the values of the active and passive components with the maximum supported damping and mass were obtained. Also, the conditions to obtain a stable frequency according to the resonator damping (R(Q)), the static capacity (Cp) and the filter frequency (f(F)) were found. Under these conditions, the circuit oscillation frequency will be proportional to the resonant series frequency and does not depend on the previous parameters (R(Q), f(F), and Cp). If these conditions cannot be satisfied, the expression of the oscillation frequency is given and the discrimination of these effects is obtained through resonator frequency measurements.

Endothelial cells actively concentrate insulin during its transendothelial transport

PubMed Central

Genders, Amanda J.; Frison, Vera; Abramson, Sarah R.; Barrett, Eugene J.

2013-01-01

We examined insulin's uptake and transendothelial transport (TET) by cultured bovine aortic endothelial cells (BAECs) in order to: a) ascertain whether insulin accumulates within the cells to concentrations greater than in the media; b) compare the TET of insulin to that of inulin (using the latter as a tracer for passive transport or leak); and c) determine whether insulin's TET depended on insulin action. Using 125I-insulin at physiologic concentrations, we found that BAECs accumulate insulin >5-fold above media concentrations and that the TET of insulin, but not inulin, is saturable and requires intact PI-3-kinase and MEK-kinase signaling. We conclude that the insulin receptor and downstream signaling from the receptor regulate endothelial insulin transport. Based on comparison of the kinetics of BAEC insulin uptake with insulin TET, we suggest that insulin uptake is rate limiting for insulin TET. PMID:23350546

On TB Vaccines, Patients' Demands, and Modern Printed Media in Times of Biomedical Uncertainties: Buenos Aires, 1920-1950.

PubMed

Armus, Diego

2016-03-01

Reconstructing some of the experiences of people living with tuberculosis in Argentina in the first half of the twentieth century, as reflected not only in written and oral accounts but also in individual and collective actions, this article explores the ways in which patients came to grips with medical expertise in times of biomedical uncertainty. These negotiations, which inevitably included adaptations as well as confrontations, highlight a much less passive and submissive patient-physician relationship than is often assumed. Though patients were certainly subordinate to medical doctors' knowledge and practices, that subordination, far from absolute, was limited and often overthrown. The article focuses on patients' demands to gain access to a vaccine not approved by the medical establishment. By engaging with media organizations, the sick invoked their "right to health" in order to obtain access to experimental treatments when biomedicine was unable to deliver efficient therapies.

generation of picosecond pulses in solid-state lasers using new active media

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

Lisitsyn, V.N.; Matrosov, V.N.; Pestryakov, E.V.

Results are reported of investigations aimed at generating nanosecond radiation pulses in solid-state lasers using new active media having broad gain lines. Passive mode locking is accomplished for the first time in a BeLa:Nd/sup 3/ laser at a wavelength 1.354 microm, and in a YAG:Nd/sup 3/ laser on a 1.32-microm transition. The free lasing and mode-locking regimes were investigated in an alexandrite (BeA1/sub 2/O/sub 4/:Cr/sup 3/) laser in the 0.72-0.78-microm range and in a synchronously pumped laser on F/sub 2//sup -/ centers in LiF in the 1.12-1.24-microm region. The features of nonlinear perception of IR radiation by the eye, usingmore » a developed picosecond laser on F/sub 2//sup -/ centers, are investigated for the first time.« less

Opportunities and Constraints in Disseminating Qualitative Research in Web 2.0 Virtual Environments.

PubMed

Hays, Charles A; Spiers, Judith A; Paterson, Barbara

2015-11-01

The Web 2.0 digital environment is revolutionizing how users communicate and relate to each other, and how information is shared, created, and recreated within user communities. The social media technologies in the Web 2.0 digital ecosystem are fundamentally changing the opportunities and dangers in disseminating qualitative health research. The social changes influenced by digital innovations shift dissemination from passive consumption to user-centered, apomediated cooperative approaches, the features of which are underutilized by many qualitative researchers. We identify opportunities new digital media presents for knowledge dissemination activities including access to wider audiences with few gatekeeper constraints, new perspectives, and symbiotic relationships between researchers and users. We also address some of the challenges in embracing these technologies including lack of control, potential for unethical co-optation of work, and cyberbullying. Finally, we offer solutions to enhance research dissemination in sustainable, ethical, and effective strategies. © The Author(s) 2015.

MediaQuotient[TM]: National Survey of Family Media Habits, Knowledge, and Attitudes.

ERIC Educational Resources Information Center

Gentile, Douglas A.; Walsh, David A.

This study examined family media habits, including the use of television, movies, videos, computer and video games, the Internet, music, and print media. The study was conducted by mail with telephone follow-ups, surveying a national random sample of 527 parents of 2- to 17-year-olds who completed MediaQuotient questionnaires. Findings were…

Media Use and Adolescent Psychological Adjustment: An Examination of Gender Differences

ERIC Educational Resources Information Center

Ohannessian, Christine McCauley

2009-01-01

This study examined media use and psychological adjustment (as indicated by depression and anxiety symptomatology) in a sample of 328 14- to 16-year-old adolescents. Primary goals of the study were to explore whether media use differs by gender, whether media use is related to adolescent psychological problems, and whether media use moderates the…

Four passive sampling elements (quatrefoil)--II. Film badges for monitoring radon and its progeny.

PubMed

Tommasino, L; Tokonami, S

2011-05-01

The four passive samplers (quatrefoil) already described in a parallel paper, make it possible to obtain thin radiation sources, useful for alpha and beta counting by any passive and real-time detector. In the present paper, the applications of this quatrefoil for measuring radon gas by etch-track detectors will be described. In the case of radon measurements, different solids have been identified, with radon-sorption partition coefficients related to air from 1 to 2000. Uniquely compact radon badges can be obtained by using a layer of these solids facing an alpha track-etch detector. These radon badges make it possible to overcome most of the shortcomings of existing passive monitors. Moreover, these badges show promise for studying the radon solubility of polymer films.

Apparatus and method for quantitative assay of generic transuranic wastes from nuclear reactors

DOEpatents

Caldwell, J.T.; Kunz, W.E.; Atencio, J.D.

1982-03-31

A combination of passive and active neutron measurements which yields quantitative information about the isotopic composition of transuranic wastes from nuclear power or weapons material manufacture reactors is described. From the measurement of prompt and delayed neutron emission and the incidence of two coincidentally emitted neutrons from induced fission of fissile material in the sample, one can quantify /sup 233/U, /sup 235/U and /sup 239/Pu isotopes in waste samples. Passive coincidence counting, including neutron multiplicity measurement and determination of the overall passive neutron flux additionally enables the separate quantitative evaluation of spontaneous fission isotopes such as /sup 240/Pu, /sup 244/Cm and /sup 252/Cf, and the spontaneous alpha particle emitter /sup 241/Am. These seven isotopes are the most important constituents of wastes from nuclear power reactors and once the mass of each isotope present is determined by the apparatus and method of the instant invention, the overall alpha particle activity can be determined to better than 1 nCi/g from known radioactivity data. Therefore, in addition to the quantitative analysis of the waste sample useful for later reclamation purposes, the alpha particle activity can be determined to decide whether permanent low-level burial is appropriate for the waste sample.

Apparatus and method for quantitative assay of generic transuranic wastes from nuclear reactors

DOEpatents

Caldwell, John T.; Kunz, Walter E.; Atencio, James D.

1984-01-01

A combination of passive and active neutron measurements which yields quantitative information about the isotopic composition of transuranic wastes from nuclear power or weapons material manufacture reactors is described. From the measurement of prompt and delayed neutron emission and the incidence of two coincidentally emitted neutrons from induced fission of fissile material in the sample, one can quantify .sup.233 U, .sup.235 U and .sup.239 Pu isotopes in waste samples. Passive coincidence counting, including neutron multiplicity measurement and determination of the overall passive neutron flux additionally enables the separate quantitative evaluation of spontaneous fission isotopes such as .sup.240 Pu, .sup.244 Cm and .sup.252 Cf, and the spontaneous alpha particle emitter .sup.241 Am. These seven isotopes are the most important constituents of wastes from nuclear power reactors and once the mass of each isotope present is determined by the apparatus and method of the instant invention, the overall alpha particle activity can be determined to better than 1 nCi/g from known radioactivity data. Therefore, in addition to the quantitative analysis of the waste sample useful for later reclamation purposes, the alpha particle activity can be determined to decide whether "permanent" low-level burial is appropriate for the waste sample.

Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors: Impact of sulfur passivation on gate stack quality

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

Lei, Dian; Wang, Wei; Gong, Xiao, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org

2016-01-14

The effect of room temperature sulfur passivation of the surface of Ge{sub 0.83}Sn{sub 0.17} prior to high-k dielectric (HfO{sub 2}) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the chemical bonding at the interface of HfO{sub 2} and Ge{sub 0.83}Sn{sub 0.17}. Sulfur passivation is found to be effective in suppressing the formation of both Ge oxides and Sn oxides. A comparison of XPS results for sulfur-passivated and non-passivated Ge{sub 0.83}Sn{sub 0.17} samples shows that sulfur passivation of the GeSn surface could also suppress the surface segregation of Sn atoms. In addition, sulfur passivation reduces the interface trapmore » density D{sub it} at the high-k dielectric/Ge{sub 0.83}Sn{sub 0.17} interface from the valence band edge to the midgap of Ge{sub 0.83}Sn{sub 0.17}, as compared with a non-passivated control. The impact of the improved D{sub it} is demonstrated in Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs with sulfur passivation show improved subthreshold swing S, intrinsic transconductance G{sub m,int}, and effective hole mobility μ{sub eff} as compared with the non-passivated control. At a high inversion carrier density N{sub inv} of 1 × 10{sup 13 }cm{sup −2}, sulfur passivation increases μ{sub eff} by 25% in Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs.« less

Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings

PubMed Central

Beamer, P.I.; Sugeng, A. J.; Kelly, M.D.; Lothrop, N.; Klimecki, W.; Wilkinson, S.T.; Loh, M.

2014-01-01

Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p<0.05), whose primary source in indoor air is resuspended soil from outdoors. In the second rural community, our estimated metal concentrations in air were comparable to active air sampling measurements taken previously. This passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites. PMID:24469149

Phosphorus removal from aquaculture effluents at the Northeast Fishery Center in Lamar, Pennsylvania using iron oxide sorption media

USGS Publications Warehouse

Sibrell, Philip; Kehler, Thomas

2016-01-01

Three different iron oxide-based sorption media samples were tested for removal of phosphorus (P) from fish hatchery effluents using fixed bed processing. Two of the media samples were derived from residuals produced by the treatment of acid mine drainage, which were then compared to granular ferric hydroxide (GFH), a commercially available sorption medium. All of the media types removed from 50 to 70% of the P from the incoming aquaculture wastewater over 70–175 days of operation without regeneration. In some of the sorption trials, the GFH media showed superior adsorption in the earlier stages of the trial, but the GFH appeared to reach saturation more quickly, so that media performance was similar – at about 60% removal of P – over a longer time period of 175 days. Media regeneration tests were also conducted for both the commercial and mine drainage media, and demonstrated longer term performance, with overall P removal of 50–55%, over 223 days of total operation, with the advantages of phosphorus recycle and media reuse.

Short communication: Passive shedding of Mycobacterium avium ssp. paratuberculosis in commercial dairy goats in Brazil.

PubMed

Schwarz, D G G; Lima, M C; Barros, M; Valente, F L; Scatamburlo, T M; Rosado, N; Oliveira, C T S A M; Oliveira, L L; Moreira, M A S

2017-10-01

Goat farming is a low-cost alternative to dairy production in developing countries. In Brazil, goat production has increased in recent years due in part to the implementation of programs encouraging this activity. Mycobacterium avium ssp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a disease that causes chronic granulomatous enteritis in ruminants, but MAP transmission dynamics are still poorly understood in goats. In a previously published study of our research group, 10 dairy goat farms (467 animals) from Minas Gerais state were analyzed for MAP detection; 2 fecal cultures and 11 milk samples tested positive for MAP by conventional PCR and were confirmed by sequencing. Because no clinical signs were observed over 1 yr of monitoring, we hypothesized that these MAP-positive goats could be passive shedders. Thus, in the present study, 4 positive goats (4/13) from the previous study were purchased and feces and milk samples were collected for evaluation (twice, with an interval of 3 mo between tests) by culture of MAP, IS900 PCR, or both. All analyses were negative for MAP. At the last time point, blood samples were collected for ELISA, the animals were killed, and tissues collected for tissue culture and histopathology. At necropsy, no macroscopic lesions related to paratuberculosis were observed. Similarly, no histological changes were observed and MAP in samples stained by Ziehl-Neelsen was not detected. These animals were characterized as potential passive shedders with upward contamination of the teat canal by MAP. This is the first report of the passive shedding phenomenon in goats in Brazil and it highlights the importance of identifying these animals for control programs and to ensure the quality of dairy products. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Assessing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in air across Latin American countries using polyurethane foam disk passive air samplers.

PubMed

Schuster, Jasmin K; Harner, Tom; Fillmann, Gilberto; Ahrens, Lutz; Altamirano, Jorgelina C; Aristizábal, Beatriz; Bastos, Wanderley; Castillo, Luisa Eugenia; Cortés, Johana; Fentanes, Oscar; Gusev, Alexey; Hernandez, Maricruz; Ibarra, Martín Villa; Lana, Nerina B; Lee, Sum Chi; Martínez, Ana Patricia; Miglioranza, Karina S B; Puerta, Andrea Padilla; Segovia, Federico; Siu, May; Tominaga, Maria Yumiko

2015-03-17

A passive air sampling network has been established to investigate polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at Global Atmospheric Passive Sampling (GAPS) sites and six additional sites in the Group of Latin American and Caribbean Countries (GRULAC) region. The air sampling network covers background, agricultural, rural, and urban sites. Samples have been collected over four consecutive periods of 6 months, which started in January 2011 [period 1 (January to June 2011), period 2 (July to December 2011), period 3 (January to June 2012), and period 4 (July 2012 to January 2013)]. Results show that (i) the GAPS passive samplers (PUF disk type) and analytical methodology are adequate for measuring PCDD/F burdens in air and (ii) PCDD/F concentrations in air across the GRULAC region are widely variable by almost 2 orders of magnitude. The highest concentrations in air of Σ4-8PCDD/Fs were found at the urban site São Luis (Brazil, UR) (i.e., 2560 fg/m3) followed by the sites in São Paulo (Brazil, UR), Mendoza (Argentina, RU), and Sonora (Mexico, AG) with values of 1690, 1660, and 1610 fg/m3, respectively. Very low concentrations of PCDD/Fs in air were observed at the background site Tapanti (Costa Rica, BA), 10.8 fg/m3. This variability is attributed to differences in site characteristics and potential local/regional sources as well as meteorological influences. The measurements of PCDD/Fs in air agree well with model-predicted concentrations performed using the Global EMEP Multimedia Modeling System (GLEMOS) and emission scenario constructed on the basis of the UNEP Stockholm Convention inventory of dioxin and furan emissions.

Microbial communities in methane seep sediments along US Atlantic Margin are structured by organic matter and seepage dynamics

NASA Astrophysics Data System (ADS)

Graw, M. F.; Pohlman, J.; Treude, T.; Ruppel, C. D.; Colwell, F. S.

2016-12-01

Methane seeps are dynamic environments on continental margins where subsurface methane reaches the ocean. Microbial communities play a critical role in carbon cycling within seep sediments via organic carbon degradation, methane production, and anaerobic oxidation of methane (AOM), which consumes 20-80% of methane in seep sediments. However, biogeochemical controls on microbial community structure at seeps on a margin-wide scale remain unclear. The passive US Atlantic Margin (USAM) has been identified as a region of active methane seepage. Passive margin seeps have traditionally been understudied relative to seeps on active margins. Passive margins exhibit large cross-margin variability in organic carbon deposition and are anticipated to have divergent seep dynamics from active margins. Thus, the USAM offers a unique opportunity to investigate controls on microbial communities in seep sediments. We undertook analysis of microbial communities inhabiting seep sediments at 6 biogeochemically distinct sites along the USAM. Microbiological samples were co-located with measurements of sediment geochemistry and AOM and sulfate reduction rates. Illumina sequencing of the 16S rRNA gene, using both universal (83 samples) and archaeal-specific (64 samples) primers, and the mcrA gene (18 samples) identified 44 bacterial phyla and 7 archaeal phyla. Seeps in canyons and on open slope, likely representing high and low organic content sediments, hosted distinct communities; the former was dominated by ammonia-oxidizing Marine Group I Thaumarchaeota and the latter by mixotrophic Hadesarchaeota. Seep stability also impacted microbial community structure, and in particular the establishment of an AOM community rather than a Bathyarchaeota-dominated community. These findings contribute to understanding how microbial communities are structured within methane seep sediments and pave the way for investigating broad differences in carbon cycling between seeps on passive and active margins.

Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals

PubMed Central

Zhang, Yanjie; Clapp, Aaron

2011-01-01

Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands. PMID:22247651

Classification of light sources and their interaction with active and passive environments

NASA Astrophysics Data System (ADS)

El-Dardiry, Ramy G. S.; Faez, Sanli; Lagendijk, Ad

2011-03-01

Emission from a molecular light source depends on its optical and chemical environment. This dependence is different for various sources. We present a general classification in terms of constant-amplitude and constant-power sources. Using this classification, we have described the response to both changes in the local density of states and stimulated emission. The unforeseen consequences of this classification are illustrated for photonic studies by random laser experiments and are in good agreement with our correspondingly developed theory. Our results require a revision of studies on sources in complex media.

Evaluation of different selective media and culturing techniques for the quantification of Campylobacter ssp. from broiler litter.

PubMed

Kiess, A S; Parker, H M; McDaniel, C D

2010-08-01

Poultry is a major reservoir for Campylobacter, the leading cause of foodborne illness in the United States, but how broilers become initially colonized is still under debate. Broiler litter is a potential source, but the best technique for quantifying Campylobacter from litter is still unknown. Therefore, our objectives were to determine if certain media are more selective for quantifying Campylobacter and if enrichment allows for the detection of stressed or viable but nonculturable cells from broiler litter samples. In this trial, 5 media and 2 culturing techniques were used to enumerate Campylobacter from broiler litter. The media used were campy-Line agar (CLA), campy-cefex agar (CCA), modified CCA, Campylobacter agar plates (CAP), and modified charcoal cefoperazone deoxycholate agar. Litter samples were obtained from a commercial broiler house. Each sample was equally divided and diluted 10-fold into peptone, for direct plating, or 4-fold into Campylobacter enrichment broth. Samples diluted in peptone were direct-plated onto each media and incubated under microaerophilic conditions for 48 h at 42 degrees C. Samples diluted in enrichment broth were incubated under the same conditions for 24 h, then further diluted to 10-fold before plating. Plates from enriched samples were incubated for an additional 24 h after plating. After incubation, all plates (direct and enriched) were counted and presumptive positive colonies were confirmed using a Campylobacter latex agglutination kit. Results indicated that there was no difference in the ability of any of the selective media tested to grow Campylobacter. Direct-plated samples had a higher Campylobacter isolation rate compared with enriched samples. The CLA and CAP were able to suppress total bacterial growth better than modified charcoal cefoperazone deoxycholate, modified CCA, and CCA. The CLA and CAP were the only media able to detect total bacterial population shifts over time. In conclusion, it is important before making a final decision on a selective medium to consider the medium's ability to suppress total bacterial growth as well as isolate Campylobacter.

Laboratory calibration and field testing of the Chemcatcher-Metal for trace levels of rare earth elements in estuarine waters.

PubMed

Petersen, Jördis; Pröfrock, Daniel; Paschke, Albrecht; Broekaert, Jose A C; Prange, Andreas

2015-10-01

Little knowledge is available about water concentrations of rare earth elements (REEs) in the marine environment. The direct measurement of REEs in coastal waters is a challenging task due to their ultra-low concentrations as well as the high salt content in the water samples. To quantify these elements at environmental concentrations (pg L(-1) to low ng L(-1)) in coastal waters, current analytical techniques are generally expensive and time consuming, and require complex chemical preconcentration procedures. Therefore, an integrative passive sampler was tested as a more economic alternative sampling approach for REE analysis. We used a Chemcatcher-Metal passive sampler consisting of a 3M Empore Chelating Disk as the receiving phase, as well as a cellulose acetate membrane as the diffusion-limiting layer. The effect of water turbulence and temperature on the uptake rates of REEs was analyzed during 14-day calibration experiments by a flow-through exposure tank system. The sampling rates were in the range of 0.42 mL h(-1) (13 °C; 0.25 m s(-1)) to 4.01 mL h(-1) (13 °C; 1 m s(-1)). Similar results were obtained for the different REEs under investigation. The water turbulence was the most important influence on uptake. The uptake rates were appropriate to ascertain time-weighted average concentrations of REEs during a field experiment in the Elbe Estuary near Cuxhaven Harbor (exposure time 4 weeks). REE concentrations were determined to be in the range 0.2 to 13.8 ng L(-1), where the highest concentrations were found for neodymium and samarium. In comparison, most of the spot samples measured along the Chemcatcher samples had REE concentrations below the limit of detection, in particular due to necessary dilution to minimize the analytical problems that arise with the high salt content in marine water samples. This study was among the first efforts to measure REE levels in the field using a passive sampling approach. Our results suggest that passive samplers could be an effective tool to monitor ultra-trace concentrations of REEs in coastal waters with high salt content.

Comparison of passive diffusion bag samplers and submersible pump sampling methods for monitoring volatile organic compounds in ground water at Area 6, Naval Air Station, Whidbey Island, Washington

USGS Publications Warehouse

Huffman, Raegan L.

2002-01-01

Ground-water samples were collected in April 1999 at Naval Air Station Whidbey Island, Washington, with passive diffusion samplers and a submersible pump to compare concentrations of volatile organic compounds (VOCs) in water samples collected using the two sampling methods. Single diffusion samplers were installed in wells with 10-foot screened intervals, and multiple diffusion samplers were installed in wells with 20- to 40-foot screened intervals. The diffusion samplers were recovered after 20 days and the wells were then sampled using a submersible pump. VOC concentrations in the 10-foot screened wells in water samples collected with diffusion samplers closely matched concentrations in samples collected with the submersible pump. Analysis of VOC concentrations in samples collected from the 20- to 40-foot screened wells with multiple diffusion samplers indicated vertical concentration variation within the screened interval, whereas the analysis of VOC concentrations in samples collected with the submersible pump indicated mixing during pumping. The results obtained using the two sampling methods indicate that the samples collected with the diffusion samplers were comparable with and can be considerably less expensive than samples collected using a submersible pump.

Porous protective solid phase micro-extractor sheath

DOEpatents

Andresen, Brian D.; Randich, Erik

2005-03-29

A porous protective sheath for active extraction media used in solid phase microextraction (SPME). The sheath permits exposure of the media to the environment without the necessity of extending a fragile coated fiber from a protective tube or needle. Subsequently, the sheath can pierce and seal with GC-MS septums, allowing direct injection of samples into inlet ports of analytical equipment. Use of the porous protective sheath, within which the active extraction media is contained, mitigates the problems of: 1) fiber breakage while the fiber is extended during sampling, 2) active media coating loss caused by physical contact of the bare fiber with the sampling environment; and 3) coating slough-off during fiber extension and retraction operations caused by rubbing action between the fiber and protective needle or tube.

EVALUATION OF IMMUNOASSAY METHODS FOR DETERMINATION OF 3,5,6-TRICHLORO-2-PYRIDINOL IN MULTIPLE SAMPLE MEDIA

EPA Science Inventory

Two enzyme-linked immunosorbent assay (ELISA) methods were evaluated for the determination of 3,5,6-trichloro-2-pyridinol (3,5,6-TCP) in multiple sample media (dust, soil, food, and urine). The dust and soil samples were analyzed by the RaPID (TM) commercial immunoassay testing ...

Alkyl Passivation and Amphiphilic Polymer Coating of Silicon Nanocrystals for Diagnostic Imaging

PubMed Central

Hessel, Colin M.; Rasch, Michael R.; Hueso, Jose L.; Goodfellow, Brian W.; Akhavan, Vahid A.; Puvanakrishnan, Priyaveena; Tunnell, James W.

2011-01-01

We show a method to produce biocompatible polymer-coated silicon (Si) nanocrystals for medical imaging. Silica-embedded Si nanocrystals are formed by HSQ thermolysis. The nanocrystals are then liberated from the oxide and terminated with Si-H bonds by HF etching, followed by alkyl monolayer passivation by thermal hydrosilylation. The Si nanocrystals have an average diameter of 2.1 ± 0.6 nm and photoluminesce (PL) with a peak emission wavelength of 650 nm, which lies within the transmission window of 650–900 nm that is useful for biological imaging. The hydrophobic Si nanocrystals are then coated with an amphiphilic polymer for dispersion in aqueous media with pH ranging between 7 and 10 and ionic strength between 30 mM and 2 M, while maintaining a bright and stable PL and a hydrodynamic radius of only 20 nm. Fluorescence imaging of polymer-coated Si nanocrystals in a biological tissue host is demonstrated, showing the potential for in vivo imaging. PMID:20818646

Optimal antibunching in passive photonic devices based on coupled nonlinear resonators

NASA Astrophysics Data System (ADS)

Ferretti, S.; Savona, V.; Gerace, D.

2013-02-01

We propose the use of weakly nonlinear passive materials for prospective applications in integrated quantum photonics. It is shown that strong enhancement of native optical nonlinearities by electromagnetic field confinement in photonic crystal resonators can lead to single-photon generation only exploiting the quantum interference of two coupled modes and the effect of photon blockade under resonant coherent driving. For realistic system parameters in state of the art microcavities, the efficiency of such a single-photon source is theoretically characterized by means of the second-order correlation function at zero-time delay as the main figure of merit, where major sources of loss and decoherence are taken into account within a standard master equation treatment. These results could stimulate the realization of integrated quantum photonic devices based on non-resonant material media, fully integrable with current semiconductor technology and matching the relevant telecom band operational wavelengths, as an alternative to single-photon nonlinear devices based on cavity quantum electrodynamics with artificial atoms or single atomic-like emitters.

The Amount of Media and Information Literacy Among Isfahan University of Medical Sciences' Students Using Iranian Media and Information Literacy Questionnaire (IMILQ).

PubMed

Ashrafi-Rizi, Hasan; Ramezani, Amir; Koupaei, Hamed Aghajani; Kazempour, Zahra

2014-12-01

Media and Information literacy (MIL) enables people to interpret and make informed judgments as users of information and media, as well as to become skillful creators and producers of information and media messages in their own right. The purpose of this research was to determine the amount of Media and Information Literacy among Isfahan University of Medical Sciences' students using Iranian Media and Information Literacy Questionnaire (IMILQ). This is an applied analytical survey research in which the data were collected by a researcher made questionnaire, provided based on specialists' viewpoints and valid scientific works. Its validity and reliability were confirmed by Library and Information Sciences specialists and Cronbach's alpha (r=0.89) respectively. Statistical population consisted of all students in Isfahan University of Medical Sciences (6000 cases) and the samples were 361. Sampling method was random stratified sampling. Data were analyzed by descriptive and inferential statistics. The findings showed that the mean level of Media and Information Literacy among Isfahan University of Medical Sciences' students was 3.34±0.444 (higher than average). The highest mean was promotion of scientific degree with 3.84±0.975 and the lowest mean was difficulties in starting research with 2.50±1.08. There was significant difference between educational degree, college type and family's income and amount of Media and Information Literacy. The results showed that the students didn't have enough skills in starting the research, defining the research subject as well as confining the research subject. In general, all students and education practitioners should pay special attention to factors affecting in improving Media and Information Literacy as a main capability in using printed and electronic media.

The Amount of Media and Information Literacy Among Isfahan University of Medical Sciences’ Students Using Iranian Media and Information Literacy Questionnaire (IMILQ)

PubMed Central

Ashrafi-rizi, Hasan; Ramezani, Amir; Koupaei, Hamed Aghajani; Kazempour, Zahra

2014-01-01

Introduction: Media and Information literacy (MIL) enables people to interpret and make informed judgments as users of information and media, as well as to become skillful creators and producers of information and media messages in their own right. The purpose of this research was to determine the amount of Media and Information Literacy among Isfahan University of Medical Sciences’ students using Iranian Media and Information Literacy Questionnaire (IMILQ). Methods: This is an applied analytical survey research in which the data were collected by a researcher made questionnaire, provided based on specialists’ viewpoints and valid scientific works. Its validity and reliability were confirmed by Library and Information Sciences specialists and Cronbach’s alpha (r=0.89) respectively. Statistical population consisted of all students in Isfahan University of Medical Sciences (6000 cases) and the samples were 361. Sampling method was random stratified sampling. Data were analyzed by descriptive and inferential statistics. Results: The findings showed that the mean level of Media and Information Literacy among Isfahan University of Medical Sciences’ students was 3.34±0.444 (higher than average). The highest mean was promotion of scientific degree with 3.84±0.975 and the lowest mean was difficulties in starting research with 2.50±1.08. There was significant difference between educational degree, college type and family’s income and amount of Media and Information Literacy. Conclusion: The results showed that the students didn’t have enough skills in starting the research, defining the research subject as well as confining the research subject. In general, all students and education practitioners should pay special attention to factors affecting in improving Media and Information Literacy as a main capability in using printed and electronic media. PMID:25684848

The role of passive sampling in monitoring the environmental impacts of produced water discharges from the Norwegian oil and gas industry.

PubMed

Hale, Sarah E; Oen, Amy M P; Cornelissen, Gerard; Jonker, Michiel T O; Waarum, Ivar-Kristian; Eek, Espen

2016-10-15

Stringent and periodic iteration of regulations related to the monitoring of chemical releases from the offshore oil and gas industry requires the use of ever changing, rapidly developing and technologically advancing techniques. Passive samplers play an important role in water column monitoring of produced water (PW) discharge to seawater under Norwegian regulation, where they are used to; i) measure aqueous concentrations of pollutants, ii) quantify the exposure of caged organisms and investigate PW dispersal, and iii) validate dispersal models. This article summarises current Norwegian water column monitoring practice and identifies research and methodological gaps for the use of passive samplers in monitoring. The main gaps are; i) the range of passive samplers used should be extended, ii) differences observed in absolute concentrations accumulated by passive samplers and organisms should be understood, and iii) the link between PW discharge concentrations and observed acute and sub-lethal ecotoxicological end points in organisms should be investigated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gas-diffusion-based passive sampler for ammonia monitoring in marine waters.

PubMed

O'Connor Šraj, Lenka; Almeida, M Inês G S; Bassett, Chelsea; McKelvie, Ian D; Kolev, Spas D

2018-05-01

A novel passive sampler based on gas-diffusion across a hydrophobic membrane is described for the determination of the time-weighted average concentration of dissolved molecular ammonia in high ionic strength aquatic environments, such as sea, coastal and estuarine waters, for a period of 3 days. The passive sampler developed is cheap, easy-to-use, reusable, and has a dynamic concentration range of 2.0-12µM, which covers the water quality guideline trigger value of 11.4µM (160µgL -1 NH 3 -N) for high conservation value waters, making this a powerful new tool for water quality managers involved in long-term ammonia monitoring. The gas-diffusion-based passive sampler was calibrated under laboratory conditions and deployed in a tank of seawater in the laboratory and at an estuarine site for proof of concept, and a good agreement between passive and spot sampling was achieved in both cases. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of passive knee stiffness and viscosity in individuals with spinal cord injury using pendulum test

PubMed Central

Joghtaei, Mahmoud; Arab, Amir Massoud; Hashemi-Nasl, Hamed; Joghataei, Mohammad Taghi; Tokhi, Mohammad Osman

2015-01-01

Objective Stiffness and viscosity represent passive resistances to joint motion related with the structural properties of the joint tissue and of the musculotendinous complex. Both parameters can be affected in patients with spinal cord injury (SCI). The purpose of this study was to measure passive knee stiffness and viscosity in patients with SCI with paraplegia and healthy subjects using Wartenberg pendulum test. Design Non-experimental, cross-sectional, case–control design. Setting An outpatient physical therapy clinic, University of social welfare and Rehabilitation Science, Iran. Patients A sample of convenience sample of 30 subjects participated in the study. Subjects were categorized into two groups: individuals with paraplegic SCI (n = 15, age: 34.60 ± 9.18 years) and 15 able-bodied individuals as control group (n = 15, age: 30.66 ± 11.13 years). Interventions Not applicable. Main measures Passive pendulum test of Wartenberg was used to measure passive viscous-elastic parameters of the knee (stiffness, viscosity) in all subjects. Results Statistical analysis (independent t-test) revealed significant difference in the joint stiffness between healthy subjects and those with paraplegic SCI (P = 0.01). However, no significant difference was found in the viscosity between two groups (P = 0.17). Except for first peak flexion angle, all other displacement kinematic parameters exhibited no statistically significant difference between normal subjects and subjects with SCI. Conclusions Patients with SCI have significantly greater joint stiffness compared to able-bodied subjects. PMID:25437824