An overview of experimental results and dispersion modelling of nanoparticles in the wake of moving vehicles.

PubMed

Carpentieri, Matteo; Kumar, Prashant; Robins, Alan

2011-03-01

Understanding the transformation of nanoparticles emitted from vehicles is essential for developing appropriate methods for treating fine scale particle dynamics in dispersion models. This article provides an overview of significant research work relevant to modelling the dispersion of pollutants, especially nanoparticles, in the wake of vehicles. Literature on vehicle wakes and nanoparticle dispersion is reviewed, taking into account field measurements, wind tunnel experiments and mathematical approaches. Field measurements and modelling studies highlighted the very short time scales associated with nanoparticle transformations in the first stages after the emission. These transformations strongly interact with the flow and turbulence fields immediately behind the vehicle, hence the need of characterising in detail the mixing processes in the vehicle wake. Very few studies have analysed this interaction and more research is needed to build a basis for model development. A possible approach is proposed and areas of further investigation identified. Copyright © 2010 Elsevier Ltd. All rights reserved.

Characterisation of longitudinal variation in photonic crystal fibre

NASA Astrophysics Data System (ADS)

Francis-Jones, Robert J. A.; Mosley, Peter J.

2016-10-01

We present a method by which the degree of longitudinal variation in photonic crystal fibre (PCF) may be characterised through seeded four-wave mixing (FWM). Using an iterative numerical reconstruction, we created a model PCF that displays similar FWM phasematching properties across all measured length scales. Our results demonstrate that the structure of our PCF varies by less than 1% and that the characteristic length of the variations is approximately 15 cm.

Differentiated Financing of Schools in French-Speaking Belgium: Prospectives for Regulating a School Quasi-Market

ERIC Educational Resources Information Center

Demeuse, Marc; Derobertmasure, Antoine; Friant, Nathanael

2010-01-01

The school quasi-market in French-speaking Belgium is characterised by segregation. Efforts to apply measures that encourage greater social mixing have met with stiff resistance. In 2008 and 2009, turbulence was caused by the application of the "social mixing" law influencing the registration procedures. The purpose of this article is to…

High spatial resolution microdosimetry with monolithic ΔE-E detector on 12C beam: Monte Carlo simulations and experiment

NASA Astrophysics Data System (ADS)

Tran, Linh T.; Bolst, David; Guatelli, Susanna; Biasi, Giordano; Fazzi, Alberto; Sagia, Eleni; Prokopovich, Dale A.; Reinhard, Mark I.; Keat, Ying C.; Petasecca, Marco; Lerch, Michael L. F.; Pola, Andrea; Agosteo, Stefano; Matsufuji, Naruhiro; Jackson, Michael; Rosenfeld, Anatoly B.

2018-04-01

Nuclear fragmentation produced in 12C ion therapeutic beams contributes significantly to the Relative Biological Effectiveness (RBE)-weighted dose in the distal edge of the Spread out Bragg Peak (SOBP) and surrounding tissues in out-of-field. Complex mixed radiation field originated by the therapeutic 12C ion beam in a phantom is difficult to measure. This study presents a new method to characterise the radiation field produced in a 12C ion beam using a monolithic ΔE-E telescope which provides the capability to identify the particle components of the mixed radiation field as well as the microdosimetric spectra that allows derivation of the RBE based on a radiobiological model. The response of the monolithic ΔE-E telescope to a 290 MeV/u 12C ion beam at defined positions along the pristine Bragg Peak was studied using the Geant4 Monte Carlo toolkit. The microdosimetric spectra derived from the ΔE stage and the two-dimensional scatter plots of energy deposition in ΔE and E stages of the device in coincidence are presented, as calculated in-field and out-of-field. Partial dose weighted contribution to the microdosimetric spectra from nuclear fragments and recoils, such as 1H, 4He, 3He, 7Li, 9Be and 11B, have been analysed for each position. Comparison of simulation and experimental results are presented and demonstrates that the microdosimetric spectra changes dramatically within 0.5 mm depth increments close to and at the distal edge of the Bragg Peak which is impossible to identify using conventional Tissue Equivalent Proportional Counter (TEPC).

Uncovering a Hidden Professional Agenda for Teacher Educators: A Mixed Method Study on Flemish Teacher Educators and Their Professional Development

ERIC Educational Resources Information Center

Tack, Hanne; Valcke, Martin; Rots, Isabel; Struyven, Katrien; Vanderlinde, Ruben

2018-01-01

Taking into account the pressing need to understand more about what teacher educators' professional development characterises, this article adopts a mixed method approach to explore Flemish (Dutch-speaking part of Belgium) teacher educators' professional development needs and opportunities. Analysis results of a large-scale survey study with 611…

A review of cognitive biases in youth depression: attention, interpretation and memory.

PubMed

Platt, Belinda; Waters, Allison M; Schulte-Koerne, Gerd; Engelmann, Lina; Salemink, Elske

2017-04-01

Depression is one of the most common mental health problems in childhood and adolescence. Although data consistently show it is associated with self-reported negative cognitive styles, less is known about the mechanisms underlying this relationship. Cognitive biases in attention, interpretation and memory represent plausible mechanisms and are known to characterise adult depression. We provide the first structured review of studies investigating the nature and causal role of cognitive biases in youth depression. Key questions are (i) do cognitive biases characterise youth depression? (ii) are cognitive biases a vulnerability factor for youth depression? and (iii) do cognitive biases play a causal role in youth depression? We find consistent evidence for positive associations between attention and interpretation biases and youth depression. Stronger biases in youth with an elevated risk of depression support cognitive-vulnerability models. Preliminary evidence from cognitive bias modification paradigms supports a causal role of attention and interpretation biases in youth depression but these paradigms require testing in clinical samples before they can be considered treatment tools. Studies of memory biases in youth samples have produced mixed findings and none have investigated the causal role of memory bias. We identify numerous areas for future research in this emerging field.

Analysis system for characterisation of simple, low-cost microfluidic components

NASA Astrophysics Data System (ADS)

Smith, Suzanne; Naidoo, Thegaran; Nxumalo, Zandile; Land, Kevin; Davies, Emlyn; Fourie, Louis; Marais, Philip; Roux, Pieter

2014-06-01

There is an inherent trade-off between cost and operational integrity of microfluidic components, especially when intended for use in point-of-care devices. We present an analysis system developed to characterise microfluidic components for performing blood cell counting, enabling the balance between function and cost to be established quantitatively. Microfluidic components for sample and reagent introduction, mixing and dispensing of fluids were investigated. A simple inlet port plugging mechanism is used to introduce and dispense a sample of blood, while a reagent is released into the microfluidic system through compression and bursting of a blister pack. Mixing and dispensing of the sample and reagent are facilitated via air actuation. For these microfluidic components to be implemented successfully, a number of aspects need to be characterised for development of an integrated point-of-care device design. The functional components were measured using a microfluidic component analysis system established in-house. Experiments were carried out to determine: 1. the force and speed requirements for sample inlet port plugging and blister pack compression and release using two linear actuators and load cells for plugging the inlet port, compressing the blister pack, and subsequently measuring the resulting forces exerted, 2. the accuracy and repeatability of total volumes of sample and reagent dispensed, and 3. the degree of mixing and dispensing uniformity of the sample and reagent for cell counting analysis. A programmable syringe pump was used for air actuation to facilitate mixing and dispensing of the sample and reagent. Two high speed cameras formed part of the analysis system and allowed for visualisation of the fluidic operations within the microfluidic device. Additional quantitative measures such as microscopy were also used to assess mixing and dilution accuracy, as well as uniformity of fluid dispensing - all of which are important requirements towards the successful implementation of a blood cell counting system.

Characterisation of the Interaction between Toroidal Vortex Structures and Flame Front Propagation

NASA Astrophysics Data System (ADS)

Long, E. J.; Hargrave, G. K.; Jarvis, S.; Justham, T.; Halliwell, N.

2006-07-01

Experimental laser diagnostic data is presented for flame characterisation during interactions with toroidal vortices generated in the wake of an annular obstacle. A novel twin section combustion chamber has been utilised to allow the controlled formation of stable eddy structures into which a flame front can propagate. High speed laser sheet visualisation was employed to record the flow field and flame front temporal development and high-speed digital particle image velocimetry was used to quantify the velocity field of the unburnt mixture ahead of the flame front. Results provide characterisation of the toroidal vortex/flame front interaction for a range of vortex scales of and recirculation strengths.

A Proposed Extension to the Soil Moisture and Ocean Salinity Level 2 Algorithm for Mixed Forest and Moderate Vegetation Pixels

NASA Technical Reports Server (NTRS)

Panciera, Rocco; Walker, Jeffrey P.; Kalma, Jetse; Kim, Edward

2011-01-01

The Soil Moisture and Ocean Salinity (SMOS)mission, launched in November 2009, provides global maps of soil moisture and ocean salinity by measuring the L-band (1.4 GHz) emission of the Earth's surface with a spatial resolution of 40-50 km.Uncertainty in the retrieval of soilmoisture over large heterogeneous areas such as SMOS pixels is expected, due to the non-linearity of the relationship between soil moisture and the microwave emission. The current baseline soilmoisture retrieval algorithm adopted by SMOS and implemented in the SMOS Level 2 (SMOS L2) processor partially accounts for the sub-pixel heterogeneity of the land surface, by modelling the individual contributions of different pixel fractions to the overall pixel emission. This retrieval approach is tested in this study using airborne L-band data over an area the size of a SMOS pixel characterised by a mix Eucalypt forest and moderate vegetation types (grassland and crops),with the objective of assessing its ability to correct for the soil moisture retrieval error induced by the land surface heterogeneity. A preliminary analysis using a traditional uniform pixel retrieval approach shows that the sub-pixel heterogeneity of land cover type causes significant errors in soil moisture retrieval (7.7%v/v RMSE, 2%v/v bias) in pixels characterised by a significant amount of forest (40-60%). Although the retrieval approach adopted by SMOS partially reduces this error, it is affected by errors beyond the SMOS target accuracy, presenting in particular a strong dry bias when a fraction of the pixel is occupied by forest (4.1%v/v RMSE,-3.1%v/v bias). An extension to the SMOS approach is proposed that accounts for the heterogeneity of vegetation optical depth within the SMOS pixel. The proposed approach is shown to significantly reduce the error in retrieved soil moisture (2.8%v/v RMSE, -0.3%v/v bias) in pixels characterised by a critical amount of forest (40-60%), at the limited cost of only a crude estimate of the optical depth of the forested area (better than 35% uncertainty). This study makes use of an unprecedented data set of airborne L-band observations and ground supporting data from the National Airborne Field Experiment 2005 (NAFE'05), which allowed accurate characterisation of the land surface heterogeneity over an area equivalent in size to a SMOS pixel.

Non-Noble Metal Oxide Catalysts for Methane Catalytic Combustion: Sonochemical Synthesis and Characterisation

PubMed Central

Jędrzejczyk, Roman J.; Dziedzicka, Anna; Kuterasiński, Łukasz; Sitarz, Maciej

2017-01-01

The aim of this study was to obtain nanocrystalline mixed metal-oxide–ZrO2 catalysts via a sonochemically-induced preparation method. The effect of a stabiliser’s addition on the catalyst parameters was investigated by several characterisation methods including X-ray Diffraction (XRD), nitrogen adsorption, X-ray fluorescence (XRF), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and µRaman. The sonochemical preparation method allowed us to manufacture the catalysts with uniformly dispersed metal-oxide nanoparticles at the support surface. The catalytic activity was tested in a methane combustion reaction. The activity of the catalysts prepared by the sonochemical method was higher than that of the reference catalysts prepared by the incipient wetness method without ultrasonic irradiation. The cobalt and chromium mixed zirconia catalysts revealed their high activities, which are comparable with those presented in the literature. PMID:28686190

Characterisation and modelling of mixing processes in groundwaters of a potential geological repository for nuclear wastes in crystalline rocks of Sweden.

PubMed

Gómez, Javier B; Gimeno, María J; Auqué, Luis F; Acero, Patricia

2014-01-15

This paper presents the mixing modelling results for the hydrogeochemical characterisation of groundwaters in the Laxemar area (Sweden). This area is one of the two sites that have been investigated, under the financial patronage of the Swedish Nuclear Waste and Management Co. (SKB), as possible candidates for hosting the proposed repository for the long-term storage of spent nuclear fuel. The classical geochemical modelling, interpreted in the light of the palaeohydrogeological history of the system, has shown that the driving process in the geochemical evolution of this groundwater system is the mixing between four end-member waters: a deep and old saline water, a glacial meltwater, an old marine water, and a meteoric water. In this paper we put the focus on mixing and its effects on the final chemical composition of the groundwaters using a comprehensive methodology that combines principal component analysis with mass balance calculations. This methodology allows us to test several combinations of end member waters and several combinations of compositional variables in order to find optimal solutions in terms of mixing proportions. We have applied this methodology to a dataset of 287 groundwater samples from the Laxemar area collected and analysed by SKB. The best model found uses four conservative elements (Cl, Br, oxygen-18 and deuterium), and computes mixing proportions with respect to three end member waters (saline, glacial and meteoric). Once the first order effect of mixing has been taken into account, water-rock interaction can be used to explain the remaining variability. In this way, the chemistry of each water sample can be obtained by using the mixing proportions for the conservative elements, only affected by mixing, or combining the mixing proportions and the chemical reactions for the non-conservative elements in the system, establishing the basis for predictive calculations. © 2013 Elsevier B.V. All rights reserved.

Are manic symptoms that 'dip' into depression the essence of mixed features?

PubMed

Malhi, Gin S; Fritz, Kristina; Allwang, Christine; Burston, Nicole; Cocks, Chris; Devlin, Jill; Harper, Margaret; Hoadley, Ben; Kearney, Brian; Klug, Peter; Meagher, Linton; Rowe, Mark; Samir, Hany; Way, Raymond; Wilson, Craig; Lyndon, William

2016-03-01

Three symptoms of (hypo)mania that clinically represent mood disorders mixed states have been omitted from the DSM-5 mixed features specifier because 'they fail to discriminate between manic and depressive syndromes'. Therefore, the present study examined the role of distractibility, irritability and psychomotor agitation (DIP) in characterising mixed depressive states. Fifty in-patients at a specialist mood disorders unit underwent a detailed longitudinal clinical evaluation (3-6 weeks) and were assessed on a range of standardized measures to characterise their illness according to depression subtype, duration of illness and clinical features-including specifically depressive and manic symptoms and the context in which these occur. 49 patients met criteria for major depressive episode, and of these, 34 experienced at least one dip symptom. Patients who endorsed distractibility were more likely to be diagnosed with Bipolar Disorder than Major Depressive Disorder; patients who endorsed irritable mood were more likely to have non-melancholic depression (admixture of depressive and anxiety symptoms), and patients who reported psychomotor agitation experienced a significantly greater number of distinct periods of (hypo)manic symptoms compared with those who did not. The present study used a modest sample size and did not control for medication or comorbid illness. Although this is inevitable when examining real-world patients in a naturalistic setting, future research needs to allow for comorbidity and its impact, specifically anxiety. The present findings suggest that all 3 symptoms that have been excluded from DSM-5 may be cardinal features of mixed states, as they 'dip' into depressive symptoms to create a mixed state. Copyright © 2015 Elsevier B.V. All rights reserved.

Asymmetrical flow field-flow fractionation for human serum albumin based nanoparticle characterisation and a deeper insight into particle formation processes.

PubMed

John, C; Langer, K

2014-06-13

Nanoparticles used as drug delivery systems are of growing interest in the pharmaceutical field. Understanding the behaviour and effects of nanosystems in the human body is dependent on comprehensive characterisation of the systems especially with regard to size and size distribution. Asymmetrical flow field-flow fractionation (AF4) is a promising method for this challenge as this technique enables chromatographic separation of particles and solute molecules according to their respective size. Within this study AF4 was used for the characterisation of human serum albumin (HSA) based nanoparticles. In a first part, the most important aspects of method development like the choice of cross flow rate, focusing and the increase of sample concentration via outlet stream splitting on the sample separation were evaluated. Sample fractionation was controlled by inline-coupling of a dynamic light scattering detector (DLS, Zetasizer) and was confirmed by DLS batch mode measurements. In a second part the applicability of field-flow fractionation for characterisation of the HSA particle formation process by a desolvation method was evaluated. A time dependent particle formation was observed which was controlled by the amount of desolvating agent. Furthermore, field-flow fractionation in combination with in-line dynamic light scattering was used to monitor the increase of particle diameter during PEGylation of the resulting HSA nanoparticles. The separation of nanoparticles from dissolved polyethylene glycol (PEG) could successfully be used for determination of the particles' PEGylation degree. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrodynamic characteristics and mixing behaviour of Sclerotium glucanicum culture fluids in an airlift reactor with an internal loop used for scleroglucan production.

PubMed

Kang, X; Wang, H; Wang, Y; Harvey, L M; McNeil, B

2001-10-01

The filamentous fungus, Sclerotium glucanicum NRRL 3006, was cultivated in a 0.008 m(3) airlift bioreactor with internal recirculation loop (ARL-IL) for production of the biopolymer, scleroglucan. The rheological behaviour of the culture fluid was characterised by measurement of the fluid consistency coefficient (K) and the flow behaviour index (n). Based on these measurements, the culture fluid changed from a low viscosity Newtonian system early in the process, to a viscous non-Newtonian (pseudoplastic) system. In addition, reactor hydrodynamics and mixing behaviour were characterised by measurement of whole mean gas hold-up (epsilon(g)), liquid re-circulation velocity (U(ld)) and mixing time (t(m)). Under identical process conditions, the effects of the viscosity of the culture fluid and air flow rate on epsilon(g), U(ld) and t(m) were examined and empirical correlations for epsilon(g), U(ld) and t(m) with both superficial velocity U(g) and consistency coefficient K were obtained and expressed separately. The correlations obtained are likely to describe the behaviour of real fungal culture fluids more accurately than previous correlations based on Newtonian or simulated non-Newtonian systems.

Eclectic lefty-hand: Conjectures on Jimi Hendrix, handedness, and Electric Ladyland.

PubMed

Christman, Stephen

2010-01-01

An analysis of Jimi Hendrix's guitar playing and song writing is presented in light of the effects of his mixed-right-handedness on motoric and conceptual processing. It is argued that (i) his mixed-handedness allowed him greater integration of the roles of his left and right hands in guitar playing and (ii) his right-handedness conferred specific benefits in playing a left-handed guitar. In terms of his song writing, the greater interhemispheric interaction (and consequent greater access to right hemisphere processing) associated with mixed-handedness is argued to characterise aspects of his lyrics and vocal delivery.

Fast novel nonlinear optical NLC system with local response

NASA Astrophysics Data System (ADS)

Iljin, Andrey; Residori, Stefania; Bortolozzo, Umberto

2017-06-01

Nonlinear optical performance of a novel liquid crystalline (LC) cell has been studied in two-wave mixing experiments revealing high diffraction efficiency within extremely wide intensity range, fast recording times and spatial resolution. Photo-induced modulation of the LC order parameter resulting from trans-cis isomerisation of dye molecules causes consequent changes of refractive indices of the medium (Light-Induced Order Modification, LIOM-mechanism) and is proved to be the main mechanism of optical nonlinearity. The proposed arrangement of the electric-field-stabilised homeotropic alignment hinders the LC director reorientation, prevents appearance of surface effects and ensures the optical cell quality. The LIOM-type nonlinearity, characterised with the substantially local nonlinear optical response, could also be extended for the recording of arbitrary phase profiles as requested in several applications for light-beam manipulation, recording of dynamic volume holograms and photonic lattices.

Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt

PubMed Central

Al-Mansob, Ramez A.; Ismail, Amiruddin; Yusoff, Nur Izzi Md.; Rahmat, Riza Atiq O. K.; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

2017-01-01

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR–asphalt mixes prepared using the wet process. Mechanical testing on the ENR–asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR–asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR–asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress. PMID:28182724

Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt.

PubMed

Al-Mansob, Ramez A; Ismail, Amiruddin; Yusoff, Nur Izzi Md; Rahmat, Riza Atiq O K; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

2017-01-01

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.

An empirical review of antimalarial quality field surveys: the importance of characterising outcomes.

PubMed

Grech, James; Robertson, James; Thomas, Jackson; Cooper, Gabrielle; Naunton, Mark; Kelly, Tamsin

2018-01-05

For decades, thousands of people have been dying from malaria infections because of poor-quality medicines (PQMs). While numerous efforts have been initiated to reduce their presence, PQMs are still risking the lives of those seeking treatment. This review addresses the importance of characterising results of antimalarial medicine field surveys based upon the agreement of clearly defined definitions. Medicines found to be of poor quality can be falsified or counterfeit, substandard or degraded. The distinction between these categories is important as each category requires a different countermeasure. To observe the current trends in the reporting of field surveys, a systematic literature search of six academic databases resulted in the quantitative analysis of 61 full-text journal articles. Information including sample size, sampling method, geographical regions, analytical techniques, and characterisation conclusions was observed for each. The lack of an accepted uniform reporting system has resulted in varying, incomplete reports, which may not include important information that helps form effective countermeasures. The programmes influencing medicine quality such as prequalification, procurement services, awareness and education can be supported with the information derived from characterised results. The implementation of checklists such as the Medicine Quality Assessment Reporting Guidelines will further strengthen the battle against poor-quality antimalarials. Copyright © 2017 Elsevier B.V. All rights reserved.

Turbulence-assisted shear exfoliation of graphene using household detergent and a kitchen blender

NASA Astrophysics Data System (ADS)

Varrla, Eswaraiah; Paton, Keith R.; Backes, Claudia; Harvey, Andrew; Smith, Ronan J.; McCauley, Joe; Coleman, Jonathan N.

2014-09-01

To facilitate progression from the lab to commercial applications, it will be necessary to develop simple, scalable methods to produce high quality graphene. Here we demonstrate the production of large quantities of defect-free graphene using a kitchen blender and household detergent. We have characterised the scaling of both graphene concentration and production rate with the mixing parameters: mixing time, initial graphite concentration, rotor speed and liquid volume. We find the production rate to be invariant with mixing time and to increase strongly with mixing volume, results which are important for scale-up. Even in this simple system, concentrations of up to 1 mg ml-1 and graphene masses of >500 mg can be achieved after a few hours mixing. The maximum production rate was ~0.15 g h-1, much higher than for standard sonication-based exfoliation methods. We demonstrate that graphene production occurs because the mean turbulent shear rate in the blender exceeds the critical shear rate for exfoliation.To facilitate progression from the lab to commercial applications, it will be necessary to develop simple, scalable methods to produce high quality graphene. Here we demonstrate the production of large quantities of defect-free graphene using a kitchen blender and household detergent. We have characterised the scaling of both graphene concentration and production rate with the mixing parameters: mixing time, initial graphite concentration, rotor speed and liquid volume. We find the production rate to be invariant with mixing time and to increase strongly with mixing volume, results which are important for scale-up. Even in this simple system, concentrations of up to 1 mg ml-1 and graphene masses of >500 mg can be achieved after a few hours mixing. The maximum production rate was ~0.15 g h-1, much higher than for standard sonication-based exfoliation methods. We demonstrate that graphene production occurs because the mean turbulent shear rate in the blender exceeds the critical shear rate for exfoliation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03560g

[The interview as a research data collection method].

PubMed

Debout, Christophe

2016-04-01

The interview is a widely-used method for collecting research data, notably in qualitative and mixed protocols. However, it is an umbrella term which groups together numerous types of interviews adapted to the methodological diversity which characterises nursing science. Copyright © 2016. Published by Elsevier Masson SAS.

Auditory Processing Disorders: Acquisition and Treatment

ERIC Educational Resources Information Center

Moore, David R.

2007-01-01

Auditory processing disorder (APD) describes a mixed and poorly understood listening problem characterised by poor speech perception, especially in challenging environments. APD may include an inherited component, and this may be major, but studies reviewed here of children with long-term otitis media with effusion (OME) provide strong evidence…

Effect of ageing on the availability of heavy metals in soils amended with compost and biochar: evaluation of changes in soil and amendment properties.

PubMed

Venegas, A; Rigol, A; Vidal, M

2016-10-01

Remediation strategies using soil amendments should consider the time dependence of metal availability to identify amendments that can sustainably reduce available pollutant concentrations over time. Drying-wetting cycles were applied on amendments, soils and soil + amendment mixtures, to mimic ageing at field level and investigate its effect on extractable Cd, Cu, Ni, Pb and Zn concentrations from three contaminated soils. The amendments investigated were municipal waste organic compost and biochars. The amendments, soils and mixtures were characterised by their physicochemical properties at different ageing times. The amendments were also characterised in terms of sorption capacity for Cd and Cu. The sorption capacity and the physicochemical properties of the amendments remained constant over the period examined. When mixed with the soils, amendments, especially the compost, immediately reduced the extractable metals in the soils with low pH and acid neutralisation capacity, due to the increase in pH and buffering capacity of the mixtures. The amendments had a relatively minor impact on the metal availability concentrations for the soil with substantially high acid neutralisation capacity. The most important changes in extractable metal concentrations were observed at the beginning of the experiments, ageing having a minor effect on metal concentrations when compared with the initial effect of amendments.

Ultrasound Imaging Velocimetry: a review

NASA Astrophysics Data System (ADS)

Poelma, Christian

2017-01-01

Whole-field velocity measurement techniques based on ultrasound imaging (a.k.a. `ultrasound imaging velocimetry' or `echo-PIV') have received significant attention from the fluid mechanics community in the last decade, in particular because of their ability to obtain velocity fields in flows that elude characterisation by conventional optical methods. In this review, an overview is given of the history, typical components and challenges of these techniques. The basic principles of ultrasound image formation are summarised, as well as various techniques to estimate flow velocities; the emphasis is on correlation-based techniques. Examples are given for a wide range of applications, including in vivo cardiovascular flow measurements, the characterisation of sediment transport and the characterisation of complex non-Newtonian fluids. To conclude, future opportunities are identified. These encompass not just optimisation of the accuracy and dynamic range, but also extension to other application areas.

Environmental characterisation of coal mine waste rock in the field: an example from New Zealand

NASA Astrophysics Data System (ADS)

Hughes, J.; Craw, D.; Peake, B.; Lindsay, P.; Weber, P.

2007-08-01

Characterisation of mine waste rock with respect to acid generation potential is a necessary part of routine mine operations, so that environmentally benign waste rock stacks can be constructed for permanent storage. Standard static characterisation techniques, such as acid neutralisation capacity (ANC), maximum potential acidity, and associated acid-base accounting, require laboratory tests that can be difficult to obtain rapidly at remote mine sites. We show that a combination of paste pH and a simple portable carbonate dissolution test, both techniques that can be done in the field in a 15 min time-frame, is useful for distinguishing rocks that are potentially acid-forming from those that are acid-neutralising. Use of these techniques could allow characterisation of mine wastes at the metre scale during mine excavation operations. Our application of these techniques to pyrite-bearing (total S = 1-4 wt%) but variably calcareous coal mine overburden shows that there is a strong correlation between the portable carbonate dissolution technique and laboratory-determined ANC measurements (range of 0-10 wt% calcite equivalent). Paste pH measurements on the same rocks are bimodal, with high-sulphur, low-calcite rocks yielding pH near 3 after 10 min, whereas high-ANC rocks yield paste pH of 7-8. In our coal mine example, the field tests were most effective when used in conjunction with stratigraphy. However, the same field tests have potential for routine use in any mine in which distinction of acid-generating rocks from acid-neutralising rocks is required. Calibration of field-based acid-base accounting characteristics of the rocks with laboratory-based static and/or kinetic tests is still necessary.

Electrically induced microflows probed by fluorescence correlation spectroscopy.

PubMed

Ybert, C; Nadal, F; Salomé, R; Argoul, F; Bourdieu, L

2005-03-01

We report on the experimental characterisation of electrically induced flows at the micrometer scale through Fluorescence Correlation Spectroscopy (FCS) measurements. We stress the potential of FCS as a useful characterisation technique in microfluidics devices for transport properties cartography. The experimental results obtained in a model situation are in agreement with previous calculations (F. Nadal, F. Argoul, P. Kestener, B. Pouligny, C. Ybert, A. Ajdari, Eur. Phys. J. E 9, 387 (2002)) predicting the structure and electric-field dependency of the induced flow. Additionally, the present study evidences a complex behaviour of the probe nanobeads under electric field whose precise understanding might prove relevant for situations where nano-objects interact with an external electric field.

Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung.

PubMed

Tewes, Frederic; Ehrhardt, Carsten; Healy, Anne Marie

2014-01-01

Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)-in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8±0.3μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8kJ/m(3). However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2±2.0μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH4)2CO3 and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2±0.8μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8±0.7% to 19.5±3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci. Copyright © 2013 Elsevier B.V. All rights reserved.

A Quantitative, Non-Destructive Methodology for Habitat Characterisation and Benthic Monitoring at Offshore Renewable Energy Developments

PubMed Central

Sheehan, Emma V.; Stevens, Timothy F.; Attrill, Martin J.

2010-01-01

Following governments' policies to tackle global climate change, the development of offshore renewable energy sites is likely to increase substantially over coming years. All such developments interact with the seabed to some degree and so a key need exists for suitable methodology to monitor the impacts of large-scale Marine Renewable Energy Installations (MREIs). Many of these will be situated on mixed or rocky substrata, where conventional methods to characterise the habitat are unsuitable. Traditional destructive sampling is also inappropriate in conservation terms, particularly as safety zones around (MREIs) could function as Marine Protected Areas, with positive benefits for biodiversity. Here we describe a technique developed to effectively monitor the impact of MREIs and report the results of its field testing, enabling large areas to be surveyed accurately and cost-effectively. The methodology is based on a high-definition video camera, plus LED lights and laser scale markers, mounted on a “flying array” that maintains itself above the seabed grounded by a length of chain, thus causing minimal damage. Samples are taken by slow-speed tows of the gear behind a boat (200 m transects). The HD video and randomly selected frame grabs are analysed to quantify species distribution. The equipment was tested over two years in Lyme Bay, UK (25 m depth), then subsequently successfully deployed in demanding conditions at the deep (>50 m) high-energy Wave Hub site off Cornwall, UK, and a potential tidal stream energy site in Guernsey, Channel Islands (1.5 ms−1 current), the first time remote samples from such a habitat have been achieved. The next stage in the monitoring development process is described, involving the use of Remote Operated Vehicles to survey the seabed post-deployment of MREI devices. The complete methodology provides the first quantitative, relatively non-destructive method for monitoring mixed-substrate benthic communities beneath MPAs and MREIs pre- and post-device deployment. PMID:21206748

A quantitative, non-destructive methodology for habitat characterisation and benthic monitoring at offshore renewable energy developments.

PubMed

Sheehan, Emma V; Stevens, Timothy F; Attrill, Martin J

2010-12-29

Following governments' policies to tackle global climate change, the development of offshore renewable energy sites is likely to increase substantially over coming years. All such developments interact with the seabed to some degree and so a key need exists for suitable methodology to monitor the impacts of large-scale Marine Renewable Energy Installations (MREIs). Many of these will be situated on mixed or rocky substrata, where conventional methods to characterise the habitat are unsuitable. Traditional destructive sampling is also inappropriate in conservation terms, particularly as safety zones around (MREIs) could function as Marine Protected Areas, with positive benefits for biodiversity. Here we describe a technique developed to effectively monitor the impact of MREIs and report the results of its field testing, enabling large areas to be surveyed accurately and cost-effectively. The methodology is based on a high-definition video camera, plus LED lights and laser scale markers, mounted on a "flying array" that maintains itself above the seabed grounded by a length of chain, thus causing minimal damage. Samples are taken by slow-speed tows of the gear behind a boat (200 m transects). The HD video and randomly selected frame grabs are analysed to quantify species distribution. The equipment was tested over two years in Lyme Bay, UK (25 m depth), then subsequently successfully deployed in demanding conditions at the deep (>50 m) high-energy Wave Hub site off Cornwall, UK, and a potential tidal stream energy site in Guernsey, Channel Islands (1.5 ms⁻¹ current), the first time remote samples from such a habitat have been achieved. The next stage in the monitoring development process is described, involving the use of Remote Operated Vehicles to survey the seabed post-deployment of MREI devices. The complete methodology provides the first quantitative, relatively non-destructive method for monitoring mixed-substrate benthic communities beneath MPAs and MREIs pre- and post-device deployment.

Finding consistency between different views of the absorption enhancement of black carbon: An observationally constrained hybrid model to support a transition in optical properties with mass fraction

NASA Astrophysics Data System (ADS)

Coe, H.; Allan, J. D.; Whitehead, J.; Alfarra, M. R. R.; Villegas, E.; Kong, S.; Williams, P. I.; Ting, Y. C.; Haslett, S.; Taylor, J.; Morgan, W.; McFiggans, G.; Spracklen, D. V.; Reddington, C.

2015-12-01

The mixing state of black carbon is uncertain yet has a significant influence on the efficiency with which a particle absorbs light. In turn, this may make a significant contribution to the uncertainty in global model predictions of the black carbon radiative budget. Previous modelling studies that have represented this mixing state using a core-shell approach have shown that aged black carbon particles may be considerably enhanced compared to freshly emitted black carbon due to the addition of co-emitted, weakly absorbing species. However, recent field results have demonstrated that any enhancement of absorption is minor in the ambient atmosphere. Resolving these differences in absorption efficiency is important as they will have a major impact on the extent to which black carbon heats the atmospheric column. We have made morphology-independent measurements of refractory black carbon mass and associated weakly absorbing material in single particles from laboratory-generated diesel soot and black carbon particles in ambient air influenced by traffic and wood burning sources and related these to the optical properties of the particles. We compared our calculated optical properties with optical models that use varying mixing state assumptions and by characterising the behaviour in terms of the relative amounts of weakly absorbing material and black carbon in a particle we show a sharp transition in mixing occurs. We show that the majority of black carbon particles from traffic-dominated sources can be treated as externally mixed and show no absorption enhancement, whereas models assuming internal mixing tend to give the best estimate of the absorption enhancement of thickly coated black carbon particles from biofuel or biomass burning. This approach reconciles the differences in absorption enhancement previously observed and offers a systematic way of treating the differences in behaviour observed.

Newer approach of using alternatives to (Indium doped) metal electrodes, dyes and electrolytes in dye sensitized solar cell

NASA Astrophysics Data System (ADS)

Patni, Neha; Sharma, Pranjal; Pillai, Shibu G.

2018-04-01

This work demonstrates the PV study of dye sensitised solar cells by fabricating the (PV) cell using the ITO, FTO and AZO glass substrate. Dyes used for the fabrication were extracted from beetroot and spinach and a cocktail dye by mixing both of the dyes was also prepared. Similarly the three dufferent electrolytes used were iodide-triiodide couple, polyaniline and mixture of polyaniline and iodide couple. Mixed dye and mixed electrolyte has emerged as the highest efficient cell. The electrical characterisation shows that the highest power conversion efficiency of 1.86% was achieved by FTO substrate, followed by efficiency of 1.83% by AZO substrate and efficiency of 1.63% with ITO substrate using mixed dye and mixed electrolyte approach. This justifies that FTO and AZO shows better efficiency and hence proposed to be used as an alternative to indium free system.

Education and Education Research: Moribund Fields or Dynamic Interacting Systems?

ERIC Educational Resources Information Center

Reddy, C.

2011-01-01

The complex field of education is often depicted as a static field governed by technocratic approaches to activities that characterise the field. Education change is equally viewed in such limited and positivistic ways and linear means-end processes (Hoban 2002). In such orientations to the field, educational research therefore, is about finding…

Gamma-ray imaging system for real-time measurements in nuclear waste characterisation

NASA Astrophysics Data System (ADS)

Caballero, L.; Albiol Colomer, F.; Corbi Bellot, A.; Domingo-Pardo, C.; Leganés Nieto, J. L.; Agramunt Ros, J.; Contreras, P.; Monserrate, M.; Olleros Rodríguez, P.; Pérez Magán, D. L.

2018-03-01

A compact, portable and large field-of-view gamma camera that is able to identify, locate and quantify gamma-ray emitting radioisotopes in real-time has been developed. The device delivers spectroscopic and imaging capabilities that enable its use it in a variety of nuclear waste characterisation scenarios, such as radioactivity monitoring in nuclear power plants and more specifically for the decommissioning of nuclear facilities. The technical development of this apparatus and some examples of its application in field measurements are reported in this article. The performance of the presented gamma-camera is also benchmarked against other conventional techniques.

Influence of the physico-chemical properties of CeO 2-ZrO 2 mixed oxides on the catalytic oxidation of NO to NO 2

NASA Astrophysics Data System (ADS)

Atribak, Idriss; Guillén-Hurtado, Noelia; Bueno-López, Agustín; García-García, Avelina

2010-10-01

Commercial and home-made Ce-Zr catalysts prepared by co-precipitation were characterised by XRD, Raman spectroscopy, N 2 adsorption at -196 °C and XPS, and were tested for NO oxidation to NO 2. Among the different physico-chemical properties characterised, the surface composition seems to be the most relevant one in order to explain the NO oxidation capacity of these Ce-Zr catalysts. As a general trend, Ce-Zr catalysts with a cerium-rich surface, that is, high XPS-measured Ce/Zr atomic surface ratios, are more active than those with a Zr-enriched surface. The decrease in catalytic activity of the Ce-Zr mixed oxided upon calcinations at 800 °C with regard to 500 °C is mainly attributed to the decrease in Ce/Zr surface ratio, that is, to the surface segregation of Zr. The phase composition (cubic or t'' for Ce-rich compositions) seems not to be a direct effect on the catalytic activity for NO oxidation in the range of compositions tested. However, the formation of a proper solid solution prevents important surface segregation of Zr upon calcinations at high temperature. The effect of the BET surface area in the catalytic activity for NO oxidation of Ce-Zr mixed oxides is minor in comparison with the effect of the Ce/Zr surface ratio.

Developing a Characterisation of Citizenship Education: Issues Arising from Work Undertaken in a Higher Education Network

ERIC Educational Resources Information Center

Davies, Ian; Arthur, James; Harrison, Tom; Watson, Helen

2008-01-01

In order to understand better the way in which the emerging field of citizenship education is being characterised we reflect on work emerging from a higher education network (citizED) for citizenship education. Three of the four authors of this article are closely involved in that network. CitizED was established with funding from the Teacher…

Clinical challenges in the molecular characterization of circulating tumour cells in breast cancer.

PubMed

Lianidou, E S; Mavroudis, D; Georgoulias, V

2013-06-25

Blood testing for circulating tumour cells (CTC) has emerged as one of the hottest fields in cancer research. CTC detection and enumeration can serve as a 'liquid biopsy' and an early marker of response to systemic therapy, whereas their molecular characterisation has a strong potential to be translated to individualised targeted treatments and spare breast cancer (BC) patients unnecessary and ineffective therapies. Different analytical systems for CTC detection and isolation have been developed and new areas of research are directed towards developing novel assays for CTC molecular characterisation. Molecular characterisation of single CTC holds considerable promise for predictive biomarker assessment and to explore CTC heterogeneity. The application of extremely powerful next-generation sequencing technologies in the area of CTC molecular characterisation in combination with reliable single CTC isolation opens new frontiers for the management of patients in the near future. This review is mainly focused on the clinical potential of the molecular characterisation of CTC in BC.

Clinical challenges in the molecular characterization of circulating tumour cells in breast cancer

PubMed Central

Lianidou, E S; Mavroudis, D; Georgoulias, V

2013-01-01

Blood testing for circulating tumour cells (CTC) has emerged as one of the hottest fields in cancer research. CTC detection and enumeration can serve as a ‘liquid biopsy' and an early marker of response to systemic therapy, whereas their molecular characterisation has a strong potential to be translated to individualised targeted treatments and spare breast cancer (BC) patients unnecessary and ineffective therapies. Different analytical systems for CTC detection and isolation have been developed and new areas of research are directed towards developing novel assays for CTC molecular characterisation. Molecular characterisation of single CTC holds considerable promise for predictive biomarker assessment and to explore CTC heterogeneity. The application of extremely powerful next-generation sequencing technologies in the area of CTC molecular characterisation in combination with reliable single CTC isolation opens new frontiers for the management of patients in the near future. This review is mainly focused on the clinical potential of the molecular characterisation of CTC in BC. PMID:23756869

Characterisation of InlA truncation in Listeria monocytogenes isolates from farm animals and human cases in the province of Quebec

PubMed Central

Fravalo, Philippe; Cherifi, Tamazight; Neira Feliciano, Kersti Dina; Letellier, Ann; Fairbrother, Julie-Hélène; Bekal, Sadjia

2017-01-01

The introduction of Listeria monocytogenes into the food production chain is a concern, with numerous grouped cases of listeriosis associated with milk-derived or pork-derived products have been documented. Management of this zoonotic pathogen considers all strains as an equal risk. Recently, a new perspective for characterisation of strain virulence was introduced with the discovery of the unaltered sequence of InlA as a determinant of strain virulence; this has also been reported as an infrequent finding among so-called environmental strains, that is, strains isolated from food or from surfaces in food industries. The aim of this study was to differentiate L monocytogenes strains isolated from animal cases versus those from human cases and to differentiate clinical strains from environmental ones using a Caenorhabditis elegans virulence testing model. In Quebec in 2013/2014, the surveillance of L monocytogenes clinical isolates registered a total of 20 strains of animal origin and 16 pulsed-field gel electrophoresis types isolated from human cases. The mixed PCR multiplex agglutination protocol used for geno-serotyping clearly discriminated genogroup IVB strains from bovine and human origins. The presence of a premature stop codon single nucleotide polymorphism in the inlA gene sequence in clinical strains and the identical behaviour of particular strains in the C elegans model are discussed in this paper from the perspective of industrial management of L monocytogenes risk. PMID:28761668

Characteristics of tyre dust in polluted air: Studies by single particle mass spectrometry (ATOFMS)

NASA Astrophysics Data System (ADS)

Dall'Osto, Manuel; Beddows, David C. S.; Gietl, Johanna K.; Olatunbosun, Oluremi A.; Yang, Xiaoguang; Harrison, Roy M.

2014-09-01

There is a paucity of quantitative knowledge on the contributions of non-exhaust (abrasion and re-suspension) sources to traffic emissions. Abrasive emissions can be broadly categorised as tyre wear, brake wear and road dust/road surface wear. Current research often considers road dust and tyre dust as externally mixed particles, the former mainly composed of mineral matter and the latter solely composed of mainly organic matter and some trace elements. The aim of this work was to characterise tyre wear from both laboratory and field studies by using Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS). Real-time single particle chemical composition was obtained from a set of rubber tyres rotating on a metal surface. Bimodal particle number size distributions peaking at 35 nm and 85 nm were obtained from SMPS/APS measurements over the range 6-20,000 nm. ATOFMS mass spectra of tyre wear in the particle size range 200-3000 nm diameter show peaks due to exo-sulphur compounds, nitrate, Zn and ions of high molecular weight (m/z > 100) attributed to organic polymers. Two large ATOFMS datasets collected from a number of outdoor studies were examined. The former was constituted of 48 road dust samples collected on the roads of London. The latter consisted of ATOFMS ambient air field studies from Europe, overall composed of more than 2,000,000 single particle mass spectra. The majority (95%) of tyre wear particles present in the road dust samples and atmospheric samples are internally mixed with metals (Li, Na, Ca, Fe, Ti), as well as phosphate. It is concluded that the interaction of tyres with the road surface creates particles internally mixed from two sources: tyre rubber and road surface materials. Measurements of the tyre rubber component alone may underestimate the contribution of tyre wear to concentrations of airborne particulate matter. The results presented are especially relevant for urban aerosol source apportionment and PM2.5 exposure assessment.

Sheet metals characterization using the virtual fields method

NASA Astrophysics Data System (ADS)

Marek, Aleksander; Davis, Frances M.; Pierron, Fabrice

2018-05-01

In this work, a characterisation method involving a deep-notched specimen subjected to a tensile loading is introduced. This specimen leads to heterogeneous states of stress and strain, the latter being measured using a stereo DIC system (MatchID). This heterogeneity enables the identification of multiple material parameters in a single test. In order to identify material parameters from the DIC data, an inverse method called the Virtual Fields Method is employed. The method combined with recently developed sensitivity-based virtual fields allows to optimally locate areas in the test where information about each material parameter is encoded, improving accuracy of the identification over the traditional user-defined virtual fields. It is shown that a single test performed at 45° to the rolling direction is sufficient to obtain all anisotropic plastic parameters, thus reducing experimental effort involved in characterisation. The paper presents the methodology and some numerical validation.

Detection and characterisation of anthropogenic pieces by magnetic method

NASA Astrophysics Data System (ADS)

Nodot, Emilie; Munschy, Marc; Benevent, Pierre

2013-04-01

Human activities have let many anthropogenic objects buried under our feet. Some of these like explosive devices left after the World Wars turn out to be a threat to safety or environment. Others must be perfectly localised in case of construction work, for example gas pipe. Geophysics and more specifically magnetic cartography (many of these items are magnetic) can obviously help to locate them. We already use this method on daily basis to detect UXO (unexploded ordnance) but less than 10% of the unearthed objects are actually bombs or shells. Detection and mostly characterisation methods must be improved in order to reduce this proportion. On the field there are a few things we can do to increase data qualities. Characterisation may be improved by multiple scale prospections. We search a large area with our usual and rather fast method then we achieve high definition cartographies of small interesting areas (upon the object to characterise). In the case of measurements in an urban environment for example, data are distorted. The traffic (train, tramway, cars…) produces temporal variations of the magnetic field. This effect can be lessened, sometimes even removed by the use of a fixed scalar magnetic sensor. Data treatment is another key as regards the characterisation. Tools such as analytic signal or derivative are frequently used at the first degree. We will see that in a synthetic case the second and third degree bring even more information. A new issue appeared recently about pipes. Can we localise very precisely (less than 10 cm uncertainty) a gas pipe? Horizontally we can but due to our inversion method we still have troubles with the depth accuracy. Our final concern is about the amplitude of some anomalies. Potential methods equations are based on the fact that the anomaly norm must be minor to magnetic field norm. Sometimes this is not the case but vector magnetometry is a lead to solve this problem.

Using a Laboratory Simulator in the Teaching and Study of Chemical Processes in Estuarine Systems

ERIC Educational Resources Information Center

Garcia-Luque, E.; Ortega, T.; Forja, J. M.; Gomez-Parra, A.

2004-01-01

The teaching of Chemical Oceanography in the Faculty of Marine and Environmental Sciences of the University of Cadiz (Spain) has been improved since 1994 by the employment of a device for the laboratory simulation of estuarine mixing processes and the characterisation of the chemical behaviour of many substances that pass through an estuary. The…

The Changing Face of the Australian Teaching Profession: New Generations and New Ways of Working and Learning

ERIC Educational Resources Information Center

Mayer, Diane

2006-01-01

Today's workforce is characterised by an increasing mix of people with varying career aspirations, work motivators and job satisfiers. This paper discusses the intergenerational nature of today's workforce, which is currently dominated by the age groups commonly referred to as Baby Boomers and Generation X. The Baby Boomers defined and redefined…

The Opportunities to Build on Existing Expertise in Writing Classrooms: A Study of Writing Lessons in New Zealand Primary Schools

ERIC Educational Resources Information Center

Jesson, Rebecca N.; Cockle, Victoria

2016-01-01

The present study investigated 15 Year 4-6 classrooms in two multicultural schools in New Zealand to understand what opportunities students had to draw on their diverse experiences of texts. A mixed-methods approach was taken, including classroom observations and student interviews. Results suggested that lessons were characterised by a consistent…

Current Application of Capillary Electrophoresis in Nanomaterial Characterisation and Its Potential to Characterise the Protein and Small Molecule Corona

PubMed Central

Guggenheim, Emily J.; Briffa, Sophie M.; Thorn, James A.; Lynch, Iseult; Valsami-Jones, Eugenia

2018-01-01

Due to the increasing use and production of nanomaterials (NMs), the ability to characterise their physical/chemical properties quickly and reliably has never been so important. Proper characterisation allows a thorough understanding of the material and its stability, and is critical to establishing dose-response curves to ascertain risks to human and environmental health. Traditionally, methods such as Transmission Electron Microscopy (TEM), Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) have been favoured for size characterisation, due to their wide-availability and well-established protocols. Capillary Electrophoresis (CE) offers a faster and more cost-effective solution for complex dispersions including polydisperse or non-spherical NMs. CE has been used to rapidly separate NMs of varying sizes, shapes, surface modifications and compositions. This review will discuss the literature surrounding the CE separation techniques, detection and NM characteristics used for the analysis of a wide range of NMs. The potential of combining CE with mass spectrometry (CE-MS) will also be explored to further expand the characterisation of NMs, including the layer of biomolecules adsorbed to the surface of NMs in biological or environmental compartments, termed the acquired biomolecule corona. CE offers the opportunity to uncover new/poorly characterised low abundance and polar protein classes due to the high ionisation efficiency of CE-MS. Furthermore, the possibility of using CE-MS to characterise the poorly researched small molecule interactions within the NM corona is discussed. PMID:29439415

Demographic response to rural restructuring and counterurbanisation in South Australia, 1981-1991.

PubMed

Smailes, P J

1996-09-01

"Using South Australia as a case study, this paper seeks to trace and demonstrate two processes (counterurbanisation and rural restructuring) whose effects overlap to differentiate and characterise the population geography of...two zones, separated by a transition along the outer fringe of Adelaide's urban field.... In the demographic core zone [rural restructuring] has been partly offset by continued counterurbanisation, resulting in demographic mixing and rural dilution. The 1981-91 population growth in rural communities is shown to be more a function of population density at the outset of the period than of initial population size. Demographic growth...is shown to conform to a simple unidimensional scale, allowing the production of a clear, easily interpretable typology of rural demographic change with few non-conforming statistical areas. At a local level within individual rural communities, demographic decline is shown to be accompanied by increased concentration of the population into small towns, while demographic growth is associated with deconcentration." excerpt

Inflation with a massive vector field nonminimally coupled to gravity

NASA Astrophysics Data System (ADS)

Páramos, J.

2018-01-01

The possibility that inflation is driven by a massive vector field with SO(3) global symmetry nonminimally coupled to gravity is presented. Through an appropriate Ansatz for the vector field, the behaviour of the equations of motion is studied through the ensuing dynamical system, focusing on the characterisation of the ensuing fixed points.

Characterisation and materials flow management for waste electrical and electronic equipment plastics from German dismantling centres.

PubMed

Arends, Dagmar; Schlummer, Martin; Mäurer, Andreas; Markowski, Jens; Wagenknecht, Udo

2015-09-01

Waste electrical and electronic equipment is a complex waste stream and treatment options that work for one waste category or product may not be appropriate for others. A comprehensive case study has been performed for plastic-rich fractions that are treated in German dismantling centres. Plastics from TVs, monitors and printers and small household appliances have been characterised extensively. Based on the characterisation results, state-of-the-art treatment technologies have been combined to design an optimised recycling and upgrade process for each input fraction. High-impact polystyrene from TV casings that complies with the European directive on the restriction of hazardous substances (RoHS) was produced by applying continuous density separation with yields of about 60%. Valuable acrylonitrile butadiene styrene/polycarbonate can be extracted from monitor and printer casings by near-infrared-based sorting. Polyolefins and/or a halogen-free fraction of mixed styrenics can be sorted out by density separation from monitors and printers and small household appliances. Emerging separation technologies are discussed to improve recycling results. © The Author(s) 2015.

Mixing characterisation of full-scale membrane bioreactors: CFD modelling with experimental validation.

PubMed

Brannock, M; Wang, Y; Leslie, G

2010-05-01

Membrane Bioreactors (MBRs) have been successfully used in aerobic biological wastewater treatment to solve the perennial problem of effective solids-liquid separation. The optimisation of MBRs requires knowledge of the membrane fouling, biokinetics and mixing. However, research has mainly concentrated on the fouling and biokinetics (Ng and Kim, 2007). Current methods of design for a desired flow regime within MBRs are largely based on assumptions (e.g. complete mixing of tanks) and empirical techniques (e.g. specific mixing energy). However, it is difficult to predict how sludge rheology and vessel design in full-scale installations affects hydrodynamics, hence overall performance. Computational Fluid Dynamics (CFD) provides a method for prediction of how vessel features and mixing energy usage affect the hydrodynamics. In this study, a CFD model was developed which accounts for aeration, sludge rheology and geometry (i.e. bioreactor and membrane module). This MBR CFD model was then applied to two full-scale MBRs and was successfully validated against experimental results. The effect of sludge settling and rheology was found to have a minimal impact on the bulk mixing (i.e. the residence time distribution).

Understanding the value of mixed methods research: the Children’s Safety Initiative-Emergency Medical Services

PubMed Central

Hansen, Matthew; O’Brien, Kerth; Meckler, Garth; Chang, Anna Marie; Guise, Jeanne-Marie

2016-01-01

Mixed methods research has significant potential to broaden the scope of emergency care and specifically emergency medical services investigation. Mixed methods studies involve the coordinated use of qualitative and quantitative research approaches to gain a fuller understanding of practice. By combining what is learnt from multiple methods, these approaches can help to characterise complex healthcare systems, identify the mechanisms of complex problems such as medical errors and understand aspects of human interaction such as communication, behaviour and team performance. Mixed methods approaches may be particularly useful for out-of-hospital care researchers because care is provided in complex systems where equipment, interpersonal interactions, societal norms, environment and other factors influence patient outcomes. The overall objectives of this paper are to (1) introduce the fundamental concepts and approaches of mixed methods research and (2) describe the interrelation and complementary features of the quantitative and qualitative components of mixed methods studies using specific examples from the Children’s Safety Initiative-Emergency Medical Services (CSI-EMS), a large National Institutes of Health-funded research project conducted in the USA. PMID:26949970

Attribution and Characterisation of Sclerophyll Forested Landscapes Over Large Areas

NASA Astrophysics Data System (ADS)

Jones, Simon; Soto-Berelov, Mariela; Suarez, Lola; Wilkes, Phil; Woodgate, Will; Haywood, Andrew

2016-06-01

This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI), bole density, canopy height), which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest). High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning) and researchers (RMIT, CRC for Spatial Information and CSIRO) conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet) scanners. Results are presented of: 1) inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2) canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3) time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS) with new aspirational targets of 5%). In this research we conducted a total of 67 ground-based method-to-method pairwise comparisons across 11 plots in five sites, incorporating the previously mentioned LAI methods. Out of the 67 comparisons, 29 had an RMSE ≥ 0.5 LAIe. This has important implications for the validation of remotely sensed products since ground based techniques themselves exhibit LAI variations greater than internationally recommended guidelines for satellite product accuracies. 2. Two methods of canopy height derivation are proposed and tested over a large area (4 Million Ha). 99th percentile maximum height achieved a RMSE of 6.6%, whilst 95th percentile dominant height a RMSE = 10.3%. Vertical canopy complexity (i.e. the number of forest layers of strata) was calculated as the local maxima of vegetation density within the LiDAR canopy profile and determined using a cubic spline smoothing of Pgap. This was then validated against in-situ and LiDAR observations of canopy strata with an RMSE 0.39 canopy layers. 3. Preliminary results are presented of landcover characterisation using LandTrendr analysis of Landsat LEDAPS data. kNN is then used to link these features to a dense network of 800 field plots sites.

Functional Testing and Characterisation of ISFETs on Wafer Level by Means of a Micro-droplet Cell#

PubMed Central

Poghossian, Arshak; Schumacher, Kerstin; Kloock, Joachim P.; Rosenkranz, Christian; Schultze, Joachim W.; Müller-Veggian, Mattea; Schöning, Michael J.

2006-01-01

A wafer-level functionality testing and characterisation system for ISFETs (ion-sensitive field-effect transistor) is realised by means of integration of a specifically designed capillary electrochemical micro-droplet cell into a commercial wafer prober-station. The developed system allows the identification and selection of “good” ISFETs at the earliest stage and to avoid expensive bonding, encapsulation and packaging processes for non-functioning ISFETs and thus, to decrease costs, which are wasted for bad dies. The developed system is also feasible for wafer-level characterisation of ISFETs in terms of sensitivity, hysteresis and response time. Additionally, the system might be also utilised for wafer-level testing of further electrochemical sensors.

Exact ground-state correlation functions of an atomic-molecular Bose–Einstein condensate model

NASA Astrophysics Data System (ADS)

Links, Jon; Shen, Yibing

2018-05-01

We study the ground-state properties of an atomic-molecular Bose–Einstein condensate model through an exact Bethe Ansatz solution. For a certain range of parameter choices, we prove that the ground-state Bethe roots lie on the positive real-axis. We then use a continuum limit approach to obtain a singular integral equation characterising the distribution of these Bethe roots. Solving this equation leads to an analytic expression for the ground-state energy. The form of the expression is consistent with the existence of a line of quantum phase transitions, which has been identified in earlier studies. This line demarcates a molecular phase from a mixed phase. Certain correlation functions, which characterise these phases, are then obtained through the Hellmann–Feynman theorem.

Pacific deep circulation and ventilation controlled by tidal mixing away from the sea bottom.

PubMed

Oka, Akira; Niwa, Yoshihiro

2013-01-01

Vertical mixing in the ocean is a key driver of the global ocean thermohaline circulation, one of the most important factors controlling past and future climate change. Prior observational and theoretical studies have focused on intense tidal mixing near the sea bottom (near-field mixing). However, ocean general circulation models that employ a parameterization of near-field mixing significantly underestimate the strength of the Pacific thermohaline circulation. Here we demonstrate that tidally induced mixing away from the sea bottom (far-field mixing) is essential in controlling the Pacific thermohaline circulation. Via the addition of far-field mixing to a widely used tidal parameterization, we successfully simulate the Pacific thermohaline circulation. We also propose that far-field mixing is indispensable for explaining the presence of the world ocean's oldest water in the eastern North Pacific Ocean. Our findings suggest that far-field mixing controls ventilation of the deep Pacific Ocean, a process important for ocean carbon and biogeochemical cycles.

The determination of the botanical origin in honeys with over-represented pollen: combination of melissopalynological, sensory and physicochemical analysis.

PubMed

Rodopoulou, Maria-Anna; Tananaki, Chrysoula; Dimou, Maria; Liolios, Vasilios; Kanelis, Dimitrios; Goras, Georgios; Thrasyvoulou, Andreas

2018-05-01

Pollen analysis of honey is the basic method for the determination of its botanical origin. However, the presence of over-represented pollen in honeys may lead the analysis to false results. This can be more severe if this pollen is present in unifloral under-represented honeys of commercial importance (e.g. thyme honey). In the present study, we investigated the abundance of over-represented pollen grains on several quality characteristics in honey samples. In particular, we mixed honeys characterised as over-represented, specifically chestnut and eucalyptus, with thyme honeys in different analogies, and we also analysed the melissopalynological, organoleptic, physicochemical (water content, electrical conductivity, colour) and volatile characteristics of the blends. The most sensitive parameters were the microscopic characteristics, followed by the organoleptic ones. Blends of thyme honey with an originally low percentage of thyme pollen were the most influenced and could not be characterised as unifloral regarding their melissopalynological characteristics, even when they were mixed with small quantities of honeys with over-represented pollen (i.e. 5%). The present study confirms that, in the case of presence of over-represented pollen in honeys, pollen analysis alone cannot give trustworthy results for the determination of the botanical origin, even though their exclusion during pollen analysis, when they are present in percentages of up to 30%, could provide more accurate results. Consequently, pollen analysis should also be combined with the other analyses, especially in honeys with under-represented and over-represented pollens, to give safer results for the botanical characterisation of honeys. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Structural control on geothermal circulation in the Cerro Tuzgle-Tocomar geothermal volcanic area (Puna plateau, Argentina)

NASA Astrophysics Data System (ADS)

Giordano, Guido; Pinton, Annamaria; Cianfarra, Paola; Baez, Walter; Chiodi, Agostina; Viramonte, José; Norini, Gianluca; Groppelli, Gianluca

2013-01-01

The reconstruction of the stratigraphical-structural framework and the hydrogeology of geothermal areas is fundamental for understanding the relationships between cap rocks, reservoir and circulation of geothermal fluids and for planning the exploitation of the field. The Cerro Tuzgle-Tocomar geothermal volcanic area (Puna plateau, Central Andes, NW Argentina) has a high geothermal potential. It is crossed by the active NW-SE trans-Andean tectonic lineament known as the Calama-Olacapato-Toro (COT) fault system, which favours a high secondary permeability testified by the presence of numerous springs. This study presents new stratigraphic and hydrogeological data on the geothermal field, together with the analysis from remote sensed image analysis of morphostructural evidences associated with the structural framework and active tectonics. Our data suggest that the main geothermal reservoir is located within or below the Pre-Palaeozoic-Ordovician basement units, characterised by unevenly distributed secondary permeability. The reservoir is recharged by infiltration in the ridges above 4500 m a.s.l., where basement rocks are in outcrop. Below 4500 m a.s.l., the reservoir is covered by the low permeable Miocene-Quaternary units that allow a poor circulation of shallow groundwater. Geothermal fluids upwell in areas with more intense fracturing, especially where main regional structures, particularly NW-SE COT-parallel lineaments, intersect with secondary structures, such as at the Tocomar field. Away from the main tectonic features, such as at the Cerro Tuzgle field, the less developed network of faults and fractures allows only a moderate upwelling of geothermal fluids and a mixing between hot and shallow cold waters. The integration of field-based and remote-sensing analyses at the Cerro Tuzgle-Tocomar area proved to be effective in approaching the prospection of remote geothermal fields, and in defining the conceptual model for geothermal circulation.

Characterising Passive Dosemeters for Dosimetry of Biological Experiments in Space (dobies)

NASA Astrophysics Data System (ADS)

Vanhavere, Filip; Spurny, Frantisek; Yukihara, Eduardo; Genicot, Jean-Louis

Introduction: The DOBIES (Dosimetry of biological experi-ments in space) project focusses on the use of a stan-dard dosimetric method (as a combination of differ-ent passive techniques) to measure accurately the absorbed doses and equivalent doses in biological samples. Dose measurements on biological samples are of high interest in the fields of radiobiology and exobiology. Radiation doses absorbed by biological samples must be quantified to be able to determine the relationship between observed biological effects and the radiation dose. The radiation field in space is very complex, con-sisting of protons, neutrons, electrons and high-energy heavy charged particles. It is not straightfor-ward to measure doses in this radiation field, cer-tainly not with only small and light passive doseme-ters. The properties of the passive detectors must be tested in radiation fields that are representative of the space radiation. We will report on the characterisation of different type of passive detectors at high energy fields. The results from such characterisation measurements will be applied to recent exposures of detectors on the International Space Station. Material and methods: Following passive detectors are used: • thermoluminescent detectors (TLD) • optically stimulated luminescence detectors (OSLD) • track etch detectors (TED) The different groups have participated in the past to the ICCHIBAN series of irradiations. Here protons and other particles of high energy were used to de-termine the LET-dependency of the passive detec-tors. The last few months, new irradiations have been done at the iThemba labs (100-200 MeV protons), Dubna (145 MeV protons) and the JRC-IRMM (quasi mono energetic neutrons up to 19 MeV). All these detectors were also exposed to a simulated space radiation field at CERN (CERF-field). Discussion: The interpretation of the TLD and OSLD results is done using the measured LET spectrum (TED) and the LET-dependency curves of ths TLD and OSLDs. These LET- dependency curves are determined based on the different irradiations listed above. We will report on the results of the different detectors in these fields. Further information on the LET of the space irradia-tion can be deduced from the ratio of the different peaks of the TLDs after glow curve deconvolution, and from the shape of the decay curve of the OSLDs. The results in the CERF field can on the other hand directly being used as a calibration for space radia-tion fields. Conclusion: Combining different passive detectors will lead to improved information on the radiation field, and thus to a better estimation of the absorbed dose to the bio-logical samples. We use the characterisations on high energy accelerators to improve the estimation of some recent space doses.

Classification of instability modes in a model of aluminium reduction cells with a uniform magnetic field

NASA Astrophysics Data System (ADS)

Molokov, Sergei; El, Gennady; Lukyanov, Alexander

2011-10-01

A unified view on the interfacial instability in a model of aluminium reduction cells in the presence of a uniform, vertical, background magnetic field is presented. The classification of instability modes is based on the asymptotic theory for high values of parameter β, which characterises the ratio of the Lorentz force based on the disturbance current, and gravity. It is shown that the spectrum of the travelling waves consists of two parts independent of the horizontal cross-section of the cell: highly unstable wall modes and stable or weakly unstable centre, or Sele's modes. The wall modes with the disturbance of the interface being localised at the sidewalls of the cell dominate the dynamics of instability. Sele's modes are characterised by a distributed disturbance over the whole horizontal extent of the cell. As β increases these modes are stabilized by the field.

Strong Magnetic Field Characterisation

DTIC Science & Technology

2012-04-01

an advertised surface field of approximately 0.5 T were used to supply the static magnetic field source. The disc magnet had a diameter of 50 mm and... colour bar indicates the magnetic field strength set to an arbitrary 0.25 T. The white area has a field >0.25 T. The size of the arrow is proportional...9 shows the magnetic field strength along a slice in the XZ plane. The colours represent the total UNCLASSIFIED 10 UNCLASSIFIED DSTO-TR-2699

Groundwater circulation and geochemistry of a karstified bank marginal fracture system, South Andros Island, Bahamas

NASA Astrophysics Data System (ADS)

Whitaker, Fiona F.; Smart, Peter L.

1997-10-01

On the east coast of South Andros Island, Bahamas, a major bank-marginal fracture system characterised by vertically extensive cavern systems (blue holes) is developed sub-parallel to the steep-sided deep-water re-entrant of the Tongue of the Ocean. In addition to providing a discharge route for meteoric, mixed and geochemically evolved saline groundwaters, a strong local circulation occurs along the fracture system. This generates enhanced vertical mixing within voids of the fracture system, evidenced by the increasing mixing zone thickness, and the thinning and increasing salinity of brackish lens waters from north to south along the fracture system. Furthermore, tidally driven pumping of groundwaters occurs between the fracture and adjacent carbonate aquifer affecting a zone up to 200 m either side of the fracture. The resultant mixing of groundwaters of contrasting salinity and PCO 2 within and along the fracture system and with the surrounding aquifer waters, together with bacterial oxidation of organic matter, generates significant potential for locally enhanced diagenesis. Undersaturation with respect to calcite within the fresh (or brackish)-salt water mixing zone is observed in the fracture system and predicted in the adjacent aquifer, while mixing between the brackish fracture lens and surrounding high PCO 2 fresh waters causes dissolution of aragonite but not calcite. The latter gives rise to considerable secondary porosity development, because active tidal pumping ensures continued renewal of dissolutional potential. This is evidenced by calcium and strontium enrichment in the brackish lens which indicates porosity generation by aragonite dissolution at a maximum rate of 0.35% ka -1, up to twice the average estimated for the fresh water lens. In contrast saline groundwaters are depleted in calcium relative to open ocean waters suggesting the formation of calcite cements. The development of a major laterally continuous cavernous fracture zone along the margin of the carbonate platform permits enhanced groundwater flow and mixing which may result in generation of a diagenetic `halo' at a scale larger than that generally recognised around syn-sedimentary fractures in fossil carbonates. This may be characterised by increased secondary porosity where a relative fall in sea-level results in exposure and formation of a meteoric groundwater system, or cementation by `marine' calcite both below this meteoric system, and where the bank surface is flooded by seawater.

Mixing Phenomena in a Bottom Blown Copper Smelter: A Water Model Study

NASA Astrophysics Data System (ADS)

Shui, Lang; Cui, Zhixiang; Ma, Xiaodong; Akbar Rhamdhani, M.; Nguyen, Anh; Zhao, Baojun

2015-03-01

The first commercial bottom blown oxygen copper smelting furnace has been installed and operated at Dongying Fangyuan Nonferrous Metals since 2008. Significant advantages have been demonstrated in this technology mainly due to its bottom blown oxygen-enriched gas. In this study, a scaled-down 1:12 model was set up to simulate the flow behavior for understanding the mixing phenomena in the furnace. A single lance was used in the present study for gas blowing to establish a reliable research technique and quantitative characterisation of the mixing behavior. Operating parameters such as horizontal distance from the blowing lance, detector depth, bath height, and gas flow rate were adjusted to investigate the mixing time under different conditions. It was found that when the horizontal distance between the lance and detector is within an effective stirring range, the mixing time decreases slightly with increasing the horizontal distance. Outside this range, the mixing time was found to increase with increasing the horizontal distance and it is more significant on the surface. The mixing time always decreases with increasing gas flow rate and bath height. An empirical relationship of mixing time as functions of gas flow rate and bath height has been established first time for the horizontal bottom blowing furnace.

Delta 37Cl and Characterisation of Petroleum-gas Reservoirs

NASA Astrophysics Data System (ADS)

Woulé Ebongué, V.; Jendrzejewski, N.; Walgenwitz, F.; Pineau, F.; Javoy, M.

2003-04-01

The geochemical characterisation of formation waters from oil/gas fields is used to detect fluid-flow barriers in reservoirs and to reconstruct the system dynamic. During the progression of the reservoir filling, the aquifer waters are pushed by hydrocarbons toward the reservoir bottom and their compositions evolve due to several parameters such as water-rock interactions, mixing with oil-associated waters, physical processes etc. The chemical and isotopic evolution of these waters is recorded in irreducible waters that have been progressively "fossilised" in the oil/gas column. Residual salts precipitated from these waters were recovered. Chloride being the most important dissolved anion in these waters and not involved in diagenetic reactions, its investigation should give insights into the different transport or mixing processes taking place in the sedimentary basin and point out to the formation waters origins. The first aim of our study was to test the Cl-RSA technique (Chlorine Residual Salts Analysis) based on the well-established Sr-RSA technique. The main studied area is a turbiditic sandstone reservoir located in the Lower Congo basin in Angola. Present-day aquifer waters, irreducible waters from sandstone and shale layers as well as drilling mud and salt dome samples were analysed. Formation waters (aquifer and irreducible trapped in shale) show an overall increase of chlorinity with depth. Their δ37Cl values range from -1.11 ppm to +2.30 ppm ± 0.05 ppm/ SMOC. Most Cl-RSA data as well as the δ37Cl obtained on a set of water samples (from different aquifers in the same area) are lower than -0.13 ppm with lower δ37Cl values at shallower depths. In a δ37Cl versus chlorinity diagram, they are distributed along a large range of chlorinity: 21 to 139 g/l, in two distinct groups. (1) Irreducible waters from one of the wells display a positive correlation between chlorinity and the δ37Cl values. (2) In contrary, the majority of δ37Cl measured on aquifers and on residual salts from a second well are anti-correlated with chlorinity. The preliminary determinations of δ37Cl values of sandstone irreducible waters seem to match the values obtained on irreducible waters trapped in the shale porosity. δ37Cl values and chlorinities are used to identify the contributions of physico-chemical processes such as ion filtration, diffusion or mixing. The chronology of the events and their relative importance are discussed.

Mixed acinar-neuroendocrine-ductal carcinoma of the pancreas: a tale of three lineages.

PubMed

Anderson, Mark J; Kwong, Christina A; Atieh, Mohammed; Pappas, Sam G

2016-06-02

Most pancreatic cancers arise from a single cell type, although mixed pancreatic carcinomas represent a rare exception. The rarity of these aggressive malignancies and the limitations of fine-needle aspiration (FNA) pose significant barriers to diagnosis and appropriate management. We report a case of a 54-year-old man presenting with abdominal pain, jaundice and a hypodense lesion within the uncinate process on CT. FNA suggested poorly differentiated adenocarcinoma, which was subsequently resected via pancreaticoduodenectomy. Pathological analysis yielded diagnosis of invasive mixed acinar-neuroendocrine-ductal pancreatic carcinoma. Given the rare and deadly nature of these tumours, clinicians must be aware of their pathophysiology and do practice with a high degree of clinical suspicion, when appropriate. Surgical resection and thorough pathological analysis with immunohistochemical staining and electron microscopy remain the standards of care for mixed pancreatic tumours without gross evidence of metastasis. Diligent characterisation of the presentation and histological findings associated with these neoplasms should continue in order to promote optimal diagnostic and therapeutic strategies. 2016 BMJ Publishing Group Ltd.

Characterisation and evaluation of antiviral recombinant peptides based on the heptad repeat regions of NDV and IBV fusion glycoproteins

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

Wang Xiaojia, E-mail: wangxj@cau.edu.cn; Li Chuangen; Chi Xiaojing

Mixed virus infections can cause livestock losses that are more devastating than those caused by single virus infections. Newcastle disease virus (NDV) and infectious bronchitis virus (IBV), serious threats to the poultry industry, can give rise to complex mixed infections that hinder diagnosis and prevention. In this study, we show that newly designed peptides, which are based on the heptad repeat (HR) region of the fusion glycoproteins from NDV and IBV, have more potent antiviral activity than the mother HR peptides. Plaque formation and chicken embryo infectivity assays confirmed these results. The novel peptides completely inhibited single virus infections andmore » mixed infections caused by NDV and IBV. Furthermore, we assessed cell toxicity and possible targets for the peptides, thereby strengthening the notion that HR2 is an attractive site for therapeutic intervention. These results suggest the possibility of designing a relatively broad-spectrum class of antiviral peptides that can reduce the effects of mixed-infections.« less

A fluidic device for the controlled formation and real-time monitoring of soft membranes self-assembled at liquid interfaces.

PubMed

Mendoza-Meinhardt, Arturo; Botto, Lorenzo; Mata, Alvaro

2018-02-13

Membrane materials formed at the interface between two liquids have found applications in a large variety of technologies, from sensors to drug-delivery and catalysis. However, studying the formation of these membranes in real-time presents considerable challenges, owing to the difficulty of prescribing the location and instant of formation of the membrane, the difficulty of observing time-dependent membrane shape and thickness, and the poor reproducibility of results obtained using conventional mixing procedures. Here we report a fluidic device that facilitates characterisation of the time-dependent thickness, morphology and mass transport properties of materials self-assembled at fluid-fluid interfaces. In the proposed device the membrane forms from the controlled coalescence of two liquid menisci in a linear open channel. The linear geometry and controlled mixing of the solutions facilitate real-time visualisation, manipulation and improve reproducibility. Because of its small dimensions, the device can be used in conjunction with standard microscopy methods and reduces the required volumes of potentially expensive reagents. As an example application to tissue engineering, we use the device to characterise interfacial membranes formed by supra-molecular self-assembly of peptide-amphiphiles with either an elastin-like-protein or hyaluronic acid. The device can be adapted to study self-assembling membranes for applications that extend beyond bioengineering.

Use of a mixing model to investigate groundwater-surface water mixing and nitrogen biogeochemistry in the bed of a groundwater-fed river

NASA Astrophysics Data System (ADS)

Lansdown, Katrina; Heppell, Kate; Ullah, Sami; Heathwaite, A. Louise; Trimmer, Mark; Binley, Andrew; Heaton, Tim; Zhang, Hao

2010-05-01

The dynamics of groundwater and surface water mixing and associated nitrogen transformations in the hyporheic zone have been investigated within a gaining reach of a groundwater-fed river (River Leith, Cumbria, UK). The regional aquifer consists of Permo-Triassic sandstone, which is overlain by varying depths of glaciofluvial sediments (~15 to 50 cm) to form the river bed. The reach investigated (~250m long) consists of a series of riffle and pool sequences (Käser et al. 2009), with other geomorphic features such as vegetated islands and marginal bars also present. A network of 17 piezometers, each with six depth-distributed pore water samplers based on the design of Rivett et al. (2008), was installed in the river bed in June 2009. An additional 18 piezometers with a single pore water sampler were installed in the riparian zone along the study reach. Water samples were collected from the pore water samplers on three occasions during summer 2009, a period of low flow. The zone of groundwater-surface water mixing within the river bed sediments was inferred from depth profiles (0 to 100 cm) of conservative chemical species and isotopes of water with the collected samples. Sediment cores collected during piezometer installation also enabled characterisation of grain size within the hyporheic zone. A multi-component mixing model was developed to quantify the relative contributions of different water sources (surface water, groundwater and bank exfiltration) to the hyporheic zone. Depth profiles of ‘predicted' nitrate concentration were constructed using the relative contribution of each water source to the hyporheic and the nitrate concentration of the end members. This approach assumes that the mixing of different sources of water is the only factor controlling the nitrate concentration of pore water in the river bed sediments. Comparison of predicted nitrate concentrations (which assume only mixing of waters with different nitrate concentrations) with actual nitrate concentrations (measured from samples collected in the field) then allows patches of biogeochemical activity to be identified. The depth of the groundwater-surface water mixing zone was not uniform along the study reach or over the three sampling periods, varying from <10 to 50 cm in depth. The influence of factors such as the strength of groundwater upwelling, channel geomorphology, substrate composition (permeability) and river discharge on the extent of groundwater-surface mixing have been investigated. During the three field campaigns conducted, groundwater nitrate concentrations (100 cm) were higher than surface water nitrate concentrations (3.7 ± 0.4 mg N/L versus 2.0 ± 0.03 mg N/L; p < 0.001; n = 27), indicating that throughout the reach investigated groundwater will supply nitrate to the overlying water column unless nitrate attenuation occurs along the upwelling flow path. Actual (measured) pore water nitrate concentrations often differed from concentrations predicted using the mixing model, which suggests that biogeochemical transformations also affected nitrate concentrations in the hyporheic zone. The initial field data suggested that there were regions of both nitrate production and nitrate consumption in the subsurface sediments, and that these zones may extend beyond the depths commonly associated with the hyporheic zone. This research demonstrates that a multi-component mixing model can be used to identify possible hotspots of nitrate production or consumption in the bed of a groundwater-fed river. Käser, DH, Binley, A, Heathwaite, AL and Krause, S (2009) Spatio-temporal variations of hyporheic flow in a riffle-pool sequence. Hydrological Processes 23: 2138 - 2149. Rivett, MO, Ellis, PA, Greswell, RB, Ward, RS, Roche, RS, Cleverly, MG, Walker, C, Conran, D, Fitzgerald, PJ, Willcox, T and Dowle, J (2008) Cost-effective mini drive-point piezometers and multilevel samplers for monitoring the hyporheic zone. Quarterly Journal of Engineering Geology and Hydrogeology 41: 49 - 60.

Formation of budesonide/α-lactose glass solutions by ball-milling

NASA Astrophysics Data System (ADS)

Dudognon, E.; Willart, J. F.; Caron, V.; Capet, F.; Larsson, T.; Descamps, M.

2006-04-01

The possibility to obtain amorphous budesonide stabilised by blending with an excipient characterised by a higher glass transition temperature, namely α-lactose, has been studied. We carried out the mixing of the two compounds at room temperature by ball-milling. The four obtained blends (containing, respectively, 10, 30, 50 and 70% w of budesonide) are X-ray amorphous and exhibit a single glass transition located between the ones of pure milled crystalline compounds. This revealed that the two amorphous phases are miscible whatever the composition and sufficiently mixed to relax as a whole. Ball-milling thus appears as a powerful tool to form amorphous molecular alloys with enhanced stability properties.

Facts and controversies in mixed connective tissue disease.

PubMed

Martínez-Barrio, Julia; Valor, Lara; López-Longo, F Javier

2018-01-12

Mixed connective tissue disease (MCTD) is a systemic autoimmune rheumatic disease (SARD) characterised by the combination of clinical manifestations of systemic lupus erythematosus (SLE), cutaneous systemic sclerosis (SSc) and polymyositis-dermatomyositis, in the presence of elevated titers of anti-U1-RNP antibodies. Main symptoms of the disease are polyarthritis, hand oedema, Raynaud's phenomenon, sclerodactyly, myositis and oesophageal hypomobility. Although widely discussed, most authors today accept MCTD as an independent entity. Others, however, suggest that these patients may belong to subgroups or early stages of certain definite connective diseases, such as SLE or SSc, or are, in fact, SARD overlap syndromes. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Proton imaging of stochastic magnetic fields

NASA Astrophysics Data System (ADS)

Bott, A. F. A.; Graziani, C.; Tzeferacos, P.; White, T. G.; Lamb, D. Q.; Gregori, G.; Schekochihin, A. A.

2017-12-01

Recent laser-plasma experiments (Fox et al., Phys. Rev. Lett., vol. 111, 2013, 225002; Huntington et al., Nat. Phys., vol. 11(2), 2015, 173-176 Tzeferacos et al., Phys. Plasmas, vol. 24(4), 2017a, 041404; Tzeferacos et al., 2017b, arXiv:1702.03016 [physics.plasm-ph]) report the existence of dynamically significant magnetic fields, whose statistical characterisation is essential for a complete understanding of the physical processes these experiments are attempting to investigate. In this paper, we show how a proton-imaging diagnostic can be used to determine a range of relevant magnetic-field statistics, including the magnetic-energy spectrum. To achieve this goal, we explore the properties of an analytic relation between a stochastic magnetic field and the image-flux distribution created upon imaging that field. This `Kugland image-flux relation' was previously derived (Kugland et al., Rev. Sci. Instrum. vol. 83(10), 2012, 101301) under simplifying assumptions typically valid in actual proton-imaging set-ups. We conclude that, as with regular electromagnetic fields, features of the beam's final image-flux distribution often display a universal character determined by a single, field-scale dependent parameter - the contrast parameter s/{\\mathcal{M}}lB$ - which quantifies the relative size of the correlation length B$ of the stochastic field, proton displacements s$ due to magnetic deflections and the image magnification . For stochastic magnetic fields, we establish the existence of four contrast regimes, under which proton-flux images relate to their parent fields in a qualitatively distinct manner. These are linear, nonlinear injective, caustic and diffusive. The diffusive regime is newly identified and characterised. The nonlinear injective regime is distinguished from the caustic regime in manifesting nonlinear behaviour, but as in the linear regime, the path-integrated magnetic field experienced by the beam can be extracted uniquely. Thus, in the linear and nonlinear injective regimes we show that the magnetic-energy spectrum can be obtained under a further statistical assumption of isotropy. This is not the case in the caustic or diffusive regimes. We discuss complications to the contrast-regime characterisation arising for inhomogeneous, multi-scale stochastic fields, which can encompass many contrast regimes, as well as limitations currently placed by experimental capabilities on one's ability to extract magnetic-field statistics. The results presented in this paper are of consequence in providing a comprehensive description of proton images of stochastic magnetic fields, with applications for improved analysis of proton-flux images.

Model-based characterisation of growth performance and l-lactic acid production with high optical purity by thermophilic Bacillus coagulans in a lignin-supplemented mixed substrate medium.

PubMed

Glaser, Robert; Venus, Joachim

2017-07-25

Three Bacillus coagulans strains were characterised in terms of their ability to grow in lignin-containing fermentation media and to consume the lignocellulose-related sugars glucose, xylose, and arabinose. An optical-density high-throughput screening was used for precharacterisation by means of different mathematical models for comparison (Logistic, Gompertz, Baranyi, Richards & Stannard, and Schnute). The growth response was characterised by the maximum growth rate and lag time. For a comparison of the screening and fermentation results, an unstructured mathematical model was proposed to characterise the lactate production, bacterial growth and substrate consumption. The growth model was then applied to fermentation procedures using wheat straw hydrolysates. The results indicated that the unstructured growth model can be used to evaluate lactate producing fermentation. Under the experimental fermentation conditions, one strain showed the ability to tolerate a high lignin concentration (2.5g/L) but lacked the capacity for sufficient pentose uptake. The lactate yield of the strains that were able to consume all sugar fractions of glucose, xylose and arabinose was ∼83.4%. A photometric measurement at 280nm revealed a dynamic change in alkali-lignin concentrations during lactate producing fermentation. A test of decolourisation of vanillin, ferulic acid, and alkali-lignin samples also showed the decolourisation performance of the B. coagulans strains under study. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Beyond Constructivism: The Progressive Research Programme into Learning Science

ERIC Educational Resources Information Center

Taber, Keith S.

2006-01-01

In this paper, it is suggested that while there are a variety of frames or perspectives that guide research into learning science, a pre-paradigmatic field need not be a "free-for-all". Lakatos suggested that academic research fields were characterised by research programmes (RP), which offered heuristic guidance to researchers, and which…

Statistical steady states in turbulent droplet condensation

NASA Astrophysics Data System (ADS)

Bec, Jeremie; Krstulovic, Giorgio; Siewert, Christoph

2017-11-01

We investigate the general problem of turbulent condensation. Using direct numerical simulations we show that the fluctuations of the supersaturation field offer different conditions for the growth of droplets which evolve in time due to turbulent transport and mixing. This leads to propose a Lagrangian stochastic model consisting of a set of integro-differential equations for the joint evolution of the squared radius and the supersaturation along droplet trajectories. The model has two parameters fixed by the total amount of water and the thermodynamic properties, as well as the Lagrangian integral timescale of the turbulent supersaturation. The model reproduces very well the droplet size distributions obtained from direct numerical simulations and their time evolution. A noticeable result is that, after a stage where the squared radius simply diffuses, the system converges exponentially fast to a statistical steady state independent of the initial conditions. The main mechanism involved in this convergence is a loss of memory induced by a significant number of droplets undergoing a complete evaporation before growing again. The statistical steady state is characterised by an exponential tail in the droplet mass distribution.

Synthesis, characterisation and computational studies on a novel one-dimensional arrangement of Schiff-base Mn3 single-molecule magnet.

PubMed

Lin, Po-Heng; Gorelsky, Serge; Savard, Didier; Burchell, Tara J; Wernsdorfer, Wolfgang; Clérac, Rodolphe; Murugesu, Muralee

2010-09-07

The syntheses, structures and magnetic properties are reported for three new manganese complexes containing the Schiff-base ((2-hydroxy-3-methoxyphenyl)methylene)isonicotinohydrazine (H(2)hmi) ligand. Complex [Mn(II)(H(2)hmi)(2)(MeOH)(2)Cl(2)] (1) was obtained from the reaction of H(2)hmi with MnCl(2) in a MeOH-MeCN mixture. Addition of triethylamine to the previous reaction mixture followed by diethyl ether diffusion yielded a dinuclear manganese [Mn(III)(2)(hmi)(2)(OMe)(2)](infinity).2MeCN.2OEt(2) (2) compound. Upon increasing the MnCl(2)/H(2)hmi ratio, the mixed valence complex [Mn(III)(2)Mn(II)(hmi)(2)(OMe)(2)Cl(2)](infinity).MeOH (3) was obtained. Dc and ac magnetic measurements were carried out on all three samples. The ac susceptibility and field dependence of the magnetisation measurements confirmed that complex 3 exhibits a single-molecule magnet behaviour with an effective energy barrier of 8.1 K and an Arrhenius pre-exponential factor of 3 x 10(-9) s.

Characterisation of the properties of a negative hydrogen ion beam by several beam diagnostic techniques

NASA Astrophysics Data System (ADS)

Maurizio, R.; Fantz, U.; Bonomo, F.; Serianni, G.

2016-06-01

The beam properties of the BATMAN negative ion source, which is the prototype of one module of the source for the ITER neutral beam injection system, are characterised by means of three diagnostic techniques: beam emission spectroscopy (BES), the experimental calorimeter mini-STRIKE and a copper calorimeter. The main beam parameters—beam divergence, homogeneity and top-bottom asymmetries—are studied in different operational scenarios: with different magnetic filter field setups, source settings and with different gases (hydrogen or deuterium). Among all dependences, the influence of the magnetic field configuration on the beam and the evolution of the beam features during some conditioning days are investigated in detail. Data show that the stronger the filter field in the beam region, the higher the beam top-bottom asymmetry—likely a v× B effect. During the conditioning of the source, such vertical beam asymmetry increases as well, suggesting an inhomogeneous H -production at the first grid of the extraction system.

Radiation response and basic dosimetric characterisation of the ‘Magic Plate’

NASA Astrophysics Data System (ADS)

Alrowaili, Z. A.; Lerch, M.; Petasecca, M.; Carolan, M.; Rosenfeld, A.

2017-02-01

Two Dimensional (2D) silicon diode arrays are often implemented in radiation therapy quality assurance (QA) applications due to their advantages such as: real-time operation (compared to the films), large dynamic range and small size (compared to ionization chambers). The Centre for Medical Radiation Physics, University of Wollongong has developed a multifunctional 2D silicon diode array known as the Magic Plate (MP) for real-time applications and is suitable as a transmission detector for photon flunce mapping (MPTM) or for in phantom dose mapping (MPDM). The paper focusses on the characterisation of the MPDM in terms of output factor and square field beam profiling in 6 MV, 10 MV and 18 MV clinical photon fields. We have found excellent agreement with three different ion chambers for all measured parameters with output factors agreeing within 1.2% and field profiles agreeing within 3% and/or 3mm. This work has important implications for the development of the MP when operating in transmission mapping mode.

Development of a Geant4 application to characterise a prototype neutron detector based on three orthogonal 3He tubes inside an HDPE sphere.

PubMed

Gracanin, V; Guatelli, S; Prokopovich, D; Rosenfeld, A B; Berry, A

2017-01-01

The Bonner Sphere Spectrometer (BSS) system is a well-established technique for neutron dosimetry that involves detection of thermal neutrons within a range of hydrogenous moderators. BSS detectors are often used to perform neutron field surveys in order to determine the ambient dose equivalent H*(10) and estimate health risk to personnel. There is a potential limitation of existing neutron survey techniques, since some detectors do not consider the direction of the neutron field, which can result in overly conservative estimates of dose in neutron fields. This paper shows the development of a Geant4 simulation application to characterise a prototype neutron detector based on three orthogonal 3 He tubes inside a single HDPE sphere built at the Australian Nuclear Science and Technology Organisation (ANSTO). The Geant4 simulation has been validated with respect to experimental measurements performed with an Am-Be source. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Finger printing of mixed contaminants from former manufactured gas plant (MGP) site soils: Implications to bioremediation.

PubMed

Thavamani, Palanisami; Megharaj, Mallavarapu; Krishnamurti, G S R; McFarland, Ross; Naidu, Ravi

2011-01-01

Contaminants in general do not occur as single chemicals but as mixtures at any contaminated site. Gasworks sites are the typical mixed contaminated sites. These sites are not only subjected to PAH contamination but also varying degrees of heavy metal contamination. Bioremediation in these sites is often hindered by the presence of heavy metals. The co-occurrence of PAHs with heavy metals has not been systematically investigated. Metals are reported to inhibit the general soil microbiological processes. The total concentration of soluble metal in the system includes both free metal ion and complexed forms. Within bioavailable fraction, the most toxic form is the free metal species, which was not addressed well so far in gas works site characterisation. This study underpins the science and importance of metal bioavailability and speciation based site characterisation in mixed contaminated sites. In this study a detailed elemental chemistry of the gas works site soils are discussed using different methods. The PAH contamination was contributed by both low and high molecular weight PAHs. The total PAHs concentration ranged from 335 to 8645 mg/kg. Among most toxic metals Pb was found in high concentration ranging from 88 to 671 mg/kg, Cd 8 to 112 mg/kg and Zn varied from 64 to 488 mg/kg. Thermodynamic chemical equilibrium model VMINTEQ (Ver 2.52) was used to calculate the free metal species in gas works site soils. The percentage free metal species showed a different trend compared to total metal concentrations, free Zn species ranged 18-86%, free Cd was 26-87% and Pb showed lowest free metal percentage (0-17%). The bioavailable metal species and its implications to bioremediation have also been discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

ESEEM of industrial silica-bearing powders: reactivity of defects during wet processing in the ceramics production

NASA Astrophysics Data System (ADS)

Romanelli, Maurizio; Di Benedetto, Francesco; Fornaciai, Gabriele; Innocenti, Massimo; Montegrossi, Giordano; Pardi, Luca A.; Zoleo, Alfonso; Capacci, Fabio

2015-05-01

A study is undertaken to ascertain whether changes in the speciation of inorganic radicals are occurring during the ceramic industrial production that involves abundant silica powders as raw material. Industrial dusts were sampled in two ceramic firms, immediately after the wet mixing stage, performed with the aid of a relevant pressure. The dusts were then characterised by means of X-ray diffraction, analysis of the trace elements through chemical methods, granulometry, continuous-wave electron paramagnetic resonance (EPR) and pulsed electron spin echo envelope modulation (ESEEM) spectroscopies. The results of the characterisation point to a relevant change in the speciation of the two samples; namely, a prevailing contribution due to an inorganic radical different from that pertaining to pure quartz is pointed out. The combined interpretation of EPR and ESEEM data suggests the attribution of the main paramagnetic contribution to the A-centre in kaolinite, a constituent that is added to pure quartz at the initial stage of the ceramic production. In one of the two samples, a second weak EPR signal is attributed to the quartz's hAl species. By taking into account the relative quantities of quartz and kaolinite mixed in the two samples, and the relative abundances of the two radical species, we propose that the partial or complete suppression of the hAl species in favour of the A-centre of kaolinite has occurred. Although this change is apparently fostered by the mixture between quartz and another radical-bearing raw material, kaolinite, the suppression of the hAl centre of quartz is ascribed to the role played by the pressure and the wet environment during the industrial mixing procedure. This suppression provides a net change of radical speciation associated with quartz, when this phase is in contact with workers' respiratory system.

What factors drive copepod community distribution in the Gulf of Gabes, Eastern Mediterranean Sea?

PubMed

Drira, Zaher; Bel Hassen, Malika; Ayadi, Habib; Aleya, Lotfi

2014-02-01

The spatial and temporal variations in copepod communities were investigated during four oceanographic cruises conducted between July 2005 and March 2007 aboard the R/V Hannibal. A close relationship was observed between the temperature, salinity, hydrographic properties and water masses characterising the Gulf of Gabes. Indeed, water thermal stratification began in May-June, and a thermocline was established at a 20-m depth, but ranged from 25 m in July to more than 30 m in September. The zooplankton community is dominated by copepods representing 69 % to 83 % of total zooplankton. Spatial and temporal variation of copepods in relation to environmental factors shows their close relationship with the hydrodynamic features of the water column. Thermal stratification in the column, established in summer, supports copepod development. In fact, copepod abundance increases gradually with rising water temperature and salinity, starting from the beginning of thermal stratification (May-June 2006) and lasting until its completion (July 2005 and September 2006). When the water column is well mixed (March 2007), copepod abundance decreased. Our finding shows that temperature and salinity seem to be the most important physical factors and thus strongly influence the taxonomic diversity and distribution of the copepod population. They are characterised by the dominance of Oithona nana, representing 75-86 % of total cyclopoid abundance. The most abundant species during the stratification period were O. nana, Acartia clausi and Stephos marsalensis in July 2005 and September 2006. However, during the mixing period, Euterpina acutifrons was more abundant, representing 21 % of the total. Unlike the copepod community, which is more abundant during the period of high stratification, phytoplankton proliferates during semi-mixed conditions.

Optimisation of industrial wastes reuse as construction materials.

PubMed

Collivignarelli, C; Sorlini, S

2001-12-01

This study concerns the reuse of two inorganic wastes, foundry residues and fly ashes from municipal solid waste incineration, as "recycled aggregate" in concrete production. This kind of reuse was optimised by waste treatment with the following steps: waste washing with water; waste stabilisation-solidification treatment with inorganic reagents; final grinding of the stabilised waste after curing for about 10-20 days. Both the treated wastes were reused in concrete production with different mix-designs. Concrete specimens were characterised by means of conventional physical-mechanical tests (compression, elasticity modulus, shrinkage) and different leaching tests. Experimental results showed that a good structural and environmental quality of "recycled concrete" is due both to a correct waste treatment and to a correct mix-design for concrete mixture.

Numerical analysis of scalar dissipation length-scales and their scaling properties

NASA Astrophysics Data System (ADS)

Vaishnavi, Pankaj; Kronenburg, Andreas

2006-11-01

Scalar dissipation rate, χ, is fundamental to the description of scalar-mixing in turbulent non-premixed combustion. Most contributions to the statistics for χ come from the finest turbulent mixing-scales and thus its adequate characterisation requires good resolution. Reliable χ-measurement is complicated by the trade-off between higher resolution and greater signal-to-noise ratio. Thus, the present numerical study utilises the error-free mixture fraction, Z, and fluid mechanical data from the turbulent reacting jet DNS of Pantano (2004). The aim is to quantify the resolution requirements for χ-measurement in terms of easily measurable properties of the flow like the integral-scale Reynolds number, Reδ, using spectral and spatial-filtering [cf. Barlow and Karpetis (2005)] analyses. Analysis of the 1-D cross-stream dissipation spectra enables the estimation of the dissipation length scales. It is shown that these spectrally-computed scales follow the expected Kolmogorov scaling with Reδ-0.75 . The work also involves local smoothening of the instantaneous χ-field over a non-overlapping spatial-interval (filter-width, wf), to study the smoothened χ-value as a function of wf, as wf is extrapolated to the smallest scale of interest. The dissipation length-scales thus captured show a stringent Reδ-1 scaling, compared to the usual Kolmogorov-type. This concurs with the criterion of 'resolution adequacy' of the DNS, as set out by Sreenivasan (2004) using the theory of multi-fractals.

Time-dependent analysis of the mixed-field orientation of molecules without rotational symmetry

NASA Astrophysics Data System (ADS)

Thesing, Linda V.; Küpper, Jochen; González-Férez, Rosario

2017-06-01

We present a theoretical study of the mixed-field orientation of molecules without rotational symmetry. The time-dependent one-dimensional and three-dimensional orientation of a thermal ensemble of 6-chloropyridazine-3-carbonitrile molecules in combined linearly or elliptically polarized laser fields and tilted dc electric fields is computed. The results are in good agreement with recent experimental results of one-dimensional orientation for weak dc electric fields [J. L. Hansen, J. Chem. Phys. 139, 234313 (2013)]. Moreover, they predict that using elliptically polarized laser fields or strong dc fields, three-dimensional orientation is obtained. The field-dressed dynamics of excited rotational states is characterized by highly non-adiabatic effects. We analyze the sources of these non-adiabatic effects and investigate their impact on the mixed-field orientation for different field configurations in mixed-field-orientation experiments.

Direct observation of light focusing by single photoreceptor cell nuclei.

PubMed

Błaszczak, Zuzanna; Kreysing, Moritz; Guck, Jochen

2014-05-05

The vertebrate retina is inverted with respect to its optical function, which requires light to pass through the entire tissue prior to detection. The last significant barrier for photons to overcome is the outer nuclear layer formed by photoreceptor cell (PRC) nuclei. Here we experimentally characterise the optical properties of PRC nuclei using bright-field defocusing microscopy to capture near-field intensity distributions behind individual nuclei. We find that some nuclei efficiently focus incident light confirming earlier predictions based on comparative studies of chromatin organisation in nocturnal and diurnal mammals. The emergence of light focusing during the development of mouse nuclei highlights the acquired nature of the observed lens-like behaviour. Optical characterisation of these nuclei is an important first step towards an improved understanding of how light transmission through the retina is influenced by its constituents.

The Fourth Sociology and Music Education: Towards a Sociology of Integration

ERIC Educational Resources Information Center

Wright, Ruth

2014-01-01

By identifying three main sociologies that characterise broad movements in the field since its inception, this paper provides a background to considerations of music education from the perspective of sociology. A fourth sociology is then proposed that may be useful to interrogate the complexities of the field of 21st century music education. This…

Exploring the Emotions in Pedagogical Content Knowledge about the Electric Field

ERIC Educational Resources Information Center

Melo, Lina; Cañada, Florentina; Mellado, Vicente

2017-01-01

The objective of this study was to characterise the changes in the Pedagogical Content Knowledge (PCK) about electric fields of two Colombian physics teachers (Isabel and Alejandro) at the high school level (pupils of ages 17-19), the emotions and their relationship with PCK. The research was conducted during two consecutive years, before and…

Experimental procedures characterizing firebrand generation in wildland fires

Treesearch

Mohamad El Houssami; Eric Mueller; Alexander Filkov; Jan C Thomas; Nicholas Skowronski; Michael R Gallagher; Ken Clark; Robert Kremens; Albert Simeoni

2016-01-01

This study aims to develop a series of robust and efficient methodologies, which can be applied to understand and estimate firebrand generation and to evaluate firebrand showers close to a fire front. A field scale high intensity prescribed fire was conducted in the New Jersey Pine Barrens in March 2013. Vegetation was characterised with field and remotely sensed data...

Dyscalculia ? Maths Difficulties. An Analysis of Conflicting Positions at a Time That Calls for Inclusive Practices

ERIC Educational Resources Information Center

Schmidt, Maria Christina Secher

2016-01-01

Using Bourdieu's notion of field, the Scandinavian field of maths pedagogy occurs at a time characterised by increasing inclusion efforts in primary school. Various stakeholders in maths pedagogy are arguing about what should be done about pupils who perform poorly in mathematics and what causes their difficulties. Four analytical positions are…

Alabama warm mix asphalt field study : final report.

DOT National Transportation Integrated Search

2010-05-01

The Alabama Department of Transportation hosted a warm mix asphalt field demonstration in August 2007. The warm mix asphalt technology demonstrated was Evotherm Dispersed Asphalt Technology. The WMA and hot mix asphalt produced for the demonstration ...

Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo

NASA Astrophysics Data System (ADS)

Cook, Joseph M.; Hodson, Andrew J.; Gardner, Alex S.; Flanner, Mark; Tedstone, Andrew J.; Williamson, Christopher; Irvine-Fynn, Tristram D. L.; Nilsson, Johan; Bryant, Robert; Tranter, Martyn

2017-11-01

The darkening effects of biological impurities on ice and snow have been recognised as a control on the surface energy balance of terrestrial snow, sea ice, glaciers and ice sheets. With a heightened interest in understanding the impacts of a changing climate on snow and ice processes, quantifying the impact of biological impurities on ice and snow albedo (bioalbedo) and its evolution through time is a rapidly growing field of research. However, rigorous quantification of bioalbedo has remained elusive because of difficulties in isolating the biological contribution to ice albedo from that of inorganic impurities and the variable optical properties of the ice itself. For this reason, isolation of the biological signature in reflectance data obtained from aerial/orbital platforms has not been achieved, even when ground-based biological measurements have been available. This paper provides the cell-specific optical properties that are required to model the spectral signatures and broadband darkening of ice. Applying radiative transfer theory, these properties provide the physical basis needed to link biological and glaciological ground measurements with remotely sensed reflectance data. Using these new capabilities we confirm that biological impurities can influence ice albedo, then we identify 10 challenges to the measurement of bioalbedo in the field with the aim of improving future experimental designs to better quantify bioalbedo feedbacks. These challenges are (1) ambiguity in terminology, (2) characterising snow or ice optical properties, (3) characterising solar irradiance, (4) determining optical properties of cells, (5) measuring biomass, (6) characterising vertical distribution of cells, (7) characterising abiotic impurities, (8) surface anisotropy, (9) measuring indirect albedo feedbacks, and (10) measurement and instrument configurations. This paper aims to provide a broad audience of glaciologists and biologists with an overview of radiative transfer and albedo that could support future experimental design.

Understanding the value of mixed methods research: the Children's Safety Initiative-Emergency Medical Services.

PubMed

Hansen, Matthew; O'Brien, Kerth; Meckler, Garth; Chang, Anna Marie; Guise, Jeanne-Marie

2016-07-01

Mixed methods research has significant potential to broaden the scope of emergency care and specifically emergency medical services investigation. Mixed methods studies involve the coordinated use of qualitative and quantitative research approaches to gain a fuller understanding of practice. By combining what is learnt from multiple methods, these approaches can help to characterise complex healthcare systems, identify the mechanisms of complex problems such as medical errors and understand aspects of human interaction such as communication, behaviour and team performance. Mixed methods approaches may be particularly useful for out-of-hospital care researchers because care is provided in complex systems where equipment, interpersonal interactions, societal norms, environment and other factors influence patient outcomes. The overall objectives of this paper are to (1) introduce the fundamental concepts and approaches of mixed methods research and (2) describe the interrelation and complementary features of the quantitative and qualitative components of mixed methods studies using specific examples from the Children's Safety Initiative-Emergency Medical Services (CSI-EMS), a large National Institutes of Health-funded research project conducted in the USA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

SU-E-T-137: The Response of TLD-100 in Mixed Fields of Photons and Electrons.

PubMed

Lawless, M; Junell, S; Hammer, C; DeWerd, L

2012-06-01

Thermoluminescent dosimeters are used routinely for dosimetric measurements of photon and electron fields. However, no work has been published characterizing TLDs for use in combined photon and electron fields. This work investigates the response of TLD-100 (LiF:Mg,Ti) in mixed fields of photon and electron beam qualities. TLDs were irradiated in a 6 MV photon beam, 6 MeV electron beam, and a NIST traceable cobalt-60 beam. TLDs were also irradiated in a mixed field of the electron and photon beams. All irradiations were normalized to absorbed dose to water as defined in the AAPM TG-51 report. The average response per dose (nC/Gy) for each linac beam quality was normalized to the average response per dose of the TLDs irradiated by the cobalt-60 standard.Irradiations were performed in a water tank and a Virtual Water™ phantom. Two TLD dose calibration curves for determining absorbed dose to water were generated using photon and electron field TLD response data. These individual beam quality dose calibration curves were applied to the TLDs irradiated in the mixed field. The TLD response in the mixed field was less sensitive than the response in the photon field and more sensitive than the response in the electron field. TLD determination of dose in the mixed field using the dose calibration curve generated by TLDs irradiated by photons resulted in an underestimation of the delivered dose, while the use of a dose calibration curve generated using electrons resulted in an overestimation of the delivered dose. The relative response of TLD-100 in mixed fields fell consistently between the photon nd electron relative responses. When using TLD-100 in mixed fields, the user must account for this intermediate response to avoid an over- or underestimation of the dose due to calibration in a single photon or electron field. © 2012 American Association of Physicists in Medicine.

Diffraction enhanced kinetic depth X-ray imaging

NASA Astrophysics Data System (ADS)

Dicken, A.

An increasing number of fields would benefit from a single analytical probe that can characterise bulk objects that vary in morphology and/or material composition. These fields include security screening, medicine and material science. In this study the X-ray region is shown to be an effective probe for the characterisation of materials. The most prominent analytical techniques that utilise X-radiation are reviewed. The study then focuses on methods of amalgamating the three dimensional power of kinetic depth X-ray (KDFX) imaging with the materials discrimination of angular dispersive X-ray diffraction (ADXRD), thus providing KDEX with a much needed material specific counterpart. A knowledge of the sample position is essential for the correct interpretation of diffraction signatures. Two different sensor geometries (i.e. circumferential and linear) that are able to collect end interpret multiple unknown material diffraction patterns and attribute them to their respective loci within an inspection volume are investigated. The circumferential and linear detector geometries are hypothesised, simulated and then tested in an experimental setting with the later demonstrating a greater ability at discerning between mixed diffraction patterns produced by differing materials. Factors known to confound the linear diffraction method such as sample thickness and radiation energy have been explored and quantified with a possible means of mitigation being identified (i.e. via increasing the sample to detector distance). A series of diffraction patterns (following the linear diffraction approach) were obtained from a single phantom object that was simultaneously interrogated via KDEX imaging. Areas containing diffraction signatures matched from a threat library have been highlighted in the KDEX imagery via colour encoding and match index is inferred by intensity. This union is the first example of its kind and is called diffraction enhanced KDEX imagery. Finally an additional source of information obtained from object disparity is explored as an alternative means of calculating sample loci. This offers a greater level of integration between these two complimentary techniques as object disparity could be used to reinforce the results produced by the linear diffraction geometry.

Markers for Chinese and Korean Air Masses: Halocarbons and Other Trace Gases Measured During KORUS-AQ

NASA Astrophysics Data System (ADS)

Blake, N. J.; Blake, D. R.; Meinardi, S.; Simpson, I. J.; Hughes, S.; Barletta, B.; Fleming, L.; Vizenor, N.; Schroeder, J.; Emmons, L. K.; Knote, C. J.

2017-12-01

The UC-Irvine Whole Air Sampler (WAS) collected a total of 2650 samples aboard the NASA DC-8 aircraft in support of the May-June 2016 field deployment phase of the KORUS-AQ mission: An International Cooperative Air Quality Field Study in Korea. Here we employ our trace gas measurements, along with CAM-chem tracers and back-trajectories to identify source regions during KORUS-AQ, with a focus on air masses which indicate Chinese and/or Korean origin. During KORUS-AQ we flew mostly over and around the Korean Peninsula with the intent of characterising Korean sources, but Chinese influence was observed offshore near the surface of the West Sea during several KORUS-AQ flights - in accord with forecast predictions from CAM-chem model runs. Unlike previous missions in the Asian region such as TRACE-P (2001), we found that halon-1211 (H-1211) is no longer a useful indicator of air masses from China because of production decline. By contrast, mixing ratios of the long-lived halocarbons carbon tetrachloride (CCl4) and chlorofluorocarbon-113 (CFC-113) were more strongly enhanced in air masses intercepted from China compared to Korea. We will use these tracers, the shorter-lived halocarbons, dichloromethane (CH2Cl2) and methyl chloride (CH3Cl), as well as the sulfur gas carbonyl sulfide (COS) and others, to characterize different regional air mass origins and their sources.

Analysis of Electrokinetic Mixing Using AC Electric Field and Patchwise Surface Heterogeneities

NASA Astrophysics Data System (ADS)

Luo, Win-Jet; Yarn, Kao-Feng; Hsu, Shou-Ping

2007-04-01

In this paper, the authors investigate the use of an applied AC electric field and microchannel surface heterogeneities to carry out the microfluidic mixing of two-dimensional, time-dependent electroosmotic flows. The time-dependent flow fields within the microchannel are simulated using the backwards-Euler time-stepping numerical method. The mixing efficiencies obtained in microchannels with two different patchwise surface heterogeneity patterns are investigated. In general, the results show that the application of an AC electric field significantly reduces the required mixing length compared with the use of a DC electric field. Furthermore, the presence of oppositely charged surface heterogeneities on the microchannel walls results in the formation of localized flow circulation regions within the bulk flow. These circulation regions grow and decay periodically in accordance with the periodic variation of the AC electric field intensity and provide an effective means of enhancing species mixing in the microchannel. Consequently, the use of an AC electric field together with patchwise surface heterogeneities permits a significant reduction in both the mixing channel length and the retention time required to attain a homogeneous solution.

Bi-photon spectral correlation measurements from a silicon nanowire in the quantum and classical regimes

PubMed Central

Jizan, Iman; Helt, L. G.; Xiong, Chunle; Collins, Matthew J.; Choi, Duk-Yong; Joon Chae, Chang; Liscidini, Marco; Steel, M. J.; Eggleton, Benjamin J.; Clark, Alex S.

2015-01-01

The growing requirement for photon pairs with specific spectral correlations in quantum optics experiments has created a demand for fast, high resolution and accurate source characterisation. A promising tool for such characterisation uses classical stimulated processes, in which an additional seed laser stimulates photon generation yielding much higher count rates, as recently demonstrated for a χ(2) integrated source in A. Eckstein et al. Laser Photon. Rev. 8, L76 (2014). In this work we extend these results to χ(3) integrated sources, directly measuring for the first time the relation between spectral correlation measurements via stimulated and spontaneous four wave mixing in an integrated optical waveguide, a silicon nanowire. We directly confirm the speed-up due to higher count rates and demonstrate that this allows additional resolution to be gained when compared to traditional coincidence measurements without any increase in measurement time. As the pump pulse duration can influence the degree of spectral correlation, all of our measurements are taken for two different pump pulse widths. This allows us to confirm that the classical stimulated process correctly captures the degree of spectral correlation regardless of pump pulse duration, and cements its place as an essential characterisation method for the development of future quantum integrated devices. PMID:26218609

Quantitative characterisation of audio data by ordinal symbolic dynamics

NASA Astrophysics Data System (ADS)

Aschenbrenner, T.; Monetti, R.; Amigó, J. M.; Bunk, W.

2013-06-01

Ordinal symbolic dynamics has developed into a valuable method to describe complex systems. Recently, using the concept of transcripts, the coupling behaviour of systems was assessed, combining the properties of the symmetric group with information theoretic ideas. In this contribution, methods from the field of ordinal symbolic dynamics are applied to the characterisation of audio data. Coupling complexity between frequency bands of solo violin music, as a fingerprint of the instrument, is used for classification purposes within a support vector machine scheme. Our results suggest that coupling complexity is able to capture essential characteristics, sufficient to distinguish among different violins.

Diluted Magnetic Semiconductors for Magnetic Field Tunable Infrared Detectors

DTIC Science & Technology

2005-06-30

significantly improved performance and technological advances of quantum well infrared photodetectors (QWIPs)14 and quantum cascade lasers (QCLs)15...NUMBER FA8655-04-1-3069 5b. GRANT NUMBER 4. TITLE AND SUBTITLE Magnetic Field Tunable Terahertz Quantum Well Infrared Photodetector 5c...fabrication in II-VI materials, quantum well infrared photodetector device design and magneto-optical characterisation are all well understood

Speaking of Users: On User Discourses in the Field of Public Libraries

ERIC Educational Resources Information Center

Hedemark, Ase; Hedman, Jenny; Sundin, Olof

2005-01-01

Introduction: The aim of the study reported is to examine user discourses identified in the Swedish public library field. The following questions are posed: What user discourses can be found and what characterises them? How are users categorised and what does this categorisation imply? The departure point in this paper is that the ways users are…

Magneto-optical imaging of thin magnetic films using spins in diamond

NASA Astrophysics Data System (ADS)

Simpson, David A.; Tetienne, Jean-Philippe; McCoey, Julia M.; Ganesan, Kumaravelu; Hall, Liam T.; Petrou, Steven; Scholten, Robert E.; Hollenberg, Lloyd C. L.

2016-03-01

Imaging the fields of magnetic materials provides crucial insight into the physical and chemical processes surrounding magnetism, and has been a key ingredient in the spectacular development of magnetic data storage. Existing approaches using the magneto-optic Kerr effect, x-ray and electron microscopy have limitations that constrain further development, and there is increasing demand for imaging and characterisation of magnetic phenomena in real time with high spatial resolution. Here we show how the magneto-optical response of an array of negatively-charged nitrogen-vacancy spins in diamond can be used to image and map the sub-micron stray magnetic field patterns from thin ferromagnetic films. Using optically detected magnetic resonance, we demonstrate wide-field magnetic imaging over 100 × 100 μm2 with sub-micron spatial resolution at video frame rates, under ambient conditions. We demonstrate an all-optical spin relaxation contrast imaging approach which can image magnetic structures in the absence of an applied microwave field. Straightforward extensions promise imaging with sub-μT sensitivity and sub-optical spatial and millisecond temporal resolution. This work establishes practical diamond-based wide-field microscopy for rapid high-sensitivity characterisation and imaging of magnetic samples, with the capability for investigating magnetic phenomena such as domain wall and skyrmion dynamics and the spin Hall effect in metals.

Comparison of Mixing Calculations for Reacting and Non-Reacting Flows in a Cylindrical Duct

NASA Technical Reports Server (NTRS)

Oechsle, V. L.; Mongia, H. C.; Holdeman, J. D.

1994-01-01

A production 3-D elliptic flow code has been used to calculate non-reacting and reacting flow fields in an experimental mixing section relevant to a rich burn/quick mix/lean burn (RQL) combustion system. A number of test cases have been run to assess the effects of the variation in the number of orifices, mass flow ratio, and rich-zone equivalence ratio on the flow field and mixing rates. The calculated normalized temperature profiles for the non-reacting flow field agree qualitatively well with the normalized conserved variable isopleths for the reacting flow field indicating that non-reacting mixing experiments are appropriate for screening and ranking potential rapid mixing concepts. For a given set of jet momentum-flux ratio, mass flow ratio, and density ratio (J, MR, and DR), the reacting flow calculations show a reduced level of mixing compared to the non-reacting cases. In addition, the rich-zone equivalence ratio has noticeable effect on the mixing flow characteristics for reacting flows.

Entanglement hamiltonian and entanglement contour in inhomogeneous 1D critical systems

NASA Astrophysics Data System (ADS)

Tonni, Erik; Rodríguez-Laguna, Javier; Sierra, Germán

2018-04-01

Inhomogeneous quantum critical systems in one spatial dimension have been studied by using conformal field theory in static curved backgrounds. Two interesting examples are the free fermion gas in the harmonic trap and the inhomogeneous XX spin chain called rainbow chain. For conformal field theories defined on static curved spacetimes characterised by a metric which is Weyl equivalent to the flat metric, with the Weyl factor depending only on the spatial coordinate, we study the entanglement hamiltonian and the entanglement spectrum of an interval adjacent to the boundary of a segment where the same boundary condition is imposed at the endpoints. A contour function for the entanglement entropies corresponding to this configuration is also considered, being closely related to the entanglement hamiltonian. The analytic expressions obtained by considering the curved spacetime which characterises the rainbow model have been checked against numerical data for the rainbow chain, finding an excellent agreement.

Exploring transient X-ray sky with Einstein Probe

NASA Astrophysics Data System (ADS)

Yuan, W.; Zhang, C.; Ling, Z.; Zhao, D.; Chen, Y.; Lu, F.; Zhang, S.

2017-10-01

The Einstein Probe is a small satellite in time-domain astronomy to monitor the soft X-ray sky. It is a small mission in the space science programme of the Chinese Academy of Sciences. It will carry out systematic survey and characterisation of high-energy transients at unprecedented sensitivity, spatial resolution, Grasp and monitoring cadence. Its wide-field imaging capability is achieved by using established technology of micro-pore lobster-eye X-ray focusing optics. Complementary to this is X-ray follow-up capability enabled by a narrow-field X-ray telescope. It is capable of on-board triggering and real time downlink of transient alerts, in order to trigger fast follow-up observations at multi-wavelengths. Its scientific goals are concerned with discovering and characterising diverse types of X-ray transients, including tidal disruption events, supernova shock breakouts, high-redshift GRBs, and of particular interest, X-ray counterparts of gravitational wave events.

Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

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

Štengl, Václav, E-mail: stengl@iic.cas.cz; Henych, Jiří; Grygar, Tomáš

Nanostructured TiO{sub 2} and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m{sup 2} g{sup −1}. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures.more » Undoped TiO{sub 2} and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH{sub 3}O from TMP at room temperature and 100 °C. Cleavage of CH{sub 3}O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP.« less

Evaluation of illumination system uniformity for wide-field biomedical hyperspectral imaging

NASA Astrophysics Data System (ADS)

Sawyer, Travis W.; Siri Luthman, A.; E Bohndiek, Sarah

2017-04-01

Hyperspectral imaging (HSI) systems collect both spatial (morphological) and spectral (chemical) information from a sample. HSI can provide sensitive analysis for biological and medical applications, for example, simultaneously measuring reflectance and fluorescence properties of a tissue, which together with structural information could improve early cancer detection and tumour characterisation. Illumination uniformity is a critical pre-condition for quantitative data extraction from an HSI system. Non-uniformity can cause glare, specular reflection and unwanted shading, which negatively impact statistical analysis procedures used to extract abundance of different chemical species. Here, we model and evaluate several illumination systems frequently used in wide-field biomedical imaging to test their potential for HSI. We use the software LightTools and FRED. The analysed systems include: a fibre ring light; a light emitting diode (LED) ring; and a diffuse scattering dome. Each system is characterised for spectral, spatial, and angular uniformity, as well as transfer efficiency. Furthermore, an approach to measure uniformity using the Kullback-Leibler divergence (KLD) is introduced. The KLD is generalisable to arbitrary illumination shapes, making it an attractive approach for characterising illumination distributions. Although the systems are quite comparable in their spatial and spectral uniformity, the most uniform angular distribution is achieved using a diffuse scattering dome, yielding a contrast of 0.503 and average deviation of 0.303 over a ±60° field of view with a 3.9% model error in the angular domain. Our results suggest that conventional illumination sources can be applied in HSI, but in the case of low light levels, bespoke illumination sources may offer improved performance.

High frequency mode shapes characterisation using Digital Image Correlation and phase-based motion magnification

NASA Astrophysics Data System (ADS)

Molina-Viedma, A. J.; Felipe-Sesé, L.; López-Alba, E.; Díaz, F.

2018-03-01

High speed video cameras provide valuable information in dynamic events. Mechanical characterisation has been improved by the interpretation of the behaviour in slow-motion visualisations. In modal analysis, videos contribute to the evaluation of mode shapes but, generally, the motion is too subtle to be interpreted. In latest years, image treatment algorithms have been developed to generate a magnified version of the motion that could be interpreted by naked eye. Nevertheless, optical techniques such as Digital Image Correlation (DIC) are able to provide quantitative information of the motion with higher sensitivity than naked eye. For vibration analysis, mode shapes characterisation is one of the most interesting DIC performances. Full-field measurements provide higher spatial density than classical instrumentations or Scanning Laser Doppler Vibrometry. However, the accurateness of DIC is reduced at high frequencies as a consequence of the low displacements and hence it is habitually employed in low frequency spectra. In the current work, the combination of DIC and motion magnification is explored in order to provide numerical information in magnified videos and perform DIC mode shapes characterisation at unprecedented high frequencies through increasing the amplitude of displacements.

Microstructure and mechanical properties of arabinoxylan and (1,3;1,4)-β-glucan gels produced by cryo-gelation.

PubMed

Lopez-Sanchez, Patricia; Wang, Dongjie; Zhang, Zhiyan; Flanagan, Bernadine; Gidley, Michael J

2016-10-20

The interactions between heteroxylans and mixed linkage glucans determine the architecture and mechanical properties of cereal endosperm cell walls. In this work hydrogels made of cross-linked arabinoxylan with addition of β-glucan were synthesised by cryogelation as a biomimetic tool to investigate endosperm walls. Molecular and microstructural properties were characterised by nuclear magnetic resonance ((13)C NMR), scanning electron microscopy (SEM) and immunolabelling/confocal laser scanning microscopy (CLSM). The response to mechanical stress was studied by compression-relaxation experiments. The hydrogels consisted of a scaffold characterised by dense walls interconnected by macropores with both hemicelluloses co-localised and homogeneously distributed. The gels showed a high degree of elasticity reflected in their ability to resist compression without developing cracks and recover 60-80% of their original height. Our results highlight the compatibility of these hemicelluloses to coexist in confined environments such as cell walls and their potential role in determining mechanical properties in the absence of cellulose. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterisation of bare and tannase-loaded calcium alginate beads by microscopic, thermogravimetric, FTIR and XRD analyses.

PubMed

Larosa, Claudio; Salerno, Marco; de Lima, Juliana Silva; Merijs Meri, Remo; da Silva, Milena Fernandes; de Carvalho, Luiz Bezerra; Converti, Attilio

2018-08-01

Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and to preserve, at the same time, their catalytic activity. Sodium alginate was mixed with Aspergillus ficuum tannase in aqueous solution, and tannase-loaded calcium alginate beads were prepared using a simple droplet-based microfluidic system. Extensive experimental analysis was carried out to characterise the samples. Microscopic imaging revealed morphological differences between the surfaces of bare alginate matrix and tannase-loaded alginate beads. Thermal analysis allowed assessing the hydration contents of alginate and revealed the presence of tannase entrapped in the loaded beads, which was confirmed by vibrational spectroscopy. X-ray diffraction allowed us to conclude that alginate of tannase-loaded beads is not crystalline, which would make them suitable as carriers for possible controlled release. Moreover, they could be used in food applications to improve tea quality or clarify juices. Copyright © 2018 Elsevier B.V. All rights reserved.

Reproductive cycles of deer.

PubMed

Asher, G W

2011-04-01

The cervids are a complex assemblage of taxa showing extreme diversity in morphology, physiology, ecology and geographical distribution. Reproductive strategies adopted by various species are also diverse, and include a range from highly seasonal to completely aseasonal birth patterns. The recent growth in knowledge on cervid reproduction is strongly biased towards the larger-bodied, gregarious mixed grazer-browser species that have adapted well to human management and commercialisation. These species tend to represent 'K-selected' climax species characterised by very productive annual breeding success, singleton births and long breeding life (10+ years). Conversely, we know relatively little about the reproductive patterns of the 'r-selected' smaller-bodied, solitary (and often highly territorial), forest-dwelling browser species, often characterised by great fecundity (twinning) and shorter breeding life (<10 years). This group includes many of the endangered cervid taxa. This review extends earlier reviews to include more recent work on cervid reproductive cycles, particularly in relation to environmental factors influencing gestation length. Copyright © 2010 Elsevier B.V. All rights reserved.

Chromium and yttrium-doped magnesium aluminum oxides prepared from layered double hydroxides

NASA Astrophysics Data System (ADS)

García-García, J. M.; Pérez-Bernal, M. E.; Ruano-Casero, R. J.; Rives, V.

2007-12-01

Layered double hydroxides with the hydrotalcite-like structures, containing Mg 2+ and Al 3+, doped with Cr 3+ and Y 3+, have been prepared by precipitation at constant pH. The weight percentages of Cr 3+ and Y 3+ were 1, 2, or 3%, and 0.5 or 1%, respectively. Single phases were obtained in all cases, whose crystallinity decreased as the content in Cr and Y was increased. The solids have been characterised by element chemical analysis, powder X-ray diffraction, thermal analyses (differential, thermogravimetric and programmed reduction), FT-IR and UV-vis spectroscopies; the specific surface areas have been determined from nitrogen adsorption isotherms at -196 °C. Upon calcination at 1200 °C for 5 h in air all solids display a mixed structure (spinel and rock salt for MgO); these solids have also been characterised by these techniques and their chromatic coordinates (CIE - L∗a∗b∗) have been determined. Their pink colour makes these solids suitable for being used as ceramic pigments.

Rapid measurement of the yield stress of anaerobically-digested solid waste using slump tests.

PubMed

Garcia-Bernet, D; Loisel, D; Guizard, G; Buffière, P; Steyer, J P; Escudié, R

2011-04-01

The anaerobic digestion of solid waste is usually performed using dry or semi-dry technology. Incoming waste and fermenting digestate are pasty media and thus, at the industrial scale, their suitability for pumping and mixing is a prerequisite at the industrial scale. However, their rheology has been poorly characterised in the literature because there is no suitable experimental system for analysing heterogeneous media composed of coarse particles. We have developed a practical rheometrical test, a "slump test", for the analysis of actual digested solid waste. It makes it possible to estimate yield stress from the final slump height. From the slump behavior, we conclude that digestates behave as visco-elastic materials. The yield stress of different digested waste was measured between 200 and 800Pa. We show that the media containing smaller particles or with higher moisture content are characterised by smaller yield stresses. This study thus demonstrates the impact of the origin of the digestate on the yield stress. Copyright © 2010 Elsevier Ltd. All rights reserved.

QCD Sum Rules for Magnetically Induced Mixing between ηc and J/ψ

DOE PAGES

Cho, Sungtae; Hattori, Koichi; Lee, Su Houng; ...

2014-10-20

We investigate the properties of charmonia in strong magnetic fields by using QCD sum rules. We show how to implement the mixing effects between ηc and J/ψ on the basis of field-theoretical approaches, and then show that the sum rules are saturated by the mixing effects with phenomenologically determined parameters. Consequently, we find that the mixing effects are the dominant contribution to the mass shifts of the static charmonia in strong magnetic fields.

Field Monitoring of Experimental Hot Mix Asphalt Projects Placed in Massachusetts

DOT National Transportation Integrated Search

2017-06-30

Since 2000, Massachusetts has been involved with numerous field trials of experimental hot mix asphalt mixtures. These experimental mixtures included several pilot projects using the Superpave mixture design methodology, utilization of warm mix aspha...

Heat transfer enhancement with mixing vane spacers using the field synergy principle

NASA Astrophysics Data System (ADS)

Yang, Lixin; Zhou, Mengjun; Tian, Zihao

2017-01-01

The single-phase heat transfer characteristics in a PWR fuel assembly are important. Many investigations attempt to obtain the heat transfer characteristics by studying the flow features in a 5 × 5 rod bundle with a spacer grid. The field synergy principle is used to discuss the mechanism of heat transfer enhancement using mixing vanes according to computational fluid dynamics results, including a spacer grid without mixing vanes, one with a split mixing vane, and one with a separate mixing vane. The results show that the field synergy principle is feasible to explain the mechanism of heat transfer enhancement in a fuel assembly. The enhancement in subchannels is more effective than on the rod's surface. If the pressure loss is ignored, the performance of the split mixing vane is superior to the separate mixing vane based on the enhanced heat transfer. Increasing the blending angle of the split mixing vane improves heat transfer enhancement, the maximum of which is 7.1%. Increasing the blending angle of the separate mixing vane did not significantly enhance heat transfer in the rod bundle, and even prevented heat transfer at a blending angle of 50°. This finding testifies to the feasibility of predicting heat transfer in a rod bundle with a spacer grid by field synergy, and upon comparison with analyzed flow features only, the field synergy method may provide more accurate guidance for optimizing the use of mixing vanes.

Differential recognition of the multiple banded antigen isoforms across Ureaplasma parvum and Ureaplasma urealyticum species by monoclonal antibodies.

PubMed

Aboklaish, Ali F; Ahmed, Shatha; McAllister, Douglas; Cassell, Gail; Zheng, Xiaotian T; Spiller, Owen B

2016-08-01

Two separate species of Ureaplasma have been identified that infect humans: Ureaplasma parvum and Ureaplasma urealyticum. Most notably, these bacteria lack a cell wall and are the leading infectious organism associated with infection-related induction of preterm birth. Fourteen separate representative prototype bacterial strains, called serovars, are largely differentiated by the sequence of repeating units in the C-terminus of the major surface protein: multiple-banded antigen (MBA). Monoclonal antibodies that recognise single or small groups of serovars have been previously reported, but these reagents remain sequestered in individual research laboratories. Here we characterise a panel of commercially available monoclonal antibodies raised against the MBA and describe the first monoclonal antibody that cross-reacts by immunoblot with all serovars of U. parvum and U. urealyticum species. We also describe a recombinant MBA expressed by Escherichia coli which facilitated further characterisation by immunoblot and demonstrate immunohistochemistry of paraffin-embedded antigens. Immunoblot reactivity was validated against well characterised previously published monoclonal antibodies and individual commercial antibodies were found to recognise all U. parvum strains, only serovars 3 and 14 or only serovars 1 and 6, or all strains belonging to U. parvum and U. urealyticum. MBA mass was highly variable between strains, consistent with variation in the number of C-terminal repeats between strains. Antibody characterisation will enable future investigations to correlate severity of pathogenicity to MBA isoform number or mass, in addition to development of antibody-based diagnostics that will detect infection by all Ureaplasma species or alternately be able to differentiate between U. parvum, U. urealyticum or mixed infections. Copyright © 2016 Elsevier B.V. All rights reserved.

High-throughput SRCD using multi-well plates and its applications

NASA Astrophysics Data System (ADS)

Hussain, Rohanah; Jávorfi, Tamás; Rudd, Timothy R.; Siligardi, Giuliano

2016-12-01

The sample compartment for high-throughput synchrotron radiation circular dichroism (HT-SRCD) has been developed to satisfy an increased demand of protein characterisation in terms of folding and binding interaction properties not only in the traditional field of structural biology but also in the growing research area of material science with the potential to save time by 80%. As the understanding of protein behaviour in different solvent environments has increased dramatically the development of novel functions such as recombinant proteins modified to have different functions from harvesting solar energy to metabolonics for cleaning heavy and metal and organic molecule pollutions, there is a need to characterise speedily these system.

Theoretical description of the mixed-field orientation of asymmetric-top molecules: A time-dependent study

NASA Astrophysics Data System (ADS)

Omiste, Juan J.; González-Férez, Rosario

2016-12-01

We present a theoretical study of the mixed-field-orientation of asymmetric-top molecules in tilted static electric field and nonresonant linearly polarized laser pulse by solving the time-dependent Schrödinger equation. Within this framework, we compute the mixed-field orientation of a state-selected molecular beam of benzonitrile (C7H5N ) and compare with the experimental observations [J. L. Hansen et al., Phys. Rev. A 83, 023406 (2011), 10.1103/PhysRevA.83.023406] and with our previous time-independent descriptions [J. J. Omiste et al., Phys. Chem. Chem. Phys. 13, 18815 (2011), 10.1039/c1cp21195a]. For an excited rotational state, we investigate the field-dressed dynamics for several field configurations as those used in the mixed-field experiments. The nonadiabatic phenomena and their consequences on the rotational dynamics are analyzed in detail.

Response of TLD-100 in mixed fields of photons and electrons

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

Lawless, Michael J.; Junell, Stephanie; Hammer, Cliff

Purpose: Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. Methods: TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable {sup 60}Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam.more » The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the {sup 60}Co beam. Irradiations were performed in water and in a Virtual Water Trade-Mark-Sign phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. Results: TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. Conclusions: The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality.« less

Response of TLD-100 in mixed fields of photons and electrons.

PubMed

Lawless, Michael J; Junell, Stephanie; Hammer, Cliff; DeWerd, Larry A

2013-01-01

Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable (60)Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam. The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the (60)Co beam. Irradiations were performed in water and in a Virtual Water™ phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality.

Axisymmetric magnetic modes of neutron stars having mixed poloidal and toroidal magnetic fields

NASA Astrophysics Data System (ADS)

Lee, Umin

2018-05-01

We calculate axisymmetric magnetic modes of a neutron star possessing a mixed poloidal and toroidal magnetic field, where the toroidal field is assumed to be proportional to a dimensionless parameter ζ0. Here, we assume an isentropic structure for the neutron star and consider no effects of rotation. Ignoring the equilibrium deformation due to the magnetic field, we employ a polytrope of the index n = 1 as the background model for our modal analyses. For the mixed poloidal and toroidal magnetic field with ζ _0\

A Case Study of a Mixed Methods Study Engaged in Integrated Data Analysis

ERIC Educational Resources Information Center

Schiazza, Daniela Marie

2013-01-01

The nascent field of mixed methods research has yet to develop a cohesive framework of guidelines and procedures for mixed methods data analysis (Greene, 2008). To support the field's development of analytical frameworks, this case study reflects on the development and implementation of a mixed methods study engaged in integrated data analysis.…

Fault architecture and deformation processes within poorly lithified rift sediments, Central Greece

NASA Astrophysics Data System (ADS)

Loveless, Sian; Bense, Victor; Turner, Jenni

2011-11-01

Deformation mechanisms and resultant fault architecture are primary controls on the permeability of faults in poorly lithified sediments. We characterise fault architecture using outcrop studies, hand samples, thin sections and grain-size data from a minor (1-10 m displacement) normal-fault array exposed within Gulf of Corinth rift sediments, Central Greece. These faults are dominated by mixed zones with poorly developed fault cores and damage zones. In poorly lithified sediment deformation is distributed across the mixed zone as beds are entrained and smeared. We find particulate flow aided by limited distributed cataclasis to be the primary deformation mechanism. Deformation may be localised in more competent sediments. Stratigraphic variations in sediment competency, and the subsequent alternating distributed and localised strain causes complexities within the mixed zone such as undeformed blocks or lenses of cohesive sediment, or asperities at the mixed zone/protolith boundary. Fault tip bifurcation and asperity removal are important processes in the evolution of these fault zones. Our results indicate that fault zone architecture and thus permeability is controlled by a range of factors including lithology, stratigraphy, cementation history and fault evolution, and that minor faults in poorly lithified sediment may significantly impact subsurface fluid flow.

Judicialization 2.0: Understanding right-to-health litigation in real time.

PubMed

Biehl, João; Socal, Mariana P; Gauri, Varun; Diniz, Debora; Medeiros, Marcelo; Rondon, Gabriela; Amon, Joseph J

2018-05-21

Over the past two decades, debate over the whys, the hows, and the effects of the ever-expanding phenomenon of right-to-health litigation ('judicialization') throughout Latin America have been marked by polarised arguments and limited information. In contrast to claims of judicialization as a positive or negative trend, less attention has been paid to ways to better understand the phenomenon in real time. In this article, we propose a new approach-Judicialization 2.0-that recognises judicialization as an integral part of democratic life. This approach seeks to expand access to information about litigation on access to medicines (and health care generally) in order to better characterise the complexity of the phenomenon and thus inform new research and more robust public discussions. Drawing from our multi-disciplinary perspectives and field experiences in highly judicialized contexts, we thus describe a new multi-source, multi-stakeholder mixed-method approach designed to capture the patterns and heterogeneity of judicialization and understand its medical and socio-political impact in real time, along with its counterfactuals. By facilitating greater data availability and open access, we can drive advancements towards transparent and participatory priority setting, as well as accountability mechanisms that promote quality universal health coverage.

Relative age effect: implications for effective practice.

PubMed

Andronikos, Georgios; Elumaro, Adeboye Israel; Westbury, Tony; Martindale, Russell J J

2016-01-01

Physical and psychological differences related to birthdate amongst athletes of the same selection year have been characterised as the "relative age effects" (RAEs). RAEs have been identified in a variety of sports, both at youth and adult level, and are linked with dropout of athletes and a reduction of the talent pool. This study examined the existence, mechanisms and possible solutions to RAEs using qualitative methodology. Seven experts in the field of talent identification and development were interviewed. Inductive analysis of the data showed that, while there was mixed evidence for the existence of RAEs across sports, the eradication of RAEs was attributed to controllable features of the development environment. The factors reported included the structure of "categories" used to group athletes within the sport (e.g. age, weight, size, skills), recognition and prioritisation of long-term development over "short term win focus." Education of relevant parties (e.g. coaches, scouts, clubs) about RAEs and the nature of "talent" within a long-term context was suggested, along with careful consideration of the structure of the development environment (e.g. delayed selection, provision for late developers, focus on skills not results, use of challenge). Implications for research and practice are discussed.

Tissue engineering and regenerative medicine: manufacturing challenges.

PubMed

Williams, D J; Sebastine, I M

2005-12-01

Tissue engineering and regenerative medicine are interdisciplinary fields that apply principles of engineering and life sciences to develop biological substitutes, typically composed of biological and synthetic components, that restore, maintain or improve tissue function. Many tissue engineering technologies are still at a laboratory or pre-commercial scale. The short review paper describes the most significant manufacturing and bio-process challenges inherent in the commercialisation and exploitation of the exciting results emerging from the biological and clinical laboratories exploring tissue engineering and regenerative medicine. A three-generation road map of the industry has been used to structure a view of these challenges and to define where the manufacturing community can contribute to the commercial success of the products from these emerging fields. The first-generation industry is characterised by its demonstrated clinical applications and products in the marketplace, the second is characterised by emerging clinical applications, and the third generation is characterised by aspirational clinical applications. The paper focuses on the cost reduction requirement of the first generation of the industry to allow more market penetration and consequent patient impact. It indicates the technological requirements, for instance the creation of three-dimensional tissue structures, and value chain issues in the second generation of the industry. The third-generation industry challenges lie in fundamental biological and clinical science. The paper sets out a road map of these generations to identify areas for research.

Field investigation with real-time virus genetic characterisation support of a cluster of Ebola virus disease cases in Dubréka, Guinea, April to June 2015.

PubMed

Pini, Alessandro; Zomahoun, Delayo; Duraffour, Sophie; Derrough, Tarik; Charles, Myrna; Quick, Joshua; Loman, Nick; Cowley, Lauren; Leno, Mamadou; Ouedraogo, Nobila; Thiam, Oumou; Hernández-Romieu, Alfonso; Iko, Annie; Keita, Halimatou; Konate, Djiba; Soumah, Aboubacar Aboubak; Bouchouar, Etran; Ileka-Priouzeau, Samuel; Keita, Sakoba; Diallo, Boubacar; Cisse, Fode; Jansa, Josep; Carroll, Miles; Günther, Stephan; Severi, Ettore; Formenty, Pierre

2018-03-01

On 11 May 2015, the Dubréka prefecture, Guinea, reported nine laboratory-confirmed cases of Ebola virus disease (EVD). None could be epidemiologically linked to cases previously reported in the prefecture. We describe the epidemiological and molecular investigations of this event. We used the Dubréka EVD registers and the Ebola treatment centre's (ETC) records to characterise chains of transmission. Real-time field Ebola virus sequencing was employed to support epidemiological results. An epidemiological cluster of 32 cases was found, of which 27 were laboratory confirmed, 24 were isolated and 20 died. Real-time viral sequencing on 12 cases demonstrated SL3 lineage viruses with sequences differing by one to three nt inside a single phylogenetic cluster. For isolated cases, the average time between symptom onset and ETC referral was 2.8 days (interquartile range (IQR): 1-4). The average time between sample collection and molecular results' availability was 3 days (IQR: 2-5). In an area with scarce resources, the genetic characterisation supported the outbreak investigations in real time, linking cases where epidemiological investigation was limited and reassuring that the responsible strain was already circulating in Guinea. We recommend coupling thorough epidemiological and genomic investigations to control EVD clusters.

Inclusive Education and the Arts

ERIC Educational Resources Information Center

Allan, Julie

2014-01-01

This paper addresses the troubled, problematic and contested field of inclusive education, characterised by antagonisms between so-called inclusionists and special educationists; frustration, particularly among disability activists caused by the abstraction of the social model of disability and the expansion of the special educational needs…

The Contribution of Mixed Methods Research to the Field of Childhood Trauma: A Narrative Review Focused on Data Integration

ERIC Educational Resources Information Center

Boeije, Hennie; Slagt, Meike; van Wesel, Floryt

2013-01-01

In mixed methods research (MMR), integrating the quantitative and the qualitative components of a study is assumed to result in additional knowledge (or "yield"). This narrative review examines the extent to which MMR is used in the field of childhood trauma and provides directions for improving mixed methods studies in this field. A…

Applying the Multiple Inverse Method to the analysis of earthquake focal mechanism data: New insights into the active stress field of Italy and surrounding regions

NASA Astrophysics Data System (ADS)

Macchiavelli, Chiara; Mazzoli, Stefano; Megna, Antonella; Saggese, Ferdinando; Santini, Stefano; Vitale, Stefano

2012-12-01

In order to obtain new insights into the active tectonic setting of the Italian territory and surrounding regions, the Multiple Inverse Method (MIM) has been applied to the analysis of fault plane solutions from more than 700 earthquakes with Mw ≥ 4. The active stress field in the top 40 km of the lithosphere has been defined for four 10 km-thick layers, each including 810 square cells of 1.5° side. The obtained stress field maps point out that most of the upper crustal seismicity of the Western and Central Alps is controlled by a strike-slip regime, which is dominant also in part of the Dinarides, Albanides and Hellenides and in a large sector encompassing eastern Sicily and the Malta area to the eastern Tunisia offshore. On the other hand, the well-known extensional belt occurring in the interior of the Apennines appears to extend well beyond the backbone of Italy, potentially reaching the outer foothills of the northern Marche region, while the adjacent Adria block (extending to the eastern Po Plain and the outer Dinarides) sticks out as a major area characterised by dominant thrust faulting in the upper crust. A similar regime characterises also a large sector of the western Tyrrhenian Sea, from NE Tunisia through western Sicily and the west coast of Sardinia, to the Provence coast. Besides lateral variations, our analysis also points out a significant vertical heterogeneity of the stress field, the deeper levels (20 to 40 km) investigated in this study being characterised by dominant horizontal maximum compression even in areas of upper crustal extension. The application of the MIM to a large seismological dataset, providing basic information for the compilation of active stress maps, contributes to a better understanding of active tectonic processes and may be used for improving seismotectonic zoning and reservoir management.

Characterisation of mega-voltage electron pencil beam dose distributions: viability of a measurement-based approach.

PubMed

Barnes, M P; Ebert, M A

2008-03-01

The concept of electron pencil-beam dose distributions is central to pencil-beam algorithms used in electron beam radiotherapy treatment planning. The Hogstrom algorithm, which is a common algorithm for electron treatment planning, models large electron field dose distributions by the superposition of a series of pencil beam dose distributions. This means that the accurate characterisation of an electron pencil beam is essential for the accuracy of the dose algorithm. The aim of this study was to evaluate a measurement based approach for obtaining electron pencil-beam dose distributions. The primary incentive for the study was the accurate calculation of dose distributions for narrow fields as traditional electron algorithms are generally inaccurate for such geometries. Kodak X-Omat radiographic film was used in a solid water phantom to measure the dose distribution of circular 12 MeV beams from a Varian 21EX linear accelerator. Measurements were made for beams of diameter, 1.5, 2, 4, 8, 16 and 32 mm. A blocked-field technique was used to subtract photon contamination in the beam. The "error function" derived from Fermi-Eyges Multiple Coulomb Scattering (MCS) theory for corresponding square fields was used to fit resulting dose distributions so that extrapolation down to a pencil beam distribution could be made. The Monte Carlo codes, BEAM and EGSnrc were used to simulate the experimental arrangement. The 8 mm beam dose distribution was also measured with TLD-100 microcubes. Agreement between film, TLD and Monte Carlo simulation results were found to be consistent with the spatial resolution used. The study has shown that it is possible to extrapolate narrow electron beam dose distributions down to a pencil beam dose distribution using the error function. However, due to experimental uncertainties and measurement difficulties, Monte Carlo is recommended as the method of choice for characterising electron pencil-beam dose distributions.

Functional characterisation of metal(loid) processes in planta through the integration of synchrotron techniques and plant molecular biology

PubMed Central

Donner, Erica; Punshon, Tracy; Guerinot, Mary Lou; Lombi, Enzo

2013-01-01

Functional characterisation of the genes regulating metal(loid) homeostasis in plants is a major focus of crop biofortification, phytoremediation, and food security research. This paper focuses on the potential for advancing plant metal(loid) research by combining molecular biology and synchrotron-based techniques. Recent advances in x-ray focussing optics and fluorescence detection have greatly improved the potential of synchrotron techniques for plant science research, allowing metal(loids) to be imaged in vivo in hydrated plant tissues at sub-micron resolution. Laterally resolved metal(loid) speciation can also be determined. By using molecular techniques to probe the location of gene expression and protein localisation and combining it with this synchrotron-derived data, functional information can be effectively and efficiently assigned to specific genes. This paper provides a review of the state of the art in this field, and provides examples as to how synchrotron-based methods can be combined with molecular techniques to facilitate functional characterisation of genes in planta. PMID:22200921

Global optimisation methods for poroelastic material characterisation using a clamped sample in a Kundt tube setup

NASA Astrophysics Data System (ADS)

Vanhuyse, Johan; Deckers, Elke; Jonckheere, Stijn; Pluymers, Bert; Desmet, Wim

2016-02-01

The Biot theory is commonly used for the simulation of the vibro-acoustic behaviour of poroelastic materials. However, it relies on a number of material parameters. These can be hard to characterize and require dedicated measurement setups, yielding a time-consuming and costly characterisation. This paper presents a characterisation method which is able to identify all material parameters using only an impedance tube. The method relies on the assumption that the sample is clamped within the tube, that the shear wave is excited and that the acoustic field is no longer one-dimensional. This paper numerically shows the potential of the developed method. It therefore performs a sensitivity analysis of the quantification parameters, i.e. reflection coefficients and relative pressures, and a parameter estimation using global optimisation methods. A 3-step procedure is developed and validated. It is shown that even in the presence of numerically simulated noise this procedure leads to a robust parameter estimation.

Slip-based terrain estimation with a skid-steer vehicle

NASA Astrophysics Data System (ADS)

Reina, Giulio; Galati, Rocco

2016-10-01

In this paper, a novel approach for online terrain characterisation is presented using a skid-steer vehicle. In the context of this research, terrain characterisation refers to the estimation of physical parameters that affects the terrain ability to support vehicular motion. These parameters are inferred from the modelling of the kinematic and dynamic behaviour of a skid-steer vehicle that reveals the underlying relationships governing the vehicle-terrain interaction. The concept of slip track is introduced as a measure of the slippage experienced by the vehicle during turning motion. The proposed terrain estimation system includes common onboard sensors, that is, wheel encoders, electrical current sensors and yaw rate gyroscope. Using these components, the system can characterise terrain online during normal vehicle operations. Experimental results obtained from different surfaces are presented to validate the system in the field showing its effectiveness and potential benefits to implement adaptive driving assistance systems or to automatically update the parameters of onboard control and planning algorithms.

Neuroethological validation of an experimental apparatus to evaluate oriented and non-oriented escape behaviours: Comparison between the polygonal arena with a burrow and the circular enclosure of an open-field test.

PubMed

Biagioni, Audrey Francisco; dos Anjos-Garcia, Tayllon; Ullah, Farhad; Fisher, Isaac René; Falconi-Sobrinho, Luiz Luciano; de Freitas, Renato Leonardo; Felippotti, Tatiana Tocchini; Coimbra, Norberto Cysne

2016-02-01

Inhibition of GABAergic neural inputs to dorsal columns of the periaqueductal grey matter (dPAG), posterior (PH) and dorsomedial (DMH) hypothalamic nuclei elicits distinct types of escape behavioural reactions. To differentiate between the variety and intensity of panic-related behaviours, the pattern of defensive behaviours evoked by blockade of GABAA receptors in the DMH, PH and dPAG were compared in a circular open-field test and in a recently designed polygonal arena. In the circular open-field, the defensive behaviours induced by microinjection of bicuculline into DMH and PH were characterised by defensive alertness behaviour and vertical jumps preceded by rearing exploratory behaviour. On the other hand, explosive escape responses interspersed with horizontal jumps and freezing were observed after the blockade of GABAA receptors on dPAG neurons. In the polygonal arena apparatus, the escape response produced by GABAergic inhibition of DMH and PH neurons was directed towards the burrow. In contrast, the blockade of GABAA receptors in dPAG evoked non-oriented escape behaviour characterised by vigorous running and horizontal jumps in the arena. Our findings support the hypothesis that the hypothalamic nuclei organise oriented escape behavioural responses whereas non-oriented escape is elaborated by dPAG neurons. Additionally, the polygonal arena with a burrow made it easy to discriminate and characterise these two different patterns of escape behavioural responses. In this sense, the polygonal arena with a burrow can be considered a good methodological tool to discriminate between these two different patterns of escape behavioural responses and is very useful as a new experimental animal model of panic attacks. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of vertical mixing in oscillatory vegetated flows

NASA Astrophysics Data System (ADS)

Abdolahpour, M.; Ghisalberti, M.; Lavery, P.; McMahon, K.

2016-02-01

Seagrass meadows are primary producers that provide important ecosystem services, such as improved water quality, sediment stabilisation and trapping and recycling of nutrients. Most of these ecological services are strongly influenced by the vertical exchange of water across the canopy-water interface. That is, vertical mixing is the main hydrodynamic process governing the large-scale ecological and environmental impact of seagrass meadows. The majority of studies into mixing in vegetated flows have focused on steady flow environments whereas many coastal canopies are subjected to oscillatory flows driven by surface waves. It is known that the rate of mass transfer will vary greatly between unidirectional and oscillatory flows, necessitating a specific investigation of mixing in oscillatory canopy flows. In this study, we conducted an extensive laboratory investigation to characterise the rate of vertical mixing through a vertical turbulent diffusivity (Dt,z). This has been done through gauging the evolution of vertical profiles of concentration (C) of a dye sheet injected into a wave-canopy flow. Instantaneous measurement of the variance of the vertical concentration distribution ( allowed the estimation of a vertical turbulent diffusivity (). Two types of model canopies, rigid and flexible, with identical heights and frontal areas, were subjected to a wide and realistic range of wave height and period. The results showed two important mechanisms that dominate vertical mixing under different conditions: a shear layer that forms at the top of the canopy and wake turbulence generated by the stems. By allowing a coupled contribution of wake and shear layer mixing, we present a relationship that can be used to predict the rate of vertical mixing in coastal canopies. The results further showed that the rate of vertical mixing within flexible vegetation was always lower than the corresponding rigid canopy, confirming the impact of plant flexibility on canopy-flow interactions.

Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

PubMed Central

Hiromitsu, Shirasawa; Jin, Kumagai; Emiko, Sato; Katsuya, Kabashima; Yukiyo, Kumazawa; Wataru, Sato; Hiroshi, Miura; Ryuta, Nakamura; Hiroshi, Nanjo; Yoshihiro, Minamiya; Yoichi, Akagami; Yukihiro, Terada

2015-01-01

Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time. PMID:26477850

Effects of different excitation waveforms on detection and characterisation of delamination in PV modules by active infrared thermography

NASA Astrophysics Data System (ADS)

Sinha, Archana; Gupta, Rajesh

2017-10-01

Delamination significantly affects the performance and reliability of photovoltaic (PV) modules. Recently, an active infrared thermography approach using step heating has been exploited for the detection and characterisation of delamination in PV modules. However, step heating takes longer observation time and causes overheating problems. This paper presents the effects of different thermal excitation waveforms namely rectangular, half-sine and short pulse, on the detection and characterisation of delamination in PV module by experiments and simulations. For simulation, a 3-dimensional electro-thermal model of heat conduction, based on resistance-capacitance network approach, has been exploited to study the variation in maximum thermal contrast and peak contrast time with the delamination thickness and heating parameters. Results show that the rectangular waveform provides better detection of delamination due to higher absolute contrast, while the half-sine waveform allows better characterisation of delamination in the PV modules with low-cost and low-power heat source. The high-energy short pulse enabled quick visualisation of delamination, but has limited practical implementation. The advantages and limitations of each waveform have been highlighted to assess the specific requirement for appropriate choice in the non-destructive thermographic inspection of delamination in PV modules at the manufacturing units or outdoor fields.

Ground Penetrating Radar as a Contextual Sensor for Multi-Sensor Radiological Characterisation

PubMed Central

Ukaegbu, Ikechukwu K.; Gamage, Kelum A. A.

2017-01-01

Radioactive sources exist in environments or contexts that influence how they are detected and localised. For instance, the context of a moving source is different from a stationary source because of the effects of motion. The need to incorporate this contextual information in the radiation detection and localisation process has necessitated the integration of radiological and contextual sensors. The benefits of the successful integration of both types of sensors is well known and widely reported in fields such as medical imaging. However, the integration of both types of sensors has also led to innovative solutions to challenges in characterising radioactive sources in non-medical applications. This paper presents a review of such recent applications. It also identifies that these applications mostly use visual sensors as contextual sensors for characterising radiation sources. However, visual sensors cannot retrieve contextual information about radioactive wastes located in opaque environments encountered at nuclear sites, e.g., underground contamination. Consequently, this paper also examines ground-penetrating radar (GPR) as a contextual sensor for characterising this category of wastes and proposes several ways of integrating data from GPR and radiological sensors. Finally, it demonstrates combined GPR and radiation imaging for three-dimensional localisation of contamination in underground pipes using radiation transport and GPR simulations. PMID:28387706

Mechanical, thermal and morphological characterisation of 3D porous Pennisetum purpureum/PLA biocomposites scaffold.

PubMed

Revati, R; Abdul Majid, M S; Ridzuan, M J M; Normahira, M; Mohd Nasir, N F; Rahman Y, M N; Gibson, A G

2017-06-01

The mechanical, thermal, and morphological properties of a 3D porous Pennisetum purpureum (PP)/polylactic acid (PLA) based scaffold were investigated. In this study, a scaffold containing P. purpureum and PLA was produced using the solvent casting and particulate leaching method. P. purpureum fibre, also locally known as Napier grass, is composed of 46% cellulose, 34% hemicellulose, and 20% lignin. PLA composites with various P. purpureum contents (10%, 20%, and 30%) were prepared and subsequently characterised. The morphologies, structures and thermal behaviours of the prepared composite scaffolds were characterised using field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology was studied using FESEM; the scaffold possessed 70-200μm-sized pores with a high level of interconnectivity. The moisture content and mechanical properties of the developed porous scaffolds were further characterised. The P. purpureum/PLA scaffold had a greater porosity factor (99%) and compression modulus (5.25MPa) than those of the pure PLA scaffold (1.73MPa). From the results, it can be concluded that the properties of the highly porous P. purpureum/PLA scaffold developed in this study can be controlled and optimised. This can be used to facilitate the construction of implantable tissue-engineered cartilage. Copyright © 2017 Elsevier B.V. All rights reserved.

The value of automated gel column agglutination technology in the identification of true inherited D blood types in massively transfused patients.

PubMed

Summers, Thomas; Johnson, Viviana V; Stephan, John P; Johnson, Gloria J; Leonard, George

2009-08-01

Massive transfusion of D- trauma patients in the combat setting involves the use of D+ red blood cells (RBCs) or whole blood along with suboptimal pretransfusion test result documentation. This presents challenges to the transfusion service of tertiary care military hospitals who ultimately receive these casualties because initial D typing results may only reflect the transfused RBCs. After patients are stabilized, mixed-field reaction results on D typing indicate the patient's true inherited D phenotype. This case series illustrates the utility of automated gel column agglutination in detecting mixed-field reactions in these patients. The transfusion service test results, including the automated gel column agglutination D typing results, of four massively transfused D- patients transfused D+ RBCs is presented. To test the sensitivity of the automated gel column agglutination method in detecting mixed-field agglutination reactions, a comparative analysis of three automated technologies using predetermined mixtures of D+ and D- RBCs is also presented. The automated gel column agglutination method detected mixed-field agglutination in D typing in all four patients and in the three prepared control specimens. The automated microwell tube method identified one of the three prepared control specimens as indeterminate, which was subsequently manually confirmed as a mixed-field reaction. The automated solid-phase method was unable to detect any mixed fields. The automated gel column agglutination method provides a sensitive means for detecting mixed-field agglutination reactions in the determination of the true inherited D phenotype of combat casualties transfused massive amounts of D+ RBCs.

The effect of fringe fields from patterned magnetic domains on the electroluminescence of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Harmon, Nicholas J.; Wohlgennant, Markus; Flatté, Michael E.

2016-10-01

Large magnetic field effects, either in conduction or luminescence, have been observed in organic light-emitting diodes (OLEDs) for over a decade now. The physical processes are largely understood when exciton formation and recombination lead to the magnetic field effects. Recently, magnetic field effects in some co-evaporated blends have shown that exciplexes deliver even larger responses. In either case, the magnetic field effects arise from some spin-mixing mechanism and spin-selective processes in either the exciton formation or the exciplex recombination. Precise control of light output is not possible when the spin mixing is either due to hyper-fine fields or differences in the Lande g-factor. We theoretically examine the optical output when a patterned magnetic film is deposited near the OLED. The fringe fields from the magnetic layers supply an additionally source of spin mixing that can be easily controlled. In the absence of other spin mixing mechanisms, the luminescence from exciplexes can be modified by 300%. When other spin-mixing mechanisms are present, fringe fields from remanent magnetic states act as a means to either boost or reduce light emission from those mechanisms. Lastly, we examine the influence of spin decoherence on the optical output.

Detection of quantum well induced single degenerate-transition-dipoles in ZnO nanorods.

PubMed

Ghosh, Siddharth; Ghosh, Moumita; Seibt, Michael; Rao, G Mohan

2016-02-07

Quantifying and characterising atomic defects in nanocrystals is difficult and low-throughput using the existing methods such as high resolution transmission electron microscopy (HRTEM). In this article, using a defocused wide-field optical imaging technique, we demonstrate that a single ultrahigh-piezoelectric ZnO nanorod contains a single defect site. We model the observed dipole-emission patterns from optical imaging with a multi-dimensional dipole and find that the experimentally observed dipole pattern and model-calculated patterns are in excellent agreement. This agreement suggests the presence of vertically oriented degenerate-transition-dipoles in vertically aligned ZnO nanorods. The HRTEM of the ZnO nanorod shows the presence of a stacking fault, which generates a localised quantum well induced degenerate-transition-dipole. Finally, we elucidate that defocused wide-field imaging can be widely used to characterise defects in nanomaterials to answer many difficult questions concerning the performance of low-dimensional devices, such as in energy harvesting, advanced metal-oxide-semiconductor storage, and nanoelectromechanical and nanophotonic devices.

In situ electrostatic characterisation of ion beams in the region of ion acceleration

NASA Astrophysics Data System (ADS)

Bennet, Alexander; Charles, Christine; Boswell, Rod

2018-02-01

In situ and ex situ techniques have been used to measure directional ion beams created by a sharp axial potential drop in low pressure expanding plasmas. Although Retarding Field Energy Analysers (RFEAs) are the most convenient technique to measure the ion velocities and plasma potentials along with the plasma density, they are bulky and are contained in a grounded shield that may perturb the electric potential profile of the expanding plasma. In principle, ex situ techniques produce a more reliable measurement and Laser Induced Fluorescence spectroscopy (LIF) has previously been used to characterise the spatial velocity profile of ion beams in the same region of acceleration for a range of pressures. Here, satisfactory agreement between the ion velocity profiles measured by LIF and RFEA techniques has allowed the RFEA method to be confidently used to probe the ion beam characteristics in the regions of high gradients in plasma density and DC electric fields which have previously proven difficult.

Energy and direction distribution of neutrons in workplace fields: implication of the results from the EVIDOS project for the set-up of simulated workplace fields.

PubMed

Luszik-Bhadra, M; Lacoste, V; Reginatto, M; Zimbal, A

2007-01-01

Workplace neutron spectra from nuclear facilities obtained within the European project EVIDOS are compared with those of the simulated workplace fields CANEL and SIGMA and fields set-up with radionuclide sources at the PTB. Contributions of neutrons to ambient dose equivalent and personal dose equivalent are given in three energy intervals (for thermal, intermediate and fast neutrons) together with the corresponding direction distribution, characterised by three different types of distributions (isotropic, weakly directed and directed). The comparison shows that none of the simulated workplace fields investigated here can model all the characteristics of the fields observed at power reactors.

Positioning and aligning CNTs by external magnetic field to assist localised epoxy cure

NASA Astrophysics Data System (ADS)

Ariu, G.; Hamerton, I.; Ivanov, D.

2016-01-01

This work focuses on the generation of conductive networks through the localised alignment of nano fillers, such as multi-walled carbon nanotubes (MWCNTs). The feasibility of alignment and positioning of functionalised MWCNTs by external DC magnetic fields was investigated. The aim of this manipulation is to enhance resin curing through AC induction heating due to hysteresis losses from the nanotubes. Experimental analyses focused on in-depth assessment of the nanotube functionalisation, processing and characterisation of magnetic, rheological and cure kinetics properties of the MWCNT solution. The study has shown that an external magnetic field has great potential for positioning and alignment of CNTs. The study demonstrated potential for creating well-ordered architectures with an unprecedented level of control of network geometry. Magnetic characterisation indicated cobalt-plated nanotubes to be the most suitable candidate for magnetic alignment due to their high magnetic sensitivity. Epoxy/metal-plated CNT nanocomposite systems were validated by thermal analysis as induction heating mediums. The curing process could therefore be optimised by the use of dielectric resins. This study offers a first step towards the proof of concept of this technique as a novel repair technology.

Characterisation of edge turbulence in relation to edge magnetic field configuration in L-mode plasmas in the Mega Amp Spherical Tokamak.

NASA Astrophysics Data System (ADS)

Dewhurst, J.; Hnat, B.; Dudson, B.; Dendy, R. O.; Counsell, G. F.; Kirk, A.

2007-12-01

Almost all astrophysical and magnetically confined fusion plasmas are turbulent. Here, we examine ion saturation current (Isat) measurements of edge plasma turbulence for three MAST L-mode plasmas that differ primarily in their edge magnetic field configurations. First, absolute moments of the coarse grained data are examined to obtain accurate values of scaling exponents. The dual scaling behaviour is identified in all samples, with the temporal scale τ ≍ 40-60 μs separating the two regimes. Strong universality is then identified in the functional form of the probability density function (PDF) for Isat fluctuations, which is well approximated by the Fréchet distribution on temporal scales τ ≤ 40μs. For temporal scales τ > 40μs, the PDFs appear to converge to the Gumbel distribution, which has been previously identified as a universal feature of many other complex phenomena. The optimal fitting parameters k=1.15 for Fréchet and a=1.35 for Gumbel provide a simple quantitative characterisation of the full spectrum of fluctuations. We conclude that, to good approximation, the properties of the edge turbulence are independent of the edge magnetic field configuration.

Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

NASA Astrophysics Data System (ADS)

Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

2017-06-01

Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high-pressure Raman cell, providing access only to a few N2 rotational levels. Because of this, the four-wave mixing signal in the flame is lower by more than an order of magnitude compared to the signal generated in room temperature air plasma. Preliminary experiments demonstrated four-wave mixing signal generated by the electric field in the flame, following ns pulse discharge breakdown. The electric field in the flame is estimated using four-wave mixing signal calibration vs. temperature in electrostatic electric field generated in heated air. Further measurements in the flame are underway.

A three-dimensional simulation of transition and early turbulence in a time-developing mixing layer

NASA Technical Reports Server (NTRS)

Cain, A. B.; Reynolds, W. C.; Ferziger, J. H.

1981-01-01

The physics of the transition and early turbulence regimes in the time developing mixing layer was investigated. The sensitivity of the mixing layer to the disturbance field of the initial condition is considered. The growth of the momentum thickness, the mean velocity profile, the turbulence kinetic energy, the Reynolds stresses, the anisotropy tensor, and particle track pictures of computations are all examined in an effort to better understand the physics of these regimes. The amplitude, spectrum shape, and random phases of the initial disturbance field were varied. A scheme of generating discrete orthogonal function expansions on some nonuniform grids was developed. All cases address the early or near field of the mixing layer. The most significant result shows that the secondary instability of the mixing layer is produced by spanwise variations in the straining field of the primary vortex structures.

Biosynthesis of silver and platinum nanoparticles using orange peel extract: characterisation and applications.

PubMed

Castro, Laura; Blázquez, María Luisa; González, Felisa; Muñoz, Jesús Ángel; Ballester, Antonio

2015-10-01

This study focuses on the green synthesis of noble metal nanoparticles (silver (Ag) and platinum (Pt)) and how the size and shape of the nanoparticles produced can be controlled through changes in the initial pH value of the precursor solution. The nanoparticles were characterised by ultra-violet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. This simple and environmentally friendly method allows the synthesis of diverse nanostructures in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally adding seed crystallites. The antibacterial effects of Ag nanoparticles and catalytic properties of Pt nanoparticles were explored for future promising biotechnological approaches in different fields.

Experimental study of mixing mechanisms in stably stratified Taylor-Couette flow

NASA Astrophysics Data System (ADS)

Augier, Pierre; Caulfield, Colm-Cille; Dalziel, Stuart

2014-11-01

We consider experimentally the mechanisms of mixing in stably stratified Taylor-Couette (TC) flow in a TC apparatus for which both cylinders can rotate independently. In the case for which only the inner cylinder rotates, centrifugal instability rapidly splits an initially linear density profile into an array of thin nearly homogeneous layers. Shadowgraph, PIV and density profiles measured by a moving conductivity probe allow us to characterise this process and the resulting flow. In particular, we observe turbulent intrusions of mixed fluid propagating relatively slowly around the tank at the interfaces between the layers, leading to a time-dependent variation in the sharpness and turbulent activity at these interfaces, whose period scales with (but is much larger than) the rotation period. Interestingly, the turbulent intrusions are anti-correlated between adjacent interfaces leading to snake-skin-like patterns in the spatio-temporal diagrams of the density profiles. We also explore how the presence of a density stratification modifies end effects at the top and bottom of the cylinders, in both the presence and absence of primary centrifugal instability.

Rapid Microfluidic Mixers Utilizing Dispersion Effect and Interactively Time-Pulsed Injection

NASA Astrophysics Data System (ADS)

Leong, Jik-Chang; Tsai, Chien-Hsiung; Chang, Chin-Lung; Lin, Chiu-Feng; Fu, Lung-Ming

2007-08-01

In this paper, we present a novel active microfluidic mixer utilizing a dispersion effect in an expansion chamber and applying interactively time-pulsed driving voltages to the respective inlet fluid flows to induce electroosmotic flow velocity variations for developing a rapid mixing effect in a microchannel. Without using any additional equipment to induce flow perturbations, only a single high-voltage power source is required for simultaneously driving and mixing sample fluids, which results in a simple and low-cost system for mixing. The effects of the applied main electrical field, interactive frequency, and expansion ratio on the mixing performance are thoroughly examined experimentally and numerically. The mixing ratio can be as high as 95% within a mixing length of 3000 μm downstream from the secondary T-form when a driving electric field strength of 250 V/cm, a periodic switching frequency of 5 Hz, and the expansion ratio M=1:10 are applied. In addition, the optimization of the driving electric field, switching frequency, expansion ratio, expansion entry length, and expansion chamber length for achieving a maximum mixing ratio is also discussed in this study. The novel method proposed in this study can be used for solving the mixing problem in the field of micro-total-analysis systems in a simple manner.

Public Administration Teaching and Interdisciplinarity: Considering the Consequences

ERIC Educational Resources Information Center

van der Waldt, Gerrit

2014-01-01

Public administration is a highly diverse and evolving field of scientific inquiry. The study domain is characterised further by often-competing paradigmatic perspectives and seemingly endless teaching modalities. There seems to be an increasing realisation that answers to complex societal challenges cannot be solved within the knowledge…

Low-field thermal mixing in [1-(13)C] pyruvic acid for brute-force hyperpolarization.

PubMed

Peat, David T; Hirsch, Matthew L; Gadian, David G; Horsewill, Anthony J; Owers-Bradley, John R; Kempf, James G

2016-07-28

We detail the process of low-field thermal mixing (LFTM) between (1)H and (13)C nuclei in neat [1-(13)C] pyruvic acid at cryogenic temperatures (4-15 K). Using fast-field-cycling NMR, (1)H nuclei in the molecule were polarized at modest high field (2 T) and then equilibrated with (13)C nuclei by fast cycling (∼300-400 ms) to a low field (0-300 G) that activates thermal mixing. The (13)C NMR spectrum was recorded after fast cycling back to 2 T. The (13)C signal derives from (1)H polarization via LFTM, in which the polarized ('cold') proton bath contacts the unpolarised ('hot') (13)C bath at a field so low that Zeeman and dipolar interactions are similar-sized and fluctuations in the latter drive (1)H-(13)C equilibration. By varying mixing time (tmix) and field (Bmix), we determined field-dependent rates of polarization transfer (1/τ) and decay (1/T1m) during mixing. This defines conditions for effective mixing, as utilized in 'brute-force' hyperpolarization of low-γ nuclei like (13)C using Boltzmann polarization from nearby protons. For neat pyruvic acid, near-optimum mixing occurs for tmix∼ 100-300 ms and Bmix∼ 30-60 G. Three forms of frozen neat pyruvic acid were tested: two glassy samples, (one well-deoxygenated, the other O2-exposed) and one sample pre-treated by annealing (also well-deoxygenated). Both annealing and the presence of O2 are known to dramatically alter high-field longitudinal relaxation (T1) of (1)H and (13)C (up to 10(2)-10(3)-fold effects). Here, we found smaller, but still critical factors of ∼(2-5)× on both τ and T1m. Annealed, well-deoxygenated samples exhibit the longest time constants, e.g., τ∼ 30-70 ms and T1m∼ 1-20 s, each growing vs. Bmix. Mixing 'turns off' for Bmix > ∼100 G. That T1m≫τ is consistent with earlier success with polarization transfer from (1)H to (13)C by LFTM.

Acoustic source localization in mixed field using spherical microphone arrays

NASA Astrophysics Data System (ADS)

Huang, Qinghua; Wang, Tong

2014-12-01

Spherical microphone arrays have been used for source localization in three-dimensional space recently. In this paper, a two-stage algorithm is developed to localize mixed far-field and near-field acoustic sources in free-field environment. In the first stage, an array signal model is constructed in the spherical harmonics domain. The recurrent relation of spherical harmonics is independent of far-field and near-field mode strengths. Therefore, it is used to develop spherical estimating signal parameter via rotational invariance technique (ESPRIT)-like approach to estimate directions of arrival (DOAs) for both far-field and near-field sources. In the second stage, based on the estimated DOAs, simple one-dimensional MUSIC spectrum is exploited to distinguish far-field and near-field sources and estimate the ranges of near-field sources. The proposed algorithm can avoid multidimensional search and parameter pairing. Simulation results demonstrate the good performance for localizing far-field sources, or near-field ones, or mixed field sources.

The Specificity of Observational Studies in Physical Activity and Sports Sciences: Moving Forward in Mixed Methods Research and Proposals for Achieving Quantitative and Qualitative Symmetry.

PubMed

Anguera, M Teresa; Camerino, Oleguer; Castañer, Marta; Sánchez-Algarra, Pedro; Onwuegbuzie, Anthony J

2017-01-01

Mixed methods studies are been increasingly applied to a diversity of fields. In this paper, we discuss the growing use-and enormous potential-of mixed methods research in the field of sport and physical activity. A second aim is to contribute to strengthening the characteristics of mixed methods research by showing how systematic observation offers rigor within a flexible framework that can be applied to a wide range of situations. Observational methodology is characterized by high scientific rigor and flexibility throughout its different stages and allows the objective study of spontaneous behavior in natural settings, with no external influence. Mixed methods researchers need to take bold yet thoughtful decisions regarding both substantive and procedural issues. We present three fundamental and complementary ideas to guide researchers in this respect: we show why studies of sport and physical activity that use a mixed methods research approach should be included in the field of mixed methods research, we highlight the numerous possibilities offered by observational methodology in this field through the transformation of descriptive data into quantifiable code matrices, and we discuss possible solutions for achieving true integration of qualitative and quantitative findings.

Alcohol-flavoured tobacco products.

PubMed

Jackler, Robert K; VanWinkle, Callie K; Bumanlag, Isabela M; Ramamurthi, Divya

2018-05-01

In 2009, the Food and Drug Administration (FDA) banned characterising flavours in cigarettes (except for menthol) due to their appeal to teen starter smokers. In August 2016, the agency deemed all tobacco products to be under its authority and a more comprehensive flavour ban is under consideration. To determine the scope and scale of alcohol-flavoured tobacco products among cigars & cigarillos, hookahs and electronic cigarettes (e-cigarettes). Alcohol-flavoured tobacco products were identified by online search of tobacco purveyors' product lines and via Google search cross-referencing the various tobacco product types versus a list of alcoholic beverage flavours (eg, wine, beer, appletini, margarita). 48 types of alcohol-flavoured tobacco products marketed by 409 tobacco brands were identified. Alcohol flavours included mixed drinks (n=25), spirits (11), liqueurs (7) and wine/beer (5). Sweet and fruity tropical mixed drink flavours were marketed by the most brands: piña colada (96), mojito (66) and margarita (50). Wine flavours were common with 104 brands. Among the tobacco product categories, brands offering alcohol-flavoured e-cigarettes (280) were most numerous, but alcohol-flavoured products were also marketed by cigars & cigarillos (88) and hookah brands (41). Brands by major tobacco companies (eg, Philip Morris, Imperial Tobacco) were well represented among alcohol-flavoured cigars & cigarillos with five companies offering a total of 17 brands. The widespread availability of alcohol-flavoured tobacco products illustrates the need to regulate characterising flavours on all tobacco products. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Aerosol characterisation at the FEBUKO upwind station Goldlauter (II): Detailed organic chemical characterisation

NASA Astrophysics Data System (ADS)

Müller, K.; van Pinxteren, D.; Plewka, A.; Svrcina, B.; Kramberger, H.; Hofmann, D.; Bächmann, K.; Herrmann, H.

An extensive set of gaseous and particulate organic compounds was quantified before an orographic cloud passage at the upwind site of the research region in Thüringer Wald. Samples were collected with two different time resolutions, 2 h for gaseous species and spray absorber samples and the whole cloud event duration to determine the concentrations of ketones, aldehydes, monocarboxylic acids, dicarboxylic acids (DCA), hydrocarbons, biogenic sugars and alcohols in both the gas and particle phase. The measurement of different groups of organic compounds delivered size-segregated concentrations at the upwind site of a cloud experiment. The size distribution of DCA showed a peak in the mass-rich impactor stage 3 (0.42-1.2 μm). The concentrations of DCA from the filters, the impactor foils as well as the spray absorber samples decreased with increasing C-number. The time resolved measurements revealed an increasing mixing ratio from night time to midday for carboxylic and DCA, and related carbonyl compounds. The biogenic compounds xylitol (up to 103 ng m -3), levoglucosan (up to 62 ng m -3) and pinonaldehyde (up to 34 ng m -3) were the compounds found in highest concentrations in the particle phase beside the oxalate (up to 104 ng m -3). The organic trace gases with the highest mixing ratios identified were formaldehyde (up to 1.47 ppbv), acetaldehyde (up to 0.84 ppbv) and acetone (up to 0.65 ppbv), acetic acid (up to 0.43 ppbv) and formic acid (up to 0.41 ppbv).

Characterisation of iron-rich atmospheric submicrometre particles in the roadside environment

NASA Astrophysics Data System (ADS)

Sanderson, P.; Su, S. S.; Chang, I. T. H.; Delgado Saborit, J. M.; Kepaptsoglou, D. M.; Weber, R. J. M.; Harrison, Roy M.

2016-09-01

Human exposure to ambient metallic nanoparticles is an area of great interest owing to their potential health impacts. Ambient metallic nanoparticles found in the roadside environment are contributed by combustion engines and wear of brakes, tyres and road surfaces. Submicrometre atmospheric particles collected at two UK urban sites have been subject to detailed characterisation. It is found that many metallic nanoparticles collected from roadside sampling sites are rich in iron. The Fe-rich nanoparticles can be classified into (1) high Fe content (ca 90 wt%) with each alloying element less than 1 wt%; and (2) moderate Fe content (<75 wt%) with high manganese and silicon content. Both clusters contain a variable mix of minor constituents, Mn, S and Si being most important in the high-Fe group. The moderate Fe group also contains Zn, Cu, Ba, Al and Ca. The Fe-rich nanoparticles exhibit primary particle sizes ranging between 20 and 30 nm, although some much larger particles up to around 100 nm can also be observed, along with some very small particles of 10 nm or less. These tend to agglomerate forming clusters ranging from ∼200 nm to 1 μm in diameter. The iron-rich particles observed are oxides, taking the form of spheres or multifaceted regular polyhedra. Analysis by EELS shows that both high- and moderate-Fe groups include particles of FeO, Fe3O4, α-Fe2O3 and γ-Fe2O3 of which γ-Fe2O3 is the most prominent. Internal mixing of different Fe-oxides is not observed.

Generic evolution of mixing in heterogeneous media

NASA Astrophysics Data System (ADS)

De Dreuzy, J.; Carrera, J.; Dentz, M.; Le Borgne, T.

2011-12-01

Mixing in heterogeneous media results from the competition bewteen flow fluctuations and local scale diffusion. Flow fluctuations quickly create concentration contrasts and thus heterogeneity of the concentration field, which is slowly homogenized by local scale diffusion. Mixing first deviates from Gaussian mixing, which represents the potential mixing induced by spreading before approaching it. This deviation fundamentally expresses the evolution of the interaction between spreading and local scale diffusion. We characterize it by the ratio γ of the non-Gaussian to the Gaussian mixing states. We define the Gaussian mixing state as the integrated squared concentration of the Gaussian plume that has the same longitudinal dispersion as the real plume. The non-Gaussian mixing state is the difference between the overall mixing state defined as the integrated squared concentration and the Gaussian mixing state. The main advantage of this definition is to use the full knowledge previously acquired on dispersion for characterizing mixing even when the solute concentration field is highly non Gaussian. Using high precision numerical simulations, we show that γ quickly increases, peaks and slowly decreases. γ can be derived from two scales characterizing spreading and local mixing, at least for large flux-weighted solute injection conditions into classically log-normal Gaussian correlated permeability fields. The spreading scale is directly related to the longitudinal dispersion. The local mixing scale is the largest scale over which solute concentrations can be considered locally uniform. More generally, beyond the characteristics of its maximum, γ turns out to have a highly generic scaling form. Its fast increase and slow decrease depend neither on the heterogeneity level, nor on the ratio of diffusion to advection, nor on the injection conditions. They might even not depend on the particularities of the flow fields as the same generic features also prevail for Taylor dispersion. This generic characterization of mixing can offer new ways to set up transport equations that honor not only advection and spreading (dispersion), but also mixing.

Numerical study of enhanced mixing in pressure-driven flows in microchannels using a spatially periodic electric field

NASA Astrophysics Data System (ADS)

Krishnaveni, T.; Renganathan, T.; Picardo, J. R.; Pushpavanam, S.

2017-09-01

We propose an innovative mechanism for enhancing mixing in steady pressure driven flow of an electrolytic solution in a straight rectangular microchannel. A transverse electric field is used to generate an electroosmotic flow across the cross-section. The resulting flow field consists of a pair of helical vortices that transport fluid elements along the channel. We show, through numerical simulations, that chaotic advection may be induced by periodically varying the direction of the applied electric field along the channel length. This periodic electric field generates a longitudinally varying, three-dimensional steady flow, such that the streamlines in the first half of the repeating unit cell intersect those in the second half, when projected onto the cross-section. Mixing is qualitatively characterized by tracking passive particles and obtaining Poincaré maps. For quantification of the extent of mixing, Shannon entropy is calculated using particle advection of a binary mixture. The convection diffusion equation is also used to track the evolution of a scalar species and quantify the mixing efficiency as a function of the Péclet number.

Numerical study of enhanced mixing in pressure-driven flows in microchannels using a spatially periodic electric field.

PubMed

Krishnaveni, T; Renganathan, T; Picardo, J R; Pushpavanam, S

2017-09-01

We propose an innovative mechanism for enhancing mixing in steady pressure driven flow of an electrolytic solution in a straight rectangular microchannel. A transverse electric field is used to generate an electroosmotic flow across the cross-section. The resulting flow field consists of a pair of helical vortices that transport fluid elements along the channel. We show, through numerical simulations, that chaotic advection may be induced by periodically varying the direction of the applied electric field along the channel length. This periodic electric field generates a longitudinally varying, three-dimensional steady flow, such that the streamlines in the first half of the repeating unit cell intersect those in the second half, when projected onto the cross-section. Mixing is qualitatively characterized by tracking passive particles and obtaining Poincaré maps. For quantification of the extent of mixing, Shannon entropy is calculated using particle advection of a binary mixture. The convection diffusion equation is also used to track the evolution of a scalar species and quantify the mixing efficiency as a function of the Péclet number.

Characterisation of exposure to non-ionising electromagnetic fields in the Spanish INMA birth cohort: study protocol.

PubMed

Gallastegi, Mara; Guxens, Mònica; Jiménez-Zabala, Ana; Calvente, Irene; Fernández, Marta; Birks, Laura; Struchen, Benjamin; Vrijheid, Martine; Estarlich, Marisa; Fernández, Mariana F; Torrent, Maties; Ballester, Ferrán; Aurrekoetxea, Juan J; Ibarluzea, Jesús; Guerra, David; González, Julián; Röösli, Martin; Santa-Marina, Loreto

2016-02-18

Analysis of the association between exposure to electromagnetic fields of non-ionising radiation (EMF-NIR) and health in children and adolescents is hindered by the limited availability of data, mainly due to the difficulties on the exposure assessment. This study protocol describes the methodologies used for characterising exposure of children to EMF-NIR in the INMA (INfancia y Medio Ambiente- Environment and Childhood) Project, a prospective cohort study. Indirect (proximity to emission sources, questionnaires on sources use and geospatial propagation models) and direct methods (spot and fixed longer-term measurements and personal measurements) were conducted in order to assess exposure levels of study participants aged between 7 and 18 years old. The methodology used varies depending on the frequency of the EMF-NIR and the environment (homes, schools and parks). Questionnaires assessed the use of sources contributing both to Extremely Low Frequency (ELF) and Radiofrequency (RF) exposure levels. Geospatial propagation models (NISMap) are implemented and validated for environmental outdoor sources of RFs using spot measurements. Spot and fixed longer-term ELF and RF measurements were done in the environments where children spend most of the time. Moreover, personal measurements were taken in order to assess individual exposure to RF. The exposure data are used to explore their relationships with proximity and/or use of EMF-NIR sources. Characterisation of the EMF-NIR exposure by this combination of methods is intended to overcome problems encountered in other research. The assessment of exposure of INMA cohort children and adolescents living in different regions of Spain to the full frequency range of EMF-NIR extends the characterisation of environmental exposures in this cohort. Together with other data obtained in the project, on socioeconomic and family characteristics and development of the children and adolescents, this will enable to evaluate the complex interaction between health outcomes in children and adolescents and the various environmental factors that surround them.

Spatial and temporal analyses for multiscale monitoring of landslides: Examples from Northern Ireland

NASA Astrophysics Data System (ADS)

Bell, Andrew; McKinley, Jennifer; Hughes, David

2013-04-01

Landslides in the form of debris flows, large scale rotational features and composite mudflows impact transport corridors cutting off local communities and in some instances result in loss of life. This study presents landslide monitoring methods used for predicting and characterising landslide activity along transport corridors. A variety of approaches are discussed: desk based risk assessment of slopes using Geographical Information Systems (GIS); Aerial LiDAR surveys and Terrestrial LiDAR monitoring and field instrumentation of selected sites. A GIS based case study is discussed which provides risk assessment for the potential of slope stability issues. Layers incorporated within the system include Digital Elevation Model (DEM), slope, aspect, solid and drift geology and groundwater conditions. Additional datasets include consequence of failure. These are combined within a risk model, presented as likelihoods of failure. This integrated spatial approach for slope risk assessment provides the user with a preliminary risk assessment of sites. An innovative "Flexviewer" web-based server interface allows users to view data without needing advanced GIS techniques to gather information about selected areas. On a macro landscape scale, Aerial LiDAR (ALS) surveys are used for the characterisation of landslides from the surrounding terrain. DEMs are generated along with terrain derivatives: slope, curvature and various measures of terrain roughness. Spatial analysis of terrain morphological parameters allow characterisation of slope stability issues and are used to predict areas of potential failure or recently failure terrain. On a local scale ground monitoring approaches are employed for the monitoring of changes in selected slopes using ALS and risk assessment approaches. Results are shown from on-going bimonthly Terrestrial LiDAR (TLS) monitoring of the slope within a site specific geodectically referenced network. This has allowed a classification of changes in the slopes with DEMs of difference showing areas of recent movement, erosion and deposition. In addition, changes in the structure of the slope characterised by DEM of difference and morphological parameters in the form of roughness, slope and curvature measures are progressively linked to failures indicated from temporal DEM monitoring. Preliminary results are presented for a case site at Straidkilly Point, Glenarm, Co. Antrim, Northern Ireland, illustrating multiple approaches to the spatial and temporal monitoring of landslides. These indicate how spatial morphological approaches and risk assessment frameworks coupled with TLS monitoring and field instrumentation enable characterisation and prediction of potential areas of slope stability issues. On site weather instrumentation and piezometers document changes in pore water pressures resulting in site-specific information with geotechnical observations parameterised within the temporal LiDAR monitoring. This provides a multifaceted approach to the characterisation and analysis of slope stability issues. The presented methodology of multiscale datasets and surveying approaches utilising spatial parameters and risk index mapping enables a more comprehensive and effective prediction of landslides resulting in effective characterisation and remediation strategies.

Stretching of passive tracers and implications for mantle mixing

NASA Astrophysics Data System (ADS)

Conjeepuram, N.; Kellogg, L. H.

2007-12-01

Mid ocean ridge basalts(MORB) and ocean island basalts(OIB) have fundamentally different geochemical signatures. Understanding this difference requires a fundamental knowledge of the mixing processes that led to their formation. Quantitative methods used to assess mixing include examining the distribution of passive tracers, attaching time-evolution information to simulate decay of radioactive isotopes, and, for chaotic flows, calculating the Lyapunov exponent, which characterizes whether two nearby particles diverge at an exponential rate. Although effective, these methods are indirect measures of the two fundamental processes associated with mixing namely, stretching and folding. Building on work done by Kellogg and Turcotte, we present a method to compute the stretching and thinning of a passive, ellipsoidal tracer in three orthogonal directions in isoviscous, incompressible three dimensional flows. We also compute the Lyapunov exponents associated with the given system based on the quantitative measures of stretching and thinning. We test our method with two analytical and three numerical flow fields which exhibit Lagrangian turbulence. The ABC and STF class of analytical flows are a three and two parameter class of flows respectively and have been well studied for fast dynamo action. Since they generate both periodic and chaotic particle paths depending either on the starting point or on the choice of the parameters, they provide a good foundation to understand mixing. The numerical flow fields are similar to the geometries used by Ferrachat and Ricard (1998) and emulate a ridge - transform system. We also compute the stable and unstable manifolds associated with the numerical flow fields to illustrate the directions of rapid and slow mixing. We find that stretching in chaotic flow fields is significantly more effective than regular or periodic flow fields. Consequently, chaotic mixing is far more efficient than regular mixing. We also find that in the numerical flow field, there is a fundamental topological difference in the regions exhibiting slow or regular mixing for different model geometries.

Exploring Intercultural Competence through the Lens of Self-Authorship

ERIC Educational Resources Information Center

Mascadri, Julia; Brownlee, Jo Lunn; Walker, Susan; Alford, Jennifer

2017-01-01

Intercultural competence among educators has long been recognised as important, especially in contexts characterised by growing and shifting cultural diversity such as Australia. However, the capacity to be interculturally competent has only recently been enshrined in teacher standards in Australia, and research into this field among early…

Miazma: physics edutainment through a computer game

NASA Astrophysics Data System (ADS)

Fülöp, Zs.; Biri, S.; Lévai, G.

2017-11-01

The beginning of the 21st century is characterised by several contradictions and challenges. One of them is that scientific and technological development has never been as important for the well-being of humankind as today. Nevertheless, these fields seem to lose the attention of talented and interested youngsters.

Coaches, Sexual Harassment and Education

ERIC Educational Resources Information Center

Fasting, Kari; Brackenridge, Celia

2009-01-01

Sexual harassment in sport has become an active research field within the past decade yet we know relatively little about the characteristics of the harassing coach. How are harassing coaches characterised by their victims, that is, the athletes themselves? Do they demonstrate specific kinds of behaviours? One purpose of this article is to address…

Theorising Knowledge Practices: A Missing Piece of the Educational Technology Puzzle

ERIC Educational Resources Information Center

Howard, Sarah; Maton, Karl

2011-01-01

Educational technology research has been characterised as lacking theoretical frameworks that can enable cumulative knowledge-building across the field. This article explores the value of Legitimation Code Theory (LCT) for addressing these issues by discussing research into the key of integration of information and communication technologies in…

A Compass for Teaching Enterprise Governance

ERIC Educational Resources Information Center

Berg, Terje

2015-01-01

A business school's study programme in general and the field of enterprise governance in particular can be characterised as a mosaic, that is, seemingly independent parts that, in the end, create a meaningful totality. Management accounting encompasses many topics and concepts and there seems to be an overwhelming supply of techniques. Sometimes,…

Phenotypic and molecular characterisation of efficient nitrogen-fixing Azotobacter strains from rice fields for crop improvement.

PubMed

Sahoo, Ranjan K; Ansari, Mohammad W; Dangar, Tushar K; Mohanty, Santanu; Tuteja, Narendra

2014-05-01

Biological nitrogen fixation (BNF) is highly effective in the field and potentially useful to reduce adverse effects chemical fertilisers. Here, Azotobacter species were selected via phenotypic, biochemical and molecular characterisations from different rice fields. Acetylene reduction assay of Azotobacter spp. showed that Azotobacter vinelandii (Az3) fixed higher amount of nitrogen (121.09 nmol C2H4 mg(-1) bacteria h(-1)). Likewise, its plant growth functions, viz. siderophore, hydrogen cyanide, salicylic acid, IAA, GA3, zeatin, NH3, phosphorus solubilisation, ACC deaminase and iron tolerance, were also higher. The profile of gDNA, plasmid DNA and cellular protein profile depicted inter-generic and inter-specific diversity among the isolates of A. vinelandii. The PCR-amplified genes nifH, nifD and nifK of 0.87, 1.4 and 1.5 kb , respectively, were ascertained by Southern blot hybridisation in isolates of A. vinelandii. The 16S rRNA sequence from A. vinelandii (Az3) was novel, and its accession number (JQ796077) was received from NCBI data base. Biofertiliser formulation of novel A. vinelandii isolates along with commercial one was evaluated in rice (Oriza sativa L. var. Khandagiri) fields. The present finding revealed that treatment T4 (Az3) (A. vinelandii) are highly efficient to improved growth and yield of rice crop.

Nanominerals and nanoparticles in feed coal and bottom ash: implications for human health effects.

PubMed

Silva, Luis F O; da Boit, Kátia M

2011-03-01

Environmental and human health risk assessments of nanoparticle effects from coal and bottom ash require thorough characterisation of nanoparticles and their aggregates. In this manuscript, we expand the study of human exposure to nanosized particles from coal combustion sources (typically <100 nm in size), characterising the complex micromineralogy of these airborne combustion-derived nanomaterials. Our study focuses on bottom ash generated in the Santa Catarina power station (Brazil) which uses coal enriched in ashes, many potential elements (e.g. Cr and Ni) and pyrite. Transmission electron microscope data reveal nanoscale C deposits juxtaposed with and overgrown by slightly larger aluminosilicate (Al-Si) glassy spheres, oxides, silicates, carbonated, phosphates and sulphates. Iron oxides (mainly hematite and magnetite) are the main bottom ash products of the oxidation of pyrite, sometimes via intermediate pyrrhotite formation. The presence of iron oxide nanocrystals mixed with silicate glass particles emphasises the complexity of coal and bottom ash micromineralogy. Given the potentially bioreactive nature of such transition metal-bearing materials, there is likely to be an increased health risk associated with their inhalation.

Continuous-spin mixed-symmetry fields in AdS(5)

NASA Astrophysics Data System (ADS)

Metsaev, R. R.

2018-05-01

Free mixed-symmetry continuous-spin fields propagating in AdS(5) space and flat R(4,1) space are studied. In the framework of a light-cone gauge formulation of relativistic dynamics, we build simple actions for such fields. The realization of relativistic symmetries on the space of light-cone gauge mixed-symmetry continuous-spin fields is also found. Interrelations between constant parameters entering the light-cone gauge actions and eigenvalues of the Casimir operators of space-time symmetry algebras are obtained. Using these interrelations and requiring that the field dynamics in AdS(5) be irreducible and classically unitary, we derive restrictions on the constant parameters and eigenvalues of the second-order Casimir operator of the algebra.

The importance of being fractional in mixing: optimal choice of the index s in H-s norm

NASA Astrophysics Data System (ADS)

Vermach, Lukas; Caulfield, C. P.

2015-11-01

A natural measure of homogeneity of a mixture is the variance of the concentration field, which in the case of a zero-mean field is the L2-norm. Mathew et al. (Physica D, 2005) introduced a new multi-scale measure to quantify mixing referred to as the mix-norm, which is equivalent to the H - 1 / 2 norm, the Sobolev norm of negative fractional index. Unlike the L2-norm, the mix-norm is not conserved by the advection equation and thus captures mixing even in the non-diffusive systems. Furthermore, the mix-norm is consistent with the ergodic definition of mixing and Lin et al. (JFM, 2011) showed that this property extends to any norm from the class H-s , s > 0 . We consider a zero-mean passive scalar field organised into two layers of different concentrations advected by a flow field in a torus. We solve two non-linear optimisation problems. We identify the optimal initial perturbation of the velocity field with given initial energy as well as the optimal forcing with given total action (the time integral of the kinetic energy of the flow) which both yield maximal mixing by a target time horizon. We analyse sensitivity of the results with respect to s-variation and thus address the importance of the choice of the fractional index This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/H023348/1 for the University of Cambridge Centre for Doctoral Training, the Cambridge Centre for Analysis.

Characterising the material properties at the interface between skin and a skin vaccination microprojection device.

PubMed

Crichton, Michael L; Archer-Jones, Cameron; Meliga, Stefano; Edwards, Grant; Martin, Darren; Huang, Han; Kendall, Mark A F

2016-05-01

The rapid emergence of micro-devices for biomedical applications over the past two decades has introduced new challenges for the materials used in the devices. Devices like microneedles and the Nanopatch, require sufficient strength to puncture skin often with sharp-slender micro-scale profiles, while maintaining mechanical integrity. For these technologies we sought to address two important questions: 1) On the scale at which the device operates, what forces are required to puncture the skin? And 2) What loads can the projections/microneedles withstand prior to failure. First, we used custom fabricated nanoindentation micro-probes to puncture skin at the micrometre scale, and show that puncture forces are ∼0.25-1.75mN for fresh mouse skin, in agreement with finite element simulations for our device. Then, we used two methods to perform strength tests of Nanopatch projections with varied aspect ratios. The first method used a nanoindenter to apply a force directly on the top or on the side of individual silicon projections (110μm in length, 10μm base radius), to measure the force of fracture. Our second method used an Instron to fracture full rows of projections and characterise a range of projection designs (with the method verified against previous nanoindentation experiments). Finally, we used Cryo-Scanning Electron Microscopy to visualise projections in situ in the skin to confirm the behaviour we quantified, qualitatively. Micro-device development has proliferated in the past decade, including devices that interact with tissues for biomedical outcomes. The field of microneedles for vaccine delivery to skin has opened new material challenges both in understanding tissue material properties and device material. In this work we characterise both the biomaterial properties of skin and the material properties of our microprojection vaccine delivery device. This study directly measures the micro-scale puncture properties of skin, whilst demonstrating clearly how these relate to device design. This will be of strong interest to those in the field of biomedical microdevices. This includes work in the field of wearable and semi-implantable devices, which will require clear understanding of tissue behaviour and material characterisation. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Towards understanding turbulent scalar mixing

NASA Technical Reports Server (NTRS)

Girimaji, Sharath S.

1992-01-01

In an effort towards understanding turbulent scalar mixing, we study the effect of molecular mixing, first in isolation and then by accounting for the effects of the velocity field. The chief motivation for this approach stems from the strong resemblance of the scalar probability density function (PDF) obtained from the scalar field evolving from the heat conduction equation that arises in a turbulent velocity field. However, the evolution of the scalar dissipation is different for the two cases. We attempt to account for these differences, which are due to the velocity field, using a Lagrangian frame analysis. After establishing the usefulness of this approach, we use the heat-conduction simulations (HCS), in lieu of the more expensive direct numerical simulations (DNS), to study many of the less understood aspects of turbulent mixing. Comparison between the HCS data and available models are made whenever possible. It is established that the beta PDF characterizes the evolution of the scalar PDF during mixing from all types of non-premixed initial conditions.

Effect of electrode positions on the mixing characteristics of an electroosmotic micromixer.

PubMed

Seo, H S; Kim, Y J

2014-08-01

In this study, an electrokinetic microchannel with a ring-type mixing chamber is introduced for fast mixing. The modeled micromixer that is used for the study of the electroosmotic effect takes two fluids from different inlets and combines them in a ring-type mixing chamber and, then, they are mixed by the electric fields at the electrodes. In order to compare the mixing performance in the modeled micromixer, we numerically investigated the flow characteristics with different positions of the electrodes in the mixing chamber using the commercial code, COMSOL. In addition, we discussed the concentration distributions of the dissolved substances in the flow fields and compared the mixing efficiency in the modeled micromixer with different electrode positions and operating conditions, such as the frequencies and electric potentials at the electrodes.

The Specificity of Observational Studies in Physical Activity and Sports Sciences: Moving Forward in Mixed Methods Research and Proposals for Achieving Quantitative and Qualitative Symmetry

PubMed Central

Anguera, M. Teresa; Camerino, Oleguer; Castañer, Marta; Sánchez-Algarra, Pedro; Onwuegbuzie, Anthony J.

2017-01-01

Mixed methods studies are been increasingly applied to a diversity of fields. In this paper, we discuss the growing use—and enormous potential—of mixed methods research in the field of sport and physical activity. A second aim is to contribute to strengthening the characteristics of mixed methods research by showing how systematic observation offers rigor within a flexible framework that can be applied to a wide range of situations. Observational methodology is characterized by high scientific rigor and flexibility throughout its different stages and allows the objective study of spontaneous behavior in natural settings, with no external influence. Mixed methods researchers need to take bold yet thoughtful decisions regarding both substantive and procedural issues. We present three fundamental and complementary ideas to guide researchers in this respect: we show why studies of sport and physical activity that use a mixed methods research approach should be included in the field of mixed methods research, we highlight the numerous possibilities offered by observational methodology in this field through the transformation of descriptive data into quantifiable code matrices, and we discuss possible solutions for achieving true integration of qualitative and quantitative findings. PMID:29312061

Mesures in situ par infiltrométrie des propriétés hydrodynamiques des sols de Mnasra (Maroc)

NASA Astrophysics Data System (ADS)

Tamoh, Karim; Maslouhi, Abdellatif

2004-04-01

The aim of this work is the field hydraulic characterisation of Mnasra soils in northern Morocco, which represents an essential step to study the hydraulic and chemical transports through the vadose zone. We have used a tension infiltrometer associated with a transient axisymmetric infiltration method to determine the hydraulic conductivity, which reduces the duration of measurements. This allows us to characterise a large area with many measurements. Parameters of the characteristic functions K( h) and θ( h) are estimated for six different soils belonging to two geomorphologically different domains: a sandy zone and an alluvial plain. To cite this article: K. Tamoh, A. Maslouhi, C. R. Geoscience 336 (2004).

3D imaging of cells in scaffolds: direct labelling for micro CT.

PubMed

Shepherd, David V; Shepherd, Jennifer H; Best, Serena M; Cameron, Ruth E

2018-06-12

The development of in-vitro techniques to characterise the behaviour of cells in biomedical scaffolds is a rapidly developing field. However, until now it has not been possible to visualise, directly in 3D, the extent of cell migration using a desktop X-ray microCT. This paper describes a new technique based on cell labelling with a radio opacifier (barium sulphate), which permits cell tracking without the need for destructive sample preparation. The ability to track cells is highlighted via a comparison of cell migration through demonstrator lyophilised collagen scaffolds with contrasting pore size and interconnectivity. The results demonstrate the ease with which the technique can be used to characterise the effects of scaffold architecture on cell infiltration.

Recent advancements in mechanical characterisation of 3D woven composites

NASA Astrophysics Data System (ADS)

Saleh, Mohamed Nasr; Soutis, Constantinos

2017-12-01

Three dimensional (3D) woven composites have attracted the interest of academia and industry thanks to their damage tolerance characteristics and automated fabric manufacturing. Although much research has been conducted to investigate their out-of-plane "through thickness" properties, still their in-plane properties are not fully understood and rely on extensive experimentation. To date, the literature lacks an inclusive summary of the mechanical characterisation for 3D woven composites. Therefore, the objective of this paper is to provide a comprehensive review of the available research studies on 3D woven composites mechanical characterisation, with less emphasis on the out-of-plane response, but an in-depth review of the in-plane response "un-notched vs. notched". The paper highlights the knowledge gap in the literature of 3D woven composites, suggesting opportunities for future research in this field and a room for improvement in utilising Non-Destructive Techniques (NDT), such as Digital Image Correlation (DIC), Acoustic Emission (AE) and X-ray Computed Tomography (CT), for observing damage initiation and evolution in 3D woven composites that could be used to calibrate and evaluate analytical and numerical models.

Integration of immunological aspects in the European Human Embryonic Stem Cell Registry.

PubMed

Borstlap, Joeri; Kurtz, Andreas

2008-05-01

The immunological properties of stem cells are of increasing importance in regenerative medicine. Immunomodulatory mechanisms seem to play an important role not only with respect to the understanding of underlying mechanisms of autologous versus allogenic therapeutic approaches, but also for endogeneous tissue regeneration. The newly established European human embryonic stem cell registry (hESCreg) offers an international database for the registration, documentation and characterisation of human embryonic stem cells (hESC) and their use. By doing so, hESCreg aims to develop a model procedure for further standardisation efforts in the field of stem cell research and regenerative medicine, and eventually the registry may lead to a repository of therapy-related information. Currently the stem cell characterisation data acquired by the registry are divided into several categories such as cell derivation, culture conditions, genetic constitution, stem cell marker expression and degree of modification. This article describes immunological aspects of stem cell characterisation and explores the layout and relevance of a possible additional section to the hESCreg repository to include immunological characteristics of human embryonic stem cells.

Approach to fitting parameters and clustering for characterising measured voltage dips based on two-dimensional polarisation ellipses

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

García-Sánchez, Tania; Gómez-Lázaro, Emilio; Muljadi, E.

An alternative approach to characterise real voltage dips is proposed and evaluated in this study. The proposed methodology is based on voltage-space vector solutions, identifying parameters for ellipses trajectories by using the least-squares algorithm applied on a sliding window along the disturbance. The most likely patterns are then estimated through a clustering process based on the k-means algorithm. The objective is to offer an efficient and easily implemented alternative to characterise faults and visualise the most likely instantaneous phase-voltage evolution during events through their corresponding voltage-space vector trajectories. This novel solution minimises the data to be stored but maintains extensivemore » information about the dips including starting and ending transients. The proposed methodology has been applied satisfactorily to real voltage dips obtained from intensive field-measurement campaigns carried out in a Spanish wind power plant up to a time period of several years. A comparison to traditional minimum root mean square-voltage and time-duration classifications is also included in this study.« less

Novel reference radiation fields for pulsed photon radiation installed at PTB.

PubMed

Klammer, J; Roth, J; Hupe, O

2012-09-01

Currently, ∼70 % of the occupationally exposed persons in Germany are working in pulsed radiation fields, mainly in the medical sector. It has been known for a few years that active electronic dosemeters exhibit considerable deficits or can even fail completely in pulsed fields. Type test requirements for dosemeters exist only for continuous radiation. Owing to the need of a reference field for pulsed photon radiation and accordingly to the upcoming type test requirements for dosemeters in pulsed radiation, the Physikalisch-Technische Bundesanstalt has developed a novel X-ray reference field for pulsed photon radiation in cooperation with a manufacturer. This reference field, geared to the main applications in the field of medicine, has been well characterised and is now available for research and type testing of dosemeters in pulsed photon radiation.

Deficiencies of active electronic radiation protection dosimeters in pulsed fields.

PubMed

Ankerhold, U; Hupe, O; Ambrosi, P

2009-07-01

Nowadays nearly all radiation fields used for X-ray diagnostics are pulsed. These fields are characterised by a high dose rate during the pulse and a short pulse duration in the range of a few milliseconds. The use of active electronic dosimeters has increased in the past few years, but these types of dosimeters might possibly not measure reliably in pulsed radiation fields. Not only personal dosimeters but also area dosimeters that are used mainly for dose rate measurements are concerned. These cannot be substituted by using passive dosimeter types. The characteristics of active electronic dosimeters determined in a continuous radiation field cannot be transferred to those in pulsed fields. Some provisional measurements with typical electronic dosimeters in pulsed radiation fields are presented to reveal this basic problem.

Performance of a PTW 60019 microDiamond detector in a 1.5 T MRI-linac

NASA Astrophysics Data System (ADS)

Woodings, S. J.; Wolthaus, J. W. H.; van Asselen, B.; de Vries, J. H. W.; Kok, J. G. M.; Lagendijk, J. J. W.; Raaymakers, B. W.

2018-03-01

Accurate small-field dosimetry is critical for a magnetic resonance linac (MRI-linac). The PTW 60019 microDiamond is close to an ideal detector for small field dosimetry due to its small physical size, high signal-to-noise ratio and approximate water equivalence. It is important to fully characterise the performance of the detector in a 1.5 T magnetic field prior to its use for MRI-linac commissioning and quality assurance. Standard techniques of detector testing have been implemented, or adapted where necessary to suit the capabilities of the MRI-linac. Detector warmup, constancy, dose linearity, dose rate linearity, field size dependence and leakage were within tolerance. Measurements with the detector were consistent with ion chamber measurements for medium sized fields. The effective point of measurement of the detector when used within a 1.5 T magnetic field was determined to be 0.80 ± 0.23 mm below the top surface of the device, consistent with the existing vendor recommendation and alignment mark at 1.0 mm. The angular dependence was assessed. Variations of up to 9.7% were observed, which are significantly greater than in a 0 T environment. Within the expected range of use, the maximum effect is approximately 0.6% which is within tolerance. However for large beams within a magnetic field, the divergence and consequent variation in angle of photon incidence means that the microDiamond would not be ideal for characterising the profiles and it would not be suitable for determining large-field beam parameters such as symmetry. It would also require a correction factor prior to use for patient-specific QA measurements where radiation is delivered from different gantry angles. The results of this study demonstrate that the PTW 60019 microDiamond detector is suitable for measuring small radiation fields within a 1.5 T magnetic field and thus is suitable for use in MRI-linac commissioning and quality assurance.

Performance of a PTW 60019 microDiamond detector in a 1.5 T MRI-linac.

PubMed

Woodings, S J; Wolthaus, J W H; van Asselen, B; de Vries, J H W; Kok, J G M; Lagendijk, J J W; Raaymakers, B W

2018-03-08

Accurate small-field dosimetry is critical for a magnetic resonance linac (MRI-linac). The PTW 60019 microDiamond is close to an ideal detector for small field dosimetry due to its small physical size, high signal-to-noise ratio and approximate water equivalence. It is important to fully characterise the performance of the detector in a 1.5 T magnetic field prior to its use for MRI-linac commissioning and quality assurance. Standard techniques of detector testing have been implemented, or adapted where necessary to suit the capabilities of the MRI-linac. Detector warmup, constancy, dose linearity, dose rate linearity, field size dependence and leakage were within tolerance. Measurements with the detector were consistent with ion chamber measurements for medium sized fields. The effective point of measurement of the detector when used within a 1.5 T magnetic field was determined to be 0.80 ± 0.23 mm below the top surface of the device, consistent with the existing vendor recommendation and alignment mark at 1.0 mm. The angular dependence was assessed. Variations of up to 9.7% were observed, which are significantly greater than in a 0 T environment. Within the expected range of use, the maximum effect is approximately 0.6% which is within tolerance. However for large beams within a magnetic field, the divergence and consequent variation in angle of photon incidence means that the microDiamond would not be ideal for characterising the profiles and it would not be suitable for determining large-field beam parameters such as symmetry. It would also require a correction factor prior to use for patient-specific QA measurements where radiation is delivered from different gantry angles. The results of this study demonstrate that the PTW 60019 microDiamond detector is suitable for measuring small radiation fields within a 1.5 T magnetic field and thus is suitable for use in MRI-linac commissioning and quality assurance.

Catamenial psychosis in an adolescent girl

PubMed Central

Fernando, Myra Deanne; Grizzaffi, Joseph; Crapanzano, Kathleen A; Jones, Glenn N

2014-01-01

We report the case of an adolescent girl who was 14 years old at initial presentation. A shy, immature and timid individual, she began to have recurring, progressive episodes characterised by insomnia, paranoia, distorted thinking and mood instability with a mix of depressive and manic-like symptoms. An extensive medical work up was unrevealing. Her family noted a pattern that coincided with her menstrual cycle. An endocrine consult was obtained, and the diagnosis of catamenial psychosis was performed. After treatment with leuprolide, resulting in a shutdown of the hypothalamic-pituitary-ovarian axis, the patient’s symptoms were resolved completely. PMID:25422338

Electric-field-driven electron-transfer in mixed-valence molecules.

PubMed

Blair, Enrique P; Corcelli, Steven A; Lent, Craig S

2016-07-07

Molecular quantum-dot cellular automata is a computing paradigm in which digital information is encoded by the charge configuration of a mixed-valence molecule. General-purpose computing can be achieved by arranging these compounds on a substrate and exploiting intermolecular Coulombic coupling. The operation of such a device relies on nonequilibrium electron transfer (ET), whereby the time-varying electric field of one molecule induces an ET event in a neighboring molecule. The magnitude of the electric fields can be quite large because of close spatial proximity, and the induced ET rate is a measure of the nonequilibrium response of the molecule. We calculate the electric-field-driven ET rate for a model mixed-valence compound. The mixed-valence molecule is regarded as a two-state electronic system coupled to a molecular vibrational mode, which is, in turn, coupled to a thermal environment. Both the electronic and vibrational degrees-of-freedom are treated quantum mechanically, and the dissipative vibrational-bath interaction is modeled with the Lindblad equation. This approach captures both tunneling and nonadiabatic dynamics. Relationships between microscopic molecular properties and the driven ET rate are explored for two time-dependent applied fields: an abruptly switched field and a linearly ramped field. In both cases, the driven ET rate is only weakly temperature dependent. When the model is applied using parameters appropriate to a specific mixed-valence molecule, diferrocenylacetylene, terahertz-range ET transfer rates are predicted.

Sensitive fluorescent in situ hybridisation method for the characterisation of breast cancer cells in bone marrow aspirates.

PubMed Central

Forus, A; Høifødt, H K; Overli, G E; Myklebost, O; Fodstad, O

1999-01-01

AIM: The presence of malignant cells in the blood and bone marrow of patients with cancer at the time of surgery may be indicative of early relapse. In addition to their numbers, the phenotypes of the micrometastatic cells might be essential in determining whether overt metastases will develop. This study aimed to establish a sensitive method for the detection and characterisation of malignant cells present in bone marrow. METHODS: In spiking experiments, SKBR3 cells were mixed with mononuclear cells in known proportions to mimic bone marrow samples with micrometastatic cells. Tumour cells were extracted using SAM-M450 Dynabeads coupled to the MOC-31 anti-epithelial antibody, and were further analysed for amplification of erbB2 and int2 by fluorescent in situ hybridisation (FISH). erbB2 and int2 copy numbers were also determined in 15 primary breast cancers, and bone marrow samples from patients with amplification were analysed for micrometastatic cells by immunomagnetic enrichment and FISH. RESULTS: In model experiments, cells with amplification could be detected in bead selected fractions when ratios of tumour cells (SKBR3) to mononuclear cells were as low as 10:10(7). Among the tumour samples, eight showed increased copy numbers of erbB2 and/or int2, and three of these patients had detectable numbers of tumour cells in their bone marrow: 4000, 540, and 26 tumour cells/10(7) mononuclear cells, respectively. The patient with 540 tumour cells/10(7) mononuclear cells showed high level amplification of erbB2 and suffered from a particularly aggressive disease, whereas the patient with 4000 tumour cells/10(7) mononuclear cells had favourable disease progression. CONCLUSION: These results demonstrate the feasibility and advantage of combining immunomagnetic selection and FISH characterisation of cancer cells in bone marrow samples. It is possible that molecular characterisation of such cells could provide prognostically valuable information. PMID:10474684

Nanoindentation characterisation of human colorectal cancer cells considering cell geometry, surface roughness and hyperelastic constitutive behaviour

NASA Astrophysics Data System (ADS)

Boccaccio, Antonio; Uva, Antonio E.; Papi, Massimiliano; Fiorentino, Michele; De Spirito, Marco; Monno, Giuseppe

2017-01-01

Characterisation of the mechanical behaviour of cancer cells is an issue of crucial importance as specific cell mechanical properties have been measured and utilized as possible biomarkers of cancer progression. Atomic force microscopy certainly occupies a prominent place in the field of the mechanical characterisation devices. We developed a hybrid approach to characterise different cell lines (SW620 and SW480) of the human colon carcinoma submitted to nanoindentation measurements. An ad hoc algorithm was written that compares the force-indentation curves experimentally retrieved with those predicted by a finite element model that simulates the nanoindentation process and reproduces the cell geometry and the surface roughness. The algorithm perturbs iteratively the values of the cell mechanical properties implemented in the finite element model until the difference between the experimental and numerical force-indentation curves reaches the minimum value. The occurrence of this indicates that the implemented material properties are very close to the real ones. Different hyperelastic constitutive models, such as Arruda-Boyce, Mooney-Rivlin and Neo-Hookean were utilized to describe the structural behaviour of indented cells. The algorithm was capable of separating, for all the cell lines investigated, the mechanical properties of cell cortex and cytoskeleton. Material properties determined via the algorithm were different with respect to those obtained with the Hertzian contact theory. This demonstrates that factors such as: the cell geometry/anatomy and the hyperelastic constitutive behaviour, which are not contemplated in the Hertz’s theory hypotheses, do affect the nanoindentation measurements. The proposed approach represents a powerful tool that, only on the basis of nanoindentation measurements, is capable of characterising material at the subcellular level.

Mixing and transport during pharmaceutical twin-screw wet granulation: experimental analysis via chemical imaging.

PubMed

Kumar, Ashish; Vercruysse, Jurgen; Toiviainen, Maunu; Panouillot, Pierre-Emmanuel; Juuti, Mikko; Vanhoorne, Valérie; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

2014-07-01

Twin-screw granulation is a promising continuous alternative for traditional batch high shear wet granulation (HSWG). The extent of HSWG in a twin screw granulator (TSG) is greatly governed by the residence time of the granulation materials in the TSG and degree of mixing. In order to determine the residence time distribution (RTD) and mixing in TSG, mostly visual observation and particle tracking methods are used, which are either inaccurate and difficult for short RTD, or provide an RTD only for a finite number of preferential tracer paths. In this study, near infrared chemical imaging, which is more accurate and provides a complete RTD, was used. The impact of changes in material throughput (10-17 kg/h), screw speed (500-900 rpm), number of kneading discs (2-12) and stagger angle (30-90°) on the RTD and axial mixing of the material was characterised. The experimental RTD curves were used to calculate the mean residence time, mean centred variance and the Péclet number to determine the axial mixing and predominance of convective over dispersive transport. The results showed that screw speed is the most influential parameter in terms of RTD and axial mixing in the TSG and established a significant interaction between screw design parameters (number and stagger angle of kneading discs) and the process parameters (material throughput and number of kneading discs). The results of the study will allow the development and validation of a transport model capable of predicting the RTD and macro-mixing in the TSG. These can later be coupled with a population balance model in order to predict granulation yields in a TSG more accurately. Copyright © 2014 Elsevier B.V. All rights reserved.

Numerical analysis of mixing enhancement for micro-electroosmotic flow

NASA Astrophysics Data System (ADS)

Tang, G. H.; He, Y. L.; Tao, W. Q.

2010-05-01

Micro-electroosmotic flow is usually slow with negligible inertial effects and diffusion-based mixing can be problematic. To gain an improved understanding of electroosmotic mixing in microchannels, a numerical study has been carried out for channels patterned with wall blocks, and channels patterned with heterogeneous surfaces. The lattice Boltzmann method has been employed to obtain the external electric field, electric potential distribution in the electrolyte, the flow field, and the species concentration distribution within the same framework. The simulation results show that wall blocks and heterogeneous surfaces can significantly disturb the streamlines by fluid folding and stretching leading to apparently substantial improvements in mixing. However, the results show that the introduction of such features can substantially reduce the mass flow rate and thus effectively prolongs the available mixing time when the flow passes through the channel. This is a non-negligible factor on the effectiveness of the observed improvements in mixing efficiency. Compared with the heterogeneous surface distribution, the wall block cases can achieve more effective enhancement in the same mixing time. In addition, the field synergy theory is extended to analyze the mixing enhancement in electroosmotic flow. The distribution of the local synergy angle in the channel aids to evaluate the effectiveness of enhancement method.

Swapping Settings: Researching Information Literacy in Workplace and in Educational Contexts

ERIC Educational Resources Information Center

Lundh, Anna Hampson; Limberg, Louise; Lloyd, Annemaree

2013-01-01

Introduction: Information literacy research is characterised by a multitude of interests, research approaches and theoretical starting-points. Challenges lie in the relevance of research to professional fields where information literacy is a concern, and the need to build a strong theoretical base for the research area. We aim to lay a foundation…

Methodological Capacity within the Field of "Educational Technology" Research: An Initial Investigation

ERIC Educational Resources Information Center

Bulfin, Scott; Henderson, Michael; Johnson, Nicola F.; Selwyn, Neil

2014-01-01

The academic study of educational technology is often characterised by critics as methodologically limited. In order to test this assumption, the present paper reports on data collected from a survey of 462 "research active" academic researchers working in the broad areas of educational technology and educational media. The paper…

Embracing Connectedness and Change: A Complex Dynamic Systems Perspective for Applied Linguistic Research

ERIC Educational Resources Information Center

Cameron, Lynne

2015-01-01

Complex dynamic systems (CDS) theory offers a powerful metaphorical model of applied linguistic processes, allowing holistic descriptions of situated phenomena, and addressing the connectedness and change that often characterise issues in our field. A recent study of Kenyan conflict transformation illustrates application of a CDS perspective. Key…

UMTS signal measurements with digital spectrum analysers.

PubMed

Licitra, G; Palazzuoli, D; Ricci, A S; Silvi, A M

2004-01-01

The launch of the Universal Mobile Telecommunications System (UMTS), the most recent mobile telecommunications standard has imposed the requirement of updating measurement instrumentation and methodologies. In order to define the most reliable measurement procedure, which is aimed at assessing the exposure to electromagnetic fields, modern spectrum analysers' features for correct signal characterisation has been reviewed.

Uncertainty in vegetation products derived from field spectral measurements: an error budget approach

NASA Astrophysics Data System (ADS)

Anderson, K.; Dungan, J. L.

2008-12-01

One of the biggest challenges in the use of proximal remote sensing methods continues to be the accurate, reproducible characterisation of natural surface reflectance properties measured in the solar radiation environment. Complexities in such measurements arise from differences in instrument type, field-of-view, atmospheric conditions, solar illumination and measurement angles and uncertainty in the calibration of reference sources used. Three GER 1500 spectroradiometers were used to measure the reflectance of a short sward grass canopy. A full laboratory assessment was first carried out to characterise instrument uncertainty. Wavelength-dependent patterns in noise equivalent delta radiances (NEdL) were similar for all three instruments, (less than 1 W m-2 sr μm-1 in the range 400-1000 nm). The spectroradiometers were then used in the field, each in a single-beam configuration and two in a dual-field- of-view configuration to compare their field reproducibility to laboratory measurements. Hemispherical-conical reflectance factors (HCRF) were collected in clear sky conditions of a grass (Pennisetum clandestinum) canopy. Two measurement dates were used where skies were clean (diffuse-to-global (DG) irradiance ratios < 0.13) and stable (standard deviation in DG < 0.001). Spectra were collected at nadir during the two- hour period spanning solar noon with a 2° range in solar zenith angles. A reproducible method was used which enabled positioning of instruments to within 1° precision in the azimuthal direction and with no movement in zenithal position. Ten measurements were taken with each sensor head, from a calibrated optical grade Spectralon panel (99% reflecting), the grass target, and a control surface -- a grey, 75% Spectralon panel. After each sequence the sensor heads were changed. On each date, the sequence of measurements was repeated. Field results showed standard uncertainties (u) of less than 0.01 (SD in HCRF) for the grey panel and less than 0.015 for vegetation. The grey panel data showed a wavelength- dependent pattern, similar to the NEdL laboratory trend, but subsequent error propagation of laboratory- derived NEdL through to a reflectance factor showed that the laboratory characterisation was unable to account for all of the uncertainty measured in the field. Therefore the estimate of u gained from field data more closely represents the reproducibility of measurements where atmospheric, solar zenith and instrument-related uncertainties are combined. Results on vegetation u showed a stronger wavelength dependency with higher standard uncertainties beyond the vegetation red-edge than in visible wavelengths (maximum = 0.015 at 800 nm, and 0.004 at 550nm). The results demonstrate that standard uncertainties of field reflectance data have a spectral dependence and exceed laboratory-derived estimates of instrument "noise". Uncertainty of this type must be taken into account when statistically testing for differences in field spectra. Improved reporting of standard uncertainties from field experiments will foster progress in remote sensing science.

Layered acoustofluidic resonators for the simultaneous optical and acoustic characterisation of cavitation dynamics, microstreaming, and biological effects.

PubMed

Pereno, V; Aron, M; Vince, O; Mannaris, C; Seth, A; de Saint Victor, M; Lajoinie, G; Versluis, M; Coussios, C; Carugo, D; Stride, E

2018-05-01

The study of the effects of ultrasound-induced acoustic cavitation on biological structures is an active field in biomedical research. Of particular interest for therapeutic applications is the ability of oscillating microbubbles to promote both cellular and tissue membrane permeabilisation and to improve the distribution of therapeutic agents in tissue through extravasation and convective transport. The mechanisms that underpin the interaction between cavitating agents and tissues are, however, still poorly understood. One challenge is the practical difficulty involved in performing optical microscopy and acoustic emissions monitoring simultaneously in a biologically compatible environment. Here we present and characterise a microfluidic layered acoustic resonator ( μ LAR) developed for simultaneous ultrasound exposure, acoustic emissions monitoring, and microscopy of biological samples. The μ LAR facilitates in vitro ultrasound experiments in which measurements of microbubble dynamics, microstreaming velocity fields, acoustic emissions, and cell-microbubble interactions can be performed simultaneously. The device and analyses presented provide a means of performing mechanistic in vitro studies that may benefit the design of predictable and effective cavitation-based ultrasound treatments.

Nutrition economics – characterising the economic and health impact of nutrition

PubMed Central

Lenoir-Wijnkoop, I.; Dapoigny, M.; Dubois, D.; van Ganse, E.; Gutiérrez-Ibarluzea, I.; Hutton, J.; Jones, P.; Mittendorf, T.; Poley, M. J.; Salminen, S.; Nuijten, M. J. C.

2011-01-01

There is a new merging of health economics and nutrition disciplines to assess the impact of diet on health and disease prevention and to characterise the health and economic aspects of specific changes in nutritional behaviour and nutrition recommendations. A rationale exists for developing the field of nutrition economics which could offer a better understanding of both nutrition, in the context of having a significant influence on health outcomes, and economics, in order to estimate the absolute and relative monetary impact of health measures. For this purpose, an expert meeting assessed questions aimed at clarifying the scope and identifying the key issues that should be taken into consideration in developing nutrition economics as a discipline that could potentially address important questions. We propose a first multidisciplinary outline for understanding the principles and particular characteristics of this emerging field. We summarise here the concepts and the observations of workshop participants and propose a basic setting for nutrition economics and health outcomes research as a novel discipline to support nutrition, health economics and health policy development in an evidence and health-benefit-based manner. PMID:20797310

Nutrition economics - characterising the economic and health impact of nutrition.

PubMed

Lenoir-Wijnkoop, I; Dapoigny, M; Dubois, D; van Ganse, E; Gutiérrez-Ibarluzea, I; Hutton, J; Jones, P; Mittendorf, T; Poley, M J; Salminen, S; Nuijten, M J C

2011-01-01

There is a new merging of health economics and nutrition disciplines to assess the impact of diet on health and disease prevention and to characterise the health and economic aspects of specific changes in nutritional behaviour and nutrition recommendations. A rationale exists for developing the field of nutrition economics which could offer a better understanding of both nutrition, in the context of having a significant influence on health outcomes, and economics, in order to estimate the absolute and relative monetary impact of health measures. For this purpose, an expert meeting assessed questions aimed at clarifying the scope and identifying the key issues that should be taken into consideration in developing nutrition economics as a discipline that could potentially address important questions. We propose a first multidisciplinary outline for understanding the principles and particular characteristics of this emerging field. We summarise here the concepts and the observations of workshop participants and propose a basic setting for nutrition economics and health outcomes research as a novel discipline to support nutrition, health economics and health policy development in an evidence and health-benefit-based manner.

Asymmetric flow field-flow fractionation (AF4) for the quantification of nanoparticle release from tablets during dissolution testing.

PubMed

Engel, A; Plöger, M; Mulac, D; Langer, K

2014-01-30

Nanoparticles composed of poly(DL-lactide-co-glycolide) (PLGA) represent promising colloidal drug carriers for improved drug targeting. Although most research activities are focused on intravenous application of these carriers the peroral administration is described to improve bioavailability of poorly soluble drugs. Based on these insights the manuscript describes a model tablet formulation for PLGA-nanoparticles and especially its analytical characterisation with regard to a nanosized drug carrier. Besides physico-chemical tablet characterisation according to pharmacopoeias the main goal of the study was the development of a suitable analytical method for the quantification of nanoparticle release from tablets. An analytical flow field-flow fractionation (AF4) method was established and validated which enables determination of nanoparticle content in solid dosage forms as well as quantification of particle release during dissolution testing. For particle detection a multi-angle light scattering (MALS) detector was coupled to the AF4-system. After dissolution testing, the presence of unaltered PLGA-nanoparticles was successfully proved by dynamic light scattering and scanning electron microscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

Micromixer utilizing electrokinetic instability-induced shedding effect.

PubMed

Tai, Chang-Hsien; Yang, Ruey-Jen; Huang, Min-Zhong; Liu, Chia-Wei; Tsai, Chien-Hsiung; Fu, Lung-Ming

2006-12-01

This paper presents a T-shaped micromixer featuring 45 degrees parallelogram barriers (PBs) within the mixing channel. The presented device obtains a rapid mixing of two sample fluids with conductivity ratio of 10:1 (sample concentration:running buffer concentration) by means of the electrokinetic instability-induced shedding effects which are produced when a direct current (DC) electric field of an appropriate intensity is applied. The presented device uses a single high-voltage power source to simultaneously drive and mix the sample fluids. The effectiveness of the mixer is characterized experimentally as a function of the applied electrical field intensity and the extent to which the PBs obstruct the mixing channel. The experimental results indicate that the mixing performance reaches 91% at a cross-section located 2.3 mm downstream of the T-junction when the barriers obstruct 4/5 of the channel width and an electrical field of 300 V/cm is applied. The micromixing method presented in this study provides a simple low-cost solution to mixing problems in lab-on-a-chip systems.

Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

NASA Astrophysics Data System (ADS)

Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

2014-11-01

The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in northern Italy, while a substantial fraction (41%) was due to the most aged aerosols imported from transalpine areas. The different meteorological regimes also affected the BC mixing state: in periods of enhanced stagnation and recirculation of pollutants, the number fraction of the BC-containing particles determined by ATOFMS was 75% of the total, while in the days of enhanced ventilation of the planetary boundary layer (PBL), such fraction was significantly lower (50%) because of the relative greater influence of non-BC-containing aerosol local sources in the Po Valley. Overall, a full internal mixing between BC and the non-refractory aerosol chemical components was not observed during the experiment in this environment.

Nanoscale Control over the Mixing Behavior of Surface-Confined Bicomponent Supramolecular Networks Using an Oriented External Electric Field

PubMed Central

2017-01-01

Strong electric fields are known to influence the properties of molecules as well as materials. Here we show that by changing the orientation of an externally applied electric field, one can locally control the mixing behavior of two molecules physisorbed on a solid surface. Whether the starting two-component network evolves into an ordered two-dimensional (2D) cocrystal, yields an amorphous network where the two components phase separate, or shows preferential adsorption of only one component depends on the solution stoichiometry. The experiments are carried out by changing the orientation of the strong electric field that exists between the tip of a scanning tunneling microscope and a solid substrate. The structure of the two-component network typically changes from open porous at negative substrate bias to relatively compact when the polarity of the applied bias is reversed. The electric-field-induced mixing behavior is reversible, and the supramolecular system exhibits excellent stability and good response efficiency. When molecular guests are adsorbed in the porous networks, the field-induced switching behavior was found to be completely different. Plausible reasons behind the field-induced mixing behavior are discussed. PMID:29112378

Influence of continuous magnetic field on the separation of ephedrine enantiomers by molecularly imprinted polymers.

PubMed

Guerreiro, António R; Korkhov, Vadim; Mijangos, Irene; Piletska, Elena V; Rodins, Juris; Turner, Anthony P F; Piletsky, Sergey A

2008-02-28

A set of polymers was imprinted with (-)-ephedrine using UV initiation, under the influence of a constant external magnetic field with intensities ranging from 0 to 1.55 T. Synthesised materials were characterised by X-ray crystallography, infrared spectroscopy, swelling and surface area. Recognition properties were assessed by the ability to discriminate between (+) and (-)-ephedrine and by Scatchard analyses on chromatographic mode. It was shown that polymer morphology and recognition properties are affected by the magnetic field. This resulted in considerable improvements in the chromatographic resolution of ephedrine enantiomers by materials synthesised under the influence of magnetic field. Apparently the magnetic field improved the ordering of the polymer structure and facilitated the formation of more uniform imprinting sites.

Effect of mix parameters on longevity of bituminous mixtures

NASA Astrophysics Data System (ADS)

Reichle, Clayton Matthew

This study was performed to evaluate the effects of varying aggregate sources, aggregate gradations on the stripping and rutting potential of bituminous based plant mixes specified by the Missouri Department of Transportation. The different aggregate combinations included two different aggregate sources (Potosi Dolomite and Jefferson City Dolomite) including two variations for the Jefferson City Dolomite mix to simulate a marginally in-specification mix and an out-of-specification but in-field tolerance mix. The "field" mix simulated the marginal mix where field tolerance of high dust and low binder content were maximized. All three mixes were evaluated for stripping susceptibility using the Tensile Strength Ratio (TSR) test and the Hamburg Wheel Tracking Device (HWTD). The mix characteristics (unit weight, effective binder content, and air voids) were used for a Level 3 analysis in the Mechanistic-Empirical Pavement Design Guide (MEPDG) to determine long term pavement distress conditions such as fatigue cracking, rutting, and IRI (smoothness). The Potosi mix exhibited the best resistance to rutting and stripping during both the TSR testing as well as the Hamburg testing. The Jefferson City In-Spec and Out-of-Spec mixes showed less resistance to rutting and stripping in order, respectively. This was expected for the Jefferson City mixes where the aggregate was of lower quality (higher Los Angeles Abrasion, Micro Deval loss, absorption, and deleterious materials). Also, in the case of the Jefferson City Out-of-Spec mix, the binder content was lower. Upon evaluating the mixes using the MEPDG software, it was shown that mix characteristics such as air voids, VMA, and VFA influenced the fatigue cracking, rutting, and IRI predictions to a minor degree.

Integrated ExoMars PanCam, Raman, and close-up imaging field tests on AMASE 2009

NASA Astrophysics Data System (ADS)

Foss Amundsen, Hans Erik; Westall, Frances; Steele, Andrew; Vago, Jorge; Schmitz, Nicole; Bauer, Arnold; Cousins, Claire; Rull, Fernando; Sansano, Antonio; Midtkandal, Ivar

2010-05-01

Arctic Mars Analog Svalbard Expedition (AMASE) uses Mars analog field sites on the Arctic islands of Svalbard (Norway) for research within astrobiology and for testing of payload instruments onboard Mars missions Mars Science Laboratory, ExoMars and Mars Sample Return. AMASE 2009 marked the seventh consecutive year of field testing. Instrument shakedowns were arranged to mimic rover operations on Mars and included the panoramic camera (PanCam), mineral- and organic chemistry sensors (Raman-LIBS) and ground penetrating radar (Wisdom) onboard ExoMars together with CheMin and SAM instruments onboard MSL and testing of sampling and caching protocols using JPĹs Fido rover. Test sites included volcanic rocks within the Bockfjord Volcanic Complex (BVC) with carbonate deposits identical to those in ALH84001 and Carboniferous sandstones and paleosols at Ismåsestranda. In view of the 2018 ExoMars mission, field models of the PanCam and Raman instruments, as well as an Olympus E410 camera having similar technical specifications to the ExoMars Close-Up Imager (CLUPI) were used in an integrated exercise to characterise the geology and habitability of the different field sites. The BVC locality consisted of volcanclastic sediments deposited on the flanks of the 1 Ma old Sverrefjell volcano. This volcano is constructed of primitive alkaline basalt with abundant mantle xenoliths. The sediments were a mixture of hyaloclastite, ash, volcanic bombs, lava detritus, and xenoliths (peridotites, granulites) deposited in a roughly laminated fashion on the slopes of the volcano. Late stage carbonate deposits were also present. The Ismåsestranda locality consisted of fine-grained sandstone deposited in a littoral environment. The sandstones were characterised by a variety of sedimentary structures reflecting a marginal marine depositional environment. They were highly variegated in colour due to diagenetic remobilisation of trace elements. PanCam made general context observations using the stereo Wide Angle Camera for taking images at 12 VIS-NIR wavelengths. More detailed images were made with the narrow angle colour High Resolution Channel of PanCam (PanCam HRC). These images were complimented by colour images made at 50-7 cm distance from the rock targets by the CLUPI-simulator camera. Compositional information was provided by the Raman spectrometer.The images and analyses obtained from the instruments permitted preliminary characterisation of the geological context at the two test sites. However, full characterisation of the rocks using more than one site is necessary to correctly interpret the nature of the rocks and their environment of formation, especially in the case of the Ismåsestranda sediments. Joint testing of ExoMars, MSL and MSR instruments on AMASE provides a unique opportunity to highgrade instrument selection for future Mars missions and to foster collaboration between ESA and NASA teams towards the tandem launch of ExoMars and MAX-C in 2018.

Field trial of solvent-free emulsion in Oregon : appendices.

DOT National Transportation Integrated Search

2003-03-01

This final report summarizes construction, laboratory and performance information gathered by ODOT personnel from a single field trial of solvent-free emulsion mix constructed in June 2001. The solvent-free emulsion mix presented several placement pr...

Vlasov Simulation of Mixing in Antihydrogen Formation

NASA Astrophysics Data System (ADS)

So, Chukman; Fajans, Joel; Friedland, Lazar; Wurtele, Jonathan; Alpha Collaboration

2011-10-01

In the ALPHA apparatus, low temperature antiprotons (p) and positrons (e+) are prepared adjacent to each other in a nested Penning trap. To create trappable antihydrogen (H), the two species must be mixed such that some resultant H atoms have sub-Kelvin kinetic energy. A new simulation has been developed to study and optimize the autoresonant mixing, in ALPHA. The p dynamics are governed by their own self- field, the e+ plasma field, and the external fields. The e+ 's are handled quasi-statically with a Poisson-Boltzmann solver. p 's are handled by multiple time dependent 1D Vlasov-Poisson solvers, each representing a radial slice of the plasma. The 1D simulatiuons couple through the 2D Poisson equation. We neglect radial transport due to the strong solenoidal field. The advantages and disadvantages of different descretization schemes, comparisons of simulation with experiment, and techniques for optimizing mixing, will be presented.

Comparison of visual receptive fields in the dorsolateral prefrontal cortex and ventral intraparietal area in macaques.

PubMed

Viswanathan, Pooja; Nieder, Andreas

2017-12-01

The concept of receptive field (RF) describes the responsiveness of neurons to sensory space. Neurons in the primate association cortices have long been known to be spatially selective but a detailed characterisation and direct comparison of RFs between frontal and parietal association cortices are missing. We sampled the RFs of a large number of neurons from two interconnected areas of the frontal and parietal lobes, the dorsolateral prefrontal cortex (dlPFC) and ventral intraparietal area (VIP), of rhesus monkeys by systematically presenting a moving bar during passive fixation. We found that more than half of neurons in both areas showed spatial selectivity. Single neurons in both areas could be assigned to five classes according to the spatial response patterns: few non-uniform RFs with multiple discrete response maxima could be dissociated from the vast majority of uniform RFs showing a single maximum; the latter were further classified into full-field and confined foveal, contralateral and ipsilateral RFs. Neurons in dlPFC showed a preference for the contralateral visual space and collectively encoded the contralateral visual hemi-field. In contrast, VIP neurons preferred central locations, predominantly covering the foveal visual space. Putative pyramidal cells with broad-spiking waveforms in PFC had smaller RFs than putative interneurons showing narrow-spiking waveforms, but distributed similarly across the visual field. In VIP, however, both putative pyramidal cells and interneurons had similar RFs at similar eccentricities. We provide a first, thorough characterisation of visual RFs in two reciprocally connected areas of a fronto-parietal cortical network. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Weaving the history of the solar wind with magnetic field lines

NASA Astrophysics Data System (ADS)

Alvarado Gomez, Julian

2017-08-01

Despite its fundamental role for the evolution of the solar system, our observational knowledge of the wind properties of the young Sun comes from a single stellar observation. This unexpected fact for a field such as astrophysics arises from the difficulty of detecting Sun-like stellar winds. Their detection relies on the appearance of an astrospheric signature (from the stellar wind-ISM interaction region), visible only with the aid of high-resolution HST Lyman-alpha spectra. However, observations and modelling of the present day Sun have revealed that magnetic fields constitute the main driver of the solar wind, providing guidance on how such winds would look like back in time. In this context we propose observations of four young Sun-like stars in order to detect their astrospheres and characterise their stellar winds. For all these objects we have recovered surface magnetic field maps using the technique of Zeeman Doppler Imaging, and developed detailed wind models based on these observed field distributions. Even a single detection would represent a major step forward for our understanding of the history of the solar wind, and the outflows in more active stars. Mass loss rate estimates from HST will be confronted with predictions from realistic models of the corona/stellar wind. In one of our objects the comparison would allow us to quantify the wind variability induced by the magnetic cycle of a star, other than the Sun, for the first time. Three of our targets are planet hosts, thus the HST spectra would also provide key information on the high-energy environment of these systems, guaranteeing their legacy value for the growing field of exoplanet characterisation.

Characterisation of flattening filter free (FFF) beam properties for initial beam set-up and routine QA, independent of flattened beams

NASA Astrophysics Data System (ADS)

Paynter, D.; Weston, S. J.; Cosgrove, V. P.; Thwaites, D. I.

2018-01-01

Flattening filter free (FFF) beams have reached widespread use for clinical treatment deliveries. The usual methods for FFF beam characterisation for their quality assurance (QA) require the use of associated conventional flattened beams (cFF). Methods for QA of FFF without the need to use associated cFF beams are presented and evaluated against current methods for both FFF and cFF beams. Inflection point normalisation is evaluated against conventional methods for the determination of field size and penumbra for field sizes from 3 cm  ×  3 cm to 40 cm  ×  40cm at depths from dmax to 20 cm in water for matched and unmatched FFF beams and for cFF beams. A method for measuring symmetry in the cross plane direction is suggested and evaluated as FFF beams are insensitive to symmetry changes in this direction. Methods for characterising beam energy are evaluated and the impact of beam energy on profile shape compared to that of cFF beams. In-plane symmetry can be measured, as can cFF beams, using observed changes in profile, whereas cross-plane symmetry can be measured by acquiring profiles at collimator angles 0 and 180. Beam energy and ‘unflatness’ can be measured as with cFF beams from observed shifts in profile with changing beam energy. Normalising the inflection points of FFF beams to 55% results in an equivalent penumbra and field size measurement within 0.5 mm of conventional methods with the exception of 40 cm  ×  40 cm fields at a depth of 20 cm. New proposed methods are presented that make it possible to independently carry out set up and QA measurements on beam energy, flatness, symmetry and field size of an FFF beam without the need to reference to an equivalent flattened beam of the same energy. The methods proposed can also be used to carry out this QA for flattened beams, resulting in universal definitions and methods for MV beams. This is presented for beams produced by an Elekta linear accelerator, but is anticipated to also apply to other manufacturers’ beams.

Minimization of required model runs in the Random Mixing approach to inverse groundwater flow and transport modeling

NASA Astrophysics Data System (ADS)

Hoerning, Sebastian; Bardossy, Andras; du Plessis, Jaco

2017-04-01

Most geostatistical inverse groundwater flow and transport modelling approaches utilize a numerical solver to minimize the discrepancy between observed and simulated hydraulic heads and/or hydraulic concentration values. The optimization procedure often requires many model runs, which for complex models lead to long run times. Random Mixing is a promising new geostatistical technique for inverse modelling. The method is an extension of the gradual deformation approach. It works by finding a field which preserves the covariance structure and maintains observed hydraulic conductivities. This field is perturbed by mixing it with new fields that fulfill the homogeneous conditions. This mixing is expressed as an optimization problem which aims to minimize the difference between the observed and simulated hydraulic heads and/or concentration values. To preserve the spatial structure, the mixing weights must lie on the unit hyper-sphere. We present a modification to the Random Mixing algorithm which significantly reduces the number of model runs required. The approach involves taking n equally spaced points on the unit circle as weights for mixing conditional random fields. Each of these mixtures provides a solution to the forward model at the conditioning locations. For each of the locations the solutions are then interpolated around the circle to provide solutions for additional mixing weights at very low computational cost. The interpolated solutions are used to search for a mixture which maximally reduces the objective function. This is in contrast to other approaches which evaluate the objective function for the n mixtures and then interpolate the obtained values. Keeping the mixture on the unit circle makes it easy to generate equidistant sampling points in the space; however, this means that only two fields are mixed at a time. Once the optimal mixture for two fields has been found, they are combined to form the input to the next iteration of the algorithm. This process is repeated until a threshold in the objective function is met or insufficient changes are produced in successive iterations.

MetNH3: Metrology for ammonia in ambient air

NASA Astrophysics Data System (ADS)

Braban, Christine; Twigg, Marsailidh; Tang, Sim; Leuenberger, Daiana; Ferracci, Valerio; Martin, Nick; Pascale, Celine; Hieta, Tuomas; Pogany, Andrea; Persijn, Stefan; van Wijk, Janneke; Gerwig, Holger; Wirtze, Klaus; Tiebe, Carlo; Balslev-Harder, David; Niederhausen, Bernhardt

2015-04-01

Measuring ammonia in ambient air is a sensitive and priority issue due to its harmful effects on human health and ecosystems. The European Directive 2001/81/EC on 'National Emission Ceilings for Certain Atmospheric Pollutants (NEC)' regulates ammonia emissions in the member states. However, there is a lack of regulation to ensure reliable ammonia measurements namely in applicable analytical technology, maximum allowed uncertainty, quality assurance and quality control (QC/QA) procedures as well as in the infrastructure to attain metrological traceability. Validated ammonia measurement data of high quality from air monitoring networks are vitally important for identifying changes due to implementations of environment policies, for understanding where the uncertainties in current emission inventories are derived from and for providing independent verification of atmospheric model predictions. The new EURAMET project MetNH3 aims to develop improved reference gas mixtures by static and dynamic gravimetric generation methods, develop and characterise laser based optical spectrometric standards and establish the transfer from high-accuracy standards to field applicable methods. MetNH3started in June 2014 and in this presentation the first results from the metrological characterisation of a commercially available cavity ring-down spectrometer (CRDS) will be discussed. Also first tests and results from a new design, Controlled Atmosphere Test Facility (CATFAC), which is to be characterised and used to validate the performance of diffusive samplers, denuders and on-line instruments, will be reported. CAFTEC can be used to control test parameters such as ammonia concentration, relative humidity and wind speed. Outline plans for international laboratory and field intercomparisons in 2016 will be presented.

Characterising invasive non-native Rhododendron ponticum spectra signatures with spectroradiometry in the laboratory and field: Potential for remote mapping

NASA Astrophysics Data System (ADS)

Taylor, Sarah L.; Hill, Ross A.; Edwards, Colin

2013-07-01

Compared with traditional ground surveys, remote sensing has the potential to map the spatial extent of non-native invasive species rapidly and reliably. This paper assesses the potential of spectroradiometry to distinguish and characterise the status of invasive non-native rhododendron (Rhododendron ponticum). Absolute reflectance of target plant material was measured with an ASD Fieldspec Pro System under standardised laboratory conditions and in the field to characterise spectral signatures in the winter, during leaf-off conditions for woodland overstory, and in the summer when mature rhododendrons are flowering. A logistic regression model of absolute reflectance at key wavelengths (490, 550, 610, 1040 and 1490 nm) was used to determine the success of discriminating rhododendron from three other shrubby species likely to be encountered in woodlands during the winter. The logistic regression model was highly significant (p < 0.001), with 93.5% of 246 leaf sets correctly identified as rhododendron or non-rhododendron (i.e. cherry laurel (Prunus laurocerasus), holly (Ilex aquifolium), and beech (Fagus sylvatica)). Rescaling the data to emulate the spectral resolution of airborne and satellite acquired data decreased the total success rate of correctly identifying rhododendron by only 0.4%; although this error rate will likely increase for airborne or satellite data as a result of atmospheric attenuation and reduced spatial resolution. This demonstrates the potential to map bush presence using hyperspectral data and indicates the optimum spectral wavelengths required. Such information is critical to the development of successful strategic management plans to eradicate rhododendron (and the associated Phytophthora ramorum pathogen) effectively from a site.

Unveiling the thermal entanglement in a mixed-spin XXZ model with Dzyaloshinskii-Moriya interaction under a homogeneous magnetic field

NASA Astrophysics Data System (ADS)

Liu, Cheng-Cheng; Xu, Shuai; He, Juan; Ye, Liu

2015-10-01

We analytically investigate the thermal entanglement of three-mixed-spin (1/2, 1, 1/2) XXZ model with the DM interaction under an external magnetic field B. Two different cases are considered: one subsystem (1/2, 1/2) consists of two spin-1/2 fermions and the other subsystem (1/2, 1) contains a spin-1/2 fermion and a spin-1 boson. It is shown that the DM interaction parameter D, the external magnetic field strength B and coupling constant J have different effects on Fermi and mixed Fermi-Bose systems. All of the factors mentioned above can be utilized to control entanglement switch of any two particles in mixed spins model.

Electric-field-driven electron-transfer in mixed-valence molecules

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

Blair, Enrique P., E-mail: enrique-blair@baylor.edu; Corcelli, Steven A., E-mail: scorcell@nd.edu; Lent, Craig S., E-mail: lent@nd.edu

2016-07-07

Molecular quantum-dot cellular automata is a computing paradigm in which digital information is encoded by the charge configuration of a mixed-valence molecule. General-purpose computing can be achieved by arranging these compounds on a substrate and exploiting intermolecular Coulombic coupling. The operation of such a device relies on nonequilibrium electron transfer (ET), whereby the time-varying electric field of one molecule induces an ET event in a neighboring molecule. The magnitude of the electric fields can be quite large because of close spatial proximity, and the induced ET rate is a measure of the nonequilibrium response of the molecule. We calculate themore » electric-field-driven ET rate for a model mixed-valence compound. The mixed-valence molecule is regarded as a two-state electronic system coupled to a molecular vibrational mode, which is, in turn, coupled to a thermal environment. Both the electronic and vibrational degrees-of-freedom are treated quantum mechanically, and the dissipative vibrational-bath interaction is modeled with the Lindblad equation. This approach captures both tunneling and nonadiabatic dynamics. Relationships between microscopic molecular properties and the driven ET rate are explored for two time-dependent applied fields: an abruptly switched field and a linearly ramped field. In both cases, the driven ET rate is only weakly temperature dependent. When the model is applied using parameters appropriate to a specific mixed-valence molecule, diferrocenylacetylene, terahertz-range ET transfer rates are predicted.« less

The effects of the stellar wind and orbital motion on the jets of high-mass microquasars

NASA Astrophysics Data System (ADS)

Bosch-Ramon, V.; Barkov, M. V.

2016-05-01

Context. High-mass microquasar jets propagate under the effect of the wind from the companion star, and the orbital motion of the binary system. The stellar wind and the orbit may be dominant factors determining the jet properties beyond the binary scales. Aims: This is an analytical study, performed to characterise the effects of the stellar wind and the orbital motion on the jet properties. Methods: Accounting for the wind thrust transferred to the jet, we derive analytical estimates to characterise the jet evolution under the impact of the stellar wind. We include the Coriolis force effect, induced by orbital motion and enhanced by the wind's presence. Large-scale evolution of the jet is sketched, accounting for wind-to-jet thrust transfer, total energy conservation, and wind-jet flow mixing. Results: If the angle of the wind-induced jet bending is larger than its half-opening angle, the following is expected: (I) a strong recollimation shock; (II) bending against orbital motion, caused by Coriolis forces and enhanced by the wind presence; and (III) non-ballistic helical propagation further away. Even if disrupted, the jet can re-accelerate due to ambient pressure gradients, but wind entrainment can weaken this acceleration. On large scales, the opening angle of the helical structure is determined by the wind-jet thrust relation, and the wind-loaded jet flow can be rather slow. Conclusions: The impact of stellar winds on high-mass microquasar jets can yield non-ballistic helical jet trajectories, jet partial disruption and wind mixing, shocks, and possibly non-thermal emission. Among other observational diagnostics, such as radiation variability at any band, the radio morphology on milliarcsecond scales can be informative on the wind-jet interaction.

Maternal and child dietary patterns and their determinants in Nigeria.

PubMed

Nwaru, Bright I; Onyeka, Ifeoma N; Ndiokwelu, Chika; Esangbedo, Dorothy O; Ngwu, Elizabeth K; Okolo, Selina N

2015-07-01

Understanding the overall dietary patterns of a population is a key step in initiating appropriate nutritional interventions and policies. Studies characterising the dietary patterns of Nigerian mothers and children are lacking. Complete dietary data for 13,566 mothers and their 13,506 children were analysed from the 2008 Nigerian Demographic and Health Surveys (NDHS), a nationally representative sample, to identify the overall maternal and child dietary patterns and to study the potential determinants of such dietary patterns. The 2008 NDHS included questions that inquired about the food items mothers and their children had consumed during the 24 h preceding the day of the interview. Factor analysis with the principal component procedure was used to construct the dietary patterns, and multiple multilevel logistic regression was used to investigate the determinants of the dietary patterns. Four ('mixed', 'traditional', 'staple foods and milk products' and 'beverages') and five ('mixed', 'selective', 'beverages and candies', 'gruels, grains and semi-solids' and 'infant formula and cereals') distinct dietary patterns were obtained for the mothers and children, respectively. The key determinants of both maternal and child dietary patterns were month of interview, religion, region of residence, maternal education, maternal occupation, wealth index and maternal body mass index. Marital status additionally predicted maternal patterns, while sex of the child, number of siblings, child's age, maternal age and place of residence additionally determined the child's patterns. This study has identified four and five different dietary patterns to characterise the dietary habits of Nigerian mothers and their children, respectively, and has shown the important socio-economic/demographic factors influencing the dietary patterns, which can guide appropriate nutritional interventions among Nigerian mothers and children. © 2012 Blackwell Publishing Ltd.

Variation in cervical and breast cancer screening coverage in England: a cross-sectional analysis to characterise districts with atypical behaviour

PubMed Central

Massat, Nathalie J; Douglas, Elaine; Waller, Jo; Wardle, Jane; Duffy, Stephen W

2015-01-01

Objectives Reducing cancer screening inequalities in England is a major focus of the 2011 Department of Health cancer outcome strategy. Screening coverage requires regular monitoring in order to implement targeted interventions where coverage is low. This study aimed to characterise districts with atypical coverage levels for cervical or breast screening. Design Observational study of district-level coverage in the English Cervical and Breast screening programmes in 2012. Setting England, UK. Participants All English women invited to participate in the cervical (age group 25–49 and 50–64) and breast (age group 50–64) screening programmes. Outcomes Risk adjustment models for coverage were developed based on district-level characteristics. Funnel plots of adjusted coverage were constructed, and atypical districts examined by correlation analysis. Results Variability in coverage was primarily explained by population factors, whereas general practice characteristics had little independent effect. Deprivation and ethnicity other than white, Asian, black or mixed were independently associated with poorer coverage in both screening programmes, with ethnicity having the strongest effect; by comparison, the influence of Asian, black or mixed ethnic minority was limited. Deprivation, ethnicity and urbanisation largely accounted for the lower cervical screening coverage in London. However, for breast screening, being located in London remained a strong negative predictor. A subset of districts was identified as having atypical coverage across programmes. Correlates of deprivation in districts with relatively low adjusted coverage were substantially different from overall correlates of deprivation. Discussion These results inform the continuing drive to reduce avoidable cancer deaths in England, and encourage implementation of targeted interventions in communities residing in districts identified as having atypically low coverage. Sequential implementation to monitor the impact of local interventions would help accrue evidence on ‘what works’. PMID:26209119

Evaluation of a lime-mediated sewage sludge stabilisation process. Product characterisation and technological validation for its use in the cement industry.

PubMed

Rodríguez, N Husillos; Granados, R J; Blanco-Varela, M T; Cortina, J L; Martínez-Ramírez, S; Marsal, M; Guillem, M; Puig, J; Fos, C; Larrotcha, E; Flores, J

2012-03-01

This paper describes an industrial process for stabilising sewage sludge (SS) with lime and evaluates the viability of the stabilised product, denominated Neutral, as a raw material for the cement industry. Lime not only stabilised the sludge, raised the temperature of the mix to 80-100°C, furthering water evaporation, portlandite formation and the partial oxidation of the organic matter present in the sludge. Process mass and energy balances were determined. Neutral, a white powder consisting of portlandite (49.8%), calcite (16.6%), inorganic oxides (13.4%) and organic matter and moisture (20.2%), proved to be technologically apt for inclusion as a component in cement raw mixes. In this study, it was used instead of limestone in raw mixes clinkerised at 1400, 1450 and 1500°C. These raw meals exhibited greater reactivity at high temperatures than the limestone product and their calcination at 1500°C yielded clinker containing over 75% calcium silicates, the key phases in Portland clinker. Finally, the two types of raw meal (Neutral and limestone) were observed to exhibit similar mineralogy and crystal size and distribution. Published by Elsevier Ltd.

The generation and dissipation of solar and galactic magnetic fields.

NASA Technical Reports Server (NTRS)

Parker, E. N.

1973-01-01

Turbulent diffusion of magnetic field plays an essential role in the generation of magnetic field in most astrophysical bodies. Review of what can be proved and what can be believed about the turbulent diffusion of magnetic field. Observations indicate the dissipation of magnetic field at rates that can be understood only in terms of turbulent diffusion. Theory shows that a large-scale weak magnetic field diffuses in a turbulent flow in the same way that smoke is mixed throughout the fluid by the turbulence. The small-scale fields (produced from the large-scale field by the turbulence) are limited in their growth by reconnection of field lines at neutral points, so that the turbulent mixing of field and fluid is not halted by them. Altogether, it appears that the mixing of field and fluid in the observed turbulent motions in the sun and in the Galaxy is unavoidable. Turbulent diffusion causes decay of the general solar fields in a decade or so, and of the galactic field in 100 m.y. to 1 b.y. It is concluded that continual dynamo action is implied by the observed existence of the fields.

Comparison of Laboratory and Field Density of Asphalt Mixtures

DOT National Transportation Integrated Search

1991-01-01

The objective of this paper is to investigate the relationships between the measured density of the mixture obtained in the mix design, during quality control of the mixture (laboratory compaction of field produced mix), after initial compaction (cor...

Field trial of solvent-free emulsion in Oregon : final report.

DOT National Transportation Integrated Search

2003-03-01

This final report summarizes construction, laboratory and performance information gathered by ODOT personnel from a single field trial of solvent-free emulsion mix constructed in June 2001. The solvent-free emulsion mix presented several placement pr...

Unparticle-Higgs field mixing: Mikheyev-Smirnov-Wolfenstein resonances, seesaw mechanism, and spinodal instabilities

NASA Astrophysics Data System (ADS)

Boyanovsky, D.; Holman, R.; Hutasoit, Jimmy A.

2009-04-01

Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at “tree level” as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.

Systematic modelling and design evaluation of unperturbed tumour dynamics in xenografts.

PubMed

Parra Guillen, Zinnia P Patricia; Mangas Sanjuan, Victor; Garcia-Cremades, Maria; Troconiz, Inaki F; Mo, Gary; Pitou, Celine; Iversen, Philip W; Wallin, Johan E

2018-04-24

Xenograft mice are largely used to evaluate the efficacy of oncological drugs during preclinical phases of drug discovery and development. Mathematical models provide a useful tool to quantitatively characterise tumour growth dynamics and also optimise upcoming experiments. To the best of our knowledge, this is the first report where unperturbed growth of a large set of tumour cell lines (n=28) has been systematically analysed using the model proposed by Simeoni in the context of non-linear mixed effect (NLME). Exponential growth was identified as the governing mechanism in the majority of the cell lines, with constant rate values ranging from 0.0204 to 0.203 day -1 No common patterns could be observed across tumour types, highlighting the importance of combining information from different cell lines when evaluating drug activity. Overall, typical model parameters were precisely estimated using designs where tumour size measurements were taken every two days. Moreover, reducing the number of measurement to twice per week, or even once per week for cell lines with low growth rates, showed little impact on parameter precision. However, in order to accurately characterise parameter variability (i.e. relative standard errors below 50%), a sample size of at least 50 mice is needed. This work illustrates the feasibility to systematically apply NLME models to characterise tumour growth in drug discovery and development, and constitutes a valuable source of data to optimise experimental designs by providing an a priori sampling window and minimising the number of samples required. The American Society for Pharmacology and Experimental Therapeutics.

FragIdent--automatic identification and characterisation of cDNA-fragments.

PubMed

Seelow, Dominik; Goehler, Heike; Hoffmann, Katrin

2009-03-02

Many genetic studies and functional assays are based on cDNA fragments. After the generation of cDNA fragments from an mRNA sample, their content is at first unknown and must be assigned by sequencing reactions or hybridisation experiments. Even in characterised libraries, a considerable number of clones are wrongly annotated. Furthermore, mix-ups can happen in the laboratory. It is therefore essential to the relevance of experimental results to confirm or determine the identity of the employed cDNA fragments. However, the manual approach for the characterisation of these fragments using BLAST web interfaces is not suited for larger number of sequences and so far, no user-friendly software is publicly available. Here we present the development of FragIdent, an application for the automatic identification of open reading frames (ORFs) within cDNA-fragments. The software performs BLAST analyses to identify the genes represented by the sequences and suggests primers to complete the sequencing of the whole insert. Gene-specific information as well as the protein domains encoded by the cDNA fragment are retrieved from Internet-based databases and included in the output. The application features an intuitive graphical interface and is designed for researchers without any bioinformatics skills. It is suited for projects comprising up to several hundred different clones. We used FragIdent to identify 84 cDNA clones from a yeast two-hybrid experiment. Furthermore, we identified 131 protein domains within our analysed clones. The source code is freely available from our homepage at http://compbio.charite.de/genetik/FragIdent/.

Hyperspectral imaging to investigate the distribution of organic matter and iron down the soil profile

NASA Astrophysics Data System (ADS)

Hobley, Eleanor; Kriegs, Stefanie; Steffens, Markus

2017-04-01

Obtaining reliable and accurate data regarding the spatial distribution of different soil components is difficult due to issues related with sampling scale and resolution on the one hand and laboratory analysis on the other. When investigating the chemical composition of soil, studies frequently limit themselves to two dimensional characterisations, e.g. spatial variability near the surface or depth distribution down the profile, but rarely combine both approaches due to limitations to sampling and analytical capacities. Furthermore, when assessing depth distributions, samples are taken according to horizon or depth increments, resulting in a mixed sample across the sampling depth. Whilst this facilitates mean content estimation per depth increment and therefore reduces analytical costs, the sample information content with regards to heterogeneity within the profile is lost. Hyperspectral imaging can overcome these sampling limitations, yielding high resolution spectral data of down the soil profile, greatly enhancing the information content of the samples. This can then be used to augment horizontal spatial characterisation of a site, yielding three dimensional information into the distribution of spectral characteristics across a site and down the profile. Soil spectral characteristics are associated with specific chemical components of soil, such as soil organic matter or iron contents. By correlating the content of these soil components with their spectral behaviour, high resolution multi-dimensional analysis of soil chemical composition can be obtained. Here we present a hyperspectral approach to the characterisation of soil organic matter and iron down different soil profiles, outlining advantages and issues associated with the methodology.

Identification of opportunistic enteric parasites among immunocompetent patients with diarrhoea from Northern India and genetic characterisation of Cryptosporidium and Microsporidia.

PubMed

Ghoshal, U; Dey, A; Ranjan, P; Khanduja, S; Agarwal, V; Ghoshal, U C

2016-01-01

Enteric parasitic infestation is a major public health problem in developing countries. Parasites such as Cryptosporidium spp., Cyclospora spp., Cystoisospora spp. and Microsporidia may cause severe diarrhoea among immunocompromised patients. There is scanty data on their frequency among immunocompetent patients. Accordingly, we studied the frequency of enteric opportunistic parasites among immunocompetent patients with diarrhoea from northern India; we also performed genetic characterisation of Cryptosporidia and Microsporidia among them. Stool samples from 80 immunocompetent patients with diarrhoea, and 110 healthy controls were examined. Parasites were detected by direct microscopy, modified acid-fast (Kinyoun's) and modified trichrome stain. Polymerase chain reaction--restriction fragment length polymorphism was used for genetic characterisation of selected species such as Cryptosporidia and Microsporidia. Enteric parasites were detected in 16/80 (20%) patients (mean age 28.8±20 years, 45, 56% males) and in 2/110 (1.8%) healthy controls (P=0.00007). Parasites detected were Cryptosporidium spp. (8/16, 50.0%), Cystoisospora spp. (4/16, 25%), Microsporidia (1/16, 6.25%), Cyclospora spp. (1/16, 6.25%) and Giardia spp. (1/16, 6.25%). One patient had mixed infection with Cystoisospora spp. and Giardia spp. The species of Cryptosporidia and Microsporidia detected were Cryptosporidium hominis and Enterocytozoon bieneusi, respectively. Parasites were more often detected in younger patients (≤20 years of age) than in older. Most of the parasite infected patients presented with chronic diarrhoea. Opportunistic enteric parasitic infestation was more common among immunocompetent patients with diarrhoea than healthy subjects. Special staining as well as molecular methods are essential for appropriate diagnosis of these parasites.

Effect of the 6PBT stirrer eccentricity and off-bottom clearance on mixing of pseudoplastic fluid in a stirred tank

NASA Astrophysics Data System (ADS)

Luan, Deyu; Zhang, Shengfeng; Wei, Xing; Duan, Zhenya

The aim of this work is to investigate the effect of the shaft eccentricity on the flow field and mixing characteristics in a stirred tank with the novel stirrer composed of perturbed six-bent-bladed turbine (6PBT). The difference between coaxial and eccentric agitations is studied using computational fluid dynamics (CFD) simulations combined with standard k-ε turbulent equations, that offer a complete image of the three-dimensional flow field. In order to determine the capability of CFD to forecast the mixing process, particle image velocimetry (PIV), which provide an accurate representation of the time-averaged velocity, was used to measure fluid velocity. The test liquid used was 1.25% (wt) xanthan gum solution, a pseudoplastic fluid with a yield stress. The comparison of the experimental and simulated mean flow fields has demonstrated that calculations based on Reynolds-averaged Navier-Stokes equations are suitable for obtaining accurate results. The effects of the shaft eccentricity and the stirrer off-bottom distance on the flow model, mixing time and mixing efficiency were extensively analyzed. It is observed that the microstructure of the flow field has a significant effect on the tracer mixing process. The eccentric agitation can lead to the flow model change and the non-symmetric flow structure, which would possess an obvious superiority of mixing behavior. Moreover, the mixing rate and mixing efficiency are dependent on the shaft eccentricity and the stirrer off-bottom distance, showing the corresponding increase of the eccentricity with the off-bottom distance. The efficient mixing process of pseudoplastic fluid stirred by 6PBT impeller is obtained with the considerably low mixing energy per unit volume when the stirrer off-bottom distance, C, is T/3 and the eccentricity, e, is 0.2. The research results provide valuable references for the improvement of pseudoplastic fluid agitation technology.

Field management of asphalt concrete mixes.

DOT National Transportation Integrated Search

1988-01-01

Marshall properties were determined on mixes from three different contractors each producing a 1/2-in and a 3/4-in top-sized aggregate mix. From these data, statistical analyses were made to determine differences among contractors and between mix typ...

Continuous spin fields of mixed-symmetry type

NASA Astrophysics Data System (ADS)

Alkalaev, Konstantin; Grigoriev, Maxim

2018-03-01

We propose a description of continuous spin massless fields of mixed-symmetry type in Minkowski space at the level of equations of motion. It is based on the appropriately modified version of the constrained system originally used to describe massless bosonic fields of mixed-symmetry type. The description is shown to produce generalized versions of triplet, metric-like, and light-cone formulations. In particular, for scalar continuous spin fields we reproduce the Bekaert-Mourad formulation and the Schuster-Toro formulation. Because a continuous spin system inevitably involves infinite number of fields, specification of the allowed class of field configurations becomes a part of its definition. We show that the naive choice leads to an empty system and propose a suitable class resulting in the correct degrees of freedom. We also demonstrate that the gauge symmetries present in the formulation are all Stueckelberg-like so that the continuous spin system is not a genuine gauge theory.

Early detection of glaucoma by means of a novel 3D computer‐automated visual field test

PubMed Central

Nazemi, Paul P; Fink, Wolfgang; Sadun, Alfredo A; Francis, Brian; Minckler, Donald

2007-01-01

Purpose A recently devised 3D computer‐automated threshold Amsler grid test was used to identify early and distinctive defects in people with suspected glaucoma. Further, the location, shape and depth of these field defects were characterised. Finally, the visual fields were compared with those obtained by standard automated perimetry. Patients and methods Glaucoma suspects were defined as those having elevated intraocular pressure (>21 mm Hg) or cup‐to‐disc ratio of >0.5. 33 patients and 66 eyes with risk factors for glaucoma were examined. 15 patients and 23 eyes with no risk factors were tested as controls. The recently developed 3D computer‐automated threshold Amsler grid test was used. The test exhibits a grid on a computer screen at a preselected greyscale and angular resolution, and allows patients to trace those areas on the grid that are missing in their visual field using a touch screen. The 5‐minute test required that the patients repeatedly outline scotomas on a touch screen with varied displays of contrast while maintaining their gaze on a central fixation marker. A 3D depiction of the visual field defects was then obtained that was further characterised by the location, shape and depth of the scotomas. The exam was repeated three times per eye. The results were compared to Humphrey visual field tests (ie, achromatic standard or SITA standard 30‐2 or 24‐2). Results In this pilot study 79% of the eyes tested in the glaucoma‐suspect group repeatedly demonstrated visual field loss with the 3D perimetry. The 3D depictions of visual field loss associated with these risk factors were all characteristic of or compatible with glaucoma. 71% of the eyes demonstrated arcuate defects or a nasal step. Constricted visual fields were shown in 29% of the eyes. No visual field changes were detected in the control group. Conclusions The 3D computer‐automated threshold Amsler grid test may demonstrate visual field abnormalities characteristic of glaucoma in glaucoma suspects with normal achromatic Humphrey visual field testing. This test may be used as a screening tool for the early detection of glaucoma. PMID:17504855

Visualizing turbulent mixing of gases and particles

NASA Technical Reports Server (NTRS)

Ma, Kwan-Liu; Smith, Philip J.; Jain, Sandeep

1995-01-01

A physical model and interactive computer graphics techniques have been developed for the visualization of the basic physical process of stochastic dispersion and mixing from steady-state CFD calculations. The mixing of massless particles and inertial particles is visualized by transforming the vector field from a traditionally Eulerian reference frame into a Lagrangian reference frame. Groups of particles are traced through the vector field for the mean path as well as their statistical dispersion about the mean position by using added scalar information about the root mean square value of the vector field and its Lagrangian time scale. In this way, clouds of particles in a turbulent environment are traced, not just mean paths. In combustion simulations of many industrial processes, good mixing is required to achieve a sufficient degree of combustion efficiency. The ability to visualize this multiphase mixing can not only help identify poor mixing but also explain the mechanism for poor mixing. The information gained from the visualization can be used to improve the overall combustion efficiency in utility boilers or propulsion devices. We have used this technique to visualize steady-state simulations of the combustion performance in several furnace designs.

Citizen Formation for a New Millennium in Sweden--A Prognosis of Our Time

ERIC Educational Resources Information Center

Olson, Maria; Dahlstedt, Magnus

2014-01-01

The aim of this article is to forecast the present situation of citizenship formation in the field of Swedish education. In highlighting trends and tendencies in the educational assignment to provide for democratic citizenship in the first decade of the 21st century, which can be characterised as lacking collective visions for change, three…

Taking Development Seriously: Critique of the 2008 "JME" Special Issue on Moral Functioning

ERIC Educational Resources Information Center

Gibbs, John C.; Moshman, David; Berkowitz, Marvin W.; Basinger, Karen S.; Grime, Rebecca L.

2009-01-01

This essay comments on articles comprising a "Journal of Moral Education" Special Issue (September, 2008, 37[3]). The issue was intended to honour the 50th anniversary of Lawrence Kohlberg's doctoral dissertation and his subsequent impact on the field of moral development and education. The articles were characterised by the Issue editor (Don…

Wage Returns to University Disciplines in Greece: Are Greek Higher Education Degrees Trojan Horses?

ERIC Educational Resources Information Center

Livanos, Ilias; Pouliakas, Konstantinos

2011-01-01

This paper examines the wage returns to qualifications and academic disciplines in the Greek labour market. Exploring wage responsiveness across various degree subjects in Greece is interesting, as it is characterised by high levels of graduate unemployment, which vary considerably with the field of study, and relatively low levels of wage…

High-field specific heats of A15 V3Si and Nb3Sn

NASA Astrophysics Data System (ADS)

Stewart, G. R.; Brandt, B. L.

1984-04-01

In order to further understand the anomalous behavior of the specific heat of Nb3Sn in an 18-T magnetic field discovered by Stewart, Cort, and Webb

Rubber modified asphalt mix.

DOT National Transportation Integrated Search

1985-01-01

This report summarizes the design and field installation of an asphalt mix containing up to 3.0% closed cell rubber by weight of the mix. The performance is discussed as well as possible reasons for the early failure of the mix. Suggestions are made ...

The effect of different methods to compute N on estimates of mixing in stratified flows

NASA Astrophysics Data System (ADS)

Fringer, Oliver; Arthur, Robert; Venayagamoorthy, Subhas; Koseff, Jeffrey

2017-11-01

The background stratification is typically well defined in idealized numerical models of stratified flows, although it is more difficult to define in observations. This may have important ramifications for estimates of mixing which rely on knowledge of the background stratification against which turbulence must work to mix the density field. Using direct numerical simulation data of breaking internal waves on slopes, we demonstrate a discrepancy in ocean mixing estimates depending on the method in which the background stratification is computed. Two common methods are employed to calculate the buoyancy frequency N, namely a three-dimensionally resorted density field (often used in numerical models) and a locally-resorted vertical density profile (often used in the field). We show that how N is calculated has a significant effect on the flux Richardson number Rf, which is often used to parameterize turbulent mixing, and the turbulence activity number Gi, which leads to errors when estimating the mixing efficiency using Gi-based parameterizations. Supported by ONR Grant N00014-08-1-0904 and LLNL Contract DE-AC52-07NA27344.

DIVERSE MODELS FOR SOLVING CONTRASTING OUTFALL PROBLEMS

EPA Science Inventory

Mixing zone initial dilution and far-field models are useful for assuring that water quality criteria will be met when specific outfall discharge criteria are applied. Presented here is a selective review of mixing zone initial dilution models and relatively simple far-field tran...

The subcontinental mantle beneath southern New Zealand, characterised by helium isotopes in intraplate basalts and gas-rich springs

NASA Astrophysics Data System (ADS)

Hoke, L.; Poreda, R.; Reay, A.; Weaver, S. D.

2000-07-01

New helium isotope data measured in Cenozoic intraplate basalts and their mantle xenoliths are compared with present-day mantle helium emission on a regional scale from thermal and nonthermal gas discharges on the South Island of New Zealand and the offshore Chatham Islands. Cenozoic intraplate basaltic volcanism in southern New Zealand has ocean island basalt affinities but is restricted to continental areas and absent from adjacent Pacific oceanic crust. Its distribution is diffuse and widespread, it is of intermittent timing and characterised by low magma volumes. Most of the 3He/ 4He ratios measured in fluid inclusions in mantle xenocrysts and basalt phenocrysts such as olivine, garnet, and amphibole fall within the narrow range of 8.5 ± 1.5 Ra (Ra is the atmospheric 3He/ 4He ratio) with a maximum value of 11.5 Ra. This range is characteristic of the relatively homogeneous and degassed upper MORB-mantle helium reservoir. No helium isotope ratios typical of the lower less degassed mantle (>12 Ra), such as exemplified by the modern hot-spot region of Hawaii (with up to 32 Ra) were measured. Helium isotope ratios of less than 8 Ra are interpreted in terms of dilution of upper mantle helium with a radiogenic component, due to either age of crystallisation or small-scale mantle heterogeneities caused by mixing of crustal material into the upper mantle. The crude correlation between age of samples and helium isotopes with generally lower R/Ra values in mantle xenoliths compared with host rock phenocrysts and the in general depleted Nd and Sr isotope ratios and the light rare earth element enrichment of the basalts supports derivation of melts as small melt fractions from a depleted upper mantle, with posteruptive ingrowth of radiogenic helium as a function of lithospheric age. In comparison, the regional helium isotope survey of thermal and nonthermal gas discharges of the South Island of New Zealand shows that mantle 3He anomalies in general do not show an obvious relationship with either age or proximity to the Cenozoic intraplate volcanic centres or with major faults. In general, areas characterised by mantle 3He emission are interpreted to define those regions beneath which mantle melting and basalt magma addition to the crust are recent. The strongest mantle 3He anomaly (equivalent to >80% mantle helium component) is centred over southern Dunedin, measured in magmatic CO 2-rich mineral water springs issuing from crystalline basement rocks which outcrop at the southern extent of Miocene intraplate basaltic volcanism which ceased 9 Ma ago. This mantle helium anomaly overlaps with an area characterised by elevated surface high heat flow, compatible with a long-lived mantle melt/heat input into the crust. In comparison Banks Peninsula, another Miocene intraplate basaltic centre, is characterised by relatively low surface heat flow and a small mantle helium contribution measured in a nitrogen-rich spring. Here the thermal transient induced by the magmatic event has either dissipated or has not reached the surface. In the former case one might be dealing with storage and mixing of magmatic and crustal gases at shallow crustal levels and in the latter with active to recent mantle-melt degassing at depth. Along the most actively deforming part of the plate boundary zone, the transpressional Alpine Fault and Marlborough fault systems, mantle helium is present in gas-rich springs in all those areas underlain by actively subducting oceanic crust (the Australian plate in the south and Pacific plate in the north), whereas the central part of the Alpine transpressional fault is characterised by pure crustal radiogenic helium. Areas where the mantle helium component is negligible are restricted to the centre part of the South Island, extending along its length from Southland to northern Canterbury and Murchison. These areas are interpreted to delineate the extent of thicker and colder lithosphere compared to all other areas where mantle helium release from partial mantle melts at depth is recent to active being added to the lower lithosphere and/or lower crust. Areas characterised by mantle helium anomalies are equated with areas of thermal mantle anomalies, i.e., localised mantle heterogeneities such as upwelling less dense silicate melts in the upper asthenospheric mantle.

Compatible-strain mixed finite element methods for incompressible nonlinear elasticity

NASA Astrophysics Data System (ADS)

Faghih Shojaei, Mostafa; Yavari, Arash

2018-05-01

We introduce a new family of mixed finite elements for incompressible nonlinear elasticity - compatible-strain mixed finite element methods (CSFEMs). Based on a Hu-Washizu-type functional, we write a four-field mixed formulation with the displacement, the displacement gradient, the first Piola-Kirchhoff stress, and a pressure-like field as the four independent unknowns. Using the Hilbert complexes of nonlinear elasticity, which describe the kinematics and the kinetics of motion, we identify the solution spaces of the independent unknown fields. In particular, we define the displacement in H1, the displacement gradient in H (curl), the stress in H (div), and the pressure field in L2. The test spaces of the mixed formulations are chosen to be the same as the corresponding solution spaces. Next, in a conforming setting, we approximate the solution and the test spaces with some piecewise polynomial subspaces of them. Among these approximation spaces are the tensorial analogues of the Nédélec and Raviart-Thomas finite element spaces of vector fields. This approach results in compatible-strain mixed finite element methods that satisfy both the Hadamard compatibility condition and the continuity of traction at the discrete level independently of the refinement level of the mesh. By considering several numerical examples, we demonstrate that CSFEMs have a good performance for bending problems and for bodies with complex geometries. CSFEMs are capable of capturing very large strains and accurately approximating stress and pressure fields. Using CSFEMs, we do not observe any numerical artifacts, e.g., checkerboarding of pressure, hourglass instability, or locking in our numerical examples. Moreover, CSFEMs provide an efficient framework for modeling heterogeneous solids.

Characterisation of Two Oxidosqualene Cyclases Responsible for Triterpenoid Biosynthesis in Ilex asprella

PubMed Central

Zheng, Xiasheng; Luo, Xiuxiu; Ye, Guobing; Chen, Ye; Ji, Xiaoyu; Wen, Lingling; Xu, Yaping; Xu, Hui; Zhan, Ruoting; Chen, Weiwen

2015-01-01

Ilex asprella, a plant widely used as a folk herbal drug in southern China, produces and stores a large amount of triterpenoid saponins, most of which are of the α-amyrin type. In this study, two oxidosqualene cyclase (OSC) cDNAs, IaAS1 and IaAS2, were cloned from the I. asprella root. Functional characterisation was performed by heterologous expression in the yeast Saccharomyces cerevisiae. Analysis of the resulting products by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) showed that both genes encode a mixed amyrin synthase, producing α-amyrin and β-amyrin at different ratios. IaAS1, which mainly produces α-amyrin, is the second triterpene synthase so far identified in which the level of α-amyrin produced is ≥80% of total amyrin production. By contrast, IaAS2 mainly synthesises β-amyrin, with a yield of 95%. Gene expression patterns of these two amyrin synthases in roots and leaves of I. asprella were found to be consistent with the content patterns of total saponins. Finally, phylogenetic analysis and multiple sequence alignment of the two amyrin synthases against several known OSCs from other plants were conducted to further elucidate their evolutionary relationship. PMID:25664861

Chemical characterisation of spent rechargeable batteries.

PubMed

Vassura, Ivano; Morselli, Luciano; Bernardi, Elena; Passarini, Fabrizio

2009-08-01

A chemical characterisation of used batteries can give useful information to implement suitable recycling techniques and to estimate the flux of the different materials recovered. This work is aimed to provide quantitative data about the composition of mixed batteries (in particular, Ni-Cd, Ni-MH and Li-ion batteries) collected in a Northern Italian town in order to evaluate the feasibility of recovery processes applied to the selected material. The higher concentration of metals in the <3mm fraction suggested that significant quantities of valuable elements could be recovered: in particular, for a kg of the <3mm fraction deriving from disassembled batteries, about 390 g Ni and 330 g Cd can be recovered from Ni-Cd, 630 g Ni, 80 g Co from Ni-MH and 250 g Co, 110 g Ni, 120 g Cu from Li-ion ones. Leaching tests applied to the same fractions, to assess possible contaminant releases, resulted in low metal content in aqueous solutions (except for Al and Fe, the concentrations of all metals remained below 1mg/kg). Even so, great care is required in all handling activities due to the high pH values of leachate solutions.

Rhenium tetrazolato complexes coordinated to thioalkyl-functionalised phenanthroline ligands: synthesis, photophysical characterisation, and incubation in live HeLa cells.

PubMed

Werrett, Melissa V; Wright, Phillip J; Simpson, Peter V; Raiteri, Paolo; Skelton, Brian W; Stagni, Stefano; Buckley, Alysia G; Rigby, Paul J; Massi, Massimiliano

2015-12-21

Three new complexes of formulation fac-[Re(CO)3(diim)L], where diim is either 1,10-phenanthroline or 1,10-phenanthroline functionalised at position 5 by a thioalkyl chain, and L is either a chloro or aryltetrazolato ancillary ligand, were synthesised and photophysically characterised. The complexes exhibit phosphorescent emission with maxima around 600 nm, originating from triplet metal-to-ligand charge transfer states with partially mixed ligand-to-ligand charge transfer character. The emission is relatively long-lived, within the 200-400 ns range, and with quantum yields of 2-4%. The complexes were trialed as cellular markers in live HeLa cells, along with two previously reported rhenium tetrazolato complexes bound to unsubstituted 1,10-phenanthroline. All five complexes exhibit good cellular uptake and non-specific perinuclear localisation. Upon excitation at 405 nm, the emission from the rhenium complexes could be clearly distinguished from autofluorescence, as demonstrated by spectral detection within the live cells. Four of the complexes did not appear to be toxic, however prolonged excitation could result in membrane blebbing. No major sign of photobleaching was detected upon multiple imaging on the same cell sample.

A New Theory of Mix in Omega Capsule Implosions

NASA Astrophysics Data System (ADS)

Knoll, Dana; Chacon, Luis; Rauenzahn, Rick; Simakov, Andrei; Taitano, William; Welser-Sherrill, Leslie

2014-10-01

We put forth a new mix model that relies on the development of a charge-separation electrostatic double-layer at the fuel-pusher interface early in the implosion of an Omega plastic ablator capsule. The model predicts a sizable pusher mix (several atom %) into the fuel. The expected magnitude of the double-layer field is consistent with recent radial electric field measurements in Omega plastic ablator implosions. Our theory relies on two distinct physics mechanisms. First, and prior to shock breakout, the formation of a double layer at the fuel-pusher interface due to fast preheat-driven ionization. The double-layer electric field structure accelerates pusher ions fairly deep into the fuel. Second, after the double-layer mix has occurred, the inward-directed fuel velocity and temperature gradients behind the converging shock transports these pusher ions inward. We first discuss the foundations of this new mix theory. Next, we discuss our interpretation of the radial electric field measurements on Omega implosions. Then we discuss the second mechanism that is responsible for transporting the pusher material, already mixed via the double-layer deep into the fuel, on the shock convergence time scale. Finally we make a connection to recent mix motivated experimental data on. This work conducted under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory, managed by LANS, LLC under Contract DE-AC52-06NA25396.

Designing a ruggedisation lab to characterise materials for harsh environments.

PubMed

Frazzette, Nicholas; Jethva, Janak; Mehta, Khanjan; Stapleton, Joshua J; Randall, Clive

Designing products for use in developing countries presents a unique set of challenges including harsh operating environments, costly repairs and maintenance, and users with varying degrees of education and device familiarity. For products to be robust, adaptable and durable, they need to be ruggedised for environmental factors such as high temperature and humidity as well as different operational conditions such as shock and chemical exposure. The product characterisation and ruggedisation processes require specific expertise and resources that are seldom available outside of large corporations and elite national research labs. There is no standardised process since product needs strongly depend on the context and user base, making it particularly onerous for underfunded start-ups and academic groups. Standardised protocols that identify essential lab testing regimens for specific contexts and user groups can complement field-testing and accelerate the product development process while reducing costs. This article synthesises current methods and strategies for product testing employed by large corporations as well as defence-related entities. A technological and organisational framework for a service-for-fee product characterisation and ruggedisation lab that reduces costs and shortens the timespan from product invention to commercial launch in harsh settings is presented.

Effect of image scaling and segmentation in digital rock characterisation

NASA Astrophysics Data System (ADS)

Jones, B. D.; Feng, Y. T.

2016-04-01

Digital material characterisation from microstructural geometry is an emerging field in computer simulation. For permeability characterisation, a variety of studies exist where the lattice Boltzmann method (LBM) has been used in conjunction with computed tomography (CT) imaging to simulate fluid flow through microscopic rock pores. While these previous works show that the technique is applicable, the use of binary image segmentation and the bounceback boundary condition results in a loss of grain surface definition when the modelled geometry is compared to the original CT image. We apply the immersed moving boundary (IMB) condition of Noble and Torczynski as a partial bounceback boundary condition which may be used to better represent the geometric definition provided by a CT image. The IMB condition is validated against published work on idealised porous geometries in both 2D and 3D. Following this, greyscale image segmentation is applied to a CT image of Diemelstadt sandstone. By varying the mapping of CT voxel densities to lattice sites, it is shown that binary image segmentation may underestimate the true permeability of the sample. A CUDA-C-based code, LBM-C, was developed specifically for this work and leverages GPU hardware in order to carry out computations.

Global tidal phasing potential

NASA Astrophysics Data System (ADS)

Neill, S. P.; Cooper, M. M.; Lewis, M. J.

2016-02-01

Tidal energy is characterised by intermittency over a range of timescales, from semi-diurnal and lunar periods through to annual and decadal. Therefore, the electricity that can be generated by the tides will be characterised by similar scales of intermittency. However, with knowledge of the phase relationship between sites, it may be possible to reduce intermittency, particularly at the semi-diurnal timescale, by aggregating the electricity generated by discrete regions suitable for the conversion of tidal energy into electricity. In this study, we make use of a global tidal atlas (FES2012) to make a preliminary assessment of regions of the globe where it could be possible to combine the electricity generated at a number of discrete sites to provide firmer power to regional electricity networks. In contrast to the northwest European shelf, where the high tidal stream sites tend to either be in phase or 180 out-of-phase with one-another, we find numerous regions around the globe with potential for regional tidal phasing. However, development of higher resolution regional models, or the examination of field data, are required to fully characterise the phasing potential of these regions. In addition, technical and economical constraints on the resource should be considered such as water depth and distance to shore.

The importance of mineralogical input into geometallurgy programs

USGS Publications Warehouse

Hoal, K. Olson; Woodhead, J.D.; Smith, Kathleen S.

2013-01-01

Mineralogy is the link between ore formation and ore extraction. It is the most fundamental component of geomet programs, and the most important aspect of a life-of-project approach to mineral resource projects. Understanding orebodies is achieved by understanding the mineralogy and texture of the materials, throughout the process, because minerals hold the information required to unlock the value they contain. Geomet mineralogy programs absolutely require the appropriate expertise and at least three steps of mineral characterisation prior to using semi-automated or other methods: field examination, thorough core logging, and optical microscopy. Economic geological inputs for orebody characterisation are necessary for orebody understanding, and are exemplified by current research in the Zambian Copperbelt, where revised sequence stratigraphy and understanding of alteration, metasomatism and metamorphism can be used to predict topical issues at mine sites. Environmental inputs for sustainability characterisation are demonstrated by recent work on tailings from the Leadville, Colorado, USA area, including linking mineralogy to water quality issues. Risk assessments need to take into account the technical uncertainties around geological variability and mineral extractability, and mineralogy is the only metric that can be used to make this risk contribution.

Dendrimers

NASA Astrophysics Data System (ADS)

Bryant, L. Henry; Bulte, Jeff W. M.

Dendrimers have received an enormous amount of attention in the last ten years and several recent review articles have appeared in the literature that address their potential applications [1-3]. Stoddart et al [1] have stated that: "We are now approaching a time when the study of dendriniers bec omes inextricably linked with many other fields, leaving the comprehensive reviewer of the subject a near-impossible task to fulfil". On that note, this review provides a brief introduction to the chemical principles of dendrimers by highlighting main synthetic strategies and methods for characterisation. p]Dendrimers containing heteroatoms will not be reviewed per se since these have recently been reviewed [4]. The major thrust of this review is the potential applications of dendrimers in such areas as boron neutron capture therapy, as contrast agents in magnetic resonance imaging, as vaccines, as cellular transfection agents and as bioconjugate dendrimers, i.e., in-vitro immunoassays for antigens. The outline used in this review proved to be effective in classifying most published papers about dendrimers, but it must be kept in mind that some articles not only transcended two different classifications, such as synthesis and characterisation, but several classifications such as synthesis, characterisation and at least one potential application covered in this review.

Advances in research on structural characterisation of agricultural products using atomic force microscopy.

PubMed

Liu, Dongli; Cheng, Fang

2011-03-30

Atomic force microscopy (AFM) has many unique features compared with other conventional microscopies, such as high magnification with high resolution, minimal sample preparation, acquiring 2D and 3D images at the same time, observing ongoing processes directly, the possibility of manipulating macromolecules, etc. As a nanotechnology tool, AFM has been used to investigate the nanostructure of materials in many fields. This mini-review focuses mainly on its latest application to characterise the macromolecular nanostructure and surface topography of agricultural products. First the fundamentals of AFM are briefly explained. Then the macromolecular nanostructure information on agricultural products from AFM images is introduced by exploring the structure-function relationship in three aspects: agricultural product processing, agricultural product ripening and storage, and genetic and environmental factors. The surface topography characterisation of agricultural products using AFM is also discussed. The results reveal that AFM could be a powerful nanotechnology tool to acquire a deeper understanding of the mechanisms of structure and quality variations of agricultural products, which could be instructive in improving processing and storage technologies, and AFM is also helpful to reveal the essential nature of a product at nanoscale. Copyright © 2011 Society of Chemical Industry.

Simple, quick and cost-efficient: A universal RT-PCR and sequencing strategy for genomic characterisation of foot-and-mouth disease viruses.

PubMed

Dill, V; Beer, M; Hoffmann, B

2017-08-01

Foot-and-mouth disease (FMD) is a major contributor to poverty and food insecurity in Africa and Asia, and it is one of the biggest threats to agriculture in highly developed countries. As FMD is extremely contagious, strategies for its prevention, early detection, and the immediate characterisation of outbreak strains are of great importance. The generation of whole-genome sequences enables phylogenetic characterisation, the epidemiological tracing of virus transmission pathways and is supportive in disease control strategies. This study describes the development and validation of a rapid, universal and cost-efficient RT-PCR system to generate genome sequences of FMDV, reaching from the IRES to the end of the open reading frame. The method was evaluated using twelve different virus strains covering all seven serotypes of FMDV. Additionally, samples from experimentally infected animals were tested to mimic diagnostic field samples. All primer pairs showed a robust amplification with a high sensitivity for all serotypes. In summary, the described assay is suitable for the generation of FMDV sequences from all serotypes to allow immediate phylogenetic analysis, detailed genotyping and molecular epidemiology. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation.

PubMed

Casado-Coterillo, Clara; Del Mar López-Guerrero, María; Irabien, Angel

2014-06-19

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials.

Electrochemical characterisation of air electrodes based on La 0.6Sr 0.4CoO 3 and carbon nanotubes

NASA Astrophysics Data System (ADS)

Thiele, Doreen; Züttel, Andreas

The efficiency of fuel cells suffers from the high activation polarisation at the cathode, where the oxygen reduction reaction takes place. In order to improve the performance, air electrodes composed of carbon nanotubes (CNTs) and the perovskite La 0.6Sr 0.4CoO 3 are produced by two different methods and investigated. In the first method CNTs are directly grown on the perovskite and in the second method CNTs and perovskite are combined by ultrasonic mixing. Their catalytic activity towards oxygen reduction in alkaline solution is evaluated by polarisation curves and electrochemical impedance spectroscopy. Best performance shows the electrode composed of 25 wt% CNTs, 55 wt% La 0.6Sr 0.4CoO 3 and 20 wt% PTFE as binder, produced by ultrasonic mixing. The Nyquist plot of this electrode displays two potential-dependent semi-circles, accounting for processes on the catalyst surface and for processes depending on the morphology of the electrode.

New generation mix-designs : laboratory-field testing and modifications to Texas HMA mix-design procedures.

DOT National Transportation Integrated Search

2012-10-01

Recent changes to the Texas hot mix asphalt (HMA) mix-design procedures such as adaption of the higher-stiffer PG asphalt-binder grades and the Hamburg test have ensured that the mixes that are routinely used on the Texas highways are not prone to ru...

Laboratory study - laboratory testing of bridge deck mixes

DOT National Transportation Integrated Search

2003-03-01

The purpose of this investigation was to develop bridge deck mixes that will improve field performance and minimize cracking potential compared to MoDOT's current (B-2) bridge deck mix design. The mix designs developed in this study were tested and c...

Installation report : rubber modified asphalt mix.

DOT National Transportation Integrated Search

1983-01-01

This report describes the design of an asphalt mix containing up to 3.0% closed cell waste rubber and a field installation of the mix. The Marshall design procedure was used to determine the asphalt content for the mix containing 3.0% rubber as well ...

Mixing high-viscosity fluids via acoustically driven bubbles

NASA Astrophysics Data System (ADS)

Orbay, Sinem; Ozcelik, Adem; Lata, James; Kaynak, Murat; Wu, Mengxi; Huang, Tony Jun

2017-01-01

We present an acoustofluidic micromixer which can perform rapid and homogeneous mixing of highly viscous fluids in the presence of an acoustic field. In this device, two high-viscosity polyethylene glycol (PEG) solutions were co-injected into a three-inlet PDMS microchannel with the center inlet containing a constant stream of nitrogen flow which forms bubbles in the device. When these bubbles were excited by an acoustic field generated via a piezoelectric transducer, the two solutions mixed homogenously due to the combination of acoustic streaming, droplet ejection, and bubble eruption effects. The mixing efficiency of this acoustofluidic device was evaluated using PEG-700 solutions which are ~106 times more viscous than deionized (DI) water. Our results indicate homogenous mixing of the PEG-700 solutions with a ~0.93 mixing index. The acoustofluidic micromixer is compact, inexpensive, easy to operate, and has the capacity to mix highly viscous fluids within 50 ms.

Superstring-inspired SO(10) GUT model with intermediate scale

NASA Astrophysics Data System (ADS)

Sasaki, Ken

1987-12-01

A new mechanism is proposed for the mixing of Weinberg-Salam Higgs fields in superstring-inspired SO(10) models with no SO(10) singlet fields. The higher-dimensional terms in the superpotential can generate both Higgs field mixing and a small mass for the physical neutrino. I would like to thank Professor C. Iso for hospitality extended to me at the Tokyo Institute of Technology.

Characterisation of capacitive field-effect sensors with a nanocrystalline-diamond film as transducer material for multi-parameter sensing.

PubMed

Abouzar, M H; Poghossian, A; Razavi, A; Williams, O A; Bijnens, N; Wagner, P; Schöning, M J

2009-01-01

The feasibility of a capacitive field-effect EDIS (electrolyte-diamond-insulator-semiconductor) platform for multi-parameter sensing is demonstrated by realising EDIS sensors with an O-terminated nanocrystalline-diamond (NCD) film as transducer material for the detection of pH and penicillin concentration as well as for the label-free electrical monitoring of adsorption and binding of charged macromolecules, like polyelectrolytes. The NCD films were grown on p-Si-SiO(2) substrates by microwave plasma-enhanced chemical vapour deposition. To obtain O-terminated surfaces, the NCD films were treated in an oxidising medium. The NCD-based field-effect sensors have been characterised by means of constant-capacitance method. The average pH sensitivity of the O-terminated NCD film was 40 mV/pH. A low detection limit of 5 microM and a high penicillin G sensitivity of 65-70 mV/decade has been obtained for an EDIS penicillin biosensor with the adsorptively immobilised enzyme penicillinase. Alternating potential changes, having tendency to decrease with increasing the number of adsorbed polyelectrolyte layers, have been observed after the layer-by-layer deposition of polyelectrolyte multilayers, using positively charged PAH (poly (allylamine hydrochloride)) and a negatively charged PSS (poly (sodium 4-styrene sulfonate)) as a model system. The response mechanism of the developed EDIS sensors is discussed.

Wind tunnel measurements for dispersion modelling of vehicle wakes

NASA Astrophysics Data System (ADS)

Carpentieri, Matteo; Kumar, Prashant; Robins, Alan

2012-12-01

Wind tunnel measurements downwind of reduced scale car models have been made to study the wake regions in detail, test the usefulness of existing vehicle wake models, and draw key information needed for dispersion modelling in vehicle wakes. The experiments simulated a car moving in still air. This is achieved by (i) the experimental characterisation of the flow, turbulence and concentration fields in both the near and far wake regions, (ii) the preliminary assessment of existing wake models using the experimental database, and (iii) the comparison of previous field measurements in the wake of a real diesel car with the wind tunnel measurements. The experiments highlighted very large gradients of velocities and concentrations existing, in particular, in the near-wake. Of course, the measured fields are strongly dependent on the geometry of the modelled vehicle and a generalisation for other vehicles may prove to be difficult. The methodology applied in the present study, although improvable, could constitute a first step towards the development of mathematical parameterisations. Experimental results were also compared with the estimates from two wake models. It was found that they can adequately describe the far-wake of a vehicle in terms of velocities, but a better characterisation in terms of turbulence and pollutant dispersion is needed. Parameterised models able to predict velocity and concentrations with fine enough details at the near-wake scale do not exist.

The public health significance of latrines discharging to groundwater used for drinking.

PubMed

Ravenscroft, P; Mahmud, Z H; Islam, M Shafiqul; Hossain, A K M Z; Zahid, A; Saha, G C; Zulfiquar Ali, A H M; Islam, Khairul; Cairncross, S; Clemens, J D; Islam, M Sirajul

2017-11-01

Faecal contamination of groundwater from pit latrines is widely perceived as a major threat to the safety of drinking water for several billion people in rural and peri-urban areas worldwide. On the floodplains of the Ganges-Brahmaputra-Meghna delta in Bangladesh, we constructed latrines and monitored piezometer nests monthly for two years. We detected faecal coliforms (FC) in 3.3-23.3% of samples at four sites. We differentiate a near-field, characterised by high concentrations and frequent, persistent and contiguous contamination in all directions, and a far-field characterised by rare, impersistent, discontinuous low-level detections in variable directions. Far-field FC concentrations at four sites exceeded 0 and 10 cfu/100 ml in 2.4-9.6% and 0.2-2.3% of sampling events respectively. The lesser contamination of in-situ groundwater compared to water at the point-of-collection from domestic wells, which itself is less contaminated than at the point-of-consumption, demonstrates the importance of recontamination in the well-pump system. We present a conceptual model comprising four sub-pathways: the latrine-aquifer interface (near-field); groundwater flowing from latrine to well (far-field); the well-pump system; and post-collection handling and storage. Applying a hypothetical dose-response model suggests that 1-2% of the diarrhoeal disease burden from drinking water is derived from the aquifer, 29% from the well-pump system, and 70% from post-collection handling. The important implications are (i) that leakage from pit latrines is a minor contributor to faecal contamination of drinking water in alluvial-deltaic terrains; (ii) fears of increased groundwater pollution should not constrain expanding latrine coverage, and (iii) that more attention should be given to reducing contamination around the well-head. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mixed-order phase transition in a colloidal crystal.

PubMed

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-05

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field [Formula: see text] At the transition field [Formula: see text], the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length [Formula: see text] Mean-field critical exponents are predicted, since the upper critical dimension of the transition is [Formula: see text] Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Mixed-order phase transition in a colloidal crystal

NASA Astrophysics Data System (ADS)

Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

2017-12-01

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid-solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2-Hs2|-1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

Effect of gas mixing on physical properties of warm collisional helicon plasmas

NASA Astrophysics Data System (ADS)

Kabir, M.; Niknam, A. R.

2017-10-01

The effect of inert gas mixing on the physical properties of a helicon plasma source with a Nagoya type III antenna is analytically investigated by taking into account the thermal and collisional effects. The dielectric permittivity tensor of this mixed gas plasma is obtained by using the Bhatnagar-Gross- Krook kinetic theory. Considering the dielectric tensor of mixed gas plasma and solving the electromagnetic field equations, the profiles of electromagnetic fields and plasma resistance are plotted and discussed. The results show that the plasma resistance peaks decrease with increasing Xe fraction in Ar-Xe plasma, and increase with the He fraction in Ar-He plasma. It is also shown that by increasing the xenon filling fraction, the electromagnetic field amplitudes are lowered, and by increasing the helium filling fraction, they are increased.

Flow Field Analysis of Micromixer Powered by Ciliary Motion of Vorticella

NASA Astrophysics Data System (ADS)

Hayasaka, Yo; Nagai, Moeto; Matsumoto, Nobuyoshi; Kawashima, Takahiro; Shibata, Takayuki

We demonstrate the observation of a flow field generated by ciliary motion of Vorticella in a microfluidic chamber. We applied the property that Vorticella vibrates its cilia and create a flow field to a micromixer. The stability and mixing performance of Vorticella were measured by PIV (Particle Image Velocimetry). One cell of Vorticella mixed the half area of the microchamber. We revealed that the flow field of a single cell in a chamber was more stable than that of multiple cells.

Evaluation of field-produced hot mix asphalt (HMA) mixtures with fractionated recycled asphalt pavement (RAP) : 2007 Illinois tollway field mix trials.

DOT National Transportation Integrated Search

2008-10-01

To test the fractionated recycled asphalt pavement (FRAP) materials, the Illinois Tollway, working through its : contractors and consultants, developed and conducted a project on the applicability and feasibility of using : increased RAP contents thr...

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO2 with applications in food and feed.

PubMed

Omar, J; Boix, A; Kerckhove, G; von Holst, C

2016-12-01

Titanium dioxide (TiO 2 ) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO 2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i.e., to break up agglomerates and/or aggregates of the material. The results showed that high amplitudes (60%) favoured a better dispersion and time was fixed in mid-values (5 min). In a next step, key factors of asymmetric flow field-flow fraction (AF4), namely cross-flow (CF), detector flow (DF), exponential decay of the cross-flow (CF exp ) and focus time (Ft), were studied through experimental design. Firstly, a full-factorial design was employed to establish the statistically significant factors (p < 0.05). Then, the information obtained from the full-factorial design was utilised by applying a central composite design to obtain the following optimum conditions of the system: CF, 1.6 ml min -1 ; DF, 0.4 ml min -1 ; Ft, 5 min; and CF exp , 0.6. Once the optimum conditions were obtained, the stability of the dispersed sample was measured for 24 h by analysing 10 replicates with AF4 in order to assess the performance of the optimised dispersion protocol. Finally, the recovery of the optimised method, particle shape and particle size distribution were estimated.

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO2 with applications in food and feed

PubMed Central

Omar, J.; Boix, A.; Kerckhove, G.; von Holst, C.

2016-01-01

ABSTRACT Titanium dioxide (TiO2) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i.e., to break up agglomerates and/or aggregates of the material. The results showed that high amplitudes (60%) favoured a better dispersion and time was fixed in mid-values (5 min). In a next step, key factors of asymmetric flow field-flow fraction (AF4), namely cross-flow (CF), detector flow (DF), exponential decay of the cross-flow (CFexp) and focus time (Ft), were studied through experimental design. Firstly, a full-factorial design was employed to establish the statistically significant factors (p < 0.05). Then, the information obtained from the full-factorial design was utilised by applying a central composite design to obtain the following optimum conditions of the system: CF, 1.6 ml min–1; DF, 0.4 ml min–1; Ft, 5 min; and CFexp, 0.6. Once the optimum conditions were obtained, the stability of the dispersed sample was measured for 24 h by analysing 10 replicates with AF4 in order to assess the performance of the optimised dispersion protocol. Finally, the recovery of the optimised method, particle shape and particle size distribution were estimated. PMID:27650879

Computational Model Prediction and Biological Validation Using Simplified Mixed Field Exposures for the Development of a GCR Reference Field

NASA Technical Reports Server (NTRS)

Hada, M.; Rhone, J.; Beitman, A.; Saganti, P.; Plante, I.; Ponomarev, A.; Slaba, T.; Patel, Z.

2018-01-01

The yield of chromosomal aberrations has been shown to increase in the lymphocytes of astronauts after long-duration missions of several months in space. Chromosome exchanges, especially translocations, are positively correlated with many cancers and are therefore a potential biomarker of cancer risk associated with radiation exposure. Although extensive studies have been carried out on the induction of chromosomal aberrations by low- and high-LET radiation in human lymphocytes, fibroblasts, and epithelial cells exposed in vitro, there is a lack of data on chromosome aberrations induced by low dose-rate chronic exposure and mixed field beams such as those expected in space. Chromosome aberration studies at NSRL will provide the biological validation needed to extend the computational models over a broader range of experimental conditions (more complicated mixed fields leading up to the galactic cosmic rays (GCR) simulator), helping to reduce uncertainties in radiation quality effects and dose-rate dependence in cancer risk models. These models can then be used to answer some of the open questions regarding requirements for a full GCR reference field, including particle type and number, energy, dose rate, and delivery order. In this study, we designed a simplified mixed field beam with a combination of proton, helium, oxygen, and iron ions with shielding or proton, helium, oxygen, and titanium without shielding. Human fibroblasts cells were irradiated with these mixed field beam as well as each single beam with acute and chronic dose rate, and chromosome aberrations (CA) were measured with 3-color fluorescent in situ hybridization (FISH) chromosome painting methods. Frequency and type of CA induced with acute dose rate and chronic dose rates with single and mixed field beam will be discussed. A computational chromosome and radiation-induced DNA damage model, BDSTRACKS (Biological Damage by Stochastic Tracks), was updated to simulate various types of CA induced by acute exposures of the mixed field beams used for the experiments. The chromosomes were simulated by a polymer random walk algorithm with restrictions to their respective domains in the nucleus [1]. The stochastic dose to the nucleus was calculated with the code RITRACKS [2]. Irradiation of a target volume by a mixed field of ions was implemented within RITRACKs, and the fields of ions can be delivered over specific periods of time, allowing the simulation of dose-rate effects. Similarly, particles of various types and energies extracted from a pre-calculated spectra of galactic cosmic rays (GCR) can be used in RITRACKS. The number and spatial location of DSBs (DNA double-strand breaks) were calculated in BDSTRACKS using the simulated chromosomes and local (voxel) dose. Assuming that DSBs led to chromosome breaks, and simulating the rejoining of damaged chromosomes occurring during repair, BDSTRACKS produces the yield of various types of chromosome aberrations as a function of time (only final yields are presented). A comparison between experimental and simulation results will be shown.

The roll-up and merging of coherent structures in shallow mixing layers

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

Lam, M. Y., E-mail: celmy@connect.ust.hk; Ghidaoui, M. S.; Kolyshkin, A. A.

2016-09-15

The current study seeks a fundamental explanation to the development of two-dimensional coherent structures (2DCSs) in shallow mixing layers. A nonlinear numerical model based on the depth-averaged shallow water equations is used to investigate the temporal evolution of shallow mixing layers, where the mapping from temporal to spatial results is made using the velocity at the center of the mixing layers. The flow is periodic in the streamwise direction. Transmissive boundary conditions are used in the cross-stream boundaries to prevent reflections. Numerical results are compared to linear stability analysis, mean-field theory, and secondary stability analysis. Results suggest that the onsetmore » and development of 2DCS in shallow mixing layers are the result of a sequence of instabilities governed by linear theory, mean-field theory, and secondary stability theory. The linear instability of the shearing velocity gradient gives the onset of 2DCS. When the perturbations reach a certain amplitude, the flow field of the perturbations changes from a wavy shape to a vortical (2DCS) structure because of nonlinearity. The development of the vertical 2DCS does not appear to follow weakly nonlinear theory; instead, it follows mean-field theory. After the formation of 2DCS, separate 2DCSs merge to form larger 2DCS. In this way, 2DCSs grow and shallow mixing layers develop and grow in scale. The merging of 2DCS in shallow mixing layers is shown to be caused by the secondary instability of the 2DCS. Eventually 2DCSs are dissipated by bed friction. The sequence of instabilities can cause the upscaling of the turbulent kinetic energy in shallow mixing layers.« less

Statistical independence of the initial conditions in chaotic mixing.

PubMed

García de la Cruz, J M; Vassilicos, J C; Rossi, L

2017-11-01

Experimental evidence of the scalar convergence towards a global strange eigenmode independent of the scalar initial condition in chaotic mixing is provided. This convergence, underpinning the independent nature of chaotic mixing in any passive scalar, is presented by scalar fields with different initial conditions casting statistically similar shapes when advected by periodic unsteady flows. As the scalar patterns converge towards a global strange eigenmode, the scalar filaments, locally aligned with the direction of maximum stretching, as described by the Lagrangian stretching theory, stack together in an inhomogeneous pattern at distances smaller than their asymptotic minimum widths. The scalar variance decay becomes then exponential and independent of the scalar diffusivity or initial condition. In this work, mixing is achieved by advecting the scalar using a set of laminar flows with unsteady periodic topology. These flows, that resemble the tendril-whorl map, are obtained by morphing the forcing geometry in an electromagnetic free surface 2D mixing experiment. This forcing generates a velocity field which periodically switches between two concentric hyperbolic and elliptic stagnation points. In agreement with previous literature, the velocity fields obtained produce a chaotic mixer with two regions: a central mixing and an external extensional area. These two regions are interconnected through two pairs of fluid conduits which transfer clean and dyed fluid from the extensional area towards the mixing region and a homogenized mixture from the mixing area towards the extensional region.

Generation of coherent terahertz radiation in ultrafast laser-gas interactionsa)

NASA Astrophysics Data System (ADS)

Kim, Ki-Yong

2009-05-01

The generation of intense terahertz radiation in ultrafast laser-gas interactions is studied on a basis of transient electron current model. When an ultrashort pulse laser's fundamental and its second harmonic fields are mixed to ionize a gas, a nonvanishing, directional photoelectron current can be produced, which simultaneously emits terahertz radiation in the far field. Here, the generation mechanism is examined with an analytic derivation and numerical simulations, in which tunneling ionization and subsequent electron motion in the combined laser field play a key role. In the simulations, three types of laser-gas interactions are considered: (i) mixing the fundamental and its second harmonic fields, (ii) mixing nonharmonic, two-color fields, and (iii) focusing single-color, few-cycle pulses. In these interactions, terahertz generation and other nonlinear effects driven by the transient current are investigated. In particular, anticorrelation between terahertz and second (or third) harmonic generation is observed and analyzed.

Storage and retrieval of light pulse in coupled quantum wells

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

Liu, Jibing, E-mail: liu0328@foxmail.com; Liu, Na; Shan, Chuanjia

In this paper, we propose an effective scheme to create a frequency entangled states based on bound-to-bound inter-subband transitions in an asymmetric three-coupled quantum well structure. A four-subband cascade configuration quantum well structure is illuminated with a pulsed probe field and two continuous wave control laser fields to generate a mixing field. By properly adjusting the frequency detunings and the intensity of coupling fields, the conversion efficiency can reach 100%. A maximum entangled state can be achieved by selecting a proper length of the sample. We also numerically investigate the propagation dynamics of the probe pulse and mixing pulse, themore » results show that two frequency components are able to exchange energy through a four-wave mixing process. Moreover, by considering special coupling fields, the storage and retrieval of the probe pulse is also numerically simulated.« less

Simulation analysis of rectifying microfluidic mixing with field-effect-tunable electrothermal induced flow.

PubMed

Liu, Weiyu; Ren, Yukun; Tao, Ye; Yao, Bobin; Li, You

2018-03-01

We report herein field-effect control on in-phase electrothermal streaming from a theoretical point of view, a phenomenon termed "alternating-current electrothermal-flow field effect transistor" (ACET-FFET), in the context of a new technology for handing analytes in microfluidics. Field-effect control through a gate terminal endows ACET-FFET the ability to generate arbitrary symmetry breaking in the transverse vortex flow pattern, which makes it attractive for mixing microfluidic samples. A computational model is developed to study the feasibility of this new microfluidic device design for micromixing. The influence of various parameters on developing an efficient mixer is investigated, and an integrated layout of discrete electrode array is suggested for achieving high-throughput mixing. Our physical demonstration with field-effect electrothermal flow control using a simple electrode structure proves invaluable for designing active micromixers for modern micro total analytical system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mixed Methods Research in School Psychology: A Mixed Methods Investigation of Trends in the Literature

ERIC Educational Resources Information Center

Powell, Heather; Mihalas, Stephanie; Onwuegbuzie, Anthony J.; Suldo, Shannon; Daley, Christine E.

2008-01-01

This article illustrates the utility of mixed methods research (i.e., combining quantitative and qualitative techniques) to the field of school psychology. First, the use of mixed methods approaches in school psychology practice is discussed. Second, the mixed methods research process is described in terms of school psychology research. Third, the…

Highlights from the HIV Cure and Reservoir Symposium, 11-12 September 2017, Ghent, Belgium.

PubMed

Kint, Sam; Van Hecke, Clarissa; Cole, Basiel; Vandekerckhove, Linos; Sips, Magdalena

2018-01-01

For the second time, the HIV Cure Research Center (HCRC) at Ghent University organised the HIV Cure and Reservoir Symposium, in Ghent, Belgium, where in this two-day conference, virologists, molecular biologists, immunologists and clinicians presented the most recent achievements in the field of HIV cure, including data on therapeutic vaccines, HIV remission strategies such as 'shock and kill' or 'block and lock', benefits of early ART and potential of haematopoietic stem cell transplant in achieving cure. Furthermore, methods to characterise and quantify the HIV reservoir were discussed along with HIV reservoir characterisation in different body parts, including the central nervous system. An HIV activist and representative of a patients' agency also presented the patients' perspective on HIV cure. This report is a summary of all topics discussed during this symposium.

Characterisation of the epithermal neutron irradiation facility at the Portuguese research reactor using MCNP.

PubMed

Beasley, D G; Fernandes, A C; Santos, J P; Ramos, A R; Marques, J G; King, A

2015-05-01

The radiation field at the epithermal beamline and irradiation chamber installed at the Portuguese Research Reactor (RPI) at the Campus Tecnológico e Nuclear of Instituto Superior Técnico was characterised in the context of Prompt Gamma Neutron Activation Analysis (PGNAA) applications. Radiographic films, activation foils and thermoluminescence dosimeters were used to measure the neutron fluence and photon dose rates in the irradiation chamber. A fixed-source MCNPX model of the beamline and chamber was developed and compared to measurements in the first step towards planning a new irradiation chamber. The high photon background from the reactor results in the saturation of the detector and the current facility configuration yields an intrinsic insensitivity to various elements of interest for PGNAA. These will be addressed in future developments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Beyond the Domestic Sphere? A Home Science Education at the University of New Zealand, 1911-1936

ERIC Educational Resources Information Center

Collins, Jenny

2009-01-01

International developments in the field of household science, debates about women's rights to a higher education and changes in workforce demographics came together in the first decade of the twentieth century to facilitate the establishment of a School of Home Science at the University of Otago. The early years were characterised by struggles…

Social insects: from selfish genes to self organisation and beyond.

PubMed

Boomsma, Jacobus J; Franks, Nigel R

2006-06-01

Selfish gene and self-organisation approaches have revolutionised the study of social insects and have provided unparalleled insights into the highly sophisticated nature of insect social evolution. Here, we briefly review the core programs and interfaces with communication and recognition studies that characterise these fields today, and offer an interdisciplinary future perspective for the study of social insect evolutionary biology.

An experiment to test in-field pointing for Elisa

NASA Astrophysics Data System (ADS)

Brugger, Christina; Broll, Bernhard; Fitzsimons, Ewan; Johann, Ulrich; Jonke, Wouter; Lucarelli, Stefano; Nikolov, Susanne; Voert, Martijn; Weise, Dennis; Witvoet, Gert

2017-11-01

The evolved Laser Interferometer Space Antenna (eLISA) Mission is being developed to detect and characterise gravitational waves by measuring pathlength changes between free flying inertial test masses over a baseline of order 1 Gm. Here the observed astrophysical events and objects lie in a frequency range between 30 μHz and 1 Hz (the LISA measurement band, LMB).

A Systematic Review of Research into Rare Diseases in the Educational Sphere

ERIC Educational Resources Information Center

Darretxe, Leire; Gaintza, Zuriñe; Monzon-Gonzalez, Javier

2017-01-01

Rare diseases (RDs) represent a wide, varied group of illnesses characterised by their low prevalence among the population. Moreover, they can appear at any time of life, including in infancy. For this reason, the aim of this article was to review and analyse research in the field of education to find out what kind of educational response is…

A Quarter Century of Getting It Right in Education: Worldwide Successes and Continuing Challenges

ERIC Educational Resources Information Center

Heyneman, Stephen P.; Anderson, Kathryn H.

2008-01-01

In his article, Steven Klees claims that certain economic policies have been a failure in general and specifically in education. He has it backwards. His characterisation of the economics profession has not been true since the 1960s. Nobel Prizes to Simon, Akerlof, Spence and Stiglitz illustrate a flowering of ideas in fields of behaviourial and…

Laser vibrometry characterisation of a microfluidic lab-on-a-chip device: a preliminary investigation

NASA Astrophysics Data System (ADS)

Fury, C.; Gélat, P. N.; Jones, P. H.; Memoli, G.

2014-04-01

Since their original inception as ultrasound contrast agents, potential applications of microbubbles have evolved to encompass molecular imaging and targeted drug delivery. As these areas develop, so does the need to understand the mechanisms behind the interaction of microbubbles both with biological tissue and with other microbubbles. There is therefore a metrological requirement to develop a controlled environment in which to study these processes. Presented here is the design and characterisation of such a system, which consists of a microfluidic chip, specifically developed for manipulating microbubbles using both optical and acoustic trapping. A laser vibrometer is used to observe the coupling of acoustic energy into the chip from a piezoelectric transducer bonded to the surface. Measurement of the velocity of surface waves on the chip is investigated as a potential method for inferring the nature of the acoustic fields excited within the liquid medium of the device. Comparison of measured surface wavelengths with wave types suggests the observation of anti-symmetric Lamb or Love-Kirchhoff waves. Further visual confirmation of the acoustic fields through bubble aggregation highlights differences between the model and experimental results in predicting the position of acoustic pressure nodes in relation to excitation frequency.

Fractionation of poly(methacrylic acid) and poly(vinyl pyridine) in aqueous and organic mobile phases by multidetector thermal field-flow fractionation.

PubMed

Greyling, Guilaume; Pasch, Harald

2017-08-25

Multidetector thermal field-flow fractionation (ThFFF) is shown to be a versatile characterisation platform that can be used to characterise hydrophilic polymers in a variety of organic and aqueous solutions with various ionic strengths. It is demonstrated that ThFFF fractionates isotactic and syndiotactic poly(methacrylic acid) (PMAA) as well as poly(2-vinyl pyridine) (P2VP) and poly(4-vinyl pyridine) (P4VP) according to microstructure in organic solvents and that the ionic strength of the mobile phase has no influence on the retention behaviour of the polymers. With regard to aqueous solutions, it is shown that, despite the weak retention, isotactic and syndiotactic PMAA show different retention behaviours which can qualitatively be attributed to microstructure. Additionally, it is shown that the ionic strength of the mobile phase has a significant influence on the thermal diffusion of polyelectrolytes in aqueous solutions and that the addition of an electrolyte is essential to achieve a microstructure-based separation of P2VP and P4VP in aqueous solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamics of yield-stress droplets: Morphology of impact craters

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Sohr, David; Ferrari, Leo; Dalziel, Stuart

2017-11-01

Yield strength can play an important role for the dynamics of droplets impacting on surfaces, whether at the industrial or planetary scale, and can capture a zoo of impact crater morphologies, from simple parabolic craters, to more complex forms with forms with, for example, multiple rings, central peaks. Here we show that the morphology of planetary impact craters can be reproduced in the laboratory using carbopol, a transparent yield-stress fluid, as both impactor and bulk fluid. Using high-speed video photography, we characterise the universal, transient initial excavation stage of impact and show the dependence of the subsequent relaxation to final crater morphology on impactor size, impact speed and yield stress. To further interrogate our laboratory impacts, we dye our impactor to map its final distribution and use particle tracking to determine the flow fields during impact and the maximal extent of the yield surface. We characterise the flow-fields induced during impact, and the maximal extent of the yield surface, by tracking particles within the bulk fluid and map the distribution of impactor and bulk by tracing the final distribution of dyed impactor. The results of laboratory impact droplets are used to infer the properties of planetary impactors, and aid in inter.

Hot mix asphalt research investigation for Connecticut : part E - comparison of field performance of superpave and traditional marshall mixes.

DOT National Transportation Integrated Search

2014-07-01

This research is part of the series of investigated topics surrounding hot mix asphalt in Connecticut. : This research investigates the performance of sections of pavements designed using both the Marshall : and Superpave mix design methods. Sixteen ...

A mechanical model for complex fault patterns induced by fluid overpressures due to dehydration reaction within evaporitic rocks

NASA Astrophysics Data System (ADS)

de Paola, N.; Collettini, C.; Trippetta, F.; Barchi, M. R.; Minelli, G.

2006-12-01

Complex fault patterns, i.e. faults which exhibit a diverse range of strikes, may develop under a weak/absent regional tectonic field (e.g. polygonal faults). We studied a complex synsedimentary fault pattern, geometrically similar to polygonal fault systems, developed during an early Jurassic faulting episode and exposed in the Umbria-Marche Apennines (Italy). Along the passive margin of the African plate, these faults disrupt the Early Jurassic platform overlying the Triassic Evaporites, and bound the subsiding basins where a pelagic succession was successively deposited. We digitised the fault pattern at the regional scale on the grounds of the available geological maps, characterising each fault in terms of attitude, length and throw (i.e. vertical displacement). Fault statistical analysis shows a largely scattered orientation, a high grade of fragmentation, an average length of about 10 km and a constant length/displacement ratio. The measured stratigraphic throw ranges from 300 m to 700 m leading to very low long-term fault slip rates (less than 0.1 mm/yr). We propose a mechanical model where Jurassic faulting has been strongly influenced by the onset of dehydration of the Triassic Evaporites, made of interbedded gypsum layers and dolostones. Dehydration, i.e. anhydritization of the gypsum rich layers, initiated during burial at 1000 m of depth. During initial phases of dehydration increasing fluid pressures trapped at the gypsum-dolostones interface, promote hydrofracturing and faulting within the dolostone layers and subsequent fluid release. Fluid expulsion produces volume contraction of the dehydrating rocks causing vertical thinning and horizontal isotropic extension. This state of non-plane strain is accommodated within the composite gypsum-dolostones sequence by a mix of ductile (flowage and boudinage) and brittle (hydrofracturing and faulting) deformation processes. The stress field caused by the former processes, consistent with an almost isotropic stress distribution within the horizontal plane, explains well the studied complex fault pattern and seems to be dominant over the far-field regional extensional tectonics.

The Periodic Flapping and Breathing of Saturn's Magnetodisk During Equinox

NASA Astrophysics Data System (ADS)

Sorba, A. M.; Achilleos, N.; Guio, P.; Arridge, C. S.; Dougherty, M. K.; Sergis, N.

2017-12-01

Periodic variations have been observed in many field and particle properties in Saturn's magnetosphere, modulated at a period close to the planetary rotation rate. Magnetic field observations by Cassini's magnetometer instrument suggest that in the outer magnetosphere (beyond 12 Saturn radii) Saturn's current sheet is periodically displaced with respect to the rotational equator, to a first approximation acting as a rotating, tilted disk. This manifests as a `flapping' mode when observed by the spacecraft. Recent studies suggest the magnetosphere also has a `breathing' mode, expanding and contracting with a period close to the planetary rotation rate. We model these two modes in tandem by combining a global, geometrical model of a tilted and rippled current sheet with a local, force-balance model of Saturn's magnetodisk, accounting for the magnetospheric size and hot plasma content. We simulate the breathing behavior by introducing an azimuthal dependence of the system size. We fit Cassini magnetometer data acquired on equatorial orbits from 23 Oct - 17 Dec 2009 (Revs 120-122), close to Saturn equinox, in order that seasonal effects on the current sheet are minimised. We find that our model characterises well the amplitude and phase of the oscillations in the data, for those passes that show clear periodic signatures in the field. In particular, the Bθ (meridional) component can only be characterised when the breathing mode is included. This study introduces calculations for an oscillating boundary under conditions of constant solar wind dynamic pressure, which provide a good basis for understanding the complex relationship between current sheet dynamics and the periodic field perturbations.

Inventory of MRI applications and workers exposed to MRI-related electromagnetic fields in the Netherlands.

PubMed

Schaap, Kristel; Christopher-De Vries, Yvette; Slottje, Pauline; Kromhout, Hans

2013-12-01

This study aims to characterise and quantify the population that is occupationally exposed to electromagnetic fields (EMF) from magnetic resonance imaging (MRI) devices and to identify factors that determine the probability and type of exposure. A questionnaire survey was used to collect information about scanners, procedures, historical developments and employees working with or near MRI scanners in clinical and research MRI departments in the Netherlands. Data were obtained from 145 MRI departments. A rapid increase in the use of MRI and field strength of the scanners was observed and quantified. The strongest magnets were employed by academic hospitals and research departments. Approximately 7000 individuals were reported to be working inside an MRI scanner room and were thus considered to have high probability of occupational exposure to static magnetic fields (SMF). Fifty-four per cent was exposed to SMF at least one day per month. The largest occupationally exposed group were radiographers (n ~ 1700). Nine per cent of the 7000 involved workers were regularly present inside a scanner room during image acquisition, when exposure to additional types of EMF is considered a possibility. This practice was most prevalent among workers involved in scanning animals. The data illustrate recent trends and historical developments in magnetic resonance imaging and provide an extensive characterisation of the occupationally exposed population. A considerable number of workers are potentially exposed to MRI-related EMF. Type and frequency of potential exposure depend on the job performed, as well as the type of workplace. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Nanotechnology-supported THz medical imaging

PubMed Central

Stylianou, Andreas; Talias, Michael A

2013-01-01

Over the last few decades, the achievements and progress in the field of medical imaging have dramatically enhanced the early detection and treatment of many pathological conditions. The development of new imaging modalities, especially non-ionising ones, which will improve prognosis, is of crucial importance. A number of novel imaging modalities have been developed but they are still in the initial stages of development and serious drawbacks obstruct them from offering their benefits to the medical field. In the 21 st century, it is believed that nanotechnology will highly influence our everyday life and dramatically change the world of medicine, including medical imaging. Here we discuss how nanotechnology, which is still in its infancy, can improve Terahertz (THz) imaging, an emerging imaging modality, and how it may find its way into real clinical applications. THz imaging is characterised by the use of non-ionising radiation and although it has the potential to be used in many biomedical fields, it remains in the field of basic research. An extensive review of the recent available literature shows how the current state of this emerging imaging modality can be transformed by nanotechnology. Innovative scientific concepts that use nanotechnology-based techniques to overcome some of the limitations of the use of THz imaging are discussed. We review a number of drawbacks, such as a low contrast mechanism, poor source performance and bulky THz systems, which characterise present THz medical imaging and suggest how they can be overcome through nanotechnology. Better resolution and higher detection sensitivity can also be achieved using nanotechnology techniques. PMID:24555052

On-ground and in-orbit characterisation plan for the PLATO CCD normal cameras

NASA Astrophysics Data System (ADS)

Gow, J. P. D.; Walton, D.; Smith, A.; Hailey, M.; Curry, P.; Kennedy, T.

2017-11-01

PLAnetary Transits and Ocillations (PLATO) is the third European Space Agency (ESA) medium class mission in ESA's cosmic vision programme due for launch in 2026. PLATO will carry out high precision un-interrupted photometric monitoring in the visible band of large samples of bright solar-type stars. The primary mission goal is to detect and characterise terrestrial exoplanets and their systems with emphasis on planets orbiting in the habitable zone, this will be achieved using light curves to detect planetary transits. PLATO uses a novel multi- instrument concept consisting of 26 small wide field cameras The 26 cameras are made up of a telescope optical unit, four Teledyne e2v CCD270s mounted on a focal plane array and connected to a set of Front End Electronics (FEE) which provide CCD control and readout. There are 2 fast cameras with high read-out cadence (2.5 s) for magnitude ~ 4-8 stars, being developed by the German Aerospace Centre and 24 normal (N) cameras with a cadence of 25 s to monitor stars with a magnitude greater than 8. The N-FEEs are being developed at University College London's Mullard Space Science Laboratory (MSSL) and will be characterised along with the associated CCDs. The CCDs and N-FEEs will undergo rigorous on-ground characterisation and the performance of the CCDs will continue to be monitored in-orbit. This paper discusses the initial development of the experimental arrangement, test procedures and current status of the N-FEE. The parameters explored will include gain, quantum efficiency, pixel response non-uniformity, dark current and Charge Transfer Inefficiency (CTI). The current in-orbit characterisation plan is also discussed which will enable the performance of the CCDs and their associated N-FEE to be monitored during the mission, this will include measurements of CTI giving an indication of the impact of radiation damage in the CCDs.

Field Management of Hot Mix Asphalt Volumetric Properties

DOT National Transportation Integrated Search

1995-12-01

The Federal Highway Administration (FHWA) Demonstration Project No. 74 has clearly shown that significant differences exist between the volumetric properties of the laboratory designed and plant produced hot mix asphalt (HMA) mixes. The volumetric pr...

Life sciences on the moon

NASA Astrophysics Data System (ADS)

Horneck, G.

Despite of the fact that the lunar environment lacks essential prerequisites for supporting life, lunar missions offer new and promising opportunities to the life sciences community. Among the disciplines of interest are exobiology, radiation biology, ecology and human physiology. In exobiology, the Moon offers an ideal platform for studies related to the understanding of the principles, leading to the origin, evolution and distribution of life. These include the analysis of lunar samples and meteorites in relatively pristine conditions, radioastronomical search for other planetary systems or Search for Extra-Terrestrial Intelligence (SETI), and studies on the role of radiation in evolutionary processes and on the environmental limits for life. For radiation biology, the Moon provides an unique laboratory with built-in sources for optical as well as ionising radiation to investigate the biological importance of the various components of cosmic and solar radiation. Before establishing a lunar base, precursor missions will provide a characterisation of the radiation field, determination of depth dose distributions in different absorbers, the installation of a solar flare alert system, and a qualification of the biological efficiency of the mixed radiation environment. One of the most challenging projects falls into the domain of ecology with the establishment for the first time of an artificial ecosystem on a celestial body beyond the Earth. From this venture, a better understanding of the dynamics regulating our terrestrial biosphere is expected. It will also serve as a precursor of bioregenerative life support systems for a lunar base. The establishment of a lunar base with eventually long-term human presence will raise various problems in the fields of human physiology and health care, psychology and sociology. Protection guidelines for living in this hostile environment have to be established.

Experimental study of a fine structure of 2D wakes and mixing past an obstacle in a continuously stratified fluid

NASA Astrophysics Data System (ADS)

Chashechkin, Yuli. D.; Mitkin, Vladimir V.

2001-10-01

Experimental investigations of fine and macroscopic structures of density and velocity disturbances generated by a towing cylinder or a vertical strip in a linearly stratified liquid are carried out in a rectangular tank. A density gradient field is visualised by different Schlieren methods (direct shadow, 'slit-knife', 'slit-thread', 'natural rainbow') characterised by a high spatial resolution. Profiles of fluid velocity are visualised by density markers — wakes past a vertically descending sugar crystal or an ascending gas bubble. In a fluid at rest, the density marker acts as a vertical linear source of internal oscillations which allows us to measure buoyancy frequency over all depth by the Schlieren instrument directly or by a conductivity probe in a particular point. Sensitive methods reveal a set of high gradient interfaces inside and outside the downstream wake besides well-known large scale elements: upstream disturbances, attached internal waves and vortices. Solitary interfaces located inside the attached internal waves field have no features on their leading and trailing edges. A thickness of interfaces is defined by an appropriate diffusion coefficient and a buoyancy frequency. High gradient interfaces bound compact vortices. Vortices moving with respect to environment emit their own systems of internal waves randomising a regular pattern of attached antisymmetric internal waves. But after a rather long time a wave recurrence occurs and a regular but symmetric structure of the longest waves (similar to the pattern of initial attached internal waves) is observed again. High gradient interfaces and lines of their intersections act as collectors of a dye coming from a compact source or from a coloured liquid volume inside the tank and separate coloured and clear areas.

Reconstructing Deep-Marine Sediment Gravity Flow Dynamics from Ancient Rocks: an Example from Skoorsteenberg Fm. Tanqua Karoo

NASA Astrophysics Data System (ADS)

Kane, I. A.; Pontén, A. S. M.; Hodgson, D.; Vangdal, B.

2015-12-01

The processes which create deep-marine lobes are challenging to study, owing to the depth of the lobes beneath the sea surface and the destructive nature of the sediment gravity flows which transport the sediment that builds them. One approach is to reconstruct paleohydraulics using detailed outcrop observations which can be used to build a theoretical framework for flow behavior. The Skoorsteenberg Fm., Tanqua Karoo, offers an excellent opportunity to study fine-grained deep-marine lobes in near continuous quasi-3D exposure. The spatial and stratigraphic distribution of the various facies of Fan 3 (one of the Skoorsteenberg Fm. lobe complexes) are presented. The turbidites which dominate the proximal and medial lobe areas, pass down-dip into very muddy sandstones which are here attributed to a type of transitional flow state. The model developed here suggests that turbidity currents exiting channels were large and turbulent enough to erode and entrain their substrate, increasing their concentration and clay content. As the flows decelerated they became increasingly stratified, characterised by an increasing bulk Richardson (Ri). Sand and silt particles settled together with flocculated clay, forming a cohesive, low yield-strength layer. This layer flowed in a laminar manner but settling of sand grains continued due to the low yield strength. The rising yield strength of the lower layer progressively inhibited the efficiency of vertical mixing, characterised by an increasing flux Richardson number, which, when it exceeded a critical value , led to a catastrophic collapse of the turbulent energy field and en-masse transformation of the upper part of the flow, ultimately resulting in a highly argillaceous sandstone (debrite) division. This transformation was possible due to the narrow grain size range, dominantly silt-vf sand with abundant flocculated clay, which behaved as a single phase. This model of flow evolution accounts for the presence of such beds without invoking external controls or large-scale flow partitioning, and also explains the abrupt pinchout of all divisions of these sandstones following catastrophic loss of turbulence.

Characterization of phenotypes of immune cells and cytokines associated with chronic exposure to Premolis semirufa caterpillar bristles extract.

PubMed

Villas-Boas, Isadora Maria; Gonçalves-de-Andrade, Rute Maria; Squaiella-Baptistão, Carla Cristina; Sant'Anna, Osvaldo Augusto; Tambourgi, Denise V

2013-01-01

The Brazilian moth Premolis semirufa (Walker, 1856), usually called pararama, is a parasite of the rubber Hevea genus. Contact with the bristles causes symptoms of acute inflammation. A chronic inflammatory reaction frequently occurs in individuals after multiple contacts, and this reaction is characterised by articular synovial membrane thickening with joint deformities, common characteristics of chronic synovitis. Extract from the bristles has been shown to induce an intense inflammatory response in a murine model, and this reaction was characterised by the presence of neutrophils in the paw tissues of injected mice and a strong, specific antibody response. There is not yet an effective treatment for incidents involving contact with pararama. In this study, we evaluated the phenotype of the immunological response and cytokine production in BALB/c mice subcutaneously injected in the footpad with P. semirufa bristle extract or sterile saline (control) seven times at 15 day intervals. An analysis of cells from the draining lymph node by flow cytometry showed that the absolute numbers of TCD4, TCD8 and B lymphocytes, as well as the expression of activation molecules, were higher in the extract-treated group. Furthermore, immunohistochemistry and immunofluorescence analyses showed a mixed inflammatory infiltrate composed of neutrophils and macrophages at the inoculation site. In addition, an analysis of paw cytokines showed elevated levels of IL-6, IL-12, IL-10, IL-17 and IL-23 after the 7(th) inoculation. In conclusion, these data provide evidence of pro-inflammatory changes in the phenotypes of immune cells and cytokine production in animals subjected to injections with an extract from Premolis semirufa bristles, which may explain the intense and prolonged inflammatory response that characterises this disorder.

Summer phytoplankton pigments and community composition related to water mass properties in the Gulf of Gabes

NASA Astrophysics Data System (ADS)

Bel Hassen, M.; Drira, Z.; Hamza, A.; Ayadi, H.; Akrout, F.; Issaoui, H.

2008-05-01

Variations in phytoplankton pigments and community composition were examined in the Gulf of Gabes in relationship to water mass properties, characterised by the influence of the Modified Atlantic Water and by the thermal stratification. Data were collected on board the R/V Hannibal during July 2005. Distinct water masses were identified using cluster analysis of temperature-salinity ( T- S) characteristics. Three major clusters appeared based on the combined effects of temperature and salinity. The first cluster was identified as the cool and less salty bottom Modified Atlantic Water (MAW). The warmer and saltier Mediterranean Mixed Water (MMW) represented the second cluster. The third cluster was the Transition Water (TW) separating the two previous clusters. The pigment and taxonomic composition of these water masses were examined. Chlorophyll a was rather low (<200 ng l -1). Chlorophyll b was generally the most abundant accessory pigment and fucoxanthin dominated the accessory pigments in the MAW. Proportions of chlorophyll a associated with different phytoplankton classes were estimated using CHEMTAX software, and did not present significant variations among water groups. The results pointed out variations in the relative contribution of each phytoplankton taxa in each station group. Chlorophytes and prasinophytes accounted for 65% of chlorophyll a in the MMW. Diatoms and chlorophytes were relatively abundant in the MAW contributing to almost 63% of chlorophyll a. An unstructured community, slightly dominated by prasinophytes, chlorophytes and cryptophytes, characterised the TW. Different trophic statuses were observed in these water masses, the MMW and the MAW being characterised by mesotrophy, while an oligotrophy was observed in the TW. Nutrient availability, particularly the P-limitation supported by the summer stratification, as revealed by the high N:P ratio (greater than 20), seems to enhance the development of small-sized phytoplankton, thereby supporting the regenerated production.

Listeria monocytogenes-carrying consortia in food industry. Composition, subtyping and numerical characterisation of mono-species biofilm dynamics on stainless steel.

PubMed

Rodríguez-López, Pedro; Saá-Ibusquiza, Paula; Mosquera-Fernández, Maruxa; López-Cabo, Marta

2015-08-03

In order to find out how real Listeria monocytogenes-carrying biofilms are in industrial settings, a total of 270 environmental samples belonging to work surfaces from fish (n = 123), meat (n = 75) and dairy industries (n = 72) were analysed in order to detect L. monocytogenes. 12 samples were positive for L. monocytogenes and a total of 18 different species were identified as accompanying microbiota in fish and meat industry. No L. monocytogenes was found in samples from dairy industry. Molecular characterisation combining results of AscI and ApaI macrorestriction PFGE assays yielded 7 different subtypes of L. monocytogenes sharing in 71.43% of cases the same serogroup (1/2a-3a). Results from dynamic numerical characterisation between L. monocytogenes monospecies biofilms on stainless steel (SS) using MATLAB-based tool BIOFILMDIVER demonstrated that except in isolate A1, in which a significant increase in the percentage of covered area (CA), average diffusion distance (ADD) and maximum diffusion distance (MDD) was observed after 120 h of culture, no significant differences were observed in the dynamics of the rest of the L. monocytogenes isolates. Quantitative dual-species biofilm association experiments performed on SS indicated that L. monocytogenes cell counts presented lower values in mixed-species cultures with certain species at 24 and 48 h compared with mono-species culture. However, they remained unaltered after 72 h except when co-cultured with Serratia fonticola which presented differences in all sampling times and was also the dominant species within the dual-species biofilm. When considering frequency of appearance of accompanying species, an ecological distribution was demonstrated as Escherichia coli appeared to be the most abundant in fish industry and Carnobacterium spp. in meat industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Accuracy Test of the OPLS-AA Force Field for Calculating Free Energies of Mixing and Comparison with PAC-MAC

PubMed Central

2017-01-01

We have calculated the excess free energy of mixing of 1053 binary mixtures with the OPLS-AA force field using two different methods: thermodynamic integration (TI) of molecular dynamics simulations and the Pair Configuration to Molecular Activity Coefficient (PAC-MAC) method. PAC-MAC is a force field based quasi-chemical method for predicting miscibility properties of various binary mixtures. The TI calculations yield a root mean squared error (RMSE) compared to experimental data of 0.132 kBT (0.37 kJ/mol). PAC-MAC shows a RMSE of 0.151 kBT with a calculation speed being potentially 1.0 × 104 times greater than TI. OPLS-AA force field parameters are optimized using PAC-MAC based on vapor–liquid equilibrium data, instead of enthalpies of vaporization or densities. The RMSE of PAC-MAC is reduced to 0.099 kBT by optimizing 50 force field parameters. The resulting OPLS-PM force field has a comparable accuracy as the OPLS-AA force field in the calculation of mixing free energies using TI. PMID:28418655

Mixed-order phase transition in a colloidal crystal

PubMed Central

Tierno, Pietro; Casademunt, Jaume

2017-01-01

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid–solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2−Hs2|−1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions. PMID:29158388

Flux-related and Critical Dilution Indices: Quantitative Indicators of Mixing and Mixing-controlled Reactions in Heterogeneous Porous Media

NASA Astrophysics Data System (ADS)

Chiogna, G.; Cirpka, O. A.; Grathwohl, P.; Rolle, M.

2010-12-01

The correct quantification of mixing is of utmost importance for modeling reactive transport in porous media and, thereby assessing the fate and transport of contaminants in the subsurface. An appropriate measure of mixing in heterogeneous porous formations should correctly capture the effects on mixing intensity of various processes at different scales, such as local dispersion and the effect of mixing enhancement due to heterogeneities. In this work, we use the concept of the flux-related dilution index as a measure of transverse mixing. This quantity expresses the dilution of the mass flux of a tracer solution over the total discharge of the system and is particularly suited to address problems where a compound is continuously injected into the domain. We focus our attention on two-dimensional systems under steady-state flow conditions and investigate both conservative and reactive transport in both homogeneous and heterogeneous porous media at different scales. For mixing-controlled reactive systems, we introduce and illustrate the concept of the critical dilution index, which represents the amount of mixing required for complete degradation of a continuously emitted plume undergoing decay upon mixing with ambient water. We perform two-dimensional numerical experiments at bench and field scales in homogeneous and heterogeneous conductivity fields. These numerical simulations show that the flux-related dilution index quantifies mixing and that the concept of the critical dilution index is a useful measure to relate the mixing of conservative tracers to mixing-controlled turnover of reactive compounds. In the end we define an effective transverse dispersion coefficient which is able to capture the main characteristics of the physical mechanisms controlling reactive transport at the field scale. Furthermore we investigated the influence of compound specific local transverse dispersion coefficients on the flux related dilution index and on the critical dilution index.

An experimental study of reactive turbulent mixing

NASA Technical Reports Server (NTRS)

Cooper, L. P.; Marek, C. J.; Strehlow, R. A.

1977-01-01

An experimental study of two coaxial gas streams, which react very rapidly, was performed to investigate the mixing characteristics of turbulent flow fields. The center stream consisted of a CO-N2 mixture and the outer annular stream consisted of air vitiated by H2 combustion. The streams were at equal velocity (50 m/sec) and temperature (1280 K). Turbulence measurements were obtained using hot film anemometry. A sampling probe was used to obtain time averaged gas compositions. Six different turbulence generators were placed in the annular passage to alter the flow field mixing characteristics. The turbulence generators affected the bulk mixing of the streams and the extent of CO conversion to different degrees. The effects can be related to the average eddy size (integral scale) and the bulk mixing. Higher extents of conversion of CO to CO2 were found be increasing the bulk mixing and decreasing the average eddy size.

The cause and source of melting for the most recent volcanism in Tibet: A combined geochemical and geophysical perspective

NASA Astrophysics Data System (ADS)

Wei, Feixiang; Prytulak, Julie; Xu, Jiandong; Wei, Wei; Hammond, James O. S.; Zhao, Bo

2017-09-01

We investigate the youngest volcanic activity on the Tibetan Plateau by combining observations from petrologic, geochemical and seismic tomography studies. Recent (from 2.80 Ma to present) post-collisional potassium-rich lavas from the Ashikule Volcanic Basin (AVB) in northwestern Tibet are characterised by remarkably enriched light rare earth elements (LREE) relative to heavy rare earth elements (HREE), and enriched large ion lithophile element (LILE) relative to high field strength elements (HFSE). Strontium and neodymium isotopic compositions are surprisingly restricted, and show little evidence for mixing or crustal contamination, despite the thick crust upon which they are erupted. Geochemical characteristics indicate a homogeneous source, highly enriched in trace elements, which is most consistent with derivation from long-lived subcontinental lithospheric mantle (SCLM). P-wave anisotropy tomography documents a gap between the north-subducting Indian slab and south-subducting Tarim slab directly beneath the AVB. We propose that volcanism in northwestern Tibet is associated with the progressive closure of this gap, during which shear heating of the SCLM can generate localised melting, with deep-seated faults providing a mechanism for erupted lavas to escape large-scale crustal contamination and fractionation in magma reservoirs. Thus, shear heating may provide an explanation for the restricted range of radiogenic isotope compositions from a SCLM source that should be, by its nature, heterogeneous on a large scale.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin

2000-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both: mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, compositional variations in metal alloys have been investigated.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin; Rose, M. Franklin (Technical Monitor)

2001-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both 1) mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, 2) compositional variations in metal alloys have been investigated.

Functional redundancy ensures performance robustness in 3-stage PHA-producing mixed cultures under variable feed operation.

PubMed

Carvalho, Gilda; Pedras, Inês; Karst, Soren M; Oliveira, Catarina S S; Duque, Anouk F; Nielsen, Per H; Reis, Maria A M

2018-01-25

Polyhydroxyalkanoates (PHA) are biopolymers that can be produced by mixed microbial cultures using wastes or industrial by-products, which represent an economical and environmental advantage over pure culture processes. The use of alternate feedstocks enables using seasonal by-products, providing that the process is resilient to transient conditions. The mixed microbial communities of a 3-stage PHA producing system fed initially with molasses and then cheese whey were investigated through amplicon sequencing of the 16S rRNA gene. The transition in feedstock resulted in an adaptation of the acidogenic community, where Actinobacteria dominated with sugarcane molasses (up to 93% of the operational taxonomic units) and Firmicutes, with cheese whey (up to 97%). The resulting fermentation products profile also changed, with a higher fraction of HV precursors obtained with molasses than cheese whey (7.1±0.5 and 1.7±0.7 gCOD/L, respectively). As for the PHA storing culture, the genera Azoarcus, Thauera and Paracoccus were enriched with fermented molasses (average 89% of Bacteria). Later, fermented cheese whey fostered a higher diversity, including some less characterised PHA-storers such as the genera Paenibacillus and Lysinibacillus. Although the microbial community structure was significantly affected by the feedstock shift, the acidogenic and PHA storing performance of the 3-stage system was very similar once a pseudo steady state was attained, showing that a reliable level of functional redundancy was attained in both mixed cultures. Copyright © 2017 Elsevier B.V. All rights reserved.

Parametric effect on the mixing of the combination of a hydrogen porthole with an air porthole in transverse gaseous injection flow fields

NASA Astrophysics Data System (ADS)

Li, Lang-quan; Huang, Wei; Yan, Li; Li, Shi-bin

2017-10-01

The dual transverse injection system with a front hydrogen porthole and a rear air porthole arranged in tandem is proposed, and this is a realistic approach for mixing enhancement and penetration improvement of transverse injection in a scramjet combustor. The influence of this dual transverse injection system on mixing characteristics has been evaluated numerically based on grid independency analysis and code validation. The numerical approach employed in the current study has been validated against the available experimental data in the open literature, and the predicted wall static pressure distributions show reasonable agreement with the experimental data for the cases with different jet-to-crossflow pressure ratios. The obtained results predicted by the three-dimensional Reynolds-average Navier - Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model show that the air pothole has an great impact on penetration depth and mixing efficiency, and the effect of air jet on flow field varies with different values of the aspect ratio. The air porthole with larger aspect ratio can increase the fuel penetration depth. However, when the aspect ratio is relatively small, the fuel penetration depth decreases, and even smaller than that of the single injection system. At the same time, the air pothole has a highly remarkable improvement on mixing efficiency, especially in the near field. The smaller the aspect ratio of the air porthole is, the higher the mixing efficiency in the near field is. This is due to its larger circulation in the near field. The dual injection system owns more losses of stagnation pressure than the single injection system.

Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7−x thin films visualized by scanning SQUID microscopy

PubMed Central

Wells, Frederick S.; Pan, Alexey V.; Wang, X. Renshaw; Fedoseev, Sergey A.; Hilgenkamp, Hans

2015-01-01

The glass-like vortex distribution in pulsed laser deposited YBa2Cu3O7 − x thin films is observed by scanning superconducting quantum interference device microscopy and analysed for ordering after cooling in magnetic fields significantly smaller than the Earth's field. Autocorrelation calculations on this distribution show a weak short-range positional order, while Delaunay triangulation shows a near-complete lack of orientational order. The distribution of these vortices is finally characterised as an isotropic vortex glass. Abnormally closely spaced groups of vortices, which are statistically unlikely to occur, are observed above a threshold magnetic field. The origin of these groups is discussed, but will require further investigation. PMID:25728772

Development of a personal dosimetry system based on optically stimulated luminescence of alpha-Al2O3:C for mixed radiation fields.

PubMed

Lee, S Y; Lee, K J

2001-04-01

To develop a personal optically stimulated luminescence (OSL) dosimetry system for mixed radiation fields using alpha-Al2O3:C, a discriminating badge filter system was designed by taking advantage of its optically stimulable properties and energy dependencies. This was done by designing a multi-element badge system for powder layered alpha-Al2O3:C material and an optical reader system based on high-intensity blue light-emitting diode (LED). The design of the multielement OSL dosimeter badge system developed allows the measurement of a personal dose equivalent value Hp(d) in mixed radiation fields of beta and gamma. Dosimetric properties of the personal OSL dosimeter badge system investigated here were the dose response, energy response and multi-readability. Based on the computational simulations and experiments of the proposed dosimeter design, it was demonstrated that a multi-element dosimeter system with an OSL technology based on alpha-Al2O3:C is suitable to obtain personal dose equivalent information in mixed radiation fields.

Natural succession impeded by smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium) in an abandoned agricultural field

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

Nelson, J.K.

1997-11-01

In 1975, an abandoned agricultural field at Rocky Flats Environmental Technology Site (Site) that had been cultivated for more than 38 years, was seeded with smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium). Although these species are commonly planted in reclamation and roadside seed mixtures, few studies have documented their impact on the re-establishment of native plant communities. In 1994, species richness, cover, and biomass were sampled in the agricultural field and compared to the surrounding mixed-grass prairie at the Site. The agricultural field contained only 61 plant species (62% native), compared to 143 species (81% native) in themore » surrounding mixed-grass prairie. Community similarity based on species presence/absence was 0.47 (Sorensen coefficient of similarity). Basal vegetative cover was 11.2% in the agricultural field and 29.1% in the mixed-grass prairie. Smooth brome and intermediate wheatgrass accounted for 93% of the relative foliar cover and 96% of the biomass in the agricultural field. The aggressive nature of these two planted species has impeded the natural succession of the agricultural field to a more native prairie community. Studies of natural succession on abandoned fields and roads in northeastern Colorado have indicated that if left alone, fields would return to their native climax state in approximately 50 years and would be approaching their native state after 20--25 years. Based on the results of this study, this agricultural field may take more than 100 years to return to a native mixed-grass prairie state and it may never achieve a native state without human intervention.« less

Effects of incomplete mixing on reactive transport in flows through heterogeneous porous media

NASA Astrophysics Data System (ADS)

Wright, Elise E.; Richter, David H.; Bolster, Diogo

2017-11-01

The phenomenon of incomplete mixing reduces bulk effective reaction rates in reactive transport. Many existing models do not account for these effects, resulting in the overestimation of reaction rates in laboratory and field settings. To date, most studies on incomplete mixing have focused on diffusive systems; here, we extend these to explore the role that flow heterogeneity has on incomplete mixing. To do this, we examine reactive transport using a Lagrangian reactive particle tracking algorithm in two-dimensional idealized heterogeneous porous media. Contingent on the nondimensional Peclet and Damköhler numbers in the system, it was found that near well-mixed behavior could be observed at late times in the heterogeneous flow field simulations. We look at three common flow deformation metrics that describe the enhancement of mixing in the flow due to velocity gradients: the Okubo-Weiss parameter (θ ), the largest eigenvalue of the Cauchy-Green strain tensor (λC), and the finite-time Lyapunov exponent (Λ ). Strong mixing regions in the heterogeneous flow field identified by these metrics were found to correspond to regions with higher numbers of reactions, but the infrequency of these regions compared to the large numbers of reactions occurring elsewhere in the domain imply that these strong mixing regions are insufficient in explaining the observed near well-mixed behavior. Since it was found that reactive transport in these heterogeneous flows could overcome the effects of incomplete mixing, we also search for a closure for the mean concentration. The conservative quantity u2¯, where u =CA-CB , was found to predict the late time scaling of the mean concentration, i.e., Ci¯˜u2¯ .

Study of the flow mixing in a novel ARID raceway for algae production

DOE PAGES

Xu, Ben; Li, Peiwen; Waller, P.

2014-07-31

A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a bettermore » mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry.« less

Study of the flow mixing in a novel ARID raceway for algae production

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

Xu, Ben; Li, Peiwen; Waller, P.

A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a bettermore » mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry.« less

Mixed Beam Murine Harderian Gland Tumorigenesis: Predicted Dose-Effect Relationships if neither Synergism nor Antagonism Occurs

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

Siranart, Nopphon; Blakely, Eleanor A.; Cheng, Alden

Complex mixed radiation fields exist in interplanetary space, and not much is known about their latent effects on space travelers. In silico synergy analysis default predictions are useful when planning relevant mixed-ion-beam experiments and interpreting their results. These predictions are based on individual dose-effect relationships (IDER) for each component of the mixed-ion beam, assuming no synergy or antagonism. For example, a default hypothesis of simple effect additivity has often been used throughout the study of biology. However, for more than a century pharmacologists interested in mixtures of therapeutic drugs have analyzed conceptual, mathematical and practical questions similar to those thatmore » arise when analyzing mixed radiation fields, and have shown that simple effect additivity often gives unreasonable predictions when the IDER are curvilinear. Various alternatives to simple effect additivity proposed in radiobiology, pharmacometrics, toxicology and other fields are also known to have important limitations. In this work, we analyze upcoming murine Harderian gland (HG) tumor prevalence mixed-beam experiments, using customized open-source software and published IDER from past single-ion experiments. The upcoming experiments will use acute irradiation and the mixed beam will include components of high atomic number and energy (HZE). We introduce a new alternative to simple effect additivity, "incremental effect additivity", which is more suitable for the HG analysis and perhaps for other end points. We use incremental effect additivity to calculate default predictions for mixture dose-effect relationships, including 95% confidence intervals. We have drawn three main conclusions from this work. 1. It is important to supplement mixed-beam experiments with single-ion experiments, with matching end point(s), shielding and dose timing. 2. For HG tumorigenesis due to a mixed beam, simple effect additivity and incremental effect additivity sometimes give default predictions that are numerically close. However, if nontargeted effects are important and the mixed beam includes a number of different HZE components, simple effect additivity becomes unusable and another method is needed such as incremental effect additivity. 3. Eventually, synergy analysis default predictions of the effects of mixed radiation fields will be replaced by more mechanistic, biophysically-based predictions. However, optimizing synergy analyses is an important first step. If mixed-beam experiments indicate little synergy or antagonism, plans by NASA for further experiments and possible missions beyond low earth orbit will be substantially simplified.« less

"Willing Enthusiasts" or "Lame Ducks"? Issues in Teacher Professional Development Policy in England and Wales 1910-1975

ERIC Educational Resources Information Center

Robinson, Wendy; Bryce, Marie

2013-01-01

Though there is a well-established body of research in the field of teacher professional development, it is characterised by a real dearth of any detailed historical analysis. This paper seeks to address this gap, by offering a new historical analysis of a case study of the evolution of organised teacher professional development in England and…

How Does Innovative Continuous Professional Development (CPD) Operate in the ECEC Sector? Insights from a Cross-Analysis of Cases in Denmark, Italy and Poland

ERIC Educational Resources Information Center

Bove, Chiara; Jensen, Bente; Wyslowska, Olga; Iannone, Rosa Lisa; Mantovani, Susanna; Karwowska-Struczyk, Malgorzata

2018-01-01

This article offers insights into what characterises innovative continuous professional development (CPD) in the field of early childhood education and care (ECEC) by analysing similarities and differences from case studies of exemplary approaches to innovative CPD in Denmark, Italy and Poland. The comparative analysis focuses on four features…

Characterising the Ionosphere (La caracterisation de l’ionosphere)

DTIC Science & Technology

2009-01-01

and these emissions are characteristic for proton precipitation. The hydrogen that is produced by charge exchange collisions has the kinetic energy ...the same kinetic energy as the original proton had, but does not gyrate around the magnetic field. The precipitation therefore spreads horizontally...latitudinal extend of the D-region ionization [Rodger et al., 2006]. Depending on their energy , these energetic protons also penetrate into the middle

Nonclassical properties of coherent light in a pair of coupled anharmonic oscillators

NASA Astrophysics Data System (ADS)

Alam, Nasir; Mandal, Swapan

2016-01-01

The Hamiltonian and hence the equations of motion involving the field operators of two anharmonic oscillators coupled through a linear one is framed. It is found that these equations of motion involving the non-commuting field operators are nonlinear and are coupled to each other and hence pose a great problem for getting the solutions. In order to investigate the dynamics and hence the nonclassical properties of the radiation fields, we obtain approximate analytical solutions of these coupled nonlinear differential equations involving the non-commuting field operators up to the second orders in anharmonic and coupling constants. These solutions are found useful for investigating the squeezing of pure and mixed modes, amplitude squared squeezing, principal squeezing, and the photon antibunching of the input coherent radiation field. With the suitable choice of the parameters (photon number in various field modes, anharmonic, and coupling constants, etc.), we calculate the second order variances of field quadratures of various modes and hence the squeezing, amplitude squared, and mixed mode squeezing of the input coherent light. In the absence of anharmonicities, it is found that these nonlinear nonclassical phenomena (squeezing of pure and mixed modes, amplitude squared squeezing and photon antibunching) are completely absent. The percentage of squeezing, mixed mode squeezing, amplitude squared squeezing increase with the increase of photon number and the dimensionless interaction time. The collapse and revival phenomena in squeezing, mixed mode squeezing and amplitude squared squeezing are exhibited. With the increase of the interaction time, the monotonic increasing nature of the squeezing effects reveal the presence of unwanted secular terms. It is established that the mere coupling of two oscillators through a third one does not produces the squeezing effects of input coherent light. However, the pure nonclassical phenomena of antibunching of photons in vacuum field modes are obtained through the mere coupling and hence the transfers of photons from the remaining coupled mode.

Chaotic dynamics in premixed hydrogen/air channel flow combustion

NASA Astrophysics Data System (ADS)

Pizza, Gianmarco; Frouzakis, Christos E.; Mantzaras, John

2012-04-01

The complex oscillatory behaviour observed in fuel-lean premixed hydrogen/air atmospheric pressure flames in an open planar channel with prescribed wall temperature is investigated by means of direct numerical simulations, employing detailed chemistry descriptions and species transport, and nonlinear dynamics analysis. As the inflow velocity is varied, the sequence of transitions includes harmonic single frequency oscillations, intermittency, mixed mode oscillations, and finally a period-doubling cascade leading to chaotic dynamics. The observed modes are described and characterised by means of phase-space portraits and next amplitude maps. It is shown that the interplay of chemistry, transport, and wall-bounded developing flow leads to considerably richer dynamics compared to fuel-lean hydrogen/air continuously stirred tank reactor studies.

▼ Eluxadoline for IBS-D.

PubMed

2017-08-01

Irritable bowel syndrome (IBS) is a chronic relapsing gastrointestinal problem characterised by intestinal pain and associated alterations of defecation and/or bowel habit (constipation: IBS-C or diarrhoea: IBS-D). 1,2 Opioid receptors in the gut have a role in gastrointestinal motility, secretion and sensation. 3 Τ Eluxadoline (Truberzi-Allergan) is a locally acting, mixed opioid receptor agonist/antagonist licensed for the treatment of IBS-D in adults. 4 Here, we consider the evidence for eluxadoline and how it fts with current management strategies for IBS-D. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

CESAR: A Code for Nuclear Fuel and Waste Characterisation

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

Vidal, J.M.; Grouiller, J.P.; Launay, A.

2006-07-01

CESAR (Simplified Evolution Code Applied to Reprocessing) is a depletion code developed through a joint program between CEA and COGEMA. In the late 1980's, the first use of this code dealt with nuclear measurement at the Laboratories of the La Hague reprocessing plant. The use of CESAR was then extended to characterizations of all entrance materials and for characterisation, via tracer, of all produced waste. The code can distinguish more than 100 heavy nuclides, 200 fission products and 100 activation products, and it can characterise both the fuel and the structural material of the fuel. CESAR can also make depletionmore » calculations from 3 months to 1 million years of cooling time. Between 2003-2005, the 5. version of the code was developed. The modifications were related to the harmonisation of the code's nuclear data with the JEF2.2 nuclear data file. This paper describes the code and explains the extensive use of this code at the La Hague reprocessing plant and also for prospective studies. The second part focuses on the modifications of the latest version, and describes the application field and the qualification of the code. Many companies and the IAEA use CESAR today. CESAR offers a Graphical User Interface, which is very user-friendly. (authors)« less

Development of a Methodology for the Characterisation of Air-coupled Ultrasound Probes

NASA Astrophysics Data System (ADS)

Pietroni, Paolo; Marco Revel, Gian

2010-05-01

This study is aimed at developing a technique for the characterisation of air-coupled ultrasound probes, starting from the analysis of the mechanical behaviour of the probe membrane. The vibratory behaviour of the emission membrane is studied using laser-Doppler vibrometry techniques with high frequency demodulation system (20 MHz). The determination of the vibration provides information which are useful for the assessment of the performance of the probe, in particular concerning the Quality factor and the portion of the membrane which really contributes to the emission. During the second step the results of the vibration measurements are used to calculate, by means of numerical boundary element method, the ultrasound beam emitted in terms of intensity in space. The obtained field is compared with the direct measurements carried out by scanning with the receiver probe and a pinhole plate. This comparison allows the potential and the problems of the two different characterisation techniques to be determined, even if the pinhole technique (which is currently considered the state of the art) cannot be used as an absolute reference. This study appears to be useful for paving the way for a new methodology for the calibration of air-coupled ultrasound probes, which potentially could be used not only to improve the probe manufacturing process, but also to control conformity to specifications.

Standardisation of magnetic nanoparticles in liquid suspension

NASA Astrophysics Data System (ADS)

Wells, James; Kazakova, Olga; Posth, Oliver; Steinhoff, Uwe; Petronis, Sarunas; Bogart, Lara K.; Southern, Paul; Pankhurst, Quentin; Johansson, Christer

2017-09-01

Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way.

Nanostructured Mn-Fe Binary Mixed Oxide: Synthesis, Characterization and Evaluation for Arsenic Removal.

PubMed

Pillewan, Pradnya; Mukherjee, Shrabanti; Bansiwal, Amit; Rayalu, Sadhana

2014-07-01

Adsorption of arsenic on bimetallic Mn and Fe mixed oxide was carried out using both field as well as simulated water. The material was synthesized using hydrothermal method and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Langmuir and Freundlich adsorption isotherms were computed using batch adsorption studies to determine the adsorption capacity of Mn-Fe binary mixed oxide for arsenic. Adsorption capacity for MFBMO obtained from Freundlich model was found to be 2.048 mg/g for simulated water and 1.084 mg/g for field water. Mn-Fe binary mixed oxide was found to be effective adsorbent for removal of arsenic from water.

Analyses of turbulent flow fields and aerosol dynamics of diesel engine exhaust inside two dilution sampling tunnels using the CTAG model.

PubMed

Wang, Yan Jason; Yang, Bo; Lipsky, Eric M; Robinson, Allen L; Zhang, K Max

2013-01-15

Experimental results from laboratory emission testing have indicated that particulate emission measurements are sensitive to the dilution process of exhaust using fabricated dilution systems. In this paper, we first categorize the dilution parameters into two groups: (1) aerodynamics (e.g., mixing types, mixing enhancers, dilution ratios, residence time); and (2) mixture properties (e.g., temperature, relative humidity, particle size distributions of both raw exhaust and dilution gas). Then we employ the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model to investigate the effects of those parameters on a set of particulate emission measurements comparing two dilution tunnels, i.e., a T-mixing lab dilution tunnel and a portable field dilution tunnel with a type of coaxial mixing. The turbulent flow fields and aerosol dynamics of particles are simulated inside two dilution tunnels. Particle size distributions under various dilution conditions predicted by CTAG are evaluated against the experimental data. It is found that in the area adjacent to the injection of exhaust, turbulence plays a crucial role in mixing the exhaust with the dilution air, and the strength of nucleation dominates the level of particle number concentrations. Further downstream, nucleation terminates and the growth of particles by condensation and coagulation continues. Sensitivity studies reveal that a potential unifying parameter for aerodynamics, i.e., the dilution rate of exhaust, plays an important role in new particle formation. The T-mixing lab tunnel tends to favor the nucleation due to a larger dilution rate of the exhaust than the coaxial mixing field tunnel. Our study indicates that numerical simulation tools can be potentially utilized to develop strategies to reduce the uncertainties associated with dilution samplings of emission sources.

PREFACE: 13th International Conference on Metrology and Properties of Engineering Surfaces

NASA Astrophysics Data System (ADS)

Leach, Richard

2011-08-01

The 13th International Conference on Metrology and Properties of Engineering Surfaces focused on the progress in surface metrology, surface characterisation instrumentation and properties of engineering surfaces. The conference provided an international forum for academics, industrialists and engineers from different disciplines to meet and exchange their ideas, results and latest research. The conference was held at Twickenham Stadium, situated approximately six miles from Heathrow Airport and approximately three miles from the National Physical Laboratory (NPL). This was the thirteenth in the very successful series of conferences, which have firmly established surface topography as a new and exciting interdisciplinary field of scientific and technological studies. Scientific Themes: Surface, Micro and Nano Metrology Measurement and Instrumentation Metrology for MST Devices Freeform Surface Measurement and Characterisation Uncertainty, Traceability and Calibration AFM/SPM Metrology Tribology and Wear Phenomena Functional Applications Stylus and Optical Instruments

STEM-EDX tomography of bimetallic nanoparticles: A methodological investigation

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

Slater, Thomas J. A.; Janssen, Arne; Camargo, Pedro H. C.

This paper presents an investigation of the limitations and optimization of energy dispersive X-ray (EDX) tomography within the scanning transmission electron microscope, focussing on application of the technique to characterising the 3D elemental distribution of bimetallic AgAu nanoparticles. The detector collection efficiency when using a standard tomography holder is characterised using a tomographic data set from a single nanoparticle and compared to a standard low background double tilt holder. Optical depth profiling is used to investigate the angles and origin of detector shadowing as a function of specimen field of view. A novel time-varied acquisition scheme is described to compensatemore » for variations in the intensity of spectrum images at each sample tilt. Lastly, the ability of EDX spectrum images to satisfy the projection requirement for nanoparticle samples is discussed, with consideration of the effect of absorption and shadowing variations« less

STEM-EDX tomography of bimetallic nanoparticles: A methodological investigation

DOE PAGES

Slater, Thomas J. A.; Janssen, Arne; Camargo, Pedro H. C.; ...

2015-10-22

This paper presents an investigation of the limitations and optimization of energy dispersive X-ray (EDX) tomography within the scanning transmission electron microscope, focussing on application of the technique to characterising the 3D elemental distribution of bimetallic AgAu nanoparticles. The detector collection efficiency when using a standard tomography holder is characterised using a tomographic data set from a single nanoparticle and compared to a standard low background double tilt holder. Optical depth profiling is used to investigate the angles and origin of detector shadowing as a function of specimen field of view. A novel time-varied acquisition scheme is described to compensatemore » for variations in the intensity of spectrum images at each sample tilt. Lastly, the ability of EDX spectrum images to satisfy the projection requirement for nanoparticle samples is discussed, with consideration of the effect of absorption and shadowing variations« less

Novel circuit design for high-impedance and non-local electrical measurements of two-dimensional materials

NASA Astrophysics Data System (ADS)

De Sanctis, Adolfo; Mehew, Jake D.; Alkhalifa, Saad; Tate, Callum P.; White, Ashley; Woodgate, Adam R.; Craciun, Monica F.; Russo, Saverio

2018-02-01

Two-dimensional materials offer a novel platform for the development of future quantum technologies. However, the electrical characterisation of topological insulating states, non-local resistance, and bandgap tuning in atomically thin materials can be strongly affected by spurious signals arising from the measuring electronics. Common-mode voltages, dielectric leakage in the coaxial cables, and the limited input impedance of alternate-current amplifiers can mask the true nature of such high-impedance states. Here, we present an optical isolator circuit which grants access to such states by electrically decoupling the current-injection from the voltage-sensing circuitry. We benchmark our apparatus against two state-of-the-art measurements: the non-local resistance of a graphene Hall bar and the transfer characteristic of a WS2 field-effect transistor. Our system allows the quick characterisation of novel insulating states in two-dimensional materials with potential applications in future quantum technologies.

Alpha Particle Detection Using Alpha-Induced Air Radioluminescence: A Review and Future Prospects for Preliminary Radiological Characterisation for Nuclear Facilities Decommissioning

PubMed Central

Crompton, Anita J.; Jenkins, Alex

2018-01-01

The United Kingdom (UK) has a significant legacy of nuclear installations to be decommissioned over the next 100 years and a thorough characterisation is required prior to the development of a detailed decommissioning plan. Alpha radiation detection is notoriously time consuming and difficult to carry out due to the short range of alpha particles in air. Long-range detection of alpha particles is therefore highly desirable and this has been attempted through the detection of secondary effects from alpha radiation, most notably the air-radioluminescence caused by ionisation. This paper evaluates alpha induced air radioluminescence detectors developed to date and looks at their potential to develop a stand-off, alpha radiation detector which can be used in the nuclear decommissioning field in daylight conditions to detect alpha contaminated materials. PMID:29597340

[Spinocerebellar ataxia type 2 associated to pigmentary retinitis].

PubMed

Jiménez-Caballero, Pedro Enrique; Serviá, Mónica

2010-07-01

Ocular disorders are useful in the characterisation of the different types of spinocerebellar ataxias (SCA); pigmentary retinitis is an alteration that is specifically associated to SCA type 7 and is characterised by night blindness, sensitivity to glare and progressive narrowing of the visual field. A 34-year-old woman with clinical symptoms of progressive ataxia and visual impairment secondary to pigmentary retinitis. The patient had a personal history with an autosomal dominant pattern of a similar disorder in her father and paternal grandmother. In the genetic study she presented a triplet expansion in the SCA type 2 gene. CONCLUSIONS; Although pigmentary retinitis belongs to the SCA type 7 phenotype, our patient presented this retinal disorder, as in other cases of SCA type 2. A genetic study for SCA type 2 must therefore be conducted in patients with a degenerative ataxic clinical picture and who present evidence of pigmentary retinitis.

Molecular characterisation and nucleotide sequence analysis of canine parvovirus strains in vaccines in India.

PubMed

Nandi, Sukdeb; Anbazhagan, Rajendra; Kumar, Manoj

2010-01-01

Canine parvovirus 2 (CPV-2) is one of the most important viruses that causes haemorrhagic gastroenteritis and myocarditis of dogs worldwide. The picture has been complicated further due to the emergence of new mutants of CPV, namely: CPV-2a, CPV-2b and CPV-2c. In this study, the molecular characterisation of strains present in the CPV vaccines available on the Indian market was performed using polymerase chain reaction and DNA sequencing. The VP1/VP2 genes of two vaccine strains and a field strain (Bhopal) were sequenced and the nucleotide and the deduced amino acid sequences were compared. The results indicated that the isolate belonged to CPV type 2b and the strains in the vaccines belonged to type CPV-2. From the study, it is inferred that the CPV strain used in commercially available vaccine preparation differed from the strains present in CPV infection in dogs in India.

A homodyne detector integrated onto a photonic chip for measuring quantum states and generating random numbers

NASA Astrophysics Data System (ADS)

Raffaelli, Francesco; Ferranti, Giacomo; Mahler, Dylan H.; Sibson, Philip; Kennard, Jake E.; Santamato, Alberto; Sinclair, Gary; Bonneau, Damien; Thompson, Mark G.; Matthews, Jonathan C. F.

2018-04-01

Optical homodyne detection has found use as a characterisation tool in a range of quantum technologies. So far implementations have been limited to bulk optics. Here we present the optical integration of a homodyne detector onto a silicon photonics chip. The resulting device operates at high speed, up 150 MHz, it is compact and it operates with low noise, quantified with 11 dB clearance between shot noise and electronic noise. We perform on-chip quantum tomography of coherent states with the detector and show that it meets the requirements for characterising more general quantum states of light. We also show that the detector is able to produce quantum random numbers at a rate of 1.2 Gbps, by measuring the vacuum state of the electromagnetic field and applying off-line post processing. The produced random numbers pass all the statistical tests provided by the NIST test suite.

Model studies of the beam-filling error for rain-rate retrieval with microwave radiometers

NASA Technical Reports Server (NTRS)

Ha, Eunho; North, Gerald R.

1995-01-01

Low-frequency (less than 20 GHz) single-channel microwave retrievals of rain rate encounter the problem of beam-filling error. This error stems from the fact that the relationship between microwave brightness temperature and rain rate is nonlinear, coupled with the fact that the field of view is large or comparable to important scales of variability of the rain field. This means that one may not simply insert the area average of the brightness temperature into the formula for rain rate without incurring both bias and random error. The statistical heterogeneity of the rain-rate field in the footprint of the instrument is key to determining the nature of these errors. This paper makes use of a series of random rain-rate fields to study the size of the bias and random error associated with beam filling. A number of examples are analyzed in detail: the binomially distributed field, the gamma, the Gaussian, the mixed gamma, the lognormal, and the mixed lognormal ('mixed' here means there is a finite probability of no rain rate at a point of space-time). Of particular interest are the applicability of a simple error formula due to Chiu and collaborators and a formula that might hold in the large field of view limit. It is found that the simple formula holds for Gaussian rain-rate fields but begins to fail for highly skewed fields such as the mixed lognormal. While not conclusively demonstrated here, it is suggested that the notionof climatologically adjusting the retrievals to remove the beam-filling bias is a reasonable proposition.

Dual and mixed nonsymmetric stress-based variational formulations for coupled thermoelastodynamics with second sound effect

NASA Astrophysics Data System (ADS)

Tóth, Balázs

2018-03-01

Some new dual and mixed variational formulations based on a priori nonsymmetric stresses will be developed for linearly coupled irreversible thermoelastodynamic problems associated with second sound effect according to the Lord-Shulman theory. Having introduced the entropy flux vector instead of the entropy field and defining the dissipation and the relaxation potential as the function of the entropy flux, a seven-field dual and mixed variational formulation will be derived from the complementary Biot-Hamilton-type variational principle, using the Lagrange multiplier method. The momentum-, the displacement- and the infinitesimal rotation vector, and the a priori nonsymmetric stress tensor, the temperature change, the entropy field and its flux vector are considered as the independent field variables of this formulation. In order to handle appropriately the six different groups of temporal prescriptions in the relaxed- and/or the strong form, two variational integrals will be incorporated into the seven-field functional. Then, eliminating the entropy from this formulation through the strong fulfillment of the constitutive relation for the temperature change with the use of the Legendre transformation between the enthalpy and Gibbs potential, a six-field dual and mixed action functional is obtained. As a further development, the elimination of the momentum- and the velocity vector from the six-field principle through the a priori satisfaction of the kinematic equation and the constitutive relation for the momentum vector leads to a five-field variational formulation. These principles are suitable for the transient analyses of the structures exposed to a thermal shock of short temporal domain or a large heat flux.

Implementation of MEPDG for asphalt pavement with RAP.

DOT National Transportation Integrated Search

2013-06-01

This study explored the potential of using high reclaimed asphalt pavement (RAP) content with hot mix asphalt (HMA) in base and surface courses for conditions prevailing in Oklahoma. A total of eight Superpave mixes (four mixes for each of two field ...

Field verification process for open-graded HMAC mixes : final report.

DOT National Transportation Integrated Search

2002-07-01

The State of Oregon uses significant amounts of open-graded HMAC mixes as primary wearing courses on state highways. The primary materials design system for these mixes relies heavily on laboratory draindown to select the design asphalt content. Subs...

Effect of standing transverse acoustic oscillations on fuel-oxidant mixing in cylindrical combustion chambers

NASA Technical Reports Server (NTRS)

Mickelsen, William R

1957-01-01

Vapor fuel-oxidant mixing is analyzed for standing transverse acoustic fields simulating those existing in screeching or screaming combustors. The additional mixing due to the acoustic field is shown to be a function of sound pressure and frequency, stream velocity, and turbulence. The effects of these parameters are shown graphically for a realistic range of combustor conditions. The fuel-oxidant ratio at various combustor stations is shown to have a cyclic fluctuation which is in phase with the pressure fluctuations. Possible mechanisms contributing to screech and scream are discussed.

Higher-Order Squeezing of Quantum Field and the Generalized Uncertainty Relations in Non-Degenerate Four-Wave Mixing

NASA Technical Reports Server (NTRS)

Li, Xi-Zeng; Su, Bao-Xia

1996-01-01

It is found that the field of the combined mode of the probe wave and the phase-conjugate wave in the process of non-degenerate four-wave mixing exhibits higher-order squeezing to all even orders. And the generalized uncertainty relations in this process are also presented.

Feasibility of Using Unbound Mixed Recycled Aggregates from CDW over Expansive Clay Subgrade in Unpaved Rural Roads

PubMed Central

Del Rey, Isaac; Ayuso, Jesús; Galvín, Adela P.; Jiménez, José R.; Barbudo, Auxi

2016-01-01

Social awareness aims to increase practical skills, such as sustainable development, which seeks to increase the use of different types of waste in construction activities. Although insufficient attention is sometimes given to these actions, it is essential to spread information regarding new studies in the field of waste recycling, which encourages and promotes waste use. Reusing and recycling construction waste in the creation of buildings and infrastructure are fundamental strategies to achieving sustainability in the construction and engineering sectors. In this context, the concept of waste would no longer exist, as waste would become a material resource. Therefore, this study analyses the behaviours of two unbound mixed recycled aggregates (MRA) in the structural layers of an unpaved rural road with low traffic (category T43). The sections were built on inappropriate soil (A-7-6) with a high degree of free swelling. The experimental road consisted of three sections: the first was made with natural aggregates (NA) that were used as a control, the second was composed of MRA in the subbase and NA in the base, and the third section was completely composed of MRA. The materials were characterised in the laboratory. The behaviours of the structural layers in the experimental road were determined by controlling compaction (“in situ” density and moisture) and measuring the deflections and load capacity (deflectometer) during the 18 months after construction. The results show that the sections made with recycled aggregates meet the technical specifications required by General Technical Specifications for Road and Bridge Works (PG-3). Therefore, the water-soluble sulphate content and Los Angeles abrasion coefficient limits can be increased for recycled aggregates without compromising the quality of this type of road with low traffic. To the best of our knowledge, this is the first study regarding the use of unbound MRA made from construction and demolition waste (CDW) in the construction of an unpaved rural road with low traffic on an expansive clay subgrade. PMID:28774053

Simultaneous infection of Schistosoma mansoni and S. rodhaini in Biomphalaria glabrata: impact on chronobiology and cercarial behaviour

PubMed Central

Norton, Alice; Rollinson, David; Richards, Louisa; Webster, Joanne

2008-01-01

Background The chances of a schistosome cercaria encountering a suitable definitive host may be enhanced by emergence from the molluscan intermediate host with maximal glycogen stores and by an appropriate chronobiological rhythm. This study aimed to identify and characterize the effects of potential competitive interactions in the snail host Biomphalaria glabrata, between the closely-related Schistosoma mansoni and S. rodhaini, on phenotypic behavioural traits. It was predicted that inter-specific competition would affect chronobiological emergence rhythms and reduce the activity of schistosome swimming behavioural traits. Biomphalaria glabrata snails (120) were exposed to either S. mansoni or S. rodhaini single infections, or a mixed infection of both species simultaneously and the resulting cercarial phenotypic traits were characterised. Cercariae were identified from co-exposed snails by amplification and sequencing of the mitochondrial cytochrome oxidase subunit 1 (CO1). Results S. mansoni and S. rodhaini largely maintained their distinct chronobiological rhythms after mixed exposures and infections. However, inter-specific competition appeared to result in a restriction of the shedding pattern of S. rodhaini and slight shift in the shedding pattern of S. mansoni. Inter-specific competition also significantly lowered hourly cercarial production for both parasite species in comparison to single exposures and infections and reduced cercarial swimming activity. Conclusion Inter-specific competition was shown to influence cercarial production, chronobiology and activity and should therefore be investigated further in field situations to determine the effects of these changes on parasite fitness (incorporating both host finding and infectivity) where these two species overlap. Importantly this competition did not result in a large change in chronobiological emergence of cercariae for either species indicating that it would not have a large influence on the species of hosts available for infection at time of emergence. This study has furthermore demonstrated the potential for phenotypic measures to provide markers for species-specific identification even in conditions of co-infection. PMID:19055722

Electric Field Generation and Control of Bipartite Quantum Entanglement between Electronic Spins in Mixed Valence Polyoxovanadate [GeV14O40]8.

PubMed

Palii, Andrew; Aldoshin, Sergey; Tsukerblat, Boris; Borràs-Almenar, Juan José; Clemente-Juan, Juan Modesto; Cardona-Serra, Salvador; Coronado, Eugenio

2017-08-21

As part of the search for systems in which control of quantum entanglement can be achieved, here we consider the paramagnetic mixed valence polyoxometalate K 2 Na 6 [GeV 14 O 40 ]·10H 2 O in which two electrons are delocalized over the 14 vanadium ions. Applying a homogeneous electric field can induce an antiferromagnetic coupling between the two delocalized electronic spins that behave independently in the absence of the field. On the basis of the proposed theoretical model, we show that the external field can be used to generate controllable quantum entanglement between the two electronic spins traveling over a vanadium network of mixed valence polyoxoanion [GeV 14 O 40 ] 8- . Within a simplified two-level picture of the energy pattern of the electronic pair based on the previous ab initio analysis, we evaluate the temperature and field dependencies of concurrence and thus indicate that the entanglement can be controlled via the temperature, magnitude, and orientation of the electric field with respect to molecular axes of [GeV 14 O 40 ] 8- .

Bifurcation of potential vorticity gradients across the Southern Hemisphere stratospheric polar vortex

NASA Astrophysics Data System (ADS)

Conway, Jonathan; Bodeker, Greg; Cameron, Chris

2018-06-01

The wintertime stratospheric westerly winds circling the Antarctic continent, also known as the Southern Hemisphere polar vortex, create a barrier to mixing of air between middle and high latitudes. This dynamical isolation has important consequences for export of ozone-depleted air from the Antarctic stratosphere to lower latitudes. The prevailing view of this dynamical barrier has been an annulus compromising steep gradients of potential vorticity (PV) that create a single semi-permeable barrier to mixing. Analyses presented here show that this barrier often displays a bifurcated structure where a double-walled barrier exists. The bifurcated structure manifests as enhanced gradients of PV at two distinct latitudes - usually on the inside and outside flanks of the region of highest wind speed. Metrics that quantify the bifurcated nature of the vortex have been developed and their variation in space and time has been analysed. At most isentropic levels between 395 and 850 K, bifurcation is strongest in mid-winter and decreases dramatically during spring. From August onwards a distinct structure emerges, where elevated bifurcation remains between 475 and 600 K, and a mostly single-walled barrier occurs at other levels. While bifurcation at a given level evolves from month to month, and does not always persist through a season, interannual variations in the strength of bifurcation display coherence across multiple levels in any given month. Accounting for bifurcation allows the region of reduced mixing to be better characterised. These results suggest that improved understanding of cross-vortex mixing requires consideration of the polar vortex not as a single mixing barrier but as a barrier with internal structure that is likely to manifest as more complex gradients in trace gas concentrations across the vortex barrier region.

An Assessment of Southern Ocean Water Masses and Sea Ice During 1988-2007 in a Suite of Interannual CORE-II Simulations

NASA Technical Reports Server (NTRS)

Downes, Stephanie M.; Farneti, Riccardo; Uotila, Petteri; Griffies, Stephen M.; Marsland, Simon J.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne;

Studying relationships between environment and malaria incidence in Camopi (French Guiana) through the objective selection of buffer-based landscape characterisations

PubMed Central

2011-01-01

Background Malaria remains a major health problem in French Guiana, with a mean of 3800 cases each year. A previous study in Camopi, an Amerindian village on the Oyapock River, highlighted the major contribution of environmental features to the incidence of malaria attacks. We propose a method for the objective selection of the best multivariate peridomestic landscape characterisation that maximises the chances of identifying relationships between environmental features and malaria incidence, statistically significant and meaningful from an epidemiological point of view. Methods A land-cover map, the hydrological network and the geolocalised inhabited houses were used to characterise the peridomestic landscape in eleven discoid buffers with radii of 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 and 1000 metres. Buffer-based landscape characterisations were first compared in terms of their capacity to discriminate between sites within the geographic space and of their effective multidimensionality in variable space. The Akaike information criterion (AIC) was then used to select the landscape model best explaining the incidences of P. vivax and P. falciparum malaria. Finally, we calculated Pearson correlation coefficients for the relationships between environmental variables and malaria incidence, by species, for the more relevant buffers. Results The optimal buffers for environmental characterisation had radii of 100 m around houses for P. vivax and 400 m around houses for P. falciparum. The incidence of P. falciparum malaria seemed to be more strongly linked to environmental features than that of P. vivax malaria, within these buffers. The incidence of P. falciparum malaria in children was strongly correlated with proportions of bare soil (r = -0.69), land under high vegetation (r = 0.68) and primary forest (r = 0.54), landscape division (r = 0.48) and the number of inhabited houses (r = -0.60). The incidence of P. vivax malaria was associated only with landscape division (r = 0.49). Conclusions The proposed methodology provides a simple and general framework for objective characterisation of the landscape to account for field observations. The use of this method enabled us to identify different optimal observation horizons around houses, depending on the Plasmodium species considered, and to demonstrate significant correlations between environmental features and the incidence of malaria. PMID:22151738

Studying relationships between environment and malaria incidence in Camopi (French Guiana) through the objective selection of buffer-based landscape characterisations.

PubMed

Stefani, Aurélia; Roux, Emmanuel; Fotsing, Jean-Marie; Carme, Bernard

2011-12-13

Malaria remains a major health problem in French Guiana, with a mean of 3800 cases each year. A previous study in Camopi, an Amerindian village on the Oyapock River, highlighted the major contribution of environmental features to the incidence of malaria attacks. We propose a method for the objective selection of the best multivariate peridomestic landscape characterisation that maximises the chances of identifying relationships between environmental features and malaria incidence, statistically significant and meaningful from an epidemiological point of view. A land-cover map, the hydrological network and the geolocalised inhabited houses were used to characterise the peridomestic landscape in eleven discoid buffers with radii of 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 and 1000 metres. Buffer-based landscape characterisations were first compared in terms of their capacity to discriminate between sites within the geographic space and of their effective multidimensionality in variable space. The Akaike information criterion (AIC) was then used to select the landscape model best explaining the incidences of P. vivax and P. falciparum malaria. Finally, we calculated Pearson correlation coefficients for the relationships between environmental variables and malaria incidence, by species, for the more relevant buffers. The optimal buffers for environmental characterisation had radii of 100 m around houses for P. vivax and 400 m around houses for P. falciparum. The incidence of P. falciparum malaria seemed to be more strongly linked to environmental features than that of P. vivax malaria, within these buffers. The incidence of P. falciparum malaria in children was strongly correlated with proportions of bare soil (r = -0.69), land under high vegetation (r = 0.68) and primary forest (r = 0.54), landscape division (r = 0.48) and the number of inhabited houses (r = -0.60). The incidence of P. vivax malaria was associated only with landscape division (r = 0.49). The proposed methodology provides a simple and general framework for objective characterisation of the landscape to account for field observations. The use of this method enabled us to identify different optimal observation horizons around houses, depending on the Plasmodium species considered, and to demonstrate significant correlations between environmental features and the incidence of malaria. © 2011 Stefani et al; licensee BioMed Central Ltd.

A micromixer with consistent mixing performance for a wide range of flow rates.

PubMed

Goovaerts, Robert; Van Assche, Tom; Sonck, Marc; Denayer, Joeri; Desmet, Gert

2015-02-01

A micromixer with consistent mixing performance for a wide range of flow rates is presented. The mixer makes use of internally moving elements, i.e. steel balls that are located in dedicated mixing chambers. Movement is induced by a rotating magnetic field. To get better insight in differences between active and passive mixing, we studied a mixer that can operate in both regimes. A mixing performance study for a range of flow rates along with pressure drop data is presented. The response of the moving elements in regard to the magnetic field is shown experimentally and shows the limitations of earlier modeling studies. Lastly, the estimated power input on the fluids was calculated and allows for a comparison with more well-known convective-type mixers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrokinetically driven microfluidic mixing with patchwise surface heterogeneity and AC applied electric field

NASA Astrophysics Data System (ADS)

Luo, Win-Jet; Yue, Cheng-Feng

2004-12-01

This paper investigates two-dimensional, time-dependent electroosmotic flows driven by an AC electric field via patchwise surface heterogeneities distributed along the microchannel walls. The time-dependent flow fields through the microchannel are simulated for various patchwise heterogeneous surface patterns using the backwards-Euler time stepping numerical method. Different heterogeneous surface patterns are found to create significantly different electrokinetic transport phenomena. It is shown that the presence of oppositely charged surface heterogeneities on the microchannel walls results in the formation of localized flow circulations within the bulk flow. These circulation regions grow and decay periodically in accordance with the applied periodic AC electric field intensity. The circulations provide an effective means of enhancing species mixing in the microchannel. A suitable design of the patchwise heterogeneous surface pattern permits the mixing channel length and the retention time required to attain a homogeneous solution to be reduced significantly.

Effects of ionic concentration gradient on electroosmotic flow mixing in a microchannel.

PubMed

Peng, Ran; Li, Dongqing

2015-02-15

Effects of ionic concentration gradient on electroosmotic flow (EOF) mixing of one stream of a high concentration electrolyte solution with a stream of a low concentration electrolyte solution in a microchannel are investigated numerically. The concentration field, flow field and electric field are strongly coupled via concentration dependent zeta potential, dielectric constant and electric conductivity. The results show that the electric field and the flow velocity are non-uniform when the concentration dependence of these parameters is taken into consideration. It is also found that when the ionic concentration of the electrolyte solution is higher than 1M, the electrolyte solution essentially cannot enter the channel due to the extremely low electroosmotic flow mobility. The effects of the concentration dependence of zeta potential, dielectric constant and electric conductivity on electroosmotic flow mixing are studied. Copyright © 2014 Elsevier Inc. All rights reserved.

Multivariate statistical approach to estimate mixing proportions for unknown end members

USGS Publications Warehouse

Valder, Joshua F.; Long, Andrew J.; Davis, Arden D.; Kenner, Scott J.

2012-01-01

A multivariate statistical method is presented, which includes principal components analysis (PCA) and an end-member mixing model to estimate unknown end-member hydrochemical compositions and the relative mixing proportions of those end members in mixed waters. PCA, together with the Hotelling T2 statistic and a conceptual model of groundwater flow and mixing, was used in selecting samples that best approximate end members, which then were used as initial values in optimization of the end-member mixing model. This method was tested on controlled datasets (i.e., true values of estimates were known a priori) and found effective in estimating these end members and mixing proportions. The controlled datasets included synthetically generated hydrochemical data, synthetically generated mixing proportions, and laboratory analyses of sample mixtures, which were used in an evaluation of the effectiveness of this method for potential use in actual hydrological settings. For three different scenarios tested, correlation coefficients (R2) for linear regression between the estimated and known values ranged from 0.968 to 0.993 for mixing proportions and from 0.839 to 0.998 for end-member compositions. The method also was applied to field data from a study of end-member mixing in groundwater as a field example and partial method validation.

La prospection geothermique de surface au Maroc: hydrodynamisme, anomalies thermiques et indices de surfaceGeothermal prospecting in Morocco: hydrodynamics, thermal anomalies and surface indices

NASA Astrophysics Data System (ADS)

Zarhloule, Y.; Lahrache, A.; Ben Abidate, L.; Khattach, D.; Bouri, S.; Boukdir, A.; Ben Dhia, H.

2001-05-01

Shallow geothermal prospecting ( < 700 m) has been performed in four zones in Morocco for which few deep data are available: northwestern basin, northeastern basin, Tadla Basin and Agadir Basin. These areas are different geologically and hydrogeologically. The temperature data from 250 wells at depths between 15 and 500 m have been analysed in order to estimate the natural geothermal gradient in these areas, to determine the principal thermal anomalies, to identify the main thermal indices and to characterise the recharge, discharge and potential mixing limits of the aquifers. The hydrostratigraphical study of each basin revealed several potential reservoir layers in which the Turonian carbonate aquifer (Tadal and Agadir Basins) and Liassic acquifer (Moroccan northwestern and northeastern basins) are the most important hot water reservoirs in Morocco. The recharge zones of each aquifer are characterised by high topography, high water potential, shallow cold water, low geothermal gradient and negative anomalies. The discharge zones are characterized by low topography, low piezometric level, high geothermal gradient, high temperature with hot springs and positive anomalies. The main thermal indices and the principal thermal anomalies that coincide with the artesian zones of the Turonian and Liassic aquifers have been identified.

A rheological and microstructural characterisation of bigels for cosmetic and pharmaceutical uses.

PubMed

Lupi, Francesca R; Shakeel, Ahmad; Greco, Valeria; Oliviero Rossi, Cesare; Baldino, Noemi; Gabriele, Domenico

2016-12-01

Bigels are biphasic systems formed by water-based hydrogels and oil-based organogels, mainly studied, in the last few years, for pharmaceutical and cosmetic application focused on the controlled delivery of both lipophilic and hydrophilic active agents. The rheological properties of bigels depend on both the amount and the rheological characteristics of single structured phases. Moreover, it can be expected that, at large fractions of one of the starting gels, systems more complex than oil-in-water or water-in-oil can be obtained, yielding bicontinuous or matrix-in-matrix arrangement. Model bigels were investigated from a microstructural (i.e. microscopy and electrical conductivity tests) and rheological point of view. The hydrogel was prepared by using a low-methoxyl pectin whereas the organogel was prepared by using olive oil and, as gelator, a mixture of glyceryl stearate and policosanol. Model bigels were obtained by increasing the amount of organogel mixed with the hydrogel, and microstructural characterisation evidenced an organogel-in-hydrogel behaviour for all investigated samples, even though at the highest organogel content a more complex structure seems to arise. A semi-empirical model, based on theoretical equations developed for suspensions of elastic spheres in elastic media, was proposed to relate bigel rheological properties to single phase properties and fractions. Copyright © 2016 Elsevier B.V. All rights reserved.

A cross-sectional mixed methods study protocol to generate learning from patient safety incidents reported from general practice.

PubMed

Carson-Stevens, Andrew; Hibbert, Peter; Avery, Anthony; Butlin, Amy; Carter, Ben; Cooper, Alison; Evans, Huw Prosser; Gibson, Russell; Luff, Donna; Makeham, Meredith; McEnhill, Paul; Panesar, Sukhmeet S; Parry, Gareth; Rees, Philippa; Shiels, Emma; Sheikh, Aziz; Ward, Hope Olivia; Williams, Huw; Wood, Fiona; Donaldson, Liam; Edwards, Adrian

2015-12-01

Incident reports contain descriptions of errors and harms that occurred during clinical care delivery. Few observational studies have characterised incidents from general practice, and none of these have been from the England and Wales National Reporting and Learning System. This study aims to describe incidents reported from a general practice care setting. A general practice patient safety incident classification will be developed to characterise patient safety incidents. A weighted-random sample of 12,500 incidents describing no harm, low harm and moderate harm of patients, and all incidents describing severe harm and death of patients will be classified. Insights from exploratory descriptive statistics and thematic analysis will be combined to identify priority areas for future interventions. The need for ethical approval was waivered by the Aneurin Bevan University Health Board research risk review committee given the anonymised nature of data (ABHB R&D Ref number: SA/410/13). The authors will submit the results of the study to relevant journals and undertake national and international oral presentations to researchers, clinicians and policymakers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The vaginal microbiome during pregnancy and the postpartum period in a European population

PubMed Central

MacIntyre, David A.; Chandiramani, Manju; Lee, Yun S.; Kindinger, Lindsay; Smith, Ann; Angelopoulos, Nicos; Lehne, Benjamin; Arulkumaran, Shankari; Brown, Richard; Teoh, Tiong Ghee; Holmes, Elaine; Nicoholson, Jeremy K.; Marchesi, Julian R.; Bennett, Phillip R.

2015-01-01

The composition and structure of the pregnancy vaginal microbiome may influence susceptibility to adverse pregnancy outcomes. Studies on the pregnant vaginal microbiome have largely been limited to Northern American populations. Using MiSeq sequencing of 16S rRNA gene amplicons, we characterised the vaginal microbiota of a mixed British cohort of women (n = 42) who experienced uncomplicated term delivery and who were sampled longitudinally throughout pregnancy (8–12, 20–22, 28–30 and 34–36 weeks gestation) and 6 weeks postpartum. We show that vaginal microbiome composition dramatically changes postpartum to become less Lactobacillus spp. dominant with increased alpha-diversity irrespective of the community structure during pregnancy and independent of ethnicity. While the pregnancy vaginal microbiome was characteristically dominated by Lactobacillus spp. and low alpha-diversity, unlike Northern American populations, a significant number of pregnant women this British population had a L. jensenii-dominated microbiome characterised by low alpha-diversity. L. jensenii was predominantly observed in women of Asian and Caucasian ethnicity whereas L. gasseri was absent in samples from Black women. This study reveals new insights into biogeographical and ethnic effects upon the pregnancy and postpartum vaginal microbiome and has important implications for future studies exploring relationships between the vaginal microbiome, host health and pregnancy outcomes. PMID:25758319

Characterisation of the Subaquatic Groundwater Discharge That Maintains the Permanent Stratification within Lake Kivu; East Africa

PubMed Central

Ross, Kelly Ann; Gashugi, Elisée; Gafasi, Augustin; Wüest, Alfred; Schmid, Martin

2015-01-01

Warm and cold subaquatic groundwater discharge into Lake Kivu forms the large-scale density gradients presently observed in the lake. This structure is pertinent to maintaining the stratification that locks the high volume of gases in the deepwater. Our research presents the first characterisation of these inflows. Temperature and conductivity profiling was conducted from January 2010 to March 2013 to map the locations of groundwater discharge. Water samples were obtained within the lake at the locations of the greatest temperature anomalies observed from the background lake-profile. The isotopic and chemical signatures of the groundwater were applied to assess how these inflows contribute to the overall stratification. It is inferred that Lake Kivu’s deepwater has not been completely recharged by the groundwater inflows since its turnover that is speculated to have occurred within the last ~1000 yrs. Given a recent salinity increase in the lake constrained to within months of seismic activity measured beneath the basin, it is plausible that increased hydrothermal-groundwater inflows into the deep basin are correlated with episodic geologic events. These results invalidate the simple two-component end-member mixing regime that has been postulated up to now, and indicate the importance of monitoring this potentially explosive lake. PMID:25799098

The juxtamembrane regions of human receptor tyrosine kinases exhibit conserved interaction sites with anionic lipids

PubMed Central

Hedger, George; Sansom, Mark S. P.; Koldsø, Heidi

2015-01-01

Receptor tyrosine kinases (RTKs) play a critical role in diverse cellular processes and their activity is regulated by lipids in the surrounding membrane, including PIP2 (phosphatidylinositol-4,5-bisphosphate) in the inner leaflet, and GM3 (monosialodihexosylganglioside) in the outer leaflet. However, the precise details of the interactions at the molecular level remain to be fully characterised. Using a multiscale molecular dynamics simulation approach, we comprehensively characterise anionic lipid interactions with all 58 known human RTKs. Our results demonstrate that the juxtamembrane (JM) regions of RTKs are critical for inducing clustering of anionic lipids, including PIP2, both in simple asymmetric bilayers, and in more complex mixed membranes. Clustering is predominantly driven by interactions between a conserved cluster of basic residues within the first five positions of the JM region, and negatively charged lipid headgroups. This highlights a conserved interaction pattern shared across the human RTK family. In particular predominantly the N-terminal residues of the JM region are involved in the interactions with PIP2, whilst residues within the distal JM region exhibit comparatively less lipid specificity. Our results suggest that JM–lipid interactions play a key role in RTK structure and function, and more generally in the nanoscale organisation of receptor-containing cell membranes. PMID:25779975

Additional asphalt to increase the durability of Virginia's superpave surface mixes.

DOT National Transportation Integrated Search

2003-01-01

Although Superpave has been successful in preventing rutting, many believe that the design asphalt content needs fine-tuning to produce durable mixes. This investigation used various laboratory tests to test samples of field surface mixes (12.5 mm an...

Balanced RAP/RAS mix design and performance evaluation for project - specific service conditions.

DOT National Transportation Integrated Search

2013-01-01

This presentation summarizes Projects 0-6092/0-6614. It includes accomplishments, best practices, field performance data of RAP/RAS test sections, balanced RAP/RAS mix design for project-specific conditions, and approaches for improving RAP/RAS mix p...

The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

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

Walsh, D. A., E-mail: david.walsh@stfc.ac.uk; Snedden, E. W.; Jamison, S. P.

The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immunemore » to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.« less

Extended parametric gain range in photonic crystal fibers with strongly frequency-dependent field distributions.

PubMed

Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

2014-08-15

The parametric gain range of a degenerate four-wave mixing process is determined in the undepleted pump regime. The gain range is considered with and without taking the mode field distributions of the four-wave mixing components into account. It is found that the mode field distributions have to be included to evaluate the parametric gain correctly in dispersion-tailored speciality fibers and that mode profile engineering can provide a way to increase the parametric gain range.

Entrainment and mixing in thrust augmenting ejectors

NASA Technical Reports Server (NTRS)

Bernal, L.; Sarohia, V.

1983-01-01

An experimental investigation of two-dimensional thrust augmenting ejector flows has been conducted. Measurements of the shroud surface pressure distribution, mean velocity, turbulent intensities and Reynolds stresses were made in two shroud geometries at various primary nozzle pressure ratios. The effects of shroud geometry and primary nozzle pressure ratio on the shroud surface pressure distribution, mean flow field and turbulent field were determined. From these measurements the evolution of mixing within the shroud of the primary flow and entrained fluid was obtained. The relationship between the mean flow field, the turbulent field and the shroud surface pressure distribution is discussed.

Statistical characterisation of COSMO Sky-Med X-SAR retrieved precipitation fields by scale-invariance analysis

NASA Astrophysics Data System (ADS)

Deidda, Roberto; Mascaro, Giuseppe; Hellies, Matteo; Baldini, Luca; Roberto, Nicoletta

2013-04-01

COSMO Sky-Med (CSK) is an important programme of the Italian Space Agency aiming at supporting environmental monitoring and management of exogenous, endogenous and anthropogenic risks through X-band Synthetic Aperture Radar (X-SAR) on board of 4 satellites forming a constellation. Most of typical SAR applications are focused on land or ocean observation. However, X-band SAR can be detect precipitation that results in a specific signature caused by the combination of attenuation of surface returns induced by precipitation and enhancement of backscattering determined by the hydrometeors in the SAR resolution volume. Within CSK programme, we conducted an intercomparison between the statistical properties of precipitation fields derived by CSK SARs and those derived by the CNR Polar 55C (C-band) ground based weather radar located in Rome (Italy). This contribution presents main results of this research which was aimed at the robust characterisation of rainfall statistical properties across different scales by means of scale-invariance analysis and multifractal theory. The analysis was performed on a dataset of more two years of precipitation observations collected by the CNR Polar 55C radar and rainfall fields derived from available images collected by the CSK satellites during intense rainfall events. Scale-invariance laws and multifractal properties were detected on the most intense rainfall events derived from the CNR Polar 55C radar for spatial scales from 4 km to 64 km. The analysis on X-SAR retrieved rainfall fields, although based on few images, leaded to similar results and confirmed the existence of scale-invariance and multifractal properties for scales larger than 4 km. These outcomes encourage investigating SAR methodologies for future development of meteo-hydrological forecasting models based on multifractal theory.

Characterisation of recirculation zones in complex terrain using multi-lidar measurements

NASA Astrophysics Data System (ADS)

Menke, R.; Mann, J.; Vasiljevic, N.

2017-12-01

Wind fields in complex terrain show a higher complexity compared to sites with simpler geometries. It is imperative to understand well the characteristics of complex flows to account for them during the site validation to ensure the wind turbines can withstand the local flow conditions. This study focuses on the description of recirculation zones occurring on lee sides of hills. The flow recirculation can have a significant impact on the success of wind energy projects since it represents one of the main contributors to the turbulence generation. An extensive dataset of observation of flow over complex terrain is available from the Perdigão 2017 field campaign (https://www.nature.com/news/world-s-largest-wind-mapping-project-spins-up-in-portugal-1.21481). A setup of 8 long-range WindScanners (Vasiljević et al., 2016), scanning lidars deployed by DTU performed RHI scans at several positions along two parallel ridges probing the flow field in two vertical planes, in addition data from several meteorological masts is available. With the above-mentioned lidar setup we achieved simultaneous dual-Doppler scans of the recirculation zone at three positions and simultaneous observations of recirculation behind two parallel ridges. Methods are developed to identify and define the extent of recirculation bubbles. Different parameters are defined to characterise the dimensions of the recirculation zone. The change of these parameters along the ridges is studied. In particular, the impact of atmospheric stability and the changes of the wind field at the position of the downwind ridge are investigated. Furthermore, the geometry of the recirculation zone for different wind directions and in connection to the upstream wind conditions is investigated.

Characterisation of a plastic scintillation detector to be used in a multicentre stereotactic radiosurgery dosimetry audit

NASA Astrophysics Data System (ADS)

Dimitriadis, A.; Patallo, I. Silvestre; Billas, I.; Duane, S.; Nisbet, A.; Clark, C. H.

2017-11-01

Scintillation detectors are considered highly suitable for dosimetric measurement of small fields in radiotherapy due to their near-tissue equivalence and their small size. A commercially available scintillation detector, the Exradin W1 (Standard Imaging, Middleton, USA), has been previously characterised by two independent studies (Beierholm et al., 2014; Carrasco et al., 2015a, 2015b) but the results from these publications differed in some aspects (e.g. energy dependence, long term stability). The respective authors highlighted the need for more studies to be published (Beierholm et al., 2015; Carrasco et al., 2015a, 2015b). In this work, the Exradin W1 was characterised in terms of dose response, dependence on dose rate, energy, temperature and angle of irradiation, and long-term stability. The observed dose linearity, short-term repeatability and temperature dependence were in good agreement with previously published data. Appropriate corrections should therefore be applied, where possible, in order to achieve measurements with low-uncertainty. The angular dependence was characterised along both the symmetrical and polar axis of the detector for the first time in this work and a dose variation of up to 1% was observed. The response of the detector was observed to decrease at a rate of approximately 1.6% kGy-1 for the first 5 kGy delivered, and then stabilised to 0.2% kGy-1 in the subsequent 20 kGy. The main goal of this work was to assess the suitability of the Exradin W1 for use in dose verification measurements for stereotactic radiosurgery. The results obtained confirm that the detector is suitable for use in such situations. The detector is now utilised in a multi-centre stereotactic radiosurgery dosimetric audit, with the application of appropriate correction factors.

Characterisation of ALS genes in the polyploid species Schoenoplectus mucronatus and implications for resistance management.

PubMed

Scarabel, Laura; Locascio, Antonella; Furini, Antonella; Sattin, Maurizio; Varotto, Serena

2010-03-01

The polyploid weed Schoenoplectus mucronatus (L.) Palla has evolved target-site resistance to ALS-inhibiting herbicides in Italian rice crops. Molecular and genetic characterisation of the resistance mechanism is relevant to the evolution and management of herbicide resistance. The authors aimed (a) to study the organisation of the target-site loci in two field-selected S. mucronatus populations with different cross-resistance patterns, (b) to identify the mutations endowing resistance to ALS inhibitors and determine the role of these mutations by using transgenesis and (c) to analyse the implications for the management of the S. mucronatus populations. Two complete ALS genes (ALS1 and ALS2) having an intron and a third partial intronless ALS gene (ALS3) were identified. The presence of multiple ALS genes was confirmed by Southern blot analyses, and ALS loci were characterised by examining cytosine methylation. In S. mucronatus leaves, the transcripts of ALS1, ALS2 and ALS3 were detected. Two mutations endowing resistance (Pro(197) to His and Trp(574) to Leu) were found in both resistant populations, but at different frequencies. Tobacco plants transformed with the two resistant alleles indicated that the Pro(197)-to-His substitution conferred resistance to SU and TP herbicides, while the allele with the Trp(574)-to-Leu substitution conferred cross-resistance to SU, TP, IMI and PTB herbicides. Schoenoplectus mucronatus has multiple ALS genes characterised by methylated sites that can influence the expression profile. The two mutated alleles proved to be responsible for ALS resistance. At population level, the resistance pattern depends on the frequency of various resistant genotypes, and this influences the efficacy of various ALS-inhibiting herbicides.

Large-scale deployment of the Global Trigger Tool across a large hospital system: refinements for the characterisation of adverse events to support patient safety learning opportunities.

PubMed

Good, V S; Saldaña, M; Gilder, R; Nicewander, D; Kennerly, D A

2011-01-01

The Institute for Healthcare Improvement encourages use of the Global Trigger Tool to objectively determine and monitor adverse events (AEs). Baylor Health Care System (BHCS) is an integrated healthcare delivery system in North Texas. The Global Trigger Tool was applied to BHCS's eight general acute care hospitals, two inpatient cardiovascular hospitals and two rehabilitation/long-term acute care hospitals. Data were collected from a monthly random sample of charts for each facility for patients discharged between 1 July 2006 and 30 June 2007 by external professional nurse auditors using an MS Access Tool developed for this initiative. In addition to the data elements recommended by Institute for Healthcare Improvement, BHCS developed fields to permit further characterisation of AEs to identify learning opportunities. A structured narrative description of each identified AE facilitated text mining to further characterise AEs. INITIAL FINDINGS: Based on this sample, AE rates were found to be 68.1 per 1000 patient days, or 50.8 per 100 encounters, and 39.8% of admissions were found to have ≥1 AE. Of all AEs identified, 61.2% were hospital-acquired, 10.1% of which were associated with a National Coordinating Council - Medical Error Reporting and Prevention harm score of "H or I" (near death or death). To enhance learning opportunities and guide quality improvement, BHCS collected data-such as preventability and AE source-to characterise the nature of AEs. Data are provided regularly to hospital teams to direct quality initiatives, moving from a general focus on reducing AEs to more specific programmes based on patterns of harm and preventability.

Electrokinetic effects on motion of submicron particles in microchannel

NASA Astrophysics Data System (ADS)

Sato, Yohei; Hishida, Koichi

2006-11-01

Two-fluid mixing utilizing electrokinetically driven flow in a micro-channel is investigated by micron-resolution particle image velocimetry and an image processing technique. Submicron particles are transported and mixed with deionized water by electrophoresis. The particle electrophoretic velocity that is proportional to an applied electric field is measured in a closed cell, which is used to calculate the electroosmotic flow velocity. At a constant electric field, addition of pressure-driven flow to electrokinetically driven flow in a T-shaped micro-channel enhances two-fluid mixing because the momentum flux is increased. On the other hand, on application of an alternative sinusoidal electric field, the velocity difference between pressure-driven and electroosmotic flows has a significant effect on increasing the length of interface formed between two fluids. It is concluded from the present experiments that the transport and mixing process in the micro-channel will be enhanced by accurate flow-rate control of both pressure-driven and electroosmotic flows.

Simulations of Heterogeneous Detonations and Post Detonation Turbulent Mixing and Afterburning

NASA Astrophysics Data System (ADS)

Menon, Suresh; Gottiparthi, Kalyana

2011-06-01

Most metal-loaded explosives and thermobaric explosives exploit the afterburning of metals to maintain pressure and temperature conditions.The use of such explosives in complex environment can result in post detonation flow containing many scales of vortical motion, flow jetting and shear, as well as plume-surface interactions due to flow impingement and wall flows. In general, all these interactions can lead to highly turbulent flow fields even if the initial ambient conditions were quiescent. Thus, turbulent mixing can dominate initial mixing and impact the final afterburn. We conduct three-dimensional numerical simulations of the propagation of detonation resulting from metal-loaded (inert or reacting) explosives and analyze the afterburn process as well as the generation of multiple scales of mixing in the post detonation flow field. Impact of the detonation and post-detonation flow field on solid surface is also considered for a variety of initial conditions. Comparison with available data is carried out to demonstrate validity of the simulation method. Supported by Defense Threat Reduction Agency

Turbulent Mixing at the Edge of a Cloud

NASA Astrophysics Data System (ADS)

Shaw, Raymond; Beals, Matthew; Fugal, Jacob; Kumar, Bipin; Lu, Jiang; Schumacher, Joerg; Stith, Jeffrey

2013-11-01

Numerical and field experiments have been brought to bear on the question of how atmospheric clouds respond when they experience turbulent mixing with their environment. Simply put, we ask when a cloud is diluted, do all droplets evaporate uniformly (homogeneous mixing) or does a subset of droplets evaporate completely, leaving the remaining droplets unaffected (inhomogeneous mixing)? First, the entrainment of clear air and its subsequent mixing with a filament of cloudy air is studied in DNS that combine the Eulerian description of the turbulent velocity, temperature and vapor fields with a Lagrangian cloud droplet ensemble. The simulations provide guidance on the proper definition of the thermodynamic response time for the Damkoehler number, and demonstrate the transition from inhomogeneous to homogeneous mixing as mixing progresses within the inertial subrange. Second, an airborne digital holographic instrument (Holodec) shows that cloud edges are inhomogeneous at the centimeter scales. In local cloud volumes the droplet size distribution fluctuates strongly in number density but with a nearly unchanging mean droplet diameter, until the fluctuations finally cascade to the centimeter scale, when the droplet diameter begins to respond.

Compaction and measurement of field density for Oregon open-graded (F-MIX) asphalt pavement

DOT National Transportation Integrated Search

1999-06-01

A research project conducted by Oregon State University (OSU) and the Oregon Department of Transportation (ODOT) investigated compaction of Oregon F-mix asphalt pavement, an open-graded mix with 25-mm maximum size aggregate and air voids typically in...

Aberrant epithelial GREM1 expression initiates colonic tumorigenesis from cells outside of the crypt base stem cell niche

PubMed Central

Bansal, Mukesh; Rafferty, Hannah; Boitsova, Tatjana; Bardella, Chiara; Jaeger, Emma; Lewis, Annabelle; Freeman-Mills, Luke; Giner, Francesc Castro; Rodenas-Cuadrado, Pedro; Mallappa, Sreelakshmi; Clark, Susan; Thomas, Huw; Jeffery, Rosemary; Poulsom, Richard; Rodriguez-Justo, Manuel; Novelli, Marco; Chetty, Runjan; Silver, Andrew; Sansom, Owen James; Greten, Florian R; Wang, Lai Mun; East, James Edward; Tomlinson, Ian; Leedham, Simon John

2015-01-01

Hereditary mixed polyposis syndrome (HMPS) is characterised by the development of mixed morphology colorectal tumours and is caused by a 40 kb duplication that results in aberrant epithelial expression of the mesenchymal Bone Morphogenetic Protein antagonist, GREM1. Here we use HMPS tissue and a mouse model of the disease to show that epithelial GREM1 disrupts homeostatic intestinal morphogen gradients, altering cell-fate, that is normally determined by position along the vertical epithelial axis. This promotes the persistence and/or reacquisition of stem-cell properties in Lgr5 negative (non-expressing) progenitor cells that have exited the stem-cell niche. These cells form ectopic crypts, proliferate, accumulate somatic mutations and can initiate intestinal neoplasia, indicating that the crypt base stem-cell is not the sole cell-of-origin of colorectal cancer. Furthermore, we show that epithelial expression of GREM1 also occurs in traditional serrated adenomas, sporadic pre-malignant lesions with a hitherto unknown pathogenesis and these lesions can be considered the sporadic equivalents of HMPS polyps. PMID:25419707

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation

PubMed Central

Casado-Coterillo, Clara; López-Guerrero, María del Mar; Irabien, Ángel

2014-01-01

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials. PMID:24957178

Large-Eddy-Simulation of a flow over a submerged rigid canopy

NASA Astrophysics Data System (ADS)

Monti, Alessandro; Omidyeganeh, Mohammad; Pinelli, Alfredo

2017-11-01

We have performed a wall-resolved Large-Eddy-Simulation of flow over a shallow submerged rigid canopy (H / h = 4 ; H and h are the open channel and the canopy heights respectively) in a transitional/dense regime (Nepf ARFM 44, 2011), at low Reynolds number (Reb =Ubulk H / ν = 6000). An immersed boundary method (Favier et al. JCP 261, 2013) has been adopted to represent filamentous rigid elements of the canopy. The presence of the permeable and porous canopy induces a typical inflection point in the mean velocity profile, depicting two separated and developed layers, outer boundary layer and in-canopy uniform flow. The aim of the work is to explore and unravel the mechanisms of the interaction between the fluid flow and the rigid canopy by identifying the physical parameters that govern the mixing mechanisms within the different flow layers and by exploring the impact of the sweep/ejection events at the canopy edge. The results show that the flow is characterised by large scale stream- and span-wise vortices and regions of different dynamics that affect also the filamentous layer, hence the mixing mechanisms.

Porous poly-ether ether ketone (PEEK) manufactured by a novel powder route using near-spherical salt bead porogens: characterisation and mechanical properties.

PubMed

Siddiq, Abdur R; Kennedy, Andrew R

2015-02-01

Porous PEEK structures with approximately 85% open porosity have been made using PEEK-OPTIMA® powder and a particulate leaching technique using porous, near-spherical, sodium chloride beads. A novel manufacturing approach is presented and compared with a traditional dry mixing method. Irrespective of the method used, the use of near-spherical beads with a fairly narrow size range results in uniform pore structures. However the integration, by tapping, of fine PEEK into a pre-existing network salt beads, followed by compaction and "sintering", produces porous structures with excellent repeatability and homogeneity of density; more uniform pore and strut sizes; an improved and predictable level of connectivity via the formation of "windows" between the cells; faster salt removal rates and lower levels of residual salt. Although tapped samples show a compressive yield stress >1 MPa and stiffness >30 MPa for samples with 84% porosity, the presence of windows in the cell walls means that tapped structures show lower strengths and lower stiffnesses than equivalent structures made by mixing. Copyright © 2014 Elsevier B.V. All rights reserved.

Dietary Behaviours, Impulsivity and Food Involvement: Identification of Three Consumer Segments

PubMed Central

Sarmugam, Rani; Worsley, Anthony

2015-01-01

This study aims to (1) identify consumer segments based on consumers’ impulsivity and level of food involvement, and (2) examine the dietary behaviours of each consumer segment. An Internet-based cross-sectional survey was conducted among 530 respondents. The mean age of the participants was 49.2 ± 16.6 years, and 27% were tertiary educated. Two-stage cluster analysis revealed three distinct segments; “impulsive, involved” (33.4%), “rational, health conscious” (39.2%), and “uninvolved” (27.4%). The “impulsive, involved” segment was characterised by higher levels of impulsivity and food involvement (importance of food) compared to the other two segments. This segment also reported significantly more frequent consumption of fast foods, takeaways, convenience meals, salted snacks and use of ready-made sauces and mixes in cooking compared to the “rational, health conscious” consumers. They also reported higher frequency of preparing meals at home, cooking from scratch, using ready-made sauces and mixes in cooking and higher vegetable consumption compared to the “uninvolved” consumers. The findings show the need for customised approaches to the communication and promotion of healthy eating habits. PMID:26393649

Dietary Behaviours, Impulsivity and Food Involvement: Identification of Three Consumer Segments.

PubMed

Sarmugam, Rani; Worsley, Anthony

2015-09-18

This study aims to (1) identify consumer segments based on consumers' impulsivity and level of food involvement, and (2) examine the dietary behaviours of each consumer segment. An Internet-based cross-sectional survey was conducted among 530 respondents. The mean age of the participants was 49.2 ± 16.6 years, and 27% were tertiary educated. Two-stage cluster analysis revealed three distinct segments; "impulsive, involved" (33.4%), "rational, health conscious" (39.2%), and "uninvolved" (27.4%). The "impulsive, involved" segment was characterised by higher levels of impulsivity and food involvement (importance of food) compared to the other two segments. This segment also reported significantly more frequent consumption of fast foods, takeaways, convenience meals, salted snacks and use of ready-made sauces and mixes in cooking compared to the "rational, health conscious" consumers. They also reported higher frequency of preparing meals at home, cooking from scratch, using ready-made sauces and mixes in cooking and higher vegetable consumption compared to the "uninvolved" consumers. The findings show the need for customised approaches to the communication and promotion of healthy eating habits.

A new look at the robust control of discrete-time Markov jump linear systems

NASA Astrophysics Data System (ADS)

Todorov, M. G.; Fragoso, M. D.

2016-03-01

In this paper, we make a foray in the role played by a set of four operators on the study of robust H2 and mixed H2/H∞ control problems for discrete-time Markov jump linear systems. These operators appear in the study of mean square stability for this class of systems. By means of new linear matrix inequality (LMI) characterisations of controllers, which include slack variables that, to some extent, separate the robustness and performance objectives, we introduce four alternative approaches to the design of controllers which are robustly stabilising and at the same time provide a guaranteed level of H2 performance. Since each operator provides a different degree of conservatism, the results are unified in the form of an iterative LMI technique for designing robust H2 controllers, whose convergence is attained in a finite number of steps. The method yields a new way of computing mixed H2/H∞ controllers, whose conservatism decreases with iteration. Two numerical examples illustrate the applicability of the proposed results for the control of a small unmanned aerial vehicle, and for an underactuated robotic arm.

Chirp mixing

NASA Astrophysics Data System (ADS)

Khaneja, Navin

2018-07-01

In this paper, we develop the theory of chirp mixing in NMR spectroscopy. The working principle is simple, given coupled homonuclear spins with offsets in range [ - B, B ] , we adiabatically sweep through the resonances. This achieves cross polarization between the z magnetization of the coupled spins. We repeat this basic operation many times with a supercycle to achieve appropriate mixing time. When we sweep through the resonances, midway between the resonances of the coupled spin I and S, the effective field seen by two spins is the same and hence they precess at same frequency around their effective fields. This means the coupling, which normally gets averaged out due to the chemical shift difference is no more averaged out for a short time and we get mixing. In this paper, we develop these basic ideas. By virtue of its design, the chirp mixing is much more broadband compared to state of the art methods. The proposed methodology is demonstrated on 13 C mixing in a sample of Alanine.

Rapid micromixer via ferrofluids

NASA Astrophysics Data System (ADS)

Fu, L. M.; Tsai, C. H.; Leong, K. P.; Wen, C. Y.

Performances of a micromixer based on ferrofluids are predicted numerically. A permanent magnet is used to induce transient interactive flows between a water-based ferrofluid and water. The external magnetic field causes the ferrofluid to expand significantly and uniformly toward miscible water, associated with a great number of extremely fine fingering structures on the interface in the upstream and downstream regions of the microchannel. These pronounced fingering patterns, which mimic the experimental observations of Wen et al. (2009), increase the mixing interfacial length dramatically. Along with the dominant diffusion effects occurring around the circumferential regions of the fine finger structures, the mixing efficiency increases significantly. The mixing efficiency can be as high as 95% within 2.0 s and a distance of 3.0 mm from the inlet of the mixing channel, when the applied peak magnetic field is 145.8 Oe. The proposed mixing scheme not only provides an excellent mixing, even in simple microchannel, but also can be easily applied to lab-on-a-chip applications with an external permanent magnet.

Exploring the Ice Giants with JWST

NASA Astrophysics Data System (ADS)

Orton, Glenn S.; Fletcher, Leigh; Hammel, Heidi B.; Melin, Henrik; Guerlet, Sandrine; Greathouse, Thomas K.; Irwin, Patrick GJ

2017-06-01

The Ice Giants Uranus and Neptune are among the least-explored environments in our Solar System, having been visited only once, by Voyager 2 in 1986 and 1989, respectively. Their bulk properties and composition, intermediate between the hydrogen-rich gas giants and the smaller terrestrial worlds, make them representative of a planetary class that may be commonplace in other planetary systems. Furthermore, their small angular diameter, low atmospheric temperatures, and dynamic and ever-changing atmospheres make them tantalising infrared targets for JWST. This presentation will reveal the scientific rationale and requirements for a long-term program of JWST spectroscopic mapping of these two worlds. Specifically, the MIRI instrument can be used to determine the 3-dimensional temperature structure to understand (i) seasonal atmospheric circulation from the equator to the poles, (ii) the relation between temperatures, visible atmospheric banding and storm phenomena; and (iii) to discover the unknown circulations and wave phenomena shaping their middle atmospheres. JWST spectra will also allow us to search for and map chemical species produced from photochemistry (e.g., hydrocarbons derived from methane photolysis), from vertical mixing (e.g., disequilibrium species), and from external sources (e.g., HCN and oxygen compounds delivered by comets, ring rain and interplanetary dust). Furthermore, near-infrared imaging and spectroscopy with NIRCAM and NIRSpec will provide detailed characterisations of ice-giant cloud and haze formation and their evolution with time, as well as revealing how auroral processes (observed via H3+ emission) influence the middle atmosphere. JWST will not only enable intercomparison of these atmospheric processes on two very different worlds (Uranus with its extreme tilt and sluggish mixing; Neptune with its powerful internal heat source), but also mature our understanding of how ice giant phenomena compare to both gas giant and terrestrial atmospheric processes. We propose that preliminary mapping observations from the GTO programme will initiate a long-term programme of ice giant characterisation over the duration of JWST’s lifetime.

Variation in cervical and breast cancer screening coverage in England: a cross-sectional analysis to characterise districts with atypical behaviour.

PubMed

Massat, Nathalie J; Douglas, Elaine; Waller, Jo; Wardle, Jane; Duffy, Stephen W

2015-07-24

Reducing cancer screening inequalities in England is a major focus of the 2011 Department of Health cancer outcome strategy. Screening coverage requires regular monitoring in order to implement targeted interventions where coverage is low. This study aimed to characterise districts with atypical coverage levels for cervical or breast screening. Observational study of district-level coverage in the English Cervical and Breast screening programmes in 2012. England, UK. All English women invited to participate in the cervical (age group 25-49 and 50-64) and breast (age group 50-64) screening programmes. Risk adjustment models for coverage were developed based on district-level characteristics. Funnel plots of adjusted coverage were constructed, and atypical districts examined by correlation analysis. Variability in coverage was primarily explained by population factors, whereas general practice characteristics had little independent effect. Deprivation and ethnicity other than white, Asian, black or mixed were independently associated with poorer coverage in both screening programmes, with ethnicity having the strongest effect; by comparison, the influence of Asian, black or mixed ethnic minority was limited. Deprivation, ethnicity and urbanisation largely accounted for the lower cervical screening coverage in London. However, for breast screening, being located in London remained a strong negative predictor. A subset of districts was identified as having atypical coverage across programmes. Correlates of deprivation in districts with relatively low adjusted coverage were substantially different from overall correlates of deprivation. These results inform the continuing drive to reduce avoidable cancer deaths in England, and encourage implementation of targeted interventions in communities residing in districts identified as having atypically low coverage. Sequential implementation to monitor the impact of local interventions would help accrue evidence on 'what works'. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Theoretical Studies of Strongly Interacting Fine Particle Systems

NASA Astrophysics Data System (ADS)

Fearon, Michael

Available from UMI in association with The British Library. A theoretical analysis of the time dependent behaviour of a system of fine magnetic particles as a function of applied field and temperature was carried out. The model used was based on a theory assuming Neel relaxation with a distribution of particle sizes. This theory predicted a linear variation of S_{max} with temperature and a finite intercept, which is not reflected by experimental observations. The remanence curves of strongly interacting fine-particle systems were also investigated theoretically. It was shown that the Henkel plot of the dc demagnetisation remanence vs the isothermal remanence is a useful representation of interactions. The form of the plot was found to be a reflection of the magnetic and physical microstructure of the material, which is consistent with experimental data. The relationship between the Henkel plot and the noise of a particulate recording medium, another property dependent on the microstructure, is also considered. The Interaction Field Factor (IFF), a single parameter characterising the non-linearity of the Henkel plot, is investigated. These results are consistent with a previous experimental study. Finally the results of the noise power spectral density for erased and saturated recording media are presented, so that characterisation of interparticle interactions may be carried out with greater accuracy.

Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971.

PubMed

Holovachov, Oleksandr

2015-05-01

Three known and two new species of Leptolaimoides are described from bottom sediments collected in Skagerrak off the west coast of Sweden. The following known species are redescribed: Leptolaimoides haploopis Jensen, 1978, L. tubulosus Vitiello, 1971 and L. hexatubulosus Hoang Lai-Phu et al., 2009. Leptolaimoides filicaudatus sp. n. is characterised by the 431-543 µm long body; cephalic sensilla papilliform; amphid 23-26 µm long, located 9-10 µm from anterior end; first body pore located 35-37 µm from anterior end; lateral field simple along most of body, areolated on tail, arising 36-40 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male without tubular and without alveolar supplements; spicules arcuate and 16 µm long. Leptolaimoides leptomicron sp. n. is characterised by the 776-847 µm long body; cephalic sensilla papilliform; amphid 15-17 µm long, located 9-13 µm from anterior end; first body pore located 40-46 µm from anterior end; lateral field areolated, arising 26-28 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with three tubular and without alveolar supplements, spicules arcuate and 28-29 µm long. The diagnosis of the genus Leptolaimoides is emended and a tabular compendium and dichotomous identification key to species of the genus Leptolaimoides are provided.

Coherent Microwave-to-Optical Conversion via Six-Wave Mixing in Rydberg Atoms

NASA Astrophysics Data System (ADS)

Han, Jingshan; Vogt, Thibault; Gross, Christian; Jaksch, Dieter; Kiffner, Martin; Li, Wenhui

2018-03-01

We present an experimental demonstration of converting a microwave field to an optical field via frequency mixing in a cloud of cold 87Rb atoms, where the microwave field strongly couples to an electric dipole transition between Rydberg states. We show that the conversion allows the phase information of the microwave field to be coherently transferred to the optical field. With the current energy level scheme and experimental geometry, we achieve a photon-conversion efficiency of ˜0.3 % at low microwave intensities and a broad conversion bandwidth of more than 4 MHz. Theoretical simulations agree well with the experimental data, and they indicate that near-unit efficiency is possible in future experiments.

Apertureless near-field terahertz imaging using the self-mixing effect in a quantum cascade laser

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

Dean, Paul, E-mail: p.dean@leeds.ac.uk; Keeley, James; Kundu, Iman

2016-02-29

We report two-dimensional apertureless near-field terahertz (THz) imaging using a quantum cascade laser (QCL) source and a scattering probe. A near-field enhancement of the scattered field amplitude is observed for small tip-sample separations, allowing image resolutions of ∼1 μm (∼λ/100) and ∼7 μm to be achieved along orthogonal directions on the sample surface. This represents the highest resolution demonstrated to date with a THz QCL. By employing a detection scheme based on self-mixing interferometry, our approach offers experimental simplicity by removing the need for an external detector and also provides sensitivity to the phase of the reinjected field.

Theoretical Study of Turbulent Mixing in Inclined Ducted Jets.

DTIC Science & Technology

Jet mixing flow, * Thrust augmentation , Curved profiles, Short takeoff aircraft, Flow fields, Ducts, Ejectors , Mathematical models, Secondary flow, Theory, Angles, Problem solving, Incompressible flow

Clouding tracing: Visualization of the mixing of fluid elements in convection-diffusion systems

NASA Technical Reports Server (NTRS)

Ma, Kwan-Liu; Smith, Philip J.

1993-01-01

This paper describes a highly interactive method for computer visualization of the basic physical process of dispersion and mixing of fluid elements in convection-diffusion systems. It is based on transforming the vector field from a traditionally Eulerian reference frame into a Lagrangian reference frame. Fluid elements are traced through the vector field for the mean path as well as the statistical dispersion of the fluid elements about the mean position by using added scalar information about the root mean square value of the vector field and its Lagrangian time scale. In this way, clouds of fluid elements are traced and are not just mean paths. We have used this method to visualize the simulation of an industrial incinerator to help identify mechanisms for poor mixing.

State of the art on nuclear heating in a mixed (n/γ) field in research reactors

NASA Astrophysics Data System (ADS)

Amharrak, H.; Salvo, J. Di; Lyoussi, A.; Carette, M.; Reynard-Carette, C.

2014-06-01

This article aims at inventorying the knowledge on nuclear heating measurements in a mixed (n,γ) field in low-power research reactors using ThermoLuminescent Detectors (TLDs), Optically Stimulated Luminescent Detectors (OSLDs) and Ionization Chambers. The difficulty in measuring a mixed (n,γ) field in a reactor configuration lies in quantifying the contribution of the gamma photons and neutrons to the full signal measured by these detectors. The algorithms and experimental protocols developed together with the calculation methods used to assess the contribution of the neutron dose to the total integrated dose as measured by these detectors will be described in this article. This 'inventory' will be used to summarize the best methods to be used in relation to the requirements.

Soil and substrate morphology as witnesses of present and former agricultural landscape management

NASA Astrophysics Data System (ADS)

Chartin, C.; Salvador-Blanes, S.; Hinschberger, F.; Bourennane, H.; Macaire, J.-J.

2009-04-01

Water and tillage erosion, combined with the effect of successive regrouping of the land campaigns, have sensibly modified the morphology of cultivated hillslopes. Nowadays, we can still observe over cultivated landscapes various anthropogenic structures (e.g. lynchets) that correspond to former and/or present field limits. The aim of this work is to spatially characterise the geometry of these various structures, and to assess their relation with soil variability. The 10 ha studied site corresponds to an hillslope located in a small calcareous watershed near Tours in the Parisian Basin (France). Soils are mainly Cambisols (calcaric), Epileptic cambisols (calcaric) and Colluvic cambisols. This watershed is characterised by the presence of many soil accumulation structures and has been submitted to an important regrouping of the lands since the 1960's. The existing structures were accurately located and defined through a topographical analysis (slope, profile curvature...), and then related to past and present field limits using aerial photographies and cadastral maps. Two main morphological structures, deeply marked in the topography, are identified. The most remarkable type corresponds to well developed lynchets located at the lower part of field limits. Secondary structures, less marked than lynchets, are linked to field limits which existed at least since 1836, but that disappeared from the 1960's. These secondary structures look like longitudinal bulges placed perpendicularly to the direction of the main slope. A soil survey on these two geomorphic structure types has been performed in order to determine their specific geometry. Lynchets are characterised by a large increase in the thickness of soils: from 35 cm at 24 m upslope to more than 120 cm on its top. But, in some cases, the elevation study shows a topographical discontinuity between the top of the accumulation and the field or road below, discontinuity that is more important than the maximum soil thickness observed in the lynchet. This implies that the substrate, which is mostly homogeneous, has been largely excavated below these limits certainly due to repeated tillage operations. Concerning the secondary structures, soil thickness increases slightly from 35 cm at 16 m up- and downslope the former field limit to 70 cm at the maximum of the bulges convexity. However, the slope morphology seems to show larger soil accumulation considering a regular substrate morphology along the hillslope profile. Here too, by combining soil thickness and surface topography, we show that the substrate has certainly been strongly remodelled at these former field limits by tillage erosion. The spatial variability of the various soils types is closely linked to the sequence of structures oriented perpendicularly to the direction of the main slope. Although the current topography is clearly marked by various structures linked to former and present field limits, it appears that soil thickness is not the only factor explaining these large variations in the slope morphology: long-term agricultural practices, certainly tillage, "shape" the substrate as well. It is thus important to take into account these substrate excavations for sediment budget studies. The use of tracers such as 137Cs will allow to understand the intensity of these morphological changes at the slope scale within the last decades.

Transverse mixing of conservative and reactive tracers in porous media: Quantification through the concepts of flux-related and critical dilution indices

NASA Astrophysics Data System (ADS)

Chiogna, Gabriele; Cirpka, Olaf A.; Grathwohl, Peter; Rolle, Massimo

2011-02-01

The correct quantification of mixing is of utmost importance for modeling reactive transport in porous media and for assessing the fate and transport of contaminants in the subsurface. An appropriate measure of mixing in heterogeneous porous formations should correctly capture the effects on mixing intensity of various processes at different scales, such as local dispersion and the mixing enhancement due to heterogeneities. In this work, we use the concept of flux-related dilution index as a measure of transverse mixing. This quantity expresses the dilution of the mass flux of a conservative tracer solution over the total discharge of the system, and is particularly suited to address problems where a compound is continuously injected into the domain. We focus our attention on two-dimensional systems under steady state flow conditions and investigate both conservative and reactive transport in homogeneous and heterogeneous porous media at different scales. For mixing-controlled reactive systems, we introduce and illustrate the concept of critical dilution index, which represents the amount of mixing required for complete degradation of a continuously emitted plume undergoing decay upon mixing with ambient water. We perform two-dimensional numerical experiments at bench and field scales in homogeneous and heterogeneous conductivity fields. These numerical simulations show that the flux-related dilution index quantifies mixing and that the concept of critical dilution index is a useful measure to relate the mixing of conservative tracers to mixing-controlled degradation of reactive compounds.

Field verification of asphalt aging in hot mix plants.

DOT National Transportation Integrated Search

1986-02-01

As a measure of the aging of asphalt concrete mixes in the mixing and placement process, a formula was developed to determine the percentage of expected change in asphalt viscosity at the time of paving (Lund and Wilson, 1984). A value of 30 or highe...

Use of NDT equipment for construction quality control of hot mix asphalt pavements

DOT National Transportation Integrated Search

2006-08-01

The focus of the study has been to evaluate the utility of seismic methods in the quality management of the hot mix asphalt layers. Procedures are presented to measure the target field moduli of hot mix asphalt (HMA) with laboratory seismic methods, ...

Using 3D geological modelling and geochemical mixing models to characterise alluvial aquifer recharge sources in the upper Condamine River catchment, Queensland, Australia.

PubMed

Martinez, Jorge L; Raiber, Matthias; Cendón, Dioni I

2017-01-01

The influence of mountain front recharge on the water balance of alluvial valley aquifers located in upland catchments of the Condamine River basin in Queensland, Australia, is investigated through the development of an integrated hydrogeological framework. A combination of three-dimensional (3D) geological modelling, hydraulic gradient maps, multivariate statistical analyses and hydrochemical mixing calculations is proposed for the identification of hydrochemical end-members and quantification of the relative contributions of each end-member to alluvial aquifer recharge. The recognised end-members correspond to diffuse recharge and lateral groundwater inflows from three hydrostratigraphic units directly connected to the alluvial aquifer. This approach allows mapping zones of potential inter-aquifer connectivity and areas of groundwater mixing between underlying units and the alluvium. Mixing calculations using samples collected under baseflow conditions reveal that lateral contribution from a regional volcanic aquifer system represents the majority (41%) of inflows to the alluvial aquifer. Diffuse recharge contribution (35%) and inflow from two sedimentary bedrock hydrostratigraphic units (collectively 24%) comprise the remainder of major recharge sources. A detailed geochemical assessment of alluvial groundwater evolution along a selected flowpath of a representative subcatchment of the Condamine River basin confirms mixing as a key process responsible for observed spatial variations in hydrochemistry. Dissolution of basalt-related minerals and dolomite, CO 2 uptake, ion-exchange, precipitation of clay minerals, and evapotranspiration further contribute to the hydrochemical evolution of groundwater in the upland alluvial aquifer. This study highlights the benefits of undertaking an integrated approach that combines multiple independent lines of evidence. The proposed methods can be applied to investigate processes associated with inter-aquifer mixing, including groundwater contamination resulting from depressurisation of underlying geological units hydraulically connected to the shallower water reservoirs. Copyright © 2016 Elsevier B.V. All rights reserved.

Diffraction properties of opaque disks outside and inside a laser cavity

NASA Astrophysics Data System (ADS)

de Saint Denis, Renaud; Passilly, Nicolas; Fromager, Michael; Cagniot, Emmanuel; Ait-Ameur, Kamel

2008-02-01

Diffraction of symmetrical Laguerre-Gauss TEMp0 beams incident on an opaque disk known as a stop is considered. The near- and far-field patterns are studied. Thanks to zero-field occluding, conversion from TEM10 beam to dark hollow beam can be achieved with better efficiency than from a TEM00 beam. It is shown that the fundamental mode of a laser cavity including a diaphragm and a stop can be TEM00- or TEM10-like in shape depending on their size. This result is interpreted from the new divergence hierarchy, which characterises the diffracted TEMp0 beams emerging from the stop.

Rapid qualitative and quantitative analysis of opiates in extract of poppy head via FTIR and chemometrics: towards in-field sensors.

PubMed

Turner, Nicholas W; Cauchi, Michael; Piletska, Elena V; Preston, Christopher; Piletsky, Sergey A

2009-07-15

Identification and quantification of the opiates morphine and thebaine has been achieved in three commercial poppy cultivars using FTIR-ATR spectroscopy, from a simple and rapid methanolic extraction, suitable for field analysis. The limits of detection were 0.13 mg/ml (0.013%, w/v) and 0.3 mg/ml (0.03%, w/v) respectively. The concentrations of opiates present were verified with HPLC-MS. The chemometrics has been used to identify specific "signature" peaks in the poppy IR spectra for characterisation of cultivar by its unique fingerprint offering a potential forensic application in opiate crop analysis.

Receptivity of the compressible mixing layer

NASA Astrophysics Data System (ADS)

Barone, Matthew F.; Lele, Sanjiva K.

2005-09-01

Receptivity of compressible mixing layers to general source distributions is examined by a combined theoretical/computational approach. The properties of solutions to the adjoint Navier Stokes equations are exploited to derive expressions for receptivity in terms of the local value of the adjoint solution. The result is a description of receptivity for arbitrary small-amplitude mass, momentum, and heat sources in the vicinity of a mixing-layer flow, including the edge-scattering effects due to the presence of a splitter plate of finite width. The adjoint solutions are examined in detail for a Mach 1.2 mixing-layer flow. The near field of the adjoint solution reveals regions of relatively high receptivity to direct forcing within the mixing layer, with receptivity to nearby acoustic sources depending on the source type and position. Receptivity ‘nodes’ are present at certain locations near the splitter plate edge where the flow is not sensitive to forcing. The presence of the nodes is explained by interpretation of the adjoint solution as the superposition of incident and scattered fields. The adjoint solution within the boundary layer upstream of the splitter-plate trailing edge reveals a mechanism for transfer of energy from boundary-layer stability modes to Kelvin Helmholtz modes. Extension of the adjoint solution to the far field using a Kirchhoff surface gives the receptivity of the mixing layer to incident sound from distant sources.

Study of the peculiarities of multiparticle production via event-by-event analysis in asymmetric nucleus-nucleus interactions

NASA Astrophysics Data System (ADS)

Fedosimova, Anastasiya; Gaitinov, Adigam; Grushevskaya, Ekaterina; Lebedev, Igor

2017-06-01

In this work the study on the peculiarities of multiparticle production in interactions of asymmetric nuclei to search for unusual features of such interactions, is performed. A research of long-range and short-range multiparticle correlations in the pseudorapidity distribution of secondary particles on the basis of analysis of individual interactions of nuclei of 197 Au at energy 10.7 AGeV with photoemulsion nuclei, is carried out. Events with long-range multiparticle correlations (LC), short-range multiparticle correlations (SC) and mixed type (MT) in pseudorapidity distribution of secondary particles, are selected by the Hurst method in accordance with Hurst curve behavior. These types have significantly different characteristics. At first, they have different fragmentation parameters. Events of LC type are processes of full destruction of the projectile nucleus, in which multicharge fragments are absent. In events of mixed type several multicharge fragments of projectile nucleus are discovered. Secondly, these two types have significantly different multiplicity distribution. The mean multiplicity of LC type events is significantly more than in mixed type events. On the basis of research of the dependence of multiplicity versus target-nuclei fragments number for events of various types it is revealed, that the most considerable multiparticle correlations are observed in interactions of the mixed type, which correspond to the central collisions of gold nuclei and nuclei of CNO-group, i.e. nuclei with strongly asymmetric volume, nuclear mass, charge, etc. Such events are characterised by full destruction of the target-nucleus and the disintegration of the projectile-nucleus on several multi-charged fragments.

Patients' expectations of deep brain stimulation, and subjective perceived outcome related to clinical measures in Parkinson's disease: a mixed-method approach.

PubMed

Maier, Franziska; Lewis, Catharine J; Horstkoetter, Nina; Eggers, Carsten; Kalbe, Elke; Maarouf, Mohammad; Kuhn, Jens; Zurowski, Mateusz; Moro, Elena; Woopen, Christiane; Timmermann, Lars

2013-11-01

To study patients' expectations of subthalamic deep brain stimulation (STN-DBS) and their subjective perceived outcome, by using qualitative and quantitative methods in Parkinson's disease (PD). PD patients were prospectively examined before and 3 months after surgery. Semistructured interviews regarding preoperative expectations and postsurgical subjective perceived outcome were conducted. These were analysed using content analysis. For statistical analyses, patients were classified according to their subjective perceived outcome, resulting in three different subjective outcome groups (negative, mixed, positive outcome). The groups were used for multiple comparisons between and within each group regarding motor impairment, quality of life (QoL), neuropsychiatric status and cognitive functioning, using standard instruments. A logistic regression analysis was conducted to find predictors of subjective negative outcome. Receiver operating characteristic curves were used to analyse cut-off scores for predictive tests. Of the 30 PD patients participating, 8 had a subjective negative outcome, 8 a mixed and 14 a positive outcome. All groups significantly improved in motor functioning. Patients with subjective negative outcome were characterised by preoperative unrealistic expectations, no postsurgical improvement in QoL, and significantly higher presurgical and postsurgical apathy and depression scores. Higher preoperative apathy and depression scores were significant predictors of negative subjective outcome. Cut-off scores for apathy and depression were identified. The mixed-method approach proved useful in examining a patient's subjective perception of STN-DBS outcome. Our results show that significant motor improvement does not necessarily lead to a positive subjective outcome. Moreover, PD patients should be screened carefully before surgery regarding apathy and depression. (DRKS-ID: DRKS00003221).

Venera 15: Water vapour in the middle atmosphere of Venus

NASA Astrophysics Data System (ADS)

Ignatiev, N. I.; Moroz, V. I.; Zasova, L. V.; Khatuntsev, I. V.

1999-01-01

In 1983, spectra of Venus in the region of 6-40 μm were measured by means of the Fourier Spectrometer aboard the Venera 15 orbiter. It covered local solar times from 4 a.m. to 10 a.m. and from 4 p.m. to 10 p.m. in the latitude range from -65° up to 87°. The results of an extended processing and analysis of these data are presented. Time and spatial variations of the water vapour were found. Most of the measurements fall in the range of 5-15 ppm, which is close to the early results. The effective altitude of sounding is approximately equal to the altitude where the optical depth τ = 1. Two latitude regions can be distinguished: (A) 20° < φ < 50° and (B) φ > 60°, which are characterised by different altitudes of the level of τ = 1: 62 and 55 km respectively. Mean mixing ratios near this level in the two regions are almost the same, but the partial pressures and mass densities in region (B) are 2-4 times greater than those in region (A). In region (A) a weak dayside maximum and a nightside minimum were observed. Region (B) is of inhomogeneous structure, and the retrieved mixing ratio has greater uncertainty and may probably change from the detection limit of 1 ppm up to 30 ppm. Although the retrieval of H2O mixing ratio altitude profile from the Venera 15 data appeared to be impossible, indirect indications were found that at least in region (A) the mixing ratio decreases with altitude.

Chameleon-photon mixing in a primordial magnetic field

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

Schelpe, Camilla A. O.

2010-08-15

The existence of a sizable, O(10{sup -10}-10{sup -9} G), cosmological magnetic field in the early Universe has been postulated as a necessary step in certain formation scenarios for the large-scale O({mu}G) magnetic fields found in galaxies and galaxy clusters. If this field exists then it may induce significant mixing between photons and axion-like particles (ALPs) in the early Universe. The resonant conversion of photons into ALPs in a primordial magnetic field has been studied elsewhere by Mirizzi, Redondo and Sigl (2009). Here we consider the nonresonant mixing between photons and scalar ALPs with masses much less than the plasma frequencymore » along the path, with specific reference to the chameleon scalar field model. The mixing would alter the intensity and polarization state of the cosmic microwave background (CMB) radiation. We find that the average modification to the CMB polarization modes is negligible. However the average modification to the CMB intensity spectrum is more significant and we compare this to high-precision measurements of the CMB monopole made by the far infrared absolute spectrophotometer on board the COBE satellite. The resulting 95% confidence limit on the scalar-photon conversion probability in the primordial field (at 100 GHz) is P{sub {gamma}{r_reversible}{phi}<}2.6x10{sup -2}. This corresponds to a degenerate constraint on the photon-scalar coupling strength, g{sub eff}, and the magnitude of the primordial magnetic field. Taking the upper bound on the strength of the primordial magnetic field derived from the CMB power spectra, B{sub {lambda}{<=}5}.0x10{sup -9} G, this would imply an upper bound on the photon-scalar coupling strength in the range g{sub eff} < or approx. 7.14x10{sup -13} GeV{sup -1} to g{sub eff} < or approx. 9.20x10{sup -14} GeV{sup -1}, depending on the power spectrum of the primordial magnetic field.« less

Development of a Field-Portable Near-Infrared Water-Cement Ratio Meter. Phase I: Investigation of Spectral Feasibility

DOT National Transportation Integrated Search

1999-06-25

In order to accurately predict the strength and durability of an adequately mixed and compacted concrete mix it is useful, if not necessary, to know the water-cement ratio of the fresh concrete mix. In this work near-infrared reflection spectroscopy ...

A numerical study of mixing enhancement in supersonic reacting flow fields. [in scramjets

NASA Technical Reports Server (NTRS)

Drummond, J. Philip; Mukunda, H. S.

1988-01-01

NASA Langley has intensively investigated the components of ramjet and scramjet systems for endoatmospheric, airbreathing hypersonic propulsion; attention is presently given to the optimization of scramjet combustor fuel-air mixing and reaction characteristics. A supersonic, spatially developing and reacting mixing layer has been found to serve as an excellent physical model for the mixing and reaction process. Attention is presently given to techniques that have been applied to the enhancement of the mixing processes and the overall combustion efficiency of the mixing layer. A fuel injector configuration has been computationally designed which significantly increases mixing and reaction rates.

Free energy surfaces in the superconducting mixed state

NASA Technical Reports Server (NTRS)

Finnemore, D. K.; Fang, M. M.; Bansal, N. P.; Farrell, D. E.

1989-01-01

The free energy surface for Tl2Ba2Ca2Cu3O1O has been measured as a function of temperature and magnetic field to determine the fundamental thermodynamic properties of the mixed state. The change in free energy, G(H)-G(O), is found to be linear in temperature over a wide range indicating that the specific heat is independent of field.

Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

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

Zhao, Yanlin; Wang, Mi; Yao, Jun

2014-04-11

Electrical impedance tomography (EIT) is one of the process tomography techniques to provide an on-line non-invasive imaging for multiphase flow measurement. With EIT measurements, the images of impedance real part, impedance imaginary part, phase angle, and magnitude can be obtained. However, most of the applications of EIT in the process industries rely on the conductivity difference between two phases in fluids to obtain the concentration profiles. It is not common to use the imaginary part or phase angle due to the dominant change in conductivity or complication in the use of other impedance information. In a solid-liquid two phases systemmore » involving nano- or submicro-particles, characterisation of particles (e.g. particle size and concentration) have to rely on the measurement of impedance phase angle or imaginary part. Particles in a solution usually have an electrical double layer associated with their surfaces and can form an induced electrical dipole moment due to the polarization of the electrical double layer under the influence of an alternating electric field. Similar to EIT, electrical impedance spectroscopy (EIS) measurement can record the electrical impedance data, including impedance real part, imaginary part and phase angle (θ), which are caused by the polarization of the electrical double layer. These impedance data are related to the particle characteristics e.g. particle size, particle and ionic concentrations in the aqueous medium, therefore EIS method provides a capability for characterising the particles in suspensions. Electrical impedance tomography based on EIS measurement or namely, electrical impedance tomography spectroscopy (EITS) could image the spatial distribution of particle characteristics. In this paper, a new method, including test set-up and data analysis, for characterisation of particles in suspensions are developed through the experimental approach. The experimental results on tomographic imaging of colloidal particles based on EIS measurement using a sensor of 8 electrodes are reported. Results have demonstrated the potential as well as revealed the challenge in the use of EIS and EITS for characterisation of particle in suspension.« less

Smart Aquifer Characterisation validated using Information Theory and Cost benefit analysis

NASA Astrophysics Data System (ADS)

Moore, Catherine

2016-04-01

The field data acquisition required to characterise aquifer systems are time consuming and expensive. Decisions regarding field testing, the type of field measurements to make and the spatial and temporal resolution of measurements have significant cost repercussions and impact the accuracy of various predictive simulations. The Smart Aquifer Characterisation (SAC) research programme (New Zealand (NZ)) addresses this issue by assembling and validating a suite of innovative methods for characterising groundwater systems at the large, regional and national scales. The primary outcome is a suite of cost effective tools and procedures provided to resource managers to advance the understanding and management of groundwater systems and thereby assist decision makers and communities in the management of their groundwater resources, including the setting of land use limits that protect fresh water flows and quality and the ecosystems dependent on that fresh water. The programme has focused novel investigation approaches including the use of geophysics, satellite remote sensing, temperature sensing and age dating. The SMART (Save Money And Reduce Time) aspect of the programme emphasises techniques that use these passive cost effective data sources to characterise groundwater systems at both the aquifer and the national scale by: • Determination of aquifer hydraulic properties • Determination of aquifer dimensions • Quantification of fluxes between ground waters and surface water • Groundwater age dating These methods allow either a lower cost method for estimating these properties and fluxes, or a greater spatial and temporal coverage for the same cost. To demonstrate the cost effectiveness of the methods a 'data worth' analysis is undertaken. The data worth method involves quantification of the utility of observation data in terms of how much it reduces the uncertainty of model parameters and decision focussed predictions which depend on these parameters. Such decision focussed predictions can include many aspects of system behaviour which underpin management decisions e.g., drawdown of groundwater levels, salt water intrusion, stream depletion, or wetland water level. The value of a data type or an observation location (e.g. remote sensing data (Westerhoff 2015) or a distributed temperature sensing measurement) is greater the more it enhances the certainty with which the model is able to predict such environmental behaviour. By comparing the difference in predictive uncertainty with or without such data, the value of potential observations is assessed. This can easily be achieved using rapid linear predictive uncertainty analysis methods (Moore 2005, Moore and Doherty 2006). By assessing the tension between the cost of data acquisition and the predictive accuracy achieved by gathering these observations in a pareto analysis, the relative cost effectiveness of these novel methods can be compared with more traditional measurements (e.g. bore logs, aquifer pumping tests, and simultaneous stream loss gaugings) for a suite of pertinent groundwater management decisions (Wallis et al 2014). This comparison illuminates those field data acquisition methods which offer the best value for the specific issues managers face in any region, and also indicates the diminishing returns of increasingly large and expensive data sets. References: Wallis I, Moore C, Post V, Wolf L, Martens E, Prommer. Using predictive uncertainty analysis to optimise tracer test design and data acquisition. Journal of Hydrology 515 (2014) 191-204. Moore, C. (2005). The use of regularized inversion in groundwater model calibration and prediction uncertainty analysis. Thesis submitted for the degree of Doctor of Philosophy at The University of Queensland, Australia. Moore, C., and Doherty, D. (2005). Role of the calibration process in reducing model predictive error. Water Resources Research 41, no.5 W05050. Westerhoff RS. Using uncertainty of Penman and Penman-Monteith methods in combined satellite and ground-based evapotranspiration estimates. Remote Sensing of Environment 169, 102-112

Near-field refrigeration and tunable heat exchange through four-wave mixing

NASA Astrophysics Data System (ADS)

Khandekar, Chinmay; Messina, Riccardo; Rodriguez, Alejandro W.

2018-05-01

We modify and extend a recently proposed four-wave mixing scheme [C. Khandekar and A. Rodriguez, Opt. Express 25(19), 23164 (2017)] for achieving near-field thermal upconversion and energy transfer, to demonstrate efficient thermal refrigeration at low intensities ˜ 109W/m2 over a wide range of gap sizes (from tens to hundreds of nanometers) and operational temperatures (from tens to hundreds of Kelvins). We further exploit the scheme to achieve magnitude and directional tunability of near-field heat exchange between bodies held at different temperatures.

Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

NASA Astrophysics Data System (ADS)

Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

2014-02-01

Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

Synthesis and (spectro)electrochemistry of mixed-valent diferrocenyl-dihydrothiopyran derivatives.

PubMed

Kowalski, Konrad; Karpowicz, Rafał; Mlostoń, Grzegorz; Miesel, Dominique; Hildebrandt, Alexander; Lang, Heinrich; Czerwieniec, Rafał; Therrien, Bruno

2015-04-07

Three novel diferrocenyl complexes were prepared and characterised. 2,2-Diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran (1, sulphide) was accessible by the hetero-Diels-Alder reaction of diferrocenyl thioketone with 2,3-dimethyl-1,3-butadiene. Stepwise oxidation of 1 gave the respective oxides 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1-oxide (2, sulfoxide) and 2,2-diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1,1-dioxide (3, sulfone), respectively. The molecular structures of 1 and 3 in the solid state were determined by single crystal X-ray crystallography. The oxidation of sulphide 1 to sulfone 3, plays only a minor role on the overall structure of the two compounds. Electrochemical (cyclic voltammetry (= CV), square wave voltammetry (= SWV)) and spectroelectrochemical (in situ UV-Vis/NIR spectroscopy) studies were carried out. The CV and SWV measurements showed that an increase of the sulphur atom oxidation from -2 in 1 to +2 in 3 causes an anodic shift of the ferrocenyl-based oxidation potentials of about 100 mV. The electrochemical oxidation of 1-3 generates mixed-valent cations 1(+)-3(+). These monooxidised species display low-energy electronic absorption bands between 1000 and 3000 nm assigned to IVCT (= Inter-Valence Charge Transfer) electronic transitions. Accordingly, the mixed-valent cations 1(+)-3(+) are classified as weakly coupled class II systems according to Robin and Day.

Determination of mixing state and sources of wintertime organic aerosol in Paris using single particle mass spectrometry

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Wiedensohler, A.; Jeong, C.; McGuire, M.; Evans, G. J.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J.

2012-12-01

The size-resolved chemical composition of single particles at an urban background site in Paris, France, was determined using an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) as part of the MEGAPOLI winter campaign in January/February 2010. A variety of mixing states were identified for organic aerosol by mass spectral clustering and apportioned to both fossil fuel and biomass burning sources. The ATOFMS data were scaled in order to produce mass concentration estimates for each organic aerosol particle type identified. Potassium-containing organic aerosol internally mixed with nitrate, associated with local wood burning, was observed to dominate during periods characterised by marine air masses. Sulfate-rich potassium-containing organic aerosol, associated with transboundary transport of biomass burning emissions, dominated during periods influenced by continental air masses. The scaled total mass concentration for potassium-containing particles was well correlated (R2 = 0.79) with concurrent measurements of potassium mass concentration measured with a Particle-Into-Liquid-Sampler (PILS). Another organic particle type, also containing potassium but rich in trimethylamine and sulfate, was detected exclusively during continental air mass events. These particles are postulated to have accumulated gas phase trimethylamine through heterogeneous reaction before arriving at the sampling site. Potential source regions for transboundary organic aerosols have been investigated using the potential source contribution function (PSCF). Comparison with aerosol mass spectrometer (AMS) measurements will also be discussed.

Multimode four-wave mixing in an unresolved sideband optomechanical system

NASA Astrophysics Data System (ADS)

Li, Zongyang; You, Xiang; Li, Yongmin; Liu, Yong-Chun; Peng, Kunchi

2018-03-01

We have studied multimode four-wave mixing (FWM) in an unresolved sideband cavity optomechanical system. The radiation pressure coupling between the cavity fields and multiple mechanical modes results in the formation of a series of tripod-type energy-level systems, which induce the multimode FWM phenomenon. The FWM mechanism enables remarkable amplification of a weak signal field accompanied by the generation of an FWM field when only a microwatt-level pump field is applied. For proper system parameters, the amplified signal and FWM fields have equal intensity with opposite phases. The gain and frequency response bandwidth of the signal field can be dynamically tuned by varying the pump intensity, optomechanical coupling strength, and additional feedback control. Under certain conditions, the frequency response bandwidth can be very narrow and reaches the level of hertz.

[A review of mixed gas detection system based on infrared spectroscopic technique].

PubMed

Dang, Jing-Min; Fu, Li; Yan, Zi-Hui; Zheng, Chuan-Tao; Chang, Yu-Chun; Chen, Chen; Wang, Yi-Din

2014-10-01

In order to provide the experiences and references to the researchers who are working on infrared (IR) mixed gas detection field. The proposed manuscript reviews two sections of the aforementioned field, including optical multiplexing structure and detection method. At present, the coherent light sources whose representative are quantum cascade laser (QCL) and inter-band cascade laser(ICL) become the mainstream light source in IR mixed gas detection, which replace the traditional non-coherent light source, such as IR radiation source and IR light emitting diode. In addition, the photon detector which has a super high detectivity and very short response time is gradually beyond thermal infrared detector, dominant in the field of infrared detector. The optical multiplexing structure is the key factor of IR mixed gas detection system, which consists of single light source multi-plexing detection structure and multi light source multiplexing detection structure. Particularly, single light source multiplexing detection structure is advantages of small volume and high integration, which make it a plausible candidate for the portable mixed gas detection system; Meanwhile, multi light source multiplexing detection structure is embodiment of time division multiplex, frequency division multiplexing and wavelength division multiplexing, and become the leading structure of the mixed gas detection system because of its wider spectral range, higher spectral resolution, etc. The detection method applied to IR mixed gas detection includes non-dispersive infrared (NDIR) spectroscopy, wavelength and frequency-modulation spectroscopy, cavity-enhanced spectroscopy and photoacoustic spectroscopy, etc. The IR mixed gas detection system designed by researchers after recognizing the whole sections of the proposed system, which play a significant role in industrial and agricultural production, environmental monitoring, and life science, etc.

PIV Measurements of Supersonic Internally-Mixed Dual-Stream Jets

NASA Technical Reports Server (NTRS)

Bridges, James E.; Wernet, Mark P.

2012-01-01

While externally mixed, or separate flow, nozzle systems are most common in high bypass-ratio aircraft, they are not as attractive for use in lower bypass-ratio systems and on aircraft that will fly supersonically. The noise of such propulsion systems is also dominated by jet noise, making the study and noise reduction of these exhaust systems very important, both for military aircraft and future civilian supersonic aircraft. This paper presents particle image velocimetry of internally mixed nozzle with different area ratios between core and bypass, and nozzles that are ideally expanded and convergent. Such configurations independently control the geometry of the internal mixing layer and of the external shock structure. These allow exploration of the impact of shocks on the turbulent mixing layers, the impact of bypass ratio on broadband shock noise and mixing noise, and the impact of temperature on the turbulent flow field. At the 2009 AIAA/CEAS Aeroacoustics Conference the authors presented data and analysis from a series of tests that looked at the acoustics of supersonic jets from internally mixed nozzles. In that paper the broadband shock and mixing noise components of the jet noise were independently manipulated by holding Mach number constant while varying bypass ratio and jet temperature. Significant portions of that analysis was predicated on assumptions regarding the flow fields of these jets, both shock structure and turbulence. In this paper we add to that analysis by presenting particle image velocimetry measurements of the flow fields of many of those jets. In addition, the turbulent velocity data documented here will be very useful for validation of computational flow codes that are being developed to design advanced nozzles for future aircraft.

Cristallisation fractionnée et contamination crustale dans la série magmatique jurassique transitionnelle du Haut Atlas central (Maroc)Fractional crystallisation and crustal contamination in the transitional Jurassic magmatic series of Central High Atlas (Morocco)

NASA Astrophysics Data System (ADS)

Zayane, Rachid; Essaifi, Abderrahim; Maury, René C.; Piqué, Alain; Laville, Edgard; Bouabdelli, Mohamed

The Middle Jurassic plutonism of the Central High Atlas (Morocco) was emplaced in N45° trending anticlinal ridges. It is characterised by various petrographic facies including mafic rocks (troctolites), intermediate rocks (diorites, monzodiorites), and evolved rocks (syenites), together with heterogeneous facies resulting from mixing between acidic and the intermediate magmas. Mineralogical and chemical data show ( i) the transitional character of the Jurassic magmatic series of the Central High Atlas and ( ii) the implication of continental crust as a contaminant during fractional crystallization. To cite this article: R. Zayane et al., C. R. Geoscience 334 (2002) 97-104.

Synthesis and DNA interaction of a mixed proflavine-phenanthroline Tröger base.

PubMed

Baldeyrou, Brigitte; Tardy, Christelle; Bailly, Christian; Colson, Pierre; Houssier, Claude; Charmantray, Franck; Demeunynck, Martine

2002-04-01

We report the synthesis of an asymmetric Tröger base containing the two well characterised DNA binding chromophores, proflavine and phenanthroline. The mode of interaction of the hybrid molecule was investigated by circular and linear dichroism experiments and a biochemical assay using DNA topoisomerase I. The data are compatible with a model in which the proflavine moiety intercalates between DNA base pairs and the phenanthroline ring occupies the DNA groove. DNase I cleavage experiments were carried out to investigate the sequence preference of the hybrid ligand and a well resolved footprint was detected at a site encompassing two adjacent 5'-GTC.5-GAC triplets. The sequence preference of the asymmetric molecule is compared to that of the symmetric analogues.

Scrubbing intensification for sulphur and ammonia compounds removal.

PubMed

Couvert, A; Sanchez, C; Laplanche, A; Renner, C

2008-02-01

Operating conditions were optimised in a new compact scrubber in order to remove odorous sulphur (H(2)S and CH(3)SH) and ammonia compounds. The influence of the superficial gas and liquid velocities, pH, contactor length, inlet concentrations (sulphur compounds, ammonia, chlorine), and the mixing effects was characterised. Whereas abatement increased with velocities, pH and the chlorine concentration, an increase of inlet CH(3)SH concentration drove to a worse efficiency of process. Moreover, the contactor length and the presence of another pollutant in the gas phase only played a role on the methylmercaptan removal. Finally, the reactive consumptions were estimated at the outlet of the reactor. The chlorination by-product quantification permitted to understand the under-stoichiometry.

Characterisation of nasal Staphylococcus delphini and Staphylococcus pseudintermedius isolates from healthy donkeys in Tunisia.

PubMed

Gharsa, H; Slama, K Ben; Gómez-Sanz, E; Gómez, P; Klibi, N; Zarazaga, M; Boudabous, A; Torres, C

2015-07-01

Staphylococcus intermedius group (SIG) bacteria can colonise the nares of some animals but are also emerging pathogens in humans and animals. To analyse SIG nasal carriage in healthy donkeys destined for food consumption in Tunisia and to characterise recovered isolates. Nasal swabs from 100 healthy donkeys were tested for SIG recovery, and isolates were identified by biochemical and molecular methods. Antimicrobial susceptibility of isolates was tested and detection of antimicrobial resistance and virulence genes was performed. Isolates were typed at the clonal level by multilocus sequence typing and SmaI pulsed-field gel electrophoresis. Staphylococcus delphini and Staphylococcus pseudintermedius (included in SIG) were obtained in 19% and 2% of the tested samples, respectively, and one isolate per sample was characterised. All isolates were meticillin susceptible and mecA negative. Most S. delphini and S. pseudintermedius isolates showed susceptibility to all antimicrobials tested, with the exception of 2 isolates resistant to tetracycline (tet(M) gene) or fusidic acid. The following toxin genes were identified (percentage of isolates): lukS-I (100%), lukF-I (9.5%), siet (100%), se-int (90%), seccanine (19%) and expA (9.5%). Thirteen different pulsed-field gel electrophoresis profiles were identified among the 21 SIG isolates. Additionally, the following 9 different sequence types (STs) were detected by multilocus sequence typing, 6 of them new: ST219 (6 isolates), ST12 (5 isolates), ST220 (3 isolates), ST13, ST50, ST193, ST196, ST218 and ST221 (one isolate each). Staphylococcus delphini and S. pseudintermedius are common nasal colonisers of donkeys, generally susceptible to the antimicrobials tested; nevertheless, these SIG isolates contain virulence genes, including the recently described exfoliative gene (expA) and several enterotoxin genes, with potential implications for public health. This is the first description of S. delphini in Tunisia. The Summary is available in Chinese - see Supporting information. © 2014 EVJ Ltd.

Modelling of proton acceleration in application to a ground level enhancement

NASA Astrophysics Data System (ADS)

Afanasiev, A.; Vainio, R.; Rouillard, A. P.; Battarbee, M.; Aran, A.; Zucca, P.

2018-06-01

Context. The source of high-energy protons (above 500 MeV) responsible for ground level enhancements (GLEs) remains an open question in solar physics. One of the candidates is a shock wave driven by a coronal mass ejection, which is thought to accelerate particles via diffusive-shock acceleration. Aims: We perform physics-based simulations of proton acceleration using information on the shock and ambient plasma parameters derived from the observation of a real GLE event. We analyse the simulation results to find out which of the parameters are significant in controlling the acceleration efficiency and to get a better understanding of the conditions under which the shock can produce relativistic protons. Methods: We use the results of the recently developed technique to determine the shock and ambient plasma parameters, applied to the 17 May 2012 GLE event, and carry out proton acceleration simulations with the Coronal Shock Acceleration (CSA) model. Results: We performed proton acceleration simulations for nine individual magnetic field lines characterised by various plasma conditions. Analysis of the simulation results shows that the acceleration efficiency of the shock, i.e. its ability to accelerate particles to high energies, tends to be higher for those shock portions that are characterised by higher values of the scattering-centre compression ratio rc and/or the fast-mode Mach number MFM. At the same time, the acceleration efficiency can be strengthened by enhanced plasma density in the corresponding flux tube. The simulations show that protons can be accelerated to GLE energies in the shock portions characterised by the highest values of rc. Analysis of the delays between the flare onset and the production times of protons of 1 GV rigidity for different field lines in our simulations, and a subsequent comparison of those with the observed values indicate a possibility that quasi-perpendicular portions of the shock play the main role in producing relativistic protons.

Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

NASA Astrophysics Data System (ADS)

van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

2016-09-01

Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

Chaotic characteristics enhanced by impeller of perturbed six-bent-bladed turbine in stirred tank

NASA Astrophysics Data System (ADS)

Luan, Deyu; Zhang, Shengfeng; Lu, Jianping; Zhang, Xiaoguang

The fundamental way of improving the mixing efficiency is to induce the chaotic flow in a stirred vessel. The impeller form plays an important role for changing the structure of flow field and realizing chaotic mixing. Based on the velocity time series acquired by the experiment of particle image velocimetry (PIV), with the software Matlab, the macro-instability (MI), largest Lyapunov exponent (LLE), and Kolmogorov entropy in the water stirred tank is investigated respectively with the impeller of perturbed six-bent-bladed turbine (6PBT). The results show that the MI characteristics are obvious and two peak values of MI frequency are observed at the speed N = 60 rpm. With the increasing speed (more than 100 rpm), the peak characteristics of MI frequency disappear and a multi-scale wavelet structure of characterizing the chaotic flow field appears. Moreover, under the speed N = 60 rpm, the LLE is less than 0 and Kolmogorov entropy is 0, which means that the flow field is in the periodic moving state. As the speed is increased to more than 100 rpm, the LLE and Kolmogorov entropy are all more than 0, which indicates that the flow field goes into the chaotic mixing. When the speed reaches up to about 210 rpm, both of the LLE and Kolmogorov entropy achieve the optimum values, which will result in an excellent chaos with the highest mixing efficient. So it is feasible that the MI frequency, the LLE and the Kolmogorov entropy can be used to analyze the flow field characteristics in a stirred tank. The research results promote the understanding of the chaotic mixing mechanism and provide a theoretical reference for the development of new type impeller.

Symmetries, supersymmetries and cohomologies in gauge theories

NASA Astrophysics Data System (ADS)

Bǎbǎlîc, Elena-Mirela

2009-12-01

The main subjects approached in the thesis are the following: a) the derivation of the interactions in two space-time dimensions in a particular class of topological BF models; b) the construction of the couplings in D ≥ 5 dimensions between one massless tensor field with the mixed symmetry (3, 1) and one with the mixed symmetry of the Riemann tensor; c) the evaluation of the existence of interactions in D ≥ 5 dimensions between two different collections of massless tensor fields with the mixed symmetries (3, 1) and (2, 2); d) the analysis of the relation between the BRST charges obtained in the pure-spinor formalism, respectively in the κ-symmetric one for the supermembrane in eleven dimensions. Our procedure for the first three subjects is based on solving the equations that describe the deformation of the solution to the master equation by means of specific cohomological techniques, while for the fourth one we will use techniques specific to the BRST Hamiltonian approach in order to write the BRST charge. The interactions are obtained under the following hypotheses: locality, Lorentz covariance, Poincare invariance, analyticity of the deformations, and preservation of the number of derivatives on each field. The first three assumptions imply that the interacting theory is local in space-time, Lorentz covariant and Poincare invariant. The analyticity of the deformations refers to the fact that the deformed solution to the master equation is analytical in the coupling constant and reduces to the original solution in the free limit. The conservation of the number of derivatives on each field with respect to the free theory means here that the following two requirements are simultaneously satisfied: (i) the derivative order of the equations of motion on each field is the same for the free and respectively for the interacting theory; (ii) the maximum number of derivatives in the interaction vertices is equal to two, i.e. the maximum number of derivatives from the free Lagrangian. The main results of the thesis are: interactions in two space-time dimensions for a particular class of BF models; interactions between one massless tensor field with the mixed symmetry (3, 1) and one with the mixed symmetry of the Riemann tensor; interactions between collections of massless tensor fields with the mixed symmetries (3, 1) and (2, 2); relating the kappa-symmetric and pure-spinor versions of the supermembrane in eleven dimensions.

Molecular characterisation of enteroinvasive Escherichia coli O136:K78 isolates from patients of a diarrhoea outbreak in China.

PubMed

Zhou, X; Xia, W; Tu, J; Xue, L; Ni, X

2015-01-01

A diarrhoea outbreak occurred in a kindergarten, which caused 21 relevant infected cases. Our object was to confirm the pathogens and their molecular characterisation. Faecal samples from 21 patients were collected on the 3rd day after their symptom onset, and a regular epidemiological investigation was conducted. Bacterial isolation was performed in accordance with standard laboratory protocol, serological and molecular characterisations were determined by serum agglutination test and real-time polymerase chain reaction (PCR) method, respectively. The pulsed field gel electrophoresis (PFGE) and 16S rRNAs were conducted to determine the homology. Eleven enteroinvasive Escherichia coli (EIEC) O136:K78 strains were isolated. The serum agglutination test showed that all strains' serotypes were E. coli (EIEC) O136:K78. Real-time PCR showed that 10 (91%) strains carried the invasion plasmid antigen H gene (ipaH), carried by all four Shigella species and EIEC. The strain that didn't carry the ipaH gene had different biochemical reactions of L-lizyna and L-rhamnose with the other strains. The complete 16S rRNA sequences showed 98.4% identity between ipaH-negative isolate and the others, and the PFGE indicated that the ipaH-negative isolate was not homological with other isolates in this diarrhoea outbreak. The diarrhoea outbreak was caused by E. coli (EIEC) O136:K78.

Development of a Methodology for the Characterisation of Air-coupled Ultrasound Probes

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

Pietroni, Paolo; Marco Revel, Gian

2010-05-28

This study is aimed at developing a technique for the characterisation of air-coupled ultrasound probes, starting from the analysis of the mechanical behaviour of the probe membrane. The vibratory behaviour of the emission membrane is studied using laser-Doppler vibrometry techniques with high frequency demodulation system (20 MHz). The determination of the vibration provides information which are useful for the assessment of the performance of the probe, in particular concerning the Quality factor and the portion of the membrane which really contributes to the emission. During the second step the results of the vibration measurements are used to calculate, by meansmore » of numerical boundary element method, the ultrasound beam emitted in terms of intensity in space. The obtained field is compared with the direct measurements carried out by scanning with the receiver probe and a pinhole plate. This comparison allows the potential and the problems of the two different characterisation techniques to be determined, even if the pinhole technique (which is currently considered the state of the art) cannot be used as an absolute reference. This study appears to be useful for paving the way for a new methodology for the calibration of air-coupled ultrasound probes, which potentially could be used not only to improve the probe manufacturing process, but also to control conformity to specifications.« less

Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

DOE PAGES

Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; ...

2015-01-09

We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: m DM, M med , g DM and g q, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework canmore » be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. In conclusion, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.« less

Hawaii Ocean Mixing Experiment: Program Summary

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Chao, Benjamin F. (Technical Monitor)

2002-01-01

It is becoming apparent that insufficient mixing occurs in the pelagic ocean to maintain the large scale thermohaline circulation. Observed mixing rates fall a factor of ten short of classical indices such as Munk's "Abyssal Recipe." The growing suspicion is that most of the mixing in the sea occurs near topography. Exciting recent observations by Polzin et al., among others, fuel this speculation. If topographic mixing is indeed important, it must be acknowledged that its geographic distribution, both laterally and vertically, is presently unknown. The vertical distribution of mixing plays a critical role in the Stommel Arons model of the ocean interior circulation. In recent numerical studies, Samelson demonstrates the extreme sensitivity of flow in the abyssal ocean to the spatial distribution of mixing. We propose to study the topographic mixing problem through an integrated program of modeling and observation. We focus on tidally forced mixing as the global energetics of this process have received (and are receiving) considerable study. Also, the well defined frequency of the forcing and the unique geometry of tidal scattering serve to focus the experiment design. The Hawaiian Ridge is selected as a study site. Strong interaction between the barotropic tide and the Ridge is known to take place. The goals of the Hawaiian Ocean Mixing Experiment (HOME) are to quantify the rate of tidal energy loss to mixing at the Ridge and to identify the mechanisms by which energy is lost and mixing generated. We are challenged to develop a sufficiently comprehensive picture that results can be generalized from Hawaii to the global ocean. To achieve these goals, investigators from five institutions have designed HOME, a program of historic data analysis, modeling and field observation. The Analysis and Modeling efforts support the design of the field experiments. As the program progresses, a global model of the barotropic (depth independent) tide, and two models of the baroclinic (depth varying) tide, all validated with near-Ridge data, will be applied, to reveal the mechanisms of tidal energy conversion along the Ridge, and allow spatial and temporal integration of the rate of conversion. Field experiments include a survey to identify "hot spots" of enhanced mixing and barotropic to baroclinic conversion, a Nearfield study identifying the dominant mechanisms responsible for topographic mixing, and a Farfield program which quantifies the barotropic energy flux convergence at the Ridge and the flux divergence associated with low mode baroclinic waves radiation. The difference is a measure of the tidal power available for mixing at the Ridge. Field work is planned from years 2000 through 2002, with analysis and modeling efforts extending through early 2006. If successful, HOME will yield an understanding of the dominant topographic mixing processes applicable throughout the global ocean. It will advance understanding of two central problems in ocean science, the maintenance of the abyssal stratification, and the dissipation of the tides. HOME data will be used to improve the parameterization of dissipation in models which presently assimilate TOPEX-POSEIDON observations. The improved understanding of the dynamics and spatial distribution of mixing processes will benefit future long-term programs such as CLIVAR.

Electroosmotic mixing in microchannels.

PubMed

Glasgow, Ian; Batton, John; Aubry, Nadine

2004-12-01

Mixing is an essential, yet challenging, process step for many Lab on a Chip (LOC) applications. This paper presents a method of mixing for microfluidic devices that relies upon electroosmotic flow. In physical tests and in computer simulations, we periodically vary the electric field with time to mix two aqueous solutions. Good mixing is shown to occur when the electroosmotic flow at the two inlets pulse out of phase, the Strouhal number is on the order of 1, and the pulse volumes are on the order of the intersection volume.

Quantifying Diapycnal Mixing in an Energetic Ocean

NASA Astrophysics Data System (ADS)

Ivey, Gregory N.; Bluteau, Cynthia E.; Jones, Nicole L.

2018-01-01

Turbulent diapycnal mixing controls global circulation and the distribution of tracers in the ocean. For turbulence in stratified shear flows, we introduce a new turbulent length scale Lρ dependent on χ. We show the flux Richardson number Rif is determined by the dimensionless ratio of three length scales: the Ozmidov scale LO, the Corrsin shear scale LS, and Lρ. This new model predicts that Rif varies from 0 to 0.5, which we test primarily against energetic field observations collected in 100 m of water on the Australian North West Shelf (NWS), in addition to laboratory observations. The field observations consisted of turbulence microstructure vertical profiles taken near moored temperature and velocity turbulence time series. Irrespective of the value of the gradient Richardson number Ri, both instruments yielded a median Rif=0.17, while the observed Rif ranged from 0.01 to 0.50, in agreement with the predicted range of Rif. Using a Prandtl mixing length model, we show that diapycnal mixing Kρ can be predicted from Lρ and the background vertical shear S. Using field and laboratory observations, we show that Lρ=0.3LE where LE is the Ellison length scale. The diapycnal diffusivity can thus be calculated from Kρ=0.09LES2. This prediction agrees very well with the diapycnal mixing estimates obtained from our moored turbulence instruments for observed diffusivities as large as 10-1 m2s-1. Moorings with relatively low sampling rates can thus provide long time series estimates of diapycnal mixing rates, significantly increasing the number of diapycnal mixing estimates in the ocean.

Reynolds number effects on mixing due to topological chaos.

PubMed

Smith, Spencer A; Warrier, Sangeeta

2016-03-01

Topological chaos has emerged as a powerful tool to investigate fluid mixing. While this theory can guarantee a lower bound on the stretching rate of certain material lines, it does not indicate what fraction of the fluid actually participates in this minimally mandated mixing. Indeed, the area in which effective mixing takes place depends on physical parameters such as the Reynolds number. To help clarify this dependency, we numerically simulate the effects of a batch stirring device on a 2D incompressible Newtonian fluid in the laminar regime. In particular, we calculate the finite time Lyapunov exponent (FTLE) field for three different stirring protocols, one topologically complex (pseudo-Anosov) and two simple (finite-order), over a range of viscosities. After extracting appropriate measures indicative of both the amount of mixing and the area of effective mixing from the FTLE field, we see a clearly defined Reynolds number range in which the relative efficacy of the pseudo-Anosov protocol over the finite-order protocols justifies the application of topological chaos. More unexpectedly, we see that while the measures of effective mixing area increase with increasing Reynolds number for the finite-order protocols, they actually exhibit non-monotonic behavior for the pseudo-Anosov protocol.

[Mixed methods research in public health: issues and illustration].

PubMed

Guével, Marie-Renée; Pommier, Jeanine

2012-01-01

For many years, researchers in a range of fields have combined quantitative and qualitative methods. However, the combined use of quantitative and qualitative methods has only recently been conceptualized and defined as mixed methods research. Some authors have described the emerging field as a third methodological tradition (in addition to the qualitative and quantitative traditions). Mixed methods research combines different perspectives and facilitates the study of complex interventions or programs, particularly in public health, an area where interdisciplinarity is critical. However, the existing literature is primarily in English. By contrast, the literature in French remains limited. The purpose of this paper is to present the emergence of mixed methods research for francophone public health specialists. A literature review was conducted to identify the main characteristics of mixed methods research. The results provide an overall picture of the mixed methods approach through its history, definitions, and applications, and highlight the tools developed to clarify the approach (typologies) and to implement it (integration of results and quality standards). The tools highlighted in the literature review are illustrated by a study conducted in France. Mixed methods research opens new possibilities for examining complex research questions and provides relevant and promising opportunities for addressing current public health issues in France.

Dark field photoelectron emission microscopy of micron scale few layer graphene

NASA Astrophysics Data System (ADS)

Barrett, N.; Conrad, E.; Winkler, K.; Krömker, B.

2012-08-01

We demonstrate dark field imaging in photoelectron emission microscopy (PEEM) of heterogeneous few layer graphene (FLG) furnace grown on SiC(000-1). Energy-filtered, threshold PEEM is used to locate distinct zones of FLG graphene. In each region, selected by a field aperture, the k-space information is imaged using appropriate transfer optics. By selecting the photoelectron intensity at a given wave vector and using the inverse transfer optics, dark field PEEM gives a spatial distribution of the angular photoelectron emission. In the results presented here, the wave vector coordinates of the Dirac cones characteristic of commensurate rotations of FLG on SiC(000-1) are selected providing a map of the commensurate rotations across the surface. This special type of contrast is therefore a method to map the spatial distribution of the local band structure and offers a new laboratory tool for the characterisation of technically relevant, microscopically structured matter.

Performance analysis of a microfluidic mixer based on high gradient magnetic separation principles

NASA Astrophysics Data System (ADS)

Liu, Mengyu; Han, Xiaotao; Cao, Quanliang; Li, Liang

2017-09-01

To achieve a rapid mixing between a water-based ferrofluid and DI water in a microfluidic environment, a magnetically actuated mixing system based on high gradient magnetic separation principles is proposed in this work. The microfluidic system consists of a T-shaped mirochannel and an array of integrated soft-magnetic elements at the sidewall of the channel. With the aid of an external magnetic bias field, these elements are magnetized to produce a magnetic volume force acting on the fluids containing magnetic nanoparticles, and then to induce additional flows for improving the mixing performance. The mixing process is numerically investigated through analyzing the concentration distribution of magnetic nanoparticles using a coupled particle-fluid transport model, and mixing performances under different parametrical conditions are investigated in detail. Numerical results show that a high mixing efficiency around 97.5% can be achieved within 2 s under an inlet flow rate of 1 mm s-1 and a relatively low magnetic bias field of 50 mT. Meanwhile, it has been found that there is an optimum number of magnetic elements used for obtaining the best mixing performance. These results show the potential of the proposed mixing method in lab-on-a-chip system and could be helpful in designing and optimizing system performance.

A Programmable and Configurable Mixed-Mode FPAA SoC

DTIC Science & Technology

2016-03-17

A Programmable and Configurable Mixed-Mode FPAA SoC Sahil Shah, Sihwan Kim, Farhan Adil, Jennifer Hasler, Suma George, Michelle Collins, Richard...Abstract: The authors present a Floating-Gate based, System-On-Chip large-scale Field- Programmable Analog Array IC that integrates divergent concepts...Floating-Gate, SoC, Command Word Classification This paper presents a Floating-Gate (FG) based, System- On-Chip (SoC) large-scale Field- Programmable

Pedagogical Strategies Used by Selected Leading Mixed Methodologists in Mixed Research Courses

ERIC Educational Resources Information Center

Frels, Rebecca K.; Onwuegbuzie, Anthony J.; Leech, Nancy L.; Collins, Kathleen M. T.

2014-01-01

The teaching of research methods is common across multiple fields in the social and educational sciences for establishing evidence-based practices and furthering the knowledge base through scholarship. Yet, specific to mixed methods, scant information exists as to how to approach teaching complex concepts for meaningful learning experiences. Thus,…

Evaluating Mixed Research Studies: A Mixed Methods Approach

ERIC Educational Resources Information Center

Leech, Nancy L.; Dellinger, Amy B.; Brannagan, Kim B.; Tanaka, Hideyuki

2010-01-01

The purpose of this article is to demonstrate application of a new framework, the validation framework (VF), to assist researchers in evaluating mixed research studies. Based on an earlier work by Dellinger and Leech, a description of the VF is delineated. Using the VF, three studies from education, health care, and counseling fields are…

A common soil handling technique can generate incorrect estimates of soil biota effects on plants

USDA-ARS?s Scientific Manuscript database

Several plant-soil biota (PSB) studies were recently published in high profile journals that used the suspect “mixed soil sampling” methodology. To explore the extent to which mixing field samples (i.e. employing mixed soil sample designs) can generate erroneous conclusions, we used real data to pa...

Triangulation, Respondent Validation, and Democratic Participation in Mixed Methods Research

ERIC Educational Resources Information Center

Torrance, Harry

2012-01-01

Over the past 10 years or so the "Field" of "Mixed Methods Research" (MMR) has increasingly been exerting itself as something separate, novel, and significant, with some advocates claiming paradigmatic status. Triangulation is an important component of mixed methods designs. Triangulation has its origins in attempts to validate research findings…

Center for the Built Environment: Research on Building Envelope Systems

Science.gov Websites

Studies Facade and Perimeter Zone Field Study Facades and Thermal Comfort Facade Symposium Mixed-Mode Research Adaptive Comfort Model Mixed-Mode Case Studies Operable Windows and Thermal Comfort Occupant thermal preferences in naturally ventilated as sealed buildings? Case Study Research of Mixed-Mode Office

Enhanced mixing in polyacrylamide gels containing embedded silica nanoparticles as internal electroosmotic pumps.

PubMed

Matos, Marvi A; White, Lee R; Tilton, Robert D

2008-02-15

Many biosensors, including those based on sensing agents immobilized inside hydrogels, suffer from slow response dynamics due to mass transfer limitations. Here we present an internal pumping strategy to promote convective mixing inside crosslinked polymer gels. This is envisioned as a potential tool to enhance biosensor response dynamics. The method is based on electroosmotic flows driven by non-uniform, oscillating electric fields applied across a polyacrylamide gel that has been doped with charged colloidal silica inclusions. Evidence for enhanced mixing was obtained from florescence recovery after photobleaching (FRAP) measurements with fluorescein tracer dyes dissolved in the gel. Mixing rates in silica-laden gels under the action of the applied electric fields were more than an order of magnitude faster than either diffusion or electrophoretically driven mixing in gels that did not contain silica. The mixing enhancement was due in comparable parts to the electroosmotic pumping and to the increase in gel swelling caused by the presence of the silica inclusions. The latter had the effect of increasing tracer mobility in the silica-laden gels.

Mixing Enhancement in a Lobed Injector

NASA Technical Reports Server (NTRS)

Smith, L. L.; Majamaki, A. J.; Lam, I. T.; Delabroy, O.; Karagozian, A. R.; Marble, F. E.; Smith, O. I.

1997-01-01

An experimental investigation of the non-reactive mixing processes associated with a lobed fuel injector in a coflowing air stream is presented. The lobed fuel injector is a device which generates streamwise vorticity, producing high strain rates which can enhance the mixing of reactants while delaying ignition in a controlled manner. The lobed injectors examined in the present study consist of two corrugated plates between which a fuel surrogate, CO2, is injected into coflowing air. Acetone is seeded in the CO2 supply as a fuel marker. Comparison of two alternative lobed injector geometries is made with a straight fuel injector to determine net differences in mixing and strain fields due to streamwise vorticity generation. Planar laser-induced fluorescence (PLIF) of the seeded acetone yields two-dimensional images of the scalar concentration field at various downstream locations, from which local mixing and scalar dissipation rates are computed. It is found that the lobed injector geometry can enhance molecular mixing and create a highly strained flowfield, and that the strain rates generated by scalar energy dissipation can potentially delay ignition in a reacting flowfield.

Numerical mixing calculations of confined reacting jet flows in a cylindrical duct

NASA Technical Reports Server (NTRS)

Oechsle, Victor L.; Holdeman, J. D.

1995-01-01

The results reported in this paper describe some of the main flow characteristics and NOx production results which develop in the mixing process in a constant cross-sectional cylindrical duct. A 3-dimensional numerical model has been used to predict the mixing flow field and NOx characteristics in a mixing section of an RQL combustor. Eighteen configurations have been analyzed in a circular geometry in a fully reacting environment simulating the operating condition of an actual RQL gas turbine combustion liner. The evaluation matrix was constructed by varying three parameter: (1) jet-to-mainstream momentum-flux ration (J), (2) orifice shape or orifice aspect ratio, and (3) slot slant angle. The results indicate that the mixing flow field and NOx production significantly vary with the value of the jet penetration and subsequently, slanting elongated slots generally improve the NOx production at high J conditions. Round orifices produce low NOx at low J due to the strong jet penetration. The NOx production trends do not correlate with the mixing non-uniformity parameters described herein.

Molecular fingerprinting of complex grass allergoids: size assessments reveal new insights in epitope repertoires and functional capacities.

PubMed

Starchenka, S; Bell, A J; Mwange, J; Skinner, M A; Heath, M D

2017-01-01

Subcutaneous allergen immunotherapy (SCIT) is a well-documented treatment for allergic disease which involves injections of native allergen or modified (allergoid) extracts. The use of allergoid vaccines is a growing sector of the allergy immunotherapy market, associated with shorter-course therapy. The aim of this study was the structural and immunological characterisation of group 1 (Lol p 1) IgG-binding epitopes within a complex mix grass allergoid formulation containing rye grass. HP-SEC was used to resolve a mix grass allergoid preparation of high molecular weight into several distinct fractions with defined molecular weight and elution profiles. Allergen verification of the HP-SEC allergoid fractions was confirmed by mass spectrometry analysis. IgE and IgG immunoreactivity of the allergoid preparations was explored and Lol p 1 specific IgG-binding epitopes mapped by SPOT synthesis technology (PepSpot™) with structural analysis based on a Lol p 1 homology model. Grass specific IgE reactivity of the mix grass modified extract (allergoid) was diminished in comparison with the mix grass native extract. A difference in IgG profiles was observed between an intact mix grass allergoid preparation and HP-SEC allergoid fractions, which indicated enhancement of accessible reactive IgG epitopes across size distribution profiles of the mix grass allergoid formulation. Detailed analysis of the epitope specificity showed retention of six Lol p 1 IgG-binding epitopes in the mix grass modified extract. The structural and immunological changes which take place following the grass allergen modification process was further unravelled revealing distinct IgG immunological profiles. All epitopes were mapped on the solvent exposed area of Lol p 1 homology model accessible for IgG binding. One of the epitopes was identified as an 'immunodominant' Lol p 1 IgG-binding epitope (62-IFKDGRGCGSCFEIK-76) and classified as a novel epitope. The results from this study support the concept that modification allows shorter-course therapy options as a result of providing an IgG epitope repertoire important for efficacy. Additionally, the work paves the way to help further develop methods for standardising allergoid platforms.

Mental Imagery-Based Training to Modify Mood and Cognitive Bias in Adolescents: Effects of Valence and Perspective.

PubMed

Burnett Heyes, S; Pictet, A; Mitchell, H; Raeder, S M; Lau, J Y F; Holmes, E A; Blackwell, S E

2017-01-01

Mental imagery has a powerful impact on emotion and cognitive processing in adults, and is implicated in emotional disorders. Research suggests the perspective adopted in mental imagery modulates its emotional impact. However, little is known about the impact of mental imagery in adolescence, despite adolescence being the key time for the onset of emotional dysfunction. We administered computerised positive versus mixed valence picture-word mental imagery training to male adolescent participants (N = 60, aged 11-16 years) across separate field and observer perspective sessions. Positive mood increased more following positive than mixed imagery; pleasantness ratings of ambiguous pictures increased following positive versus mixed imagery generated from field but not observer perspective; negative interpretation bias on a novel scrambled sentences task was smaller following positive than mixed imagery particularly when imagery was generated from field perspective. These findings suggest positive mental imagery generation alters mood and cognition in male adolescents, with the latter moderated by imagery perspective. Identifying key components of such training, such as imagery perspective, extends understanding of the relationship between mental imagery, mood, and cognition in adolescence.

Velocity Measurement in a Dual-Mode Supersonic Combustor using Particle Image Velocimetry

NASA Technical Reports Server (NTRS)

Goyne, C. P.; McDaniel, J. C.; Krauss, R. H.; Day, S. W.; Reubush, D. E. (Technical Monitor); McClinton, C. R. (Technical Monitor); Reubush, D. E.

2001-01-01

Temporally and spatially-resolved, two-component measurements of velocity in a supersonic hydrogen-air combustor are reported. The combustor had a single unswept ramp fuel injector and operated with an inlet Mach number of 2 and a flow total temperature approaching 1200 K. The experiment simulated the mixing and combustion processes of a dual-mode scramjet operating at a flight Mach number near 5. The velocity measurements were obtained by seeding the fuel with alumina particles and performing Particle Image Velocimetry on the mixing and combustion wake of the ramp injector. To assess the effects of combustion on the fuel air-mixing process, the distribution of time-averaged velocity and relative turbulence intensity was determined for the cases of fuel-air mixing and fuel-air reacting. Relative to the mixing case, the near field core velocity of the reacting fuel jet had a slower streamwise decay. In the far field, downstream of 4 to 6 ramp heights from the ramp base, the heat release of combustion resulted in decreased flow velocity and increased turbulence levels. The reacting measurements were also compared with a computational fluid dynamics solution of the flow field. Numerically predicted velocity magnitudes were higher than that measured and the jet penetration was lower.

Microfluidic active mixers employing ultra-high aspect-ratio rare-earth magnetic nano-composite polymer artificial cilia

NASA Astrophysics Data System (ADS)

Rahbar, Mona; Shannon, Lesley; Gray, Bonnie L.

2014-02-01

We present a new micromixer based on highly magnetic, flexible, high aspect-ratio, artificial cilia that are fabricated as individual micromixer elements or in arrays for improved mixing performance. These new cilia enable high efficiency, fast mixing in a microchamber, and are controlled by small electromagnetic fields. The artificial cilia are fabricated using a new micromolding process for nano-composite polymers. Cilia fibers with aspect-ratios as high as 8:0.13 demonstrate the fabrication technique's capability in creating ultra-high aspect-ratio microstructures. Cilia, which are realized in polydimethylsiloxane doped with rare-earth magnetic powder, are magnetized to produce permanent magnetic structures with bidirectional deflection capabilities, making them highly suitable as mixers controlled by electromagnetic fields. Due to the high magnetization level of the polarized nano-composite polymer, we are able to use miniature electromagnets providing relatively small magnetic fields of 1.1 to 7 mT to actuate the cilia microstructures over a very wide motion range. Mixing performances of a single cilium, as well as different arrays of multiple cilia ranging from 2 to 8 per reaction chamber, are characterized and compared with passive diffusion mixing performance. The mixer cilia are actuated at different amplitudes and frequencies to optimize mixing performance. We demonstrate that more than 85% of the total volume of the reaction chamber is fully mixed after 3.5 min using a single cilium mixer at 7 mT compared with only 20% of the total volume mixed with passive diffusion. The time to achieve over 85% mixing is further reduced to 70 s using an array of eight cilia microstructures. The novel microfabrication technique and use of rare-earth permanently-magnetizable nano-composite polymers in mixer applications has not been reported elsewhere by other researchers. We further demonstrate improved mixing over other cilia micromixers as enabled by the high aspect-ratio, high flexibility, and magnetic properties of our cilia micromixer elements.

Wave-mixing-induced transparency with zero phase shift in atomic vapors

NASA Astrophysics Data System (ADS)

Zhou, F.; Zhu, C. J.; Li, Y.

2017-12-01

We present a wave-mixing induced transparency that can lead to a hyper-Raman gain-clamping effect. This new type of transparency is originated from a dynamic gain cancellation effect in a multiphoton process where a highly efficient light field of new frequency is generated and amplified. We further show that this novel dynamic gain cancellation effect not only makes the medium transparent to a probe light field at appropriate frequency but also eliminates the probe field propagation phase shift. This gain-cancellation-based induced transparency holds for many potential applications on optical communication and may lead to effective suppression of parasitic Raman/hyper-Raman noise field generated in high intensity optical fiber transmissions.

Calculation of the flow field in supersonic mixed-compression inlets at angle of attack using the three-dimensional method of characteristics with discrete shock wave fitting

NASA Technical Reports Server (NTRS)

Vadyak, J.; Hoffman, J. D.

1978-01-01

The influence of molecular transport is included in the computation by treating viscous and thermal diffusion terms in the governing partial differential equations as correction terms in the method of characteristics scheme. The development of a production type computer program is reported which is capable of calculating the flow field in a variety of axisymmetric mixed-compression aircraft inlets. The results agreed well with those produced by the two-dimensional method characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results agree well with experimental data except in regions of high viscous interaction and boundary layer removal.

Generalized continuity equations from two-field Schrödinger Lagrangians

NASA Astrophysics Data System (ADS)

Spourdalakis, A. G. B.; Pappas, G.; Morfonios, C. Â. V.; Kalozoumis, P. A.; Diakonos, F. K.; Schmelcher, P.

2016-11-01

A variational scheme for the derivation of generalized, symmetry-induced continuity equations for Hermitian and non-Hermitian quantum mechanical systems is developed. We introduce a Lagrangian which involves two complex wave fields and whose global invariance under dilation and phase variations leads to a mixed continuity equation for the two fields. In combination with discrete spatial symmetries of the underlying Hamiltonian, the mixed continuity equation is shown to produce bilocal conservation laws for a single field. This leads to generalized conserved charges for vanishing boundary currents and to divergenceless bilocal currents for stationary states. The formalism reproduces the bilocal continuity equation obtained in the special case of P T -symmetric quantum mechanics and paraxial optics.

Dosimetry measurements using Timepix in mixed radiation fields induced by heavy ions; comparison with standard dosimetry methods

PubMed Central

Ploc, Ondrej; Kubancak, Jan; Sihver, Lembit; Uchihori, Yukio; Jakubek, Jan; Ambrozova, Iva; Molokanov, Alexander; Pinsky, Lawrence

2014-01-01

Objective of our research was to explore capabilities of Timepix for its use as a single dosemeter and LET spectrometer in mixed radiation fields created by heavy ions. We exposed it to radiation field (i) at heavy ion beams at HIMAC, Chiba, Japan, (ii) in the CERN's high-energy reference field (CERF) facility at Geneva, France/Switzerland, (iii) in the exposure room of the proton therapy laboratory at JINR, Dubna, Russia, and (iv) onboard aircraft. We compared the absolute values of dosimetric quantities obtained with Timepix and with other dosemeters and spectrometers like tissue-equivalent proportional counter (TEPC) Hawk, silicon detector Liulin, and track-etched detectors (TEDs).

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams.

PubMed

Alejo, A; Kar, S; Tebartz, A; Ahmed, H; Astbury, S; Carroll, D C; Ding, J; Doria, D; Higginson, A; McKenna, P; Neumann, N; Scott, G G; Wagner, F; Roth, M; Borghesi, M

2016-08-01

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

NASA Astrophysics Data System (ADS)

Alejo, A.; Kar, S.; Tebartz, A.; Ahmed, H.; Astbury, S.; Carroll, D. C.; Ding, J.; Doria, D.; Higginson, A.; McKenna, P.; Neumann, N.; Scott, G. G.; Wagner, F.; Roth, M.; Borghesi, M.

2016-08-01

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

Sexual differences in food preferences in the white stork: an experimental study

NASA Astrophysics Data System (ADS)

Kwieciński, Zbigniew; Rosin, Zuzanna M.; Dylewski, Łukasz; Skórka, Piotr

2017-06-01

Sex differences in the foraging ecology of monomorphic species are poorly understood, due to problems with gender identification in field studies. In the current study, we used experimental conditions to investigate the food preferences of the white stork Ciconia ciconia, an opportunistic species in terms of food, but characterised by a low level of sexual dimorphism. During a 10-day experiment, 29 individuals (20 females and 9 males) were studied by means of a `cafeteria test' in which the storks' diet consisted of mammals, birds, fish, amphibians, insects and earthworms. The storks preferred food characterised by high calorific and protein values such as mammals, birds and fish. Sexes differed strongly in their preferences; males preferred mammals, whereas females preferred birds. Moreover, females consumed insects and earthworms less often than males. Interestingly, males spent significantly less time foraging than females. We have demonstrated that the white stork exhibits clear sexual differences in food preferences which are mostly attributable to differences in parental duties, physiology and anatomy.

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

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

Alejo, A.; Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.

2016-08-15

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species.more » Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.« less

MAPS development for the ALICE ITS upgrade

NASA Astrophysics Data System (ADS)

Yang, P.; Aglieri, G.; Cavicchioli, C.; Chalmet, P. L.; Chanlek, N.; Collu, A.; Gao, C.; Hillemanns, H.; Junique, A.; Kofarago, M.; Keil, M.; Kugathasan, T.; Kim, D.; Kim, J.; Lattuca, A.; Marin Tobon, C. A.; Marras, D.; Mager, M.; Martinengo, P.; Mazza, G.; Mugnier, H.; Musa, L.; Puggioni, C.; Rousset, J.; Reidt, F.; Riedler, P.; Snoeys, W.; Siddhanta, S.; Usai, G.; van Hoorne, J. W.; Yi, J.

2015-03-01

Monolithic Active Pixel Sensors (MAPS) offer the possibility to build pixel detectors and tracking layers with high spatial resolution and low material budget in commercial CMOS processes. Significant progress has been made in the field of MAPS in recent years, and they are now considered for the upgrades of the LHC experiments. This contribution will focus on MAPS detectors developed for the ALICE Inner Tracking System (ITS) upgrade and manufactured in the TowerJazz 180 nm CMOS imaging sensor process on wafers with a high resistivity epitaxial layer. Several sensor chip prototypes have been developed and produced to optimise both charge collection and readout circuitry. The chips have been characterised using electrical measurements, radioactive sources and particle beams. The tests indicate that the sensors satisfy the ALICE requirements and first prototypes with the final size of 1.5 × 3 cm2 have been produced in the first half of 2014. This contribution summarises the characterisation measurements and presents first results from the full-scale chips.

The Optimization Design of An AC-Electroosmotic Micro mixer

NASA Astrophysics Data System (ADS)

Wang, Yangyang; Suh, Yongkweon; Kang, Sangmo

2007-11-01

We propose the optimization design of an AC-electroosmotic micro-mixer, which is composed of a channel and a series of pairs of electrodes attached on the bottom wall in zigzag patterns. The AC electric field is applied to the electrodes so that a fluid flow takes place around the electrodes across the channel, thus contributing to the mixing of the fluid within the channel. We have performed numerical simulations by using a commercial code (CFX 10) to optimize the shape and pattern of the electrodes via the concept of mixing index. It is found that the best combination of two kinds of electrodes, which leads to good mixing performance, is not simply harmonic one. When the length ratio of the two kinds of electrodes closes to 2:1, we can get the best mixing effect. Furthermore, we will visualize the flow pattern and measure the velocity field with a PTV technique to validate the numerical simulations. In addition, the mixing pattern will be visualized via the experiment.

Charged lepton mixing - an experimental overview

NASA Astrophysics Data System (ADS)

Rusu, Vadim

2015-04-01

Exploring the flavor sector of the Standard Model has always been a powerful probe in particle physics. Searches for charged leptons mixing, in particular muon decays, effectively pioneered this program almost 100 years ago. Still, even what one might consider, naively, simple questions, like why three lepton generations, are left unanswered. We do know now that neutral leptons (neutrinos) mix. We also know that, in all likelihood, the physics behind charged lepton mixing is also somehow responsible for generating neutrino masses. Not surprisingly, a revived interest in this field is currently under way, with experiments either ongoing or at planning stage throughout the world. The advent of powerful high intensity beams opens up new venues for exploration. Coupled with clever experimental ideas, sensitivities that were previously impossible to attain, are now within reach. I will review here the current status of charged lepton mixing experiments, what should we expect from the next generation projects and my view on how the field will progress in the future.

Design and simulation of the micromixer with chaotic advection in twisted microchannels.

PubMed

Jen, Chun-Ping; Wu, Chung-Yi; Lin, Yu-Cheng; Wu, Ching-Yi

2003-05-01

Chaotic mixers with twisted microchannels were designed and simulated numerically in the present study. The phenomenon whereby a simple Eulerian velocity field may generate a chaotic response in the distribution of a Lagrangian marker is termed chaotic advection. Dynamic system theory indicates that chaotic particle motion can occur when a velocity field is either two-dimensional and time-dependent, or three-dimensional. In the present study, micromixers with three-dimensional structures of the twisted microchannel were designed in order to induce chaotic mixing. In addition to the basic T-mixer, three types of micromixers with inclined, oblique and wavelike microchannels were investigated. In the design of each twisted microchannel, the angle of the channels' bottoms alternates in each subsection. When the fluids enter the twisted microchannels, the flow sways around the varying structures within the microchannels. The designs of the twisted microchannels provide a third degree of freedom to the flow field in the microchannel. Therefore, chaotic regimes that lead to chaotic mixing may arise. The numerical results indicate that mixing occurs in the main channel and progressively larger mixing lengths are required as the Peclet number increased. The swaying of the flow in the twisted microchannel causes chaotic advection. Among the four micromixer designs, the micromixer with the inclined channel most improved mixing. Furthermore, using the inclined mixer with six subsections yielded optimum performance, decreasing the mixing length by up to 31% from that of the basic T-mixer.

Rapid magnetic microfluidic mixer utilizing AC electromagnetic field.

PubMed

Wen, Chih-Yung; Yeh, Cheng-Peng; Tsai, Chien-Hsiung; Fu, Lung-Ming

2009-12-01

This paper presents a novel simple micromixer based on stable water suspensions of magnetic nanoparticles (i.e. ferrofluids). The micromixer chip is built using standard microfabrication and simple soft lithography, and the design can be incorporated as a subsystem into any chemical microreactor or a miniaturized biological sensor. An electromagnet driven by an AC power source is used to induce transient interactive flows between a ferrofluid and Rhodamine B. The alternative magnetic field causes the ferrofluid to expand significantly and uniformly toward Rhodamine B, associated with a great number of extremely fine fingering structures on the interface in the upstream and downstream regions of the microchannel. These pronounced fingering patterns, which have not been observed by other active mixing methods utilizing only magnetic force, increase the mixing interfacial length dramatically. Along with the dominant diffusion effects occurring around the circumferential regions of the fine finger structures, the mixing efficiency increases significantly. The miscible fingering instabilities are observed and applied in the microfluidics for the first time. This work is carried with a view to developing functionalized ferrofluids that can be used as sensitive pathogen detectors and the present experimental results demonstrate that the proposed micromixer has excellent mixing capabilities. The mixing efficiency can be as high as 95% within 2.0 s and a distance of 3.0 mm from the inlet of the mixing channel, when the applied peak magnetic field is higher than 29.2 Oe and frequency ranges from 45 to 300 Hz.

Weakening gravity on redshift-survey scales with kinetic matter mixing

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

D'Amico, Guido; Huang, Zhiqi; Mancarella, Michele

We explore general scalar-tensor models in the presence of a kinetic mixing between matter and the scalar field, which we call Kinetic Matter Mixing. In the frame where gravity is de-mixed from the scalar this is due to disformal couplings of matter species to the gravitational sector, with disformal coefficients that depend on the gradient of the scalar field. In the frame where matter is minimally coupled, it originates from the so-called beyond Horndeski quadratic Lagrangian. We extend the Effective Theory of Interacting Dark Energy by allowing disformal coupling coefficients to depend on the gradient of the scalar field asmore » well. In this very general approach, we derive the conditions to avoid ghost and gradient instabilities and we define Kinetic Matter Mixing independently of the frame metric used to described the action. We study its phenomenological consequences for a ΛCDM background evolution, first analytically on small scales. Then, we compute the matter power spectrum and the angular spectra of the CMB anisotropies and the CMB lensing potential, on all scales. We employ the public version of COOP, a numerical Einstein-Boltzmann solver that implements very general scalar-tensor modifications of gravity. Rather uniquely, Kinetic Matter Mixing weakens gravity on short scales, predicting a lower σ{sub 8} with respect to the ΛCDM case. We propose this as a possible solution to the tension between the CMB best-fit model and low-redshift observables.« less

Fuel combustion exhibiting low NO{sub x} and CO levels

DOEpatents

Keller, J.O.; Bramlette, T.T.; Barr, P.K.

1996-07-30

Method and apparatus are disclosed for safely combusting a fuel in such a manner that very low levels of NO{sub x} and CO are produced. The apparatus comprises an inlet line containing a fuel and an inlet line containing an oxidant. Coupled to the fuel line and to the oxidant line is a mixing means for thoroughly mixing the fuel and the oxidant without combusting them. Coupled to the mixing means is a means for injecting the mixed fuel and oxidant, in the form of a large-scale fluid dynamic structure, into a combustion region. Coupled to the combustion region is a means for producing a periodic flow field within the combustion region to mix the fuel and the oxidant with ambient gases in order to lower the temperature of combustion. The means for producing a periodic flow field can be a pulse combustor, a rotating band, or a rotating cylinder within an acoustic chamber positioned upstream or downstream of the region of combustion. The mixing means can be a one-way flapper valve; a rotating cylinder; a rotating band having slots that expose open ends of said fuel inlet line and said oxidant inlet line simultaneously; or a set of coaxial fuel annuli and oxidizer annuli. The means for producing a periodic flow field may or may not be in communication with an acoustic resonance. When employed, the acoustic resonance may be upstream or downstream of the region of combustion. 14 figs.

Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

PubMed

Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

2013-10-01

Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

Stereo Imaging Velocimetry of Mixing Driven by Buoyancy Induced Flow Fields

NASA Technical Reports Server (NTRS)

Duval, W. M. B.; Jacqmin, D.; Bomani, B. M.; Alexander, I. J.; Kassemi, M.; Batur, C.; Tryggvason, B. V.; Lyubimov, D. V.; Lyubimova, T. P.

2000-01-01

Mixing of two fluids generated by steady and particularly g-jitter acceleration is fundamental towards the understanding of transport phenomena in a microgravity environment. We propose to carry out flight and ground-based experiments to quantify flow fields due to g-jitter type of accelerations using Stereo Imaging Velocimetry (SIV), and measure the concentration field using laser fluorescence. The understanding of the effects of g-jitter on transport phenomena is of great practical interest to the microgravity community and impacts the design of experiments for the Space Shuttle as well as the International Space Station. The aim of our proposed research is to provide quantitative data to the community on the effects of g-jitter on flow fields due to mixing induced by buoyancy forces. The fundamental phenomenon of mixing occurs in a broad range of materials processing encompassing the growth of opto-electronic materials and semiconductors, (by directional freezing and physical vapor transport), to solution and protein crystal growth. In materials processing of these systems, crystal homogeneity, which is affected by the solutal field distribution, is one of the major issues. The understanding of fluid mixing driven by buoyancy forces, besides its importance as a topic in fundamental science, can contribute towards the understanding of how solutal fields behave under various body forces. The body forces of interest are steady acceleration and g-jitter acceleration as in a Space Shuttle environment or the International Space Station. Since control of the body force is important, the flight experiment will be carried out on a tunable microgravity vibration isolation mount, which will permit us to precisely input the desired forcing function to simulate a range of body forces. To that end, we propose to design a flight experiment that can only be carried out under microgravity conditions to fully exploit the effects of various body forces on fluid mixing. Recent flight experiments, by the P.I. through collaboration with the Canadian Space Agency (STS-85, August 1997), aimed at determining the stability of the interface between two miscible liquids inside an enclosure show that a long liquid column (5 cm) under microgravity isolation conditions can be stable, i.e. the interface remains sharp and vertical over a short time scale; thus transport occurs by molecular mass diffusion. On the other hand, when the two liquids were excited from a controlled vibration source (Microgravity Vibration Isolation Mount) two to four mode large amplitude quasi-stationary waves were observed. The data was limited to CCD recording of the dynamics of the interface between the two fluids. We propose to carry out flight experiments to quantify the dynamics of the flow field using Stereo Imaging Velocimetry and measure the concentration field using laser fluorescence. The results will serve as a basis to understand effects of g-jitter on transport phenomena, in this case mass diffusion. As the measurement of the kinematics of the flow field will shed light on the instability mechanism. The research will allow measurement of the flow field in microgravity environment to prove two hypotheses: (1) Maxwell's hypothesis: finite convection always exists in diffusing systems, and (2) Quasi-stationary waves inside a bounded enclosure in a microgravity environment is generated by Kelvin-Helmholtz instability; resonance of the interface which produces incipient mixing is due to Rayleigh-Taylor instability. The first hypothesis can be used as a benchmark experiment to illustrate diffusive mixing. The second hypothesis will lead to the understanding of g-jitter effects on buoyancy driven flow fields which occur in many situations involving materials processing, and other basic fluid physics phenomena. In addition, the second hypothesis will also provide insight in how Rayleigh-Taylor and Kelvin-Helmholtz instabilities propagate concentration fronts during mixing. Measurement of the flow field using SIV is important because it is the flow field which causes instability at the interface between the two fluids. Mixing driven by buoyancy induced flow fields will be addressed both experimentally and computationally. The experimental effort will address the kinematics of mixing: stretching, transport and chaos. Quantification of the mechanisms of mixing will consists of measuring the flow field using the SIV system at Glenn and capturing the dynamics of the interface, to measure mass transport, using a CCD camera. These experiments will be carried out within the framework of Earth's gravity and g-jitter microgravity acceleration as in a Space Shuttle environment or the International Space Station. The g-jitter will be induced and controlled using a tunable vibration isolation platform to isolate against vibration as well as input periodic and random vibration to the system. The parametric range of the microgravity experiment will be extended from the experiments on STS-85 to investigate higher mode quasi-stationary waves (8 to 12), as well as resonance regions which leads to chaos and turbulence. Ground-based experiments will focus on effects of vibration on stably stratified fluid layers in order to scale for possible scenarios in a microgravity environment. These vibrations will be subjected perpendicular to the concentration field on the ground since the parallel case can only be carried out in a microgravity environment. The concept of dynamical similarity will be applied to tune the experiments as closely as possible to a Space Shuttle environment or the International Space Station. The computational effort will take advantage of the Computational Laboratory at Glenn to corroborate the experimental findings with predictions of the dynamics of the flow field using the codes FLUENT (finite difference based) and FIDAP (finite element based). We will investigate two important cases, single-fluid model to address dilute systems with negligible jump in viscosity and the more general two-fluid model which accounts for finite jump in viscosity. Apart from its microgravity relevance, this experiment is well suited to study dynamics in nonlinear systems.

Tensor non-Gaussianity from axion-gauge-fields dynamics: parameter search

NASA Astrophysics Data System (ADS)

Agrawal, Aniket; Fujita, Tomohiro; Komatsu, Eiichiro

2018-06-01

We calculate the bispectrum of scale-invariant tensor modes sourced by spectator SU(2) gauge fields during inflation in a model containing a scalar inflaton, a pseudoscalar axion and SU(2) gauge fields. A large bispectrum is generated in this model at tree-level as the gauge fields contain a tensor degree of freedom, and its production is dominated by self-coupling of the gauge fields. This is a unique feature of non-Abelian gauge theory. The shape of the tensor bispectrum is approximately an equilateral shape for 3lesssim mQlesssim 4, where mQ is an effective dimensionless mass of the SU(2) field normalised by the Hubble expansion rate during inflation. The amplitude of non-Gaussianity of the tensor modes, characterised by the ratio Bh/P2h, is inversely proportional to the energy density fraction of the gauge field. This ratio can be much greater than unity, whereas the ratio from the vacuum fluctuation of the metric is of order unity. The bispectrum is effective at constraining large mQ regions of the parameter space, whereas the power spectrum constrains small mQ regions.

A multiproxy study between the Río de la Plata and the adjacent South-western Atlantic inner shelf to assess the sediment footprint of river vs. marineinfluence

NASA Astrophysics Data System (ADS)

Burone, Leticia; Ortega, Leonardo; Franco-Fraguas, Paula; Mahiques, Michel; García-Rodriguez, Felipe; Venturini, Natalia; Marin, Yamandú; Brugnoli, Ernesto; Nagai, Renata; Muniz, Pablo; Bícego, Marcia; Figueira, Rubens; Salaroli, Alexandre

2013-03-01

Proxies of terrigenous versus marine input (Al and Ti, Fe/Ca and Ti/Ca ratios), origin of organic matter (δ13C, δ15N and C/N ratio), productivity (Corg; Nt; CaCO3, P, Ca, and Ba content; and Ba/Al and Ba/Ti ratios), hydrodynamics (grain size, mean diameter and sorting) and biological records of the main features of the environment (benthic foraminifera assemblage distribution) were used to assess the sediment footprint of river vs. marine influence along the salinity gradient between the Rio de la Plata (RdlP) estuary and the adjacent South Western Atlantic Shelf. These criteria permitted characterisation and interpretation of the sedimentary processes influencing transition between three known environments: tidal river, estuarine and marine zones. Increases in sand and clay content at the transition between tidal river and proper estuarine zones indicate resuspension/deposition processes associated with the maximum turbidity zone (MTZ). The MTZ was also characterised by an increase in mixed organic matter content indicated by stable carbon and nitrogen isotope values, an increment in productivity proxies (Corg, Nt and CaCO3) and the substitution of the Miliammina fusca assemblage (brackish environments) for the Ammonia tepida assemblage (estuarine environments). The transition between estuarine and marine environments was characterised by a sharp (up to 99%) increase in sand content, reflecting the progradation of modern RdlP sediments toward relict continental shelf sediment. C/N values typical of the marine environment, decreased trace element concentrations and the distribution of the Buliminella elegantissima assemblage (a more marine assemblage) also highlight the marine environment. This paper is particularly important as a tool both to better understand sedimentological dynamics in salinity fronts (along the shelf sediment of large estuaries) and to elaborate more precise palaeoenvironmental and palaeoceanographic reconstructions.

Co-pyrolysis behaviour and kinetic of two typical solid wastes in China and characterisation of activated carbon prepared from pyrolytic char.

PubMed

Ma, Yuhui; Niu, Ruxuan; Wang, Xiaona; Wang, Qunhui; Wang, Xiaoqiang; Sun, Xiaohong

2014-11-01

This is the first study on the co-pyrolysis of spent substrate of Pleurotus ostreatus and coal tar pitch, and the activated carbon prepared from the pyrolytic char. Thermogravimetry (TG) analysis was carried out taking spent substrate, coal tar pitch and spent substrate-coal tar pitch mixture. The activation energies of pyrolysis reactions were obtained via the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. The kinetic models were determined by the master-plots method. The activated carbons were characterised by N2-adsorption, Fourier transform infrared spectroscopy and X-ray diffraction. Experimental results demonstrated a synergistic effect happened during co-pyrolysis, which was characterised by a decreased maximum decomposition rate and an enhanced char yield. The average activation energies of the pyrolysis reactions of spent substrate, coal tar pitch and the mixture were 115.94, 72.92 and 94.38 kJ mol(-1) for the Flynn-Wall-Ozawa method, and 112.17, 65.62 and 89.91 kJ mol(-1) for the Kissinger-Akahira-Sunose method. The reaction model functions were f(α) = (1-α)(3.42), (1-α)(1.72) and (1-α)(3.07) for spent substrate, coal tar pitch and the mixture, respectively. The mixture char-derived activated carbon had a Brunauer-Emmett-Teller surface area up to 1337 m(2) g(-1) and a total pore volume of 0.680 cm(3) g(-1). Mixing spent substrate with coal tar pitch led to the creation of more micropores and a higher surface area compared with the single spent substrate and coal tar pitch char. Also, the mixture char-derived activated carbon had a higher proportion of aromatic stacking. This study provides a reference for the utilisation of spent substrate and coal tar pitch via co-pyrolysis, and their pyrolytic char as a promising precursor of activated carbon. © The Author(s) 2014.

EMRP JRP MetNH3: Towards a Consistent Metrological Infrastructure for Ammonia Measurements in Ambient Air

NASA Astrophysics Data System (ADS)

Leuenberger, Daiana; Balslev-Harder, David; Braban, Christine F.; Ebert, Volker; Ferracci, Valerio; Gieseking, Bjoern; Hieta, Tuomas; Martin, Nicholas A.; Pascale, Céline; Pogány, Andrea; Tiebe, Carlo; Twigg, Marsailidh M.; Vaittinen, Olavi; van Wijk, Janneke; Wirtz, Klaus; Niederhauser, Bernhard

2016-04-01

Measuring ammonia in ambient air is a sensitive and priority issue due to its harmful effects on human health and ecosystems. In addition to its acidifying effect on natural waters and soils and to the additional nitrogen input to ecosystems, ammonia is an important precursor for secondary aerosol formation in the atmosphere. The European Directive 2001/81/EC on "National Emission Ceilings for Certain Atmospheric Pollutants (NEC)" regulates ammonia emissions in the member states. However, there is a lack of regulation regarding certified reference material (CRM), applicable analytical methods, measurement uncertainty, quality assurance and quality control (QC/QA) procedures as well as in the infrastructure to attain metrological traceability. As shown in a key comparison in 2007, there are even discrepancies between reference materials provided by European National Metrology Institutes (NMIs) at amount fraction levels up to three orders of magnitude higher than ambient air levels. MetNH3 (Metrology for ammonia in ambient air), a three-year project that started in June 2014 in the framework of the European Metrology Research Programme (EMRP), aims to reduce the gap between requirements set by the European emission regulations and state-of-the-art of analytical methods and reference materials. The overarching objective of the JRP is to achieve metrological traceability for ammonia measurements in ambient air from primary certified reference material CRM and instrumental standards to the field level. This requires the successful completion of the three main goals, which have been assigned to three technical work packages: To develop improved reference gas mixtures by static and dynamic gravimetric generation methods Realisation and characterisation of traceable preparative calibration standards (in pressurised cylinders as well as mobile generators) of ammonia amount fractions similar to those in ambient air based on existing methods for other reactive analytes. The aimed uncertainty is < 1 % for static mixtures at the 10 to 100 μmol/mol level, and < 3 % for portable dynamic generators in the 0 to 500 nmol/mol amount fraction range. Special emphasis is put on the minimisation of adsorption losses. To develop and characterise laser based optical spectrometric standards Evaluation and characterisation of the applicability of a newly developed open-path as well as of existing extractive measurement techniques as optical transfer standards according to metrological standards. To establish the transfer from high-accuracy standards to field applicable methods Employment of characterised exposure chambers as well as field sites for validation and comparison experiments to test and evaluate the performance of different instruments and measurement methods at ammonia amount fractions of the ambient air. The active exchange in workshops and inter-comparisons, publications in technical journals as well as presentations at relevant conferences and standardisation bodies will transfer the knowledge to stakeholders and end-users. The work has been carried out in the framework of the EMRP. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.

Application of a Novel Functional Gene Microarray to Probe the Functional Ecology of Ammonia Oxidation in Nitrifying Activated Sludge

PubMed Central

Short, Michael D.; Abell, Guy C. J.; Bodrossy, Levente; van den Akker, Ben

2013-01-01

We report on the first study trialling a newly-developed, functional gene microarray (FGA) for characterising bacterial and archaeal ammonia oxidisers in activated sludge. Mixed liquor (ML) and media biofilm samples from a full-scale integrated fixed-film activated sludge (IFAS) plant were analysed with the FGA to profile the diversity and relative abundance of ammonia-oxidising archaea and bacteria (AOA and AOB respectively). FGA analyses of AOA and AOB communities revealed ubiquitous distribution of AOA across all samples – an important finding for these newly-discovered and poorly characterised organisms. Results also revealed striking differences in the functional ecology of attached versus suspended communities within the IFAS reactor. Quantitative assessment of AOB and AOA functional gene abundance revealed a dominance of AOB in the ML and approximately equal distribution of AOA and AOB in the media-attached biofilm. Subsequent correlations of functional gene abundance data with key water quality parameters suggested an important functional role for media-attached AOB in particular for IFAS reactor nitrification performance and indicate possible functional redundancy in some IFAS ammonia oxidiser communities. Results from this investigation demonstrate the capacity of the FGA to resolve subtle ecological shifts in key microbial communities in nitrifying activated sludge and indicate its value as a tool for better understanding the linkages between the ecology and performance of these engineered systems. PMID:24155925

Characterisation, solubility and intrinsic dissolution behaviour of benzamide: dibenzyl sulfoxide cocrystal.

PubMed

Grossjohann, Christine; Eccles, Kevin S; Maguire, Anita R; Lawrence, Simon E; Tajber, Lidia; Corrigan, Owen I; Healy, Anne Marie

2012-01-17

This study examined the 1:1 cocrystal benzamide:dibenzyl sulfoxide, comprising the poorly water soluble dibenzyl sulfoxide (DBSO) and the more soluble benzamide (BA), to establish if this cocrystal shows advantages in terms of solubility and dissolution in comparison to its pure components and to a physical mixture. Solubility studies were performed by measuring DBSO solubility as a function of BA concentration, and a ternary phase diagram was constructed. Dissolution was examined through intrinsic dissolution studies. Solid-state characterisation was carried out by powder X-ray diffraction (PXRD), energy-dispersive X-ray diffraction (EDX), infra-red spectroscopy (ATR-FTIR) and thermal analysis. DBSO solubility was increased by means of complexation with BA. For the cocrystal, the solubility of both components was decreased in comparison to pure components. The cocrystal was identified as metastable and incongruently saturating. Dissolution studies revealed that dissolution of DBSO from the cocrystal was not enhanced in comparison to the pure compound or a physical mix, while BA release was retarded and followed square root of time kinetics. At the disk surface a layer of DBSO was found. The extent of complexation in solution can change the stability of the complex substantially. Incongruent solubility and dissolution behaviour of a cocrystal can result in no enhancement in the dissolution of the less soluble component and retardation of release of the more soluble component. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of pharmacogenetic traits in two distinct South African populations

PubMed Central

2011-01-01

Our knowledge of pharmacogenetic variability in diverse populations is scarce, especially in sub-Saharan Africa. To bridge this gap in knowledge, we characterised population frequencies of clinically relevant pharmacogenetic traits in two distinct South African population groups. We genotyped 211 tagging single nucleotide polymorphisms (tagSNPs) in 12 genes that influence antiretroviral drug disposition, in 176 South African individuals belonging to two distinct population groups residing in the Western Cape: the Xhosa (n = 109) and Cape Mixed Ancestry (CMA) (n = 67) groups. The minor allele frequencies (MAFs) of eight tagSNPs in six genes (those encoding the ATP binding cassette sub-family B, member 1 [ABCB1], four members of the cytochrome P450 family [CYP2A7P1, CYP2C18, CYP3A4, CYP3A5] and UDP-glucuronosyltransferase 1 [UGT1A1]) were significantly different between the Xhosa and CMA populations (Bonferroni p < 0.05). Twenty-seven haplotypes were inferred in four genes (CYP2C18, CYP3A4, the gene encoding solute carrier family 22 member 6 [SLC22A6] and UGT1A1) between the two South African populations. Characterising the Xhosa and CMA population frequencies of variant alleles important for drug transport and metabolism can help to establish the clinical relevance of pharmacogenetic testing in these populations. PMID:21712189

Potential of fluorescence spectroscopy for the characterisation of maple syrup flavours.

PubMed

Panneton, Bernard; Clément, Alain; Lagacé, Luc

2013-10-01

Maple syrup has high maket value. It is produced in North East America from the heat-evaporated sap of Acer saccharum Marshall. For marketing purposes, there is interest in defining its flavour profile in a consistent and repeatable manner. An experiment was undertaken to explore the potential of autofluorescence of maple syrup induced at 275 and 360 nm to characterise flavours. A mixed data factor analysis revealed two independent groups of variables. One represents early season woody and late season empyreumatic flavours. The other is related to off-flavour, confectionery and maple flavours. Maple and confectionery flavours are subtle, difficult to distinguish and opposed to off-flavour. There were clear relationships among the two groups and fluorescence profiles. For each of the five basic flavours, discriminant models based on partial least squares regressions were developed. For each sample of syrup, flavours combined to form flavour profiles, and the results from the five discriminant models were aggregated to reproduce these profiles. For excitation at 275 nm, the woody/off-flavour and confectionery/empyreumatic/maple flavour profiles were classified correctly 86 and 78% of the time (cross-validation) respectively. Induced autofluorescence spectra were shown to contain information related to maple syrup flavours. This fluorescence-flavour relationship is not considered quantitative yet, and further research avenues are proposed. © 2013 Society of Chemical Industry.

PAH body burden and biomarker responses in mussels (Mytilus edulis) exposed to produced water from a North Sea oil field: laboratory and field assessments.

PubMed

Sundt, Rolf C; Pampanin, Daniela M; Grung, Merete; Baršienė, Janina; Ruus, Anders

2011-07-01

In order to study the impact of produced water (PW) from a North Sea oil field on blue mussels (Mytilus edulis), chemical and biological markers were selected. A laboratory exposure (0.125%, 0.25% and 0.5% of PW) and a field study (6 stations 0.2-2 km from a PW discharge point) were conducted. In the laboratory study, PAH bioaccumulation increased in mussel soft tissue even at the lowest exposure dose. Micronuclei frequency demonstrated a dose-response pattern, whereas lysosomal membrane stability showed tendency towards a dose-response pattern. The same markers were assessed in the field study, biomarker analyses were consistent with the contamination level, as evaluated by mussel polycyclic aromatic hydrocarbons body burden. Overall, obtained results confirmed the value of an ecotoxicological approach for a scientifically sound characterisation of biological effects induced by offshore oilfield operational discharges. Copyright © 2011 Elsevier Ltd. All rights reserved.

Supernova brightening from chameleon-photon mixing

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

Burrage, C.

2008-02-15

Measurements of standard candles and measurements of standard rulers give an inconsistent picture of the history of the universe. This discrepancy can be explained if photon number is not conserved as computations of the luminosity distance must be modified. I show that photon number is not conserved when photons mix with chameleons in the presence of a magnetic field. The strong magnetic fields in a supernova mean that the probability of a photon converting into a chameleon in the interior of the supernova is high, this results in a large flux of chameleons at the surface of the supernova. Chameleonsmore » and photons also mix as a result of the intergalactic magnetic field. These two effects combined cause the image of the supernova to be brightened resulting in a model which fits both observations of standard candles and observations of standard rulers.« less

The operations of quantum logic gates with pure and mixed initial states.

PubMed

Chen, Jun-Liang; Li, Che-Ming; Hwang, Chi-Chuan; Ho, Yi-Hui

2011-04-07

The implementations of quantum logic gates realized by the rovibrational states of a C(12)O(16) molecule in the X((1)Σ(+)) electronic ground state are investigated. Optimal laser fields are obtained by using the modified multitarget optimal theory (MTOCT) which combines the maxima of the cost functional and the fidelity for state and quantum process. The projection operator technique together with modified MTOCT is used to get optimal laser fields. If initial states of the quantum gate are pure states, states at target time approach well to ideal target states. However, if the initial states are mixed states, the target states do not approach well to ideal ones. The process fidelity is introduced to investigate the reliability of the quantum gate operation driven by the optimal laser field. We found that the quantum gates operate reliably whether the initial states are pure or mixed.

Achieving nonlinear optical modulation via four-wave mixing in a four-level atomic system

NASA Astrophysics Data System (ADS)

Li, Hai-Chao; Ge, Guo-Qin; Zubairy, M. Suhail

2018-05-01

We propose an accessible scheme for implementing tunable nonlinear optical amplification and attenuation via a synergetic mechanism of four-wave mixing (FWM) and optical interference in a four-level ladder-type atomic system. By constructing a cyclic atom-field interaction, we show that two reverse FWM processes can coexist via optical transitions in different branches. In the suitable input-field conditions, strong interference effects between the input fields and the generated FWM fields can be induced and result in large amplification and deep attenuation of the output fields. Moreover, such an optical modulation from enhancement to suppression can be controlled by tuning the relative phase. The quantum system can be served as a switchable optical modulator with potential applications in quantum nonlinear optics.

Ground-water flow simulation and chemical and isotopic mixing equation analysis to determine source contributions to the Missouri River alluvial aquifer in the vicinity of the Independence, Missouri, well field

USGS Publications Warehouse

Kelly, Brian P.

2002-01-01

The city of Independence, Missouri, operates a well field in the Missouri River alluvial aquifer. Steady-state ground-water flow simulation, particle tracking, and the use of chemical and isotopic composition of river water, ground water, and well-field pumpage in a two-component mixing equation were used to determine the source contributions of induced inflow from the Missouri River and recharge to ground water from precipitation in well-field pumpage. Steady-state flow-budget analysis for the simulation-defined zone of contribution to the Independence well field indicates that 86.7 percent of well-field pumpage is from induced inflow from the river, and 6.7 percent is from ground-water recharge from precipitation. The 6.6 percent of flow from outside the simulation-defined zone of contribution is a measure of the uncertainty of the estimation, and occurs because model cells are too large to uniquely define the actual zone of contribution. Flow-budget calculations indicate that the largest source of water to most wells is the Missouri River. Particle-tracking techniques indicate that the Missouri River supplies 82.3 percent of the water to the Independence well field, ground-water recharge from precipitation supplies 9.7 percent, and flow from outside defined zones of contribution supplies 8.0 percent. Particle tracking was used to determine the relative amounts of source water to total well-field pumpage as a function of traveltime from the source. Well-field pumpage that traveled 1 year or less from the source was 8.8 percent, with 0.6 percent from the Missouri River, none from precipitation, and 8.2 percent between starting cells. Well-field pumpage that traveled 2 years or less from the source was 10.3 percent, with 1.8 percent from the Missouri River, 0.2 percent from precipitation, and 8.3 percent between starting cells. Well-field pumpage that traveled 5 years or less from the source was 36.5 percent, with 27.1 percent from the Missouri River, 1.1 percent from precipitation, and 8.3 percent between starting cells. Well-field pumpage that traveled 10 years or less from the source was 42.7 percent, with 32.6 percent from the Missouri River, 1.8 percent from precipitation, and 8.3 percent between starting cells. Well-field pumpage that traveled 25 years or less from the source was 71.9 percent, with 58.9 percent from the Missouri River, 4.7 percent from precipitation, and 8.3 percent between starting cells. Results of chemical (calcium, sodium, iron, and fluoride) and isotopic (oxygen and hydrogen) analyses of water samples collected from the Missouri River, selected monitoring wells around the Independence well field, and combined well-field pumpage were used in a two component mixing equation to estimate the relative amount of Missouri River water in total well-field pumpage. The relative amounts of induced inflow from the Missouri River in well-field pumpage ranged from 49 percent for sodium to 80 percent for calcium, and sensitivities ranged from 0 percent for iron to plus or minus 35 percent for naturally occurring stable isotope (18O). The average of all mixing equation results indicated that 61 percent of well-field pumpage was from induced inflow from the Missouri River. All methods used in the study indicate that more than one-half of the water in well-field pumpage was inflow from the Missouri River. River inflow estimates from ground-water simulation methods are larger and error values are smaller than those using chemical and isotopic data in the mixing equation, although substantial uncertainties exist for both estimation methods. Because of the complex hydrology of the aquifer near the Independence well field, the source estimates using particle tracking probably are the most reliable of the ground-water simulation methods. Mixing equation results are less reliable than those of the ground-water simulation for this study. However, more reliable results can be obtained from the mixing equatio

APPARENT CROSS-FIELD SUPERSLOW PROPAGATION OF MAGNETOHYDRODYNAMIC WAVES IN SOLAR PLASMAS

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

Kaneko, T.; Yokoyama, T.; Goossens, M.

2015-10-20

In this paper we show that the phase-mixing of continuum Alfvén waves and/or continuum slow waves in the magnetic structures of the solar atmosphere as, e.g., coronal arcades, can create the illusion of wave propagation across the magnetic field. This phenomenon could be erroneously interpreted as fast magnetosonic waves. The cross-field propagation due to the phase-mixing of continuum waves is apparent because there is no real propagation of energy across the magnetic surfaces. We investigate the continuous Alfvén and slow spectra in two-dimensional (2D) Cartesian equilibrium models with a purely poloidal magnetic field. We show that apparent superslow propagation acrossmore » the magnetic surfaces in solar coronal structures is a consequence of the existence of continuum Alfvén waves and continuum slow waves that naturally live on those structures and phase-mix as time evolves. The apparent cross-field phase velocity is related to the spatial variation of the local Alfvén/slow frequency across the magnetic surfaces and is slower than the Alfvén/sound velocities for typical coronal conditions. Understanding the nature of the apparent cross-field propagation is important for the correct analysis of numerical simulations and the correct interpretation of observations.« less

Characterisation of High Grazing Angle X-band Sea-clutter Doppler Spectra

DTIC Science & Technology

2013-08-01

0397 2 Background The ocean surface is a highly complex dynamical system and relating Doppler spectra to surface conditions is a difficult problem...1966] then extended this theory to water and classified it as a ‘slightly rough’ surface. He showed that the scattering elements of primary importance...incidence field. This is the definition for the Bragg water -wave propagation number defined in the spatial frequency domain as kw = 2k0 cos θ, where

Industry-Oriented Laboratory Development for Mixed-Signal IC Test Education

ERIC Educational Resources Information Center

Hu, J.; Haffner, M.; Yoder, S.; Scott, M.; Reehal, G.; Ismail, M.

2010-01-01

The semiconductor industry is lacking qualified integrated circuit (IC) test engineers to serve in the field of mixed-signal electronics. The absence of mixed-signal IC test education at the collegiate level is cited as one of the main sources for this problem. In response to this situation, the Department of Electrical and Computer Engineering at…

Application of pulsed-field gel electrophoresis to characterise and trace the prevalence of Enterobacter sakazakii in an infant formula processing facility.

PubMed

Mullane, N R; Whyte, P; Wall, P G; Quinn, T; Fanning, S

2007-05-01

Enterobacter sakazakii (E. sakazakii) contamination of powdered infant formula (PIF) and its processing environment was monitored between April 2005 and March 2006. The purpose of the monitoring programme was to locate points of contamination, investigate clonal persistence, and identify possible dissemination routes along the processing chain. A total of 80 E. sakazakii isolates were recovered from the manufacturing facility. The overall frequency of isolation of E. sakazakii in intermediate and final product was 2.5%, while specific locations in the processing environment were contaminated at frequencies up to 31%. All E. sakazakii isolates were characterised by pulsed-field gel electrophoresis (PFGE). XbaI macrorestriction digests yielded 19 unique pulse-types that could be grouped into 6 clusters of between 5 and 32 isolates. The formation of large clusters was consistent with the presence of a number of clones in the manufacturing environment. While the majority of isolates were of environmental origin (72.5%), no cluster was confined to one specific location and indistinguishable PFGE profiles were generated from isolates cultured from the manufacturing environment, sampling points along the processing chain and from intermediate and final product. These findings suggest that the manufacturing environment serves as a key route for sporadic contamination of PIF. These data will support the development of efficient intervention measures contributing to the reduction of E. sakazakii in the PIF processing chain.

Analog Module Architecture for Space-Qualified Field-Programmable Mixed-Signal Arrays

NASA Technical Reports Server (NTRS)

Edwards, R. Timothy; Strohbehn, Kim; Jaskulek, Steven E.; Katz, Richard

1999-01-01

Spacecraft require all manner of both digital and analog circuits. Onboard digital systems are constructed almost exclusively from field-programmable gate array (FPGA) circuits providing numerous advantages over discrete design including high integration density, high reliability, fast turn-around design cycle time, lower mass, volume, and power consumption, and lower parts acquisition and flight qualification costs. Analog and mixed-signal circuits perform tasks ranging from housekeeping to signal conditioning and processing. These circuits are painstakingly designed and built using discrete components due to a lack of options for field-programmability. FPAA (Field-Programmable Analog Array) and FPMA (Field-Programmable Mixed-signal Array) parts exist but not in radiation-tolerant technology and not necessarily in an architecture optimal for the design of analog circuits for spaceflight applications. This paper outlines an architecture proposed for an FPAA fabricated in an existing commercial digital CMOS process used to make radiation-tolerant antifuse-based FPGA devices. The primary concerns are the impact of the technology and the overall array architecture on the flexibility of programming, the bandwidth available for high-speed analog circuits, and the accuracy of the components for high-performance applications.