Beta particle dose rates to micro-organisms in soil

International Nuclear Information System (INIS)

Kabir, M.; Spiers, F.W.; Iinuma, Takeshi.

1977-01-01

Studies were made to estimate the beta-particle dose rates to micro-organisms of various sizes in soil. The small insects and organisms living in soil are constantly exposed to beta-radiation arising from naturally occuring radionuclides in soil as in this case no overlying tissue shields them. The technique of measuring beta-particle dose rate consisted of using of a thin plastic scintillator to measure the pulse height distribution as the beta particle traverses the scintillator. The integrated response was determined by the number and size of the photomultiplier pulses. From the data of soil analyses it was estimated that typically about 29% of the beta particles emitted per gm. of soil were contributed by the U/Ra series, 21% by the Th series and about 50% by potassium. By combining the individual spectra of these three radionuclides in the proportion found in a typical soil, a resultant spectrum was computed representing the energy distribution of the beta particles. The dose rate received by micro-organisms of different shape and size in soil was derived from the equilibrium dose rates combined with a 'Geometrical Factor' of the organisms. For small organisms, the dose rates did not vary between the spherical and cylindrical types, but in the case of larger organisms, the dose rates were found to be greater for the spherical types of the same diameter. (auth.)

Influence of agitation intensity on flotation rate of apatite particles

Directory of Open Access Journals (Sweden)

Francisco Gregianin Testa

Full Text Available Abstract The agitation intensity has a directly influence on flotation performance, lifting the particles and promoting the contact of bubbles and particles. In this paper, the energy input by the agitation on apatite flotation was investigated. The influence of pulp agitation in the flotation rate of particles with different sizes and two dosage levels was evaluated by batch testing. The flotation tests were conducted in an oscillating grid flotation cell (OGC, developed to promote a near isotropic turbulence environment. The cell is able to control the intensity of agitation and measure the energy transferred to the pulp phase. A sample of pure apatite was crushed (P80=310µm, characterized and floated with sodium oleate as collector. Four levels of energy dissipation, from 0.1 to 2 kWm-3, and two levels of collector dosage are used during the tests. The flotation kinetics by particle size were determined in function of the energy transferred. The results show a strong influence of the agitation intensity on the apatite flotation rate with both low and high dosage. For fine particles, when increasing the energy input, the flotation rate increase too, and this fact can be attributed to elevation of bubble-particle collisions. The kinetic result for the coarse particles demonstrated a reduction of the flotation rate whenever the energy input for this particle size was increased, whereby the turbulence caused by the agitation promotes the detachment of bubble-particle.

Chemical compositions of subway particles in Seoul, Korea determined by a quantitative single particle analysis.

Science.gov (United States)

Kang, Sunni; Hwang, HeeJin; Park, YooMyung; Kim, HyeKyoung; Ro, Chul-Un

2008-12-15

A novel single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal subway samples collected at a subway station in Seoul, Korea. For all 8 samples collected twice in each season, 4 major types of subway particles, based on their chemical compositions, are significantly encountered: Fe-containing; soil-derived; carbonaceous; and secondary nitrate and/or sulfate particles. Fe-containing particles are generated indoors from wear processes at rail-wheel-brake interfaces while the others may be introduced mostly from the outdoor urban atmosphere. Fe-containing particles are the most frequently encountered with relative abundances in the range of 61-79%. In this study, it is shown that Fe-containing subway particles almost always exist either as partially or fully oxidized forms in underground subway microenvironments. Their relative abundances of Fe-containing particles increase as particle sizes decrease. Relative abundances of Fe-containing particles are higher in morning samples than in afternoon samples because of heavier train traffic in the morning. In the summertime samples, Fe-containing particles are the most abundantly encountered, whereas soil-derived and nitrate/sulfate particles are the least encountered, indicating the air-exchange between indoor and outdoor environments is limited in the summer, owing to the air-conditioning in the subway system. In our work, it was observed that the relative abundances of the particles of outdoor origin vary somewhat among seasonal samples to a lesser degree, reflecting that indoor emission sources predominate.

The Influence of Particle Charge on Heterogeneous Reaction Rate Coefficients

Science.gov (United States)

Aikin, A. C.; Pesnell, W. D.

2000-01-01

The effects of particle charge on heterogeneous reaction rates are presented. Many atmospheric particles, whether liquid or solid are charged. This surface charge causes a redistribution of charge within a liquid particle and as a consequence a perturbation in the gaseous uptake coefficient. The amount of perturbation is proportional to the external potential and the square of the ratio of debye length in the liquid to the particle radius. Previous modeling has shown how surface charge affects the uptake coefficient of charged aerosols. This effect is now included in the heterogeneous reaction rate of an aerosol ensemble. Extension of this analysis to ice particles will be discussed and examples presented.

X particle effect for 6Li reaction rates calculations

International Nuclear Information System (INIS)

Kocak, G.; Balantekin, A. B.

2009-01-01

The inferred primordial 6 L i-7 L i abundances are different from standard big bang nucleosynthesis results, 6 L i is 1000 times larger and 7 L i is 3 times smaller than the big bang prediction. In big bang nucleosynthesis, negatively charged massive X particles a possible solution to explain this primordial Li abundances problem [1]. In this study, we consider only X particle effect for nuclear reactions to obtain S-factor and reaction rates for Li. All S-factors calculated within the Optical Model framework for d(α,γ)6 L i system. We showed that the enhancement effect of massive negatively charged X particle for 6 L i system reaction rate.(author)

Feeding ecology informs parasite epidemiology: prey selection modulates encounter rate with Echinococcus multilocularis in urban coyotes.

Science.gov (United States)

Liccioli, Stefano; Bialowas, Carly; Ruckstuhl, Kathreen E; Massolo, Alessandro

2015-01-01

We investigated the role of urban coyote feeding ecology in the transmission of Echinococcus multilocularis, the causative agent of Alveolar Echinococcosis in humans. As coyotes can play a main role in the maintenance of this zoonotic parasite within North American urban settings, such study can ultimately aid disease risk management. Between June 2012 and June 2013, we collected 251 coyote feces and conducted trapping of small mammals (n = 971) in five parks in the city of Calgary, Alberta, Canada. We investigated E. multilocularis epidemiology by assessing seasonal variations of coyote diet and the selective consumption of different rodent intermediate host species. Furthermore, accounting for small mammal digestibility and coyote defecation rates we estimated the number of small mammal preys ingested by coyote and consequently, coyote encounter rates with the parasite. Dominant food items included small mammals, fruit and vegetation, although hare and deer were seasonally relevant. The lowest frequency of occurrence per scat of small mammals was recorded in winter (39.4%), when consumption of deer was highest (36.4%). However, highest encounter rates (number of infected hosts predated/season) with E. multilocularis (95% CI: 1.0-22.4), combined with the lack of predation on non-competent small mammal species, suggest that winter is the critical season for transmission and control of this parasite. Within the small mammal assemblage, voles (Microtus pennsylvanicus and Myodes gapperi) were the selected preys of urban coyotes and likely played a key role for the maintenance of the urban sylvatic life-cycle of E. multilocularis in Calgary.

Feeding ecology informs parasite epidemiology: prey selection modulates encounter rate with Echinococcus multilocularis in urban coyotes.

Directory of Open Access Journals (Sweden)

Stefano Liccioli

Full Text Available We investigated the role of urban coyote feeding ecology in the transmission of Echinococcus multilocularis, the causative agent of Alveolar Echinococcosis in humans. As coyotes can play a main role in the maintenance of this zoonotic parasite within North American urban settings, such study can ultimately aid disease risk management. Between June 2012 and June 2013, we collected 251 coyote feces and conducted trapping of small mammals (n = 971 in five parks in the city of Calgary, Alberta, Canada. We investigated E. multilocularis epidemiology by assessing seasonal variations of coyote diet and the selective consumption of different rodent intermediate host species. Furthermore, accounting for small mammal digestibility and coyote defecation rates we estimated the number of small mammal preys ingested by coyote and consequently, coyote encounter rates with the parasite. Dominant food items included small mammals, fruit and vegetation, although hare and deer were seasonally relevant. The lowest frequency of occurrence per scat of small mammals was recorded in winter (39.4%, when consumption of deer was highest (36.4%. However, highest encounter rates (number of infected hosts predated/season with E. multilocularis (95% CI: 1.0-22.4, combined with the lack of predation on non-competent small mammal species, suggest that winter is the critical season for transmission and control of this parasite. Within the small mammal assemblage, voles (Microtus pennsylvanicus and Myodes gapperi were the selected preys of urban coyotes and likely played a key role for the maintenance of the urban sylvatic life-cycle of E. multilocularis in Calgary.

Benthic life in the pelagic: Aggregate encounter and degradation rates by pelagic harpacticoid copepods

DEFF Research Database (Denmark)

Koski, Marja; Kiørboe, Thomas; Takahashi, K.

2005-01-01

We measured field abundances, feeding rates, swimming behavior, and particle colonization of two harpacticoids, the pelagic Microsetella norvegica and the semibenthic Amonardia normanni, to examine (1) if aggregates have a significant role in harpacticoid nutrition and (2) if harpacticoids...

IUTAM symposium on hydrodynamic diffusion of suspended particles

Energy Technology Data Exchange (ETDEWEB)

Davis, R.H. [ed.

1995-12-31

Hydrodynamic diffusion refers to the fluctuating motion of nonBrownian particles (or droplets or bubbles) which occurs in a dispersion due to multiparticle interactions. For example, in a concentrated sheared suspension, particles do not move along streamlines but instead exhibit fluctuating motions as they tumble around each other. This leads to a net migration of particles down gradients in particle concentration and in shear rate, due to the higher frequency of encounters of a test particle with other particles on the side of the test particle which has higher concentration or shear rate. As another example, suspended particles subject to sedimentation, centrifugation, or fluidization, do not generally move relative to the fluid with a constant velocity, but instead experience diffusion-like fluctuations in velocity due to interactions with neighboring particles and the resulting variation in the microstructure or configuration of the suspended particles. In flowing granular materials, the particles interact through direct collisions or contacts (rather than through the surrounding fluid); these collisions also cause the particles to undergo fluctuating motions characteristic of diffusion processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

RadNuc: a graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a 137Cs irradiator.

Science.gov (United States)

Pasternack, Jordan B; Howell, Roger W

2013-02-01

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy is generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. The GUI controlled irradiator can achieve a maximum dose rate of 40 cGy/h and a minimum dose rate of 0.01 cGy/h. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001 cGy/h. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides. Copyright © 2013 Elsevier Inc. All rights reserved.

Being on sick leave due to heart failure: self-rated health, encounters with healthcare professionals and social insurance officers and self-estimated ability to return to work.

Science.gov (United States)

Nordgren, Lena; Söderlund, Anne

2015-01-01

Younger people with heart failure often experience poor self-rated health. Furthermore, poor self-rated health is associated with long-term sick leave and disability pension. Socio-demographic factors affect the ability to return to work. However, little is known about people on sick leave due to heart failure. The aim of this study was to investigate associations between self-rated health, mood, socio-demographic factors, sick leave compensation, encounters with healthcare professionals and social insurance officers and self-estimated ability to return to work, for people on sick leave due to heart failure. This population-based investigation had a cross-sectional design. Data were collected in Sweden in 2012 from two official registries and from a postal questionnaire. In total, 590 subjects, aged 23-67, responded (response rate 45.8%). Descriptive statistics, correlation analyses (Spearman bivariate analysis) and logistic regression analyses were used to investigate associations. Poor self-rated health was strongly associated with full sick leave compensation (OR = 4.1, p health was moderately associated with low income (OR =  .6, p =  .003). Good self-rated health was strongly associated with positive encounters with healthcare professionals (OR = 3.0, p =  .022) and to the impact of positive encounters with healthcare professionals on self-estimated ability to return to work (OR = 3.3, p work imposes reduced quality of life. Positive encounters with healthcare professionals and social insurance officers can be supportive when people with heart failure struggle to remain in working life.

Deviation from the kinetic law of mass action for reactions induced by binary encounters in liquid solutions

International Nuclear Information System (INIS)

Doktorov, Alexander B; Kipriyanov, Alexey A

2007-01-01

In considering the irreversible chemical reaction A+B→ C+B in liquid solutions two many-particle approaches to the derivation of binary non-Markovian kinetic equations are compared: simple superposition decoupling and a method of extracting 'pair' channels from three-particle correlation evolution. It is shown that both methods provide an almost identical description of this reaction. However, in studies of reversible reactions in liquid solutions only the channel extraction method gives a correct physically clear description of the reaction though it consists of a sequence of steps: the development of integral encounter theory (IET), effective pairs approximation (EPA), modified encounter theory (MET), and the final regular form (RF) of kinetic equations. It is shown that the rate equations often encountered in the literature correspond to the independence of transient channels of 'scattering' in the bimolecular reversible reaction (A+B -B), while the independent transient channel of 'decay' in the reversible reactionA+B -C is defined solely by time integral convolution. In the general case transient channels in non-Markovian theory are not independent, and their interference manifests itself as a non-Markovian inhomogeneous source in binary non-Markovian kinetic equations in regular form. Based on the derived equations new universal kinetics (independent of models) of chemical equilibrium attainment have been obtained. It is shown that these kinetics can differ essentially from the kinetics corresponding to the kinetic law of mass action of formal chemical kinetics

Estimates of particle- and thorium-cycling rates in the northwest Atlantic Ocean

International Nuclear Information System (INIS)

Murnane, R.J.; Sarmiento, J.L.; Cochran, J.K.

1994-01-01

The authors provide least squares estimates of particle-cycling rate constants and their errors at 13 depths in the Northwest Atlantic Ocean using a compilation of published results and conservation equations for thorium and particle cycling. The predicted rates of particle aggregation and disaggregation vary through the water column. The means and standard deviations, based on lognormal probability distributions, for the lowest and highest rates of aggregation (β 2 ) and disaggregation (β -2 ) in the water column are 8±27 y -1 2 -1 , and 580±2000 y -1 -2 3 ±10 4 y -1 . Median values for these rates are 2.1 y -1 2 -1 , and 149 y -1 -2 -1 . Predicted rate constants for thorium adsorption (k 1 = 5.0±1.0x10 4 m 3 kg -1 y -1 ) and desorption (k -1 = 3.1±1.5 y -1 ) are consistent with previous estimates. Least squares estimates of the sum of the time dependence and transport terms from the particle and thorium conservation equations are on the same order as other terms in the conservation equations. Forcing this sum to equal zero would change the predicted rates. Better estimates of the time dependence of thorium activities and particle concentrations and of the concentration and flux of particulate organic matter would help to constrain estimates of β 2 and β -2 . 46 refs., 8 figs., 5 tabs

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating.

Science.gov (United States)

Koivisto, Antti J; Jensen, Alexander C Ø; Kling, Kirsten I; Kling, Jens; Budtz, Hans Christian; Koponen, Ismo K; Tuinman, Ilse; Hussein, Tareq; Jensen, Keld A; Nørgaard, Asger; Levin, Marcus

2018-01-05

Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO 2 )-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m 3 test chamber while measuring concentrations of 5.6nm to 31μm-size particles and volatile organic compounds (VOC), as well as particle deposition onto room surfaces and on the spray gun user hand. The particle emission and deposition rates were quantified using aerosol mass balance modelling. The geometric mean particle number emission rate was 1.9×10 10 s -1 and the mean mass emission rate was 381μgs -1 . The respirable mass emission-rate was 65% lower than observed for the entire measured size-range. The mass emission rates were linearly scalable (±ca. 20%) to the process duration. The particle deposition rates were up to 15h -1 for deposited particles consisted of mainly TiO 2 , TiO 2 mixed with Cl and/or Ag, TiO 2 particles coated with carbon, and Ag particles with size ranging from 60nm to ca. 5μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Effects of Soundscapes on Perceived Crowding and Encounter Norms

Science.gov (United States)

Kim, Sang-Oh; Shelby, Bo

2011-07-01

Soundscapes in recreation settings are becoming an important issue, but there are few studies of the effects of sounds on recreation experiences, especially crowding perceptions and encounter norms. This study compared effects of six types of sounds (an airplane, a truck engine, children playing, birds, water, and a control) on perceived crowding (PC) and encounter norms for hikers. Data were collected from 47 college students through lab experiments using simulated images, with moving hikers inserted in the original photo taken in the Jungmeori area of Mudeungsan Provincial Park in Korea. Overall, the motor-made sounds of the airplane and truck engine increased PC and decreased acceptability ratings, and the natural sounds of birds and water decreased PC and increased acceptability ratings. Ratings of the sound of children playing were similar to those in the control (i.e., no sound). In addition, as numbers of hikers increased, the overall effects of sounds decreased, and there were few significant differences in PC or acceptability ratings at the highest encounter levels. Theoretical and methodological implications are discussed.

Organised Cultural Encounters

DEFF Research Database (Denmark)

Christiansen, Lene Bull; Galal, Lise Paulsen; Hvenegård-Lassen, Kirsten

2017-01-01

The article introduces the special issue by presenting the concept of organised cultural encounters that are encounters organised to manage and/or transform problems perceived to originate in or include cultural differences. Inspired by Pratt’s conceptualisation of the contact zone, a critical...... perspective on the particular historical and spatial context of any encounter and how this context frames and mediates what takes place during an encounter is applied. While the articles of the issue present different varieties of organised cultural encounters, it is argued that they are not only of the same...

Assessment of weathering and leaching rates of Thule hot particles

Energy Technology Data Exchange (ETDEWEB)

Roos, P. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Roskilde (Denmark)); Outola, I. (STUK-Radiation and Nuclear Safety Authority (Finland)); Nygren, U.; Ramebaeck, H. (FOI CBRN Defence and Security (Sweden)); Sidhu, R. (Institute of Energy Technology, Environmental Monitoring Section, Health and Safety Dept. (Norway))

2010-03-15

Within the current project a methodology for separating actinide particles originating from the Thule 1968 accident has been developed. Particles were completely isolated in water using visual and radiometric methods. The particles were attached electrostatic to a plastic support and could easily be moved to any container for leaching studies or other type of studies. Leaching and dissolution studies performed within the project indicate that some particles are relatively easily destroyed or leached while others are more refractory. The results shows that even though the oxide particles are hard to completely dissolve they release material even when exposed to weak solvents like water and salt solutions. Exposures to lung simulant fluids show relatively slow dissolution rates comparable to what is found using only water. Sequential extraction of particles shows that variation between particles is very large; some dissolve easily while some does not. Of radiological importance is the disruption of particles when exposed to dissolution. (author)

Assessment of weathering and leaching rates of Thule hot particles

International Nuclear Information System (INIS)

Roos, P.; Outola, I.; Nygren, U.; Ramebaeck, H.; Sidhu, R.

2010-03-01

Within the current project a methodology for separating actinide particles originating from the Thule 1968 accident has been developed. Particles were completely isolated in water using visual and radiometric methods. The particles were attached electrostatic to a plastic support and could easily be moved to any container for leaching studies or other type of studies. Leaching and dissolution studies performed within the project indicate that some particles are relatively easily destroyed or leached while others are more refractory. The results shows that even though the oxide particles are hard to completely dissolve they release material even when exposed to weak solvents like water and salt solutions. Exposures to lung simulant fluids show relatively slow dissolution rates comparable to what is found using only water. Sequential extraction of particles shows that variation between particles is very large; some dissolve easily while some does not. Of radiological importance is the disruption of particles when exposed to dissolution. (author)

Conservative interacting particles system with anomalous rate of ergodicity

OpenAIRE

Brzeźniak, Zdzislaw; Flandoli, Franco; Neklyudov, Misha; Zegarliński, Boguslaw

2010-01-01

We analyze certain conservative interacting particle system and establish ergodicity of the system for a family of invariant measures. Furthermore, we show that convergence rate to equilibrium is exponential. This result is of interest because it presents counterexample to the standard assumption of physicists that conservative system implies polynomial rate of convergence.

Coupled force-balance and particle-occupation rate equations for high-field electron transport

International Nuclear Information System (INIS)

Lei, X. L.

2008-01-01

It is pointed out that in the framework of balance-equation approach, the coupled force-balance and particle-occupation rate equations can be used as a complete set of equations to determine the high-field transport of semiconductors in both strong and weak electron-electron interaction limits. We call to attention that the occupation rate equation conserves the total particle number and maintains the energy balance of the relative electron system, and there is no need to introduce any other term in it. The addition of an energy-drift term in the particle-occupation rate equation [Phys. Rev. B 71, 195205 (2005)] is physically inadequate for the violation of the total particle-number conservation and the energy balance. It may lead to a substantial unphysical increase of the total particle number by the application of a dc electric field

Sterile endophthalmitis rates and particle size analyses of different formulations of triamcinolone acetonide.

Science.gov (United States)

Dodwell, David G; Krimmel, Darrel A; de Fiebre, Christopher M

2015-01-01

To evaluate the rate of sterile endophthalmitis (SE) following intravitreal injection of three different formulations of triamcinolone acetonide (TA) in a single physician practice and also to assess the mean diameter and concentration of particles of the two TA formulations currently available commercially in the USA. It was hypothesized that TA formulations with smaller particles and/or greater concentrations would have a higher incidence of SE. Single-site, interventional case series in which the medical records of 392 consecutive eyes receiving intravitreal TA as Triesence(®), Kenalog(®)-40, or preservative-free TA between September 2008 and October 2013 were retrospectively reviewed for the incidence of SE. Particle sizing of TA formulations was conducted by an independent commercial laboratory. Five cases of SE were identified. The four cases of SE following Triesence(®) (4.6%) represented a rate significantly higher than the one case of SE following preservative-free TA (0.6%; P=0.049) and the 0% incidence rate of SE following Kenalog(®)-40 (P=0.0210). Triesence(®) had significantly smaller particles than Kenalog(®)-40 (P<0.0001). The rate of SE was the highest with the formulation of TA that had the smallest particle size and highest particle load (number of particles injected). The lowest rate of SE was seen with Kenalog(®)-40, the only TA formulation that contained a benzyl alcohol preservative. The data do not support a principal causative role of benzyl alcohol in the development of TA-induced SE. Instead, the data support the particle theory of TA-induced SE; however, larger-scale, multicenter studies are needed to confirm and expand on these findings.

Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

Directory of Open Access Journals (Sweden)

C. D. O'Dowd

2007-01-01

Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

Indoor particle dynamics in a school office: determination of particle concentrations, deposition rates and penetration factors under naturally ventilated conditions.

Science.gov (United States)

Cong, X C; Zhao, J J; Jing, Z; Wang, Q G; Ni, P F

2018-05-09

Recently, the problem of indoor particulate matter pollution has received much attention. An increasing number of epidemiological studies show that the concentration of atmospheric particulate matter has a significant effect on human health, even at very low concentrations. Most of these investigations have relied upon outdoor particle concentrations as surrogates of human exposures. However, considering that the concentration distribution of the indoor particulate matter is largely dependent on the extent to which these particles penetrate the building and on the degree of suspension in the indoor air, human exposures to particles of outdoor origin may not be equal to outdoor particle concentration levels. Therefore, it is critical to understand the relationship between the particle concentrations found outdoors and those found in indoor micro-environments. In this study, experiments were conducted using a naturally ventilated office located in Qingdao, China. The indoor and outdoor particle concentrations were measured at the same time using an optical counter with four size ranges. The particle size distribution ranged from 0.3 to 2.5 μm, and the experimental period was from April to September, 2016. Based on the experimental data, the dynamic and mass balance model based on time was used to estimate the penetration rate and deposition rate at air exchange rates of 0.03-0.25 h -1 . The values of the penetration rate and deposition velocity of indoor particles were determined to range from 0.45 to 0.82 h -1 and 1.71 to 2.82 m/h, respectively. In addition, the particulate pollution exposure in the indoor environment was analyzed to estimate the exposure hazard from indoor particulate matter pollution, which is important for human exposure to particles and associated health effects. The conclusions from this study can serve to provide a better understanding the dynamics and behaviors of airborne particle entering into buildings. And they will also highlight

Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

Energy Technology Data Exchange (ETDEWEB)

Dobbs, Adam James [Imperial College, London (United Kingdom)

2011-10-01

A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

Cultural geography. Different encounters, encountering difference

OpenAIRE

Longhurst, Robyn

2007-01-01

In the first half of this paper it is argued that cultural geography is a dynamic and diverse field that extends well beyond a single branch of human geography. The boundaries between it and other sub-disciplines are often blurred. People have «different» encounters with cultural geography depending on their sub-disciplinary convergences. People also have different encounters with cultural geography depending on where they live and work. «Place matters» in the construction, production and rep...

Observation of advanced particle removal rates in pump limiter simulation experiments

International Nuclear Information System (INIS)

Goebel, D.M.; Conn, R.W.

1984-05-01

The performance of particle removal schemes for density and impurity control in tokamaks and mirror machines depends strongly on the plasma parameters and local recycling near the plasma neutralizier plates and gas pumping ducts. The relationship between plasma density, electron temperature, ion energy and gas flow and particle removal rate through a pumping duct located near a plasma neutralizer plate has been experimentally investigated in the steady state plasma device PISCES. Results indicate that initially the particle removal by pumps at the end of the duct is proportional to the plasma flux to the plate. A nonlinear increase in the pumping rate occurs when the ionization mean free path for neutrals from the plate becomes less than the plasma radius. The transition from a transparent to an opaque plasma due to local ionization of the neutrals produced at the neutralizer plate greatly enhances the particle removal rate by recycling of the neutral gas as it flows away from the neutralizer plate or out of the pumping ducts. Parameters were varied to determine the importance of ballistic scattering of higher energy ions from the plate, but no effects were found in these experiments

Mobile encounters

DEFF Research Database (Denmark)

Koefoed, Lasse Martin; Christensen, Mathilde Dissing; Simonsen, Kirsten

2017-01-01

The paper explores modes of encounters in the everyday practice of bus travel. Particularly, it addresses cross-cultural encounters located in the tension between familiarity and difference, between inclusion and exclusion. The paper is located in contemporary thoughts, approaching public transport...... not only as a moving device but also as a social arena. Furthermore, the bus is simultaneously perceived as a public space, at once composite, contradictory and heterogeneous, and as a meeting place involving ‘Throwntogetherness’. The encounters analysed are bodily, emotional charged and outspoken meetings...

Synergistic effects in radiation-induced particle ejection from solid surfaces

International Nuclear Information System (INIS)

Itoh, Noriaki

1990-01-01

A description is given on radiation-induced particle ejection from solid surfaces, emphasizing synergistic effects arising from multi-species particle irradiation and from irradiation under complex environments. First, it is pointed out that synergisms can be treated by introducing the effects of material modification on radiation-induced particle ejection. As examples of the effects of surface modification on the sputtering induced by elastic encounters, sputtering of alloys and chemical sputtering of graphite are briefly discussed. Then the particle ejection induced by electronic encounters is explained emphasizing the difference in the behaviors from materials to materials. The possible synergistic effects of electronic and elastic encounters are also described. Lastly, we point out the importance of understanding the elementary processes of material-particle interaction and of developing computer codes describing material behaviors under irradiation. (author)

arXiv Gravitational wave energy emission and detection rates of Primordial Black Hole hyperbolic encounters

CERN Document Server

García-Bellido, Juan

2018-01-01

We describe in detail gravitational wave bursts from Primordial Black Hole (PBH) hyperbolic encounters. The bursts are one-time events, with the bulk of the released energy happening during the closest approach, which can be emitted in frequencies that could be within the range of both LIGO (10-1000Hz) and LISA ($10^{-6}-1$ Hz). Furthermore, we correct the results for the power spectrum of hyperbolic encounters found in the literature and present new exact and approximate expressions for the peak frequency of the emission. Note that these GW bursts from hyperbolic encounters between PBH are complementary to the GW emission from the bounded orbits of BHB mergers detected by LIGO, and help breaking degeneracies in the determination of the PBH mass, spin and spatial distributions.

Test Method for High β Particle Emission Rate of 63Ni Source Plate

OpenAIRE

ZHANG Li-feng

2015-01-01

For the problem of measurement difficulties of β particle emission rate of Ni-63 source plate used for Ni-63 betavoltaic battery, a relative test method of scintillation current method was erected according to the measurement principle of scintillation detector.β particle emission rate of homemade Ni-63 source plate was tested by the method, and the test results were analysed and evaluated, it was initially thought that scintillation current method was a feasible way of testing β particle emi...

Encounters of The Solar System With Molecular Clouds

International Nuclear Information System (INIS)

Wickramasinghe, J. T.

2008-01-01

The solar system has penetrated about 5 -- 10 giant molecular clouds over its history, and passes within 5 parsecs of a star-forming nebula every 100 million years or so. Numerical simulations of the effect of such encounters in perturbing the Oort cloud of comets are carried out using standard n-body computational techniques. It is found that the ingress of comets into the inner planetary system during such encounters amounts to factors of ∼100 over the average. During an encounter the impact rate of comets onto Earth increases by a comparable factor. The of ages of impact craters on the Earth is shown to be consistent with predictions from the model

Determination of reactivity rates of silicate particle-size fractions

Directory of Open Access Journals (Sweden)

Angélica Cristina Fernandes Deus

2014-04-01

Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

Particle-size effect on the rate of TiO2 carbonizing

International Nuclear Information System (INIS)

Lekanova, T.L.; Ryabkov, Yu.I.; Sevbo, O.A.

2003-01-01

Dependence of recovery rate constant of titanium dioxide in TiO 2 -C system on the value of specific surface initial components at 1300 deg C was studied. It is shown that decrease in equivalent particle size of titanium dioxide and carbon particles in the range of 500-100 μm has a similar effect on increase in titanium dioxide recovery rate. Analysis of kinetic equations suggests diffusion character of titanium dioxide carbonizing at the values of initial components specific surface in excess of 100 m 2 /g [ru

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia; Angulo, C.; Arnould, M.

2000-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. we report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies, the theoretical predictions obtained in the framework of the Hauser-Feshbach model is used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (authors)

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia

1999-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged -particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies the theoretical predictions obtained in the framework of the Hauser-Feshbach model are used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (author)

Use, misuse and extensions of "ideal gas" models of animal encounter.

Science.gov (United States)

Hutchinson, John M C; Waser, Peter M

2007-08-01

Biologists have repeatedly rediscovered classical models from physics predicting collision rates in an ideal gas. These models, and their two-dimensional analogues, have been used to predict rates and durations of encounters among animals or social groups that move randomly and independently, given population density, velocity, and distance at which an encounter occurs. They have helped to separate cases of mixed-species association based on behavioural attraction from those that simply reflect high population densities, and to detect cases of attraction or avoidance among conspecifics. They have been used to estimate the impact of population density, speeds of movement and size on rates of encounter between members of the opposite sex, between gametes, between predators and prey, and between observers and the individuals that they are counting. One limitation of published models has been that they predict rates of encounter, but give no means of determining whether observations differ significantly from predictions. Another uncertainty is the robustness of the predictions when animal movements deviate from the model's assumptions in specific, biologically relevant ways. Here, we review applications of the ideal gas model, derive extensions of the model to cover some more realistic movement patterns, correct several errors that have arisen in the literature, and show how to generate confidence limits for expected rates of encounter among independently moving individuals. We illustrate these results using data from mangabey monkeys originally used along with the ideal gas model to argue that groups avoid each other. Although agent-based simulations provide a more flexible alternative approach, the ideal gas model remains both a valuable null model and a useful, less onerous, approximation to biological reality.

Theoretical Evaluation of the Escape Rate of Charged Particles Trapped in a Potential Energy Well

International Nuclear Information System (INIS)

Chang Yongbin; Ordonez, C.A.

2003-01-01

In various types of charged particle sources and traps, charged particles are temporarily trapped within a potential energy well. In the work reported, a theoretical evaluation of the escape rate of trapped charged particles is carried out. As a specific example, the loss rate is evaluated for trapped plasma particles that are undergoing both collisions among themselves and collisions with particles of a different plasma species having a different temperature. Conditions are considered in which both species are confined within a nested Penning trap

Particle deposition from aqueous suspensions in turbulent pipe flow - a comparison of observed deposition rates and predicted arrival rates

International Nuclear Information System (INIS)

Rodliffe, R.S.

1979-11-01

At the present time, there appear to be only four adequately controlled and characterised experimental studies of particle deposition from single phase water in turbulent pipe flow. These are used to illustrate the ranges of applicability of methods for predicting particle arrival rates at tube walls. Arrival rates are predicted from mass transfer correlations and the theory of Reeks and Skyrme (1976) when transport is limited by Brownian diffusion and inertial behaviour, respectively. The regimes in which finite particle size limits the application of these methods are defined and preliminary consideration is given to the conditions under which gravitational settling may make a contribution to deposition in vertically mounted tubes. (author)

Charged particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, C.

1999-01-01

We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal reason for setting up the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The main goal of NACRE network was the transparency in the procedure of calculating the rates. More specifically this compilation aims at: 1. updating the experimental and theoretical data; 2. distinctly identifying the sources of the data used in rate calculation; 3. evaluating the uncertainties and errors; 4. providing numerically integrated reaction rates; 5. providing reverse reaction rates and analytical approximations of the adopted rates. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. The compilation is concerned with the reaction rates that are large enough for the target lifetimes shorter than the age of the Universe, taken equal to 15 x 10 9 y. The reaction rates are provided for temperatures lower than T = 10 10 K. In parallel with the rate compilation a cross section data base has been created and located at the site http://pntpm.ulb.ac.be/nacre..htm. (authors)

Thinking about the service encounter enhances encounter-related word-of-mouth

DEFF Research Database (Denmark)

Mattsson, Jan; Söderlund, Magnus

) the memorability of the service encounter and (b) the extent to which what had happened had been subject to rehearsal with the purpose of telling others about it. These findings should be seen in relation to the literature’s view that customer satisfaction, not thinking, is a dominant predictor of word-of-mouth......This study examines the impact of thinking about a service encounter, after it has been completed, on telling others about it (i.e., word-of-mouth). The main finding was that encounter-related thinking boosted word-of-mouth. We also found that the think-talk association was mediated by (a....... Our results, however, indicate that satisfaction’s contribution to the variation in talking about the encounter was modest (and customer satisfaction played only a minor role in explaining why an encounter is thought about)....

Effect of Particle Size on Mechanical Properties of Sawdust-High Density Polyethylene Composites under Various Strain Rates

Directory of Open Access Journals (Sweden)

Haliza Jaya

2016-06-01

Full Text Available There is a need to understand the effect of wood particle size, as it affects the characteristics of wood-based composites. This study considers the effect of wood particle size relative to the dynamic behavior of wood composites. The compression Split Hopkinson Pressure Bar (SHPB was introduced to execute dynamic compression testing at the strain rate of 650 s-1, 900 s-1, and 1100 s-1, whereas a conventional universal testing machine (UTM was used to perform static compression testing at the strain rate of 0.1 s-1, 0.01 s-1, and 0.001 s-1 for four different particle sizes (63 µm, 125 µm, 250 µm, and 500 µm. The results showed that mechanical properties of composites were positively affected by the particle sizes, where the smallest particle size gave the highest values compared to the others. Moreover, the particle size also affected the rate sensitivity and the thermal activation volume of sawdust/HDPE, where smaller particles resulted in lower rate sensitivity. For the post-damage analysis, the applied strain rates influenced deformation behavior differently for all particle sizes of the specimens. In a fractographic analysis under dynamic loading, the composites with large particles experienced severe catastrophic deformation and damages compared to the smaller particles.

The probability of an encounter of two Brownian particles before escape

International Nuclear Information System (INIS)

Holcman, D; Kupka, I

2009-01-01

We study the probability of meeting of two Brownian particles before one of them exits a finite interval. We obtain an explicit expression for the probability as a function of the initial distance between the two particles using the Weierstrass elliptic function. We also find the law of the meeting location. Brownian simulations show the accuracy of our analysis. Finally, we discuss some applications to the probability that a double-strand DNA break repairs in confined environments.

Low velocity encounters of minor bodies with the outer planets

International Nuclear Information System (INIS)

Carusi, A.; Perozzi, E.; Valsecchi, G.B.

1983-01-01

Previous studies of close encounters of minor bodies with Jupiter have shown that the perturbations are stronger either if the encounter is very deep or if the velocity of the minor body relative to the planet is low. In the present research the author investigates the effects of low velocity encounters between fictitious minor bodies and the four outer planets. Two possible outcomes of this type of encounter are the temporary satellite capture of the minor body by the planet, and the exchange of perihelion with aphelion of the minor body orbit. Different occurrence rates of these processes are found for different planets, and the implications for the orbital evolution of minor bodies in the outer Solar System are discussed. (Auth.)

Encounters between degenerate stars and extrasolar comet clouds

International Nuclear Information System (INIS)

Pineault, S.; Poisson, E.

1989-01-01

Under the assumption that the presence of comet clouds around otherwise normal stars is a common occurrence in the Galaxy, the observational consequences of random penetration encounters between the general Galactic population of degenerate stars and these comet clouds is considered. The only case considered is where the compact stars is a single star. For this scenario, encounters involving neutron stars (NSs) result in impact rates 1000-10,000 times slower than in the model of Tremaine and Zytkow (1986). The rate for white dwarfs (WDs) is larger than the one for NSs by a factor of about 30 times the ratio of the degenerate star number densities. The mean impact rate is significantly increased if the number of comets in a cloud is nearly independent of the mass of the central star. It is concluded that some of the observed gamma-ray bursts may be caused by accretion of comets onto NSs and that this scenario, but with a WD as the accretor, probably contributes to the optical flash background rate. 38 refs

Resource-driven encounters among consumers and implications for the spread of infectious disease

Science.gov (United States)

Flynn, Jason M.

2017-01-01

Animals share a variety of common resources, which can be a major driver of conspecific encounter rates. In this work, we implement a spatially explicit mathematical model for resource visitation behaviour in order to examine how changes in resource availability can influence the rate of encounters among consumers. Using simulations and asymptotic analysis, we demonstrate that, under a reasonable set of assumptions, the relationship between resource availability and consumer conspecific encounters is not monotonic. We characterize how the maximum encounter rate and associated critical resource density depend on system parameters like consumer density and the maximum distance from which consumers can detect and respond to resources. The assumptions underlying our theoretical model and analysis are motivated by observations of large aggregations of black-backed jackals at carcasses generated by seasonal outbreaks of anthrax among herbivores in Etosha National Park, Namibia. As non-obligate scavengers, black-backed jackals use carcasses as a supplemental food resource when they are available. While jackals do not appear to acquire disease from ingesting anthrax carcasses, changes in their movement patterns in response to changes in carcass abundance do alter jackals' conspecific encounter rate in ways that may affect the transmission dynamics of other diseases, such as rabies. Our theoretical results provide a method to quantify and analyse the hypothesis that the outbreak of a fatal disease among herbivores can potentially facilitate outbreaks of an entirely different disease among jackals. By analysing carcass visitation data, we find support for our model's prediction that the number of conspecific encounters at resource sites decreases with additional increases in resource availability. Whether or not this site-dependent effect translates to an overall decrease in encounters depends, unexpectedly, on the relationship between the maximum distance of detection and

Encountering Materiality

DEFF Research Database (Denmark)

Svabo, Connie

2016-01-01

DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016.......DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016....

Incidence of Norovirus-Associated Medical Encounters among Active Duty United States Military Personnel and Their Dependents.

Directory of Open Access Journals (Sweden)

Brian Rha

Full Text Available Norovirus is a leading cause of gastroenteritis episodes and outbreaks in US military deployments, but estimates of endemic disease burden among military personnel in garrison are lacking.Diagnostic codes from gastroenteritis-associated medical encounters of active duty military personnel and their beneficiaries from July 1998-June 2011 were obtained from the Armed Forces Health Surveillance Center. Using time-series regression models, cause-unspecified encounters were modeled as a function of encounters for specific enteropathogens. Model residuals (representing unexplained encounters were used to estimate norovirus-attributable medical encounters. Incidence rates were calculated using population data for both active duty and beneficiary populations.The estimated annual mean rate of norovirus-associated medically-attended visits among active duty personnel and their beneficiaries was 292 (95% CI: 258 to 326 and 93 (95% CI: 80 to 105 encounters per 10,000 persons, respectively. Rates were highest among beneficiaries <5 years of age with a median annual rate of 435 (range: 318 to 646 encounters per 10,000 children. Norovirus was estimated to cause 31% and 27% of all-cause gastroenteritis encounters in the active duty and beneficiary populations, respectively, with over 60% occurring between November and April. There was no evidence of any lag effect where norovirus disease occurred in one population before the other, or in one beneficiary age group before the others.Norovirus is a major cause of medically-attended gastroenteritis among non-deployed US military active duty members as well as in their beneficiaries.

Modeling Fuel Treatment Leverage: Encounter Rates, Risk Reduction, and Suppression Cost Impacts

Directory of Open Access Journals (Sweden)

Matthew P. Thompson

2017-11-01

Full Text Available The primary theme of this study is the cost-effectiveness of fuel treatments at multiple scales of investment. We focused on the nexus of fuel management and suppression response planning, designing spatial fuel treatment strategies to incorporate landscape features that provide control opportunities that are relevant to fire operations. Our analysis explored the frequency and magnitude of fire-treatment encounters, which are critical determinants of treatment efficacy. Additionally, we examined avoided area burned, avoided suppression costs, and avoided damages, and combined all three under the umbrella of leverage to explore multiple dimensions with which to characterize return on investment. We chose the Sierra National Forest, California, USA, as our study site, due to previous work providing relevant data and analytical products, and because it has the potential for large, long-duration fires and corresponding potential for high suppression expenditures. Modeling results generally confirmed that fire-treatment encounters are rare, such that median suppression cost savings are zero, but in extreme years, savings can more than offset upfront investments. Further, reductions in risk can expand areas where moderated suppression response would be appropriate, and these areas can be mapped in relation to fire control opportunities.

Phototransformation rate constants of PAHs associated with soot particles

International Nuclear Information System (INIS)

Kim, Daekyun; Young, Thomas M.; Anastasio, Cort

2013-01-01

Photodegradation is a key process governing the residence time and fate of polycyclic aromatic hydrocarbons (PAHs) in particles, both in the atmosphere and after deposition. We have measured photodegradation rate constants of PAHs in bulk deposits of soot particles illuminated with simulated sunlight. The photodegradation rate constants at the surface (k p 0 ), the effective diffusion coefficients (D eff ), and the light penetration depths (z 0.5 ) for PAHs on soot layers of variable thickness were determined by fitting experimental data with a model of coupled photolysis and diffusion. The overall disappearance rates of irradiated low molecular weight PAHs (with 2–3 rings) on soot particles were influenced by fast photodegradation and fast diffusion kinetics, while those of high molecular weight PAHs (with 4 or more rings) were apparently controlled by either the combination of slow photodegradation and slow diffusion kinetics or by very slow diffusion kinetics alone. The value of z 0.5 is more sensitive to the soot layer thickness than the k p 0 value. As the thickness of the soot layer increases, the z 0.5 values increase, but the k p 0 values are almost constant. The effective diffusion coefficients calculated from dark experiments are generally higher than those from the model fitting method for illumination experiments. Due to the correlation between k p 0 and z 0.5 in thinner layers, D eff should be estimated by an independent method for better accuracy. Despite some limitations of the model used in this study, the fitted parameters were useful for describing empirical results of photodegradation of soot-associated PAHs. - Highlights: ► PAHs on soot were evaluated by a model of coupled photolysis and diffusion. ► Photodegradation rate at the surface, diffusion coefficient, and light penetration path were determined. ► Low MW PAHs were influenced by fast photodegradation and fast diffusion. ► High MW PAHs were controlled either by slow

The way we encounter reading material influences how frequently we mind wander

OpenAIRE

Trish L Varao Sousa; Jonathan S A Carriere; Dan eSmilek

2013-01-01

We examined whether different encounters of reading material influence the likelihood of mind wandering, memory for the material, and the ratings of interest in the material. In a within-subjects design participants experienced three different reading encounters: (1) reading a passage aloud, (2) listening to a passage being read to them, and (3) reading a passage silently. Throughout each reading encounter probes were given in order to identify mind wandering. After finishing the passage part...

Particle creation rate for dynamical black holes

Energy Technology Data Exchange (ETDEWEB)

Firouzjaee, Javad T. [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); University of Oxford, Department of Physics (Astrophysics), Oxford (United Kingdom); Ellis, George F.R. [University of Cape Town, Mathematics and Applied Mathematics Department, Rondebosch (South Africa)

2016-11-15

We present the particle creation probability rate around a general black hole as an outcome of quantum fluctuations. Using the uncertainty principle for these fluctuation, we derive a new ultraviolet frequency cutoff for the radiation spectrum of a dynamical black hole. Using this frequency cutoff, we define the probability creation rate function for such black holes. We consider a dynamical Vaidya model and calculate the probability creation rate for this case when its horizon is in a slowly evolving phase. Our results show that one can expect the usual Hawking radiation emission process in the case of a dynamical black hole when it has a slowly evolving horizon. Moreover, calculating the probability rate for a dynamical black hole gives a measure of when Hawking radiation can be killed off by an incoming flux of matter or radiation. Our result strictly suggests that we have to revise the Hawking radiation expectation for primordial black holes that have grown substantially since they were created in the early universe. We also infer that this frequency cut off can be a parameter that shows the primordial black hole growth at the emission moment. (orig.)

Protoplanetary disc response to distant tidal encounters in stellar clusters

Science.gov (United States)

Winter, A. J.; Clarke, C. J.; Rosotti, G.; Booth, R. A.

2018-04-01

The majority of stars form in a clustered environment. This has an impact on the evolution of surrounding protoplanetary discs (PPDs) due to either photoevaporation or tidal truncation. Consequently, the development of planets depends on formation environment. Here, we present the first thorough investigation of tidally induced angular momentum loss in PPDs in the distant regime, partly motivated by claims in the literature for the importance of distant encounters in disc evolution. We employ both theoretical predictions and dynamical/hydrodynamical simulations in 2D and 3D. Our theoretical analysis is based on that of Ostriker (1994) and leads us to conclude that in the limit that the closest approach distance xmin ≫ r, the radius of a particle ring, the fractional change in angular momentum scales as (xmin/r)-5. This asymptotic limit ensures that the cumulative effect of distant encounters is minor in terms of its influence on disc evolution. The angular momentum transfer is dominated by the m = 2 Lindblad resonance for closer encounters and by the m = 1, ω = 0 Lindblad resonance at large xmin/r. We contextualize these results by comparing expected angular momentum loss for the outer edge of a PPD due to distant and close encounters. Contrary to the suggestions of previous works, we do not find that distant encounters contribute significantly to angular momentum loss in PPDs. We define an upper limit for closest approach distance where interactions are significant as a function of arbitrary host to perturber mass ratio M2/M1.

Surface Potential and Particle Size Effect on the Rate of Perikinetic Coagulation

International Nuclear Information System (INIS)

Molina-Bolivar, J. A.; Galisteo-Gonzalez, F.; Cabrerizo-Vilchez, M.; Hidalgo-alvarez, R.

1998-01-01

The diffusion-controlled rapid coagulation rate of monodisperse polystyrene particles in aqueous solutions has been measured with a low angle scattering apparatus (nephelometer). We have refined this technique by using a narrow scattering flow cell and a pneumatic addicting-mixing device to introduce the salt solution and the latex sample in the cell. Coagulation rate constants were determined from analysis of the scattered light intensity dependence with time at an angle of 4.5 degree centigrade ± 1 degree centigrade. Experiments were designed to check the effects of particle size, surface potential and counterion valency on rapid coagulation constant. The particle ranged in diameter from 151 nm to 530 nm. The results are compared with the predictions of Smoluchowski's theory. Experiments to obtain the stability diagrams and the critical coagulation concentration of latexes have been performed. (Author) 31 refs

A 3D particle Monte Carlo approach to studying nucleation

DEFF Research Database (Denmark)

Köhn, Christoph; Bødker Enghoff, Martin; Svensmark, Henrik

2018-01-01

The nucleation of sulphuric acid molecules plays a key role in the formation of aerosols. We here present a three dimensional particle Monte Carlo model to study the growth of sulphuric acid clusters as well as its dependence on the ambient temperature and the initial particle density. We initiate...... a swarm of sulphuric acid–water clusters with a size of 0.329 nm with densities between 107 and and 108 cm-3 at temperatures between 200 and 300 K and a relative humidity of 50%. After every time step, we update the position of particles as a function of size-dependent diffusion coefficients. If two...... particles encounter, we merge them and add their volumes and masses. Inversely, we check after every time step whether a polymer evaporates liberating a molecule. We present the spatial distribution as well as the size distribution calculated from individual clusters. We also calculate the nucleation rate...

A 3D particle Monte Carlo approach to studying nucleation

Science.gov (United States)

Köhn, Christoph; Enghoff, Martin Bødker; Svensmark, Henrik

2018-06-01

The nucleation of sulphuric acid molecules plays a key role in the formation of aerosols. We here present a three dimensional particle Monte Carlo model to study the growth of sulphuric acid clusters as well as its dependence on the ambient temperature and the initial particle density. We initiate a swarm of sulphuric acid-water clusters with a size of 0.329 nm with densities between 107 and 108 cm-3 at temperatures between 200 and 300 K and a relative humidity of 50%. After every time step, we update the position of particles as a function of size-dependent diffusion coefficients. If two particles encounter, we merge them and add their volumes and masses. Inversely, we check after every time step whether a polymer evaporates liberating a molecule. We present the spatial distribution as well as the size distribution calculated from individual clusters. We also calculate the nucleation rate of clusters with a radius of 0.85 nm as a function of time, initial particle density and temperature. The nucleation rates obtained from the presented model agree well with experimentally obtained values and those of a numerical model which serves as a benchmark of our code. In contrast to previous nucleation models, we here present for the first time a code capable of tracing individual particles and thus of capturing the physics related to the discrete nature of particles.

Universalist ethics in extraterrestrial encounter

Science.gov (United States)

Baum, Seth D.

2010-02-01

If humanity encounters an extraterrestrial civilization, or if two extraterrestrial civilizations encounter each other, then the outcome may depend not only on the civilizations' relative strength to destroy each other but also on what ethics are held by one or both civilizations. This paper explores outcomes of encounter scenarios in which one or both civilizations hold a universalist ethical framework. Several outcomes are possible in such scenarios, ranging from one civilization destroying the other to both civilizations racing to be the first to commit suicide. Thus, attention to the ethics of both humanity and extraterrestrials is warranted in human planning for such an encounter. Additionally, the possibility of such an encounter raises profound questions for contemporary human ethics, even if such an encounter never occurs.

Surgical Space Suits Increase Particle and Microbiological Emission Rates in a Simulated Surgical Environment.

Science.gov (United States)

Vijaysegaran, Praveen; Knibbs, Luke D; Morawska, Lidia; Crawford, Ross W

2018-05-01

The role of space suits in the prevention of orthopedic prosthetic joint infection remains unclear. Recent evidence suggests that space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause. This study aimed to compare the particle and microbiological emission rates (PER and MER) of space suits and standard surgical clothing. A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during 5 separate experiments. Particle counts were analyzed with 2 separate particle counters capable of detecting particles between 0.1 and 20 μm. An Andersen impactor was used to sample bacteria, with culture counts performed at 24 and 48 hours. Four experiments consistently showed statistically significant increases in both PER and MER when space suits are used compared with standard surgical clothing. One experiment showed inconsistent results, with a trend toward increases in both PER and MER when space suits are used compared with standard surgical clothing. Space suits cause increased PER and MER compared with standard surgical clothing. This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in clinical studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials

Science.gov (United States)

White, Bradley William

The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites is investigated in this work. Particle reinforced polymer composites show promise as structural energetic materials that can provide structural strength while simultaneously being capable of releasing large amounts of chemical energy through highly exothermic reactions occurring between the particles and with the matrix. This advanced class of materials is advantageous due to the decreased amount of high density inert casings needed for typical energetic materials and for their ability to increase payload expectancy and decrease collateral damage. Structural energetic materials can be comprised of reactive particles that undergo thermite or intermetallic reactions. In this work nickel (Ni) and aluminum (Al) particles were chosen as reinforcing constituents due to their well characterized mechanical and energetic properties. Although, the reactivity of nickel and aluminum is well characterized, the effects of their particle size, volume fractions, and spatial distribution on the mechanical behavior of the epoxy matrix and composite, across a large range of strain rates, are not well understood. To examine these effects castings of epoxy reinforced with 20--40 vol.% Al and 0--10 vol.% Ni were prepared, while varying the aluminum nominal particle size from 5 to 50 mum and holding the nickel nominal particle size constant at 50 mum. Through these variations eight composite materials were produced, possessing unique microstructures exhibiting different particle spatial distributions and constituent makeup. In order to correlate the microstructure to the constitutive response of the composites, techniques such as nearest-neighbor distances, and multiscale analysis of area fractions (MSAAF) were used to quantitatively characterize the microstructures. The composites were investigated under quasi-static and dynamic compressive loading conditions to characterize

Particle mis-identification rate algorithm for the CLIC ILD and CLIC SiD detectors

CERN Document Server

Nardulli, J

2011-01-01

This note describes the algorithm presently used to determine the particle mis- identification rate and gives results for single particles for the CLIC ILD and CLIC SiD detector concepts as prepared for the CLIC Conceptual Design Report.

Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

CERN Document Server

Kürten, Andreas; Almeida, Joao; Kupiainen-Määttä, Oona; Dunne, Eimear M.; Duplissy, Jonathan; Williamson, Christina; Barmet, Peter; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Flagan, Richard C.; Franchin, Alessandro; Gordon, Hamish; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Ickes, Luisa; Jokinen, Tuija; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Onnela, Antti; Ortega, Ismael K.; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schnitzhofer, Ralf; Schobesberger, Siegfried; Smith, James N.; Steiner, Gerhard; Stozhkov, Yuri; Tomé, António; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Wagner, Paul E.; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Ken; Kulmala, Markku; Curtius, Joachim

2016-01-01

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia arethought to be the dominant processes responsible for new particle formation (NPF) in the cold temperaturesof the middle and upper troposphere. Ions are also thought to be important for particle nucleation inthese regions. However, global models presently lack experimentally measured NPF rates under controlledlaboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here withdata obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets)chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. Theconditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrationsbet ween 5 × 105and 1 × 109cm3, and ammonia mixing ratios from zero added ammonia, i.e., nominally purebinary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation s...

A new balance formula to estimate new particle formation rate: reevaluating the effect of coagulation scavenging

Directory of Open Access Journals (Sweden)

R. Cai

2017-10-01

Full Text Available A new balance formula to estimate new particle formation rate is proposed. It is derived from the aerosol general dynamic equation in the discrete form and then converted into an approximately continuous form for analyzing data from new particle formation (NPF field campaigns. The new formula corrects the underestimation of the coagulation scavenging effect that occurred in the previously used formulae. It also clarifies the criteria for determining the upper size bound in measured aerosol size distributions for estimating new particle formation rate. An NPF field campaign was carried out from 7 March to 7 April 2016 in urban Beijing, and a diethylene glycol scanning mobility particle spectrometer equipped with a miniature cylindrical differential mobility analyzer was used to measure aerosol size distributions down to ∼ 1 nm. Eleven typical NPF events were observed during this period. Measured aerosol size distributions from 1 nm to 10 µm were used to test the new formula and the formulae widely used in the literature. The previously used formulae that perform well in a relatively clean atmosphere in which nucleation intensity is not strong were found to underestimate the comparatively high new particle formation rate in urban Beijing because of their underestimation or neglect of the coagulation scavenging effect. The coagulation sink term is the governing component of the estimated formation rate in the observed NPF events in Beijing, and coagulation among newly formed particles contributes a large fraction to the coagulation sink term. Previously reported formation rates in Beijing and in other locations with intense NPF events might be underestimated because the coagulation scavenging effect was not fully considered; e.g., estimated formation rates of 1.5 nm particles in this campaign using the new formula are 1.3–4.3 times those estimated using the formula neglecting coagulation among particles in the nucleation mode.

FORMATION OF CENTAURS’ RINGS THROUGH THEIR PARTIAL TIDAL DISRUPTION DURING PLANETARY ENCOUNTERS

Energy Technology Data Exchange (ETDEWEB)

Hyodo, Ryuki; Charnoz, Sébastien [Institut de Physique du Globe, F-75005 Paris, France (France); Genda, Hidenori [Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Ohtsuki, Keiji [Department of Planetology, Kobe University, Kobe 657-8501 (Japan)

2016-09-01

Centaurs are minor planets orbiting between Jupiter and Neptune that have or had crossing orbits with one or more giant planets. Recent observations and reinterpretation of previous observations have revealed the existence of ring systems around 10199 Chariklo and 2060 Chiron. However, the origin of the ring systems around such a minor planet is still an open question. Here, we propose that the tidal disruption of a differentiated object that experiences a close encounter with a giant planet could naturally form diverse ring–satellite systems around the Centaurs. During the close encounter, the icy mantle of the passing object is preferentially ripped off by the planet's tidal force and the debris is distributed mostly within the Roche limit of the largest remnant body. Assuming the existence of a 20−50 wt% silicate core below the icy mantle, a disk of particles is formed when the objects pass within 0.4–0.8 of the planet's Roche limit with the relative velocity at infinity 3−6 km s{sup −1} and 8 hr initial spin period of the body. The resultant ring mass is 0.1%–10% of the central object's mass. Such particle disks are expected to spread radially, and materials spreading beyond the Roche limit would accrete into satellites. Our numerical results suggest that ring formation would be a natural outcome of such extreme close encounters, and Centaurs can naturally have such ring systems because they cross the orbits of the giant planets.

FORMATION OF CENTAURS’ RINGS THROUGH THEIR PARTIAL TIDAL DISRUPTION DURING PLANETARY ENCOUNTERS

International Nuclear Information System (INIS)

Hyodo, Ryuki; Charnoz, Sébastien; Genda, Hidenori; Ohtsuki, Keiji

2016-01-01

Centaurs are minor planets orbiting between Jupiter and Neptune that have or had crossing orbits with one or more giant planets. Recent observations and reinterpretation of previous observations have revealed the existence of ring systems around 10199 Chariklo and 2060 Chiron. However, the origin of the ring systems around such a minor planet is still an open question. Here, we propose that the tidal disruption of a differentiated object that experiences a close encounter with a giant planet could naturally form diverse ring–satellite systems around the Centaurs. During the close encounter, the icy mantle of the passing object is preferentially ripped off by the planet's tidal force and the debris is distributed mostly within the Roche limit of the largest remnant body. Assuming the existence of a 20−50 wt% silicate core below the icy mantle, a disk of particles is formed when the objects pass within 0.4–0.8 of the planet's Roche limit with the relative velocity at infinity 3−6 km s"−"1 and 8 hr initial spin period of the body. The resultant ring mass is 0.1%–10% of the central object's mass. Such particle disks are expected to spread radially, and materials spreading beyond the Roche limit would accrete into satellites. Our numerical results suggest that ring formation would be a natural outcome of such extreme close encounters, and Centaurs can naturally have such ring systems because they cross the orbits of the giant planets.

An inverse modeling procedure to determine particle growth and nucleation rates from measured aerosol size distributions

Directory of Open Access Journals (Sweden)

B. Verheggen

2006-01-01

Full Text Available Classical nucleation theory is unable to explain the ubiquity of nucleation events observed in the atmosphere. This shows a need for an empirical determination of the nucleation rate. Here we present a novel inverse modeling procedure to determine particle nucleation and growth rates based on consecutive measurements of the aerosol size distribution. The particle growth rate is determined by regression analysis of the measured change in the aerosol size distribution over time, taking into account the effects of processes such as coagulation, deposition and/or dilution. This allows the growth rate to be determined with a higher time-resolution than can be deduced from inspecting contour plots ('banana-plots''. Knowing the growth rate as a function of time enables the evaluation of the time of nucleation of measured particles of a certain size. The nucleation rate is then obtained by integrating the particle losses from time of measurement to time of nucleation. The regression analysis can also be used to determine or verify the optimum value of other parameters of interest, such as the wall loss or coagulation rate constants. As an example, the method is applied to smog chamber measurements. This program offers a powerful interpretive tool to study empirical aerosol population dynamics in general, and nucleation and growth in particular.

Whole house particle removal and clean air delivery rates for in-duct and portable ventilation systems.

Science.gov (United States)

Macintosh, David L; Myatt, Theodore A; Ludwig, Jerry F; Baker, Brian J; Suh, Helen H; Spengler, John D

2008-11-01

A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-microm particles ranged from 1.5 hr(-1) during operation of an in-duct, 5-in. pleated media filter to 7.2 hr(-1) for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr(-1) when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) mass concentrations were 0.5 hr(-1) under baseline conditions, 0.5 hr(-1) during operation of three portable ionic air cleaners, 1 hr(-1) for an in-duct 1-in. media filter, 2.4 hr(-1) for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr(-1) for an in-duct 5-in. media filter, 4.7 hr(-1) during operation of five portable HEPA filters, 6.1 hr(-1) for a conventional in-duct electronic air cleaner, and 7.5 hr(-1) for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m3/min for the conventional media filter to 32 m3/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates.

Impact Of Particle Agglomeration On Accumulation Rates In The Glass Discharge Riser Of HLW Melter

International Nuclear Information System (INIS)

Kruger, A. A.; Rodriguez, C. A.; Matyas, J.; Owen, A. T.; Jansik, D. P.; Lang, J. B.

2012-01-01

The major factor limiting waste loading in continuous high-level radioactive waste (HLW) melters is an accumulation of particles in the glass discharge riser during a frequent and periodic idling of more than 20 days. An excessive accumulation can produce robust layers a few centimeters thick, which may clog the riser, preventing molten glass from being poured into canisters. Since the accumulation rate is driven by the size of particles we investigated with x-ray microtomography, scanning electron microscopy, and image analysis the impact of spinel forming components, noble metals, and alumina on the size, concentration, and spatial distribution of particles, and on the accumulation rate. Increased concentrations of Fe and Ni in the baseline glass resulted in the formation of large agglomerates that grew over the time to an average size of ∼185+-155 μm, and produced >3 mm thick layer after 120 h at 850 deg C. The noble metals decreased the particle size, and therefore significantly slowed down the accumulation rate. Addition of alumina resulted in the formation of a network of spinel dendrites which prevented accumulation of particles into compact layers

Fermi level equilibration between colloidal lead and silver particles in aqueous solution

International Nuclear Information System (INIS)

Henglein, A.; Holzwarth, A.; Mulvaney, P.

1992-01-01

Colloidal solutions of lead and silver were mixed under the exclusion of air. The equilibration of the Fermi levels in the two different types of metal particles took place over a few days at room temperature. The equilibration took place by the transfer of lead atoms from lead to silver particles until the latter carried a lead mantle of one to two monolayers. This could be concluded from the observed changes in the optical spectrum of the silver particles. The results are discussed in terms of two mechanisms: (1) Pb atom transfer following heterocoagulation of the lead and silver particles and (2) electron transfer during Brownian encounters, followed by Pb 2+ desorption from the lead particles and subsequent Pb 2+ reductor on the silver particles carrying the transferred electrons. Traces of methylviologen, MV 2+ , in the solution drastically increase the rate of equilibration; this is explained by a relay mechanism in which electrons in the lead particles are first picked up by MV 2+ and are then transferred from MV + to the silver particles. 2 refs., 4 figs

In vitro studies of copper release from powder particles in synthetic biological media

International Nuclear Information System (INIS)

Midander, Klara; Wallinder, Inger Odnevall; Leygraf, Christofer

2007-01-01

The aim of this paper is to provide quantitative data on copper release from powder particles of different copper materials, including artificial copper patina, Cu 2 O and metallic Cu, when exposed to different synthetic biological media to simulate an inhalation scenario and/or skin contact. Generated data may contribute in risk assessment of potential health effects following exposure to and handling of various copper materials. All tests were performed in vitro to determine total copper concentrations, release rates of total copper, and to elucidate its time-dependence. The copper release process was interpreted in terms of specific surface area, surface morphology-, and composition. All powder materials show a time-dependent release process with total copper release rates less than 3 μg/cm 2 per hour at steady state conditions, for all media investigated. The importance of using relevant test media when simulating different interstitial lung conditions and difficulties encountered when comparing powder particles of essentially different properties are thoroughly discussed. - Copper release rates from particles are essential to assess potential health aspects

Understanding metropolitan patterns of daily encounters.

Science.gov (United States)

Sun, Lijun; Axhausen, Kay W; Lee, Der-Horng; Huang, Xianfeng

2013-08-20

Understanding of the mechanisms driving our daily face-to-face encounters is still limited; the field lacks large-scale datasets describing both individual behaviors and their collective interactions. However, here, with the help of travel smart card data, we uncover such encounter mechanisms and structures by constructing a time-resolved in-vehicle social encounter network on public buses in a city (about 5 million residents). Using a population scale dataset, we find physical encounters display reproducible temporal patterns, indicating that repeated encounters are regular and identical. On an individual scale, we find that collective regularities dominate distinct encounters' bounded nature. An individual's encounter capability is rooted in his/her daily behavioral regularity, explaining the emergence of "familiar strangers" in daily life. Strikingly, we find individuals with repeated encounters are not grouped into small communities, but become strongly connected over time, resulting in a large, but imperceptible, small-world contact network or "structure of co-presence" across the whole metropolitan area. Revealing the encounter pattern and identifying this large-scale contact network are crucial to understanding the dynamics in patterns of social acquaintances, collective human behaviors, and--particularly--disclosing the impact of human behavior on various diffusion/spreading processes.

Innovative generativity of digital service encounters

DEFF Research Database (Denmark)

Henten, Anders; Sørensen, Jannick Kirk

2018-01-01

The research question examined in this chapter is how service encounters, based on digital interfaces, differ from face-to-face (f2f) encounters in terms of potential innovative generativity. New computer technologies facilitating big data processing and the development of advanced recommender...... systems and the recent developments of artificial intelligence with respect to cognitive and affective computing will certainly enhance the potential for innovations to be created on the basis of digital service encounters. However, the empathetic understanding of the needs and wants of the service users...... that can be part of the f2f service encounters cannot automatically result from digital service encounters. Digital tools can be developed and used to supplement the impressions that f2f encounters initiate. However, human interpretations and even human f2f encounters will also be needed to maintain...

Reduction of exposure to ultrafine particles by kitchen exhaust hoods: the effects of exhaust flow rates, particle size, and burner position.

Science.gov (United States)

Rim, Donghyun; Wallace, Lance; Nabinger, Steven; Persily, Andrew

2012-08-15

Cooking stoves, both gas and electric, are one of the strongest and most common sources of ultrafine particles (UFP) in homes. UFP have been shown to be associated with adverse health effects such as DNA damage and respiratory and cardiovascular diseases. This study investigates the effectiveness of kitchen exhaust hoods in reducing indoor levels of UFP emitted from a gas stove and oven. Measurements in an unoccupied manufactured house monitored size-resolved UFP (2 nm to 100 nm) concentrations from the gas stove and oven while varying range hood flow rate and burner position. The air change rate in the building was measured continuously based on the decay of a tracer gas (sulfur hexafluoride, SF(6)). The results show that range hood flow rate and burner position (front vs. rear) can have strong effects on the reduction of indoor levels of UFP released from the stove and oven, subsequently reducing occupant exposure to UFP. Higher range hood flow rates are generally more effective for UFP reduction, though the reduction varies with particle diameter. The influence of the range hood exhaust is larger for the back burner than for the front burner. The number-weighted particle reductions for range hood flow rates varying between 100 m(3)/h and 680 m(3)/h range from 31% to 94% for the front burner, from 54% to 98% for the back burner, and from 39% to 96% for the oven. Copyright © 2012 Elsevier B.V. All rights reserved.

The effect of coarse second-phase particles on the rate of grain refinement during severe deformation processing

DEFF Research Database (Denmark)

Apps, P.J.; Bowen, Jacob R.; Prangnell, P.B.

2003-01-01

The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg a...... by an effective strain of only five in the particle-containing alloy, compared to ten in the single-phase material. The mechanisms that contribute to this acceleration of the grain refinement process are discussed.......The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg...... alloy, deformed identically by ECAE to an effective strain of ten. The materials were analysed by high-resolution EBSD orientation mapping, which revealed that grain refinement occurred at a dramatically higher rate in the particle-containing alloy. A submicron grain structure could be achieved...

Plate-out rates of radon progeny and particles in a spherical chamber

International Nuclear Information System (INIS)

Cheng, Y.S.; Chen, B.T.

1990-01-01

In indoor and mining environments, deposition or ''plate-out'' of radon progeny onto walls occurs simultaneously with attachment of the radon progeny to airborne particles. Attachment and plate-out processes affect the atmosphere in which radon exposures takes place by reducing concentrations and shifting activity size distributions. Both processes have important consequences in determining the deposition pattern and initial dose of inhaled radon progeny. Theoretical deposition models show that turbulence and natural convection in a room are the major factors that influence plate-out rates. Here we describe plate-out measurements for radon progeny and aerosol particles in a spherical chamber under controlled laboratory conditions. The temperature and velocity profiles in still and turbulent air were monitored. A 161-liter spherical aluminum chamber was used to study the mixing. During mixing, air velocity was detected when rotational speeds were higher than 500 rpm. Monodisperse silver aerosols and polystyrene latex particles in the size range of 5 nm to 2 μm were used in the deposition study. Radon-220 progeny were generated by passing Rn-220 gas into the chamber and letting the gas decay into 212 Pb. The deposition rates of the particles and radon progeny ( 212 Pb) in the chamber were determined by monitoring the concentration decay of the aerosol as a function of time

Collaborative Project: Understanding the Chemical Processes tat Affect Growth rates of Freshly Nucleated Particles

Energy Technology Data Exchange (ETDEWEB)

McMurry, Peter [Univ. of Minnesota, Minneapolis, MN (United States); Smuth, James [University Corporation for Atmospheric Research, Irvine, CA (United States)

2015-11-12

This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate.

Evolution of Cometary Dust Particles to the Orbit of the Earth: Particle Size, Shape, and Mutual Collisions

Science.gov (United States)

Yang, Hongu; Ishiguro, Masateru

2018-02-01

In this study, we numerically investigated the orbital evolution of cometary dust particles, with special consideration of the initial size–frequency distribution (SFD) and different evolutionary tracks according to the initial orbit and particle shape. We found that close encounters with planets (mostly Jupiter) are the dominating factor determining the orbital evolution of dust particles. Therefore, the lifetimes of cometary dust particles (∼250,000 yr) are shorter than the Poynting–Robertson lifetime, and only a small fraction of large cometary dust particles can be transferred into orbits with small semimajor axes. The exceptions are dust particles from 2P/Encke and, potentially, active asteroids that have little interaction with Jupiter. We also found that the effects of dust shape, mass density, and SFD were not critical in the total mass supply rate to the interplanetary dust particle (IDP) cloud complex when these quantities are confined by observations of zodiacal light brightness and SFD around the Earth’s orbit. When we incorporate a population of fluffy aggregates discovered in the Earth’s stratosphere and the coma of 67P/Churyumov–Gerasimenko within the initial ejection, the initial SFD measured at the comae of comets (67P and 81P/Wild 2) can produce the observed SFD around the Earth’s orbit. Considering the above effects, we derived the probability of mutual collisions among dust particles within the IDP cloud for the first time in a direct manner via numerical simulation and concluded that mutual collisions can mostly be ignored.

Encounters with immigrant customers

DEFF Research Database (Denmark)

Mygind, Anna; Espersen, Sacha; Nørgaard, Lotte Stig

2013-01-01

were not sufficiently assessed at the counter (n = 55, 65%), and that their latest encounter with an immigrant customer was less satisfactory than a similar encounter with an ethnic Danish customer (n = 48, 57%) (significantly more pharmacists than assistants: odds ratio, OR, 3.19; 95% confidence...

The TDF System for Thermonuclear Plasma Reaction Rates, Mean Energies and Two-Body Final State Particle Spectra

International Nuclear Information System (INIS)

Warshaw, S I

2001-01-01

The rate of thermonuclear reactions in hot plasmas as a function of local plasma temperature determines the way in which thermonuclear ignition and burning proceeds in the plasma. The conventional model approach to calculating these rates is to assume that the reacting nuclei in the plasma are in Maxwellian equilibrium at some well-defined plasma temperature, over which the statistical average of the reaction rate quantity σv is calculated, where σ is the cross-section for the reaction to proceed at the relative velocity v between the reacting particles. This approach is well-understood and is the basis for much nuclear fusion and astrophysical nuclear reaction rate data. The Thermonuclear Data File (TDF) system developed at the Lawrence Livermore National Laboratory (Warshaw 1991), which is the topic of this report, contains data on the Maxwellian-averaged thermonuclear reaction rates for various light nuclear reactions and the correspondingly Maxwellian-averaged energy spectra of the particles in the final state of those reactions as well. This spectral information closely models the output particle and energy distributions in a burning plasma, and therefore leads to more accurate computational treatments of thermonuclear burn, output particle energy deposition and diagnostics, in various contexts. In this report we review and derive the theoretical basis for calculating Maxwellian-averaged thermonuclear reaction rates, mean particle energies, and output particle spectral energy distributions for these reactions in the TDF system. The treatment of the kinematics is non-relativistic. The current version of the TDF system provides exit particle energy spectrum distributions for two-body final state reactions only. In a future report we will discuss and describe how output particle energy spectra for three- and four-body final states can be developed for the TDF system. We also include in this report a description of the algorithmic implementation of the TDF

CLOSE STELLAR ENCOUNTERS IN YOUNG, SUBSTRUCTURED, DISSOLVING STAR CLUSTERS: STATISTICS AND EFFECTS ON PLANETARY SYSTEMS

International Nuclear Information System (INIS)

Craig, Jonathan; Krumholz, Mark R.

2013-01-01

Both simulations and observations indicate that stars form in filamentary, hierarchically clustered associations, most of which disperse into their galactic field once feedback destroys their parent clouds. However, during their early evolution in these substructured environments, stars can undergo close encounters with one another that might have significant impacts on their protoplanetary disks or young planetary systems. We perform N-body simulations of the early evolution of dissolving, substructured clusters with a wide range of properties, with the aim of quantifying the expected number and orbital element distributions of encounters as a function of cluster properties. We show that the presence of substructure both boosts the encounter rate and modifies the distribution of encounter velocities compared to what would be expected for a dynamically relaxed cluster. However, the boost only lasts for a dynamical time, and as a result the overall number of encounters expected remains low enough that gravitational stripping is unlikely to be a significant effect for the vast majority of star-forming environments in the Galaxy. We briefly discuss the implications of this result for models of the origin of the solar system, and of free-floating planets. We also provide tabulated encounter rates and orbital element distributions suitable for inclusion in population synthesis models of planet formation in a clustered environment.

CLOSE STELLAR ENCOUNTERS IN YOUNG, SUBSTRUCTURED, DISSOLVING STAR CLUSTERS: STATISTICS AND EFFECTS ON PLANETARY SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Craig, Jonathan; Krumholz, Mark R., E-mail: krumholz@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2013-06-01

Both simulations and observations indicate that stars form in filamentary, hierarchically clustered associations, most of which disperse into their galactic field once feedback destroys their parent clouds. However, during their early evolution in these substructured environments, stars can undergo close encounters with one another that might have significant impacts on their protoplanetary disks or young planetary systems. We perform N-body simulations of the early evolution of dissolving, substructured clusters with a wide range of properties, with the aim of quantifying the expected number and orbital element distributions of encounters as a function of cluster properties. We show that the presence of substructure both boosts the encounter rate and modifies the distribution of encounter velocities compared to what would be expected for a dynamically relaxed cluster. However, the boost only lasts for a dynamical time, and as a result the overall number of encounters expected remains low enough that gravitational stripping is unlikely to be a significant effect for the vast majority of star-forming environments in the Galaxy. We briefly discuss the implications of this result for models of the origin of the solar system, and of free-floating planets. We also provide tabulated encounter rates and orbital element distributions suitable for inclusion in population synthesis models of planet formation in a clustered environment.

Close Stellar Encounters in Young, Substructured, Dissolving Star Clusters: Statistics and Effects on Planetary Systems

Science.gov (United States)

Craig, Jonathan; Krumholz, Mark R.

2013-06-01

Both simulations and observations indicate that stars form in filamentary, hierarchically clustered associations, most of which disperse into their galactic field once feedback destroys their parent clouds. However, during their early evolution in these substructured environments, stars can undergo close encounters with one another that might have significant impacts on their protoplanetary disks or young planetary systems. We perform N-body simulations of the early evolution of dissolving, substructured clusters with a wide range of properties, with the aim of quantifying the expected number and orbital element distributions of encounters as a function of cluster properties. We show that the presence of substructure both boosts the encounter rate and modifies the distribution of encounter velocities compared to what would be expected for a dynamically relaxed cluster. However, the boost only lasts for a dynamical time, and as a result the overall number of encounters expected remains low enough that gravitational stripping is unlikely to be a significant effect for the vast majority of star-forming environments in the Galaxy. We briefly discuss the implications of this result for models of the origin of the solar system, and of free-floating planets. We also provide tabulated encounter rates and orbital element distributions suitable for inclusion in population synthesis models of planet formation in a clustered environment.

ACES M and S: Unmitigated Factorial Encounter Study on DAA/TCAS Interoperability

Science.gov (United States)

Thipphavong, David; Cone, Andrew; Park, Chunki; Lee, Seung Man; Santiago, Confesor

2016-01-01

Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements for DAA alerting and guidance systems. This presentation contains the results of two combinatorial encounter analysis studies using NASA's SAA Control fast-time simulation capability for this purpose. In these studies, encounters between two aircraft were simulated one at a time for the full factorial combination of encounter geometries (e.g., encounter angle, CPA offset) and aircraft performance (e.g., ownership and intruder ground speeds and vertical rates). The first study analyzes the relationships (e.g., timeline) between the different alerting-safety regions in the SC-228 MOPS (in order of increasing severity): 1) DAA warning alert, 2) well clear recovery (WCR) guidance, 3) DAA-Collision Avoidance (CA), and 4) TCAS RA. This study will focus primarily on encounter situations in which TCAS RA occurs prior to any of the other alerting-safety boundaries. In particular, this study will investigate whether using vertical distance or vertical distance at closest point of approach (i.e., vertical miss distance or VMD) is more appropriate for the definition of the DAA-CA region. In addition, cases where transitions between different regions skip an intermediate region will be analyzed. The second study in this presentation explores a proposal to use an altitude rate error threshold to determine if vertical maneuvers are acceptable for DAA WCR guidance against non-cooperative intruders. This study incorporates the radar from the Honeywell sensor model and examines a series of

Evaluation of salt particle collection device for preventing SCC on canister - Effect on particle collection rate by electric field

International Nuclear Information System (INIS)

Takeda, H.; Saegusa, T.

2013-01-01

Now, in Japan, while metal casks are used for spent nuclear fuel storage, a practical use of concrete casks is under review because of its cost effectiveness and procurement easiness. In reviewing the practical use, stress corrosion cracking (SCC) of a canister container in the concrete cask becomes an issue and is needed to be resolved soon. A natural ventilation system is generally adopted for the storage facilities, especially in Japan where facilities are built near coasts so that the cooling air includes sea salt particles. Therefore, the occurrence of SCC is concerned when the sea salt particles adhere to welded parts of the canisters. In this study, we proposed a salt particle collection device with low pressure loss which does not interfere with the air flow into the building or the concrete casks. The device is composed of a stack of 10 parallel stainless steel plates, the air is free to circulate in the space between them. Pressure loss tests in a laboratory and salt particle collection tests in the field have been performed. It has been clarified that the pressure loss of the device is one-thirtieth to one-twentieth of that of a commercial filter and 40% of the particles in the air could be collected and the device would not influence the heat removal performance. Moreover, we evaluated the effect of electric field on the particle collection under supposing the particle charge. In the case of electric field over 10 3 kV/m the particle collection rate could be improved dramatically

Critical rate of energy loss for registration of charged particles in cellulose nitrate

International Nuclear Information System (INIS)

Knoefel, T.M.J.; Sachett, I.A.

1979-09-01

Cellulose nitrate films LR-115 type II (Kodak-Pathe) have been exposed, at right angles, to alpha-particle beams in the energy range 2.5 - 5.5 MeV. From measurements of both through etched track density, a critical rate of energy lo ss for track registration of (0.85 +- 0.05) MeV cm 2 /mg has been derived, which corresponds to a critical alpha-particle energy of (4.6 +- 0.4) MeV. These results are compatible with those obtained by other authors whenever similar etching conditions are used. The concepts of threshold rate of energy loss and a threshold energy for etched-track formation are introduced, and their values are obtained from the experiment as being (0.80 +- 0.05) MeV cm 2 /mg and (5.1 +- 0.4) Mev, respectively. In addition, the present work provides a suitable set of useful, reference data for further applications of such plastic nuclear track detector in problems concerned with the detection of low-energy alpha particles. (Author) [pt

Realistic interpretation of quantum mechanics and encounter-delayed-choice experiment

Science.gov (United States)

Long, GuiLu; Qin, Wei; Yang, Zhe; Li, Jun-Lin

2018-03-01

In this paper, a realistic interpretation (REIN) of the wave function in quantum mechanics is briefly presented. We demonstrate that in the REIN, the wave function of a microscopic object is its real existence rather than a mere mathematical description. Specifically, the quantum object can exist in disjointed regions of space just as the wave function is distributed, travels at a finite speed, and collapses instantly upon a measurement. Furthermore, we analyze the single-photon interference in a Mach-Zehnder interferometer (MZI) using the REIN. Based on this, we propose and experimentally implement a generalized delayed-choice experiment, called the encounter-delayed-choice experiment, where the second beam splitter is decided whether or not to insert at the encounter of two sub-waves along the arms of the MZI. In such an experiment, the parts of the sub-waves, which do not travel through the beam splitter, show a particle nature, whereas the remaining parts interfere and thus show a wave nature. The predicted phenomenon is clearly demonstrated in the experiment, thus supporting the REIN idea.

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

Science.gov (United States)

Fischer, G.; Karakaş, G.

2009-01-01

The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling

Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

International Nuclear Information System (INIS)

Reedy, R.C.

1984-01-01

A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm -2 . Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures

The Art of the Encounter

Directory of Open Access Journals (Sweden)

Éric Vautrin

2013-03-01

Full Text Available As the archives from the second half of Grotowski’s life were made available, this text focuses on the Polish master’s conceptions of theatre where he describes theatre as the art of the encounter. This paper simultaneously places this proposition in the context of questions of a specific time period, and reveals how this encounter is the anathema that will revert viewpoints both about the art of acting and the creation of theatrical relations. These researches on theatre as the art of the encounter continue today through the Open Program, one of the two groups of the Workcenter of Jerzy Grotowski and Thomas Richards, and, notably, their creations around American poet Allen Ginsberg, an author whose poetry intends, in a similar way, to encounter the other and the world.

Scaling of the space-time correlation function of particle currents in a suspension of hard-sphere-like particles: exposing when the motion of particles is Brownian.

Science.gov (United States)

van Megen, W; Martinez, V A; Bryant, G

2009-12-18

The current correlation function is determined from dynamic light scattering measurements of a suspension of particles with hard spherelike interactions. For suspensions in thermodynamic equilibrium we find scaling of the space and time variables of the current correlation function. This finding supports the notion that the movement of suspended particles can be described in terms of uncorrelated Brownian encounters. However, in the metastable fluid, at volume fractions above freezing, this scaling fails.

Particle size distribution effect on burn rate of ammonium nitrate based propellant

NARCIS (Netherlands)

Miedema, J.R.; Klein, A.J.J.; Zee, F.W.M.

1995-01-01

Burn rate control of a Phase Stabilised Ammonium Nitrate (PSAN) propellant by specific surface area (SSA) tuning of the PSAN oxidiser resulted in unexpected effects of applying a new batch of PSAN having a different particle size distribution. Analysis of the deviations and consultation of

Encounter with comet Halley

International Nuclear Information System (INIS)

Sagdeev, R.Z.

1989-01-01

This paper reports on an international armada of six spacecraft which encountered the comet Halley and performed in-situ measurements. These encounters led to the discovery of a number of cometary plasma physics phenomena. Another important result was that a value for the average density of the cometary nucleus could be estimated, which is found to be compatible with snow ball models for the nucleus

Encounters with Pinyon-Juniper influence riskier movements in Greater Sage-Grouse across the Great Basin

Science.gov (United States)

Prochazka, Brian; Coates, Peter S.; Ricca, Mark; Casazza, Michael L.; Gustafson, K. Ben; Hull, Josh M.

2016-01-01

Fine-scale spatiotemporal studies can better identify relationships between individual survival and habitat fragmentation so that mechanistic interpretations can be made at the population level. Recent advances in Global Positioning System (GPS) technology and statistical models capable of deconstructing high-frequency location data have facilitated interpretation of animal movement within a behaviorally mechanistic framework. Habitat fragmentation due to singleleaf pinyon (Pinus monophylla; hereafter pinyon) and Utah juniper (Juniperus osteosperma; hereafter juniper) encroachment into sagebrush (Artemisia spp.) communities is a commonly implicated perturbation that can adversely influence greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) demographic rates. Using an extensive GPS data set (233 birds and 282,954 locations) across 12 study sites within the Great Basin, we conducted a behavioral change point analysis and subsequently constructed Brownian bridge movement models from each behaviorally homogenous section. We found a positive relationship between modeled movement rate and probability of encountering pinyon-juniper with significant variation among age classes. The probability of encountering pinyon-juniper among adults was two and three times greater than that of yearlings and juveniles, respectively. However, the movement rate in response to the probability of encountering pinyon-juniper trees was 1.5 times greater for juveniles. We then assessed the risk of mortality associated with an interaction between movement rate and the probability of encountering pinyon-juniper using shared frailty models. During pinyon-juniper encounters, on average, juvenile, yearling, and adult birds experienced a 10.4%, 0.2%, and 0.3% reduction in annual survival probabilities. Populations that used pinyon-juniper habitats with a frequency ≥ 3.8 times the overall mean experienced decreases in annual survival probabilities of 71.1%, 0.9%, and 0.9%. This

The Idealized Cultural Encounter

DEFF Research Database (Denmark)

Christiansen, Lene Bull

Studies into cultural encounters have predominantly taken point of departure in ‘problematic encounters’, in which researchers and participants see cultural difference as an obstacle on the road to harmonious relationships (e.g. in ‘the clash of civilisations,’ or in migration/integration studies......). This paper proposes to study cultural encounters which are organised around ideals of cultural difference as a positive social and political force. The Danish People to People NGO Mellemfolkeligt Samvirke (MS) is build around ideals of equality, co-operation, mutuality and solidarity between people...... and cultures. A prominent feature of the organisation is organised cultural encounters between Northern (predominantly Danish) volunteers and Africans, which takes place at ‘training centres’ both in Denmark and in African countries, such as Kenya or Tanzania. In this paper I will outline the theoretical...

Strengthening student communication through pediatric simulated patient encounters

Directory of Open Access Journals (Sweden)

Ryan Whitt

2014-08-01

Full Text Available As medical students enter the role of physician, clinical outcomes not only rely on their mastery of clinical knowledge, but also on the effectiveness in which they can communicate with patients and family members. While students typically have numerous opportunities to practice clinical communication with adult patients, such practice in pediatric settings is limited. This study examines if simulated patient (SP encounters strengthen third-year medical students’ communication skills during the pediatrics clerkship. During 2011-2013, three SP encounters (comprising 3 pediatric scenarios were incorporated into a pediatrics clerkship at one United States medical school to give students a safe venue to practice advanced communication with observation and direct feedback. Third-year medical students engaged in the scenarios and received both written and oral feedback from an evaluator observing the encounter. With IRB approval, students’ self-perceived confidence and abilities at performing the advanced communication skills were measured using an eightitem, Likert scale questionnaire administered pre and post the SP encounter. Pre- and post-questionnaires (n = 215; response rate, 96% analyzed using a Wilcoxon-matched pairs signed-rank test demonstrated statistically significant increases in students’ perception of their confidence and abilities regarding their performance (P < 0.05; Bonferroni correction, P < 0.006. There was an increases in student confidence and self-perceived ability in: first, communicating with children and family members of young patients; second, managing confrontational situations involving parents; third, performing a thorough psychosocial history with an adolescent; and fourth, using Evidence Based Medicine to motivate parents.

Bubbles and Dust: Dissolution Rates of Unhydrated Volcanic Ash as a Function of Morphology, Composition, and Particle Size

Science.gov (United States)

Wygel, C. M.; Sahagian, D. L.

2017-12-01

Volcanic eruptions are natural hazards due to their explosive nature and widespread transportation and deposition of ash particles. After deposition and subsequent leaching in soils or water bodies, ash deposition positively (nutrients) and negatively (contaminants) impacts the health of flora and fauna, including humans. The effects of ash leachates have been difficult to replicate in field and laboratory studies due to the many complexities and differences between ash particles. Ash morphology is characteristic for each eruption, dependent upon eruption energy, and should play a critical role in determining leaching rates. Morphology reflects overall particle surface area, which is strongly influenced by the presence of surface dust. In addition, ash composition, which in part controls morphology and particle size, may also affect leaching rates. This study determines the extent to which ash morphology, surface area, composition, and particle size control ash dissolution rates. Further, it is necessary to determine whether compound vesicular ash particles permit water into their interior structures to understand if both the internal and external surface areas are available for leaching. To address this, six fresh, unhydrated ash samples from diverse volcanic environments and a large range in morphology, from Pele's spheres to vesicular compound ash, are tested in the laboratory. Ash morphology was characterized on the Scanning Electron Microscope (SEM) before and after leaching and surface area was quantified by Brunauer Emmett Teller (BET) analysis and with geometric calculations. Column Leachate Tests (CLT) were conducted to compare leaching rates over a range of basaltic to silicic ashes as a function of time and surface area, to recreate the effects of ash deposition in diverse volcanic environments. After the CLT, post-leaching water analyses were conducted by Ion Coupled Plasma-Mass Spectrometry (ICP-MS) and Ion Chromatography (IC). We find that leaching

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

CERN Document Server

Kassel, Florian; Dabrowski, Anne; de Boer, Wim

2016-01-01

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field,...

Privacy encounters in Teledialogue

DEFF Research Database (Denmark)

Andersen, Lars Bo; Bøge, Ask Risom; Danholt, Peter

2017-01-01

Privacy is a major concern when new technologies are introduced between public authorities and private citizens. What is meant by privacy, however, is often unclear and contested. Accordingly, this article utilises grounded theory to study privacy empirically in the research and design project...... Teledialogue aimed at introducing new ways for public case managers and placed children to communicate through IT. The resulting argument is that privacy can be understood as an encounter, that is, as something that arises between implicated actors and entails some degree of friction and negotiation....... An argument which is further qualified through the philosophy of Gilles Deleuze. The article opens with a review of privacy literature before continuing to present privacy as an encounter with five different foci: what technologies bring into the encounter; who is related to privacy by implication; what...

Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

Energy Technology Data Exchange (ETDEWEB)

Smith, James N. [NCAR, Boulder, CO (United States); McMurry, Peter H. [NCAR, Boulder, CO (United States)

2015-11-12

This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

Web-based versus face-to-face interprofessional team encounters with standardized patients.

Science.gov (United States)

Lempicki, Kelly A; Holland, Christine S

2018-03-01

Challenges exist in developing interprofessional education (IPE) activities including coordinating schedules and obtaining appropriate space for teams to work. Virtual worlds have been explored as a means to overcome some of these challenges. We sought to develop a web-based interprofessional team interaction with a standardized patient (SP), as compared to a face-to-face SP interaction, focusing on the competency area of interprofessional communication. Interprofessional teams of students were randomized to complete a web-based or face-to-face SP encounter. The web-based encounter was conducted via video conference that students accessed using their own electronic device. Interprofessional communication was evaluated by faculty observers and the SPs. Participants of the web-based encounter also completed a perceptions questionnaire. Interprofessional communication was rated as average/above average by the authors and SPs. Perceptions of the web-based encounter were mixed with not all students willing to complete such an encounter again despite finding it enjoyable and a positive learning experience. The need for adequate preparation was identified, including the opportunity to review the patient case before the encounter. The web-based SP encounter afforded students the opportunity to utilize communication technology to provide patient-centered care while collaborating as an interprofessional team. Video conferencing presents an opportunity to bypass some logistical challenges in scheduling IPE experiences and can be implemented as a co-curricular activity, avoiding course revisions. Additional studies are needed to further explore student and patient perspectives and clarify when, and with what level of trainees, the experiences are most valuable. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of a generalized particle momentum distribution on plasma nuclear fusion rates

International Nuclear Information System (INIS)

Kim, Yeong E.; Zubarev, Alexander L.

2006-01-01

We investigate the effect of a generalized particle momentum distribution derived by Galitskii and Yakimets (GY) on nuclear reaction rates in plasma. We derive an approximate semi-analytical formula for nuclear fusion reaction rate between nuclei in a plasma (quantum plasma nuclear fusion; or QPNF). The QPNF formula is applied to calculate deuteron-deuteron fusion rate in a plasma, and the results are compared with the results calculated with the conventional Maxwell-Boltzmann velocity distribution. As an application, we investigate the deuteron-deuteron fusion rate for mobile deuterons in a deuterated metal/alloy. The calculated deuteron-deuteron fusion rates at low energies are enormously enhanced due to the modified tail of the GY's generalized momentum distribution. Our preliminary estimates indicate also that the deuteron-lithium (D+Li) fusion rate and the proton-lithium (p+Li) fusion rate in a metal/alloy at ambient temperatures are also substantially enhanced. (author)

Using measurements of the aerosol charging state in determination of the particle growth rate and the proportion of ion-induced nucleation

Directory of Open Access Journals (Sweden)

J. Leppä

2013-01-01

Full Text Available The fraction of charged nucleation mode particles as a function of particle diameter depends on the particle growth rate and the proportion of particles formed via ion-induced nucleation. In this study we have tested the applicability of recent data analysis methods to determine the growth rate and the proportion of ion-induced nucleation from the measured charged fractions. For this purpose we have conducted a series of aerosol dynamic simulations covering a wide range of atmospheric conditions. The growth rate and initial fraction of charged particles were estimated from simulated data using these methods and compared with the values obtained directly from the simulations. We found that the data analysis methods used in this study should not be used when the nuclei growth rate is less than ~3 nm h⁻¹, or when charged particles grow much more rapidly than neutral ones. Furthermore, we found that the difference in removal rates of neutral and charged particles should be taken into account when estimating the proportion of ion-induced nucleation. Neglecting the higher removal rate of charged particles compared with that of neutral ones could result in an underestimation of the proportion of ion-induced nucleation by up to a factor of 2. This underestimation is further increased if charged particles grow more rapidly than neutral ones. We also provided a simple way of assessing whether these methods are suitable for analyzing data measured under specific conditions. The assessment procedure was illustrated using a few examples of actual measurement sites with a more detailed examination of the typical conditions observed at the SMEAR II station in Hyytiälä, Finland.

Effect of Monomer Dosing Rate in the Preparation of Mesoporous Polystyrene Nanoparticles by Semicontinuous Heterophase Polymerization

Directory of Open Access Journals (Sweden)

Dalia Y. Sosa

2014-12-01

Full Text Available The semicontinuous heterophase polymerization of styrene in the presence of cross-linking and porogen agents was carried out. Latexes with close to 20% solid content, which contained mesoporous nanoparticles with 28 nm in average diameters, up to 0.5 cm3/g in porosity and 6–8 nm in pore diameters were obtained. By varying the monomer dosing rate over the micellar solution, an unexpected direct dependence of instantaneous conversion on the monomer dosing rate was found. This was ascribed to the higher average number of radicals per particle attained in the polymerization at the higher dosing rate, which in turn would arise from the higher gel percentage in the polymer. It is believed that the cross-linked chains prevent encounters between radicals, delaying the bimolecular termination reactions and allowing the existence of more than one radical inside the particles, which in turn increases the propagation rate.

Slew-rate dependence of tracer magnetization response in magnetic particle imaging

Science.gov (United States)

Shah, Saqlain A.; Ferguson, R. M.; Krishnan, K. M.

2014-10-01

Magnetic Particle Imaging (MPI) is a new biomedical imaging technique that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide nanoparticle tracers. Currently, 25 kHz and 20 mT/μ0 excitation fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. Here, we address fundamental questions about MPI tracer magnetization dynamics and predict tracer performance in future scanners that employ new combinations of excitation field amplitude (Ho) and frequency (ω). Using an optimized, monodisperse MPI tracer, we studied how several combinations of drive field frequencies and amplitudes affect the tracer's response, using Magnetic Particle Spectrometry and AC hysteresis, for drive field conditions at 15.5, 26, and 40.2 kHz, with field amplitudes ranging from 7 to 52 mT/μ0. For both fluid and immobilized nanoparticle samples, we determined that magnetic response was dominated by Néel reversal. Furthermore, we observed that the peak slew-rate (ωHo) determined the tracer magnetic response. Smaller amplitudes provided correspondingly smaller field of view, sometimes resulting in excitation of minor hysteresis loops. Changing the drive field conditions but keeping the peak slew-rate constant kept the tracer response almost the same. Higher peak slew-rates led to reduced maximum signal intensity and greater coercivity in the tracer response. Our experimental results were in reasonable agreement with Stoner-Wohlfarth model based theories.

Fluidization of spherocylindrical particles

Science.gov (United States)

Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

2017-06-01

Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

Aperture and counting rate of rectangular telescopes for single and multiple parallel particles. [Spark chamber telescopes

Energy Technology Data Exchange (ETDEWEB)

D' Ettorre Piazzoli, B; Mannocchi, G [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Melone, S [Istituto di Fisica dell' Universita, Ancona, Italy; Picchi, P; Visentin, R [Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Laboratori Nazionali di Frascati

1976-06-01

Expressions for the counting rate of rectangular telescopes in the case of single as well as multiple particles are given. The aperture for single particles is obtained in the form of a double integral and analytical solutions are given for some cases. The intensity for different multiplicities of parallel particles is related to the geometry of the detectors and to the features of the radiation. This allows an absolute comparison between the data recorded by different devices.

Influence of particle size on the low and high strain rate behavior of dense colloidal dispersions of nanosilica

Energy Technology Data Exchange (ETDEWEB)

Asija, Neelanchali; Chouhan, Hemant; Gebremeskel, Shishay Amare; Bhatnagar, Naresh, E-mail: nareshb@mech.iitd.ac.in [Indian Institute of Technology Delhi, Mechanical Engineering Department (India)

2017-01-15

Shear thickening is a non-Newtonian flow behavior characterized by the increase in apparent viscosity with the increase in applied shear rate, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this remarkable property of shear-thickening fluids (STFs), they are extensively used in hip protection pads, protective gear for athletes, and more recently in body armor. The use of STFs in body armor has led to the development of the concept of liquid body armor. In this study, the effect of particle size is explored on the low and high strain rate behavior of nanosilica dispersions, so as to predict the efficacy of STF-aided personal protection systems (PPS), specifically for ballistic applications. The low strain rate study was conducted on cone and plate rheometer, whereas the high strain rate characterization of STF was conducted on in-house fabricated split Hopkinson pressure bar (SHPB) system. Spherical nanosilica particles of three different sizes (100, 300, and 500 nm) as well as fumed silica particles of four different specific surface areas (Aerosil A-90, A-130, A-150, and A-200), respectively, were used in this study. The test samples were prepared by dispersing nanosilica particles in polypropylene glycol (PPG) using ultrasonic homogenization method. The low strain rate studies aided in determining the CSR of the synthesized STF dispersions, whereas the high strain rate studies explored the impact-resisting ability of STFs in terms of the impact toughness and the peak stress attained during the impact loading of STF in SHPB testing.

Age as a risk factor for the disruption of cognitive performance by exposure to the types of radiation encounted on exploratory class missions to other planets

Science.gov (United States)

Exposure to the types of radiation encountered in space (particles of high energy and charge [HZE particles]) produces changes in neurocognitive performance similar to those observed in the aged organism. As such, it is possible that there would be an interaction between the effects of exposure to ...

Charged-particle thermonuclear reaction rates: II. Tables and graphs of reaction rates and probability density functions

International Nuclear Information System (INIS)

Iliadis, C.; Longland, R.; Champagne, A.E.; Coc, A.; Fitzgerald, R.

2010-01-01

Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14 to 40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this issue (Paper I). We present a low rate, median rate and high rate which correspond to the 0.16, 0.50 and 0.84 quantiles, respectively, of the cumulative reaction rate distribution. The meaning of these quantities is in general different from the commonly reported, but statistically meaningless expressions, 'lower limit', 'nominal value' and 'upper limit' of the total reaction rate. In addition, we approximate the Monte Carlo probability density function of the total reaction rate by a lognormal distribution and tabulate the lognormal parameters μ and σ at each temperature. We also provide a quantitative measure (Anderson-Darling test statistic) for the reliability of the lognormal approximation. The user can implement the approximate lognormal reaction rate probability density functions directly in a stellar model code for studies of stellar energy generation and nucleosynthesis. For each reaction, the Monte Carlo reaction rate probability density functions, together with their lognormal approximations, are displayed graphically for selected temperatures in order to provide a visual impression. Our new reaction rates are appropriate for bare nuclei in the laboratory. The nuclear physics input used to derive our reaction rates is presented in the subsequent paper of this issue (Paper III). In the fourth paper of this issue (Paper IV) we compare our new reaction rates to previous results.

An experimental study of particle-bubble interaction and attachment in flotation

KAUST Repository

Sanchez Yanez, Aaron

2017-01-01

bubbles were observed using two high speed cameras. The cameras were placed perpendicular to each other allowing to reconstruct the three-dimensional position of the particle, the bubble and the particle-bubble aggregate. A single size of particle was used varying the size for the bubbles. It was found that the attachment of a particle to a bubble depends on its degree of hydrophobicity and on the relative position of the particle and the bubble before they encounter.

Enhancement and degradation of the R2* relaxation rate resulting from the encapsulation of magnetic particles with hydrophilic coatings.

Science.gov (United States)

de Haan, Hendrick W; Paquet, Chantal

2011-12-01

The effects of including a hydrophilic coating around the particles are studied across a wide range of particle sizes by performing Monte Carlo simulations of protons diffusing through a system of magnetic particles. A physically realistic methodology of implementing the coating by cross boundary jump scaling and transition probabilities at the coating surface is developed. Using this formulation, the coating has three distinct impacts on the relaxation rate: an enhancement at small particle sizes, a degradation at intermediate particle sizes, and no effect at large particles sizes. These varied effects are reconciled with the underlying dephasing mechanisms by using the concept of a full dephasing zone to present a physical picture of the dephasing process with and without the coating for all sizes. The enhancement at small particle sizes is studied systemically to demonstrate the existence of an optimal ratio of diffusion coefficients inside/outside the coating to achieve maximal increase in the relaxation rate. Copyright © 2011 Wiley Periodicals, Inc.

Physician assistant program education on spirituality and religion in patient encounters.

Science.gov (United States)

Berg, Gina M; Whitney, Melissa P; Wentling, Callie J; Hervey, Ashley M; Nyberg, Sue

2013-01-01

To describe educational practices of physician assistant (PA) programs regarding spirituality and religion discussions during patient encounters. Patients want their health care provider to be aware of their spiritual and religious beliefs. This topic is addressed in physician and nursing education but may not be included in PA programs. Data regarding curriculum were collected via electronic survey emailed to 143 PA programs across the United States. Thirty-eight programs responded for a response rate of 27%. Most (68.4%) program respondents reported students' desire to be trained to discuss spirituality and religion, yet 36.8% do not offer this training. Just over half (69.2%) would consider adding curriculum to teach students to discuss spirituality, but the majority (92.3%) would not add curriculum to discuss religion during patient encounters. PA programs offer training to discuss spirituality in patient encounters but not to discuss religiosity. Programs may want to consider adding some curriculum to increase PAs awareness of spirituality and religion needs of patients.

Encounters in cancer treatment

DEFF Research Database (Denmark)

Høybye, Mette Terp; Tjørnhøj-Thomsen, Tine

2014-01-01

Based on extensive ethnographic material from in-depth interviews with Danish cancer patients after treatment, this study analyzes their stories to explore how interactions with the physician configures and situates a need for rehabilitation. We identify three themes in the illness stories: (1...... by this encounter. The significance of the social encounters in cancer treatment is elucidated through this analysis, and we demonstrate how the need for recognition of the complex effects of cancer on one's life is central to counter experiences of objectification and dehumanization....

[A tale of two encounters].

Science.gov (United States)

Chanel, Marie-Paule

The moving testimony of a patient shows the impact which a successful encounter can have. Beyond the positive clinical consequences, her rediscovered motivation and pleasure are the essential drivers which have guided her along the pathway of reconstruction. A tale of two encounters which have marked her life course. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Innovation from the ICT-based service encounter

DEFF Research Database (Denmark)

Henten, Anders

2012-01-01

The pupose of the paper is to develop a framework for analyzing the dynamics of innovations emanating from the ICT-based service encounters. Many innovations are based on the direct encounter between employees and customers, and the paper aims to extend the analysis of such encounters to ICT...

ASRS Reports on Wake Vortex Encounters

Science.gov (United States)

Connell, Linda J.; Taube, Elisa Ann; Drew, Charles Robert; Barclay, Tommy Earl

2010-01-01

ASRS is conducting a structured callback research project of wake vortex incidents reported to the ASRS at all US airports, as well as wake encounters in the enroute environment. This study has three objectives: (1) Utilize the established ASRS supplemental data collection methodology and provide ongoing analysis of wake vortex encounter reports; (2) Document event dynamics and contributing factors underlying wake vortex encounter events; and (3) Support ongoing FAA efforts to address pre-emptive wake vortex risk reduction by utilizing ASRS reporting contributions.

Initial Encounters : The Lived Experiences of Buyers

NARCIS (Netherlands)

G. Wright; J.J. Dekker

2012-01-01

The initial encounter between a buyer and a seller has received much attention among practitioners. The first time a buyer interacts with a seller is thought to be highly influential. The premise is that buyers form an opinion during this first encounter, or even the first minutes of this encounter.

Scientific misconduct encountered by APAME journals: an online survey.

Science.gov (United States)

Looi, Lai-Meng; Wong, Li Xuan; Koh, Cing Chai

2015-12-01

In June 2015, invitations were sent by email to 151 APAME journals to participate in an online survey with an objective of gaining insight into the common publication misconduct encountered by APAME editors. The survey, conducted through SurveyMonkey over a 20-day-period, comprised 10 questions with expansions to allow anecdotes limited to 400 characters, estimated to take less than 10 minutes to complete. Only one invitation was issued per journal, targeting (in order of priority) editors, editorial board members and editorial staff, and limited by email availability. 54 (36%) journals responded. 98% of respondents held Editor or Editorial Board positions. All respondent journals have editorial policies on publication ethics and 96% provide instructions related to ethics. 45% use anti-plagiarism software to screen manuscripts, the most popular being iThenticate, CrossCheck and Turnitin. Up to 50% of journals had encountered studies without IRB approval. Author misconduct encountered were (in rank order): plagiarism (75%), duplicate publication (58%), unjustified authorship (39%), authorship disputes (33%), data falsification (29%), data/image manipulation (27%), conflict of interest (25%), copyright violation (17%) and breach of confidentiality (10%). Reviewer misconduct encountered were: conflict of interest (19%), plagiarism (17%), obstructive behavior (17%), abusive language (13%) and breach of confidentiality (13%). Notwithstanding the limitations of the survey and the response rate, a few insights have been gained: (1) the need for strengthening the ethical culture of researchers/authors and reviewers, (2) anti-plagiarism software can improve plagiarism detection by about 15%, and (3) the need for technical support to detect plagiarism, duplicate publication and image manipulation.

LHC experiences close encounters with UFOs

CERN Multimedia

Mike Lamont for the LHC Team

2011-01-01

On 29 May, yet another record was set as 1092 bunches per beam were injected into the LHC, hitting a peak luminosity of 1.26x1033 cm-2 s-1. While running at 3.5 TeV each beam now packs a total energy of over 70 MJ – equivalent to a TGV travelling at a 70 kph.   Operators in the LHC Control Centre happily show off their display screens after succesfully injecting 1092 bunches injected into the machine for the first time.  As the total beam intensity has been pushed up, the LHC has encountered a number of related problems, such as the so-called UFOs (Unidentified Falling Objects). These are thought to be dust particles falling through the beam, causing localized beam loss. The losses can push nearby beam loss monitors over the threshold and dump the beam. This is more of an annoyance than a danger for the LHC, but UFOs do reduce the operational efficiency of the machine. Despite this, the luminosity delivered to the experiments has steadily increased. On three occasions there ha...

The space of togetherness--a caring encounter.

Science.gov (United States)

Holopainen, Gunilla; Kasén, Anne; Nyström, Lisbet

2014-03-01

Encounters in relation to the nurse-patient relationship are often discussed within nursing and caring literature without a reflection on the actual meaning of the concept. Assuming that an encounter is essential for nursing care, this article seeks to create a deeper understanding of the concept through a hermeneutic approach to texts by the philosophers Buber and Marcel. Presence, recognition, availability and mutuality seem to be essential prerequisites for an encounter. As these prerequisites are fulfilled within and between human beings who encounter each other, it is possible to speak of a space of togetherness, a mutual existence, where life's mystery shines forth and caring is realized. The challenge lies in creating these encounters within nursing care. © 2012 The Authors Scandinavian Journal of Caring Sciences © 2012 Nordic College of Caring Science.

Exact Solutions of Fragmentation Equations with General Fragmentation Rates and Separable Particles Distribution Kernels

Directory of Open Access Journals (Sweden)

S. C. Oukouomi Noutchie

2014-01-01

Full Text Available We make use of Laplace transform techniques and the method of characteristics to solve fragmentation equations explicitly. Our result is a breakthrough in the analysis of pure fragmentation equations as this is the first instance where an exact solution is provided for the fragmentation evolution equation with general fragmentation rates. This paper is the key for resolving most of the open problems in fragmentation theory including “shattering” and the sudden appearance of infinitely many particles in some systems with initial finite particles number.

Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

International Nuclear Information System (INIS)

Mothilal, T.; Pitchandi, K.

2015-01-01

Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%

Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Mothilal, T. [T. J. S. Engineering College, Gummidipoond (India); Pitchandi, K. [Sri Venkateswara College of Engineering, Sriperumbudur (India)

2015-10-15

Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%.

Experimental Challenges and Successes in Measuring Aerosol Concentrations at Prototypic Spray Conditions Encountered at the Hanford Waste Treatment and Immobilization Plant - 13327

Energy Technology Data Exchange (ETDEWEB)

Bontha, J.R.; Gauglitz, P.A.; Kurath, D.E.; Adkins, H.E.; Enderlin, C.W.; Blanchard, J.; Daniel, R.C.; Song, C.; Schonewill, P.P.; Mahoney, L.A.; Buchmiller, W.C.; Boeringa, G.; Jenks, J. [Pacific Northwest National Laboratory, PO Box 999, Richland, Washington 99352 (United States)

2013-07-01

To date, majority of the work done on measuring aerosol releases from failure of process piping was done using simple Newtonian fluids and small engineered-nozzles that do not accurately represent the fluids and breaches postulated during accident analysis at the Hanford Waste Treatment and Immobilization Plant (WTP). In addition, the majority of the work conducted in this area relies on in-spray measurements that neglect the effect of splatter and do not yield any information regarding aerosol generation rates from this additional mechanism. In order to estimate aerosol generation rates as well as reduce the uncertainties in estimating the aerosol release fractions over a broad range of breaches, fluid properties and operating conditions encountered at the WTP, the Pacific Northwest National Laboratory (PNNL) has designed, commissioned, and tested two experimental test stands. The first test stand, referred to as the large-scale test stand, was designed specifically to measure aerosol concentrations and release fractions under prototypic conditions of flow and pressure for a range of breaches postulated in the hazard analysis for 0.076 m (3-inch) process pipes. However, the size of the large-scale test stand, anticipated fluid loss during a breach, experimental risks, and costs associated with hazardous chemical simulant testing limited the large-scale test stand utility to water and a few non-hazardous physical simulants that did not fully span the particle size and rheological properties of the fluids encountered at the WTP. Overcoming these limitations and extending the range of simulants used, required designing and building a smaller test stand, which was installed and operated in a fume hood. This paper presents some of the features of both test stands, the experimental challenges encountered, and successes in measuring aerosol concentration in both test stands over a range of test conditions. (authors)

Beyond the Embodied Digital Service Encounter

DEFF Research Database (Denmark)

Sørensen, Jannick Kirk

2018-01-01

When a digital service encounter develops differently than anticipated, the client becomes a user. This transformation reveals the ambiguous nature of digital service encounter being neither well-functioning tools, nor having the same sensitivity to and tolerance for service failures as in human ...

Environmental Catastrophes in the Earth's History Due to Solar Systems Encounters with Giant Molecular Clouds

Science.gov (United States)

Pavlov, Alexander A.

2011-01-01

In its motion through the Milky Way galaxy, the solar system encounters an average density (>=330 H atoms/cubic cm) giant molecular cloud (GMC) approximately every 108 years, a dense (approx 2 x 103 H atoms/cubic cm) GMC every approx 109 years and will inevitably encounter them in the future. However, there have been no studies linking such events with severe (snowball) glaciations in Earth history. Here we show that dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere during the solar system's immersion into a dense (approx ,2 x 103 H atoms/cubic cm) GMC. The stratospheric dust layer from such interstellar particles could provide enough radiative forcing to trigger the runaway ice-albedo feedback that results in global snowball glaciations. We also demonstrate that more frequent collisions with less dense GMCs could cause moderate ice ages.

Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth

Directory of Open Access Journals (Sweden)

Z. Wu

2013-07-01

Full Text Available This study examines the hygroscopicity of newly formed particles (diameters range 25–45 nm during two atmospheric new particle formation (NPF events in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010 (HCCT-2010 field experiment. At the end of the NPF event involving clear particle growth, we measured an unusually high soluble particle fraction of 58.5% at 45 nm particle size. The particle growth rate contributed through sulfuric acid condensation only accounts for around 6.5% of the observed growth rate. Estimations showed that sulfuric acid condensation explained, however, only around 10% of that soluble particle fraction. Therefore, the formation of additional water-soluble matter appears imperative to explain the missing soluble fraction. Although direct evidence is missing, we consider water-soluble organics as candidates for this mechanism. For the case with clear growth process, the particle growth rate was determined by two alternative methods based on tracking the mode diameter of the nucleation mode. The mean particle growth rate obtained from the inter-site data comparison using Lagrangian consideration is 3.8 (± 2.6 nm h−1. During the same period, the growth rate calculated based on one site data is 5.0 nm h−1 using log-normal distribution function method. In light of the fact that considerable uncertainties could be involved in both methods, we consider both estimated growth rates consistent.

Termite: Emulation Testbed for Encounter Networks

Directory of Open Access Journals (Sweden)

Rodrigo Bruno

2015-08-01

Full Text Available Cutting-edge mobile devices like smartphones and tablets are equipped with various infrastructureless wireless interfaces, such as WiFi Direct and Bluetooth. Such technologies allow for novel mobile applications that take advantage of casual encounters between co-located users. However, the need to mimic the behavior of real-world encounter networks makes testing and debugging of such applications hard tasks. We present Termite, an emulation testbed for encounter networks. Our system allows developers to run their applications on a virtual encounter network emulated by software. Developers can model arbitrary encounter networks and specify user interactions on the emulated virtual devices. To facilitate testing and debugging, developers can place breakpoints, inspect the runtime state of virtual nodes, and run experiments in a stepwise fashion. Termite defines its own Petri Net variant to model the dynamically changing topology and synthesize user interactions with virtual devices. The system is designed to efficiently multiplex an underlying emulation hosting infrastructure across multiple developers, and to support heterogeneous mobile platforms. Our current system implementation supports virtual Android devices communicating over WiFi Direct networks and runs on top of a local cloud infrastructure. We evaluated our system using emulator network traces, and found that Termite is expressive and performs well.

Joule heat production rate and the particle energy injection rate as a function of the geomagnetic indices AE and AL

International Nuclear Information System (INIS)

Ahn, B.; Akasofu, S.; Kamide, Y.

1983-01-01

As a part of the joint efforts of operating six meridian chains of magnetometers during the IMS, magnetic records from 71 stations are used to deduce the distribution of electric fields and currents in the polar ionosphere for March 17, 18, and 19, 1978. As a continuation of this project, we have constructed hourly distribution maps of the Joule heat production rate and their sum over the entire polar region on the three days. For this purpose the conductivity distribution is inferred at each instant partially on the basis of an empirical method devised by Ahn et al. (1982). The particle energy injection rate is estimated similarly by using an empirical method. The data set thus obtained allows us to estimate also the global Joule heat production rate U/sub J/, the global particle energy injection rate U/sub A/ and the sum U/sub Gamma/ of the two quantities. It is found that three global quantities (watt) are related almost linearly to the AE(nT) and AL(nT) indices. Our present estimates give the following relationships: U/sub J/ = 2.3 times 10 8 x AE 8 U/sub A/ = 0.6 times 10 8 x AE 8 and U/sub I/ = 2.9 times 10 8 x AE: U/sub J/ = 3.0 times 10 8 x AL 8 U/sub A/ = 0.8 times 10 8 x AL, and U/sub I/ = 3.8 times 10 8 x AL

Effect of particle-particle shearing on the bioleaching of sulfide minerals.

Science.gov (United States)

Chong, N; Karamanev, D G; Margaritis, A

2002-11-05

The biological leaching of sulfide minerals, used for the production of gold, copper, zinc, cobalt, and other metals, is very often carried out in slurry bioreactors, where the shearing between sulfide particles is intensive. In order to be able to improve the efficiency of the bioleaching, it is of significant importance to know the effect of particle shearing on the rate of leaching. The recently proposed concept of ore immobilization allowed us to study the effect of particle shearing on the rate of sulfide (pyrite) leaching by Thiobacillus ferrooxidans. Using this concept, we designed two very similar bioreactors, the main difference between which was the presence and absence of particle-particle shearing. It was shown that when the oxygen mass transfer was not the rate-limiting step, the rate of bioleaching in the frictionless bioreactor was 2.5 times higher than that in a bioreactor with particle friction (shearing). The concentration of free suspended cells in the frictionless bioreactor was by orders of magnitude lower than that in the frictional bioreactor, which showed that particle friction strongly reduces the microbial attachment to sulfide surface, which, in turn, reduces the rate of bioleaching. Surprisingly, it was found that formation of a layer of insoluble iron salts on the surface of sulfide particles is much slower under shearless conditions than in the presence of particle-particle shearing. This was explained by the effect of particle friction on liquid-solid mass transfer rate. The results of this study show that reduction of the particle friction during bioleaching of sulfide minerals can bring important advantages not only by increasing significantly the bioleaching rate, but also by increasing the rate of gas-liquid oxygen mass transfer, reducing the formation of iron precipitates and reducing the energy consumption. One of the efficient methods for reduction of particle friction is ore immobilization in a porous matrix. Copyright 2002

Protoplanetary disc truncation mechanisms in stellar clusters: comparing external photoevaporation and tidal encounters

Science.gov (United States)

Winter, A. J.; Clarke, C. J.; Rosotti, G.; Ih, J.; Facchini, S.; Haworth, T. J.

2018-04-01

Most stars form and spend their early life in regions of enhanced stellar density. Therefore the evolution of protoplanetary discs (PPDs) hosted by such stars are subject to the influence of other members of the cluster. Physically, PPDs might be truncated either by photoevaporation due to ultraviolet flux from massive stars, or tidal truncation due to close stellar encounters. Here we aim to compare the two effects in real cluster environments. In this vein we first review the properties of well studied stellar clusters with a focus on stellar number density, which largely dictates the degree of tidal truncation, and far ultraviolet (FUV) flux, which is indicative of the rate of external photoevaporation. We then review the theoretical PPD truncation radius due to an arbitrary encounter, additionally taking into account the role of eccentric encounters that play a role in hot clusters with a 1D velocity dispersion σv ≳ 2 km/s. Our treatment is then applied statistically to varying local environments to establish a canonical threshold for the local stellar density (nc ≳ 104 pc-3) for which encounters can play a significant role in shaping the distribution of PPD radii over a timescale ˜3 Myr. By combining theoretical mass loss rates due to FUV flux with viscous spreading in a PPD we establish a similar threshold for which a massive disc is completely destroyed by external photoevaporation. Comparing these thresholds in local clusters we find that if either mechanism has a significant impact on the PPD population then photoevaporation is always the dominating influence.

Global Diabetes Encounters

DEFF Research Database (Denmark)

Juul Nielsen, Annegrete; Langstrup, Henriette

2014-01-01

As already recognized, though little theorized within International Relations, the capacity of technology to ensure the achievement of preset policy goals is often grossly overrated. Drawing on Science and Technology Studies, this chapter proposes a lens to investigate global encounters, which ta...

Graphene supported Sn-Sb rate at carbon core-shell particles as a superior anode for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Chen, Shuangqiang; Chen, Peng; Wang, Yong [Department of Chemical Engineering, School of Environmental and Chemical Engineering, Shanghai University (China); Wu, Minghong; Pan, Dengyu [Institute of Nanochemistry and Nanobiology, Shanghai Univ. (China)

2010-10-15

This paper reports the preparation and Li-storage properties of graphene nanosheets(GNS), GNS supported Sn-Sb rate at carbon (50-150 nm) and Sn-Sb nanoparticles (5-10 nm). The best cycling performance and excellent high rate capabilities were observed for GNS-supported Sn-Sb rate at carbon core-shell particles, which exhibited initial capacities of 978, 850 and 668 mAh/g respectively at 0.1C, 2C and 5C (1C = 800 mA/g) with good cyclability. Besides the GNS support, the carbon skin around Sn-Sb particles is believed to be a key factor to improve electrochemical properties of Sn-Sb. (author)

Encounters of aircraft with volcanic ash clouds; A compilation of known incidents, 1953-2009

Science.gov (United States)

Guffanti, Marianne; Casadevall, Thomas J.; Budding, Karin

2010-01-01

Information about reported encounters of aircraft with volcanic ash clouds from 1953 through 2009 has been compiled to document the nature and scope of risks to aviation from volcanic activity. The information, gleaned from a variety of published and other sources, is presented in database and spreadsheet formats; the compilation will be updated as additional encounters occur and as new data and corrections come to light. The effects observed by flight crews and extent of aircraft damage vary greatly among incidents, and each incident in the compilation is rated according to a severity index. Of the 129 reported incidents, 94 incidents are confirmed ash encounters, with 79 of those having various degrees of airframe or engine damage; 20 are low-severity events that involve suspected ash or gas clouds; and 15 have data that are insufficient to assess severity. Twenty-six of the damaging encounters involved significant to very severe damage to engines and (or) airframes, including nine encounters with engine shutdown during flight. The average annual rate of damaging encounters since 1976, when reporting picked up, has been approximately 2 per year. Most of the damaging encounters occurred within 24 hours of the onset of ash production or at distances less than 1,000 kilometers from the source volcanoes. The compilation covers only events of relatively short duration for which aircraft were checked for damage soon thereafter; documenting instances of long-term repeated exposure to ash (or sulfate aerosols) will require further investigation. Of 38 source volcanoes, 8 have caused 5 or more encounters, of which the majority were damaging: Augustine (United States), Chaiten (Chile), Mount St. Helens (United States), Pacaya (Guatemala), Pinatubo (Philippines), Redoubt (United States), Sakura-jima (Japan), and Soufriere Hills (Montserrat, Lesser Antilles, United Kingdom). Aircraft have been damaged by eruptions ranging from small, recurring episodes to very large

Frontcountry encounter norms among three cultures

Science.gov (United States)

Jerry J. Vaske; Maureen P. Donnelly; Robert M. Doctor; James P. Petruzzi

1995-01-01

Existing normative studies have focused on backcountry encounter norms reported by North Americans. This study extends previous research by comparing encounter norms reported by three different cultures - North Americans, Europeans, and Japanese - in a frontcountry day use recreation area. Data were obtained from on-site surveys distributed at the Columbia Icefield in...

Cosmopolitan encounters

DEFF Research Database (Denmark)

Plage, Stefanie; Willing, Indigo; Woodward, Ian

2017-01-01

This study contributes to the growing research on everyday cosmopolitanism in diverse societies. We employ a cosmopolitan encounters framework to explore the reflexive openness people perform and the ethical reasoning they draw on to get along with each other. In particular, we look beyond....... The ethical framework we propose is grounded in reflexive acts of sharing going beyond notions of giving and performing hospitality within a host/guest dyad....

Due Regard Encounter Model Version 1.0

Science.gov (United States)

2013-08-19

Note that no existing model covers encoun- ters between two IFR aircraft in oceanic airspace. The reason for this is that one cannot observe encounters...encounters between instrument flight rules ( IFR ) and non- IFR traffic beyond 12NM. 2 TABLE 1 Encounter model categories. Aircraft of Interest Intruder...Aircraft Location Flight Rule IFR VFR Noncooperative Noncooperative Conventional Unconventional CONUS IFR C C U X VFR C U U X Offshore IFR C C U X VFR C U

High-velocity runaway stars from three-body encounters

Science.gov (United States)

Gvaramadze, V. V.; Gualandris, A.; Portegies Zwart, S.

2010-01-01

We performed numerical simulations of dynamical encounters between hard, massive binaries and a very massive star (VMS; formed through runaway mergers of ordinary stars in the dense core of a young massive star cluster) to explore the hypothesis that this dynamical process could be responsible for the origin of high-velocity (≥ 200 - 400 km s-1) early or late B-type stars. We estimated the typical velocities produced in encounters between very tight massive binaries and VMSs (of mass of ≥ 200 M⊙) and found that about 3 - 4% of all encounters produce velocities ≥ 400 km s-1, while in about 2% of encounters the escapers attain velocities exceeding the Milky Ways's escape velocity. We therefore argue that the origin of high-velocity (≥ 200 - 400 km s-1) runaway stars and at least some so-called hypervelocity stars could be associated with dynamical encounters between the tightest massive binaries and VMSs formed in the cores of star clusters. We also simulated dynamical encounters between tight massive binaries and single ordinary 50 - 100 M⊙ stars. We found that from 1 to ≃ 4% of these encounters can produce runaway stars with velocities of ≥ 300 - 400 km s-1 (typical of the bound population of high-velocity halo B-type stars) and occasionally (in less than 1% of encounters) produce hypervelocity (≥ 700 km s-1) late B-type escapers.

Measurement of Localized Corrosion Rates at Inclusion Particles in AA7075 by In Situ Three Dimensional (3D) X-ray Synchrotron Tomography

Energy Technology Data Exchange (ETDEWEB)

Singh, Sudhanshu S.; Williams, Jason J.; Stannard, Tyler J.; Xiao, Xianghui; De Carlo, Francesco; Chawla, Nikhilesh

2016-03-01

In situ X-ray synchrotron tomography was used to measure the localized corrosion rate of Mg2Si particles present in 7075 aluminum alloys in deionized ultra-filtered (DIUF) water. The evolution of hydrogen bubbles was captured as a function of time and the measured volume was used to calculate the local corrosion rate of Mg2Si particles. It was shown that in the absence of chloride ions, stress was needed to create fresh particle surfaces, either by fracture or debonding, to initiate corrosion at the particles.

Kinetics of small particle activation in supersaturated vapors

Energy Technology Data Exchange (ETDEWEB)

McGraw, R.; Wang, J.

2010-08-29

We examine the nucleated (with barrier) activation of perfectly wetting (zero contact angle) particles ranging from bulk size down to one nanometer. Thermodynamic properties of the particles, coated with liquid layers of varying thickness and surrounded by vapor, are analyzed. Nano-size particles are predicted to activate at relative humidity below the Kelvin curve on crossing a nucleation barrier, located at a critical liquid layer thickness such that the total particle size (core + liquid layer) equals the Kelvin radius (Fig. 1). This barrier vanishes precisely as the critical layer thickness approaches the thin layer limit and the Kelvin radius equals the radius of the particle itself. These considerations are similar to those included in Fletcher's theory (Fletcher, 1958) however the present analysis differs in several important respects. Firstly, where Fletcher used the classical prefactor-exponent form for the nucleation rate, requiring separate estimation of the kinetic prefactor, we solve a diffusion-drift equation that is equivalent to including the full Becker-Doering (BD) multi-state kinetics of condensation/evaporation along the growth coordinate. We also determine the mean first passage time (MFPT) for barrier crossing (Wedekind et al., 2007), which is shown to provide a generalization of BD nucleation kinetics especially useful for barrier heights that are considerably lower than those typically encountered in homogeneous vapor-liquid nucleation, and make explicit comparisons between the MFPT and BD kinetic models. Barrier heights for heterogeneous nucleation are computed by a thermo-dynamic area construction introduced recently to model deliquescence and efflorescence of small particles (McGraw and Lewis, 2009). In addition to providing a graphical representation of the activation process that offers new insights, the area construction provides a molecular approach that avoids explicit use of the interfacial tension. Typical barrier profiles for

Processing changes across reading encounters.

Science.gov (United States)

Levy, B A; Newell, S; Snyder, J; Timmins, K

1986-10-01

Five experiments examined changes in the processing of a text across reading encounters. Experiment 1 showed that reading speed increased systematically across encounters, with no loss in the extensiveness of analyses of the printed text, as indicated by the ability to detect nonword errors embedded within that passage. Experiment 2 replicated this improved reading fluency with experience and showed that it occurred even with typescript changes across trials, thus indicating that a primed visual operations explanation cannot account for the effect. The third and fourth experiments then extended the study of the familiarity effect to higher level processing, as indicated by the detection of word errors. Familiarity facilitated the detection of these violations at the syntactic-semantic levels. Finally, Experiment 5 showed that these higher level violations continued to be well detected over a series of reading encounters with the same text. The results indicate that prior experience improves reading speed, with no attenuation of analysis of the printed words or of the passage's message.

Predicting the Effects of Powder Feeding Rates on Particle Impact Conditions and Cold Spray Deposited Coatings

Science.gov (United States)

Ozdemir, Ozan C.; Widener, Christian A.; Carter, Michael J.; Johnson, Kyle W.

2017-10-01

As the industrial application of the cold spray technology grows, the need to optimize both the cost and the quality of the process grows with it. Parameter selection techniques available today require the use of a coupled system of equations to be solved to involve the losses due to particle loading in the gas stream. Such analyses cause a significant increase in the computational time in comparison with calculations with isentropic flow assumptions. In cold spray operations, engineers and operators may, therefore, neglect the effects of particle loading to simplify the multiparameter optimization process. In this study, two-way coupled (particle-fluid) quasi-one-dimensional fluid dynamics simulations are used to test the particle loading effects under many potential cold spray scenarios. Output of the simulations is statistically analyzed to build regression models that estimate the changes in particle impact velocity and temperature due to particle loading. This approach eases particle loading optimization for more complete analysis on deposition cost and time. The model was validated both numerically and experimentally. Further numerical analyses were completed to test the particle loading capacity and limitations of a nozzle with a commonly used throat size. Additional experimentation helped document the physical limitations to high-rate deposition.

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

Energy Technology Data Exchange (ETDEWEB)

Kassel, Florian; Boer, Wim de [Institute for Experimental Nuclear Physics (IEKP), KIT, Karlsruhe (Germany); Guthoff, Moritz; Dabrowski, Anne [CERN, Meyrin (Switzerland)

2016-10-15

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb{sup -1} corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate-dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the transient current technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model, the rate-dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate-dependent measurements from a strong radioactive source, was able to predict the non-linear decrease of the

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

International Nuclear Information System (INIS)

Kassel, Florian; Boer, Wim de; Guthoff, Moritz; Dabrowski, Anne

2016-01-01

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb -1 corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate-dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the transient current technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model, the rate-dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate-dependent measurements from a strong radioactive source, was able to predict the non-linear decrease of the CCE in

The GENGA code: gravitational encounters in N-body simulations with GPU acceleration

International Nuclear Information System (INIS)

Grimm, Simon L.; Stadel, Joachim G.

2014-01-01

We describe an open source GPU implementation of a hybrid symplectic N-body integrator, GENGA (Gravitational ENcounters with Gpu Acceleration), designed to integrate planet and planetesimal dynamics in the late stage of planet formation and stability analyses of planetary systems. GENGA uses a hybrid symplectic integrator to handle close encounters with very good energy conservation, which is essential in long-term planetary system integration. We extended the second-order hybrid integration scheme to higher orders. The GENGA code supports three simulation modes: integration of up to 2048 massive bodies, integration with up to a million test particles, or parallel integration of a large number of individual planetary systems. We compare the results of GENGA to Mercury and pkdgrav2 in terms of energy conservation and performance and find that the energy conservation of GENGA is comparable to Mercury and around two orders of magnitude better than pkdgrav2. GENGA runs up to 30 times faster than Mercury and up to 8 times faster than pkdgrav2. GENGA is written in CUDA C and runs on all NVIDIA GPUs with a computing capability of at least 2.0.

The GENGA code: gravitational encounters in N-body simulations with GPU acceleration

Energy Technology Data Exchange (ETDEWEB)

Grimm, Simon L.; Stadel, Joachim G., E-mail: sigrimm@physik.uzh.ch [Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)

2014-11-20

We describe an open source GPU implementation of a hybrid symplectic N-body integrator, GENGA (Gravitational ENcounters with Gpu Acceleration), designed to integrate planet and planetesimal dynamics in the late stage of planet formation and stability analyses of planetary systems. GENGA uses a hybrid symplectic integrator to handle close encounters with very good energy conservation, which is essential in long-term planetary system integration. We extended the second-order hybrid integration scheme to higher orders. The GENGA code supports three simulation modes: integration of up to 2048 massive bodies, integration with up to a million test particles, or parallel integration of a large number of individual planetary systems. We compare the results of GENGA to Mercury and pkdgrav2 in terms of energy conservation and performance and find that the energy conservation of GENGA is comparable to Mercury and around two orders of magnitude better than pkdgrav2. GENGA runs up to 30 times faster than Mercury and up to 8 times faster than pkdgrav2. GENGA is written in CUDA C and runs on all NVIDIA GPUs with a computing capability of at least 2.0.

Dental Encounter System (DES)

Data.gov (United States)

Department of Veterans Affairs — Dental Encounter System (DES) is an automated health care application designed to capture critical data about the operations of VA Dental Services. Information on...

MSFC Stream Model Preliminary Results: Modeling the 1998-2002 Leonid Encounters and the 1993,1994, and 2004 Perseid Encounters

Science.gov (United States)

Moser, D. E.; Cooke, W. J.

2004-01-01

The cometary meteoroid ejection models of Jones (1996) and Crifo (1997) were used to simulate ejection from comets 55P/Tempel-Tuttle during the last 12 revolutions, and the 1862, 1737, and 161 0 apparitions of 1 OSP/Swift-Tuttle. Using cometary ephemerides generated by the JPL HORIZONS Solar System Data and Ephemeris Computation Service, ejection was simulated in 1 hour time steps while the comet was within 2.5 AU of the Sun. Also simulated was ejection occurring at the hour of perihelion passage. An RK4 variable step integrator was then used to integrate meteoroid position and velocity forward in time, accounting for the effects of radiation pressure, Poynting-Robertson drag, and the gravitational forces of the planets, which were computed using JPL's DE406 planetary ephemerides. An impact parameter is computed for each particle approaching the Earth, and the results are compared to observations of the 1998-2002 Leonid showers, and the 1993-1 994 Perseids. A prediction for Earth's encounter with the Perseid stream in 2004 is also presented.

Determinants of customer satisfaction with service encounter

Directory of Open Access Journals (Sweden)

Ariana Nefat

2008-12-01

Full Text Available Service encounters are the focal point of a customer’s perception of a service in terms of its quality, value and customer satisfaction. The paper researches the influence of the components of a service encounter on customer satisfaction. Among several factors that determine customer satisfaction the quality of service, which is related to the characteristics of service, plays an important role. However, a direct insight into the reasons that make a service encounter satisfactory or unsatisfactory is provided by the critical incident technique, where causes of dis/satisfaction differ primarily depending on whether they derive from interpersonal contact or from contact with technology. The evidence of service, which includes people, process and the physical evidence, plays a critical role in a customer’s dis/satisfaction. The influence of these elements cannot be observed separately; it must be observed in their interaction during the delivery of service and their strongest effect is achieved during face-to-face service encounters that have the characteristics of a theatre metaphor. Even though a high level of satisfaction may be achieved after the recovery of a service, enterprises should aim to conduct excellent service encounters right from the start.

Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

Science.gov (United States)

Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

2015-01-15

The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles. Copyright © 2014. Published by Elsevier B.V.

Smelting reduction rate of fine Wustite particles in a CO gas-conveyed bed; CO gas yuso sonai Wustite biryushi no yoyu kangen sokudo

Energy Technology Data Exchange (ETDEWEB)

Hayashi, S; Iguchi, Y [Nagoya Institute of Technology, Nagoya (Japan)

1999-06-01

Using a laboratory scale fine particles-gas conveyed bed, the reduction rates of liquid wustite with CO gas were measured. CO-CO{sub 2} mixtures having various flow rates and compositions were flowed downward through a cylindrical reactor maintained at a constant temperature of 1,723 to 1,823K. A batch of pure spherical wustite particles (mean dia.: 48.5 {mu}m) was concurrently fed into the reactor at a small constant rate and reduced in a hot zone. The reduction process was found to proceed in such a manner that metallic iron particles were enclosed inside a wustite droplet. Rate analysis was made of one dimensional mass balance equations for particles and gas in a steady moving bed under an isothermal condition using the reaction rate for a single particle taking the shrinkage into consideration. Under relatively small reducing potentials, it was concluded that the major fraction of overall reaction resistance is attributable to chemical reaction. However, under higher reducing potentials, the reduction process was estimated to include some mass transfer resistances within the liquid oxide phase. From the temperature dependence of forward chemical reaction rate constants, the activation energy was evaluated to be 90.6 kJ/mol. (author)

Iteration particle swarm optimization for contract capacities selection of time-of-use rates industrial customers

International Nuclear Information System (INIS)

Lee, Tsung-Ying; Chen, Chun-Lung

2007-01-01

This paper presents a new algorithm for solving the optimal contract capacities of a time-of-use (TOU) rates industrial customer. This algorithm is named iteration particle swarm optimization (IPSO). A new index, called iteration best is incorporated into particle swarm optimization (PSO) to improve solution quality and computation efficiency. Expanding line construction cost and contract recovery cost are considered, as well as demand contract capacity cost and penalty bill, in the selection of the optimal contract capacities. The resulting optimal contract capacity effectively reaches the minimum electricity charge of TOU rates users. A significant reduction in electricity costs is observed. The effects of expanding line construction cost and contract recovery cost on the selection of optimal contract capacities can also be estimated. The feasibility of the new algorithm is demonstrated by a numerical example, and the IPSO solution quality and computation efficiency are compared to those of other algorithms

Extension of a Kinetic-Theory Approach for Computing Chemical-Reaction Rates to Reactions with Charged Particles

Science.gov (United States)

Liechty, Derek S.; Lewis, Mark J.

2010-01-01

Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties (i.e., no macroscopic reaction rate information) are extended to include reactions involving charged particles and electronic energy levels. The proposed extensions include ionization reactions, exothermic associative ionization reactions, endothermic and exothermic charge exchange reactions, and other exchange reactions involving ionized species. The extensions are shown to agree favorably with the measured Arrhenius rates for near-equilibrium conditions.

Moving Encounters

Directory of Open Access Journals (Sweden)

Ann Deslandes

2011-04-01

Full Text Available This essay explores my experience of losing an authoritative speaking position – that is, ‘falling on my face’ in a research encounter with the Brazilian Landless Worker’s Movement (O Movimento dos Trabalhadores Rurais sem Terra, or MST.  My specific movements through this locale invoke Gayatri Chakravorty Spivak’s concept of ‘unlearning one’s privilege as a loss’; and Sara Ahmed’s theory of ‘stranger fetishism’.  In writing my brief loss, I also; of course, recover my speaking position, meaning that I can always efface the loss by re-writing it as a source of ethnographic authority.  This essay is written in two voices in order to reflect this paradox: one which describes the encounter, and one that critically ruminates upon it.  I note, for example, that the MST as a variegated conglomerate of people takes the form of particular ‘Others’ when they are represented in the scholarship and polemic of ‘first world’ activists in the so called ‘global justice movement’.  ‘Falling on my face in the street’ of these Others locates particular processes of fetishization within the global justice movement and the relationships across power and difference that are contained herein; processes that impact on the idea of a ‘global’ solidarity against systemic ‘global’ oppressions.

Customer-sales employee encounters: a dyadic perspective.

NARCIS (Netherlands)

Dolen, van W.; Lemmink, J.G.A.M.; Ruyter, de J.C.; Jong, de A.

2003-01-01

Although researchers have suggested that the performance of the salesperson during sales encounters is critical, many of the underlying mechanisms that govern the interaction between salespersons and customers are still unclear. In this research, we investigate sales encounters from a new approach

Customer-to-customer roles and impacts in service encounters

OpenAIRE

Lee, Linda

2016-01-01

This thesis investigates customer-to-customer roles and impacts in the context of service encounters. This topic is studied from two angles: customer interactions during group service encounters and customer perceptions post service encounters. The first angle is a focus on group service encounters that addresses the lack of research on customer-to-customer interactions that occur in customer-to-customer interaction-intensive contexts. These are contexts where the interactions between custome...

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

Directory of Open Access Journals (Sweden)

Jian Li

2015-12-01

Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

A Lakatosian Encounter

Science.gov (United States)

Chick, Helen

2010-01-01

There is much to be learned and pondered by reading "Proofs and Refutations," by Imre Lakatos. It highlights the importance of mathematical definitions, and how definitions evolve to capture the essence of the object they are defining. It also provides an exhilarating encounter with the ups and downs of the mathematical reasoning process, where…

Festival as embodied encounters

DEFF Research Database (Denmark)

Simonsen, Kirsten; Koefoed, Lasse Martin; Neergaard, Maja de

2017-01-01

This article is part of a project on Paradoxical Spaces: Encountering the Other in public space which explores how cultural difference is experienced, practiced and negotiated in public space. Specifically, it explores the ‘multicultural’ festival Kulturhavn taking place yearly along the harbour...... of Copenhagen. Multicultural festivals are seen as places for on-going identity negotiations, where individuals and groups define meaningful concepts of identity along with notions of exclusion. In the paper, we adopt a performative approach abandoning the distinction between bodies and space and embracing...... ideas of ‘embodiment’ and ‘rhythm’. We explore participant engagement emphasizing bodily practices as well as sensuous experiences, but also differential processes and orientalist images produced in, and through, encounters. Among the range of activities at the festival, we focus on three: food; dance...

Exposure assessment and heart rate variability monitoring in workers handling titanium dioxide particles: a pilot study

Energy Technology Data Exchange (ETDEWEB)

Ichihara, Sahoko [Mie University, Graduate School of Regional Innovation Studies (Japan); Li, Weihua [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Omura, Seiichi [Tokyo Institute of Technology (Japan); Fujitani, Yuji [National Institute for Environmental Studies (Japan); Liu, Ying; Wang, Qiangyi [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Hiraku, Yusuke [Mie University Graduate School of Medicine, Department of Environmental and Molecular Medicine (Japan); Hisanaga, Naomi [Aichi Gakusen University, Faculty of Human Science and Design (Japan); Wakai, Kenji [Nagoya University Graduate School of Medicine, Department of Preventive Medicine (Japan); Ding, Xuncheng [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Kobayashi, Takahiro, E-mail: takakoba@airies.or.jp [Association for International Research Initiatives for Environmental Studies (Japan); Ichihara, Gaku, E-mail: gak@rs.tus.ac.jp [Tokyo University of Science, Department of Occupational and Environmental Health, Faculty of Pharmaceutical Sciences (Japan)

2016-03-15

Titanium dioxide (TiO{sub 2}) particles are used for surface coating and in a variety of products such as inks, fibers, food, and cosmetics. The present study investigated possible respiratory and cardiovascular effects of TiO{sub 2} particles in workers exposed to this particle at high concentration in a factory in China. The diameter of particles collected on filters was measured by scanning electron microscopy. Real-time size-dependent particle number concentration was monitored in the nostrils of four workers using condensation particle counter and optical particle counter. Electrocardiogram was recorded using Holter monitors for the same four workers to record heart rate variability. Sixteen workers underwent assessment of the respiratory and cardiovascular systems. Mass-based individual exposure levels were also measured with personal cascade impactors. The primary particle diameter ranged from 46 to 562 nm. Analysis of covariance of the pooled data of the four workers showed that number of particles with a diameter <300 nm was associated positively with total number of N–N and negatively with total number of increase or decrease in successive RR intervals greater than 50 ms (RR50+/−) or percentage of RR 50+/− that were parameters of parasympathetic function. The total mass concentration was 9.58–30.8 mg/m{sup 3} during work, but significantly less before work (0.36 mg/m{sup 3}). The clear abnormality in respiratory function was not observed in sixteen workers who had worked for 10 months to 13 years in the factory. The study showed that exposure to particles with a diameter <300 nm might affect HRV in workers handling TiO{sub 2} particles. The results highlight the need to investigate the possible impact of exposure to nano-scaled particles on the autonomic nervous system.

Precritical increase of particle collision rates

International Nuclear Information System (INIS)

Muenchow, L.

1990-01-01

In quantum kinetics the collision integral follows from the imaginary part of the mass operator. Using this connection it is shown that the coupling of single particle motion to precritical density fluctuations causes a strong increase of the collision integral near the point of phase instability. 13 refs

Co-creation of Innovations in ICT based service encounters

DEFF Research Database (Denmark)

Sørensen, Jannick Kirk; Henten, Anders

2014-01-01

Innovations in services often emanate from service encounters (i.e. the touch points between the service producers and the customers). Two different types of service encounters are dealt with: face-to-face and ICT-based service encounters. The aim of the chapter is to examine the specific...

Dynamics of polyelectrolyte adsorption and colloidal flocculation upon mixing studied using mono-dispersed polystyrene latex particles

NARCIS (Netherlands)

Feng, Lili; Cohen Stuart, Martien; Adachi, Yasuhisa

2015-01-01

The dynamic behavior of polyelectrolytes just after their encounter with the surface of bare colloidal particles is analyzed, using the flocculation properties of mono-dispersed polystyrene latex (PSL) particles. Applying a Standardized Colloid Mixing (SCM) approach, effects of ionic strength and

Crowdsourcing for Context: Regarding Privacy in Beacon Encounters via Contextual Integrity

Directory of Open Access Journals (Sweden)

Bello-Ogunu Emmanuel

2016-07-01

Full Text Available Research shows that context is important to the privacy perceptions associated with technology. With Bluetooth Low Energy beacons, one of the latest technologies for providing proximity and indoor tracking, the current identifiers that characterize a beacon are not sufficient for ordinary users to make informed privacy decisions about the location information that could be shared. One solution would be to have standardized category and privacy labels, produced by beacon providers or an independent third-party. An alternative solution is to find an approach driven by users, for users. In this paper, we propose a novel crowdsourcing based approach to introduce elements of context in beacon encounters.We demonstrate the effectiveness of this approach through a user study, where participants use a crowd-based mobile app designed to collect beacon category and privacy information as a scavenger hunt game. Results show that our approach was effective in helping users label beacons according to the specific context of a given beacon encounter, as well as the privacy perceptions associated with it. This labeling was done with an accuracy of 92%, and with an acceptance rate of 82% of all recommended crowd labels. Lastly, we conclusively show how crowdsourcing for context can be used towards a user-centric framework for privacy management during beacon encounters.

Value creation and knowledge development in tourism experience encounters

DEFF Research Database (Denmark)

Sørensen, Flemming; Jensen, Jens Friis

2015-01-01

It has been argued that service encounters between front-line employees and users support the development of knowledge about users' needs. However, the potential for this often remains unused, not least in tourism. This article argues that if tourism service encounters are changed into ‘experience...... encounters’ by integrating them into the tourism experience to which they are related, this will create added experiential value for tourists and increase the creation of knowledge about users. This is illustrated in an innovation field experiment in a retro design boutique hotel in which service encounters...... were developed into experience encounters. The experiment illustrates the potential that experience encounters have to create knowledge and value, but also suggests some barriers that need to be overcome....

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating

DEFF Research Database (Denmark)

Koivisto, Antti J.; Jensen, Alexander C. Ø.; Kling, Kirsten I.

2017-01-01

Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO2)-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m3 test chamber while measuring concentrations of 5.6nm ...

Administrative encounters in general practice: low value or hidden value care?

Science.gov (United States)

Trevena, Lyndal J; Harrison, Christopher; Britt, Helena C

2018-02-19

To determine the frequency of general practice administrative encounters, and to determine whether they represent low value care. Secondary analysis of data from the Bettering Evaluation and Care of Health (BEACH) dataset. 1 568 100 GP-patient encounters in Australia, 2000-01 to 2015-16. An annual nationally representative random sample of about 1000 GPs, who each recorded the details of 100 consecutive encounters with patients. Proportions of general practice encounters that were potentially low value care encounters (among the patient's reasons for the encounter was at least one administrative, medication, or referral request) and potentially low value care only encounters (such reasons were the sole reason for the encounter). For 2015-16, we also examined other health care provided by GPs at these encounters. During 2015-16, 18.5% (95% CI, 17.7-19.3%) of 97 398 GP-patient encounters were potentially low value care request encounters; 7.4% (95% CI, 7.0-7.9%) were potentially low value care only encounters. Administrative work was requested at 3.8% (95% CI, 3.5-4.0%) of GP visits, 35.4% of which were for care planning and coordination, 33.5% for certification, and 31.2% for other reasons. Medication requests were made at 13.1% (95% CI, 12.4-13.7%) of encounters; other health care was provided at 57.9% of medication request encounters, counselling, advice or education at 23.4%, and pathology testing was ordered at 16.7%. Referrals were requested at 2.8% (95% CI, 1.7-3.0%) of visits, at 69.4% of which additional health care was provided. The problems managed most frequently at potentially low value care only encounters were chronic diseases. Most patients requested certificates, medications and referrals in the context of seeking help for other health needs. Additional health care, particularly for chronic diseases, was provided at most GP administrative encounters. The MBS Review should consider the hidden value of these encounters.

Awkward Encounters and Ethnography

DEFF Research Database (Denmark)

Koning, Juliette; Ooi, Can-Seng

2013-01-01

from these encounters. Un-paralyzing reflexivity means to include the awkward, the emotional, and admit the non-rational aspects of our ethnographic experiences; such inclusive reflexivity is incredibly insightful. Research limitations/implications – Inclusive reflexivity not only allows room...

Uncorrelated Encounter Model of the National Airspace System, Version 2.0

Science.gov (United States)

2013-08-19

can exist to certify avoidance systems for operational use. Evaluations typically include flight tests, operational impact studies, and simulation of...appropriate for large-scale air traffic impact studies— for example, examination of sector loading or conflict rates. The focus here includes two types of...between two IFR aircraft in oceanic airspace. The reason for this is that one cannot observe encounters of sufficient fidelity in the available data

The electrochemical reduction rate of colloidal particles of silver halides as a function of the electrolyte composition

International Nuclear Information System (INIS)

Selivanov, V.N.

1997-01-01

Influence of silver halide colloid particles concentration (AgI), electrolyte composition and signs of the electrode and colloids charges on their reduction threshold current densities has been studied. It has been discovered that reduction threshold current densities of positively charged colloid particles exceed by a factor of 3-4 the threshold densities of silver ions diffusion current. It is shown that the threshold density of colloids reduction current is limited by the rates of their electrophoretic transfer and diffusion

Disintegration rate and properties of active pharmaceutical ingredient particles as determined from the dissolution time profile of a pharmaceutical formulation: an inverse problem.

Science.gov (United States)

Horkovics-Kovats, Stefan

2014-02-01

Dissolution profile of a finished dosage form (FDF) contains hidden information regarding the disintegration of the form and the particle properties of the active pharmaceutical ingredient. Here, an extraction of this information from the dissolution profile without limitation to sink conditions is provided. In the article, mathematical relationships between the continuously measured dissolution profile of an FDF containing uniform or heterogeneous particles and its disintegration rate are developed. Further, the determinability of the disintegration kinetics and particle properties released from an FDF using the derived recurrent procedure was analyzed. On the basis of the theoretical data sets, it was demonstrated that the introduced analysis of dissolution profiles correctly identifies the disintegration rate of FDF containing multiple particle types. Furthermore, for known disintegration rates, the intrinsic lifetime of particles (time needed for total particle dissolution in infinite volume) released from the FDF and their relative amount can be determined. The extractable information from FDF dissolution time profiles can be utilized in designing of the formulation process, resulting in improved understanding of FDF properties, contributing thus to the implementation of quality by design in the FDF development. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Close stellar encounters in globular clusters

International Nuclear Information System (INIS)

Bailyn, C.D.

1989-01-01

Stellar encounters are expected to produce a variety of interesting objects in the cores of globular clusters, either through the formation of binaries by tidal capture, or direct collisions. Here, I describe several attempts to observe the products of stellar encounters. In particular, the use of color maps has demonstrated the existence of a color gradient in the core of M15, which seems to be caused by a population of faint blue objects concentrated towards the cluster center. (author)

Effects of cooling rate on particle rearrangement statistics: Rapidly cooled glasses are more ductile and less reversible.

Science.gov (United States)

Fan, Meng; Wang, Minglei; Zhang, Kai; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

2017-02-01

Amorphous solids, such as metallic, polymeric, and colloidal glasses, display complex spatiotemporal response to applied deformations. In contrast to crystalline solids, during loading, amorphous solids exhibit a smooth crossover from elastic response to plastic flow. In this study, we investigate the mechanical response of binary Lennard-Jones glasses to athermal, quasistatic pure shear as a function of the cooling rate used to prepare them. We find several key results concerning the connection between strain-induced particle rearrangements and mechanical response. We show that the energy loss per strain dU_{loss}/dγ caused by particle rearrangements for more rapidly cooled glasses is larger than that for slowly cooled glasses. We also find that the cumulative energy loss U_{loss} can be used to predict the ductility of glasses even in the putative linear regime of stress versus strain. U_{loss} increases (and the ratio of shear to bulk moduli decreases) with increasing cooling rate, indicating enhanced ductility. In addition, we characterized the degree of reversibility of particle motion during a single shear cycle. We find that irreversible particle motion occurs even in the linear regime of stress versus strain. However, slowly cooled glasses, which undergo smaller rearrangements, are more reversible during a single shear cycle than rapidly cooled glasses. Thus, we show that more ductile glasses are also less reversible.

Encounter success of free-ranging marine predator movements across a dynamic prey landscape.

Science.gov (United States)

Sims, David W; Witt, Matthew J; Richardson, Anthony J; Southall, Emily J; Metcalfe, Julian D

2006-05-22

Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of 'model' sharks. Movements of transmitter-tagged sharks monitored for 964 days (16754 km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species.

Shouting in a Desert: Dutch missionary encounters with Javanese Islam, 1850-1910 : Dutch missionary encounters with Javanese Islam, 1850-1910

NARCIS (Netherlands)

M.J. Kruithof (Maryse)

2014-01-01

markdownabstract__Abstract__ ‘‘Shouting in a desert’ Dutch missionary encounters with Javanese Islam’ concentrates on the shifts and developments in the Dutch mission discourse within the period from 1850 to 1910. It explores the Dutch missionary encounter with local communities and is conducted

Toward the Long-Term Scientific Study of Encounter Group Phenomena: I. Methodological Considerations.

Science.gov (United States)

Diamond, Michael Jay; Shapiro, Jerrold Lee

This paper proposes a model for the long-term scientific study of encounter, T-, and sensitivity groups. The authors see the need for overcoming major methodological and design inadequacies of such research. They discuss major methodological flaws in group outcome research as including: (1) lack of adequate base rate or pretraining measures; (2)…

Common Factors Among Family Medicine Residents Who Encounter Difficulty.

Science.gov (United States)

Binczyk, Natalia M; Babenko, Oksana; Schipper, Shirley; Ross, Shelley

2018-04-01

Residents in difficulty are costly to programs in both time and resources, and encountering difficulty can be emotionally harmful to residents. Approximately 10% of residents will encounter difficulty at some point in training. While there have been several studies looking at common factors among residents who encounter difficulty, some of the findings are inconsistent. The objective of this study was to determine whether there are common factors among the residents who encounter difficulty during training in a large Canadian family medicine residency program. Secondary data analysis was performed on archived resident files from a Canadian family medicine residency program. Residents who commenced an urban family medicine residency program between the years of 2006 and 2014 were included in the study. Five hundred nine family medicine residents were included in data analysis. Residents older than 30 years were 2.33 times (95% CI: 1.27-4.26) more likely to encounter difficulty than residents aged 30 years or younger. Nontransfer residents were 8.85 times (95% CI: 1.17-66.67) more likely to encounter difficulty than transfer residents. The effects of sex, training site, international medical graduate status, and rotation order on the likelihood of encountering difficulty were nonsignificant. Older and nontransfer residents may be facing unique circumstances and may benefit from additional support from the program.

A drop in the pond: the effect of rapid mass-loss on the dynamics and interaction rate of collisionless particles

Science.gov (United States)

Penoyre, Zephyr; Haiman, Zoltán

2018-01-01

In symmetric gravitating systems experiencing rapid mass-loss, particle orbits change almost instantaneously, which can lead to the development of a sharply contoured density profile, including singular caustics for collisionless systems. This framework can be used to model a variety of dynamical systems, such as accretion discs following a massive black hole merger and dwarf galaxies following violent early star formation feedback. Particle interactions in the high-density peaks seem a promising source of observable signatures of these mass-loss events (i.e. a possible EM counterpart for black hole mergers or strong gamma-ray emission from dark matter annihilation around young galaxies), because the interaction rate depends on the square of the density. We study post-mass-loss density profiles, both analytic and numerical, in idealized cases and present arguments and methods to extend to any general system. An analytic derivation is presented for particles on Keplerian orbits responding to a drop in the central mass. We argue that this case, with initially circular orbits, gives the most sharply contoured profile possible. We find that despite the presence of a set of singular caustics, the total particle interaction rate is reduced compared to the unperturbed system; this is a result of the overall expansion of the system dominating over the steep caustics. Finally, we argue that this result holds more generally, and the loss of central mass decreases the particle interaction rate in any physical system.

Service encounters as bases for innovation

DEFF Research Database (Denmark)

Sundbo, Jon; Sundbo, Donna; Henten, Anders

2015-01-01

customers with the innovating organization. Based on literature studies and pilot case studies, seven propositions are proposed and tested in a qualitative, hermeneutic way in field experiments in nine service organizations. Important new results are that encounter-based innovation requires mutual empathy...... between employees and customers, employees investing stubbornness and time can be a driver for innovation, and several layers of management can be a barrier. In the field experiments three new factors for encounter-based innovation were found: translation, multitasking, and hyper-professionalism. The two...

Granular shear flows of flexible rod-like particles

Science.gov (United States)

Guo, Y.; Curtis, J.; Wassgren, C.; Ketterhagen, W.; Hancock, B.

2013-06-01

Flexible particles are widely encountered in nature, e.g., stalks of plants, fiberglass particles, and ceramic nanofibers. Early studies indicated that the deformability of particles has a significant impact on the properties of granular materials and fiber suspensions. In this study, shear flows of flexible particles are simulated using the Discrete Element Method (DEM) to explore the effect of particle flexibility on the flow behavior and constitutive laws. A flexible particle is formed by connecting a number of constituent spheres in a straight line using elastic bonds. The forces/moments due to the normal, tangential, bending, and torsional deformation of a bond resist the relative movement between two bonded constituent spheres. The bond stiffness determines how difficult it is to make a particle deform, and the bond damping accounts for the energy dissipation in the particle vibration process. The simulation results show that elastically bonded particles have smaller coefficients of restitution compared to rigidly connected particles, due to the fact that kinetic energy is partially converted to potential energy in a contact between flexible particles. The coefficient of restitution decreases as the bond stiffness decreases and the bond damping coefficient increases. As a result, smaller stresses are obtained for granular flows of the flexible particles with smaller bond stiffness and larger bond damping coefficient.

Composition and properties of atmospheric particles in the eastern Atlantic and impacts on gas phase uptake rates

Directory of Open Access Journals (Sweden)

G. McFiggans

2009-12-01

humidity using HTDMA data. Heterogeneous uptake rates of hypoiodous acid (HOI were also predicted and the nss accumulation mode was found to be the most significant part of the size distribution, which could act as an inert sink for this species. The predicted uptake rates were enhanced by around a factor of 2 during the African influence period due to the addition of both coarse and fine particles.

The hygroscopicity of the nss fraction was modelled using the Aerosol Diameter Dependent Equilibrium Model (ADDEM using the measured composition and results compared with the HTDMA data. This was the first time such a reconciliation study with this model has been performed with marine data and good agreement was reached within the resolution of the instruments. The effect of hygroscopic growth on HOI uptake was also modelled and ambient uptake rates were found to be approximately doubled compared to equivalent dry particles.

Brain systems underlying encounter expectancy bias in spider phobia.

Science.gov (United States)

Aue, Tatjana; Hoeppli, Marie-Eve; Piguet, Camille; Hofstetter, Christoph; Rieger, Sebastian W; Vuilleumier, Patrik

2015-06-01

Spider-phobic individuals are characterized by exaggerated expectancies to be faced with spiders (so-called encounter expectancy bias). Whereas phobic responses have been linked to brain systems mediating fear, little is known about how the recruitment of these systems relates to exaggerated expectancies of threat. We used fMRI to examine spider-phobic and control participants while they imagined visiting different locations in a forest after having received background information about the likelihood of encountering different animals (spiders, snakes, and birds) at these locations. Critically, imagined encounter expectancies modulated brain responses differently in phobics as compared with controls. Phobics displayed stronger negative modulation of activity in the lateral prefrontal cortex, precuneus, and visual cortex by encounter expectancies for spiders, relative to snakes or birds (within-participants analysis); these effects were not seen in controls. Between-participants correlation analyses within the phobic group further corroborated the hypothesis that these phobia-specific modulations may underlie irrationality in encounter expectancies (deviations of encounter expectancies from objective background information) in spider phobia; the greater the negative modulation a phobic participant displayed in the lateral prefrontal cortex, precuneus, and visual cortex, the stronger was her bias in encounter expectancies for spiders. Interestingly, irrationality in expectancies reflected in frontal areas relied on right rather than left hemispheric deactivations. Our data accord with the idea that expectancy biases in spider phobia may reflect deficiencies in cognitive control and contextual integration that are mediated by right frontal and parietal areas.

Aerosol material release rates from zircaloy-4 at temperatures from 2000 to 22000C

International Nuclear Information System (INIS)

Mulpuru, S.R.; Wren, D.J.; Rondeau, R.K.

1987-01-01

During some postulated severe accidents involving loss of coolant and loss of emergency coolant injection, the temperatures in a CANDU reactor fuel channel become high enough to cause failure and melting of the Zircaloy fuel cladding. At such high temperatures, vapors of fission products and structural (fuel and cladding) materials will be released into the coolant steam and hydrogen mixture. These vapors will condense as cooler conditions are encountered downstream. The vapors from structural materials are relatively involatile; therefore, they will condense readily into aerosol particles. These particles, in turn, will provide sites for the condensation of the more volatile fission products. The aerosol transport of fission products in the primary heat transport system (PHTS) will thus be influenced by the structural material release rates. As part of an ongoing program to develop predictive tools for aerosol and associated fission product transport through the PHTS, experiments have been conducted to measure the vapor mass release rates of the alloying elements from Zircaloy-4 at high temperatures. The paper presents the results and analysis of these experiments

Theoretical analysis of the distribution of isolated particles in totally asymmetric exclusion processes: Application to mRNA translation rate estimation

Science.gov (United States)

Dao Duc, Khanh; Saleem, Zain H.; Song, Yun S.

2018-01-01

The Totally Asymmetric Exclusion Process (TASEP) is a classical stochastic model for describing the transport of interacting particles, such as ribosomes moving along the messenger ribonucleic acid (mRNA) during translation. Although this model has been widely studied in the past, the extent of collision between particles and the average distance between a particle to its nearest neighbor have not been quantified explicitly. We provide here a theoretical analysis of such quantities via the distribution of isolated particles. In the classical form of the model in which each particle occupies only a single site, we obtain an exact analytic solution using the matrix ansatz. We then employ a refined mean-field approach to extend the analysis to a generalized TASEP with particles of an arbitrary size. Our theoretical study has direct applications in mRNA translation and the interpretation of experimental ribosome profiling data. In particular, our analysis of data from Saccharomyces cerevisiae suggests a potential bias against the detection of nearby ribosomes with a gap distance of less than approximately three codons, which leads to some ambiguity in estimating the initiation rate and protein production flux for a substantial fraction of genes. Despite such ambiguity, however, we demonstrate theoretically that the interference rate associated with collisions can be robustly estimated and show that approximately 1% of the translating ribosomes get obstructed.

Service quality, trust, and patient satisfaction in interpersonal-based medical service encounters.

Science.gov (United States)

Chang, Ching-Sheng; Chen, Su-Yueh; Lan, Yi-Ting

2013-01-16

Interaction between service provider and customer is the primary core of service businesses of different natures, and the influence of trust on service quality and customer satisfaction could not be ignored in interpersonal-based service encounters. However, lack of existing literature on the correlation between service quality, patient trust, and satisfaction from the prospect of interpersonal-based medical service encounters has created a research gap in previous studies. Therefore, this study attempts to bridge such a gap with an evidence-based practice study. We adopted a cross-sectional design using a questionnaire survey of outpatients in seven medical centers of Taiwan. Three hundred and fifty copies of questionnaire were distributed, and 285 valid copies were retrieved, with a valid response rate of 81.43%. The SPSS 14.0 and AMOS 14.0 (structural equation modeling) statistical software packages were used for analysis. Structural equation modeling clarifies the extent of relationships between variables as well as the chain of cause and effect. Restated, SEM results do not merely show empirical relationships between variables when defining the practical situation. For this reason, SEM was used to test the hypotheses. Perception of interpersonal-based medical service encounters positively influences service quality and patient satisfaction. Perception of service quality among patients positively influences their trust. Perception of trust among patients positively influences their satisfaction. According to the findings, as interpersonal-based medical service encounters will positively influence service quality and patient satisfaction, and the differences for patients' perceptions of the professional skill and communication attitude of personnel in interpersonal-based medical service encounters will influence patients' overall satisfaction in two ways: (A) interpersonal-based medical service encounter directly affects patient satisfaction, which represents a

Service quality, trust, and patient satisfaction in interpersonal-based medical service encounters

Science.gov (United States)

2013-01-01

Background Interaction between service provider and customer is the primary core of service businesses of different natures, and the influence of trust on service quality and customer satisfaction could not be ignored in interpersonal-based service encounters. However, lack of existing literature on the correlation between service quality, patient trust, and satisfaction from the prospect of interpersonal-based medical service encounters has created a research gap in previous studies. Therefore, this study attempts to bridge such a gap with an evidence-based practice study. Methods We adopted a cross-sectional design using a questionnaire survey of outpatients in seven medical centers of Taiwan. Three hundred and fifty copies of questionnaire were distributed, and 285 valid copies were retrieved, with a valid response rate of 81.43%. The SPSS 14.0 and AMOS 14.0 (structural equation modeling) statistical software packages were used for analysis. Structural equation modeling clarifies the extent of relationships between variables as well as the chain of cause and effect. Restated, SEM results do not merely show empirical relationships between variables when defining the practical situation. For this reason, SEM was used to test the hypotheses. Results Perception of interpersonal-based medical service encounters positively influences service quality and patient satisfaction. Perception of service quality among patients positively influences their trust. Perception of trust among patients positively influences their satisfaction. Conclusions According to the findings, as interpersonal-based medical service encounters will positively influence service quality and patient satisfaction, and the differences for patients’ perceptions of the professional skill and communication attitude of personnel in interpersonal-based medical service encounters will influence patients’ overall satisfaction in two ways: (A) interpersonal-based medical service encounter directly

Service quality, trust, and patient satisfaction in interpersonal-based medical service encounters

Directory of Open Access Journals (Sweden)

Chang Ching-Sheng

2013-01-01

Full Text Available Abstract Background Interaction between service provider and customer is the primary core of service businesses of different natures, and the influence of trust on service quality and customer satisfaction could not be ignored in interpersonal-based service encounters. However, lack of existing literature on the correlation between service quality, patient trust, and satisfaction from the prospect of interpersonal-based medical service encounters has created a research gap in previous studies. Therefore, this study attempts to bridge such a gap with an evidence-based practice study. Methods We adopted a cross-sectional design using a questionnaire survey of outpatients in seven medical centers of Taiwan. Three hundred and fifty copies of questionnaire were distributed, and 285 valid copies were retrieved, with a valid response rate of 81.43%. The SPSS 14.0 and AMOS 14.0 (structural equation modeling statistical software packages were used for analysis. Structural equation modeling clarifies the extent of relationships between variables as well as the chain of cause and effect. Restated, SEM results do not merely show empirical relationships between variables when defining the practical situation. For this reason, SEM was used to test the hypotheses. Results Perception of interpersonal-based medical service encounters positively influences service quality and patient satisfaction. Perception of service quality among patients positively influences their trust. Perception of trust among patients positively influences their satisfaction. Conclusions According to the findings, as interpersonal-based medical service encounters will positively influence service quality and patient satisfaction, and the differences for patients’ perceptions of the professional skill and communication attitude of personnel in interpersonal-based medical service encounters will influence patients’ overall satisfaction in two ways: (A interpersonal-based medical

Strange culinary encounters:

DEFF Research Database (Denmark)

Leer, Jonatan; Kjær, Katrine Meldgaard

2015-01-01

In this article, we examine the ways in which the encountering of 'other' food cultures is played out in the two travelogue cooking shows Gordon's Great Escape and Jamie's Italian Escape. We investigate how the two protagonist chefs Jamie Oliver and Gordon Ramsay imagine, meet and evaluate the ‘o...... approach to meeting the other (culinary culture), ultimately, their respective culinary adventures work to re-affirm a social hierarchy in their favor....

Neural Correlates of Racial Ingroup Bias in Observing Computer-Animated Social Encounters

Directory of Open Access Journals (Sweden)

Yuta Katsumi

2018-01-01

Full Text Available Despite evidence for the role of group membership in the neural correlates of social cognition, the mechanisms associated with processing non-verbal behaviors displayed by racially ingroup vs. outgroup members remain unclear. Here, 20 Caucasian participants underwent fMRI recording while observing social encounters with ingroup and outgroup characters displaying dynamic and static non-verbal behaviors. Dynamic behaviors included approach and avoidance behaviors, preceded or not by a handshake; both dynamic and static behaviors were followed by participants’ ratings. Behaviorally, participants showed bias toward their ingroup members, demonstrated by faster/slower reaction times for evaluating ingroup static/approach behaviors, respectively. At the neural level, despite overall similar responses in the action observation network to ingroup and outgroup encounters, the medial prefrontal cortex showed dissociable activation, possibly reflecting spontaneous processing of ingroup static behaviors and positive evaluations of ingroup approach behaviors. The anterior cingulate and superior frontal cortices also showed sensitivity to race, reflected in coordinated and reduced activation for observing ingroup static behaviors. Finally, the posterior superior temporal sulcus showed uniquely increased activity to observing ingroup handshakes. These findings shed light on the mechanisms of racial ingroup bias in observing social encounters, and have implications for understanding factors related to successful interactions with individuals from diverse backgrounds.

Effect of HZE particles and space hadrons on bacteriophages

International Nuclear Information System (INIS)

Iurov, S.S.; Akoev, I.G.; Leonteva, G.A.

1983-01-01

The effects of particle radiation of the type encountered in space flight on bacteriophages are investigated. Survival and mutagenesis were followed in dry film cultures or liquid suspensions of T4Br(+) bacteriophage exposed to high-energy (HZE) particles during orbital flight, to alpha particles and accelerator-generated hardrons in the laboratory, and to high-energy cosmic rays at mountain altitudes. The HZE particles and high-energy hadrons are found to have a greater relative biological efficiency than standard gamma radiation, while exhibiting a highly inhomogeneous spatial structure in the observed biological and genetic effects. In addition, the genetic lesions observed are specific to the type of radiation exposure, consisting primarily of deletions and multiple lesions of low revertability, with mode of action depending on the linear energy transfer. 18 references

Guest-Host Encounters in Diaspora-Heritage Tourism: The Taglit-Birthright Israel Mifgash (Encounter)

Science.gov (United States)

Sasson, Theodore; Mittelberg, David; Hecht, Shahar; Saxe, Leonard

2011-01-01

More than 300,000 diaspora Jewish young adults and tens of thousands of their Israeli peers have participated in structured, cross-cultural encounters--"mifgashim"--in the context of an experiential education program known as Taglit-Birthright Israel. Drawing on field observations, interviews, and surveys, the formal and informal…

The Impact of Value-Orientations on Cross-cultural Encounters and ...

African Journals Online (AJOL)

encounters and mediation in the Tanzanian educational system. The purpose of the article is to give an emic perspective on value-orientations in crosscultural encounters and mediation situations in the educational system, to improve understanding of the conflictive aspects of these encounters. To achieve this purpose, the ...

Single-particle characterization of urban aerosol particles collected in three Korean cites using low-Z electron probe X-ray microanalysis.

Science.gov (United States)

Ro, Chul-Un; Kim, HyeKyeong; Oh, Keun-Young; Yea, Sun Kyung; Lee, Chong Bum; Jang, Meongdo; Van Grieken, René

2002-11-15

A recently developed single-particle analytical technique, called low-Z electron probe X-ray microanalysis (low-Z EPMA), was applied to characterize urban aerosol particles collected in three cities of Korea (Seoul, CheongJu, and ChunCheon) on single days in the winter of 1999. In this study, it is clearly demonstrated that the low-Z EPMA technique can provide detailed and quantitative information on the chemical composition of particles in the urban atmosphere. The collected aerosol particles were analyzed and classified on the basis of their chemical species. Various types of particles were identified, such as soil-derived, carbonaceous, marine-originated, and anthropogenic particles. In the sample collected in Seoul, carbonaceous, aluminosilicates, silicon dioxide, and calcium carbonate aerosol particles were abundantly encountered. In the CheongJu and ChunCheon samples, carbonaceous, aluminosilicates, reacted sea salts, and ammonium sulfate aerosol particles were often seen. However, in the CheongJu sample, ammonium sulfate particles were the most abundant in the fine fraction. Also, calcium sulfate and nitrate particles were significantly observed. In the ChunCheon sample, organic particles were the most abundant in the fine fraction. Also, sodium nitrate particles were seen at high levels. The ChunCheon sample seemed to be strongly influenced by sea-salt aerosols originating from the Yellow Sea, which is located about 115 km away from the city.

A photo-tunable membrane based on inter-particle crosslinking for decreasing diffusion rates

KAUST Repository

Li, Song

2015-01-01

Functional polymeric membranes are widely used to adjust and control the diffusion of molecules. Herein, photosensitive poly(hydroxycinnamic acid) (PHCA) microspheres, which were fabricated by an emulsification solvent-evaporation method, were embedded into an ethyl cellulose matrix to fabricate composite membranes with a photo-tunable property. The photoreaction of PHCA is based on the [2 + 2] cycloaddition of cinnamic moieties upon irradiation with 365 nm light. Intra-particle crosslinking in PHCA microspheres was confirmed in the solution phase, while inter-particle crosslinking between adjacent PHCA microspheres dominated the solid membrane phase. The inter-particle crosslinking turned down the permeability of the composite membranes by 74%. To prove the applicability of the designed system, the composite membrane was coated on a model drug reservoir tablet. Upon irradiating the tablet with UV light, the original permeability decreased by 57%, and consequently the diffusion rate of the cargo (Rhodamine B) from the tablet slowed down. Most importantly, the tablet showed sustained release for over 10 days. This controllability can be further tuned by adjusting the membrane thickness. Composite membranes showed excellent processing reproducibility together with consistent mechanical properties. These results demonstrate that the incorporation of photosensitive PHCA microspheres in polymeric membranes provides a promising photo-tunable material for different applications including coating and separation. This journal is © The Royal Society of Chemistry 2015.

Influence of shielding gas on fume formation rate and particle size distribution for optimised GMAW

International Nuclear Information System (INIS)

Carpenter, K.R.; Monaghan, B.J.; Nicholson, A.; Cuiuri, D.; Norrish, J.

2010-01-01

The influence of shielding gas on fume formation rate (FFR) and particle size distribution has been investigated by using a technique developed for automatic control of the welding voltage in gas metal arc welding (GMAW). The results for automatic control are compared with the use of a fixed voltage. Significant reductions in FFR and a general decrease in average particle size were observed using the automatic control technique. This reduction in FFR was attributed to improved metal transfer stability, via a reduction in the occurrence of repelled globular transfer, by promoting the 'drop-spray' transfer condition, together with a reduction in the arc length. FFR and particle size were strongly related to the C O2 content of the shielding gas, where FFR increased as percent C 02 increased, due mainly to the dominant influence of C O2 on weld transfer and arc characteristics. The results indicate that FFR for GMAW in the spray regime should be determined by using optimised welding conditions for each shielding gas composition.

Modeling of particle agglomeration in nanofluids

International Nuclear Information System (INIS)

Krishna, K. Hari; Neti, S.; Oztekin, A.; Mohapatra, S.

2015-01-01

Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed

Emotions in relation to healthcare encounters affecting self-esteem.

Science.gov (United States)

Räty, Lena; Gustafsson, Barbro

2006-02-01

This study identifies emotions in patients with epilepsy as a result of confirming and disconfirming healthcare experiences. A discussion of emotions as a motive for patients' goal-directed actions was a further aim of this study. The critical incident method was used for data collection. Emotions occurring in confirming and disconfirming healthcare encounters were analyzed using the Belief-Desire Theory of Emotions and were categorized as basic, complex, or self-evaluating. Confirming encounters aroused emotions like hope, a feeling of security, joy, relief, and pride, while disconfirming encounters aroused emotions like despair, fear, unrest, resignation, shame, and guilt. The emotions identified in the healthcare encounters were recognized as motives for action. An emotion such as a feeling of security aroused a desire in the patients to strengthen their positive self and motivated them to have a constructive and sympathetic attitude toward the healthcare experience. An emotion such as anger caused patients to strive to maintain their self-respect either by avoiding difficult situations and ignoring the problem (patients with a low self-esteem) or by trying to re-create a positive self-image (patients with a high self-esteem). Healthcare encounters between patient and caregiver considerably affect the patient's emotional status and thereby his or her well-being. The importance of establishing healthcare encounters that evoke positive emotions that strengthen patients' resources must be addressed in future nursing care.

An Improvement to DCPT: The Particle Transfer Probability as a Function of Particle's Age

International Nuclear Information System (INIS)

L. Pan; G. S. Bodvarsson

2001-01-01

Multi-scale features of transport processes in fractured porous media make numerical modeling a difficult task of both conceptualization and computation. Dual-continuum particle tracker (DCPT) is an attractive method for modeling large-scale problems typically encountered in the field, such as those in unsaturated zone (UZ) of Yucca Mountain, Nevada. The major advantage is its capability to capture the major features of flow and transport in fractured porous rock (i-e., a fast fracture sub-system combined with a slow matrix sub-system) with reasonable computational resources. However, like other conventional dual-continuum approach-based numerical methods, DCPT (v1.0) is often criticized for failing to capture the transient features of the diffusion depth into the matrix. It may overestimate the transport of tracers through the fractures, especially for the cases with large fracture spacing, and predict artificial early breakthroughs. The objective of this study is to develop a new theory for calculating the particle transfer probability to captures the transient features of the diffusion depth into the matrix within the framework of the dual-continuum random walk particle method (RWPM)

Gravitational wave bursts from Primordial Black Hole hyperbolic encounters

CERN Document Server

Garcia-Bellido, Juan

2017-01-01

We propose that Gravitational Wave (GW) bursts with millisecond durations can be explained by the GW emission from the hyperbolic encounters of Primordial Black Holes in dense clusters. These bursts are single events, with the bulk of the released energy happening during the closest approach, and emitted in frequencies within the AdvLIGO sensitivity range. We provide expressions for the shape of the GW emission in terms of the peak frequency and amplitude, and estimate the rates of these events for a variety of mass and velocity configurations. We study the regions of parameter space that will allow detection by both AdvLIGO and, in the future, LISA. We find for realistic configurations, with total mass M∼60 M⊙, relative velocities v∼0.01c, and impact parameters b∼10−3 AU, for AdvLIGO an expected event rate is O(10) events/yr/Gpc^3 with millisecond durations. For LISA, the typical duration is in the range of minutes to hours and the event-rate is O(10^3) events/yr/Gpc^3 for both 10^3 M⊙ IMBH and 1...

Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

Science.gov (United States)

Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

2014-01-01

The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can

Effect of indirect non-thermal plasma on particle size distribution and composition of diesel engine particles

Science.gov (United States)

Linbo, GU; Yixi, CAI; Yunxi, SHI; Jing, WANG; Xiaoyu, PU; Jing, TIAN; Runlin, FAN

2017-11-01

To explore the effect of the gas source flow rate on the actual diesel exhaust particulate matter (PM), a test bench for diesel engine exhaust purification was constructed, using indirect non-thermal plasma technology. The effects of different gas source flow rates on the quantity concentration, composition, and apparent activation energy of PM were investigated, using an engine exhaust particle sizer and a thermo-gravimetric analyzer. The results show that when the gas source flow rate was large, not only the maximum peak quantity concentrations of particles had a large drop, but also the peak quantity concentrations shifted to smaller particle sizes from 100 nm to 80 nm. When the gas source flow rate was 10 L min-1, the total quantity concentration greatly decreased where the removal rate of particles was 79.2%, and the variation of the different mode particle proportion was obvious. Non-thermal plasma (NTP) improved the oxidation ability of volatile matter as well as that of solid carbon. However, the NTP gas source rate had little effects on oxidation activity of volatile matter, while it strongly influenced the oxidation activity of solid carbon. Considering the quantity concentration and oxidation activity of particles, a gas source flow rate of 10 L min-1 was more appropriate for the purification of particles.

Live Aircraft Encounter Visualization at FutureFlight Central

Science.gov (United States)

Murphy, James R.; Chinn, Fay; Monheim, Spencer; Otto, Neil; Kato, Kenji; Archdeacon, John

2018-01-01

Researchers at the National Aeronautics and Space Administration (NASA) have developed an aircraft data streaming capability that can be used to visualize live aircraft in near real-time. During a joint Federal Aviation Administration (FAA)/NASA Airborne Collision Avoidance System flight series, test sorties between unmanned aircraft and manned intruder aircraft were shown in real-time at NASA Ames' FutureFlight Central tower facility as a virtual representation of the encounter. This capability leveraged existing live surveillance, video, and audio data streams distributed through a Live, Virtual, Constructive test environment, then depicted the encounter from the point of view of any aircraft in the system showing the proximity of the other aircraft. For the demonstration, position report data were sent to the ground from on-board sensors on the unmanned aircraft. The point of view can be change dynamically, allowing encounters from all angles to be observed. Visualizing the encounters in real-time provides a safe and effective method for observation of live flight testing and a strong alternative to travel to the remote test range.

An experimental study of particle-bubble interaction and attachment in flotation

KAUST Repository

Sanchez Yanez, Aaron

2017-05-01

The particle-bubble interaction is found in industrial applications with the purpose of selective separation of materials especially in the mining industry. The separation is achieved with the use of bubbles that collect particles depending on their hydrophobicity. There are few experimental studies involving a single interaction between a bubble and a particle. The purpose of this work is to understand this interaction by the study of a single bubble interacting with a single particle. Experiments were conducted using ultra-pure water, glass particles and air bubbles. Single interactions of particles with bubbles were observed using two high speed cameras. The cameras were placed perpendicular to each other allowing to reconstruct the three-dimensional position of the particle, the bubble and the particle-bubble aggregate. A single size of particle was used varying the size for the bubbles. It was found that the attachment of a particle to a bubble depends on its degree of hydrophobicity and on the relative position of the particle and the bubble before they encounter.

Binary encounter electron production in ion-atom collisions

International Nuclear Information System (INIS)

Grabbe, S.; Bhalla, C.P.; Shingal, R.

1993-01-01

The binary encounter electrons are produced by hard collisions between the target electrons and the energetic projectiles. Richard et al. found the measured double differential cross section for BEe production at zero degree laboratory scattering angle, in collisions of F q+ with H 2 and He targets, to increase as the charge state of the projectile was decreased. The binary encounter electron production has recently been a subject of detailed investigations. We have calculated the differential elastic scattering cross sections of electrons from several ions incorporating the exchange contribution of the continuum and the bound orbitals in addition to the static potential. The double differential binary encounter electron production cross sections are presented using the impulse approximation

First-Year Principal Encounters Homophobia

Science.gov (United States)

Retelle, Ellen

2011-01-01

A 1st-year principal encounters homonegativity and an ethical dilemma when she attempts to terminate a teacher because of the teacher's inadequate and ineffective teaching. The teacher responds by threatening to "out" Ms. L. to the parents.

Bottom concentrations Determination of particle material in suspension in Medellin City

International Nuclear Information System (INIS)

Echeverri Londono, Carlos Alberto

2000-01-01

The aim of this work is at achieving a better understanding of background concentrations of particle materials in suspension (pst) in Medellin. This will allow certain actions and programs for watching and controlling air pollution in this city. Metals analyzed in particle material were: calcium, chromium, copper, iron, magnesium, nickel and lead. Chromium and nickel were not detected in any station and lead was detected in one station only. It is observed that all metals have a large dispersion, excepting total iron in La America and magnesium in point 2 at Belencito, which demonstrates the high temporal variability of these metals in these places. also It is observed that metals do not have a homogenous variation in their breathable fraction (encountered in pm-10) in relation to the total metals (encountered in PST) which is indication of the different sources contribution to the metals concentration and, in general, of PST and PM - 10

Anaerobic co-digestion of food waste and dairy manure: effects of food waste particle size and organic loading rate.

Science.gov (United States)

Agyeman, Fred O; Tao, Wendong

2014-01-15

This study was to comprehensively evaluate the effects of food waste particle size on co-digestion of food waste and dairy manure at organic loading rates increased stepwise from 0.67 to 3 g/L/d of volatile solids (VS). Three anaerobic digesters were fed semi-continuously with equal VS amounts of food waste and dairy manure. Food waste was ground to 2.5 mm (fine), 4 mm (medium), and 8 mm (coarse) for the three digesters, respectively. Methane production rate and specific methane yield were significantly higher in the digester with fine food waste. Digestate dewaterability was improved significantly by reducing food waste particle size. Specific methane yield was highest at the organic loading rate of 2g VS/L/d, being 0.63, 0.56, and 0.47 L CH4/g VS with fine, medium, and coarse food waste, respectively. Methane production rate was highest (1.40-1.53 L CH4/L/d) at the organic loading rate of 3 g VS/L/d. The energy used to grind food waste was minor compared with the heating value of the methane produced. Copyright © 2013 Elsevier Ltd. All rights reserved.

Beauty is distractive: particle production during multifield inflation

Energy Technology Data Exchange (ETDEWEB)

Battefeld, Diana; Battefeld, Thorsten [Institute for Astrophysics, University of Göttingen, Friedrich Hund Platz 1, D-37077 Göttingen (Germany); Byrnes, Christian [Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld (Germany); Langlois, David, E-mail: dbattefe@astro.physik.uni-goettingen.de, E-mail: tbattefe@astro.physik.uni-goettingen.de, E-mail: byrnes@physik.uni-bielefeld.de, E-mail: langlois@apc.univ-paris7.fr [APC (CNRS-Université Paris 7), 10, rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France)

2011-08-01

We consider a two-dimensional model of inflation, where the inflationary trajectory is ''deformed'' by a grazing encounter with an Extra Species/Symmetry Point (ESP) after the observable cosmological scales have left the Hubble radius. The encounter entails a sudden production of particles, whose backreaction causes a bending of the trajectory and a temporary decrease in speed, both of which are sensitive to initial conditions. This ''modulated'' effect leads to an additional contribution to the curvature perturbation, which can be dominant if the encounter is close. We compute associated non-Gaussianities, the bispectrum and its scale dependence as well as the trispectrum, which are potentially detectable in many cases. In addition, we consider a direct modulation of the coupling to the light field at the ESP via a modulaton field, a mixed scenario whereby the modulaton is identified with a second inflaton, and an extended Extra Species Locus (ESL); all of these scenarios lead to similar additional contributions to observables. We conclude that inflaton interactions throughout inflation are strongly constrained if primordial non-Gaussianities remain unobserved in current experiments such as PLANCK. If they are observed, an ESP encounter leaves additional signatures on smaller scales which may be used to identify the model.

Humor During Clinical Practice: Analysis of Recorded Clinical Encounters.

Science.gov (United States)

Phillips, Kari A; Singh Ospina, Naykky; Rodriguez-Gutierrez, Rene; Castaneda-Guarderas, Ana; Gionfriddo, Michael R; Branda, Megan; Montori, Victor

2018-01-01

Little is known about humor's use in clinical encounters, despite its many potential benefits. We aimed to describe humor during clinical encounters. We analyzed 112 recorded clinical encounters. Two reviewers working independently identified instances of humor, as well as information surrounding the logistics of its use. Of the 112 encounters, 66 (59%) contained 131 instances of humor. Humor was similarly frequent in primary care (36/61, 59%) and in specialty care (30/51, 59%), was more common in gender-concordant interactions (43/63, 68%), and was most common during counseling (81/112, 62%). Patients and clinicians introduced humor similarly (63 vs 66 instances). Typically, humor was about the patient's medical condition (40/131, 31%). Humor is used commonly during counseling to discuss the patient's medical condition and to relate to general life events bringing warmth to the medical encounter. The timing and topic of humor and its use by all parties suggests humor plays a role in the social connection between patients and physicians and allows easier discussion of difficult topics. Further research is necessary to establish its impact on clinicians, patients, and outcomes. © Copyright 2018 by the American Board of Family Medicine.

Personal Albums and Cultural Encounters

DEFF Research Database (Denmark)

Marselis, Randi Lorenz

2018-01-01

as discussions of representational ethics in relation to anthropological and colonial photography, this article examines the exhibition The Photo Albums at the Dutch National Maritime Museum. Typically, the photo collections of maritime museums include many photographs that represent cultural encounters...

Service Encounter Related Process Quality, Patient Satisfaction, and Behavioral Intention

Directory of Open Access Journals (Sweden)

Nandakumar Mekoth

2011-12-01

Full Text Available This study identifies some of the critical service encounters thatthe outpatients undergo in a health care facility and investigateswhether the service encounter related process quality as perceivedby the patients leads to patient satisfaction, repeat visit, and recommendationintentions. Personal visits, observations, and enquiriesat the outpatient center have been conducted to identifythe various service encounters that outpatients undergo in thehospital. Exit interviews of the outpatients have been conductedto identify service encounter related process quality variableswhich determine patient satisfaction and behavioral intentions.A preliminary scale to measure service encounter related processquality was developed and its factor structure and internal consistencyreliability were established. The study reveals that boththe physician quality and laboratory quality have been found tobe significantly related to patient satisfaction. However, quite interestingly,courtesy shown by the registration or outpatient staff,perceived length of waiting time, or even the salient aspects of theservicescape, did not influence patient satisfaction.

Particle melting and particle/plasma interactions in DC and RF plasmas: a modeling study. (Volumes I and II)

International Nuclear Information System (INIS)

Wei, D.Y.C.

1987-01-01

Integral process models were developed to predict particle melting in both DC and RF plasmas. Specifically, a numerical model has been developed to predict the temperature history of particles injected in a low pressure DC plasma jet. The temperature and velocity fields of the plasma jet are predicted as a free jet by solving the parabolized Navier-Stokes equations using a spatial marching scheme. Correction factors were introduced to take into account non continuum effects encountered in the low pressure environment. The plasma jet profiles as well as the particle/plasma interactions under different jet pressure ratios (from underexpanded to overexpanded) were investigated. The flow and temperature fields in the RF plasma torch are calculated using the axisymmetric Navier-Stokes equations based on the primitive variables, along with pseudo two-dimensional electromagnetic field equations. Particle trajectories and heat transfer characteristics in both DC and RF plasmas are calculated using predicted plasma jet profiles. Particle melting efficiencies in both DC and RF plasmas are evaluated and compared using model alloy systems. Based on the theoretical considerations, an alternative route of plasma spraying process (hybrid plasma spraying process) is proposed. An evaluation of particle melting in hybrid plasma jets had indicated that further improvement in deposit properties could be made

A broad-application microchannel-plate detector system for advanced particle or photon detection tasks large area imaging, precise multi-hit timing information and high detection rate

CERN Document Server

Jagutzki, O; Mergel, V; Schmidt-Böcking, H; Spielberger, L; Spillmann, U; Ullmann-Pfleger, K

2002-01-01

New applications for single particle and photon detection in many fields require both large area imaging performance and precise time information on each detected particle. Moreover, a very high data acquisition rate is desirable for most applications and eventually the detection and imaging of more than one particle arriving within a microsecond is required. Commercial CCD systems lack the timing information whereas other electronic microchannel plate (MCP) read-out schemes usually suffer from a low acquisition rate and complicated and sometimes costly read-out electronics. We have designed and tested a complete imaging system consisting of an MCP position readout with helical wire delay-lines, single-unit amplifier box and PC-controlled time-to-digital converter (TDC) readout. The system is very flexible and can detect and analyse position and timing information at single particle rates beyond 1 MHz. Alternatively, multi-hit events can be collected and analysed at about 20 kHz rate. We discuss the advantage...

Nuclear thermodynamics below particle threshold

International Nuclear Information System (INIS)

Schiller, A.; Agvaanluvsan, U.; Algin, E.; Bagheri, A.; Chankova, R.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Voinov, A.

2005-01-01

From a starting point of experimentally measured nuclear level densities, we discuss thermodynamical properties of nuclei below the particle emission threshold. Since nuclei are essentially mesoscopic systems, a straightforward generalization of macroscopic ensemble theory often yields unphysical results. A careful critique of traditional thermodynamical concepts reveals problems commonly encountered in mesoscopic systems. One of which is the fact that microcanonical and canonical ensemble theory yield different results, another concerns the introduction of temperature for small, closed systems. Finally, the concept of phase transitions is investigated for mesoscopic systems

Identification and quantification of particle growth channels during new particle formation

Directory of Open Access Journals (Sweden)

M. R. Pennington

2013-10-01

Full Text Available Atmospheric new particle formation (NPF is a key source of ambient ultrafine particles that may contribute substantially to the global production of cloud condensation nuclei (CCN. While NPF is driven by atmospheric nucleation, its impact on CCN concentration depends strongly on atmospheric growth mechanisms since the growth rate must exceed the loss rate due to scavenging in order for the particles to reach the CCN size range. In this work, chemical composition measurements of 20 nm diameter particles during NPF in Hyytiälä, Finland, in March–April 2011 permit identification and quantitative assessment of important growth channels. In this work we show the following: (A sulfuric acid, a key species associated with atmospheric nucleation, accounts for less than half of particle mass growth during this time period; (B the sulfate content of a growing particle during NPF is quantitatively explained by condensation of gas-phase sulfuric acid molecules (i.e., sulfuric acid uptake is collision-limited; (C sulfuric acid condensation substantially impacts the chemical composition of preexisting nanoparticles before new particles have grown to a size sufficient to be measured; (D ammonium and sulfate concentrations are highly correlated, indicating that ammonia uptake is driven by sulfuric acid uptake; (E sulfate neutralization by ammonium does not reach the predicted thermodynamic end point, suggesting that a barrier exists for ammonia uptake; (F carbonaceous matter accounts for more than half of the particle mass growth, and its oxygen-to-carbon ratio (~ 0.5 is characteristic of freshly formed secondary organic aerosol; and (G differences in the overall growth rate from one formation event to another are caused by variations in the growth rates of all major chemical species, not just one individual species.

Particle resuspension due to human walking

International Nuclear Information System (INIS)

Mana, Zakaria

2014-01-01

In nuclear facilities, during normal operations in controlled areas, workers could be exposed to radioactive aerosols (1 μm ≤ dp ≤ 10 μm). One of the airborne contamination sources is particles that are initially seeded on the floor and could be removed by workers while they are walking. During the outage of EDF nuclear facilities, there is a resuspension of some radionuclides in aerosol form (1 μm ≤ dp ≤ 10 μm). Since the number of co-activity will increase in reactors buildings of EDF, it becomes important to understand particle resuspension due to the activity of the operators to reduce their radiation exposure. The purpose of this Ph.D thesis is to quantify the resuspension of particles due to the progress of operators on a contaminated soil. Thus, the approach is to combine an aerodynamic resuspension model with numerical calculations of flow under a shoe, and then to characterize experimentally some input parameters of the model (particle diameter, adhesion forces, shoes motion). The resuspension model Rock'n'Roll proposed by Reeks and Hall (2001) was chosen because it describes physically the resuspension mechanism and because it is based on the moment of forces applied to a particle. This model requires two input parameters such as friction velocity and adhesion forces distribution applied on each particle. Regarding the first argument, numerical simulations were carried on using the ANSYS CFX software applied to a safety shoe in motion (digitized by 3D CAO); the mapping of friction velocity shows values of about 1 m.s -1 for an angular average velocity of 200 degrees.s -1 . As regards the second parameter, AFM (Atomic Force Microscopy) measurements were carried out with alumina and cobalt oxide particles in contact with epoxy surfaces representative of those encountered in EDF power plants. AFM provides the distribution of adhesion forces and reveals a much lower value than what can be calculated theoretically using JKR model (Johnson

Pet ownership increases human risk of encountering ticks.

Science.gov (United States)

Jones, E H; Hinckley, A F; Hook, S A; Meek, J I; Backenson, B; Kugeler, K J; Feldman, K A

2018-02-01

We examined whether pet ownership increased the risk for tick encounters and tickborne disease among residents of three Lyme disease-endemic states as a nested cohort within a randomized controlled trial. Information about pet ownership, use of tick control for pets, property characteristics, tick encounters and human tickborne disease were captured through surveys, and associations were assessed using univariate and multivariable analyses. Pet-owning households had 1.83 times the risk (95% CI = 1.53, 2.20) of finding ticks crawling on and 1.49 times the risk (95% CI = 1.20, 1.84) of finding ticks attached to household members compared to households without pets. This large evaluation of pet ownership, human tick encounters and tickborne diseases shows that pet owners, whether of cats or dogs, are at increased risk of encountering ticks and suggests that pet owners are at an increased risk of developing tickborne disease. Pet owners should be made aware of this risk and be reminded to conduct daily tick checks of all household members, including the pets, and to consult their veterinarian regarding effective tick control products. © 2017 Blackwell Verlag GmbH.

Determination of air exchange rates of rooms and deposition factors for fine particles by means of photoelectric aerosol sensors

International Nuclear Information System (INIS)

Skillas, G.; Siegmann, H.C.; Hueglin, Ch.

1999-01-01

Indoor and outdoor concentrations or airborne fine particles from internal combustion engines have been measured over periods of 24 h with a time resolution of 10 s. With this time series, the ventilation air exchange rate of different rooms has been computed using a novel approach to the solution of the mass balance equation. A 'mixing time' parameter has been introduced in order to account for the initial non-homogeneous distribution of the pollutants in the rooms. It is demonstrated that this method can be used to determine the impact of health relevant outdoor particles on the indoor particle concentration. This yields information on the protection a building offers against pollutants entering from outdoors. (author)

Computational Modelling of Gas-Particle Flows with Different Particle Morphology in the Human Nasal Cavity

Directory of Open Access Journals (Sweden)

Kiao Inthavong

2009-01-01

Full Text Available This paper summarises current studies related to numerical gas-particle flows in the human nasal cavity. Of interest are the numerical modelling requirements to consider the effects of particle morphology for a variety of particle shapes and sizes such as very small particles sizes (nanoparticles, elongated shapes (asbestos fibres, rough shapes (pollen, and porous light density particles (drug particles are considered. It was shown that important physical phenomena needed to be addressed for different particle characteristics. This included the Brownian diffusion for submicron particles. Computational results for the nasal capture efficiency for nano-particles and various breathing rates in the laminar regime were found to correlate well with the ratio of particle diffusivity to the breathing rate. For micron particles, particle inertia is the most significant property and the need to use sufficient drag laws is important. Drag correlations for fibrous and rough surfaced particles were investigated to enable particle tracking. Based on the simulated results, semi-empirical correlations for particle deposition were fitted in terms of Peclet number and inertial parameter for nanoparticles and micron particles respectively.

Single particle aerosol mass spectrometry of coal combustion particles associated with high lung cancer rates in Xuanwei and Fuyuan, China.

Science.gov (United States)

Lu, Senlin; Tan, Zhengying; Liu, Pinwei; Zhao, Hui; Liu, Dingyu; Yu, Shang; Cheng, Ping; Win, Myat Sandar; Hu, Jiwen; Tian, Linwei; Wu, Minghong; Yonemochi, Shinich; Wang, Qingyue

2017-11-01

Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM). The total of 38,372 particles mass-analyzed by SPAMS can be divided into 9 groups based on their chemical composition and their number percentages: carbonaceous, Na-rich, K-rich, Al-rich, Fe-rich, Si-rich, Ca-rich, heavy metal-bearing, and PAH-bearing particles. The carbonaceous and PAH-bearing particles are enriched in the size range below 0.56 μm, Fe-bearing particles range from 0.56 to 1.0 μm in size, and heavy metals such as Ti, V, Cr, Cu, Zn, and Pb have diameters below 1 μm. The TEM results show that the particles from Xuanwei and Fuyuan coal combustion can be classified into soot aggregates, Fe-rich particles, heavy metal containing particles, and mineral particles. Non-volatile particles detected by SPAMS could also be observed with TEM. The number percentages by SPAMS also correlate with the mass concentrations measured by ICP-MS. Our results could provide valuable insight for understanding high lung cancer incidence in the area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Athletic Training Student Core Competency Implementation During Patient Encounters.

Science.gov (United States)

Cavallario, Julie M; Van Lunen, Bonnie L; Hoch, Johanna M; Hoch, Matthew; Manspeaker, Sarah A; Pribesh, Shana L

2018-03-01

  Health care research evidence suggests that early patient encounters (PEs), as well as the purposeful implementation of professional core competencies (CCs), for athletic training students (ATSs) may be beneficial to their ability to provide care. However, no investigators have related facets of the clinical education experience with CC implementation as a form of summative assessment of the clinical experience.   To determine the relationship between the frequency and length of PEs, as well as the student's role and clinical site during PEs, and the students' perceived CC implementation during these encounters.   Cross-sectional study.   Professional athletic training program, National Collegiate Athletic Association Division I institution.   We purposefully recruited 1 athletic training program that used E*Value software; 40 participants (31 females, 9 males) enrolled in the professional phase (12 first year, 14 second year, 14 third year) participated.   Participants viewed a 20-minute recorded CC educational module followed by educational handouts, which were also posted online for reference throughout the semester. The E*Value software was used to track PEs, including the type of encounter (ie, actual patient, practice encounter, didactic practice scenario), the type of site where the encounter occurred (university, high school), and the participant's role (observed, assisted, performed), as well as responses to an added block of questions indicating which, if any, of the CCs were implemented during the PE.   Variables per patient were PE length (minutes), participant role, site at which the encounter occurred, and whether any of the 6 CCs were implemented ( yes/ no). Variables per participant were average encounter length (minutes), encounter frequency, modal role, clinical site assignment, and the number of times each CC was implemented. Separate 1-way analyses of variance were used to examine the relationships between role or clinical site

Quantifying the Effects of Gas-Rich Flyby Encounters on Galaxy Evolution

Science.gov (United States)

Dumas, Julie; Holley-Bockelmann, Kelly; Lang, Meagan

2017-01-01

Recent work has shown that flyby encounters may be a common event in a galaxy's lifetime. Galaxy flybys are a one-time encounter when two halos interpenetrate, but unlike a galaxy merger, the two halos later detach. Relatively little work has been done to assess how flybys affect galaxy evolution. We present preliminary results of a suite of high-resolution hydrodynamical + N-body simulations of gas-rich flyby encounters, concentrating on Milky Way-like primaries. We track the bulk changes in structure, star formation history, kinematics, and morphology over a broad span of flyby encounters.

A study on the particle penetration in RMS Right Single Quotation Marks particle transport system

International Nuclear Information System (INIS)

Son, S. M.; Oh, S. H.; Choi, C. R.

2014-01-01

In nuclear facilities, a radiation monitoring system (RMS) monitors the exhaust gas containing the radioactive material. Samples of exhaust gas are collected in the downstream region of air cleaning units (ACUs) in order to examine radioactive materials. It is possible to predict an amount of radioactive material by analyzing the corrected samples. Representation of the collected samples should be assured in order to accurately sense and measure of radioactive materials. The radius of curvature is mainly 5 times of tube diameter. Sometimes, a booster fan is additionally added to enhance particle penetration rate... In this study, particle penetrations are calculated to evaluate particle penetration rate with various design parameters (tube lengths, tube declined angles, radius of curvatures, etc). The particle penetration rates have been calculated for several elements in the particle transport system. In general, the horizontal length of tube and the number of bending tube have a big impact on the penetration rate in the particle transport system. If the sampling location is far from the radiation monitoring system, additional installation of booster fans could be considered in case of large diameter tubes, but is not recommended in case of small diameter tube. In order to enhance particle penetration rate, the following works are recommended by priority. 1) to reduce the interval between sampling location and radiation monitoring system 2) to reduce the number of the bending tube

Development of laboratory and process sensors to monitor particle size distribution of industrial slurries

Energy Technology Data Exchange (ETDEWEB)

Pendse, H.P.

1992-10-01

In this paper we present a novel measurement technique for monitoring particle size distributions of industrial colloidal slurries based on ultrasonic spectroscopy and mathematical deconvolution. An on-line sensor prototype has been developed and tested extensively in laboratory and production settings using mineral pigment slurries. Evaluation to date shows that the sensor is capable of providing particle size distributions, without any assumptions regarding their functional form, over diameters ranging from 0.1 to 100 micrometers in slurries with particle concentrations of 10 to 50 volume percents. The newly developed on-line sensor allows one to obtain particle size distributions of commonly encountered inorganic pigment slurries under industrial processing conditions without dilution.

Dynamics of neutral and charged aerosol particles

Energy Technology Data Exchange (ETDEWEB)

Leppae, J.

2012-07-01

Atmospheric aerosol particles have various climate effects and adverse health effects, which both depend on the size and number concentration of the particles. Freshly-formed particles are not large enough to impact neither health nor climate and they are most susceptible to removal by collisions with larger pre-existing particles. Consequently, the knowledge of both the formation and the growth rate of particles are crucially important when assessing the health and climate effects of atmospheric new particle formation. The purpose of this thesis is to increase our knowledge of the dynamics of neutral and charged aerosol particles with a specific interest towards the particle growth rate and processes affecting the aerosol charging state. A new model, Ion-UHMA, which simulates the dynamics of neutral and charged particles, was developed for this purpose. Simple analytical formulae that can be used to estimate the growth rate due to various processes were derived and used to study the effects of charged particles on the growth rate. It was found that the growth rate of a freshly-formed particle population due to condensation and coagulation could be significantly increased when a considerable fraction of the particles are charged. Finally, recent data-analysis methods that have been applied to the aerosol charging states obtained from the measurements were modified for a charge asymmetric framework. The methods were then tested on data obtained from aerosol dynamics simulations. The methods were found to be able to provide reasonable estimates on the growth rate and proportion of particles formed via ion-induced nucleation, provided that the growth rate is high enough and that the charged particles do not grow much more rapidly than the neutral ones. A simple procedure for estimating whether the methods are suitable for analysing data obtained in specific conditions was provided. In this thesis, the dynamics of neutral and charged aerosol particles were studied in

Recent trends in particle accelerator radiation safety

International Nuclear Information System (INIS)

Ohnesorge, W.F.; Butler, H.M.

1974-01-01

The use of particle accelerators in applied and research activities continues to expand, bringing new machines with higher energy and current capabilities which create radiation safety problems not commonly encountered before. An overview is given of these increased ionizing radiation hazards, along with a discussion of some of the new techniques required in evaluating and controlling them. A computer search of the literature provided a relatively comprehensive list of publications describing accelerator radiation safety problems and related subjects

Initiating Service Encounter-based Innovation by Word-of-Business

DEFF Research Database (Denmark)

Mattsson, Jan

2015-01-01

Purpose – This paper aims to set up a natural experiment as action research and to develop a framework of cognitive distance of informants to improve the initiation of service encounter-based innovation. Design/methodology/approach – Natural experiment as action research in one Scandinavian case...... transcriptions of interviews and transcriptions. Research limitations/implications – Only one Scandinavian company and a limited number of informants were activated. Also, the time period only included the initiation phase of service encounter-based innovation. Practical implications – Three different strategies...... in an emerging innovation field, open/user-driven innovation. Theory from business marketing, service encounter and innovation is also used....

Particle deposition in ventilation ducts

Energy Technology Data Exchange (ETDEWEB)

Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)

2002-09-01

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the

The Particle Number Emission Characteristics of the Diesel Engine with a Catalytic Diesel Particle Filter

Directory of Open Access Journals (Sweden)

Li Jia Qiang

2016-01-01

Full Text Available Due to their adverse health effects and their abundance in urban areas, diesel exhaust ultrafine particles caused by the aftertreatment devices have been of great concern in the past years. An experiment of particles number emissions was carried out on a high-pressure, common rail diesel engine with catalytic diesel particle filter (CDPF to investigate the impact of CDPF on the number emission characteristics of particles. The results indicated that the conversion rates of CDPF is over 97%. The size distributions of particles are bimodal lognormal distributions downstream CDPF at 1400 r/min and 2300 r/min. CDPF has a lower conversion rates on the nucleation mode particles. The geometric number mean diameters of particles downstream CDPF is smaller than that upstream CDPF.

Control of spontaneous emission rate in luminescent resonant diamond particles

Science.gov (United States)

Savelev, R.; Zalogina, A.; Kudryashov, S.; Ivanova, A.; Levchenko, A.; Makarov, S.; Zuev, D.; Shadrivov, I.

2018-01-01

We study the properties of luminescent diamond particles of different sizes (up to ~1.5 μm) containing multiple NV-centers. We theoretically predict that the average liftetime in such particles is decreased by several times as compared to optically small subwavelength nanodiamonds. In our experiments, samples were obtained by milling the plasma-enhanced chemical vapor deposited diamond film, and characterized by Raman spectroscopy and dark- field spectroscopy methods. Time-resolved luminescence measurements of the excited state of NV-centers showed that their average lifetime varies from 10 to 17 ns in different samples. By comparing this data to the values of the lifetime of the NV-centers in optically small nanodiamonds, known from literature, we confirm a severalfold decrease of the lifetime in resonant particles.

Preliminary results of the alpha particle registration intercomparison ALRIT

International Nuclear Information System (INIS)

Paretzke, H.G.

1976-01-01

In view of the widespread interest in alpha particle registration with solid state nuclear track detectors, an international intercomparison of such measurements has been arranged. Sixteen sets of fourteen detectors each were sent to GSF-Neuherberg, there irradiated carefully with different alpha particle fields, and then returned for evaluation. Fourteen irradiation runs were made for each set simulating seven different irradiation situations commonly encountered in practical applications. The preliminary results of this intercomparison reported in this paper are based on the results of eight sets. They show good agreement with respect to the determination of track densities in the case of vertical incident alpha particles. Also the results obtained for determination of particle energies and angle of incidence in most cases were rather accurate. However, apparently it is still rather difficult to determine accurately and precisely the specific activity of alpha emitters on a thick filter positioned at some distance, i.e. for the case of 2π-incidence and a broad energy spectrum. (orig.) [de

Particle magnetic moment conservation and resonance in a pure magnetohydrodynamic shock and field inclination influence on diffusive shock acceleration

International Nuclear Information System (INIS)

Lieu, R.; Quenby, J.J.

1990-01-01

Computational and analytical methods have been used in a study of particle acceleration by MHD shocks. Numerical simulations of single-particle trajectories indicate that magnetic moment is conserved quite accurately for an encounter with a near-perpendicular shock, and for all pitch angles except the very small ones. Acceleration is most effective for particles which are reflected by the shock at small pitch angles. If future encounters with the shock are possible, large acceleration will be repeated only for relativistic plasma flow velocities. Results for the pure MHD shock are then considered within the context of a diffusion model (hence a diffusive MHD shock). The microscopic approach is employed whereby one follows the history of a test particle and explicitly takes into account the possibility of reflection by the shock. Exact analytical solutions are currently available to order V/c, where V is the plasma flow speed, and are found to be in complete agreement with diffusion theory. More specifically, the presence of electromagnetic effects leads to a shortening of acceleration time scale but does not change the steady state spectrum of energetic particles. 7 refs

Calculating gamma dose factors for hot particle exposures

International Nuclear Information System (INIS)

Murphy, P.

1990-01-01

For hot particle exposures to the skin, the beta component of radiation delivers the majority of the dose. However, in order to fully demonstrate regulatory compliance, licenses must ordinarily provide reasonable bases for assuming that both the gamma component of the skin dose and the whole body doses are negligible. While beta dose factors are commonly available in the literature, gamma dose factors are not. This paper describes in detail a method by which gamma skin dose factors may be calculated using the Specific Gamma-ray Constant, even if the particle is not located directly on the skin. Two common hot particle exposure geometries are considered: first, a single square centimeter of skin lying at density thickness of 7 mg/cm 2 and then at 1000 mg/cm 2 . A table provides example gamma dose factors for a number of isotopes encountered at power reactors

Ulysses at jupiter: an overview of the encounter.

Science.gov (United States)

Smith, E J; Wenzel, K P; Page, D E

1992-09-11

In February 1992, the Ulysses spacecraft flew through the giant magnetosphere of Jupiter. The primary objective of the encounter was to use the gravity field of Jupiter to redirect the spacecraft to the sun's polar regions, which will now be traversed in 1994 and 1995. However, the Ulysses scientific investigations were well suited to observations of the Jovian magnetosphere, and the encounter has resulted in a major contribution to our understanding of this complex and dynamic plasma environment. Among the more exciting results are (i) possible entry into the polar cap, (ii) the identification of magnetospheric ions originating from Jupiter's ionosphere, lo, and the solar wind, (iii) observation of longitudinal asymmetries in density and discrete wave-emitting regions of the lo plasma torus, (iv) the presence of counter-streaming ions and electrons, field-aligned currents, and energetic electron and radio bursts in the dusk sector on high-latitude magnetic field lines, and (v) the identification of the direction of the magnetic field in the dusk sector, which is indicative of tailward convection. This overview serves as an introduction to the accompanying reports that present the preliminary scientific findings. Aspects of the encounter that are common to all of the investigations, such as spacecraft capabilities, the flight path past Jupiter, and unique aspects of the encounter, are presented herein.

Microstructure and Strain Rate Effects on the Mechanical Behavior of Particle Reinforced Epoxy-Based Reactive Materials

Science.gov (United States)

2011-12-01

particles using positron annihilation lifetime spectroscopy (PALS). They found that the free volume of the matrix was dependent on the volume fraction...mechanical analysis and positron annihilation lifetime spectroscopy ,” Polymer International, vol. 51, pp. 1277–1284, 2002. [35] G. W. Brassell and K. B...use as structural materials in applications at high rates of strain. These types of com- posites are very complex due to their heterogeneous

A Lakatosian Encounter with Probability

Science.gov (United States)

Chick, Helen

2010-01-01

There is much to be learned and pondered by reading "Proofs and Refutations" by Imre Lakatos (Lakatos, 1976). It highlights the importance of mathematical definitions, and how definitions evolve to capture the essence of the object they are defining. It also provides an exhilarating encounter with the ups and downs of the mathematical reasoning…

Considerations of particle vaporization and analyte diffusion in single-particle inductively coupled plasma-mass spectrometry

International Nuclear Information System (INIS)

Ho, Koon-Sing; Lui, Kwok-On; Lee, Kin-Ho; Chan, Wing-Tat

2013-01-01

The intensity of individual gold nanoparticles with nominal diameters of 80, 100, 150, and 200 nm was measured using single-particle inductively coupled plasma-mass spectrometry (ICP-MS). Since the particles are not perfectly monodisperse, a distribution of ICP-MS intensity was obtained for each nominal diameter. The distribution of particle mass was determined from the transmission electron microscopy (TEM) image of the particles. The distribution of ICP-MS intensity and the distribution of particle mass for each nominal diameter were correlated to give a calibration curve. The calibration curves are linear, but the slope decreases as the nominal diameter increases. The reduced slope is probably due to a smaller degree of vaporization of the large particles. In addition to the degree of particle vaporization, the rate of analyte diffusion in the ICP is an important factor that determines the measured ICP-MS intensity. Simulated ICP-MS intensity versus particle size was calculated using a simple computer program that accounts for the vaporization rate of the gold nanoparticles and the diffusion rate and degree of ionization of the gold atoms. The curvature of the simulated calibration curves changes with sampling depth because the effects of particle vaporization and analyte diffusion on the ICP-MS intensity are dependent on the residence time of the particle in the ICP. Calibration curves of four hypothetical particles representing the four combinations of high and low boiling points (2000 and 4000 K) and high and low analyte diffusion rates (atomic masses of 10 and 200 Da) were calculated to further illustrate the relative effects of particle vaporization and analyte diffusion. The simulated calibration curves show that the sensitivity of single-particle ICP-MS is smaller than that of the ICP-MS measurement of continuous flow of standard solutions by a factor of 2 or more. Calibration using continuous flow of standard solution is semi-quantitative at best. An

Monte Carlo problem and parallel computers, and how to do a fast particle mover on the STAR 100

International Nuclear Information System (INIS)

Sinz, K.H.P.H.

1975-01-01

Particle simulation problems of the Monte Carlo type are widely believed to be intrinsically highly scalar problems. In the absence of a definitive mathematical theorem to the contrary, this belief is based on the very apparent programming difficulties encountered on a vector machine. This class of problem is therefore thought to be ill-suited to highly parallel and vectorized computers. However, it is demonstrated by several examples that a particle mover is fully vectorizable. In the case of the CDC STAR 100 it is found that the performance of such a particle mover is not hopeless but hopeful, and is in fact helpful. One of the several possible vectorizations is estimated to yield a gain of a factor of 15 on the STAR over good serial coding on the same machine. This falls far short of the STAR's peak vector performance of 30 to 70 times scalar rates because certain fast vector instructions are not available and have to be simulated. The current STAR algorithm outperforms the carefully handcoded 7600 by a factor of 3. This performance margin is achievable despite the 7600's fivefold superior scalar capability. A more generally vectorized particle mover will always substantially outperform scalar coding on any machine equipped with a properly chosen set of fast vector instructions. (U.S.)

Spacecraft environment during the GIOTTO-Halley encounter: a summary

International Nuclear Information System (INIS)

Young, D.T.

1983-01-01

A summary of the present volume is presented in which the separate disciplines are drawn together to give an overview of the spacecraft environment during the GIOTTO-Halley interaction. Specific recommendations are made as to how the work of the Plasma Environment Working Group might continue to contribute to the GIOTTO program during encounter and post-encounter data analysis. 28 references, 3 tables

PARTICLE FILTER BASED VEHICLE TRACKING APPROACH WITH IMPROVED RESAMPLING STAGE

Directory of Open Access Journals (Sweden)

Wei Leong Khong

2014-02-01

Full Text Available Optical sensors based vehicle tracking can be widely implemented in traffic surveillance and flow control. The vast development of video surveillance infrastructure in recent years has drawn the current research focus towards vehicle tracking using high-end and low cost optical sensors. However, tracking vehicles via such sensors could be challenging due to the high probability of changing vehicle appearance and illumination, besides the occlusion and overlapping incidents. Particle filter has been proven as an approach which can overcome nonlinear and non-Gaussian situations caused by cluttered background and occlusion incidents. Unfortunately, conventional particle filter approach encounters particle degeneracy especially during and after the occlusion. Particle filter with sampling important resampling (SIR is an important step to overcome the drawback of particle filter, but SIR faced the problem of sample impoverishment when heavy particles are statistically selected many times. In this work, genetic algorithm has been proposed to be implemented in the particle filter resampling stage, where the estimated position can converge faster to hit the real position of target vehicle under various occlusion incidents. The experimental results show that the improved particle filter with genetic algorithm resampling method manages to increase the tracking accuracy and meanwhile reduce the particle sample size in the resampling stage.

Fractal and Morphological Characteristics of Single Marble Particle Crushing in Uniaxial Compression Tests

Directory of Open Access Journals (Sweden)

Yidong Wang

2015-01-01

Full Text Available Crushing of rock particles is a phenomenon commonly encountered in geotechnical engineering practice. It is however difficult to study the crushing of rock particles using classical theory because the physical structure of the particles is complex and irregular. This paper aims at evaluating fractal and morphological characteristics of single rock particle. A large number of particle crushing tests are conducted on single rock particle. The force-displacement curves and the particle size distributions (PSD of crushed particles are analysed based on particle crushing tests. Particle shape plays an important role in both the micro- and macroscale responses of a granular assembly. The PSD of an assortment of rocks are analysed by fractal methods, and the fractal dimension is obtained. A theoretical formula for particle crushing strength is derived, utilising the fractal model, and a simple method is proposed for predicting the probability of particle survival based on the Weibull statistics. Based on a few physical assumptions, simple equations are derived for determining particle crushing energy. The results of applying these equations are tested against the actual experimental data and prove to be very consistent. Fractal theory is therefore applicable for analysis of particle crushing.

Encounters with immigrant customers: perspectives of Danish community pharmacy staff on challenges and solutions.

Science.gov (United States)

Mygind, Anna; Espersen, Sacha; Nørgaard, Lotte Stig; Traulsen, Janine M

2013-06-01

To explore the challenges that Danish community pharmacy staff encounter when serving non-Western immigrant customers. Special attention was paid to similarities and differences between the perceptions of pharmacists and pharmacy assistants. A questionnaire was distributed to one pharmacist and one pharmacy assistant employed at each of the 55 community pharmacies located in the five local councils in Denmark with the highest number of immigrant inhabitants. The total response rate was 76% (84/110). Most respondents found that the needs of immigrant customers were not sufficiently assessed at the counter (n = 55, 65%), and that their latest encounter with an immigrant customer was less satisfactory than a similar encounter with an ethnic Danish customer (n = 48, 57%) (significantly more pharmacists than assistants: odds ratio, OR, 3.19; 95% confidence interval, CI, 1.27-8.04). Forty-two per cent (n = 35) perceived that immigrant customers put pressure on pharmacy staff resources, while 27% (n = 23) found that the immigrant customer group make work more interesting. More pharmacists than assistants agreed on the latter (OR, 3.43; 95% CI, 1.04-11.33). Within the past 14 days, 86% (n = 72) experienced that their advice and counselling were not understood by immigrant customers, whereas 49% (n = 41) experienced lack of understanding by ethnic Danes; and 30% (n = 25) had consciously refrained from counselling an immigrant, whereas 19% (n = 16) had done so with an ethnic Dane. Use of under-aged children as interpreters during the past month was reported by 79% of respondents. Regarding suggestions on how to improve encounters with immigrant customers, most respondents listed interventions aimed at patients, general practitioners and pharmaceutical companies. Community pharmacy staff report poorer quality in their encounters with immigrant customers, including sub-optimal counselling and frequent use of under-aged children as

Improvement of a method for predicting failure rates of coated particles during irradiation

International Nuclear Information System (INIS)

Bongartz, K.

1977-01-01

A method for calculating the coating stress distribution resulting from the statistical spread of geometrical parameters in irradiated fuel particle batches has been developed by Gulden et al. The existing method utilizing coated particles is extended in two ways: 1. A more realistic treatment of the buffer layer is adopted, taking into account its physical properties. 2. A statistical distribution according to Weibull has been adopted for the silicon carbide layer strength. Calculations with both the new and the old assumptions were performed on one feed particle and one breed particle type. It is shown that the two modifications influence the results of the original method. It was found that the extension of the first assumption has no influence on the stress distribution and the fraction of breaking feed particles, but it changes the stress distribution of the breed particles significantly. The fraction of broken particles at end burnup is increased by a factor of approximately 10. The extension of the second assumption affects the fraction of broken feed as well as that of the breed particles. Depending on the Weibull parameter, m, the number of failed feed particles increases by a factor of 1.3 to 2; the corresponding factor for breed particles is between 3.5 and 60

A robust upscaling of the effective particle deposition rate in porous media

Science.gov (United States)

Boccardo, Gianluca; Crevacore, Eleonora; Sethi, Rajandrea; Icardi, Matteo

2018-05-01

In the upscaling from pore to continuum (Darcy) scale, reaction and deposition phenomena at the solid-liquid interface of a porous medium have to be represented by macroscopic reaction source terms. The effective rates can be computed, in the case of periodic media, from three-dimensional microscopic simulations of the periodic cell. Several computational and semi-analytical models have been studied in the field of colloid filtration to describe this problem. They typically rely on effective deposition rates defined by complex fitting procedures, neglecting the advection-diffusion interplay, the pore-scale flow complexity, and assuming slow reactions (or large Péclet numbers). Therefore, when these rates are inserted into general macroscopic transport equations, they can lead to several conceptual inconsistencies and significant errors. To study more accurately the dependence of deposition on the flow parameters, in this work we advocate a clear distinction between the surface processes (that altogether defines the so-called attachment efficiency), and the pore-scale processes. With this approach, valid when colloidal particles are small enough, we study Brownian and gravity-driven deposition on a face-centred cubic (FCC) arrangement of spherical grains, and define a robust upscaling based on a linear effective reaction rate. The case of partial deposition, defined by an attachment probability, is studied and the limit of perfect sink is retrieved as a particular case. We introduce a novel upscaling approach and a particularly convenient computational setup that allows the direct computation of the asymptotic stationary value of effective rates. This allows to drastically reduce the computational domain down to the scale of the single repeating periodic unit. The savings are ever more noticeable in the case of higher Péclet numbers, when larger physical times are needed to reach the asymptotic regime and thus, equivalently, much larger computational domain and

Charged particle periodicity in the Saturnian magnetosphere

International Nuclear Information System (INIS)

Carbary, J.F.; Krimigis, S.M.

1982-01-01

The low energy charged particles (LECP) experiments on the Voyager 1 and 2 spacecraft performed measurements of electrons (approx.22 keV to approx.20 MeV) and ions (approx.28 keV to approx.150 MeV) during the Saturn encounters in 1980 and 1981. Count rate ratios of two of the low energy electron (22 to 35 keV and 183 to 500 keV) and ion (43 to 80 keV and 137 to 215 keV) channels exhibit an approximation 10 hour periodicity in the outer Saturnian magnetosphere beyond the orbit of Titan. Electron ratios vary from approx.50 to approx.300; ion ratios vary from approx.3 to approx.20. Similar but less pronounced periodicities are observed for higher and lower energy electron and ion spectral indices. Three complete cycles were observed during the Voyager 2 outbound portion of the encounter from which were determined an electron ratio period of 10/sup h/21/sup m/ +- 48/sup m/ and an ion ratio period of 9/sup h/49/sup m/ +- 59/sup m/. Using Saturn Kilometric Radiation (SKR) and Saturn Electrostatic Discharge (SED) periods, extrapolation backward from Voyager 2 to Voyager 1 suggests that the periodicities are Saturnian rather than Jovian in nature, and that they persist in phase for time intervals at least as long as 287 days. Ratio minima, or spectral hardenings, occur in the same hemisphere as do auroral brightenings, SKR activity, and spoke enhanement. We interpret the observations as prima facie evidence of an asymmetry in the Saturian magnetic field and the root cause of the observed SKR periodicity

Ultra-high-speed digital in-line holography system applied to particle-laden supersonic underexpanded jet flows

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Buchmann, Nicolas A.; Soria, Julio

2012-01-01

-fluid interactions in these high-speed flows special high performance techniques are required. The present work is an investigation into the applicability of magnified digital in-line holography with ultra-high-speed recording for the study of three-dimensional supersonic particle-laden flows. An optical setup...... × 10mm calibration grid and 120 μm particles on a glass plate. In the case with the calibration grid it is found that accurate determination of the depthwise position is possible. However, when applying the same technique to the particle target, significant problems are encountered. © 2012...

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes

KAUST Repository

Li, Yiyang; El Gabaly, Farid; Ferguson, Todd R.; Smith, Raymond B.; Bartelt, Norman C.; Sugar, Joshua D.; Fenton, Kyle R.; Cogswell, Daniel A.; Kilcoyne, A. L. David; Tyliszczak, Tolek; Bazant, Martin Z.; Chueh, William C.

2014-01-01

©2014 Macmillan Publishers Limited. All rights reserved. Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO 4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes.

Science.gov (United States)

Li, Yiyang; El Gabaly, Farid; Ferguson, Todd R; Smith, Raymond B; Bartelt, Norman C; Sugar, Joshua D; Fenton, Kyle R; Cogswell, Daniel A; Kilcoyne, A L David; Tyliszczak, Tolek; Bazant, Martin Z; Chueh, William C

2014-12-01

Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes

KAUST Repository

Li, Yiyang

2014-09-14

©2014 Macmillan Publishers Limited. All rights reserved. Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO 4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

The Power of Citizens and Professionals in Welfare Encounters

DEFF Research Database (Denmark)

Mik-Meyer, Nanna

relationships with welfare workers. However, other factors impact these interactions; factors which often pull in different directions. Welfare encounters are thus influenced by bureaucratic principles and market values as well. Consequently, this book engages with both Weberian (bureaucracy) and Foucauldian...... (market values/NPM) studies when investigating the powerful welfare encounter. The book is targeted Academics, post-graduates, and undergraduates within sociology, anthropology and political science....

Charged particle detectors made from thin layers of amorphous silicon

International Nuclear Information System (INIS)

Morel, J.R.

1986-05-01

A series of experiments was conducted to determine the feasibility of using hydrogenated amorphous silicon (α-Si:H) as solid state thin film charged particle detectors. 241 Am alphas were successfully detected with α-Si:H devices. The measurements and results of these experiments are presented. The problems encountered and changes in the fabrication of the detectors that may improve the performance are discussed

Association of volume of patient encounters with residents' in-training examination performance.

Science.gov (United States)

McCoy, Christopher P; Stenerson, Matthew B; Halvorsen, Andrew J; Homme, Jason H; McDonald, Furman S

2013-08-01

Patient care and medical knowledge are Accreditation Council for Graduate Medical Education (ACGME) core competencies. The correlation between amount of patient contact and knowledge acquisition is not known. To determine if a correlation exists between the number of patient encounters and in-training exam (ITE) scores in internal medicine (IM) and pediatric residents at a large academic medical center. Retrospective cohort study Resident physicians at Mayo Clinic from July 2006 to June 2010 in IM (318 resident-years) and pediatrics (66 resident-years). We tabulated patient encounters through review of clinical notes in an electronic medical record during post graduate year (PGY)-1 and PGY-2. Using linear regression models, we investigated associations between ITE score and number of notes during the previous PGY, adjusted for previous ITE score, gender, medical school origin, and conference attendance. For IM, PGY-2 admission and consult encounters in the hospital and specialty clinics had a positive linear association with ITE-3 % score (β = 0.02; p = 0.004). For IM, PGY-1 conference attendance is positively associated with PGY-2 ITE performance. We did not detect a correlation between PGY-1 patient encounters and subsequent ITE scores for IM or pediatric residents. No association was found between IM PGY-2 ITE score and inpatient, outpatient, or total encounters in the first year of training. Resident continuity clinic and total encounters were not associated with change in PGY-3 ITE score. We identified a positive association between hospital and subspecialty encounters during the second year of IM training and subsequent ITE score, such that each additional 50 encounters were associated with an increase of 1 % correct in PGY-3 ITE score after controlling for previous ITE performance and continuity clinic encounters. We did not find a correlation for volume of encounters and medical knowledge for IM PGY-1 residents or the pediatric cohort.

Phase identification of quasi-periodic flow measured by particle image velocimetry with a low sampling rate

International Nuclear Information System (INIS)

Pan, Chong; Wang, Hongping; Wang, Jinjun

2013-01-01

This work mainly deals with the proper orthogonal decomposition (POD) time coefficient method used for extracting phase information from quasi-periodic flow. The mathematical equivalence between this method and the traditional cross-correlation method is firstly proved. A two-dimensional circular cylinder wake flow measured by time-resolved particle image velocimetry within a range of Reynolds numbers is then used to evaluate the reliability of this method. The effect of both the sampling rate and Reynolds number on the identification accuracy is finally discussed. It is found that the POD time coefficient method provides a convenient alternative for phase identification, whose feasibility in low-sampling-rate measurement has additional advantages for experimentalists. (paper)

Very massive runaway stars from three-body encounters

Science.gov (United States)

Gvaramadze, Vasilii V.; Gualandris, Alessia

2011-01-01

Very massive stars preferentially reside in the cores of their parent clusters and form binary or multiple systems. We study the role of tight very massive binaries in the origin of the field population of very massive stars. We performed numerical simulations of dynamical encounters between single (massive) stars and a very massive binary with parameters similar to those of the most massive known Galactic binaries, WR 20a and NGC 3603-A1. We found that these three-body encounters could be responsible for the origin of high peculiar velocities (≥70 km s-1) observed for some very massive (≥60-70 M⊙) runaway stars in the Milky Way and the Large Magellanic Cloud (e.g. λ Cep, BD+43°3654, Sk -67°22, BI 237, 30 Dor 016), which can hardly be explained within the framework of the binary-supernova scenario. The production of high-velocity massive stars via three-body encounters is accompanied by the recoil of the binary in the opposite direction to the ejected star. We show that the relative position of the very massive binary R145 and the runaway early B-type star Sk-69°206 on the sky is consistent with the possibility that both objects were ejected from the central cluster, R136, of the star-forming region 30 Doradus via the same dynamical event - a three-body encounter.

General particle transport equation. Final report

International Nuclear Information System (INIS)

Lafi, A.Y.; Reyes, J.N. Jr.

1994-12-01

The general objectives of this research are as follows: (1) To develop fundamental models for fluid particle coalescence and breakage rates for incorporation into statistically based (Population Balance Approach or Monte Carlo Approach) two-phase thermal hydraulics codes. (2) To develop fundamental models for flow structure transitions based on stability theory and fluid particle interaction rates. This report details the derivation of the mass, momentum and energy conservation equations for a distribution of spherical, chemically non-reacting fluid particles of variable size and velocity. To study the effects of fluid particle interactions on interfacial transfer and flow structure requires detailed particulate flow conservation equations. The equations are derived using a particle continuity equation analogous to Boltzmann's transport equation. When coupled with the appropriate closure equations, the conservation equations can be used to model nonequilibrium, two-phase, dispersed, fluid flow behavior. Unlike the Eulerian volume and time averaged conservation equations, the statistically averaged conservation equations contain additional terms that take into account the change due to fluid particle interfacial acceleration and fluid particle dynamics. Two types of particle dynamics are considered; coalescence and breakage. Therefore, the rate of change due to particle dynamics will consider the gain and loss involved in these processes and implement phenomenological models for fluid particle breakage and coalescence

Connection between encounter volume and diffusivity in geophysical flows

Science.gov (United States)

Rypina, Irina I.; Smith, Stefan G. Llewellyn; Pratt, Larry J.

2018-04-01

Trajectory encounter volume - the volume of fluid that passes close to a reference fluid parcel over some time interval - has been recently introduced as a measure of mixing potential of a flow. Diffusivity is the most commonly used characteristic of turbulent diffusion. We derive the analytical relationship between the encounter volume and diffusivity under the assumption of an isotropic random walk, i.e., diffusive motion, in one and two dimensions. We apply the derived formulas to produce maps of encounter volume and the corresponding diffusivity in the Gulf Stream region of the North Atlantic based on satellite altimetry, and discuss the mixing properties of Gulf Stream rings. Advantages offered by the derived formula for estimating diffusivity from oceanographic data are discussed, as well as applications to other disciplines.

In situ energetic particle observations at comet Halley recorded by instrumentation aboard the Giotto and Vega 1 missions

Energy Technology Data Exchange (ETDEWEB)

McKenna-Lawlor, S.; Daly, P.; Kirsch, E.; Wilken, B.; O' Sullivan, D.; Thompson, A.; Kecskemety, K.; Somogyi, A.; Coates, A.

1989-04-01

Three important observations recorded in the energetic particle data secured at Halley's comet during March 1986 are reviewed. These include (a) quasi periodic variations of cometary ion fluxes observed inbound and outbound by both the EPONA instrument aboard Giotto and by the Tunde-M instrument aboard Vega 1. A possible explanation of the results in terms of a spin modulation of the outgassing rate of the nucleus is discussed; (b) by combining the EPONA data with JPA-IIS data it is possible to infer that the ion fluxes measured at encounter by EPONA were of the water group. These particles displayed energies in excess of those attained by the pick-up process acting alone. Comparisons between energy spectra prepared using the composite observational data and, corresponding, theoretically derived plots suggest that, downstream of the shock (inbound), stochastic (second-order-Fermi) acceleration may have contributed to energizing the particles; (c) large fluxes of electrons (E>300keV) and ions (E>3.5 MeV) were unexpectedly recorded by EPONA in the magnetic cavity. The observed enhancements (up to approximately three orders of magnitude) appear to be cometary in origin.

In situ energetic particle observations at comet Halley recorded by instrumentation aboard the Giotto and Vega 1 missions

International Nuclear Information System (INIS)

McKenna-Lawlor, S.; Daly, P.; Kirsch, E.; Wilken, B.; O'Sullivan, D.; Thompson, A.; Kecskemety, K.; Somogyi, A.

1989-01-01

Three important observations recorded in the energetic particle data secured at Halley's comet during March 1986 are reviewed. These include (a) quasi periodic variations of cometary ion fluxes observed inbound and outbound by both the EPONA instrument aboard Giotto and by the Tunde-M instrument aboard Vega 1. A possible explanation of the results in terms of a spin modulation of the outgassing rate of the nucleus is discussed; (b) by combining the EPONA data with JPA-IIS data it is possible to infer that the ion fluxes measured at encounter by EPONA were of the water group. These particles displayed energies in excess of those attained by the pick-up process acting alone. Comparisons between energy spectra prepared using the composite observational data and, corresponding, theoretically derived plots suggest that, downstream of the shock (inbound), stochastic (second-order-Fermi) acceleration may have contributed to energizing the particles; (c) large fluxes of electrons (E>300keV) and ions (E>3.5 MeV) were unexpectedly recorded by EPONA in the magnetic cavity. The observed enhancements (up to approximately three orders of magnitude) appear to be cometary in origin

Challenges in the professional care encounters

DEFF Research Database (Denmark)

Kaldal, Maiken Holm; Kristiansen, Jette; Uhrenfeldt, Lisbeth

in the review. Data were extracted and the findings were categorized and themed on the basis of similarity of meaning and aggregated to produce a comprehensive set of synthesized findings. The review process resulted in 55 findings and 14 categories. The categories generated six themes: Psychological reactions...... to keep the patients happy as they try to avoid conflicts. The imagination and thoughts of what might happen in the encounter are based on the nursing students’ personal life experiences. They uses their close relatives as keys to the express empathy in the establishment of the nurse-patient relation...... are challenged by their personal boundaries in the professional care encounter and they experience a great psychological impact Patient contact is an unavoidable and complex component in the nursing education. The students have not yet built up a professional filter and are exposed to a wealth of emotional...

Motility of copepod nauplii and implications for food encounter

DEFF Research Database (Denmark)

Titelman, Josefin; Kiørboe, Thomas

2003-01-01

(Centropages typicus, Calanus helgolandicus, Temora longicornis, Acartia tonsa, Eurytemora affinis and Euterpina acutifrons). Behaviors of individual nauphi were divided into sequences of sinking, swimming and jumping events. Motility behavior is both stage- and species-specific in terms of appearance......Velocity differences drive all encounter processes. Therefore, knowledge of both prey and predator motility are essential in order to understand feeding behavior and predict food acquisition rates. Here, we describe and quantify the motility behavior of young and old naupliar stages of 6 copepods...... of tracks, speeds, durations and frequencies of events as well as time budgets. Motility mode often changes drastically during naupliar ontogeny. Crudely, nauplii can be divided into those moving with a jump-sink type of motility of various frequencies (1 min(-1) to 3 s(-1)) and those swimming...

Dispersion of Bed Load Particles

OpenAIRE

SAWAI, Kenji

1987-01-01

The motion of bed load particles is so irregular that they disperse remarkably with time.In this study, some flume tests using painted tracer particles were carried out, in which thedispersive property of tracers changed variously with sediment feed rate.In analysing this process, a stochastic simulation model is proposed where it is discussedabout the degree of exposure of individual particle near the bed surface and about the variationof its pick up rate. The exponential distribution of ste...

Nanoparticle growth by particle-phase chemistry

Science.gov (United States)

Apsokardu, Michael J.; Johnston, Murray V.

2018-02-01

The ability of particle-phase chemistry to alter the molecular composition and enhance the growth rate of nanoparticles in the 2-100 nm diameter range is investigated through the use of a kinetic growth model. The molecular components included are sulfuric acid, ammonia, water, a non-volatile organic compound, and a semi-volatile organic compound. Molecular composition and growth rate are compared for particles that grow by partitioning alone vs. those that grow by a combination of partitioning and an accretion reaction in the particle phase between two organic molecules. Particle-phase chemistry causes a change in molecular composition that is particle diameter dependent, and when the reaction involves semi-volatile molecules, the particles grow faster than by partitioning alone. These effects are most pronounced for particles larger than about 20 nm in diameter. The modeling results provide a fundamental basis for understanding recent experimental measurements of the molecular composition of secondary organic aerosol showing that accretion reaction product formation increases linearly with increasing aerosol volume-to-surface-area. They also allow initial estimates of the reaction rate constants for these systems. For secondary aerosol produced by either OH oxidation of the cyclic dimethylsiloxane (D5) or ozonolysis of β-pinene, oligomerization rate constants on the order of 10-3 to 10-1 M-1 s-1 are needed to explain the experimental results. These values are consistent with previously measured rate constants for reactions of hydroperoxides and/or peroxyacids in the condensed phase.

Particle physics instrumentation

International Nuclear Information System (INIS)

Riegler, W.

2011-01-01

This report summarizes a series of three lectures aimed at giving an overview of basic particle detection principles, the interaction of particles with matter, the application of these principles in modern detector systems, as well techniques to read out detector signals in high-rate experiments. (author)

Attributions of Intentions and Fairness Judgments regarding Interracial Peer Encounters

Science.gov (United States)

Killen, Melanie; Kelly, Megan Clark; Richardson, Cameron; Jampol, Noah Simon

2010-01-01

To investigate how adolescents interpret ambiguous actions in hypothetical interracial peer encounters, we conducted a study in which 8th- and 11th-grade students (N = 837) evaluated 4 interracial peer encounters in which the intentions of the protagonist were ambiguous. The sample was evenly divided by gender and included both African American…

Relative feeding rates on free and particle-bound bacteria by freshwater macrozooplankton

International Nuclear Information System (INIS)

Schoenberg, S.A.; Maccubbin, A.E.

1985-01-01

Feeding suspensions of equivalent particle spectra were assembled with either free-living ( 3 H]thymidine. Clearance (ml ind -1 d -1 ) of attached bacteria was 3-29 x that of free bacteria for the cladocerans Acantholeberis, Chydorus, and Eubosmina. Pseudosida and Ceriodaphnia showed weaker discrimination or no selection, indicating a lower size threshold for filtration in these species. Feeding suspensions composed of isolated free bacteria yielded significantly higher or lower estimates of grazing than free bacteria with the full complement of particles, depending on species. Relative clearance (attached:free) tended to increase with body size within a species and varied for different particle environments. Bacteria associated with large particles may increase detrital energy flow to consumers in eutrophic environments

Ultra-high-speed digital in-line holography system applied to particle-laden supersonic underexpanded jet flows

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Buchmann, Nicolas A.; Soria, Julio

2012-01-01

-fluid interactions in these high-speed flows special high performance techniques are required. The present work is an investigation into the applicability of magnified digital in-line holography with ultra-high-speed recording for the study of three-dimensional supersonic particle-laden flows. An optical setup...... × 10mm calibration grid and 120 μm particles on a glass plate. In the case with the calibration grid it is found that accurate determination of the depthwise position is possible. However, when applying the same technique to the particle target, significant problems are encountered....

The Splashback Radius of Halos from Particle Dynamics. II. Dependence on Mass, Accretion Rate, Redshift, and Cosmology

Science.gov (United States)

Diemer, Benedikt; Mansfield, Philip; Kravtsov, Andrey V.; More, Surhud

2017-07-01

The splashback radius R sp, the apocentric radius of particles on their first orbit after falling into a dark matter halo, has recently been suggested to be a physically motivated halo boundary that separates accreting from orbiting material. Using the Sparta code presented in Paper I, we analyze the orbits of billions of particles in cosmological simulations of structure formation and measure R sp for a large sample of halos that span a mass range from dwarf galaxy to massive cluster halos, reach redshift 8, and include WMAP, Planck, and self-similar cosmologies. We analyze the dependence of R sp/R 200m and M sp/M 200m on the mass accretion rate Γ, halo mass, redshift, and cosmology. The scatter in these relations varies between 0.02 and 0.1 dex. While we confirm the known trend that R sp/R 200m decreases with Γ, the relationships turn out to be more complex than previously thought, demonstrating that R sp is an independent definition of the halo boundary that cannot trivially be reconstructed from spherical overdensity definitions. We present fitting functions for R sp/R 200m and M sp/M 200m as a function of accretion rate, peak height, and redshift, achieving an accuracy of 5% or better everywhere in the parameter space explored. We discuss the physical meaning of the distribution of particle apocenters and show that the previously proposed definition of R sp as the radius of the steepest logarithmic density slope encloses roughly three-quarters of the apocenters. Finally, we conclude that no analytical model presented thus far can fully explain our results.

Drug-related police encounters across the globe: How do they compare?

Science.gov (United States)

Hughes, Caitlin E; Barratt, Monica J; Ferris, Jason A; Maier, Larissa J; Winstock, Adam R

2018-06-01

Drug law enforcement subsumes the majority of drug policy expenditure across the globe. Fuelled by knowledge that much of this investment is ineffective or counter-productive there have been increasing calls for cross-national comparisons to identify where policing approaches differ and what types of approaches may be more effective. Yet, to date cross-national comparison of drug law enforcement has proven a methodologically hazardous affair. Using a new drug policing module added to the 2017 Global Drug Survey, this study seeks to provide the first cross-national comparison of the incidence, nature and intensity of illicit drug-related police encounters amongst people who use drugs. The Global Drug Survey was administered in late 2016. Across 26 countries including Australia, Germany, Italy, Mexico, Switzerland, the UK and the USA a total of 45,942 people who had recently used drugs completed the drug policing module. Key variables assessed included the incidence and frequency of drug-related police encounters in the last 12 months that involved: a) being stopped and searched; b) encountering a drug detection dog; c) being given a caution or warning; d) being charged and arrested; and e) paying a bribe. Multi-level models were used to control for pre-existing national differences in drug use prevalence and non-drug specific policing (including the total number of police personnel in each country). Drug-related police encounters were most commonly reported in Italy and Scotland. Conversely, police encounters were most likely to lead to arrest in Norway, Finland and Sweden. The type and locations of encounters further differed across countries, with for example stop and search most reported in Greece and Colombia, and encounters with drug detection dogs most reported in Scotland, Italy, UK and Australia. Multi-level models showed that the incidence of reported policing encounters continued to differ significantly across countries after controlling for pre

Jagiellonian University Radiation Damage in Silicon Particle Detectors in High Luminosity Experiments

CERN Document Server

Oblakowska-Mucha, A

2017-01-01

Radiation damage is nowadays the most serious problem in silicon particle detectors placed in the very harsh radiation environment. This problem will be even more pronounced after the LHC Upgrade because of extremely strong particle fluences never encountered before. In this review, a few aspects of radiation damage in silicon trackers are presented. Among them, the change in the silicon lattice and its influence on the detector performance are discussed. Currently applied solutions and the new ideas for future experiments will be also shown. Most of the results presented in this summary were obtained within the RD50 Collaboration

Effect of the heating rate on the microstructure of in situ Al2O3 particle-reinforced Al matrix composites prepared via displacement reactions in an Al/CuO system

International Nuclear Information System (INIS)

Zhao, Ge; Shi, Zhiming; Ta, Na; Ji, Guojun; Zhang, Ruiying

2015-01-01

Highlights: • The heating rate has a significant effect on the microstructures of composites. • The microstructure is determined by the diffusion rate of O and Cu in the heating stage. • The diffusion of Cu and O atoms is influenced by the heating rate. • With increasing heating rate, the Al 2 O 3 particle distribution becomes more uniformly. • With increasing heating rate, the form of Al 2 Cu changes from network to block-like. - Abstract: In this study, an in situ Al 2 O 3 particle-reinforced Al(Cu) matrix composite was successfully synthesized using a displacement reaction between Al and CuO powders. The powders were mixed at a weight ratio of 4:1 Al to CuO, cold-pressed and holding time at 900 °C for 1 h using varying heating rates. The effects of the heating rate on the microstructures of the composites were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), optical microscopy (MO), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results indicate that all of the composites contain Al, Al 2 O 3 particles and Al 2 Cu phases. Although the heating rate does not significantly affect the phase compositions of the composites, it has a significant effect on their microstructures, most likely because it strongly influences the diffusion rates of the Cu and O atoms. As the heating rate is increased, the Al 2 O 3 particles become more dispersed, and they have a more uniform particle size distribution. Meanwhile, the Al 2 Cu structure transforms from the network (Al + Al 2 Cu) eutectic to the block-like Al 2 Cu phase. The ∼2 μm Al 2 O 3 particles and the block-like Al 2 Cu phase are distributed uniformly in the Al matrix when the sample is placed directly into a 900 °C furnace. This sample has a relative higher Rockwell hardness B (HRB) value of 87

Encounter Group Effects of Soccer Team Performance.

Science.gov (United States)

Magen, Zipora

1980-01-01

Suggests that a positive relationship exists between encounter group experience and the soccer team performance--a conclusion worthy of consideration in further research in the fields of psychology and sociology of sports. (Author)

N-Body simulations of tidal encounters between stellar systems

International Nuclear Information System (INIS)

Rao, P.D.; Ramamani, N.; Alladin, S.M.

1985-10-01

N-Body simulations have been performed to study the tidal effects of a primary stellar system on a secondary stellar system of density close to the Roche density. Two hyperbolic, one parabolic and one elliptic encounters have been simulated. The changes in energy, angular momentum, mass distribution, and shape of the secondary system have been determined in each case. The inner region containing about 40% of the mass was found to be practically unchanged and the mass exterior to the tidal radius was found to escape. The intermediate region showed tidal distension. The thickness of this region decreased as we went from hyperbolic encounters to the elliptic encounter keeping the distance of closest approach constant. The numerical results for the fractional change in energy have been compared with the predictions of the available analytic formulae and the usefulness and limitations of the formulae have been discussed. (author)

Preferrential Concentration of Particles in Protoplanetary Nebula Turbulence

Science.gov (United States)

Hartlep, Thomas; Cuzzi, Jeffrey N.

2015-01-01

Preferential concentration in turbulence is a process that causes inertial particles to cluster in regions of high strain (in-between high vorticity regions), with specifics depending on their stopping time or Stokes number. This process is thought to be of importance in various problems including cloud droplet formation and aerosol transport in the atmosphere, sprays, and also in the formation of asteroids and comets in protoplanetary nebulae. In protoplanetary nebulae, the initial accretion of primitive bodies from freely-floating particles remains a problematic subject. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" [1] in turbulent nebulae. One scenario that can lead directly from independent nebula particulates to large objects, avoiding the problematic m-km size range, involves formation of dense clumps of aerodynamically selected, typically mm-size particles in protoplanetary turbulence. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles generally known as "chondrules" [2]. Thus, while it is arcane, turbulent preferential concentration acting directly on chondrule size particles are worthy of deeper study. Here, we present the statistical determination of particle multiplier distributions from numerical simulations of particle-laden isotopic turbulence, and a cascade model for modeling turbulent concentration at lengthscales and Reynolds numbers not accessible by numerical simulations. We find that the multiplier distributions are scale dependent at the very largest scales but have scale-invariant properties under a particular variable normalization at smaller scales.

Ultraviolet spectrophotometry of Comet Giacobini-Zinner during the ICE encounter. [International Cometary Explorer

Science.gov (United States)

Mcfadden, Lucy A.; Ahearn, Michael F.; Feldman, Paul D.; Boehnhardt, Hermann; Rahe, Juergen; Festou, Michel C.; Brandt, John C.; Maran, Stephen P.; Niedner, Malcolm B.; Smith, Andrew M.

1987-01-01

The IUE's UV spectrophotometer was used to monitor Comet Giacobini-Zinner's H2O production rate from June to October, 1985, in support of the International Cometary Explorer (ICE) mission. Observation results for the spatial and temporal variation and the abundance or upper limits of C, CO, CO(+), CO2(+), CS, H, Mg(+), O, OH, and S, between September 9 and 12, included the time of the ICE encounter: at this time, the H2O production rate obtained was consistent with a number of gas production rates derived indirectly from the ICE experiments. A comparison of the CO2(+) ion abundance with the total electron density measured by the plasma electron and radio science experiments on ICE implies an ion deficiency relative to electrons, so that the satisfaction of charge balance criteria requires the presence of a major ion population not detected by remote sensing.

A comparison between tracer gas and aerosol particles distribution indoors: The impact of ventilation rate, interaction of airflows, and presence of objects

DEFF Research Database (Denmark)

Bivolarova, Mariya Petrova; Ondráček, Jakub; Melikov, Arsen Krikor

2017-01-01

for the exposure to all different-sized test particles. A change in the ventilation rate did not affect the difference in concentration distribution between tracer gas and larger particle sizes. Increasing the room surface area did not influence the similarity in the dispersion of the aerosol particles...... room with mixing ventilation. Three layouts were arranged: an empty room, an office room with an occupant sitting in front of a table, and a single-bed hospital room. The room occupant was simulated by a thermal manikin. Monodisperse particles of three sizes (0.07, 0.7, and 3.5 μm) and nitrous oxide...... tracer gas were generated simultaneously at the same location in the room. The particles and gas concentrations were measured in the bulk room air, in the breathing zone of the manikin, and in the exhaust air. Within the breathing zone of the sitting occupant, the tracer gas emerged as reliable predictor...

Nanoparticle growth by particle-phase chemistry

Directory of Open Access Journals (Sweden)

M. J. Apsokardu

2018-02-01

Full Text Available The ability of particle-phase chemistry to alter the molecular composition and enhance the growth rate of nanoparticles in the 2–100 nm diameter range is investigated through the use of a kinetic growth model. The molecular components included are sulfuric acid, ammonia, water, a non-volatile organic compound, and a semi-volatile organic compound. Molecular composition and growth rate are compared for particles that grow by partitioning alone vs. those that grow by a combination of partitioning and an accretion reaction in the particle phase between two organic molecules. Particle-phase chemistry causes a change in molecular composition that is particle diameter dependent, and when the reaction involves semi-volatile molecules, the particles grow faster than by partitioning alone. These effects are most pronounced for particles larger than about 20 nm in diameter. The modeling results provide a fundamental basis for understanding recent experimental measurements of the molecular composition of secondary organic aerosol showing that accretion reaction product formation increases linearly with increasing aerosol volume-to-surface-area. They also allow initial estimates of the reaction rate constants for these systems. For secondary aerosol produced by either OH oxidation of the cyclic dimethylsiloxane (D5 or ozonolysis of β-pinene, oligomerization rate constants on the order of 10−3 to 10−1 M−1 s−1 are needed to explain the experimental results. These values are consistent with previously measured rate constants for reactions of hydroperoxides and/or peroxyacids in the condensed phase.

Individual dose and exposure of Italian children to ultrafine particles.

Science.gov (United States)

Buonanno, G; Marini, S; Morawska, L; Fuoco, F C

2012-11-01

Time-activity patterns and the airborne pollutant concentrations encountered by children each day are an important determinant of individual exposure to airborne particles. This is demonstrated in this work by using hand-held devices to measure the real-time individual exposure of more than 100 children aged 8-11 years to particle number concentrations and average particle diameter, as well as alveolar and tracheobronchial deposited surface area concentration. A GPS-logger and activity diaries were also used to give explanation to the measurement results. Children were divided in three sample groups: two groups comprised of urban schools (school time from 8:30 am to 1:30 pm) with lunch and dinner at home, and the third group of a rural school with only dinner at home. The mean individual exposure to particle number concentration was found to differ between the three groups, ranging from 6.2 × 10(4)part.cm(-3) for children attending one urban school to 1.6 × 10(4)part.cm(-3) for the rural school. The corresponding daily alveolar deposited surface area dose varied from about 1.7 × 10(3)mm(2) for urban schools to 6.0 × 10(2)mm(2) for the rural school. For all of the children monitored, the lowest particle number concentrations are found during sleeping time and the highest were found during eating time. With regard to alveolar deposited surface area dose, a child's home was the major contributor (about 70%), with school contributing about 17% for urban schools and 27% for the rural school. An important contribution arises from the cooking/eating time spent at home, which accounted for approximately 20% of overall exposure, corresponding to more than 200 mm(2). These activities represent the highest dose received per time unit, with very high values also encountered by children with a fireplace at home, as well as those that spend considerable time stuck in traffic jams. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

Science.gov (United States)

Cropper, S L; Kocaoglu-Vurma, N A; Tharp, B W; Harper, W J

2013-06-01

The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules. © 2013 Institute of Food Technologists®

Rethinking social identity theory in international encounters:

DEFF Research Database (Denmark)

Lauring, Jakob

2008-01-01

In a globalized business environment, interaction across linguistic boundaries is becoming a normal part of everyday life. In these encounters language differences may affect the formation of social identities among organization members. While studies based on Social Identity Theory perceive...... the link between identity and language to be linear, this article takes a different approach. By drawing on anthropological theories on ethnic identity it is argued that the relation between language and social identity is negotiated in interaction. In the empirical analysis the article focuses...... on the encounter between expatriates and local employees of a Danish subsidiary in England. The findings show that identity making may be actualized by competition for resources and recognition. This can be done by investing certain objects such as the symbolic application of language with certain identifications...

Hotspots on Io During the Ganymede 2 Encounter

Science.gov (United States)

1996-01-01

The Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft imaged Io at high spectral resolution at a range of 439,000 km (275,000 miles) during the G2 encounter on 6 September 1996. This image shows, on the right, Io as seen by NIMS, centered on 150 W longitude. The image on the left shows the same view point from Voyager data (from the encounters in 1979 and 1980). The NIMS image can be compared to the NIMS hotspot image from the G1 orbit (June 1996) to monitor changes on Io. The most dramatic feature of the G2 image is the hotspot at Malik Patera. Preliminary analysis of the data yields a temperature of at least 1000 K (727 C) for this hotspot, an increase of more than 300 K from the G1 encounter. In the overlap area of the G1 and G2 images all the hotspots seen during the G1 encounter are also seen in the G2 image. Other hotspots were seen, including one at the Pele plume origin site. This image is at the 4 micron band to best view the Malik hotspot. Most of the other hotspots are best seen at longer wavelengths. NIMS is continuing to observe Io to monitor volcanic activity throughout the Galileo mission.The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

Charged particle discrimination with silicon surface barrier detectors

International Nuclear Information System (INIS)

Coote, G.E.; Pithie, J.; Vickridge, I.C.

1996-01-01

The application for materials analysis of nuclear reactions that give rise to charged particles is a powerful surface analytical and concentration depth profiling technique. Spectra of charged particles, with energies in the range 0.1 to 15 MeV, emitted from materials irradiated with beams of light nuclei such as deuterons are measured with silicon surface barrier detectors. The spectra from multi-elemental materials typically encountered in materials research are usually composed of an overlapping superposition of proton, alpha, and other charged particle spectra. Interpretation of such complex spectra would be simplified if a means were available to electronically discriminate between the detector response to the different kinds of charged particle. We have investigated two methods of discriminating between different types of charged particles. The fast charge pulses from a surface barrier detector have different shapes, depending on the spatial distribution of energy deposition of the incident particle. Fast digitisation of the pulses, followed by digital signal processing provides one avenue for discrimination. A second approach is to use a thin transmission detector in front of a thick detector as a detector telescope. For a given incident energy, different types of charged particles will lose different amounts of energy in the thin detector, providing an alternative means of discrimination. We show that both approaches can provide significant simplification in the interpretation of charged particle spectra in practical situations, and suggest that silicon surface barrier detectors having graded electronic properties could provide improved discrimination compared to the current generation of detectors having homogeneous electronic properties. (author).12 refs., 2 tabs., 28 figs

Pipeline negotiations as a challenging setting for organised cultural encounters

DEFF Research Database (Denmark)

Guerrieri, Valeria

has linked together countries, cultures, identities, ultimately challenging, reorganizing and renegotiating them. Starting from these premises, the following paper intends to show how Canadian Mackenzie Valley represents a unique contact zone for the development of cultural encounters, where different...... with often competing interests and positions - the practice of public hearings can be approached as a form of organized cultural encounter, whose “implied purposes” are to deal with more or less substantial cultural differences and to provide a wider cultural understanding of each different position. Through......Within the context of resource extraction, cultural encounters have been historically performed in the way of more or less antagonistic social interactions, ranging from outright domination to more empowerment-oriented relations. Throughout the last decades, the building of pipelines in particular...

Moral Relations in Encounters with Nature

Science.gov (United States)

Andersson, Karin; Öhman, Johan

2015-01-01

The overall aim of this article is to develop in-depth knowledge about the connection between outdoor experiences and moral attitudes towards nature. The study focuses on processes in which moral relations are at stake in encounters between students and nature. The purpose is to identify such events, describe their specific circumstances and…

Encountering spiritual tourism in Kathmandu

OpenAIRE

Børø, Nora

2015-01-01

Spiritual tourism as a phenomenon is increasing worldwide. Many have conducted research looking at the intersection between religion and tourism, but few have focused on the host community within these encounters. Many Western tourists arrive in Kathmandu to go on retreats', and to participate in yoga and meditation classes. The majority of these are particularly interested in various forms of Buddhist practice and traditions. In this thesis I have studied how N...

Tracking and imaging elementary particles

International Nuclear Information System (INIS)

Breuker, H.; Drevermann, H.; Grab, C.; Rademakers, A.A.; Stone, H.

1991-01-01

The Large Electron-Positron (LEP) Collider is one of the most powerful particle accelerators ever built. It smashes electrons into their antimatter counterparts, positrons, releasing as much as 100 billion electron volts of energy within each of four enormous detectors. Each burst of energy generates a spray of hundreds of elementary particles that are monitored by hundreds of thousands of sensors. In less than a second, an electronic system must sort through the data from some 50,000 electron-positron encounters, searching for just one or two head-on collisions that might lead to discoveries about the fundamental forces and the elementary particles of nature. When the electronic systems identify such a promising event, a picture of the data must be transmitted to the most ingenious image processor ever created. The device is the human brain. Computers cannot match the brain's capacity to recognize complicated patterns in the data collected by the LEP detectors. The work of understanding subnuclear events begins therefore through the visualization of objects that are trillions of times smaller than the eye can see and that move millions of times faster than the eye can follow. During the past decade, the authors and their colleagues at the European laboratory for particle physics (CERN) have attempted to design the perfect interface between the minds of physicists and the barrage of electronic signals from the LEP detectors. Using sophisticated computers, they translate raw data - 500,000 numbers from each event - into clear, meaningful images. With shapes, curves and colors, they represent the trajectories of particles, their type, their energy and many other properties

Variation of Particle Control with Changes in Divertor Geometry

International Nuclear Information System (INIS)

Petrie, T W; Allen, S L; Brooks, N H; Fenstermacher, M E; Ferron, J R; Greenfield, C M; Groth, M; Hyatt, A W; Leonard, A W; Luce, T C; Mahdavi, M A; Murakami, M; Porter, G D; Rensink, M E; Schaffer, M J; Wade, M R; Watkins, J G; West, W P; Wolf, N S

2004-01-01

Recent experiments on DIII-D point to the importance of two factors in determining how effectively the deuterium particle inventory in a tokamak plasma can be controlled through pumping at the divertor target(s): (1) the divertor magnetic balance, i.e., the degree to which the divertor topology is single-null (SN) or double-null (DN), and (2) the direction of the of Bx(divergent)B ion drift with respect to the X-point(s). Changes in divertor magnetic balance near the DN shape have a much stronger effect on the particle exhaust rate at the inner divertor target(s) than on the particle exhaust rate at the outer divertor target(s). The particle exhaust rate for the DN shape is strongest at the outer strike point opposite the Bx(divergent)B ion particle drift direction. Our data suggests that the presence of Bx(divergent)B and ExB ion particle drifts in the scrapeoff layer (SOL) and divertors play an important role in the particle exhaust rates of DN and near-DN plasmas. Particle exhaust rates are shown to depend strongly on the edge (pedestal) density n e,PED . In the lower range of densities considered in this study, i.e., n e,PED / n GREENWALD <0.4, particle exhaust rates are also found to be approximately proportional to the deuterium recycling intensity in front of the respective plenum entrance. Our results are shown to have implications for particle control in ITER and other future tokamaks

Variation of particle control with changes in divertor geometry

International Nuclear Information System (INIS)

Petrie, T.W.; Allen, S.L.; Brooks, N.H.; Fenstermacher, M.E.; Groth, M.; Porter, G.D.; Rensink, M.E.; Wolf, N.S.; Ferron, J.R.; Greenfield, C.M.; Hyatt, A.W.; Leonard, A.W.; Luce, T.C.; Mahdavi, M.A.; Schaffer, M.J.; West, W.P.; Murakami, M.; Wade, M.R.; Watkins, J.G.

2005-01-01

Recent experiments on DIII-D point to the importance of two factors in determining how effectively the deuterium particle inventory in a tokamak plasma can be controlled through pumping at the divertor target(s): (1) the divertor magnetic balance, i.e., the degree to which the divertor topology is single-null (SN) or double-null (DN), and (2) the direction of the of Bx∇B ion drift with respect to the X-point(s). Changes in divertor magnetic balance near the DN shape have a much stronger effect on the particle exhaust rate at the inner divertor target(s) than on the particle exhaust rate at the outer divertor target(s). The particle exhaust rate for the DN shape is strongest at the outer strike point opposite the Bx∇B ion particle drift direction. Our data suggests that the presence of Bx∇B and ExB ion particle drifts in the scrapeoff layer (SOL) and divertors play an important role in the particle exhaust rates of DN and near-DN plasmas. Particle exhaust rates are shown to depend strongly on the edge (pedestal) density n e,PED . In the lower range of densities considered in this study, i.e., n e,PED /n GREENWALD <0.4, particle exhaust rates are also found to be approximately proportional to the deuterium recycling intensity in front of the respective plenum entrance. Our results are shown to have implications for particle control in ITER and other future tokamaks. (author)

Particle-associated flagellates: swimming patterns, colonization rates, and grazing on attached bacteria

DEFF Research Database (Denmark)

Kiørboe, Thomas; Grossart, H.P.; Ploug, H.

2004-01-01

Some pelagic flagellates colonize particles, such as marine snow, where they graze on bacteria and thus impact the dynamics of the attached microbial communities. Particle colonization is governed by motility. Swimming patterns of 2 particle-associated flagellates, Bodo designis and Spumella sp......., are very different, the former swimming slowly in an erratic, random pattern, and the latter faster and along smooth helixes of variable amplitude and frequency. At spatial scales exceeding ca. 50 mum, the motility of B. designis can be described as a random walk and modeled as diffusion. Spumella sp...

Domestic Violence Encountered among Kurdish Women

Science.gov (United States)

Ali, Sirwan Kamil

2015-01-01

Background and objective; There is growing recognition that violence against women has a large public health impact, in addition to being a gross violation of women's human rights. The study's aims were: To show the types of domestic abuse encountered by Kurdish women, and study the relationship between them. Methods; The study conducted in the…

Encounters on a Shape-changing Bench

DEFF Research Database (Denmark)

Kinch, Sofie; Grönvall, Erik; Petersen, Marianne Graves

2014-01-01

; a concert hall, an airport and a shopping mall. We gathered insights from more than 120 people, as they unexpectedly encountered the shape changing capabilities of the bench. By taking the user tests out of the lab and into the wild, we explored the influence of context on the users experience of a shape...

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

International Nuclear Information System (INIS)

Lee, E. Y.; Kim, J. H.; Jeong, S. I.; Lee, S. H.; Eum, G. W.

2015-01-01

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

Energy Technology Data Exchange (ETDEWEB)

Lee, E. Y.; Kim, J. H.; Jeong, S. I. [Andong National University, Andong (Korea, Republic of); Lee, S. H.; Eum, G. W. [Corporate R and D Institute Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

2015-04-15

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

THE INFLUENCE OF BUILDING FEATURES ON AIR EXCHANGE RATE AND PARTICLE PENETRATION

Science.gov (United States)

The paper discusses some measured values of particle penetration into an unoccupied research house under a variety of conditions. (NOTE: Exposure to fine particles of outdoor origin continues to receive increased attention. Since people spend up to 90% of their time indoors, the ...

NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A<16

International Nuclear Information System (INIS)

Xu, Y.; Takahashi, K.; Goriely, S.; Arnould, M.; Ohta, M.; Utsunomiya, H.

2013-01-01

An update of the NACRE compilation [3] is presented. This new compilation, referred to as NACRE II, reports thermonuclear reaction rates for 34 charged-particle induced, two-body exoergic reactions on nuclides with mass number A 6 ≲T⩽10 10 K range. Along with the ‘adopted’ rates, their low and high limits are provided. The new rates are available in electronic form as part of the Brussels Library (BRUSLIB) of nuclear data. The NACRE II rates also supersede the previous NACRE rates in the Nuclear Network Generator (NETGEN) for astrophysics. [ (http://www.astro.ulb.ac.be/databases.html)

Flight-management strategies for escape from microburst encounters. M.S. Thesis - George Washington Univ.

Science.gov (United States)

Hinton, David A.

1988-01-01

An effort is underway by NASA, FAA, and industry to reduce the threat of convective microburst wind shear phenomena to aircraft. The goal is to develop and test a candidate set of strategies for recovery from inadvertent microburst encounters during takeoff. Candidate strategies were developed and evaluated using a fast-time simulation consisting of a simple point-mass performance model of a transport-category airplane and an analytical microburst model. The results indicate that the recovery strategy characteristics that best utilize available airplane energy include an initial reduction in pitch attitude to reduce the climb rate, followed by an increase in pitch up to the stick shaker angle of attack. The stick shaker angle of attack should be reached just as the airplane is exiting the microburst. The shallowest angle of climb necessary for obstacle clearance should be used. If the altitude is higher than necessary, an intentional descent to reduce the airspeed deceleration should be used. Of the strategies tested, two flight-path-angle based strategies had the highest recovery altitudes and the least sensitivity to variations in the encounter scenarios.

Particle production by neutrinos

International Nuclear Information System (INIS)

Schreiner, P.

1979-01-01

A review is given of particle production by neutrinos in charged-current inclusive and exclusive channels. The production rates for various particles in neutrino-nucleon interactions at a beam energy of 25 GeV are compared. The mesons are, of course, dominated by pion production. The p 0 (760) rate is an order of magnitude smaller. Strange and charm pseudoscalar mesons are a further factor of two down in rate. The strange vector mesons are suppressed by more than an order of magnitude relative to K 0 production; however, the charmed D* + (2010) is only a factor of two smaller in rate than the D 0 (1860). With regards to the baryons, most of them are, of course, nucleons. The Λ 0 and Y*(1385) rates are down by one and two orders of magnitudes, respectively. The lower limit on the charmed Σ/sub c/ ++ baryon rate is similar to the Y*(1385) rate. Finally, the quasielastic and one-pion production exclusive channels have about the same cross section as that of the D* + ; associated production of strange particles in the νn → μ - K + Λ channel and the ΔS = +ΔΩ process νp → μ - pK + are down by factors of five and twenty, respectively, compared to the quasielastic cross section

Self. Propagating | a strategy of encounter |

Directory of Open Access Journals (Sweden)

Gabrielle Lorraine Fletcher

2015-11-01

Full Text Available This piece mobilises both creative non-fiction and ficto-criticism to expose the necessary terrains of narrativity as a Country of the Lived,  making visible the redactive cartography of the PhD in telling Indigenous selfhood, and mobilising an argument for authentic encounter under the comfortable maps of form.

Well, hydrology, and geochemistry problems encountered in ATES systems and their solutions

International Nuclear Information System (INIS)

Jenne, E.A.; Andersson, O.; Willemsen, A.

1992-08-01

In aquifer thermal energy storage (ATES) systems, wells provide the interface between the energy storage and use. Efficient operational wells are, therefore, essential for the system to run at maximum (design) efficiency. Adequate test drilling to accurately predict aquifer properties is essential in the design phase; proper construction and development are crucial; and proper monitoring of performance is necessary to identify the early stages of clogging and to evaluate the adequacy of well rehabilitation. Problems related to hydrology, well, and aquifer properties include: loss of permeability resulting from gas exsolution, chemical precipitation, and dispersion and movement of fine-grained particles; loss of recoverable heat caused by excessive regional ground-water gradient, hydrodynamic mixing of injected and native ground water, buoyancy flow and heat conduction through the cap and base of the storage zone; leakage up along the well casing; and ''fracturing'' of a shallow upper aquiclude as a result of an injection pressure greater than the hydrostatic pressure on the aquiclude. The predominant geochemical problems encountered are precipitation of carbonates in some areas and iron plus manganese oxides in others. These precipitation problems can be anticipated, and thus avoided, via geochemical calculations. The likelihood of iron carbonate precipitation is less certain because of the lack of adequate research. Corrosion is a frequent problem. Most of the hydrochemically related clogging and corrosion problems that have been encountered in ATES systems can be predicted and avoided by appropriate design, construction, and operation of new ATF-S systems, assuming that appropriate hydrologic and geochemical modeling is carried out in advance. It is prudent to carefully consider the need for water treatment and to anticipate that there will be some increase in injection pressure and decrease of specific capacity over time

High-Strain-Rate Material Behavior and Adiabatic Material Instability in Impact of Micron-Scale Al-6061 Particles

Science.gov (United States)

Chen, Qiyong; Alizadeh, Arash; Xie, Wanting; Wang, Xuemei; Champagne, Victor; Gouldstone, Andrew; Lee, Jae-Hwang; Müftü, Sinan

2018-04-01

Impact of spherical particles onto a flat sapphire surface was investigated in 50-950 m/s impact speed range experimentally and theoretically. Material parameters of the bilinear Johnson-Cook model were determined based on comparison of deformed particle shapes from experiment and simulation. Effects of high-strain-rate plastic flow, heat generation due to plasticity, material damage, interfacial friction and heat transfer were modeled. Four distinct regions were identified inside the particle by analyzing temporal variation of material flow. A relatively small volume of material near the impact zone becomes unstable due to plasticity-induced heating, accompanied by severe drop in the flow stress for impact velocity that exceeds 500 m/s. Outside of this region, flow stress is reduced due to temperature effects without the instability. Load carrying capacity of the material degrades and the material expands horizontally leading to jetting. The increase in overall plastic and frictional dissipation with impact velocity was found to be inherently lower than the increase in the kinetic energy at high speeds, leading to the instability. This work introduces a novel method to characterize HSR (109 s-1) material properties and also explains coupling between HSR material behavior and mechanics that lead to extreme deformation.

BodyHeat Encounter: Performing Technology in Pedagogical Spaces of Surveillance/Intimacy

Science.gov (United States)

Fels, Lynn; Ricketts, Kathryn

2015-01-01

What occurs when videographer and performer encounter each other through the lens of a camera? This collaborative performative inquiry focuses on embodiment and emergent narrative as realized through an encounter between technology and the visceral body--a relational body that smells, touches, sees, hears and feels the emergent world through…

Particle transport in 3He-rich events: wave-particle interactions and particle anisotropy measurements

Directory of Open Access Journals (Sweden)

B. T. Tsurutani

2002-04-01

Full Text Available Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985 of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading

Particle transport in 3He-rich events: wave-particle interactions and particle anisotropy measurements

Directory of Open Access Journals (Sweden)

T. Hada

Full Text Available Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985 of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading

Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline.

Science.gov (United States)

Short, Daniel Z; Vu, Diep; Durbin, Thomas D; Karavalakis, Georgios; Asa-Awuku, Akua

2015-09-01

Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on particulate matter (PM) such as black carbon (BC) and water-soluble and insoluble particle compositions are not well-defined. This study tests seven 2012 model year vehicles, which include one port fuel injection (PFI) configured hybrid vehicle, one PFI vehicle, and six gasoline direct injection (GDI) vehicles. Each vehicle was driven on the Unified transient testing cycle (UC) using four different fuels. Three fuels had a constant octane rating of 87 with varied aromatic concentrations at 15%, 25%, and 35%. A fourth fuel with higher octane rating, 91, contained 35% aromatics. BC, PM mass, surface tension, and water-soluble organic mass (WSOM) fractions were measured. The water-insoluble mass (WIM) fraction of the vehicle emissions was estimated. Increasing fuel aromatic content increases BC emission factors (EFs) of transient cycles. BC concentrations were higher for the GDI vehicles than the PFI and hybrid vehicles, suggesting a potential climate impact for increased GDI vehicle production. Vehicle steady-state testing showed that the hygroscopicity of PM emissions at high speeds (70 mph; κ > 1) are much larger than emissions at low speeds (30 mph; κ < 0.1). Iso-paraffin content in the fuels was correlated to the decrease in WSOM emissions. Both aromatic content and vehicle speed increase the amount of hygroscopic material found in particle emissions.

Optimized synthesis of nano-sized LiFePO4/C particles with excellent rate capability for lithium ion batteries

International Nuclear Information System (INIS)

Liu, Houbin; Miao, Cui; Meng, Yan; He, Yan-Bing; Xu, Qiang; Zhang, Xinhe; Tang, Zhiyuan

2014-01-01

Olivine-type LiFePO 4 /C composite with excellent rate capability and cycling stability is synthesized by an optimized ethylene glycol assisted solution-phase method. In an attempt to improve the electrochemical performance, the size of LiFePO 4 /C particle is reduced by optimizing the reaction time and temperature. The results show that the LiFePO 4 /C synthesized at 130 °C for 5 h consists of well-distributed nano-particles of size about 50 nm in diameter and 100 nm in length, which is uniformly coated with a carbon layer about 3.0 nm in thickness. The material synthesized at 130 °C exhibits the least charge-transfer resistance than the LiFePO 4 /C synthesized at 120 and 140 °C. The specific capacity of optimized LiFePO 4 /C at discharge rate of 0.1 C can reach to 166.5 mAhg −1 , nearly to the theoretical capacity. Even at high rate of 5, 10, 20 and 30 C, the specific capacities of 132.3, 120.4, 97.3 and 66.6 mAhg −1 are achieved, respectively, with no significant capacity fading after 100 cycles. This is a promising method used in industrialization to synthesize LiFePO 4 /C composite with excellent performance

Use of new computer technologies in elementary particle physics

International Nuclear Information System (INIS)

Gaines, I.; Nash, T.

1987-01-01

Elementary particle physics and computers have progressed together for as long as anyone can remember. The symbiosis is surprising considering the dissimilar objectives of these fields, but physics understanding cannot be had simply by detecting the passage of particles. It requires a selection of interesting events and their analysis in comparison with quantitative theoretical predictions. The extraordinary reach made by experimentalists into realms always further removed from everyday observation frequently encountered technology constraints. Pushing away such barriers has been an essential activity of the physicist since long before Rossi developed the first practical electronic AND gates as coincidence circuits in 1930. This article describes the latest episode of this history, the development of new computer technologies to meet the various and increasing appetite for computing of experimental (and theoretical) high energy physics

Acquisition of an Underway CTD System for the Flow Encountering Abrupt Topography DRI

Science.gov (United States)

2015-09-30

Acquisition of an Underway CTD System for the Flow Encountering Abrupt Topography DRI T. M. Shaun Johnston Scripps Institution of Oceanography...westward flow in the North Equatorial Current (NEC) encounters tall, steep, submarine topography and islands. During the Flow Encountering Abrupt... Topography (FLEAT) DRI, investigators will determine: • Whether appreciable energy/momentum is lost from the large-scale NEC flow to smaller scales and

Satisfaction with the outpatient encounter - A comparison of patients' and physicians' views

NARCIS (Netherlands)

Zandbelt, Linda C.; Smets, Ellen M. A.; Oort, Frans J.; Godfried, Mieke H.; de Haes, Hanneke C. J. M.

2004-01-01

OBJECTIVE: To compare patients' and physicians' visit-specific satisfaction in an internal medicine outpatient setting, and to explain their respective views. DESIGN: Patients' and physicians' background characteristics were assessed prior to outpatient encounters. Immediately after the encounter,

Plasma and energetic particle structure of a collisionless quasi-parallel shock

Science.gov (United States)

Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Smith, E. J.; Wenzel, K. P.; Reinhard, R.; Sanderson, T. R.; Feldman, W. C.; Parks, G. K.

1983-01-01

The quasi-parallel interplanetary shock of November 11-12, 1978 from both the collisionless shock and energetic particle points of view were studied using measurements of the interplanetary magnetic and electric fields, solar wind electrons, plasma and MHD waves, and intermediate and high energy ions obtained on ISEE-1, -2, and -3. The interplanetary environment through which the shock was propagating when it encountered the three spacecraft was characterized; the observations of this shock are documented and current theories of quasi-parallel shock structure and particle acceleration are tested. These observations tend to confirm present self consistent theories of first order Fermi acceleration by shocks and of collisionless shock dissipation involving firehouse instability.

Users’ encounter with normative discourses on Facebook

DEFF Research Database (Denmark)

Mathieu, David

2016-01-01

This study asks whether users’ encounter with normative discourses of lifestyle, consumption, and health on social media such as Facebook gives rise to agency. The theoretical framework draws on reception analysis, for its implied, but central interest in agency that lies at the intersection...... of texts and audiences. Based on a critique of the “participatory paradigm,” a paradigm that situates the locus of agency in the structural opposition between senders and users, in the norms of rational deliberation or in the figure of the activist, gaps are identified which can be filled by adopting...... an explicit focus on the socio-cultural practices of ordinary audiences in their encounters with media discourses. The study investigates user agency on seven Facebook groups and pages with the help of a three-pronged perspective based on the notion of the media–audience relationship as (1) power structure...

Mobbing behaviors encountered by nurse teaching staff.

Science.gov (United States)

Yildirim, Dilek; Yildirim, Aytolan; Timucin, Arzu

2007-07-01

The term 'mobbing' is defined as antagonistic behaviors with unethical communication directed systematically at one individual by one or more individuals in the workplace. This cross-sectional and descriptive study was conducted for the purpose of determining the mobbing behaviors encountered by nursing school teaching staff in Turkey, its effect on them, and their responses to them. A large percentage (91%) of the nursing school employees who participated in this study reported that they had encountered mobbing behaviors in the institution where they work and 17% that they had been directly exposed to mobbing in the workplace. The academic staff who had been exposed to mobbing behaviors experienced various physiological, emotional and social reactions. They frequently 'worked harder and [were] more organized and worked very carefully to avoid criticism' to escape from mobbing. In addition, 9% of the participants stated that they 'thought about suicide occasionally'.

Particle drag history in a subcritical post-shock flow - data analysis method and uncertainty

Science.gov (United States)

Ding, Liuyang; Bordoloi, Ankur; Adrian, Ronald; Prestridge, Kathy; Arizona State University Team; Los Alamos National Laboratory Team

2017-11-01

A novel data analysis method for measuring particle drag in an 8-pulse particle tracking velocimetry-accelerometry (PTVA) experiment is described. We represented the particle drag history, CD(t) , using polynomials up to the third order. An analytical model for continuous particle position history was derived by integrating an equation relating CD(t) with particle velocity and acceleration. The coefficients of CD(t) were then calculated by fitting the position history model to eight measured particle locations in the sense of least squares. A preliminary test with experimental data showed that the new method yielded physically more reasonable particle velocity and acceleration history compared to conventionally adopted polynomial fitting. To fully assess and optimize the performance of the new method, we performed a PTVA simulation by assuming a ground truth of particle motion based on an ensemble of experimental data. The results indicated a significant reduction in the RMS error of CD. We also found that for particle locating noise between 0.1 and 3 pixels, a range encountered in our experiment, the lowest RMS error was achieved by using the quadratic CD(t) model. Furthermore, we will also discuss the optimization of the pulse timing configuration.

Feminist Encounters with Evolutionary Psychology

OpenAIRE

O'Neill, Rachel

2016-01-01

This Section of Australian Feminist Studies is the product of an event that took place at King’s College London in January 2015, hosted as part of the UK-based ‘Critical Sexology’ seminar series. Participants at this event – feminist scholars working across the fields of lin- guistics, cultural studies, sociology, and psychology – were invited to reflect on their encounters with evolutionary psychology (EP). As the event organiser, I was interested to prompt a discussion about how EP shapes t...

Estimating migratory connectivity of birds when re-encounter probabilities are heterogeneous

Science.gov (United States)

Cohen, Emily B.; Hostelter, Jeffrey A.; Royle, J. Andrew; Marra, Peter P.

2014-01-01

Understanding the biology and conducting effective conservation of migratory species requires an understanding of migratory connectivity – the geographic linkages of populations between stages of the annual cycle. Unfortunately, for most species, we are lacking such information. The North American Bird Banding Laboratory (BBL) houses an extensive database of marking, recaptures and recoveries, and such data could provide migratory connectivity information for many species. To date, however, few species have been analyzed for migratory connectivity largely because heterogeneous re-encounter probabilities make interpretation problematic. We accounted for regional variation in re-encounter probabilities by borrowing information across species and by using effort covariates on recapture and recovery probabilities in a multistate capture–recapture and recovery model. The effort covariates were derived from recaptures and recoveries of species within the same regions. We estimated the migratory connectivity for three tern species breeding in North America and over-wintering in the tropics, common (Sterna hirundo), roseate (Sterna dougallii), and Caspian terns (Hydroprogne caspia). For western breeding terns, model-derived estimates of migratory connectivity differed considerably from those derived directly from the proportions of re-encounters. Conversely, for eastern breeding terns, estimates were merely refined by the inclusion of re-encounter probabilities. In general, eastern breeding terns were strongly connected to eastern South America, and western breeding terns were strongly linked to the more western parts of the nonbreeding range under both models. Through simulation, we found this approach is likely useful for many species in the BBL database, although precision improved with higher re-encounter probabilities and stronger migratory connectivity. We describe an approach to deal with the inherent biases in BBL banding and re-encounter data to demonstrate

A review of methods for sampling large airborne particles and associated radioactivity

International Nuclear Information System (INIS)

Garland, J.A.; Nicholson, K.W.

1990-01-01

Radioactive particles, tens of μm or more in diameter, are unlikely to be emitted directly from nuclear facilities with exhaust gas cleansing systems, but may arise in the case of an accident or where resuspension from contaminated surfaces is significant. Such particles may dominate deposition and, according to some workers, may contribute to inhalation doses. Quantitative sampling of large airborne particles is difficult because of their inertia and large sedimentation velocities. The literature describes conditions for unbiased sampling and the magnitude of sampling errors for idealised sampling inlets in steady winds. However, few air samplers for outdoor use have been assessed for adequacy of sampling. Many size selective sampling methods are found in the literature but few are suitable at the low concentrations that are often encountered in the environment. A number of approaches for unbiased sampling of large particles have been found in the literature. Some are identified as meriting further study, for application in the measurement of airborne radioactivity. (author)

The Production of FRW Universe and Decay to Particles in Multiverse

Science.gov (United States)

Ghaffary, Tooraj

2017-09-01

In this study, first, it will be shown that as the Hubble parameter, " H", increases the production cross section for closed and flat Universes increases rapidly at smaller values of " H" and becomes constant for higher values of " H". However in the case of open Universe, the production cross section has been encountered a singularity. Before this singularity, as the H parameter increases, the cross section increases, for smaller H, ( H < 2.5), exhibits a turn-over at moderate values of H, (2.5 < H < 3.5), decreases for larger amount of H After that and for a special value of H, the cross section has been encountered with a singularity. Although the cross section cannot be defined at this singularity but before and after this point, it is certainly equal to zero. After this singularity, the cross section increases rapidly, when H increases. It is shown that if the production cross section of Universe happens before this singularity, it can't achieve to higher values of Hubble parameter after singularity. More over if the production cross section of Universe situates after the singularity, it won't get access to values of Hubble parameter less than the singularity. After that the thermal distribution for particles inside the FRW Universes are obtained. It is found that a large amount of particles are produced near apparent horizon due to their variety in their energy and their probabilities. Finally, comparing the particle production cross sections for flat, closed and open Universes, it is concluded that as the value of k increases, the cross section decreases.

Statistics of particle time-temperature histories.

Energy Technology Data Exchange (ETDEWEB)

Hewson, John C.; Lignell, David O.; Sun, Guangyuan

2014-10-01

Particles in non - isothermal turbulent flow are subject to a stochastic environment tha t produces a distribution of particle time - temperature histories. This distribution is a function of the dispersion of the non - isothermal (continuous) gas phase and the distribution of particles relative to that gas phase. In this work we extend the one - dimensional turbulence (ODT) model to predict the joint dispersion of a dispersed particle phase and a continuous phase. The ODT model predicts the turbulent evolution of continuous scalar fields with a model for the cascade of fluctuations to smaller sc ales (the 'triplet map') at a rate that is a function of the fully resolved one - dimens ional velocity field . Stochastic triplet maps also drive Lagrangian particle dispersion with finite Stokes number s including inertial and eddy trajectory - crossing effect s included. Two distinct approaches to this coupling between triplet maps and particle dispersion are developed and implemented along with a hybrid approach. An 'instantaneous' particle displacement model matches the tracer particle limit and provide s an accurate description of particle dispersion. A 'continuous' particle displacement m odel translates triplet maps into a continuous velocity field to which particles respond. Particles can alter the turbulence, and modifications to the stochastic rate expr ession are developed for two - way coupling between particles and the continuous phase. Each aspect of model development is evaluated in canonical flows (homogeneous turbulence, free - shear flows and wall - bounded flows) for which quality measurements are ava ilable. ODT simulations of non - isothermal flows provide statistics for particle heating. These simulations show the significance of accurately predicting the joint statistics of particle and fluid dispersion . Inhomogeneous turbulence coupled with the in fluence of the mean flow fields on particles of varying properties

Evaluation of a blender for HTGR fuel particles

International Nuclear Information System (INIS)

Johnson, D.R.

1977-03-01

An experimental blender for mixing HTGR fuel particles prior to molding the particles into fuel rods was evaluated. The blender consists of a conical chamber with an air inlet in the bottom. A pneumatically operated valve provides for discharge of the particles out of the bottom of the cone. The particles are mixed by periodically levitating with pulses of air. The blender has provision for regulating the air flow rate and the number and duration of the air flow pulses. The performance of the blender was governed by the particle blend being mixed, the air flow rate, and the pulse time. Adequately blended fuel rods can be made, if the air flow rate and pulse time are carefully controlled for each fuel rod composition

Rate laws of the self-induced aggregation kinetics of Brownian particles

Science.gov (United States)

Mondal, Shrabani; Sen, Monoj Kumar; Baura, Alendu; Bag, Bidhan Chandra

2016-03-01

In this paper we have studied the self induced aggregation kinetics of Brownian particles in the presence of both multiplicative and additive noises. In addition to the drift due to the self aggregation process, the environment may induce a drift term in the presence of a multiplicative noise. Then there would be an interplay between the two drift terms. It may account qualitatively the appearance of the different laws of aggregation process. At low strength of white multiplicative noise, the cluster number decreases as a Gaussian function of time. If the noise strength becomes appreciably large then the variation of cluster number with time is fitted well by the mono exponentially decaying function of time. For additive noise driven case, the decrease of cluster number can be described by the power law. But in case of multiplicative colored driven process, cluster number decays multi exponentially. However, we have explored how the rate constant (in the mono exponentially cluster number decaying case) depends on strength of interference of the noises and their intensity. We have also explored how the structure factor at long time depends on the strength of the cross correlation (CC) between the additive and the multiplicative noises.

New particle searches at PEP

International Nuclear Information System (INIS)

Berley, D.; Bulos, F.; Cheng, D.

1988-01-01

The new particles that could be produced at PEP are discussed in terms of their specific signatures and production rates. We find that a small number of general signatures characterize these particles. Backgrounds associated with the general signatures are considered and necessary rejection rates are calculated. We describe several typical detectors and tabulate the requirements they place on the PEP machine and the experimental areas. 10 figs., 2 tabs

A laboratory investigation on the influence of adsorbed gases and particles from the exhaust of a kerosene burner on the evaporation rate of ice crystals and the ice nucleating ability of the exhaust particles

Energy Technology Data Exchange (ETDEWEB)

Diehl, K; Mitra, S K; Pruppacher, H R [Johannes Gutenberg Univ., Mainz (Germany). Inst. fuer Physik der Atmosphaere

1998-12-31

Laboratory experiments are described during which the influence of the exhausts of a kerosene burner on microphysical processes were studied. In one experimental investigation the evaporation rates of polluted ice crystals were compared with the evaporation rates of pure ice crystals. During another experimental investigation the ice nucleating ability of the exhaust particles was studied. The results show that the evaporation rate of polluted ice crystals was significantly reduced and also that ice nucleation takes place between -20 and -38 deg C. (author) 7 refs.

A laboratory investigation on the influence of adsorbed gases and particles from the exhaust of a kerosene burner on the evaporation rate of ice crystals and the ice nucleating ability of the exhaust particles

Energy Technology Data Exchange (ETDEWEB)

Diehl, K.; Mitra, S.K.; Pruppacher, H.R. [Johannes Gutenberg Univ., Mainz (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

Laboratory experiments are described during which the influence of the exhausts of a kerosene burner on microphysical processes were studied. In one experimental investigation the evaporation rates of polluted ice crystals were compared with the evaporation rates of pure ice crystals. During another experimental investigation the ice nucleating ability of the exhaust particles was studied. The results show that the evaporation rate of polluted ice crystals was significantly reduced and also that ice nucleation takes place between -20 and -38 deg C. (author) 7 refs.

Determination of parameters for hypervelocity dust grains encountered in near-Earth space

Science.gov (United States)

Tanner, William G.; Maag, Carl R.; Alexander, W. Merle; Sappenfield, Patricia

1993-01-01

Primarily interest was in the determination of the population of micrometeoroids and space debris and interpretation of the hole size in a thin film or in a micropore foam returned from space with theoretical calculations describing the event. In order to augment the significance of the theoretical calculations of the impact event, an experiment designed to analyze the charge production due to hypervelocity impacts on thin films also produced data which described the penetration properties of micron and sub-micron sized projectiles. The thin film penetration sites in the 500 A and 1000 A aluminum films were counted and a size distribution function was derived. In the case of the very smallest dust grains, there were no independent measurements of velocities like that which existed for the larger dust grains (d(sub p) is less than or equal to 1 micron). The primary task then became to assess the relationship between the penetration hole and the particle diameter of the projectile which made the hole. The most promising means to assess the measure of the diameters of impacting grains came in the form of comparing cratering mechanics to penetration mechanics. Future experimentation will produce measurements of the cratering as opposed to the penetrating event. Particles encountered by surfaces while being flown in space will degrade that surface in a systematic manner even when the impact is with small hypervelocity particles, d(sub p) is less than or equal to 10 microns. Though not to a degree which would precipitate a catastrophic failure of a system, the degradation of the materials comprising the interconnected system will occur. It is the degradation of the optical system and the subsequent embrittlement of other materials that can lead to degradation if not to failure. It is to this end that research was conducted to compare the primary consequences for experiments which will be flown to those which have been returned.

Choosing a language in international office service encounters

DEFF Research Database (Denmark)

Hazel, Spencer

Choosing a language in international office service encounters – from multilingual miscellany to medium-of-interaction in a matter of seconds Spencer Hazel Roskilde University, Denmark In higher education settings characterized by increasing transnational student and staff mobility, members...... to a multimodal interaction analysis following the ethnomethodological tradition of Conversation Analysis. Gafaranga, J. (2000). Medium repair vs. other-language repair: Telling the medium of a bilingual conversation. International Journal of Bilingualism, 4(3), 327-350. Hall, J. K., Hellermann, J., & Pekarek...... Preisler (eds.) Language alternation, language choice and language encounter in international education. Dordrecht: Springer Preisler, Bent, Ida Klitgård, and Anne H. Fabricius. (2011). Language and learning in the international university: from English uniformity to diversity and hybridity. Bristol...

Stereotype threat and racial differences in citizens' experiences of police encounters.

Science.gov (United States)

Najdowski, Cynthia J; Bottoms, Bette L; Goff, Phillip Atiba

2015-10-01

We conducted 2 studies to investigate how cultural stereotypes that depict Blacks as criminals affect the way Blacks experience encounters with police officers, expecting that such encounters induce Blacks to feel stereotype threat (i.e., concern about being judged and treated unfairly by police because of the stereotype). In Study 1, we asked Black and White participants to report how they feel when interacting with police officers in general. As predicted, Blacks, but not Whites, reported concern that police officers stereotype them as criminals simply because of their race. In addition, this effect was found for Black men but not Black women. In Study 2, we asked Black and White men to imagine a specific police encounter and assessed potential downstream consequences of stereotype threat. Consistent with Study 1, Black but not White men anticipated feeling stereotype threat in the hypothetical police encounter. Further, racial differences in anticipated threat translated into racial differences in anticipated anxiety, self-regulatory efforts, and behavior that is commonly perceived as suspicious by police officers. By demonstrating that Blacks might expect to be judged and treated unfairly by police because of the negative stereotype of Black criminality, this research extends stereotype threat theory to the new domain of criminal justice encounters. It also has practical implications for understanding how the stereotype could ironically contribute to bias-based policing and racial disparities in the justice system. (c) 2015 APA, all rights reserved).

THE RINGS OF CHARIKLO UNDER CLOSE ENCOUNTERS WITH THE GIANT PLANETS

Energy Technology Data Exchange (ETDEWEB)

Araujo, R. A. N.; Sfair, R.; Winter, O. C., E-mail: ran.araujo@gmail.com, E-mail: rsfair@feg.unesp.br, E-mail: ocwinter@gmail.com [UNESP - Univ. Estadual Paulista, Grupo de Dinâmica Orbital e Planetologia, CEP 12516-410, Guaratingueta, SP (Brazil)

2016-06-20

The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approach to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.

Method for producing ceramic particles and agglomerates

Science.gov (United States)

Phillips, Jonathan; Gleiman, Seth S.; Chen, Chun-Ku

2001-01-01

A method for generating spherical and irregularly shaped dense particles of ceramic oxides having a controlled particle size and particle size distribution. An aerosol containing precursor particles of oxide ceramics is directed into a plasma. As the particles flow through the hot zone of the plasma, they melt, collide, and join to form larger particles. If these larger particles remain in the hot zone, they continue melting and acquire a spherical shape that is retained after they exit the hot zone, cool down, and solidify. If they exit the hot zone before melting completely, their irregular shape persists and agglomerates are produced. The size and size distribution of the dense product particles can be controlled by adjusting several parameters, the most important in the case of powder precursors appears to be the density of powder in the aerosol stream that enters the plasma hot zone. This suggests that particle collision rate is responsible for determining ultimate size of the resulting sphere or agglomerate. Other parameters, particularly the gas flow rates and the microwave power, are also adjusted to control the particle size distribution.

High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

Science.gov (United States)

Fiorini, M.; Aglieri Rinella, G.; Carassiti, V.; Ceccucci, A.; Cortina Gil, E.; Cotta Ramusino, A.; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Perktold, L.; Petagna, P.; Petrucci, F.; Poltorak, K.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

2013-08-01

The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼ 1 GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X0. The expected fluence for 100 days of running is 2 ×1014 1 MeV neq /cm2, comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass (< 0.15 %X0) cooling system is being constructed, using a novel microchannel cooling silicon plate. Two complementary read-out architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100 μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200 μm thick silicon sensors.

Boundary Transgressions: An Issue In Psychotherapeutic Encounter ...

African Journals Online (AJOL)

Boundary transgressions tend to be conceptualized on a continuum ranging from boundary crossings to boundary violations. Boundary crossings (e.g. accepting an inexpensive holiday gift from a client, unintentionally encountering a client in public, or attending a client's special event) are described in the literature as ...

Mechanisms and rates of bacterial colonization of sinking aggregates

DEFF Research Database (Denmark)

Kiørboe, Thomas; Grossart, H.P.; Ploug, H.

2002-01-01

Quantifying the rate at which bacteria colonize aggregates is a key to understanding microbial turnover of aggregates. We used encounter models based on random walk and advection-diffusion considerations to predict colonization rates from the bacteria's motility patterns (swimming speed, tumbling...

Preliminary Exploration of Encounter During Transit Across Southern Africa

Energy Technology Data Exchange (ETDEWEB)

Stroud, Phillip David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cuellar-Hengartner, Leticia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kubicek, Deborah Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cleland, Timothy James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-10-28

Los Alamos National Laboratory (LANL) is utilizing the Probability Effectiveness Methodology (PEM) tools, particularly the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) to support the DNDO Architecture and Planning Directorate’s (APD) development of a multi-region terrorist risk assessment tool. The effort is divided into three stages. The first stage is an exploration of what can be done with PATRIOT essentially as is, to characterize encounter rate during transit across a single selected region. The second stage is to develop, condition, and implement required modifications to the data and conduct analysis to generate a well-founded assessment of the transit reliability across that selected region, and to identify any issues in the process. The final stage is to extend the work to a full multi-region global model. This document provides the results of the first stage, namely preliminary explorations with PATRIOT to assess the transit reliability across the region of southern Africa.

Variation of particle exhaust with changes in divertor magnetic balance

International Nuclear Information System (INIS)

Petrie, T.W.; Allen, S.L.; Brooks, N.H.

2006-01-01

Recent experiments on DIII-D point to the importance of two factors in determining how effectively the deuterium particle inventory in a tokamak plasma can be controlled through pumping at the divertor target(s): (1) the divertor magnetic balance, i.e. the degree to which the divertor topology is single-null or double-null (DN) and (2) the direction of the of B x ∇B ion drift with respect to the X-point(s). Changes in divertor magnetic balance near the DN shape have a much stronger effect on the particle exhaust rate at the inner divertor target(s) than on the particle exhaust rate at the outer divertor target(s). The particle exhaust rate for the DN shape is strongest at the outer strike point opposite the B x ∇B ion particle drift direction. Our data suggests that the presence of B x ∇B and E x B ion particle drifts in the scrape-off layer and divertor(s) play an important role in the particle exhaust rates of DN and near-DN plasmas. Particle exhaust rates are shown to depend strongly on the edge (pedestal) density. These results have implications for particle control in ITER and other future tokamaks

DEM Particle Fracture Model

Energy Technology Data Exchange (ETDEWEB)

Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

2015-12-01

An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density and packings o the samples are also studied in numerical examples.

Radiation in Particle Simulations

International Nuclear Information System (INIS)

More, R.; Graziani, F.; Glosli, J.; Surh, M.

2010-01-01

Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of

Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: crystallization relative humidities and nucleation rates.

Science.gov (United States)

Pant, Atul; Parsons, Matthew T; Bertram, Allan K

2006-07-20

Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is

Uptake of small particles by tree canopies

International Nuclear Information System (INIS)

Belot, Y.; Camus, H.; Gauthier, D.; Caput, C.

1992-01-01

Most of the deposition data that are available to assess the radiological consequences of an accident have been acquired for low-growing vegetation and are inadapted to forest areas. Consequently, a programme was undertaken to study the deposition of particles on components of different trees and extrapolate the experimental data so obtained to large-scale canopies. The experiments were performed in a wind tunnel allowing canopy components to be exposed to a flow of suspended fluorescent particles of reasonably uniform size. Emphasis was put on particles in the 0.3-1.2 μm subrange, because most of the radioactive particles sampled at long distance from sources are comprised in this size interval. The uptake rates were determined for bare and leaf bearing twigs of several evergreen species (Picea abies, Pinus sylvestris and Quercus ilex), as a function of wind speed and particle size. The deposition rates obtained for the tree components were then used as input to a model that describes the uptake of particles by a large-scale canopy under specified conditions of weather and canopy structure. The model accounts for the diffusion of particles between different strata of the canopy, as well as deposition of particles on the canopy components. It calculates the rates of particle deposition to the horizontal surface of the canopy, and the repartition of the deposited particles within the canopy. Increases in wind speed cause increased deposition, but the effect is less important that it would have been for larger particles. The deposition is relatively insensitive to the size of particles within the subrange considered in this study. 13 refs., 2 figs., 1 tab

Interfaith dialogue as moral encounter

DEFF Research Database (Denmark)

Galal, Lise Paulsen

The concept of interfaith dialogue has been introduced and developed by scholars of different religions. The aim has been to find solutions from within religion to handle and optimise encounters with religious ‘Others’. Furthermore, interfaith dialogue has increasingly become a tool to solve...... between Muslims and Christians and analyse the different moral orders involved and how – following these orders – the participants are expected to deal with differences. Main focus is on how the participants are expected to deal with a requirement of staying the same (as Christian or Muslim) while...

Special relativity a first encounter

CERN Document Server

Giulini, Domenico

2005-01-01

Special relativity provides the foundations of our knowledge of space and time. Without it, our understanding of the world, and its place in the universe, would be unthinkable. This book gives a concise, elementary, yet exceptionally modern, introduction to special relativity. It is a gentle yet serious 'first encounter', in that it conveys a true understanding rather than purely reports the basic facts. Only very elementary mathematical knowledge is needed to master it (basichigh-school maths), yet it will leave the reader with a sound understanding of the subject. Special Relativity: A First

Value Encounters - Modeling and Analyzing Co-creation of Value

Science.gov (United States)

Weigand, Hans

Recent marketing and management literature has introduced the concept of co-creation of value. Current value modeling approaches such as e3-value focus on the exchange of value rather than co-creation. In this paper, an extension to e3-value is proposed in the form of a “value encounter”. Value encounters are defined as interaction spaces where a group of actors meet and derive value by each one bringing in some of its own resources. They can be analyzed from multiple strategic perspectives, including knowledge management, social network management and operational management. Value encounter modeling can be instrumental in the context of service analysis and design.

Storyboard GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid encounters

Science.gov (United States)

1989-01-01

Storyboard with mosaicked image of an asteroid and entitled GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid objectives. These objectives include: first asteroid encounter; surface geology, composition size, shape, mass; and relation of primitive bodies to meteorites.

Nature and frequency of exchanges on medications during primary care encounters.

Science.gov (United States)

Richard, Claude; Lussier, Marie-Thérèse

2006-12-01

To describe the exchanges, related to discussion of all medications during primary care medical consultations. Descriptive study of audio recordings of 422 medical encounters. Coding was done with MEDICODE, a validated instrument developed to analyse verbal exchanges on medications. The unit of analysis is the medication. An average of 3.9 medications (S.D.=2.8; range 1-21) are discussed per interview and 4.2 themes are broached for each drug (S.D.=2.6; range 1-17). "Active Discussed", "Represcribed" and "Newly Prescribed" drugs account for 43.1, 16.3 and 10.6%, respectively of all medications discussed. Themes most often discussed are Name, Instructions, Observed Main Effect, Class, Reasons for Taking the Drug, General Use of the Medication, Expected Effect on Symptoms, Form of the Medication, Indications Another Consultation Needed, and Alternative Medication. The least often discussed themes include clinically significant ones such as Possible Adverse Effects, Observed Adverse Effects, Expression of Attitudes and Emotions with regard to the medication, Compliance and Warnings. The average number of themes discussed differed between medications that were prescribed during the encounter, either New prescriptions or Represcribed drugs, compared to medications that were only discussed during the encounter. Our results show that medication discussions are heterogeneous and vary with the status of the medication and the theme. Also, the nature and extent of the discussions about medications do not support the shared-decision making model. Though it is too soon to make specific recommendations about discussions on medications, it seems clear that information-sharing about medications during medical encounters is a process that extends beyond any single encounter. Although communication skills are now part of most medical curriculums, there is an obvious need to put forth the concept of patient medication knowledge-building over multiple physician-patient encounters and

Research on bimodal particle extinction coefficient during Brownian coagulation and condensation for the entire particle size regime

International Nuclear Information System (INIS)

Tang Hong; Lin Jianzhong

2011-01-01

The extinction coefficient of atmospheric aerosol particles influences the earth’s radiation balance directly or indirectly, and it can be determined by the scattering and absorption characteristics of aerosol particles. The problem of estimating the change of extinction coefficient due to time evolution of bimodal particle size distribution is studied, and two improved methods for calculating the Brownian coagulation coefficient and the condensation growth rate are proposed, respectively. Through the improved method based on Otto kernel, the Brownian coagulation coefficient can be expressed simply in powers of particle volume for the entire particle size regime based on the fitted polynomials of the mean enhancement function. Meanwhile, the improved method based on Fuchs–Sutugin kernel is developed to obtain the condensation growth rate for the entire particle size regime. And then, the change of the overall extinction coefficient of bimodal distributions undergoing Brownian coagulation and condensation can be estimated comprehensively for the entire particle size regime. Simulation experiments indicate that the extinction coefficients obtained with the improved methods coincide fairly well with the true values, which provide a simple, reliable, and general method to estimate the change of extinction coefficient for the entire particle size regime during the bimodal particle dynamic processes.

The transmission characteristics of indoor particles under different ventilation conditions

Directory of Open Access Journals (Sweden)

Lv Yang

2017-01-01

Full Text Available In modern society, ventilation is an important method for removing indoor particles. This study applies the parameter of attenuation index to analyze the effect of the removal of indoor particles in the two typical ventilation strategies called ceiling exhaust and slit exhaust strategy. Experiment was conducted in a chamber and riboflavin particles were used as the indoor particles source, instantaneous microbial detection (IMD used to measure the particulate concentration. Conclusions can be found that air exchange rate is an important factor affecting the indoor particle concentration distribution. In the process of indoor free settling(air exchange rate is 0 h-1, the deposition rate were 0.086 h-1, 0.122 h-1, 0.173 h-1 for the particles of 0.5–1.0 μm, 1.0–3.0μm and 3.0–5.0 μm. When the air exchange rate increased to 2.5 h-1, the differences in the attenuation index is significant. There was also a significant linear relationship between air exchange rate and attenuation index. Furthermore, the effect of the slit exhaust strategy on the removal of coarse particles is more remarkable as the increasing air exchange rate.

Particle size dependence of biogenic secondary organic aerosol molecular composition

Science.gov (United States)

Tu, Peijun; Johnston, Murray V.

2017-06-01

Formation of secondary organic aerosol (SOA) is initiated by the oxidation of volatile organic compounds (VOCs) in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process) to be distinguished from those produced by particle phase reaction (a volume-limited process). In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O / C) ratio and carbon oxidation state (OSc) were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases). Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased), the average O / C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes important.

Particle size dependence of biogenic secondary organic aerosol molecular composition

Directory of Open Access Journals (Sweden)

P. Tu

2017-06-01

Full Text Available Formation of secondary organic aerosol (SOA is initiated by the oxidation of volatile organic compounds (VOCs in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process to be distinguished from those produced by particle phase reaction (a volume-limited process. In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O ∕ C ratio and carbon oxidation state (OSc were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases. Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased, the average O ∕ C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes

Multiple Codes, Multiple Impressions: An Analysis of Doctor-Client Encounters in Nigeria

Science.gov (United States)

Odebunmi, Akin

2013-01-01

Existing studies on doctor-client interactions have largely focused on monolingual encounters and the interactional effects and functions of the languages used in the communication between doctors and their clients. They have neither, to a large extent, examined the several codes employed in single encounters and their pragmatic roles nor given…

Particle size control of detergents in mixed flow spray dryers

Directory of Open Access Journals (Sweden)

Mark Jonathan Crosby

2015-03-01

Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

Avoidance: From threat encounter to action execution

NARCIS (Netherlands)

Arnaudova, I.

2015-01-01

Every day we encounter many threats to survival: a car speeding on a small street or an angry neighbor carrying an axe. Mostly, people go through their days not worrying that their chance of survival might be small. They avoid many dangers without even thinking about them (e.g., looking at both

Entering a Crack: An Encounter with Gossip

Science.gov (United States)

Henderson, Linda

2014-01-01

In this paper, I enter a crack to think otherwise about the concept "gossip". Drawing on previous scholarship engaging with Deleuzian concepts to inform research methodologies, this paper builds on this body of work. Following Deleuze and Guattari, the paper undertakes a mapping of gossip, subsequent to an encounter with a crack.…

Pharmacy users' expectations of pharmacy encounters: a Q-methodological study.

Science.gov (United States)

Renberg, Tobias; Wichman Törnqvist, Kristina; Kälvemark Sporrong, Sofia; Kettis Lindblad, Asa; Tully, Mary P

2011-12-01

Pharmacy practice is evolving according to general health-care trends such as increased patient involvement and public health initiatives. In addition, pharmacists strive to find new professional roles. Clients' expectations of service encounters at pharmacies is an under-explored topic but crucial to understanding how pharmacy practice can evolve efficiently. To identify and describe different normative expectations of the pharmacy encounter among pharmacy clients. Q methodology, an approach to systematically explore subjectivity that retains complete patterns of responses and organizes these into factors of operant subjectivity. Eighty-five regular prescription medication users recruited at Swedish community pharmacies and by snowballing. Seven factors of operant subjectivity were identified, and organized into two groups. Factors that emphasized the physical drug product as the central object of the pharmacy encounter were labelled as independent drug shopping; logistics of drug distribution; and supply of individual's own drugs. Factors that emphasized personal support as desirable were labelled competence as individual support; individualist professional relations, just take care of me; and practical health-care and lifestyle support. The systematic Q-methodological approach yielded valuable insights into how pharmacy clients construct their expectations for service encounters. They hold differentiating normative expectations for pharmacy services. Understanding these varying viewpoints may be important for developing and prioritizing among efficient pharmacy services. Clients' expectations do not correspond with trends that guide current pharmacy practice development. This might be a challenge for promoting or implementing services based on such trends. © 2010 Blackwell Publishing Ltd.

Comet Dust: The Diversity of Primitive Particles and Implications

Science.gov (United States)

John Bradley; Zolensky, Michael E.

2016-01-01

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive particles has expanded significantly through microscale investigations of cosmic dust samples (IDPs and AMMs) and of comet dust samples (Stardust and Rosetta's COSIMA), as well as through remote sensing (spectroscopy and imaging) via Spitzer and via spacecraft encounters with 103P/Hartley 2 and 67P/Churyumov-Gerasimenko. Microscale investigations show that comet dust and cosmic dust are particles of unequilibrated materials, including aggregates of materials unequilibrated at submicron scales. We call unequilibrated materials "primitive" and we deduce they were incorporated into ice-­-rich (H2O-, CO2-, and CO-ice) parent bodies that remained cold, i.e., into comets, because of the lack of aqueous or thermal alteration since particle aggregation; yet some Stardust olivines suggest mild thermal metamorphism. Primitive particles exhibit a diverse range of: structure and typology; size and size distribution of constituents; concentration and form of carbonaceous and organic matter; D-, N-, and O- isotopic enhancements over solar; Mg-, Fe-contentsof thesilicate minerals; the compositions and concentrations of sulfides, and of less abundant mineral species such as chondrules, CAIs and carbonates. The unifomity within a group of samples points to: aerodynamic sorting of particles and/or particle constituents; the inclusion of a limited range of oxygen fugacities; the inclusion or exclusion of chondrules; a selection of organics. The properites of primitive particles imply there were disk processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disk present at the time and in the region where the comets formed.

Avoiding humiliations in the clinical encounter.

Science.gov (United States)

Malterud, Kirsti; Hollnagel, Hanne

2007-06-01

To explore potentials for avoiding humiliations in clinical encounters, especially those that are unintended and unrecognized by the doctor. Furthermore, to examine theoretical foundations of degrading behaviour and identify some concepts that can be used to understand such behaviour in the cultural context of medicine. Finally, these concepts are used to build a model for the clinician in order to prevent humiliation of the patient. Empirical studies document experiences of humiliation among patients when they see their doctor. Philosophical and sociological analysis can be used to explain the dynamics of unintended degrading behaviour between human beings. Skjervheim, Vetlesen, and Bauman have identified the role of objectivism, distantiation, and indifference in the dynamics of evil acts, pointing to the rules of the cultural system, rather than accusing the individual of bad behaviour. Examining the professional role of the doctor, parallel traits embedded in the medical culture are demonstrated. According to Vetlesen, emotional awareness is necessary for moral perception, which again is necessary for moral performance. A better balance between emotions and rationality is needed to avoid humiliations in the clinical encounter. The Awareness Model is presented as a strategy for clinical practice and education, emphasizing the role of the doctor's own emotions. Potentials and pitfalls are discussed.

Determination of the light-induced degradation rate of the solar cell sensitizer N719 on TiO2 nanocrystalline particles

DEFF Research Database (Denmark)

Nour-Mohammadi, Farahnaz; Doan Nguyen, Sau; Boschloo, Gerrit

2005-01-01

The oxidative degradation rate, kdeg of the solar cell dye (Bu4N+)2 [Ru(dcbpyH)2(NCS)2]2–, referred to as N719 or [RuL2(NCS)2], was obtained by applying a simple model system. Colloidal solutions of N719-dyed TiO2 particles in acetonitrile were irradiated with 532-nm monochromatic light, and the ...

Energetic particles in the inner magnetosphere of Jupiter: simulation and results from the energetic particles detector on board the Galileo spacecraft

International Nuclear Information System (INIS)

Lagg, A.

1997-11-01

The simulation of the Low Energy Magnetospheric Measurement System (LEMMS) on board the GALILEO spacecraft and the analysis of data from the Jovian magnetosphere are the main topics of this work. The geometric factors obtained from this simulation can reproduce spectral electron fluxes measured in the Jovian magnetosphere without applying additional corrections. The depletion of particles at high pitch angles measured during the first encounter period with Io is used to calculate neutral number density and latitudinal extension of the neutral gas torus at the Io orbit. As the most likely interaction process the charge exchange between energetic charged particles and the neutral sulfur and oxygen atoms in the torus is discussed. A simple model for this region including this interaction mechanism is the basis for the first calculation of the neutral number density from in-situ measurements of charged particle fluxes. An additional topic of the data analysis is an energy dispersive enhancement of electron fluxes observed in the Io torus. The plasma transport as a consequence of the gradient-curvature drift motion is examined. The time and the origin of a possible injection process is estimated. (author)

Analysis of aluminum protective effect for female astronauts in solar particle events

Directory of Open Access Journals (Sweden)

Xu Feng

2017-01-01

Full Text Available In order to ensure the health and safety of female astronauts in space, the risks of space radiation should be evaluated, and effective methods for protecting against space radiation should be investigated. In this paper, a dose calculation model is established for Chinese female astronauts. The absorbed doses of some organs in two historical solar particle events are calculated using Monte Carlo methods, and the shielding conditions are 0 gcm-2 and 5 gcm-2 aluminum, respectively. The calculated results are analysed, compared, and discussed. The results show that 5 gcm-2 aluminum cannot afford enough effective protection in solar particle events. Hence, once encountering solar particle events in manned spaceflight missions, in order to ensure the health and safety of female astronauts, they are not allowed to stay in the pressure vessel, and must enter into the thicker shielding location such as food and water storage cabin.

Multi-purpose two- and three-dimensional momentum imaging of charged particles for attosecond experiments at 1 kHz repetition rate

Energy Technology Data Exchange (ETDEWEB)

Månsson, Erik P., E-mail: erik.mansson@sljus.lu.se; Sorensen, Stacey L.; Gisselbrecht, Mathieu [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Arnold, Cord L.; Kroon, David; Guénot, Diego; Fordell, Thomas; Johnsson, Per; L’Huillier, Anne [Division of Atomic Physics, Lund University, Box 118, 221 00 Lund (Sweden); Lépine, Franck [Institut Lumière Matière, UMR5306, Université Lyon 1-CNRS, 10 rue Ada Byron, 69622 Villeurbanne cedex (France)

2014-12-15

We report on the versatile design and operation of a two-sided spectrometer for the imaging of charged-particle momenta in two dimensions (2D) and three dimensions (3D). The benefits of 3D detection are to discern particles of different mass and to study correlations between fragments from multi-ionization processes, while 2D detectors are more efficient for single-ionization applications. Combining these detector types in one instrument allows us to detect positive and negative particles simultaneously and to reduce acquisition times by using the 2D detector at a higher ionization rate when the third dimension is not required. The combined access to electronic and nuclear dynamics available when both sides are used together is important for studying photoreactions in samples of increasing complexity. The possibilities and limitations of 3D momentum imaging of electrons or ions in the same spectrometer geometry are investigated analytically and three different modes of operation demonstrated experimentally, with infrared or extreme ultraviolet light and an atomic/molecular beam.

Islamic Canon law encounters South African financing and banking ...

African Journals Online (AJOL)

Islamic Canon law encounters South African financing and banking institutions: Prospects and possibilities for Islamic economic empowerment and Black Economic Empowerment in a Democratic South Africa.

Generalizability of Standardized Patients' Satisfaction Ratings of Their Clinical Encounter with Fourth-Year Medical Students.

Science.gov (United States)

Vu, Nu Viet; And Others

1990-01-01

At the end of their clinical clerkship rotations, all students in one medical school's classes of 1988 (N=69), 1989 (N=63), 1990 (N=66) took the Post-Clerkship Examination. This study examined the nature of the patients' satisfaction ratings; reliability of patient satisfaction ratings and number of patients needed to derive reliable ratings; etc.…

Estimating rates of decompression from textures of erupted ash particles produced by 1999-2006 eruptions of Tungurahua volcano, Ecuador

Science.gov (United States)

Wright, Heather M.N.; Cashman, Katharine V.; Mothes, Patricia A.; Hall, Minard L.; Ruiz, Andrés Gorki; Le Pennec, Jean-Luc

2012-01-01

Persistent low- to moderate-level eruptive activity of andesitic volcanoes is difficult to monitor because small changes in magma supply rates may cause abrupt transitions in eruptive style. As direct measurement of magma supply is not possible, robust techniques for indirect measurements must be developed. Here we demonstrate that crystal textures of ash particles from 1999 to 2006 Vulcanian and Strombolian eruptions of Tungurahua volcano, Ecuador, provide quantitative information about the dynamics of magma ascent and eruption that is difficult to obtain from other monitoring approaches. We show that the crystallinity of erupted ash particles is controlled by the magma supply rate (MSR); ash erupted during periods of high magma supply is substantially less crystalline than during periods of low magma supply. This correlation is most easily explained by efficient degassing at very low pressures (<<50 MPa) and degassing-driven crystallization controlled by the time available prior to eruption. Our data also suggest that the observed transition from intermittent Vulcanian explosions at low MSR to more continuous periods of Strombolian eruptions and lava fountains at high MSR can be explained by the rise of bubbles through (Strombolian) or trapping of bubbles beneath (Vulcanian) vent-capping, variably viscous (and crystalline) magma.

Comet Dust: The Diversity of "Primitive" Particles and Implications

Science.gov (United States)

Wooden, Diane H.; Ishii, Hope A.; Bradley, John P.; Zolensky, Michael E.

2016-01-01

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive particles has expanded significantly through microscale investigations of cosmic dust samples ( IDP's(Interplanetary Dust Particles) and AMM's (Antarctic Micrometeorites)) and of comet dust samples (Stardust and Rosetta's COSIMA), as well as through remote sensing (spectroscopy and imaging) via Spitzer and via spacecraft encounters with 103P/Hartley 2 and 67P/Churyumov-Gerasimenko. Microscale investigations show that comet dust and cosmic dust are particles of unequilibrated materials, including aggregates of materials unequilibrated at submicron scales. We call unequilibrated materials "primitive" and we deduce they were incorporated into ice-rich (H2O-, CO2-, and CO-ice) parent bodies that remained cold, i.e., into comets, because of the lack of aqueous or thermal alteration since particle aggregation; yet some Stardust olivines suggest mild thermal metamorphism. Primitive particles exhibit a diverse range of: structure and typology; size and size distribution of constituents; concentration and form of carbonaceous and organic matter; D-, N-, and O- isotopic enhancements over solar; Mg-, Fe-contents of the silicate minerals; the compositions and concentrations of sulfides, and of less abundant mineral species such as chondrules, CAIs and carbonates. The uniformity within a group of samples points to: aerodynamic sorting of particles and/or particle constituents; the inclusion of a limited range of oxygen fugacities; the inclusion or exclusion of chondrules; a selection of organics. The properties of primitive particles imply there were disk processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disk present at the time and in the region where the comets formed.

Cooling many particles at once

International Nuclear Information System (INIS)

Vitiello, G.; Knight, P.; Beige, A.

2005-01-01

Full text: We propose a mechanism for the collective cooling of a large number N of trapped particles to very low temperatures by applying red-detuned laser fields and coupling them to the quantized field inside an optical resonator. The dynamics is described by what appear to be rate equations but where some of the major quantities are coherences and not populations. It is shown that the cooperative behaviour of the system provides cooling rates of the same order of magnitude as the cavity decay rate. This constitutes a significant speed-up compared to other cooling mechanisms since this rate can, in principle, be as large as the square root of N times the single-particle cavity or laser coupling constants. (author)

A Survey Instrument for Measuring the Experiential Value of Employee-Tourist Encounters

DEFF Research Database (Denmark)

Mattsson, Jan; Sørensen, Flemming; Jensen, Jens Friis

In this paper, we develop and test a survey instrument that aims at estimating the experiential value of employee-tourist encounters in destination-based tourism companies, as well as the characteristics of encounters that affect such experiential value. We suggest that such an instrument can...... for their visitors, rather than simply delivering service quality....

Structural and fractal properties of particles emitted from spark ignition engines.

Science.gov (United States)

Chakrabarty, Rajan K; Moosmüller, Hans; Arnott, W Patrick; Garro, Mark A; Walker, John

2006-11-01

Size, morphology, and microstructure of particles emitted from one light-duty passenger vehicle (Buick Century; model year 1990; PM (particulate matter) mass emission rate 3.1 mg/km) and two light-duty trucks (Chevrolet C2; model year 1973; PM mass emission rate 282 mg/km, and Chevrolet El Camino; model year 1976; PM mass emission rate 31 mg/km), running California's unified driving cycles (UDC) on a chassis dynamometer, were studied using scanning electron microscopy (SEM). SEM images yielded particle properties including three-dimensional density fractal dimensions, monomer and agglomerate number size distributions, and three different shape descriptors, namely aspect ratio, root form factor, and roundness. The density fractal dimension of the particles was between 1.7 and 1.78, while the number size distribution of the particles placed the majority of the particles in the accumulation mode (0.1-0.3 microm). The shape descriptors were found to decrease with increasing particle size. Partial melting of particles, a rare and previously unreported phenomenon, was observed upon exposure of particles emitted during phase 2 of the UDC to the low accelerating voltage electron beam of the SEM. The rate of melting was quantified for individual particles, establishing a near linear relationship between the melting rate and the organic carbon 1 to elemental carbon ratio.

An assessment of technology-based service encounters & network security on the e-health care systems of medical centers in Taiwan

Directory of Open Access Journals (Sweden)

Chang Ching

2008-04-01

Full Text Available Abstract Background Enhancing service efficiency and quality has always been one of the most important factors to heighten competitiveness in the health care service industry. Thus, how to utilize information technology to reduce work load for staff and expeditiously improve work efficiency and healthcare service quality is presently the top priority for every healthcare institution. In this fast changing modern society, e-health care systems are currently the best possible way to achieve enhanced service efficiency and quality under the restraint of healthcare cost control. The electronic medical record system and the online appointment system are the core features in employing e-health care systems in the technology-based service encounters. Methods This study implemented the Service Encounters Evaluation Model, the European Customer Satisfaction Index, the Attribute Model and the Overall Affect Model for model inference. A total of 700 copies of questionnaires from two authoritative southern Taiwan medical centers providing the electronic medical record system and the online appointment system service were distributed, among which 590 valid copies were retrieved with a response rate of 84.3%. We then used SPSS 11.0 and the Linear Structural Relationship Model (LISREL 8.54 to analyze and evaluate the data. Results The findings are as follows: (1 Technology-based service encounters have a positive impact on service quality, but not patient satisfaction; (2 After experiencing technology-based service encounters, the cognition of the service quality has a positive effect on patient satisfaction; and (3 Network security contributes a positive moderating effect on service quality and patient satisfaction. Conclusion It revealed that the impact of electronic workflow (online appointment system service on service quality was greater than electronic facilities (electronic medical record systems in technology-based service encounters. Convenience and

An assessment of technology-based service encounters & network security on the e-health care systems of medical centers in Taiwan.

Science.gov (United States)

Chang, Hsin Hsin; Chang, Ching Sheng

2008-04-17

Enhancing service efficiency and quality has always been one of the most important factors to heighten competitiveness in the health care service industry. Thus, how to utilize information technology to reduce work load for staff and expeditiously improve work efficiency and healthcare service quality is presently the top priority for every healthcare institution. In this fast changing modern society, e-health care systems are currently the best possible way to achieve enhanced service efficiency and quality under the restraint of healthcare cost control. The electronic medical record system and the online appointment system are the core features in employing e-health care systems in the technology-based service encounters. This study implemented the Service Encounters Evaluation Model, the European Customer Satisfaction Index, the Attribute Model and the Overall Affect Model for model inference. A total of 700 copies of questionnaires from two authoritative southern Taiwan medical centers providing the electronic medical record system and the online appointment system service were distributed, among which 590 valid copies were retrieved with a response rate of 84.3%. We then used SPSS 11.0 and the Linear Structural Relationship Model (LISREL 8.54) to analyze and evaluate the data. The findings are as follows: (1) Technology-based service encounters have a positive impact on service quality, but not patient satisfaction; (2) After experiencing technology-based service encounters, the cognition of the service quality has a positive effect on patient satisfaction; and (3) Network security contributes a positive moderating effect on service quality and patient satisfaction. It revealed that the impact of electronic workflow (online appointment system service) on service quality was greater than electronic facilities (electronic medical record systems) in technology-based service encounters. Convenience and credibility are the most important factors of service quality

submitter Introduction to Collective Effects in Particle Accelerators

CERN Document Server

Zimmermann, Frank

2016-01-01

The beam intensity and the beam brightness of particle accelerators or colliders operated for high - energy physics were, and are, often severely limited by “collective effects” (e.g.[1]). By contrast, new light sources, such as linac - based free electron lasers, may even rely on collective instabilities to accomplish their mission! The term “collective effects” refers to the interaction of beam particles with each other through a variety of processes, e.g. (1) non-delayed self-fields and image fields present even for constant perfectly conducting and magnetic boundaries (direct and indirect “space - charge effects”), (2) longer - lived electro-magnetic “wake fields” due to a finite chamber resistivity or geometric variation in the beam - pipe cross section, which typically affect later parts of the beam, (3) coherent synchrotron radiation, which on a curved trajectory may even influence earlier parts of the beam, giving rise to “non-causal” wake fields, otherwise not normally encountered...

Patient-provider interaction during medication encounters: A study in outpatient pharmacies in the Netherlands.

Science.gov (United States)

Koster, Ellen S; van Meeteren, Marijke M; van Dijk, Marloes; van de Bemt, Bart J F; Ensing, Hendrikus T; Bouvy, Marcel L; Blom, Lyda; van Dijk, Liset

2015-07-01

To describe communication between pharmacy staff and patients at the counter in outpatient pharmacies. Both content and communication style were investigated. Pharmaceutical encounters in three outpatient pharmacies in the Netherlands were video-recorded. Videos were analyzed based on an observation protocol for the following information: content of encounter, initiator of a theme and pharmacy staff's communication style. In total, 119 encounters were recorded which concerned 42 first prescriptions, 16 first refill prescriptions and 61 follow-up refill prescriptions. During all encounters, discussion was mostly initiated by pharmacy staff (85%). In first prescription encounters topics most frequently discussed included instructions for use (83%) and dosage instructions (95%). In first refill encounters, patient experiences such as adverse effects (44%) and beneficial effects (38%) were regularly discussed in contrast to follow-up refills (7% and 5%). Patients' opinion on medication was hardly discussed. Pharmacy staff in outpatient pharmacies generally provide practical information, less frequently they discuss patients' experiences and seldom discuss patients' perceptions and preferences about prescribed medication. This study shows there is room for improvement, as communication is still not according to professional guidelines. To implement professional guidelines successfully, it is necessary to identify underlying reasons for not following the guidelines. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The Reality of Encounters with Local Life in Other Cultures

Directory of Open Access Journals (Sweden)

Jin-Young Kim

2017-12-01

Full Text Available Equipped with mobile technologies, travelers increasingly seek opportunities to encounter the real lives of the people residing in the focal destination. With this trend of pursuing local life experience, this study investigated how international visitors recognize the lives of people in the focal destination, and whether this recognition is related to satisfaction. Reviews for Teheran’s Grand Bazaar from an online review site, Tripadvisor.com, showed that visitors’ local encounters were linked with favorable emotions (good, interesting, and worthwhile. To lend support to the contact hypothesis, which posits that intercultural experiences can lead to more favorable evaluations of the host community; the visitors who recognized direct and indirect encounters with local life indicated higher satisfaction. Even if brief, the experience of local life appeared to create more intimate feelings for the focal destination. Interestingly, the number of past travel experiences, which was captured by the number of reviews written by the reviewer, was found to have a negative association with satisfaction. We draw further implications for the travelers as well as the local community.

Global Particle Balance Measurements in DIII-D H-mode Discharges

International Nuclear Information System (INIS)

Unterberg, Ezekial A.; Allen, S.L.; Brooks, N.; Evans, T.E.; Leonard, A.W.; McLean, A.; Watkins, J.G.; Whyte, D.G.

2011-01-01

Experiments are performed on the DIII-D tokamak to determine the retention rate in an all graphite first-wall tokamak. A time-dependent particle balance analysis shows a majority of the fuel retention occurs during the initial Ohmic and L-mode phase of discharges, with peak fuel retention rates typically similar to 2 x 10(21) D/s. The retention rate can be zero within the experimental uncertainties (<3 x 10(20) D/s) during the later stationary phase of the discharge. In general, the retention inventory can decrease in the stationary phase by similar to 20-30% from the initial start-up phase of the discharge. Particle inventories determined as a function of time in the discharge, using a 'dynamic' particle balance analysis, agree with more accurate particle inventories directly measured after the discharge, termed 'static' particle balance. Similarly, low stationary retention rates are found in discharges with heating from neutral-beams, which injects particles, and from electron cyclotron waves, which does not inject particles. Detailed analysis of the static and dynamic balance methods provide an estimate of the DIII-D global co-deposition rate of <= 0.6-1.2 x 10(20) D/s. Dynamic particle balance is also performed on discharges with resonant magnetic perturbation ELM suppression and shows no additional retention during the ELM-suppressed phase of the discharge.

The importance of motivation, weapons, and foul odors in driving encounter competition in carnivores.

Science.gov (United States)

Allen, Maximilian L; Wilmers, Christopher C; Elbroch, L Mark; Golla, Julie M; Wittmer, Heiko U

2016-08-01

Encounter competition is interference competition in which animals directly contend for resources. Ecological theory predicts the trait that determines the resource holding potential (RHP), and hence the winner of encounter competition, is most often body size or mass. The difficulties of observing encounter competition in complex organisms in natural environments, however, has limited opportunities to test this theory across diverse species. We studied the outcome of encounter competition contests among mesocarnivores at deer carcasses in California to determine the most important variables for winning these contests. We found some support for current theory in that body mass is important in determining the winner of encounter competition, but we found that other factors including hunger and species-specific traits were also important. In particular, our top models were "strength and hunger" and "size and hunger," with models emphasizing the complexity of variables influencing outcomes of encounter competition. In addition, our wins above predicted (WAP) statistic suggests that an important aspect that determines the winner of encounter competition is species-specific advantages that increase their RHP, as bobcats (Lynx rufus) and spotted skunks (Spilogale gracilis) won more often than predicted based on mass. In complex organisms, such as mesocarnivores, species-specific adaptations, including strategic behaviors, aggressiveness, and weapons, contribute to competitive advantages and may allow certain species to take control or defend resources better than others. Our results help explain how interspecific competition shapes the occurrence patterns of species in ecological communities. © 2016 by the Ecological Society of America.

The effect of particle shape on hopper discharge

Energy Technology Data Exchange (ETDEWEB)

Cleary, P.W. [CSIRO, Clayton, Vic. (Australia). Mathematical and Information Sciences

1999-07-01

Hopper flows are an important class of industrial particle flows. The inclusion of particle shape allows DEM models to replicate many features of real hopper flows that are not possible when using circular particles. Elongated particles can produce flow rates up to 30% lower than for circular particles and the flow patterns are quite different. The yielding of the particle microstructure resembles more the tearing of a continuum solid, with large scale quasi-stable voids being formed and large groups of particles moving together. The flow becomes increasingly concentrated in a relatively narrow funnel above the hopper opening. This is encouragement that DEM may be able to predict important problems such as bridging and rat-holing. Increasing the blockiness or angularity of the particles also increases resistance to flow and reduces flow rates by up to 28% but does not have any perceptible effect on the nature of the flow. 11 refs., 7 figs.

Magnetic particle separation using controllable magnetic force switches

International Nuclear Information System (INIS)

Wei Zunghang; Lee, C.-P.; Lai, M.-F.

2010-01-01

Magnetic particle separation is very important in biomedical applications. In this study, a magnetic particle microseparator is proposed that uses micro magnets to produce open/closed magnetic flux for switching on/off the separation. When all magnets are magnetized in the same direction, the magnetic force switch for separation is on; almost all magnetic particles are trapped in the channel side walls and the separation rate can reach 95%. When the magnetization directions of adjacent magnets are opposite, the magnetic force switch for separation is off, and most magnetic particles pass through the microchannel without being trapped. For the separation of multi-sized magnetic particles, the proposed microseparator is numerically demonstrated to have high separation rate.

Determining size-specific emission factors for environmental tobacco smoke particles

Energy Technology Data Exchange (ETDEWEB)

Klepeis, Neil E.; Apte, Michael G.; Gundel, Lara A.; Sextro, Richard G.; Nazaroff, William W.

2002-07-07

Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured every minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1-2+ micrometer diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01-1+ micrometer diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m{sup 3} chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 hours after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle emission factors were fit with log-normal distributions, yielding an average mass median diameter of 0.2 micrometers and an average geometric standard deviation of 2.3 with no systematic differences between cigars and cigarettes. The equivalent total particle emission rate, obtained integrating each size distribution, was 0.2-0.7 mg/min for cigars and 0.7-0.9 mg/min for cigarettes.

Cultural diversity, democracy and the prospects of cosmopolitanism: a theory of cultural encounters.

Science.gov (United States)

Delanty, Gerard

2011-12-01

The most appropriate way of theorizing cultural diversity is to situate it in the context of a broader relational theory of culture in which the key dynamic is cultural encounters. The relational conception of culture places the emphasis on the relations between social actors and the processes by which some of these relations generate enduring cultural regularities and forms. This has important implications for political community and in particular for cosmopolitanism. It is in relationships that cultural phenomena are generated and become the basis of different kinds of political community. The paper outlines a typology of six kinds of cultural encounters and discusses four major cultural trends that variously emerge from these encounters. This approach with its emphasis on cultural encounters is the broad sociological context in which questions about cultural change and the prospects of cosmopolitanism should be discussed. © London School of Economics and Political Science 2011.

Potentials and pitfalls of the encounter between leisure-time centers and primary schools

DEFF Research Database (Denmark)

Ringskou, Lea Thomsen; Gravesen, David Thore

Our research offers a qualitative, in depth-perspective on the encounter between leisure-time centers and primary schools in Denmark. In our presentration we will, in a cross-cultural perspective, reappraise the roles of leisure-time pedagogues and discuss the potentials and pitfalls of the encou......Our research offers a qualitative, in depth-perspective on the encounter between leisure-time centers and primary schools in Denmark. In our presentration we will, in a cross-cultural perspective, reappraise the roles of leisure-time pedagogues and discuss the potentials and pitfalls...... of the encounter between leisure-time centers and primary schools. In 2014, the Danish Primary School was reformed. To a considerable extent, the reform can be understood in response to receding results in international tests (Knudsen 2010). The official aim of the reform is to challenge all pupils, regardless...... the encounter between leisure-time centers and primary schools?...

Microscopic origin and macroscopic implications of lane formation in mixtures of oppositely-driven particles

Science.gov (United States)

Whitelam, Stephen

Colloidal particles of two types, driven in opposite directions, can segregate into lanes. I will describe some results on this phenomenon obtained by simple physical arguments and computer simulations. Laning results from rectification of diffusion on the scale of a particle diameter: oppositely-driven particles must, in the time taken to encounter each other in the direction of the drive, diffuse in the perpendicular direction by about one particle diameter. This geometric constraint implies that the diffusion constant of a particle, in the presence of those of the opposite type, grows approximately linearly with Peclet number, a prediction confirmed by our numerics. Such environment-dependent diffusion is statistically similar to an effective interparticle attraction; consistent with this observation, we find that oppositely-driven colloids display features characteristic of the simplest model system possessing both interparticle attractions and persistent motion, the driven Ising lattice gas. Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Difficult medical encounters and job satisfaction - results of a cross sectional study with general practitioners in Germany.

Science.gov (United States)

Goetz, Katja; Mahnkopf, Janis; Kornitzky, Anna; Steinhäuser, Jost

2018-05-09

In primary care 15% of patient encounters are perceived as challenging by general practitioners (GP). However it is unknown what impact these encounters have regarding job satisfaction. The aim of this study was to evaluate which encounters are perceived as challenging by German GPs and whether they were associated with job satisfaction. A total of 1538 questionnaires were sent to GPs in the federal state of Schleswig-Holstein, Germany. GPs should rate 14 medical conditions and 8 traits of patients on the perceived challenge using a Likert scale (1: 'not challenging at all' to 10: 'extremely challenging'). Job satisfaction was measured with the Warr-Cook-Wall job satisfaction scale. A linear regression analyses were used to explore potential associations between for the primary outcome variable 'overall job satisfaction'. Total response was 578 (38%). GPs perceived 16% of their patients as challenging. Psychiatric disorders such as somatization disorder (mean = 7.42), schizophrenia (mean = 6.83) and anxiety disorder (mean = 6.57) were ranked as high challenging while diabetes mellitus type 2 (mean = 4.87) and high blood pressure (mean = 3.22) were ranked as a rather low challenging condition. GPs were mostly satisfied with 'colleagues' (mean = 5.80) and mostly dissatisfied with their 'hours of work' (mean = 4.20). The linear regression analysis showed no association with challenging medical conditions and traits of patients but only with different aspects of job satisfaction concerning the outcome variable 'overall job satisfaction'. Especially psychiatric conditions are perceived as challenging the question arises, in what amount psychiatric competences are gained during the postgraduate specialty training in general practice and if GPs with a mandatory rotation in psychiatry perceive these conditions as less challenging. Interestingly this study indicates that challenging encounter in terms of challenging medical conditions and traits

Lightweight energetic particle detector EPONA and its performance on Giotto

Energy Technology Data Exchange (ETDEWEB)

McKenna-Lawlor, S.; Kirsch, E.; Thompson, A.; O' Sullivan, D.; Wenzel, K.-P.

1987-06-01

A lightweight energetic particle detector system (EPONA/EPA) is described which was designed to operate in those novel environmental conditions (i) characterised by the varying solar aspect angles and temperatures pertaining during the cruise phase of the Giotto spacecraft and (ii) during the dust bombardment characterising closest approach (approx. 600 km) to the nucleus of comet Halley. Representative data, illustrating the functioning of EPONA during both the Giotto cruise phase and at comet encounter, are represented. The instrument has a wide range of applications to other space experiments where reliable plasma diagnostics are required.

Dyadic Interactions in Service Encounter: Bayesian SEM Approach

Science.gov (United States)

Sagan, Adam; Kowalska-Musiał, Magdalena

Dyadic interactions are an important aspects in service encounters. They may be observed in B2B distribution channels, professional services, buying centers, family decision making or WOM communications. The networks consist of dyadic bonds that form dense but weak ties among the actors.

Application of RVA and Time-Lapse Photography to Explore Effects of Extent of Chlorination, Milling Extraction Rate, and Particle-Size Reduction of Flour on Cake-Baking Functionality

Science.gov (United States)

Three factors (extent of chlorination, milling extraction rate and particle-size reduction) in the cake-bakeing functionality of Croplan 594W flour were explored by Rapid Visco-Analyzer (RVA) and time-lapse photography. The extent of chlorination and milling extraction rate showed dramatic effects,...

Tailoring particle size and morphology of colloidal Ag particles via chemical precipitation for Ag-BSCCO composites

International Nuclear Information System (INIS)

Medendorp, N.W. Jr.; Bowman, K.J.; Trumble, K.P.

1996-01-01

The chemical precipitation of silver particles is an effective method for tailoring the particle size and morphology. This article investigates a chemical precipitation method for producing silver colloids, and how processing parameters affected particle size, morphology and adherence. Decreasing the silver nitrate concentration during precipitation with sodium borohydride decreased the colloidal silver particle size. Decreasing the addition rate of the reducing agent produced faceted particles. Reversing the reactant addition order also changed the particle size and the morphology. Precipitated colloids demonstrated a difference between the growth-dominated and the equilibrium structures. Co-dispersing Bi-based superconducting platelets during precipitation allowed Ag colloids to preferentially nucleate on the platelets and to remain adhered even after the additional processing. (orig.)

Border Encounters: American Cultural Politics and the U.S.-Mexico Border

OpenAIRE

Reimer, Jennifer Andrea

2011-01-01

AbstractBorder Encounters: American Cultural Politics and the U.S.-Mexico BorderbyJennifer Andrea ReimerDoctor of Philosophy in Ethnic StudiesUniversity of California, BerkeleyProfessor José David Saldívar, Co-ChairProfessor Laura E. Pérez, Co-ChairBorder Encounters: American Cultural Politics and the U.S.-Mexico Border is a transnational, interdisciplinary cultural study of the contemporary U.S.-Mexico border that argues for the critical role of the international border in the racial past, p...

In Situ Balloon-Borne Ice Particle Imaging in High-Latitude Cirrus

Science.gov (United States)

Kuhn, Thomas; Heymsfield, Andrew J.

2016-09-01

Cirrus clouds reflect incoming solar radiation, creating a cooling effect. At the same time, these clouds absorb the infrared radiation from the Earth, creating a greenhouse effect. The net effect, crucial for radiative transfer, depends on the cirrus microphysical properties, such as particle size distributions and particle shapes. Knowledge of these cloud properties is also needed for calibrating and validating passive and active remote sensors. Ice particles of sizes below 100 µm are inherently difficult to measure with aircraft-mounted probes due to issues with resolution, sizing, and size-dependent sampling volume. Furthermore, artefacts are produced by shattering of particles on the leading surfaces of the aircraft probes when particles several hundred microns or larger are present. Here, we report on a series of balloon-borne in situ measurements that were carried out at a high-latitude location, Kiruna in northern Sweden (68N 21E). The method used here avoids these issues experienced with the aircraft probes. Furthermore, with a balloon-borne instrument, data are collected as vertical profiles, more useful for calibrating or evaluating remote sensing measurements than data collected along horizontal traverses. Particles are collected on an oil-coated film at a sampling speed given directly by the ascending rate of the balloon, 4 m s-1. The collecting film is advanced uniformly inside the instrument so that an always unused section of the film is exposed to ice particles, which are measured by imaging shortly after sampling. The high optical resolution of about 4 µm together with a pixel resolution of 1.65 µm allows particle detection at sizes of 10 µm and larger. For particles that are 20 µm (12 pixel) in size or larger, the shape can be recognized. The sampling volume, 130 cm3 s-1, is well defined and independent of particle size. With the encountered number concentrations of between 4 and 400 L-1, this required about 90- to 4-s sampling times to

Kinetic energy density and agglomerate abrasion rate during blending of agglomerates into powders.

Science.gov (United States)

Willemsz, Tofan A; Hooijmaijers, Ricardo; Rubingh, Carina M; Tran, Thanh N; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

2012-01-23

Problems related to the blending of a cohesive powder with a free flowing bulk powder are frequently encountered in the pharmaceutical industry. The cohesive powder often forms lumps or agglomerates which are not dispersed during the mixing process and are therefore detrimental to blend uniformity. Achieving sufficient blend uniformity requires that the blending conditions are able to break up agglomerates, which is often an abrasion process. This study was based on the assumption that the abrasion rate of agglomerates determines the required blending time. It is shown that the kinetic energy density of the moving powder bed is a relevant parameter which correlates with the abrasion rate of agglomerates. However, aspects related to the strength of agglomerates should also be considered. For this reason the Stokes abrasion number (St(Abr)) has been defined. This parameter describes the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. The St(Abr) number is shown to predict the abrasion potential of agglomerates in the dry-mixing process. It appeared possible to include effects of filler particle size and impeller rotational rate into this concept. A clear relationship between abrasion rate of agglomerates and the value of St(Abr) was demonstrated. Copyright © 2011 Elsevier B.V. All rights reserved.

Beyond cultural competency: Bourdieu, patients and clinical encounters.

Science.gov (United States)

Lo, Ming-Cheng M; Stacey, Clare L

2008-07-01

In response to widely documented racial and ethnic disparities in health, clinicians and public health advocates have taken great strides to implement 'culturally competent' care. While laudable, this important policy and intellectual endeavour has suffered from a lack of conceptual clarity and rigour. This paper develops a more careful conceptual model for understanding the role of culture in the clinical encounter, paying particular attention to the relationship between culture, contexts and social structures. Linking Bourdieu's (1977) notion of 'habitus' and William Sewell's (1992) axioms of multiple and intersecting structures, we theorise patient culture in terms of 'hybrid habitus'. This conceptualisation of patient culture highlights three analytical dimensions: the multiplicity of schemas and resources available to patients, their specific patterns of integration and application in specific contexts, and the constitutive role of clinical encounters. The paper concludes with a discussion of directions for future research as well as reforms of cultural competency training courses.

Control of respirable particles and radon progeny with portable air cleaners

International Nuclear Information System (INIS)

Offermann, F.J.; Sextro, R.G.; Fisk, W.J.; Nazaroff, W.W.; Nero, A.V.; Revzan, K.L.; Yater, J.

1984-02-01

Eleven portable air cleaning devices have been evaluated for control of indoor concentrations of respirable particles and radon progeny. Following injection of cigarette smoke and radon in a room-size chamber, decay rates for particles and radon progeny concentrations were measured with and without air cleaner operation. Particle concentrations were obtained for total number concentration and for number concentration by particle size. In tests with no air cleaner the natural decay rate for cigarette smoke was observed to be 0.2 hr -1 . Air cleaning rates for particles were found to be negligible for several small panel-filters, a residential ion-generator, and a pair of mixing fans. The electrostatic precipitators and extended surface filters tested had significant particle removal rates, and a HEPA-type filter was the most efficient air cleaner. The evaluation of radon progeny control produced similar results; the air cleaners which were effective in removing particles were also effective in removing radon progeny. At low particle concentrations plateout of the unattached radon progeny is an important removal mechanism. Based on data from these tests, the plateout rate for unattached progeny was found to be 15 hr -1 . The unattached fraction and the overall removal rate due to deposition of attached and unattached nuclides have been estimated for each radon decay product as a function of particle concentration. While air cleaning can be effective in reducing total radon progeny, concentrations of unattached radon progeny can increase with increasing air cleaning. 39 references, 26 figures, 9 tables

Physician as partner or salesman? Shared decision-making in real-time encounters.

Science.gov (United States)

Karnieli-Miller, Orit; Eisikovits, Zvi

2009-07-01

The results of recent research have led to the increased advocacy of shared decision-making regarding medical treatment. Nonetheless, only a limited number of studies have focused on the process of decision-making in real-time encounters. The present paper aims to document and analyze this process. Specifically, we assess whether these decisions are the result of partnership or of persuasive tactics based on power and hierarchical relationships. We will describe and analyze different strategies used by pediatric gastroenterologists in breaking bad news encounters, as well as their consequences. The analysis is based on a multi-method, multi-participant phenomenological study on breaking bad news to adolescents and their families regarding a chronic illness. It included 17 units of analysis (actual encounters and 52 interviews with physicians, parents and adolescents). Data were collected from three hospitals in Northern Israel using observations and audiotapes of diagnosis disclosure encounters and audio-taped interviews with all participants. The analysis identified eight different presentation tactics used in actual encounters during which physicians made various use of language, syntax and different sources of power to persuade patients to agree with their preferred treatment choice. The tactics included various ways of presenting the illness, treatment and side effects; providing examples from other success or failure stories; sharing the decision only concerning technicalities; and using plurals and authority. The findings suggest that shared decision-making may be advocated as a philosophical tenet or a value, but it is not necessarily implemented in actual communication with patients. Rather, treatment decisions tend to be unilaterally made, and a variety of persuasive approaches are used to ensure agreement with the physician's recommendation. The discussion is focused on the complexity of sharing a decision, especially in the initial bad news encounter

Unsteady Particle Deposition in a Human Nasal Cavity during Inhalation

Directory of Open Access Journals (Sweden)

Camby M.K. Se

2010-12-01

Full Text Available The present study investigates the deposition efficiency during the unsteady inhalation cycle by using Computational Fluid Dynamics (CFD. The unsteady inhalation profile was applied at the outlet of nasopharynx, which had a maximum flow rate of 40.3L/min which corresponds to an equivalent steady inhalation tidal volume flow rate of 24.6L/min. Aerodynamic particle sizes of 5μm and 20μm were studied in order to reflect contrasting Stokes numbered particle behaviour. Two particle deposition efficiencies in the nasal cavity versus time are presented. In general, the deposition of 5μm particles was much less than 20μm particles. The first 0.2 second of the inhalation cycle was found to be significant to the particle transport, since the majority of particles were deposited during this period (i.e. its residence time. Comparisons were also made with its equivalent steady inhalation flow rate which found that the unsteady inhalation produced lower deposition efficiency for both particle sizes.

Lattice gauge calculation in particle theory

International Nuclear Information System (INIS)

Barkai, D.; Moriarty, K.J.M.; Rebbi, C.; Brookhaven National Lab., Upton, NY

1985-01-01

There are many problems in particle physics which cannot be treated analytically, but are amenable to numcerical solution using today's most powerful computers. Prominent among such problems are those encountered in the theory of strong interactions, where the resolution of fundamental issues such as demonstrating quark confinement or evaluating hadronic structure is rooted in a successful description of the behaviour of a very large number of dynamical variables in non-linear interaction. This paper briefly outlines the mathematical problems met in the formulation of the quantum field theory for strong interactions, the motivation for numerical methods of resolution and the algorithms which are currently being used. Such algorithms require very large amounts of memory and computation and, because of their organized structure, are ideally suited for implementation on mainframes with vectorized architecture. While the details of the actual implementation will be coverd in other contributions to this conference, this paper will present an account of the most important physics results obtained up to now and will conclude with a survey of open problems in particle theory which could be solved numerically in the near future. (orig.)

Lattice gauge calculation in particle theory

International Nuclear Information System (INIS)

Barkai, D.; Moriarity, K.J.M.; Rebbi, C.

1985-01-01

There are many problems in particle physics which cannot be treated analytically, but are amenable to numerical solution using today's most powerful computers. Prominent among such problems are those encountered in the theory of strong interactions, where the resolution of fundamental issues such as demonstrating quark confinement or evaluating hadronic structure is rooted in a successful description of the behavior of a very large number of dynamical variables in non-linear interaction. This paper briefly outlines the mathematical problems met in the formulation of the quantum field theory for strong interactions, the motivation for numerical methods of resolution and the algorithms which are currently being used. Such algorithms require very large amounts of memory and computation and, because of their organized structure, are ideally suited for implementation on mainframes with vectorized architecture. While the details of the actual implementation will be covered in other contributions to this conference, this paper will present an account of the most important physics results obtained up to now and will conclude with a survey of open problems in particle theory which could be solved numerically in the near future

Lattice gauge calculation in particle theory

Energy Technology Data Exchange (ETDEWEB)

Barkai, D [Control Data Corp., Fort Collins, CO (USA); Moriarty, K J.M. [Dalhousie Univ., Halifax, Nova Scotia (Canada). Inst. for Computational Studies; Rebbi, C [European Organization for Nuclear Research, Geneva (Switzerland); Brookhaven National Lab., Upton, NY (USA). Physics Dept.)

1985-05-01

There are many problems in particle physics which cannot be treated analytically, but are amenable to numcerical solution using today's most powerful computers. Prominent among such problems are those encountered in the theory of strong interactions, where the resolution of fundamental issues such as demonstrating quark confinement or evaluating hadronic structure is rooted in a successful description of the behaviour of a very large number of dynamical variables in non-linear interaction. This paper briefly outlines the mathematical problems met in the formulation of the quantum field theory for strong interactions, the motivation for numerical methods of resolution and the algorithms which are currently being used. Such algorithms require very large amounts of memory and computation and, because of their organized structure, are ideally suited for implementation on mainframes with vectorized architecture. While the details of the actual implementation will be coverd in other contributions to this conference, this paper will present an account of the most important physics results obtained up to now and will conclude with a survey of open problems in particle theory which could be solved numerically in the near future.

In situ measurement of mesopelagic particle sinking rates and the control of carbon transfer to the ocean interior during the Vertical Flux in the Global Ocean (VERTIGO) voyages in the North Pacific

Science.gov (United States)

Trull, T. W.; Bray, S. G.; Buesseler, K. O.; Lamborg, C. H.; Manganini, S.; Moy, C.; Valdes, J.

2008-07-01

Among the parameters affecting carbon transfer to the ocean interior, particle sinking rates vary three orders of magnitude and thus more than primary production, f-ratios, or particle carbon contents [e.g., Boyd, P.W., Trull, T.W., 2006. Understanding the export of marine biogenic particles: is there consensus? Progress in Oceanography 4, 276-312, doi:10.1016/j.pocean.2006.10.007]. Very few data have been obtained from the mesopelagic zone where the majority of carbon remineralization occurs and the attenuation of the sinking flux is determined. Here, we report sinking rates from ˜300 m depth for the subtropical (station ALOHA, June 2004) and subarctic (station K2, July 2005) North Pacific Ocean, obtained from short (6.5 day) deployments of an indented rotating sphere (IRS) sediment trap operating as an in situ settling column [Peterson, M.L., Wakeham, S.G., Lee, C., Askea, M.A., Miquel, J.C., 2005. Novel techniques for collection of sinking particles in the ocean and determining their settling rates. Limnology and Oceanography Methods 3, 520-532] to separate the flux into 11 sinking-rate fractions ranging from >820 to >2 m d -1 that are collected by a carousel for further analysis. Functioning of the IRS trap was tested using a novel programming sequence to check that all particles have cleared the settling column prior to the next delivery of particles by the 6-hourly rotation cycle of the IRS. There was some evidence (from the flux distribution among the cups and photomicroscopy of the collected particles) that very slow-sinking particles may have been under-collected because they were unable to penetrate the brine-filled collection cups, but good evidence for appropriate collection of fast-settling fractions. Approximately 50% of the particulate organic carbon (POC) flux was sinking at greater than 100 m d -1 at both stations. At ALOHA, more than 15% of the POC flux sank at >820 m d -1, but low fluxes make this uncertain, and precluded resolution of particles

Concentration and size distribution of particles in abstracted groundwater.

Science.gov (United States)

van Beek, C G E M; de Zwart, A H; Balemans, M; Kooiman, J W; van Rosmalen, C; Timmer, H; Vandersluys, J; Stuyfzand, P J

2010-02-01

Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of larger particles. However, the particle concentration in groundwater derived from abstraction wells, with high groundwater flow velocities, is much lower than in groundwater from monitor wells, with minimal flow velocities. This inconsistency points to exhaustion of the particle supply in the aquifer around wells due to groundwater abstraction for many years. The particle size distribution can be described with the help of a power law or Pareto distribution. Comparing the measured particle size distribution with the Pareto distribution shows that particles with a diameter >7 microm are under-represented. As the particle size distribution is dependent on the flow velocity, so is the value of the "Pareto" slope beta. (c) 2009 Elsevier Ltd. All rights reserved.

VizieR Online Data Catalog: Stellar encounters with long-period comets (Feng+, 2015)

Science.gov (United States)

Feng, F.; Bailer-Jones, C. A. L.

2016-07-01

We have conducted simulations of the perturbation of the Oort cloud in order to estimate the significance of known encounters in generating long-period comets. We collected the data of stellar encounters from three sources: (Bailer-Jones, 2015, Cat. J/A+A/575/A35, hereafter BJ15), Dybczynski & Berski (2015MNRAS.449.2459D), and Mamajek et al. (2015ApJ...800L..17M). Following BJ15, we use the term 'object' to refer to each encountering star in our catalogue. A specific star may appear more than once but with different data, thus leading to a different object. (1 data file).

Stochastic motion of particles in tandem mirror devices

International Nuclear Information System (INIS)

Ichikawa, Y.H.; Kamimura, T.

1982-01-01

Stochastic motion of particles in tandem mirror devices is examined on basis of a nonlinear mapping of particle positions on the equatorial plane. Local stability analysis provides detailed informations on particle trajectories. The rate of stochastic plasma diffusion is estimated from numerical observations of motions of particles over a large number of time steps. (author)

Assessing the environmental risk from hot particles in the vicinity of Dounreay-a case for inaction?

International Nuclear Information System (INIS)

Jackson, D; Stone, D M; Smith, K; Morgan, G; Shimmield, T

2007-01-01

This study assesses the impact on species other than humans associated with radioactive particles present in the marine environment close to the UKAEA Dounreay site, through a review of marine survey data, to establish the distribution of species and the likelihood of encountering a particle, and considering retention, dissolution or absorption of the particle. Assumptions are made regarding particle density, distribution, size and bio-availability of the radioactive materials. From this, impacts are assessed against the likelihood of mortality or other significant harm to individuals and interpreted in terms of local populations. Results obtained indicate that no significant impact, at the population level, is likely to be observed. This does not preclude that some individuals will be affected. It does, however, suggest that any decision to remediate, if based predominantly on environmental considerations, should be cognisant of the damage caused by remediation itself and subsequent exploitation of the environment by humans

Reflexivity: The Creation of Liminal Spaces--Researchers, Participants, and Research Encounters.

Science.gov (United States)

Enosh, Guy; Ben-Ari, Adital

2016-03-01

Reflexivity is defined as the constant movement between being in the phenomenon and stepping outside of it. In this article, we specify three foci of reflexivity--the researcher, the participant, and the encounter--for exploring the interview process as a dialogic liminal space of mutual reflection between researcher and participant. Whereas researchers' reflexivity has been discussed extensively in the professional discourse, participants' reflexivity has not received adequate scholarly attention, nor has the promise inherent in reflective processes occurring within the encounter. © The Author(s) 2015.

Concentration and size distribution of particles in abstracted groundwater

NARCIS (Netherlands)

Van Beek, C.G.E.M.; de Zwart, A.H.; Balemans, M.; Kooiman, J.W.; van Rosmalen, C.; Timmer, H.; Vandersluys, J.; Stuijfzand, P.J.

2010-01-01

Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of

Initiator Systems Effect on Particle Coagulation and Particle Size Distribution in One-Step Emulsion Polymerization of Styrene

Directory of Open Access Journals (Sweden)

Baijun Liu

2016-02-01

Full Text Available Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.

Dental case manager encounters: the association with retention in dental care and treatment plan completion.

Science.gov (United States)

Lemay, Celeste A; Tobias, Carol; Umez-Eronini, Amarachi A; Brown, Carolyn; McCluskey, Amanda; Fox, Jane E; Bednarsh, Helene; Cabral, Howard J

2013-01-01

Little is known about dental case managers as few programs have been scientifically evaluated. The goal of this study was to explore the impact of dental case manager on retention in dental care and completion of treatment plans, while specifically exploring the number of dental case manager encounters. Fourteen programs enrolled people with HIV/AIDS (PLWHA) in dental care and a longitudinal study between 2007 and 2009. The 758 participants had a total of 2715 encounters with a dental case manager over twelve months: 29% had a single encounter; 21% had two; 27% had 3-4 and; 23% had 5-29 encounters. Adjusting for baseline characteristics, participants receiving more encounters were significantly more likely to complete their Phase 1 treatment plan, be retained in dental care, and experience improvements in overall oral health status. Organizations considering efforts to improve the oral health of vulnerable, hard-to-engage populations should consider these findings when planning interventions. ©2012 Special Care Dentistry Association and Wiley Periodicals, Inc.

Does assisted driving behavior lead to safety-critical encounters with unequipped vehicles' drivers?

Science.gov (United States)

Preuk, Katharina; Stemmler, Eric; Schießl, Caroline; Jipp, Meike

2016-10-01

With Intelligent Transport Systems (e.g., traffic light assistance systems) assisted drivers are able to show driving behavior in anticipation of upcoming traffic situations. In the years to come, the penetration rate of such systems will be low. Therefore, the majority of vehicles will not be equipped with these systems. Unequipped vehicles' drivers may not expect the driving behavior of assisted drivers. However, drivers' predictions and expectations can play a significant role in their reaction times. Thus, safety issues could arise when unequipped vehicles' drivers encounter driving behavior of assisted drivers. This is why we tested how unequipped vehicles' drivers (N=60) interpreted and reacted to the driving behavior of an assisted driver. We used a multi-driver simulator with three drivers. The three drivers were driving in a line. The lead driver in the line was a confederate who was followed by two unequipped vehicles' drivers. We varied the equipment of the confederate with an Intelligent Transport System: The confederate was equipped either with or without a traffic light assistance system. The traffic light assistance system provided a start-up maneuver before a light turned green. Therefore, the assisted confederate seemed to show unusual deceleration behavior by coming to a halt at an unusual distance from the stop line at the red traffic light. The unusual distance was varied as we tested a moderate (4m distance from the stop line) and an extreme (10m distance from the stop line) parameterization of the system. Our results showed that the extreme parametrization resulted in shorter minimal time-to-collision of the unequipped vehicles' drivers. One rear-end crash was observed. These results provided initial evidence that safety issues can arise when unequipped vehicles' drivers encounter assisted driving behavior. We recommend that future research identifies counteractions to prevent these safety issues. Moreover, we recommend that system developers

Application of particle swarm optimisation for solving deteriorating inventory model with fluctuating demand and controllable deterioration rate

Science.gov (United States)

Chen, Yu-Ren; Dye, Chung-Yuan

2013-06-01

In most of the inventory models in the literature, the deterioration rate of goods is viewed as an exogenous variable, which is not subject to control. In the real market, the retailer can reduce the deterioration rate of product by making effective capital investment in storehouse equipments. In this study, we formulate a deteriorating inventory model with time-varying demand by allowing preservation technology cost as a decision variable in conjunction with replacement policy. The objective is to find the optimal replenishment and preservation technology investment strategies while minimising the total cost over the planning horizon. For any given feasible replenishment scheme, we first prove that the optimal preservation technology investment strategy not only exists but is also unique. Then, a particle swarm optimisation is coded and used to solve the nonlinear programming problem by employing the properties derived from this article. Some numerical examples are used to illustrate the features of the proposed model.

Particle Emissions from Domestic Gas Cookers

DEFF Research Database (Denmark)

Glarborg, Peter; Livbjerg, Hans; Wagner, Ayten Yilmaz

2010-01-01

The authors experimentally studied the formation of submicron particles from a domestic gas cooker in a compartment free from external particle sources. The effects of fuel (methane, natural gas, odorant-free natural gas), primary aeration, flow rate, and fuel sulphur content on particle emissions...... of the emitted particles were found to have a mean value of about 7 nm for partially premixed flames, increasing to ∼10 nm for nonpremixed flames. The quantity of primary air had a strong impact on the particle emissions, showing a minimum at a primary aeration level of 60-65%. Presence of sulphur in small...... quantities may enhance particle formation under some conditions, but results were not conclusive....

Recent Observations of Energetic Particles from the Voyager Spacecraft

Science.gov (United States)

Cummings, A. C.; Stone, E. C.; Heikkila, B.; Lal, N.; Webber, W. R.

2013-05-01

The Voyager spacecraft have been exploring the heliosheath since their crossings of the solar wind termination shock on December 2004 (Voyager 1) and August 2007 (Voyager 2). Starting on 7 May 2012, dramatic short-term changes in the intensities of heliospheric particles and galactic cosmic rays have been occurring periodically at Voyager 1. In July, a series of encounters with a heliospheric depletion region occurred, culminating on 25 August 2012 with the durable entry into the region by Voyager 1 (durable at least through the time of this writing in early February 2012). This depletion region is characterized by the disappearance of particles accelerated in the heliosphere, the anomalous cosmic rays and termination shock particles, and the increased intensity of galactic cosmic ray nuclei and electrons. The result is that the low-energy part of the galactic cosmic ray spectra is being revealed for the first time. Data from the magnetometer experiment on Voyager 1 implies that the spacecraft is not yet in the interstellar medium, but it apparently has a good connection path to it. At Voyager 2, dramatic changes haven't occurred but there are longer-term trends in the intensities that are different from what were observed on Voyager 1. We will report on the recent observations of energetic particles from both spacecraft. This work was supported by NASA under contract NNN12AA012.

Preliminary Uncorrelated Encounter Model of the National Airspace System

National Research Council Canada - National Science Library

Kochenderfer, M. J; Kuchar, J. K; Espindle, L. P; Gertz, J. L

2008-01-01

...) and which may not be in contact with air traffic control. In response to the need to develop a model of these types of encounters, Lincoln Laboratory undertook an extensive radar data collection and modeling effort...

Grassroots Leadership: Encounters with Power Dynamics and Oppression

Science.gov (United States)

Kezar, Adrianna

2011-01-01

This article focuses on the nature of power dynamics that faculty and staff grassroots leaders encounter as they attempt to create change. I identified five distinctive types of power dynamics--"oppression," "silencing," "controlling," "inertia," and "micro-aggressions" from the most overt to more subtle and covert forms. Staff experience multiple…

Stress Coping Techniques For Female Doctors Encountering Sexual ...

African Journals Online (AJOL)

... Muslim and Christian female doctors encounter with sexual harassment. It was also found that sexual harassment cut across all age groups. The findings of these study indicated that stress coping techniques is an effective method in the reduction of stress posed by sexual harassment on female doctors from their patients.

First results from the RAPID imaging energetic particle spectrometer on board Cluster

Directory of Open Access Journals (Sweden)

B. Wilken

2001-09-01

Full Text Available The advanced energetic particle spectrometer RAPID on board Cluster can provide a complete description of the relevant particle parameters velocity, V , and atomic mass, A, over an energy range from 30 keV up to 1.5 MeV. We present the first measurements taken by RAPID during the commissioning and the early operating phases. The orbit on 14 January 2001, when Cluster was travelling from a perigee near dawn northward across the pole towards an apogee in the solar wind, is used to demonstrate the capabilities of RAPID in investigating a wide variety of particle populations. RAPID, with its unique capability of measuring the complete angular distribution of energetic particles, allows for the simultaneous measurements of local density gradients, as reflected in the anisotropies of 90° particles and the remote sensing of changes in the distant field line topology, as manifested in the variations of loss cone properties. A detailed discussion of angle-angle plots shows considerable differences in the structure of the boundaries between the open and closed field lines on the nightside fraction of the pass and the magnetopause crossing. The 3 March 2001 encounter of Cluster with an FTE just outside the magnetosphere is used to show the first structural plasma investigations of an FTE by energetic multi-spacecraft observations.Key words. Magnetospheric physics (energetic particles, trapped; magnetopause, cusp and boundary layers; magnetosheath

Social Workers' Reflections on the Therapeutic Encounter With Elder Abuse and Neglect.

Science.gov (United States)

Goldblatt, Hadass; Band-Winterstein, Tova; Alon, Sara

2016-02-24

The aim of this qualitative study was to explore social workers' reflections on their experience of the therapeutic encounter with victims and perpetrators of elder abuse and neglect. The research questions were as follows: How do social workers tune themselves toward the therapeutic encounter with elder abuse? How do they position themselves vis-à-vis the clients? How do social workers describe the meaning of the intervention both for the clients and for themselves? What is the added value of the therapeutic encounter in this field for the social workers? Participants were 17 experienced women social workers, who worked with abusers and with abused and neglected older adults in Israel. Data were collected via in-depth semi-structured interviews, which were later transcribed and content analyzed. Two main themes emerged from the findings, emphasizing two key aspects of the social workers' reflective process experienced during the therapeutic encounter: (a) focus on the client: "This is the journey of their lives"-reflection on the therapeutic "journey"; (b) focus on the social worker's inner and professional world: "'There is nothing to be done' is no longer in my vocabulary"-a personal and professional maturation process. The social workers expressed a positive attitude toward their elder clients. A unique dialogue developed in the therapeutic encounter, whereby the social workers considered any change as valuable if it allowed the elders a sense of control and self-worth, whereas the social workers were enriched by the elders' life experience, and matured both personally and professionally. Thus, both sides benefited from this reciprocal relationship. Implications for further research and practice are discussed. © The Author(s) 2016.

Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?

Energy Technology Data Exchange (ETDEWEB)

Zhao, G. Q.; Feng, H. Q. [Institute of Space Physics, Luoyang Normal University, Luoyang (China); Wu, D. J. [Purple Mountain Observatory, CAS, Nanjing (China); Chu, Y. H. [Institute of Space Science, National Central University, Chungli, Taiwan (China); Huang, J. [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing (China)

2017-09-20

Previous studies revealed that electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency exist widely in the solar wind, and the majority of ECWs are left-handed (LH) polarized waves. Using the magnetic field data from the STEREO mission, this Letter carries out a survey of ECWs over a long period of 7 years and calculates the occurrence rates of ECWs with different polarization senses. Results show that the occurrence rate is nearly a constant for the ECWs with right-handed polarization, but it varies significantly for the ECWs with LH polarization. Further investigation of plasma conditions reveals that the LH ECWs take place preferentially in a plasma characterized by higher temperature, lower density, and larger velocity. Some considerable correlations between the occurrence rate of LH ECWs and the properties of ambient plasmas are discussed. The present research may provide evidence for the effect of alpha particles on the generation of ECWs.